Multilayer structures for transporting or storing gas or for exploiting offshore oil deposits on the seabed

Abstract

The present invention relates to a multi-layer structure for transporting or storing gas or for exploiting offshore oil or gas deposits, comprising, from the inside to the outside, at least one sealing layer and at least one composite reinforcing layer, the innermost composite reinforcing layer being welded to the outermost adjacent sealing layer, the sealing layers consisting of a composition mainly comprising at least one semi-crystalline thermoplastic polymer P1i (i = 1 to n, n is the number of sealing layers) having a Tm of less than 280 °C, in particular less than 265 °C, measured according to ISO 11357-3:2013, the at least one thermoplastic polymer of each sealing layer being the same or different. at least one of the composite reinforcing layers may consist of a fibrous material in the form of continuous fibres impregnated with a composition comprising mainly at least one thermoplastic polymer P2j, in particular semi-crystalline, where j = 1 to m, m being the number of reinforcing layers, and the thermoplastic polymer P2j has a Tg, measured in accordance with ISO11357-3:2013, higher than the maximum use temperature (Tu) of the structure, Tg ≥ Tu + 20°C, where Tu is higher than 50°C, in particular higher than 100°C; hydrogen is excluded from the gas transport or gas storage, and multilayer structures selected from reservoirs, pipes or tubes for transporting or storing hydrogen are excluded. It relates to a multilayer structure.

Description

[Technical Field]

[0001] This patent application relates to composite multi-layer structures for transporting or storing gas or for exploiting offshore oil or gas deposits, and to methods for manufacturing said structures. [Background technology]

[0002] The exploitation of oil deposits located offshore exposes the materials used to extreme conditions, in particular the pipes that connect the various underwater equipment of the platform and carry the extracted hydrocarbons, which are generally transported at high temperatures and pressures (e.g. 700 bar).

[0003] Therefore, during the operation of the facility, the mechanical strength and heat and chemical resistance of the materials used are crucial issues. In particular, such pipes must be able to withstand high-temperature oil, gas, water, and mixtures of at least two of these products for up to 20 years.

[0004] Traditionally, these pipes include a non-sealing metallic lining formed by a spirally wound metal strip, such as a lock seam strip, which gives the pipe its shape and is then coated, generally by extrusion, with a polymer layer intended to provide a seal.

[0005] This sheath is mainly It must be capable of being continuously extruded onto the support of an inner carcass, if necessary, and must be sufficiently flexible to accommodate the curvatures imposed on the flexible pipe during the manufacturing, laying, and use operations of the flexible pipe on site (movements due to expansion or lifting of the flexible pipe to change its location of use); It must be able to withstand compressive creep, which is exacerbated by temperature levels (creep occurs in gaps (spaces or clearances) between the metal reinforcements it supports (e.g. Z-shaped self-locking seams or T-shaped seams) when the pipeline is pressurized by the transported effluent); It must be sufficiently chemically stable so that its mechanical properties and its seal do not deteriorate in a manner that would be fatal during the life of the flexible pipe.

[0006] For the transportation or storage of gas, or the extraction of oil or gas deposits, it is beneficial to use composite pipes consisting of this sealing sheath, also called a liner (which provides sealing for the pipe and chemical and abrasion resistance), reinforced by an outer adhesive layer made of composite material, manufactured by filament winding from unidirectional (UD) tapes that are deposited in successive layers on the liner, at one or more orientation angles to the axis of the pipe, so as to provide sufficient flexibility for the composite pipe. The composite reinforcement allows the pipe to withstand pressure (internal fluid pressure and external pressure in deep-sea applications).

[0007] This technology has been developed by the company Airborne and is described, for example, in document FR2964173.

[0008] More recently, Technip (WO2012118379) has been interested in this pipe concept in combination with metal external reinforcements, possibly constituting pressure arches, with the aim of eliminating the inner carcass of current offshore flexible pipes.

[0009] However, the solution envisaged for this type of composite pipe is based on using the same polymer for the liner and the matrix of the composite in order to guarantee a good and durable bond between the liner and the composite.

[0010] For example, Airborne has developed a range of flexible pipes that have no inner carcass but instead have a sealed sheath bonded to a composite reinforcement. PA11 liner with PA11 FC composite (JIP completed in 2011), or PA12 liner with PA12 FC composite, or PVDF liner with PVDF FC composite However, all of these structures have the disadvantage that the matrix of the composite reinforcement has a glass transition temperature (Tg) lower than the service temperature (Tu) of the pipe. For pipes based on PA11 or PA12, this is 50°C in the dry state at a service temperature (Tu) of 60-80°C, while for PVDF, it is -40°C at service temperatures above 100°C, often approaching 130°C, during continuous operation. In the special case of PVDF, the matrix stiffness (modulus) remains high until another transition above its Tg is reached, the alpha transition being around 100°C, beyond which its behavior becomes purely rubbery. Therefore, in all of the above-mentioned industrial and commercial cases of TP matrix composite pipes, the matrix of the composite reinforcement is fully rubberized at the service temperature (Tu) of the composite pipe.

