Optical fiber cable with jacket having co-extruded elements and tooling for forming same

Abstract

The disclosure relates to an optical fiber cable. The optical fiber cable includes a cable jacket having an inner surface and an outer surface. The inner surface defines a central bore extending along a longitudinal axis of the optical fiber cable, and the outer surface defines an outermost surface of the optical fiber cable. At least one optical fiber is disposed within the central bore. The cable jacket includes an outer matrix formed from a first polymer composition and a plurality of filaments formed from a second polymer composition embedded in the outer matrix.

Description

Atty Dkt No. : HI24-119PCTOPTICAL FIBER CABLE WITH JACKET HAVING CO-EXTRUDED ELEMENTS AND TOOLING FOR FORMING SAME CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of U.S. Provisional Application No.63 / 721,001, filed on November 15, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.BACKGROUND

[0002] The disclosure relates generally to an optical fiber cable and method for producing same and, in particular, to a cable jacket of an optical fiber cable having co-extruded structures and an extrusion die for producing same.

[0003] In an optical fiber cable, certain materials are chosen for various elements of the construction based on such factors as desired properties, cost, and ease of manufacturability. With respect to the cable jacket, polymers are typically used to encase the cable core because of the relatively low cost and extrudability over long lengths. However, being the outermost layer of the optical fiber cable, there are many different environmental and structural concerns associated with the cable jacket. Polymers satisfy these concerns to varying degrees. For instance, certain polymers may provide adequate mechanical strength and chemical resistance, but the thermal properties may not be ideal for a particular application. Accordingly, material selection may involve tradeoffs in terms of emphasizing certain properties, especially when evaluated in light of the cost to provide enhanced properties.SUMMARY

[0004] According to an aspect, embodiments of the disclosure relate to an optical fiber cable. The optical fiber cable comprises a cable jacket having an inner surface and an outer surface. The inner surface defines a central bore extending along a longitudinal axis of the optical fiber cable, and the outer surface defines an outermost surface of the optical fiber cable. At least one optical fiber is disposed within the central bore. The cable jacket comprises an outer matrix comprising a first polymer composition and a plurality of filaments comprising a second polymer composition embedded in the outer matrix.Atty Dkt No. : HI24-119PCT

[0005] According to another aspect, embodiments of the disclosure relate to a method of preparing an optical fiber cable. In the method, a first polymer composition is co-extruded with a second polymer composition through an extrusion die comprising a tip insert to form an optical fiber cable jacket around a cable core. The cable core comprises at least one optical fiber. The tip insert comprises a plurality of grooves configured to form the second polymer composition into a plurality of filaments embedded in an outer matrix of the first polymer composition. The outer matrix defines an outermost surface of the optical fiber cable.

[0006] Additional features and advantages will be set forth in the detailed description that follows, and, in part, will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings.

[0007] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or framework to understand the nature and character of the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment s), and together with the description serve to explain principles and the operation of the various embodiments.

[0009] FIG. 1 depicts a cross-sectional view of an optical fiber cable having a cable jacket with an outer matrix and a plurality of filaments, according to an exemplary embodiment;

[0010] FIGS. 2 and 3 depict cross-sectional views of a cable jacket with filaments extending to a deeper depth (FIG. 2) and a shallower depth (FIG. 3) than the filaments shown in FIG. 1, according to exemplary embodiments;

[0011] FIG. 4 is a cross-sectional view of an extrusion die and tip insert for producing a cable jacket having a plurality of filaments, according to an exemplary embodiment;Atty Dkt No. : HI24-119PCT

[0012] FIG. 5 depicts a first tip insert design, according to an exemplary embodiment;

[0013] FIGS. 6A and 6B depict a second tip insert design, according to an exemplary embodiment;

[0014] FIGS. 7A-7C provide tables of polymer flow patterns based on the winding of grooves of the tip insert at different angles relative to a longitudinal axis of the tip insert as well as the structure of the cable jacket produced by same, according to exemplary embodiments; and

[0015] FIGS. 8-12 depict experimental examples of cable jackets produced using the tip insert and extrusion die, according to embodiments of the present disclosure.DETAILED DESCRIPTION

