US2303338A - Preparation of artificial filaments or threads - Google Patents

Description

Dec. l, 1942A.

C. DREYFUS EVAL PREPARATION OF ARTIFICIAL FILAMENTS OR THREADS Filed sept. 21. 195s INVENTRS cAMlLLE DREYFUS GEORGE :SCHNEIDER ATTORNEYS Patented Dec. l, 1942 UNITED STATESA PREPARATION F ARTIFICIAL FILAMENTS 0B THR EADS Camille Dreyfus, New York, N. Y., and George Schneider, Montclair, N. J., assignors to Celanese Corporation of America, a corporation of v Delaware Application September 21, 1939, Serial No. 295,906 l 16 Claims. This inventionrelates to the production of filaments or threads from organic esters of cellulose,4

and relates more particularly to the preparation of such materials by the extrusion of organic esters of cellulose while in molten state.

An 'object of our invention is to provide a method of preparing filaments or threads from organic esters of cellulose which'is simpler and more expeditious than those formerly used.

A further object of our invention is to prepare filaments or threads. that are of greater tensile strength and of improved textile properties as compared with filaments or threads producedl from organic estersof cellulose by prior f 15 pipe I and may be melted by the heating medium processes.

Other objects of our invention will appear from `the following detoued description. n Heretofore, in the production of filaments or threads from organic esters of cellulose, either by the dryor evaporative method or by the wet method of spinning, solutions of the organic esters of cellulose in volatile organic solvents were extruded through the orifices of a spinneret into an evaporative coagulating medium. The usel of such volatile solvents, however, presents the disadvantages that it is costly to recoverI the same and even with the greatest care a considerable amount is lost, they are generally inflammable and therefore present a fire risk, and some of the solvent is retained by the yarns and filaf ments with the resultant effect on the tenacity and other properties of the same.

We have found that the disadvantages arising out of the use of volatile solvents may be avoided l by shaping or extruding the organic ester of cellulosevthrough the orifices of a spinneret while the same is in molten condition. In this manner there are produced filaments or threads that are free of residual volatile solvent and therefore of superior tenacity and other textile properties.,

Further, we have found that if the solidified filaments or threads are stretched the resulting orientation of themat'erial produces increased tenacity. l

In accordance with our invention melted or` ganic ester of cellulose of good stability is exlulose such as cellulosepropionate and cellulose butyrate, or mixed esters suchas cellulose acetopropionate and cellulose aceto-butyrate- In the drawing, the figure shows one form of 5 apparatus suitable for Vcarrying out the invention,

this drawing being merely illustrative.

'Ihe apparatus comprises a closed vessel I provided with aremovable cover 2 anda jacket 3 for receiving a fluid heating medium, such as steam or hot Water which -may be` introduced through the pipe 5 and taken off through pipe 4. The cellulose acetate, 6, can be introduced into the vessel by removing the cover 2 or in the form of a slurry orsuspension through valved in the jacket.. Pressure may be built up in the r inert liquid or gas under pressure introduced through pipe 8, this hot liquid or gas aidingin the melting of the cellulose acetate.4 When thecellulose acetate is melted it is forced, by means of the high pressure in the vessel I, through they valved outlet I0 into the header I I and from the latter it is-delivered through pump I2 to`spinneret's I3. The filaments I5 are (extruded through orices in the spinnerets into spinning cells or 'chambers I4 through which cool or cold air or other gas passes in order to set the formed filaments. The formed filaments may be collected on any suitable take-up means.`

By this invention filaments of low denier, say i from less than 2 to 10 or more, which are associated together in required number to form yarn' -may be produced. -However, -laments of large denier, say from 150 to 500 or more, which may be used as horsehair, bristles and the like, may be made, as may be ribbons or bands to be used as articial straw. 'Ihe molten cellulose acetate may be extruded through metallic jets or spinv40 nerets of"sulicien't strength' and/or reinforced to withstand the extrusion pressure, andfl which have orifices of required size, say circular orifices of from 0.05 mm. in diameter or upward in the case of making yarns or bristles, or the orifices may bein the frm of slits, when artificial straw is made. l'

Any `suitable temperatures and pressures may be employed for melting and extruding the cellulose acetate. We have found that although it is diiiicult to melt cellulose acetate at ordinary pressures Without decomposition, the cellulose'acetate canbe readilymelted'or at least rendered suflil 5,5 air or otherlreactive gas. -Pressures of to 5 00 A vessel I by means of lsteam or hot water 9 or hot lbs. per square temperatures of For the same effect, the higher lower is the required temperature.

