Underwater pipe comprising an inner sealing sheath made of polyaryletherketone

Abstract

The application relates to an underwater pipe for transporting hydrocarbons and / or gases, the pipe comprising, from the outside to the inside: - at least one reinforcing layer; and - a inner polymeric sealing sheath comprising a layer of polymeric material sheathed around a metal armature, characterised in that the polymeric material of the layer of the inner polymeric sealing sheath is a composition C comprising a delamination-resistant polymer mixture M, wherein the mixture M comprises at least one pseudo-amorphous or semi-crystalline polyaryletherketone having a melting point that is less than or equal to 340°C, and a poly(etherimide-siloxane) copolymer, the application further relating to the preparation method thereof and to the uses thereof in the transportation of hydrocarbons and / or gases.

Description

[0001] TITLE: Subsea pipeline comprising an internal polyaryletherketone sealing sheath

[0002] The present invention relates to an underwater pipeline intended for the transport of hydrocarbons in deep water or for the transport of gas, typically CO2.

[0003] These pipes are likely to be used under high pressures, greater than 100 bars, or even up to 1000 bars, and at high temperatures, greater than 130°C, or even 170°C, for long periods of time, i.e. several years, typically 20 years.

[0004] Subsea pipelines intended for the transport of hydrocarbons or gas in deep water generally include at least one reinforcing layer around an internal sealing polymer sheath, in which the hydrocarbons or gases circulate.

[0005] The material constituting the internal sealing polymer sheath must be chemically stable and capable of mechanically resisting the transported fluid and its characteristics (composition, temperature and pressure). The material must combine characteristics of ductility, resistance to time (generally, the pipe must have a lifespan of at least 20 years), mechanical resistance, heat and pressure. In particular, the material must be chemically inert with respect to the chemical compounds constituting the transported fluid or have aging kinetics compatible with the application.

[0006] Various polymer materials are used in the internal polymeric sealing sheath of a flexible subsea pipeline, for example: polyethylene, particularly medium or high density polyethylene, for low temperature applications (typically below 90°C). However, polyethylene is susceptible to blistering under certain conditions. polyamide (PA), particularly polyamide 11. Unlike polyethylene, polyamide has good resistance to blistering under pressure and temperature, as well as a low tendency to swell when in contact with the petroleum fluid. Polyamide is generally used for hydrocarbon transport conditions where the pressure is high and the temperature preferably remains below 90°C, or even for a temperature that can rise to 110°C.

[0007] On the other hand, one of the disadvantages of polyamide is that it tends to hydrolyze in the presence of water, often contained in production crudes (chemical aging). Hydrolysis is rapid when subjected to temperatures (around 110°C and above) and low pH values ​​(pH below 7). Another disadvantage is its purchase cost, which is significantly higher than that of polyethylene. Polyvinylidene fluoride (PVDF) has very good chemical inertness. PVDF-based sheaths can withstand high operating pressures as well as temperatures of up to 130°C-150°C.

[0008] Its major drawback remains its price, much higher than that of polyethylene or polyamide.

[0009] The use of thermoplastic materials in unbonded flexible pipe is summarized in API RP 17B (2014) and API 17J (2014) published by the American Petroleum Institute.

[0010] The use of the above-mentioned polymer materials is, however, limited due to their insufficient resistance to gas permeation, particularly CO2.

[0011] Indeed, the hydrocarbons transported typically include crude oil, water, and pressurized gases, such as hydrogen sulfide (H2S) in a concentration generally of the order of 100 ppm, carbon dioxide (CO2) at a pressure of up to 100 bars (such pressures can be reached for certain underwater wells extracting oil from pre-salt deposits) and methane (CH4) generally at a pressure of between 1 bar and several hundred bars.

[0012] The amount of acidic species such as CO2 within the pipeline tends to increase due to gas reinjection in service, leading to high partial pressures of CO2 in the transported hydrocarbons.

[0013] Similarly, gas transmission pipelines, and more specifically gas injection pipelines, primarily transport CO2, and CO2 permeation is also an issue.

[0014] Thus, flexible pipes with an internal sealing sheath preventing the penetration of CO2 into the rest of the multi-layer pipe are traditionally used for several types of lines such as those for gas injection, oil production, gas export and gas refueling operations.

[0015] These gases (H2S and / or CO2) can lead to the degradation of the reinforcement layers located outside the internal polymeric sealing sheath. These reinforcement layers, often metallic or made of composite material, are typically tensile armor plies and / or a pressure vault. A metallic reinforcement layer is particularly subject to stress corrosion cracking (SCC). Indeed, under the operating conditions of the pipe, the at least one metallic reinforcement layer is subject to very high radial pressure or longitudinal tension stresses and is in a very corrosive environment, particularly in the presence of CO2 and H2S. Stress corrosion causes the appearance of cracks and degrades the at least one reinforcement layer.

[0016] Using an internal polymeric sealing sheath with a barrier effect to gases likely to damage this / these reinforcing layer(s) makes it possible to improve the resistance of the pipe by reducing the composition of the annulus, and in particular to improve the resistance to stress corrosion of the at least one reinforcing layer, and therefore the service life of the pipe.

[0017] The literature teaches that poly-aryl ether ketones (PAEKs), and in particular poly-ether ketone ketones (PEKK), have low CO2 permeation. Blocking gas permeation requires a polymer whose chains have low mobility in the operating temperature range and which has the ability to crystallize upon cooling.

[0018] However, the polymeric material of the inner polymeric sheath of a pipe is used in a temperature range significantly lower than its glass transition temperature. Due to the very strong inter-chain bonds, polyaryletherketones are very rigid and their elongation at break, typically 1 to 8%, is often considered too low to allow their use as a polymeric material of the inner polymeric sheath of a flexible pipe. The required elongation at break is generally greater than 8%, preferably greater than 10%, particularly preferably greater than 15%, or even greater than 20%. Thus, a sheath based on polyaryletherketone does not have the flexibility required to be used as an inner polymeric sheath of a flexible pipe for the intended applications.

[0019] The introduction of an elastomeric phase can lower the stiffness and increase the flexibility of the polyaryletherketone, provided that this elastomeric phase is well dispersed. Thus, in order to maintain low permeation, it is important to introduce, within the polyaryletherketone matrix, a finely dispersed impact modifier phase, which provides compatibility at the micrometer scale, and has no significant impact on the crystallization of the polyaryletherketone matrix.

[0020] But adding an impact modifier is not enough to prepare a flexible pipe inner polymer sheath. Another challenge is to successfully extrude the material in the form of a layer, and around the carcass required for deep subsea applications so that the pipe can withstand external pressure. The crosshead extrusion process required for this operation requires a long residence time of the molten polymer. Therefore, the chosen formulation must be stable in the molten state for at least 5 minutes, preferably 10 minutes, and even preferably 20 minutes.

[0021] Application WO 2019 / 150060 highlights the difficulties of compounding blends of poly(aryletherketone) and polysiloxane. It describes a polymer blend, comprising a poly(aryletherketone), a polysiloxane and a polysiloxane block copolymer. This blend has good impact resistance, good elongation at break and improved flexibility. The advantageous mechanical properties are said to be linked to the presence of the polysiloxane block copolymer, which ensures better dispersion of the polysiloxane within the poly(aryletherketone) by acting as a surfactant. The composition of this application is described as being usable for the manufacture of sheaths or pipes in pipelines in the oil field.

[0022] Exemplified herein are compositions consisting of a mixture of polyetherketoneketone (PEKK), 3.75% to 7.5% by weight of a poly(etherimide-siloxane) copolymer, and 3.5% to 7% by weight of polydimethylsiloxane.

[0023] The introduction of polydimethylsiloxane in high proportions has sometimes proven complicated to implement because polydimethylsiloxane can be in the form of a very viscous liquid that is difficult to handle and to introduce in a well-controlled proportion into a composition. Furthermore, the addition of polydimethylsiloxane to a composition tends to reduce its barrier properties.

[0024] Finally, compared to the manufacture of conventional plastic parts, the particularity of the extrusion of polymer sheaths for flexible pipes is that it is a continuous thick-walled extrusion process. This thickness can induce different cooling rates on the surface of the sheath or in the mass of the extruded sheath. Consequently, the crystallization kinetics of the polymer formulation must preferably allow a sufficient level of crystallization to be achieved to obtain the desired gas permeation.

[0025] One of the objectives of the present invention is to provide an underwater pipe for the transport of hydrocarbons and / or gas (in particular CO2) whose internal sealing polymer sheath presents a good compromise between low permeation to gas and in particular to CO2 and sufficient elongation at break, in particular in order to ensure the flexibility of the sheath and therefore of the pipe.

[0026] One of the objectives is to provide a subsea pipeline whose sheath has good aptitude for being prepared by extrusion, in particular a sheath whose polymeric material is stable in the molten state for at least 5 minutes.To these ends, according to a first object, the invention relates to an underwater pipe intended for the transport of hydrocarbons and / or gas comprising from the outside to the inside: at least one reinforcing layer, an internal polymeric sealing sheath comprising a layer of polymeric material sheathed around a metal carcass, characterized in that the polymeric material of said layer of the internal polymeric sealing sheath is a composition C comprising a non-delaminating mixture M of polymers, the mixture M comprising: at least 50% by weight of at least one polyaryletherketone, pseudo-amorphous or semi-crystalline, said polyaryletherketone having a melting temperature of less than or equal to 340°C, relative to the total weight of the mixture M; and, from 5% to 40% by weight of a poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M.

[0027] Definitions

[0028] "Transport of hydrocarbons and / or gas" means the transport of hydrocarbons, gas or a mixture thereof. The gas is preferably CO2.

[0029] By "sheathed around" we mean that the metal carcass is coated with the layer of internal polymeric sealing sheath.

[0030] The term "thermoplastic polymer" refers to a polymer that becomes less viscous, or more liquid, or liquid when heated sufficiently and that reversibly retains its thermoplasticity. Thermoplastic polymers are generally contrasted with thermosetting polymers, which irreversibly transform into an insoluble, non-formable polymer network when heated.

[0031] The term "homopolymer" is understood to mean a polymer consisting of a single repeating unit.

[0032] The term "copolymer" refers to a polymer resulting from the copolymerization of at least two types of chemically different monomers, called comonomers. A copolymer is therefore formed of at least two repeating units from different monomers. It can also be formed of three or more repeating units from different monomers.

[0033] The copolymer may have a homogeneous structure, in particular of the statistical, alternating or random type, or a heterogeneous structure, in particular of the sequenced or block type. In particular, the term "block copolymer" or "block copolymer" is understood to denote copolymers in the aforementioned sense, in which at least two distinct homopolymer blocks are covalently linked. The length of the blocks may be variable. The blocks may be composed of 1 to 1000, preferably 1 to 500, more preferably 1 to 100, and in particular 1 to 50 repeating units, respectively. The link between the two homopolymer blocks may be: a simple covalent bond or an intermediate non-repeating unit called a junction block.

