US2391973A

US2391973A - Apparatus for the production of artificial filaments

Info

Publication number: US2391973A
Application number: US436894A
Authority: US
Inventors: Hunter Archibald Stuart
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1942-03-30
Filing date: 1942-03-30
Publication date: 1946-01-01
Anticipated expiration: 1963-01-01

Description

Jan. 1, 1946. s HUNTER 2,391,973

APPARATUS FOR THE PRODUCTION OF ARTIFICIAL FILAMENTS Filed March 30, 1942 Archibald 5.Hun"[e1" IIIIIIIIEHHEHIIIWlillllll Patented Jan. 1, 1946 APPARATUS FOR THE PRODUCTION OF ARTIFICIAL FILAMENTS Archibald Stuart Hunter,

Kenmore, N. Y., assignor to E. I. du Pont de Nemours & Company. Wilmington, Dei., a. corporation of Delaware Application March 30, 1942, Serial No. 436,894

4 Claims.

This invention relates to the production of artificial filaments, and more particularly it relates to the production of artificial filaments having an uneven or irregular denier.

The most convenient and generally satisfactory method for producing continuous artificial filaments having varying deniers is to give to the stream of filament-forming solution passing through the spinneret, a pulsating motion. A number of processes and apparatus have been suggested for initiating this pulsating motion. In some cases, devices have been mounted between the metering pump and the spinneret which regularly and momentarily interrupt the flow oi filament-forming solution. It is also known to introduce a pulsating flow of filamentforming solution into the line leading from the metering pump to the spinneret.

However, where it is desired to produce artificial filaments with frequent and sharp variations in the denier so as to provide a particular effect in fabrics composed of the variable denier filaments, the methods and apparatus proposed heretofore are not in general satisfactory, principally because the variation in denier obtained was so slight and gradual that fabrics produced therefrom do not have the desired appearance. It is further noted that in most cases the thick portion of the filaments. while being of sufficient thickness, are quite long and not short and sharp as is desired in many cases.

It is, therefore. an object of my invention to provide means for the production of artificial filaments having an uneven denier in which the unevenness or irregularity of denier varies frequently and sharply.

It is a further object of my invention to provide means for the production of uneven denier yarn, which can be attached to conventional artificial yarn production mechanisms without extensive change or modification of such mechanism.

It is another object of the invention to provide a means for changing the fiow of filament-forming solution passing to a spinning nozzle from an even fiow to a pulsating fiow.

Other objects of the invention will appear hereinafter.

These objects are accomplished by my invention which comprises a gear pump mechanism the rate of delivery of which varies at least 400 times per minute, said mechanism consisting of a viscose metering pump of the gear type in which a portion of some or the gear teeth has been removed.

My invention will now be described with particular reference to the production of artificial filaments produced from viscose. The invention, however, is not restricted to the spinning of viscose but is applicable to the production of artificial filaments from cellulose derivative compositions in an organic solvent, which will be coagulable in the presence of heated gases, or it may be applicable to the production of regenerated cellulose or cellulose derivative filaments from solutions coagulable in a liquid coagulating bath. It is further applicable to the production of filaments from synthetic linear polyamides, polyvinyl alcohol, poiyvinyl acetal, polyvinyl acetate, vinyl chloride-vinyl acetate interpolymer, polyvinyl chloride. casein, and other filament-forming materials.

The invention will be more clearly apparent by reference to the following detailed descriptions taken in connection with the accompanying drawing, in which Fig. 1 is a diagrammatic elevational view of a typical fiow system showing flow pulsating device interposed between the candle filter and the spinneret.

Fig. la. is an elevation of a typical viscose metering pump with one of the side components of its casing removed to show the disposition of the gears therein and the position of the inlet and outlet ports relative to the gears.

Fig. 2 is a side view of the meshing gears used in the standard viscose metering pump of Fig. in. modified in accordance with my invention.

Fig. 3 is a top view or the gears of Fig. 2.