[0011] To solve this problem and ensure that the matrix does not become rubbery at the service temperature (in this case, 130°C), Kutting & Total, followed by Vitrex and Magma, developed a solution consisting of a PEEK sealing sheath (or liner) reinforced with a composite with a PEEK matrix. PEEK's Tg is 140°C, which is therefore higher than the maximum service temperature and therefore meets the high stiffness requirement. The disadvantage is that the resulting sealing sheath (liner) is also very stiff, which can limit fatigue resistance and is a major disadvantage for flexible pipe manufacturing. Furthermore, the processing temperatures for this type of sealing sleeve are very high (typically 380-400°C), which presents significant challenges in terms of tooling and process control for the usual deformation process, which is tube extrusion.

[0012] Additionally, Ticona (Celanese) has partnered with Airborne to offer composite pipes containing PPS FC reinforcements and a PPS sealed sheath.

[0013] When Tu > 90°C, this structure presents the same problems of composite matrix as the PVDF-based solution (i.e., Tg < Tu), and further shows the problem of deformation temperature (in the cases of PPS and PVDF, typically 350°C vs. 250°C respectively).

[0014] When Tu < 90°C, PPS is suitable for the matrix of the composite material, but the problem of its high rigidity that limits the flexibility of the composite pipe and the problem of its low fatigue resistance due to Tg higher than Tu remain, as well as the problem of the extrusion temperature of the sealing sheath (liner).

[0015] Therefore, still, on the one hand, optimize the matrix of the composite material to optimize its mechanical strength at high temperatures, and on the other hand, optimize the material that constitutes the sealing liner to optimize its application temperature without reducing the adhesion of the composite reinforcing material to the sealing liner. Therefore, the possible change in the composition of the material that constitutes the sealing sheath, which is carried out to ensure at least partial miscibility with the matrix of the composite material, should not lead to a significant increase in the extrusion temperature of this liner (i.e., remain < 300°C, preferably < 290°C, and even more preferably < 250°C).

[0016] These problems are solved by providing the multi-layer structure and especially the flexible pipe of the present invention, which is a fully bonded "binary material" composite pipe, deposited by filament winding on a liner that is pre-extruded at a relatively low temperature, especially composed of high-strength composite reinforcing materials. The adhesion between the composite material and the liner is very good.

Summary of the Invention

[0017] Therefore, the present invention is a multi-layer structure selected from storage tanks, pipes or tubes for transporting or storing gas or for mining offshore oil or gas deposits, comprising, from the inside to the outside, at least one sealing layer and at least one composite reinforcing layer, the innermost composite reinforcing layer is welded to the outermost adjacent sealing layer; the sealing layer consists of a composition comprising mainly at least one semi-crystalline thermoplastic polymer P1i (i = 1 to n, n is the number of sealing layers) having a Tm of less than 280 ° C, in particular less than 265 ° C, measured according to ISO 11357-3:2013, the at least one thermoplastic polymer of each sealing layer may be the same or different, at least one of the composite reinforcing layers consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one thermoplastic polymer P2j, in particular semi-crystalline, with j=1 to m, m being the number of reinforcing layers, the thermoplastic polymer P2j having a Tg, measured according to ISO 11357-3:2013, higher than the maximum use temperature (Tu) of the structure, Tg ≥ Tu + 20 ° C, with Tu being higher than 50 ° C, in particular higher than 100 ° C, Hydrogen is excluded from said gas transport or gas storage, and multi-layer structures intended to transport hydrogen selected from reservoirs, pipes or tubes are excluded. It relates to a multilayer structure.

[0018] Therefore, the inventors have proposed using different polymers for the composite matrix and liner, in particular: The matrix of the composite reinforcement is composed of a polymer having a Tg significantly higher than the maximum service temperature Tu of the reservoir or pipe (typically Tg > Tu + 20°C) so as to remain in its glassy domain and have high stiffness, thus allowing the composite to have high mechanical strength; It has been unexpectedly discovered that the semi-crystalline polymers constituting the liner have a low melting point Tm, which allows them to be processed by extrusion, extrusion blow molding, rotational molding, injection molding or pure resin film wrapping at moderate temperatures, as the case may be, relative to the Tm of this polymer, below 280°C, preferably below 265°C, as commonly used by those skilled in the art. The low Tm semi-crystalline polymers known to date also have a low Tg, which in most cases will be below the maximum use temperature. As a result, the polymers constituting the liner are very flexible and highly resistant to fatigue, since they operate in a rubberized region. Their semi-crystalline nature ensures good resistance to chemical attack, abrasion and creep, and The two polymers mentioned above (one constituting the composite matrix and one constituting the liner) are sufficiently miscible to ensure weldability of the composite to the liner and, consequently, excellent adhesion between the liner and the composite. The durability of the adhesion is ensured by the durability of the materials constituting the mixture at the interface of the two materials, i.e., at the welded joint. The miscibility of the two polymers is preferably expressed by a single Tg or, if not, by a characteristic signature of a partially homogeneous mixture, for example, by the presence of two Tg values ​​intermediate to those of the two pure polymers. DETAILED DESCRIPTION OF THE INVENTION

[0019] The immiscibility of the two polymers results in the presence of two Tg's in the mixture of the two polymers, which correspond to the Tg's of each of the pure polymers measured separately.