We have found that the temperatures and pressures required for meltingand extruding the cellulose acetate may be reduced by heating the same under pressure in the presence of water or other aqueous liquid, in which case the pressures employed to melt the cellulose acetate will be from 50 to 250 or more pounds per square inch above atmospheric, and the temperature will be that of boiling water at such pressures. Itis preferable to employ the higher pressures, i. e. 150 to 250 or more pounds per square inch and 150 C. upwards are employed.

inch are generally suitable and the pressure the the temperatures corresponding thereto, i. e., i

about 185 to 210 C.

As an alternative and in some respects preferred method of lowering the temperature required for melting, there is associated with the cellulose acetate relatively non-volatile solvents or plasticizers, in amounts of from 10 to 50% or more of the cellulose acetate present. Examples of such plasticizers are dimethyl phthalate, di-

Aethyl phthalate, dimethoxy ethyl phthalate, di-

butyl phthalate, triacetin, ethyl orthotoluene sulphonamide, ethyl'paratoluene sulphonamide. A mixture of two or more of these plasticizers may be used. These plasticizers may be associated with the cellulose acetate in intimate admixture prior to melting in any suitable manner, such as byl finely grinding the ingredients together; dissolving them in a volatile solvent to form a plastic mass, kneading the plastic mass under heat, and working the mass of heated malaxating rolls until practically all the volatile solvent is evaporated, etc.

The melting and extrusion of the cellulose acetate whether alone or in the presence of water or plasticizer may be carried out in any suitable apparatus such as a closed vessel in which pressure may be exerted by mechanical means such as pistons, or .by hydraulic or pneumatic means such as hot water, hot mineral oil or other inert liquid, or heated nitrogen, steam, carbon dioxide or other inert gas under pressure. When the cellulose acetate is melted it is forced, by means of the high. pressure obtaining in the vessel, through a suitable opening in said vessel into a header, and from the header the melted cellulose acetate is pumped into a spinneret from which the laments are extruded into suitable orifices therein. A

In order to harden the filaments extruded from the spinnerets, they may be extruded into a chamber through which cool or cold air or other gas passes or into a cool or cold bath of water or other inert liquid. or if special effects such as dyeing or saponiiication are desired into a bath containing the ingredients required to cause such effects, such as aqueous solutions of caustic soda or other alkali for saponication, or aqueous or other baths containing dyestuis or their components for dyeing. l

The filaments are then passed around godet rollers or other take-up devices which preferably rotate at a peripheral speed greater than that at which the cellulose acetate is extruded so that the molten cellulose acetate filaments are drawn out as they leave the spinnerets, after which they are. wound up, preferably with twisting. by a suitable machinefsuch as a ring-spinning or captwisting'device when yarns l,are made. However, in some instances, especially .when the yarns or filaments are subsequently subjected to a stretchcase of artificial straw or bristles, the plasticizer 'may be advantageously retained. l

ing operation, we prefer not to draw the filaments out, in which case the godet rollers or other takeup devices are run at a peripheral speed equal to that at which the cellulose acetate is extruded.

