US3164947A

US3164947A - Cordage and methods of manufacture thereof

Info

Publication number: US3164947A
Application number: US261658A
Authority: US
Inventors: Dexter W Gaston
Original assignee: Wall Rope Works Inc
Current assignee: Wall Rope Works Inc
Priority date: 1963-02-28
Filing date: 1963-02-28
Publication date: 1965-01-12
Anticipated expiration: 1982-01-12

Description

Jan. 12,1965 D. w, GASTON 3,164,947

CORDAGE AND METHODS OF MANUFACTURE THEREOF Filed Feb. 28, 1963 Q v SUPPLY 2 Ir l2 l4 ,ne gx'rnunca 6 rw ER DIE Q J' G 1 l ORIENTATION TWISTER ZONE 8 I FIG. I.

OUENOH 3,164,947 CORDAGE AND METHODS OF MANUFACTURE THEREOF Dexter W. Gaston, Delanco, N.J., assignor to Wall Rope Works, Inc., Beverly, N.J., a corporation of New ,Jersey Filed Feb. 28, 1963, Ser. No. 261,658

- 24 Claims. (CI. 57-14) This invention relates to cordage and methods of manufacture thereof and has particular reference to the manufacture of rope or other cordage from extruded plastics:

As will appear, the invention basically relates to yarn formation, and yarns provided in accordance therewith may be associated in various ways for the formation .of cordage. For consistency of description, primary reference will be made to the formation of twisted rope as the end product.

But it will become evident that the yarns vproduced j in :accordance with the ,invention are the like, and it will therefore be understood that the invention is not limited to twisted rope.

The conventional practice in the formation of twisted ropes from synthetic plastic material involves the drawing of filaments, the twisting of the filaments into yarns,

commonly referred to as threads or singles yarns, the twisting of these yarns to form what are known as plied yarns, ply yarns, or, simply plies, the formation of these plied yarns into strands, generally involving the formation of concentric twisted layers of the plied yarn, and

' finally the laying, with twisting, of the strands into rope.

The ropes, in turn, may be laid together to form cables.

Variants of the foregoing are made involving, for example, the twisting of plied yarns into cords which are in turn formed into strands; or yarns may be plaitedto form strands; or plaited yarns may be formed into cords,

In accordance with theinvention disclosed and claimed in Stratford application, Serial No. 261,659 filed February 28, 1963, ribbons, using this term in a broad sense as will hereafter appear, are extruded, the ribbons taking the form offilaments of different or similar shapes which are continuously or intermittently interconnected by reduced thickness bridges. Through the formation and use of these ribbons numerous advantages are obtained which may be briefly referred to as follows:

The sensitivity of the extrusion process is greatly reduced due to the fact'that the. cross-sectional areas of the extrusion openings in the dies are greatly enlarged avoiding difficulties of clogging and the like. "Another aspect of reduction of sensitivity of the extrusion process is involved in the possibility of drawing contaminated, substandard or reprocessed materials at draw ratios as great as l2to 1 in spite of the presence of foreign particles creating points of stress concentration, the foregoing being due to the large deniers of the ribbons.

Plying operations are'eliminated together with the overtwist involvedin making yarn, thereby greatly reducing the throwing costs. In fact, the ribbons may be put directly into the strands of a rope, cable, braid or plait, totally eliminating yarn and ply making operations.

atefit equally applicable to braided or plaited rope, cable or" "ice Universal winding of the ribbons may immediatt follow the extrusion operation. The improvement packaging thus achieved permits the maintenance of ventory between extrusion and yarn making.

The formed ribbons maybe fully locking or 861 locking and have advantageous winding characteristics contrasted with filaments of circular cross-sections.

The use of ribbons in accordance with the inventi reduces yarn or strand twist, or both, depending on r bon shape and the final desired rope. The advantage reduction of twist will be evident when it is consider that for a given load applied to a final product, the to the existence of twist increases the lengthwise stress the filaments as an increasing function of the amount twist. Theoretically, for the attainment of maxim! strength filaments should be extending in the direction the applied force, i.e., they should be untwisted a should lie parallel to each other; but twist is necessz from a practical standpoint to form a compact structl which will withstand wear and prevent separation of 1 individual filaments which would cause them to be dividually broken in use, permit snagging, and pen them to twist on themselves with resultant breakage. accordance with the present invention, the amount twist may be greatly reduced, thus providing a better proach to the theoretically desirable condition of fi ments in respect to the direction of applied load.

