WO2016024938A1

WO2016024938A1 - Fluoropolymer compositions and uses thereof

Info

Publication number: WO2016024938A1
Application number: PCT/US2014/050452
Authority: WO
Inventors: Masahide Yodogawa; David J. Lavanga; Dennis G. MURPHY
Original assignee: Agc Chemicals Americas, Inc.
Priority date: 2014-08-09
Filing date: 2014-08-09
Publication date: 2016-02-18

Abstract

A fluoropolymer composition includes a first fluoropolymer having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. The fluoropolymer composition also includes a second fluoropolymer that is different than the first fluoropolymer. The fluoropolymer composition further includes a crosslinker. The fluoropolymer composition may be included in an insulated conduit for use in offshore, deep water environments. The insulated conduit includes a continuous steel pipe having one or more pipe sections. The steel pipe has an outer surface and an inner surface. The insulated conduit includes the fluoropolymer composition disposed about the steel pipe for providing a thermal insulation layer.

Description

FLUOROPOLYMER COMPOSITIONS AND USES THEREOF

FIELD OF THE INVENTION

[0001] The present invention generally relates to a fhioropolymer composition. More specifically, the present invention relates to a fluoropolymer composition which may be used for a thermal insulation layer about an insulated conduit.

BACKGROUND

[0002] Transport conduits are commonly used to transport liquids, such as oil, in the oil and gas industry. Often these transport conduits operate in offshore, deep water environments (e.g. environments having a high temperature (e.g. greater than 130°C (e.g. 200°C) and at depths exceeding 1,000 meters). Typically, a thermal insulation layer is applied to the transport conduit to provide controlled energy loss and maintain a temperature of the liquid in the deep water environments. Maintaining the temperature of the liquid in the transport conduit prevents the formation of hydrates and waxes in the liquid, particularly when the liquid is oil. If present, the hydrates and/or waxes typically decrease pumping efficiency of the liquid. Conventional thermal insulation layers are typically not capable of maintaining the temperature of the liquid in the transport conduit when the temperature of the liquid approaches 200°C. As such, there remains an opportunity to develop a composition for a thermal insulation layer such that the transport conduit can be utilized in deep water environments with liquid temperatures at or above 200°C.

SUMMARY OF THE INVENTION AND ADVANTAGES

[0003] The present disclosure provides a fluoropolymer composition. The fluoropolymer composition includes a first fluoropolymer having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. The fluoropolymer composition also includes a second fluoropolymer that is different than the first fluoropolymer. The fluoropolymer composition further includes a crosslinker.

[0004] The present disclosure also includes an insulated conduit for use in offshore, deep water environments. The insulated conduit includes a continuous steel pipe having one or more pipe sections. The steel pipe has an outer surface and an inner surface. The insulated conduit also includes the fluoropolymer composition disposed about the steel pipe for providing a thermal insulation layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description, when considered in connection with the accompanying drawings.

[0006] Figure 1 is a cross-sectional view of an embodiment of a first insulated conduit.

[0007] Figure 2 is a cross-sectional view of an embodiment of the first insulated conduit.

[0008] Figure 3 is a cross-sectional view of an embodiment of a second insulated conduit.

[0009] Figure 4 is a cross-sectional view of an embodiment of the second insulated conduit.

DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure provides a first insulated conduit 10 (hereinafter the insulated conduit 10) for use in offshore, deep water environments (e.g. environments having a high temperature (e.g. greater than 130°C (e.g. 200°C) and at depths exceeding 1,000 meters). The insulated conduit 10 includes a continuous steel pipe 12 having one or more pipe sections. The steel pipe 12 has an outer surface and an inner surface. The insulated conduit 10 also includes a first fluoropolymer composition 14 (hereinafter the fluoropolymer composition 14) disposed about the steel pipe 12 for providing a thermal insulation layer.

[0011] The present disclosure also provides the fluoropolymer composition 14 itself (i.e., the present disclosure provides the fluoropolymer composition 14 independent of the inclusion of the fluoropolymer composition 14 in the insulated conduit 10). The fluoropolymer composition 14 includes a first fluoropolymer. The first fluoropolymer has an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. The fluoropolymer composition 14 also includes a second fluoropolymer that is different from the first fluoropolymer. The fluoropolymer composition 14 further includes a crosslinker.

[0012] The first fluoropolymer may be any polymer containing a fluorine atom bonded to a carbon atom and having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. In certain embodiments, the first fluoropolymer is a tetrafluoroethylene/propylene copolymer (TFE/P), a tetrafluoroethylene/propylene/vinylidene fluoride copolymer, a vinylidene fluoride/hexafluoropropylene copolymer, a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene copolymer, a vinylidene fluoride/tetrafluoroethylene/perfluoroalkylvinylether copolymer, a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene/perfluoroalkylvinylether copolymer, a tetrafluoroethylene/ethylene/perfluoroalkylvinylether copolymer, a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene/ethylene/perfluoroalkylvinylether copolymer, a vinylidenefluoride/chlorotrifluoroethylelne copolymer, a perfluoroalkoxy copolymer of polytetrafluoroethylene and perfluoro alkylvinyl ether, a polytetrafluoroethylene, a fluorinated ethylene propylene, a tetrafluoroethylene/hexafluoropropylene copolymer, a polyvinylidene fluoride, a polyvinyl fluoride, an ethylene/tetrafluoroethylene copolymer, an ethylene/tetrafluoroethylene/hexafluoropropylene copolymer, an ethylene/chlorotrifluoroethylene copolymer, a polychlorotrifluoroethylene, and combinations thereof. Typically the first fhioropolymer is TFE/P. TFE/P is the reaction product of tetrafluoroethylene and propylene.

[0013] As stated above, the first fhioropolymer has an absorption peak at from 1,640 to

1,700 cm-1 in its infrared absorption spectrum. In certain embodiments, the first fhioropolymer has an absorption peak at from 1,660 to 1,700 cm-1 on the infrared absorption spectrum. Alternatively, the first fhioropolymer has an absorption peak at from 1,680 to 1,700 cm-1 on the infrared absorption spectrum. The absorption peak within such a range is attributable to an increase in carbon-carbon unsaturated bonds.

[0014] In certain embodiments, the first fhioropolymer is formed by heat-treating a mixture comprising a precursor of the first fhioropolymer and a first organic peroxide. One procedure for heat-treating the mixture is disclosed in U.S. Pat. No. 8,044,145, which is hereby incorporated by reference in its entirety. Typically, in these embodiments, the precursor of the first fhioropolymer is TFE/P. In certain embodiments, when the first fhioropolymer is prepared by heat-treating, the precursor of the first fhioropolymer and the first organic peroxide are heated at a temperature of from 110 to 380°C for about 10 seconds to about 3 hours, alternatively from 10 seconds to 30 minutes, or alternatively from 10 seconds to 15 minutes. The heat-treating may be carried out using any device capable of reaching and maintaining a temperature profile of from 110 to 380°C for about 10 seconds to about 3 hours. Suitable devices include, but are not limited to, a heating oven, an extruder, and a kneader. The mixture may also be kneaded while the mixture is heated from 110 to 380°C for about 10 seconds to about 3 hours. Heat-treating the mixture of the precursor of the first fhioropolymer and the first organic peroxide produces the first fhioropolymer having an absorption peak at from 1,640 to 1,700 cm-1 in the infrared absorption spectrum. Without being held to any particular theory, it is believed that carbon- carbon unsaturated bonds are formed during the heat-treating process by withdrawing hydrogen atoms from the precursor of the first fhioropolymer.

[0015] A person have ordinary skill in the art would know suitable methods for measuring the absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. As one example, the absorption peak may be measured by taking a one gram sample of the first fhioropolymer, pressing the one gram sample to a thickness of about 0.2 mm by hot pressing at 170° C, and measuring the infrared absorption spectrum with an FT-IR spectrometer. The intensity of the absorption peak at from 1,640 to 1,700 cm-1 may be calculated from measuring the height of a perpendicular line that extends from the apex of the absorption occurring from 1,640 to 1,700 cm-1 to another line that connects the intensities at two points of 1,630 cm-1 and 1,710 cm-1. When a one gram sample of the first fhioropolymer is pressed to a thickness of about 0.2 mm by hot pressing at 170° C, the first fhioropolymer has a peak intensity represented by absorbance of from 0.01 to 5.0, alternatively from 0.02 to 2.0, alternatively from 0.03 to 1.8, or alternatively from 0.05 to 1.5.

[0016] The precursor of the first fhioropolymer is a fhioropolymer that does not have an absorption peak at from 1,640 to 1,700 cm-1 in the infrared absorption spectrum. The absence of the absorption peak is understood to mean that a hot pressed sample of the precursor of the first fhioropolymer has an absorption intensity less than 0.05, alternatively less than 0.02, or alternatively less than 0.01 (i.e., the absorption peak is absent in the precursor of the first fhioropolymer). The difference in the peak intensity of the absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1 is believed to be due to an increased amount of the carbon-carbon unsaturated bonds that are produced during the heat-treatment of the precursor of the first fluoropolymer and the first organic peroxide. In other words, the first fluoropolymer has a greater amount of carbon-carbon unsaturated bonds as compared to the precursor of the first fluoropolymer.

[0017] The first organic peroxide may be any organic peroxide. In certain embodiments, the first organic peroxide has a temperature of half-life of one minute (a temperature at which its half-life is one minute) from 110 to 300°C, alternatively 110 to 250°C, or alternatively from 110 to 200°C.

[0018] Specific examples of the first organic peroxide include, but are not limited to, dicumyl peroxide, l,3-bis(tert-butylperoxyisopropyl)benzene, tert-butylcumyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, tert-butylperoxybenzoate, 2,5-dimethyl-2,5- dibenzoyl peroxyhexane, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane and dibenzoyl peroxide and combinations thereof. In certain embodiments, the first organic peroxide is dicumyl peroxide, l,3-bis(tert-butylperoxyisopropyl)benzene, tert-butylcumyl peroxide, tert- butylperoxybenzoate 2,5-dimethyl-2,5-dibenzoyl peroxyhexane and combinations thereof. One example of a preferred first organic peroxide is dicumyl peroxide manufactured by NOF Corporation under the trade name PERCUMYL D.

[0019] During the heat-treating process, the first organic peroxide is present in an amount of from 0.1 to 10 or from 0.5 to 7, parts by weight based on 100 parts by weight of the precursor of the first fluoropolymer. Including the first organic peroxide in the amount described above produces the carbon-carbon unsaturated bonds in the first fluoropolymer.

[0020] The first fluoropolymer has a Mooney viscosity from 20 to 300, alternatively from 20 to 270, alternatively from 30 to 240, or alternatively 30 to 200, as measured in accordance with JIS K6300. Specifically, the Mooney viscosity is measure according to JIS D6300 using a rotor having a diameter of 38.1 mm and a thickness of 5.54 mm at 100°C with a one minute preheating time and a rotor rotational time of 4 minutes. The Mooney viscosity is an index for molecular weight. The larger the Mooney viscosity, the higher the molecular weight, and the smaller the Mooney viscosity, the lower the molecular weight.

[0021] In certain embodiments, the first fluoropolymer is present in an amount of from about 10 to about 90 parts by weight based on 100 parts by weight of the fluoropolymer composition 14. Alternatively, the first fluoropolymer is present in an amount of from about 10 to about 80, from about 20 to about 60, from about 25 to about 45, from about 30 to about 40, or about 35, parts by weight based on 100 parts by weight of the fluoropolymer composition 14.

