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US 2007.006861 OA1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2007/0068610 A1 (43) Pub. Date: Mar. 29, 2007

(54) MICROCRYSTALLINE Publication Classification PYROTECHNIC COMPOSITIONS (51) Int. Cl. (76) Inventor: Russell R. Nickel, Columbus, MT (US) C06B 45/10 (2006.01) (52) U.S. Cl...... 149/19.8 Correspondence Address: PSERIEDER, WOODRUFF & (57) ABSTRACT 12412 POWERSCOURT DRIVE SUTE 200 ST. LOUIS, MO 63131-3615 (US) A. pyrotechnic composition comprising microcrystalline nitrocellulose which is characterized as an ultra low- (21) Appl. No.: 11/469,936 composition. The pyrotechnic composition includes at least one flame coloring agent, and may be produced with or (22) Filed: Sep. 5, 2006 without an optional oxidizing agent, with or without an optional powder, with or without an optional Related U.S. Application Data donor. Upon combustion, the pyrotechnic composition pro duces illuminating emissions having desired colors and (63) Continuation-in-part of application No. 11/058,677, luminosity characteristics with significantly reduced or toxic filed on Feb. 15, 2005. combustion products and Smoke. US 2007/006861.0 A1 Mar. 29, 2007

MCROCRYSTALLINE NITROCELLULOSE may include at least one compound selected from a group PYROTECHNIC COMPOSITIONS consisting of ammonium , alkali metal perchlo rates, alkali metal , alkali metal and alka CROSS-REFERENCE TO RELATED line earth metal nitrates. Additional fuels may include car APPLICATIONS bon, , titanium alloys, , Zirconium alloys, 0001. The present application is a continuation-in-part of , alloys of iron, , alloys of magnesium, U.S. patent application Ser. No. 11/058,677 herein incorpo aluminum and alloys of aluminum. These materials are rated by reference, filed on Feb. 15, 2005 and published as easily solidified with binders, agglomerated, or compressed, U.S. Patent Application Publication No. 2006/0180253 on to form pellets or granules. Aug. 17, 2006. 0008. It is known that pyrotechnic compositions includ ing nitrocellulose as the Sole in a color generating STATEMENT REGARDING FEDERALLY composition are not capable of generating Sufficient tem SPONSORED RESEARCH perature during combustion to produce an acceptable light output and depth of color Suitable for use as a pyrotechnic 0002) Not Applicable. star or other visual display element. Initially, it was thought that the inability of nitrocellulose to produce BACKGROUND OF THE INVENTION adequate colors was due to the presence of contaminants in 0003. The present invention is related to the manufacture the combustion flame including salts and un-oxi and use of pyrotechnic compositions such as are used in dized , but extensive testing has shown that the lack fireworks and for providing an illuminating visual of functionality is mainly due to the low combustion tem display, and in particular to the use of microcrystalline perature inherent to nitrocellulose itself. Even when com nitrocellulose as a fuel component in a pyrotechnic compo pressed to a great degree, nitrocellulose does not produce a sition to provide vivid colors during combustion. Sufficient combustion temperature to generate usable colors or useful luminosity as a fireworks display component by 0004 Nitrocellulose, also known as cellulose , itself. pyroxylin, colloxylin, Xyloidin, celloidin, and parlodion, is a fast burning, easily ignitable, high-nitrogen energetic mate 0009 Common nitrocellulose is not capable of reaching rial which has been used in Such applications as explosives Sufficient temperatures during combustion to allow the use and as a gun and rocket propellant. Nitrocellulose burns of a variety of color generating salts because the combustion cleanly with non-toxic combustion byproducts. Such as temperature of nitrocellulose does not reach sufficient levels nitrogen, carbon dioxide, and water vapor. In the fireworks to cause the decomposition of the colorant salts into their industry, nitrocellulose is typically utilized as an energetic constituent ions, enabling them to reform into the proper in a lacquer form, added to pyrotechnic compositions. color radiating species in combination with free chlorine. To solve this problem, it is known to combine the nitrocellulose 0005 Nitrocellulose is manufactured from cellulose, with additional chemical additives to increase the tempera which has the chemical formula CHOs, and which is the ture of combustion. Typically both oxidizers and fuels are principle structural component of cell walls in higher plants. used for this purpose, and usually in combination with each An almost pure form of cellulose, known as alpha cellulose, other, since adding either an oxidizer or a fuel alone would occurs naturally in cotton fibers. The physical properties of alter the oxygen balance of the pyrotechnic composition, cellulose are a result of an association of cellulose chains thereby lowering the performance. which form crystalline structures called microfibrils, typi 0010. It is further well known that it is advantageous to cally having a diameter of 2-20 nm, a length of between provide free and excess chlorine ions to color generating 100-40,000 nm, and which contain about 2000 cellulose compositions to ensure the prompt and efficient production