阅读说明：本技术 燃料管道及其制备和使用方法 (Fuel lines and methods of making and using the same ) 是由 詹姆斯·勒德洛 凯文·M·麦考利 于 2018-09-28 设计创作，主要内容包括：本公开涉及耐燃料和抗分层的多层管道。在一方面,本公开提供一种具有环形横截面的一定长度的管道,所述环形横截面包括由至少75wt％的含氟聚合物(例如,至少75wt％的PVDF聚合物)形成的环形含氟聚合物层,所述含氟聚合物层具有外表面和内表面；以及围绕所述环形含氟聚合物层设置、由至少75wt％的热塑性塑料(例如,热塑性聚氨酯、热塑性聚酰胺和/或热塑性聚酯)形成的环形热塑性层,所述热塑性聚氨酯层具有内表面,所述内表面与所述含氟聚合物层的所述外表面接触；以及外表面,其中所述含氟聚合物层例如通过电子束处理共价结合至所述热塑性聚氨酯层。(The present disclosure relates to fuel resistant and delamination resistant multilayer pipes. In one aspect, the present disclosure provides a length of pipe having an annular cross-section comprising an annular fluoropolymer layer formed from at least 75 wt% fluoropolymer (e.g., at least 75 wt% PVDF polymer), the fluoropolymer layer having an outer surface and an inner surface; and an annular thermoplastic layer disposed about said annular fluoropolymer layer formed from at least 75 wt% of a thermoplastic (e.g., a thermoplastic polyurethane, a thermoplastic polyamide, and/or a thermoplastic polyester), said thermoplastic polyurethane layer having an inner surface in contact with said outer surface of said fluoropolymer layer; and an outer surface, wherein the fluoropolymer layer is covalently bonded to the thermoplastic polyurethane layer, for example, by electron beam treatment.)

1. A length of pipe having an annular cross-section with an inner surface and an outer surface, the annular cross-section comprising:

an annular fluoropolymer layer formed from at least 75 wt% fluoropolymer (e.g., at least 75 wt% PVDF polymer), the fluoropolymer layer having an outer surface and an inner surface; and

an annular thermoplastic layer disposed about said fluoropolymer layer formed from at least 75 wt% thermoplastic, said thermoplastic layer having an inner surface in contact with said outer surface of said fluoropolymer layer; and an outer surface of the outer shell,

wherein the fluoropolymer layer is covalently bonded to the thermoplastic layer.

2. The length of pipe of claim 1, wherein the fluoropolymer of the fluoropolymer layer is selected from PVDF polymer, FEP polymer, PEA polymer, ETFE polymer, ECTFE polymer, PCTFE polymer, THV polymer, or combinations or copolymers thereof.

3. A length of pipe according to claim 1 or claim 2, wherein the fluoropolymer layer has a thickness in the range 0.1mm to 10 mm.

4. A length of pipe according to any one of claims 1 to 3, wherein the thermoplastic comprises (or is) a thermoplastic polyurethane (e.g. a thermoplastic polyurethane elastomer).

5. A length of tubing as claimed in claim 4, wherein the thermoplastic polyurethane of the thermoplastic layer is a polyether polyurethane.

6. A length of pipe according to any one of claims 1 to 5, wherein the thermoplastic comprises (or is) a thermoplastic polyester (e.g. a thermoplastic polyester elastomer).

7. A length of pipe according to any one of claims 1 to 6, wherein the thermoplastic comprises (or is) a thermoplastic polyamide (e.g. a thermoplastic polyamide elastomer).

8. A length of pipe according to any one of claims 1 to 7, wherein the thermoplastic of the thermoplastic layer has a Shore A hardness in the range of 50 to 95.

9. A length of pipe according to any one of claims 1 to 8, wherein the thermoplastic layer has a thickness in the range of 0.5mm to 20 mm.

10. A length of pipe according to any one of claims 1 to 9, wherein the inner surface of the fluoropolymer layer forms the inner surface of the pipe.

11. A length of pipe according to any one of claims 1 to 10, wherein the annular cross-section further comprises one or more inner annular polymer layers disposed on the inner surface of the fluoropolymer layer.

12. A length of pipe according to any one of claims 1 to 11, wherein the outer surface of the thermoplastic layer forms the outer surface of the pipe.

13. A length of pipe according to any one of claims 1 to 12, further comprising one or more outer annular polymer layers disposed on the outer surface of the thermoplastic layer.

14. A length of pipe as claimed in any one of claims 1 to 13, having a length of at least 1m, for example at least 2 m.

15. A length of flexible pipe according to any one of claims 1 to 14, wherein the fluoropolymer layer is covalently bonded to the thermoplastic layer by a plurality of > CH-moieties and/or > CF-moieties of the fluoropolymer to a plurality of > CH-moieties of the soft segment of the thermoplastic.

16. A length of flexible pipe according to any one of claims 1 to 15, wherein the length of pipe does not exhibit significant delamination when immersed in CE10 fuel at 40 ℃ for three months.

17. A method for preparing a length of flexible pipe, for example according to any one of claims 1 to 16, the method comprising:

providing a length of pipe having an annular cross-section with an inner surface and an outer surface, the annular cross-section comprising:

an annular fluoropolymer layer formed from at least 75 wt% fluoropolymer (e.g., at least 75 wt% PVDF polymer), the fluoropolymer layer having an outer surface and an inner surface; and

an annular thermoplastic layer disposed about said annular fluoropolymer layer formed from at least 75 wt% thermoplastic, said thermoplastic layer having an inner surface in contact with said outer surface of said fluoropolymer layer; and

treating the length of tubing with an electron beam.

18. The method of claim 17, wherein the treating with the electron beam is performed at a dose of at least 1Mrad, such as at least 5 Mrad.

19. The method of claim 17 or claim 18, wherein the treating with the electron beam forms a covalent bond between the fluoropolymer layer and the thermoplastic layer.

20. A method of transporting a hydrocarbon fuel, the method comprising

Providing a length of pipe according to any one of claims 1 to 17; and

passing the hydrocarbon fuel through the flexible conduit from a first end to a second end of the flexible conduit.