[0022] Referring now to the second fluoropolymer, the second fluoropolymer is a fluoropolymer that is different than the first fluoropolymer. In certain embodiments, the second fluoropolymer is a tetrafluoroethylene/propylene copolymer (TFE/P), a tetrafluoroethylene/propylene/vinylidene fluoride copolymer, a vinylidene fluoride/hexafluoropropylene copolymer, a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene copolymer, a vinylidene fluoride/tetrafluoroethylene/perfluoroalkylvinylether copolymer, a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene/perfluoroalkylvinylether copolymer, a tetrafluoroethylene/ethylene/perfluoroalkylvinylether copolymer, a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene/ethylene/perfluoroalkylvinylether copolymer, a vinylidenefluoride/chlorotrifluoroethylelne copolymer, a perfluoroalkoxy copolymer of polytetrafluoroethylene and perfluoro alkylvinyl ether, a polytetrafluoroethylene, a fluorinated ethylene propylene, a tetrafluoroethylene/hexafluoropropylene copolymer, a polyvinylidene fluoride, a polyvinyl fluoride, an ethylene/tetrafluoroethylene copolymer, an ethylene/tetrafluoroethylene/hexafluoropropylene copolymer, an ethylene/chlorotrifluoroethylene copolymer, a polychlorotrifluoroethylene, and combinations thereof. Typically the second fluoropolymer is TFE/P.

[0023] When the first fluoropolymer is TFE/P and the second fluoropolymer is TFE/P, the first fluoropolymer has an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1 and the second fluoropolymer does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. As described above, the absence of the absorption peak is understood to mean that a hot pressed sample of the second fluoropolymer has an absorption intensity less than 0.05, alternatively less than 0.02, or alternatively less than 0.01, between 1,640 to 1,700 cm-1. In one embodiment, the first fluoropolymer is TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and the second fluoropolymer is TFE/P that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. As such, because an absorption peak from 1,640 to 1,700 cm-1 is associated with carbon-carbon unsaturated bonds, the TFE/P with an absorption peak in this range (i.e., the first fluoropolymer) has a greater number of carbon-carbon unsaturated bonds than the TFE/P without an absorption peak in this range (i.e., the second fluoropolymer). As such, the first and second fluoropolymers are different when the first fluoropolymer is TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and the second fluoropolymer is TFE/P that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. This difference is significant because the amount of carbon-carbon unsaturated bonds influences the mechanical properties of the fluoropolymer (e.g. crosslinkability). [0024] In certain embodiments, the second fhioropolymer is present in an amount of from about 10 to about 90 parts by weight based on 100 parts by weight of the fhioropolymer composition 14. Alternatively, the second fhioropolymer is present in an amount of from about 10 to about 80, from about 20 to about 60, from about 25 to about 45, from about 30 to about 40, or about 35, parts by weight based on 100 parts by weight of the fhioropolymer composition 14.

[0025] Referring now to the crosslinker, the crosslinker may be any compound capable of reacting with a carbon-carbon unsaturated bond. It is to be appreciated that the crosslinker may also be referred to as a crosslinking agent or even as a crosslinking co-agent. In certain embodiments, the crosslinker is an unsaturated polyfunctional compound. In certain embodiments, the unsaturated polyfunctional compound is a triallyl derivative of cyanuric acid. Specific examples include triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), triallyl isocyanurate oligomer, trimethallyl isocyanurate (TMAIC) or combinations thereof. Typically, the crosslinker is TAIC.

[0026] In certain embodiments, the crosslinker is present in an amount of from about 1 to about 10 parts by weight based on 100 parts by weight of the fhioropolymer composition 14. Alternatively, the crosslinker is present in an amount of from about 2 to about 9, from about 3 to about 8, or from about 4 to about 7, parts by weight based on 100 parts by weight of the fhioropolymer composition.

[0027] In certain embodiments, the fhioropolymer composition 14 further comprises a second organic peroxide that is the same as or different than the first organic peroxide. Suitable second organic peroxides include, but are not limited to, monoperoxides, peroxy esters, diperoxides and combinations thereof. Suitable monoperoxides include diacyl peroxides such as dibenzoyl peroxide. Suitable peroxy esters include dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoate. Suitable diperoxides include l,3-bis-(t-butylperoxy isopropyl) benzene, di(tert-butylperoxyisopropyl)benzene, 2,5- dimethyl-2,5-di-(t-butylperoxy)-hexine-3,2,5-dimethyl-2,5-di-(t-butylperoxyl)-hexane, alpha,alpha'-bis-(t-butylperoxy)-p-diisopropyl benzene, and 2,5-dimethyl-2,5-di- (benzoylperoxy)-hexane. In certain embodiments, the second organic peroxide is di(tert- butylperoxyisopropyl)benzene.

[0028] In certain embodiments, the fluoropolymer composition 14 further comprises a filler. Suitable fillers include inorganic fillers, reinforcing fillers or fibers, nano-fillers, conductive fillers, insulation fillers, flame-retardant fillers, inorganic reinforcing material such as white carbon, magnesium carbonate, surface-treated calcium carbonate, inorganic fillers such as calcium carbonate, clay, talc, diatomaceous earth, alumina or barium sulfate and pigments. In certain embodiments, the filler is selected from the group of carbon black, silica, and combinations thereof. The carbon black may be any commercially available carbon black such as channel black, furnace black, acetylene black or thermal black. The silica can be a hydrophilic or hydrophobic silica. In certain embodiments, the silica is a hydrophilic fumed silica. In certain embodiments, the fluoropolymer composition 14 includes silica in an amount of from about 1 to about 8, alternatively from about 2 to about 7, or alternatively from about 3 to about 6, parts by weight of silica based on 100 parts by weight of the fluoropolymer composition 14. In certain embodiments, the fluoropolymer composition 14 includes carbon black in an amount from about 1 to about 8, alternatively from about 2 to about 7, or alternatively from about 3 to about 6, parts by weight of carbon black based on 100 parts by weight of the fluoropolymer composition 14. In certain embodiments, the fluoropolymer composition 14 includes the filler selected from the group of carbon black, silica, and combinations thereof, with the filler being present in an amount of from about 5 to about 15 parts by weight based on 100 parts by weight of the fluoropolymer composition 14.

[0029] In certain embodiments, the fluoropolymer composition 14 further comprises a syntactic additive. The syntactic additive may be any additive having a hollow interior. Examples of suitable syntactic additives include, but are not limited to, hollow polymers, glass microspheres or ceramic microspheres. Examples of glass or ceramic microspheres include glass, polymeric, or ceramic, including silica and alumina, microspheres. In one embodiment, the syntactic additive is a hollow, lime-borosilicate glass microsphere. Including the syntactic additive generally increases the compressive creep and crush resistance of the fluoropolymer composition 14. In addition, the syntactic additive also decreases the thermal conductivity of the fluoropolymer composition 14. Although various syntactic additives may be used, in certain embodiments, the syntactic additive has a crush strength of at least 15,000 psi, alternatively at least 20,000 psi, alternatively at least 25,000 psi, or alternatively at least 28,000 psi.

[0030] The syntactic additive may be present in an amount of from about 1 to about 35 parts by weight based on 100 parts by weight of the fluoropolymer composition 14. Alternatively, the syntactic additive may be present in an amount of from about 5 to about 30, from about 10 to about 25, from about 12 to about 23, or from about 14 to about 21, parts by weight based on 100 parts by weight of the composition. When the syntactic additive is present in the weights described above, the syntactic additive typically is present in an amount of from about 5 to about 35, from about 10 to about 30, from about 15 to about 30 or from about 20 to about 30, volume percent based on the total volume of the fluoropolymer composition 14. Without being held to any particular theory, the syntactic additive is believed to avoid thermal pathways. Moreover, because the syntactic additive decreases the thermal conductivity and also has a high crush strength, the nuoropolymer composition 14 is particular suitable as the insulation layer in the offshore, deep water environments (e.g. environments having a high temperature (e.g. greater than 130°C (e.g. 200°C) and at depths exceeding 1,000 meters).

[0031] Although not required, in certain embodiments, the nuoropolymer composition 14 comprises the reaction product of the first fluoropolymer, the second fluoropolymer, and the crosslinker, such that the fluoropolymer composition 14 is crosslinked. Typically, in these embodiments, the first fluoropolymer comprises TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, the second fluoropolymer comprises TFE/P, and the crosslinker comprises the triallyl derivative of cyanuric acid (e.g. TAIC). When the fluoropolymer composition 14 comprises the reaction product described above, the fluoropolymer composition 14 has excellent mechanical properties. More specifically, the fluoropolymer composition 14 has excellent thermal insulation, heat resistance, and tensile strength. As such, the fluoropolymer composition 14 may be used in harsh environments where a balance of mechanical and thermal properties are required. For example, the fluoropolymer composition 14 may be used in the offshore, deep water environments noted above.

[0032] As described above, the fluoropolymer composition 14 has excellent thermal insulation as demonstrated by the low thermal conductivity values. For example, the excellent thermal insulation is present in certain embodiments when the fluoropolymer composition 14 has a thermal conductivity less than 0.40W/mK at 205°C. Alternatively, the excellent thermal insulation is present when the the fluoropolymer composition 14 has a thermal conductivity less than 0.35W/mK at 205°C, alternatively less than 0.30W/mK at 205°C, or alternatively from about 0.1 to about 0.25W/mK at 205°C. In certain embodiments, the fluoropolymer composition 14 has a thermal conductivity less than 0.40W/mK at 20°C. Alternatively, the fluoropolymer composition 14 has a thermal conductivity less than 0.35W/mK at 20°C, alternatively less than 0.30W/mK at 20°C, or alternatively from about 0.1 to about 0.25W/mK at 20°C. Not only does the fluoropolymer composition 14 have excellent thermal insulation, even at temperatures above 200°C, the fluoropolymer composition 14 is also thermally stable at these temperatures. In other words, the fluoropolymer composition 14 is capable of withstanding heat at or above 200°C without degrading the polymer and while providing excellent thermal insulation. As such, the fluoropolymer composition 14 may be used as the insulation layer.

[0033] The fluoropolymer composition 14 may also include additives. These additives are generally selected to tailor the fluoropolymer composition 14 for a specific use. Examples of suitable additives include, but are not limited to, adhesion improvers, pigments, and processing aids, antioxidants, flame-retardants, stabilizers, internal mold release agents. In general, the additives are collectively present in an amount of from about 0.1 to about 5 parts by weight based on 100 parts by weight of the fluoropolymer composition 14.

[0034] In certain embodiments, the fluoropolymer composition 14 comprises the reaction product of a first TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, a second TFE/P that is different than the first TFE/P and that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and TAIC. In this embodiment, the reaction product is formed by the first TFE/P present in an amount of from about 25 to about 40 parts by weight, the second TFE/P present in an amount of from about 45 to about 55 parts by weight, and TAIC present in an amount of from about 2 to about 8 parts by weight, each based on 100 parts by weight of the fluoropolymer composition 14. Without being held to any particular theory, when the reaction product described above has superior mechanical and thermal isolative properties when compared to a similar compositions including only one of the aforementioned TFE/P polymers.

