US3690970A - Propellant powders containing nitrocellulose,stabilized with certain aldehydes - Google Patents

Abstract

A SINGLE OR MULTIPLE-BASE PROPELLANT POWDER HAVING IMPROVED BALLISTIC, MECHANICAL AND CHEMICAL PROPERTIES WHICH COMPRISES A NITROCELLULOSE OR NITROGLYCERIN BASE POWDER AND AN EFFECTIVE AMOUNT OF AN ALIPHATIC OR AROMATIC ALDEHYDE.

Description

United States Patent Oifice US. Cl. 149-2 7 Claims ABSTRACT OF THE DISCLOSURE A single or multiple-base propellant powder having improved ballistic, mechanical and chemical properties which comprises a nitrocellulose or nitroglycerin base powder and an effective amount of an aliphatic or aromatic aldehyde.

BACKGROUND OF THE INVENTION The present invention relates to single or multiple-base propellant powders distinguishable over conventional propellant powders by an improved efliciency and stability, said propellant powders also yielding higher initial velocities with the gas pressures being increased only to a minor extent, or not at all. The propellant powders of the present invention further exhibit desirable burning properties and also possess improved properties from a chemical as well as from a ballistic point of view.

Among propellant powders, a distinction is made, as is well known in the art, between single-base powders substantially containing nitrocellulose, double-base powders containing, in addition to nitrocellulose, a further active component as the energy carrier, for example nitration products of polyvalent alcohols, such as nitroglycerin or diethylene glycol dinitrate (DEGB), and the triple-based powders which contain still a third component, which in most cases is a nitro compound. In these propellant powders a controlled deflagration takes place during ignition, with gasses being liberated which drive the projectile through the barrel of the firearm and out of the firearm and impart to the projectile, at the muzzle of the barrel, a specific initial velocity.

The propellant powders are commercially available in the form of strip-shaped powders as well as in the form of spherical-grain powders. The strip-shaped powders are plasticized with the use of either water or solvents, shaped by extruding, for example, by means of a press, and then the solvent or water is removed. In contrast thereto, the spherical-grain powders are produced with the use of a very large quantity of water, which has the advantage of a larger safety margin as compared with the stripshaped powders produced with solvents. The sphericalgrain powders generally exhibit a very high bulk density and accordingly are very well suited for firearms with high efliciency (power) with a powder charge chamber which is very small.

An essential procedure during the removal of solvents and water from propellant powders resides in a simultaneous hardening of the powder surface. Moreover, it is likewise conventional to add stabilizers, such as diphenylamine, to the propellant powders during the plasticizing step, in order to bind the nitric oxides and the nitrous acid produced during the decomposition of the degradation products of nitrocellulose, and to prevent a catalytic decomposition of the powders. Furthermore, most propellant powders are subjected to a post-treatment, because of their sensitivity with respect to friction, and are also exposed to a surface treatment, for example, a treatment 3,690,970 Patented Sept. 12, 1972 with alkylaryl urea derivatives, urethanes, phthalates, and the like, said compounds compressing and smoothing the surface of the powders.

SUMMARY OF THE INVENTION An object of the present invention is to avoid the prior art disadvantages of propellant powders.

Another object of the present invention is to provide an gniprovcd propellant having improved efficiency and sta- 1 ity.

A further object of the present invention is to provide a hardened single or multiple-base propellant powder possessing improved ballistic properties, including an increased efficiency, an improved stability and a favorable burning velocity.

Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Pursuant to the present invention, it has been found that the above-mentioned disadvantages may be eliminated and a much improved single or multiple-base propellant powder having improved ballistic properties such as efficiency, stability and burning velocity, may be obtained by treating said single or multiple-base propellant powders with aldehydes during or after their production.

Suitable aldehydes which can be used in the present invention include the aliphatic as well as the aromatic aldehydes with the aliphatic aldehydes and particularly formaldehyde being generally preferred. Exemplary of some of the aldehydes which can be used in the present invention include acetaldehyde, pivalaldehyde, propionaldehyde, butyraldehyde, adipaldehyde, benzaldehyde, methylbutyraldehyde and the like. Of course, as stated above, formaldehyde is generally preferred.

The aldehyde can be added to the crude powder mass by mixing the aldehyde, prior to shaping, with an aqueous solution of the aldehyde in a mixing device, such as a masticator-mixer. However, it is also possible to place the propellant powder in contact with the aldehyde in the vapor phase prior to, during or after the drying process, by employing the aldehydes either in a gaseous phase or as an evaporated solution.

The propellant powders treated with the aldehydes in accordance with the present invention when compared to powders which are not treated with aldehydes, exhibit a substantial improvement in their mechanical, chemical and ballistic properties. They are harder, exhibit a greater stability, and result in higher initial velocities, with the gas pressures being increased very little or not at all. The increase in their efliciency can be utilized either in the firearm itself or by reducing the weight of the powder in the charge.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples are given merely as being illustrative of the present invention and accordingly are not to be considered as limiting.