molecules. Within a plant cell, the orientation of microfibrils of the preferred “mono-chloride' color emitting species. The changes from layer to layer. Often, especially in very strong favored color generating species in pyrotechnic flames is plant cell walls, the microfibrils are arranged screw-like generally considered to be a mono-chloride of an alkali about an axis of the cell, with changes in the turning angle metal or alkaline earth metal. In the past it has been found from layer to layer. to be advantageous to add supplemental chlorine donating 0006 Nitrocellulose is produced by the well known pro compounds to increase the chances of forming the desired cess of nitrating cellulose with a mixture of concentrated mono-chlorides and thus the intended color. Recently, per acids including nitric acid, which has the chemical formula chlorates Such as potassium and ammonium perchlorate HNO. During the resulting chemical process, the nitric acid have been discovered to pose a heath hazard in lower levels converts the cellulose into cellulose nitrate, having the than previously believed. chemical formula of CHO(NO), CHOs (NO), or 0011 Since a majority of chlorine-containing compounds CH, Os(NO), depending on the degree of nitration. Sulfu normally employed in color-generating pyrotechnic compo ric acid generally is used in conjunction with the nitric acid sitions, are either toxic, hazardous, or pose a pollution during the nitrating process to prevent the water produced in hazard, particularly in geographic locations near which the reaction from diluting the concentration of nitric acid. regular fireworks displays are provided, it would be advan 0007 Pyrotechnic and explosive compositions are typi tageous to provide a pyrotechnic composition for use in cally fairly dense mixtures of crystalline salts for flame fireworks and flares which produces illuminating emissions color, crystalline oxidizers, carbonaceous fuels, and pow having desired color and luminosity characteristics while dered . The flame coloring agents are commonly the reducing or eliminating harmful or toxic compounds. salts of the metals; , , , , cal 0012 Another problem with the use of nitrocellulose in a cium, potassium, Sodium and lithium. The oxidizing agents pyrotechnic composition is the inherent low density nature US 2007/006861.0 A1 Mar. 29, 2007

of nitrocellulose. The addition of fuels or oxidizers to a such as described in U.S. Pat. No. 6,599,379 B2 to Hiskey pyrotechnic composition containing nitrocellulose may et al. because of the clean burning, low Smoke, low tem serve to increase the density of the composition, but the perature and generally environmentally friendly nature of nitrocellulose molecules remain overall a low density mate conventional nitrocellulose. However, conventional nitro rial. Coloiding and partial dissolution of the pyrotechnic cellulose has the undesirable property of not being able to composition has been employed in pyrotechnic components, attain combustion temperatures which are sufficient to gen as well as propellant applications for many years. The use of erate the vivid and vibrant colors desired in fireworks additional binders, solvents, , and coloiding displays without the use of Supplemental energetic oxidiz agents generally only results in slower rate or burn and an ers, fuels, and/or combinations of same. The oxidizers and increase in the Smoke output of the pyrotechnic composition fuels employed with conventional nitrocellulose are the upon combustion, and increases the complexity of the manu same as used in current state of the art fireworks composi facturing process. tions. Thus, the problems inherent in utilizing these oxidiz 0013. Accordingly, it would be advantageous to provide ers and fuel in combination with conventional nitrocellulose a pyrotechnic composition which reduces the requirement remain the same, albeit at a reduced amount. for additional binders or densifying agents, which has a 0020. The present invention serves to remove nearly dense crystalline form, and which provides self binding completely these Smoke causing and potentially environ characteristics under minor or moderate compression to a mentally hazardous materials both from the standpoint of the plastic-like substance, but which is harder and more durable combustion byproducts from the fireworks display and from then current pyrotechnic compositions. the manufacture of same by providing pyrotechnic compo sitions which include microcrystalline nitrocellulose BRIEF SUMMARY OF THE INVENTION (MCNC) as a principal component by weight. 