[0020] By "multilayer structure" is meant, for example, a reservoir, pipe or tube comprising or consisting of several layers, in particular two layers.

[0021] The term "gas" refers to any gas, and in particular to offshore gas, especially natural gas excluding hydrogen.

[0022] The sealing layer(s) are the innermost layer compared to the composite reinforcing layer, which is the outermost layer.

[0023] Even if there is an inner, and therefore innermost, non-sealing metal layer formed by a spirally wound metal strip, such as a lock seam strip, forming the carcass, on which a sealing layer is coated by extrusion, the sealing layer(s) will come into contact with the gas or oil and gas extracted from the seabed.

[0024] If several sealing layers are present, only the innermost sealing layer is in direct contact with the gas or oil and gas extracted from the seabed.

[0025] If there is only one sealing layer and one composite reinforcing layer, then there will be a two layer multi-layer structure, and these two layers will be welded together and in direct contact with each other to bond them together.

[0026] If there are several sealing layers and / or several composite reinforcing layers, the outermost layer of said sealing layers, and therefore the layer opposite the layer in contact with the gas or oil and gas extracted on the seabed, is welded to the innermost layer of said composite reinforcing layers and is therefore in direct contact with each other and bonded to each other.

[0027] The other composite reinforcing layers are also welded together.

[0028] The other sealing layers are also welded together.

[0029] About the sealing layer and thermoplastic polymer P1i There may be one or more sealing layers.

[0030] Each of said layers consists of a composition mainly comprising at least one thermoplastic polymer P1i, where i corresponds to the number of layers present, and i is between 1 and 10, in particular between 1 and 5, in particular between 1 and 3, preferentially i=1.

[0031] The term "predominantly" means that said at least one polymer is present in greater than 50% by weight relative to the total weight of the composition.

[0032] Advantageously, said at least one primary polymer is present in an amount of more than 60% by weight, in particular more than 70% by weight, in particular more than 80% by weight and more particularly 90% or more by weight relative to the total weight of the composition.

[0033] The composition may further comprise an impact modifier and / or additive.

[0034] The additives may be selected from antioxidants, heat stabilizers, UV absorbers, light stabilizers, lubricants, inorganic fillers, flame retardants, nucleating agents, plasticizers, dyes, carbon black, and carbonaceous nanofillers.

[0035] Advantageously, said composition consists mainly of said thermoplastic polymer P1i, 0-5% by weight of impact modifiers, 0-5% by weight of additives, the sum of the components of the composition being equal to 100% (with a maximum of 90% of P2i).

[0036] The at least one primary polymer in each layer may be the same or different.

[0037] In one embodiment, a single predominant polymer is present in at least the sealing layer welded to the composite reinforcing layer.

[0038] Thermoplastic polymer P1i A thermoplastic, or thermoplastic polymer, refers to a semi-crystalline material that is generally solid at room temperature and that may soften during an increase in temperature, particularly after passing its glass transition temperature (Tg), and may exhibit a sharp transition as it passes what is called its melting point (Tm), becoming solid again when the temperature drops below its crystallization temperature.

[0039] Tg, Tc, and Tm are determined by differential scanning calorimetry (DSC) according to standards 11357-2:2013 and 11357-3:2013, respectively.

[0040] The number average molecular weight Mn of said thermoplastic polymer is preferably in the range of 10 000 to 40 000, preferably in the range of 12 000 to 30 000. These Mn values ​​may correspond to an intrinsic viscosity of 0.8 or greater, when determined with m-cresol according to standard ISO 307:2007, but by changing the solvent (using m-cresol instead of sulfuric acid, and the temperature being 20° C.).

[0041] Examples of suitable semi-crystalline thermoplastic polymers in the present invention include: Copolymers such as polyamide-polyether copolymers, polyesters, polyamides including PVDF and PVDF / PEI blends in which PVDF is predominant.

[0042] Particularly more preferred among the semi-crystalline polymers are polyamides and their semi-crystalline copolymers.

[0043] The nomenclature used to define polyamides is described in ISO standard 1874-1:2011 "Plastiques -- Materiaux polyamides (PA) pour moulage et extrusion -- Partie 1: Designation", in particular page 3 (Tables 1 and 2), and is well known to those skilled in the art.

[0044] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

[0045] Advantageously, said thermoplastic polymer is a long-chain aliphatic polyamide, ie a polyamide having an average number of carbon atoms per nitrogen atom greater than 8.5, preferably greater than 9.

[0046] In particular, long-chain aliphatic polyamides include polyamide 11 (PA11), polyamide 12 (PA12), polyamide 1010 (PA1010), polyamide 1012 (PA1012), and polyamide 1212 (PA1 212), or mixtures or copolyamides thereof, in particular PA11 and PA12.

[0047] Advantageously, said thermoplastic polymer is a long-chain semi-aromatic polyamide, i.e. a polyamide having an average number of carbon atoms per nitrogen atom greater than 8.5, preferably greater than 9, and having a melting point between 240 and 280°C.

