Patent GB-370430-A (GB)
Title: Improvements in the treatment of filaments, yarns, ribbons, and the like, made of orcontaining cellulose esters or ethers
IPC: D01F2/28
Filed: 1930-12-20
Abstract: <PICT:0370430/IV/1> <PICT:0370430/IV/2> <PICT:0370430/IV/3> Filaments, threads yarns, warps, and ribbons of cellulose acetate or other esters or ethers of cellulose are softened and subjected to at least two stages of stretching, the tension between at least two of the stages being substantially removed whilst retaining the plasticity or softness of the products.  The filaments may be treated with a solvent or swelling agent before the first stretching only, or also before any of the subsequent stretchings. Aqueous solutions of thiocyanates of the alkalis, ammonia, or alkaline earths; zinc chloride solutions; acetic acid, formic acid, lactic acid, diacetone alcohol, acetone; ethers and esters of olefine glycols such as mono- or di-methyl or ethyl ether of ethylene glycol, dioxane, ethers of propylene glycol, mono-ethyl ether of diethylene glycol, glycol mono-acetate, methyl glycol mono-acetate, phenols, formaldehyde, acetaldehyde, acetins, dichlorethylene, ethylene chloride, or methylene chloride may be used as softening agents.  The softening agent may be applied in aqueous solution, or in solution in benzene or other hydrocarbon. The softening agent or solvent may be incorporated in the spinning solution.  In the stretching operations, it is preferable to allow a rest period between the first and second and between the second and third stages and then if more stages are applied, to stretch without intermediate rest periods.  The threads may be treated in hanks, or while travelling from bobbin or beam to bobbin or beam or from a dry or wet spinning apparatus to a winding device.  The successive stretches may be applied during a single travel, or the material may be reeled between successive stretches. For treatment of hanks, a long bath containing the softening agent is used.  This bath is preferably lined with copper.  A long screw fitted with hand-wheel or power drive is arranged longitudinally along the top of the bath.  Two rollers, one fixed in relation to the length of the bath, and the other adjustable by means of the screw dip into the bath and carry the hanks.  The rollers may be rotated during the stretching operation.  This may be effected by the screw which regulates the distance between the rollers, by gearing it to one or both of the rollers.  In treating threads during travel from one point to another, the softening agent may be applied while they are in bobbin, cheese, pirn or cake form, and the package may be immersed in the liquid or treated with the vapour of the reagent, or if the threads are wound on perforated tubes, the reagent may be forced or sucked through the package. Between successive stretchings, the thread may be allowed to hang loosely or may be piled, or the rest period may be allowed to take place between successive rollers rotating at the same speed. Where looping takes place, a faller roller may be arranged in each loop to maintain a light tension and retain the threads in position.  When using single rollers at the end of each stretching stage, the threads may be lapped round the rollers to prevent slipping and to allow the tension to be released between successive stages.  When the materials have been treated with concentrated swelling agents, it is preferable to wash with solutions of the swelling agents at gradually decreasing concentration.  The treatment is applicable to threads of cellulose acetate, formate, propionate, or butyrate, or ethyl, methyl, or benzyl cellulose.  As shown in the drawings, yarn or filaments from a bobbin or spinning apparatus are passed round a series of rollers 9 . . 15 mounted in a bath 6 containing a softening liquid.  The filaments are stretched in stages by making the speed of roller 10 greater than roller 9, that of roller 11 being equal to that of roller 10 but less than that of roller 12. A rest period is permitted between rollers 12 and 13, and two further stages of stretching are effected by means of rollers 14, 15.  After leaving the bath, the filaments are sprayed with washing liquid.  Instead of lapping the threads round a series of rollers, they may be passed between a series of nip-rollers, this method being preferred when treating threads in warp formation. For relieving the tension during a rest period, the threads may be passed over a roller 22, Fig. 3, provided with two jockey rollers 24, 25 mounted on a saddle 23.  for economy of space, the series of stretching rollers may be arranged in epicyclic relation to and driven by a common cog wheel 26, fig. 4, the gearing for successive rollers being adjusted so as to impart stretching in stages with one or more stages of no stretch.  Specifications 277,089, 323,790 and 336,217, [all in Class 2 (ii), Cellulose &c.], are referred to.