[0016] Referring generally to the figures, various embodiments of an optical fiber cable having a cable jacket with co-extruded filaments and tooling for producing the same are provided. As will be discussed more fully below, the cable jacket includes an outer matrix in which a plurality of filaments is embedded during a co-extrusion process. The co-extrusion process utilizes a specialized tip insert in an extrusion die to manipulate the molten polymers of the jacket and of the filament to improve the interaction between the two. Advantageously, the tip insert improves the adhesion and / or mechanical interlocking of the outer matrix and embedded filaments by increasing the area and changing the geometry of the interface between the outer matrix and filaments. In this way, the filaments can be used to increase the stiffness of the cable jacket (e.g., to improve blowing or jetting performance) or to reduce thermal shrinkage, amongst other possibilities. Exemplary embodiments of the optical fiber cable and method of producing same will be described in greater detail below and in relation to the figures provided herewith, and these exemplary embodiments are provided by way of illustration, not by way of limitation.

[0017] FIG. 1 depicts a cross-sectional view of an embodiment of an optical fiber cable 10 according to the present disclosure. The embodiment of the optical fiber cable 10 depicted in FIG.1 is merely exemplary, and as will be discussed more fully below, a variety of optical fiber cable types with a wide range of sizes and structures can make use of the teachings of the present disclosure. The optical fiber cable 10 includes a cable jacket 12 having an inner surface 14 and an outer surface 16. The inner surface 14 defines a central bore 18 of the cable jacket 12 that extendsAtty Dkt No. : HI24-119PCTalong a longitudinal axis of the optical fiber cable 10. In one or more embodiments, the outer surface 16 defines an outermost surface of the optical fiber cable 10. A maximum distance between the inner surface 14 and the outer surface 16 defines a thickness T of the cable jacket 12. In one or more embodiments, the thickness T of the cable jacket 12 is 0.2 mm or greater, and in certain embodiments, the thickness T is up to about 10% of the cable diameter.

[0018] Disposed within the central bore 18 is a cable core 20. The cable core 20 includes at least one optical fiber 22. In the exemplary embodiment shown in FIG. 1 , the optical fiber 22 is disposed in a buffer tube 24. Further, in the embodiment depicted, the buffer tube 24 is a tight buffer tube in which the inner surface of the buffer tube 24 contacts the outer surface of the optical fiber 22 such that the optical fiber 22 is a tight buffered optical fiber. However, in one or more other embodiments, the buffer tube 24 may be a loose tube in which the inner surface of the buffer tube 24 does not contact the outer surface of the optical fiber 22, and the loose tube may include a plurality of optical fibers 22. In one or more embodiments, the buffer tube 24 may include, e.g., from one to twenty-four optical fibers 22. Further, the optical fibers 22 disposed within the buffer tube 24 may be arranged in continuously or intermittently bonded ribbons. Still further, while one buffer tube 24 is depicted, the cable core 20 may include a plurality of buffer tubes 24, each containing one or more optical fibers 22. Yet further, aspects of the cable jacket 12 described herein are equally applicable to embodiments of the cable 10 in which the cable core 20 does not include a buffer tube 24. For instance, the cable core 20 can include optical fibers disposed in intermittently-bonded ribbons that are wrapped with binder threads or thin films or that are disposed loosely in the cable jacket 12.

[0019] The cable core 20 may include a variety of additional structures surrounding the buffer tube 24. In the embodiment depicted, optical fiber cable 20 includes a plurality of strengthening yarns 26, such as fiber glass, aramid, or basalt yarns, around the buffer tuber tube 24.

[0020] Other structures that may be included in the cable core 20 are water-blocking tape or yarns, an armor layer, or strength members (e.g., fiber-reinforced strength members or metal wires). In one or more embodiments, the cable core 20 may include a plurality of buffer tubes 24 stranded around a central strength member.Atty Dkt No. : HI24-119PCT

[0021] According to the present disclosure, the cable jacket 12 includes a continuous outer matrix 30 and a plurality of filaments 32 embedded within the continuous outer matrix 30. In one or more embodiments, the filaments 32 are discrete elements disposed within the continuous outer matrix 30. That is, the filaments 32 are not connected to one or more of the other filaments. In one or more other embodiments, such as the embodiment shown in FIG. 1, the filaments 32 are connected by a web 34 extending between adjacent filaments 32. In one or more embodiments, the cable jacket 12 comprises at least two filaments 32, at least four filaments 32, at least seven filaments 32, at least ten filaments 32, or at least fifteen filaments 32. In general, there is no specific upper limit to the number of filaments 32; however, depending on the circumference and thickness of the cable jacket 12, the number of filaments 32 may be limited so as to avoid creating essentially a continuous layer instead of a series of filaments 32. In one or more embodiments, the cable jacket 12 includes more than two filaments 32 to avoid creating a preferential bend axis in the optical fiber cable 10. In one or more embodiments in which the filaments 32 are connected by webs 34, the combination of filaments 32 and webs 34 defines the inner surface 14 of the cable jacket 12.