[0034] “Consisting essentially of unit(s)” means that the unit(s) represent(s) a molar proportion of 95% to 99.9% of the total number of moles of repeating units in the polymer.

[0035] “Consisting of unit(s)” means that the unit(s) represent(s) a molar proportion of at least 99.9%, in particular 100%, in the polymer relative to the total number of moles of repeating units in the polymer.

[0036] The term "non-delaminating polymer blend" is understood to mean a macroscopically homogeneous polymer composition. The term includes in particular such compositions composed of phases immiscible with each other and dispersed on a micrometric or submicron scale. The term "non-delaminating" refers in particular to the property of the composition or the polymeric sheath sealing the pipe, of not exhibiting any visually observable separation into several layers, such as flaking or onion skin effect.

[0037] The term "glass transition temperature", denoted T, is understood to mean g, designate the temperature at which an at least partially amorphous polymer passes from a rubbery state to a glassy state, or vice versa, as measured by differential scanning calorimetry (DSC) according to standard NF ISO 1 1357-2:2020, in second heating, using temperature ramps in heating and cooling at 20°C / min. In the present application, when reference is made to a glass transition temperature, it is more particularly, unless otherwise indicated, the glass transition temperature at half-step height as defined in this standard.

[0038] The term "melting temperature", denoted T, is understood to mean f, designate the temperature at which a semi-crystalline polymer passes into the viscous liquid state, as measured by differential scanning calorimetry (DSC) according to standard NF EN ISO 11357-3:2018, in the second heating, using a heating rate of 20°C / min. In this application, when reference is made to a melting temperature, it is more particularly, unless otherwise indicated, the peak melting temperature as defined in this standard.

[0039] The term "pseudo-amorphous" polymer refers to a polymer that does not exhibit a melting endotherm as measured by differential scanning calorimetry (DSC) according to standard NF EN ISO 11357-3:2018, in the second heating, using heating and cooling rates of 20°C / min. The pseudo-amorphous polymer is nevertheless capable of crystallizing once heated to a temperature above its glass transition temperature, in particular to a temperature in the range Tg+40°C to Tg+110°C, for example at Tg+75°C, for a sufficient time, in particular for 10 to 30 minutes, for example 20 minutes. Thus, a melting temperature can also be measured in the second heating for pseudo-amorphous polymers, by proceeding as follows:

[0040] - 1 èreheating according to a ramp of 20°C / min up to a plateau temperature in the range Tg+40°C to Tg+1 10°C, for example to Tg+75°C, for a sufficient time, in particular for 10 to 30 minutes, for example 20 minutes, in particular at Tg+75°C for 20 minutes;

[0041] - Cooling at a rate of 20°C / min to room temperature;

[0042] - 2 ème heating according to a ramp at 20°C / min.

[0043] The term "modulus of elasticity in tension", or more simply "elastic modulus" or "modulus of elasticity", is understood to mean the slope of the stress-strain curve C(E) in the interval between the two strains £i = 0.05% and £2 = 0.25%, as defined in ISO 527-1:2019. The elastic modulus is here expressed in gigapascals (GPa). The slope is preferably measured by a linear regression method. Although the elastic modulus is here determined by a mechanical stress in tension, the measurement could be made from other types of stress, for example in bending or compression.

[0044] Nominal strain means the strain calculated from the displacement of the grips and the clamping distance of the test apparatus, as defined in ISO 527-1:2019. Nominal strain at break or elongation at break means the strain at the last point recorded before the stress is reduced to a value less than or equal to 10% of the strength when failure occurs after the yield point, as defined in ISO 527-1:2019. It is expressed as a dimensionless ratio or as a percentage (%).

[0045] The actual measurement of the elastic modulus and the nominal strain at break corresponding to the average of five tests carried out consecutively. These tests can, for example, be implemented using an MTS 810® device, marketed by MTS Systems Corporation, equipped with a mechanical extensometer.

[0046] The term "Charpy impact strength", or more simply "impact strength", refers to the impact strength of bars measuring 80*10*4 mm. 3 notched type A, as measured according to ISO 179:2010. The actual measurement corresponds to the average of 10 tests carried out consecutively. A notch (V-shaped with a notch bottom radius of 0.25 + / - 0.05 mm) can be implemented on a device specially designed for this purpose (Automatic Notchvis Plus), marketed by the company Ceast). The bars are then left to rest for 24 hours. The impact resistance measurement can be carried out on a Zwick 5102 impact testing machine.

[0047] Generally, those skilled in the art use the term "gas permeation" for a sheath or layer, and "gas permeability" for a material, but these two expressions correspond to the same property. For the purposes of the present application, the term "gas permeation" has been chosen. Gas permeability is typically measured by following the fluid permeability test method of API17J 2009.

[0048] The singular forms “a” and “the” applied to composition constituents, such as polyaryletherketone having a melting temperature of less than or equal to 340°C, or poly(etherimide-siloxane) copolymer, mean by default “at least one” and respectively “said at least one”. The singular forms nevertheless include, without it being necessary to recall it each time, the embodiments where “a” means “a single one” and “the” means “the only one”.

[0049] Polyaryletherketone

[0050] The non-delaminating mixture M of polymers comprises at least 50% by weight of at least one polyaryletherketone having a melting temperature of less than or equal to 340°C, relative to the total weight of mixture M.

[0051] The non-delaminating mixture M of polymers may in particular comprise at least 60% by weight, or at least 70%, or at least 80% by weight, or at least 85% by weight of said at least one polyaryletherketone having a melting temperature of less than or equal to 340°C, relative to the total weight of mixture M.

[0052] Optionally, the mixture M may also comprise from 0% to 40% by weight of a polyaryletherketone having a melting temperature strictly above 340°C as another thermoplastic polymer. The mixture M may in particular comprise more than 5% by weight of a polyaryletherketone having a melting temperature strictly above 340°C as another thermoplastic polymer, relative to the total weight of the mixture M. The mixture M (and preferably the composition C) may in particular comprise less than 30% by weight, or less than 25% by weight, or less than 20% by weight, or less than 15% by weight, or even less than 10% by weight of a polyaryletherketone having a melting temperature strictly above 340°C as another thermoplastic polymer, relative to the total weight of the mixture M.

[0053] According to certain embodiments, the mixture M does not comprise, and preferably the composition C does not comprise, any other polyaryletherketone than said at least one polyaryletherketone having a melting temperature of less than or equal to 340°C. A polyaryletherketone (PAEK) comprises the units of the following formulas: (-Ar-X-) and (-Ari-Y-), in which:

[0054] - Ar and A each denote a divalent aromatic radical;

[0055] - Ar and A may preferably be chosen from 1,3-phenylene, 1,4-phenylene, 1,1'-biphenylene divalent in positions 3,3', 1,1'-biphenyl divalent in positions 3,4', 1,4-naphthylene, 1,5-naphthylene and 2,6-naphthylene;

[0056] - X denotes an electron-withdrawing group; it may preferably be chosen from the carbonyl group and the sulfonyl group,

[0057] - Y denotes a group selected from an oxygen atom, a sulfur atom, an alkylene group, such as -(CH)2- and isopropylidene.

[0058] In these X and Y units, at least 50%, preferably at least 70% and more particularly at least 80% of the X groups are a carbonyl group, and at least 50%, preferably at least 70% and more particularly at least 80% of the Y groups represent an oxygen atom.

[0059] According to a preferred embodiment, 100% of the X groups denote a carbonyl group and 100% of the Y groups represent an oxygen atom.

[0060] Advantageously, the PAEK(s) may be chosen from:

[0061] - a polyether-ketone-ketone, also called PEKK; a PEKK comprises one or more units of formula: -Ph-O-Ph-C(O)-Ph-C(O)-;

[0062] - a polyether-ether-ketone, also called PEEK; a PEEK comprises one or more units of formula: -Ph-O-Ph-O-Ph-C(O)-;

[0063] - a polyether ketone, also called PEK; a PEK comprises one or more units of formula: -Ph-O-Ph-C(O)-;

[0064] - a polyether-ether-ketone-ketone, also called PEEKK; a PEEKK comprises one or more units of formula: -Ph-O-Ph-O-Ph-C(O)- Ph-C(O)-;

[0065] - a polyether-ether-ether-ketone, also called PEEEK; a PEEEK comprises one or more units of formula: -Ph-O-Ph-O-Ph-O- Ph-C(O)-;

[0066] - a poly-ether-diphenyl-ether-ketone also called PEDEK; a PEDEK comprises one or more units of formula: a PEDEK comprises one or more units of formula -Ph-O-Ph- Ph-O-Ph-C(O)-;

[0067] - their mixtures; and,

[0068] - copolymers comprising at least two of the above-mentioned units, in which: Ph represents a phenylene group and -C(O)- a carbonyl group, each of the phenylenes being able independently to be of the ortho (1-2), meta (1-3) or para (1-4) type, preferably being of the meta or para type. In addition, defects, terminal groups and / or monomers can be incorporated in very small quantities into the polymers as described in the list above, without having an impact on their performance.

[0069] According to certain embodiments, the PAEK having a melting temperature of less than or equal to 340°C is a polyether-ketone-ketone (PEKK) essentially consisting of, and preferably consisting of: a terephthalic repeating unit and, where appropriate, an isophthalic repeating unit, the terephthalic repeating unit (“T unit”) having the formula:

[0070] The mass proportion of T units relative to the sum of the T and I units can vary from 0% to 100%. The choice of the molar proportion of T units relative to the sum of the T and I units is one of the factors which makes it possible to adjust the melting temperature as well as the crystallization rate properties of the polyether-ketone-ketones. A given molar proportion of T units relative to the sum of the T and I units can be obtained by adjusting the respective concentrations of the reactants during the polymerization, in a manner known per se. Preferably, the molar percentage of terephthalic units relative to the sum of the terephthalic and isophthalic units is less than or equal to 74%, preferably from 0% to 5% or from 45% to 73%, and more preferably from 58% to 72%.

[0071] Preferably, the polyether-ketone-ketone has a homogeneous structure, and can in particular be of the statistical type.

[0072] Polyether-ketone-ketones having a mass proportion of T units relative to the sum of T and I units less than or equal to 74% have a melting temperature less than or equal to 340°C.

[0073] Preferably, a polyetherketoneketone having a melting temperature of less than or equal to 340°C is chosen from polyetherketoneketones having a mass proportion of T units relative to the sum of the T and I units of 0% to 5% or 45% to 73%. The mass proportion of T units relative to the sum of the T and I units may in particular be 0% to 5%, or 45% to 50%, or 50% to 55%, or 55% to 58%, or 58% to 62%, or 62% to 68%, or 68% to 72%.

[0074] More preferably, a polyetherketoneketone having a melting temperature of less than or equal to 340°C is chosen from polyetherketoneketones having a mass proportion of T units relative to the sum of T and I units of 58% to 72%.

