US2596128A - Method and apparatus for producing fine fibers - Google Patents

Description

May 13, 1952 M. A. cHAvANNEs Erm. 2,596,128

METHOD AND APPARATUS FOR PRODUCING FINE FIBERS Filed OCT.. 17, 1949 6 Sheets-Sheet l faire] eff? May 13,' 1952 2,596,128

M. A. CHAVANNES TAL METHOD AND APPARATUS FOR PRODUCING FINE FIBERS Filed Oct. 17, 1949 6 Sheets-Sheet 2 May 13, 1952 M. A. cHAvANNr-:s ETAL f 2,596,128

METHOD AND APPARATUS FOR PRODUCING FINE FIBERS Filed oct. 17. 194s 6 sheets-sheet 5 1552/58 f6] J6? 167 J70 JZ! 176 f7.9 .782 135 .788 J3! 1.9,? )197 200 203 Z06` May 13, 1952 Filed Oct. 17, 1949 M. A. cHAvANNEs :a1-AL 2,596,128 METHOD AND APPARATUS FOR PRODUCING FINE FIBERS s sheets-sheet 4 l l l l l 4a? 4Z 44 46 48 sa 52: f4 .55 58 6o 62 64 66 da 7o 72 74 76 May 13, 1952 M. A. CHAVANNES ETAL METHOD AND APPARATUS FOR PRODUCING FINE FIBERS Filed Oct. 17, 1949 6 Sheets-Sheet 5 May 13, 1952 M. A. cHAvANNEs Erm. 2,596,128

METHOD AND APPARATUS FOR PRODUCING FINE FIBERS Filed Oct. 17, 1949 6 Shets-Sheet 6 Z 77 Mre fol/1s @WFM Patented May 13, 1952 METHOD AND APPARATUS FOR PRODUCING FINE FIBERS Marc A. Chavannes, New York, N. Y., and John C.

Elliott, Madison, Wis., assignors, by mesne assignments, to Chavannes Synthetic Fibres, Inc., a corporation of Delaware Application October 17, 1949, Serial No. 121,855

13 Claims.

This invention relates to a method for treating fibers, and more particularly to a method and apparatus for preparing extremely iine fibers from thermoplastic resinous polymers.

Heretofore many synthetic polymers, such as for example, polyvinylchloride, polyvinylidenechloride and copolymers of vnylidenechloride and vinylchlorides, have proved extremely useful in the textile field in the form of oriented bers. However, a drawback for these bers has been the diculty of extruding them in thicknesses of less than about .004 inch. Y

An object of the present invention is toprovide a method for preparing lms and bers of polyvinylidine, or polyvinylchloride or their copolymers, in any desired degree of neness.

Another object is to produce, as an article of manufacture, exceedingly fine strands of polymers which it has not previously been possible to prepare in such very fine form.

series of operations, and then to 1/ mil diameter in the second set of operations. Fibers made of copolymer of vinylidenechloride and' vinylchloride may readily be converted by our process to iibers of 1 mil diameter and lower.` Thus by a sequence of disarrangement and drawing operations, it is possible to draw a heavy extruded textile ber to almost any desired degree of neness.

In accordance with another embodiment of our invention we heat a fiber, comprising a cosubmit it to a temperature of 38 to 80 C. and

A still further object of this invention is to provide a new method of handling and drawing bers. Further objects will become apparent as the following detailed `description proceeds, reference being made to the accompanying drawings wherein:

Figures 1 through 4 are diagrammatic curves showing the results obtained with a sample of a representative liber of 10 mil diameter composed of an oriented copolymer of vinylchloride and vinylidenechloride. Figures 5 and 6 are diagrammatic views of two devices for carrying out the process of ourlinvention. l

In accordance with our invention in its broad aspect, we first disorient an oriented ber by heating the ber to a temperature within the temperature range at which the fiber undergoes plastic flow, and then either at the plastic `iow temperature or below this temperature draw the ber to a substantial extent, as for example, 100 of its length or greater, and then repeat the procedure of disorienting and drawing.

