Patent Description:
The present invention is related to optical fiber cables and more particularly to optical fiber cables that have a buffer tube coupled to an armor layer to prevent shrinkage of the buffer tube during temperature cycling. Optical fiber cables are used to transmit data over distance. Generally, large distribution cables that carry a multitude of optical fibers from a hub are sub-divided at network nodes, which are further sub-divided, e.g., to the premises of individual subscribers. The cables making up these subdivisions are carried through the distribution network on utility poles or are buried underground. In either case, the cables may be exposed to temperature extremes that the cable must be able to withstand in order to reliability transmit data in the distribution network.

<CIT>discloses an armored fiber optic cable comprising an armored corrugated jacket surrounding an inner jacket. <CIT> provides additional prior art.

The invention provides an optical fiber cable according to claim <NUM>.

Further, the invention provides a method of preparing an optical fiber cable according to claim <NUM>.

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.

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.

Referring generally to the figures, various embodiments of an optical fiber cable are disclosed in which an armor layer is coupled to a cable core using a water-blocking adhesive, such as a superabsorbent polymer (SAP) hot melt. In an optical fiber cable, the buffer tube has a relatively high coefficient of thermal expansion as compared to the jacket structure (i.e., cable jacket, strength members, and armor layer) of the optical fiber cable, which means that the buffer tube will contract more extensively than the jacket structure during temperature cycling. In certain situations, such as when an end of the optical fiber cable is terminated in a splice enclosure, the thermal contraction of the buffer tube may cause the optical fibers to be pulled out of the splice enclosure. As disclosed herein, the buffer tube in an optical fiber cable is coupled to the jacket structure, which has a much lower CTE, so that the shrinkage of the buffer tube is limited. These aspects and advantages will be discussed in greater detail with respect to the following exemplary embodiments. These embodiments are provided for the purpose of illustration and should not be read as limiting.

<FIG> depicts an embodiment of an optical fiber cable <NUM>. The optical fiber cable <NUM> includes a cable jacket <NUM> having an inner surface <NUM> and an outer surface <NUM>. The outer surface <NUM> defines an outermost surface of the optical fiber cable <NUM>. The inner surface <NUM> of the cable jacket <NUM> defines a longitudinal bore <NUM>. Disposed within the bore <NUM> are optical communication elements. In the embodiment depicted, the optical communication elements include a stack <NUM> of optical fiber ribbons <NUM>. Each optical fiber ribbon <NUM> includes a plurality of optical fibers <NUM> arranged in a planar configuration and bound together, e.g., with a matrix material. In embodiments, the stack <NUM> includes, e.g., from one to thirty-two optical fiber ribbons <NUM>. In embodiments, each optical fiber ribbon <NUM> includes from four to thirty-six optical fibers <NUM>. Thus, in embodiments, the optical fiber cable <NUM> may include, e.g., anywhere from four to <NUM> optical fibers <NUM> in the bore <NUM>. In other embodiments, the optical fibers <NUM> may be in a loose-tube configuration or arranged in a plurality of buffer tubes, e.g., wound around a central strength member.

In the embodiment depicted in <FIG>, the stack <NUM> of optical fiber ribbons <NUM> are contained in a buffer tube <NUM>. The buffer tube <NUM> has an interior surface <NUM> and an exterior surface <NUM>. In embodiments, disposed on the interior surface <NUM> and/or wrapped around the stack <NUM> is a water barrier layer <NUM> that prevents or limits water from contacting the optical fiber ribbons <NUM>. In embodiments, the water barrier layer <NUM> is a water-blocking tape, e.g., that absorbs water and/or swells when contacted with water. In other embodiments, the water barrier layer <NUM> is an SAP powder applied to the exterior of the stack <NUM> and/or the inner surface <NUM> of the buffer tube <NUM>. As used herein, all of the components from the buffer tube <NUM> inward are referred to as the "cable core" <NUM>.

