US2439328A - Plastic detonating compositions - Google Patents

Description

April 6, 1948.

H. R. WRIGHT ETAL PLASTIC DETONATING COMPOSITIONS Filed March 22, 1945 INVENTORS R. W

HA RLD RIGHT and G. ALL/1N l, www

ramadan. .6, 194s.

" ulil'l'rrfzoI STATI-:1s PATENT olf-FICE l e y 2.439.328 l n PLASTIC DETONATING y(LT-)LilloSI'IIONS I Harold Reginald Wrlght, West Kilbrlde, and William Gordon Allan, Saltcoats, Scotland,` asl signor-s toy Imperial Chemical Industries Limite'd, a corporation of Great Britain Application March 22, 1945, Serial No. 584,258

In Great Britain June 2, 1944 8 Claims.. (Cl. 52-13) l 1 i '.Ihe present invention relates to the production of new or improved plastic or gelatinous detonating explosives for civil or military uses capable or retaining or easily recovering a serviceable con# i when exposed to low atmospheric.

ltemperatures.

.sistency even Plastic and gelatinous explosives-for civil use are based on the use of nitropolyglycerine or mixtures of nitroglycerine with other liquid esters as the self explosive ingredient rendering them sensitive todetonation,` an-d in most of them there i s also present a proportion 'of nitrocellulose gelatlnised by the liquid nitric ester.

The inclusion ofa proportion of other liquid nitric esters such as nitroglycol or nitroglycrine, and to a lesser extent the inclusion of a proportion of certain aromatic nitrocompounds with the nitroglycerine. has the effect of somewhat reducing the temperature to which a nitroglycerine explosive canloe supercooled before it freezes, and low freezing detonating explosives containing 2 e In U. S. -Patent 2,407,597 there are claimed plastic or gelatlnous detonating explosive com'- positions containing a high explosive solid` for example pentaerythrltol tetranitrate, distributed through a. matrix comprising nitrocellulose dissolved or gelatinised in a nitro body composition consisting of trinitrotoluene, tetryl and from 70 to 85 per cent byweight of a mixture of dinitroa proportion of other liquid nitric esters, .freiI quentlyaccompanied by a proportion of aromatic mtrocompounds, in conjunction with the nitroglycerine are in general use for civil blasting purposes. Liquid nitric ester vdetonating explosives are, however, frequently too sensitive to initiation by friction and shock for military purposes, even when they are in the unfrozen conditlons.-

We are aware that a plastic composition freezing with diillculty has already been disclosed,

characterised by the fact that the liquid constit- 4 uent is the mother lye remainingfrom the crys.- tallisation 0f a nitro derivative of xylol, cumol or a di or tri nitro derivative of benzol, said liquid constituent being gelatinised with nitrocellulose, in some' cases with the addition of nitroglycerine, to which mixture has been added finely pulverised oxygen-yielding or containing substances, such as chlorates, perchlorates. nitrates or the like, and in some cases combustible substances, until a toluene isomers, which mixture is wholly liou d at 0 C. The pentaerythritol tetranitrate is normally sensitive to initiation by friction andshock. as well as by a detonating impulse, whereas the matrix of nitrocellulose dissolved or gelatinised in the nitro body composition is'relatively insensitive to initiation by friction and shock.v The plastic or gelatinous explosives of the said pending application are resistant to low temperatures and are of sufficient sensitiveness to a detonating impulse. but of sufficiently low sensitiveness to initiation by friction or shock to enable them. to be used for military purposes,

It is however difficult to procure non-volatile liquid .aromatic poly-nitrocompound mixtures thatlwll enable the explosiveto'be stored under cold conditions without the occurrence of crystallisation of the nitrocompound to such an extent that the explosive loses its plastic or gelatinous'character and sets irreversibly hard in the sense that the nitro-compounds cannot again be liqufied Without heating the composition to a temperature considerably above atmospheric.

