| 摘要 |
Loss of strength during the saponification of filaments, yarns, fabrics, and other materials made of cellulose acetate or other organic esters of cellulose, is avoided by the use of saponifying media containing oils. The oils used may be of mineral, vegetable or animal character; or soluble oils such as sulphonated castor oil &c. may be employed. The insoluble oils may be emulsified in aqueous saponifying media, such emulsification being assisted, if desired, by emulsifying agents, the use of soaps of inorganic or organic bases being particularly advantageous in this connection since these also exert a desirable buffer effect on the saponification reaction. Alcoholic or aqueous alcoholic saponifying media may also be used, and with alcoholic media the amount of alkali present may be, as described in Specifications 125,153 and 313,404, [both in Class 2 (ii), Cellulose &c.], less than that theoretically necessary. The saponifying agent may be caustic alkali, an alkaline salt or an organic body such as an amine or an hydroxy amine; the concentration of the saponifying agent, the temperature of the saponifying medium and the duration of the treatment may be varied, and they depend on the manner in which the saponification treatment is carried out, that is, by immersion of the materials in the form of hanks, cakes or other packages, or by treatment of the materials while travelling; the saponifying medium may be applied intermittently or to parts only of the materials; the action of the saponifying agent may be assisted by the presence in suspension of lime, baryta, barium or calcium carbonates, &c. as described in Specification 402,106; the saponifying medium may contain a solvent or swelling agent for the materials, or the latter may be treated while in a swollen condition; and the materials may be wetted out before subjection to the saponification treatment. The materials may be subjected to a stretching operation before, during or after the saponification treatment. The cellulose esters contained in the materials may be of high or low viscosity. In examples the following baths are employed--aqueous caustic soda containing turkey red oil; a homogeneous aqueous mixture containing triethanolamine, oleic acid and olive oil; and an emulsion of light mineral oil in soap solution containing caustic soda. Specifications 277,089, 316,521, 318,468, 323,790, 332,263, [all in Class 2 (ii), Cellulose &c.], 340,324, 340,325, 340,326, 340,436, 340,437, 343,062, 370,040, 370,430, 371,461, 371,910, 378,858, 400,938, and 402,104 also are referred to. |