21. A fuel powered apparatus comprising a fuel tank, a fuel powered engine and a length of tubing fluidly connecting the fuel tank with the fuel powered engine as claimed in any one of claims 1 to 17.

Technical Field

The present disclosure relates generally to polymer-based conduits suitable for conducting hydrocarbon fuels, for example. The present disclosure more particularly relates to fuel resistant and delamination resistant multilayer pipes.

Background

It is known that a multi-layer rubber tube or a laminated rubber tube can be used as a fuel delivery hose for introducing an automotive fuel feed line into a vehicle reservoir. Generally, it is desirable for such conduits to have low fuel vapor permeability in order to reduce the amount of hydrocarbon vapor released into the environment. The united states national environmental protection agency sets forth certain regulations that limit the release of hydrocarbons into the environment. And the state of california adopted a more stringent position by the California Air Resources Board (CARB), requiring a maximum permeability of 15g/m²The test involves a 1,000 hour pre-test soak step per day. In addition, the test was conducted on recycled fuel and the amount of hydrocarbon trapped that permeated through the tube wall was measured at a test temperature of 40 ℃. The market does not want to be in the situation where one tube/hose must be used in california and another tube/hose is used elsewhere in the united states, and so it is highly desirable that the fuel line be able to meet the most stringent CARB requirements.

To meet these stringent evaporative emission standards, barrier layers are often used in fuel lines. Thermoplastic fluoropolymers are particularly attractive materials for use as barrier layers. They have a unique combination of properties such as high thermal stability, chemical inertness and non-stick tearability. Thermoplastic fluoropolymers, however, are expensive compared to many other polymers and often do not provide the necessary strength and flexibility to the pipe. As a result, pipes are often formed as multi-layer structures, wherein one or more additional polymer layers may contribute their own characteristics and advantages, such as low density, elasticity, sealability, scratch resistance, and the like. Coextrusion is commonly used to form such multilayer tubes.

Maintaining adhesion between layers under application conditions can be a challenge, particularly for fluoropolymer-based liners, and prolonged exposure of the pipe to fuel can result in delamination of the layers. Many fluoropolymers are non-polar and have very low surface energy (non-wetting surface). Interlayer wetting can be achieved by melting the fluoropolymer; however, after curing, the layers of the resulting multilayer product can easily be separated (delaminated). In most cases, interlayer adhesion is inadequate unless the fluoropolymer is chemically functionalized or modified by special treatment techniques, which are both expensive and complex. If the objective is to produce a multilayer article with a very thin fluoropolymer layer, the modification of the interlayer surface can become a very expensive or even impossible operation. Chemically functionalized fluoropolymers are expensive and they are designed to adhere to specific polymers such as nylon, but not to thermoplastic polyurethanes.

What is needed are improved multilayer fuel pipes that are not only chemically resistant to hydrocarbon fuels and have very low hydrocarbon fuel permeability, but also are resistant to delamination.

Disclosure of Invention

In one aspect, the present disclosure provides a length of pipe having an annular cross-section with an inner surface and an outer surface, the annular cross-section comprising

An annular fluoropolymer layer formed from at least 75 wt% fluoropolymer (e.g., at least 75 wt% PVDF polymer), the fluoropolymer layer having an outer surface and an inner surface; and

an annular thermoplastic layer disposed about the fluoropolymer layer and formed from at least 75 wt% of a thermoplastic (e.g., a thermoplastic polyurethane, a thermoplastic polyester, and/or a thermoplastic polyamide), the thermoplastic layer having an inner surface that is in contact with an outer surface of the fluoropolymer layer; and an outer surface of the outer shell,

wherein the fluoropolymer layer is covalently bonded to the thermoplastic layer.

In another aspect, the present disclosure provides a method for preparing a length of flexible pipe, for example as described above, the method comprising

Providing a length of pipe having an annular cross-section with an inner surface and an outer surface, the annular cross-section comprising:

an annular fluoropolymer layer formed from at least 75 wt% fluoropolymer (e.g., at least 75 wt% PVDF polymer), the fluoropolymer layer having an outer surface and an inner surface; and

an annular polyurethane layer disposed about the annular fluoropolymer layer and formed from at least 75 wt% of a thermoplastic (e.g., a thermoplastic polyurethane, a thermoplastic polyester, and/or a thermoplastic polyamide), the thermoplastic layer having an inner surface that is in contact with an outer surface of the fluoropolymer layer; and

the length of tubing is treated with an electron beam.

In another aspect, the present disclosure provides a length of tubing prepared as described herein.

In another aspect, the present disclosure provides a method for transporting a hydrocarbon fuel, the method comprising

Providing a length of tubing as described herein; and

passing a hydrocarbon fuel through the flexible conduit from the first end to the second end of the flexible conduit.

In another aspect, the present disclosure provides a fuel-powered apparatus comprising a fuel tank, a fuel-powered engine, and a conduit of the present disclosure fluidly connecting the fuel tank with the fuel-powered engine (i.e., configured to transfer fuel from the fuel tank to the engine).

Other aspects of the disclosure will be apparent from the disclosure herein.

Brief description of the drawings

The accompanying drawings are included to provide a further understanding of the disclosed method and apparatus, and are incorporated in and constitute a part of this specification. The figures are not necessarily to scale and the dimensions of the various elements may be distorted for clarity. The drawings illustrate one or more embodiments of the disclosure and, together with the description, serve to explain the principles and operations of the disclosure.

FIG. 1 is a schematic side view of a length of pipe according to one embodiment of the present disclosure;

FIG. 2 is a schematic cross-sectional view of a length of the pipe of FIG. 1;

FIG. 3 is a schematic cross-sectional view of a length of tubing according to another embodiment of the present disclosure;

FIG. 4 is a schematic cross-sectional view of a length of tubing according to another embodiment of the present disclosure;

FIG. 5 is a photograph of a layered prototype 2 sample as described in example 1;

FIG. 6 is a photograph of a layered prototype sample as described in example 1;

FIG. 7 is a set of photographs of an e-beam treated sample as described in example 1;

FIG. 8 is a set of photographs of untreated and e-beam treated samples as described in example 2;

FIG. 9 is a photograph of a permeate sample vial as described in example 3;

FIG. 10 is a graph of permeation data for Ultraflex B as described in example 3; and

fig. 11 is a graph of permeation data for Kynar2500 as described in example 3.