In accordance with a preferred embodiment of our invention, the fiber, after being heated and allowed to shrink, is rst drawn in the plastic flow temperature range to a small extent, as for example, to its length before shrinkage, or from 50% to 200% of its length after shrinkage, then supercooled below the plastic flow range and drawn to a larger extent, as for example, 400% to 5000% of its original length at the lower temperature. The entire sequence of operations may then be repeated for the best results.

We may start with bers of -12- mils diameter, bring such fibers to 2 mil diameter in one then draw it to 10 to 50 times its original length at this temperature, producing a corresponding reduction in the thickness of the fiber. This ber of reduced thickness may then be subjected to a repetition of the same process and drawn again to 10 to 50 times its length, i. e., 100 to 2500 times its original length. Thus it is possible by further repetition of this process to draw the bers ad innnitum to any desired degree of neness, in a continuous process.

For further explanation of the process, we refer to Figure 5, which is a diagrammatic view of a device embodying the principles of our invention. In Figure 5, ber 1 enters the device at triplerolls (hereinafter, rol1s) 2 from which it passes into oven 3, cut away to show electric heating wire 4, insulation 5 and rolls 6. Rolls 2 maintain any tension in the fiber which :may bel necessary prior to its entry into the device. The ber passes from rolls 2 to rolls 6 which turn at a slower rate and allow :ber I to have substantially no tension and to shrink freely between rolls 2 and yl. The liber then passes to rolls I which turn faster than rolls 6, drawing the ber to approximately the length it had prior to entering the machine. Fiber I then enters oven 8 maintained at a lower temperature than oven 3 by electric resistance wire 9. The ber passes then through rolls I0 which turn at a faster rate, drawing the fiber to 4 to 50 times its original length. Fiber I then passes over idler roll II and may then pass on to other processing machinery or to storage or may be subjected to repetition of the process just described, as for example, in the device shown, where the liber passes over idler roll I2 to rolls I3 Vwhich turn at substantially the same rate as rolls I0. The ber then enters oven I4 maintained at substantially the same temperature as oven 3. Oven I4 is cut away to show electric resistance wire I5, insulation II and rolls I1. Inthis oven it passes through rolls I1 which turn at a slower rate to allow the ber to shrink freely between rolls I3 and I1. The ber then passes to rolls I8 which turn faster than rolls I1 and draw the ber out to approximately its original length. From rolls I8 ber I then passes to oven I9 maintained at Ysubstantially the same temperature as oven B.

l a wind up spool, respectively, for a ber 21. The

ber in passing from the supply spool to the wind up spoolV passes through a plurality of pairs of rubber covered rollers 28, 29, 30 and 3l. These rollers are driven at various peripheral speeds by means of worms 32, 33, 34 and 35, respectively, the worms being mounted on a common Vworm shaft 36. Suitable gearing 31, 38, 39 and 40, respectively, is interposed between the pairs of rollers and their respective worms; Between rollers 28 and 29 there is disposed a heating chamber 4I and a cooling chamber 43. The heat may' be developed by any suitable means, such as a resistance wire or by superheaters using radiant heat, or the ber may be heated by a blast of hot air which is supplied to the chamber 4I by means of a pipe 42, as shown. Similarly, the ber may be cooled by supplying coil air to the chamber 43 through pipe 44. A similar heating chamber 45 and cooling chamber 41 are provided between rollers 29 and 30, the chambers being [provided with supply pipes 46 and 48, respectively. A third set of heating and cooling chambers 49 and 5I are provided between rollers 30 and 3I, together with the Supply pipes 50 and 52, respectively.