[0035] In one embodiment, the fluoropolymer composition 14 comprises the reaction product of a first TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, a second TFE/P that is different than the first TFE/P and that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and TAIC. In this embodiment, the reaction product is formed by the first TFE/P present in an amount of from about 25 to about 40 parts by weight, the second TFE/P present in an amount of from about 45 to about 55 parts by weight, and TAIC present in an amount of from about 2 to about 8 parts by weight, each based on 100 parts by weight of the fluoropolymer composition 14. In addition, the fluoropolymer composition 14 also comprises carbon black in an amount of from about 2 to about 6 parts by weight based on 100 parts by weight of the fluoropolymer composition 14. In addition, the fluoropolymer composition 14 also comprises fumed silica in an amount of from about 2 to about 6 parts by weight based on 100 parts by weight of the fluoropolymer composition 14. The fluoropolymer composition 14 of this embodiment has excellent mechanical properties with a thermal conductivity of from about 0.1 to about 0.25W/mK at 205°C, alternatively of from about 0.1 to about 0.2W/mK at 205°C. In addition, when the fluoropolymer composition 14 comprises the reaction product described above, the fluoropolymer composition 14 has an excellent balance of mechanical properties such as tensile strength, elongation, and ductility, and is generally capable of withstanding high pressures and temperatures. As such, unlike conventional compositions, the fluoropolymer composition 14 may be used in the offshore, deep water environments (e.g. environments having a high temperature (e.g. greater than 130°C (e.g. 200°C) and at depths exceeding 1,000 meters). [0036] In another embodiment, the fhioropolymer composition 14 consists essentially of

(1) the reaction product of the first fhioropolymer, the second fhioropolymer and the crosslinker,

(2) carbon black, and (3) silica. Although not required for this embodiment, the first fhioropolymer is typically TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, the second fhioropolymer is TFE/P that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and the crosslinker is TAIC. In addition, in this embodiment, the first fhioropolymer is present in an amount of from about 25 to about 40 parts by weight, the second fhioropolymer is present in an amount of from about 45 to about 55 parts by weight, and the crosslinker is present in an amount of from about 2 to about 8 parts by weight, each based on 100 parts by weight of the fhioropolymer composition 14. In addition, the carbon black is present in an amount of from about 2 to about 6 parts by weight and the silica is present an amount of from about 2 to about 6 parts by weight, each based on 100 parts by weight of the fhioropolymer composition 14. The fhioropolymer composition 14 of this embodiment has excellent mechanical properties with a thermal conductivity of from about 0.1 to about 0.25W/mK at 205°C, alternatively of from about 0.1 to about 0.2W/mK at 205°C. In addition, when the fhioropolymer composition 14 comprises the reaction product described above, the fhioropolymer composition 14 has an excellent balance of mechanical properties such as tensile strength, elongation, and ductility. The term "consists essentially of as used in connection with this embodiment allows for the inclusion of addition materials, such as the additives described above, so longs as the additional materials are present in an amount less than 5 parts by weight based on 100 parts by weight of the fhioropolymer composition 14, and the addition materials do not adversely influence the thermal conductivity and thermal stability of the fhioropolymer composition 14 at temperatures at or above 200°C. [0037] Typically, the fluoropolymer composition 14 is crosslinked by heating. A conventional oven may be used to provide the heat required to crosslink the fluoropolymer composition 14. Alternatively, a heat oven, an extruder, and/or an autoclave may provide the heat required to crosslink the fluoropolymer composition 14. The temperature for cross-linking by heating is typically from 60 to 250°C, alternatively from 120 to 200°C. Further, the heating time is not particularly limited, but it is usually within a range of from one minute to forty-eight hours, alternatively within a range of from five minutes to twenty-four hours. Of course, if the heating temperature is increased, the heating time may be shortened. Further, re-heating treatment of the obtainable cross-linked product may also be employed, and such may be useful for further improvement of the mechanical properties. For example, re-heating treatment at a temperature of from 150 to 250°C, alternatively from 180 to 230°C, for from about 2 to 25 hours, may be employed. In certain embodiments, when heated, the second organic peroxide forms the reaction product of the first fluoropolymer, the second fluoropolymer and the crosslinker.

[0038] The fluoropolymer composition 14 may also be crosslinked by irradiation with an ionizing radiation source, with or without the second organic peroxide being present. Suitable ionizing radiation sources include electron rays or γ-rays. Typically, the ionization energy is from 1 to 300 kGy, alternatively from 10 to 200 kGy.

[0039] The fluoropolymer composition 14 described above may be formed into molded products such as seals, packings, sheets, pipes, rods, tubes, angles, channels, coated fabrics, coated plates, insulation layers, or wire coatings by usual molding or other molding methods such as extrusion, transfer, calendering, roll coating, brush coating or impregnation. Alternatively, the fluoropolymer composition 14 may be formed into molded products such as sponge rubbers. In certain embodiments, because of the excellent thermal insulation, thermal stability, and mechanical properties of the fluoropolymer composition 14, the fluoropolymer composition 14 is suitable for use as thermal insulation layer in thermally insulated liquid and/or gas transport conduits for use in subsea environments. Depending on the particular application, the fluoropolymer composition 14 may either be a solid or a syntactic foam.

[0040] As shown in Figures 1 and 2, the present disclosure provides the insulated conduit

10 for use in the offshore, deep water environments. The insulated conduit 10 includes the continuous steel pipe 12 having one or more pipe sections. The steel pipe 12 has an outer surface and an inner surface. The insulated conduit 10 also includes the fluoropolymer composition 14 (hereinafter the fluoropolymer composition 14) disposed about the steel pipe 12 for providing the thermal insulation layer. Most commonly the fluoropolymer composition 14 is disposed about an entirety of the steel pipe 12, but could be partially disposed about.

[0041] It is to be appreciated that Figures 1 and 2 are not drawn to scale. As examples, the thicknesses of some of the layers are exaggerated in relation to the thicknesses of the other layers and also relative to the thickness and diameter of the steel pipe 12.

[0042] It is also be appreciated that the term "insulated conduit 10" may refer to liquid and/or gas transport conduits, and is intended to include oil and gas pipelines and related components, including flowlines, risers, jumpers, spools, manifolds and ancillary equipment. As such, it is to be appreciated that the insulated conduit 10, can be used in environments other than the offshore, deep water environment. For example, the insulated conduit 10 can be used on land or in shallow water.

[0043] In certain embodiments, as best shown in Figure 1, the insulated conduit 10 comprises the fluoropolymer composition 14 disposed about the steel pipe 12. In this embodiment, the fluoropolymer composition 14 is the insulation layer for the insulated conduit 10. In certain embodiments, the insulated conduit 10 may comprise two or more layers of the fluoropolymer composition 14 (i.e., the insulated conduit 10 has two or more insulation layers). Due to the excellent thermal insulation of the fluoropolymer composition 14, when the insulated conduit 10 transports a liquid or gas that is at a high temperature (e.g. 200°C), the fluoropolymer composition 14 insulates the insulated conduit 10 to maintain the temperature of the liquid or gas being transported. Maintaining the temperature of the liquid or gas being transported is advantageous because it prevents or reduces the formation of hydrates and waxes in the liquid or gas, particularly when the liquid is oil, which, if present, typically decreases the pumping efficiency for the liquid or gas.

[0044] The insulated conduit 10 for use in the offshore, deep water environments comprises the fluoropolymer composition 14 disposed about the steel pipe 12 for providing the thermal insulation layer. The fluoropolymer composition 14 comprises the first fluoropolymer having an absorption peak on an infrared absorption spectrum from 1,640 to 1,700 cm-1, the second fluoropolymer that is different than the first fluoropolymer, and the crosslinker. It is to be appreciated that the insulated conduit 10 may comprise any embodiment of the fluoropolymer composition 14 described above.

[0045] The first fluoropolymer may be any of the fluoropolymers described above so long as the first fluoropolymer has an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. Typically, the first fluoropolymer is TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. As described above, the first fluoropolymer may be formed by heat-treating the mixture comprising the precursor of the first fluoropolymer and the first organic peroxide. Although not required, heat-treating the mixture comprising the precursor of the first fluoropolymer and the first organic peroxide comprises heating at a temperature of from 110 to 380°C for from 10 seconds to 3 hours. The second fluoropolymer may also be any of the fluoropolymer s described above so long as the second fluoropolymer and the first fluoropolymer are different. Typically, the second fluoropolymer is TFE/P.

[0046] In certain embodiments, of the insulated conduit 10, the first fluoropolymer is present in the fluoropolymer composition 14 in an amount of from about 10 to about 90 parts by weight based on 100 parts by weight of the fluoropolymer composition 14. Alternatively, the first fluoropolymer is present in an amount of from about 10 to about 80, from about 20 to about 60, from about 25 to about 45, from about 30 to about 40, or about 35, parts by weight based on 100 parts by weight of the fluoropolymer composition 14.

[0047] When the first fluoropolymer is TFE/P and the second fluoropolymer is TFE/P, the first fluoropolymer has an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1 and the second fluoropolymer does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. Because an absorption peak from 1,640 to 1,700 cm-1 is associated with carbon-carbon unsaturated bonds, the TFE/P with an absorption peak in this range (i.e., the first fluoropolymer) has a greater number of carbon-carbon unsaturated bonds than the TFE/P without an absorption peak in this range (i.e., the second fluoropolymer). As such, the first and second fluoropolymers are different when the first fluoropolymer is TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1 and the second fluoropolymer is TFE/P that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. This difference is significant because the amount of carbon-carbon unsaturated bonds influences the mechanical properties of the fluoropolymer (e.g. crosslinkability).

[0048] The fluoropolymer composition 14 is applied about the steel pipe 12 at a sufficient thickness to provide the insulated conduit 10 with an acceptable heat transfer coefficient (U) for the conditions under which it is to be used, with U typically being in the range from about 1 to about 10 W/mK, for example from about 2 to about 8 W/mK. The thermal conductivity of the fluoropolymer composition is less than about 0.40 W/mK at 205°C, for example from about 0.10 to 0.35 W/mK at 205°C, typically from about 0.15 to 0.20 W/mK at 205°C.

[0049] As described above, the fluoropolymer composition 14 is designed to withstand operating temperatures in excess of the maximum operating temperatures (about 200°C) of systems currently used for the thermal insulation of subsea pipelines. These operating temperatures may be as high as 270°C. In addition, the tensile strength of the fluoropolymer composition 14 is sufficiently ductile to withstand the bending strains experienced by the insulated conduit 10 during reeling and installation operations.

[0050] The thickness of the fluoropolymer composition 14 on the insulated conduit 10 is highly variable, due to the fact that each insulated conduit 10 is designed for use under specific conditions of depth, temperature, etc.

[0051] In certain embodiments as best shown in Figure 2, the insulated conduit 10 may include one or more additional layers. In certain embodiments, the insulted conduit includes a corrosion protection layer 16. Typically, the corrosion protection layer 16 comprises a high temperature corrosion protection material. Typically, the corrosion protection layer 16 is disposed directly on the steel pipe 12. Although not required, in certain embodiments, the nuoropolymer composition 14 is disposed directly on the corrosion protection layer 16 (not shown in Figure 2).

[0052] The corrosion protection layer 16 may comprise epoxy phenolics, polyphenylene sulphides, fluoropolymers, or polyimides, including modified versions and blends thereof. In certain embodiments, the composition of the corrosion protection layer 16 provides excellent adhesion to the fluoropolymer composition 14.

[0053] The insulated conduit 10 may also comprise an intermediate adhesive layer 18, which may be applied directly to the insulated conduit 10 (not shown in Figure 2) or may be applied over the corrosion protection layer 16. Typically, when the intermediate adhesive layer 18 is present, the fluoropolymer composition 14 is applied over the intermediate adhesive layer 18.

