US2036752A - Producing artificial structures, such as artificial silk, bands or the like, from viscose - Google Patents

Description

PRODUCING ARTIFICIAL STRUCTI JRES, SUCH AS ARTIFICIAL SILK, BANDS OR THE LIKE FROM VISCOSE Filed Nov. 5, 1931. 2 Sheets-Shem; l

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II R. 0 HIEHZOG If! PRODUCING ARTIFICIAL STRUCTURES, SUCH AS ARTIFICIAL SILK, BANDS OR THE LIKE FROM VISCOSE Filed Nov. 5, l93l 2 Sheets-Sheet 2 Patented Apr. 7, 1936 UNITED STATES PATENT OFt'l PRODUCING ARTIFICIAL STRUCTURES,

SUCH AS ARTIFICIAL SILK, BANDS OR THE LIKE, FROM VISCOSE Application November 5, 1931, Serial No. 573,234 In Germany November 12, 1930 7 Claims. (Cl. 18-54) This invention relates to a method of producing artificial structures, such as artificial silk, bands or the like from viscose.

It has already been proposed to spin viscose into filament-like structures by a dry method. In this connection the viscose solution is exuded under pressure through spinning apertures of a more or less fine nature, and the viscose streams thus formed are converted into the solid form by treatment with chemically active or hot ases.

According to the one method, the viscose is spun in the presence of gases containing carbonic acid, the filaments formed being coagulated under the action of this gas, and thereafter the final fixing process is performed by treatment with steam. This method, which is by no means of recent origin, has not been able to gain favor in practice, apparently owing to the fact that in the short time for which the filament remains in the spinning tube the carbonic acid, which is only present in gaseous form, is not in a position to coagulate the viscose filaments with a rapidity sufi'icient for practical purposes.

According to a second method, it is proposed in similar fashion to produce threads in staple form, with the use of hot gases as coagulating agent, and by simultaneous drying to recover the same, after they have fallen through the treatment chamber, from the bottom thereof.

This method is also incapable of use in practice, because when the longitudinally confined viscose streams fall through the hot air merely brittle, relatively thick, shrunk and consequently useless structures are obtained, due to the lack of any kind of tension in the filament.

Finally, it has also been proposed to pass viscose through extremely fine apertures of approximately 25 n or less, not otherwise usual in the trade, to perform preliminary coagulation in a hot atmosphere, for example air, and in an immediately following operation to draw the filaments in a diluted solution containing P04 ions for the purpose of fixing and conversion of the sulphur into a soluble form, the filaments then being wound. Experiments have shown that the forcing of ordinary viscose solution through apertures of a fineness amounting to 25 ,u or even less is accompanied by considerable difficulties; on the other hand it has also been found that the treatment of the filament, which has just been coagulated in the hot atmosphere, With the diluted, alkaline-efiective tri-sodium phosphate solution causes considerare dependent on the remaining conditions unable swelling and weakening of the filament, which by that time has not sufiiciently coagulated.

The invention relates to that class of dryspinning processes, in which the filaments emerg- 5 ing from the spinning apertures are treated with hot gases and coagulated.

It has been found that the temperature of the treatment gases plays a decisive part in proper 7 performance of the spinning process, and that 10 a steady and rational conduction of this process with the production of a filament possessing a suificient strength for the subsequent treatment is rendered possible if at least in one zone I of the treatment chamber surrounding the fila- 15 ment as it exudes, which zone is preferably sitdated not too far away from the spinnerette, a minimum temperature prevails which exceeds the temperature of decomposition of the cellulose, which is about C.

The gaseous medium employed for the treatment may be, for example, air.

Immediately the spun material has lost a certain proportion of its Water content, it is desirable to pass over to a lower temperature, which 5 may be accomplished in continuous process by conducting the material from the point of maxi-- mum temperature to that of lower temperature. By reason of this method of heating, in which, therefore, there is a marked drop in temperature in the direction in which the filament proceeds, there is initiated a very rapid evaporation of the water, and the product acquires a considerable strength in a very brief space of time, so that breaking of the filament is avoided. The maximum temperature capable of being employed, more particularly that of the zone in the immediate neighborhood of the spinnerette, and also the form of the optimal grades of temperature, 40 der which operations are performed, such for example as the desired drawing speed, the concentration and viscosity of the spinning solution, the thickness of the bands or filaments, the length of the apparatus, etc. 45

It is a surprising fact that the exceptionally high temperature of the treatment gases has no detrimental effect on the filament or causes the same to become brittle. This may be partly owing to the fact that with the considerable drawing 50 speed which may be attained by the method according to the invention the space of time is too short in which detrimental action on the filament might take place. Apprehension that the high temperature of the gases might cause the forma- 55 tion of blisters at those points where the filament is still more or less liquid or plastic, or even cause fracture or rupture of the outer parts of the filament has also proved to be unfounded.