[0075] The molar proportion of T units relative to the sum of the T and I units may in particular be approximately 60% or approximately 70%. A polyether-ketone-ketone having a T:I ratio of approximately 60% is a pseudo-amorphous polymer within the meaning of the present application. A polyether-ketone-ketone having a ratio of approximately 70% is a semi-crystalline polymer. Such polyether-ketone-ketones are commercially available under the name Kepstan® from the company Arkema.

[0076] According to certain embodiments, the PAEK having a melting temperature less than or equal to 340°C may be a PEEK-PEDEK copolymer essentially consisting of, or even consisting of, a repeating unit having the formula:

[0077] [Chem 3] and a repeating unit having the formula: [Chem 4]

[0078] Copolymers consisting of repeating units of formula (III) and (IV) having a molar proportion of units (III) relative to the sum of units (III) and (IV) ranging from 5% to 45% have a melting temperature less than or equal to 340°C.

[0079] According to certain embodiments, the PAEK having a melting temperature of less than or equal to 340°C may be a copolymer essentially consisting of, or even consisting of, a repeating unit having the formula (III) and a repeating unit having the formula:

[0080] [Chem 5]

[0081] Copolymers consisting of repeating units of formula (III) and (V) having a molar proportion of units (III) relative to the sum of units (III) and (V) ranging from 5% to 100% have a melting temperature less than or equal to 340°C.

[0082] According to certain embodiments, the PAEK having a melting temperature of less than or equal to 340°C may be a copolymer essentially consisting of, or even consisting of, a repeating unit having formula (III) and a repeating unit having

[0083] Copolymers consisting of repeating units of formula (III) and (VI) having a molar proportion of (III) units relative to the sum of (III) and (VI) units ranging from 5% to 100% have a melting temperature less than or equal to 340°C.

[0084] According to certain embodiments, the PAEK having a melting temperature of less than or equal to 340°C has in particular a melting temperature of less than or equal to 335°C, or a melting temperature of less than or equal to 330°C, or a melting temperature of less than or equal to 325°C, or a melting temperature of less than or equal to 320°C. This has the advantage of limiting the thermal degradation of the poly(etherimide-siloxane) copolymer when the mixture M is melted during its extrusion to form the internal polymeric sealing sheath at a maximum temperature of 5°C to 40°C above the melting temperature of the PAEK having a melting temperature of less than or equal to 340°C, including for extended residence times in the melt.

[0085] In some embodiments, the PAEK has a melting temperature greater than 275°C, or greater than or equal to 285°C, or greater than or equal to 295°C. This has the advantage that the inner polymeric sealing sheath has sufficient heat resistance properties. In some embodiments, the non-delaminating blend M of polymers comprises two polyaryletherketones having a melting temperature less than or equal to 340°C. The blend M comprises a first polyaryletherketone P1 being a semi-crystalline polymer having a melting temperature T1, and a second polyaryletherketone P2 being either a semi-crystalline polymer having a melting temperature such that T2 <TI, soit un polymère pseudo-amorphe.

[0086] According to certain embodiments, the polymer P1 may represent at least 50% by weight of the polyaryletherketones having a melting temperature less than or equal to 340°C.

[0087] According to other embodiments, the polymer P2 may represent at least 50% by weight of the polyaryletherketones having a melting temperature less than or equal to 340°C.

[0088] According to certain embodiments, P2 is a poly-ether-ketone-ketone essentially consisting of, and preferably consisting of: a terephthalic unit and an isophthalic unit, the molar percentage of terephthalic units relative to the sum of the terephthalic and isophthalic units being from 0% to 5% or from 45% to 67%, and, P1 is a poly-ether-ketone-ketone essentially consisting of, and preferably consisting of: a terephthalic unit and an isophthalic unit, the molar percentage of terephthalic units relative to the sum of the terephthalic and isophthalic units being from 63% to 73%.

[0089] According to certain embodiments, P2 is a poly-ether-ketone-ketone essentially consisting of, and preferably consisting of: a terephthalic unit and an isophthalic unit, the molar percentage of terephthalic units relative to the sum of the terephthalic and isophthalic units being from 58% to 67%, and P1 is a poly-ether-ketone-ketone essentially consisting of, and preferably consisting of: a terephthalic unit and an isophthalic unit, the molar percentage of terephthalic units relative to the sum of the terephthalic and isophthalic units being from 63% to 73%. Advantageously, P2 represents at least 50% by weight of the polyaryletherketones having a melting temperature of less than or equal to 340°C.

[0090] In the embodiments where the mixture M further comprises a polyaryletherketone having a melting temperature strictly greater than 340°C, the latter may be a PEEK homopolymer consisting of the repeating unit (III); a PEEK-PEDEK copolymer, essentially consisting of, or consisting of, the repeating units of formula (III) and of formula (IV), the molar proportion of units of formula (III) relative to the total number of moles of units (III) and (IV) being strictly greater than 45%, in particular greater than or equal to 50%; or a PEKK, essentially consisting of, or consisting of, terephthalic (T) and isophthalic (I) repeating units, the molar proportion of terephthalic repeating units relative to the total number of moles of terephthalic and isophthalic repeating units being strictly greater than 74%, in particular greater than or equal to 75%, or greater than or equal to 76%, or greater than or equal to 77%, or greater than or equal to 78%.

[0091] According to certain embodiments, the mixture M comprises two polyaryletherketones P3 and P4, P3 being a semi-crystalline or pseudoamorphous polyaryletherketone having a melting temperature less than or equal to 340°C, preferably less than or equal to 320°C, and P4 being a polyaryletherketone having a melting temperature strictly greater than 340°C. The polymer P4 may in particular represent 25% by weight or less, 20% by weight or less, 15% by weight or less, or even 10% by weight or less by weight relative to the total weight of mixture M.According to particular embodiments, the polymer P3 may be a poly-ether-ketone-ketone essentially consisting of, and preferably consisting of: a terephthalic unit and an isophthalic unit, the molar percentage of terephthalic units relative to the total number of moles of terephthalic and isophthalic units of the poly-ether-ether-ketone being from 0% to 5% or from 45% to 67%, and, the polymer P4 may be a poly-ether-ketone-ketone essentially consisting of, and preferably consisting of: a terephthalic unit and an isophthalic unit, the molar percentage of terephthalic units relative to the total number of moles of terephthalic and isophthalic units of the poly-ether-ketone-ketone being from 78% to 85%.

[0092] According to certain embodiments, the mixture M comprises a poly-ether-ketone-ketone having a mass proportion of T units relative to the sum of the T and I units of 78% to 85%. The molar proportion of T units relative to the sum of the T and I units may in particular be approximately 80%. Such a poly-ether-ketone-ketone is commercially available under the name Kepstan® from the company Arkema.

[0093] According to certain embodiments, the mixture M comprises a poly-ether-ketone-ketone essentially consisting of, and preferably consisting of: a terephthalic unit and an isophthalic unit, the molar percentage of terephthalic units relative to the total number of moles of terephthalic and isophthalic units of the poly-ether-ether-ketone being from 0% to 5% or from 45% to 67%, and, a poly-ether-ketone-ketone essentially consisting of, and preferably consisting of: a terephthalic unit and an isophthalic unit, the molar percentage of terephthalic units relative to the total number of moles of terephthalic and isophthalic units of the poly-ether-ketone-ketone being from 78% to 85%. Advantageously, the mixture M comprises 25% by weight or less, 20% by weight or less, 15% by weight or less, or 10% by weight or less of said polyether-ketone-ketone having a molar ratio T / (T+I) of 78% to 85%, relative to the total weight of mixture M.

[0094] Poly(etherimide-siloxane) copolymer

[0095] The poly(etherimide-siloxane) copolymer makes it possible in particular to improve the toughness, flexibility, elongation at break and resistance to crack propagation of composition C.

[0096] The polymer blend M comprises from 5% to 40% by weight of a poly(etherimide-siloxane) copolymer, relative to the total weight of the blend M.

[0097] Preferably, the mixture M comprises less than 30%, and even more preferably less than 25% by weight of the poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture.

[0098] According to certain embodiments, the mixture M may comprise less than 20% by weight, or less than 17.5% by weight, or less than 15% by weight of the poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M.

[0099] Preferably, the mixture M comprises more than 7.5% by weight of the poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture. The mixture M may in particular comprise more than 8.0% by weight of the poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M.

[0100] According to certain embodiments, the mixture M comprises from 5% to 8% by weight of the poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M.

[0101] According to certain embodiments, the mixture M comprises from 8% to 15% by weight of the poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M.

[0102] According to certain embodiments, the mixture M comprises from 15% to 25% by weight of the poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M.

[0103] Poly(etherimide-siloxane) copolymers comprise polyetherimide units and polysiloxane units, for example 5 to 1000, or 10 to 500 etherimide units and siloxane units.

[0104] Polyetherimide units include structural units of formula (VII): [Chem 7]

[0105] wherein each R is the same or different and represents a substituted or unsubstituted divalent organic group, such as a C6-20 aromatic hydrocarbon group or a halogenated derivative thereof, a straight or branched chain C2-20 alkylene group or a halogenated derivative thereof, a C3-8 cycloalkylene group or a halogenated derivative thereof, in particular a divalent group of formula (VIII):

[0106] [Chem 8] in which Q 1 represents — O — , — S — , — C(O) — , — SO2 — , — SO — , — C yH2y — , where y represents an integer from 1 to 5 or a halogenated derivative thereof (which includes perfluoroalkylene groups) or — (C6HI0) Z — , where z represents an integer from 1 to 4. In one embodiment, R is m-phenylene, p-phenylene or diaryl sulfone.

[0107] Further, in formula (VI), T represents — O — or a group of formula — O — Z — O — , where the divalent bonds of the — O — group or the — O — Z — O — group are in the 3,3', 3,4', 4,3' or 4,4' positions. The Z group of — O — Z — O — may be a substituted or unsubstituted divalent organic group and may be a C6-24 aromatic monocyclic or polycyclic moiety optionally substituted with 1 to 6 C1-8 alkyl groups, 1 to 8 halogen atoms or a combination thereof, provided that the valence of Z is not exceeded. Examples of Z groups include groups derived from a dihydroxy compound of formula (IX): [Chem 9] in which Ra and R b may be the same or different and represent, for example, a halogen atom or a monovalent C1-6 alkyl group; p and q each independently represent integers from 0 to 4; c represents 0 to 4; and X arepresents a bridging group connecting the hydroxy-substituted aromatic groups, the bridging group and the hydroxy substituent of each C6 arylene group being arranged in the ortho, meta or para (more precisely para) position to each other on the C6 arylene group. The bridging group Xa may represent a single bond, — O — , — S — , — S(O) — , — S(O)2 — , — C(O) — or a C1-18 organic bridging group. The C1-18 organic bridging group may be cyclic or acyclic, aromatic or non-aromatic, and may further comprise heteroatoms such as halogens, oxygen, nitrogen, sulfur, silicon or phosphorus. The C1-18 organic group may be arranged so that the C6 arylene groups attached thereto are each attached to a common alkylidene carbon or to different carbons of the C1-18 organic bridging group.

