US2939780A - Pyrotechnic compositions - Google Patents

Description

PYROTECHNIC COMPOSITIONS Jean A. M. Brock, St. Louis, Mo., assignor to Olin Mathieson Chemical Corporation, East Alton, 11]., a corporation of Virginia No Drawing. Filed Apr. 21, 1958, Ser. No. 729,526

7 Claims. (Cl. 52-24) This invention relates to pyrotechnic compositions and particularly to combination smoke and flare compositions. Various types of pyrotechnic compositions capable of providing large coluds of smoke upon combustion are well known as are pyrotechnic compositions for the production of intense flame. In various situations,'the

desirability of a pyrotechnic composition capable of the simultaneous production of huge clouds of smoke together with a brilliant flame has long been recognized. In previous attempts to provide such combination signals, pyrotechnic devices have been developed in which a smoke producing composition is adjacent to a flare composition. Such a union of a smoke producing composition with a separate flare composition has not been completely satisfactory. The preparation of such devices requires special care and involves handling of two separate mixtures. In addition, great care must be taken 'to coordinate the burning rates of the two compositions to provide satisfactory performance. 7

It is, therefore, an object of this invention to provide novel pyrotechnic compositions capable of simultaneously producing a large volume of smoke and a brilliant flame. Another object of this invention is to provide novel combination smoke and flare compositions. A further object of this invention is to provide pyrotechnic compositions overcoming the disadvantages of the prior art. A more specific object of this invention is to provide a combination white smoke and flare composition.

In accordance with this invention, these and other .objects are accomplished by providing combination white Esmoke and flare compositions containing magnesium, zinc loxide and ammonium perchlorate. Up to about 60% .by weight of the metallic magnesium in these compositions can be replaced with magnesium chloride. The substitution of magnesium chloride as a fuel retards the burning rate of the compositions and increases smoke evolution. Smoke generation of these compositions can also be intensified by the incorporation of hexachlorethane. The components of these compositions are granular and preferably have an average particle size of about 80 mesh. However, the particle size can be varied to control the rate of burning. The compositions of this invention are prepared by providing an intimate mixture of the various components which is then packed into suitable containers or pyrotechnic devices. The mixtures without a binder can be tamped into their containers or alternatively a suitable plastic binder can be utilized.

The components of the compositions made in accordance with this invention must be present in substantially stoichiometric proportions. However, the proportions can be varied to alter the characteristics of the compositions. Thus, the burning rate, flame intensity, smoke generation, and other properties of these compositions can be modified Within limits by altering the proportions between the reactants.

In order to increase the smoke forming capabilities of the compositions while retaining suitable flame intensity properties, up to about 60% by weight of the metallic M 2,939,780 Patented June .1960

magnesium can be replaced with magnesium chloride. The magnesium chloride serves both as a fuel and a chloride donor, and is preferably present in amounts-substantially equal to the metallic magnesium. Amounts of magnesium chloride slightly in excess of the magnesium can be used, but it has been found that when more than about 60% of the magnesium is replaced by magnesium chloride, the resultant composition burns with no flame and produces only a thin smoke.

[It is believed that the success of the novel composition of the present invention is dependent upon reactions which may be typified by the following chemical equations:

While all observations of the compositions indicate that upon combustion they react in the above manner, it is fully recognized that other reactions may actually occur. In any event, the molecular ratios of the reactants remain constant. Thus, it is to be distinctly understood that the present invention is not limited to the above reactions.

When the compositions consist of magnesium, zinc oxide, and ammonium perchlorate, it has been found that the proportions of the ingredients must be maintained within the following approximate percentage ranges:

Percent Magnesium 27-50 Zinc oxide 15-30 Ammonium perchlorate 30-55 Preferably the composition contains about 35% mag nesium, about 17% zinc oxide and about 49% ammonium perchlorate. These and other percentages throughout the specification are based on the relative weights of the components in the compositions.

When the metallic magnesium fuel is partially replaced by magnesium chloride, it is preferred to employ a mixture containing approximately 25% magnesium, 25% magnesium chloride, 20% zinc oxide and about 30% ammonium perchlorate, but the proportions can vary generally as indicated above with up to about 60% of the magnesium being replaced with magnesium chloride. I v

In those instances where hexachlorethane is added to compositions containing magnesium as a fuel to intensify the smoke evolution, it is preferred to use a composition containing about 12% magnesium, about 36% zinc oxide, about 35% hexachlorethane and about 17% ammonium perchlorate, but the proportions can vary "Percent Magnesium 10-25 Zinc oxide 30-40 Hexachlorethane 30-40 Ammonium perchlorate 15-25 When proportions of metallic magnesium outside of the ranges set forth above are used, undesirable results are obtained. For example, when too little magnesium is used, the intensity of the flame is severely reduced and excessive amounts of magnesium result in very rapid burning compositions.