Because of the formation of ribbons as hereafter mi fully described, they exert wedge-like action in strai preventing relative movement and giving rise to 11 resistance to hockling.

The reduced thickness bridges of the ribbons prov excellent reservoirs to hold lubricants permitting relat movements of the components of the structure.

Because of the large deniers involved, yarns or stral may be twisted directly from the ribbons as they p from the extruding devices, this being because of the l twist involved.

The foregoing advantages are involved in said St: ford application and matters pertaining thereto claimed in said application. The present invention lates to further improvements over the prior art wh may be summarized as follows:

, Because of the large deniers of ribbons which may used, lubricants and other materials maybe incorpora in the plastic as extruded. Internal lubrication parti larly may be thus achieved as is highly desirable in vi of the fact that in use the elements of a rope must nec sarily move relatively to each other and adequate ext nal lubrication has obvious disadvantages.

Fillers may also be incorporated in the plastic in: rial to provide special properties such as lubrication avoid sticking on bitts, etc., achievement of desired grez or less density, securing of luminous or reflecting pr erties, fire resistance, and others. The use of mi: resins is also made possible.

The general objects of the invention are concert with the attainment of the foregoing and other adv tageous results, and these objects and others will beco more fully apparent from consideration of the follow description, read in conjunction with the accompany drawing, in which:

FIGURE 1 is a diagram illustrative of the extrud and associated operations which may be involved accordance with the invention;

FIGURE 2 is a face view of a portion of a typi extrusion die;

FIGURE 3 is a pcrspectve view showing the form a ribbon produced .by the type of die shown in FIGURE FIGURE 4 is an elevation showing the helicoidal fo taken bytheribbon of FIGURE 3 when partially twist a single ribbon being shown for illustration though,

ll appear, in general a plurality of ribbons will be isted together; FIGURE is a cross-section of a yarn provided by a twisting of four ribbons of the type shown in FIG- lE 3; FIGURE 6 is a diagrammatic section of an alternative e of yarn provided by the association of four ribbons ving special interlocking characteristics; FIGURE 7 is a fragmentary view showing an altertive form of die in which a ribbon of curved cross- :tion is formed; I FIGURE 8 is a diagrammatic view of an alternative m of die which may be used in accordance with the 'ention for the formation of a ribbon; FIGURE 9 is a view similar to FIGURE 8 but showanother form of die; FIGURE 10 is a fragmentary elevation of a strand )vided in accordance with the invention for the forttion of a rope; and FIGURE 11 is a transverse section of a rope formed Im strands of the type illustrated in FIGURE 9. The invention is generally applicable to the formation cordage from a great variety of extrudable materials .ich may be handled, so far as extrusion is concerned, accordance with the individual known procedures appliale to them. Such extrudable materials are poly- )pylenes, polyethylenes, polyamides, polyesters, polytyl chlorides, polyvinylidene chlorides, polyurethanes, lyallomers, polycarbonates, acetyl resins, Teflon, or lers. Any of these, including the'various forms thereof, mixtures thereof may be supplied in conventional ahion through a supply conduit 2 of a conventional truder 4 which delivers them to a die indicated at 6. :nerally speaking, such an extruder includes heating :ans and an advancingrscrew to provide the plastic to die in molten condition. Various materials may be :orporated in the plastic for special purposes. Graphite, Jestos, or the like may be incorporated for lubrication rposes; if it is desired to provide a heavy rope which ll sink in water, a weighting material such as barium lphate or barium stannate may be incorporated, these to acting as lubricants. Modifying agents such as crossking material may also be incorporated to secure sired physical properties of the rope. The invention, wever, is not concerned with the chemical aspects of extruded plastic, though it is concerned with added lterials which will be discussed more fully hereafter, d it will be understood that, in general, any extrudable mposition may be used which will produce satisfactory pc or other cordage for its intended purposes by reason tensile and other properties. Following the extrusion from the'die 6, the plastic iterial is subjected to other conventional process. For ample, the extruded ribbon or ribbons indicated at 7 ss with desired drawing while in molten or soft conion (which reduces cross-sectionlinto a quench bath wherein the molten or semi-molten plastic is cooled effect solidification. While a gap is illustrated beeen the die and the surface of the liquid (usually iter or oil) in the quench tank, it'may be desirable in a case of various plastics to extrude directly into the enching liquid. From the quench tank the ribbon or ibons, now solidified, pass through relatively slowly erating draw-off rollers 10 and thence through an ientation zone 12 and through faster operating rollers The orientation zone is generally a heating zone lolving infra-red, dielectric, microwave or induction ating or passage through an oil or similar heated bath. 1e bath may provide an external lubricant for the prodt. During this passage elongation is produced, suitle for the particular plastic in accordance with known ocedures, by reason of the differential speed of the llers at 10 and 14. As is known, this procedure ineases the ultimate tensile strength of plastics of the re here involved. Following the rollers 14, the ribbon ribbons pass to winding mechanism indicated at 16.