[0054] In certain embodiments, the intermediate adhesive layer 18 comprises polymers or reactive systems containing functional groups having an affinity to the layers in contact with the intermediate adhesive layer 18 (e.g. the fluoropolymer composition 14 and/or the corrosion protection layer 16). The insulated conduit 10 may have one or more intermediate adhesive layers 18.

[0055] When the intermediate adhesive layer 18 is in contact with the fluoropolymer composition 14, the intermediate adhesive layer 18 may bond to the fluoropolymer composition 14 during the extrusion process. Suitable adhesives for use as the intermediate adhesive layer 18 are manufactured by companies such as The Dow Chemical Company, Lord Corporation, and 3M Corporation. [0056] The intermediate adhesive layer 18 may be applied by powder spray application, liquid spray application, or side-wrap, crosshead extrusion or co-extrusion methods, including co-extrusion with the nuoropolymer composition 14.

[0057] Regardless of the layer(s) in contact with the fluoropolymer composition 14, the fluoropolymer composition 14 must firmly adhere to that layer. Adhesion between the layers, also known as interlayer adhesion, is also dependent upon the coating temperature and the mode of application of the layers. For example, it may be necessary to pre-heat the corrosion protection layer 16 or system prior to the application of the fluoropolymer composition 14 to better fuse the two layers together and maximize interlayer adhesion. As such, when the corrosion protection layer 16 is disposed about the steel pipe 12, it is particularly advantageous to include the intermediate adhesive layer 18, as the fluoropolymer composition 14 has excellent adhesion to the intermediate adhesive layer 18. Interlayer adhesion may also be accomplished through the activation of one or more of the surfaces to be adhered using plasma or corona discharge treatment. This may also be utilized in conjunction with an intermediate adhesive layer 18.

[0058] As shown in Figure 2 a first protective layer 20 may be applied over the fluoropolymer composition 14 to provide further resistance to pressure in the offshore, deep water environments. The first protective layer 20 may comprise the fluoropolymer composition 14. It is to be appreciated that the first protective layer 20 is not necessary in all embodiments. For example, the first protective layer 20 may not be necessary when the fluoropolymer composition 14 is crosslinked, due to the excellent mechanical and thermal properties of the fluoropolymer composition 14. The first protective layer may also comprise a blend of the first and/or second fluoropolymer with a different polymer, such as hydrogenated nitrile butadiene rubber (HNBR), or nitrile butadiene rubber (NBR). [0059] In certain embodiments, the insulated conduit 10 may comprise a second protective layer 22. In these embodiments, the insulated conduit 10 may also comprise a third protective layer 24. It is to be appreciated that the second and third protective layers 22, 24 may independently comprise the fluoropolymer composition 14.

[0060] Typically the second and third protective layers 22, 24 may independently comprise a thermoplastic polymer, such as conventional polyethylene, polypropylene, polybutylene, polyurethane and copolymers, blends and elastomers thereof. Alternatively, the second and third protective layers 22, 24 may be independently selected from any of the foamed or solid polystyrene or styrene-based thermoplastics.

[0061] In an alternative embodiment, the second and third protective layers 22, 24 may independently comprise elastomers such as HNBR, nitrile butadiene rubber NBR, silicone rubber, ethylene propylene diene monomer EPDM rubber, and butyl rubber.

[0062] Alternatively, the second and third protective layers 22, 24 may comprise any high temperature resistant thermoplastics, either solid or foamed, disclosed in above-mentioned U.S. Patent No. 8,397,765 by Jackson et al, which is incorporated by reference in its entirety. The high temperature resistant thermoplastics disclosed therein are able to withstand operating temperatures of about 130°C or higher. The high temperature resistant thermoplastic is selected from one or more members of the group comprising: polycarbonate, polyphenylene oxide, polyphenylene oxide blended with polypropylene, polystyrene or polyamide, polycarbonate blended with polybutylene terephthalate, polyethylene terephthalate, acrylonitrile butadiene styrene, acrylonitrile styrene acrylate, or polyetherimide, polyamides, including polyamide 12 and 612 and elastomers thereof, polymethylpentene and blends thereof, cyclic olefin copolymers and blends thereof, and, partially crosslinked thermoplastic elastomers, also known as thermoplastic vulcanizates or dynamically vulcanized elastomers.

[0063] The second and/or third protective layers 22, 24 may independently be foamed or solid. The second and/or third protective layers 22, 24 may either be a blown foam or a syntactic foam having a degree of foaming of up to about 50%, for example from about 5% to about 30%.

[0064] When the second protective layer 22 is present, typically the first protective layer

20 comprises a blend of the first and/or second fluoropolymer with a polymer that is present in the second protective layer 22. When the first protective layer 20 comprises the blend, the first protective layer generally improves the adhesion of the layers present in the insulated conduit 10, such that the first protective layer may also be referred to as a "tie-layer". Of course, the first protective layer 20 may comprise the blend regardless of whether the second protective layer 22 is present.

[0065] It is to be appreciated that the first, second, and third protective layer 20, 22, 24 may increase the mechanical or chemical performance, such as impact, abrasion, crush or moisture resistance, of the insulated conduit 10. In certain embodiments, it may be advantageous to prepare the outermost layer (e.g. the third protective layer 24 in Figure 2) from a polymeric material having superior impact, abrasion, crush or chemical resistance to that of the fluoropolymer composition 14. Such a material may comprise the fluoropolymer composition 14 blended with suitable polymeric modifiers, compatibilisers, or reinforcing fillers or fibers, or it may comprise a dissimilar, preferably compatible, polymeric material. In the latter case, it may be necessary to apply an additional intermediate adhesive layer 14 to promote adhesion. It may also be advantageous to progressively foam to higher degrees the layers exterior to fluoropolymer composition 14. [0066] The present disclosure also provides a method for preparing the insulated conduit

10. The method includes a step of forming the fluoropolymer composition 14. The fluoropolymer composition 14 may be formed by preparing a mixture comprising the first fluoropolymer, the second fluoropolymer and the crosslinker. The mixture may then be compounded to form a compounded mixture. The compounded mixture typically is in the form of a ribbon or a strip, but may also be in the form of a pellet. Conventional compounding equipment may be used to compound the mixture. A nonlimiting example of a compounding procedure includes preparing a mixture by combining the first fluoropolymer, the second fluoropolymer, and the crosslinker. Shearing the mixture until the temperature of the mixture reaches between 150 and 180°F. The method may further includes adding to the mixture, any remaining components (e.g. silica, carbon black, and/or the syntactic additive), and continuing to mix until the temperature reaches 200 to 220°F. The method may also include increasing the shear until a temperature of 220 to 250°F is reached, and milling the mixture in a mill to produce a uniform mixture in the form of ribbon, strip, and/or pellet.

[0067] The fluoropolymer composition 14, and any additional layers (i.e., the corrosion protection layer 16, the intermediate adhesive layer 18, and the first, second, and/or third protective layers 20, 22, 24), may be applied to the steel pipe 12, by rubber mandrel wrapping, sidewrap or crosshead extrusion, or co-extrusion, processes. Alternatively, these layers may in some cases be applied as a fusion bonded powder by spraying the steel pipe 12 with powder- spray guns, passing the steel pipe 12 through a "curtain" of falling powder, or using a liquidized bed containing the powder, or, as a liquid coating using liquid-spray guns. Melt fusion of the powder results from contact with the hot pipe. [0068] Extrusion may be accomplished using single screw extrusion, either in single or tandem configuration, or by twin-screw extrusion methods. In the case of single screw extrusion, the extruder screw may be either single stage or 2- stage design.

[0069] A single stage compression screw would be adequate for chemical foam extrusion whereby the foaming agent is added as a pelleted concentrate or masterbatch which is pre-mixed with the polymer to be foamed using a multi-component blender, for example, mounted over the main feed port of the extruder. The design of the screw is important and it may incorporate barrier flights and mixing elements to ensure effective melting, mixing, and conveying of the polymer and foaming agent.

[0070] With a 2- stage screw, the first and second stages are separated by a decompression zone, at which point a gas or liquid physical foaming agent can be introduced into the polymer melt via an injection or feed port in the extruder barrel. The first stage acts to melt and homogenize the polymer, whereas the second stage acts to disperse the foaming agent, cool the melt temperature, and increase the melt pressure prior to the melt exiting the die. This may also be accomplished by tandem extrusion, wherein the two stages are effectively individual single screw extruders, the first feeding into the second. A 2-stage screw is also preferred for the extrusion of polymers which have a tendency to release volatiles when melted, or are hygroscopic, the extruder barrel then being equipped with a vent port positioned over the decompression zone through which the volatiles or moisture can be safely extracted.

[0071] Twin screw extrusion is preferred where the individual layer to be foamed is shear sensitive or if it is required that fillers or other additives be incorporated into the composition. It is particularly recommended for the extrusion of syntactic foams or blown foams prepared by the physical injection of a gas or liquid foaming agent. Since the twin screw design is typically modular, comprising several separate and interchangeable screw elements, such as mixing and conveying elements, it offers great versatility with respect to tailoring the screw profile for optimum mixing and melt processing.

[0072] In the case of syntactic foams, for example, the hollow microspheres are fed directly into the polymer melt using a secondary twin-screw feeder downstream of the main polymer feed hopper. An additional consideration with syntactic foams is potential breakage of the hollow microspheres during extrusion of the foam. Shear and compressive forces inside the extruder need to be minimized during processing of the foam to prevent this through judicious design of the extruder screw(s), barrels, manifolds and dies. It is contemplated that the particular fluoropolymer as well as the amount of the fluoropolymer also contribute to resisting breakage fo the syntactic additive.

[0073] A static mixing attachment or gear pump may be inserted between the end of the screw and the die to further homogenize the melt, generate melt pressure, and minimize melt flow fluctuations.

[0074] Actual coating of the steel pipe 12 may be accomplished using an annular crosshead die attached to the extruder through which the pre-heated pipe, with a prior-applied corrosion protection layer 16, is conveyed, the fluoropolymer composition 14 thereby covering the entire surface of the steel pipe 12 by virtue of the annular die forming the fluoropolymer composition 14 into a tubular profile around the conveyed steel pipe 12.

[0075] Alternatively, the fluoropolymer composition 14 may be applied by a side-wrap technique whereby the fluoropolymer composition 14 is extruded through a flat strip or sheet die. The fluoropolymer composition is extruded in the form of a sheet or tape which is then wrapped around the steel pipe 12. It may be necessary to apply a number of wraps to achieve the required thickness and, hence, performance.

[0076] The application of fluoropolymer composition 14 by the side-wrap technique may involve wrapping the steel pipe 12 as it is simultaneously rotated and conveyed forwardly along its longitudinal axis, as described above. It may also involve the application of a pre-extruded tape using rotating heads while the steel pipe 12 is conveyed longitudinally but not rotated. In this particular case, the winding angle of the fluoropolymer composition 14 and other layers can be adjusted by varying the speed of steel pipe 12 movement in the longitudinal direction and/or by varying the rotational speed of the steel pipe 12 or the rotating heads. The tape may be wound in successive layers at opposite winding angles to maintain neutrality of the steel pipe 12, until the required thickness has been built up. Application of a tension tape after application of an elastomer may be utilized to provide pressure for fusing layers together during curing.