0014 Briefly stated, the present disclosure describes a 0021 Microcrystalline nitrocellulose, described in U.S. pyrotechnic composition comprising microcrystalline nitro Patent Application Publication No. 2006/0180253 A1 to cellulose which is characterized as an ultra low-smoke Nickel et al. combusts at a higher temperature than conven composition. The pyrotechnic composition further includes tional nitrocellulose. Theoretical basis for the increased at least one flame coloring agent, and may be produced with combustion temperature include: (1) the inherent density of or without an optional oxidizing agent, with or without an the material which allows for a greater compression and optional metal powder, with or without an optional chlorine density of loading, intensifying and magnifying the heat donor. The pyrotechnic composition produces illuminating created; (2) since the microcrystalline nitrocellulose consists emissions having desired colors and luminosity character of individual crystals of nitrated alpha cellulose, there is a istics with significantly reduced toxic combustion products greater combustion Surface area and for the same nitration and Smoke. level burn more intensely; and (3), microcrystalline nitro 0.015 The present disclosure further describes a pyro cellulose, like microcrystalline cellulose, is highly absorp technic composition including microcrystalline nitrocellu tive due to the capillary action of its surface porosity. lose that does not require the use of additional binders or 0022. During the nitration process for producing micro densifying agents, which has a dense crystalline form, and crystalline nitrocellulose, the nitrating mix, typically a mix which provides self binding characteristics under minor or of sulfuric and nitric acids tend to penetrate the surface of moderate compression to a plastic-like Substance, but which microcrystalline cellulose to a greater extent than in the is harder and more durable then current pyrotechnic com nitration of fibrous cellulose during the production of con positions. ventional nitrocellulose. The residual acids are bound in the 0016. The present disclosure provides a functional color crystals tightly. During the neutralization and stabilization producing fireworks system based on nitrated microcrystal process of MCNC, typically promoted by treatment with line cellulose products that require no additional oxidizers or Solutions of alkali metal or alkaline earth metal carbonates, fuels to combust at an acceptable level for fireworks and bicarbonates or hydroxides. The and, to a greater pyrotechnic uses. degree, the nitrates of the respective alkaline treatment compounds are created and retained in the porous crystal 0017. The foregoing features, and advantages set forth in structure of microcrystalline nitrocellulose. Suitable mate the present disclosure as well as presently preferred embodi rials for treatment during the neutralization and stabilization ments will become more apparent from the reading of the process include potassium carbonate, potassium bicarbonate following description. and potassium hydroxide and to a lesser degree the carbon ates or hydroxides of strontium, barium and copper. While DESCRIPTION OF THE PREFERRED the nitrates and sulfates formed by the neutralization of the EMBODIMENT residual material consists of less than 0.5% by weight of the 0018. The following detailed description illustrates the MCNC, the tight incorporation of these oxidizing agents invention by way of example and not by way of limitation. with the MCNC crystals tends to catalyze pyrotechnic The description enables one skilled in the art to make and combustion of the MCNC with or without any additional use the present disclosure, and describes several embodi oxidizing additives. ments, adaptations, variations, alternatives, and uses of the 0023. Similar to conventional nitrocellulose-based pyro present disclosure, including what is presently believed to be technic compositions, the size of a flame envelope generated the best mode of carrying out the present disclosure. by combustion of an MCNC composition of the present 0.019 Previously, pyrotechnic chemistry has attempted to invention is greatly increased over that of Standard Solid take advantage of traditional nitrocellulose compositions, oxidizer/fuel pyrotechnic compositions. The larger the flame US 2007/006861.0 A1 Mar. 29, 2007

envelope and better the gas production, the better the result than ordinary nitrocellulose when burned under elevated ing pyrotechnic star or display. pressures. Fragments of microcrystalline nitrocellulose 0024 Microcrystalline nitrocellulose based pyrotechnic readily bond together without the use of an adhesive, and compositions do not require additional additives to attain can be mixed with other substances so as to hold an additive Sufficient temperatures for adequate luminosity, and com while self-bonding. bust very well without the inclusion of supplemental oxi dizers or fuels which produce solid particulate matter as 0029. These characteristics of microcrystalline nitrocel byproducts of combustion. During combustion, Solid par lulose enable a pyrotechnic composition including microc ticulate material present in a composition tends to radiate rystalline nitrocellulose and any optional color agents and white light while in an excited state within a flame envelope. metals to be produced with a reduction in the use of This white light often will wash out intended colors of a additional binders or densifying agents as compared to pyrotechnic display. Incorporation of microcrystalline nitro compositions utilizing convention nitrocellulose, which has cellulose in a pyrotechnic composition enables a reduction a dense crystalline form, and which provides self binding in the quantity of Solid Smoke causing particulate matter, characteristics under minor or moderate compression to providing improved color purity and color depth during form a plastic-like