[0048] In particular, the long-chain semi-aromatic polyamide is selected from polyamides 11 / 5T or 11 / 6T or 11 / 10T. Obviously, in this case, the 11 content must be carefully selected so that the Tm of the polymer is less than 280°C, preferably less than 265°C.

[0049] Advantageously, each sealing layer consists of a composition comprising the same type of polymer, in particular polyamide.

[0050] Advantageously, the composition comprising the polymer P1i is black and is able to absorb radiation suitable for welding.

[0051] There are various methods of welding thermoplastic polymer parts: thus, contact or non-contact heated blade, ultrasonic, infrared, vibration, rotary or even laser welding of one element to be welded to the other may be used.

[0052] The welding of thermoplastic polymer elements, particularly by laser welding, requires that the two elements to be welded have different properties with respect to radiation, particularly laser radiation: one element must be transparent to radiation, particularly laser radiation, while the other element must absorb radiation, particularly laser radiation. The radiation, particularly laser radiation, passes through the transparent part and then reaches the absorbing element, where it is converted into heat. This melts the contact area between the two elements, resulting in a weld.

[0053] In some applications, it is desirable that both the parts to be welded, including the part that is transparent to laser radiation, be black.

[0054] To make them absorbent, it is known to add various additives, including, for example, carbon black, to give the polymer a black color and the ability to absorb radiation suitable for welding.

[0055] In one embodiment, the welding is performed by a system selected from laser, IR heating or induction heating.

[0056] If the welding is carried out by laser welding, the composition P1i comprises a non-lumpy or non-agglomerated carbonaceous filler.

[0057] If the welding is carried out by induction, the composition P1i comprises metal particles.

[0058] Advantageously, the welding is carried out by a laser system.

[0059] Composite reinforcement layer and thermoplastic polymer P2j There may be one or more composite reinforcing layers.

[0060] Each of said layers consists of a composition mainly comprising at least one thermoplastic polymer P2j, where j corresponds to the number of layers present.

[0061] j is comprised between 1 and 10, in particular between 1 and 5, in particular between 1 and 3, with j=1 being preferred.

[0062] The term "predominantly" means that said at least one polymer is present in greater than 50% by weight relative to the total weight of the composition.

[0063] Advantageously, said at least one primary polymer is present in an amount of more than 60% by weight, in particular more than 70% by weight, in particular more than 80% by weight and more particularly 90% or more by weight relative to the total weight of the composition.

[0064] The composition may further comprise an impact modifier and / or additive.

[0065] The additives may be selected from antioxidants, heat stabilizers, UV absorbers, light stabilizers, lubricants, inorganic fillers, flame retardants, nucleating agents, plasticizers, and dyes.

[0066] Advantageously, said composition consists mainly of said thermoplastic polymer P2j, 0-5% by weight of impact modifiers, 0-5% by weight of additives, the sum of the components of the composition being equal to 100% (for a maximum of 90% of P2j).

[0067] The at least one primary polymer in each layer may be the same or different.

[0068] In one embodiment, a single predominant polymer is present in at least the composite reinforcing layer welded to the sealing layer.

[0069] In one embodiment, each reinforcing layer comprises the same type of polymer, in particular polyamide.

[0070] Thermoplastic polymer P2j Thermoplastics, or thermoplastic polymers, are intended to mean materials that are generally solid at room temperature, may be semi-crystalline or amorphous, and in particular semi-crystalline, that soften during temperature increase, in particular after passing its glass transition temperature (Tg), and flow at higher temperatures if amorphous, or that may exhibit precise melting once passing its melting point (Tm) if semi-crystalline, and that become solid again when the temperature drops below its crystallization temperature (in the case of semi-crystalline) and below its glass transition temperature (in the case of amorphous).

[0071] Tg, Tc, and Tm are determined by differential scanning calorimetry (DSC) according to standards 11357-2:2013 and 11357-3:2013, respectively.

[0072] The polymer P2j of at least one composition of said composite reinforcing layer is such that its Tg is higher than the maximum use temperature (Tu) of said structure, in particular Tg ≥ Tu + 20°C.

[0073] In one embodiment, the polymer P2j has a Tg > Tu + 20°C regardless of the position of said reinforcing layer.

[0074] In another embodiment, the reinforcing layer, consisting of a composition comprising a polymer P2j having a Tg≧Tu+20° C., is the layer that is welded to the sealing layer.

[0075] In another embodiment, the reinforcing layer consisting of a composition comprising a polymer P2j having a Tg≧Tu+20° C. is the outermost reinforcing layer of the structure. The number-average molecular weight Mn of the thermoplastic polymer is preferably in the range of 10,000 to 40,000, preferably in the range of 12,000 to 30,000. These Mn values ​​may correspond to an intrinsic viscosity of 0.8 or greater, when determined with m-cresol according to standard ISO 307:2007, but by changing the solvent (using m-cresol instead of sulfuric acid and at a temperature of 20° C.).