As shown in <FIG>, a layer or strips of water-blocking adhesive <NUM> are applied along at least a portion of the cable <NUM>. In the embodiment depicted in <FIG>, the water-blocking adhesive <NUM> adheres an armor layer <NUM> to the buffer tube <NUM>. The armor layer <NUM> is corrugated. In embodiments, the corrugated armor layer <NUM> includes twelve to fourteen corrugations <NUM> per inch, and in embodiments, the corrugations <NUM> each have a corrugation height of twenty-five to thirty mils. In embodiments, the water-blocking adhesive <NUM> is foamed, which enhances the volume-filling effect of the water-blocking adhesive <NUM> (e.g., especially into the corrugations <NUM> of the armor layer <NUM>). The optical fiber cable <NUM> may include other components, such as longitudinal strength members <NUM> and/or preferential access features <NUM>, such as a ripcord. The components of the optical fiber cable <NUM> outside of the water-blocking adhesive <NUM> (e.g., the cable jacket <NUM>, the armor layer <NUM>, and the strength members <NUM> in the embodiment of <FIG>) are referred to as the "jacket structure" <NUM>. The components of the jacket structure <NUM> are closely coupled (i.e., the cable jacket <NUM> is extruded around the armor layer <NUM> and the strength members <NUM> are embedded in the cable jacket <NUM>), which means that these components contract during thermal cycling effectively the same amount.

As disclosed herein, the water-blocking adhesive <NUM> helps prevent the shrinkage of the buffer tube <NUM> when the optical fiber cable <NUM> is exposed to temperature cycling by coupling the buffer tube <NUM> to the jacket structure <NUM>. In a typical installation, an optical fiber cable <NUM> is spliced at various locations in the cable distribution network. These splices are often contained in an enclosure, which may be suspended in the air from a utility pole or buried underground. In any case, the splice enclosure may be subject to extreme temperatures. In particular, extremely cold temperatures may cause the buffer tube <NUM> to contract, which in some circumstances, may pull the ribbons <NUM> from the splice enclosure. The contraction of the buffer tube <NUM> is attributed to the relatively high coefficient of thermal expansion (CTE) of the buffer tube material, which may be at least one of high density polyethylene (HDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene difluoride (PVDF), polyamides, polyesters, or polycarbonate and their copolymers. In general, the CTE of the buffer tube material is between about <NUM>/mK to <NUM>/mK. As shown in Table <NUM>, below, the CTE of the buffer tube material can cause significant shrink back forces to be generated.

In Table <NUM>, the area is the cross-sectional area of the buffer tube <NUM> between the inner surface <NUM> and the outer surface <NUM>. The shrink back forces in Table <NUM> correspond to the predicted maximum axial force extrapolated from measurements of buffer tube shrink back stress. To perform the measurements, sections of buffer tubes of a variety of sizes, jacketed and unjacketed, dry-filled, and gel-filled were held at a constant length while exposing the buffer tube to temperatures of -<NUM>. The maximum stress measured among all the sections was <NUM> MPa. Thus, the shrink back forces in Table <NUM> equal the measured area multiplied by the maximum measured stress.

In the optical fiber cable <NUM>, the jacket structure <NUM> (i.e., cable jacket <NUM>, armor layer <NUM>, and strength members <NUM>) has an effective CTE of about <NUM>/mK to about <NUM>/mK. Accordingly, when exposed to temperature cycling, the jacket structure <NUM> shrinks much less than the buffer tube <NUM>. Thus, as disclosed herein, the water-blocking adhesive <NUM> adheres the buffer tube <NUM> and to the armor layer <NUM> so that the buffer tube <NUM> is prevented from shrinking back when exposed to temperature cycling. Further, in embodiments in which the water-blocking adhesive <NUM> extends in a layer circumferentially around the cable core <NUM>, the armor layer <NUM> exerts radial compressive stresses on the cable core <NUM>, which also helps prevent the buffer tube from shrinking back.

Besides the adhesive bonding and radial compressive stresses between the buffer tube <NUM> and the armor layer <NUM>, a mechanical interlock may also be formed when the armor layer <NUM> includes corrugations. As shown in the cross-section of <FIG>, the water-blocking adhesive <NUM> fills the corrugations of the armor layer <NUM>, which also prevents the buffer tube <NUM> from shrinking within the armor layer <NUM>. In embodiments, the water-blocking adhesive <NUM> fills a distance d between the cable core <NUM> and armor layer <NUM> of up to <NUM>. It is noted that the depiction shown in <FIG> is not to scale, and the distance between the cable core <NUM> and armor layer <NUM> is exaggerated relative to the dimensions of the other components depicted in <FIG>.