We have found that if the filaments or yarns are drawn, and while they are hard and at a temperature not substantially above room temperatures and preferably below thesame, say from 0 to 30 C., the tenacity of the same is greatly increased. The amount of stretching is on the` order of 2O to 300% or more. This stretching may be done by passing the yarn or filaments around rollers rotating atprogressively increasing peripheral speeds or between the positive nip of pairs of rollers rotating at progressively in. creasing peripheral speeds, and this stretching may be accomplished in only one stage or in a multiplicity of stages.. lThe cooling of the yarns or filaments for stretching may be accomplished through the temperature of the surrounding atmosphere, but particularly good results are obtained by rapidly cooling the yarns or fllamen... by immersion in a relatively cold non-solvent such as water, which if desired may contain dyes, alkali for saponification, or other desired substance.' This stretching operation may be carried out concomitantly with the spinning operation, i. e., after the filaments are extruded and before they are wound onto packages; or as a separate operation, namely after the yarn has been formed and wound onto packages. If desired the stretching may be done on the yarns or filaments -While they contain plasticizer. Alternatively the not for the cellulose acetate. In some instanceswhere increased pliability is desired, as in the Any suitable effect materials may be incorporated with the cellulose acetate prior to melting and extrusion to obtain any desired effect. Thus, if yarns or filaments of low luster are to be produced, -finely divided titanium dioxide, antimony trioxide, etc., may be incorporated therein. To produce colored y-am, dyes, or finely divided pigments of organic 'or inorganic character as carbon black, graphite, ultramarine, may be incorporated.

It is to beunderstood .that the foregoingdetailed description is merely given by way of illustration and that many variations may be made therein without departing from the spirit of our invention.`

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

1. Process for the production of filaments of organic esters of cellulose, which comprises melting an organic. ester of cellulose under a pressure applied directly thereto by a hot aqueous liquid, extruding the molten organic ester of cellulose under suchpressure through orices to form laments, andsetting said formed filaments.

2. Process for thev production of-illaments o'.' cellulose acetate, which comprises melting cellucellulose acetate, which comprises melting cellulose acetate under a pressure applied directly thereto by a hot aqueous-liquid, extruding the molten cellulose acetate under such pressure through orifices to form filaments, 'and setting said formed filaments.

3. Process for vthe production of filaments of cellulose aceto-propionate', which comprises melting cellulose aceto-propionate under a pressure applied directly thereto by a hot aqueous liquid,

' plied 'directly thereto by a. hot aqueous liquid, ex-

truding the molten cellulose aceto-butyrate under such pressure through orifices to form filaments, and setting said formed filaments.

5. Process for the production of filaments. of organic esters of cellulose, which comprises melting an organic ester of cellulose under a pressure applied directly thereto by hot water, extruding the molten organic ester of cellulose under such pressure through orifices to form filaments, and setting said formed filaments.

6. Process for the production of filaments of cellulose acetate, which comprises melting cellulose acetate under a pressure applied directly thereto by hot water, extruding the molten cellu- 'lose acetate under such pressure through orifices -to form filaments, and setting said formed filaments.

'1. Process for the production of filaments of organic esters of cellulose, which comprises melting an organic ester -of cellulose under'a pressure applied directly thereto by a hot aqueous liquid, extruding the molten organic ester of cellulose under such pressure through orifices to form lalose acetate under a pressure applied directly thereto by hot water, extruding the molten cellulose acetate under such pressure through orifices to form filaments, and cooling the formed fila- -ments atleast until they are solidified;

' thereto` by hot water, extruding the molten cellulose acetate under such pressure through orifices to form filaments, cooling the formed filaments at least until they are solidied, and stretching said filaments.

13. Process vfor the production of laments of cellulose aceto-propionate, which comprises melting cellulose aceto-propionate under a pressure applied directly thereto by hot water. extruding the molten celluloseV aceto-propionate under such pressure through orifices to form laments, cooling the formed filaments at least until they are solidified, and stretching said filaments.

14. Process for the production of filaments of cellulose aceto-butyrate, which comprises melting cellulose aceto-butyrate under. a pressure applied directly thereto by hot water. extruding the molten cellulose aceto-butyrate under such pressure through orificesto form filaments, cooling the formed filaments at least until they are solidified, and stretching said filaments.

15. Process for the production of filaments of organic esters of cellulose, which comprises melting an organic ester of cellulose under a pressure applied directly thereto by hot water, extruding the molten organic ester of cellulose under such pressure through orifices to form filaments, coolorganic esters of cellulose, which comprisesmelting an organic ester of cellulose under a pressure applied directly thereto by hot water, extruding the molten organic ester of cellulose under such pressure through orices to form filaments, and cooling the formed filaments at least until they are solidiiied.

10. Process for the production of laments of atleast until they are solidied, and stretching said filaments in the presence of a cooling CAMILLE DREYFUS. GEORGE SCHNEIDER.

medium.`

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