[0022] In one or more embodiments, the filaments 32 have a first depth Di and a width W. The first depth Di is the maximum distance that the filament 32 extends into thickness T of the cable jacket 12 (e.g., measured from the inner surface 14 of the cable jacket 12). In one or more embodiments, the first depth Di is expressed as a percentage of the thickness T, such as a first depth Di of up to 80% of the thickness T, e.g., in a range from 10% to 80% of the thickness T. In one or more embodiments, the width W is the widest distance across the filament 32 (radially outside of the web 34 if present) transverse to the first depth Di. In one or more embodiments, a combined width W of all the filaments is in a range from 30% to 70% of the circumference of the cable jacket 12 at the depth at which the width W is measured. In embodiments where the widths W of the filaments 32 are different, the combined width W of all filaments 32 can in the range from 30% to 70% of the circumference of the cable jacket 12 at the depth at which the maximum of the widths W is measured. In one or more embodiments, where included, the web 34 has a second depth D2 that extends from 10% to 90% of the first depth Di. As will be apparent from the following description, the filaments 32 and webs 34 (where provided) are substantially continuous structures extruded along the length of the optical fiber cable 10. Notwithstanding, in one or more other embodiments, the filaments 32 and webs 34 may be discontinuous along the length of theAtty Dkt No. : HI24-119PCToptical fiber cable 10, e.g., extending in discrete sections along the length of the optical fiber cable 10.

[0023] In one or more embodiments, the outer matrix 30 comprises a first polymer composition, and the filaments 32 and webs 34 comprise a second polymer composition. In one or more embodiments, the second polymer composition is different from the first polymer composition. In one or more embodiments, the second polymer composition comprises at least one of a higher Young’s modulus, a higher tensile strength, and / or a lower coefficient of thermal expansion (CTE) than the first polymer composition.

[0024] In one or more embodiments, the first polymer composition and the second polymer composition are thermoplastic polymers. The thermoplastic polymers are not particularly limited in terms of molecular weight and distributions, and the thermoplastic polymers may be homopolymers, heteropolymers, or copolymers. In one or more embodiments, the thermoplastic polymers are selected from among polyolefins, polyvinylchloride, polystyrene, acrylonitrile butadiene styrene, styrene-acrylonitrile, styrene-ethylene-butylene-styrene, and technical thermoplastics. In one or more embodiments, the polyolefins include polyethylenes (very low density, linear low density, low density, medium density, high density, and ultrahigh molecular weight), polypropylene (isotactic, syndiotactic, and atactic), and polyolefin-based thermoplastic elastomers (such as ethylene vinyl acetate, ethylene butyl acrylate, ethylene methyl acrylate, thermoplastic olefin elastomer, ethylene-propylene rubber, and ethylene propylene diene monomer rubber). In one or more embodiments, the technical thermoplastics include polyesters (such as polybutylene terephthalate, polyethylene terephthalate, polycarbonate, poly methyl methacrylate, and polyoxymethylene), polyethers (such as polyphenylene ether and poly(p-phenylene oxide)), polyamides (such as polyamide 6, polyamide 12, polyamide 6.6, polyamide 4.6, and polyamide 11), polyacetal, polysulfones (such as poly ethersulfone, polysulfone, and polyphenylene sulfide), polyimides, liquid crystalline polymers and polyketones.

[0025] In one or more embodiments, one or both of the first polymer composition and the second polymer composition may further include a coupling agent. In one or more embodiments, the coupling agent is one of the polymers of the first polymer composition or the second polymer composition functionalized with a functional group. In one or more embodiments, the functionalAtty Dkt No. : HI24-119PCTgroup is maleic acid anhydride, silane, epoxy, acrylate, amine, hydroxyl, melamine, zirconate, titanate, polyol, or ester. In one or more embodiments, the coupling agent is present in an amount of up to 15 wt%, in particular in a range from 3 wt% to 10 wt%, and most particularly in a range from 5 wt% to 6 wt%, of the respective first polymer composition or the second polymer composition.

