US1773969A - Process of and apparatus for making artificial filaments - Google Patents

Description

Aug. 26, 1930. c, us ET AL 1,773,969

PROCESS OF AND APPARATUS FOR MAKING ARTIFICIAL FILAMENTS Filed Sept. 8, 1928 1 321.1? Tifia 31? O O INVENTORS CAMILLE DREYFUS HITEHEAD 8 BY WILLIAZ W ATTORNEYS Patented Aug. 26, 1930 UNITED STATES OAIILLE DBEYI'US, NEW YORK, N. Y., AND WILLIAM LAND, MARYLAND, ASSIGNORS TO CELANESE CORPORATION 01 AMERICA, A COB- POBATION OF DELAWARE PROCESS 01 AND APPARATUS FOR MAKING ARTJJICIAL IILAmTB Application fled September 8, 1928. Serial 10. 304,808.

This invention relates to process of and apparatus for the production of artificial fi aments such as artificial silk, bristles, horse hair and the like from solutions containing 5 cellulosic material[ An object of our invention is to provide a process of and apparatus for the production of artificial filaments that have more regular cross section than have artificial filaments that have heretofore been made.

Another object of our invention is to spin solutions of cellulosic material through orifices having squat shapes and which have indentations therein, whereby filaments of more uniform rigidity and pliability in all directions may be produced. Other objects of our invention will appear in the following detailed description.

In the spinning of filaments from cellulosic material, the practice has been to extrude the solutions through circular orifices into a precipitating bath or evaporative atmosphere. In such process, the outer layer of the filament or stream of cellulosic material, which is at first circular in cross section, hardens or solidifies first, forming a skin that is tougher and less fluid than the interior of the filament. After the initial hardening of the outer surface, the interior of the filament is precipitated or dried and thereby shrinks, While the outer layer has further hardened. Since the outer shell of the filament is tough er and more determined in shape than the interior, the contraction of the volume of the interior causes the outer film or layer to col lapse, and assume a very irregular cross section which is in the form of a figure of manyindentations of varying sizes and shapes, and which is often quite flat. Because of the irregularity of shape and the flatness of-the cross section of such filaments, their covering power, their pliability and their lustre are quite irregular. We have found that if instead of using circular orifices for spinning, holes having predetermined indentations therein are employed, more uniform filaments may be formed.

In accordance with our invention, we form filaments by extrusion of solutions of cellulosic material ina suitable solvent through orifices of squat shape having indentations in the form of reentrant angles or cus s into a recipitating or cvaporative atmosp 'ere.

ilaments of any suitable size may be formed by our invention. Thus filaments of say 1 to 10 denier, such as are used for making artificial yarns, may be made by our process. These filaments may be used as such, or they may be associated or twisted together to form yarns that are useful for making woven or knitted fabrics. The filaments formed by our invention may be heavier, say of 20 to 2000 denier or more, and'may be used as artificial bri'stlesin themaking of various brushes, for making braids, or for making artificial furs, etc.

The cellulosic materials employed in our precess may be any suitable ones that are used for making artificial filaments. Thus our process may be used in the making of reconstituted cellulose from viscose or by the cuprammonium or Chardonet process. This invention is particularly applicable for making filaments from organic derivatives of cellulose such as organic esters of cellulose and cellulose ethers. Examples of organic esters of cellulose are cellulose acetate, cellulose formate, cellulose propionate and cellulose butyrate; while examples of cellulose ethers are ethyl cellulose, methyl cellulose and benzyl cellulose.

When employing organic derivatives of cellulose in our process, the same may be dissolved in any suitable volatile solvent such as acetone, mixtures of acetone and ethyl or The orifices through which the solutions of cellulosic material is extruded should be of squat shape having indentations therein.

They may be in the form of polygons having reentrant angles, or they may be in the form of curved figures having reentrant cusps therein. Moreover they maybe in the form having some straight sides and some curved sides. The orifices may be wholly symmetriployed, the filaments are extruded into a recipitating aqueous bath containing aci .or

any other precipitating agent. If organic derivatives are used, the solutions may be 1 extruded into a bath containing a liquid that forms a solution with the solvent, which solution is a non-solvent for thecellulosic deriva-' tive. For instance, when a solution of an acetone soluble cellulose acetate in acetone is spun, the precipitating bath may consist of water. If'a dry spinning process is employed, the filaments are extruded into a dry evaporative atmosphere such as air, carbon dioxide, nitrogen or other gas that has no deleterious ao-efl'ect upon the filaments formed. This atmosphere is preferably maintained at a temperature at or near the boiling point of the solvent employed. 1