[0077] If the intermediate adhesive layer 18 is present between the corrosion protection layer 16 and the fluoropolymer composition 14, or between any additional layers, this can be accomplished using either a single layer sheet or annular die, or a co-extrusion die whereby a intermediate adhesive layer 18 and the fluoropolymer composition 14 are applied simultaneously. The first, second, and/or third protective layers 20, 22, 24, if necessary, may be similarly applied. Alternatively, as mentioned above, where the adhesive is a liquid it may be applied by liquid spray application.

[0078] The present disclosure also provides a second insulated conduit 26 (herein after the insulated conduit 26). Like the first insulated conduit 10, the second insulated conduit 26 is also commonly applied in the offshore, deep water environments (e.g. environments having a high temperature (e.g. greater than 130°C (e.g. 200°C) and at depths exceeding 1,000 meters), although such environments are not required. The insulated conduit 26 includes a continuous steel pipe 28 having one or more pipe sections. The steel pipe 28 has an outer surface and an inner surface. The insulated conduit 26 also includes a second fluoropolymer composition 30 (hereinafter the fluoropolymer composition 30) disposed about the steel pipe 28 for providing a thermal insulation layer.

[0079] The present disclosure also provides the fluoropolymer composition 30 itself (i.e., the present disclosure provides the fluoropolymer composition 30, independent of the use of the fluoropolymer composition 30 about the insulated conduit 26).

[0080] The fluoropolymer composition 30 comprises a fluoropolymer and a syntactic additive. The syntactic additive is present in an amount of from about 10 to about 30 volume percent based on a total volume of the fluoropolymer composition 30.

[0081] The fluoropolymer may be any polymer containing a fluorine atom bonded to a carbon atom. In certain embodiments, the fluoropolymer is a tetrafluoroethylene/propylene copolymer (TFE/P), a tetrafluoroethylene/propylene/vinylidene fluoride copolymer, a vinylidene fluoride/hexafluoropropylene copolymer, a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene copolymer, a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene/perfluoromethylevinyl ether copolymer, a perfluoroalkoxy copolymer of polytetrafluoroethylene and perfluoro alkylvinyl ether, a polytetrafluoroethylene, a fluorinated ethylene propylene, a tetrafluoroethylene and hexafluoroethylene copolymer, a polyvinylidene fluoride, and combinations thereof. Typically the fluoropolymer is TFE/P. TFE/P is the reaction product of tetrafluoroethylene and propylene.

[0082] The fluoropolymer may be a fluoropolymer having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. In certain embodiments, the fluoropolymer has an absorption peak at from 1,660 to 1,700 cm-1 on the infrared absorption spectrum. Alternatively, the fluoropolymer has an absorption peak at from 1,680 to 1,700 cm-1 on the infrared absorption spectrum. The absorption peak within such a range is attributable to an increase in carbon-carbon unsaturated bonds.

[0083] In certain embodiments, the fluoropolymer is formed by heat-treating a mixture comprising a precursor of the fluoropolymer and an organic peroxide. Typically, in these embodiments, the precursor of the fluoropolymer is TFE/P. In certain embodiments, when the fluoropolymer is prepared by heat-treating, the precursor of the fluoropolymer and the organic peroxide are heated at a temperature of from 110 to 380°C for about 10 seconds to about 3 hours, alternatively from 10 seconds to 30 minutes, alternatively from 10 seconds to 15 minutes. Additional details regarding the method of forming the fluoropolymer by heat-treating the mixture comprising the precursor of the fluoropolymer and the organic peroxide are provided above. Suitable organic peroxides are also described above.

[0084] In certain embodiments, the fluoropolymer has a Mooney viscosity from 20 to

300, alternatively from 20 to 270, alternatively from 30 to 240, or alternatively 30 to 200, as measured in accordance with JIS K6300. Specifically, the Mooney viscosity is measure according to JIS D6300 using a rotor having a diameter of 38.1 mm and a thickness of 5.54 mm at 100°C with a one minute preheating time and a rotor rotational time of 4 minutes. The Mooney viscosity is an index for the molecular weight. The larger the Mooney viscosity, the higher the molecular weight, and the smaller the Mooney viscosity, the lower the molecular weight.

[0085] In certain embodiments, the fluoropolymer is present in an amount of from about

60 to about 90 parts by weight based on 100 parts by weight of the fluoropolymer composition 30. Alternatively, the fhioropolymer is present in an amount of from about 65 to about 87, about 70 to about 84, or about 75 to about 81, parts by weight based on 100 parts by weight of the fhioropolymer composition 30. In these embodiments, the fhioropolymer is typically TFE/P. Of course, the fhioropolymer composition 30 may include any additional polymer in combination with the fhioropolymer.

[0086] In certain embodiments, a portion of the fhioropolymer is TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. In these embodiments, the TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1 is present in an amount of from about 5 to about 85 parts by weight based on 100 parts by weight of the fhioropolymer composition, with the remainder of the fhioropolymer being a fhioropolymer that is different than the TFE/P fhioropolymer TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1.

[0087] In certain embodiments, the fhioropolymer has a storage modulus of from about

150 to about 300 as measured in accordance with ASTM D6204 with a frequency of lHz, strain of 0.5 degrees, and at a temperature of 100°C.

[0088] In certain embodiments, the TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1 is present in an amount of from about 10 to about 80 parts by weight, and a TFE/P that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1 is present in an amount of from about 10 to about 80 parts by weight, each based on 100 parts by weight of the fhioropolymer composition and each collectively present in an amount of 60 to 90 parts by weight based on 100 parts by weight of the fhioropolymer composition 30. [0089] In certain embodiments, the TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1 is present in an amount of from about 30 to about 50 parts by weight, and a TFE/P that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1 is present in an amount of from about 30 to about 50 parts by weight, each based on 100 parts by weight of the fluoropolymer composition and each collectively present in an amount of 70 to 90 parts by weight based on 100 parts by weight of the fluoropolymer composition 30.

[0090] The fluoropolymer composition 30 also comprises the syntactic additive. The syntactic additive may be any additive having a hollow interior. Examples of suitable syntactic additives include, but are not limited to, a hollow polymer, glass microspheres or ceramic microspheres. Examples of glass or ceramic microspheres include glass, polymeric, or ceramic, including silica and alumina, microspheres. In one embodiment, the syntactic additive is a hollow, lime-borosilicate glass microspheres. Including the syntactic additive generally increases the compressive creep and crush resistance of the fluoropolymer composition 30. In addition, the syntactic additive also decreases the thermal conductivity of the fluoropolymer composition 30. Although various syntactic additives may be used, in certain embodiments the syntactic additive has a crush strength of at least 15,000 psi, alternatively at least 20,000 psi, alternatively at least 25,000 psi, or alternatively at least 28,000 psi. In addition, because the syntactic additive also has a high crush strength and decreases the thermal conductivity of the fluoropolymer composition 30, the fluoropolymer composition 30 is particular suitable as the insulation layer in the offshore, deep water environments.

[0091] The syntactic additive may be present in an amount of from about 1 to about 35 parts by weight based on 100 parts by weight of the fluoropolymer composition 30. Alternatively, the syntactic additive may be present in an amount of from about 5 to about 30, from about 10 to about 25, from about 12 to about 23, or from about 14 to about 21 parts by weight based on 100 parts by weight of the fluoropolymer composition 30. Based on the weight of the syntactic additive in the fluoropolymer composition 30, the syntactic additive may be present in an amount of from about 5 to about 35, from about 10 to about 30, from about 15 to about 30 or from about 20 to about 30, volume percent based on the total volume of the fluoropolymer composition 30.

[0092] The fluoropolymer composition 30 also has a specific gravity less than or equal to

1.6 when measured at room temperature. Alternatively, the fluoropolymer composition 30 has a specific gravity less than 1.45, less than 1.40, less than 1.35, less than 1.30, less than 1.25, or alternatively from about 1.1 to about 1.4 when measured at room temperature. Conventional fluoropolymer compositions that contain syntactic additives have higher specific gravity due to breakage of the syntactic additives. However, the combination of the Mooney viscosity and more specifically, the storage modulus of the fluoropolymer polymer prevent the breakage of the glass beads as the glass beads are incorporated into the fluoropolymer composition 30, and thus the fluoropolymer composition 30 has a lower specific gravity than conventional fluoropolymer compositions. If the syntactic additive is crushed, thermal pathways may form and adversely increase the thermal conductivity and decrease the mechanical properties of the resulting composition.

[0093] Without being held to any particular theory, because the fluoropolymer composition 30 includes the syntactic additives that have not been crushed or broken (as evidenced by the specific gravity of the fluoropolymer composition), the fluoropolymer composition 30, in part due to the presence of the syntactic additive, has a low thermal conductivity and high thermal stability, as demonstrated by the ability of the fluoropolymer to withstand temperate exceeding 200°C while exhibiting a thermal conductivity of less than 0.40W/mK, alternatively from about 0.1 to about 0.25W/mK. As such, the fluoropolymer composition 14 is particular suitable as the insulation layer in the offshore, deep water environments (e.g. environments having a high temperature (e.g. greater than 130°C (e.g. 200°C) and at depths exceeding 1,000 meters).

[0094] In certain embodiments, the fluoropolymer composition 30 comprises a crosslinker present in an amount of from about 1 to about 10 parts by weight based on 100 parts by weight of the fluoropolymer composition 30. Alternatively, the crosslinker is present in an amount of from about 2 to about 8 or from about 3 to about 7, parts by weight based on 100 parts by weight of the fluoropolymer composition 30. The crosslinker may be any compound capable of reacting with a carbon-carbon unsaturated bond. In certain embodiments, the crosslinker is an unsaturated polyfunctional compound. In certain embodiments, the unsaturated polyfunctional compound is a triallyl derivative of cyanuric acid. Specific examples include triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), triallyl isocyanurate oligomer, trimethallyl isocyanurate (TMAIC) or combinations thereof. Typically, the crosslinker is TAIC.

[0095] In certain embodiments, the fluoropolymer composition 30 comprises an organic peroxide. Suitable organic peroxides include, but are not limited to, monoperoxides, peroxy esters, diperoxides and combinations thereof. Suitable monoperoxides include diacyl peroxides such as dibenzoyl peroxide. Suitable peroxy esters include dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoate. Suitable diperoxides include l,3-bis-(t-butylperoxy isopropyl) benzene, di(tert- butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di-(t-butylperoxy)-hexine-3,2,5-dimethyl-2,5- di-(t-butylperoxyl)-hexane, alpha,alpha'-bis-(t-butylperoxy)-p-diisopropyl benzene, and 2,5- dimethyl-2,5-di-(benzoylperoxy)-hexane. In certain embodiments, the organic peroxide is di(tert-butylperoxyisopropyl)benzene.

[0096] In certain embodiments, the fluoropolymer composition 30 comprises a filler.

Suitable fillers are described above. In certain embodiments, the fluoropolymer composition 30 includes silica in an amount of from about 1 to about 8, alternatively from about 2 to about 7, or alternatively from about 3 to about 6 parts by weight of silica, based on 100 parts by weight of the fluoropolymer composition 30. In certain embodiments, the fluoropolymer composition 30 includes carbon black in an amount from about 1 to about 8, alternatively from about 2 to about 7, or alternatively from about 3 to about 6 parts by weight of carbon black, based on 100 parts by weight of the fluoropolymer composition 30. In certain embodiments, the fluoropolymer composition 30 includes the filler selected from the group of carbon black, silica, and combinations thereof, with the filler being present in an amount of from about 5 to about 15 parts by weight based on 100 parts by weight of the fluoropolymer composition 30.