In operation, the rollers 28 may be driven by means of worms 32 and gears 31, at 100 revolutions per minute so that the ber is fed into and through the chambers 4I and 43. In the chamber 4I Vthe ber is heated to approximately 170 C. which causes shrinkage, after which the ber is cooled as it passes through cooling chamber 43, so that at the time the ber is engaged by the rollers 29, it is chilled. As above indicated, the cooling may be effected bysupplying cold air of a temperature of approximately 10 C. through the supply pipe 44. The rollers 29 are driven at substantially 50 revolutions per minute in order to allow for the shrinkage which occurs in the heating chamber 4I. rThe rollers 30 may be driven at 100 revolutions Iper minute so that in passing through the heating and cooling chambers 45 and 41, respectively, the ber is Vrestored to its original length.y `In the heating chamber 45 the ber is heated to approximately 170 C. and it is suitably cooled in chamber 41 by cold air, at approximately 10 C., which is supplied thereto.

The main drawing operation occurs as the ber is drawn through heating` chamber 49 and cooling chamber 5I, and the last pairof rollers 3| may be driven at the speed necessary to effect the desired amount of drawing. For instance, the latter rollers may be driven at 600 revolutions per minute; the ber may be heated in chamber 40 up to 60 C.; and, it may then be cooled in cooling chamber 5I by cold air supplied thereto at a temperature of approximately 10 C.

The above described device is illustrative only since it will be appreciated that the speeds and temperatures are subject to considerable variation depending on the particular results to be obtained. In the above illustration, it is assumed that the diameter of the rollers is somewhat less than 4 inches so that the circumference of the rollers is substantially 1 foot. Thus, rollers 28 rotating at revolutions per minute serve to feed the ber at 100 feet per minute.

Suitable. means may be provided for driving the supply and wind up spools 25 and 28 at the proper rates of speed.

In each stage of the process it will be observed that the filament is chilled by cold air so that it is never touched by the rollers when it is in its heated condition.

Results obtained with bers of a copolymer of vinylidenechloride and vinylchloride (Saran) are shown by reference to Figures 1, 2, 3 and 4.

Fig. 1 is a graph wherein the initial heating temperature of the ber in a hot bath is plotted against the maximum length to which the ber could be drawn.

Fig. 2 is a graph'wherein the temperature of the drawing zone in which. the bers are drawn is plotted against the maximum length to which the ber could be drawn.

Fig. 3 is 'a graph wherein the hot bath temperatures of lfrom C. to 206 C. for the bers are plotted against the maximum inches of stretch of the ber. After disorienting the ber in the hot bath and stretching to 4 inches, the ber was drawn to 21 inches in a cold bath maintained at 68 C., removed and the drawing continued inV air until the ber broke.

Fig. 4 isa graph showing the effect of varying the cold'bath temperature from 40 C. to 80 C., the hot bath being maintained at 16B-169 C, The disorienting and stretching procedure was the same as described for Fig. 3.

It is Vnot essential to the invention how the heating is arranged. We may employ induction heating methods, hot air, radiant heat, or we may immerse the bers and pass them through baths of heated oil or any other heat transfer medium which does not attack or interfere with the bers. I

In this manner, the bers'are drawn to any desired degree of nenesss.

The applicability of the invention will become further apparent from the following specific examples which are given here by way of illustration only, and not in any sense whatever by way 'of limitation. The parts shown in the vexamples are by weight.

" Example I A two inch length of pigmented ber composed of a copolymer containing 85 percent polyvinylidenechloride and 15 percent polyvinylchloride and having a thickness of .012 inchv was immersed for 2 seconds inabath of oil .maintained at 113 C. while being allowed to shrink freely. While still in the same bath it was thenv drawn to its original length and was then immediately transferred to an oil bathrrnaintained at '68 C.

Y and drawn, in the bath, at the rate of 6 feetV per minute vto a length of 70 inches. The resulting 75 ber had a diameter of .002 inch.

A two inch length of pigmented ber composed of a copolymer containing 85 percent polyvinylidenechloride and 15 percent polyvinylchloride and having a thickness of .012 inch was immersed for 2 seconds in a bath of oil maintained at 155 C. while being allowed to shrink freely. While still in the same bath it was then drawn to its original length and was then immediately transferred to an `oil bath maintained at 74 C. and drawn, in the bath, at the rate of 6 feet per minute to a length of 21 inches. The resulting fiber had a diameter of .0015 inch.