Fig. 4 is a side view partly in section and shows a different modification of the gears of Fig. 2.

Fig. 5 is a top view of the modification of Fig. 4.

Fig. 6 shows still another modification of the gears of Fig. 2.

Fig. '7 is a top view of the modification of Fig. 6.

Referring to Fig. l of the drawing, reference numeral l designates the pipe line for passing the viscose through pipe 2 to metering pump 5. The conventional viscose gear type pump 5 is driven through gears and drive shaft (not shown). The viscose is pumped from the metering or spinning pump 5 through pipe I to a candle filter Ill and then through pipe 9 to a modified metering pump 8 which, like pump 5, is driven by conventional means not shown. Pipe 9 should not have an inside diamete greater than /21,", and preferably it should be it". The modified pump 8 breaks up the regular flow of the viscose and transmits said viscose in a pulsating flow through gooseneck 3 to the spinneret l2. The modified pump 8, for the best results, should be as close as possible to the splnneret to prevent dampening out or the pressure surge. The modified pump should be placed between the candle filter and the splnneret for the best results. In addition, the candle filter ill and the gooseneck should be made of nonstretchable material to prevent a diminishing of the pressure surge effect.

For optimum results, the pressure on the viscose spinning solution at the inlet port of pump 8 should be greater than the pumping pressure of said pump. This will prevent pipe 8 from being sucked dry. Metering pump i supplies viscose to pump 8 at a pressure which should be sufllcient to keep the inlet ports of pump 8 filled at all times. If the pumping action 01' pump I exceeds that of pump 5, a bypass 29 around pump 8 may be installed to allow viscose to pass from pipe 3 to pipe 9 to prevent pipe 9 from being Sucked dry of viscose. Pipe 29 should be of small diameter, for example, 1'; inch.

1 will now describe how the conventional gear ty e spinning pump is modified to impart a pulsating fiow to the spinning solution carried therethrough. Referring to Figs. la, 2 and 3, reference numerals i3 and I3 indicate the meshing gears of the conventional pump, the teeth I4 and II of which normally coact to free a non-pulsating flow of spinning solution to the spinneret. Gears l3 and I3 are disposed in a casing indicated generally by the reference numeral it, which casing is provided with the usual fluid inlet and outlet ports I! and respectively. According to my invention one side of each tooth of a roup of adjacent teeth of gear i3 is removed, and the same side of each tooth of a corresponding group of teeth of gear I3 is removed, leaving the remainin teeth of gear I 3 and corresponding remaining teeth of gear l3 untouched. As a result there is a pocket or channel l5 formed between the gears to the sides of the teeth which have been partly cut away. Therefore, in place of an even fiow of spinning solution through the pump, gears I3 and ill by reason of pocket I! coact to deliver a pulsating flow, the pulsations of which vary in frequency and amplitude in accordance with the speed of the pump and the number, size and shape of the pockets formed between the gears.

Figs. 4 and 5 show an inner pocket II in the gears l3 and i3, which pocket has a tapered shape. When these gears revolve, the tapered rear portion 01' the pocket aids in forming the thin connecting section of the filament between the thickened portions, and therefore aids in preventing broken filaments.

Figs. 6 and 7 illustrate another modification of the gears shown in Fig. 2. Gear is is shown with some of the teeth I unmodified, while parts of other teeth have been removed to provide an inner pocket I1 in the teeth. The coacting gear i3 is modified in the same way as gear it.

In the practice of the invention, a metered quantity of viscose is passed continuously from the spinning pump 5 through candle filter ill to the modified gear pump mechanism 8, which pulsates at least 400 times per minute. The viscose, after it has passed through the special geared valve mechanism, moves along to the spinneret in very short rapid surges. The variable delivery of viscose to the spinneret, as represented by the short rapid pulsations, in combination with a constant drawofl produces a yarn which has thickened portions at intervals along the length of individual filaments.