By employing orifices of the shape de- 2 scribed, what probably takes place is that the solution of the cellulosic material, when extruded through the orifices assumes approximately the shape of such orifices. At the indentations, or reentrant angles or cusps, the solution does not dry as rapidly as the outermost portions, due to the fact that the precipitatingbath or the heated evaporative atmosphere does not have as strong effect at the interior portions as they do at the exterior points. This is because the precipitating bath is more saturated with the products of reaction or the evaporative atmosphere is more saturated with the vapors of the solvent at the interior points, since it is w more confined at these places and less open to the main precipitating bath or drying atmosphere. When upon further exposure to the precipitating bath or drying atmosphere, the interior of the filament hardens and shrinkage occurs, collapse takes place only at the weaker or softer places corresponding to the indentations. Thus b suitably positioning these indentations, t e shape of the filament formed may be controlled. It will thus be seen that the filaments formed by our process have more uniform covering power and more uniform rigidity and pliability in all directions than have filaments formed. by extrusion through circular holes, and have a cross section whose shape is more regular than the cross section of filaments formed by the old process. In order further reference is hadto the accompanying drawing wherein Figures 1 to 8 are views on an enlarged scale of various forms of orifices that may be employed in our invention, and

Figures 1', 2 and 3 show the cross section on an enlarged scale of filaments formed to explain our invention,

gy extrusion through the orifices shown in ig. 1, 2 and 3 respectively. a I

In Fig. 1 is shown an orifice in the form of a regular polygon having right angles, in which all of the sides are equal in length and having the four reentrant angles indicatedvat 2. The cross section of the filament formed by such orifices is shown in Fig. 1. While we prefer to make the sides of the figure equal, they may be madefunequal, provided that the side 1 is not more than twice or\less than one-half of the side 3.

- In Fig. 2, the orifice is shown in the form of a symmetrical curved figure having the reentrant cusps 5. The cross section of the filament formed by extrusion through such an orifice is shown in Fig. 2.

In Fig. 3, the orifices are in the form of a regular polygon having sides of equal length and having apices 8 in the form of acute angles, and having the obtuse reentrant angles 9. The cross section of a fila ment formed by such an orifice is shown in Fig. 3.

In Fig. 4 is shown a cluster of four small round holes 10 placed close together so that the filamentsafter extrusion coalesce to form a single filament. This cluster of orifices operates under the same principle as the single orifice shown in Fig. 2, and forms a single filament much like the filament formed by extrusion through such single orifice.

In Fig. 5 is shown an orifice of polygonal form having reentrant angles 12, and is a combination of the forms shown in Figures 1 and 3.

Fig. 6 shows an orifice having the reentrant cusps 14, and is a combination of the forms shown in Figures 1 and 2.

Fig. 7 shows an orifice having reentrant cusps 16 and is a combination of the forms shown in Figures 2 and 3.

Thus it will be seen that the number of orifices that may be employed in accordance with our invention is ractically unlimited. Instead of employing t e form shown in Fig. 1, which is wholly symmetrical, a form shown in Fig. 8 may be employed, wherein the area of the portion 18 is less than that of the portion 19.

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

Havin described our invention what we claim and desire to secure by Letters Patent 1. In the method of forming filaments from solutions of cellulosic materlal, the step of extruding such filaments through an orifice in the form of a squat figure having indentations therein.

2. In the method of forming filaments from solutions of oellulosic material, the step of extruding such filaments throu h an orifice in the form of a squat figure aving reentrant angles or cusps therein.

3. Method of forming filaments comprising extruding a solution of an organic derivative of cellulose in a volatile solvent through an orifice in the form of a squat figure having indentations therein into a heated evaporative atmosphere.

4. Method of forming filaments comprising extruding a solution of cellulose acetate in a volatile solvent through an orifice in the form of a squat figure having indentations therein into a heated evaporative atmoshere.

5. Method of forming filaments comprising extruding a solution of an organic derivative of cellulose in a volatile solvent through an orifice in the form of a squat figure having reentrant angles or cusps therein, whereby filaments of substantially uniform covering power and substantially uniform rigidit and pliability in all directions is for'medl 6. Method of forming filaments comprising extruding a solution of cellulose acetate in a volatile solvent through an orifice in the form of a squat figure having reentrant angles or cusps therein, whereby filaments of substantially uniform covering power and substantially uniform rigidity and pliability in all directions is formed.

7. Filaments of cellulosic material havin substantially uniform covering ower and substantially uniform rigidity an liability in all directions, such as is formed y extrusion through an orifice of squatform having indentations therein.

8. Filaments of organic derivative of cellulose having substantially uniform cover ing power substantiall uniform rigidity and pliability in all directions, such as is formed y extrusion through an orifice of squat form having indentations therein.

9. Filaments of cellulose acetate havin substantially uniform covering ower and substantially uniform rigidity an liability in all directions, such as is formed y extrusion through an orifice of squat form having indentations therein.

10. A spinnerette having an orifice in the form of a squat figure having indentations therein. I

11. A spinnerette having an orifice in the form of a squat figure having reentrant angles or cusps therein.

In testimony whereof, we have hereunto subscribed our names.

OAMILLE DREYFUS. I WILLIAM WHITEHEAD.

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