US3311687A - Process for manufacturing a monofilament - Google Patents

Description

March 28, 1967 F. SCRAGG ETAL 3,311,687

PROCESS FOR MANUFACTURING A MONOFILAMENT Original Filed Dec. 5, 1961 2 Sheets-Sheet 1 r/Ba.

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PROCESS FOR MANUFACTURING A MONOFILAMENT Original Filed Dec. 5, 1961 2 Sheets-Sheet 2 United States Patent series? Patented f /lat. 28, 1967 3,311,687 PR6ES FQR MANUFACTURENG A MGNOFILAMENT Frederick Scragg and Alexander Albert Chubb, both of Sunderland Street Worm, Macclesfield, England Original application Dec. 5, 1961, Ser. N ISZtlSQ, now Patent No. 3,243,339. Divided and this application Jan. 29, 1955, Ser. No. @3349 Claims priority, application Great Britain, Dec. 6, 1961' 41,955/60 4 Claims. (Ci. 264167) The present invention relates to synthetic yarns, particularly textile fibers of continuous, synthetic, filamentary form.

This application is a division of our copending application Ser. No. 157,080, filed December 5, 1961, and now US. Patent 3,243,339 and entitled, Yarn and Process and Apparatus for Manufacturing the Same.

As is well known, textile yarns can be produced synthetically by extruding a suitable filament-forming material from a solution or melt and solidifying the resulting filaments, which are usually later twisted lightly to form a yarn of continuous filaments. Such yarn has certain disadvantages as compared to yarn made from staple fibers, and various attempts have been made to overcome these disadvantages. Thus, for example, yarn made from staple fiber is twisted principally so as to hold the fibers together. As a result, the yarn which is produced in this way has relatively little elastic extension, so that it can be readily used for weaving. In addition, such yarn possesses bulk not only by virtue of the fact that all of the fibers are of slightly diiferent shapes and therefore repel one another by mechanical pressure, but also because the ends of the fibers often protrude from the yarn, thus giving it a soft, springy handle.

Various attempts have been made to modify the shape of the filaments of which a continuous filament yarn is composed in order to simulate these two properties. Thus, the bulk and soft handle have been simulated by imparting to each filament of an artificial continuous filament yarn a series of distortions of more or less random character so that the yarn itself becomes of large diameter and of soft handle. Such yarns, however, inevitably have a minimum elastic extension on the order of 10% and this extension limits not only the use of the yarns but the mechanical stresses to which they may be subjected during manufacture of cloth therefrom. Moreover, it has been found that with yarns of this character, since the filaments themselves are not broken but extend angularly to the axis of the yarn in a series of curls or loops, the resulting yarn is apt to catch on the fingers of handlers of the yarn thus initiating pulling.

While it has already been proposed to cut up continuous filament yarns, form them into sliver, and then spinthe sliver, this process is lengthy and expensive, and the resultant yarn is not always as satisfactory as that made from natural fibers owing to the smooth surface of the artificial filaments and the need for applying a high degree of twist in order to hold them firmly in the yarn.

It is accordingly a primary object of the present invention to provide a synthetic yarn which approaches the properties of a natural yarn to a greater degree than any hitherto known synthetic yarn.

It is a further object of the present invention to provide a process capable of producing such a synthetic yarn in a continuous manner.

Still another object of the present invention is to provide a process which is both simple and inexpensive and which at the same time is capable of producing a synthetic yarn which very closely approaches the properties of a natural yarn.

It is furthermore an object of the present invention to provide a process capable of producing continuously a plurality of synthetic monofilaments which will very closely approach the properties of natural yarns.

An additional object of the present invention is to provide a process capable of continuously producing synthetic yarns of the above type from any plastic materials so that the invention is not limited to the use of any particular material.

It is also an object of the present invention to provide a process which is not only simple and inexpensive but which also can be very easily operated without extensive delicate controls by relatively unskilled personnel so as to produce synthetic yarns which very closely approach the properties of natural yarns, as discussed above.