Further, in the comparative example, not covered by scope of the claims, shown in <FIG>, a layer of water-blocking tape or yarns <NUM> (shown in dashed lines) is embedded in an adhesive <NUM> that may not have water-blocking capabilities. In particular, the water-blocking tape or yarns <NUM> may be wrapped around the outer surface <NUM> of the buffer tube <NUM>. Thereafter, the adhesive <NUM> is applied, in particular in liquid form, which permeates that water-blocking tape or yarns <NUM>, creating a coupling between the buffer tube <NUM> and the water-blocking tape or yarns <NUM>. In this way, the combination of the water-blocking tape or yarns <NUM> and adhesive <NUM> fulfills the functions of the water-blocking adhesive <NUM> of the embodiment shown in <FIG>.

Advantageously, an optical fiber cable <NUM> having a water-blocking adhesive <NUM> ( or an adhesive <NUM> with embedded water-blocking tapes or yarns <NUM>) filling at least a portion of the space between the buffer tube <NUM> and armor layer <NUM> along the longitudinal axis of the optical fiber cable <NUM> experiences significantly less buffer tube shrinkage as compared to conventional optical fiber cables. The shrinkage of conventional optical fiber cables as compared to embodiments of the disclosed optical fiber cable <NUM> was investigated. A six-meter length of a conventional optical fiber cable and of the presently disclosed optical fiber cable <NUM> were each exposed to following conditions: <NUM> cycles of -<NUM> to -<NUM>, aging for <NUM> week at <NUM>, and <NUM> cycles of -<NUM> to <NUM>. After exposure to these conditions, the conventional optical fiber cable experienced a buffer tube shrinkage of <NUM>% or <NUM>. The disclosed optical fiber cable <NUM> experienced a buffer tube shrinkage of only <NUM>% or <NUM>. In embodiments, the optical fiber cable <NUM> experiences a buffer tube shrinkage of less than <NUM> regardless of length. In further embodiments, the optical fiber cable <NUM> experiences a buffer tube shrinkage of less than <NUM> regardless of length, and in still other embodiments, the optical fiber cable <NUM> experiences a buffer tube shrinkage of less than <NUM> regardless of length.

Conventional optical fiber cables often are installed at splice enclosures with slack coils, which provide coupling of the cable components to prevent axial motion of the components relative to each other. However, besides being a waste of optical fiber cable, the slack coils are generally not considered aesthetically pleasing in an installation. Advantageously, embodiments of the optical fiber cable <NUM> are able to be installed at splice enclosures without requiring the use of slack coils.

In another embodiment, the optical fiber cable <NUM> is a dielectric cable that does not contain an armor layer <NUM>. In such an embodiment, the buffer tube <NUM> is coupled to the jacket structure <NUM> with the water-blocking adhesive <NUM> (or an adhesive <NUM> with embedded water-blocking tape or yarns <NUM>, not covered by the scope of the claims). In such embodiments, the water-blocking adhesive <NUM> (or adhesive <NUM>, not covered by scope of the claims) may adhere to the inner surface <NUM> of the cable jacket <NUM> and to the outer surface <NUM> of the buffer tube <NUM>. In such an embodiment, the jacket structure <NUM> may have a much lower effective CTE than the buffer tube <NUM> by virtue of the embedded strength members <NUM>, such as glass-reinforced plastic rods or strengthening yarns (e.g., yarns made of aramid, glass, carbon, and/or cotton fibers).