In view of the fact that ribbons are produced, the winder may be of universal type to provide packages which may be stored as inventory.

Instead of a winder at 16, however, a twisting device may be provided for twisting a plurality of ribbons together to form a yarn or strand which may, in turn, be wound by universal winding to provide packaging. It may be noted however that in contrast with a procedure involving the winding of filaments on beams, twisting of the ribbons into yarns or strands may be directly effected as just indicated. This is made practical by the fact that whilethe ribbons emerge from the rollers 14 at a high linear rate, the twisting necessary to form yarns or strands is relatively small so that the twisting devices can be operated at practical speeds. Twisting of the usual monofilaments at this point is not practical because their linear speed of emergence is so high that the twisting devices, to secure the high amount of twist necessary would be obliged to operate at extreme and .impractical speeds, or, alternatively, would require slowing down of the extrusion process.

Reference may now be made to FIGURE 2 which indicates at 18 the die plate of the die 6. As will be evident, this may contain a large number of openings to produce a number of ribbons corresponding thereto; but since these openings are duplicates of each other, only one opening 20 in the die plate is illustrated in FIGURE 2. This opening, as shown, comprises what are essentially circular openings 22 joined by connecting slots 24. For convenience of reference, the portions of the plastic coming from the circular portions of the openings 22 (or other enlargements as described hereafter) will be referred to as filaments, while those portions extruded from the connecting slots 24 will be referred to as bridges. The number of filament-forming openings 22 may be of any desired number, and it has been found convenient to use arrangements producing in a ribbon 4 to 11 or more filaments. The diameters of the circular openings 22 may, practically, range from about 0.010 inch to 0.050 inch, more or less. Draw ratios in the orientation zone which are practical may be around 9 to 1, meaning that the final cross-sectional area of the formed ribbon is correspondingly reduced from that approaching rollers 10, this being substantially less than the cross-section of the die opening. The draw ratio may, however, be as great as 12 or more, depending on the material. While the dimensions of the individual filament openings are not large, the complete cross-sectional area of the opening 20 is large, and consequently stoppage of flow and necessity of cleaning are much reduced. Even the constricted portions of the opening at 24 are effectively maintained clear by the abutting fiow through the larger portion of the opening.

A portion of the ribbon formed by the use of the described die is illustrated in FIGURE 3 at 26. The cross-section 28 is geometrically similar to the die opening, but reduced in dimensions in view of the draw effected between the die and the first roller in the quench bath (so that the cross-section of the ribbon as it solidifies may be considerably less than the cross-section of the opening in the die) and in view of the draw effected in the orientation zone 12 by the differential speed of the rollers 10"and 14. The filaments are indicated at 3 0 and the bridges at 31.

At this point consideration may be given to the significance of the ribbon. If individual filaments were drawn in accordance with conventional practice, a group of them would not be usable without their association or compacting into a singles yarn by twisting, the twisting being essential to hold them together to avoid snagging,

disassociation, or individual breakage. Furthermore, a high twist of monofilaments would be required for this purpose. In the casc of the ribbon 26, however, they are associated, tindziintegrally so. as a group, and twisting of this group as such is unnecessary. A plurality of ribbons may, therefore,be twisted together to form what is the equivalent of a plied yarn. In that case the twist is very much less, and as noted above, the twisting together of v ribbons may be effected at reasonable speeds as the rib- .bons emergeffrom the rollers 14.