. We have now found it possible however to produce plastic or gelatinous detonating explosives capable of continued storage at low temperature Without setting ireversibly hard, wherein a self explosive crystalline solid lcompound of non-aromatic character is distributed through a condoughyplastic mass is obtained which, similarly to gelatinised dynamite, can be pressed into long tridges of desired length.

A We are also aware that a plastic explosive freezing with d'ilculty has been' disclosed comprising inter alla o; gelatine composed of nitrocellulose and a huid nitro-derivative of a higher homologue of toluene, for instance, a nitro-derivative of xylene` orcumenc, being afluid nitro compound of definite chemical constitution, or a plurality of such fluid derivatives, and if desired containplastic stringsI which may be cut to form cary l ing oxygen containing or yielding substances and n combustible (carbonaceous) materals.

tinuous matrix comprising compositions liquid at 15 C. making up the shaded portion of the triangular diagram for the multilizomponent sys tem of dinitration product of secondary butylbenzene, dinitro-tertiary butyl-benzene and dinitrocumene in the drawing accompanying the specification.

temperature of -15 C. and the shaded portion The triangular diagram has been plotted for a compositions in the unshaded portions howeverl are solid or partially solid at '-15 C.

In the diagram'. the .weight percentages of each 'i component are represented'by theperpendicular distances from each base to theI opposite vertex.

mixed with the dinitration product of secondary butyl-benzene in amounts up to about 8 times the weight of the latter, whereas the proportion of dinitro tertiary butyl-benzene in the mixture of dinitro-compounds may not exceed about 40%. The introduction of dinitro-cumene enables compositions containing less and less of the dinitration product of secondary butyl-benzene to be used as the proportion of dinitro-cumene is increased, so that a limited range of compositions free from the dinitration product of secondary butyl-benzene can even be employed.

A thickening agent oi' colloidal character is preferably present in the matrix in solution in the mixture of dinitro-compounds in .order to render it viscous or gelatinous and to assist in preventing exudation. Nitrocellulose or other cellulose esters or the like lmaybey used for this purpose. 1

Other solid undissolved ingredients usual in explosive compositions may be presentin addition to the aforesaid crystalline solid self explosive compound distributed through matrix but these should not include solid aromaticcompounds unless they are insoluble in the aforesaid dinitro-compounds or mixture 'of dinitrocompounds. For instance explosive salts such as ammonium nitrate, oxidisingv salts, porousv absorbents. flame quenching ingredients, oxidisable ingredients and the like may be included.

The non-aromatic crystalline solid self explosive compound distributed through the matrix may advantageously be a nitric ester. for example pentaerythritol tetranitrate or hexanitromannitol, or a nitramine. for example cyclotrimethylene-trinitramine.

By dinitro-cumene we mean the liquid mixture of isomers solidifying about n+8 C. that-may be quently 'observed until a number of preparations of the solid have been made in the same surroundings.

The dinitro-cumene, and the dinitration prod-' uct of secondary butyl-benzene or the dinitrotertiary butyl-benzene, or all three. may be separately produced from the corresponding aromatic hydrocarbons or from mono-nitration products of these, and then mixed; or the mono-nitration products may be prepared from the separate aromatic hydrocarbons and may be mixed and subjected to a further stage oi nitration. For the purpose of forming the mixture of di'nitration products, however, it is 'usually most convenient to subject a previouslyvformed mixture of the uri-nitrated aromatic hydrocarbons in the required proportions to dinitration. preferably in two stages as aforesaid. The mixed nitrating acid is preferably run into the mixture of mononitrated hydrocarbons, in order to minimise the amount of tri-nitration. It is then unnecessary to purify the mixture from tri-nitro-hydrocarbons. Mixtures consisting mainly of secondary and tertiary butyl-benzenes are available industrially, and fractions of suitable compositions for admixture with cumene, which is also an induslially available product. can be distilled from ese. l A method applicable to the production of dinitro-cumene that is also applicable to the production of the dinitration* producto! secondary butyl-benzene, or to mixtures of dinitro-cumene with the dinitration product of secondary butylbenzene or with dinit'ro-'tertiary butyl-benzene,

or with both, from the corresponding aromatic hydrocarbons orhydrocarbon mixture is as iollows:

