STABILIZATION LAYERS IN FLEXIBLE PROFILE/CONDUIT PROCESSING AND APPLICATIONS

A conduit including a first concentric layer and a second concentric layer that are coextruded, the first concentric layer having a higher melt viscosity than the second concentric layer, and the first concentric layer being of a thickness of at least 3% of a combined thickness of the first and second concentric layers, is provided. Conduits further including third and fourth concentric layers and conduits further including at least one microduct within a lumen defined by the first concentric layer are further provided.

TECHNICAL FIELD

The present disclosure relates to conduits. More particularly, the disclosure relates to flexible, multi-layer polymeric conduits.

BACKGROUND

The flexible pipe and conduit manufacturing industry predominantly uses polyolefins in pipes and conduits due the versatility and case of processability of polyolefins. However, certain applications present environmentally challenging circumstances beyond the material capacity of polyolefins. Applications that may be beyond the material capacity of polyolefins include the trenchless installation of communication and power lines along large oil transport pipes for system monitoring.

Trenchless methods, like Horizontal Direction Drilling (“HDD”), are utilized in infrastructure installation projects for which open trenching is not feasible, including, for example, crossing under busy highways, and under rivers. Trenchless installations present large abrasion forces and point loads that may cause the failure of standard ducts made from high-density polyethylene (“HDPE”). One solution involves the use of stainless steel tubes. However, stainless steel tubes are rigid, and require additional tools for straightening, which reduces the pace of the installation process. Further, metallic ducts may interfere with some telecommunication applications, such as optical fiber sensing.

For environments in which metallic ducts create problems, engineering polymers may be used to prepare ducts. However, converting such engineering polymers into pipes and conduits may be challenging due to the intrinsic physical properties of the polymers, including the hypersensitivity of the polymers to variables such as temperature, shear, and moisture, which may compromise processability and dimensional uniformity. Engineering polymers may consequently fail to provide uniform wall thicknesses.

Thus, there is a need for conduits that may resist large abrasion forces and point loads. Further, there is a need for conduits that have low-temperature toughness. Further, there is a need for conduits with excellent compressive recovery that may recover 80% of inner diameter to enable cable install even when flattened. Further, there is a need for conduits with insulative properties.

There is a need to employ various functional polymers, beyond polyolefins, in conduits such that various, technically challenging polymers may be reliably co-extruded with desirable dimensional integrity.

SUMMARY

In an example, the present disclosure provides a conduit. The conduit includes a first concentric layer, including a first outer surface and defining a lumen extending therethrough. The conduit further includes a second concentric layer at least partially enveloping the first outer surface. The first concentric layer and the second concentric layer are coextruded. A first melt viscosity of the first concentric layer is higher than a second melt viscosity of the second concentric layer. A thickness of the first concentric layer is at least 3% of a combined thickness of the first and second concentric layers of the conduit.

In another example, the first melt viscosity may be at least ten times higher than the second melt viscosity.

In yet another example, the first concentric layer may include a polyamide including PA6, PA11, PA12, PA46, PA66, or combinations thereof.

In yet another example, the first concentric layer may include PA12 and the second concentric layer may include TPU.

In yet another example, the first concentric layer may include HDPE and the second concentric layer may include TPU.

In yet another example, the first concentric layer may include PP and the second concentric layer may include TPE.

In yet another example, the thickness of the first concentric layer may be at least 10% of the combined thickness.

In yet another example, the thickness of the first concentric layer may be at least 20% of the combined thickness.

In yet another example, the thickness of the first concentric layer may be at least 30% of the combined thickness.

In yet another example, the second concentric layer may be in direct contact with the first concentric layer.

In yet another example, the conduit may be without a tie layer between the first concentric layer and the second concentric layer.

In yet another example, the conduit may further include a third concentric layer including a third outer surface, the third concentric layer at least partially enveloping a second outer surface of the second concentric layer. The conduit may further include a fourth concentric layer at least partially enveloping the third concentric layer. The third concentric layer and the fourth concentric layer may be coextruded. A third melt viscosity of the third concentric layer may be higher than a fourth melt viscosity of the fourth concentric layer. A combined two-layer thickness of the first concentric layer and the third concentric layer may be at least 3% of a combined four-layer thickness of the first, second, third, and fourth concentric layers of the conduit.

In yet another example, the third melt viscosity may be at least ten times higher than the fourth melt viscosity.

In yet another example, the third concentric layer may include a polyamide including PA6, PA11, PA12, PA46, PA66, or combinations thereof.

In yet another example, the third concentric layer may include PA12 and the fourth concentric layer may include TPU.

In yet another example, the third concentric layer may include HDPE and the fourth concentric layer may include TPU.

In yet another example, the third concentric layer may include PP and the fourth concentric layer may include TPE.

In yet another example, the combined two-layer thickness may be at least 10% of the combined four-layer thickness.

In yet another example, the combined two-layer thickness may be at least 20% of the combined four-layer thickness.

In yet another example, the combined two-layer thickness may be at least 30% of the combined four-layer thickness.

In yet another example, the fourth concentric layer may be in direct contact with the third concentric layer.

In yet another example, the third concentric layer may be in direct contact with the second concentric layer.

In yet another example, the conduit may be without a tie layer between the third concentric layer and the fourth concentric layer.

In yet another example, the conduit may be without a tie layer between the third concentric layer and the second concentric layer.