[0108] A particular example of a Z group is a divalent group of formula (X): [Chem 10] in which Q represents — O — , — S — , — C(O) — , — SO2 — , — SO — or — C y H2y — , where y represents an integer from 1 to 5 or a halogenated derivative thereof (including a perfluoroalkylene group). In a particular embodiment, Z represents a derivative of bisphenol A, such that Q, in formula (X), is 2,2-isopropylidene.

[0109] In one embodiment in formula (VII), R represents m-phenylene or p-phenylene and T represents — O — Z — O — , where Z represents a divalent group of formula (X). Alternately, R represents m-phenylene or p-phenylene and T represents — O — Z — O — , where Z represents a divalent group of formula (X) and Q represents 2,2-isopropylidene. The polyetherimide blocks may be prepared by any of the methods well known to those skilled in the art, including the reaction of an aromatic bis(ether anhydride) of formula (XI):

[0110] [Chem 11] with an organic diamine of formula (XII):

[0111] H2N— R— NH2(XII) in which T and R are defined as described above. Copolymers of polyetherimides may be made by using a combination of an aromatic bis(ether anhydride) of formula (XI) and a different bis(anhydride), e.g., a bis(anhydride), where T does not contain ether functionality, and e.g., T represents a sulfone.

[0112] Illustrative examples of bis(anhydrides) include 3,3-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl ether dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)benzophenone dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfone dianhydride; 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)diphenyl ether dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)diphenyl sulfide dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)benzophenone dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)diphenylsulfone dianhydride; 4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)diphenyl-2,2-propane dianhydride; 4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)diphenyl ether dianhydride; 4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)diphenyl; 4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)benzophenone dianhydride; and 4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)diphenylsulfone dianhydride, as well as various combinations thereof. Examples of organic diamines include ethylenediamine, propylenediamine, trimethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, 1,12-dodecanediamine, 1,18-octadecanediamine, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 4-methylnonamethylenediamine, 5-methylnonamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 2,2-dimethylpropylenediamine, N-methyl-bis(3-aminopropyl)amine, 3-methoxyhexamethylenediamine, 1,2-bis(3-aminopropoxy)ethane, bis(3-aminopropyl) sulfide, 1,4-cyclohexanediamine, bis-(4-aminocyclohexyl)methane, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, m-xylylenediamine, p-xylylenediamine, 2-methyl-4,6-diethyl-1,3-phenylenediamine, 5-methyl-4,6-diethyl-1,3-phenylenediamine, benzidine, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 1,5-diaminonaphthalene, bis-(4-aminophenyl)methane, bis(2-chloro-4-amino-3,5-diethylphenyl)methane, bis(4-aminophenyl)propane, 2,4-bis(p-amino-t-butyl)toluene, bis(p-amino-t-butylphenyl)ether, bis(p-methyl-o-aminophenyl)benzene, bis(p-methyl-o-aminopentyl)benzene, 1,3-diamino-4-isopropylbenzene, bis(4-aminophenyl)sulfide, bis-(4-aminophenyl)sulfone, and bis(4-aminophenyl)ether. Combinations of these compounds may also be used. In some embodiments, the organic diamine is m-phenylenediamine, p-phenylenediamine,sulfonyldian iline or a combination comprising one or more thereof.,

[0113] The siloxane blocks contain units of the following formula (XIII): [Chem 12] wherein each R' independently represents a monovalent C1-13 hydrocarbyl group and E is an integer from 1 to 100, including 2 to 50. For example, each R' may independently represent a C1-13 alkyl group, a C1-13 alkoxy group, a C2-13 alkenyl group, a C2-13 alkenyloxy group, a C3-6 cycloalkyl group, a C3-6 cycloalkoxy group, a C6-14 aryl group, a C6-10 aryloxy group, a C7-13 arylalkyl group, a C7-13 arylalkoxy group, a C7-13 alkylaryl group, or a C7-13 alkylaryloxy group. The above groups may be wholly or partially halogenated with fluorine, chlorine, bromine, or iodine, or a combination comprising at least one of these. In one embodiment, no bromine or chlorine is present, and in other embodiments, no halogen is present. Combinations of the above R' groups may be used in the same copolymer.In one embodiment, the polysiloxane blocks comprise R' groups that have a minimal content of hydrocarbon radicals. In a particular embodiment, an R' group having a minimal content of hydrocarbon compounds is a methyl group.

[0114] Poly(etherimide-siloxanes) can be formed by polymerization of an aromatic bisanhydride (XI) and a diamine component comprising an organic diamine (XII) as described above or a mixture of diamines, and a polysiloxanediamine of the following formula (XIV): [Chem 13] wherein R' and E are as described in formula (XIII), and each R 4 independently represents a C2-C20 hydrocarbon moiety, in particular a C2-C20 arylene, an alkylene or an arylenealkylene group. In some embodiments, R 4represents a C2-C20 alkylene group, more specifically a C2-C10 alkylene group such as propylene, and E has an average value of 5 to 100, 5 to 75, 5 to 60, 5 to 15 or 15 to 40. Procedures for preparing the polysiloxane diamines of formula (XIV) are well known in the art.

[0115] In certain poly(etherimide-siloxane) copolymers, the diamine component used for preparing the copolymers may contain 10 to 90 mole percent (mol-%) or 20 to 50 mol-% or 25 to 40 mol-% of a polysiloxane diamine (XIV) and 10 to 90 mol-% or 50 to 80 mol-% or 60 to 75 mol-% of the diamine (XII), for example as described in U.S. Pat. No. 4,404,350. The diamine components may be physically mixed prior to reaction with one or more bisanhydrides, thereby forming a substantially random copolymer. Alternatively, block or alternating copolymers may be formed by selectively reacting (XII) and (XIV) with aromatic bis(ether anhydrides) (XI), to make polyimide blocks which are then reacted together. Thus, the poly(etherimide-siloxane) copolymer can be a block, random or graft copolymer.Poly(etherimide-siloxane) block copolymers comprise etherimide blocks and siloxane blocks in their polymer backbone. The etherimide blocks and siloxane blocks may be present in a random order, as blocks (i.e., AABB), alternating (i.e., ABAB), or in a combination thereof. Poly(etherimide-siloxane) graft copolymers are non-linear copolymers comprising the siloxane blocks connected to a linear or branched polymer backbone comprising etherimide blocks.

[0116] Examples of particular poly(etherimide-siloxanes) are described in U.S. Patent Nos. 4,404,350, 4,808,686 and 4,690,997.

[0117] According to preferred embodiments, the poly(etherimide-siloxane) consists essentially of, or consists of, units of formula (XV):

[0118] [Chem 14]

[0119] (XV) in which R' and E of the siloxane are as in formula (XIII), R and Z of the imide are as in formula (VII), R 4 is the same as R 4 as in formula (XIV), and n is an integer from 5 to 100. In a particular embodiment, R represents a phenylene, Z represents a residue of bisphenol A, R 4 represents n-propylene, E represents an integer from 2 to 50, or 5 to 20, or 6 to 15, n represents 5 to 100 and each R' of the siloxane is a methyl.

[0120] The relative amount of polysiloxane units and etherimide units in the poly(etherimide-siloxane) depends on the desired properties and is selected using the guidelines given in the present invention. In particular, the poly(etherimide-siloxane) copolymer is selected to have a certain average E value and is selected and used in an amount sufficient to provide the desired weight percentage (wt%) of siloxane units in the thermoplastic composition. In some embodiments, the polysiloxane block of the copolymer has a number average molecular weight (Mn) of 300 to 3,000 grams / mole (Daltons). In some embodiments, the siloxane groups of the poly(etherimide-siloxane) copolymer comprise more than 30% by weight, based on the total weight of the poly(etherimide-siloxane) copolymer.

[0121] According to certain embodiments, the siloxane groups of the poly(etherimide-siloxane) copolymer represent more than 35% by weight, relative to the total weight of the poly(etherimide-siloxane) copolymer.

[0122] According to certain embodiments, the siloxane groups of the poly(etherimide-siloxane) copolymer represent less than 50% by weight, relative to the total weight of the poly(etherimide-siloxane) copolymer.

[0123] According to certain embodiments, the siloxane groups of the poly(etherimide-siloxane) copolymer represent less than 45% by weight, relative to the total weight of the poly(etherimide-siloxane) copolymer.

[0124] Polysiloxane / polyetherimide copolymers are commercially available under the name SILTEM® from Sabic.

[0125] Other thermoplastic polymer

[0126] According to certain embodiments, the mixture M may comprise from 0% to 40% by weight of a thermoplastic polymer other than the polyaryletherketone having a melting temperature less than or equal to 340°C and the poly(etherimide-siloxane) copolymer, relative to the total weight of mixture M.

[0127] According to certain embodiments, the mixture M does not comprise, and preferably the composition C does not comprise, any other thermoplastic polymer than the polyaryletherketone having a melting temperature less than or equal to 340°C and the poly(etherimide-siloxane) copolymer.

[0128] Other thermoplastic polymers that may include polyaryletherketone with a melting temperature strictly above 340°C, polysiloxane, fluoropolymer, polyetherimide (PEI), polyphenylene sulfone (PPSU), polysulfone (PSU), polycarbonate (PC), polyphenylene ether (PPE), poly(phenylene sulfide) (PPS), poly(ethylene terephthalate) (PET), polyamide (PA), polybenzimidizole (PBI), poly(amide-imide) (PAI), poly(ether sulfone) (PES), poly(aryl sulfone), poly(ether imide sulfone), polyphenylene, polybenzoxazole, polybenzothiazole, or a mixture thereof.

[0129] According to certain embodiments, the other thermoplastic polymer may in particular be a polyaryletherketone having a melting temperature strictly greater than 340°C, as described above.

[0130] According to certain embodiments, the other thermoplastic polymer may in particular be a polysiloxane. The polysiloxane may be mono- or di-substituted by C1 to C12, preferably C1 to C6, and most particularly C1 to C4, alkyl groups and / or phenyl groups. Preferably, the alkyl groups are methyl groups. The alkyl or phenyl groups of the polysiloxane may be substituted by one or more functional groups such as epoxy, alkoxy, in particular methoxy, amine, ketone, thioether, halogen, nitrile, nitro, sulfone, phosphoryl, imino or thioester. These functional groups may also be located at the end of the polysiloxane chain. Such functionalized polysiloxanes may be used for their reaction during mixing (reactive siloxanes).

[0131] Preferably, however, the polysiloxane does not have functional groups. Furthermore, the alkyl or phenyl groups of the polysiloxane may be substituted with one or more carbocyclic, aryl, heteroaryl, alkyl, alkenyl, bicyclic or tricyclic groups.

[0132] Preferably, the polysiloxane present in the mixture M as another thermoplastic polymer is a poly(dimethylsiloxane) (PDMS). In order to facilitate handling, the polysiloxane can be combined with a solid support such as a silica, in particular fumed silica.

[0133] According to certain embodiments, the mixture M comprises from 0.1% to 3%, and preferably from 0.5% to 2% by weight of polysiloxane as other thermoplastic polymer relative to the total weight of mixture M.

