US2519382A - Method of manufacturing synthetic filaments and the like - Google Patents

Description

Aug. 22, 1950 K H. A. KULJIAN METHOD oF MANUFACTURING SYNTHETIC FILAMENTS AND THE LIKE Filed Nav. 1s, 1947 NUM. QW

- 4 7 TURA/5y Patented Aug. 22, 1950 METHOD F MANUFACTURING SYNTHETIC FILAMENTS AND THE LIKE Harry Asdour Kuljian, Merian, Pa.

Application November 13, 1947, Serial No. 785,626

8 Claims.

Synthetic filaments of the rayon type may be produced according to the viscose process, according to the cuprammonium process or according to the cellulose acetate process. In all of these processes, it is necessary to'protect the filament, in its nascent stage, from contact with the oxygen of the air or with other gases which may produce unintended chemical reactions. In the case of the viscose process, in which the viscose solution is extruded into a bath containing sulphuric acid, the presence of oxygen in the coagulating bath also causes chemical reactions which produce free sulphur which tends to deposit on the filament. When the filament is intended for use in wearing apparel and the like, the sulphur must be removed from the filament before the other treatments necessary to bring the filament to the desired finished state can be initiated. Removal of the sulphur from the filament adds another step to the manufacturing operation and thus increases the cost. Also, because removal of the sulphur involves the use of harsh chemicals and because it delays the initiation of the finishing treatments, which desirably, Should begin as soon as possible after formation of the filament, the deposit of sulphur on the filament, at least indirectly, adversely affects the quality of the filament.

It is therefore the main object of the invention to provide an improved method of manufacture of synthetic filaments whereby the production of free sulphur in the coagulating bath is prevented, or materially reduced, and whereby the filament is protected from contact with oxygen, during its formative and nascent stages and while it is still in the coagulatng bath.

A further object is to carry out the invention in a simple, eflicient, inexpensive and practical manner.

The single figure in the drawing is a highly diagrammatic view, partly in section and partly in elevation, illustrating one manner of accomplishing the objects of the invention.

According to my invention, I provide means for deg-asifying the coagulating bath, means for saturating the bath with an appropriate inert gas, and means for protecting the surface of the bath, from contact with air or other gases.

As is usual in the manufacture of synthetic laments, the appropriate solution is forced, under pressure, through a spinnerette I0, into an appropriate coagulating bath I4 contained in a receptacle I5.

Conveniently, the top wall of the receptacle, or portion I6 thereof, is provided with an access opening which is normally closed by a cover I'I,

hinged at I8. The free edge of the cover is spaced somewhat from the edge of the wall I6 to provide a passage for the filament 22. The filament emerging from the receptacle travels around godet Wheels 24 and may then be taken up for storage or for further treatment depending on the use for which the filament is intended.

In order to prevent formation of free sulphur and the 'deposit of sulphur on the filament, I provide a conventional degasifying apparatus for removing gases from the coagulating b-ath. The degasifying apparatus is connected by a pipe 30 to a reservoir 32 which contains a supply of coagulating bath liquid and is connected by a pipe 34 to a receiver 3E. During its passage from the degasifying apparatus to the receiver, the liquid is charged with CO2 gas, from a charger 40 which is connected to the pipe 34 by means of a pipe 4I. The receiver 36 is connected by a pipe 42 to the lower portion of the receptacle I5 and a pump P is cut intothis pipe for propelling the bath liquid from the receiver to the receptacle I5. From the upper portion of the liquid bath, a pipe 43 leads to a regenerator 44, and another pump P' is cut into this pipe for propelling the bath liquid from the receptacle I5 to the regenerator 44. In the regenerator, the bath liquid is reconditioned, or reconcentrated, and is returned to the reservoir 32 through a pipe 6. If desired, a pump can also be cut into the pipe i6.

In addition to the CO2 charger 4B, I provide a pipe 48 which is connected at 5t to a pipe 52 leading from a source of CO2. It will be noted that the discharge end of the pipe 48 which is below the level of the bath liquid, should be so located, and the pressure of the gas iowing therethrough should be so controlled that the CO2 bubbling upwardly through the bath liquid will not disturb or damage the fragile, nascent lilament. It will also be noted that the opening through which the filament passes is located above the level of the bath liquid and is relatively small so that only excess gas can escape through this opening. This insures the continuous presence of -a blanket of inert gas on the surface of the bath and will prevent surface absorption of air or other gases by the bath liquid. The location and size of the filament passage can be criti cal when the inert gas used is lighter than air, but are not very important when CO2 gas, which is heavier than air is used. While I have found CO2 gas to be satisfactory, I may use other inert gases such as nitrogen.