Detailed Description

As noted above, the inventors of the present disclosure have noted that conventional multilayer flexible pipe may suffer from undesirable delamination when used with hydrocarbon fuels for extended periods of time. Unexpectedly, the inventors of the present disclosure have determined that modification of the polymeric material of the pipe can provide a flexible pipe having high delamination resistance but maintaining high resistance to hydrocarbon fuels and fuel vapor permeability.

Accordingly, one aspect of the present disclosure is a length of flexible pipe having an annular cross-section with an inner surface and an outer surface. This duct is shown in a schematic perspective view in fig. 1 and in a schematic cross-sectional view in fig. 2. The flexible conduit 100 includes an annular cross-section 110 (shown in detail in FIG. 2) having an inner surface 112, an outer surface 114, an inner diameter 116, and an outer diameter 118. The inner and outer diameters define a wall thickness 120 of the pipe. Flexible conduit 100 also has a length 130.

The flexible conduit 100 is shown as being circular in overall shape. Of course, one of ordinary skill in the art will appreciate that the conduit may be manufactured in other overall shapes, such as oval, elliptical, or polygonal. Similarly, although flexible pipe 100 is shown as having a radially constant wall thickness, one of ordinary skill in the art will appreciate that in other embodiments, the wall thickness need not be constant. In this case, "wall thickness" is considered to be a radial average wall thickness. In certain desirable embodiments, the wall thickness at any point along the circumference of the pipe is no less than 50% of the average wall thickness.

The annular cross-section of the conduit 100 includes an annular fluoropolymer layer 130 formed of at least 75 wt% fluoropolymer and has an inner surface 132 and an outer surface 134. Disposed around the fluoropolymer layer is an annular thermoplastic layer 140 formed from at least 75 wt% thermoplastic (e.g., thermoplastic polyurethane, thermoplastic polyester, and/or thermoplastic polyamide) and having an inner surface 142 that is in contact with the outer surface 134 of the fluoropolymer layer; and an outer surface 144.

Notably, in this aspect of the disclosure, the fluoropolymer layer is covalently bonded to the thermoplastic layer. As described in more detail below, the inventors of the present disclosure have determined that providing covalent bonding between these layers can help prevent delamination without undesirably affecting other essential properties of the pipe.

As noted above, the fluoropolymer layer is formed from a significant amount (i.e., at least 75 weight percent) of fluoropolymer. One of ordinary skill in the art will appreciate that a variety of additional materials may be used, for example, in the fluoropolymer layer to aid in treating the fluoropolymer layer or to provide the fluoropolymer layer with a desired appearance. One of ordinary skill in the art will appreciate that a variety of commercial grades of fluoropolymers may be suitable for use in the conduits described herein. In certain embodiments of the conduit as further described herein, the fluoropolymer layer is formed from at least 75 wt% fluoropolymer, for example, at least 85 wt%, at least 90 wt%, or even at least 95 wt% fluoropolymer. In other embodiments as further described herein, the fluoropolymer layer consists essentially of fluoropolymer.

A variety of fluoropolymer materials may be used as the fluoropolymer of the fluoropolymer layer. One of ordinary skill in the art will appreciate that there are a variety of fluoropolymer materials that are resistant to hydrocarbon fuels, have acceptable fuel vapor characteristics, and are readily formed into tubes by extrusion. In certain particularly desirable embodiments, the fluoropolymer is a polymer or copolymer having monomer residues with free radical abstractable hydrogen atoms.

For example, in certain embodiments of the conduits as otherwise described herein, the fluoropolymer layer is formed of at least 75 wt% PVDF polymer (e.g., formed of or consisting essentially of at least 90 wt% PVDF polymer).; as used herein, one of ordinary skill in the art will understand that "at least 75% PVDF polymer" includes the use of a plurality of PVDF polymers at a total content of at least 75%; similar statements relating to other contents and other polymers will be similarly understood.) PVDF is a highly non-reactive and pure thermoplastic fluoropolymer PVDF is a particular plastic material in the fluoropolymer family, it is generally used in applications requiring the highest purity, strength and solvent resistance, acid, base and heat resistance and producing low smoke in the event of fire, because of its relatively low melting point, its melting process is easier as compared to other fluoropolymers, as used herein, PVDF polymer is a polymer having at least 40 mol% (e.g., at least 50 mol%) vinylidene fluoride residues, as used herein, as a homopolymer of vinylidene fluoride, or a copolymer of vinylidene fluoride with additional monomers such as commercially available from the tradenames of PVDF, such as "NOF, PVDF-polymers, such as commercially available in commercially available in the trade names" NOVELOCIF "(ORF-A, PVDF-A copolymer having a fluorinated copolymer having a ratio of at least 40 mol% of units, such as commercially available under the trade name of a fluorinated ethylene-A, such as a fluorinated ethylene-A copolymer, such as a fluorinated ethylene-A fluorinated ethylene-A fluoropolymer, such as a fluorinated ethylene-A copolymer having a fluorinated ethylene-A copolymer having a fluorinated ethylene-A fluorinated ethylene-A copolymer having a fluorinated ethylene-A fluorinated ethylene copolymer having a.

However, one of ordinary skill in the art will appreciate that other fluorinated materials may be used in the conduits of the present disclosure. For example, in certain embodiments of the pipe as otherwise described herein, the fluoropolymer of the fluoropolymer layer comprises: a PVDF polymer; fluorinated ethylene propylene copolymers ("FEP polymers"); copolymers of tetrafluoroethylene and perfluoropropyl vinyl ether ("PFA polymers"); copolymers of tetrafluoroethylene and perfluoromethyl vinyl ether ("MFA polymers"); copolymers of ethylene and tetrafluoroethylene ("ETFE polymers"); copolymers of ethylene and chlorotrifluoroethylene ("ECTFE polymers"); polychlorotrifluoroethylene ("PCTFE polymer"); terpolymers comprising tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride ("THV polymers"); or combinations or copolymers thereof. And one of ordinary skill in the art will appreciate that other fluorinated polymers may be used; desirably, the polymer has at least 75 mol%, at least 90 mol%, or even at least 95 mol% fluorinated monomer residues.