<FIG> depicts another embodiment of an optical fiber ribbon <NUM> in which the stacks <NUM> having optical fiber ribbons <NUM> with different numbers of optical fibers <NUM> contained in each ribbon <NUM>. In particular, the stacks <NUM> include an upper and lower section having less optical fiber <NUM> than a middle section. In embodiments, the upper and lower sections each include four ribbons <NUM> of twelve optical fibers <NUM> and the middle section includes eight ribbons <NUM> of twenty-four optical fibers <NUM> for a total of <NUM> optical fibers <NUM> per stack <NUM>. The ribbons <NUM> are held in the stack <NUM> with a wrap <NUM>. In the embodiment of <FIG>, the optical fiber cable <NUM> includes three stacks <NUM> for a total of <NUM> optical fibers <NUM>, but in other embodiments, the optical fiber cable <NUM> may include, e.g., up to twelve stacks <NUM> for a total of <NUM> optical fibers <NUM> in the optical fiber cable <NUM>. The stacks <NUM> are contained in the central bore <NUM> of the optical fiber cable <NUM> and held in place by foamed thermoplastic elastomer (TPE) <NUM> disposed within the central bore <NUM> around the stacks <NUM>. In embodiments, the water-blocking adhesive <NUM> (or adhesive <NUM> with embedded water-blocking tape or yarns <NUM>, not covered by scope of the claims) is applied around the foamed TPE <NUM> and adheres the foamed TPE <NUM> to the inner surface <NUM> of the cable jacket <NUM>. In embodiments, an armor layer (not shown) may also be provided on the inner surface <NUM> of the cable jacket <NUM>, and the water-blocking adhesive <NUM> (or adhesive <NUM>, not covered by scope of the claims) may adhere the foamed TPE <NUM> to the armor layer.

<FIG> provides a schematic depiction of a processing line <NUM> for applying the water-blocking adhesive <NUM> to the cable core <NUM>. As shown in <FIG>, a length of cable core <NUM> is provided on a first payoff reel <NUM>, and a spool of metal tape for the armor layer <NUM> is provided on a second payoff reel <NUM>. Both the cable core <NUM> and the armor layer <NUM> are fed onto the processing line <NUM> so that the armor layer <NUM> can be wrapped around the cable core <NUM>. In an embodiment, the water-blocking adhesive <NUM> is applied to the armor layer <NUM> prior to being wrapped around the cable core <NUM>. In an embodiment, the metal tape is provided in an uncorrugated roll, and the flat metal tape is passed through corrugating rollers prior to beign wrapped around the cable core <NUM>. Optionally, after any corrugations are formed into the armor layer <NUM> and as shown in <FIG>, the water-blocking adhesive <NUM> can be applied to the armor layer <NUM> via a first nozzle <NUM>. The cable core <NUM> and the armor layer <NUM> (with or without water-blocking adhesive <NUM>) are fed into a first former <NUM>. The first former <NUM> bends the armor layer <NUM> into a U-shape around the cable core <NUM>. Thereafter, the cable core <NUM> and armor layer <NUM> pass under a second nozzle <NUM>. The second nozzle <NUM> applies a strip of water-blocking adhesive <NUM> to the cable core <NUM>. In embodiments, the water-blocking adhesive <NUM> is applied intermittently or discontinuously along the length of the cable core <NUM>. Further, the nozzles <NUM>, <NUM> can be used in conjunction with a mechanical or air spreading device to provide a uniform coating of the water-blocking adhesive <NUM>.

After applying the water-blocking adhesive <NUM>, the cable core <NUM> and armor layer <NUM> pass through a second former <NUM> that closes the armor layer <NUM> around the cable core <NUM>. The closing of the armor layer <NUM> around the cable core <NUM> cause the water-blocking adhesive <NUM> to spread partially or totally around the circumference of the cable core <NUM>. After exiting the second former <NUM>, the cable core <NUM> and armor layer <NUM> continue to downstream processing, such as extruding of the cable jacket <NUM> around the armor layer <NUM>.

<FIG> provides a detail view of the cable core <NUM> and armor layer <NUM> in the section of the processing line <NUM> between the first former <NUM> and the second former <NUM>. As can be seen, the second nozzle <NUM> deposits the water-blocking adhesive <NUM> onto the cable core <NUM>. The armor layer <NUM>, which has been formed into a U-shape, acts as a trough to catch water-blocking adhesive <NUM> that flows around the cable core <NUM>.

