GB1026814A - Nitrocellulose - Google Patents

Abstract

Propellant powder comprises disc-shaped particles of nitrocellulose made by slicing an extruded rod of nitrocellulose lacquer. The nitrocellulose may contain stabilizers, deterrents and high-energy compounds such as triethylene glycol dinitrate, penta-aerythritol tri-nitrate, dinitrotoluene, nitroglycerin, dibutyl phthalate, diphenyl phthalate, diphenylamine, 2-nitro-diphenylamine, and ethyl centralite; modifiers such as lead compounds, carbon black, and powdered aluminium; and protective colloids such as starch, gum arabic, animal bone glue, dextrin and bentonite. Porous discs of sp. gr. 0.6-1.1 are obtained by adding a metal salt to the lacquer before extrusion, the salt being removed during subsequent processing.ALSO:Disc-shaped nitrocellulose particles are made by dissolving wet nitrocellulose in a solvent therefor which is immiscible or partly miscible with water and has a lower boiling-point than water to form a lacquer having a viscosity, as defined, of 12 to 100 seconds at 60 DEG C., extruding the lacquer through at least one orifice into an aqueous non-solvent medium, cutting disc-shaped sections from the extruded lacquer as it emerges from the orifice while in contact with the non-solvent medium to form a suspension of lacquer sections therein, heating the suspension to evaporate solvent from the lacquer sections while retaining their disc-like shape, and separating the resulting solid disc-shaped particles of nitrocellulose from the suspension. The nitrocellulose lacquer contains enough water, e.g. 3 to 30% by weight of nitrocellulose, to form emulsified water droplets without forming a separate aqueous phase. Water may be added to the lacquer if the water content of the nitro-cellulose is insufficient. Specified solvents are ethyl acetate, methyl ethyl ketone, ethyl formate, isopropyl acetate, diethyl ketone and mixtures thereof. The lacquer may also contain stabilizers, e.g. diphenylamine and 2-nitrodiphenylamine; deterrents such as dinitrotoluene, dibutyl phthalate and diphenyl phthalate, modifying agents such as lead compounds, carbon black and powdered aluminium, and protective colloids such as starch, gum arabic, animal bone glue, dextrin and bentonite. Many organic water-insoluble diluents for the lacquer are specified. The lacquer may also contain triethylene glycol dinitrate, pentaerythritol trinitrate, and nitroglycerine. The lacquer and/or aqueous non-solvent medium may contain a water-soluble metal salt, for the purpose of reducing the S.G. of the final nitrocellulose particles. Specified salts are Na2SO4, K2SO4, NaNO3, KNO3, Mg(NO3)2 and Ba(NO3)2. The salt may be added to the non-solvent medium either prior to cutting the extruded lacquer rods or prior to removal of solvent from the discs. The lacquer is preferably extruded at 60-65 DEG C. into a non-solvent medium, agitated only by the cutter blade. The discs may be recovered by filtration, dried and coated with one of the above deterrents or modifiers. The process may be batchwise or continuous.