GB875112A - Improvements in or relating to densification of nitrocellulose - Google Patents

Abstract

The process of the parent Specification (wherein cast double-base propellant grains are prepared by agitating fibrous nitrocellulose in an aqueous bath containing an active organic solvent for the nitrocellulose, the solvent being present in a proportion based on the water-solvent mixture to soften and destroy the fibrous structure of the nitrocellulose without dissolving it, and continuing agitation with removal of all the solvent until smooth, hardened, densified and irregular particles of the nitrocellulose are obtained) is modified in that the active solvent used forms a minimum boiling azeotropic mixture with water, and that the bath is heated to at least the boiling point of the mixture during the entire period of contact between the nitrocellulose and the solvent, substantially all the solvent being thereafter removed by distillation while continuing agitation until the nitrocellulose is formed into smooth particles. The solvent may be ethyl or butyl acetate, or methyl ethyl or methyl isobutyl ketone. A list of additional solvents which may be used is given. In an example, 105 parts (dry basis) of fibrous water-wet nitrocellulose is slurried with 945 parts of water, the slurry heated to 82 DEG C. and agitated in a vapour-tight vessel fitted with a reflux condenser, 111 parts of methyl ethyl ketone are added, and a mixture of the solvent and water is distilled off while agitation is continued, the final temperature being 100 DEG C.