US2423427A - Deflagrating compositions - Google Patents

Description

Patented July 1, 1947 DEFLAGRATING COMPOSITIONS Russell Charrosin Payn, Watford, England, and Elwyn Jones, Ardrossan, and John Stocks Flanders, West Kilbride, Scotland, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing. Application May 4, 1944, Serial No. 534,148. In Great Britain December 23, 1942 Claims.

The present invention relates to the provision of new or improved non-detonating deflagrating explosive compositions of the kind based on a mixture of an alkali metal nitrate and a charred carbonaceous ingredient, with or without sulphur, and thus of the general character of blackpowder. In addition to the provision of the nondetonating defiagrating explosive compositions} dients, that will burn satisfactorily at speeds substantially lower than the burning speed of ordinary blackpowder. Nevertheless, it would frequently be desirable to produce such compositions, particularly for use in slow burning delay combustion train elements. Unless recourse is had to the employment of lightly carbonised wood charcoals of pale colour, which are not easy to reproduce, in place of the usual well carbonised dark charcoals, no great reduction in the burning speed of the blackpowder can be effected by variations in the relative proportions of potassium nitrate, charcoal and sulphur, including even the omission of the last mentioned ingredient; by substitution of sodium nitrate for potassium nitrate; or by substitution of one variety of charcoal for another. Moreover the handling of varying qualities of charcoal and the impracticability of maintaining a single ratio for the amounts of the predominating ingredients of the final powders constitute a substantial inconvenience in the manufacture of iuze powders of varying burning speeds, more especially since the mingling of these ingredients together is but the first step of a lengthy process of manufacture. Moreover, the reduced speed of combustion is frequently attained only at the expense of diminished vigour of combustion. The introduction of glyceride oils, waxes, natural resins and asphalts in the mill cake gives a slow fuze powder but also diminishes the vigour of combustion.

With the object of obtaining fuzes capable of burning steadily at barometric pressures substantially below 760 mm. of mercury, it has been proposed to include certain metallic oxides in substantial proportions (e. g. 10-33%%) in the composition of a blackpowder fuze composition containing potassium nitrate as its principal constituent. A few of these metallic oxides have the property of reducing the burning speed at ordinary pressure of the blackpowder fuze powder when they are introduced into its composition; and it is thus possible to produce a range of fuze powders burning at different speeds by incorporating varying amounts of such metallic oxides with a single stock composition of potassium nitrate, charcoal and sulphur. The range of burning speeds at ordinary atmospheric pressures obtained from even the most efiective of these metallic oxides, although wider than what can be obtained by using merely inert diluents is, howu ever, not noticeably wider than what can be attained by the more usual method of varying the composition, in the case of blackpowders containing well carbonised charcoals. Although it may enter to a certain extent into the reaction during the combustion of the blackpowder, the metallic oxide leaves a substantial residue of heat absorbent incombustibile inorganic material, and as small amounts of the metallic oxides have little effect on the burning speed of the blackpowder at ordinary barometric pressure, the quenching effect of the metallic oxide on the vigour of the combustion precludes the inclusion of sufiicient of the material to effect any great reduction in the burning speed.

We have now found that certain combustible organic nitrogen-containing compounds when included in the composition of a, non-detonating explosive of the kind described even in small proportions have a powerful efiect in reducing the speed of burning of the explosive, without sensibly diminishing the vigour of its combustion. It is therefore possible in many cases to obtain blackpowders of considerably .reduced speed of combustion without using proportions of alkali metal nitrate, charcoal and sulphur and without employing qualities of charcoal prejudicial to the vigour of the combustion, such as would be required to produce a blackpowder of the like burning speed in the absence of the organic nitrogen compound.

According to the present invention there is included in the composition of a non-detonating deflagrating explosive of the kind described, a proportion of, and perferably a minor proportion of, a compound of the kind obtained by condensation between an aldehyde and an amine. Especially suitable for the purpose of the invention are condensation products of primary amines with aldehydes: for instance those obtained from acetaldehyde and primary aromatic amines such as alphaor beta naphthylamine, or mixtures of these condensation products obtained by condensation of the mixed amines with aldehyde, in presence 01 an acid.

In putting the invention into effect the organic nitrogen containing compound or mixture of compounds may advantageously be introduced during the manufacture of the non-detonating deflagrating explosive at such a stage that it can be conveniently distributed throughout the composition of the individual granules composing it. It may, for instance, be introduced into the incorporating mill with the charge of alkali metal nitrate, charred carbonaceous ingredient and any sulphur used, or ball milled along with one or other of these ingredients previous to incorporation. Otherwise it may be introduced after the mill cake has been formed, the milling operation being continued until it has been well distributed before the cake is pressed and corned or mealed. It may also be introduced in solution in a volatile organic solvent that is subsequently evaporated off.

