GB433911A - Improvements in the manufacture of artificial straws and the like - Google Patents

Abstract

In a process for the production of straw-like material a heavy artificial filamentary product formed from a spinning solution containing a cellulose derivative and a plasticizer therefor is subjected to an operation of moulding under heat to produce permanent irregularities of shape such as crinkles, twists, partial twists, patterns or frizzed effects therein. The heavy artificial filamentary product may be formed by coalescing a number of fine filaments with a total weight of about 75 denier. The invention is of particular importance with straws of 500--2000 denier or more. The filamentary product may contain any cellulose derivative, together if desired with other materials such as cotton or wool incorporated with the cellulose derivative by means of solvents and pressure. The plasticizer preferably acts as a solvent for the cellulose derivative at elevated temperatures. Suitable plasticizers are e.g. triphenyl or tricresyl phosphate, paratoluene sulphonamide, triethylene glycol, diethylene glycol, triacetin, diacetin, dibutyl tartrate and mixtures thereof. The plasticizer may be incorporated to the extent of 5--40 per cent of the weight of the straw. The moulding of the product may be performed by passage between presses or between a flat surface and a roll or between nip rolls one or both of which are heated, and serrated, grooved or patterned. The rolls may be heated by steam, hot water, electrical resistance, open flames, &c., the heat preferably being sufficient to cause the plasticizer to act as a solvent for the cellulose derivative. The product may be supplied to the rolls in semi-plastic condition by passing it first through a heated bath of non-solvent or mildly solvent liquid, and may be subjected to steam or hot water during moulding by submerging the moulding apparatus in a steam or hot water bath. Suitable moulding temperatures usually range from 125--225 DEG C. For a bright product the temperature should be just sufficient to render the material plastic but for a delustred straw the temperature should be sufficient to cause a rapid evaporation of one of the constituents, preferably a volatile plasticizer, of the filamentary product. Thus when employing a product containing 20--40 per cent of triphenyl or tricresyl phosphate a bright straw is obtained by moulding at 150 DEG C., while temperatures round about 200 DEG C., give a duller straw. Preferably a minimum of tension is used in winding up the straws, but cooling rolls or currents of air employed between the moulding device and the winding device permit tight package to be wound at any tension. A series of nip rolls having the same or different surfaces may be employed. Instead of or in addition to using pressure, the product in a flattened condition may be moulded by twisting either continuously in one direction or at intervals alternately in opposite directions. Fabrics may be formed from the straw like materials. According to the Specification as open to inspection under Sect. 91 the plasticizer may be added to the filamentary product with the aid of swelling agents such as ethylene glycol, mono-ethyl ether, or of heat, or may be applied to the formed product in a molten form or from a solution by means of wicks, rollers and the like. This subject-matter does not appear in the Specification as accepted.