[0026] In one or more embodiments, the first polymer composition and the second polymer composition may further comprise additives, such as colorants, flame retardants, fillers, and processing aids, amongst other possibilities.

[0027] FIGS. 2 and 3 depict additional examples of a cable jacket 12 having filaments 32 and webs 34 of larger and smaller sizes compared to the filaments 32 and webs 34 of FIG. 1. With reference first to FIG. 2, the filaments 32 extend to a deeper first depth Di into the thickness T of the cable jacket 12 and have a wider width W than the filaments 32 of FIG. 1. Further, the webs 34 extend to a deeper second depth D2 into the thickness T of the cable jacket 12 than the webs 34 of FIG. 1. By contrast, with reference to FIG. 3, the filaments 32 extend to a shallower first depth Di and have a narrower width W than the filaments 32 of FIG. 1. Similarly, the webs 34 extend to a shallower second depth D2 than the webs 34 of FIG. 1. In one or more embodiments, the ratio of the second polymer composition of the filaments 32 and webs 34 to the first polymer composition of the outer matrix 30 is in a range of 0.05 to 0.80. In the embodiments shown in FIGS. 1-3, the ratios of second polymer composition of the filaments 32 and webs 34 to the first polymer composition of the outer matrix 30 are 0.32, 0.68, and 0.11, respectively. The relative amount of the first polymer composition and the second polymer composition can be adjusted by adjusting the feed rate during co-extrusion for the first polymer composition and the second polymer composition. In particular, increasing the feed rate of the second polymer composition relative to the feed rate of the first polymer composition will increase the ratio of the second polymer composition to the first polymer composition (thereby increasing the first depth Di of the filaments 32), and decreasing the feed rate of the second polymer composition relative to the feed rate of the first polymer composition will decrease the ratio of the second polymer composition to the first polymer composition (thereby decreasing the first depth Di of the filaments 32).Atty Dkt No. : HI24-119PCT

[0028] FIG. 4 depicts a cross-sectional view of an extrusion die 50 with tip insert 52 configured for extruding the cable jacket 12 structure shown in FIGS. 1-3. As shown in FIG. 4, the extrusion die 50 includes a first end 56 and a second end 58. The first end 56 has an inlet 60 configured to receive molten polymer from an extruder, and the second end 58 has an outlet 62 from which emerges the cable core 20 with molten polymer formed therearound. The inlet 60 has a first diameter, and the outlet 62 has a second diameter. The first diameter is greater than the second diameter. Between the inlet 60 and the outlet 62 is a tapered channel 64 that tapers from the first diameter to the second diameter.

[0029] Disposed within the tapered channel 64 is the tip insert 52. The tip insert 52 includes a head portion 66 and a body portion 68. The body portion 68 provides a mounting structure for placement of the tip insert 52 in the tapered channel 64 of the extrusion die 50. Grooves 70 are formed in an exterior surface of the head portion 66. The grooves 70 cause formation of the filaments 32 and webs 34 during co-extrusion of the first polymer composition of the outer matrix 30 and the second polymer composition of the filaments 32 and webs 34. The width and depth of the grooves 70 determines the width W and first depth Di of the filaments 32. Additionally, the position of the tip insert 52 relative to the tapered channel 64 determines the presence or absence of the webs 34 and the second depth D2 of the webs 34.

[0030] As can be seen in FIG. 4, the tip insert 52 includes a central passage 72 through which the cable core 20 is run during co-extrusion. The central passage 72 extends along a longitudinal axis 74 of the tip insert 52. In one or more embodiments, the grooves 70 extend straight along the longitudinal axis 74. In one or more other embodiments, the grooves 70 wind helically at least partially around the longitudinal axis 74. In one or more such embodiments, the grooves 70 helically wind up to 180° around the longitudinal axis 74.

[0031] As is known in the art, a co-extrusion process requires the use of a complex and costly crosshead for combining the polymer compositions into an extruded product. According to the present disclosure, minor components of the crosshead, in particular the extrusion die 50 and the tip insert 52, can be exchanged to provide a wide variety of cable jacket structures based on the number of filaments 32, presence or absence of webs 34, and relative depth and width of the filaments 32 and webs 34. In this way, different cable designs can be accommodated by having aAtty Dkt No. : HI24-119PCTplurality of dies 50 and tip inserts 52, which are much less expensive than having a corresponding number of co-extrusion crossheads. Further, the die 50 and tip insert 52 can be relatively easily and quickly swapped on existing co-extrusion lines to convert the existing line back-and-forth between one configured for producing a cable jacket 12 according to the present disclosure and one configured for other co-extrusion structures.