In yet another example, the conduit may further include at least one microduct extending through the lumen.

In yet another example, the at least one microduct each may include an inner microduct concentric layer including an inner microduct outer surface and a microduct lumen extending therethrough. The at least one microduct each may include an outer microduct concentric layer at least partially enveloping the inner microduct outer surface. The inner microduct concentric layer and the outer microduct concentric layer may be coextruded. An inner microduct melt viscosity of the inner microduct concentric layer may be higher than an outer microduct melt viscosity of outer microduct concentric layer. An inner microduct thickness of the inner microduct concentric layer may be at least 3% of a combined thickness of the inner and outer concentric layers of the at least one microduct.

In yet another example, the conduit may further include at least one cable disposed in the microduct lumen.

In yet another example, the cable may be selected from the group consisting of communications cable, power cable, and combinations thereof.

In yet another example, the inner microduct melt viscosity may be at least ten times higher than the outer microduct melt viscosity.

In yet another example, the inner microduct concentric layer may include a polyamide including PA6, PA11, PA12, PA46, PA66, or combinations thereof.

In yet another example, the inner microduct concentric layer may include PA12 and the outer microduct concentric layer may include TPU.

In yet another example, the inner microduct concentric layer may include HDPE and the outer microduct concentric layer may include TPU.

In yet another example, the inner microduct concentric layer may include PP and the outer microduct concentric layer may include TPE.

In yet another example, the inner microduct thickness may be at least 10% of the combined thickness of the inner and outer microduct concentric layers.

In yet another example, the inner microduct thickness may be at least 20% of the combined thickness of the inner and outer microduct concentric layers.

In yet another example, the inner microduct thickness may be at least 30% of the combined thickness of the inner and outer microduct concentric layers.

In yet another example, the inner microduct concentric layer may be in direct contact with the outer microduct concentric layer.

In yet another example, the conduit may be without a tie layer between the inner microduct concentric layer and the outer microduct concentric layer.

In yet another example, the present disclosure provides an oversheath. The oversheath includes a first concentric layer, including a first outer surface and defining a lumen extending therethrough. The oversheath further includes a second concentric layer at least partially enveloping the first outer surface. The oversheath further includes at least one conduit extending through the lumen. The at least one conduit each include an inner conduit concentric layer, including a conduit outer surface and a conduit lumen extending therethrough. The at least one conduit each further include an outer conduit concentric layer at least partially enveloping the inner conduit concentric layer. The first concentric layer and the second concentric layer are coextruded. The inner conduit concentric layer and the outer conduit concentric layer are coextruded. A first melt viscosity of the first concentric layer is higher than a second melt viscosity of the second concentric layer. An inner conduit melt viscosity of the inner conduit concentric layer is higher than an outer conduit melt viscosity of the outer conduit concentric layer. A thickness of the first concentric layer is at least 3% of a combined thickness of the first and second concentric layers of the oversheath. An inner conduit thickness of the inner conduit concentric layer is at least 3% of a combined thickness of the inner and outer conduit concentric layers of the at least one conduit. The first concentric layer and the inner conduit concentric layer each independently include a polyamide (PA), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), high-density polyethylene (HDPE), or combinations thereof. The second concentric layer and the outer conduit concentric layer each independently include thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), poly-2,6-dimethylphenylene oxide (PPO), polyvinyl methyl ether, polyvinyl chloride (PVC), polyetherimide (PEI), polymethyl methacrylate (PMMA), polyacrylic acid (PAA), polyether ketone, or combinations thereof.

DETAILED DESCRIPTION

The uses of the terms “a” and “an” and “the” and similar referents in the context of describing the present disclosure (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “plurality of” is defined by the Applicant in the broadest sense, superseding any other implied definitions or limitations hereinbefore or hereinafter unless expressly asserted by Applicant to the contrary, to mean a quantity of more than one. Recitations of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

As used herein in the terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional acts or structures. The present description also contemplates other examples “comprising,” “consisting,” and “consisting essentially of,” the examples or elements presented herein, whether explicitly set forth or not.

In describing elements of the present disclosure, the terms 1st, 2nd, first, second, A, B, (a), (b), and the like may be used herein. These terms are only used to distinguish one element from another element, but do not limit the corresponding elements irrespective of the nature or order of the corresponding elements.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by those skilled in the art to which the present disclosure pertains. Such terms as those defined in a generally used dictionary are to be interpreted as having meanings equal to the contextual meanings in the relevant field of art.

As used herein, the term “about,” when used in the context of a numerical value or range set forth means a variation of ±15%, or less, of the numerical value. For example, a value differing by ±15%, ±14%, ±10%, or ±5%, among others, would satisfy the definition of “about,” unless more narrowly defined in particular instances.

As used herein, the terms “melt viscosity” and “complex viscosity” refer to a measure, at a given temperature, of the rate at which chains of a polymer may move relative to each other. The rate at which chains of a polymer may move relative to each other may be controlled by the case of rotation about the backbone bonds and the degree of entanglement of the chains.