The following specific examples will more clearly illustrate the operation of the present invention under actual operating conditions. Percentage parts are by weight unless otherwise indicated.

Example I A 7% cellulose, 6% caustic bright viscose is metered at the rate of 24 grams per minute through a metering pump (No. 1 Zenith pump) passed through a candle filter, and fed through a M; inch line to a modified pump (No. Zenith pump). In this modified pump, each gear has two 9-tooth side pockets. The pockets are made by cutting away inch of the sides of 9 adjacent teeth. The two pockets on a given gear are opposite each other and have four unaltered adjacent teeth intervening. The gears are so positioned in the pump that the pockets of the drive and the driven gear come together and thus form an open valve directly through the pump twice each time the gear is rotated. This pum is rotated at 1140 R. P. M. On leaving this new pump, the viscose passes through a 10 inch gooseneck and through a 40 hole spinneret into a coagulating regenerating bath containing 9% sulfuric acid, 19% sodium sulfate, 4% glucose, and 0.7% zinc sulfate. The bath temperature is 45' C. and the bath travel 54 inches. The yarn is collected on a bobbin at 2520 inches per minute. After normal processing, the yarn is thrown to 3 turns per inch, at which time it has a denier of 260. The filaments of the yarn produced by the above procedure have thick portions along the length thereof. The thick portions are approximately inch in length with an intervening space between them of approximately 2 inches.

Example 11 A 7% cellulose, 4% caustic dull viscose is metered at the rate of 16 grams per. minute through a metering pump (No. l Zenith pump) and passed through a inch line to a modified pump (No. l Zenith pump). Each gear in this modified pump has a one tooth center tooth pocket with two teeth tapered on each side (diamond shaped). These pockets are made by cutting a 0.032 inch wide channel to the depth of one tooth on a inch radius with a Woodruif cutter. The gears are so positioned in the pump that the pockets of the drive and the driven gear come together and thus form an open valve directly through the pump, once for each revolution. This pump is rotated at 850 R. P. M. On leaving thi modified pump, the viscose passes through a 10 inch gooseneck and through a hole spinneret into a 6% sulfuric acid, 24% sodium sulfate, 0.7% zinc sulfate coagulating regenerating bath. The bath temperature is 45 C. and the bath travel 54 inches. The yarn is collected on a bobbin at 2520 inches per minute. .After normal processing, the yarn is thrown to 3 turns per inch, at which time it has a denier of 170. The filaments of the yarn so produced have thick portiors about if; inch in length at a frequency of about one every 3 inches along the length of said filaments.

Example III The pulsating flow of viscose from the modified pump of Example 11 is combined with a stream of viscose from an adjacent normally spinning position. The junction of the two streams of viscose, one a uniform flow and the other a pulsating fiow is made at the gooseneck just in front of the spinneret. An uneven denier yarn similar to that described in Exampl 11 is obtained.

It is to be understood, of course, that my invention is not limited to the exact details of construction, arrangement and operation described above for purposes of illustration, but is susceptible rather to many changes and modifications.

Thus, in the flow disrupting device, the pocket length may vary from one to all but a few of the teeth. The shape of the pocket ma also vary. It may be along one side of the gear or it may be through the center portion of the gear teeth. When the pocket is in the center of the gear teeth, it may be rectangular in shape, diamond shaped, triangular, or any other desired form. While various pocket sizes and designs are suitable, a preierred design consists of a center pocket in which parts of 4 teeth have been removed, said pocket being triangular as shown in Fig. 4. It is to be noted that in the preparation of all of these gears, a portion of each tooth is to be left intact so that there can be continuous meshing of the teeth during their revolutions. This allows an operation of continuous motion in contrast to an eccentric motion, which is more diflicult to handle mechanically.

In normal operation, metering pumps of this type do not run over 100 R. P. M. However, in order for the modified pump to give the short rapid pulsations of the spinning solution, it must be run at such a speed that the rate of delivery of the spinning solution therefrom varies at least 400 times per minute. Preferably, the rate of delivery should be varied as often as 1,000 or 1,500 times a minute and in some cases even more for the best results.