The mono-nitrationisy conducted by adding gradually 0.9 part cumene (or 1 part of the butylbenzene) with stirring to 3 parts by weight of a mixed acid containing sulphuric acid, 25%

prepared from cumene by the conventional processes employed for the conversion of aromatichydrocarbons substantially wholly into their dinitro-derivatives by means of nitric and'sulphuric acids in association. The nitration is conveniently conducted in two stages, using a stronger acid mixture forthe conversion of the mono-nitrated hydrocarbon into the dlnitrated hydrocarbon than for the production of the mono-nitrated-hydrocarbon in order to minimise the amount of tri-nitration.

The di-nitration product of secondary butylbenzene may be similarly prepared from secondary butyl-benzene, and is aliquid at temperatures down to about 5 C., which depositsonly an unimportant percentage ot a solid when it is subjected to prolonged storage at .15 C. On further cooling to about 25 there is little further deposition of solid. The isomers'constituting the liquid mixture are new compounds in which both the nitro-groups are nuclearly positioned, but they have not yet been separated, enumerated and individually characterised by their constitutions. Dinitro tertiary butylbenzene, which may be prepared, similarly, is a solid melting at 62 C., and is generally understood to be a single compound. It has a tendency to supercool, anda lower melting point is frenitric acid and v20% water, originally warmed to about 30 C. The contents of the nitrating vessel are allowed to rise in temperature to about 40 C. during the addition ofthe mixed acid and thereafter to 50 C. at which temperature stirring is continued for half an hour. The mixture is-diluted with a small amount of water, and the yield of the mono-nitrated product is about 98% theoretical. The top layer lconsisting of the acidwet mono-nitratedproduct is placed ina ni-. trator. and warmed to about 40 C., thereupon twice its weight of a mixed acid of the composition sulphuric acid nitric acid 24% water 6% is gradually run 'into the nitrator with stirring. The temperature is allowed to rise during the addition, andl stirring continued at that tem- .perature for one anda half hours; The product is then separated and washed with a small amount of water, in which it sinks, and then with a faintly alkaline solution such as an alkaline carbonate or -sulphite to remove the last traces oi acid. It is then dried at raised temperature. advantageously by passing a current of air through it.

If desired, we can prepare the plastic or gelatnous detonating explosives of the lpresent invention according 'to the process claimed inv copending application Serial No. 549,639 which claims inter alia forming. a slurry of a finely crystalline high explosive compound sensitive to detonation byfriction or shockand nitrocellulose in a substantial quantityof cold water,l mixing into the said slurry at ordinary temperatures at least one substantially non-volatile and relaassassin tively sensitive to friction or -shock water insol- Example 1. 'Ihe resulting :explosive is likewise uble liquid solvent for nitrocellulose insuillcient to form a continuous phase but sumcient to agglomerate the nitrocellulose and crystals into discrete aggregates each containing the said nitrocellulose inV swollenv but'incompletely gelatinised condition4 associated with said solvent and a plurality oi' said crystals, separating thev still discrete aggregates from the bulk of .the coldV water without the application of any appreciable pressure, and drying the separated aggregates without causing any substantial coalescence thereof. e s

The following examples illustrate military explosives provided according to the invention:

"Example 1 The ingredients are as follows: Per cent Pentaerythritol tetranitrate-, -1- 66 f Dinitro-secondary butyl benzene r.. 30

Quarter second industrial nitrocellulose of 11.9% nitrogen content Blasting soluble nitrocellulose 0:4

The pentaerythritol tetranitrateA and the nitrocellulose used inthe water Wet condition and mixed together with half the dinitro-secondary butyl-benzene under water, the resulting granules being dried off in an oven and mixed with the other half of the dinitro-secondary butylbenzene in a McRoberts mixer. The plastic explosive has a power of about 84% that of blasting gelatine, a velocity of detonation oi '7000 metres per second and is capable of initiation by a No. 6 lead azide detonator. On storage at 15 C. it shows some change in consistency, but the nitrocompounds do not crystallise out. It becomes plastic again when further stored at a temperature of about 5 C.