And in certain embodiments as otherwise described herein, the fluoropolymer layer may contain minor amounts (e.g., no more than 25 wt%) of other polymers having free-radical abstractable hydrogen atoms (i.e., no fluoropolymer). Desirably, such polymers are miscible with or otherwise compatible with the fluoropolymer. The use of such polymers may help to strengthen the bond of the fluoropolymer layer to the thermoplastic polyurethane layer.

The fluoropolymer layer can be formed to various thicknesses. Based on the disclosure herein, one of ordinary skill in the art will balance material properties, fuel vapor permeation properties, and cost, among other factors, to provide the desired thickness for the fluoropolymer layer. In certain embodiments of the tubing as further described herein, the fluoropolymer layer has a thickness in the range of 0.1mm to 10 mm. For example, in various embodiments as otherwise described herein, the fluoropolymer layer has a thickness in a range of 0.1mm to 5mm, or 0.1mm to 3mm, or 0.1mm to 2mm, or 0.1mm to 1mm, or 0.1mm to 0.5mm, or 0.2mm to 10mm, or 0.2mm to 5mm, or 0.2mm to 3mm, or 0.2mm to 2mm, or 0.2mm to 1mm, or 0.2mm to 0.5mm, or 0.5mm to 10mm, or 0.5mm to 5mm, or 0.5mm to 3mm, or 0.5mm to 2mm, or 1mm to 10mm, or 1mm to 5mm, or 1mm to 3mm, or 2mm to 10mm, or 2mm to 7mm, or 2mm to 5 mm. The fuel vapor permeability will be a function of the layer thickness, and the thickness required to provide a particular desired permeability will depend on the characteristics of the fluoropolymer layer. For example, for many commercial grades of PVDF-HFP, thicknesses in the range of 0.25mm to 0.4mm typically provide less than 15g/m at 23 deg.C²Fuel vapor permeability per day. Grades with fewer hexafluoropropylene and more vinylidene fluoride monomer units may require thicker layers to achieve the same permeability.

As noted above, the thermoplastic layer is formed from a substantial amount (i.e., at least 75 weight percent) of a thermoplastic (e.g., a thermoplastic polyurethane, a thermoplastic polyester, and/or a thermoplastic polyamide). One of ordinary skill in the art will appreciate that a variety of additional materials (e.g., stabilizers, waxes, etc.) may be used, for example, in the thermoplastic layer to help treat or provide the fluoropolymer layer with a desired appearance or to reduce the tackiness of the thermoplastic polyurethane layer. In certain embodiments of the conduit as further described herein, the thermoplastic layer is formed from at least 95 wt% thermoplastic. In other embodiments as further described herein, the thermoplastic polyurethane layer consists essentially of a thermoplastic.

In certain embodiments as further described herein, the thermoplastic is a thermoplastic polyurethane (e.g., a thermoplastic polyurethane elastomer), a thermoplastic polyester (e.g., a thermoplastic polyester elastomer), and/or a thermoplastic polyamide (e.g., a thermoplastic polyamide elastomer).

In certain embodiments as otherwise described herein, the thermoplastic comprises (or is) a thermoplastic polyurethane (e.g., a thermoplastic polyurethane elastomer).

In certain embodiments as further described herein, the thermoplastic layer is at least 75 wt% thermoplastic polyurethane (e.g., at least 75 wt% polyether-type thermoplastic polyurethane). In certain such embodiments, the thermoplastic layer is at least 95 wt% thermoplastic polyurethane (e.g., at least 95 wt% polyether-type thermoplastic polyurethane).

In certain embodiments as otherwise described herein, the thermoplastic comprises (or is) a thermoplastic polyester (e.g., a thermoplastic polyester elastomer).

In certain embodiments as further described herein, the thermoplastic layer is at least 75 wt% of a thermoplastic polyester. In certain such embodiments, the thermoplastic layer is at least 95 wt% thermoplastic polyester.

In certain embodiments as otherwise described herein, the thermoplastic comprises (or is) a thermoplastic polyamide (e.g., a thermoplastic polyamide elastomer).

In certain embodiments as further described herein, the thermoplastic layer is at least 75 wt% of a thermoplastic polyamide. In certain such embodiments, the thermoplastic layer is at least 95 wt% thermoplastic polyamide.

A variety of thermoplastic polyurethane materials may be used as the thermoplastic polyurethane material of the thermoplastic layer. One of ordinary skill in the art will appreciate that there are a variety of thermoplastic polyurethane materials that provide the desired mechanical properties to the tube and that are readily formed into a tube by extrusion. Based on the present disclosure, one of ordinary skill in the art will select an appropriate thermoplastic polyurethane to provide any other desired properties, such as: sufficient fuel/chemical resistance; flexibility; low glass transition temperatures suitable for low temperature applications (e.g., using soft segment phases); sufficient weatherability/resistance to ultraviolet light; and sufficient mechanical strength to withstand installation, keep the fitting secure and maintain a seal in use.

Generally, thermoplastic polyurethanes are formed by reacting a polyol with an isocyanate. As will be understood by those of ordinary skill in the art, the overall characteristics of the polyurethane will depend on, among other things, the type of polyol and isocyanate, the degree of crystallinity in the polyurethane, the molecular weight of the polyurethane, and the chemical structure of the polyurethane backbone. Many typical thermoplastic polyurethanes also include chain extenders such as 1, 4-butanediol, which can form hard segment blocks in the polymer chain. Polyurethanes can be generally classified as thermoplastic polyurethanes or thermoset polyurethanes, depending on the degree of crosslinking present. Depending on the function of the reactants, thermoplastic urethanes do not have a first degree of crosslinking, while thermoset polyurethanes have a different degree of crosslinking. As used herein, at least 95 mole%, at least 99 mole%, or even substantially all of the polyol component of a "thermoplastic polyurethane" is difunctional. As described in more detail below, such materials can be crosslinked by electron beam treatment; despite this crosslinking, the present disclosure regards such materials as "thermoplastic".