Substance which is harder and more combustion. Additionally, since MCNC based pyrotechnic durable then current pyrotechnic compositions composed compositions of the present disclosure combust in a clean primarily of nitrocellulose. and orderly manner, it is not necessary to add additional chlorinated compounds to generate acceptable color purity 0030. While the pyrotechnic compositions of the present when using metal chloride salts as a color producing agent. invention which utilize microcrystalline nitrocellulose do not require Supplemental fuels or oxidizers, a Supplemental 0025. It is well known that various metal salts can be fuel or oxidizer may optionally be used with the pyrotechnic advantageously employed as flame coloring agents (flame compositions of the present invention to increase combus colorants), for example salts such as calcium car tion temperatures thereby increasing light output and burn bonate for the color orange, strontium salts such as strontium speed. Since no processing other than simple mixing and nitrate for the color red, barium salts and or boron com compression of the components of the pyrotechnic compo pounds for the color green, Sodium salts such as sodium sition is required, there is no problem with incompatibility nitrate for the color yellow, copper salts such as copper with binders or the solvents for same. For example, the chloride for the color blue, potassium salts such as potas addition of magnesium, aluminum or other suitable high sium chloride for the color violet. Combinations of metal temperature generating metallic compounds may simply be salts can yield other desirable colors. For example, a com incorporated in the dry mix during processing of the MCNC bination of copper carbonate and has a pyrotechnic composition. Since no water, alcohol, acetone purple color, and a combination of copper carbonate and or the like is needed in the processing, no incompatibilities has a blue-green color, and a combination of to the metals will be encountered. A few percent of a metallic barium nitrate and has a lime color. In spite fuel component is all that is required to increase the levels of their toxicities, other metal salts such as cadmium, of light output approaching that of Standard color generating uranium, gold, mercury, arsenic and lead may be used to pyrotechnic compositions. provide other colors if desired. Carbonate or nitrate salts are generally preferred over salts such as chloride salts as the 0031. The pyrotechnic compositions of the present inven chloride salts tend to be hydrates and contribute undesired tion which utilize microcrystalline nitrocellulose in combi Water. nation with metal chloride colorants, do not require addi 0026. It is additionally known to those of ordinary skill in tional chlorine doning compounds such as parlon, Saran, the art that metal flakes or powder can be added to pyro chlorowax, or ammonium perchlorate. technic compositions to increase the temperature and thus However additional chlorine containing compounds may be the light output of the flame or to produce a spark effect. optionally employed in the present invention in applications Suitable metals can include aluminum, magnesium, titanium where hazardous combustion byproducts are of less concern, and iron or their alloys Such as magnesium/aluminum alloy. to provide enhanced depth and clarity to well defined colors during combustion while still greatly reducing the Smoke 0027. In addition to exhibiting excellent combustion output compared to conventional pyrotechnic compositions. properties, microcrystalline nitrocellulose compacts well under minimum compression pressures, resulting in an 0032. In addition, the MCNC pyrotechnic composition of exceptionally strong compacted form which exhibits the present invention, which is advantageous in fireworks strength similar to that of the plastic Delrin (acetal). A high stars, may be used in fireworks shells and mines to fuel other binding capability enables the production of pellets or pyrotechnic devices such as gerbs, lance, flares, airburst and tablets of microcrystalline nitrocellulose which are all manner of fireworks flames where good color purity, low extremely hard and stable, and which can be machined in Smoke and low environmental impact is important. much the same manner as plastic, by mechanical cutting or 0033. The MCNC pyrotechnic compositions of the adhesively joining using solvents commonly utilized to present invention generally consist of microcrystalline nitro dissolve nitrocellulose. cellulose fuel from about 20 to 97 percent by weight, and a 0028. Additional characteristics of microcrystalline flame coloring agent from about 1 to 8 percent by weight. nitrocellulose include low friability, inherent lubricity, high The MCNC pyrotechnic compositions are more particularly bulk density of 0.58 gm/cc to 0.72 gm/cc uncompressed, and described in the following examples, which are intended as a high dilution potential. It has been observed that microc illustrative only, as numerous modifications and variation rystalline nitrocellulose exhibits a lower pressure exponent will be readily apparent to those skilled in the art. US 2007/006861.0 A1 Mar. 29, 2007

