Fabrics of which the warp is sized with water-soluble polymers of acrylic acid and/or their alkali metal salts or ammonium salts, are desized by treating the sized fabric with from 30 to 300 percent by weight of water, based on the dry weight of the fabric, and separating the resulting size solution from the fabric. The recovered size solution can be directly re-used for sizing.
A process for desizing a fabric web comprising the steps of: first wetting the dry size-loaded fabric with the desizing liquor separated from a previous batch of fabric after desizing, so that the fabric, and the size adhering thereto, take up water from the desizing liquor by swelling and/or solvation, thereby increasing the concentration of the desizing liquor; separating the concentrated desizing liquor from the fabric; recycling the concentrated desizing liquor to a sizing operation; desizing the wetted fabric by a continuous fresh water wash; separating the desized fabric from the resulting desizing liquor; and recycling the desizing liquor to the first wetting step.
A process for continuously washing a printed textile sheet-like structure, wherein water or a wash liquor is applied to the goods so that they entrain from 80 to 500% of water, based on the weight of the goods, the goods are then squeezed off between rollers so as to remove at least 30% of water, based on the weight of the goods, and the surface-swollen print paste residues are transferred from the goods to the roller, from which they are removed by means of water. The treatment can be repeated one or more times, and a conventional afterwash can be carried out if appropriate. The process is cheaper than conventional processes and only slightly affects the color of the unprinted areas.
In addition to the very time-consuming enzymatic and hydrolytic desizing processes, oxidative degradation of starch size by means of persulfate, to render the starch water-soluble, is conventionally practised. Because of the chemical similarity between starch and cellulose, oxidative degradation of the cellulose is unavoidable in this desizing process. The invention overcomes this problem by breaking up the macromolecules of the starch into dispersible fragments by means of such small amounts of persulfate that neither is the starch made water-soluble nor is the cellulose significantly damaged, the dispersants employed for the fragments being relatively oxidation-stable polymers of unsaturated carboxylic acids.
An economical process for reducing water consumption and, therefore, water discharge during the dyeing of textile goods is disclosed. Processing baths during dyeing, which can be reused directly or after minimal treatment, are segregated from baths which contain a high level of pollutants and color. The reuse baths are combined and stored separately from baths which are to be discharged. The reuse baths are then recycled directly or after minimal treatment to the dyeing process. Baths containing a high level of pollutants and color are either discharged directly to the local public treatment works or are treated in a conventional wastewater treatment plant. The process results in substantial economic benefits because the operating costs of recycling reuse baths are low and because the quantity of wastewater discharged is substantially reduced.