Thermoplastic polyurethanes are typically based on methylene diisocyanate or toluene diisocyanate and include both polyester grade polyols and polyether grade polyols thermoplastic polyurethanes can be formed by a "one-shot" reaction between isocyanate and polyol (e.g., with AN optional chain extender) or by a "prepolymer" system in which a curative is added to a partially reacted polyol isocyanate complex to complete the polyurethane reaction.

In certain embodiments of the conduit as described herein, the thermoplastic polyurethane is a polyether thermoplastic polyurethane, a polyester thermoplastic polyurethane, or a combination or copolymer thereof. Typically, the thermoplastic polyurethane used for the fuel line is an ester-type thermoplastic polyurethane. The ester-type thermoplastic polyurethanes may be based on different compositions of substituted or unsubstituted Methane Diisocyanate (MDI) and substituted or unsubstituted dihydric alcohols (glycols).

However, in certain advantageous embodiments of the conduit as otherwise described herein, the thermoplastic polyurethane of the thermoplastic polyurethane layer is a polyether polyurethane. Polyether-type thermoplastic polyurethanes may be more resistant to hydrolytic degradation than polyester-type thermoplastic polyurethanes. The fact that they generally have a lower hydrocarbon resistance makes polyether-type thermoplastic polyurethanes generally less suitable than polyester-type polyurethanes used in conventional fuel pipelines. And the softness of certain grades of polyether thermoplastic polyurethanes may make them less suitable for use in the pipes described herein. Nonetheless, the methods and conduits described herein may allow for the use of polyether-type materials.

Based on the present disclosure, one of ordinary skill in the art will select an appropriate thermoplastic polyester to provide any other desired properties, such as sufficient fuel/chemical resistance, flexibility, low glass transition temperature suitable for low temperature applications (e.g., using soft segments), sufficient weatherability/ultraviolet light resistance, and sufficient mechanical strength to withstand installation, keep the fitting stationary, and maintain a seal in use.

A variety of thermoplastic amide materials may be used as the thermoplastic material of the thermoplastic layer. One of ordinary skill in the art will appreciate that there are a variety of thermoplastic amide materials that provide the desired mechanical properties to the pipe and that are readily formed into a pipe by extrusion. Based on the present disclosure, one of ordinary skill in the art will select an appropriate thermoplastic amide to provide any other desired properties, such as: sufficient fuel/chemical resistance; flexibility; low glass transition temperatures suitable for low temperature applications (e.g., using soft segment phases); sufficient weatherability/resistance to ultraviolet light; and sufficient mechanical strength to withstand installation, keep the fitting secure and maintain a seal in use. In certain embodiments as further described herein, the thermoplastic amide is a polyether-type thermoplastic amide, such as an elastomer available from arkema under the trade name PEBAX.

Notably, the pipes described herein can be made using relatively soft thermoplastic materials (i.e., as compared to conventional pipes). For example, in certain embodiments of the conduits described herein, the thermoplastic of the thermoplastic layer may have a shore a hardness of less than 80, e.g., less than 78, or less than 75, or even less than 70. Notably, the conduits described herein may be manufactured using softer materials, yet still be sufficiently strong. And the use of soft materials may allow for narrower bend radii, which may be advantageous. Of course, materials of conventional hardness may also be used. Thus, in certain embodiments of the pipe as otherwise described herein, the thermoplastic of the thermoplastic layer may have a shore a hardness in the range of 50 to 95, for example in the range of 50 to 80, or 50 to 78 or 50 to 75, or 50 to 70, or 60 to 95, or 60 to 80, or 60 to 78, or 60 to 75, or 60 to 70, or 70 to 95, or 70 to 80.

The thermoplastic layer can be formed to various thicknesses. Based on the disclosure herein, one of ordinary skill in the art will balance material properties and cost, among other factors, to provide a desired thickness for the thermoplastic layer. In certain embodiments of the pipe as further described herein, the thermoplastic layer has a thickness in a range from 0.5mm to 20 mm. For example, in various embodiments as otherwise described herein, the thermoplastic layer has a thickness in a range of 0.5mm to 10mm, or 0.5mm to 5mm, or 0.5mm to 3mm, or 0.5mm to 2mm, or 1mm to 20mm, or 1mm to 10mm, or 1mm to 5mm, or 1mm to 3mm, or 2mm to 20mm, or 2mm to 10mm, or 2mm to 7mm, or 2mm to 5mm, or 5mm to 20mm, or 5mm to 15mm, or 5mm to 10mm, or 10mm to 20 mm.

Those of ordinary skill in the art will appreciate that the conduits of the present disclosure may be configured in a number of ways. For example, in certain embodiments as otherwise described herein, and as shown in fig. 1, the inner surface of the fluoropolymer layer forms the inner surface of the conduit. The fluoropolymer layer can be made of a material that is sufficiently resistant to hydrocarbon fuels so that a separate liner layer is not required. Of course, in other embodiments, the annular cross-section further comprises one or more inner annular polymer layers disposed on the inner surface of the fluoropolymer layer. This embodiment is shown in a schematic cross-sectional view in fig. 3. Here, annular cross-section 310 includes not only fluoropolymer layer 330 and thermoplastic layer 340, but also one or more (here, one) inner annular polymer layers 350 disposed on the inner surface of the fluoropolymer layer. Although not the innermost layer, the fluoropolymer layer can still provide a barrier to fuel vapor. A wide variety of materials may be used in the one or more inner annular polymer layers. For example, in certain embodiments, the inner annular polymer layer is formed from a thermoplastic polyurethane, a thermoplastic polyether, and/or a thermoplastic polyamide, which may be the same or different than, for example, the thermoplastic polyurethane, thermoplastic polyether, and/or thermoplastic polyamide of the thermoplastic layer. Such a three-layer pipe is described in U.S. patent No. 7866348, which is incorporated herein by reference in its entirety; those of ordinary skill in the art will appreciate that the piping designs described in this U.S. patent may be adapted as additional examples of the piping of the present disclosure.

