US2430274A - Explosive composition - Google Patents

Description

Patented Nov. 4, 1947 EXPLOSIV E COMPOSITION Robert W. Cairns, Wilmington, Del., assignor to Hercules Powder Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application December 31, 1943, Serial No. 516,508

8 Claims.

This invention relates to a new explosive composition and more particularly to a colloided nitrostarch-trinitrotoluene explosive.

Heretofore, attempts to produce an economical explosive consisting of readily available raw materials and having properties comparable with trinitrotoluene have not been successful. For example, mixtures of trinitrotoluene and ammonium nitrate have been used. However, these mixtures are hygroscopic, form unstable compounds with copper and are more insensitive to explosion by initiators than trinitrotoluene. Nitrostarch having the advantages of low cost and ample supply of raw materials has been tried with various stabilizing agents. Thus, binding oils, sodium nitrate, ammonium nitrate, barium nitrate, and other materials have been added to nitrostarch in attempts to produce an explosive having stability and explosive qualities comparable with trinitrotoluene. Mixtures of nitrostarch, trinitrotoluene and one or more other substances have been made. While all of these mixtures had certain explosive properties, none was found to be a suitable replacement for trinitrotoluene having the advantages of relative safety in manufacture transportation, of not being hygroscopic, of not forming unstable compounds with metals, and of not being too insensitive to explosion by initiators.

Now, in accordance with the present invention, it has been found that by heating mixtures of nitrostarch and solid trinitrotoluene above the melting point of trinitrotoluene, the resulting colloided nitrostarch-trinitrotoluene explosive has properties comparable with pure trinitrotoluene.

Nitrostarch is a great deal more sensitive than trinitrotoluene, but the difficulty of handling nitrostarch because of its powdery nature and ready flammability may be overcome by wetting it with a wetting liquid. It has been found that the damp nitrostarch can be mixed mechanically with granular trinitrotoluene and that the mixture may be dried in air, removing the wetting liquid. The mixture may then be heated as high as 100 C. without danger, melting the trinitrotoluene and allowing colloidization of the nitrostarch to take place. A tacky, viscous liquid is produced, which on cooling solidifies to a very fine grained material, having explosive and stability qualities comparable with trinitrotoluene.

As an illustration of a nitrostarch-trinitrotoluene explosive mixture, the following examples are given:

Example 1 8.5 parts by weight of nitrostarch were thordesirable results.

2 oughly mixed with 1.5 parts of ethyl alcohol.

The alcohol-wet nitrostarch was then mixed with 10 parts of dry trinitrotoluene; Stirring was carried out in a hard rubber vessel using a stirrer of the same material. When mixing was complete, the product was removed from the vessel and allowed to dry at room temperature. During the drying period, the alcohol evaporated. The dried mixture was then heated in the range of from -95 C. until the trinitrotoluene melted. The liquid trinitrotoluene colloided the nitrostarch, yielding a transparent, brown, tacky liquid. This material was poured into molds and upon cooling yielded a very fine grained homogeneous material.

Example 2 7.3 parts by weight of nitrostarch were mixed with 2.7 parts of ethyl alcohol. The alcohol-wet nitrostarch was then mixed with 10 parts of trinitrotoluene in 40 parts of acetone. The solution of trinitro-toluene and nitrostarch in acetone was poured after thorough mixing into water with resultant co-precipitation of the two solids. The precipitate was filtered off, allowed to dry in air at room temperature. The dried mixture was heated from 80 to C. until the trinitrotoluene melted and the fluid material was then cast into molds and allowed to cool.

While ethyl alcohol and acetone have been used as wetting liquids in the above examples, water, benzene, V alcohol-acetone, ether, ether-alcohol, ether-alcohol-acetone have also been successfully employed. Trinitrotoluene may be either mixed dry or wetted with one or more of the above liquids before mixing with the damp nitrostarch.

While the composition may be varied in a wide range, mixtures containing from about 20% to about 60%, and preferably from about 41% to 46%, of nitrostarch based upon the weight of the dry mixture have been found to give the most The damp nitrostarch may contain from about 15% to about 40% by weight of wetting liquid. The temperature range employed in colloiding the nitrostarch was from the lowest temperature which would melt the trinitrotoluene to about C. which is a temperature range of from about 76 to about 100 C. for most grades of trinitrotoluene.

