US2030212A - Production of artificial materials - Google Patents

Description

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PRODUCTION OF ARTIFICIAL MATERIALS Filed Jan. 2'7, 1953 ooooooo oo ooooo TR IIIIIIJ ATT RNEYS Patented Feb. 11, 1936 UNITED STATES PATENT OFFICE Spondon, near Derby,

England, assignors to Celanese Corporation of America, a corporation of Delaware Application January 27, 1933, Serial No. 653,805 In Great Britain February 10, 1932 7 Claims.

This invention relates to the production of artificial filaments or the like especially by the dry or evaporative method, for example, the dry spinning of filaments of cellulose acetate or other derivates of cellulose such as other cellulose esters, e. g. cellulose formate, propionate and butyrate, and cellulose ethers, e. g. methyl, ethyl and butyl cellulose. The invention relates in particular to apparatus for introducing evaporative medium into the immediate vicinity of the filaments issuing from the spinning jet for the purpose of controlling the quality of the filaments and for facilitating the drying thereof. It has been found that the effect of evaporative medium (hereafter referred to as air) applied to the filaments issuing from the jet depends upon a number of factors. Thus, as described in U. S. Patent No. 1,934,618, the distance from the point of emergence of the filaments from the jet at which the air is applied is of considerable importance. Secondly, the quantity of air so applied may depend on a number of conditions such as the denier to be spun, the rate of spinning, the spinning temperature, and the total quantity of 25 air employed to bring about setting of the filaments. Thus, for example, in spinning operations involving drying of the filaments by the use of a counter-current of air passing through the spinning cell, the quantity of air applied to 30 the filaments close to the jet is preferably of the order of 10-15% of the total quantity of air withdrawn from the spinning cell.

Means for controlling this quantity and for securing uniformity as between a number of spinning jets in a machine are described in U. S. applications S. Nos. 639,612 filed 26th October, 1932 and 653,804, filed January 27, 1933. Further, the manner in which the air is presented to the filaments has an important effect on the efficacy of the applied air. Thus, as described in U. S. application S. No. 653,804, it is desirable that the air should be applied at a relatively high velocity, which can conveniently be effected by arranging 45 the applying means close to the filaments as described in that application, and also in the form of a thin blast or stream as by means of a jet having a thin, wide orifice or otherwise arranged to spread the air in a fiat stream.

It has now been found that the effectiveness of the air can be increased by the use of at least two jets or streams which do not directly oppose each other, but are arranged to meet the filaments at different distances from the jet, the advantageous 55 result obtained probably being due to the several streams of air causing an intimate movement of the air about the filaments.

Conveniently the air is applied as two streams only, which, in order to ensure uniform treatment of all the filaments issuing from a single jet, are directed at the filaments from substantially opposite sides thereof, though, as stated above, at different distances from the jet. More than two streams may, however, be employed, these being applied at at least two different distances from the jet. Thus, for example, three or four streams may be applied at as many different distances from the jet.

The streams of air issuing from the several jets may be sufliciently wide to include all the filaments in the zone reached by the air. Thus, two of the devices described in U. S. application S. No. 653,804 may be so mounted in the spinning cell that their orifices are at different distances from the spinning jet, and each fairly close to the filaments issuing from the jet. Thus, for example, one of the devices may be arranged to discharge air two inches below a downwardly spinning jet, while the other of the devices discharges air at about four inches below the jet. The direction taken by the applied air may be directly transverse to the line of passage of the filaments, or it may be inclined in an upward or downward direction thereto.

Any suitable means may be employed for producing streams of air from the applying devices. Thus, for example, the devices may be connected to a suitable supply of air under pressure, which may if desired be arranged to serve a plurality of jets and supply each with the desired quantity of air, suitable means for this purpose being described in U. S. applications S. Nos. 639,612 and 653,804. Again, the suction employed to withdraw air from the spinning cell may serve to induce a flow of air through. the applying means onto the filaments. Again, use may be made of the flow of air induced by the heating means employed to bring the air in the cell to the spinning temperature. Thus, where the cell is heated by pipes or jackets arranged near the walls of the cell, convection currents set up along the walls of the cell may be deflected so as to impinge on the filaments issuing from the jet from opposite sides thereof and at different levels below the jet. For example, where a spinning cell is heated by a row of horizontal pipes arranged near the walls of the cell, baffle plates may be arranged so as to provide a space along each wall of the cell at which air heated by the pipes flows by convection to the upper end of the cell.

4 At the top of each of these spaces a deflector,

which can be formed of a flat nozzle, is mounted to direct the air onto the filaments.