Example 1 A strip-shaped powder, consisting of:

58.5% of nitrocellulose 40.0% of nitroglycerin 0.5% of diethyldephenylurea 1.0% of diphenylamine 0.3% of Vaseline is allowed to stand, as a calendered sheet of foil (film), in a drying chamber for 13 hours'at 50 C. A container 50 cm. high and filled with a formaldehyde solution of 38 volume percent is disposed in this drying chamber. Thereafter, the powder is further treated in the usual manner.

It is also possible to treat the finished powder with formaldehyde in the same manner, but with a maximum temperature of about 30 C., so that the nubs of the already nubbed powder will not be impaired. The term nubbing of propellant powder means the impression of indentations into the powder foil, wherein the thickness of the powder at the elevations and depressions can be somewhat thinner than the foil (sheet). Thus, the surface can be enlargd and the mutual spacing of the foils (sheets) from one another can be widened.

When condutcing the above-mentioned treatment, a strip-shaped powder is obtained having the properties as set forth in the following Table 1.

TABLE 1 m, Weight of the V atmospheric Formaldehyde treatment charge, g. m./sec. gauge Without 333 309. 598 With 325 311. 6 597 Similar results were also observed in connection with nitroglycerin-containing spherical-type powder. In this These spherical-grain powders exhibited the properties indicated in the following Table 2.

TABLE 2 M, Formaldehyde Weight of the V0, atmospheric Powder treatment charge, g. m./sec. gauge Example 3 A single base nitrocellulose powder, which exhibited the following composition:

98.4% of nitrocellulose 1.0% of diphenylamine 4.9% of dibutyl phthalate 0.6% of sodium oxalate likewise exhibited a clear increase in efiiciency, according to the following Table 3.

TABLE 3 Weight of the v t ii a mos enc Formaldehyde treatment charge, g. mJSeZ: gauge Without 49. 9 1, 034 s, 455 Wlt 49.9 1,063 3,869

TABLE 4 11b with, IIIb with,

in the He, in the H10, Ia, 11), Ha, mastieator with IIIa, masticator With Powder and formaldehyde treatment without with Without charge vapor without charge vapor Nitroglycenn, percent 39. 6 39- 4 73 40- 73 39- 5 40. 9 40. 9 38. 6 Diethyldiphenylurea, percent 0.65 0. 6 0.6 0. 6 0.6 0.6 0. 0. 6 Acetone, percent 6 0- 03 Diphenylamine, percent 1. 04 1. 1 1. 0 1.0 1.0 1. 0 1.0 1.0 Ether extract, percent 41. 7 41.6 42.6 42. 6 41. 4 42. 6 42.6 40.6 Ex-heat, caL/g 1, 234 1, 234/46 1, 24 /46 1, 241/44 1, 233/38 1, 235/39 1, 233/34 1, 237/38 Defiagration [explosion], C 160/64 164 164 165 166 TABLE 5 Upsetting P cone, Weight of atmosatmos- Recoil powder V0 pheres pheres Muzzle energy, Powder charge, g. mlsee. gauge gauge pressure I/kp.

0. 15 0. 42 I3 333 0. 27 333 0. 43 333 0. 43 325 0. 35 325 0.47 325 0. 15 325 0. 52 325 O. 48 330 0. 25 330 0. 11 330 0. 10 S30 0. 13 330 0. 10 330 0. 10

example, two powders, A and B, were employed having the following composition:

Nitroglyoen'n, percent ca. 9 ca. 10 Diphenylamine, percent.... ca. 1 ca. 1 Dibutyl phthalate, percent. ea. 5 ca. 6. 5 Ether extract, percent ca. 15 ca. 18 Ex-heat, c g ca. 900 ca. 830

The amount of aldehyde which can be used in the propellant powder composition of the present invention is that amount which is effective in producing a propellant composition exhibiting the advantageous results. Advantageously a volume percent of up to about 38% and more is effective in the present invention.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such varia tions are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as will be apparent to one skilled in the art are intended to be included.

What is claimed is:

1. A single or multiple-base propellant powder having improved ballistic, mechanical and chemical properties which comprises a nitrocellulose or nitroglycerin base powder and an efiective amount of an aliphatic aldehyde or benzaldehyde.

2. The propellant powder of claim 1, wherein the aldehyde is formaldehyde.

3. The propellant powder of claim 1, wherein said powder is a strip-shaped powder.

References Cited UNITED STATES PATENTS 3,244,668 4/1966 Knapp et al. 26045.85 3,447,983 6/1969 Camp et al 149-98 LELAND A. SEBASTIAN, Primary Examiner US. Cl. X.R.