[0032] FIG. 5 depicts an embodiment of a tip insert 52 having helical grooves 70. As can be seen in FIG. 5, the head portion 66 includes a shoulder 76 and a tip 78, and the head portion 66 defines a generally concave surface relative to a line 80 extending between the shoulder 76 and the tip 78. The concavity of the head portion 66 prevents the head portion 66 from coming into contact with the tapered channel 64 of the extrusion die 50. The tip insert 52 of the type shown in FIG. 5 leads to increased contact area between the first polymer composition and the second polymer composition, creating a wavy interface between the first polymer composition and the second polymer composition. That is, the difference between the first depth Di of the filaments 32 and the second depth D2 of the webs 34 is small, e.g., as compared to the embodiments shown in FIGS.1-3.

[0033] FIGS. 6A and 6B depict a perspective view and a tip view of another example of a tip insert 52 according to an embodiment of the present disclosure. As compared to the embodiment shown in FIG. 5, the embodiment of FIGS. 6A and 6B has a head portion 66 designed to contact the tapered channel 64 of the extrusion die 50. In this regard, the exterior surface of the head portion 66 between the shoulder 76 and the tip 78 is not concave and, in one or more embodiments, may be generally convex relative to a line extending between the shoulder 76 and the tip 78.

[0034] In the embodiment shown in FIGS. 6A and 6B, the head portion 66 includes seven grooves for creating seven filaments 32. Each of the seven grooves is helically wound 180° around the longitudinal axis 74 of the tip insert 52.

[0035] FIGS. 7A-7C depict the flow of a first polymer composition 90 and a second polymer composition 92 through three tip inserts having different groove configurations as well as resultant cable jacket 12 structures produced thereby. More specifically, the polymer flow is essentially the negative of the tip insert structure. Thus, walls of the grooves 70 are shown as openings, i.e., portions where the polymer compositions 90, 92 do not flow within the head portion. ReferringAtty Dkt No. : HI24-119PCTfirst to FIG. 7A, the head portion 66 has straight grooves 70. That is, the grooves 70 do not wind, or wind 0°, around the longitudinal axis 74. As can be seen in the bottom portion of FIG. 7A, the cable jacket 12 includes filaments 32 and webs 34 in which the difference between the first depth Di of the filaments 32 and the second depth D2 of the webs 34 is small. Further, the filaments 32 have a substantially symmetric cross-sectional area as compared to the embodiments that will be discussed below in relation to FIGS. 7B and 7C.

[0036] With reference now to FIG. 7B, the head portion 66 has grooves 70 that wind 90° around the longitudinal axis 74. As can be seen in the bottom portion of FIG. 7B, the cable jacket 12 includes filaments 32 and webs 34 in which the difference between the first depth Di of the filaments 32 and the second depth D2 of the webs 34 is greater than the embodiment of FIG. 7A. Further, the filaments 32 do not have a symmetric cross-sectional area, and instead, the filaments 32 and webs 34 define a sawtooth configuration.

[0037] Finally, with respect to FIG. 7C, the head portion 66 has grooves 70 that wind 180° around the longitudinal axis 74. As can be seen in the bottom portion of FIG. 7C, the cable jacket 12 includes filaments 32 and webs 34 in which the difference between the first depth Di of the filaments 32 and the second depth D2 of the webs 34 is greater than both the embodiments of FIGS.7A and 7B. Further, the filaments 32 again do not have a symmetric cross-sectional area, and instead, the filaments 32 and webs 34 define a sawtooth configuration that is even more exaggerated than the embodiment shown in FIG. 7B.

[0038] Thus, in comparing the embodiments shown in FIG. 7A-7C, the winding of the grooves 70 around the longitudinal axis affects both the first depth Di of the filaments 32 and the second depth D2 of the webs 34 as well as the shape of the filaments 32. In particular, a higher degree of winding around the longitudinal axis 74 increases the first depth Di, increases the difference between the first depth Di and the second depth D2, and increases the asymmetry of the cross-sectional area of the filament 32.