FIGURE 4 shows, disassociated from other ribbons, the form taken by a single ribbon when twisted into a yarn, though curvature is here not indicated. The twisted ribbon, 32, has a generally helicoidal form. The illustnation is primarily to explain how flexibility is secured. The ribbon in its original flat condition as illustrated in FIGURE 3 would, of course, have flexibility in adirection transverse to its width dimension comparable to the flexibility of its individual filaments, but would not be flexible at right angles to this direction. However, as will be evident from FIGURE 4, when twisted it has, from a macroscopic standpoint, flexibility in all directions. This flexibility is of the same order as that of a twisted singles yarn of the same number of filaments; but it may be made greater or less, depending upon the particular diedesign and resultant product cross-section by varying the width-to-thickness dimensions of the ribbon or the shapes and dimensions of the bridge and/ or filament sections, resulting from the geometric configuration of the die opening. There is still another matter of significance evident from FIGURE 4: the filaments in the twisted ribbon have a'lead which is substantially greater than they would have if adequately twisted into a singles yarn. This represents better conformity to the desirable condition of extension of filaments as far as possible in the line of applied tension.

, FIGURE 5 shows a cross-section of a yarn provided by the twisting together of four

ribbons

34, 36, 38 and 40, each being of the type shown at 26 in FIGURE 3. In such twisting of the ribbons together to form the yarn 42,

' theywill, in general, assume curved cross-sections as indicated. Even further curvature may be produced 1n Anotherfsituation of significance is also-indicated in FIGURE 5. While the plastics suitable for rope making are more or less flexible and elastic, they do have a degree of rigiditywhich will, in some cases, particularly if polypropylene is used, and also in the case of polyethylene, cause the ribbons to resist transverse curvature to small radii. Accordingly, on twisting and compacting, some of the bridges between the filaments may be stressed to a condition producing breakage at surfaces such as indicated at 44. This, however, is not disadvantageous. breakages will only locally separate pairs of the filaments in the ribbon. They may thus become only intermittently connected, but since the breaks will be irregularly distributed throughout the ribbons, there will still remain the characteristic that the ribbons represent groups of filaments adequately connected. to provide units which are equivalent to, but with their own advantages, twisted singles yarns. It will be readily seen that when breaks do occur locally, the groups of filaments on opposite sides of the breaks will generally have stresses relieved so that further breakages in a ribbon at'a given cross-section are not likely to occur.

It may be noted that the filaments of a ribbon need not all be of the same size or shape; for example, large and small filaments may alternate across the width of a ribbon.

If it is desired to provide yarns by association of ribbon in a highly compact structure, the cross-sectionsof the ribbon may be desirably modified from that heretofore described by adopting the ribbons indicated, somewhat Such conventionalized, in FIGURE 6. In this figure the for associated ribbons are indicated at 46, 48, 50 and 52 Each filament here comprises the central rectangular poi tion 54 and trapezoidal portions 58 and 60 involving th 60 angular relationship illustrated. The bridges 62 at geometrically chosen so that, in the ideal condition, th ribbons may fit tightly together as illustrated. It will b evident that this represents in aminirnum cross-section: area a maximum amount of plastic, with substantiz elimination of such inherentopenings as must occur i a bundle of cylindrical elements. Rounding of corner will,- of course, occur both in the extrusion from the dlt the drawing before solidification, and later in the drawin of the ribbon. But there is a close and significant a; proach to what would be ideal: a yarn which had a solid] filled cross-section and nevertheless flexibility. Of COHISt the ideal exhibited in FIGURE 6 will not ordinarily is achievable since difliculty would be encountered in prt ducing the complementary interlockings as shown. B1 they will occur to a suflicient extent if the ribbons are fe parallel and in engagement with each other to produc considerable compacting of the yarn. The various ribbor are nevertheless free to move lengthwise with respect t each other, and when twisting occurs as indicated by th arrows 64, there will be achieved the flexibility of th generally-helicoidal ribbon configuration as was describe in reference to FIGURE 4.

The'ribbons as formed need not be flat, and FIGURi 7 illustrates a die plate 66 provided with an extende opening in which circular openings arranged in an arc a'circle are interconnected by bridge passages 70. Rt turning to FIGURE 5, it will be evident that the curve ribbons produced by the die plate 66 could be associate and twisted without such stressing as might, in the ca: of a similar fiat ribbon, result in breakage of the bridge Many other ribbon configurations may obviously I adopted with substantially equivalent results. In fact, ribbon might be extruded closed upon itself to form tube of bridged filaments, which tube in use, and due I twisting, might be flattened to bring its opposite sides ti gether with the filaments of the sides interlocking. Suc a flattened tubular ribbon may, of course, be directl extruded.

There may also be extruded a ribbon having a cros sectional area with a circumscribing outline of conside able extent in two dimensions as by the use of a die '1 having'an opening 74 providing filament-forming openin1 76 and bridge-forming openings 78, as shown in FIGUR 8. A ribbon thus formed will, on twisting, compact int a cross-section with abutting filaments.

