US2468827A - Electrostatic control of fibers - Google Patents

Description

y 1949. E. s. KENNEDY ErAl.

ELECTROSTATIC CONTROL OF mamas Filed 001;. '4, 1944 INVENTORJ BY @4 a. m

Patented May 3, 1949 ELECTROSTATIC CONTROL or arenas Edgar S. Kennedy, Wayne, and Frederick C.

Wedler, Media, Pa., asslgnors to A merican v-iscose Corporation, Wilmington, Del., a corporation of Delaware Application October 4, 1944, Serial No. 557,190

3 Claims. 1

This invention relates to the formation of seemingly continuous structures comprising substantiallyparallelized overlapping fibers directly from loose masses of disordered heterogeneously disposed fibers of spinnable length by a single step procedure.

Fibers adapted for spinning are obtained initially in the form of tangled masses in which the fibers are matted and clumped together. after subjecting the tangled fibers to an opening operation, they are in the form of loose masses in which the fibers project in all directions; In order to convert such loose masses into a structure in which the fibers are substantially all parallelized it is common practice to subject them to a series of more or less complicated mechanical operations including picking, carding,treatment in a roving doubler, and in a combing machine. Such operations have the disadvantage that they are wasteful, because aconsiderable quantity of the fibers are broken and must be discarded. Further, the severity of the many operations is such that the surfaces of the fibers are scarred and mangled, thus impairing the appearance and quality of articles formed therefrom in subsequent processing, and, if the fibers are lustrous, some of the lustre is dimmed, whic is undesirable in some cases.

In accordance with the instant invention, the numerous pre-treatments conventionally employed precedent to formation of structures such as webs, bats, mats, spinnable slivers etc. are eliminated, and loose masses of disordered fibers of spinnable length are directly converted to an extremely compact, even, and heavy product in which the individual fibers are laid back upon one another in overlapping, parallelized condition.

'According to the invention, loose masses of disordered fibers of spinnable length are subjected to the influence of an electric field of sufficient force and quality to polarize or orient the individual fibers comprising the masses, and

straighten out all of the fibers in parallelized condition in a given direction determined by the lines of force in the field. More specifically, the

invention contemplates establishing an electrostatic field, imparting relative movement to a surface with respect to theelectric field, feeding the loose masses of fibers of spinnable length di- Even to orient the individual fibers in erect position parallelized condition, to form a seemingly continuous structure, and removing the structure from the surface; The structure comprising the overlapping fibers may be condensed or compacted to the desired size or conformed to the desired shape. The invention further contemplates I the provision of electrode members, means for setting up an' electrostatic field between the electrodes, a surface, means for imparting relative movement to the surface with respect to the field, means for feeding the loose masses of spinnable fibers directly to the field, means for laying the fibers in overlapping condition, and means for removing the overlapping fibers from the surfaceand means for condensing, compacting or shaping the structure.

In the accompanying drawings,

Figure 1 is a diagrammatic elevational view of apparatus which may be used in carrying out the invention;

Figure 2' is a modification of the apparatus shown in Figure 1; and

Figure 3 is another modification of the appa-v ratus of Figure 1.

Referring more specifically to Figure 1, the

' loose masses of disordered fibers are shown dropping from a hopper 2, onto an endless conveyor belt 5 which may be made of any non-conductive material, and which passes around pulleys 6 and I. Conveyor belt 5 carries the fibers into an electric field of appreciable strength, for example, of 6,000 to 10,000 volts perinch, which is set up between two relatively flat electrodes 8 and 9. Under the influence of the so-called lines of force of the electric field which, in the arrangement shown in Figure 1 are represented by lines I 0, and which leave the electrodes perpendicularly to the surface, the fibers move away from the surface of belt I and are oriented in erect position on the under-surface of endless belt H which is of non-conductive material and which is positioned above belt 5. Belt II is positioned so that it converges with respect to belt 5 in the direction of travel of the fibers on belt 5. As belt ll travels around rollers l2 and I3, and pulley "in, the oriented erect fibers shown at It brush against a fixed bar or rod 15 interposedbetween belts 5 and II. Rod or bar I5 is preferably a grounded metallic member, so that any electrostatic charges carried by the fibers are discharged therefrom. The fibers are laid back upon themselves with their ends overlapping to form a seemingly continuous structure in which all of the fibers are straightened out and arranged in parallelized overlapping condition. The structure I6 leaving the path defined by belts and II passes over roller Ito and is directed to a condensing compacting, and/or conforming device. Where the fibers in the mat are not sufficiently coherent to enable the seemingly continuous structure to be conveyed to roller IGa without additionalsupport, the structure may be conveyed to the condenser over a belt conveyor such as the endless belt conveyor shown at [9 in Figure 2. As shown, the structure is directed to a. rotating cone-shaped condenser l1 driven by gear lla where it is condensed to the desired size and given a false twist. Such a device is useful when the product it is desired to form is a spinnable sliver. The condenser I! may be replaced by any other suitable condensing or compacting means, or by a conforming .device to impart the desired shape to the structure. A driving mechanism (not shown) turns pulley I at a speed to move belt 5 through the electrostatic field at the desired speed. A similar device may be employed to drive pulley l3a, controlling the speed of movement of belt II. The