With these objects in view, the invention includes a monofilament which has an elongated continuous filament trunk and a plurality of filament branches distributed along the trunk, branching therefrom, and being formed integrally therewith, these branches having any desired preselected relationship with respect to the trunk of the monofilament. in accordance with the present invention the process for manufacturing the monofilament of the invention includes the step of continuously moving an endless mold surface which has formed therein an end less elongated cavity and a plurality of branch cavities branching therefrom so that upon introduction of a suitable plastic material into these cavities the monofilament of the invention may be molded. The plastic material, after it has at least partially set in the mold cavities, may be continuously withdrawn therefrom and cooling can take place either while the plastic material is still in the mold or immediately after the plastic material leaves the mold. An apparatus for producing the yarn of the invention includes at least one mold body having an exterior surface which is adapted to be continuously moved, which is endless, and which has formed therein the elongated endless cavity and the plurality of branch cavities extending therefrom, and the apparatus includes a means for introducing into these cavities a plastic material which at least partly sets in the cavities before being withdrawn therefrom.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatic side elevational view of one possible apparatus for producing a synthetic yarn according to the present invention;

FIG. 2 is a fragmentary developed view of the endless surface of a mold body according to the present invention;

FIG. 3 is a diagrammatic side elevation of another apparatus capable of producing synthetic yarn according to the present invention; and

4 is a diagrammatic sectional view of still another embodiment of an apparatus for producing the yarn of the invention.

Referring to FIG. 1, the machine illustrated therein includes a pair of rotary bodies 11 and 12 in the form of rollers of substantially cylindrical configuration supported for rotation about their axes, respectively, and driven from any suitable source of power and through any suitable transmission in such a way that the rollers 11 and 12 simultaneously turn at the same speed in opposite directions with the roller 12 turning in a clockwise direction and the roller 11 turning in a counterclockwise direction, as viewed in FIG. 1. In accordance with the present invention the endless exterior surface of at least one of a) these rollers is formed with an elongated endless cavity and a plurality of branch cavities branching from the endless cavity. This construction is illustrated in detail in FIG. 2 where the exterior surface of one of the rollers 11 and 12, the roller 12, for example, is shown in a fragmentary developed view. In the particular example illustrated one of the molds is formed by the elongated endless cavity 13a and the plurality of branch cavities 13 branching substantially laterally therefrom, as shown in FIG. 2. It will be noted that the branches 13 branch in a regular manner from the elongated endless cavity 13a. The roller is formed with an intermediate elongated endless cavity 14a having a plurality of branch cavities 14 branching therefrom, and while the branch cavities 14 are fairly regular they are distributed along the endless cavity 140: at irregular intervals. The exterior surface of the roller is also formed with a third elongated endless cavity 15a having the branch cavities 15 branching therefrom substantially laterally as indicated in P6. 2. It will be noted that with this arrangement the branch cavities 15 are more or less haphazard both in form and in distribution, so that the branch cavities and their distribution is irregular. It is to be understood that while three different types of mold cavities are illustrated in FIG. 2, any desired combinations of mold cavities may be provided on a moving endless surface. Thus, there may be 1, 2 or 3 mold cavities 13, 13a, 14-, 14a or 15, 15a, or any one or more of these types ofcavities may be included on a mold body which has a continuously moving surface formed with a cavity. It is only required that the continuously moving mold surface be formed with an endless elongated mold cavity and a plurality of branch cavities branching there from. The mold cavities may be formed in any suitable way such as by engraving, or by cutting with a suitable machine tool. In addition, the mold cavity may be formed by a photographic process in which the mold cavity is chemically etched. With this latter process the desired shape is originally drawn at a size many times greater than the final size of the mold cavity, and then the drawing is photographed onto the surface of the mold body and thereafter the chemical etching takes place, as is well known.

With the arrangement shown in FIG. 1, the mold cavity or the mold cavities may be formed either in the exterior endless surface of the roller 12 or in the exterior endless surface of the roller 11 or in both of these endless surfaces. Where this latter form is used, the mold cavity in one of the endless surfaces is a mirror image of the mold cavity in the other of the endless surfaces and of course the pair of rollers are moved in such a way that there is perfect synchronism between the rollers. Where only one of the rollers is formed with the mold cavity the other roller serves to close the mold.