[0039] Accordingly, the size and shape of the filaments 32 and webs 34 can be changed by varying at least the following parameters: (i) the degree of winding of the grooves 70 in the head portion 66, (ii) the size of the grooves 70, (iii) the degree of contact between the tip insert 52 and the tapered channel 64 of the extrusion die 50, (iv) the spacing (gum space) between the tip insert 52Atty Dkt No. : HI24-119PCTand tapered channel 64 of the extrusion die 50, and (v) the respective feed rates of the first polymer composition and the second polymer composition.

[0040] EXPERIMENTAL EXAMPLES

[0041] Several cable jackets 12 were extruded using tip inserts 52 according to the present disclosure. In each of the following examples, the cable jacket 12 includes an outer matrix 30 that is high density polyethylene (HOPE).

[0042] FIG. 8 depicts a first example of a cable jacket 12 produced using the tip insert 52 of FIG.5. The second polymer composition of the filaments 32 and the webs 34 was polypropylene. As can be seen in FIG. 8, there is a small difference between the depths of the filaments 32 and the webs 34. As discussed above, the concave surface that prevents contact between the head portion 66 and the tapered channel 64 allows for increased flow of the second polymer composition around the tip insert 52 so as to increase the depth of the webs 34, producing a wavy interface between the outer matrix 30 and the filaments 32 and webs 34.

[0043] FIG. 9 depicts a second example of a cable jacket 12 produced using the tip insert 52 of FIGS. 6A and 6B. As mentioned above, the tip insert 52 has a head portion 66 designed to contact the tapered channel 64 of the extrusion die 50. Thus, as shown in FIG. 9, the filaments 32 are not connected by webs 34. Instead, the outer matrix 30 extends substantially or fully around and between the filaments 32. FIG. 9 also shows that the filaments 32 may still in part form the inner surface 14 of the cable jacket 12. In the example cable jacket 12 of FIG. 9, the filaments 32 are formed from polycarbonate and have a generally round and symmetrical cross-sectional area.

[0044] FIGS. 10-12 depict examples of a cable jacket 12 produced using a tip insert 52 according to embodiments of the present disclosure. In FIGS. 10-12, the second polymer composition of the filaments 32 was changed in each example, and the ratio of second polymer composition to the first polymer composition was increased. Starting with FIG. 10, the second polymer composition comprised polycarbonate, and the filaments 32 had the smallest ratio of the second polymer composition to the first polymer composition of the three examples. As can be seen in FIG. 10, the filaments 32 have a teardrop shape, but the filament 32 has a generally symmetrical cross-sectional area. In FIG. 11, the second polymer composition comprised liquid crystal polymer, andAtty Dkt No. : HI24-119PCTthe filaments 32 had a higher ratio of the second polymer composition to the first polymer composition than the first example in FIG. 10. As can be seen in FIG. 11, the filaments 32 do not have a symmetrical cross-sectional area, and the filaments 32 define a sawtooth-type shape. Finally, in FIG. 12, the second polymer composition comprised co-polyester, and the filaments 32 had the highest ratio of the second polymer composition to the first polymer composition as compared to the examples in FIGS. 10 and 11. As can be seen in FIG. 12, the filaments were generally round in shape and had a substantially symmetrical cross-sectional area. FIGS. 10-12 demonstrate that different polymers can be co-extruded together to produce a variety of different cable jacket 12 cross-sections in terms of the amount of the second polymer composition, the shape of the filaments 32, and the size of the filaments 32 while still providing good interfacial interaction between the outer matrix 30 and the filaments 32.

[0045] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein, the article "a" is intended to include one or more than one component or element, and is not intended to be construed as meaning only one.

[0046] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the disclosed embodiments. Since modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments should be construed to include everything within the scope of the appended claims and their equivalents.

Claims

Atty Dkt No. : HI24-119PCTWhat is claimed is:

1. An optical fiber cable, comprising:a cable jacket having an inner surface and an outer surface, the inner surface defining a central bore extending along a longitudinal axis of the optical fiber cable and the outer surface defining an outermost surface of the optical fiber cable;at least one optical fiber disposed within the central bore;wherein the cable jacket comprises an outer matrix comprising a first polymer composition and a plurality of filaments comprising a second polymer composition embedded in the outer matrix.

