US 3214899 A
Description (OCR text may contain errors)
Nov. 2, 1965 J- M. WININGER, JR., ETAL CORDAGE PRODUCT Filed Feb. 12. 1965 F/GI 2 JOHN M. W/N/NGE'R,JR RICHARD F DYER INVENTORS ATTORNEYS United States Patent 3,214,899 CORDAGE PRODUCT John M. Wininger, Jr., and Richard F. Dyer, both of Kingsport, Tenn, assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Feb. 12, 1965, Ser. No. 432,178 6 Claims. (Cl. 57140) This application is a continuation-in-part of our application Serial No. 257,386, filed February 11, 1963, and now abandoned.
This invention relates to a new twine cordage product. More particularly this invention concerns a new material referred to as a twine cordage product for tying purposes.
In the industry as well known there are a number of products presently produced from jute, hemp, sisal and cotton and the like material of vegetable origin. These products range from rug backings and bags to simple twine or string used for tying packages. As also known such products because of their vegetable nature are susceptible to attack by bugs, mildew and other destructive forces. With the advent of various polymeric compositions which are resistant and inert it can be seen that making such type textile products from polymeric compositions would have some advantages.
Hence, work has been expanded in spinning various resistant polymeric compositions through spinnerettes to obtain polymeric filaments. Such spinnerette spun filaments, except for high expense of manufacture, are usually resistant, excellent symmetrical filaments. However, the expense and symmetry works against the use of such filaments for the above referred cordage type purposes. That is, polymeric filaments may be prone to be slippery and hence do not strongly adhere even when substantial twist is imparted to the materials such as making the materials into twine or heavy denier yarn for rug backings. It has been proposed to incorporate roughening agents into such fibers from such polymeric compositions and this may have advantages under some circumstances. On the other hand such additives further increase the cost of the symmetrical filaments and may cause abrasive action on equipment dispensing such roughened cordage.
It is therefore apparent that the development of a simplified convenient process and apparatus for the production of textile material which can be used for the aforesaid cordage type purposes represents a highly desirable result. After extended investigation we have found what is believed to be a materially different procedure for making textile products of the class indicated. This procedure is not only relatively simple, fast and less expensive than spinnerette spinning but permits the production of products not only of a coarseness suitable for cordage uses as aforementioned but also of a process, if desired, providing new products and fields of usage.
in further detail the stiffness and large denier size of polypropylene monofilament cause it to be too still? for many end uses. A fine denier per filament multifilament polymeric yarn material would be much more desirable in many fabrics and in many cordage end uses such as fish lines and fish nets. The cost of producing a fine denier per filament multifilament, continuous filament or staple polymeric yarn, however, is quite high due to the slow production rates and the expensive equipment such as spinnerette and spinning machines which are required to process the polymer into a yarn. Two types of multifilament yarn are common in the industry. The first of these is composed of continuous filaments. The second is composed of staple fibres. Traditionally, continuous filament yarn is considerably more expensive but is stronger than yarn which has been spun from chopped-up filaments or staple fibers. Staple fibers yarns while somewhat less costly are weaker in strength' It is highly de- 3,214,899 Patented Nov. 2, 1965 "ice sirable, therefore, that a method of converting polymer into high-strength flexible fiat, partially fractured, substantially continuous polymeric ribbons be devised which would utilize the low cost extrusion equipment of the film extruding industries and still retain the flexibility and hand of continuous filament yarns or staple yarns traditional in the textile trade.
In its broader aspects this invention utilizes a method of converting film into textile cordage by subjecting the film to the fracturing or slitting action of a gaseous media. By varying the conditions of the fluid treatment of the film, textile cordage may be made which vary in appearance from that of a continuous filament cordage containing few or no broken filaments or loose filament ends to a staple-like cordage containing a large number of broken filament ends. It has also been found that by varying our novel method of treatment and the treating apparatus that the hand or feel of the cordage can be made rough or fine depending on the degree of breaking up the film into fractured ribbons and the resultant size of the fractured ribbons composing the cordage. While it is known in the prior art, to extrude a film, slit it into a narrow width, orient it and then beat it with a brush or by similar mechanical treatments, these treatments of the prior art were difficult to control and made it impossible to obtain the cord-age possible by the instant invention.