In the example illustrated in FIG. 1 an extrusion press 16 is positioned so as to discharge an extrusion, which may be in strip form, directly into the nip between the rollers 11 and 12 which are driven at a speed having an appropriate relationship to the rate of extrusion. In accordance with the particular material which is being molded, either one or both of the rollers 11 and 12 may be heated. For example, either one or both of these rollers may have an electrical heating element embedded therein and connected through slip rings at the exterior of the rollers at a side surface thereof to slide contacts which are located in a suitable electrical circuit for energizing the heating elements and thus heating either one or both of the rollers 11 and 12. A suitable thermoplastic molding composition, in chip or powder form, for example, is fed into the extrusion press 16 from which a liquid or partially solidified extrusion passes between the rollers 11, 12 and is forced into the mold cavities to be molded therein. Where the extrusions are in strip form, the excess material will be squeezed from the surfaces of the rollers at those parts of the surface which are not formed with mold cavities and the excess material can simply drip from the rollers into a suitable container or may be withdrawn therefrom by a suitable suction pump or the like, for example. The one or more filaments which are continuously molded in this way are continuously withdrawn from the continuously moving mold surface or surfaces by any suitable take-up means 21 which winds the filaments or filament 29 into a suitable package. Thus, in the illustrated example three filaments 20 will be simultaneously withdrawn and wound into a package. A blower 17 provides cooling air which is blown through a suitable conduit in the space between a pair of bafiles 18 and 19 so that this cooling fluid engages the plastic material immediately when the material leaves the mold so as to accelerate the setting of the material which has already partially set in the mold itself, and thus the blower effects cooling and solidification of the filament or filaments as they are continuously wound up into packages by the take-up means 21.

In the embodiment which is illustrated in FIG. 3 the extrusion means 1d feeds the extrusion or extrusions into the nip between the roller 12 and a second mold body in the form of an endless belt 22 which is situated so as to have one of its runs engaging the exterior surface of the roller 12 along a substantial portion of the periphery thereof. In this case also either the exterior surface of the roller 12 or the endless surface of the belt 22 may be engraved or otherwise treated so as to have the mold cavities formed therein. It should be noted, in connection with the above-described embodiments, that instead of extruding strips of plastic material or a single relatively wide strip of plastic material, it is also possible to extrude into the mold cavity a substantially rod-shaped extrusion with one rod-shaped extrusion being introduced into each mold cavity and the material of the extrusion being just sufficient to fill the mold cavity while being pressed therein by the cooperation of the rollers. Of course, in the case of FIG. 3, any suitable drive means cooperates with the endless belt 22 so as to drive the same at a linear speed which is equal to the peripheral speed of the roller 12 with the lower run of the belt 22 advancing from left to right, as viewed in FIG. 3, in the case where the roller 12 rotates in a clockwise direction, as viewed in FIG. 3.

A further embodiment of an apparatus and of a process according to the present invention is illustrated in FIG. 4 where the rotary mold body 31 is in the form of a roller also formed in its exterior surface by any of the abovereferred to methods with an elongated endless mold cavity and a plurality of branch cavities branching therefrom, this arrangement being described above in connection with FIG. 2. With the embodiment of FIG. 4 the rotary mold body 31 is again driven to any suitable means and its exterior periphery dips into a bath 34 of molten plastic material which is picked up by the rotary mold body 31. A heating element 33 cooperates with the bath 34 to maintain the plastic material in a molten condition, and the properties of the plastic material are such that it will cling to the exterior surface of the roller 31 as the latter turns. A doctor 35 engages the exterior surface of the mold body to wipe therefrom all of the excess plastic material which is not located in the mold cavities, and one or more cooling nozzles 36 are provided for directing a stream of cooling air against the exterior surface of the mold body while the plastic material is still in the cavities thereof. A take-up means 37 is provided for continuously withdrawing the plastic filaments from the continuously rotating mold body 31 in the form of one or more packages. Instead of being cooled by streams of cooling fluid issuing from the one or more nozzles 36, it is possible to simply allow cooling to take place by the ambient air which is at room temperature.

