US2047313A - Production of artificial filaments - Google Patents

Description

July 14, 1936 H. DREYFUS PRODUCTION OF ARTIFICIAL FILAMENTS Filed March 22, 1933 INVE/V TU/Q Patented July 14, 1936 Henry Dreyfus, London, England Application March 22, 1933, Serial No. 662,049

In Great Britain April 30, 1932 6 Claims.

This invention relates to the production of artificial filaments or the like by the extrusion of a spinning solution into an evaporative atmosphere, as for example by the extrusion of a spinning solution containing cellulose acetate or other cellulose derivative in a volatile solvent liquid. Examples of other cellulose derivatives which may be spun by this method are other cellulose esters, such as cellulose formate, propionate and butyrate, and cellulose ethers, such as ethyl and benzyl cellulose.

The invention is concerned with the heating of the spinning solution prior to its extrusion, the object of the invention being to employ a gaseous medium for the purpose of applying heat to the spinning solution.

In the dry or evaporative method of spinning, a spinning jet is arranged in a spinning cell, the cell being provided with means for bringingthe evaporative medium, usually air, within the cell to the required temperature to bring about setting of the filaments. This air is usually caused to flow in a counter-current direction to the filaments, that is, the air enters at or near an end of the cell remote from thejet, and is drawn from suction applied at the outlet for the air. The

fiow of air removes the volatile solvent from the filaments, solvent vapours being carried from the cell together with the air by the applied suction.

The spinning solution is led to the jet by a pipe connected to a pump, usually outside the cell, this pipe being in the neighbourhood of the outlet of the air from the cell, and so under the influence of the temperature of this air. Generally the pipe is constituted by a filter immediately connected to the jet, and the relatively slow passage of the spinning solution through the filter increases the opportunity for the solution to be influenced by the surrounding air.

U. S. Patent No. 1,814,468 describes the use of collector devices by means of which the air may be constrained into the immediate vicinity of the jet and shows forms of collector devices which serve as jackets to direct such constrained air to pass into close proximity with the filter before being exhausted from the cell. In this way the heating effect of the air which is withdrawn can be utilized to increase the temperature of the spinning solution on its way to the jet.

According to the present invention, use is also made of the heated atmosphere for the attemperation of the spinning solution, the feature of the invention being that the atmosphere is carried through the body of the spinning solution in the Two forms of apparatus according to the invention are shown in the accompanying drawing as. applied to the downward spinning of filaments into an upward current of air.

In the drawing:- Figure l is a sectional view of a spinning cell containing a filter provided with passages for-the interior circulation of air; and.

Figure 2 is a sectional view of a jet fitting comprising a supply. pipe arranged for internal and external heating.

Referring to Figure l, a filter body 3 carried by the supply pipe 4 is provided with a central pas sage 5 communicating by a number of .passages B with the outside of the body. A casing I is secured about the body 3 so as to form an annular space 8 into which the spinning solution fiows after passing through the filter material 9 covering the outer perforated wall ll) of the body3.

An annular jet 1 I is secured to the lower end of the members 3, l, the passage 5 inside the member 3 thus being in communication with the interior of the spinning cell I2 through the centre of the jet ll.

Air is withdrawn from the cell l2 in controlled amount by the draw-01f I3, some of the air passing through the passage 5 while the remainder travels outside the casing I. A plate I 4 surrounding the casing 1 except for a gap l5 may be used to cause the external air to come into close contact with the casing l, and by suitably adjusting the size of the gap I5 to the total area of the passages 6, the relative amounts of external and internal air may be regulated. It will be readily seen that in addition to air being constrained into the immediate vicinity of the spinning orifices, as claimed in U. S. Patent No. 1,814,468, the air is also caused to heat up the spinning solution on its way to the jet.

If desired, shields I6 may be arranged over the heating pipes ll in the cell l2 to assist in directing the stream of air induced by convection to the outside of the filter body. The spinning solution entering the member 3 is thus given a preliminary heating by the somewhat cooler air which passes from the extrusion zone into the passage 5 and is then heated to a greater degree by the hotter air after it has passed from the inside of the filter body to the annular space 8 inside the casing 1.

Referring now to Figure 2, a disc-type jet I8 is carried by the lower end of a supply pipe l9 which is enlarged as shown at 20 to enable a pipe 2| to be carried centrally therethrough. This pipe 2| communicates with the outside of the pipe H) by passages 22 and also with a drawoif pipe 23 by a connecting pipe 24. Air can thus be drawn through the pipe 2| while the spinning solution fiows through the annular space 25 between the pipe 2! and the outside of the pipe 20.

Instead of the air passing directly into the passages 22, it may be constrained to pass first through a jacket 26 surounding the pipe 20 and may be caused to pass along the whole length of the jacket by arranging the inlet holes 2'! at the end of the jacket remote from the passages 22. In this way, the spinning solution is not only surrounded by the heated air but has a current of air passing internally through it.

All the air may be withdrawn by the pipe 23 and thus utilized for heating the spinning solution, or part of the air may be withdrawn by a second draw-01f pipe 28 so that the heating efiect may be regulated by adjusting the proportions of the air passing through the two pipes.

The zone into which the spinning solution is extruded by the jet l8 may be cooled by the injection of a suitable quantity of cool air, as by means of the flattened pipe 29.

What I claim and desire to secure by Letters Patent is:-

1. In the spinning of artificial filaments or the like by the extrusion of a spinning solution into a heated evaporative atmosphere, the steps of filtering the solution before extrusion, and passing evaporative atmosphere internally and externally of the body of. the spinning solution while it is being filtered so as to attemperate the solution prior to extrusion.

2. Process for the production of artificial filaments or the like, said process comprising filtering a spinning solution, extruding said solution downwardly into an upward current of heated evaporative atmosphere, and passing evaporative atmosphere from said current internally and externally of the body of the solution while it is being filtered so as to attemperate the solution prior to extrusion.

3. Apparatus for the extrusion of spinning solutions into an evaporative atmosphere, said apparatus comprising a supply pipe adapted to conduct the solution towards the point of extrusion, a passage running internally of said pipe and communicating with the exterior thereof, and a jacket surounding said pipe, said jacket communicating with the internal passage, and means for drawing evaporative atmosphere through the jacket and internal passage so as to attemperate the solution passing through the supply pipe.

4. Apparatus for the extrusion of spinning solutions into an evaporative atmosphere, said apparatus comprising a spinning cell, a jet in said cell, a supply pipe adapted to conduct spinning solution to said jet, a passage running internally of said pipe and in communication with the interior of said cell, means for drawing evaporative medium through said cell both externally of said supply pipe and internally via said passage, and means for constraining the evaporative medium drawn externally of the pipe to pass in close proximity thereto.

5. Apparatus for the extrusion of spinning solutions into an evaporative atmosphere, said apparatus comprising a spinning cell, a jet in said cell, a supply pipe adapted to conduct spinning solution to said jet, a passage running internally of said pipe and in communication with the interior of said cell, means for drawing some evaporative atmosphere from said cell through said internal passage, and means for drawing other evaporative atmosphere externally of the supply pipe.

6. Apparatus for the extrusion of spinning solutions into an evaporative atmosphere, comprising a spinning cell, a jet in said cell, a filter in communication with the jet, a passage running internally of said filter and in communication with the interior of the cell and forming an annular filtering zone surrounding said passage, means for drawing evaporative medium both externally of said filter and internally via said passage, and means for constraining the evaporative medium drawn externally of the filter to pass in close proximity thereto.

HENRY DREYFUS.

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