Patent GB-537519-A (GB)
Title: A process for the nitration of structures of regenerated cellulose and for the production of patterned etching effects using yarns thereof
IPC: D06M13/188
Filed: 1939-12-29
Abstract: 537,519. Nitrating cellulosic textile &c. materials; treating artificial silk &c. with liquids ; dyeing processes. HEBERLEIN & CO. AKT.-GES. Dec. 29, 1939, No. 33029. Convention date, Jan. 5. [Classes 2 (ii) and 15 (ii)] Structures of regenerated cellulose, e.g artificial silk yarns or woven fabrics of regenerated cellulose are subjected, under conditions such that the character and structure of the initial materials are maintained, to nitration treatment with nitric acid in presence of aliphatic carboxylic acids, such as glacial acetic acid, which are only attacked with difficulty, if at all, by nitric acid at ordinary temperature and are miscible therewith. Spun yarn, filaments, twist, threads, fabrics, artificial straw, films, membranes, bands, or other articles of cellulose regenerated from viscose, ammoniacalcopper solutions, or other cellulosic solutions, may be subjected to the treatment. The nitrating solution may be a mixture of one volume of nitric acid of 48‹ BÚ with three volumes of glacial acetic acid, or it may be more concentrated and may be as strong as three volumes of nitric acid with one volume of acetic acid. The time of treatment may be a few seconds or several hours depending upon the strength of the nitrating mixture and the degree of nitration desired. Instead of acetic acid there may be used propionic, butyric, or chloracetic acids. Colour effects may be obtained on mixed fabrics or other articles since nitrated regenerated cellulose may be dyed with basic dyes and when it is of low nitrogen content it dyes more deeply with substantive dyes than regenerated cellulose. Nitrated regenerated cellulose structures may be denitrated locally and then treated with basic dyes so as to give colour effects. Partially denitrated and bleached materials of nitrated regenerated cellulose are more readily parchmentized than regenerated cellulose and parchmentized effects may thus be obtained. Fabric containing natural cellulose threads, e.g. cotton, or difficultly nitratable artificial threads and readily nitratable regenerated cellulose threads may be subjected to the nitration treatment so that the latter threads become soluble in alkali whereas the other threads remain insoluble in alkali. The fabric is then treated locally with alkali so as to produce patterned effects similar to those obtainable by weaving. Difficultly nitratable artificial threads may be those in which matting pigments or dyes have been incorporated in the spinning solution. In an example, viscose fabric is treated with nitric acid and acetic acid, denitrated locally by the application of a printing paste of sodium hydrogen sulphide and gum, and then dyed with Rhodamine 3 G.O. In another example, regenerated cellulose film is treated with nitric and acetic acids, printed with a paste of caustic soda and gum, steamed and washed. Fabric consisting of cotton warp threads and cotton and viscose weft threads is treated with nitric and acetic acids, printed with a paste of soda lye and gum, and steamed. If desired the remaining nitrated threads may be denitrated with sodium hydrogen sulphide, and the fabric may then be subjected to parchmentizing or dyeing treatments so as to obtain further pattern effects. Specification 262,477, [Class 15 (ii)], is referred to.