GB624987A - Improvements in and relating to the manufacture of alginate threads - Google Patents

Abstract

A continuous spinning process for the production of alginate threads comprises projecting an aqueous alkali alginate solution having a pH of less than 9.5 into a neutral bath made up from an alkaline earth metal salt and water substantially free from temporary hardness, passing the thread thus formed to a series of thread-advancing devices for subsequent treatment, including washing and drying, and, prior to drying, treating the thread with a cation-active compound. The neutral bath is defined as one of pH range of the order of 5 to 8.5. It should contain no mineral or organic acid other than the very small quantity of carbon dioxide normally dissolved in aqueous solutions, and no carbonates or hydroxides other than a small quantity of dissolved calcium carbonate not exceeding 5 parts per 100,000 by weight. The washing of the formed thread is preferably carried out with demineralised water, i.e. water containing less than 8 parts of total solids and less than 1 part of calcium salts per 100,000 parts by weight. The cation-active compound, e.g. cetyl pyridinium bromide may be added to the spinning solution or the washing bath, but is preferably applied after the washing, e.g. by passing the thread over a wick on to which a solution of the compound is dropped so that the thread takes up about 2 per cent of the compound based on the weight of the dried thread. The thread-advancing devices may be of the kind in which the thread is advanced axially along the device while travelling helically. Specifications 319,793, [Class 120 (iii)], 385,477, 475,023, 567,641, 568,177, 571,657 and 605,826 are referred to.