It will now be understood that the term ribbon used herein has a broad connotation of indicating fil. ments which are joined continuously or intermittently exemplified by the foregoing and also by what will no be described with reference to FIGURE 9.

As described heretofore, the filaments of a ribbon we: continuously connected along their lengths by bridges, least as originally formed. It was also pointed out th under compacting stresses these bridges might be inte mittently broken, nevertheless maintaining the assembl of filaments into ribbon'units. It is, however, quite u] necessary to have the filaments connected to each otht except at intermittent quite limited spots, so long as t] connections are sufficient to prevent such substantial se arations of the filaments as might lead to snagging. Whe the ribbons are twisted together in a yarn or strand, eve though the twist is relatively loose, thereis a furth contribution to compacting, so that the connections b tween the ribbons may be relatively sparse. FIGURE illustrates the formation of a ribbon in which filame interconnections are minimized.

The die illustrated in FIGURE 9 comprises outer at inner

concentric members

80 and 82 having bearing su faces at 83. The inner surface of the outer member provided with outwardly extending openings 84 while t1 outer surface of the inner member is provided with i drawing; but twist may also be effected by suitable tive and-absolute rotations of'the die members, for nple, both may be rotated. in the same direction but itferent speeds so that relative rotation will determine, :onection with the linear rate of extrusion, the frency of occurrence of bridges along the length of the on while the mean rate of rotation will determine the t :edure for extrusion which may be more generally owed: as the plastic material leaves a die it is liquid emi-liquid and consequently if filaments are extruded mgh non-bridged openings and immediately brought :ther so as to touch each other they will cohere to pro- 2 the desired bridging.

.ibbons produced as described with reference to FIG- E 9 will obviously have high flexibility to provide (Cd cross-section and will also provide effective inter- ;ing action.

1eginning with the yarns, the formation of the rope is ventional, and may be carried out as usual through :ting, braiding and/ or plaiting operations.

is is usual, it is desirable to provide opposite twisting he steps of forming yarn from the ribbon, strands n the yarns, and rope from the strands, though this rnation may be varied if desired. The various opera- S are carried out in conventional fashion. When flat mm are used, as shown in FIGURE 3, they may be wisted when assembled and fed to the twister to form n, i.e., being untwisted prior to this yarn formation, procedure differing, thus, from the twisting of filalts in the usual formation of singles yarns prior to :mbly by reverse twisting into plied yarns. But if the IOIIS are not flat (e.g., as produced by the dies of iURES 8 and 9), they may or may not'be twisted themselves before being twisted into yarns or strands. lne of the major advantages of the invention is that I very few ribbon extruding devices need be provided t rope making plant to provide a great range of ropes. fact, ribbons of only three different deniers need be vided for ropes ranging from inch to 9 inches. For mple, for ropes in the range from A inch to A t in nominal diameter, only 9,000 denier ribbons d be produced. In this range the ribbons per yarn I range from 2 to 6, and the yarns per strand from 8 to make three strand rope. For the range of ropes n 3 inches to 6 inches (nominal circumference) ribs of 27,000 denier may be provided. In this range the mm per yarn may be 7 to 9, while the yarns per strand 7 range from 3 to 9. For 6 inch to 9 inch ropes, extruded ribbons may have a denier of 52,000. The tons per yarn will then be 8 or 9, and the yarns per nd 6 to 10.

LS specific examples for three strand ropes, the foling may be cited: or a inch rope, two 9,000 denier ribbons may n each yarn, and two yarns may form each strand, resulting strand having a denier of 36,000.

"or a inch rope, four ribbons, each of 9,000 denier, form a yarn, three yarns may form a strand, and :e strands a rope. FIGURES 3, 4, 5, 10 and 11 may considered as illustrating specifically this rope and its iponents and steps in its formation.

"or a Vs inch rope, six 9,000 denier ribbons may form it yarn, and eight yarns each strand.

he last described extrusion also exemplifies another.

upper limit depending upon the flexibility of the plastic used and the thickness of the ribbon; i.e., if the ribbon is thin, though wide, flexibility may be acceptable.

While the strands may be of layered formation, if desired, and are highly resistant to hockling because of the structural characteristics of the assembly as heretofore described, the additional complexities of forming layered strands may be avoided by twisting yarns of the type described into strands without layering. Also, ribbons may be twisted into strands without'intermediate formation of yarns.

