US2007389A - Production of artificial materials - Google Patents

Description

y 1935- w. I. TAYLOR ET AL PRODUCTION OF ARTIFICIAL MATERIALS 2 Sheets-Sheet 1 Filed Dec.

mm H} MM; 5) 8 W M ATTOIPMEVS July 9, 1935. w. TAYLOR El AL PRODUCTION OF ARTIFICIAL MATERIALS Filed Dec. 27, 1933 2 Sheets-Sheet 2 S R mrm 0 Maw VMW l H WW Patented July 9, 1935 UNlTED- STATES PRODUCTION OF ARTIFICIAL MATERIALS William Ivan Taylor and Alfred Herbert Woodrufi, Spondon, near .Derby,.England, as-, signers to Celanese Corporation of America, a corporation of Delaware Application December 21, 1933, Serial No. 704,117

' In Great Britain January 6, 1933 ,11 Claims.

This invention relates to the production of artificial materials and is particularly concerned with the production of artificial filaments by the dry or evaporative'method. i

'5: U. s. application s. No. 3'75,15 filed 1st July,

1929 describes a process for the manufacture of artificial filaments by the dry or evaporative method in which a spinning solution is extruded in theform of filaments into a vacuum or into 31 an evaporative medium at substantially reduced orsub-atmospheric pressure. The specification referred to describes a spinning apparatus resembling in general form a well-known type of apparatus in which a series of rectangular compartments containing spinning jets is provided with doors giving access to such jets, and is heated by banks of' heating pipes proceeding from one end of the series of compartments through the intervening partitions to the other end. In this manner, the heating of all the compartments may be readily controlled, and uniformity between them is obtained. The pressure difference between the inside of each compartment and the outside atmosphere ma however, amount to 5 inches of mercury and upwards as compared with the difference of but a few inches of water which maybe employed in ordinary dry-spinning processes. In consequence, difficulties arise in rendering the compartments gas-tight, not only 9 because the heating pipes pass through the walls of the compartments, but also because provision must be made to render the spinning jets accessible for the attention which theyrequire, e. g. during the starting of the spinning operation.

These difficulties may be overcome or greatly reduced by the present invention. For this purpose, the spinning apparatus may comprise a chamber of large cross-section containing a spinning jet, and a tubular cell of small crosssection leading from said chamber for the recep tion of the filaments extruded from such jet, together with means for creating and maintaining a vacuum within said cell and around said jet, and means for making a gas-tight closure around the jet and the end of the cell. The small diameter of the cell reduces the volume to be evacuated, and greatly facilitates the creation and maintenance of vacuum. r With this arrangement, heating of the cell may beeffected externally, and a convenient arrangement comprises the use of a rectangular casing surrounding the tubular cell, and, it may be, forming a continuation of the chamber containing the spinning jet, and constituting therewith an outer chamber enclosing both the spinning jet and the tubular cell. Heating pipes may be contained within such a casing, or a series of such casings, without entering the tubular cell or cells, thus overcoming the difficulty of making gas-tight joints atpoints of entry of such heating means.

Furthermore, provision may readily be made in the large chamber containing the spinning jet for rendering the" jet accessible, and for making a gas-tight closure around it and the end of the tubular cell. If the tubular cell makes a gas-tightv joint with the chamber, a door or trap inthe chamber containing'the jet may suilice, suitable gaskets or packing being provided to make the door gas-tight. Alternatively, a hood-like member may be provided inside the chamber, making a gas-tight joint around the jet, bedding down on the end of the tubular cell, and adapted to slide away from the tubular cell to give access to the jet. The hood closing the top of the tubular cell may conveniently be arranged to fit around the filter candle through which the spinning solution passes on its way to the joint-of extrusion, or on toa suitable attachment secured to the candle. Thus, for example, the hood-may bea sliding fit about the candle and maybe heavy in weight so that its own weight presses it down upon a rubber ring around the upper edge of the cell to make a gas-tight joint, the action of the vacuum within the cell also assisting considerably in sealing thejoint. l

Means are preferably provided, e. g. in connec tion with the hood at the top of the cell, for connecting the interior of the cell with the outside. atmosphere and so relieving the vacuumbefore the hood is raised to render the spinning jet accessible. i