EXAMPLE 1. 6. The pyrotechnic composition of claim 1 wherein the 0034. A blue star MCNC pyrotechnic composition com microcrystalline nitrocellulose fuel contains from about prised of: 87% microcrystalline nitrocellulose; 5% potas 10% to 13.4% nitrogen content. sium nitrate; 4% copper ; and 4% hexachloroethane 7. The pyrotechnic composition of claim 1 wherein the was dry mixed by hand and sieved several times to obtain a flame coloring agent is a metal salt. homogenous mixture. The homogenous mixture was then 8. The pyrotechnic composition of claim 7 wherein the at fed into a stokes rotary tablet press, and tablets of 0.21 least one metal salt includes a metal from the group con inches in diameter by 0.21 inches tall were formed for use sisting of sodium, barium, strontium, copper, calcium, potas as star components by simple compression. The star com sium, cesium, lithium or boron. ponents are at this point ready to be loaded into any desired 9. The pyrotechnic composition of claim 1 wherein the fireworks device without further processing. flame coloring agent may include one compound from the EXAMPLE 2 group consisting of metal chlorides of sodium, barium, 0035 A red magnesium star MCNC pyrotechnic compo strontium, copper, calcium, potassium, cesium and lithium. sition comprised of 80% microcrystalline nitrocellulose; 10. The pyrotechnic composition of claim 1 wherein the 10% strontium nitrate; 4% ; 3% mag flame coloring agent may include one metal compound from nesium metal powder, and 3% Saran was dry mixed by hand the group consisting of magnesium, aluminum, magnesium/ and sieved several times to obtain a homogenous mixture. aluminum alloys, titanium and titanium alloys. The homogenous mixture was then fed into a stokes rotary 11. The pyrotechnic composition of claim 1 wherein said tablet press and tablets of 0.21 inches in diameter by 0.21 microcrystalline nitrocellulose comprises 87% by weight, inches tall were formed by simple compression for use as said flame coloring agent comprises 4% copper oxide by star components. The star components are, at this point weight, and further including 5% and 4% ready, to be loaded into any desired fireworks device without hexachloroethane. further processing. 12. The pyrotechnic composition of claim 1 wherein said microcrystalline nitrocellulose comprises 80% by weight, EXAMPLE 3 said flame coloring agent comprises 4% strontium carbonate 0036) A red MCNC pyrotechnic composition com by weight, and further including 10% strontium nitrate, 3% prised of 96% microcrystalline nitrocellulose and 4% stron magnesium metal powder, and 3% Saran. tium chloride was dry mixed by hand and sieved several 13. The pyrotechnic composition of claim 1 wherein said times to obtain a homogenous mixture. The homogenous microcrystalline nitrocellulose comprises 96% by weight, mixture was then incrementally consolidated by hydraulic said flame coloring agent comprises 4% strontium chloride press into a paper tube having an inside diameter of 0.5 by weight. inches and a length of 2.0 inches. 14. A method for processing an ultra-low Smoke produc 0037 As various changes could be made in the above ing pyrotechnic composition comprising: compositions without departing from the scope of the dis closure, it is intended that all matter contained in the above providing a dry microcrystalline nitrocellulose fuel from description or shown in the accompanying drawings shall be about 20 to about 97 percent by weight; interpreted as illustrative and not in a limiting sense. adding a flame coloring agent from about 1 to about 8 1. A ultra low-smoke producing pyrotechnic composition percent by weight; for producing a colored flame composition comprising: mixing the ultra-low Smoke producing pyrotechnic com microcrystalline nitrocellulose fuel from about 20 to position; and about 97 percent by weight; and compressing said mixed ultra-low Smoke producing pyro a flame coloring agent from about 1 to about 8 percent by technic composition into a selected configuration. weight. 15. The method of claim 14 further comprising the step of 2. The pyrotechnic composition of claim 1 further includ utilizing said compressed configuration of said mixed ultra ing at least one chlorine containing compound from about 0 to about 10 percent by weight. low Smoke producing pyrotechnic composition in the for 3. The pyrotechnic composition of claim 1 further includ mation of at least one pyrotechnic device selected from a ing at least one oxidizing agent from about 0 to about 10 group consisting of flares, gerbs, fountains, lances, and stars. percent by weight. 16. The method of claim 14 further comprising the step of 4. The pyrotechnic composition of claim 3 wherein the adding at least one chlorine containing compound from oxidizing agent may include one compound from the group about 0 to about 10 percent by weight prior to said mixing consisting of alkali metal or alkaline earth metal nitrates, step. alkali metal or alkaline earth metal chlorates and alkali metal 17. The method of claim 14 further comprising the step of or alkaline earth metal peroxides. adding at least one oxidizing agent from about 0 to about 10 5. The pyrotechnic composition of claim 1 further includ percent by weight prior to said mixing step. ing at least one metallic fuel from about 0 to about 10 percent by weight;