The elimination of layering has another very important advantage in that by this elimination there is greater translation of material and yarn strengths into finished rope strengths. As ordinarily practiced layering involves greatly different contributions of yarns in the various layers to rope strength, whereas if layering is not used more uniform contributions of the yarns to rope strength are attained.

For purposes of illustration, FIGURE 10 shows diagrammatically a strand 102 formed of twisted yarns 42, while FIGURE 11 shows a section of a rope 104 laid from the strands 102. The yarns 42 are, for illustration, shown in solid sections, but it will be understood they have component ribbons as shown in FIGURE 5.

The ribbons which are associated to form the cordage component, i.e., yarn or strand, need not have the same composition, but may differ from each other tosecure desired properties; for example, to cite a single instance, a yarn or strand may be formed for mixed ribbons some of which may be of polyethylene and others of polypropylene to secure the improved property of non-sticking on bitts. Various advantageous compositions oftheribbons will now be discussed, and it will be understood that when special compositions are used these may provide only some of the associate ribbons, though all of the ribbons may be of the same composition.

It has been found particularly advantageous to provide ribbons which, to the extent of their plastic content, comprise mixtures which are largely or entirely of polypropylene and polyethylene. Highly effective are compositions containing polypropylene and polyethylene in approximately equal proportions. When ribbons of such a composition are extruded and radiant heat is used in the orientation, unusually high strengths are secured.

Also usable are mixtures of polyolefins (such as polypropylene or polyethylene or mixtures thereof) with polyamides, polyesters, or the like, as may be desirable to secure various properties as may be desired.

The use of various solid fillers is highly advantageous. Heretofore when small denier filaments were extruded it was impractical to incorporate solid materials except in very minor proportions (such as pigments, which may be used in very small percentages) because the solid materials produced great difficulties in-maintaining smooth flow through the dies. This was the case even when the solid materials were very fine because some agglomeration would occur in their suspension in the molten plastic carrier and this would particularly show up as high stress points in the filaments making them quite weak, as well as causing clogging of the small die openings. Attempts to use other than very finely pulverized materials were completely futile, excluding the possible uses of fibrous materials, glass beads, or the like. However, with the extrusion of high denier ribbons as heretofore described, the denier, of course, referring to the final ribbon, the overall die openings become sufficiently large i sirable to provide quite heavy ropes.

glass beads or the like are to be incorporated, ribbons of even greater deniers should desirably be produced.

'No ditficulties are experienced with ribbons of 9,000

denier which, as indicated above, may be used for the production of even the smallest commercial sizes of ropes.

The solid materials are, of course, incorporated in the plastic materials in. the molten state of these materials with thorough mixing with conventional apparatus well known in the art, and as the initial material for the present procedures such mixture is provided in theform of small pellets to the extruder.

The solid materials used may be of great variety depending on the desired properties, and in various instances, as will appear, several desirable properties may be secured using the same material or materials.

.Consideration may be first given to increasing the specific gravity of the rope material. In many cases the low specific gravities of plastics such as polypropylene and polyethylene are highly advantageous, making for easier handling of ropes and providing ropes for the advantage in some cases of floatingon water. But in other instances this is disadvantageous and it is desirable to have ropes which will sink. Thus it sometimes becomes de- In these cases weighting materials may be used among which maybe cited barium sulphate, aluminum silicates (or pulverized artificial lights. Fluorescent materials may also be incorporated to increase visibility by enchancingthe effec tive intensity of incident light.

Another modification of the ribbons may be eifecter by incorporating in the plastic fed to the extruder foam ing or blowing agents which, by the heat of extrusion Jwill in usual fashion liberate gas in the form of smal bubbles to increase the bulk of the extruded material witl major decrease of density. Ropes provided from ribbon whiohthus entrain gas bubbles will bevery light and ma befused as centers for wire cables or the like where ligh weight rather than strength is required.

rocks in general) and fibrous materialssuch as asbestos and glass fibers; A material such as barium sulphate is highly effective and may be readily incorporated in large quantities up to around 50% or more by weight of the final composition. This, of course, represents a relatively I lower volume as compared with the plastic composition such as polypropylene or polyethylene in which it is in corporated. The fibrous materials'such as asbestos and glassfibers also impart flame resistance to the product.