Similarly, in certain embodiments as otherwise described herein, and as shown in fig. 1, the outer surface of the thermoplastic layer forms the outer surface of the pipe. The thermoplastic layer may be made of a material that is sufficiently strong that a separate protective layer is not required. Of course, in other embodiments, the annular cross-section further comprises one or more outer annular polymer layers disposed on the outer surface of the fluoropolymer layer. This embodiment is shown in schematic cross-sectional view in fig. 3 at 4. here, the annular cross-section 410 includes not only the fluoropolymer layer 430 and the thermoplastic layer 440, but also one or more (here one) inner annular polymer layers 460 disposed on the outer surface of the thermoplastic layer. Although not the outermost layer, the thermoplastic layer may still provide the desired mechanical properties to the pipe. A wide variety of materials may be used in the one or more outer annular polymer layers. For example, in certain embodiments, the outer annular polymer layer is formed from poly (vinyl chloride). Such a three-layer pipe is described in U.S. patent No. 8092881, which is incorporated herein by reference in its entirety; those of ordinary skill in the art will appreciate that the piping designs described in this U.S. patent may be adapted as additional examples of the piping of the present disclosure.

In certain embodiments, the material volume of the conduit is at least 50%, at least 70%, at least 90%, or even at least 95% comprised of the thermoplastic layer and the fluoropolymer layer.

Notably, the conduits of the present disclosure do not require a coupling agent or an adhesive layer to adhere the thermoplastic layer to the fluoropolymer layer.

As described in more detail below, the tubing of the present disclosure may be made by extrusion. Thus, it can be made in a variety of lengths. In certain embodiments, the length of flexible pipe as further described herein is at least 1 m. In various embodiments as further described herein, the length of flexible pipe is at least 2m, at least 3m, at least 5m, or even at least 10 m.

The conduits of the present disclosure can be made in a variety of sizes. For example, in certain embodiments of the conduit as otherwise described herein, the inner diameter of the annular cross-section is in the range of 0.5mm to 40 mm. In various particular embodiments of the flexible conduit as further described herein, the annular cross-section has an inner diameter in the range of 0.5mm to 30mm, or 0.5mm to 20mm, or 0.5mm to 15mm, or 0.5mm to 10mm, or 0.5mm to 5mm, or 1mm to 40mm, or 1mm to 30mm, or 1mm to 20mm, or 1mm to 15mm, or 1mm to 10mm, or 5mm to 40mm, or 5mm to 30mm, or 5mm to 20mm, or 5mm to 15mm, or 5mm to 10mm, or 10mm to 40mm, or 10mm to 30mm, or 10mm to 20 mm. Similarly, in certain embodiments of the conduit as otherwise described herein, the wall thickness of the annular cross-section is in the range of 0.5mm to 15 mm. In various particular embodiments of the flexible conduit as further described herein, the wall thickness of the annular cross-section is in a range of 0.5mm to 15mm, or 0.5mm to 10mm, or 0.5mm to 8mm, or 0.5mm to 5mm, or 0.5mm to 3mm, or 0.5mm to 2mm, or 1mm to 25mm, or 1mm to 15mm, or 1mm to 10mm, or 1mm to 8mm, or 1mm to 5mm, or 1mm to 3mm, or 2mm to 25mm, or 2mm to 15mm, or 2mm to 10mm, or 2mm to 8mm, or 2mm to 5mm, or 5mm to 25mm, or 5mm to 15mm, or 5mm to 10mm, or 10mm to 25mm, or 10mm to 15mm, or 15mm to 25 mm.

The description of the pipe herein implies an interface between the thermoplastic layer and the fluoropolymer layer (i.e., at the outer surface of the fluoropolymer layer and the inner surface of the thermoplastic layer). As will be appreciated by those of ordinary skill in the art, in many real-world samples, some mixing of the materials at the interface may occur. Nevertheless, one of ordinary skill in the art would be able to discern where one layer ends and another layer begins.

As described above, the fluoropolymer layer is covalently bonded to the thermoplastic layer. In certain desirable embodiments, and as described in more detail below, covalent bonding of the fluoropolymer layer to the thermoplastic layer is achieved by treatment with an electron beam. As one of ordinary skill in the art will appreciate, treatment with an electron beam will provide a unique type of bonding between the thermoplastic and the fluoropolymer. Without intending to be bound by theory, the electron beam causes energetic electrons to collide with the material, which initiates the generation of free radicals on the polymer backbone via the extraction of atoms (e.g., hydrogen atoms) from the polymer. The two radical species can combine (terminate) to form a new bond. New bonds formed between different polymer chains will result in covalent bonding of the materials; when this occurs between the thermoplastic polymer chains and the fluoropolymer chains, covalent bonds are formed between the layers. Covalent bonding of the fluoropolymer layer to the thermoplastic layer can be through multiple > CH-moieties and/or > CF-moieties of the fluoropolymer, where "-" indicates bonding to the polyurethane and ">" indicates bonding to the fluoropolymer chain. For example, in certain embodiments, the covalent bonding of the fluoropolymer layer to the thermoplastic layer is via a plurality of > CH-moieties and/or > CF-moieties of the fluoropolymer to a plurality of > CH-moieties of a soft segment of the thermoplastic (e.g., a polyether segment of the thermoplastic). In certain desirable embodiments, substantially no separate crosslinking agent forms covalent bonds between the fluoropolymer layer and the thermoplastic layer. One of ordinary skill in the art will appreciate that some degree of crosslinking may also occur to the layer itself.

The inventors have determined that such covalent bonding between layers can advantageously help make the layers more resistant to separation or delamination when exposed to fuel. For example, in certain embodiments as otherwise described herein, a length of tubing does not exhibit significant delamination when immersed in CE10 fuel at 40 ℃ for three months. In certain embodiments as further described herein, the lamination resistance of the length of tubing is at least four times that of an equivalent tubing lacking covalent bonds between the fluoropolymer layer and the thermoplastic layer. For example, a reference tube identical to the present tube but not electron beam treated can be prepared for comparison purposes.

The use of a fluoropolymer layer (e.g., a fluoropolymer layer using PVDF polymer) may provide the pipes described herein with excellent resistance to hydrocarbon fuel vapor permeation. For example, in certain embodiments as otherwise described herein, the permeability of the pipe does not exceed 15g/m under SAEJ1737 test conditions²A day, e.g. 7g/m²Daily or 5g/m²The day is.