The compositions of the present invention rely for smoke generation upon the formation of zinc chloride which can be supplemented by the combustion of hexachlorethane. Thus, in each instance the amount of zinc oxide present should be suflicient to provide adeproperties of the composition. Amounts of .hexachlorethane in excess of 40% normally do not improve the properties of themixtures. p 7 v a r The formulations made in accordance'with this invention can readily be adjusted to include a plastic binder Upon ignition, the mixture burned for about 50 seconds such as polyvinyl acetate, ,polyvinyl chloride copolymers, polyesters, epoxy, and the like. Up to about 5% of such binderscanbe added without changing the composition. If more binder is desired, it canbe readily added by readjusting the remaining components. Since the combination smoke and flare compositions normally have a positive oxygen balance, the addition of more binder can be accomplished without difliculty.

. Theinvention will be more fully understood by refer- :ence to the following specific examples of preferred embodiments thereof. In these embodiments, all propor tions are expressed in parts by weight. 1

' About 12 parts of metallic magnesium having a granulation. ofabout 40 mesh were mixed with about 36 parts .of zinc oxide, about 35 parts of hexachlorethane, and about 17 parts of ammonium perchlorate. These materials were thoroughly mixed together with about 5 parts of polyvinyl acetate which served to bind the components together. The uniform mixture was then charged into metal cans about 2% inches in diameter and about 12%; inches high. The mixture was introduced in two increments-and pressed with a 25,000 pound load. An ignition pellet containing about 20% black powder, about 40% potassium nitrate, and about 40% silicon was attached to the upper surface of the ignition composition ,by means of a nitrocellulose lacquer. The assembly was then adaptable for. ignition by a squib, quick match or other conventional means. Upon ignition, the smoke and .flame composition burned for about seconds with a with a brilliant white flame and developed a large cloud of heavy white smoke.

While the above examples describe particular methods of formulating the compositions of this invention and also recite charging them into a specific type of container, it will be readily understoodthat other formulating means can be utilized and that the compositions can be provided with any suitable type of container. Thus, the compositions can contain sufiicient binder to provide a mix that can be molded, extruded, or otherwise shaped and the consolidated body of the composition can then be provided with a suitable wrap-per. Also, any of the conventional pyrotechnic ignition means can be employed to ignite these compositions.

Having thus described the invention, what is claimed is:

- 1. A.combinati on white smoke and flare composition consisting essentially of substantially stoichiometric proportions of magnesium, zinc oxide and ammonium perchlorate for the formation of magnesium oxide, zinc chloride, nitrogen, and water as reaction products.

2. A combination white smoke and flare composition consisting essentially of substantially stoichiometric'proportions of magnesium, magnesium chloride, zinc oxide,

and ammonium perchlorate for the formation of magnesium oxide, zinc chloride, and ammonium chloride as reaction products.

3. A combination white smoke and flare composition consisting essentially of substantially stoichiometric proportions of magnesium, zinc oxide, ammonium perchlorate, and hexachlorethane for the formation of magnesium oxide, zinc chloride, carbon dioxide and ammonium chloride as reaction products.

4.. The composition of claim 1 in which a portion of the magnesium not in excess of about 60 percent is replaced with magnesium chloride.

brilliant white flame and developed a large cloud of .heavy white smoke. .Another batch of a combination smoke and flare composition was prepared in accordance with this invention.

-In/this embodiment, a portion of the metallic magnesium was replaced with magnesium chloride. This formulation .had the following approximate composition:

'25 magnesium 25% magnesium chloride 20% zinc oxide I 30% ammonium perchlorate 5. The composition of claim 3 in which a portion of the magnesium not in excess of about 60 percent is replaced with magnesium chloride.

6. A combination White smoke and flare composition consisting essentially of between about 30 percent and about 45 percent by weight magnesium, between about 15, percent and about 30 percent by weight zinc oxide,

and between about 35 percent and about 50 percent by; weight ammonium perchlorate.

, 7. A combination white smoke and flare composition consisting essentially of between about 10 percent and about 25. percentby weight magnesium, between about 30 percent and about 40 percent by weight zinc oxide, between about 30 percent and about 40 percent by weight hexachlorethane, and between about 15 percent and about 25 percent by weight ammonium perchlorate.

References Cited in the file of this patent UNITED STATES PATENTS 2,416,639 Pearsall Feb. 25, 1947 FOREIGN PATENTS 127,031 Great Britain May 29, 1919

Claims (1)

1. 3. A COMBINATION WHITE SMOKE AND FLARE COMPOSITION CONSISTING ESSENTIALLY OF SUBSTANTIALLY STOICHIOMETRIC PROPORTIONS OF MAGNESIUM, ZINC OXIDE, AMMONIUM PERCHLORATE, AND HEXACHLORETHANE FOR THE FORMATION OF MAGNESIUM OXIDE, ZINC CHLORIDE, CARBON DIOXIDE AND AMMONIUM CHLORIDE AS REACTION PRODUCTS.