In addition to depositing on the filament, the free sulphur in the coagulating bath also tends to clog the orifices of the spinnerettes used for extruding the solutions into the bath and, in order to overcome this diiiiculty, it has been necessary to add chemicals to the bath to keep the sulphur in solution. For example, cations, such as lauryl pyridine chloride or lauryl pyridine sulphate have been used for this purpose. These chemicals are expensive and have to be used in substantial quantities thus adding to the cost of manufacture. By my invention, the production of free sulphur is prevented or materially reduced, and accordingly, the need for means for preventing deposit of sulphur on the orifices of the spinnerettes is eliminated or materially reduced.

It will be seen that by the simple expedient of' degasifying the bath and then saturating. it with an inert gas, and by blanketing the surface of the bath with inert gas to prevent reabsorption of oxygen by the bath, the productionv of free sulphur, and its consequent deposit on the filament and on the spinnerette, are eliminated or greatly reduced, thus eiecting considerable saving in the cost of manufacture and improving the quality of the iinished lament.

While the invention has been described above in connection With the manufacture of a filament it is obvious that the type f object being manufactured has no bearing on the method disclosed and claimed which can be used whether the object being made is a filament, a sheet, a rope or is of any other shape or configuration.

What I claim is:

1. In' the method of producing a synthetic filament by extruding a viscose solution into a liquid coagulating medium, the step of preventing formation of free sulphur in said medium and deposit of the free sulphur on said filament by removing oxygen from said medium.

2. In the method of producing a synthetic filament by extruding a viscose solution into a liquid coagulating medium, the step of preventing formation of free sulphur in said medium and deposit of the free sulphur on the filament, during 4 its formative stage, by removing oxygen from said medium and impregnating said medium with an inert gas.

3. The method recited in claim 2 in which the inert medium is carbon dioxide gas.

4. The method recited in claim 2 in which the inert gas is nitrogen.

5. In the method of producing a synthetic lament by extruding a viscose, solution into a liquid coagulating bath, the steps of removing oxygen from said bath, and of blanketing the surface of said bath with a heavier than air inert gas to prevent absorption of oxygen by said bath.

6. In the method of producing a synthetic lament by extruding a viscose solution into a liquid coagulating. bath, the steps of removing oxygen from said bath, replacing the oxygen with a heavier than air inert gas, and blanketing the surface of said bath with a layer of said inert gas.

'7. In the method of producing a synthetic lament by extruding a viscosev solution into a liquid coagulating bath, the steps of circulating said bath through a substantially closed circuit which includes a deaerating device for removing oxygen from said bath, forcing a heavier than air inert gas through said bath to replace the oxygen, and blanketing the surface of said bath with a layer of said gas.

8. The method defined in claim '7 together with the step of extruding the solution into a bath contained in a substantially closed receptacle.

HARRY ASDOUR KULJIAN.

REFERENCES CITED The following. references are of record in the file of thisv patent.:

UNITED STATES PATENTS Number Name Date 2,241,304 Heywood et al. May 6, 1941 2,335,922 reyfus Dec. '7, 1943 2,336,778 Costa et al. Dec. 14, 1943 2,413,102 Ebert et al. Dec. 24, 1946

Claims (1)

1. 7. IN THE METHOD OF PRODUCING A SYNTHETIC FILAMENT BY EXRUDING A VISCOSE SOLUTION INTO A LIQUID COAGULTING BATH, THE STEPS OF CIRCULATING SAID BATH THROUGH A SUBSTANTIALLY CLOSED CIRCUIT WHICH INCLUDES A DEAERATING DEVICE FOR REMOVING OXYGEN FROM SAID BATH, FORCING A HEAVIER THAN AIR INERT GAS THROUGH SAID BATH TO REPLACE THE OXYGEN, AND BLANKTING THE SURFACTOF SAID BATH WITH A LAYER OF SAID GAS.

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