In some embodiments, the water-blocking adhesive <NUM> used are physically setting thermoplastic materials. For example, these may include commercially available water-swellable hot melt adhesives such as HM002 and HM008B (available from Stewart Superabsorbents, Hickory, NC), Technomelt AS <NUM> (also known as Macromelt Q <NUM> available from Henkel Corp. , Madison Heights, MI), and NW1117 and NW1120B (Hydrolock® super absorbent thermoplastic available from H. Fuller Company, Vadnais Heights, MN).

Additionally, a variety of exemplary compositions are provided in the following paragraphs. According to one embodiment, the water-blocking adhesive <NUM> includes essentially three components that are mixed homogenously. The first component is a water-insoluble component containing at least one water-insoluble polymer or copolymer and at least one other substantially water-insoluble resin. For example, the first component can be selected from polyamides, copolyamides, polyaminoamides, polyesters, polyacrylates, polymethacrylates, polyolefins and ethylene/vinyl acetate (EVA) copolymers. Further the first component can be mixtures of one or more of the foregoing polymers. The second component is a water-soluble or water-dispersible component containing at least one water-soluble or water-dispersible oligomer and/or polymer or copolymer. For example, the second component can be selected from polyethylene glycols with molecular weights of <NUM> to <NUM>,<NUM>, polyvinyl methyl ether, polyvinyl pyrrolidone, copolymers of vinyl methyl ether or vinyl pyrrolidone, polyvinyl alcohols, water-soluble or water-dispersible polyesters or copolyesters, and water-soluble or water-dispersible acrylate polymers.

The third component is a water-swellable component (e.g., a superabsorbent polymer) consisting of a water-swellable homopolymer or copolymer. For example, the third component can be selected from any homopolymers and/or copolymers which, as hydrophilic materials, are capable of absorbing and retaining large amounts of water, even under pressure, without immediately dissolving in the water, including, for example, graft copolymers of starch or cellulose with acrylonitrile, acrylic acid or acrylamide, carboxymethyl cellulose, maleic anhydride/poly-α-olefin copolymers, polyacrylamide, polyacrylic acid and salts of polyacrylic acid, and, optionally, copolymers of acrylic acid or acrylamide with acrylate esters. In embodiments, other suitable the third components include homopolymers and copolymers of acrylic acid or methacrylic acid, acrylonitrile or methacrylonitrile, acrylamide or methacrylamide, vinyl acetate, vinyl pyrrolidone, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, vinyl sulfonic acid or hydroxyalkyl esters of such acids, <NUM> to <NUM>% by weight of the acid groups being neutralized with alkali or ammonium groups and these polymers/copolymers are crosslinked by means of polyfunctional compounds. Graft copolymers of starch or cellulose with the above comonomers can also be used in certain embodiments. Still other suitable superabsorbent polymers include crosslinked acrylate polymers, crosslinked products of vinyl alcohol-acrylate copolymers, crosslinked products of polyvinyl alcohols grafted with maleic anhydride, cross-linked products of acrylate-methacrylate copolymers, crosslinked saponification products of methyl acrylate-vinyl acetate copolymers, crosslinked products of starch acrylate graft copolymers, crosslinked saponification products of starch acrylonitrile graft copolymers, crosslinked products of carboxymethyl cellulose polymers, and crosslinked products of isobutylene-maleic anhydride copolymers.

In some embodiments, the water-blocking adhesive <NUM> also includes a tackifying resin or resins to increase the tackiness of the melt. In particular embodiments, various colophony derivatives, i.e., in particular the resin esters of abietic acid, are used for the tackifying resin; although, in other embodiments, other polyterpenes and terpene/phenol resins are used. Other colophony derivatives include colophony esters of various mono- and poly-functional alcohols. Additionally, suitable tackifying resins include wood rosin, tall oil rosin, tall oil derivatives, gum rosin, rosin ester resins, natural terpenes, synthetic terpenes, and petroleum based tackifying agents, including, e.g., aliphatic, aromatic and mixed aliphatic-aromatic petroleum based tackifying resins. Still further, other suitable tackifying resins include, e.g., alpha-methyl styrene resins, branched and unbranched C<NUM> resins, C<NUM> resins and C<NUM> resins, styrenic and hydrogenated modifications thereof, and combinations thereof.