relative speeds of belts 5 and II may be varied but in general it is preferred to move belt II at a slower speed than belt 5, because such a speed differential permits a denser and more compact deposition of the erect fibers on belt II. The density and compactness of the fibers on belt ll may be controlled, also, by appropriate adjustment of the relative widths of belts 5 and II.

In Figure 2 there is shown a modified arrangement, in which the fibers are fed from a hopper 2 into a blower I8. The masses of fibers, suspended in the current of air or other gas are opened and the separated individual fibers are dispersed directly into the electric field established between electrodes 8 and .9, and are oriented in erect parallelized position on the under surface of belt I I. In the arrangement shown in Figure 2, the belt 5 serves as a collecting surface for any fibers which do not enter the electric field directly from blower 18. If any such fibers are collected on belt 5, they are brought into the electrostatic field by travel of belt 5 around pulleys 6 and l and are oriented in erect position on belt H. An endless belt I9, which passes around suitably driven pulleys and 2|, is positioned so that one end thereof projects into the exit end of the path defined between belts 5 and H, and in close proximity to the under surface of belt ll. During the course of travel, of belt II, the fibers oriented in erect position on the under surface thereof contact belt l9. The speed of belt II is greater than the speed of belt l9, so that when the erect fibers contact belt l9 they are laid back upon one another in overlapping parallelized condition. The overlapping parallelized fibers are removed from the surface of belt I I in the form of a seemingly continuous structure or band "5 which is carried on the surface of belt I9 to the condensing devic ll. Preferably, belt I 9 is made of an electro-conductive material so that any residual electrostatic charges carried by the erect fibers emerging from the electrostatic below or above belt 5, for mechanically agitating the fibers prior to entry thereof into the electrostatic field. Such mechanical agitation serves to 4 assist in disintegrating the loose masses of fibers.

When the apparatus shown in Figure 2 is employed in carrying out the invention, the compactness and density of the erect fibers on the undersurface of belt Il may be varied as desired by adjusting the speed of belt H with relation to the pressure under which the fibers are blown into the electric field.

Generally speaking, the spinnable fibers lend themselves more readily to electrostatic orientation when they are in substantially dry condition. In many cases, it may be desirable to pass thefibers through a heating zone prior to feeding them to the electric field. For this purpose there may be provided any suitable heating or drying means suchas the heating chamber 3 shown in Figures 1 and 3. The chamber is'provided with inner walls 4 comprising radiating surfaces which receive and reflect heat furnished by electric resistance units 4a. It is desirable to provide such a chamber, or equivalent drying means, when the fibers consist of or comprise regenerated cellulose. Such fibers have a normal atmospheric moisture content of from about '7 to 11% and it has been found that improved results are obtainable in the present case if the moisture content is reduced to about 1% or less prior to exposure of the fibers to the electrostatic field.

Electrode 8 is preferably connected to ground, as shown at 23,- and electrode 9, insulated from ground, is maintained at high potential by conmeeting it to a high potential current source through conductor 24. The electrodes may be energized with a direct current, or with a rectified alternating current of high potential by means well known in the art. The electric field set up between the electrodes is uni-directional, electrode 9 being preferably negative with relation to electrode 8.

The electrodes 8 and 9 may be supported in any suitable manner, as by means of upright supports Y25 and 26 respectively. The distance between the electrodes may be adjusted at will but, in general, the electrodes are positioned'in compar'atively close proximity to each other, depending upon the length of the spinnable fibers.

, In the apparatus as shown, belts 5 and II pass directly over the surfaces of electrodes 8 and 9, respectively, but such an arrangement is not required and the belts may pass over the electrodes in spaced relation thereto.

