US2545270A - Gelatin blasting explosive composition containing water-soluble salts - Google Patents

Description

Patented Mar. 13, 1951 ifo FlcE GELATIN BLASTING EXPLOSIVE ooM- POSITION CONTAINING WATER=SOL= UBLE SALTS Stanley Fordham, Saltcoats, Scotland, and Ernest Gordon Cockbain, Blackley, Manchester, England. assignors to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing; Application July 18, 1946, Serial No. 684,552. In Great Britain July 26, 1945 V 4 Claims. I

The present invention relates to the production of new or improved blasting explosives of the kind comprising a preponderating proportion of freely water-soluble salts distributed through a lesser proportion of a viscous solution or jelly or nitrocellulose made with a solvent comprising at least one explosive liquid nitric ester, and is particularly applicable to the production of gelatine blasting explosives required to contain not less than 60 per cent of their weight of freely water-soluble salts, especially when other ingredients insoluble in the gelatinised nitrocellulose solvent are also to be included.

In order to minimise the cost of gelatine blasting explosives it is customary to include salts of explosive or oxidising character frequently in as sociation with oxidisable ingredients insoluble in theigelatinised nitrocellulose solvent, and the explosive or oxidising salts commonly employed are freely soluble in water, for instance ammonium nitrate, alkali nitrates or alkaline earth metal nitrates. In the manufacture of safety explosives it is necessary to minimise the proportion of explosive nitric ester, and this con- 'stituent is largely replaced by a self-explosive salt, which is usually ammonium nitrate, while there are also included ingredients of a flame quenching or cooling character. These, too, are frequently water-soluble salts.

It is to be expected that as the proportion of salts and other ingredients insoluble in the gelatinised nitrocellulose solvent can be increased only by decreasing the proportion of the gelatinisednitrocellulose solvent, explosive compositions containing a preponderating proportion of salts, with or without other undissolved ingredients, are liable to possess insufficient plas 2 ticity of the'explosive composition is thereby increased, and gelatine explosive containing a pre; ponderating proportion of water-soluble salts and other undissolved ingredients of increased plasticity or better flame-quenching characteristics may thereby be obtained, or the proportion of the liquid nitric ester in the composition may be ticity to enable them easily to be cartridged by extrusion, and may be so lacking in cohesiveness that they have not the character of a gelatine. I r Itis an object of the invention to provide gelatine blasting explosives of the kind described having improved plasticity, and it is a cognate object of the invention to enable the proportion of the gelatinised nitrocellulose solvent required to bind the undissolved ingredients of a gelatine blasting explosive as aforesaid to be reduced without rendering it incapable of cartridging by extI'lISlOIl.

. It has been proposed to include in a gelatinous orQsemi-gelatinous explosive a small proportion, preferably 2-6 per cent of a finely divided substantially non-carbonaceous plastic clay or claylike material as therein defined which, both alone and in, the form of a mixture with any carbonaceousingredients contained in the explosive, has a low'absorbency for nitroglycerine. The plasreduced. The use of clay is specially advantageous in the manufacture of safety explosives, since apart from its plasticising effect it has a pronounced flame-quenching or cooling effect, but the desensitising eifect of this diluent is greater than that of an equal weight of crystalline salts.

It has been found that the plasticity of blast ing explosives comprising a preponderating pro.- portion of freely water-soluble salts distributed in a lesser proportion of a viscous solution or jelly of nitrocellulose in a solvent comprising at least one explosive liquid nitric ester can even more effectively be improved by incorporating the water-soluble salts into the gelatinised nitrocellulose solvent in the presence of at least one ex plosive liquid nitric ester soluble compound of linear polythylene glycol ether structure having in its molecule a carbon chain or ring of at least eight carbon atoms joined together and at least two ethenoxy groups joined together, provided that free moisture is present when the salts are mixed in, said compound being capable of assisting emulsification in said explosive liquid nitric ester of a saturated aqueous solution of whichever freely water-soluble salt is to be present in the greatest volume.

In other words, the compound of linear polyethylene glycol ether structure is soluble in the explosive liquid nitric ester, has in its molecule a carbon chain or ring of at least eight carbon atoms joined together and at least two ethenoxy groups joined together, and is capable of assisting emulsification in said explosive liquid nitric ester of a saturated aqueous solution of whichever freely water-soIuble-salt is to be present in the greatest proportion by volume.

It is believed that there is a casual relationship between emulsifying properties of the aforesaid compounds and their beneficial effect onplas ticity of the explosivescontaining a preponderat ing proportion of freely water-soluble salts since the presence of moisture, although only in small amounts is necessary for this beneficial effect to be obtained, and many of the compounds that give it are soluble to a slight extent in the liquid nitric ester.