An arrangement similar to that of FIG. 4 may be provided wherein instead of a bath 34, an endless belt is provided with a layer of the molten plastic material and the rotating mold body engages a run of this belt on which the layer of plastic is located so that the plastic material is delivered in this way to the mold body, and with such an arrangement because the belt presses against the exterior surface of the roller it is possible to eliminate the doctor.

The material injected between the mold members, in the embodiments of FIG. 1 or 3, may be extruded in the form of a thin continuous band which is pressed into the mold cavities, as described above, or if the material is soluble it can be injected in the form of a solution, and the solvent is later removed. The filament material may be injected under pressure in the form of a fine jet into the elongated endless cavity and the pressure exerted on the filament-forming material causes it to spread into the side branches of the cavity. In any case the filament material remains in the mold cavities until at least partial setting thereof. The cold air blast which cools the material produces at least partial solidification of the filament which is stripped oti the mold and wound onto a bobbin preferably with other filaments which are formed at the same time. In the case where the filament contains a solvent, this latter may be either rapidly evporated or the filament may be sprayed with a material which causes the solvent to deposit filament material from the solution.

In the embodiment shown in FIG. 4, any melt may be provided from all thermoplastic filament-forming or fiberforming plastics such as nylon, which is a polyamide; Dacron, which is a terephthalic acid-ethylene glycolpolyester (also known as Terylene); Vinyon which is a vinylchloride-vinylacetate polymer; Saran which is a vinylchloride-vinylidene chloride polymer; and the like thermoplastics. In the melting process to produce the bath shown in FIG. 4, the temperature which is used should be as close as possible to the melting point of the particular plastic, and is generally about to C. above the melting point. Thus, for example, in the case of nylon or Dacron, the temperature may be about 250 C., or higher.

Where the plastic is in a solvent, any thermoplastic filament-forming or fiber-forming material may be used, and also the apparatus and process shown in FIGS. 1-3 is applicable to all other synthetic fibers, such as viscose and the regenerated celluloses in general including also cellulose actetate. This process is also applicable to Orlon which is a polyacrylonitrile. Any suitable solvent for the plastic may be used, such as formic acid, cresol and phenol in the case of nylon, dimethylformamide in the case of Orlon, chloroform in the case of Vinyon, etc.

In the case of regenerated cellulose it is best to proceed as it comes from the manufacturer, i.e. extrude in the form of xanthate and to spray the extrusion with a precipitating solution, for example of 10% sulfuric acid and 20% sodium sulfate in water.

In the case of cellulose diacetate, the same is extruded in molten condition at a temperature somewhat greater than 250 C., the temperature may be as high at 500 F., using a heated grid at the throat of the press itself, just before the die. It may be cooled by means of air or rings which are water cooled. The diacetate is squeezed into the nozzle by means of a screw press in the form of powder.

The diacetate may also be used in the form of a very \hick solution in acetone, the solution then being dried by means of warm air at a temperature of about 134 F.

Cellulose triacetate may be extruded in molten condition at a temperature of 570580 F., or it may be extruded in the form of a solution thereof in methylene chloride in which case the solvent is evaporated by means of dry air at a temperature of 150 F.

Nylon may be treated in the same manner as cellulose diacet'ate, e.g. by squeezing the powder in through a screw press and melting at the throat of the press itself just before the die by means of a heated grid. The temperature may be about 250-285 C. depending on the nature of the material. The cooling may be accomplished by a water cooled ring or by an air blast.

Terylene or Dacron may be treated in the same manner as nylon using a temperature of about 480 F.

Acrylan and Orion may be treated in the form of a sticky solution thereof in dimethyl for-mamide which softens the Acrylan or Orlon and then dried by air at a temperature of about F.