Referring toFIG.1A, a perspective view of an example of a conduit100is illustrated. Conduit100includes a first concentric layer104. First concentric layer104includes a first outer surface and defines a lumen106extending through first concentric layer104. Second concentric layer102at least partially envelops the first outer surface. First concentric layer104and second concentric layer102may be coextruded. A melt viscosity of first concentric layer104may be higher than a melt viscosity of second concentric layer102. A thickness of first concentric layer104is at least 3% of a combined thickness of first concentric layer104and second concentric layer102of conduit100. In certain examples, a thickness of first concentric layer104may be at least 10% of a combined thickness of first concentric layer104and second concentric layer102of conduit100. In other examples, a thickness of first concentric layer104may be at least 20% of a combined thickness of first concentric layer104and second concentric layer102of conduit100. In still other examples, a thickness of first concentric layer104may be at least 30% of a combined thickness of first concentric layer104and second concentric layer102of conduit100.

In certain examples, the melt viscosity of first concentric layer104may be at least ten times higher than the melt viscosity of second concentric layer102.

In an example, as shown inFIGS.1A and1B, second concentric layer102is in direct contact with first concentric layer104. In other examples, as shown inFIGS.1A and1B, there is no tie layer between second concentric layer102and first concentric layer104.

Thermoplastic polyurethane (TPU) has a high tensile strength to sustain tensile loads during installation, as well as excellent abrasion resistance suitable for HDD trenchless applications. TPU also offers significant cold impact resistance at temperatures of up to −40° C., which is observed in many parts of North America, Europe, and Asia during water. However, at the process temperature of 204° C., as compared to typical pipe extrusion resin like high-density polyethylene (HDPE) that has a melt viscosity of 1440 Pas at a shear rate of 100 s−1, TPU has a melt viscosity of 178 Pas at the same shear rate, which is significantly lower. The low melt viscosity of TPU may make the TPU sag and may make processing the TPU more difficult. Unlike a material like HDPE, in which the molecular weight may control both viscosity and mechanical properties, the mechanical properties of TPU may be controlled by the relative amounts of soft and hard segments of the TPU without largely changing the molecular weight of the TPU. Accordingly, a particular grade of TPU may have desirable mechanical properties, but may not meet the suitable melt strength for pipe extrusion to provide a product in-specification at a desirable production rate.

However, conduit100may be a dimensionally in-specification product. Conduit100may be produced by utilizing a 2-layer co-extrusion process such that first concentric layer104includes a polymer having a higher melt viscosity so as to provide stabilization to second concentric layer102.

Referring toFIG.2A, a perspective view of an example of a conduit200is illustrated. Conduit200includes a first concentric layer202. First concentric layer202includes a first outer surface and defines a lumen210extending through first concentric layer202. Second concentric layer204at least partially envelops the first outer surface. First concentric layer202and second concentric layer204may be coextruded. A melt viscosity of first concentric layer202may be higher than a melt viscosity of second concentric layer204. A thickness of first concentric layer202is at least 3% of a combined thickness of first concentric layer202and second concentric layer204of conduit200. In certain examples, a thickness of first concentric layer202may be at least 10% of a combined thickness of first concentric layer202and second concentric layer204of conduit200. In other examples, a thickness of first concentric layer202may be at least 20% of a combined thickness of first concentric layer202and second concentric layer204of conduit200. In still other examples, a thickness of first concentric layer202may be at least 30% of a combined thickness of first concentric layer202and second concentric layer204of conduit200.

In certain examples, the melt viscosity of first concentric layer202may be at least ten times higher than the melt viscosity of second concentric layer204.

In an example, as shown inFIGS.2A and2B, second concentric layer204is in direct contact with first concentric layer202. In other examples, as shown inFIGS.2A and2B, there is no tie layer between second concentric layer204and first concentric layer202.

Third concentric layer206includes a third outer surface and at least partially overlaps a second outer surface of second concentric layer204. Fourth concentric layer208at least partially envelops third concentric layer206. Third concentric layer206and fourth concentric layer208may be coextruded. A melt viscosity of third concentric layer206may be higher than a melt viscosity of fourth concentric layer208. A combined two-layer thickness of first concentric layer202and third concentric layer206may be at least 3% of a combined four-layer thickness of first concentric layer202, second concentric layer204, third concentric layer206, and fourth concentric layer208of conduit200. In certain examples, the combined two-layer thickness of first concentric layer202and third concentric layer206may be at least 10% of the combined four-layer thickness of first concentric layer202, second concentric layer204, third concentric layer206, and fourth concentric layer208of conduit200. In other examples, the combined two-layer thickness of first concentric layer202and third concentric layer206may be at least 20% of the combined four-layer thickness of first concentric layer202, second concentric layer204, third concentric layer206, and fourth concentric layer208of conduit200. In still other examples, the combined two-layer thickness of first concentric layer202and third concentric layer206may be at least 30% of the combined four-layer thickness of first concentric layer202, second concentric layer204, third concentric layer206, and fourth concentric layer208of conduit200.

In certain examples, the melt viscosity of third concentric layer206may be at least ten times higher than the melt viscosity of fourth concentric layer208.

In an example, as shown inFIGS.2A and2B, second concentric layer204is in direct contact with third concentric layer206, and third concentric layer206is in direct contact with fourth concentric layer208. In other examples, as shown inFIGS.2A and2B, there is no tie layer between second concentric layer204and third concentric layer206and/or no tie layer between third concentric layer206and fourth concentric layer208.

In other examples, first concentric layer202may include a polyamide including PA6, PA11, PA12, PA46, PA66, or combinations thereof. In another preferred example, first concentric layer202may include PA12.

In other examples, third concentric layer206may include a polyamide including PA6, PA11, PA12, PA46, PA66, or combinations thereof. In another preferred example, third concentric layer206may include PA12.