[0076] Examples of suitable semi-crystalline thermoplastic polymers in the present invention include: Polyamides, in particular copolymers containing aromatic and / or alicyclic structures, such as polyamide-polyether copolymers; polyester, Polyaryletherketone (PAEK), Polyetheretherketone (PEEK), Polyetherketoneketone (PEKK), Polyetherketoneetherketoneketone (PEKEKK), polyimides, in particular polyetherimides (PEI) or polyamide-imides, Polysulfones (PSU), in particular polyarylsulfones such as polyphenylsulfone (PPSU), Polyethersulfone (PES) Examples include:

[0077] Semicrystalline polymers are especially preferred, especially polyamides and their semicrystalline copolymers.

[0078] The nomenclature used to define polyamides is described in ISO standard 1874-1:2011 "Plastiques -- Materiaux polyamides (PA) pour moulage et extrusion -- Partie 1: Designation", in particular page 3 (Tables 1 and 2), and is well known to those skilled in the art.

[0079] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

[0080] Advantageously, the semicrystalline polyamide is a semi-aromatic polyamide, in particular a semi-aromatic polyamide of formula X / YAr as described in EP 1 505 099, in particular a semi-aromatic polyamide of formula A / XT, in which A is a unit derived from an amino acid, a unit derived from a lactam, and a represents the number of carbon atoms of the diamine, b represents the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, and the units (Ca diamine) are chosen from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines, and the units (Cb diacid) are chosen from units corresponding to the formula (Ca diamine).(Cb diacid), which are chosen from linear or branched aliphatic diacids, cycloaliphatic diacids, aromatic diacids,

[0081] XT denotes units resulting from the polycondensation of a Cx diamine and terephthalic acid, where x represents the number of carbon atoms in the Cx diamine and is between 6 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above and in particular a polyamide selected from PA MPMDT / 6T, PA11 / 10T, PA 5T / 10T, PA11 / BACT, PA11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA11 / BACT / 6T, PA11 / MPMDT / 6T, PA11 / MPMDT / 10T, PA11 / BACT / 10T, PA11 / MXDT / 10T, 11 / 5T / 10T.

[0082] T corresponds to terephthalic acid, MXD corresponds to m-xylenediamine, MPMD corresponds to methylpentamethylenediamine, and BAC corresponds to bis(aminomethyl)cyclohexane.

[0083] Advantageously, each composite reinforcing layer consists of a composition comprising the same type of polymer, in particular polyamide.

[0084] Advantageously, the composition comprising the polymer P2j is transparent to radiation suitable for welding.

[0085] Thermoplastic polymers are generally transparent for welding purposes, in particular laser welding. Carbonaceous nanofillers make it possible to impart a black color to a layer of a composition comprising a thermoplastic polymer while maintaining the layer's transparency to laser radiation.

[0086] Advantageously, the carbonaceous nanofillers are non-agglomerated or non-agglomerated.

[0087] Advantageously, the carbonaceous nanofiller is incorporated into the composition in an amount between 100 ppm and 500 ppm, preferably between 100 ppm and 250 ppm.

[0088] Advantageously, the carbonaceous nanofillers are chosen from carbon nanotubes (CNTs), carbon nanofibers, graphene, nanoscale carbon black and mixtures thereof.

[0089] Advantageously, the carbonaceous nanofiller does not include nanometric carbon black.

[0090] In one embodiment, the welding is performed by a system selected from laser, IR heating or induction heating.

[0091] Advantageously, the welding is carried out by a laser system.

[0092] Advantageously, the laser radiation is infrared laser radiation, preferably having a wavelength between 700 nm and 1200 nm, and preferably between 800 nm and 1100 nm.

[0093] About structures The multi-layer structure thus comprises at least one sealing layer and at least one composite reinforcing layer welded together.

[0094] In one embodiment, in said multilayer structure, each polymer P1i of each sealing layer is partially or fully miscible with each polymer P1i of an adjacent layer, each polymer P2j of each reinforcing layer is partially or fully miscible with each polymer P2j of an adjacent layer, and when adjacent, each polymer P2j is partially or fully miscible with each polymer P1i, and polymer P21 is partially or fully miscible with the polymer P11 adjacent to it; The complete or partial miscibility of the polymers is defined by the difference in the glass transition temperatures of the two resins in the mixture relative to the difference in the glass transition temperatures of the two resins before mixing; if said difference is equal to 0, the miscibility is complete, and if said difference is different from 0, the miscibility is partial, excluding immiscibility of polymer P2j with polymer P1i.

[0095] If the polymers are partially miscible, the difference is such that the greater the miscibility, the smaller the difference.

[0096] Advantageously, when the miscibility of said polymers is partial, said difference is less than 30% in absolute value, preferentially less than 20%.

[0097] In one embodiment, the glass transition temperature(s) of the mixture, depending on whether miscibility is complete or partial, must be between and differ from the glass transition temperatures of the polymers prior to blending by at least 5°C, preferably at least 10°C.

[0098] The expression "completely miscible" means, for example, that when two polymers P11 and P12 having Tg11 and Tg12 respectively are present in two adjacent sealing layers or two adjacent reinforcing layers, the mixture of the two polymers has only one Tg1112, the value of which is between Tg11 and Tg12.