One object of this invention is to disclose means which are economical and versatile for converting polymeric materials into cordage exemplified by baler twine. Another object is to provide a process involving extruding a film, orienting it highly in a longitudinal direction, and subjecting it to the action of a high velocity 'fiuid medium, and thereby forming the film into flat, partially fractured or slit, substantially continuous polymeric ribbons. A further object of this invention is to disclose a process of producing a new cordage which has additional and inherent fractuability which provides a more secure knot with less tendency to slip. A further object is to disclose a process of converting a film into cordage wherein the denier and circumference of the twine is substantially uniform along the length of the twine. A further object of this inveniton is to disclose apparatus for economically converting film into the foregoing cordage product. Other objectives will be apparent from the description of the invention which follows;
For assistance in the understanding of this invention reference is made to the attached drawings forming a part of this application. In these drawings FIGURE 1 is a schematic side elevation view of one system for drafting, heat setting and disintegrating the preliminarily oriented film product into fiat partially fractured ribbons of the present invention.
FIGURE 2 is a schematic side elevation view in which some of the parts have been shown in perspective for illustrating an arrangement of apparatus parts whereby the drafted slit film may be fractured and twisted into the new cordage textile of the present invention.
FIGURE 3 is a cross-sectional view on a gravity enlarged sacle indicating the general nature of that which a photomicrograph of the cross-section of our new cordage displays as to fractured ribbons making up the cordage.
FIGURE 4 is a view likewise on a greatly enlarged scale depicting a longitudinal section of the cordage of the present invention as would be observed from certain photomicrograph pictures thereof.
The nature and contents of the various parts making up the assemblies illustrated in the drawings are now described more completely as follows:
Referring to FIGURE 1, 1 represents the supply of film or sheeting to be processed in the present invention.
This supply 1 may comprise a conventional roll or drum of the film or may be film supplied directly from an extruder or other similarly convenient rotatable supply source.
The supply source is in series with one or more canted rolls designated 2 about which the film may be wrapped one or more times before passing into drafting over 3. This oven 3 may be of any of the usual constructions employed in the film or yarn manufacturing industry. It can be heated electrically or with hot air or any other convenient and controllable source of heat. Since the temperature of operation of these ovens will be referred to in more detail hereinafter, extended description at this point appears unnecessary.
The film discharging from oven 3 is wrapped around canted rolls 4 for feeding into oven 5. These canted rolls 4 may be the same as rolls 2 or rolls 6 to be referred to shortly. Likewise oven 5 may be of the same general construction as oven 3 but in this particular embodiment of FIGURE 1 oven 5 is employed for heat setting as will be explained in more detail hereinafter.
Oven 5 discharges onto and around canted rolls 6 which feed into a rather large jet. This large jet 7 dis charges to a smaller jet 8 the construction of which may likewise be the same as jet 7, differing primarily only in being of smaller size.
The fiat fractured ribbon from the jet 8 is picked up between the hips between the pair of pressure rolls 9, passes through a conventional traverse guide 10 onto roll 11 or other desired packaging device or other utilization.
In FIGURE 2 is shown a convenient form of apparatus which may be used to process a drafted film supply package preformed in an area separate from the film or sheeting manufacturing and drafting. That is in some instances it may not be convenient or desired to proceed with the continuous-in-line operation exemplified by the apparatus set up in FIGURE 1, hence apparatus arrangement as set forth in FIGURE 2 may be advantageously used. In FIGURE 2 a supply package is indicated at 52. This package may be one containing a ribbon or strip of film which has been drafted and otherwise processed on separate equipment as already described in connection with preceding figures. The film supply is passed through a suitable guide member to input feed rolls 53 which feed the film ribbon into jet 54. Rolls 53 are ones which may be suitably controlled to give the desired rate of feeding of the film into the jet.