Where, however, it is desired that the applied air should be cold or at a relatively low temperature, the air is most conveniently supplied under pressure from outside source, e. g. a rotary fan, an air compressor, or vessel containing air under pressure. Such arrangements may also be employed to supply heated air by arranging that the connecting pipes from the header or headers make a run through the cell of sufiicient length to bring the air to the required temperature. By the provision of suitable valves hot or cold air may be applied at will.

Whatever the nature of the devices employed to apply the opposing jets of air at different distances from the jet, it is desirable that these devices should so be arranged as not to interfere with the accessibility of the jet for cleaning or replacement. Thus, where deflectors are employed to conduct air induced by convection onto the filaments, these deflectors may be made removable, or the one arranged to discharge near to the jet may be removable while the other, which is more remote from the jet may be arranged at the far side of the cell from the door by which the jet is reached so that it Will not prevent access to the jet. The discharge orifice of this more remote deflector may be provided with a cap to be placed over the orifice while attention is being given to the jet so as to prevent the orifice becoming choked.

Where applying devices of the type described in U. S. application S. No. 653,804 are employed, these may be made movable out of operative position as described in that application, and provided, if desired, with means for cutting ofi the supply of air during the period of inaction. These means for moving the applying means and/or the cutting off of the supply of air may be effected automatically on the opening of the cell door.

If desired, the applied air may contain gases or vapours such as vapours of the solvent employed in the spinning solution where such are required for the control of the filament characteristics.

The device according to the invention may be employed in connection with any suitable form of dry spinning apparatus and in connection with any desired means for supplying air to or circulating air through the spinning cell. For example, a device or devices may be employed in connection with cells in which a draw-01f device is provided at or near the level of the jets to exhaust air from the cell or to produce a current of air through the cell. The air introduced by the device or devices need not, however, be exhausted wholly at such point, but may be exhausted from some other point or points or partly from one point and partly from another, and may be used alike in apparatus for upward or downward spinning and having a counter fiow of evaporative medium or a flow in the same direction as the filaments.

The invention will now be described in greater detail with reference to the accompanying drawing, but it is to be understood that this description is given by way of example only and is in no respect limitative.

Figure 1 is a side elevation in section and Figure 2 a front elevation in section of a spinning cell provided with means for carrying out the invention and Figure 1a is a detail of Figure 1.

Figures 3' and 4 show two further forms of a spinning cell for carrying out the invention.

Figure 5 is an inverted sectional plan view of Figure 4, and

Figure 6 shows a detail of Figure 4. Referring to Figures 1, 1a. and 2 a spinning cell I is provided with a pipe H for the supply of spinning solution which is conducted under pressure through a filter candle l2 to a spinning jet I3. The filaments l4 issuing from the jet [3 pass down the length of the cell l0 and are deflected by means of a guide bar l through an opening [6 in the cell wall and over a roller I! which feeds them to a cap spinning device I8. A current of evaporative medium is introduced into the cell in by means of an inlet and leaves the cell by a draw-off device 2| conducting it to a header 22, gauge means 23 and valve means 24 being provided to control the rate of flow of evaporative medium through the cell. In order to heat the air in the cell heating pipes 25 are provided at the front and back of the cell, these pipes being fed with a current of steam, hot water or other suitable heating medium. The heating of the air in the immediate vicinity of the pipes 25 causes a current of air to flow up the front and back of the cell. This current is isolated from the rest of the cell by means of plates 21 and is deflected on to the filaments in the neighbourhood of the spinning jet l3 by means of deflector devices 28, 29 at the front and back of the cell respectively.

It is the feature of the invention that the defiectors 28, 29 project the air on to the filaments M at slightly different levels, e. g. at 4 inches and 2 inches respectively from the spinning jet, and in this manner an intimate movement of air is set up in the neighbourhood of the filaments I4 issuing from the jet l3.

As clearly shown in Figure 2 the cell H] contains two spinning jets side by side and two collector devices 28 are provided which converge to a slit shaped nozzle 30 which throws the air on the filaments in the form of a fiat stream. The plates. 2! and the deflectors 28 are integral with one another and are secured in position by being hooked over the uppermost of the pipes 25 at the front and back of the cell. At the bottom of the plates 21 lugs 32 are provided to ensure correct posi-,.

tioning of the plates. Access to the jet I3 within the cell I0 may be obtained through a door 33, the rearmost deflector 29 being hooked off and lowered down the cell for this purpose. The deflector device 28 is sufiiciently low in the cell to permit access to be obtained to the jet l3 but in v In Figure 3 additional air is injected at different levels on the filaments issuing from the spinning jet I3 by means of nozzles 35, 36 at the front and rear of the cell respectively. Air is supplied from headers 31, 38 through valves 39,--

40 and the nozzle 36 at the rear of the cell is mounted on a swivel 4| which also serves to cut 011 the supply of air when the nozzle 36 is swung out of the way in order to render the jet l3 accessible through the door 33.

throw the air in a wide fiat stream on the filaments, thus ensuring that all the filaments issuing from the jet are adequately treated.