We have now found that the plasticity of blast+ ing explosives of the aforesaid kind can be likewise improved by incorporating the water-soluble salts into the gelatinised nitrocellulose solvent in the presence of at least one explosive liquid nitric ester soluble nitro derivative of anaryl or. lower alkaryl glyceryl or glycidyl mono-ether, in which the aryl group contains one or two nitro groups for a single ring compound, or between.

one and three nitro groups for a napthyl come salts are very dry and the water can only find its pound, provided that free moisture is present when the salts are mixed in, said compound being capable of assisting emulsiflcation in said explosive liquid nitric ester of a saturated aqueous solution of whichever freely water-soluble salt 5 is to be present in the greatest proportion by volume.

In other words, the nitro-aryl glyceryl or glycidal mono-ether used to carryout the method of the present invention is soluble in the explosive liquid nitric ester, has an aryl group contain-" ing one or, two nitro groups for a single ring compound or between one and three nitro groups for a naphthyl compound, with or without lower alkyl substitution in the aromatic portion, and iscapable of assisting emulsification in saideX plosive liquid nitric ester of a. saturated aqueous solution of whichever freel water-soluble salt is to be v present in the greatest proportion by volume. According to the present invention, therefore,

method of improving the plasticity of blasting explosives comprising a preponderating pro;

portion of freely Water-soluble salts distributed i a l p p io of a viscous solution or, jelly of liquid explosive nitric ester comprises incore porating the water-soluble salts into the gelatf inised nitrocellulose solvent, in the presence of iree moisture and of at least one ,"nitro-aryl lyceryl or glycidyl monoeether as herein. de-;

The suitability of the. compounds may readily be ascertained byshaking together a layer of the explosive liquid vnitric ester with a smaller layer of ,a saturated solution of theireely Water-soluble salt that is to be present inthe greatest volume proportion in the explosive composition, in pres,-

once of a small amount. of the compound and observing whether the breaking of emulsion is markedly delayed in comparison with that in a pontrol test carried out without the compound.

.OIlly very small proportions of the aforesaid compounds are required in the explosive composition to exert a substantially plasticising effect,

and the use of higher proportions than are necessary does not usually result in a correspondingly increased beneficial effect on the plasticity,

Hence the increased plasticity may beattained Without the introduction of sufiicient diluent ma terial to reduce the sensitiveness to. initiation of the explosive appreciably. The amount of the aforesaid nitro-aryl glyceryl or glycidyl mono ether is advantageously from about 0.02to about 3.5 per cent of the weight of the whole cornposi ion. V Vhile moisture must be present during the mixing of the water-solublesalts with the gelat inised nitrocellulose solvent, the amounts ordi-. narily associated with the freely water-soluble salts, which are frequently hygroscopic or dele iquescent compounds, for instance ammonium nitrate, and with the other ingredients, for in stance the explosive liquid nitric ester, are often sufilcient for the purpose. The moisture is most effective [or the purpose of the invention when it s associated with the surfaces of the crystals 'of the Water-soluble salt and in this case about to '0. 2 5 per cent on the weight of the explosive is ampl suflicient, but ifthe Water-soluble way into contact with their crystal surfaces as a result of-thcir being mixed into a moist jelly a somewhat higher proportion may be required. If

ural humidity content is not to be reckoned as free moisture. If the natural moistur content of the salts is insufiicient, as may be the case if they have been 'freshly dried, the necessary amount of water may be introduced, either by moistening at leastthe salt that is to be used in the greatest volume proportion before the salts are introduced into the gelatinised nitrocellulose jelly, or into the jelly.

) The aforesaid nitro-aryl glyceryl or glycidyl mono-ether may be introduced with the salts or the salt that is to be used in the greatest volume proportion; or into the nitrocellulose solvent before, after or during the gelatinisation of the nitrocellulose solvent by the nitrocellulose. i

' Owing to the increase in plasticity attainedac' cording to our invention it is possible to formulate explosive compositions capable of cartridg ing by extrusion that contain alower proportion of explosive liquid nitric ester and a higher pro portion of materials insoluble in the gelatinised nitrocellulose solvent that has hitherto been possible', and the production of inexpensive gelatine explosive compositions is thereby facilitated. k

The following example illustrates the production of an explosive of approximately the same plasticity as the following gelatine explosive, u chosen as the standard of plasticity and having Blasting soluble nitrocellulose is the product of nitration of purified cotton cops by the pot process to a nitrogen content of 11.95 to12.25 per cent. The product is at least per cent soluble in an ether-alcohol solution, and has a viscosity of to 300 c. g. s. units in solution of 3 gms. in 100 ml. acetone (95' per cent) at 20 C. The nitroglycerine is first mixed by hand with the woodmeal and the nitrocellulose, and the salts are later mixed into the resulting jelly containing the suspended Woodmeal in a McRoberts mixer for about half an hour. I

The resulting gelatine explosive can be car- .tridged easily by extrusion and nator such as a No. 6 lead azide or mercury fulv minate detonator.