Example III A two inch length of pigmented fiber composed of a .copolymer containing 85 percent polyvinylidenechloride and 15 percent polyvinylchloride and having a thickness of .012 inch was immersed for 2 seconds in a bath of oil maintained at 203 C. while being allowed to shrink freely. While still in the same bath it was then drawn to itsoriginal length and was then immediately transferred to an oil bath maintained at 68 C. and drawn. in the bath, at the rate of 6 feet per minute to a length of 39 inches. The resulting ber had a diameter of .0015 inch.

Eample IV A two inch length of pigmented ber composed of a copolymer containing 85 percent polyvinylidenechloride and 15 percent polyvinylchloride and having a thickness of .012 inch was immersed for 2 seconds in a bath of oil maintained at 190 C. while being allowed to shrink freely. While still in the same bath it was then drawn to its original length and was then immediately transferred to an oil bath maintained at 40 C. and drawn, in the bath, at the rate of 6 feet per minute to a length of 20 inches. The resulting liber had a diameter of .0018 inch.

Emample V A 1000 foot length of a pigmented fiber composedof a copolymer containing 85 percent polyvinylidenechlorideand 15 percent polyvinylchloride and having a thickness of .012' inch was Wound on a spool. The spool was then mounted in such a manner that the ber could be drawn from it and passed through a device comprising two oil baths and five sets of rollers which gripped the ber strongly and three idler rolls, substantially as shown in Figure 1. The first bath was maintained at 172 C. and the second at; 79 C. with electric heaters and controlling thermostats. The rolls were driven by a series of V-belts and chains and sprockets from a variable speed drive driven by an electric motor. The ber was passed through the apparatus at a rate which permitted it to shrink freely in the high temperature bath for 2.2 seconds and to be drawn to 0.96 times its original length, in the high temperature bath, inl second. The ber then passed from the hot bath into the cold bath and was drawn therein to 10.6 times its original length. The resulting fiber had a diameter of .002 inch.

Example VI A two inch length of fiber composed of a copolymer containing 90 percent polyvinylidenechloride and 10 percent polyvinylchloride and having a thickness of .015 inch was immersed for 3 seconds in a bath of oil maintained at 225 C. while being allowed to shrink freely. While still 6; in the same bath it was then drawn to approximately its original length and was then immediately transferred to an oil bath maintained at C. and drawn, in the bath, at the rate of 3 feet per. minute to a length of 56 inches. The resulting ber had a diameter of .002 inch.

Eample VII A two inch length of a pigmented polyethylene fiber having a thickness of .012 inch, of the type sold commercially as Avisco Type B was immersed for 15 seconds in a bath of oil maintained'at 132 C. while being allowed. to shrink freely. While still in the same bath it was then drawn to slightly over 1/4 its original length and was then immediately transferred to a bath maintained at 100 C. and drawn to 7.0 inches in length. It was then re-immersed in the 132 C. bath for 5 seconds while being allowed to shrink freely and was then transferred to the 100 C. bath and drawn to 8.5 inches. The resulting' fiber had a diameter of .0041 inch.

The above examples by no means exhaust the different possible applications of our invention. They have been shown by way of illustration only and not l'in any sense by way of limitation.

The eiamples have shown the use of polyethylene 'and of copolymers of vinylchloride and vinylidenechloride as the synthetic resins composing bers to which our invention is applicable. These are not to be considered limiting in any respect; the invention is not confined to these particular resins. Fibers formed from polyvinylchloride, polyvinylidenechloride and resinous copolymers formed by the copolymerization with vinylchloride or vinylidenechloride or copolymers of vinylchloride and vinylidenechloride of such other monomers as may be so copolymerized are also the subject of this invention. Such copolymers include for example; copolymers of vinylacetate or vinylbutyral with vinylchloride, vinylidenechloride or vinylchloride and vinylidenechloride, copolymers of acrylic acid esters or methacrylic acid esters with vinylchloride. vinylidenechloride, or vinylchloride and vinylidenechloride, and copolymers of styrene or dichlorostyrene with vinylchloride, vinylidenechloride, or vinylchloride and vinylidenechlolide. The bromides or other halide compounds corresponding to the above chloride compounds may also be used.