[0134] According to certain embodiments, the mixture M comprises less than 1% by weight of polysiloxane relative to the total weight of mixture M.

[0135] Preferably, when the mixture M comprises from 5% to 7.5% by weight of a poly(etherimide-siloxane) copolymer, then the mixture M (and preferably the composition C) does not comprise polysiloxane.

[0136] According to certain embodiments, the mixture M does not comprise, and preferably the composition C does not comprise, polysiloxane.

[0137] Preferably, composition C does not comprise any other thermoplastic polymer, or more generally, composition C does not comprise any other polymer than those present in mixture C.

[0138] Additives

[0139] Composition C may comprise from 0% to 40% by weight of one or more additives, preferably non-polymeric, relative to the total weight of composition C.

[0140] Advantageously, composition C comprises from 0% to 30%, or from 0% to 25%, or from 1% to 20%, or from 2% to 10% by weight of additives, relative to the total weight of composition C. Among the additives, one or more fillers may be mentioned. Among the possible fillers, mention may be made in particular of silica and alumina, nucleating fillers such as mineral fillers, in particular talc, carbon fillers, in particular carbon nanotubes or carbon blacks, ceramic fillers, in particular boron nitride (NB), or metal oxides, in particular ZnO or MgO, or reinforcing fillers such as glass fibers or carbon fibers. The crystallization kinetics of mixture M generally makes it possible to achieve the level of crystallization required to provide good resistance to CO2 permeation over the entire thickness of the sheath. Composition C may include additives capable of modifying (slowing down or accelerating) its crystallization kinetics.These additives can thus facilitate obtaining the desired level of crystallization. Thus, according to particular embodiments, composition C can comprise from 0.1% to 5%, in particular from 0.25% to 2.5%, by weight of a nucleating charge relative to the total weight of composition C. This makes it possible to modify the crystallization behavior of the polyaryletherketone(s), and in particular makes it possible to increase the final crystallinity in usual processes for forming polyaryletherketones that are slower to crystallize without significantly modifying the processing conditions. These polyaryletherketones that are slower to crystallize can in particular achieve sufficient crystallinity without, for example, having to consider an additional annealing step.

[0141] According to certain embodiments, the polyaryletherketone of composition C may be a poly-ether-ketone-ketone having a mass proportion of T units relative to the sum of the T and I units of less than or equal to 74%, and preferably from 0% to 5% or from 45% to 67%, and the nucleating charge may be a carbon charge. The polyaryletherketone of composition C may for example be a poly-ether-ketone-ketone having a mass proportion of T units relative to the sum of the T and I units ranging from 55% to 65%, in particular approximately 60%, and the carbon charge may be carbon nanotubes.

[0142] Furthermore, composition C may optionally comprise minor quantities, in particular less than 1% by weight relative to the total weight of composition C, of ​​functional additives. Examples that may be mentioned as such are antistatic agents, antioxidant agents, anti-UV agents, molten stabilizers, conductive agents, flame retardants, colorants and reactive agents such as alkali carbonates.

[0143] Among the additives, one or more plasticizers can be mentioned, which can improve the cold performance of the sheath (by lowering the glass transition temperature by 10°C, or even 25°C, measurable by DSC). The plasticizer can, for example, be chosen from the compounds defined in the Handbook of Plasticizers published by Georges Wypych.

[0144] Advantageously, composition C comprises between 0% and 20% by weight of plasticizer and preferably between 1% and 10% by weight of plasticizer relative to the total weight of composition C.

[0145] Composition C

[0146] Composition C comprises a non-delaminating mixture M of polymers, said mixture M comprising: at least 50% by weight of at least one polyaryletherketone, pseudo-amorphous or semi-crystalline, said polyaryletherketone having a melting temperature of less than or equal to 340°C, relative to the total weight of the mixture; and, from 5% to 40% by weight of a poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture.

[0147] According to certain embodiments, the mixture M consists of said at least one polyaryletherketone having a melting temperature of less than or equal to 340°C, said poly(etherimide-siloxane) copolymer, and from 0% to 40% by weight of another thermoplastic polymer than said polyaryletherketone and said poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M. Preferably, the composition C then does not comprise any other thermoplastic polymer, or even any other polymer, than those of the mixture M.

[0148] According to certain embodiments, the mixture M consists of said at least one polyaryletherketone and said poly(etherimide-siloxane) copolymer. Preferably, the composition C then does not comprise any other thermoplastic polymer, or even any other polymer, than those of the mixture M.

[0149] Mixture M may constitute at least 60% by weight, or at least 70% by weight, or at least 75% by weight, or at least 80% by weight, or at least 85% by weight, or at least 90% by weight, relative to the total weight of composition C.

[0150] According to certain embodiments, composition C comprises at least 60% by weight, preferably at least 70% by weight of mixture M and from 0 to 40%, preferably from 0% to 30% by weight of one or more additives, relative to the total weight of composition C.

[0151] Typically, composition C consists of:

[0152] 60 to 100% by weight, preferably 70 to 100% by weight, of mixture M as defined above, and

[0153] 0 to 40% by weight, preferably from 0 to 30% by weight of additives, relative to the total weight of composition C. According to certain embodiments, composition C consists of mixture M and from 0% to 30% by weight of additives, relative to the total weight of composition C.

[0154] According to certain embodiments, composition C consists of mixture M and from 0% to 30% by weight of additives, including 0% to 20% by weight of plasticizer(s), 0% to 5% by weight of nucleating filler(s) and less than 1% by weight of functional additives, relative to the total weight of composition C. According to certain embodiments, composition C consists of mixture M, from 0.1% to 5% of nucleating filler(s) and less than 1% of functional additives, relative to the total weight of composition C.

[0155] Properties of composition C, and therefore of the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C

[0156] The layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C has a low permeation to gas and in particular to CO2. Typically, the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C has a CO2 permeation measured at 60°C of less than 1.1x10 -8 (cm 3 (STP).cm) / (cm 2 .s.bar).

[0157] The crystallinity levels of composition C allow this good resistance to CO2 permeation. Composition C can have different levels of crystallinity, notably controllable by the crystallization kinetics of composition C. The modification of the crystallization behavior can notably be controlled by the use of a mixture of polyaryletherketones within composition C and / or by the addition of an additive within composition C.

[0158] These crystallinity levels can be evaluated by DSC in first heating at 20°C / min by the calculation: AHd-AHcc. The term "AHcc" corresponds to the cold crystallization enthalpy and the term "AHd" corresponds to the fusion enthalpy in first heating at a heating rate of 20°C / min. These enthalpies are expressed in Joule per gram of composition.

[0159] The expression AH f i-AHcc may have a value generally ranging from 0 to 50 J / grams of composition C. It may in particular have a value of 0 to 5 J / g, or from 5 J / g to 10 J / g, or from 10 J / g to 15 J / g, or from 15 J / g to 20 J / g, or from 20 J / g to 25 J / g, or from 25 J / g to 30 J / g, or from 30 J / g to 35 J / g, or from 35 J / g to 40 J / g, or from 40 J / g to 45 J / g, or from 45 J / g to 50 J / g.

[0160] Composition C, and therefore the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C, generally appears as a heterophasic, but non-delaminating, composition. Indeed, most often, the poly(etherimide-siloxane) copolymer is poorly miscible in the poly(aryletherketone). A dispersed phase in the form of nodules in a continuous phase is then observed under electron microscopy. Preferably, the nodules have an average diameter of less than 20 μm, advantageously less than 10 μm and very particularly less than 5 μm.

[0161] Preferably, the poly(aryletherketone) forms the continuous phase (also called matrix) of composition C and the poly(etherimide-siloxane) copolymer forms the dispersed phase.

[0162] The poly(etherimide-siloxane) copolymer improves the toughness, flexibility, elongation at break and resistance to crack propagation of composition C, and therefore of the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C. These improved properties make it possible to extend the service life of the internal polymeric sealing sheath and the flexible pipe. The increase in the flexibility of the sheath and its elongation at break allow higher deformations and consequently facilitate the winding of the pipe on reels and / or in carousels during its storage and / or transport as well as during its installation at sea.

[0163] Preferably, the driving flexibility is such that it is capable of undergoing at least 1000 cycles, where for each cycle, the layer of the internal polymeric sealing sheath whose polymeric material is composition C undergoes a level of flexural deformation varying from -2% to +2%, without any degradation of the layer of composition C being observed.

[0164] Preferably, the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C has a tensile modulus of elasticity, as measured according to standard ISO 527-1 A:2019 at 20°C, of ​​less than 4.0 GPa, typically less than 3.5 GPa, in particular less than 3.2 GPa, preferably less than 3.0 GPa.

[0165] Preferably, the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C has a nominal strain at break as measured according to standard ISO 527-1 A:2019 at 20°C greater than 8%, typically greater than 10%, in particular greater than 15%, preferably greater than 20%.

[0166] Preferably, the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C has a Charpy impact strength according to standard ISO 179-1:2010 / 1 eA greater than 5 KJ / m 2 , preferably greater than 6 KJ / m 2 , preferably still greater than 7 KJ / m 2 , and more preferably greater than 8 KJ / m 2 .

[0167] Preferably, the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C has a stress at yield, as measured by ISO 527-1 A:2019 at 20°C, of ​​less than 85 MPa.

[0168] Preferably, the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C resists five blistering cycles in an 85% CH4- 15% CO2 mixture at 520 bars and 110°C after exposure to diesel at 100°C for 15 days and / or resists one blistering cycle in 100% CO2 at 680 bars and 110°C, the resistance to the blistering phenomenon being evaluated according to the standard document API 17J, 2014 edition published by the American Petroleum Institute.

[0169] Pipe structure and different layers

[0170] The internal polymeric sealing sheath of the flexible pipe is typically tubular, generally has a diameter of 50 mm to 600 mm, preferably 50 to 400 mm, and / or a thickness of 1 mm to 150 mm, in particular 4 to 15 mm, preferably 7 to 10 mm and / or a length of 1 m to 10 km.

[0171] Preferably, the layer of the internal polymeric sealing sheath whose polymeric material is composition C has a thickness greater than 3 mm, in particular greater than 4 mm, preferably greater than 5 mm, particularly preferably greater than 6 mm. By "thickness" is meant the average thickness over the entire layer. Generally, the thickness of the layer is the same to ±5%, typically to ±2%, at any location in the layer. This thickness can be measured with a caliper.

[0172] The inner polymeric sealing sheath is likely to be in contact with the hydrocarbons and / or gases being transported. By "inner polymeric sealing sheath likely to be in contact with hydrocarbons" is meant that the sheath comes into contact with hydrocarbons when the pipe is put into service. Thus, the pipe does not include an inner tubular layer (i.e., a hydrocarbon-tight layer) that would oppose contact between the hydrocarbons and the sheath or layer. Typically, the pipe does not include a polymeric tubular layer coated with the inner polymeric sealing sheath or a hydrocarbon-tight metal tube (a metal carcass is not such a metal tube, because it is not hydrocarbon-tight).