. Example The ingredients are as follows:

Per cent Nitroglycerin (containing approximately 0.5

per cent moisture) 29.4 Blasting soluble nitrocellulose 0.8 Woodmeal (oven dried) 4.0 Para-nitrophenol glyceryl ether 0.4

Ammonium nitrate (0.1-0.5 per cent moisture) 41.4

moisture) The para-nitrophenol glyceryl ether is mixed by hand with the jelly formed from the nitroglycerine and the nitrocellulose containing the woodmeal in suspension. The moist salt are later mixed into the resulting jelly containing woodmeal in suspension in a McRoberts mixer for about half an hour. The resultin gelatine explosive is easily cartridged by extrusion and the cartridges are satisfactorily sensitive to commercial blasting detonators, for instance No. 6

lead azide or mercury fulminate detonators, both when freshly prepared and after storage for six months. The power of the explosive is slightly lower than that of the explosive containin 34.4 per cent nitroglycerine, and its density is approximately 1.5.

We claim:

1. A blasting explosive composition comprising 29.4 per cent nitroglycerin, 0.8 per cent nitrocellulose, 4.0 per cent oven dried wood meal, 41.4 per cent ammonium nitrate, 24.0 per cent sodium nitrate, 0.4 per cent para-nitrophenol glyceryl mono-ether, and moisture, said moisture being present as approximately 0.5 per cent of the weight of said nitroglycerin, 0.1 to 0.5 per cent of the weight of the ammonium nitrate and 0.1 per cent of the weight of the sodium nitrate.

2. A blasting explosive of improved plasticity comprising at least 60 per cent by weight of freely water-soluble inorganic nitrates distributed in a viscous solution of nitrocellulose and a liquid explosive nitric ester and including free moisture in an amount from 0.1 to 0.25 per cent by weight of a blasting explosive and from 0.2 to 0.5 per cent by weight of a nitro-aryl mono-ether selected from the group consistin of nitrophenyl and lower alkyl substituted nitrophenyl glyceryl and. glycidyl mono-ethers having from 1 to 2 nitro groups and nitronapthyl and lower alkyl substituted nitronapthyl glyceryl and glycidyl mono-ethers having from 1 to 3 nitro groups.

3. A blasting explosive of improved plasticity as set forth in claim 2 wherein the free moisture is associated with the surfaces of the crystals of the water soluble salts.

4. A blasting explosive of improved plasticity comprising at least by weight of water s01- uble explosive inorganic oxidizin salts, a less proportion of an explosive liquid nitric ester, a small amount of nitrocellulose dissolved therein, from 0.02 to 0.5% by weight of a nitro-aryl mono-ether selected from the group consisting of nitrophenyl and lower alkyl substituted nitrophenyl glyceryl and glycidyl mono-ethers having from 1 to 2 nitro groups and nitronapthyl and lower alkyl substituted nitronapthyl glyceryl and glycidyl mono-ethers having from 1 to 3 nitro groups, and from 0.1 to 0.25% by weight of the entire composition of free moisture.

STANLEY FORDHAM.

ERNEST GORDON COCKBAIN.

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

UNITED STATES PATENTS Number

Claims (1)

1. 2. A BLASTING EXPLOSIVE OF IMPROVED PLASTICITY COMPRISING AT LEAST 60 PER CENT BY WEIGHT OF FREELY WATER-SOLUBLE INORGANIC NITRATES DISTRIBUTED IN A VISCOUS SOLUTION OF NITROCELLULOSE AND A LIQUID EXPLOSIVE NITRIC ESTER AND INCLUDING FREE MOISTURE IN AN AMOUNT FROM 0.1 TO 0.25 PER CENT BY WEIGHT OF A BLASTING EXPLOSIVE AND FROM 0.2 TO 0.5 PER CENT BY WEIGHT OF A NITRO-ARYL MONO-ETHER SELECTED FROM THE GROUP CONSISTING OF NITROPHENYL AND LOWER ALKYL SUBSTITUTED NITROPHENYL GLYCERYL AND GLYCIDYL MONO-ETHERS HAVING FROM 1 TO 2 NITRO GROUPS AND NITRONAPTHYL AND LOWER ALKYL SUBSTITUTED NITRONAPTHYL GLYCERYL AND GLYCIDYL MONO-ETHERS HAVING FROM 1 TO 3 NITRO GROUPS.