[0099] This Tg1112 value is thus at least 5 °C, especially at least 10 °C higher than Tg11 and at least 5 °C, especially at least 10 °C lower than Tg12.

[0100] The expression "partially miscible" means, for example, that when two polymers P11 and P12 having Tg11 and Tg12 respectively are present in two adjacent sealing layers or two adjacent reinforcing layers respectively, the mixture of the two polymers has two Tgs of Tg’11 and Tg’12 with Tg11 < Tg’11 < Tg’12 < Tg12.

[0101] These Tg’11 and Tg’12 values are at least 5 °C, especially at least 10 °C higher than Tg11 and at least 5 °C, especially at least 10 °C lower than Tg12.

[0102] The immiscibility of the two polymers results in the presence of two Tgs of Tg11 and Tg12 corresponding to the respective Tgs of the pure polymers measured separately in the mixture of the two polymers.

[0103] Advantageously, the welded sealing layer and the reinforcing layer are made of compositions each containing a different polymer.

[0104] [[ID=2,3]] Nevertheless, the different polymers may be of the same type.

[0105] Thus, if one of the two welded composite reinforcement and sealing layers is made from a composition comprising an aliphatic polyamide, the other layer is made from a composition comprising a polyamide that is not aliphatic, e.g., a semi-aromatic polyamide, so as to have a high Tg polymer as the matrix of the composite reinforcement.

[0106] The multi-layer structure may include up to 10 sealing layers and up to 10 composite reinforcing layers.

[0107] It will be appreciated that the multi-layer structure is not necessarily symmetrical and may therefore include more sealing layers than composite layers, or vice versa.

[0108] Advantageously, said multilayer structure comprises 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 sealing layers and 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 composite reinforcing layers.

[0109] Advantageously, said multilayer structure comprises 1, 2, 3, 4 or 5 sealing layers and 1, 2, 3, 4 or 5 composite reinforcing layers.

[0110] Advantageously, said multilayer structure comprises one, two or three sealing layers and one, two or three composite reinforcing layers.

[0111] Advantageously, they each consist of a composition comprising a different polymer.

[0112] Advantageously, they consist of compositions comprising polyamides corresponding to polyamides P1i and P2j, respectively.

[0113] Advantageously, they each consist of a composition comprising a different polyamide.

[0114] In one embodiment, the multi-layer structure comprises a single sealing layer and several reinforcing layers, the sealing layers being welded to the adjacent reinforcing layers.

[0115] In another embodiment, the multi-layer structure comprises a single reinforcing layer and several sealing layers, the reinforcing layers being welded to the adjacent sealing layers.

[0116] In one advantageous embodiment, the multi-layer structure includes a single sealing layer and a single composite reinforcing layer that are welded together.

[0117] Therefore, all combinations of these two layers are within the scope of the present invention, as long as at least the innermost composite reinforcing layer is welded to the outermost adjacent sealing layer, whether or not the other layers are welded together.

[0118] Advantageously, in said multilayer structure, each sealing layer consists of the same type of polymer P1i, in particular a composition comprising a polyamide.

[0119] The expression "polymer of the same type" means, for example, polyamides which may be the same or different depending on the layer.

[0120] Advantageously, said polymer P1i is a polyamide and said polymer P2j is a polyamide.

[0121] Advantageously, the polyamide P1i is the same for all sealing layers.

[0122] Advantageously, said polymer P1i is a long-chain aliphatic polyamide, in particular PA1010, PA1012, PA1212, PA11, PA12, in particular PA11 or PA12.

[0123] Advantageously, the polyamide P1i is a long-chain semi-aromatic polyamide, in particular PA11 / 5T, PA11 / 6T or PA11 / 10T. Obviously, in this case, the content of 11 must be carefully selected so that the Tm of the polymer is less than 280°C, in particular less than 265°C.

[0124] Advantageously, in said multilayer structure, each reinforcing layer consists of a composition comprising the same type of polymer P2j, in particular polyamide.

[0125] Advantageously, the polyamide P2j is the same for all reinforcing layers.

[0126] Advantageously, said polymer P2j is a semi-aromatic polyamide, in particular chosen from PA MXDT / 6T, PA11 / 10T, PA11 / BACT, PA5T / 10T, PA11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA11 / BACT / 6T, PA11 / MPMDT / 6T, PA11 / MPMDT / 10T, PA11 / BACT / 10T, PA11 / MXDT / 10T and PA5T / 10T.

[0127] Advantageously, in said multilayer structure, the polyamides P1i and P2j are different, i.e., each sealing layer consists of a composition comprising the same type of polymer P1i, in particular a polyamide, and each reinforcing layer consists of a composition comprising the same type of polymer P2j, in particular a polyamide, insofar as the sealing layer consists of a composition comprising a long-chain aliphatic polyamide, and the sealing layer consists of a composition comprising a semi-aromatic polyamide.

[0128] Advantageously, the polymer P1i is a long-chain aliphatic polyamide, in particular PA1010, PA1012, PA1212, PA11, PA12, in particular PA11 or PA12, and the polymer P2j is a semi-aromatic polyamide, in particular chosen from PA MPMDT / 6T, PA PA11 / 10T, PA11 / BACT, PA5T / 10T, PA11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA11 / BACT / 6T, PA11 / MPMDT / 6T, PA11 / MPMDT / 10T, PA11 / BACT / 10T, PA11 / MXDT / 10T and PA5T / 10T.