The apparatus of the present invention, which makes it possible to very rapidly vary the fiow of viscose to the spinneret, is unique and makes it possible for the first time to spin continuously yarns of uneven denier characterized by the fact that the thickened portions are sharp and abrupt rather than long and tapering. For the most part, the thickened portions are not more than 1% inches in length and are spaced from 1 to inches apart. The uneven denier yarn containin; these short thick portions gives novel effects when used in knitting and weaving operations. They may be used alone or combined with other yarns. It is further possible to regularly vary the shape and spacing of the thickened portions along the length 01' the filaments by using different size pockets on the same gear and by irregularly spacing the pockets on the gears.

I claim:

1. A gear pump comprising a. casing having fluid inlet and outlet ports and two intermeshing liquid-conveying gears disposed in said casing and positively driven to deliver a continuous stream of liquid, each of said gears having registering complete teeth and registering teeth partly cut away to form one or more pockets all of the complete teeth of one gear being in register with all of the complete teeth of the other gear whereby the gears operate to impart a pulsating flow to the stream of liquid.

2. In an apparatus for the production of artificial filaments comprising a spinneret, a filter, and a liquid pump for transferring artificial filamentforming material in a non-pulsating iiow through said filter and to said spinneret, the improvement which comprises a second liquid pump located between the filter and the spinneret, said pump comprising two intermeshing, liquid-conveying gears disposed in a casing provided with fluid inlet and outlet ports, said gears being positively driven to deliver a continuous stream of artificial filament-forming material directly to the spinneret, each of said gears having registering complete teeth and teeth partly cut away to form one or more pockets whereby the gears operate to pass a pulsating flow of the artificial filament-forming material to the spinneret.

3. In an apparatus for the production of artificial filaments comprising a spinneret, a filter, and a liquid pump for transferring artificial filamentforming materials in a non-pulsating fiow through said filter and to said spinneret, the improvement which comprises a second liquid pump located between the filter and the spinneret, said pump comprising two intermeshing, liquid-conveying gears disposed in a casing provided with fluid inlet and outlet ports, said gears being positively driven to deliver a continuous stream oi artificial filament-forming material directly to the spinneret, each of said gears having registering complete teeth and teeth having a side por tion cut away to form one or more side pockets, whereby the gears operate to pass a pulsating flow oi the artificial filament-forming material to the spinneret.

4. In an apparatus for the production of variable denier artificial filaments comprising a spinneret, a filter, and a liquid pump for transferring artificial filament-forming materials in a nonpulsating flow through said filter and to said spinneret, the improvement which comprises a second liquid pump located between the filter and the spinneret, said pump comprising two intermeshing, liquid-conveying gears disposed in a casing provided with fluid inlet and outlet ports, said gears being positively driven to deliver a continuous stream of artificial filament-forming material directly to the spinneret, each of said gears having registering complete teeth and teeth having the central portion cut away to form one or more central pockets, whereby the gears operate to pass a pulsating iiow of the artificial filamenttorming material to the spinneret.

ARCHIBAID STUART HUNTER.

CERTIFICATE OF CORRECTION.

Patent No. 2,59 ,973-

January 1, 19l 6.

ARCHIBALD STUART HUNTER It is hereby certified that error of the above numbered patent requiri.

0nd column, line 55, for "3/ inch" Letters Patent should be read with this correction therein that the same may conform to the record of the case 1 Signed and sealed this 9th day of April,

appears in the printed specification ng correction as follows:

read "5/14 inch-- Page 2, secand that the said n the Patent Office.

Leslie Frazer hind. r-mininner of Patents- It is to be understood, of course, that my invention is not limited to the exact details of construction, arrangement and operation described above for purposes of illustration, but is susceptible rather to many changes and modifications.