Referring to Figures 4, 5 and 6 the main current of evaporative medium is introduced at the top The nozzles 35, 36, are of the form of fish tail gas burners, and

of the cell by an inlet device 45 and leaves at the bottom by a draw-off device 46 provided with control means 23, 24 similar to those described with reference to Figure 1. In this case the main current of air flows in the same direction as the filaments instead of in the opposite direction as described with reference to the preceding figures. Additional evaporative medium is introduced into the neighbourhood of the filaments issuing from the jet I3 by means of three nozzles 41, 48, 49 disposed round the bundle of filaments. The air is supplied at high pressure through headers 31, 38 as described with reference to Figure 3, but the rate of flow is controlled by means of an orifice valve 50 to be described hereafter. The nozzles 48, 49 are mounted on swivel pivots 5|, 52 which enable the nozzles to be swung across to the side of the spinning cell when access is required to the jet l3 through the door 33. At the same time the joints 5 I, 52 are adapted to shut off the supply of evaporative medium through the nozzles. As illustrated in Figure 5, the three nozzles 41, 48, 49 blow air in a direction tangential to the circle of filaments I4, thus ensuring that all the filaments receive an adequate supply of additional evaporative medium.

The rate of flow of additional evaporative medium from the headers 31, 38 is controlled by means shown in section in Figure 6. The air from the header 38 enters the control device by a pipe 54 and passes into a chamber 55 from which it proceeds through a screw plug 56 having a carefully bored orifice 51 into a pipe 58 leading to the air jet. When it is desired to alter the rate of flow of additional air, the chamber 55 is opened by screwing off a cover 59 and the plug 56 is screwed out and replaced by another plug having an orifice 51 of different size. The rate of fiow of air is accurately controlled by an accurate formation of the orifices 51 in the various screwed plugs employed.

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

1. Process for the production of artificial filaments by the evaporative method, said process comprising extruding the filaments into an evaporative medium and introducing into the neighbourhood of the point of extrusion of the filaments at least two streams of evaporative medium which are directed against the filaments from different sides thereof and at different distances from the point of extrusion.

'2. Process for the production of artificial filaments by the evaporative method, said process comprising-extruding the filaments into an evaporative medium and introducing from outside said medium into the neighbourhood of the point of extrusion of the filaments at least two streams of evaporative medium which are directed against the filaments from different sides thereof and at different distances from the point of extrusion.

3. Process for the production of artificial filaments by the evaporative method, said process comprising extruding the filaments as a circular bundle into an evaporative medium and introducing into the neighbourhood of the point of extrusion of the filaments a plurality of streams of evaporative medium which are introduced into the neighbourhood of the filaments in directions tangential to the bundle of filaments from difierent sides thereof and at different distances from the point of extrusion.

4. Apparatus for the production of artificial filaments by the evaporative method, said apparatus comprising a spinning cell, a spinning jet therein for the extrusion of artificial filaments and means for directing at least two streams of evaporative medium on to the filaments in the neighbourhood of the jet from different sides of the filaments and at difierent distances from the jet.

5. Apparatus for the production of artificial filaments by the evaporative method, said apparatus comprising a spinning cell, a spinning jet therein for the extrusion of artificial filaments,

means for introducing evaporative medium from K outside said cell, and means for directing at least two streams of such evaporative medium on to the filaments in the neighbourhood of the jet from different sides of the filaments and at different distances from the jet.

6. Apparatus for the production of artificial filaments by the evaporative method, said apparatus comprising a spinning cell, a. spinning jet therein for the extrusion of artificial filaments,

a door in said cell giving access to said spinning jet, and means for directing at least two streams of evaporative medium on to the filaments in the neighbourhood of the jet from different sides of the filaments and at different distances from the jet, said directing means comprising a pivotally mounted pipe adapted to swing'out of operative position in order to render the spinning jet accessible through said door.

'7. Apparatus for the production of artificial filaments by the evaporative method, said apparatus comprising a spinning cell, a spinning jet therein for the extrusion of artificial filaments, a door in said cell giving access to said spinning jet, and means for directing at least two streams of evaporative medium on to the filaments in the

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