Thespinning cell according to the present invention maybe provided with any or all of the auxiliary apparatus described in the said U. S. application S. No. 375,150 and U. S. application S. No. 484,788 filed 27th September, 1930. Thus for example, the vacuum in the cell may be maintained by drawing off the contents of the cell to a solvent recoveryplant which itself by the con-- densation of the recovered solvent assists in maintaining the vacuum. Separate means may be provided for effecting initial exhaustion of the cell, and further means may also be provided for introducing any desired quantity of evaporative medium, e, g. warm air or the like. In addition heating means may be provided for bringing the spinning solution to any desired temperature prior to its extrusion from the spinning jet. Suitable means for this purpose are described in U. S. application S. No. 375,151 filed 1st July, 1929.

While the invention is applicable generally to the production of filaments by the dry or evaporative method, it is particularly convenient in connection with the production of filaments of cellulose acetate or other organic derivatives of cellulose. Examples of other organic derivatives of cellulose are other esters of cellulose, such as cellulose formate, cellulose propionate and cellulose butyrate, and the cellulose ethers such as ethyl and benzyl cellulose. Such organic derivatives of cellulose may be dissolved in any suitable solvents, e. g. acetone, with or without high boiling solvents or plasticizers. It is an advantage of the present invention, however, that it enables solvents of relatively low volatility to be employed, these being generally more easily recoverable from the gases drawn out of the cell. Furthermore, by the employment of a vacuum or substantially reduced sub-atmospheric pressure in the spinning cell, filaments of good round or bulbous cross-section are formed, and the natureof the cross-section persists along the length of the filaments, giving great uniformity.

While, in the present description, the filaments have been assumed to take a generally downward and vertical direction during spinning, it is to be understood that the invention is not limited to such form of spinning operation.

By way of example two forms of apparatus according to the invention will now be described in greater detail with reference to the accompany ing drawings in which:--

Figure 1 is a sectional side elevation of a spinning apparatus according to the invention,

Figure 2 is a part sectional view of a detail of Figure 1,

Figure 3 is a sectional side elevation, and Figure 4 a sectional front elevation of a further form of spinning apparatus according to the invention.

In the drawings, the spinning apparatus com prises a chamber 3 fitted with a supply pipe 4, filter candle 5 and'spinning jet 6. Filaments I extruded from the jet 6 pass down a narrow tubular cell 8 inside a casing I9 forming an extension of the chamber 3 and constituting therewith an outer chamber enclosing both jet 6 and cell 8.

The filaments leave the cell 8 by a branch tube 9, being deflected by a thread guide I8 into the branch tube. The tubular cell 8 may be of any convenient cross-section, e. g. round, square or rectangular.

The upper end of the cell 8 is closed by means of a hood I 6 pressed down upon a pad of rubber or like packing material I1 and making a tight joint with a tubular member I8 fitting round the filter candle 5. Access to the spinning jet 6 is obtained through a door in the chamber 3 and by unscrewing and raising the hood IS. A heating ja'eket 2| is provided around the candle 5- and is fed with a heating fluid passing from a main 22 through a cook 23 and inlet pipe 24 into the jacket and out by a pipe 25 and cook 26 t0 an exhaust main 21. Heating pipes 28 are provided in the casing l9 and outside the cell 8. A screen 39 of wire gauze is provided in the cell 8 just below the branch pipe 9 in order to prevent the filaments 1 when first extruded from the spinning jet 6 from falling into the bottom of the cell 8 and being drawn out through the vacuum exhaust I3.

As is shown in Figure 2, the hood I6 screws on to the tubular member I8, and makes a tight joint therewith by means of a packing ring 3|. The member i8 is of substantially the same diameter as the heating jacket 2!, and the hood I6 when unscrewed from the member I8 can be slid upwards over the member I8 and the heating jacket 2|, spring clips 32 being provided to hold it in position. A passage 33 is provided through the heating jacket 2I into the interior of the candle 5, by means of which a thermometer 34 may be inserted in order to observe the temperature of the spinning solution passing through the candle. The thermometer 34 will be removed when sliding up the hood [6 for the purpose of attending to the spinning jet. The filaments 1 are collected together by the guide In in the form of a thread 35 which passes round the feed roller 36 and is collected-by means of a cap spinning device 31 and a bobbin 38.