[0173] In one embodiment, the internal polymeric sealing sheath is the only polymeric layer inside the reinforcing layer (or the innermost reinforcing layer when there are several reinforcing layers). On the other hand, the pipe may comprise one or more additional polymeric layer(s) outside the reinforcing layer (or the innermost reinforcing layer when there are several reinforcing layers). In one embodiment, the internal polymeric sealing sheath is single-layer, which excludes multi-layer internal polymeric sealing sheaths, whether the layers are not bonded together or bonded together, in particular by an adhesive or because they have been formed by coextrusion. The polymeric material of the single-layer internal polymeric sealing sheath is then composition C defined above.The internal polymeric sealing sheath is then sheathed around the metal casing. A single layer rather than two or more prevents gas accumulation between the layers, and therefore damage due to blistering of the internal polymeric sealing sheath, for example in the event of sudden deliberate or involuntary depressurization of the subsea pipeline.

[0174] In another embodiment, the inner polymeric sealing sheath is multi-layered, typically bi-layered. It then comprises, in addition to the layer whose polymeric material is composition C, at least one other layer of polymeric material. The layer whose polymeric material is composition C is the innermost layer of the inner polymeric sealing sheath. For example, the inner polymeric sealing sheath may comprise (or be made up of) the layer whose polymeric material is composition C as the innermost layer, and at least one other layer of polymeric material, the composition of which is preferably distinct from that of the innermost layer.Preferably, the polymeric material of this at least one other layer is distinct from composition C, and is for example chosen from polyolefins, in particular high density or crosslinked polyethylene, polyamides, in particular PA 11, and fluoropolymers, in particular PVDF. For example, the internal polymeric sealing sheath is two-layer and consists of an external layer whose polymeric material is chosen from polyolefins, polyamides and fluoropolymers and an internal layer whose polymeric material is composition C defined above.

[0175] As the pipe has a metal casing, it is called rough-bore.

[0176] The main function of the metal casing is to absorb radial forces directed from the outside to the inside of the pipe in order to prevent the collapse of all or part of the pipe under the effect of these forces. These forces are notably linked to the hydrostatic pressure exerted by seawater when the flexible pipe is submerged. Thus, the hydrostatic pressure can reach a very high level when the pipe is submerged at great depth, for example 200 bar when the pipe is submerged at a depth of 2000 m, so that it is often essential to provide the flexible pipe with a metal casing. When the flexible pipe includes an external polymer sheath, the metal casing also has the function of preventing the collapse of the internal polymer sealing sheath during rapid decompression of a flexible pipe having transported hydrocarbons.Indeed, the gases contained in the hydrocarbons diffuse slowly through the internal polymeric sealing sheath and are partly trapped in the annular space between the internal polymeric sealing sheath and the external polymeric sheath. Consequently, during a production shutdown causing rapid decompression of the interior of the flexible pipe, the pressure prevailing in this annular space may temporarily become significantly higher than the pressure prevailing inside the pipe, which in the absence of a metal casing would lead to the collapse of the internal polymeric sealing sheath.

[0177] The metal carcass consists of longitudinal elements wound helically with a short pitch. These longitudinal elements are stainless steel strips or wires arranged in turns stapled to each other. Advantageously, the metal carcass is made by profiling a strip into an S shape and then winding it helically so as to staple the adjacent turns together.

[0178] The concept of short pitch winding refers to any helical winding with a helix angle close to 90°, typically between 75° and 90°.

[0179] Generally, the reinforcing layer (or each reinforcing layer when there are several) consists of a winding of at least one wire with non-contiguous turns. The wire is generally metallic or made of a composite material. Typically, the at least one reinforcing layer is at least one tensile armor ply or a pressure vault.

[0180] The pipe may comprise several layers of reinforcement, generally an even number of tensile armor plies, typically two tensile armor plies, or a pressure vault and two tensile armor plies.

[0181] Tensile armor plies are made up of wires wound in long pitches and their main function is to absorb axial forces linked on the one hand to the internal pressure prevailing inside the flexible pipe and on the other hand to the weight of the flexible pipe, particularly when it is suspended.

[0182] In the present application, the concept of long pitch winding covers any helical winding with a helix angle of less than 60°, typically between 20° and 60° for armor plies.

[0183] The presence of an additional reinforcing layer intended to absorb the radial forces linked to the internal pressure, a layer notably called a "pressure vault", is not essential since the helix angles of the wires constituting the tensile armor plies are close to 55°. Indeed, this particular helix angle gives the tensile armor plies the capacity to absorb, in addition to the axial forces, the radial forces exerted on the flexible pipe and directed from the inside to the outside of the pipe.

[0184] Preferably, and in particular for applications at great depth, in addition to the tensile armor layers, the flexible pipe comprises a pressure vault interposed between the internal sealing polymer sheath and the tensile armor layers. In such a case, the radial forces exerted on the flexible pipe, in particular the radial forces directed from the inside to the outside of the pipe, are absorbed by the pressure vault in order to prevent the internal polymer sheath from bursting under the effect of the pressure prevailing inside the pipe. The pressure vault is made up of longitudinal elements wound with a short pitch, for example metal wires or composite material of Z (zeta), C, T (theta), U, K or X shape arranged in turns stapled to each other.

[0185] Advantageously, and in particular depending on the grade of the metallic or composite material constituting the tensile armor plies and the possible pressure vault, the flexible pipe may comprise an external sealing polymer sheath to prevent seawater from penetrating into the flexible pipe. This makes it possible in particular to protect the tensile armor plies from seawater and therefore to prevent the phenomenon of corrosion by seawater.

[0186] Typically, the conduct includes, from outside to inside:

[0187] - possibly an external polymeric sealing sheath,

[0188] - at least one tensile armor ply as a reinforcing layer, generally an even number of tensile armor plies, typically two tensile armor plies,

[0189] - possibly a pressure vault,

[0190] - the internal polymeric sealing sheath comprising the layer of polymeric material as defined above and sheathed around a metal carcass.

[0191] The conduit may also include one or more additional polymeric layers between two adjacent layers.

[0192] For example, the pipe may include a retaining layer either between the outer polymer sheath and the tensile armor ply (the outermost tensile armor ply when there are several tensile armor plies), or between two adjacent tensile armor plies.

[0193] The pipe may also comprise one or more anti-wear layers made of polymeric material. The anti-wear layer may be in contact either with the inner face of the aforementioned retaining layer, or with its outer face, or with both faces, this anti-wear layer making it possible to prevent the retaining layer from wearing out upon contact with the armor. The anti-wear layer may also be between two adjacent reinforcement layers, for example between the pressure vault and the tensile armor ply (the innermost tensile armor ply when there are several tensile armor plies), or between two adjacent tensile armor plies.

[0194] Anti-wear layers are generally made by helical winding of one or more ribbons obtained by extrusion of a polymeric material based on polyamide, polyolefins, or PVDF ("polyvinylidene fluoride" in English). The ribbon can be made of polysulfone (PSU), polyethersulfone (PES), polyphenylsulfone (PPSU), polyetherimide (PEI), polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK) or polyphenylene sulfide (PPS), as for example described in application WO 2006 / 120320.

[0195] The nature, number, size and organization of the layers constituting flexible pipes are essentially linked to their conditions of use and installation. The pipes may include additional layers to those mentioned above.

[0196] In one embodiment, the flexible pipe is of the unbonded type, that is to say that its reinforcing layers, such as the tensile armor ply(ies) and / or the pressure vault, are unbonded to the adjacent polymeric layer(s), such as the inner sealing polymeric sheath and / or the outer sealing polymeric sheath and / or any tubular polymeric layer making up the flexible pipe. By "unbonded" is meant that the reinforcing layers are free to move relative to the polymeric layers. Typically, the reinforcing layers of the flexible pipe are not embedded in a polymeric or elastomeric sheath. Similarly, there is preferably no adhesive between the reinforcing layers and the adjacent polymeric layer(s).

[0197] In another embodiment, the flexible pipe is of the bonded type, that is to say that at least one of the reinforcing layers, often metallic or made of composite material, is bonded to an adjacent polymeric layer. If the reinforcing layer is interposed between two polymeric layers, only one or both faces of the reinforcing layer may be bonded to the adjacent polymeric layer(s). If there are several reinforcing layers, each may be bonded to an adjacent polymeric layer, by one face of the reinforcing layer, or by both faces when the reinforcing layer is interposed between two polymeric layers. For example, the internal polymeric sealing sheath, the layer of composition C of which is sheathed around the metal carcass, may be bonded to the reinforcing layer (to the innermost reinforcing layer when there are several reinforcing layers).This bond can be achieved by using an adhesive or elastomer between two adjacent layers, or by embedding at least one face of the reinforcing layer in the adjacent polymeric or elastomeric sheath.

[0198] Flexible pipes can be used at great depths, typically up to 3,000 meters. They allow the transport of fluids, particularly hydrocarbons, with a temperature typically reaching 130°C and even exceeding 150°C and an internal pressure of up to 1,000 bars, or even 1,500 bars.

[0199] According to a second subject, the invention relates to a method for preparing the underwater pipe defined above, comprising the following steps: a) extrusion to form the internal polymeric sealing sheath as defined above, the extrusion being carried out on the metal carcass, b) assembly of the internal polymeric sealing sheath obtained in step a) with the at least one reinforcing layer.

[0200] The use of a polyaryletherketone having a melting temperature of less than or equal to 340°C makes composition C particularly suitable for being formed by extrusion into an internal sealing polymer sheath. Indeed, composition C is stable in the molten state for at least 5 minutes. The crystallization kinetics of composition C advantageously make it possible to achieve the level of crystallization required to provide good resistance to CO2 permeation over the entire thickness of the sheath.

[0201] Extrusion step a) can be carried out by any method known to those skilled in the art, for example using a single-screw or twin-screw extruder, and preferably a crosshead extrusion extruder.

[0202] Mixing of the M mixture and other components it contains (additives, etc.) can be carried out before or during extrusion.

[0203] Preferably, the maximum temperature during extrusion does not exceed 350°C, or does not exceed 345°C, or does not exceed 340°C, or does not exceed 335°C. Generally, the maximum temperature during extrusion is set at 5°C to 40°C above the melting temperature of the polyaryletherketone having a melting temperature of less than or equal to 340°C.

[0204] According to certain embodiments, the maximum temperature during the extrusion process is set from 10°C to 30°C or from 15°C to 25°C above the melting temperature of the polyaryletherketone having a melting temperature less than or equal to 340°C. A sufficiently low maximum temperature makes it possible to extrude composition C in the form of a sheath even for long residence times at the maximum extrusion temperature or a temperature thereabout. This residence time within the extruder may in particular be of an average duration greater than 1 minute, or greater than 2 minutes, or greater than 3 minutes, or greater than 4 minutes, or greater than 5 minutes, or greater than 10 minutes, or greater than 20 minutes.

