| Method for manufacture of microcrystalline nitrocellulose -> Monitor Keywords |
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Method for manufacture of microcrystalline nitrocelluloseRelated Patent Categories: Explosive And Thermic Compositions Or Charges, Containing Inorganic Nitrogen-oxygen Salt, Ammonium Nitrate, With Nitrated Organic Compound, Nitrocellulose, 10 Percent Or OverMethod for manufacture of microcrystalline nitrocellulose description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060180253, Method for manufacture of microcrystalline nitrocellulose. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] Not Applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH [0002] Not Applicable. BACKGROUND OF THE INVENTION [0003] The present application relates generally to nitrocellulose, and in particular, to a method for manufacturing microcrystalline nitrocellulose to provide an energetic, high-nitrogen fuel which is compressible and has a high binding capability. [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 propellant. Nitrocellulose burns cleanly with non-toxic combustion byproducts, such as nitrogen, carbon dioxide, and water vapor. In the fireworks industry, nitrocellulose is typically utilized as an energetic binder in a lacquer form, added to pyrotechnic compositions. [0005] Nitrocellulose is manufactured from cellulose, which has the chemical formula C.sub.6H.sub.10O.sub.5, and which is the principle structural component of cell walls in higher plants. An almost pure form of cellulose, known as alpha cellulose, occurs naturally in cotton fibers. The physical properties of cellulose are a result of an association of cellulose chains which form crystalline structures called microfibrils, typically having a diameter of 2-20 nm, a length of between 100-40,000 nm, and which contain about 2000 cellulose molecules. Within a plant cell, the orientation of microfibrils changes from layer to layer. Often, especially in very strong plant cell walls, the microfibrils are arranged screw-like about an axis of the cell, with changes in the turning angle from layer to layer. [0006] Nitrocellulose is produced by the well known process of nitrating cellulose with a mixture of concentrated acids including nitric acid, which has the chemical formula HNO.sub.3. During the resulting chemical process, the nitric acid converts the cellulose into cellulose nitrate, having the chemical formula of C.sub.6H.sub.9O.sub.5(NO.sub.2), C.sub.6H.sub.8O.sub.5(NO.sub.2).sub.2 or C.sub.6H.sub.7O.sub.5(NO.sub.2).sub.3 depending on the degree of nitration. Sulfuric acid generally is used in conjunction with the nitric acid during the nitrating process to prevent the water produced in the reaction from diluting the concentration of nitric acid. [0007] As a product of cellulose, nitrocellulose retains the general physical properties of cellulose. The most problematic physical property of cellulose is it's low bulk density. Essentially, cellulose crystals are microscopic hollow fibrous tubes. The fibrous nature of cellulose results in a light, fluffy material which is not easily compressed. Nitro cellulose retains these characteristics, and to some degree, enhances the fibrous nature of the resulting product by stiffening and strengthening the cellulose fibers during the nitration. [0008] Pyrotechnic and explosive compositions are typically fairly dense mixtures of crystalline salts for flame color, crystalline oxidizers, carbonaceous fuels, and powdered metals. The flame coloring agents are commonly metal salts of barium, strontium, iron, copper, boron, calcium, antimony, potassium, sodium, cadmium and lithium. The oxidizing agents may include at least one compound selected from a group consisting of ammonium perchlorate, alkali metal perchlorates, alkali metal chlorates, and alkali metal nitrates. Additional fuels may include carbon, titanium, titanium alloys, zirconium, zirconium alloys, iron, alloys of iron, magnesium, alloys of magnesium, aluminum and alloys of aluminum. These materials are easily solidified with binders, agglomerated, or compressed, to form pellets or granules. Most of the current pyrotechnic and explosives processing techniques rely upon the dense nature of these materials and the ability to form these materials into pellets by compression in a variety of presses. [0009] Nitrocellulose is very difficult to consolidate in this manner due to a low bulk density of approximately 0.2 gm/cc. Typically, nitrocellulose is either fully dissolved with a solvent or partially colloided with a plasticizer. Colloided materials are manufactured by partially or fully dissolving the nitrocellulose and mechanically reforming it into desired shapes and densities. This process breaks down the fibrous nature of the nitrocellulose, allowing it to be formed, molded, and extruded into a variety of shapes. One of the most commonly utilized colloiding agents is nitroglycerince, such as is used in the conventional manufacture of smokeless gunpowder. However, the addition of solvents to nitrocellulose alters the basic chemistry of the nitrocellulose, and most of the commonly used plasticizing agents are unsuitable for use in pyrotechnics. While such alterations to increase the plasticity of the nitrocellulose may be suitable for the manufacture of smokeless gunpowder, they are not desirable for use in the pyrotechnics industry. [0010] Accordingly it would be advantageous to develop a method for manufacturing a nitrocellulose product which exhibits the plastic characteristics of colloided nitrocellulose, suitable for forming, molding, or compacting, but which is not chemically altered. BRIEF SUMMARY OF THE INVENTION [0011] Briefly stated, an embodiment of the present invention provides a chemically unaltered nitrocellulose product for use in an energetic high-nitrogen fuel, which exhibits the plastic characteristics of colloided nitrocellulose, and which is suitable for forming, molding, or compacting. [0012] In an alternate embodiment of the present invention, microcrystalline cellulose produced from alpha cellulose, and consisting of aggregates of micro-crystals which many dislocations and slip planes capable of fracturing and realigning under compression, is then nitrated with nitric acid. The nitration processes converts the microcrystalline cellulose into microcrystalline cellulose nitrate, or microcrystalline nitrocellulose (MCNC) having the chemical formula of C.sub.6H.sub.9O.sub.5(NO.sub.2), C.sub.6H.sub.8O.sub.5(NO.sub.2).sub.2 or C.sub.6H.sub.7O.sub.5(NO.sub.2).sub.3 depending on the degree of nitration, while retaining the mechanical properties of the microcrystalline cellulose. [0013] The foregoing and other objects, features, and advantages of the invention as well as presently preferred embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0014] In the accompanying drawings which form part of the specification: [0015] FIG. 1 is a flow chart illustrating the steps of a method of the present invention; and [0016] FIG. 2 is a cross-sectional view of an exemplary caseless projectile cartridge of the present invention. [0017] Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. DESCRIPTION OF THE PREFERRED EMBODIMENT [0018] The following detailed description illustrates the invention by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the invention, describes several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently believed to be the best mode of carrying out the invention. Continue reading about Method for manufacture of microcrystalline nitrocellulose... 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