Referring toFIG.3A, a perspective view of an example of a conduit300, including microducts302,304in lumen306, is illustrated. An example of conduit300may be referred to as “FuturePath.” Conduit300includes a first concentric layer308. First concentric layer308includes a first outer surface and defines lumen306extending through first concentric layer308. Second concentric layer310at least partially envelops the first outer surface. First concentric layer308and second concentric layer310may be coextruded. A melt viscosity of first concentric layer308may be higher than a melt viscosity of second concentric layer310. A thickness of first concentric layer308is at least 3% of a combined thickness of first concentric layer308and second concentric layer310of conduit300.

In an example, a combined thickness of first concentric layer308and second concentric layer310of conduit300may be from about 0.5 mm, or from about 0.6 mm, or from about 0.7 mm, or from about 0.8 mm, or from about 0.9 mm, or from about 1.0 mm, or from about 1.1 mm, or from about 1.2 mm, or from about 1.3 mm, or from about 1.4 mm, or from about 1.5 mm, or from about 1.6 mm, or from about 1.7 mm, or from about 1.8 mm, or from about 1.9 mm, or from about 2.0 mm, or from about 2.1 mm, or from about 2.2 mm, or from about 2.3 mm, or from about 2.4 mm, or from about 2.5 mm, or from about 2.6 mm, or from about 2.7 mm, or from about 2.8 mm, or from about 2.9 mm, to about 3.0 mm; or from about 0.5 mm to about 0.6 mm, or to about 0.7 mm, or to about 0.8 mm, or to about 0.9 mm, or to about 1.0 mm, or to about 1.1 mm, or to about 1.2 mm, or to about 1.3 mm, or to about 1.4 mm, or to about 1.5 mm, or to about 1.6 mm, or to about 1.7 mm, or to about 1.8 mm, or to about 1.9 mm, or to about 2.0 mm, or to about 2.1 mm, or to about 2.2 mm, or to about 2.3 mm, or to about 2.4 mm, or to about 2.5 mm, or to about 2.6 mm, or to about 2.7 mm, or to about 2.8 mm, or to about 2.9 mm; or from any one of the above minima to any one of the above maxima.

In certain examples, a thickness of first concentric layer308may be at least 10% of a combined thickness of first concentric layer308and second concentric layer310of conduit300. In other examples, a thickness of first concentric layer308may be at least 20% of a combined thickness of first concentric layer308and second concentric layer310of conduit300. In still other examples, a thickness of first concentric layer308may be at least 30% of a combined thickness of first concentric layer308and second concentric layer310of conduit300.

In certain examples, the melt viscosity of first concentric layer308may be at least ten times higher than the melt viscosity of second concentric layer310.

In an example, as shown inFIGS.3A and3B, second concentric layer310is in direct contact with first concentric layer308. In other examples, as shown inFIGS.3A and3B, there is no tie layer between second concentric layer310and first concentric layer308.

Conduit300includes microducts302,304extending through lumen306. Each of microducts302,304includes inner microduct concentric layer312. Inner microduct concentric layer312includes an inner microduct outer surface, and a microduct lumen316extending through inner microduct concentric layer312. Outer microduct concentric layer314at least partially envelops the inner microduct outer surface. Inner microduct concentric layer312and outer microduct concentric layer314may be coextruded. A melt viscosity of inner microduct concentric layer312may be higher than a melt viscosity of outer microduct concentric layer314. An inner microduct thickness of inner microduct concentric layer312is at least 3% of a combined thickness of inner microduct concentric layer312and outer microduct concentric layer314. In certain examples, an inner microduct thickness of inner microduct concentric layer312may be at least 10% of a combined thickness of inner microduct concentric layer312and outer microduct concentric layer314. In other examples, an inner microduct thickness of inner microduct concentric layer312may be at least 20% of a combined thickness of inner microduct concentric layer312and outer microduct concentric layer314. In still other examples, an inner microduct thickness of inner microduct concentric layer312may be at least 30% of a combined thickness of inner microduct concentric layer312and outer microduct concentric layer314.

In an example, microducts302,304may each have an inner diameter of from about 3 mm, or from about 3.5 mm, or from about 4.0 mm, or from about 4.5 mm, or from about 5.0 mm, or from about 5.5 mm, or from about 6.0 mm, or from about 6.5 mm, or from about 7.0 mm, or from about 7.5 mm, or from about 8.0 mm, or from about 8.5 mm, or from about 9.0 mm, or from about 9.5 mm, or from about 10.0 mm, or from about 10.5 mm, or from about 11.0 mm, or from about 11.5 mm, or from about 12.0 mm, or from about 12.5 mm, or from about 13.0 mm, or from about 13.5 mm, or from about 14.0 mm, or from about 14.5 mm, or from about 15.0 mm, or from about 15.5 mm, or from about 16.0 mm, or from about 16.5 mm, or from about 17.0 mm, or from about 17.5 mm, or from about 18.0 mm, or from about 18.5 mm, or from about 19.0 mm, or from about 19.5 mm, or from about 20.0 mm; or from about 3.5 mm to about 4.0 mm, or to about 4.5 mm, or to about 5.0 mm, or to about 5.5 mm, or to about 6.0 mm, or to about 6.5 mm, or to about 7.0 mm, or to about 7.5 mm, or to about 8.0 mm, or to about 8.5 mm, or to about 9.0 mm, or to about 9.5 mm, or to about 10.0 mm, or to about 10.5 mm, or to about 11.0 mm, or to about 11.5 mm, or to about 12.0 mm, or to about 12.5 mm, or to about 13.0 mm, or to about 13.5 mm, or to about 14.0 mm, or to about 14.5 mm, or to about 15.0 mm, or to about 15.5 mm, or to about 16.0 mm, or to about 16.5 mm, or to about 17.0 mm, or to about 17.5 mm, or to about 18.0 mm, or to about 18.5 mm, or to about 19.0 mm, or to about 19.5 mm, or from any one of the above minima to any one of the above maxima.