[0205] When the internal polymeric sealing sheath is multi-layered, it is preferably obtained by coextrusion.

[0206] The method comprises step b) of assembling the internal polymeric sealing sheath obtained during step a) with the reinforcing layer(s) to form the flexible underwater pipe.

[0207] The layers are thus assembled to form a flexible subsea pipe, for example of the unbonded type, as described in the normative documents published by the American Petroleum Institute (API), API 17J and API RP 17B.

[0208] According to a third object, the invention relates to an underwater pipe capable of being obtained by the aforementioned method.

[0209] According to a fourth object, the invention relates to the use of the aforementioned underwater pipe for the transport of hydrocarbons and / or gas.

[0210] The underwater pipeline according to the invention is suitable for the transport of gas, typically CO2, in particular with a view to its reinjection into the underwater deposit from which the hydrocarbons are extracted.

[0211] According to a fifth object, the invention relates to the use of a composition C as defined above, as a polymeric material of a layer of an internal polymeric sealing sheath, said layer being sheathed around a metal carcass of an underwater pipe intended for the transport of hydrocarbons and / or gas and comprising at least one layer of metal reinforcement around said internal polymeric sealing sheath, to improve the resistance to stress corrosion of said at least one layer of metal reinforcement. Stress corrosion can be evaluated by the NACE TM0177-2016-SG standard. The embodiments described above are of course applicable.

[0212] According to a sixth object, the invention relates to the use of a composition C as defined above as a polymeric material of a layer of an internal polymeric sealing sheath, said layer being sheathed around a metal carcass of an underwater pipe intended for the transport of hydrocarbons and / or gas and comprising at least one metal reinforcing layer around said internal polymeric sealing sheath, to improve the permeation resistance of said internal polymeric sealing sheath. The embodiments described above are of course applicable.

[0213] According to a seventh object, the invention relates to a method for extracting hydrocarbons comprising: extracting a mixture of hydrocarbons and CO2 from an underwater deposit, separating the hydrocarbons and the CO2, transporting at least part of the separated CO2 to said underwater deposit in the pipe as defined above, reinjecting the transported CO2 into said underwater deposit.

[0214] This process advantageously reduces CO2 emissions during extraction, and generally increases the quantity of hydrocarbons that can be extracted from the underwater deposit.

[0215] The embodiments described above are of course applicable.

[0216] Other features and advantages of the invention will emerge from reading the description given below of particular embodiments of the invention, given for informational purposes but not as a limitation, with reference to the figures.

[0217] [Fig. 1] Figure 1 is a partial schematic perspective view of a flexible pipe according to the invention. It illustrates a pipe according to the invention comprising, from the outside to the inside: an external polymeric sealing sheath 10, an external tensile armor ply 12, an internal tensile armor ply 14 wound in the opposite direction to the external ply 12, a pressure vault 18 for absorbing the radial forces generated by the pressure of the hydrocarbons or gases transported, an internal polymeric sealing sheath 20 sheathed around an internal carcass 22 for absorbing the radial crushing forces, in which the polymeric material of the internal polymeric sealing sheath 20 is composition C as defined above.

[0218] Due to the presence of the internal carcass 22, this pipe is said to have a rough bore.

[0219] The internal polymeric sealing sheath 20 is single-layer. Alternatively, it could be multi-layer (not shown). Similarly, it would not be outside the scope of the present invention to remove the pressure vault 18, but the helix angles of the wires constituting the armor plies 12, 14 would then preferably be close to 55° and in opposite directions.

[0220] The armor plies 12, 14 are obtained by long-pitch winding of a set of wires made of metallic or composite material, generally of substantially rectangular cross-section. The invention would also apply if these wires had a cross-section of circular or complex geometry, for example of the self-stapled T type. In Figure 1, only two armor plies 12 and 14 are shown, but the pipe could also include one or more additional pairs of armors. The armor ply 12 is called external because it is here the last, starting from the inside of the pipe, before the external sealing sheath 10.

[0221] [Fig. 2] Figure 2 represents the mass loss of a poly(etherimide-siloxane) copolymer sample (Siltem® STM 1500) obtained by thermogravimetric analysis (TGA) after heating under nitrogen at different temperatures for 1 hour.

[0222] EXAMPLES

[0223] Example 1: Preparation of extruded strips and evaluation of properties

[0224] Granules comprising a PAEK, a poly(etherimide-siloxane) copolymer, and optionally an additive, the composition of which is detailed in Table 1, were used to prepare extruded strips.

[0225] [Table 1] 1 : KEPSTAN® PEKK, 6000, 7000, 8000 series grades suitable for extrusion, marketed by Arkema. These polymers are PEKK copolymers with a T / l ratio of approximately 60 / 40 (pseudo-amorphous with a melting temperature of 303°C), 70 / 30 (semi-crystalline with a melting temperature of 331°C) and 80 / 20 (semi-crystalline with a melting temperature of 355°C) respectively.

[0226] 2 : PEEK 450G™, marketed by Victrex, suitable for extrusion (semi-crystalline with a melting temperature of 343°C).

[0227] 3: SILTEM® STM1500 poly(etherimide-dimethylsiloxane) (PEI-PDMS) copolymer, which is amorphous and has a glass transition temperature Tg of 168°C. It has a mass proportion of 40% polydimethylsiloxane relative to the total weight of the polymer. It is marketed by the company Sabic.

[0228] 4 : Carbon nanotubes (CNTs), GraphiStrength® C100, marketed by Arkema.

[0229] Table 1: Composition of granules used for extrusion

[0230] A Collin single-screw extruder, with a screw diameter of 30 mm and an L / D=25, was used. The extruder is connected to a flat die with a width of 50 mm and an air gap of 8 mm. At the die outlet, the melt is conveyed onto a 3-roll calendering system. The spacing between the rolls was adjusted just above the desired thickness to produce 7 mm thick strips. The strips were then cut to the desired length using a guillotine at the end of the line.

[0231] The extruder temperature conditions were as follows:

[0232] To manufacture the strips of composition 2, 3 and 4, a temperature profile with rising temperatures up to the last zone and die at 320°C was used.

[0233] To manufacture the composition 5 strip, a bell-shaped temperature profile was used to achieve a homogeneous material and stable extrusion, with a maximum set temperature of 335°C and a final zone and die at 325°C.

[0234] To manufacture the 1c composition strip, a bell-shaped temperature profile was used to have a sufficiently homogeneous material and a sufficiently stable extrusion, with a maximum set temperature of 370°C and a final zone and die at 350°C.

[0235] To manufacture the 6c composition strip, a bell-shaped temperature profile was used to ensure a sufficiently homogeneous material and a sufficiently stable extrusion, with a maximum set point temperature of 350°C and a die at 330°C. For all strips, the screw speed was set at 30 rpm and an overall line speed of approximately 0.2 m / min. The residence time of the material in the extruder to form 7mm thick strips is estimated to have been approximately 3-4 minutes.

[0236] Appearance of the extruded bands The band of composition 1 c is delaminated (sheets visible on the section) and has numerous porosities (numerous bubbles visible on the surface or on the section).

[0237] Unlike the composition band 1c, the composition bands 2-5; 6c do not show any delamination visible to the naked eye (smooth appearance on the section) and do not show any porosities (no bubbles visible on the surface or on the section).

[0238] Preparation of type 1A specimens and type 1 bars, type A notch

[0239] To carry out mechanical tests, type 1 A specimens and type 1 A bars were manufactured subtractively by machining / milling, retaining only the core of the strips.

[0240] Due to the heterogeneous and delaminated nature of the composition 1c strip, it was not possible to produce correct specimens / bars. It could therefore not be mechanically tested.

[0241] The dimensions and shape of type 1 A test pieces are described in ISO 527-2:2012 (section 11 and Table 1 page 5). These test pieces are hereinafter referred to as “ISO 527-2 / 1 A test pieces”.

[0242] Type 1 bars have a dimension of 80.0x10.0x4.0 mm 3 , as described in ISO 179-1:2010 (section 6.3, Table 1). A “V” notch (type A notch) with a notch tip radius of 0.25 + / - 0.05 mm. These bars are hereinafter referred to as “ISO 179-1 / 1 eA bars”.

[0243] The specimens and notched bars were then left to stand for 24 hours at 23°C and 50% relative humidity.

[0244] Mechanical characterizations

[0245] ISO 527-2 / 1 A specimens were used to determine the modulus of elasticity and nominal strain at break at 23°C and 50% RH of compositions 2-5 and 6c according to ISO 527-1:2019.

[0246] For the determination of the modulus of elasticity, a crosshead speed equal to 1 mm / min was used.

[0247] For the determination of the nominal strain at break, a crosshead speed equal to 50 mm / min was used.

[0248] ISO 179-1 / 1 eA bars were used to determine the Charpy impact strength of compositions 2-5 and 6c according to ISO 179-1:2010.

[0249] Crystallinity characterization

[0250] The crystallinity of the samples was evaluated by DSC in first heating at 20°C / min by the calculation: AH f i-AHcc.

[0251] The results of the different characterizations are grouped in Table 2 below. [Table 2]

[0252] These examples demonstrate the benefit of using different compositions of PAEK having a melting temperature less than or equal to 340°C and poly(etherimide-siloxane) copolymer, allowing the shaping by extrusion of a sheath:

[0253] - non-delaminated and homogeneous, even in the case of relatively long residence times at the extrusion temperature;

[0254] - ductile, i.e. having a relatively low elastic modulus, a high nominal strain at break, and a high Charpy notched impact strength;

[0255] - can be of high thickness without losing the aforementioned advantageous properties.

[0256] The modification of crystallization behavior brought about by i) the mixture of polyaryletherketones and / or ii) the addition of an additive, leads to sheaths that can have good crystallinity while maintaining good ductility and flexibility. These levels of crystallization allow in particular better chemical resistance and high barrier properties.

[0257] Example 2: Preparation of a sheath by extrusion and evaluation of the properties

[0258] Three types of granules with composition 4, 5 or 7c from Table 1 above were dried in a drying apparatus (Piovan) with a dew point of -40°C for 48h at 180°C. The moisture level was checked after drying with a moisture meter (Aquatrac) and was less than 50 ppm.

[0259] The pellets were then introduced at a temperature of 100°C into a single-screw extruder (manufactured by Maillefer - 45mm diameter equipped with a three-zone screw), with a temperature profile as described in example 1.

[0260] The residence time of the polymer composition in the molten state depends directly on the speed of the extruder screw and can be calculated. Several screw speeds were used and a significant impact of this speed (and therefore of the residence time in the molten state) on the surface appearance of the sheath produced was observed.

[0261] Table 3 shows that depending on the composition used, the temperature of the extrudate obtained was different. Composition 4, which is the one with the lowest melting temperature, had a much better surface appearance, which is explained by the fact that the poly(etherimide-siloxane) copolymer was not degraded during extrusion.

[0262] [Table 3]

[0263] Table 3: Surface appearance of the sheath as a function of the extruder screw speed

[0264] A 7mm thick pressure sheath could be extruded onto a metal carcass, demonstrating the possibility of extruding a thick layer.