[0097] Although not required, in certain embodiments, the fluoropolymer composition 30 comprises the reaction product of the fluoropolymer, and the crosslinker, such that the fluoropolymer composition 30 is crosslinked. Typically, in these embodiments, the fluoropolymer comprises TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and comprises TFE/P that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1. Typically, in these embodiments, the crosslinker is TAIC. When the fluoropolymer composition 30 comprises the reaction product described above, the fluoropolymer composition 30 has excellent mechanical properties. More specifically, the fluoropolymer composition 30 has excellent thermal insulation, heat resistance, and tensile strength. As such, the fluoropolymer composition 30 may be used in harsh environments where a balance of mechanical and thermal properties are required. For example, the fluoropolymer composition 30 may be used as the thermal insulation layer in the offshore, deep water environments.

[0098] As described above, the fluoropolymer composition 30 has excellent thermal insulation. In certain embodiments, the fluoropolymer composition 30 has a thermal conductivity less than 0.40W/mK at 205°C. Alternatively, the fluoropolymer composition 30 has a thermal conductivity less than 0.35W/mK at 205°C, alternatively less than 0.30W/mK at 205°C, alternatively from about 0.1 to about 0.25W/mK at 205°C. In certain embodiments, the fluoropolymer composition 30 has a thermal conductivity less than 0.40W/mK at 20°C. Alternatively, the fluoropolymer composition 30 has a thermal conductivity less than 0.35W/mK at 20°C, alternatively less than 0.30W/mK at 20°C, alternatively from about 0.1 to about 0.25W/mK at 20°C. Not only does the fluoropolymer composition 30 have excellent thermal insulation, even at temperatures above 200°C, the fluoropolymer composition 30 is also thermally stable at these temperatures. In other words, the fluoropolymer composition 30 is capable of withstanding heat at or above 200°C without degrading the polymer and while preventing the heat from dissipating from the liquid or gas. As such, the fluoropolymer composition 30 may be used as the insulation layer. The fluoropolymer composition 30 may also include an additive. Suitable additives are described above and are generally selected to tailor the fluoropolymer composition 30 for a specific use. In general, the additives are collectively present in an amount of from about 0.1 to about 5 parts by weight based on 100 parts by weight of the fluoropolymer composition 30. [0099] In one embodiment, the fluoropolymer composition 30 comprises the reaction product of a TFE/P having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, a second TFE/P that is different than the first TFE/P and that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and TAIC. In this embodiment, the reaction product is produced by the first TFE/P is present in an amount of from about 25 to about 40 parts by weight, the second TFE/P is present in an amount of from about 45 to about 55 parts by weight, and the TAIC is present in an amount of from about 2 to about 8 parts by weight, each based on 100 parts by weight of the fluoropolymer composition 30. In addition, the fluoropolymer composition also comprises the syntactic additive in an amount of from about 12 to about 20 parts by weight based on 100 parts by weight of the fluoropolymer composition 30. The fluoropolymer composition 30 of this embodiment has excellent mechanical properties with a thermal conductivity of from about 0.1 to about 0.25W/mK at 205°C, alternatively of from about 0.1 to about 0.2W/mK at 205°C. In addition, when the fluoropolymer composition 30 comprises the reaction product described above, the fluoropolymer composition 30 has an excellent balance of mechanical properties such as tensile strength, elongation, and ductility.

[00100] Typically, the fluoropolymer composition 30 is crosslinked by heating. When heated, the organic peroxide will initiate unsaturated carbon-carbon bonds and form the reaction product of the fluoropolymer and the crosslinker. A conventional operation may be used to provide the heat required to crosslink the fluoropolymer composition 30. Alternatively, a heat oven and/or an autoclave may provide the heat required to crosslink the fluoropolymer composition 30. The temperature for crosslinking by heating is typically from 60 to 250°C, alternatively from 120 to 200° C. Further, the heating time is not particularly limited, but it is usually within a range of from one minute to forty-eight hours, alternatively within a range of from five minutes to twenty-four hours, depending upon the specific organic peroxide. Of course, if the heating temperature is increased, the heating time may be shortened. Further, reheating treatment of the obtainable cross-linked product may also be employed, and such may be useful for further improvement of the mechanical properties. For example, re-heating treatment at a temperature of from 150 to 250° C, alternatively from 180 to 230°C, for from about 2 to 25 hours, may be employed.

[00101] The fluoropolymer composition 30 may also be crosslinked by irradiation with an ionizing radiation source, with or without the organic peroxide being present. Suitable ionizing radiation sources include electron rays or γ-rays. Typically, the ionization energy is from 1 to 300 kGy, alternatively from 10 to 200 kGy.

[00102] The fluoropolymer composition 30 described above may be formed into molded products such as seals, packings, sheets, pipes, rods, tubes, angles, channels, coated fabrics, coated plates, insulation layers, or wire coatings by usual molding or other molding methods such as extrusion, transfer, calendering, roll coating, brush coating or impregnation. Alternatively, the fluoropolymer composition 30 may be formed into molded products such as sponge rubbers. In certain embodiments, because of the excellent thermal insulation, thermal stability, and mechanical properties of the fluoropolymer composition 30, the fluoropolymer composition 30 is suitable for use as a thermal insulation layer in thermally insulated liquid and/or gas transport conduits for use in subsea environments. Depending on the particular application, the fluoropolymer composition 30 may either be a solid or a syntactic foam.

[00103] As shown in Figures 3 and 4, the present disclosure provides the insulated conduit

26 for operation in the offshore, deep water environments (e.g. environments having a high temperature (e.g. greater than 130°C (e.g. 200°C) and at depths exceeding 1,000 meters). The insulated conduit 26 includes the continuous steel pipe 28 having one or more pipe sections. The steel pipe 28 has an outer surface and an inner surface. The insulated conduit 26 also includes the fluoropolymer composition 30 (hereinafter the fluoropolymer composition 30) disposed about the steel pipe 28 for providing a thermal insulation layer. Most commonly the fluoropolymer composition 30 is disposed about an entirety of the steel pipe 28, but could be partially disposed about.

[00104] It is to be appreciated that Figures 3 and 4 are not drawn to scale. As examples, the thicknesses of some of the layers are exaggerated in relation to the thicknesses of the other layers and also relative to the thickness and diameter of the steel pipe 28.

[00105] It is also be appreciated that the term "insulated conduit 26" refers to liquid and/or gas transport conduits, and is intended to include oil and gas pipelines and related components, including flowlines, risers, jumpers, spools, manifolds and ancillary equipment. Moreover, it is to be appreciated that the insulated conduit 10, can be used in environments other than the offshore, deep water environment. For example, the insulated conduit 10 can be used on land or in shallow water.

[00106] In certain embodiments, as best shown in Figure 3, the insulated conduit 26 comprises the fluoropolymer composition 30 is disposed about the steel pipe 28. In this embodiment, the fluoropolymer composition 30 is the insulation layer for the insulated conduit 26. It is to be appreciated that the insulated conduit 26 may comprise any embodiment of the fluoropolymer composition 30 described above.

[00107] In certain embodiments, the insulated conduit 26 may comprise two or more layers of the fluoropolymer composition 30 (i.e., the insulated conduit 26 has two or more insulation layers). Due to the excellent thermal insulation of the fluoropolymer composition 30, when the insulated conduit 26 transports a liquid or gas that is at a high temperature (e.g. 200°C), the fluoropolymer composition 30 insulates the insulated conduit 26 to maintain the temperature of the liquid or gas being transported. Maintaining the temperature of the liquid or gas being transported is advantageous because it prevents or reduces the formation of hydrates and waxes in the liquid or gas, particularly when the liquid is oil, which, if present, typically decreases the pumping efficiency.

[00108] Although various syntactic additives may be used, in certain embodiments of the insulated conduit 26, the syntactic additive has a crush strength of at least 15,000 psi, alternatively at least 20,000 psi, alternatively at least 25,000 psi, or alternatively at least 30,000 psi. As such, when the insulated conduit 26 comprises the syntactic additive, in particular a lime-borosilicate glass microsphere having a crush strength of at least 28,000 psi, the insulated conduit 26 is able to withstand extreme pressures and has excellent thermal insulation and thermal stability. The syntactic additive may be present in an amount of from about 1 to about 35 parts by weight based on 100 parts by weight of the fluoropolymer composition 30.

[00109] Although not required, in certain embodiments of the insulated conduit 26, the fluoropolymer composition 30 comprises the reaction product of the fluoropolymer, and the crosslinker. Typically, in these embodiments, the fluoropolymer comprises TFE/P and the crosslinker comprises the triallyl derivative of cyanuric acid. When the fluoropolymer composition 30 comprises the reaction product described above, the fluoropolymer composition 30 has excellent mechanical properties. More specifically, the fluoropolymer composition 30 has excellent thermal insulation, heat resistance, and tensile strength. As such, the insulated conduit 26 may be used in harsh environments where a balance of mechanical and thermal properties are required. For example, unlike conventional conduits, the insulated conduit 26 may operate in the offshore, deep water environments.

[00110] As described above, the fluoropolymer composition 30 of the insulated conduit 26 has excellent thermal insulation. In certain embodiments, the fluoropolymer composition 30 has a thermal conductivity less than 0.40W/mK at 205°C. Alternatively, the fluoropolymer composition 30 has a thermal conductivity less than 0.35W/mK at 205°C, alternatively less than 0.30W/mK at 205°C, alternatively from about 0.1 to about 0.25W/mK at 205°C. In certain embodiments, the fluoropolymer composition 30 has a thermal conductivity less than 0.40W/mK at 20°C. Alternatively, the fluoropolymer composition 30 has a thermal conductivity less than 0.35W/mK at 20°C, alternatively less than 0.30W/mK at 20°C, alternatively from about 0.1 to about 0.25W/mK at 20°C. Not only does the fluoropolymer composition 30 have excellent thermal insulation, even at temperatures above 200°C, the fluoropolymer composition 30 is also thermally stable at these temperatures. Due to the excellent thermal insulation of the fluoropolymer composition 30, which is in part associated with "unbroken" syntactic additive, when the insulated conduit 26 transports a liquid or gas that is at a high temperature (e.g. 200°C), the fluoropolymer composition 30 insulates the insulated conduit 26 to maintain the temperature of the liquid or gas being transported. Maintaining the temperature of the liquid or gas being transported is advantageous because it prevents or reduces the formation of hydrates and waxes in the liquid or gas, particularly when the liquid is oil, which, if present, typically decreases the pumping efficiency.

[00111] In one embodiment of the insulated conduit 26 for operation in the offshore, deep water environments, the insulated conduit 26 comprises the continuous steel pipe 28 comprising of one or more pipe sections and the fluoropolymer composition 30 is disposed about the steel pipe 28 for providing the thermal insulation layer.

[00112] The fluoropolymer composition 30 is applied on the steel pipe 28 at a sufficient thickness to provide the insulated conduit 26 with an acceptable heat transfer coefficient (U) for the conditions under which it is to be used, with U typically being in the range from about 1 to about 10 W/mK, for example from about 2 to about 8 W/mK. The thermal conductivity of the fluoropolymer composition is less than about 0.40 W/mK at 205°C, for example from about 0.10 to 0.35 W/mK at 205°C, typically from about 0.15 to 0.20 W/mK at 205°C. The thickness of the fluoropolymer composition 30 on the insulated conduit 26 is highly variable, due to the fact that each insulated conduit 10 is designed for use under specific conditions of depth, temperature, etc.