Substantial diminutions of the burning speed of the explosive are given by the inclusion of proportions of the order of 0.5 to 5 per cent. of the organic nitrogen compound without any noticeable reduction of th vigour of the combustion, but somewhat larger or smaller propor tions may be used if desired.

Slow burning blackpowders made in accordance with'the invention are especially useful in pelleted form for cartridges intended for the generation of gas pressure for industrial and other purposes in place of smokeless powder in forms of substantial web thickness, when their ash is not objectionable. Ordinary blackpowde-r frequently burns too rapidly to use as the gas pressure producing charge in cartridges 01' this kind, and smokless powder has the disadvantage that it is more costly to produce and that it does not, burn satisfactorily until a substantial pressure has already been built up. By means of the invention, moreover, fuze powders capable of burning satisfactorily at unusually low pressures may be obtained, so that the production of fuze powders for shells, bombs and the like is facilitated.

For the purposes of study and comparison of the burning speeds of fuze powders made in accordance with the invention, a testing method known as the lead fuze test may be used. In this test, lead tubes of specified size and weight are filled with the fuze powder to be tested and are sealed and drawn through dies until they have been reduced to a specified standard diameter. Measured lengths are then out from the middle portions of the filled and drawn tubes, and the speed of burning of these lengths is then measured at any desired pressure. Since the lead sheath is melted by the heat of combustion of the hue powder the gaseous combustion products are substantially unconfined and the burning takes place under the prevailing barometric pressure.

Although in other types of fuze the confinement or throttling of the gaseous combustion products may modify the effect of the barometric pressure on the burning speed as determined by the lead fuze test, this test is found in practice to permit satisfactory evaluation of the fuze powders.

The invention is further illustrated by the following Examples in which the parts are parts by weight.

Example 1 2 parts of a mixture of aldol-alpha-naphthylamine and aldol-beta-naphthylamine, made by treating a solution of one half mole of alphanaphthylamine and one half mole beta-naphthylamine in dilute hydrochloric acid solution (1 moles) with 1 moles acetaldehyde in a vessel under reflux without application of external heat, nearly neutralising, filtering and washing and drying th precipitate, ar milled with Parts Potassium nitrate 75 Alder charcoal of carbon content 17 Sulphur, in the incorporation stage 8 The cake is milled for 3 hours and pressed, corned, glazed and sieved in the usual way. The resulting blackpowder grain has a lead fuze speed of 250-300 seconds per yard at ordinary atmospheric pressure. A similar fuze powder made without any of the naphthylamine-acetaldehyde condensation product has a lead fuze speed of 80 to seconds per yard under a similar pressure. The resulting fuze powder may be pressed into a metal tube to serve as a bomb delay fuze.

Example 2 2 parts of the naphthylamine-acetaldehyde condensation product are milled as described in in Example 1 into a composition containing:

- Parts Potassium nitrate 64 Alder charcoal of 85% carbon content l2 Sulphur 24 The manufacture is continued as described in Example 1. The lead fuze speed is 400-450 seconds per yard as against about seconds per yard for a similarly made powder made without the addition of the naphthylamine-acetaldehyde condensation product. The product may be used for the same purpose as that of Example 1 to give a longer delay.

Example 3 The naphthylamine-acetaldehyde condensation product is the same as in the preceding examples. 3 parts of the dry material are milled into a composition containing:

Parts Potassium nitrate 70 Alder charcoal of 75% carbon content 30 duction in the burning speed of said composition.

2. The composition of claim 1 wherein the included ingredient is an acetaldehyde primary aromatic amine acid condensation product in an amount suflicient to cause a substantial reduction in the burning speed of said composition.

3. The composition of claim 1 wherein the included ingredient is an acetaldehyde isomeric naphthylamine acid condensation product in an amount suflicient to cause a substantial reduction in the burning speed of said composition.

4. The composition of claim 1 wherein the included ingredient is an acetaldehyde alpha and beta naphthylamine condensation product in an 15 Number amount sufiicient to cause a substantial reduction in the burning speed of said composition. 5. A fuze powder comprising a non-detonat-' 6 ing deflagrating modified blackpowder composition including a minor proportion of an aldehyde amine condensation product in an amount suificient to cause a substantial reduction in the 5 burning speed of said composition.

RUSSEHJL CHARROSIN PAYN. ELWYN JONES.

JOHN STOCKS FLANDERS.

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

UNITED STATES PATENTS Name Date 2,165,263 Holm July 11, 1939 2,072,720 Pearsall Mar. 2, 1937