In comparison of the trinitrotoluene-nitrostarch explosive with pure trinitrotoluene, tests were carried out to determine the sensitiveness to impact. The test constituted allowing a weight to fall on a small sample of the material from varying heights. The less sensitive the explosive the greater the height from which the weight would have to be dropped before the sample would explode. The trinitrotoluene-nitrostarch colloid compared. favorably in sensitivity with the samples of pure trinitrotoluene tested.

The rate of detonation of cast nitrostarchtrinitrotoluene .colloid was compared with that of cast trinitrotoluene. Cylindrical sticks of each were prepared and shot with a high velocity blasting gelatin as a primer. The detonation velocity was determined photographically. The

rate of detonation for pure cast trinitrotoluene was about 6910 meters per second and that of the nitrostarch-trinitrotoluene colloid was about 6560 meters per second, 7

To obtain further comparison of the ease of detonation of cast trinitrotoluene and trinitrotoluene-nitrostarch mixtures, sand tests were carried out. A small blasting cap shell was used to hold the cast material which was detonated with a primer. It was found that the nitrostarchtrinitrotoluene mixture crushed up to 93% as much sand as a like amount of pure trinitrotoluene.

' From the above tests, it will be seen that the colloided nitrostarch and trinitrotoluene have explosive vand sensitivity qualities comparable with those of pure trinitrotoluene and, therefore, can be used in bombs, mines and shells. Thus, the present invention has described a new and useful explosive composition comprising a colloided nitrostarch-trinitrotoluene formed by melting trinitrotoluene in the presence of nitrostarch.

What I claim and desire to protect by Letters Patent is: a

1. A detonating explosive composition consisting of a colloided nitrostarch-trinitrotoluene mixture comprising trinitrotoluene and from about 20%.to about 60% of nitrostarch, said percentages based'upon the weight of the dry mixture. 2. A detonating explosive composition consisting of a colloided nitrostarch-trinitrotoluene mixture comprising trinitrotoluene and from about 41% to about'46% of nitrostarch, said percentages based upon the weight of the dry mixture.

3. A method for making a detonating explosive composition comprisingmixing nitrostarch with a volatile liquid, and adding trinitrotoluene, drying the resulting mixture'to remove the liquid, heating within the range from the melting point of trinitrotoluene to about 100 C. to colloid the nitrostarch, and subsequently cooling the colloided nitrostarch trinitrotoluene mixture, said 4 nitrostarch comprising from about 20% to about of the dry material.

4. A method for making a colloided explosive composition comprising mixing about 8.5 parts of nitrostarch with about 1.5 parts of ethyl alcohol and about 10 parts of trinitrotoluene, drying, heating at a temperature of from about C, to about C. until all the trinitrotoluene has melted, and cooling.

5. A method for making a colloided explosive composition comprising mixing about 7.3 parts of nitrostarch with about 2.7 parts of ethyl alcohol, about 10 parts of trinitrotoluene, and about 40 parts of acetone, pouring the mixture into water, filtering and drying the resulting precipitate, then heating to a, temperature of from about 80 C; to about 95 C. until all the trinitrotoluene has melted, and cooling.

6. A colloided explosive composition consisting of about 8.5 parts of nitrostarch and about 10 parts of trinitrotoluene.-

7. A colloided explosive composition consisting of about 7.3 parts of nitrostarch and about 10 parts of trinitrotoluene.

8;" A method for making a detonating explosive composition comprising mixing nitrostarch with ethyl alcohol and adding trinitrotoluene, drying the resulting mixture to remove the ethyl alcohol, heatin within the range from the melting point of trinitrotoluene to about C. to colloid the nitrostarch and subsequently cooling the nitrostarch-trinitrotoluene mixture, said nitrostarch comprising from about 20% to about 60% of the dry material, r ROBERT W. CAIRNS.

REFERENCES CITED 0 The following references are of record in the meet this patent:

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