The outer casing I9 protects the tube 8 from the influences of the outside atmosphere, and enables economical heating of the cell 8 by means of the heating pipes 28 to be effected. At the same time, the volume of the inner cell 8 is very small, and the vacuum therein can be created and maintained at a relatively small cost.

In Figure 3, the filter candle 5 is contained in a chamber 49 forming an enlargement at the upper end of a tubular inner cell 8. Access to the spinning jet 6 is obtained through a door 4I bedded down to form a gas-tight joint on a gasket of soft rubber 42. The spinning solution passing through the candle 5 is heated by means of a heating coil 43 connected to the supply and exhaust headers 22, 21. At the lower end of the cell 8 opposite to the branch tube 9, a branch tube 44 is provided which is covered by means of a cap 45 giving access to the lower end of the cell for cleaning and attention.

The means for creating and maintaining a vacuum within the cell 8 comprises a tube 46 leading to a nozzle 41 in the lower end of the cell 8 and a tube 48 leading to a nozzle 49 in the enlargement 48. The tubes 46, 48 are connected by means of a three-way cook 50 to a tube 5| leading to the vacuum main I5. A fiuff trap 52 is interposed in the tube 5| containing baffles 53 of wire gauze or fabric, and provided with a detachable cover 54. In one position of the cook 50, the vacuum main I5 is connected to the nozzle 41 and permits of slight suction at the bottom of the cell which facilitates the drawing of the filaments I down the cell 8. This is particularly convenient when the spinning jet 6 is being wiped, and the spinning of the filaments I is recommenced When the filaments have passed down the cell 8 and out of the cell to the feed roller 36 the door 4| is closed and the cook 58 is moved to the second position which cuts off the vacuum from the nozzle 4'! and connects the main I5 with the nozzle 49. The nozzle 49 exerts a powerful suction which evacuates the cell 8 and the chamber 48 so that spinning proceeds in a vacuum or substantially reduced sub-atmospheric pressure. The third position of the cook 50 cuts off the vacuum mainI 5 from the spinning cell altogether.

'I-Ieatingof the cell '8 and the chamber' l lll is effected by means of'the' heating pipes 28 which are providedoutside the cell 8- and within the casing is. The nozzle tl is'curved away from the lowcr end of the-cell .8 in order toprevent filaments and filamentous particles of -fiufi from entering it. If any such particles should enter hotvevenfurther protection is alrorded to the vacuum main it by the fiuil trap 52; l

a What we claim and desireto secure by Letters Patent is:-- m

1. Apparatus for the production of artificial filaments ccmprisingja chamber'of large'crosssection, a spinning jet in said chamber for the extrusion of; artificialfilaments; a, tubular cell 2 of small cross-section leading from said chamber to receive such artificial filaments, a hood in said chamber about said jet adapted to make a gastight closure with said jet and with the end of said tubular cell, and to slide away from said cell to give access to said jet, a door in said chamber to give access in turn to said hood, and means for creating and maintaining a vacuum within said cell;

2. Apparatus for the production of artificial filaments comprising an outer cell, a spinning jet at one end of said outer cell for the extrusion of artificial filaments, a narrow inner cell within said outer cell adapted to receive such artificial filaments, and extending the length of said outer cell, means for creating and maintaining a vacuum in said inner cell, a hood surrounding said jet and adapted to make a gas-tight joint with the end of said inner cell and to be slid away from said inner cell to give access to said jet, and a door in said outer cell to give access to said hood and to said jet.

3. Apparatus for the production of artificial filaments, comprising an outer cell, a spinning jet at one thereof for the extrusion of artificial filaments, heating means within said outer cell, an inner cell within and extending the length of said outer cell and adapted to receive artificial filam nts extruded from said jet, means for creating and maintaining a vacuum in said inner cell, a hood surrounding said jet and adapted to make a gas-tight joint with the end of said inner cell and to be slid away from said inner cell to give access to said jet, and a door in said outer cell to give access to said hood and to said jet.

4. Apparatus for the production of artificial filaments, comprising a narrow tubular cell, a spinning jet disposed beyond one end of said cell, a hood adapted to surround said jet and to he slid back to give access to said jet, and packing means enabling said hood to form a gas-tight closure about said jet and the end of said tubular cell.