In an example, microducts302,304may each have an outer diameter greater than the inner diameter. In an example, the outer diameter of each of microducts302,304may be from about 5.0 mm, or from about 5.5 mm, or from about 6.0 mm, or from about 6.5 mm, or from about 7.0 mm, or from about 7.5 mm, or from about 8.0 mm, or from about 8.5 mm, or from about 9.0 mm, or from about 9.5 mm, or from about 10.0 mm, or from about 10.5 mm, or from about 11.0 mm, or from about 11.5 mm, or from about 12.0 mm, or from about 12.5 mm, or from about 13.0 mm, or from about 13.5 mm, or from about 14.0 mm, or from about 14.5 mm, or from about 15.0 mm, or from about 15.5 mm, or from about 16.0 mm, or from about 16.5 mm, or from about 17.0 mm, or from about 17.5 mm, or from about 18.0 mm, or from about 18.5 mm, or from about 19.0 mm, or from about 19.5 mm, or from about 20.0 mm, or from about 20.5 mm, or from about 21.0 mm, or from about 21.5 mm, or from about 22.0 mm, or from about 22.5 mm, or from about 23.0 mm, or from about 23.5 mm, or from about 24.0 mm, or from about 24.5 mm to about 25.0 mm; or from about 5.0 mm to about 5.5 mm, or to about 6.0 mm, or to about 6.5 mm, or to about 7.0 mm, or to about 7.5 mm, or to about 8.0 mm, or to about 8.5 mm, or to about 9.0 mm, or to about 9.5 mm, or to about 10.0 mm, or to about 10.5 mm, or to about 11.0 mm, or to about 11.5 mm, or to about 12.0 mm, or to about 12.5 mm, or to about 13.0 mm, or to about 13.5 mm, or to about 14.0 mm, or to about 14.5 mm, or to about 15.0 mm, or to about 15.5 mm, or to about 16.0 mm, or to about 16.5 mm, or to about 17.0 mm, or to about 17.5 mm, or to about 18.0 mm, or to about 18.5 mm, or to about 19.0 mm, or to about 19.5 mm, or to about 20.0 mm, or to about 20.5 mm, or to about 21.0 mm, or to about 21.5 mm, or to about 22.0 mm, or to about 22.5 mm, or to about 23.0 mm, or to about 23.5 mm, or to about 24.0 mm, or to about 24.5 mm; or from any one of the above minima to any one of the above maxima.

Though not shown inFIGS.3A and3B, conduit300may include at least one cable disposed in microduct lumen316. The at least one cable may be selected from the group consisting of communications cable, power cable, and combinations thereof.

In certain examples, the melt viscosity of inner microduct concentric layer312may be at least ten times higher than the melt viscosity of outer microduct concentric layer314.

In an example, as shown inFIGS.3A and3B, outer microduct concentric layer314is in direct contact with inner microduct concentric layer312. In other examples, as shown inFIGS.3A and3B, there is no tie layer between outer microduct concentric layer314and inner microduct concentric layer312.

In other examples, first concentric layer308may include a polyamide including PA6, PA11, PA12, PA46, PA66, or combinations thereof. In another preferred example, first concentric layer308may include PA12.

Referring toFIG.6, another example of a microduct400is illustrated. Microduct lumen404extends longitudinally through inner microduct concentric layer402. A plurality of ribs406extends longitudinally along an inner surface of inner microduct concentric layer402. Each of the plurality of ribs406protrudes inward toward microduct lumen404. Plurality of ribs406is configured to minimize the coefficient of friction of a cable (not shown) pulled longitudinally through microduct lumen404. Plurality of ribs406may be evenly distributed about a circumference of microduct lumen404. Plurality of ribs406may be integral to inner microduct concentric layer402and include the polyamide (PA), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), high-density polyethylene (HDPE), or combinations thereof, of inner microduct concentric layer402. Plurality of ribs406may include, for example, at least two ribs406evenly distributed (separated by 180°) about the circumference of microduct lumen404, or at least 4 ribs406evenly distributed (separated by 90°) about the circumference of microduct lumen404, or at least six ribs406evenly distributed (separated by 60°) about the circumference of microduct lumen404, or at least eight ribs406evenly distributed (separated by 45°) about the circumference of microduct lumen404, or more ribs406evenly distributed about the circumference of microduct lumen404. As illustrated inFIG.6, the plurality of ribs406includes 42 ribs evenly distributed about the circumference of microduct lumen404, separated by about 8.6°.

Referring toFIG.7, a cross-sectional view of another example of a conduit500is illustrated. Conduit500includes first concentric layer502and second concentric layer504. Second concentric layer504at least partially envelops first concentric layer502. First concentric layer502and second concentric layer504may be in direct contact or may be without a tie layer between first concentric layer502and second concentric layer504. First concentric layer504defines lumen506extending longitudinally through first concentric layer504. Conduit500may include at least one microduct400within lumen506.