Rhovyl which is polyvinyl chloride is used in the form of a solution thereof in acetone or by melting at a temperature of about 365 F.

Polypropylene is used by melting at a temperature somewhat greater than 330 F.

The particular temperature and/ or solvent may be determined for any particular plastic from the handbooks which are available or by simple pretreating. In general the temperature chosen should be controlled within rather close limits to avoid damage to the plastic.

The take-up means provided above in any of the embodiments of FIGS. 1, 3 or 4, will provide on the collecting bobbin the number of parallel synthetic filaments having projections of desired length formed along the length of the filaments. Inasmuch as nearly all synthetic filaments require drawings in order to improve their tenacity, a number of branched filaments sufficient to make a yarn of desired final denier is twisted together, the twisting being effected in such a manner that as many as possible of the side projections are twisted into the resultant yarn and are held firmly by the twist. The resultant twisted yarn is now drawn either hot or cold depending on the nature of the filament material, to an extent which will improve its tenacity, the side projections from the filament being drawn at the same time as the filaments themselves by cohesion of all of the parts of the twisted yarn. Subsequently, to drawing, the filaments are at least partially but preferably nearly wholly untwisted, or even reverse twisted, and the side projections may be shaken or brushed loose from the filament structure so as to project from the resultant yarn. Once the projections have been secured in this Way, the yarn may be twisted to a rather higher degree, if desired.

In accordance with the present invention the branches of each monofilament have a length which is at least as great as or at least twice as great as the average diameter of the trunk of the filament. In fact, the branches may be five times the length of the average trunk diameter and preferably are at least ten times the average trunk diameter.

Also in accordance with the present invention it is possible to extrude a continuous filament having a central cylindrical core or trunk which is simultaneously provided with a thinner radially extending web or fin on one side and an identical radially extending diametrically opposed web or fin. The filament which is obtained in this way is given a relatively high twist which is sufiicient to break the webs or fins from their edge inwardly toward the axis of the filament, and the resultant yarn will thus have a central non-extendable core surrounded by a series of thin fiufiy projections composed of broken webs or fins. Thereafter the filament may be drawn and doubled with others so as to make a yarn of desired denier.

The branched filaments which are produced in accordance with the present invention by a molding process as described above may be drawn and if desired twisted together so as to make multi-filament yarns.

It will be seen that with the monofilament of the invention the cross section of the trunk formed in the endless circumferential grooves of the rollers is in no way diminished by the branches which are made from material added to the trunk, so that in this Way the trunk of the monofilament of the invention is not weakened as would be the case if the material of the branches were derived from the body of the trunk. Moreover, it will be seen that while branch arrangements such as indicated for the branches 14 and 15 in FIG. 2 give the filament of the invention the appearance of haphazard branches both with respect to their size and distribution, in fact, since the monofilament of the invention is derived from a preformed mold the branches inevitably have a predetermined configuration and distribution according to a predetermined repeating pattern so that the appearance of haphazard branches extending from the trunk of the monofilament is purely a matter of appearance and the result of predetermined repeating patterns of the nature indicated in FIG. 2.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of yarns ditfering from the types described above.

While the invention has been illustrated and described as embodied in synthetic yarns, it is not intended to be limited to the details shown, since various modifications and structural changes may be made Without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range ot equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a process of manufacturing a filament from plastic material, the steps of continuously moving in a predetermined direction a body having an endless surface formed with cavity means composed of an endless elongated cavity which extends substantially in said predetermined direction and a plurality of branch cavities extending from said endless elongated cavity in substantially transversal direction thereto; continuously passing successive increments of said endless surface through a bath of molten thermoplastic material which adheres to said surface and fills said cavity means therein; continuously removing from said endless surface excess molten thermoplastic material which is located in said surface outside of said cavity means so as to form in said cavity means an endless elongated filament structure composed of an endless elongated filament having branches and consisting of molten thermoplastic material; continuously cooling said endless elongated filament structure of thermoplastic ma- 8 t'erial in said cavity means subsequent to removal of said excess molten thermoplastic material, so as to at least partly set the thermoplastic material of said filament structure; and continuously withdrawing said at least partly set endless elongated thermoplastic filament structure from said cavity means.