As will be understood by those of ordinary skill in the art, various other additives may be present in these layers, such as residual polymerization agents (i.e., from polymerization of the thermoplastic and/or fluoropolymer), antioxidants, flame retardants, acid scavengers, antistatic agents, and processing aids (such as melt flow index enhancers).

Another aspect of the present disclosure is a method for making a length of flexible pipe as described herein. The method comprises the following steps: providing a length of pipe having an annular cross-section with an inner surface and an outer surface, the annular cross-section comprising: an annular fluoropolymer layer formed from at least 75 wt% fluoropolymer (e.g., at least 75 wt% PVDF polymer) having an outer surface and an inner surface; and an annular thermoplastic layer disposed about the annular fluoropolymer layer and formed from at least 75 wt% thermoplastic, the thermoplastic layer having an inner surface in contact with the outer surface of the fluoropolymer layer; the length of tubing is treated with an electron beam. The structure of the pipe, the composition of the fluoropolymer layer, and the composition of the thermoplastic layer may be as otherwise described herein (e.g., as in any combination of the appended examples 2-32).

Based on the disclosure herein, one of ordinary skill in the art will select an appropriate electron beam treatment to provide a tube that is resistant to delamination. For example, in certain embodiments, the electron beam treatment is performed at a dose of at least 5Mrad, such as at least 9 Mrad. In certain embodiments as further described herein, the electron beam dose is in a range of 5Mrad to 50Mrad, or 9Mrad to 50Mrad, or 13Mrad to 50Mrad, or 5Mrad to 30Mrad, or 9Mrad to 30Mrad, or 13Mrad to 30Mrad, or 5Mrad to 20Mrad, or 9Mrad to 20Mrad, or 13Mrad to 20Mrad, or 9Mrad to 17 Mrad. One of ordinary skill in the art can adjust the treatment time to provide the desired dosage. In certain embodiments as further described herein, the energy of the electron beam is at least 1MeV, for example, in the range of 1-20 MeV.

One of ordinary skill in the art may otherwise prepare the conduits of the present disclosure using conventional methods. For example, in certain embodiments, the length of tubing is formed by co-extruding a fluoropolymer layer with a thermoplastic layer. Conventional extrusion methods, such as those described in U.S. patent No. 7866348 and U.S. patent No. 8092881, may be used to provide a length of flexible tubing.

In certain desirable embodiments, electron beam treatment forms covalent bonds between the fluoropolymer layer and the thermoplastic layer, as described above.

Since covalent bonding of the layers may be mediated by free radicals, in some embodiments it may be desirable to include a free radical initiator in the thermoplastic layer and/or fluoropolymer, i.e., prior to treatment with an electron beam. The use of free radical initiators makes it possible to obtain a given electron beam doseSuitable free radical initiators include, for example, benzophenone, p-and o-methoxybenzophenone, dimethylbenzophenone, dimethoxybenzophenone, diphenoxybenzophenone, acetophenone, o-methoxyacetophenone, acenaphthenequinone, methylethylketone, cyclopentanone, n-hexanoylbenzene, α -benzophenone, p-morpholinopropiophenone, dibenzosuberone, 4-morpholinobenzophenone, benzoin methyl ether, 3-o-morpholinobenzophenone, p-diacetylbenzene, 4-aminobenzophenone, 4' -methoxyacetophenone, α -tetralone, 9-acetylphenanthrene, 2-acetylphenanthrene, 10-thioxanthone, 3-acetylphenanthrene, 3-acetylindole, 9-fluorenone, 1-indanone, 1, 3, 5-triacetylbenzene, 9-thioxanthone, 7-H-benzo [ de ] de]Anthracen-7-one, benzoin tetrahydropyranyl ether, 4 ' -bis (dimethylamino) benzophenone, 1 ' -acetonaphthone, 2 ' -acetonaphthone, acetonaphthone and 2, 3-butanedione, benzo [ a]Anthracene-7, 12-dione, 2-dimethoxy-2-phenylacetophenone, α, α -diethoxyacetophenone, α, α -dibutoxyacetophenone, anthraquinone, isopropylthioxanthone and the like polymerization initiators include poly (ethylene/carbon monoxide), oligo [ 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) -phenyl ] -1]Acetone (II)]Polymethylvinyl ketone and polyvinyl aryl ketone. Additional free radical initiators include: anthrone; xanthone; irgacure of Ciba Geigy^TMA series of initiators, including 2, 2-dimethoxy-2-phenylacetophenone (Irgacure)^TM651) 1-hydroxycycloethylphenylacetone (Irgacure)^TM184) And 2-methyl-1- [4- (methylthio) phenyl]-2-morpholinyl-1-propanone (Irgacure)^TM907). The most preferred initiators have low mobility from the formulated resin, and have low vapor pressure and low degree of decomposition at the extrusion temperature, and sufficient solubility in the material to yield good efficiency. Many of the familiar initiators can be readily modified in vapor pressure and solubility or polymer compatibility if derivatized. For example, derivatized initiators include higher molecular weight derivatives of benzophenone, such as 4-phenylbenzophenone, 4-allyloxybenzophenone, and the like,4-dodecyloxybenzophenone, and the like. When present, the initiator is present at a level of from 0.1 to 2 wt%.

Advantageously, however, the inventors of the present disclosure have determined that it is not necessary to include a free radical initiator. Thus, in other embodiments as further described herein, the thermoplastic polyurethane layer and the fluoropolymer are substantially free (e.g., less than 0.1 wt%, less than 0.05 wt%, or less than 0.01 wt%) of free radical initiators, i.e., upon electron beam treatment.

Another aspect of the present disclosure is a flexible pipe made as described herein.

The flexible conduit as described herein is particularly useful in the transport of hydrocarbon fuels. Accordingly, another aspect of the present disclosure is a method for transporting a hydrocarbon fuel, the method comprising: providing a flexible pipe as described herein; and passing the hydrocarbon fuel through the conduit from the first end to the second end of the conduit. A wide variety of hydrocarbon fuels (e.g., gasoline, diesel fuel, kerosene) can be used with the conduits of the present disclosure.