[0265] Microscopic observations of the sheaths

[0266] Microscopic observations were made on the sheaths produced from compositions 4, 5, and 7c. Thin lamellae of 15 μm were obtained with microtome sectioning (Leica 2065) and observed under a digital microscope (Keyence VHX 700F). The area of ​​the weld line where the residence time of the polymer composition in the molten state is known to be the longest was studied.

[0267] Composition 5 showed a marked weld line without debonding but probably with some microstructural singularities and potentially slight degradation. Composition 4, on the contrary, shows almost no singularities in this area. Composition 7c shows clear signs of degradation around the entire circumference of the cladding with bubbles in the first 0.2 mm below the outer surface of the cladding, and in addition, bubbles localized at the weld line, indicating degradation related to residence time.

[0268] Mechanical properties

[0269] Tensile specimens were prepared and tested in tension at room temperature according to ISO 527-1 A from the extruded sheath.

[0270] All compositions used show higher compliance compared to an unformulated polyetherketoneketone (used as a single component). The nominal strain at break is significantly higher than 10% for compositions 5 and 4.

[0271] [Table 4]

[0272] 5 The specimen prepared from an extruded sheath of composition 7c underwent a preparatory machining / milling operation before testing in order to remove the defects present on the surface (see Table 3) and allow the characterization of its mechanical properties.

[0273] Table 4: Mechanical properties

[0274] Flexibility

[0275] A 4-meter-long flexible pipe prototype consisting of a metal frame around which a polymer sheath is extruded was subjected to a bending test. To carry out the test, the flexible pipe prototype is mounted fixed and is blocked at one of its ends and left free to deform at its other end to allow it to be moved by the test bench cylinders.

[0276] Bending and counter-bending stresses were applied sequentially, with the pipe returning to its natural unbent shape at the end of a cycle. The pipe thus experienced a stress level varying from -2% to +2% for each cycle, and this for 1000 cycles, without any damage being observed on the polymer sheath.

[0277] Resistance to blistering phenomenon

[0278] Parts of the sheath made from composition 4 were cut while retaining the full thickness of the sheath.

[0279] Two types of gas exposure tests followed by rapid decompression were performed. In the first test, the samples were exposed to diesel for 15 days at 100°C without significant swelling of the sheath. After this conditioning, the samples were exposed in an autoclave to a gas mixture of 85% CH4- 15% CC^ at 520 bar and 1 10°C for a minimum of 72 hours followed by rapid gas decompression at 70 bar / min. This cycle was repeated 5 times and after removing the sample from the autoclave, the samples showed no signs of damage after observation under a microscope at 20x magnification.

[0280] In the second test, the samples were exposed to pure CO2 at 680 bar and 110°C followed by rapid gas decompression at 70 bar / min. After removing the samples from the autoclave, they showed no signs of damage.

[0281] Permeation resistance

[0282] Portions of the sheath made from composition 4 were prepared by machining to obtain thin membranes 1.5 mm thick from a localized area in the core of the sheath cross-section.

[0283] The permeation resistance was determined using the device for measuring the permeation coefficient of a sheath sample with respect to a gas as illustrated in Figure 2 and described from page 13, line 16 to page 15 line 2 of application FR 2 987 666. The method used is that described on page 15, line 7 to page 18, line 26 of this application, in which the gas used was pure CO2, the temperature was 80°C and the pressure difference between the two sides of the membrane was 40 bars. The permeation resistance was calculated using equation [6] described on page 18, line 12 of this application. The values ​​obtained for composition 4 are less than 1.1x10 -8 (cm 3 .cm) / (cm 2 .s.bar). This represents a significant reduction compared to the reference pressure sheath materials considered, namely:

[0284] 2.9x10 -7 (cm 3 .cm) / (cm 2.s.bar) for TotalEnergies MDPE 3802 polyethylene, 1.2x10 -7 (cm 3 .cm) / (cm 2 .s.bar) for polyamide PA1 1 Rilsan® BESNO P40 TL from Arkema,

[0285] 1,4x10 7 (cm 3 .cm) / (cm 2 .s.bar) for Arkema's Kynar® 400 HDC M800 PVDF, and 2.39x10 -8 (cm 3 .cm) / (cm 2 .s.bar) for Kuraray's PA9T GenestarTM N1006D H31.

[0286] Example 3: Thermal degradation of Siltem® STM 1500 as a function of temperature

[0287] The mass loss of a poly(etherimide-siloxane) copolymer sample (Siltem® STM 1500) was determined by thermogravimetric analysis (TGA) after heating under nitrogen at different temperatures for 1 hour. The results are provided in Figure 2, which shows that below 350°C, the mass loss (related to thermal degradation of the copolymer) is low, even less than 1% up to 340°C, but that it increases rapidly for temperatures above 350°C. This justifies the interest of a temperature for melt-blending a composition comprising such a copolymer which remains less than or equal to 350°C, preferably less than or equal to 340°C.

Claims

CLAIMS 1. Subsea pipe intended for the transport of hydrocarbons and / or gas comprising from the outside to the inside: at least one reinforcing layer, and an internal polymeric sealing sheath comprising a layer of polymeric material sheathed around a metal carcass, characterized in that the polymeric material of said layer of the internal polymeric sealing sheath is a composition C comprising a non-delaminating mixture M of polymers, the mixture M comprising: at least 50% by weight of at least one polyaryletherketone, pseudoamorphous or semi-crystalline, said polyaryletherketone having a melting temperature of less than or equal to 340°C, relative to the total weight of the mixture M; and, from 5% to 40% by weight of a poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M.

2. The pipe of claim 1, wherein said polyaryletherketone having a melting temperature of less than or equal to 340°C, has a melting temperature of less than or equal to 335°C, or less than or equal to 330°C, or less than or equal to 325°C, or less than or equal to 320°C.

3. Pipe according to any one of claims 1 to 2, in which the mixture M comprises less than 15% by weight, preferably less than 10% by weight, of a polyaryletherketone having a melting temperature strictly greater than 340°C relative to the total weight of mixture M.

4. Pipe according to any one of claims 1 to 3, in which the mixture M comprises more than 7.5% by weight, and preferably more than 8% by weight, of the poly(etherimide-siloxane) copolymer, and / or the mixture M comprises less than 30%, preferably less than 25% by weight of the poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M.

5. Pipe according to any one of claims 1 to 4, in which, when the mixture M comprises from 5% to 7.5% by weight of a copolymer poly(etherimide-siloxane), then composition C does not include polysiloxane.

6. Pipe according to any one of claims 1 to 5, in which composition C does not comprise polysiloxane.

7. Pipe according to any one of claims 1 to 6, in which the layer of the internal polymeric sealing sheath whose polymeric material is composition C has a thickness greater than 3 mm, in particular greater than 4 mm, preferably greater than 5 mm, particularly preferably greater than 6 mm.

8. Pipe according to any one of claims 1 to 7, in which the layer of the internal polymeric sealing sheath of the pipe whose polymeric material is composition C: has a CO2 permeation measured according to API standard 17J:2009 at 60°C of less than 1.1x10 8 (cm 3 (STP).cm) / (cm 2 .s.bar), and / or has a tensile modulus of elasticity, as measured according to ISO 527-1A:2019 at 20°C, of ​​less than 4.0 GPa, typically less than 3.5 GPa, in particular less than 3.2 GPa, preferably less than 3.0 GPa, and / or has a nominal strain at break as measured according to ISO 527-1 A:2019 at 20°C of greater than 8%, typically greater than 10%, in particular greater than 15%, preferably greater than 20%, and / or has a Charpy impact strength according to ISO 179-1:2010 / 1 eA of greater than 5 KJ / m 2 , preferably greater than 6 KJ / m 2 , preferably still greater than 7 KJ / m 2, and more preferably greater than 8 KJ / m 2 , has a yield stress, as measured by ISO 527-1A:2019 at 20°C, of ​​less than 85 MPa, and / or withstands five blistering cycles in an 85% CH4- 15% CO2 mixture at 520 bar and 110°C after exposure to diesel at 100°C for 15 days and / or withstands one blistering cycle in 100% CO2 at 680 bar and 110°C, with resistance to blistering being evaluated according to API 17J:2014.

9. Pipe according to any one of claims 1 to 8, in which the internal polymeric sealing sheath is single-layer, the polymeric material of the single-layer being said composition C.

10. Pipe according to any one of claims 1 to 8, in which the internal polymeric sealing sheath is multi-layer, the internal polymeric sealing sheath comprising, in addition to the layer whose polymeric material is composition C, at least one other layer of polymeric material, preferably chosen from polyolefins, in particular high density or crosslinked polyethylene, polyamides, in particular PA 1 1, and fluorinated polymers, in particular PVDF.

11. Pipe according to any one of claims 1 to 10, in which the at least one reinforcing layer is at least one tensile armor ply or a pressure vault.

12. Pipe according to claim 11 comprising, from the outside to the inside: optionally an external polymeric sealing sheath, at least one tensile armor ply, generally an even number of tensile armor plies, typically two tensile armor plies, optionally a pressure vault, the internal polymeric sealing sheath comprising the layer of polymeric material defined in any one of claims 1 to 10, and sheathed around the metal carcass.

13. Method for preparing the underwater pipe according to any one of claims 1 to 12, comprising the following steps: a) extrusion to form the internal polymeric sealing sheath defined according to any one of claims 1 to 10, the extrusion being carried out on the metal carcass, b) assembly of the internal polymeric sealing sheath obtained in step a) with the at least one reinforcing layer.

14. The method of claim 13, wherein the maximum temperature during extrusion does not exceed 350°C, or does not exceed 345°C, or does not exceed 340°C, or does not exceed 335°C.

15. Use of an underwater pipeline according to any one of claims 1 to 12 for the transport of hydrocarbons and / or gas, in particular CO2.

16. A method of extracting hydrocarbons comprising: extracting a mixture of hydrocarbons and CO2 from an underwater deposit, separating the hydrocarbons and CO2, transporting at least a portion of the separated CO2 to said underwater deposit in the pipe according to any one of claims 1 to 12, reinjecting the transported CO2 into said underwater deposit. 17.Use of a composition C comprising a non-delaminating mixture M of polymers, the mixture M comprising: at least 50% by weight of at least one polyaryletherketone, pseudoamorphous or semi-crystalline, said polyaryletherketone having a melting temperature of less than or equal to 340°C, relative to the total weight of the mixture M; and, from 5% to 40% by weight of a poly(etherimide-siloxane) copolymer, relative to the total weight of the mixture M, as polymeric material of a layer of an internal polymeric sealing sheath, said layer being sheathed around a metal carcass of an underwater pipeline intended for the transport of hydrocarbons and / or gas and comprising at least one metal reinforcing layer around said internal polymeric sealing sheath, to improve the permeation resistance of said internal polymeric sealing sheath, and / or to improve the stress corrosion resistance of said at least one metal reinforcing layer.

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