In jet 54 the oriented film is acted upon by a high velocity fluid. This action causes the oriented film ribbon to fracture longitudinally but not laterally into a plurality of flat fractured ribbons.
The fractured ribbons emerge from the jet as 55 and are taken up on a conventional twister 56. By the twister it is possible to impart the desired degree of twist to the fiat filaments as in the twisting of conventional textile filaments.
In its broader aspects the process of this invention may be divided into :a number of suboperations as follows: film extrusion, slitting, orienting the film, forming the flat fractured ribbon in a fluid jet, and twisting the flat fractured ribbons into a cordage. The separate steps in the operation may be carried out in one continuous process or in various combinations of subprocessing steps. For example, the film may be extruded in one operation. In the second operation, it may be oriented. The third operation would then consist of fractured ribbon forming and twisting into a cordage. A second approach would be to extrude and wind the film full width. The full width roll of film would then be used as a supply for the orienting operation, in which case it would be slit into the desired widths and a plurality of narrow widths of film would be fed through the drafting process. These drafted ends of film might then be Wound up on individual packages. These packages would then be transferred to a third operation wherein the individual polymeric ribbons would be passed through fluid jets and twisted into cordage. In other cases, the extrusion, drafting and partially fractured ribbon formation may be carried out in one continuous operation and the twist inserted in the cordage in the same or in a subsequent operation.
While a substantial understanding of our invention is already apparent from the foregoing general description of the overall apparatus and process, a still further understanding will be had for a consideration of the following example which we set forth to illustrate a preferred embodiment of our operation.
EXAMPLE I With reference to FIGURE 1, a 37 wide roll of 5 mil thick polypropylene film was extruded and slit into 1" widths and wound on spools. A spool of this slit film 1 served as the supply for the operation of FIGURE 1. The film was withdrawn from the supply spool by canted roll pair 2 and fed into a hot air drafting oven 3 at a speed of 33% feet per minute. The temperature of the draft oven was 340 F. The film was withdrawn from the draft oven 3 by roll pair 4 at a speed of 400 feet per minute for a draft ratio of approximately 12: 1.
The jet was supplied with air at 60 pounds per square inch gauge pressure. The air was at approximately room temperature. The action of the high velocity, high pressure air on the film caused it to split into a fiat, partially fractured, substantially continuous ribbon which were removed from the jet by pinch rolls 9 at a speed slightly less than 4.00 feet per minute. The flat fractured ribbons were then wound up 'on a spool by means of traverse guide 10 and winder 11. Seven yarn ends of these fiat fractured ribbons were then twisted together at one turn per inchinto a baler twine of approximately 14,000 denier. This baler twine was set on the twister bobbin for seven minutes at C. to reduce its kinkiness. The strength of this twine was 124 pounds or 4 g./d. break and 87 pounds or 2.7 g./d. twine knot break. In a second test, ten ends of the flat filaments were combined with one turn of twist to make a twine of about 20,000 denier and a breaking strength of the twine of 177 pounds or 4 g./d. was obtained. The baler twine knot break strength was 121 pounds or 2.7 g./d. and such knots would not slip or pull out of the tied strand with the beneficial result of this relatively high knot strength.
By comparison a twine made up of 40 continuous roughened monofilaments of 690 denier per filament size twisted together to produce a twine of 27,600 total denier had a plain tensile strength of only 212 pounds or 3.5 grams per denier and a baler knot load bearing capacity or strength of only 77 pounds or 1.24 grams per denier at which point the knot slipped out to fail and drop the load. Thus the fractured film twine of this invention having at least the 3.5 g./d. strength or better and 2.0 g./d. baler knot strength or better represents a substantial improvement over the monofilament twines of the prior art.