[0129] Advantageously, the multilayer structure consists of a single reinforcing layer and a single sealing layer in which the polymer P1i is a long-chain aliphatic polyamide, in particular PA1010, PA1012, PA1212, PA11, PA12, in particular PA11 or PA12, and the polymer P2j is a semi-aromatic polyamide, in particular selected from PA MPMDT / 6T, PA PA11 / 10T, PA11 / BACT, PA11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA11 / BACT / 6T, PA11 / MPMDT / 6T, PA11 / MPMDT / 10T, PA11 / BACT / 10T, PA11 / MXDT / 10T.

[0130] Advantageously, said multilayer structure is a flexible pipe.

[0131] The maximum use temperature Tu of the multilayer structure is above 50°C, in particular above 100°C.

[0132] In one embodiment, said multilayer structure as defined above has vacuum resistance and drying capabilities.

[0133] In fact, when storing or transporting gas, the permeability of the sealing layer to the transported or stored gas can allow the gas to diffuse through the sealing layer from the inside of the tube or reservoir to the interface between the outermost sealing layer and the first composite reinforcement layer. Gas accumulation in this location can create pressures that lead to the collapse of the sealing layer if the internal pressure of the tube or reservoir is lower than the pressure at the interface with the composite reinforcement. This can occur, in particular, when production is stopped, the pumping or transport of gas stops, and the pressure drops by several hundred bar to atmospheric pressure, or when the storage reservoir is empty. The same applies during internal hydrostatic testing of the reservoir; this water is likely to migrate by infiltration at the interface between the composite reinforcement and the outermost sealing layer, which will then be very difficult to remove, leading to lengthy and expensive drying cycles of the storage reservoir, especially under reduced pressure.

[0134] In another embodiment, said multi-layer structure as defined above further comprises a metal carcass located within the sealing layer.

[0135] This metal carcass is not leak-proof and is the innermost layer.

[0136] Advantageously, said multilayer structure further comprises at least one outer layer, in particular a metal layer, said layer being the outermost layer of said multilayer structure.

[0137] The outer layer is a second reinforcing layer, but is metallic and not composite.

[0138] There may also be a polymeric protective layer (outermost layer) on the structure, which serves as an abrasion protection or allows for inscriptions to be placed on the structure.

[0139] About fiber materials As regards the fibres that make up said fibrous material, these are in particular inorganic, organic or vegetable fibres.

[0140] Advantageously, said fibrous material may or may not be sized.

[0141] The fibrous material may therefore contain up to 0.1% by weight of organic material (thermosetting or thermoplastic type) called sizing agents.

[0142] Among fibers of inorganic origin, mention may be made of carbon fibers, glass fibers, basalt fibers or basalt-based fibers, silica fibers, or silicon carbide fibers. Organic fibers include, for example, fibers based on thermoplastic or thermosetting polymers, such as semi-aromatic polyamide fibers, aramid fibers, or polyolefin fibers. Preferably, they are based on amorphous thermoplastic polymers, with a Tg higher than the glass transition temperature (Tg) of the polymer or thermoplastic polymer mixture constituting the pre-impregnated matrix if the polymer or thermoplastic polymer mixture is amorphous, or a Tg higher than the Tm of the polymer or thermoplastic polymer mixture constituting the pre-impregnated matrix if the polymer or thermoplastic polymer mixture is semi-crystalline. Advantageously, they are based on semi-crystalline thermoplastic polymers, with a melting temperature (Tm) higher than the Tg of the polymer or thermoplastic polymer mixture constituting the pre-impregnated matrix if the polymer or thermoplastic polymer mixture is amorphous, or a Tm higher than the Tm of the polymer or thermoplastic polymer mixture constituting the pre-impregnated matrix if the polymer or thermoplastic polymer mixture is semi-crystalline. Therefore, there is no risk of melting of the organic fibers that make up the fibrous material during the impregnation of the final composite with the thermoplastic matrix. Plant fibers include natural linen, hemp, lignin, bamboo, silk, especially spider silk, sisal, and other cellulose fibers, especially viscose. These plant fibers can be used pure, treated, or coated with a coating layer to facilitate adhesion and impregnation of the thermoplastic polymer matrix.

[0143] The textile material may also be a woven fabric or braided cord.

[0144] It is also possible to accommodate fibers with supporting threads.

[0145] These constituent fibers may be used alone or as a mixture. Thus, the organic fibers may be mixed with the thermoplastic polymer powder to be pre-impregnated to form a pre-impregnated fibrous material.

[0146] The organic fiber strands can have any basis weight and can have any geometric shape. The constituent fibers of the fiber material can even assume the form of a mixture of these reinforcing fibers with different geometric shapes.

[0147] The fibers are continuous fibers.

[0148] The fibrous material is preferably selected from glass fibres, carbon fibres, basalt fibres and basalt-based fibres.