2. The optical fiber cable of claim 1, wherein the plurality of filaments extends from the inner surface of the cable jacket to a first depth, the first depth being from 10% to 80% of a thickness of the cable jacket measured as a radial distance from the inner surface to the outer surface.

3. The optical fiber cable of claim 2, wherein each filament of the plurality of filaments comprises a maximum width measured transverse to the first depth and wherein a combined width of all of the maximum widths of the plurality of filaments is from 30% to 70% of a circumference of the cable jacket at a depth at which the maximum width is measured.

4. The optical fiber cable of claim 2, further comprising a plurality of webs, wherein adjacent filaments of the plurality of filaments are connected by a web of the plurality of webs.

5. The optical fiber cable of claim 4, wherein the plurality of webs extend from the inner surface of the cable jacket to a second depth, the second depth being from 10% to 90% of the first depth.Atty Dkt No. : HI24-119PCT6. The optical fiber cable of claim 1, wherein the second polymer composition comprises at least at least one of a higher Young’s modulus, a higher tensile strength, or a lower coefficient of thermal expansion as compared to the first polymer composition.

7. The optical fiber cable of claim 1, wherein the first polymer composition and the second polymer composition are each selected from a group consisting of polyolefins, polyvinylchloride, polystyrene, acrylonitrile butadiene styrene, styrene-acrylonitrile, styrene-ethylene-butylene-styrene, and technical thermoplastics.

8. The optical fiber cable of claim 1, wherein at least one of the first polymer composition or the second polymer composition further comprises a coupling agent.

9. The optical fiber cable of claim 1, wherein a ratio of the second polymer composition to the first polymer composition is in a range from 0.05 to 0.80.

10. The optical fiber cable of claim 1, wherein the plurality of filaments comprises from four filaments to fifteen filaments.

11. A method of preparing an optical fiber cable, comprising:co-extruding a first polymer composition and a second polymer composition through an extrusion die comprising a tip insert to form an optical fiber cable jacket around a cable core, the cable core comprising at least one optical fiber;wherein the tip insert comprises a plurality of grooves configured to form the second polymer composition into a plurality of filaments embedded in an outer matrix of the first polymer composition, the outer matrix defining an outermost surface of the optical fiber cable.Atty Dkt No. : HI24-119PCT12. The method of claim 11, wherein the co-extruding further comprises feeding the first polymer composition at a first rate and feeding the second polymer composition at a second rate, wherein the first rate is different from the second rate.

13. The method of claim 11, wherein the tip insert comprises a longitudinal axis, wherein the cable core extends through the extrusion die along the longitudinal axis, wherein the plurality of grooves wind at least partially around the longitudinal axis, and wherein the co-extruding further comprises flowing the first polymer composition and the second polymer composition through the plurality of grooves winding at least partially around the longitudinal axis.

14. The method of claim 13, wherein the plurality of grooves wind up to 180° around the longitudinal axis.

15. The method of claim 11 , wherein the extrusion die comprises an inlet to receive the first polymer composition and the second polymer composition, an outlet through which the cable core with the co-extruded cable jacket emerges, and a tapered channel between the inlet and the outlet and wherein the method further comprises inserting the tip insert into the extrusion die such that a head portion of the tip insert containing the plurality of grooves contacts the tapered channel.

16. The method of claim 15, wherein the plurality of filaments are discrete elements embedded in the outer matrix such that the first polymer composition separates adjacent filaments of the plurality of filaments.

17. The method of claim 11, wherein the extrusion die comprises an inlet to receive the first polymer composition and the second polymer composition, an outlet through which the cable core with the co-extruded cable jacket emerges, and a tapered channel between the inlet and the outlet and wherein the method further comprises inserting the tip insert into the extrusion dieAtty Dkt No. : HI24-119PCTsuch that a head portion of the tip insert containing the plurality of grooves is spaced apart from the tapered channel.

18. The method of claim 17, wherein adjacent filaments of the plurality of filaments are connected by a web.

19. The method of claim 11, wherein the second polymer composition comprises at least at least one of a higher Young’s modulus, a higher tensile strength, or a lower coefficient of thermal expansion as compared to the first polymer composition.

20. The method of claim 19, wherein the first polymer composition and the second polymer composition are selected from a group consisting of polyolefins, polyvinylchloride, polystyrene, acrylonitrile butadiene styrene, styrene-acrylonitrile, styrene-ethylene-butylene-styrene, and technical thermoplastics.

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