Example 2 l The proportions of pentaerythritoi tetranitrate and nitrocellulose are -the same as in Example 1. In place of the dinitration product of secondary butyl-benzene there is used of a mixture of dinitro-secondary butyl-benzene and .dinitro-tertiary butyl-benzene in the ratio 75:25. The explosive is made in the manner described in Example 1 and has similar properties except that it can be stored without setting irreversibly hard at an even lower temperature than that described in Example 1.

Example 3 The ingredients are the same as in Example 1 except-that in the place of the dinitro-secondary butyl-benzene there is used 30% of a mixture of dinitro-secondary buty-l-benzene and dinitro-tertiary butyl-benzene in the ratio :55. The explosive is made in the manner described in Exevample 1, and has similar properties except that it cannot be stored at quite so low temperatures without setting irreversibly hard.

Notwithstanding the fact that these mixtures of dinitro-secondary butyl-benzene and dinitrotertiary butyl-benzene deposit some solid crystalline matter at temperatures above+10 C. this explosive does not go irreversibly hard when stored at 10 C. andrecovers its plastic consistency at a temperature below 0 C.

vExample 4 The ingredients are the same as in Example 1, except that the pentaerythritol tetranitrate is replaced by cyclotrimethylene-trinitramine; the process is otherwise the same as described in oi.' high power and velocity and is capable of initiation by a No. 6 lead azide detonator. On storage at 15 C. it shows some change in consis- Blasting soluble nitrocellulose is the product of nitratlon ot puriiied cotton cops by the pot process to a nitrogen content of 11.95 to 12.25%. The product is at least '95% soluble in an ether- `alcohol solution, and has a viscosity of 100 to 300 c. g. s.'in vsolution oi 3 gms. in 100 ml. acetone (95%) at 20 C.

The mixture containing the dinitro-cumene, the dinitro secondary butyl-benzene and the dinitro-tertiary butyl-benzene was obtained by nitratlon in two stages of a mixture of equal `weights ot cumene and a distillate amounting to of the amount of a commercially available mixture consisting mostlyof secondary and tertiary butyl-benzene, the ratio of the amounts of tertiary and secondary hydro-carbons in the distillate being 3:1.

The pentaerythritol tetranitrate and the nitro'cellulose were used in the water wet condition and were mixed together with half the dinitro aromatic hydrocarbon mixture under water, the resulting granules being dried ofiin an oven and mixed with the other half of the dinitro aromatic hydrocarbon mixture in a McRoberts mixer. The explosive had a power of about 86%` of that of blasting gelatine and a. velocity of detonaton of about 7,000 metres per second, and it was capable of initiation by a No. 6 lead azide detonator. On storage at 14 C. it showed some change in consistency, but the nitro compounds did not crystallise out and the explosive readily assumed its plastic condition when it was further stored at a temperature of about 0 C.

Example 6 The proportions of. pentaerythritol tetramtrane and of the nitrocellulose were the same as in Example 5. A mixture oi .dinitro-cumene and dinitro secondary butyl-benzene in the ratio 50:50 prepared by dinitration from a mixture of cumene and secondary butyl-benzene was used. The properties oi the explosive were not very different i'rom that of the explosive described in Example 5.