The conduits described herein may be used to transport gasoline and other hydrocarbon fuels in engines such as non-automotive engines. The present disclosure provides a low permeability design that can be configured to meet the US EPA and california permeability requirements that require particularly stringent permeability. Accordingly, another aspect of the present disclosure is a fuel-powered apparatus that includes a fuel tank, a fuel-powered engine, and a length of tubing fluidly connecting the fuel tank with the fuel-powered engine of the present disclosure (i.e., configured to transfer fuel from the fuel tank to the engine). The engine may be an automotive engine or, in other embodiments, may be a non-automotive engine. Non-automotive equipment includes equipment such as motorcycles, four-wheeled and other recreational vehicles, lawn tractors, string trimmers, leaf blowers, snow blowers, lawn mowers, tillers, chain saws, and other yard care equipment.

Examples of the invention

Various aspects of the conduits and methods of the present disclosure are further described with reference to the non-limiting examples described below.

Example 1

Prototype 1 and prototype 2 are two-layer fuel pipes with an ester-based Thermoplastic Polyurethane (TPU) jacket and a polyvinylidene fluoride (PVDF) -based liner made by co-extrusion.

Without intending to be bound by theory, the inventors of the present disclosure believe that the liner and jacket layers are bonded together during the coextrusion process. The thermoplastic polyurethane and PVDF copolymer may interdiffuse at the resulting interface. Due to non-covalent interactions between the two polymers, adhesion may occur at the interface. For example, a dipole-dipole interaction occurs between the carbonyl groups present in the soft segment of the ester-based thermoplastic polyurethane and the C-F bonds in the PVDF. However, these interactions are reversible and after prolonged exposure to fuels (such as CE10), the liner may separate from the jacket due to loss of interlayer adhesion. This is undesirable.

The fuel channels (3/32 "ID and 3/16" OD) were electron beam treated under NEO beams (Midfield, Ohio) using a voltage of 4.5MeV and a beam current of 34mA to provide two different doses (about 10Mrad and about 14 Mrad).

The e-beam treated tubing samples and untreated control samples were immersed in CE10 fuel at 40 ℃ and examined weekly for delamination. The results of this evaluation are summarized in the following table:

while the untreated control sample showed delamination over several weeks, the treated pipe showed no delamination at 3 months of fuel exposure. Fig. 5 is a photograph of a layered prototype 2 sample, and fig. 6 is a photograph of a layered prototype 1 sample. Fig. 7 is a set of photographs of the treated samples, which showed no delamination. These results show that electron beam irradiation helps prevent delamination from occurring in prototype 1 and prototype 2 when exposed to fuel.

Example 2

The fuel tubes (3/32 "ID and 3/16" OD) were electron beam treated under NEO beams (Midfield, Ohio) using a voltage of 4.5MeV and a beam current of 34mA to achieve two different levels of total irradiation (about 10Mrad and about 14 Mrad).

The treated tubing and untreated control samples were immersed in CE10 fuel at 40 ℃ and examined weekly for stratification. The results of this evaluation are summarized in the following table:

material	Is there a layering?
		Prototype 3-non-irradiated	At 1 week
Prototype 3-10MRad	No demixing at 1 month
		Prototype 3-14MRad	No demixing at 1 month

Delamination was observed when the prototype 3 control sample was used during the first week of the immersion check. All irradiated samples did not show any delamination in the week 2 examination. FIG. 8 is a set of photographs, from top to bottom, of untreated samples after one week, 10Mrad treated samples after two weeks, and 14Mrad treated samples after two weeks. These results show that the electron beam treatment helps to prevent delamination in prototype 3.

Example 3

UltraFlex B and Kynar2500 (PVDF-HFP copolymer) were each extruded into film samples using a voltage of 4.5MeV and a beam current of 34mA, the films were electron beam treated under NEO beams (Midfield, Ohio) to achieve two different levels of total irradiation (about 10Mrad and about 14 Mrad.) then the films and untreated control films were permeation tested using a permeation jar with a glass body and a lid having an opening at the top of the lid, see FIG. 9. the top of the lid of the permeation jar was a trace on the film sample (0.005 inches thick) along which the sample was cut and then loaded into the lid of the jar. 30m L of CE10 fuel (formulation: 450m L toluene, 450m L isooctane, 100m L ethanol) was added to the jar and the initial mass of the lid with the sample was screwed down (i.e., the jar, lid and the fuel loss was taken out of the jar together with the sample in a jar and weighed oven for one week, the weight loss of the jar was calculated using the following equation of the weight of the jar per gram²Day one:

fig. 10 and 11 provide permeation data for various electron beam doses for UltraFlex B and Kynar2500, respectively. Error bars are +/-1 standard deviation. These data indicate that the e-beam treated film samples did not exhibit significantly different permeation levels than the untreated samples. This indicates that at these doses, the electron beam treatment did not substantially alter the fuel vapor barrier properties of the film.

Example 4

Fig. 10 and 11 provide permeation data for various electron beam doses for UltraFlex B and Kynar2500, respectively. Error bars are +/-1 standard deviation. These data indicate that the e-beam treated film samples did not exhibit significantly different permeation levels than the untreated samples. This indicates that at these doses, the electron beam treatment did not substantially alter the fuel vapor barrier properties of the film. The fuel channels (3/32 "ID and 3/16" OD) were electron beam crosslinked under NEO beams (Midfield, Ohio) using a voltage of 4.5MeV and a beam current of 34mA to achieve a total irradiation of 2 Mrad.

The irradiated pipe samples and the unirradiated control samples were immersed in CE10 fuel at 50 ℃ and periodically (weekly) checked for delamination.

The following table summarizes the results of this evaluation:

example 5

The three-layer fuel channels (3/32 "ID and 3/16" OD) were electron beam crosslinked under NEO beams (Midfield, Ohio) using a voltage of 4.5MeV and a beam current of 34mA to achieve a total irradiation of 2 Mrad.

The irradiated pipe samples and the unirradiated control samples were immersed in CE10 fuel at 50 ℃ and periodically (weekly) checked for delamination. The results are summarized below

Material	Is there a layering?
		PVC/TPU/PVDF-unirradiated	At 1 week
PVC/TPU/PVDF-2Mrad	No delamination at 2 months

In other respects, the present disclosure provides the following non-limiting embodiments, which may be combined in any logically and technically consistent manner.