The .examples have shown the use of several methods for carrying out the heat treatment of a berl according to our invention, but these are not to be considered limiting in any way. Our invention contemplates the use of any method of heating which can be applied to a synthetic resin fiber and the application of heat to bers in both continuous and non-continuous devices. Such heating may be accomplished in the following ways, for example: with an oven, with a liquid bath, with induction coils, with radiant bulbs or surfaces, or by passing the ber over heated rollers.

Wei prefer tc carry out the initial heating step in the process of our invention at temperatures of 130 to 240 C. for a duration of 2 to 15 seconds. Useful results, however. are obtained at temperatures of to 245 C. and durations of .5 to 30 seconds. We prefer to draw the fibers to at least 1/gtheir original length and to not more than 11/2 times their original length while still at the temperature of the initial heating, but useful results are obtained if the bers are drawn to from 1A to 2 times their original length at this temperature. We prefer to maintain the temperature of theV second or low-temperature zone, in which the fibers are drawn to `4 to 50 times their original length, at 35 to 110 C.V but useful results are obtained at 30 to 220 C. Satisfactory results are obtained if the drawing steps are carried out at drawing rates of 1 to 50 feet per minute but best results are obtained if the drawings are carried out in the preferable range of 3 to 25 feet per minute. The rates shown by the examples are not limiting.

Figures 1 and 2 show, diagrammatically, the result of applying this invention to .012" diameter fibers composed of a copolymer containing 85 percent polyvinylidenechloride and 15 percent polyvinylchloride. The method of this invention was applied to samples of such bers and various temperatures were used for the different steps of theprocess.

The curve of Figure 1 shows the length to which such fibers could be drawn at 6 feet per minute at 68 C. after being immersed for a period of 2 seconds in a bath of oil held at various temperatures while being allowed to shrink freely and after then being drawn to approximately their original length at the same temperature. in this curve; Athese occur at 173 C. and 190 C. and fibers could be drawn to 3360 and 3220 percent of their original length, respectively, after initial heating and drawing at these temperatures.

The curve of Figure 2 shows the length'to which such bers could be drawn at Variousi temperatures, using a drawing rate of 6` feet per minute, after being immersed for 2 seconds in an oil bath heldat 168 to 169 C. while being allowed to shrink freely and then being drawn to approximately their original length at the same temperature. This curve also has two sharp peaks. These are at 68 C. and 74 C.; fibers could be drawn to 3450 and 3500 percent of their original length, respectively, at these temperatures.

While we do not wish to commit ourselves to any particular theory as to the mode of function of our invention, it is our belief that the initial heating of the oriented fiber, which is accompanied by extreme shrinking of the fiber, produces disorientation of the polymeric molecules, effecting disarrangement of the molecular configuration and micellar arrangement. Drawing the fiber to 1/2 to 11/'2 times its original length Yat close to this same temperature is thought to cause some chemical unbonding of bonds which are weakened by the heating. Subsequent drawing to very-great lengths at lower temperature to produce a very thin fiber of reoriented molecules is made possible by this disorientation and unbonding. H Optimum temperature conditions for carrying out the initial heating and slight drawing occur above the softening point of -the resin. Optimum temperatures for the subsequent drawing to great length are found belowthe softening point.

It is to be fully understood that the invention is broad in scope, and is to be restricted only by the claims, in which it is our intention to cover all novelty inherent in the invention as broadly as possible, in View of prior art.

Having thus disclosed our invention, we claim A: 1. The process of producing a ne fiber from a thicker vfiber of an oriented` thermoplastic Two sharp peaks are observed resinous polymer which comprises disorienting the fiber by heating the fiber to a temperature at which the fiber undergoes plastic flow, allowing the fiber to shrink, drawing the fiber at a temperature within the plastic flow temperature range after the fiber has' undergone shrinkage, cooling the fiber to below the minimum temperature of plastic flow, and drawing the fiber at said lower temperature to a greater extent than at said higher temperature.