EXAMPLE II A sample of 5 mil x 11 inch wide polypropylene film was processed, as in Example 1, into a jet supplied With air at 20 to 30 p.s.i. gauge pressure. This jet is the same as described in Dyer U.S. Patent 2,924,868. The fractured ribbons formed by this treatment and prior to twisting into twine had the following unique properties:
Fractured ribbonsl00 Width of drawn film-5" Average thickness of fractured ribbons.001" Mean denier per ribb0n25,000/100=250 Mean width of fractured ribbon5/100=.05" Mean width to thickness ratio-.05/.0O1 =50 to 1 This twine had a tensile strength of 193 pounds or 3.6 grams per denier and 7.3 percent elongation and a baler knot strength of 133 pounds or 2.4 grams per denier and an elongation of only 14.6 percent at rupture. The flat,
rectangular cross-section, partially fractured ribbons were twisted to produce a baler twine which was suitable for use on commercial hay baling machinery. FIGURE 3 is a cross-sectional drawing of the fractured twine after twisting. The thickness has been exaggerated to show the generally rectangular shape of the cross-section.
A number of fiat fractured ribbons, prepared in accordance with this example, had inherent properties as set forth in Table 1.
ends to other fractured ribbons is large and the number which are broken and not connected at their ends is small.
In some cases it is not necessary to twist the flat fractured ribbons as a part of the process. For example, if the flat fractured ribbons are to be used subsequently in preparing heavy cordage with several ends of the ribbons plied together there may be no need to twist the ribbons prior to the plying operation in making up a cord.
While the foregoing examples have related to poly- The high knot strength of the baler twine of the present invention is due to the aforesaid additional fracturing capability in the baler twine within the range of percent to 5-0 percent.
These twines were evaluated as a substituted for sisal baler twine on an International Harvester hay baler. The evaluation indicated that the textile cordage of the present example would perform acceptably on this type of agricultural equipment.
EXAMPLE III Using filrn processed in the same manner as in Examples I and II, a quantity of baling twine was prepared which is more uniform than sisal or henequen. A Uster denier uniformity test gave a range of variation in denier of the twine of minus 10 percent below size to plus 11 percent above size which can be compared with minus to percent below size to .plus to percent above size for a good grade, domestic sisal baler twine.
The percent coefficient of denier variation of the sisal twine was 13.5 percent as compared to 4.5 percent for the fractured film twine of Example III.
This polymeric twine when untwisted will not come apart as in cordage made from staple fibers. The fractured ribbons remain connected even after untwisting and therefore retain a great portion of their tensile strength. Sisal, being a staple fiber, produces twine of no strength when untwisted.
This can be readily shown by suspending a weight of 10 to pounds by a twine of the fractured twisted twine of this invention. It is observed that although the twist works out under the influence of the weight the twine does not fail. By contrast a natural twine such as sisal will untwist and the discontinuous staple fibers making up the twine will separate to slip past each other resulting in failure of the twine and the weight will drop to the floor. In the past it has been necessary to twist two or more small sisal strands together with a ply twist opposite in the direction of the individual strand twist. Thus the twine of the present invention has substantial economic advantage in that the added cost of producing several small twines and the subsequent plying and twisting into a final twine is eliminated. At the same time the excess knot slippage of prior art continuous multifilament twines is avoided in the fractured film twine of this invention.
When film which has been disintegrated is spread out before twisting, a visual examination reveals numbers of long flat fractured ribbons which are connected at their ends to other fractured ribbons. This is shown in FIG- URE 4. When the fluid pressure is relatively low, the number of fractured ribbons which are connected at their propylene film which contained only in an antioxidant as an additive, it will be recognized that UV inhibitors, gas fading inhibitors, and other materials may be added to the polymer prior to extrusion to give the desired final properties. For example, pigment may be added to the film in suitable amounts and colors to produce a solution dyed fiat fractured ribbon if desired.
From the foregoing three examples, it will be apparent that polyallorner, polyethylene, or polyester could be bended with polypropylene or with each other by feeding the two different films through the iet in the desired proportions or by blending two or more polymers before extrusion.