[00113] As described above, the fluoropolymer composition 30 is designed to withstand operating temperatures in excess of the maximum operating temperatures (about 200°C) of systems currently used for the thermal insulation of subsea pipelines. These operating temperatures may be as high as 270°C. In addition, the tensile strength of the fluoropolymer composition 30 is sufficiently ductile to withstand the bending strains experienced by the insulated conduit 26 during reeling and installation operations.

[00114] In certain embodiments, as best shown in Figure 4, the insulated conduit 26 may include one or more additional layers. In certain embodiments, the insulted conduit includes a corrosion protection layer 32. Typically, the corrosion protection layer 32 is comprises a high temperature corrosion protection material, such as the materials described above relative to the corrosion protection layer 16 of the insulated conduit 10. Typically, the corrosion protection layer 32 is disposed directly on the steel pipe 28. Although not required, in certain embodiments, the fluoropolymer composition 30 is disposed directly on the corrosion protection layer 32 (not shown in Figure 4).

[00115] The insulated conduit 26 may also comprise an intermediate adhesive layer 34, which may be applied directly to the insulated conduit 26 (not shown in Figure 3 or 4) or may be applied over the corrosion protection layer 32. Typically, when the intermediate adhesive layer 34 is present, the fluoropolymer composition 30 is applied over the intermediate adhesive layer 34. The composition and application of the intermediate adhesive layer 34 is described above relative to intermediate adhesive layer 34 of the insulated conduit 10.

[00116] Regardless of the layer in contact with the fluoropolymer composition 30, the fluoropolymer composition 30 must firmly adhere to the layer. Adhesion between the layers, also known as interlayer adhesion, is also dependent upon the coating temperature and the mode of application of the layers. For example, it may be necessary to pre-heat the corrosion protection layer 32 or system prior to the application of the fluoropolymer composition 30 to better fuse the two layers together and maximize interlayer adhesion. As such, when the corrosion protection layer 32 is disposed over the steel pipe 28, it is particularly advantageous to include the intermediate adhesive layer 34, as the fluoropolymer composition 30 has excellent adhesion to the intermediate adhesive layer 34. Interlayer adhesion may also be accomplished through the activation of one or more of the surfaces to be adhered using plasma or corona discharge treatment. This may also be utilized in conjunction with an intermediate adhesive layer 34.

[00117] As shown in Figure 4, a first protective layer 36 may be applied over the fluoropolymer composition 30 to provide further resistance to pressure in the offshore, deep water environments. The composition and application of the first protective layer 36 is described above relative to the first protective layer 20 of the insulated conduit 10. [00118] In certain embodiments, the insulated conduit 26 may comprise a second protective layer 38. In these embodiments, the insulated conduit 26 may also comprise a third protective layer 40. The composition and application of the second and third protective layers 38, 40, is described above relative to the second and third protective layers 22, 24 of the insulated conduit 10.

[00119] The present disclosure also provides a method for preparing the insulated conduit

26. The method includes a step of forming the fluoropolymer composition 30. The fluoropolymer composition 30 is formed by forming a first mixture comprising the fluoropolymer and the crosslinker. The method further comprises heating and or shearing the first mixture to soften the fluoropolymer. After softening, the syntactic additive is added to the first mixture to form a second mixture. Softening the fluoropolymer is important because the syntactic additive is susceptible to breakage if the fluoropolymer is not softened. The method further comprises shearing the second mixture to incorporate the syntactic additive. The storage modulus of the fluoropolymer is particularly advantageous to incorporating the syntactic additive and keeping the syntactic additive from breaking or crushing. As such, heating the fluoropolymer having the storage modulus of from about 150 to about 300 in accordance with ASTM D6204 with a frequency of IHz, strain of 0.5 degrees, and at a temperature of 100°C and then adding the syntactic additive effectively incorporates the syntactic additive and allows the fluoropolymer composition 30 to have a specific gravity less than or equal to 1.6 at room temperature. The method may further comprise adding additives and/or silica or carbon black to either the first or second mixture. The method may further comprise compounding the second mixture to form a compounded mixture. The compounded mixture typically is in the form of a ribbon or a strip, but may also be in the form of a pellet. Conventional compounding equipment may be used to compound the mixture. The method may also further include milling the mixture in a mill to produce a uniform mixture. Typically, after the syntactic additive is added, the second mixture or compounded mixture is not sheared below the softening temperature of the fluoropolymer. Avoiding shearing below the softening temperature of the fluoropolymer prevents breakage of the syntactic additive and ensures that the fluoropolymer composition 30 will have a specific gravity of less than 1.6.

[00120] The remained of the method (i.e., the application of the individual layers) relative to the application of the fluoropolymer composition 30, corrosion protection layer 32, the intermediate adhesive layer 34, the first, second and/or third protective layers 36, 38, 40, is described above with respect to the insulated conduit 10 and the corresponding respective layers.

[00121] Typically, extrusion of the fluoropolymer composition may be accomplished using single screw extrusion, either in single or tandem configuration, or by twin-screw extrusion methods. In the case of single screw extrusion, the extruder screw may be either single stage or 2-stage design. Typically, the fluoropolymer composition 30 is heated prior to extrusion to soften the fluoropolymer composition 30 to avoid breaking the syntactic additives during extrusion. In other words, the fluoropolymer composition 30 is heated prior to shearing the fluoropolymer composition 30, which reduces the stress placed on the syntactic additive and avoids breaking the syntactic additive during the extrusion process. In certain embodiments, the fluoropolymer composition 30 is heated above 40, above 50, above 60, above 70, above 80, or alternatively above 90°C prior to extrusion.

[0001] The following examples are intended to illustrate the invention and are not to be viewed in any way as limiting to the scope of the invention.

EXAMPLES [00122] A sample of the first fluoropolymer composition and five comparative fhioropolymer compositions samples were prepared. The samples are provided below in Table I. Each value provided in Table 1 is the parts (by weight) of the respective component added.

Table I

[00123] Fluoropolymer 1 is a TFE/P copolymer that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and has a storage modulus of 80 as measured in accordance with ASTM D6204 with a frequency of IHz, strain of 0.5 degrees, and at a temperature of 100°C.

[00124] Fluoropolymer 2 is a TFE/P copolymer that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and that has a storage modulus of 180 as measured in accordance with ASTM D6204 with a frequency of IHz, strain of 0.5 degrees, and at a temperature of 100°C.

[00125] Fluoropolymer 3 is a TFE/P copolymer having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and a storage modulus of 180 as measured in accordance with ASTM D6204 with a frequency of IHz, strain of 0.5 degrees, and at a temperature of 100°C.

[00126] Fluoropolymer 4 is a TFE/P copolymer that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and that has a storage modulus of 289 as measured in accordance with ASTM D6204 with a frequency of IHz, strain of 0.5 degrees, and at a temperature of 100°C.

[00127] Fluoropolymer 5 is a TFE/P copolymer that does not have an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1, and that has a storage modulus of

350 as measured in accordance with ASTM D6204 with a frequency of IHz, strain of 0.5 degrees, and at a temperature of 100°C.

[00128] The carbon black is a thermal carbon black.

[00129] The silica is a hydrophilic fumed silica.

[00130] The crosslinker is TAIC.

[00131] The processing aid is calcium stearate.

[00132] The adhesion aid is magnesium oxide.

[00133] The organic peroxide is a 40 wt. % solution of di(tert-butylperoxyisopropyl) benzene.

[00134] Compounded mixtures of Sample 1 and Comparative Samples 1-5 were prepared and crosslinked by heating to 177°C for 10 minutes. The thermal conductivity value of the samples were evaluated and the results are displayed in Table II. Mechanical properties of the samples were evaluated and the results are displayed in Table III.

Table II Comp. Comp.

Component Spl. 1 Spl. 1 Spl. 2

Sample 3 Sample 5

Thermal

Conductivity at 0.2051 0.2165 0.2035 0.2003 0.2020

20°C (W/mK))

Standard Dev

0.0004 0.0024 0.0012 0.0005 0.0004

(n=5) for 20°C

Thermal

Conductivity at 0.1848 0.1896 0.1881 0.1849 0.1857

205°C

Standard Dev

(n=5) for 205°C 0.0010 0.0006 0.0009 0.0010 0.0025

(W/mK))

Table III

[00135] As shown in Table II, Sample 1 has excellent thermal insulation, particularly at

205°C, which makes the fluoropolymer composition ideal for offshore, deep water environments (e.g. environments having a high temperature (e.g. greater than 130°C (e.g. 200°C) and at depths exceeding 1,000 meters).

[00136] As shown in Table III, the tensile strength, 100% modulus, and tensile elongation were measured in accordance with ASTM 5412. The data indicates that Sample 1 has the best combination of mechanical properties. Specifically, Sample 1 has excellent tensile strength, excellent 100% modulus, and excellent tensile strength. As such, Sample 1 is particularly suitable for the offshore deep water environments. [00137] Samples of the second fluoropolymer composition were prepared. Samples 1-10 are provided below in Table IV. Each value provided in Table IV is the parts (by weight) of the respective component added.

Table IV

[00138] Fluoropolymer 2, fluoropolymer 3, fluoropolymer 4, silica, crosslinker, adhesion aid and organic peroxide 1 are as defined above.

[00139] Syntactic additive 1 is glass bubble beads having a crush strength of 5,000 psi.

[00140] Syntactic additive 2 is soda-lime-borosilicate glass bubble beads having a crush strength of 28,000 psi.

[00141] Processing aid 2 is calcium stearate.

[00142] Processing aid 3 is a blend of fatty acid derivates and waxes.

[00143] Organic peroxide 2 is di(tert-butylperoxyisopropyl) benzene. [00144] The Samples 1-10 were compounded and cured at 177°C for 10 minutes. Thermal conductivity and mechanical properties were measured. The results of this testing are shown below in Table V.

Table V

[00145] The data indicates that Samples 1-10 have excellent mechanical properties.

Specifically, Samples 1-10 have excellent tensile strength, excellent 100% modulus, and excellent tensile strength. As such, samples 1-10 are particularly suitable for the offshore, deep water environments (e.g. environments having a high temperature (e.g. greater than 200°C) and at depths exceeding 1,000 meters).

[00146] As shown in Table V, Samples 1-10 have excellent thermal insulation, particularly at 205°C, which makes the fluoropolymer composition ideal for offshore, deep water environments.

[00147] It is to be understood that the appended claims are not limited to express and particular compounds, compositions, or methods described in the detailed description, which may vary between particular embodiments which fall within the scope of the appended claims. With respect to any Markush groups relied upon herein for describing particular features or aspects of various embodiments, different, special, and/or unexpected results may be obtained from each member of the respective Markush group independent from all other Markush members. Each member of a Markush group may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims.

