| 摘要 |
The process described in the parent Specification according to which the lustre of artificial filaments, yarns, films, &c. is reduced by incorporating therein insoluble organic fibrous material, including regenerated cellulose and cellulose derivatives, in a finely divided state, is modified either by the employment of an organic fibrous material reduced to a fine state of subdivision by precipitation in a liquid medium, or by the use of finely divided cellulose benzoates in particular dibenzoyl cellulose as the delustring agent. The cellulosic material to be afterwards precipitated, may be dissolved in sulphuric acid, zinc chloride, thiocyanates, cuprammonia solution etc.; or it may be converted into viscose and subsequently precipitated from such solution. Precipitation may be effected by heat, by chemical action, or by dilution as with water and other non-solvents; thus, from a zinc chloride solution, cellulose may be precipitated by water, dilute acids, alcohol &c., from cuprammonia solution by salts, acids, alkalies, sugar &c., from viscose by acid reagents, and from a solution of dibenzoyl cellulose, the latter may be precipitated by a non-solvent such as a hydrocarbon or ether. Any residues of zinc in the cellulose precipitated from zinc chloride solution may be removed by dilute acids, and similarly copper may be removed from the cellulose obtained from cuprammonia solutions. The necessary subdivision of the cellulose or cellulose derivative during the process of precipitation may be effected by agitation or stirring as by mechanical means or by means of liquid jets or by introducing a gaseous precipitating agent through spray nozzles; and precipitation may be carried out in the presence of dispersing agents such as organic sulphonic acids, gelatine, glue &c. In examples, a solution of cellulose in sulphuric acid is diluted with water to the point of precipitation whereupon it is projected as a spray into sodium sulphate solution under vigorous agitation producing a cellulose suspension which is subsequently dialysed and then transferred to acetone for addition to a cellulose acetate spinning solution; a solution of dibenzoyl cellulose is sprayed into an excess of alcohol, and the resulting finely divided product incorporated in a viscose spinning solution. |