From the foregoing description and examples it will be apparent that the flat fractured ribbons of this process may be treated and handled or used by any of those techniques which are known in the textile trade for converting yarns or fibers into cordage. Flat fractured ribbon yarn has the unique property of resulting in a baler twine which is substantially uniform in strength, denier, circumference and friction along the length of the twine.
The highest degree of orientation preferred above is in direct relation to the orientation temperature, the oven hold-up time, and the width and thickness of the unori ented film. The range from 3:1 to 15:1 is considered to contain the preferred drafting ratios for polypropylene film as used above.
When less than the maximum drafting ratio is used, all other conditions remaining constant, it becomes apparent that the degree of fracture and separation effected in the fluid jet is reduced, and the resulting flat fractured ribbons are thicker and wider.
The take-up rate or production speed is not seen limited to any particular value. The hold-up time is directly proportional to the take-up rate; but for any given rate, the length and temperature of the oven can be designed to produce the necessary film temperature. In the various examples, take-up rates ranging from 300 ft./min. to 600 ft./min. were successfully used without indication of reaching a limit in either direction. The upper limits in production would be determined by the maximum speed at which the equipment operators could handle the materials in hook-up and doffing operations.
The air or steam pressures used in the fluid jet are in many instances also in direct relation to the thickness of the film. An unoriented 5 mil film may :be drafted and processed into flat fractured ribbons with a psi. jet pressure, but the jet pressure used in this instance will be higher than for an unoriented l mil film, assuming the same degree of fracture is effected in both thicknesses. The pressure ranges used in various runs have varied from to 90 p.s.i. with maximum unoriented film thicknesses of 5 mils. It is possible that higher jet pressures would be desirable for even thicker films (6-10 mils) to produce the desired amounts of fracture. The fiat ribbons have a mean width to thickness ratio of at least 30 to 1 and a mean denier per ribbon of more than 50 and less than 500.
Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.
1. As a new twine cordage product for tying purposes exemplified by baler twine comprised of a bundle of flat partially fractured, substantially continuous polymeric ribbons twisted together, said twine being characterized in that it has a tensile strength of at least 3.5 g./d. and a knot strength of at least 2.0 g./d., that the knots resist slippage and the twine is capable of providing approximately the same volume as comparable conventional twine from vegetable fiber composition, the twine being further characterized in that the fiat ribbons in the twine are twisted prior to their being knotted and the twine possesses additional and inherent fracturability within the range of 15 percent to 50 percent whereby upon the twine being knotted at least a part of said additional fracturability is brought into operation thereby providing a more secure knot with less tendency to slip.
2. The twine product of claim 1 wherein the denier by the Uster test method of the twine is substantially uniform along the length of the twine and does not vary more than a minus 10 percent to a plus 11 percent along said length.
3. The twine product of claim 1 wherein the twine may be untwisted without coming fully apart.
4. The twine product of claim 1 wherein the twine is essentially comprised of polypropylene.
5. As a new article of manufacture a polymer twine capable of being tied into a relatively strong non-slipping knot, essentially comprised of a plurality of thin fiat partially fractured substantially continuous ribbons of polymeric composition twisted together in twine form, the twine being particularly characterized in that the ribbons possess residual fracturability whereby upon knotting the twine said residual fracturability may come into effect thereby producing said non-slipping knot.
6. The twine of claim 5 wherein the ribbons making up the twine are of a flat rectangular cross-section with a mean width to thickness ratio of at least to 1 and a mean denier per ribbon of more than and less than 500.
References Cited by the Examiner UNITED STATES PATENTS 2,856,750 10/58 Lewis. 2,908,669 1 0/59 Hagemeyer. 3,015,150 1/62 Fior 57140 3,081,519 3/63 Blades et al. 57-140 3,112,160 11/63 Rush. 3,137,990 6/64 Carranza 57-140 FOREIGN PATENTS 813,891 5/59 Great Britain. 864,695 4/61 Great Britain.
MERVIN STEIN, Primary Examiner.