' As lubricants there may be incorporated barium stearate or other lubricating materials such as other metallic stear'ates or salts of other fat acids, graphite, molybdenum sulphide, aluminum sulphide, waxes, or the like. The use of such materials provides lubrication for the relative lengthwise movements of the rope elements, making unnecessary'the use of external lubricants such as oils or greases which have been commonlyv provided in connection with cordage. Sticking on bitts or other elements about which arope is trained is also avoided by the use of these incorporated lubricating materials.

In some cases electrical conductivity of a plastic rope or cable is desired to avoid the collection of static charges, to provide grounding, or even to transmit signals. Conductivity may be secured by incorporating various forms 'of carbon or metallic powders.

' If, on the other hand, high dielectric properties are deisred, a material such as barium stannate may be used. While flame retarding may be provided by various I materials already mentioned,-other flame retardants may be used such as aluminum sulphate, chlorinated paraffin, a tungstate, or. the like.

. Luminescent properties of various types may bepro- While twisted ropes have been primarily considerer in the foregoing, it is obvious that yarns or strand provided in accordance with the invention may be used tr form braided or plaited ropes and cables, the construc tions of which will be conventional except for their origi1 in ribbons.

It will also be evident that other light 'cordag may also be provided in accordance with the inventior It is accordingly to be understood that the invention i not to be regarded as limited except as required by th following claims.

What is claimed is:

l. Cordage comprising a plurality of strands compact ly assembled with each other, each of said strands con prising a plurality of extruded and oriented plastic ele ments compactly assembled with each other, each of whic elements comprises a plurality of continuous filaments 2 least intermittently integrally joined together with sul stantial freedom of said filaments for movements rel: tively to each other, said elements presenting externall to each other irregular surfaces impeding their relativ lateral movements, said elements having individual denie1 of at least 500, atleast some of which. plastic elemen are formed of a thermoplastic composition and a no] plastic-solid material substantially uniformly dispersed i i said plastic composition.

, elements comprises a plurality of continuous filamen at least intermittently integrally joined together by brid ing portions of less thickness than the filaments, said e1 ments presenting externally to each other irregular st faces impeding their relative lateral movements, said el .ments havingindividual deniers of at least 500, at let some of which plastic elements are formed of a therm plastic composition and a non-plastic solid material so stantially uniformly dispersed in said plastic compositic 6. Cordage according to claim 5 in which said nc plastic solid material has lubricating qualities.

vided. If high reflectivity is desired so that a rope in f the dark may become visible by reflecting distant lights,

small glass beads may be incorporated in the ribbonforming material, these being effective particularly if a fairly transparent or translucent plastic is used. Alternatively, phosphorescent materials such as the usual barium sulphide-calcium sulphide mixtures may be used which will glow in the dark after exposure to daylight or 7. Cordage according to claim 5 in which said nc plastic solid material is a weighting material.

8. Cordage according to claim 5 in which said he plastic solid material is fibrous.

9. Cordage comprising a plurality of strands co pactly assembled with each other, each of said strar comprising a plurality of extruded and oriented plas elements compactly assembled with each other, each said elements being in the form of a ribbon having a Wi( multiple times its thickness and having a denier of at le 500, at least some of which plastic elements are tom of a thermoplastic composition and a non-plastic sc material substantially uniformly dispersed in said pla: composition.

10. Cordageaccording to claim 9 in which said hi plastic solid material has lubricating qualities.

11 l. Cordage according to claim 9 in which said nontic solid material is a weighting material. 2. Cordage according to claim 9 in which said nontic solid material is fibrous. 3. Cordage comprising a plurality of strands com- ;ly assembled with each other, each of said strands iprising a plurality of extruded and oriented plastic tents compactly assembled with each other, each of elements being in the form of a ribbon having a width tiple times its thickness and having a denier of at least order of 9000, at least some of which plastic elements formed of a thermoplastic composition and a nontic solid material substantially uniformly dispersed in plastic composition. 4. Cordage according to claim 13 in which said non- .tic solid material has lubricating qualities. 5. Cordage according to claim 13 in which said nonlilC solid material is a weighting material. 6. Cordage according to claim 13 in which said non- ;tic solid material is fibrous. 7. Cordage comprising a plurality of strands comtly assembled with each other, each of said strands tprising a plurality of extruded and oriented plastic nents compactly assembled with each other, each of elements being in the form of a ribbon having a lh multiple times its thickness and having a denier of east 500, at least some of which plastic elements are ned of a thermoplastic composition containing gas stantially uniformly dispersed therein. 8. Cordage comprising a plurality of strands comtly assembled with each other, each of said strands tprising a plurality of extruded and oriented plastic nents compactly assembled with each other, each of 1 elements being in the form of a ribbon having a th multiple times its thickness and having a denier of east the order of 9000, at least some of which plastic nents are formed of a thermoplastic composition coniing gas substantially uniformly dispersed therein.