2. The process for producing a fine fiber composed of a copolymer of .vinylidenechloride and. vinylchloride which comprises heating an oriented fiber of said copolymer at 150 C. to 205 C. for 2 to 15 seconds with the fiber being allowed to shrink freely; drawing said ber to 1/2 to 11/2 times itsy original length at approximately the same temperature; and then drawing said fiber at 38v C. to 80 C., increasing its length 3 feet per minute Vat 25 feet per minute, to 10 to 50 times its original length.

3. The process for producing a fine fiber comprising a copolymer of vinylchloride and vinylidenechloride whichV comprises heating an oriented fiberV vcomprising a copolymer of vinylchlorideand vinylidenechl'oride at 120 C. to 245 C. for' 0.5 to 30 secondsv with said fiber being allowed to shrink freely; drawing said fiber to 1/4 to 2 times its originalrlength at approximately the same temperature; and then drawing said fiberat 30 C. to 220 C., increasing its length 1 foot per minute to 50 feet per minute, to 4 to 50 times its original length.

4. Apparatus for the processing of fibers or thev like comprising a plurality of vsuccessive means for engaging and feeding a continuous filament, thereby providing a path for the advance of said fiber, means disposed along said path between the first two of said feeding means for heatingsaid fiber to cause shrinkage thereof, driving means for operating the second one of said feeding means at a slower speed than the speed at which saidfirst feeding means is driven to compensate for said shrinkage, driving means for operating a third one of said feeding means at substantially the same speed as that at which said first feeding means is driven in order to draw said fiber to approximately its original length, driving means for operating a fourth one of said feeding means at a substantially greater speed than that at which said first feeding means is drivenin order to draw said fiber to a substantially greater extent than that at which it is drawn'by said third one of said feeding means, means disposed along said path between said third and said fourth feeding means for maintaining said fiber ata temperature substantially less than the`temperature to which it has been raised by said first mentioned heating means, and heating means disposed along said path between said second and third feeding means in order to' heat said fiber during the first of said drawing operations. f 5. Apparatus as claimed in claim 4 provided with cooling means between eachof said heating 'means and -the succeeding feeding means whereby said ber is chilled prior to the time that it is engagedby said feeding means.

6. Apparatus for producing a fine fiber comprising four sets of fiberfeeding rollers, three separate berheatingmeans, one of said heating means being disposed between each adjacent pair of sets of rollers, means for driving said rstand third sets `of ,rollers at approximately the same peripheral speed,-means for driving said second 9 set of rollers at a peripheral speed less than that at which said first and third sets of rollers are driven, and means for driving said fourth set of rollers at a speed greater than the speed at which said rst and third sets of rollers are driven.

7. Apparatus as claimed in claim 6 in combination with three separate ber chilling means, one fiber chilling means being disposed in front of each of said second, third and fourth sets of rollers whereby a continuous ber passing through each of said successive heating means will be chilled prior to the time that it is engaged by successive sets of rollers.

8. Apparatus as claimed in claim 6 in combination with common driving means for all of said sets of rollers.

9. The process of claim 1 wherein the polymer is polyvinylchloride.

10. The process of claim 1 wherein the polymer is a copolymer containing polyvinylchloride.

11. The process of claim 1 wherein the polymer is a copolymer of vinylchloride and vinylidenechloride.

12. The process of claim 1 wherein the polymer REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,161,766 Rugeley et al. June 6, 1939 2,183,602 Wiley Dec. 19, 1939 2,239,780 Fikentscher et al. Apr. 29, 1941 2,354,744 Dreyfus Aug. 1, 1944 2,367,173 Martin Jan. 9, 1945 2,476,830 Spencer July 19, 1949 O THER REFERENCES Sherman and Sherman: The New Fibers, Van Nostrand, New York, 1946, page 98.. (Copy in Division 15.)

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