Example 7 A The proportions of pentaerythritol tetranitrate and of the `nitrocelluloses were the sameas in Example 6. A mixture of dinitro-cumene, dinitro secondary butyl-benzene and dinitro tertiary butyl-benzene in the ratio 90:5:5 was used, this mixture being prepared by nitratlon in two stages fromV a mixture of cumene, secondary butyl-benzene and tertiary butyl-benzene in these proportions. The method by which the ingredients of the explosive 'composition were mixed was the same as in Examples 5 and 6. The properties of the explosive were not very diierent from thoseA of the explosive prepared in Example 6.

Example 8 The proportions of pentaerythritol tetranitrate and of the nitrocelluloses were the same as in Example 6. A mixture of dinitro-cumene and dinitro tertiary butyl-benzene in the ratio 70:30 was used, this mixture being prepared by nitration in two stages from a. mixture of cumene and tertiary butyl benzene in these proportions. The method by which the ingredients of the explosive composition were mixed was the same as in Example 5. The properties of the explosives were not very different from those of the explosive prepared according to Example 5.

Example 9 i The ingredients are the same as in Example 5, "except that the pentaerythritol tetranitrate is replaced by cyclo-trimethylene-trinitramine. The process by which the explosive is made is otherwise the same as that described in Example 5. The resulting explosive is lik'ewise of high power and velocity and is capable of initiation by a Number 6 lead azide detonator. On storage at 14 it showed some change in consistency, but the aromatic nitro-compounds did not crystallise out, and the explosive readily resumed its plastic condition when it wasfurther stored at a. temperature of about C.

We claim: Y

1. Plastic detonating explosives capable o1 being stored continuously at low temperatures without setting irreversibiy hard which comprise a self-explosive solid compound from the group consisting of self-explosive non-aromatic crystalline solid 'nitric esters and cyclo-trimethylenetrinitramine distributed through a continuous matrix comprising a liquid which freezes below 15 C. and the composition of which is shown in the shaded portion of the triangular diagram for the multi-component system of dinitrocumene, dinitro tertiary-butylbenzene and the dinitration product 'of secondary-butylbenzene in the drawing accompanying the specication.

2. Plastic detonating explosives as dened in claim 1 wherein the self-explosive solid compound is pentaerythritol tetranitrate.

6. Plastic detonating explosives capable of being stored continuously at low temperatureswithout setting irreversibiy hard which comprise a self-explosive solid compound from the group consisting of self-explosive non-aromatic crystalline solid nitric esters and cyciotrimethyienetrinitramine distributedthrough a continuous matrix comprising the liquid mixture of nuclear dinitro compounds obtainable by direct dinitration of secondary-butylbenzene.

7. Plastic detonating explosives capable of being stored continuously at low temperatures without setting irreversibiy hard which comprise a self-explosive solid compound from the group consisting of self-explosive'non-aromatic crystalline solid nitric esters and cyclotrimethylenetrinitramine distributed through a continuous matrix comprising a. vliquid mixture of dinitro tertiary-butylbenzene and the dinitration product of secondary-butyibenzene, said liquid mixture freezing below 15 C. and containing at least 60% of the dinitration product of secondary-butylbenzene.

8. Plastic detonating explosives capable of being stored continuously at low temperatures without setting irreversibiy hard which comprise a self-explosive solid compound from the group consisting of self-explosive non-aromatic crystalline solid nitric esters and cyclotrimethylenetrinitramine distributed through a continuous matrix comprising a. liquid mixture of dinitrocumene and the dinitration product of secondary-butylbenzene. said liquid mixture freezing 3. Plastic detonating explosives as defined in A below 15 C. and containing at least 10% of the dinitration product of secondary-butylbenzene.

HAROLD REGINALD WRIGHT. WILLIAM GoaDoN ALLAN.

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

UNITED STATES PATENTS Number Name Date 1,867,285 Stettbacher July 12, 1932 2,083,143 Byers June 8, 1937 2,371,879 Davis Mar. 20, 1945 2,407,597 Wright Sept. 10, 1946 2,407,599 Williams Sept. 10, 1946 FOREIGN PATENTS Number Country Date 13,373 'Great Britain 1912 126,196 Great Britain May 1919

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