GB367896A - Improvements in spinning of artificial filaments, threads, ribbons and the like - Google Patents

Abstract

Artificial filaments, yarns, threads, ribbons, straw, &c. are produced by extruding a solution containing an organic derivative of cellulose, a di- or polyhydric alcohol or a derivative thereof and an oleaginous substance into a coagulating medium such as a coagulating liquid or an evaporative atmosphere. The extruded products may be drawn down or stretched to produce filaments of low denier, e.g. 1,8 to 1,5 or less; and yarns produced from the filaments are very pliable and may be knotted closely without further lubrication: artificial straws, ribbons, &c. so obtained may be knitted or sharply bent without showing any tendency to break. Di- and polyhydric alcohols and derivatives which may be employed include ethylene glycol, diethylene glycol, glycerol, and diglycerol; ethers such as the mono- and di-methyl-, ethyl- and butyl-ethers of ethylene glycol; and esters such as monoacetin and diacetin and the acetic acid esters of diglycerol, diethylene glycol, or ethylene glycol. These compounds may be added in an amount from 2-20 per cent of the weight of the cellulose derivative. Suitable solvents for the spinning solution include acetone, alone or mixed with water or ethyl or methyl alcohol, or mixtures of methylene chloride or ethylene dichloride with ethyl or methyl alcohol. The oleaginous substances include glycerides, e.g. olein or stearin; free fatty acids, e.g. oleic or stearic acids; olive, castor, or coco-nut oils or the free fatty acids derived therefrom; mineral oils, e.g. kerosene, gasoline, mineral lubricating oils, petroleum jelly, &c. These substances may be added singly or in admixture, generally in an amount 2-20 per cent of the weight of the cellulose derivative. Examples of organic derivatives of cellulose include cellulose acetate, especially acetone-soluble varieties, and other esters, e.g. cellulose formate, propionate, and butyrate; and ethers, e.g. ethyl, methyl, and benzyl cellulose. The spinning solutions may contain 15-30 per cent by weight of the cellulose derivative. The solution is spun through nets having a suitable number of orifices; for filaments, circular orifices 0,04-0,15 mm. diameter may be used; for artificial straw, the orifices may be in the form of slits. For fine filaments, the filament may be drawn down or stretched during formation by suitable mechanical means, e.g. rollers running at progressively increasing peripheral speeds. In an example, a spinning solution is prepared by dissolving 1 part of an acetone-soluble cellulose acetate having an acetyl value of 54-55 per cent in 3 parts of a solvent mixture comprising 95 parts acetone and 5 parts methyl alcohol. Ethylene glycol and olive oil each in amount equal to 5 per cent of the weight of cellulose acetate are then added and after thorough mixing and filtration the solution is extruded into a drying evaporative atmosphere to form filaments which are stretched by rollers. Filaments having a denier of 1,5 may be obtained. In a second example the solvent mixture comprises acetone 95 parts and water 5 parts, and the amount of olive oil is increased to 10 per cent; filaments having a denier of 1,7 may be obtained. Specification 313,885, [Class 2 (ii), Cellulose &c.], is referred to. The Specification as open to inspection under Sect. 91 (3) (a) describes also the production of filaments &c. by extruding a solution of an organic derivative of cellulose containing a di- or polyhydric alcohol or derivative thereof; and includes three examples involving spinning solutions comprising cellulose acetate dissolved in aqueous or alcoholic acetone solvent mixtures with an addition of diethylene glycol. This subject-matter does not appear in the Specification as accepted.