Microcrystalline Nitrocellulose Pyrotechnic Compositions

Abstract

A pyrotechnic composition comprising microcrystalline nitrocellulose which is characterized as an ultra low-smoke composition. The pyrotechnic composition includes at least one flame coloring agent, and may be produced with or without an optional oxidizing agent, with or without an optional metal powder, with or without an optional chlorine donor. Upon combustion, the pyrotechnic composition produces illuminating emissions having desired colors and luminosity characteristics with significantly reduced or toxic combustion products and smoke.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation-in-part of U.S. patent application Ser. No. 11 / 058,677 herein incorporated by reference, filed on Feb. 15, 2005 and published as U.S. Patent Application Publication No. 2006 / 0180253 on Aug. 17, 2006.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH [0002] Not Applicable. BACKGROUND OF THE INVENTION [0003] The present invention is related to the manufacture and use of pyrotechnic compositions such as are used in fireworks and flares for providing an illuminating visual display, and in particular to the use of microcrystalline nitrocellulose as a fuel component in a pyrotechnic composition to provide vivid colors during combustion. [0004] Nitrocellulose, also known as cellulose nitrate, pyroxylin, colloxylin, xyloidin, celloidin, and parlodion, is a fast burning, easily ignitable, high-nitrogen energetic material which has been used in such applications as explosives and as a gun and rocket propell...

AI Technical Summary

Benefits of technology

[0014] Briefly stated, the present disclosure describes a pyrotechnic composition comprising microcrystalline nitrocellulose which is characterized as an ultra low-smoke composition. The pyrotechnic composition further includes at least one flame coloring agent, and may be produced with or without an optional oxidizing agent, with or without an optional metal powder, with or without an optional chlorine donor. The pyrotechnic composition produces illuminating emissions having desired colors and luminosity characteristics with significantly reduced toxic combustion products and smoke.

[0015] The present disclosure further describes a pyrotechnic composition including microcrystalline nitrocellulose that does not require the use of additional binders or densifying agents, which has a dense crystalline form, and which provides self binding characteristics under minor or moderate compression to a plastic-like substance, but which is harder and more durable then current pyrotechnic compositions.

Problems solved by technology

It is known that pyrotechnic compositions including nitrocellulose as the sole propellant in a color generating composition are not capable of generating sufficient temperature during combustion to produce an acceptable light output and depth of color suitable for use as a pyrotechnic star or other fireworks visual display element.

Initially, it was thought that the inability of nitrocellulose to produce adequate colors was due to the presence of contaminants in the combustion flame including sodium salts and un-oxidized carbon, but extensive testing has shown that the lack of functionality is mainly due to the low combustion temperature inherent to nitrocellulose itself.

Even when compressed to a great degree, nitrocellulose does not produce a sufficient combustion temperature to generate usable colors or useful luminosity as a fireworks display component by itself.

Common nitrocellulose is not capable of reaching sufficient temperatures during combustion to allow the use of a variety of color generating salts because the combustion temperature of nitrocellulose does not reach sufficient levels to cause the decomposition of the colorant salts into their constituent ions, enabling them to reform into the proper color radiating species in combination with free chlorine.

Typically both oxidizers and fuels are used for this purpose, and usually in combination with each other, since adding either an oxidizer or a fuel alone would alter the oxygen balance of the pyrotechnic composition, thereby lowering the performance.

Recently, perchlorates such as potassium and ammonium perchlorate have been discovered to pose a heath hazard in lower levels than previously believed.

Another problem with the use of nitrocellulose in a pyrotechnic composition is the inherent low density nature of nitrocellulose.

The use of additional binders, solvents, plasticizers, and coloiding agents generally only results in slower rate or burn and an increase in the smoke output of the pyrotechnic composition upon combustion, and increases the complexity of the manufacturing process.