The conduits and methods described above may be better understood in connection with the following Examples. In addition, the following non-limiting examples are an illustration. The illustrated methods are applicable to other examples of conducts of the present disclosure. The procedures described as general methods describe what is believed will be typically effective to provide conduits of the present disclosure. However, the person skilled in the art will appreciate that it may be necessary to vary the procedures for any given example of the present disclosure, e.g., vary the order or steps and/or the chemical reagents used.

EXAMPLES

1. Preparation of Example of Conduit with Microducts

An example of a conduit that is illustrated inFIGS.3A and3Bwas produced by a 2-layer co-extrusion process operating at about 216° C., including a polyamide (PA12) with a high melt viscosity as first concentric layer308and inner microduct concentric layer312, and TPU as second concentric layer310and outer microduct concentric layer314. The polyamide used is commercially available under the tradename and grade Vestamid® NRG 3001, from the supplier Evonik Industries. The TPU used is commercially available under the tradename and grade Estane ETE 65DT3, from the supplier Lubrizol. The TPU layers310and314had a thickness of 1.8 mm and 3.5 mm, respectively. The polyamide layers308and312had a thickness of 0.8 mm and 0.8 mm, respectively. The microducts302,304had an outside diameter of 18 mm.

FIG.4illustrates a comparison of the viscosity-oscillation frequency data for PA12 to the viscosity-oscillation frequency data for pipe-grade HDPE resin and TPU functional material. The pipe grade HDPE resin is commercially available under the tradename and grade Alathon L5040TC, from the supplier Lyondellbasell. AsFIG.4demonstrates, the “complex viscosity,” also known as melt viscosity, of PA12 is twice the melt viscosity of HDPE and over 10 times the melt viscosity of TPU. The large melt viscosity of PA12 may stabilize the TPU if the co-extruded layer of PA12 is present in as little as 3% of the combined thickness of the two concentric layers of conduit, or as little as 3% of the combined thickness of the two concentric layers of microduct.

2. Determination of Properties of Coextruded Conduit of Example 1, Illustrated in FIGS.3A and3B

The functional properties of the PA12/TPU co-extruded conduit of Example 1 were tested and compared to a conduit prepared from HDPE.

The minimum working pull strength of the conduit and microducts was determined in accordance with the applicable provisions of ASTM D 638 and modifications specified in GR-356-CORE Performance Requirements and Test Procedures Issue 2, June. 2009 4-10 Telecordia Technologies, Inc. Five test specimens were used for each sample tested. Each test specimen measured 12 inches±⅛ inch long (300 mm±3 mm) and was cut from the respective sample. The Zwick/Roell Z050 N universal tensile machines was used, and the rate of testing was 2.0 in/min (5.1 cm/min).

Crush load measurements were conducted following ASTM D2412, using a Zwick/Roell Z050N universal tensile machine. For each sample, 5 test specimens were used, each test specimen measured 6 inches±⅛ inch long (150 mm±3 mm). Test specimens were tested at a compressive deformation rate of 0.5 in/min (12.5 mm/min). From the crush load deformation graph, the crush load at 20% deformation was recorded.

The abrasion mass loss was measured using a test method based on the ASTM D3389. In this test, for each sample, a specimen of 6 inches±⅛ inch long (150 mm+3 mm) was used. The specimen was abraded over a 50-grit abrasive cloth with a 15-lb (6.8 kg) force for 2 hours. The specimen was weighed before and after the abrasion. The weight loss after the abrasion was calculated as a percentage of the original weight.

Table 1 lists the functional properties of the coextruded conduit of Example 1 compared to a similar product made from HDPE. The coextruded conduit of Example 1 has a safe pull load that is about 3 times the safe pull load of the comparison product made from HDPE. Further, the coextruded conduit of Example 1 has a 6% greater crush load at 20% deflection, and about twice the abrasion mass loss, of the comparison product made from HDPE.

3. Crush Force-Deformation Dependence on Relative Layer Thicknesses

A coextruded conduit product of the present disclosure may have mechanical integrity if there is chemical compatibility between the coextruded materials such that the coextruded materials may form a unified load transfer body. If coextruded materials are not compatible, the layer with a higher melt viscosity may simply act as a scaffold and may not contribute to the loading capability of the conduit.FIG.5illustrates a crush force-deformation plot for an example of a conduit that is illustrated inFIGS.3A and3Band prepared according to Example 1, produced by a 2-layer co-extrusion process, including a polyamide (PA12) with a high melt viscosity as first concentric layer308, and TPU as second concentric layer310, as well as another example of a PA12-TPU conduit with different PA12 and TPU layer thicknesses.FIG.5demonstrates crush force-deformation of two examples of the PA12-TPU conduits with different PA12 and TPU layer thicknesses compared to a conduit made from HDPE. For a telecommunication industry standard deformation of 20%, the crush force for a coextruded conduit including 30% PA12 and 70% TPU is 7399 lbf prepared according to Example 1 (top curve illustrated inFIG.5, percentages reflect the layer thicknesses for the co-extruded conduits), which is 6% greater than that of single-layer HDPE (middle curve illustrated inFIG.5). The crush force for a coextruded conduit including 20% PA12 and 80% TPU (bottom curve illustrated inFIG.5, percentages reflect the layer thicknesses for the co-extruded conduits) is 7% smaller than that of HDPE. Because PA12 and TPU are chemically compatible, by varying the relative layer thicknesses, the crush force of the coextruded conduit may be controlled. The crush force-deformation results demonstrate the importance of compatibility between layers of a coextruded conduit. If the layers of a coextruded conduit include chemically compatible materials, a synergistic impact on both processing and product properties is observed that is dependent on the relative percentages of the coextruded layers of the individual materials. When PA12 and TPU are coextruded at a layer thickness of PA12 of less than 10%, it was observed that PA12 provides mostly process stabilization of TPU. When PA12 has a relative layer thickness of greater than 10%, the PA12 provides both processing stabilization and mechanical functionality to the coextruded product, as illustrated inFIG.5.