If desired, hopper 2 may be replaced by or be connected with a staple fiber cutting mechanism for cutting continuous filaments into fibers of spinnable length and, in such case, the invention makes possible a direct and mosteconomical towto-top conversion. By such an arrangement a tow of freshly formed continuous filaments coming from a spinning machine, and which have been subjected to the usual after-treatments, may be cut to spinnable length and directly formed into a spinnable sliver, or a mat, web, bat or the like, without resort to an expensive combing operation, elimination of which greatly reduces the cost of the yarns and of the final products fabricated therefrom. I

By the practice of the present invention it is possible to form a spinnable sliver, for example, directly from loose masses of disordered spinnable fibers of any material, whether artificial or natural, including fibers of regenerated cellulose, cellulose acetate, or other cellulose derivative, nylons or other polymeric materials, wool, cotton, etc., and where the masses comprise several mixed varieties of spinnable fibers, a better and more uniform blending thereof is obtained. The sliver obtained by the method of the invention may be drafted and twisted in any well known or appropriate manner to form a yarn directly therefrom. Since the sliver is formed directly from the loose masses of disordered fibers without subjecting the fibers to picking, carding, combing or like mechanical operations, the fibers are not broken, and the surfaces thereof are not marred, so that in addition to the fact that the sliver is produced by 'dition, a third endess surface having a fiber-rea very economical method, yarns of superior qual- I ity are obtained.

It will be obvious that changes and modifications can be made in the above described apparatus and method within the scope of our invention which is not to be limited except as set forth 7 in the appended claims.

We claim: 1. Apparatus for forming a seemingly continuous structure of indefinite length from loose masses of spinnable fibers which comprises electrode members, means for continuously maintaining an electrostatic field between the electrodes, means for continuously feeding the spinnable fibers to the field, an endless surface above the zone of the field to which the fibers are fed and having a discharge portion extending out selves in overlapping parallelized condition on the second surface and carried thereby from the vicinity of the field in the form of a seemingly continuous structure.

2. Apparatus for forming a seemingly continuous structure of indefinite length from loose masses of spinnable fibers which comprises electrode members, means for continuously maintaining an electrostatic field between the electrodes, an endless surface, means for continuously moving the surface through the field, means for continuously feeding the spinnable fibers to the surface, a second endless surface above the zone of the field through which the first-mentioned surface carries the fibers and having a discharge portion extending out of the field, means for continuously moving the second surface through the field in the direction of movement of the first surface whereby the fibers carried on the first surface are electrostatically erected against the second surface in oriented and parallelized conceiving portion disposed closely beneath the fiber discharge end of the surface against which the fibers are erected in the field, and means for continuously moving the third surface in the direction of movement of the first and second surfaces whereby when the erected fibers contact the third surface all of the erected fibers are laid back upon themselves in overlapping parallelized condition on said third surface and carried thereby from the vicinity of the field in the form of a seemingly continous structure.

3. Apparatus for forming a seemingly continuous structure of indefinite length from loose masses of spinnable fibers which comprises electrode members, means for continuously maintaining an electrostatic field between the electrodes, an endless surface, means for continuously moving the surface through the field, means for continuously feedin spinnable fibers to the surface, a second endless surface above the zone of the' field through which the first-mentioned surface carries the fibers and having a discharge portion extending out of the field, means for continuously moving the second surface in the direction of movement of the first surface, said second surface being arranged in a plane converging to the plane of the first surface in the direction of movement of the surfaces, a third endless surface having a fiber-receiving portion disposed closely beneath the fiber-discharge end of the surface on which the fibers are erected which extends out of the field, and means for continuously moving the third surface in the direction of movement of the first and second surfaces whereby when the erected fibers contact said third surface all of the fibers are laid back upon themselves in overlapping parallelized condition on the third surface and carried thereby from the vicinity of the field in the form of a seemingly continuous structure.

EDGAR S. KENNEDY. FREDERICK C. WEDLER.

REFERENCES CITED The, following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,549,875 Home Aug. 18, 1925 1,604,406 Gayle Oct. 26, 1926 1,636,977 Anderson July 26, 1927 1,968,860 Strang Aug. 7, 1934 1,968,861 Strang Aug. 7, 1934 2,166,385 Wintermute July 18; 1939 2,231,324 Crompton Feb. 11, 1941 2,257,997 Barnes Oct. 7, 1941 2,272,247 Paulus Feb. 10, 1942 2,442,880 Schwartz June 8, 1948

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