[00148] Further, any ranges and subranges relied upon in describing various embodiments of the present invention independently and collectively fall within the scope of the appended claims, and are understood to describe and contemplate all ranges including whole and/or fractional values therein, even if such values are not expressly written herein. One of skill in the art readily recognizes that the enumerated ranges and subranges sufficiently describe and enable various embodiments of the present invention, and such ranges and subranges may be further delineated into relevant halves, thirds, quarters, fifths, and so on. As just one example, a range "of from 0.1 to 0.9" may be further delineated into a lower third, i.e., from 0.1 to 0.3, a middle third, i.e., from 0.4 to 0.6, and an upper third, i.e., from 0.7 to 0.9, which individually and collectively are within the scope of the appended claims, and may be relied upon individually and/or collectively and provide adequate support for specific embodiments within the scope of the appended claims. In addition, with respect to the language which defines or modifies a range, such as "at least," "greater than," "less than," "no more than," and the like, it is to be understood that such language includes subranges and/or an upper or lower limit. As another example, a range of "at least 10" inherently includes a subrange of from at least 10 to 35, a subrange of from at least 10 to 25, a subrange of from 25 to 35, and so on, and each subrange may be relied upon individually and/or collectively and provides adequate support for specific embodiments within the scope of the appended claims. Finally, an individual number within a disclosed range may be relied upon and provides adequate support for specific embodiments within the scope of the appended claims. For example, a range "of from 1 to 9" includes various individual integers, such as 3, as well as individual numbers including a decimal point (or fraction), such as 4.1, which may be relied upon and provide adequate support for specific embodiments within the scope of the appended claims.

[00149] The present invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. The present invention may be practiced otherwise than as specifically described. The subject matter of all combinations of independent and dependent claims, both singly and multiply dependent, is herein expressly contemplated.

Claims

1. A fluoropolymer composition comprising;

a first fluoropolymer having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1;

a second fluoropolymer that is different than said first fluoropolymer; and

a crosslinker.

2. The fluoropolymer composition as set forth in claim 1 wherein said first fluoropolymer is formed by heat-treating a mixture comprising a precursor of said first fluoropolymer and a first organic peroxide.

3. The fluoropolymer composition as set forth in claim 2 wherein heat-treating the mixture comprises heating at a temperature of from 110 to 380°C for from 10 seconds to 3 hours.

4. The fluoropolymer composition as set forth in claim 2 or 3 wherein said precursor of said first fluoropolymer is a tetrafluoroethylene propylene copolymer.

5. The fluoropolymer composition as set forth in any one of claims 1 to 4 wherein said second fluoropolymer is a tetrafluoroethylene propylene copolymer.

6. The fluoropolymer composition as set forth in any one of claims 1 to 5 wherein said crosslinker is a triallyl derivative of cyanuric acid.

7. The fluoropolymer composition as set forth in any one of claims 1 to 6 further comprising a second organic peroxide that is the same as or different than said first organic peroxide.

8. The fluoropolymer composition as set forth in any one of claims 1 to 7 wherein said first fluoropolymer is present in an amount of from about 20 to about 45 parts by weight based on 100 parts by weight of said fluoropolymer composition.

9. The fluoropolymer composition as set forth in any one of claims 1 to 8 wherein said second fluoropolymer is present in an amount of from about 35 to about 65 parts by weight based on 100 parts by weight of said fluoropolymer composition.

10. The fluoropolymer composition as set forth in any one of claims 1 to 9 wherein said crosslinker is present in an amount of from about 1 to about 10 parts by weight based on 100 parts by weight of said fluoropolymer composition.

11. The fluoropolymer composition as set forth in any one of claims 1 to 10 further comprising a filler selected from the group of carbon black, silica, and combinations thereof, wherein said filler is present in an amount of from about 5 to about 15 parts by weight based on 100 parts by weight of said fluoropolymer composition.

12. The fluoropolymer composition as set forth in any one of claims 1 to 11 further comprising a syntactic additive present in an amount of from about 1 to about 30 parts by weight based on 100 parts by weight of said fluoropolymer composition.

13. The fluoropolymer composition as set forth in any one of claims 1 to 12 comprising the reaction product of said first fluoropolymer, said second fluoropolymer, and said crosslinker.

14. The fluoropolymer composition as set forth in claim 13 having a thermal conductivity less than 0.40W/mK at 205°C.

15. The fluoropolymer composition as set forth in claim 13 or 14 having a thermal conductivity of from about 0.1 to about 0.25W/mK at 205°C.

16. An insulated conduit for use in offshore, deep water environments, said insulated conduit comprising;

a continuous steel pipe comprising of one or more pipe sections, wherein said steel pipe has an outer surface and an inner surface; and

a fluoropolymer composition disposed about said steel pipe for providing a thermal insulation layer, said fluoropolymer composition comprising,

a first fluoropolymer having an absorption peak on an infrared absorption spectrum from 1,640 to 1,700 cm-1,

a second fluoropolymer that is different than said first fluoropolymer, and a crosslinker.

17. The insulated conduit as set forth in claim 16 wherein said first fluoropolymer is formed by heat-treating a mixture comprising a precursor of said first fluoropolymer and a first organic peroxide.

18. The insulated conduit as set forth in claim 17 wherein heat-treating the mixture comprising said precursor of said first fluoropolymer and said first organic peroxide comprises heating at a temperature of from 110 to 380°C for from 10 seconds to 3 hours.

19. The insulated conduit as set forth in claim 17 or 18 wherein said precursor of said first fluoropolymer is a tetrafluoroethylene propylene copolymer.

20. The insulated conduit as set forth in any one of claims 16 to 19 wherein said second fluoropolymer is a tetrafluoroethylene propylene copolymer.

21. The insulated conduit as set forth in any one of claims 16 to 20 wherein said crosslinker is a triallyl derivative of cyanuric acid.

22. The insulated conduit as set forth in any one of claims 16 to 21 wherein said fluoropolymer composition further comprises a second organic peroxide that is the same as or different than said first organic peroxide.

23. The insulated conduit as set forth in any one of claims 16 to 22 wherein said first fluoropolymer is present in an amount of from about 20 to about 45 parts by weight based on 100 parts by weight of said fluoropolymer composition.

24. The insulated conduit as set forth in any one of claims 16 to 23 wherein said second fluoropolymer is present in an amount of from about 35 to about 65 parts by weight based on 100 parts by weight of said fluoropolymer composition.

25. The insulated conduit as set forth in any one of claims 16 to 24 wherein said crosslinker is present in an amount of from about 1 to about 10 parts by weight based on 100 parts by weight of said fluoropolymer composition.

26. The insulated conduit as set forth in any one of claims 16 to 25 wherein said fluoropolymer composition further comprises a filler selected from the group of carbon black, silica, and combinations thereof present in an amount of from about 5 to about 15 parts by weight based on 100 parts by weight of said fluoropolymer composition.

27. The insulated conduit as set forth in any one of claims 16 to 25 wherein said fluoropolymer composition further comprises a syntactic additive present in an amount of from about 1 to about 30 parts by weight based on 100 parts by weight of said fluoropolymer composition.

28. The insulated conduit as set forth in any one of claims 16 to 27 wherein said fluoropolymer composition comprises the reaction product of said first fluoropolymer, said second fluoropolymer, and said crosslinker.

29. The insulated conduit as set forth in claim 28 wherein said fluoropolymer composition has a thermal conductivity less 0.40W/mK at 205°C.

30. The insulated conduit as set forth in claim 28 or 29 wherein said fluoropolymer composition has a thermal conductivity of from about 0.1 to about 0.25W/mK at 205°C.

31. An insulated conduit for use in offshore, deep water environments, said insulated conduit comprising;

a fluoropolymer composition disposed about said steel pipe for providing a thermal insulation layer, said fluoropolymer composition comprising the reaction product of,

a first fluoropolymer having an absorption peak on an infrared absorption spectrum from 1,640 to 1,700 cm-1, present in an amount of from about 20 to about 45 parts by weight based on 100 parts by weight of said fluoropolymer composition,

a second fluoropolymer that is different than said first fluoropolymer, and present in an amount of from about 35 to about 65 parts by weight based on 100 parts by weight of said fluoropolymer composition, and

a triallyl derivative of cyanuric acid present in an amount of from about 1 to about 10 parts by weight based on 100 parts by weight of said fluoropolymer composition; wherein said fluoropolymer composition has a thermal conductivity of less than about 0.40 W/mK at 205°C.

32. The insulated conduit as set forth in claim 31 wherein said first fluoropolymer is formed by heat-treating a mixture comprising a precursor of said first fluoropolymer and a first organic peroxide.

33. The insulated conduit as set forth in claim 32 wherein heat-treating the mixture comprises heating at a temperature of from 110 to 380°C for from 10 seconds to 3 hours.

34. The insulated conduit as set forth in claims 32 or 33 wherein said precursor of said first fluoropolymer is a tetrafluoroethylene propylene copolymer.

35. The insulated conduit as set forth in any one of claims 31 to 34 wherein said fluoropolymer composition further comprises a filler selected from the group of carbon black, silica, and combinations thereof present in an amount of from about 5 to about 15 parts by weight based on 100 parts by weight of said fluoropolymer composition.

36. The insulated conduit as set forth in any one of claims 31 to 35 wherein said fluoropolymer composition further comprises a filler selected from the group of carbon black, silica, and combinations thereof, wherein said filler is present in an amount of from about 5 to about 15 parts by weight based on 100 parts by weight of said fluoropolymer composition.

37. The insulated conduit as set forth in any one of claims 31 to 36 wherein said fluoropolymer composition has a thermal conductivity of from about 0.1 to about 0.25W/mK at 205°C.

38. A fluoropolymer composition comprising;

a first fluoropolymer; and

a syntactic additive present in an amount of from about 10 to about 30 volume percent based on a total volume of said fluoropolymer composition;

wherein said fluoropolymer composition has a specific gravity less than or equal to 1.6.

39. The fluoropolymer composition as set forth in claim 38 wherein said fluoropolymer is a tetrafluoroethylene propylene copolymer.

40. The fluoropolymer composition as set forth in claim 39 wherein said fhioropolymer is a tetrafhioroethylene propylene copolymer having an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1.

41. The fluoropolymer composition as set forth in claim 39 wherein a portion of said tetrafhioroethylene propylene copolymer has an absorption peak on an infrared absorption spectrum at from 1,640 to 1,700 cm-1.

42. The fluoropolymer composition as set forth in any one of claims 38 to 41 wherein said fluoropolymer has a storage modulus of from about 150 to about 300 as measured in accordance with ASTM D6204 with a frequency of IHz, strain of 0.5 degrees, and at a temperature of 100^°C.

43. The fluoropolymer composition as set forth in any one of claims 38 to 42 wherein said fluoropolymer is present in an amount of from about 60 to about 90 parts by weight based on 100 parts by weight of said fluoropolymer composition.

44. The fluoropolymer composition as set forth in any one of claims 38 to 43 further comprising a crosslinker present in an amount of from about 1 to about 10 parts by weight based on 100 parts by weight of said fluoropolymer composition.

45. The fluoropolymer composition as set forth in claim 44 wherein said crosslinker is a triallyl derivative of cyanuric acid.

46. The fluoropolymer composition as set forth in any one of claims 38 to 45 further comprising an organic peroxide.

47. The fluoropolymer composition as set forth in any one of claims 38 to 46 further comprising a filler selected from the group of carbon black, silica, and combinations thereof, wherein said filler is present in an amount of from about 5 to about 15 parts by weight based on 100 parts by weight of said fluoropolymer composition.

48. The fluoropolymer composition as set forth in any one of claims 44 to 47 comprising the reaction product of said fluoropolymer and said crosslinker.

49. The fluoropolymer composition as set forth in claim 48 having a thermal conductivity less than 0.4W/mK at 205°C.

50. The fluoropolymer composition as set forth in claims 48 or 49 having a thermal conductivity from about 0.1 to about 0.25W/mK at 205°C.

51. A method comprising compounding the fluoropolymer composition as set forth in anyone of 1 to 12 or 38 to 47.

52. A method comprising extruding the fluoropolymer composition as set forth in anyone of claims 1 to 12, 37 to 47, or 51 about a steel pipe to form a thermal insulation layer.