Patent GB-510083-A (GB)
Title: Improvements in treating cellulosic materials
IPC: D06M13/432
Filed: 1938-01-21
Abstract: 510,083. Dyeing processes; treating natural and artificial textiles, films, and paper with liquids. TOOTAL BROADHURST LEE CO., Ltd., BANCROFT, J., FOULDS, R. P., and ROSCOE, W. E. Jan. 21, 1938, Nos. 1985 and 11133. [Classes 2 (ii) and 15 (ii)] [Also in Group VIII] Parchmentized effects are produced on cellulosic textile materials including cellulose acetate materials but especially cotton, rayon of all kinds, and linen, in the form of fibres, yarns, filaments, or fabrics, by treating them with strong sulphuric acid in which formaldehyde, or a substance liberating formaldehyde, and urea have been dissolved before application of the acid to the materials. The materials are in general brought to air-dry condition before being treated with the acid. The solution may contain at least 2 per cent. by weight of formaldehyde and urea calculated on the weight of acid. Transparent, stiff, deeper dyeing, and other parchmentizing effects are obtained. Paraformaldehyde may be added to the sulphuric acid and urea may be dissolved in the mixture. The textile material is then treated at room temperature. The treating solution may be obtained by dissolving mono-, or dimethylol urea or methylene urea in the sulphuric acid. One or more treatments may be carried out and the treatment may be preceded or followed by a treatment with parchmentizing acid not containing urea and formaldehyde. The proportion of the added substance may be such that precipitation of methylene urea takes place during washing with water or treatment with the acid solution so that the material becomes opaque or delustred. Pattern effects may be obtained by printing cloth, before the ' treatment, with wax or other resist, or the cloth may be given a pattern by means of an embossing calender prior to the acid treatment. The embossed portions are less susceptible to the action of the acid. Any precipitation of methylene urea takes place to a greater extent in the unembossed portions, so that the embossed pattern is stiffened and stands out white or opaque in contrast to the transparent parchmentized portions. If desired, a dye or dye component, pigment, or colouring matter may be dissolved or dispersed in the sulphuric acid with the urea and formaldehyde. Dyes sold under the Registered Trade Marks " Caledon," " Indanthrene," and " Monastral," may be used. Coloured pattern effects may be obtained by printing methods with or without a resist, or by all-over treatment of a cloth or yarn bearing an embossed pattern, the embossed portions being less sensitive to the dye. Differential colour effects may be obtained. In an example, a solution of 81 per cent. H2SO4 containing paraformaldehyde has urea added to it, the temperature being kept low. A small addition of Monastral Blue is then made. A cotton fabric with an embossed pattern is immersed in the solution for a short time and then washed. The embossed portion shows opaque and almost white in contrast with the other portion which is blue and more parchmentized. The Provisional Specification includes the treatment of paper, and films.