Colored Pyrotechnic Smoke-Producing Composition

Abstract

A colored pyrotechnic smoke-producing composition has an oxidizer, a fuel, a flame retardant, a dye, a coolant, and a binder. The oxidizer may be potassium chlorate. The fuel may be starch, dextrose, lactose, and / or sucrose. The coolant may be sodium bicarbonate or magnesium carbonate. The binder may be nitrocellulose or a halogen-free thermoplastic. The flame retardant may be one or more nitrogen-rich compounds. The composition may be in pelletized form or in the form of a solid charge. The composition may consist of on a mass basis oxidizer 20-35%, fuel 15-25%, flame retardant 5-15%, dye 27-40%, coolant 8-18%, and binder 1-2%. The invention may be a device consisting of a body filled with the composition and a first fire starter composition, and an attached squib igniter. The body may be a grenade. A process for producing the composition is also disclosed.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a smoke-producing pyrotechnic composition that is useful primarily in pyrotechnics for the production of colored smokes. More particularly, the present invention is related to generally cool-burning, non-toxic, and non-corrosive smoke producing compositions, which incorporate at least one affordable nitrogen-rich compound in addition to an oxidizer-fuel system, smoke-forming substance, and binder. Affordable nitrogen-rich compounds that are suitable for use with the current invention can include guanidine nitrate, guanidine carbonate, or dicyandiamide; azodicarbonamide, melamine, and oxamide.BACKGROUND OF THE INVENTION[0002]Effective and safe generation of colored smoke by the vaporization of an organic dye poses a challenging pyrotechnic problem. The military and the fireworks and entertainment industries rely on this technique for the generation of copious quantities of brilliantly colored smoke.[0003]The requirements fo...

AI Technical Summary

Benefits of technology

The present invention provides an improved colored pyrotechnic smoke-producing composition that has all the advantages of the prior art. The composition includes an oxidizer, a fuel, a flame retardant, a dye, a coolant, and a binder. The composition can be in pelletized form or a solid charge. The device consists of a body filled with the composition and a first fire starter composition, and an attached squib igniter. The process for producing the composition is also disclosed. The invention solves the problems of prior art and provides a safer and more effective colored pyrotechnic smoke-producing composition.

Problems solved by technology

Effective and safe generation of colored smoke by the vaporization of an organic dye poses a challenging pyrotechnic problem.

If the temperature is too high, the dye molecules will decompose, and the generated smoke's color quality and volume will deteriorate.

By considering the kinetics of combustion and the desired yield of colored smoke, conventional smoke-producing compositions require a strongly exothermic composition, but struggle to limit the degradation of the coloring medium by combustion.

A weakly exothermic composition is unsuitable because it permits only a minimal percentage of coloring medium and furnishes only a very mediocre smoke yield that is hardly visible, especially when there is a cloudy or dark sky.

A weakly exothermic composition also is difficult to ignite to initiate smoke emission.

In contrast, a two slow combustion produces a smoke yield of minimal consequence and tends toward self-extinction of the combustion process.

However, most existing smoke-producing compositions have severe limitations.

One of the limitations is that of toxicity.

Many smoke-producing compositions incorporate materials that are severely toxic or become irritants when subjected to the heat necessary to produce smoke.

Salts do not work well: ionic species generally have low volatility because of their strong inter-ionic attractions within the crystalline lattice.

At the typical reaction temperatures of smoke compositions, these groups are likely to release their oxygen, leading to oxidative decomposition of the dye molecules.

Groups such as —NH2 and —NHR (amines) are used, but potentially dangerous oxidative coupling reactions can occur in an oxygen rich environment.Old-style dyes for military markers and grenades are polycyclic or aromatic amino, hydroxyl, azo and keto compounds, in which unsaturation conjugated with the aromatic structure.

Such compounds are known to cause chromosome mutations, which may lead to cancer.

However, if the temperature of the fuel-oxidizer reaction is too high, the dye will degrade, and the quantity and color quality of smoke generated will be unsatisfactory.

Although heat is required for the dye to undergo the essential phase changes to produce colored smoke, individual molecules of the dye are subject to degradation at elevated temperatures.

If the molecular structure of the dye is subject to forces and energies that are great enough to cleave the molecule's bonds, changes in smoke color or loss of color properties are likely to occur.

Another problem encountered in the search for a desirable smoke-generating composition is the production of a solid residue as conventional smoke-producing compositions burn.

As a result, deflagration can occur, which can cause injury to bystanders, or result in only a limited release of colored smoke.

Furthermore, the formation of slag increases the decomposition of the dye vapor, which may lead to color deterioration.

Only a few dye materials have been found suitable for use in prior art smoke-producing compositions that rely upon the vaporization of an organic dye because most dye materials generate excessive slag or clinkers.

Other known compositions have the drawback of burning at temperatures that are too high (600-800° C.) or leave too many carbonaceous residues, which are impermeable to the dye molecules in the gas phase.

These conditions cause the destruction of the smoke-producing components and therefore demonstrate poor effectiveness in producing colored smokes.

Another drawback may be the rapid ascent of the smoke because of the smoke's high temperature, which causes the smoke to dissipate too quickly for the desired effect to be achieved.

Another major drawback of using such mixtures is the hazard created by the creation of a flame front at the moment of ignition of the main filling composition.

This behavior can create safety hazards to personnel and equipment, as well as potentially causing brush and grass fires in dry environments with significantly elevated fire danger conditions.

However, many smoke-producing compositions presently used are difficult to handle.

Many such compositions are toxic and irritating, requiring special precautions during use.

Many such compositions are also corrosive and damaging to both electronic and mechanical equipment.

Finally, some compositions produce an excess of heat and flame, again limiting their usefulness and requiring that additional safety measures be taken.

For these reasons, conventional smoke-producing compositions are found to be inadequate

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