US2304212A - Spinning artificial silk - Google Patents

Description

8, 9 P. F. c. SOWTER ETAL 2,304,212

SPINNING ARTIFICIAL SILK Filed March 11, 1941 INVENTORS PECSOWTER PW) W.DD. HARRIES ATTORNEYS Patented Dec. 8, 1942 SPINNING ARTIFICIAL SILK Percy Frederick Combe Sowter and William Dan Douglas Harries, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware Application March 11, 1941, Serial No. 382,680

' In Great Britain April 25, 1940 8 Claims. (01. 18-54) This invention relates to the centrifugal spinning of artificial silk, and is particularly concerned with facilitating removal of cakes of yarn from spinning-pots.

In the centrifugal spinning of wet yarn o artificial filament it is desirable that the spun cakes should be removed from the spinning-pot as soon as possible after dofiing. A delay of only one day in freeing the cakes from the pots results in the hold-up of several pots per spindle, while to dry the cakes in the pots might, owing to the limited amount of surface exposed, take a week or more. In the case of cellulose acetate or other cellulose ester or. ether yarns difficulty is found in obtaining a quick and easy release of the cakes from the spinning pots, .in spite of the walls of the pots being usually provided with a sharp taper. This is especially true of such yarns as have been prepared by extrusion of the spinning solution into a coagulating bath containing a high concentration of a solvent for the cellulose ester or ether, and maybe by subjecting the yarn to stretching, as described, for example, in U. S. Patents Nos. 2,147,640 and 2,086,122. Thus, it is found that a cake of cellulose acetate yarn which has been produced using aqueous diethylene-glycol diacetate, as the coagulant, cannot be removed from the pot without damage even after standing several days.

The close adhesion of the yarn to the spinning pot is probably due to the perfect contact set up between the soft yarn and the walls of the pot. Air is excluded and a suction effect is obtained on attempting to withdraw the cake. With a viscose yarn the problem is not so acute since 1 the cake readily shrinks from the Walls of the spinning-pot after standing for a short time.

It has now been found that removal of the cake of yarn from the spinning-pot is facilitated by running into the spinning pot an additional end of yarn, preferably coarse, dry yarn, at the commencement of spinning, the additional yarn conveniently being run together with the wet yarn. The supply of this additional yarn can be stopped after a short time, for example 30-60 seconds. In this way, a relatively coarse layer of doubled yarn is formed at the surface of the cake adjacent to the wall of the spinning-pot. The surface is thus broken and the suction effect produced on attempting to remove the cake'is avoided. a

Best results are obtained using as the additional yarn one of heavy denier compared with the. wet spun yarn. Thus, a dry yarn of about for dOllbling with a freshly spun yarn of about 100- 50 denier.

It is desirable that the additional yarn should.

be of-a smooth character such as obtains in continuous filament yarns, for example yarns of dryor wet-spun cellulose acetate or other cellulose derivative, or natural silk. Yarn made from staple fibres, e. g., Wool or cotton, is not generally satisfactory .slnce it is apt either-to adhere to the Walls of the pot or to form "bridges in the cake, 1. e., lengths of yarn drawn tight inside the spinning pot so as to form a chord to the circle of which the main cake of yarn is the circumference. Its springy nature makes wool 3, yarn particularly prone to this latter defect.

One, two or more ends of the additional yarn can be doubled in; for example the formation of the cake may be started by running into the spinning funnel two ends of dry 300 denier cellulose acetate yarn with each freshly spun end of 100*150 denier cellulose acetate yarn. emerging from the coagulating bath. The dry ends can be broken out after 30-60 seconds, i. e. after the first few metres of freshly spun yarn have been taken up in the spinning-pot. The doubled yarn thus formed at the surface of the cake considerably facilitates the removal of the latter from the spinning-pot.

If desired, a heavier coating of doubled yarn than is strictly necessary to facilitate removal of the cake from the pot may be provided. This wet spun yarns Whether derived from cellulose apparatus;

and its derivatives or from synthetic fibre-forming polymers, for example polyhexamethylene adipamide.

The accompanying drawing shows diagrammatically the carrying-out of the invention,

Fig. 1 being a side elevation of a wet-spinning Fig, 2 a cross-section through a spinningpost in which winding of the cake has been completed; and

Fig. 3 a view similar to Fig. 2 showing the removal of the cake from the inverted pot.

In Fig. 1, a Wet-spun cellulose acetate thread l is drawn from the spinning apparatus 2 by a feed roller 3 and delivered to a spinning-pot 4 300 denier has been found to be very satisfactory 55 through a funnel 5. A conveniently placed bobbin 6 enables a thread I of dry cellulose acetate (e. g., 2-fold 140-150 denier) to be run into the pot 5 along with the thread i at the beginning of the winding operation. In 30-60 seconds, a layer 8 of the coarse material formed by the two threads l, l is built insidethe pot. l is then broken and the thread I is built into the cake 9 inside the layer 8.

As Fig. 2 indicates diagrammatically, the coarse thread forming the layer 8'prevents the outer surface of the cake 9 from making very intimate contact with the inside surface of the pot 4. Consequently, when the pot 4 is inverted on to a surface l0 and withdrawn (as shown in Fig. 3), the cake 9 is released. If necessary, the pot may be bumped on the surface, but sometimes the cake will nearly fall out under its own weight, especially if it has been kept in the pot for a few hours.

Having described our invention, what we desire to secure by Letters Patent is:

1. In the centrifugal spinning of wet yarn of artificial filaments by means of a spinning-pot, running an additional yarn into the pot at the commencement of spinning to form a layer that facilitates the removal of the cake of yarn wound in the pot.

2. An operation according to claim 1, wherein the additional yarn is a dry yarn.

3. In the centrifugal spinning of wet yarn of cellulose derivative artificial filaments by means of a spinning-pot, running an additional yarn into the pot at the commencement of spinning'to form a layer that facilitates the removal of the cake of yarn wound in the pot. I

4. In the centrifugal spinning of wet yarn of cellulose acetate artificial filaments by meansof a spinning-pot, running an additional dry The thread the commencement of spinning to form a layer that facilitates the removal of the cake of yarn wound in the pot.

5. In the centrifugal spinning of wet yarn of cellulose acetate artificial filaments by means of a spinning-pot, running an additional coarse yam, together with the wet yarn, into the pot at the commencement of spinning to form a layer that facilitates the removal of the cake of yarn wound in the pot,

6. In the centrifugal spinning of wet yarn of cellulose acetate artificial filaments by means of a spinning-pot, running an additional continuous filament yarn together with the wet yarn, into the pot at the commencement of spinning to form a layer that facilitates the removal of the cake of yarn wound in the pot.

'7. In the centrifugal spinning by means of a spinning-pot of wet yarn of cellulose acetate artificial filaments which has been produced by extruding a solution of cellulose acetate into a spinningbath containing a high concentration of solvent for the cellulose acetate, running an adartificial filaments which has been produced by extruding a solution of cellulose acetate into a spinning bath containing aqueous diethyleneglycol diacetate, running an additional continuous filament yarn together with the wet yarn into the pot at the commencement of spinning to form a layer that facilitates the removal of the cake of yarn wound in the pot.

PERCY FREDERICK CQMBE SOW'I'ER. WILLIAM DAN DOUGLAS HARRIES.

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