In particular embodiments, the water-blocking adhesive <NUM> contains the following components: <NUM> to <NUM>% by weight of resin esters or terpene/phenol resins; <NUM> to <NUM>% by weight of thermoplastic copolymer, more particularly ethylene/vinyl acetate copolymer; <NUM> to <NUM>% by weight of acrylate copolymers; <NUM> to <NUM>% by weight of polyethylene glycols; <NUM> to <NUM>% by weight of polyvinyl ethyl ethers, water-soluble or water-dispersible acrylate polymers or water-soluble or water-dispersible copolyesters; <NUM> to <NUM>% by weight of powder-form polyacrylic acid salt, polyacrylamide or similar powdered superabsorbent polymer; and <NUM> to <NUM>% by weight of stabilizers, such as, for example, antioxidants based on sterically hindered phenols, that enhance the temperature stability of the compositions.

In other particular embodiments, the water-blocking adhesive <NUM> contains the following components: <NUM> to <NUM>% by weight of resin esters, terpene/phenol resins or the like; <NUM> to <NUM>% by weight of thermoplastic polymer or copolymer, more particularly ethylene/vinyl acetate copolymer; <NUM> to <NUM>% by weight of polyethylene glycols: <NUM> to <NUM>% by weight of a powdered superabsorbent polymer, more particularly polyacrylic acid salt; <NUM> to <NUM>% by weight of a stabilizer; and <NUM> to <NUM>% by weight of waxes, more particularly ethylene bis-stearamide.

In another embodiment of a suitable water-blocking adhesive <NUM> composition, the water-blocking adhesive <NUM> is comprised of <NUM> to <NUM>% by weight of at least one tackifying resin, <NUM> to <NUM>% by weight of at least one water-dispersible EVA wax, <NUM> to <NUM>% by weight of at least one ethylene/acrylic acid copolymer, <NUM> to <NUM>% by weight of at least one water-soluble homopolymer or copolymer, and <NUM> to <NUM>% by weight of at least one powdered superabsorbent polymer having an average particle size of less than <NUM> microns.

The tackifying resins can be selected from the same group of tackifying resins discussed above. The water-dispersible EVA waxes are selected from polyethylene waxes based on an ethylene/vinyl acetate copolymer having a vinyl acetate content of up to <NUM>% and molecular weights of between <NUM> and about <NUM>,<NUM>. Flexibilizing ethylene copolymers, particularly ethylene/alkyl acrylate copolymers having an alkyl acrylate proportion of <NUM> to <NUM>% by weight, are suitable as hydrophobic matrix components for binding the powdered superabsorbent polymer. Longer-chain alkyl acrylic esters are particularly suitable as comonomers in this respect, particularly the C4-C12 alkyl acrylates.

The water-soluble homopolymer or copolymer can include polyethylene glycol, ethylene oxide/propylene oxide copolymers (either as block copolymers or as random copolymers having a predominate proportion of ethylene oxide), polyvinyl methyl ether, polyvinyl pyrrolidone, polyvinyl alcohol, and copolymers of such monomers with other olefinically unsaturated monomers. In embodiments, these water-soluble polymers have molecular weights of between <NUM> and <NUM>,<NUM>, they may be liquid at room temperature, or they may be solid and waxy in cases where higher molecular weights are used. Suitable powdered superabsorbsent polymers include those listed above.

In still another embodiment, the water-blocking adhesive <NUM> is comprised of <NUM>% to <NUM>% by weight of a block copolymer, <NUM>% to <NUM>% by weight of a powdered superabsorbent polymer, <NUM>% to <NUM>% by weight of a plasticizing oil, and optionally <NUM>% to <NUM>% by weight of a surfactant. Suitable block copolymers include linear and radial copolymer structures having the formula (A-B)x or A-B-A, where block A is a polyvinylarene block, block B is a poly(monoalkenyl) block, and x is an integer of at least <NUM>. Suitable block A polyvinylarenes include, e.g., polystyrene, polyalpha-methylstyrene, polyvinyltoluene and combinations thereof. Suitable B blocks include, e.g., conjugated diene elastomers including, e.g., polybutadiene and polyisoprene, hydrogenated elastomers, ethylene/butylene (hydrogenated butadiene) and ethylene/propylene (hydrogenated isoprene), and combinations and mixtures thereof. Suitable powdered superabsorbent polymers include those listed above.