For the purpose of the invention there are preferably employed viscose solutions which differ quite appreciably from those otherwise usual in the trade. Since the danger exists that upon the drying process an excessive alkaline condition and the separation of salts is liable to take place, it is preferable to employ the least possible concentrations of lye, in order not to impair the quality of the finished product. This, for example, may be accomplished. by the fact that the pressing of the liquor after the mercerization is extended beyond the usual degree, for example to two and a half times the dry weight of the cellulose. The dissolution may also take place, not in sodium lye, but in water, whereby there is employed a relatively small amount of sodium lye in relation to the cellulose, amounting to approximately half the quantity in weight, or even less. Dependent upon the production of the viscose, the absolute amount of NaOH may be reduced, for example, down to 41%.

In addition to this it is also of advantage to ensure that the cellulose solution is in a sufficiently tenacious or glutinous form. In the case of solutions revealing sufficient tenacity upon the drawing of the filament the advantage is obtained that the filament leaving the spinnerette possesses an appreciable strength before the treatment gases have had time to take effect thereon. This tenacity may be obtained either by increasing the concentration of the cellulose f. i. above 7% or by colloidal chemical influence on the size of the particles.

Thus, for example, the tenacity of the viscose solution may be increased by shortening the preliminary ripening process.

After the viscose filaments which have left the spinning apertures and are still in a liquid state have passed through the treatment gases, and during the time when the same are gradually hardening and are extensively dried, they are, after leaving the treatment chamber, before or after the final winding operation, subjected to the subsequent treatment necessary to convert them into saleable products. This consists more particularly in final coagulation and conversion into cellulose hydrate, removal of the dried salts and remnant caustic soda, and in removal of the sulphur, adhering traces of metal and dyes. For this purpose it is possible to employ the known de-acidifying, washing, de-sulphurizing, bleaching, avivating and like means.

The advantages of the invention reside in the possibility of even and rational spinning of the viscose at a high drawing speed, the possibility of the employment of spinnerettes with usual orifices, in obtaining a filament which is sufficiently strong to withstand the subsequent treatment whilst retaining a gas-treatment apparatus of technically reasonable length, and also in part in a saving in raw material, such for example as caustic soda.

Example 1 220 grammes of air-dried artificial silk cellulose are immersed for 2 hours in sodium lye of 18% strength at room temperature, and are then pressed to 600 grammes. After disintegration the alkali cellulose is allowed to ripen at room temperature over a period of 20 hours. For sulphurizing purposes there are employed 60 com.

of carbonic disulphide. After a further 10-l5 hours the xanthogenate obtained is dissolved by kneading in 1500 com. water. The cellulose solution is filtered, deaerated, and, at a later stage, is spun at a ripeness amounting to 4 Hottenroth. The filament emerging from the spinnerette, which is furnished with a cooling ring surrounding the same, is first conducted for a distance of cm. through hot air having a temperature of 250 C., and thereupon over a further distance of cm. at a temperature of 95. The continuously spun filaments are then wound outside of the gastreatment chamber, additionally treated and finished off.

Example 2 1 kilogramme of air-dried artificial silk cellulose is immersed for 1 hour at room temperature in sodium lye containing 220 grammes NaOH per litre, is then pressed to 2840 grammes, and disintegrated. The alkali cellulose is allowed to preliminarily ripen for a period of 5 days at 16 C. The same is then well sulphurized with 400 grammes carbon disulphide, and finally the xanthate is dissolved in water to form a viscose containing 15% cellulose and 7.5% NaOH. During the de-aerating process and up to the time spinning is performed the viscose is kept cool. The same is spun without any measurable degree of ripeness, i.e., before it has matured, ernploying a cooled spinnerette having ten apertures each of .15 mm. diameter.

The filaments sprayed out of the spinarette in a downward direction are allowed to fall through a sufficiently wide, vertical and heated pipe, which is sealed off against the spinarette towards the top with the exception of the requisite outlet apertures for the hot gas, and is open towards the bottom. The spinning tube is surrounded by a second pipe or tube for the purpose of insulation. The space between the two tubes is filled out with an insulating agent. The spinning tube itself is surrounded by insulated heating filaments, by means of which the inner tube, by suitable distribution and feeding of the electric current, may be heated to the desired temperatures in the different zones.

In the upper zone of approximately 1 metre length towards the spinarette there is maintained a temperature of 400-450 C. measured within the tube near the surface; the middle and lower zones, which are also each approximately 1 metre in length, possess correspondingly lower temperatures of 250 and 150 C. respectively. The filament drawn at the rate of 150 in. per minute runs out of the lower opening of the spinning tube in a practically dry state, and in the known manner is wound in bobbin form, and is subsequently fixed and additionally treated.

An apparatus suitable for carrying out the process described in the above is illustrated in the accompanying drawings.

Fig. 1 is a vertical front elevation view, partly in section, of the complete apparatus.

Fig, 2 shows on larger scale a detail of Fig. 1.

Referring now to the drawings, I is the vertical, cylindrical spinning tube, which is furnished at its upper, middle and lower portions with the separate windings 2, 3 and 4 of electrically heated wires. The ends 5 of each winding are connected, with the interposition of regulating resistances 6, with a source of current I over a switch 8.