The subject-matter of the disclosure may also relate, among others, to the following aspects:

A first aspect relates to a conduit, comprising: a first concentric layer, comprising a first outer surface and defining a lumen extending therethrough; a second concentric layer at least partially enveloping the first outer surface; wherein the first concentric layer and the second concentric layer are coextruded; wherein a first melt viscosity of the first concentric layer is higher than a second melt viscosity of the second concentric layer; and wherein a thickness of the first concentric layer is at least 3% of a combined thickness of the first and second concentric layers of the conduit.

A second aspect relates to the conduit of aspect 1, wherein the first melt viscosity is at least ten times higher than the second melt viscosity.

A third aspect relates to the conduit of any preceding aspect, wherein the first concentric layer comprises a polyamide (“PA”), polyvinyl chloride (“PVC”), polybutylene terephthalate (“PBT”), polyethylene terephthalate (“PET”), polystyrene (“PS”), polypropylene (“PP”), polyvinylidene fluoride (“PVDF”), polytetrafluoroethylene (“PTFE”), polyethylene oxide (“PEO”), high-density polyethylene (“HDPE”), or combinations thereof.

A fourth aspect relates to the conduit of any preceding aspect, wherein the first concentric layer comprises a polyamide comprising PA6, PA11, PA12, PA46, PA66, or combinations thereof.

A fifth aspect relates to the conduit of any preceding aspect, wherein the second concentric layer comprises thermoplastic polyurethane (“TPU”), thermoplastic elastomer (“TPE”), poly-2,6-dimethylphenylene oxide (“PPO”), polyvinyl methyl ether, polyvinyl chloride (“PVC”), polyetherimide (“PEI”), polymethyl methacrylate (“PMMA”), polyacrylic acid (“PAA”), polyether ketone, or combinations thereof.

A sixth aspect relates to the conduit of any preceding aspect, wherein the first concentric layer comprises PA12 and the second concentric layer comprises TPU.

A seventh aspect relates to the conduit of aspects 1 to 5, wherein the first concentric layer comprises HDPE and the second concentric layer comprises TPU.

An eighth aspect relates to the conduit of aspects 1 to 5, wherein the first concentric layer comprises PP and the second concentric layer comprises TPE.

A ninth aspect relates to the conduit of any preceding aspect, wherein the thickness of the first concentric layer is at least 10% of the combined thickness.

A tenth aspect relates to the conduit of any preceding aspect, wherein the thickness of the first concentric layer is at least 20% of the combined thickness.

An eleventh aspect relates to the conduit of any preceding aspect, wherein the thickness of the first concentric layer is at least 30% of the combined thickness.

A twelfth aspect relates to the conduit of any preceding aspect, wherein the second concentric layer is in direct contact with the first concentric layer.

A thirteenth aspect relates to the conduit of aspects 1 to 12, without a tie layer between the first concentric layer and the second concentric layer.

A fourteenth aspect relates to the conduit of any preceding aspect, further comprising: a third concentric layer comprising a third outer surface, the third concentric layer at least partially enveloping a second outer surface of the second concentric layer; and a fourth concentric layer at least partially enveloping the third concentric layer; wherein the third concentric layer and the fourth concentric layer are coextruded; wherein a third melt viscosity of the third concentric layer is higher than a fourth melt viscosity of the fourth concentric layer; and wherein a combined two-layer thickness of the first concentric layer and the third concentric layer is at least 3% of a combined four-layer thickness of the first, second, third, and fourth concentric layers of the conduit.

A fifteenth aspect relates to the conduit of aspect 14, wherein the third melt viscosity is at least ten times higher than the fourth melt viscosity.

A sixteenth aspect relates to the conduit of aspects 14 and 15, wherein the third concentric layer comprises a polyamide (PA), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), high-density polyethylene (HDPE), or combinations thereof.

A seventeenth aspect relates to the conduit of aspects 14 to 16, wherein the third concentric layer comprises a polyamide comprising PA6, PA11, PA12, PA46, PA66, or combinations thereof.

A nineteenth aspect relates to the conduit of aspects 14 to 18, wherein the third concentric layer comprises PA12 and the fourth concentric layer comprises TPU.

A twentieth aspect relates to the conduit of aspects 14 to 18, wherein the third concentric layer comprises HDPE and the fourth concentric layer comprises TPU.

A twenty-first aspect relates to the conduit of aspects 14 to 18, wherein the third concentric layer comprises PP and the fourth concentric layer comprises TPE.

A twenty-second aspect relates to the conduit of aspects 14 to 21, wherein the combined two-layer thickness is at least 10% of the combined four-layer thickness.

