| 摘要 |
"Densified" nitrocellulose particles are produced by forming a slurry by agitating water-moist nitrocellulose fibres free from fibre aggregates in a mixture of a volatile hydrocarbon diluent, a volatile nitrocellulose solvent miscible in all proportions therewith and a small proportion of a water-soluble protective colloid, the mixture of diluent and solvent being capable of softening and swelling the nitrocellulose fibres but not of dissolving them and the solvent being soluble in water at ordinary atmospheric temperatures to the extent of at least 2.5% by weight, subjecting the slurry to high shear action until the softened and swollen fibres break down into smooth surfaced rounded particles, initiating the hardening of the particles by dilution of the slurry with the hydrocarbon diluent while the high shear agitation is continued, and finally removing substantially all of the nitrocellulose solvent and water by azeotropic distillation in the presence of hydrocarbon diluent (in a proportion sufficient to prevent resoftening of the particles) to complete the hardening and densification of the nitrocellulose particles. The diluent may be a volatile petroleum hydrocarbon or mixture of volatile petroleum hydrocarbons, for example heptane in a petroleum distillate boiling between 190 DEG and 240 DEG F. preferably between 201 DEG and 217 DEG F. The nitrocellulose solvent may be methyl ethyl ketone and the nitrogen content of the nitrocellulose may be about 11% by weight or over 12.6% by weight. The initial ratio (by weight) of the diluent to the solvent in the slurry may be between 1.0 and 1.2. |