Suitable plasticizing oils include, e.g., hydrocarbon oils low in aromatic content, mineral oil. In a particular embodiment, the plasticizing oils are paraffinic or naphthenic. In some embodiments, the water-blocking adhesive <NUM> can also include tackifying agents, such as those listed above, up to <NUM>% by weight.

In an embodiment, the water-blocking adhesive <NUM> includes at least one of sodium or potassium sodium acrylate or acrylamide copolymers, cross-linked carboxymethylcellulose, ethylene maleic anhydride copolymers, cross-linked polyethylene oxide, polyvinyl alcohol copolymers, or starch-grafted copolymers of polyacrylonitrile.

Referring to each of the above described water-blocking adhesive <NUM> compositions, in embodiments, the average particle size of the superabsorbent polymer powders is between <NUM> micron and <NUM> microns. Broadly, in embodiments, the average particle size of the superabsorbent polymer powder is less than or equal to <NUM> microns. In other embodiments, the average particle size of the superabsorbent polymer powders is less than or equal to <NUM> microns. In still other embodiments, the average particle size of the superabsorbent polymer powders is less than or equal to <NUM> microns, and in yet other embodiments, the average particle size of the superabsorbent polymer powders is less than or equal to <NUM> microns. Further, in embodiments, the average particle size of the superabsorbent polymer powders is greater than <NUM> micron, and in other embodiments, the average particle size of the superabsorbent polymer powders is greater than <NUM> microns. Additionally, in embodiments, less than <NUM>% of the superabsorbent polymer powder particles have a maximum outer dimension ≥ <NUM> microns. In still other embodiments, less than <NUM>% of the superabsorbent polymer powder particles have a maximum outer dimension ≥ <NUM> microns, and in yet other embodiments, less than <NUM>% of the superabsorbent polymer powder particles have a maximum outer dimension ≥ <NUM> microns. Further, in embodiments, the superabsorbent polymer powders have particles that are spherical in shape.

Claim 1:
An optical fiber cable (<NUM>) comprising:
a cable jacket (<NUM>) comprising a jacket inner surface (<NUM>) and a jacket outer surface (<NUM>), the jacket inner surface (<NUM>) defining a central bore (<NUM>) along a longitudinal axis of the optical fiber cable (<NUM>) and the jacket outer surface (<NUM>) defining an outermost surface of the optical fiber cable (<NUM>);
at least one optical fiber (<NUM>) disposed within the central bore (<NUM>);
a buffer tube (<NUM>) disposed within the central bore (<NUM>) and surrounding the at least one optical fiber (<NUM>) along the longitudinal axis, the buffer tube (<NUM>) comprising a buffer tube inner surface (<NUM>) and a buffer tube outer surface (<NUM>);
an armor layer (<NUM>) disposed between the jacket inner surface (<NUM>) and the buffer tube outer surface (<NUM>);
a water-blocking adhesive (<NUM>) disposed between the armor layer (<NUM>) and the buffer tube outer surface (<NUM>);
wherein the water-blocking adhesive (<NUM>) extends along at least a portion of the longitudinal axis of the optical fiber cable (<NUM>) and at least partially around a circumference of the buffer tube (<NUM>);
wherein the armor layer (<NUM>) comprises a plurality of corrugations (<NUM>);
wherein the water-blocking adhesive (<NUM>) adheres to the armor layer (<NUM>) and to the buffer tube outer surface (<NUM>) and wherein the water-blocking adhesive (<NUM>) adheres to the plurality of the corrugations (<NUM>) to create a mechanical interlock between the buffer tube (<NUM>) and the armor layer (<NUM>),
characterised in that the water-blocking adhesive (<NUM>) is a superabsorbent, water-swellable hotmelt.