A twenty-third aspect relates to the conduit of aspects 14 to 22, wherein the combined two-layer thickness is at least 20% of the combined four-layer thickness.

A twenty-fourth aspect relates to the conduit of aspects 14 to 23, wherein the combined two-layer thickness is at least 30% of the combined four-layer thickness.

A twenty-fifth aspect relates to the conduit of aspects 14 to 24, wherein the fourth concentric layer is in direct contact with the third concentric layer.

A twenty-sixth aspect relates to the conduit of aspects 14 to 25, wherein the third concentric layer is in direct contact with the second concentric layer.

A twenty-seventh aspect relates to the conduit of aspects 14 to 24, without a tie layer between the third concentric layer and the fourth concentric layer.

A twenty-eighth aspect relates to the conduit of aspects 14 to 24 and 27, without a tie layer between the third concentric layer and the second concentric layer.

A twenty-ninth aspect relates to the conduit of any preceding aspect, further comprising at least one microduct extending through the lumen.

A thirtieth aspect relates to the conduit of aspect 29, wherein the at least one microduct each comprise: an inner microduct concentric layer, comprising an inner microduct outer surface, and a microduct lumen extending therethrough; and an outer microduct concentric layer, the outer microduct concentric layer at least partially enveloping the inner microduct outer surface; wherein the inner microduct concentric layer and the outer microduct concentric layer are coextruded; wherein an inner microduct melt viscosity of the inner microduct concentric layer is higher than an outer microduct melt viscosity of the outer microduct concentric layer; and wherein an inner microduct thickness of the inner microduct concentric layer is at least 3% of a combined microduct thickness of the inner and outer concentric layers of the at least one microduct.

A thirty-first aspect relates to the conduit of aspect 30, further comprising at least one cable disposed in the microduct lumen.

A thirty-second aspect relates to the conduit of aspect 31, wherein the cable is selected from the group consisting of communications cable, power cable, and combinations thereof.

A thirty-third aspect relates to the conduit of aspects 30 to 32, wherein the inner microduct melt viscosity is at least ten times higher than the outer microduct melt viscosity.

A thirty-fifth aspect relates to the conduit of aspects 30 to 34, wherein the inner microduct concentric layer comprises a polyamide comprising PA6, PA11, PA12, PA46, PA66, or combinations thereof.

A thirty-seventh aspect relates to the conduit of aspects 30 to 36, wherein the inner microduct concentric layer comprises PA12 and the outer microduct concentric layer comprises TPU.

A thirty-eighth aspect relates to the conduit of aspects 30 to 36, wherein the inner microduct concentric layer comprises HDPE and the outer microduct concentric layer comprises TPU.

A thirty-ninth aspect relates to the conduit of aspects 30 to 36, wherein the inner microduct concentric layer comprises PP and the outer microduct concentric layer comprises TPE.

A fortieth aspect relates to the conduit of aspects 30 to 39, wherein the inner microduct thickness is at least 10% of the combined microduct thickness of the inner and outer microduct concentric layers.

A forty-first aspect relates to the conduit of aspects 30 to 40, wherein the inner microduct thickness is at least 20% of the combined microduct thickness of the inner and outer microduct concentric layers.

A forty-second aspect relates to the conduit of aspects 30 to 41, wherein the inner microduct thickness is at least 30% of the combined microduct thickness of the inner and outer microduct concentric layers.

A forty-third aspect relates to the conduit of aspects 30 to 42, wherein the inner microduct concentric layer is in direct contact with the outer microduct concentric layer.

A forty-fourth aspect relates to the conduit of aspects 30 to 42, without a tie layer between the inner microduct concentric layer and the outer microduct concentric layer.

A thirty-ninth aspect relates to an oversheath, comprising: a first concentric layer, comprising a first outer surface and defining a lumen extending therethrough; a second concentric layer at least partially enveloping the first outer surface; and at least one conduit extending through the lumen, the at least one conduit each comprising: an inner conduit concentric layer, comprising a conduit outer surface and a conduit lumen extending therethrough; and an outer conduit concentric layer, the outer conduit concentric layer at least partially enveloping the inner conduit concentric layer; wherein the first concentric layer and the second concentric layer are coextruded; wherein the inner conduit concentric layer and the outer conduit concentric layer are coextruded; wherein a first melt viscosity of the first concentric layer is higher than a second melt viscosity of the second concentric layer; wherein an inner conduit melt viscosity of the inner conduit concentric layer is higher than an outer conduit melt viscosity of the outer conduit concentric layer; wherein a thickness of the first concentric layer is at least 3% of a combined thickness of the first and second concentric layers of the oversheath; wherein an inner conduit thickness of the inner conduit concentric layer is at least 3% of a combined conduit thickness of the inner and outer conduit concentric layers of the at least one conduit; wherein the first concentric layer and the inner conduit concentric layer each independently comprise a polyamide (PA), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), high-density polyethylene (HDPE), or combinations thereof; and wherein the second concentric layer and the outer concentric layer each independently comprise thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), poly-2,6-dimethylphenylene oxide (PPO), polyvinyl methyl ether, polyvinyl chloride (PVC), polyetherimide (PEI), polymethyl methacrylate (PMMA), polyacrylic acid (PAA), polyether ketone, or combinations thereof.

In addition to the features mentioned in each of the independent aspects enumerated above, some examples may show, alone or in combination, the optional features mentioned in the dependent aspects and/or as disclosed in the description above and shown in the figures.