By suitable adjustment of the three resistances 6 it is possible to produce various temperatures as desired in the respective sections of the spinning tube. To avoid loss of heat this tube is surrounded by a jacket 9, the space between the two being filled out with a suitable insulating material I0. In the upper end of the tube I there is fitted in gastight fashion a pipe socket I I, having lateral portions l2, l2 furnished with closure members I3, is and capable of being connected with a gas source. The upper part of the socket l l is widened out at 14, and serves for the reception of a cooling ring I 5, which is furnished with intake and discharge pipes I6, I! for the cooling Water and constitutes at the upper end a seat l8 for the actual spinnerette l9, which may be constructed in any desired manner, for example in the form of a rose. The interior of the spinarette i9 is connected by the screw 20 with the pipe 2| serving for the supply of spinning solution. Below the spinnerette l9 there is provided an annular jet pipe 22 having numerous outlet apertures on the inner side for a gaseous cooling agent, which is conducted to the annular pipe through the feed pipe 23. The other end of the pipe 2| is connected with the lifting pipe 24, which is conducted as far as the bottom of a tank 25 for the spinning solution. This tank 25 is fitted in a pressure-proof vessel 26, through the top of which there is passed the lifting pipe 24 in sealed fashion, and into which there also opens out a pipe 21, which leads to the regulating valve 28 of a compressed gas container 29 and. serves the purpose of forcing the spinning liquid at a pressure, which is capable of being controlled by the manometer 30, through the lifting pipe and the spinnerette.

For the purpose of controlling the temperature a thermo-electric pyrometer 3| is introduced into the spinning tube from the top, and leads to a mini-voltmeter 32, where the temperature may be read in direct fashion.

It is obvious that pyrometers may also be introduced at suitable points into the other zones. Since the spinning tubes possess quite a considerable height amounting to a few metres a platform 33 is provided half way to facilitate operations. The bundle of filaments exuding from the spinnerette I9 is, after traversing the tube l, engaged by a fixed filament guide 34 at the lower end and passed to a movable filament guide 35, to be then wound about the bobbin 36. The bobbin 36 and the movable filament guide 35 receive their motion from a motor 3! through the medium of the belt drives 38 and 39. The reciprocatory motion of the movable filament guide 35 is obtained by means of a cam 40.

It will be obvious that no restriction is made to the specific form of embodiment shown, and that various modifications are quite possible within the meaning of the above description and the annexed claims without departing from the spirit of the invention.

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

1. A method of producing artificial structures from a solution consisting essentially of viscose,

comprising spinning the solution into air, the temperature of which is approximately 400 C.

2. A method of producing artificial structures from a solution consisting essentially of viscose, comprising spinning the solution into heated air, subjecting the chamber into which the solution is extruded to a temperature control whereby the structure leaving the spinneret passes through zones of decreasing temperature, the range of temperature in the zone of highest temperature lying between 450 C. and C.

3. A method of producing artificial structures from a solution consisting essentially of viscose, comprising spinning the solution from a spinneret having a cooling ring surrounding the same into heated air, subjecting the chamber into which the spinning solution is extruded to a temperature control whereby the structure leaving the spinneret passes through zones of decreasing temperature, the range of temperature in the zone of highest temperature lying between 450 C. and 120 C.

4. A method of producing artificial structures from viscose comprising extruding viscose into a zone heated to a temperature of at least 120 C. and not exceeding about 450 C. and withdrawing the formed article with a speed suificient to prevent substantial destruction of the cellulose, but permitting coagulation of the viscose.

5. A method of producing artificial structures from viscose comprising extruding viscose into a Zone heated to a temperature from about 250 C. to about 450 C. and withdrawing the formed article with a speed sufficient tOl prevent substantial destruction of the cellulose, but permitting coagulation of the viscose.

6. A method of producing artificial structures comprising spinning a viscose solution under tension into an indiiferent gas atmosphere heated from 120 C.-450 C., the viscose solution having a cellulose content not exceeding 15% and an alkali content limited to about one half of the percentage of the cellulose content.

7. A method of producing artificial structures comprising spinning a viscose solution under tension into an indifferent gas atmosphere heated from 120 C.-450 C., the viscose solution having a cellulose content not exceeding 15% and an alkali content limited to about one half of the percentage of the cellulose content prepared by immersing cellulose in caustic alkali solution, pressing the resulting alkali cellulose to about 2.75 times the weight of the cellulose, disintegrating the pressed alkali cellulose, allowing the alkali cellulose to ripen for about 20 hours, sulfurizing the ripened alkali cellulose with carbon disulfide in quantity amounting to. not more than 30% of the cellulose, dissolving the xanthogenate in water in quantity amounting to about seven times the weight of the cellulose, deaerating and ripening the resulting viscose solution to a ripeness of 4 Hottenroth.

REGINALD OLIVER HERZOG. HELMUT HOFFMANN.

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