5. Apparatus for the production of artificial filaments comprising a chamber of large crosssection, a spinning jet in said chamber for the extrusion of a thread of artificial filaments, a tubular cell of small cross-section leading into said chamber and adapted to receive such artificial filaments, means for continuously exhausting the cell so as to create and maintain a vacuum therein, means in connection with said chamber for giving access to the jet therein and adapted to make a gas-tight closure about said jet and the end of said tubular cell, and an exit for the withdrawal of such artificial filaments from said tubular cell, said exit being adapted to leave only a slight clearance between it and the thread of artificial filaments passing through it.

6. Apparatus for the production of artificial filaments comprising a chamber of'large crosssection, a tubular cell of small cross-section therein, a gas-tight joint between the upper end of "said'c'elland said chamber, a spinning jet in said chamber beyond 'the'end of said cell for the extrusion of artificial filaments into said cell, means for'continuously exhausting said cell so as to create and maintain a vacuum therein, means in connection with said chamber for giving access to the jet therein and adapted to make a gastight closure about said jet and the end of said tubular cell, and an exit for the withdrawal of such artificial filaments from said tubular cell, said exit being adapted to leave only a slight clearance between itand the thread of artificial filaments passing through it. V

7. Apparatus for the production of artificial filaments comprising an outer chamber, an innor cell enclosed therein, heating means within the said outer chamber and outside said inner cell, a spinning jet in said chamber beyond the end of said cell for the extrusion of artificial filaments into said cell, means for continuously exhausting said cell so as to create and maintain a vacuum therein, means in connection with said chamber for giving access to the jet therein and adapted to make a gas-tight closure about said jet and the end of said inner cell, and an exit for the withdrawal of such artificial filaments from said inner cell, saidexit being adapted to leave only a slight clearance between it and the thread of artificial filaments passing through it. 8. Apparatus for the production of artificial filaments comprising a chamber of large crosssection, a spinning jet in said chamber for the extrusion of a thread of artificial filaments, a tubular cell of small cross-section leading into said chamber and adapted to receive such artificial filaments, means in connection with the end of said tubular cell leading into said chamber for giving a high degree of suction for continuously exhausting said cell so as to create and maintain a vacuum therein, means at the other end of said cell for giving a low degree of suction, a doorin said chamber to give access to said jet, a gasket to render said door gas-tight when closed and an exit for the withdrawal of such artificial filaments from said tubular cel1,said exit being adapted to leave only a slight clearance between it and the thread of artificial filaments passing through it.

9. Apparatus for the production of artificial filaments comprising an outer chamber, an inner cell enclosed therein, a spinning jet for the extrusion of artificial filaments into said inner cell, means in connection with said chamber for giving access to said spinning jet and adapted to make a gas-tight closure about said jet and the end of said inner cell, means for maintaining a suction within said inner cell whilesaid closure means is open, means for continuously exhausting said inner cell while said closure means is closed so as to create and maintain a vacuum therein, and an exit for the withdrawal of such artificial filaments from said inner cell, said exit being adapted to leave only a slight clearance between it and the thread of artificial filaments passing through it.

10. Apparatus for the production of artificial filaments comprising a chamber of large crosssection, a spinning jet in said chamber for the extrusion of a thread of artificial filaments, a tubular cell of small cross-section leading into said chamber and adapted to receive such artificial filaments, means at the lower end of said cell for continuously exhausting the cell so as to create and maintain a vacuum therein, a gauze screen adapted to prevent filaments and fluff from being drawn into said exhausting means, means in connection with said chamber for giving access to the jet therein and adapted to make a gas-tight closure about said jet and: the end of said tubular cell, and. an exit for the withdrawal for heating spinning solution on its way to said spinning jet, a tubular cell 01 small cross-section leading into said chamber and adapted to receive such artificial filaments, means for continuously exhausting the cell so as to create and maintain a vacuum therein, means in connection with said chamber for giving access to the jet therein and adapted to make a gas-tight closure about said jet and the end of said tubular cell, and an exit for the withdrawal of such artificial filaments from said tubular cell, said exit being adapted to leave only a slight clearance between it and the thread of artificial filaments passing through it.

WILLIAM IVAN TAYLOR.

ALFRED HERBERT WOODRUFF.

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