2. A process as defined in claim 1, wherein the step of continuously cooling said endless elongated thermoplastic filament structure in said cavity means comprises effecting relative movement of said filament structure and of a cooling fluid.

3. A process as defined in claim 2, wherein the step of continuously cooling said elongated plastic filament comprises directing a stream of cooling fluid against the filament structure in said cavity means.

4. A process as defined in claim 1 wherein the step of continuously removing excess thermoplastic material from said surface includes continuously returning such excess material to said bath of thermoplastic material.

References Cited by the Examiner UNITED STATES PATENTS 2,002,153 5/1935 Mendel 161177 XR 2,005,292 9/ 1936 Hiers 264-214 2,125,034 7/1938 Shepherd 264-214 2,743,511 5/1956 Genovese 161-177 2,786,233 3/1957 Merrill 18-10 2,825,624 3/1958 Fry 264-16-7 2,869,318 I/ 1959 Stucki 264-280 3,017,686 1/1962 Breen et a1 264-210 3,085,292 4/ 1963 Kinseth 264-175 XR 3,134,138 5/1964 Pu'fahl 264-167 3,142,147 7/ 1964 Betsch 161-177 XR 3,146,492 9/1964 Lemelson 18-10 3,161,708 12/1964 Scragg 264-177 FOREIGN PATENTS 13,518 10/ 1907 Great Britain.

206,366 9/ 1955 Australia. 1,246,923 10/ 1960 France.

927,052 5/ 1963 Great Britain.

ALEXANDER H. BRODMERKEL, Primary Examiner.

ALFRED L. LEAVITI', Examiner.

K. VERNON, F. S. WHISENHUNT, I. H. WOO,

Assistant Examiners.

Claims (1)

1. IN A PROCESS OF MANUFACTURING A FILAMENT FROM PLASTIC MATERIAL, THE STEPS OF CONTINUOUSLY MOVING IN A PREDETERMINED DIRECTION A BODY HAVING AN ENDLESS SURFACE FORMED WITH CAVITY MEANS COMPOSED OF AN ENDLESS ELONGATED CAVITY WHICH EXTENDS SUBSTANTIALLY IN SAID PREDETERMINED DIRECTION AND A PLURALITY OF BRANC CAVITIES EXTENDING FROM SAID ENDLESS ELONGATED CAVITY IN SUBSTANTIALLY TRANSVERSAL DIRECTION THERETO; CONTINUOUSLY PASSING SUCCESSIVE INCREMENTS OF SAID SURFACE THROUGH A BATH OF MOLTEN THERMOPLASTIC MATERIAL WHICH ADHERES TO SAID SURFACE AND FILLS SAID CAVITY MEANS THEREIN; CONTINUOUSLY REMOVING FROM SAID ENDLESS SURFACE EXCESS MOLTEN THERMOPLASTIC MATERIAL WHICH IS LOCATED IN SAID SURFACE OUTSIDE OF SAID CAVITY MEANS SO AS TO FROM IN SAID CAVITY MEANS AN ENDLESS ELONGATED FILAMENT STRUCTURE COMPOSED OF AN ENDLESS ELONGATED FILAMENT HAVING BRANCHES AND CONSISTING OF MOLTEN THERMOPLASTIC MATERIAL; CONTINUOUSLY COOLING SAID ENDLESS ELONGATED FILAMENT STRUCTURE OF THERMOPLASTIC MATERIAL IN SAID CAVITY MEANS SUBSEQUENT TO REMOVAL OF SAID EXCESS MOLTEN THERMOPLASTIC MATERIAL, SO AS TO AT LEAST PARTLY SET THE THERMOPLASTIC MATERIAL OF SAID FILAMENT STRUCTURE; AND CONTINUOUSLY WITHDRAWING SAID AT LEAST PARTLY SET ENDLESS ELONGATED THERMOPLASTIC FILAMENT STRUCTURE FROM SAID CAVITY MEANS.

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