9. Cordage comprising a plurality of strands comtly assembled with each other, each of said strands iprising a plurality of extruded and oriented plastic nents compactly assembled with each other, each of 1 elements being in the form of a ribbon having a width ltiple times its thickness and having a denier of at it 500, at least some of which plastic elements are ned of a thermoplastic mixture comprising primarily stantial amounts of each of polypropylene and polyylene.

10. Cordage comprising a plurality of strands comtly assembled with each other, each of said strands uprising a plurality of-extruded and oriented plastic nents compactly assembled with each other, each of 1 elements being in the form of a ribbon having a width ltiple times its thickness and having a denier of at at the order of 9000, at least some of which plastic elents are formed of a thermoplastic mixture comprising primarily substantial amounts of each of polypropylene and polyethylene.

21. Cordage comprising a plurality of strands compactly assembled with each other, each of said strands comprising a plurality of extruded and oriented plastic elements compactly assembled with each other, each of said elements being in the form of a ribbon having a width multiple times its thickness and having a denier of at least 500, at least some ofwhich plastic elements are formed of a thermoplastic mixture comprising primarily approximately equal amounts of polypropylene and polyethylene.

22. Cordage comprising a plurality of strands compactly assembled with each other, each of said strands comprising a-- plurality of extruded and oriented plastic elements compactly assembled with each other, each of said elements being in the form of a ribbon having a width multiple times its thickness and having a denier of at least the order of 9000, at least some of which plastic elements are formed of a thermoplastic mixture comprising primarily approximately equal amounts of polypropylene and polyethylene.

23. Cordage comprising a plurality of strands compactly assembled with each other, each of said strands comprising a plurality of extruded and oriented plastic elements compactly assembled with each other, each of said elements being in the form of a ribbon having a width multiple times its thickness and having a denier of at least 500, at least some of whichplastic elements are formed of a thermoplastic mixture comprising primarily at least one polyolefin and atleast one thermoplastic of nonolefinic type.

24. Cordage comprising a plurality of strands compactly assembled with each other, each of said strands comprising a plurality of extruded and oriented plastic elements compactly assembled with each other, each of said elements being in the form of a ribbon having a width multiple times its thickness and having a denier of at least the order of 9000, at least some of which plastic elements are formed of a thermoplastic mixture comprising primarily at least one polyolefin and at least one thermoplastic of non-olefinic type.

References Cited in the file of this patent UNITED STATES PATENTS 2,382,355 Warren Aug. 14, 1945 2,385,890 Spanagel Oct. 2, 1945 2,694,606 Etzkorn Nov. 16, 1954 2,945,739 Lehmicke July 19, 1960 2,959,839 Craig Nov. 15, 1960 2,991,147 Thomas July 4, 1961 3,015,150 Fior Jan. 2, 1962 3,039,174 Radow et al June 19, 1962 FOREIGN PATENTS 861,114 Great Britain Feb. 15, 1961

Claims

1. CORDAGE COMPRISING A PLURALITY OF STRANDS COMPACTLY ASSEMBLED WITH EACH OTHER, EACH OF SAID STRANDS COMPRISING A PLURALITY OF EXTRUDED AND ORIENTED PLASTIC ELEMENTS COMPACTLY ASSEMBLED WITH EACH OTHER, EACH OF WHICH ELEMENTS COMPRISES A PLURALITY OF CONTINUOUS FILAMENTS AT LEAST INTERMITTENTLY INTEGRALLY JOINED TOGETHER WITH SUBSTANTIAL FREEDOM OF SAID FILAMENTS FOR MOVEMENTS RELATIVELY TO EACH OTHER, SAID ELEMENTS PRESENTING EXTERNALLY TO EACH OTHER IRREGULAR SURFACES IMPEDING THEIR RELATIVE LATERAL MOVEMENTS, SAID ELEMENTS HAVING INDIVIDUAL DENIERS OF AT LEAST 500, AT LEAST ONE OF WHICH PLASTIC ELEMENTS ARE FORMED OF A THERMOPLSTIC COMPOSITION AND A NONPLASTIC SOLID MATERIAL SUBSTANTIALLY UNIFORMLY DISPERSED IN SAID PLASTIC COMPOSITION.