[0149] More advantageously, the fiber material is selected from carbon fibers, basalt fibers, and basalt-based fibers.

[0150] It is used in the form of one roving or several rovings.

[0151] According to another aspect, the present invention relates to a method for manufacturing a multilayer structure as defined above, characterized in that it comprises a step of welding a reinforcing layer as defined above to a sealing layer as defined above.

[0152] Advantageously, the welding process is carried out by a system selected from laser, infrared heating or induction heating.

[0153] Advantageously, the method comprises the steps of extruding the sealing layer onto a metal carcass and welding a reinforcing layer to the sealing layer.

[0154] According to another aspect, the present invention relates to the use of a multilayer structure selected from a reservoir or a pipe or tube, comprising, from the inside to the outside, at least one sealing layer as defined above and at least one composite reinforcing layer as defined above, the innermost composite reinforcing layer is welded to the outermost adjacent sealing layer; the sealing layer consists of a composition comprising mainly at least one semi-crystalline thermoplastic polymer P1i (i = 1 to n, n is the number of sealing layers) having a Tm of less than 280 ° C, in particular less than 265 ° C, measured according to ISO 11357-3:2013, the at least one thermoplastic polymer of each sealing layer may be the same or different, at least one of the composite reinforcing layers consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one thermoplastic polymer P2j, in particular semi-crystalline, with j=1 to m, m being the number of reinforcing layers, the thermoplastic polymer P2j having a Tg, measured according to ISO 11357-3:2013, higher than the maximum use temperature (Tu) of the structure, Tg ≥ Tu + 20°C, in particular Tg ≥ Tu + 30°C, with Tu being higher than 50°C, in particular higher than 100°C; for the preparation of tanks or pipes or tubes for transporting or storing gas or for the exploitation of offshore oil or gas deposits; The transport or storage of hydrogen is excluded, and tanks or pipes or tubes for transporting or storing gases are excluded. Multilayer structures selected from reservoirs, pipes or tubes for transporting or storing hydrogen are excluded. Regarding use. [Example]

[0155] In all cases the reservoir is obtained by rotational molding of the liner at a temperature compatible with the properties of the thermoplastic resin used, but in all cases below 280°C.

[0156] The tube is obtained by extruding the liner at a temperature appropriate to the properties of the thermoplastic resin used, which in all cases is below 280°C.

[0157] For epoxy, a wet filament winding method is used, which involves winding the fiber around a liner, pre-impregnating the fiber in a liquid epoxy bath, and then polymerizing it in an oven for two hours.

[0158] In all other cases, a fibrous material pre-impregnated with a thermoplastic resin (tape) is used, which is deposited by filament winding using a robot equipped with a 1500 W laser heater at a speed of 12 m / min.

[0159] Example 1 (counterexample) Flexible wastewater transport tubing (offshore applications) consisting of epoxy (Tg 130°C)-T700SC31E carbon fiber composite reinforcement and an HDPE sealing layer. There is no miscibility between the two resins (see Table I), which prevents any welding between the fibrous reinforcement and the sealing layer.

[0160] Example 2 Type IV or V gas (natural gas) storage tanks made of BACT / 10T-T700SC31E carbon fiber composite reinforcement and PA6 sealing layer. There is good partial compatibility between the two resins, allowing for good welding between the fibrous reinforcement and the sealing layer (see Table 1).

[0161] Example 3 Type IV or V gas (natural gas) storage tanks made of BACT / 10T-T700SC31E carbon fiber composite reinforcement and PA66 sealing layer. There is good partial compatibility between the two resins, allowing for good welding between the fibrous reinforcement and the sealing layer (see Table 1).

[0162] Example 4 Flexible pipe used for pumping petroleum, consisting of a BACT / 10T-T700SC31E carbon fiber composite reinforcement and a PA11 sealing layer deposited on an inner metal carcass. The partial miscibility between the two resins is low (see Table 1), leading to poor quality welding between the fibrous reinforcement and the sealing layer.

[0163] Example 5 11 / BACT / 10T-T700SC31E Flexible pipe used for pumping petroleum, consisting of a carbon fiber composite reinforcement and a PA11 sealing layer deposited on an inner metal carcass. There is good partial compatibility between the two resins (see Table 1), leading to a good weld between the fibrous reinforcement and the sealing layer.

[0164] In all examples in Table 1 below, to assess resin miscibility, blends were made from powders with particle size of approximately 150 μm in a Micro DSM with a 1 minute recirculation time after melting. All blends were made at 300°C, except for the epoxy-polyethylene blend, which was made at 220°C.

[0165] At the end of the mixing process, the mixture is poured into a mold to produce test specimens that are characterized by DMA. TIFF0007747616000001.tif134170 Compatibility test results - Column 4: Glass transition temperature of each resin before mixing - Column 5: Glass transition temperature of the resin in the mixture - Column 6: Ratio of the difference in glass transition temperature of the resins in the mixture to the difference in glass transition temperature of the resins before mixing. 100% indicates resin immiscibility; <80% indicates poor miscibility; <30% indicates good but partial miscibility; 0 indicates complete miscibility.

Claims

1. A multi-layer structure selected from a tank, a pipe or a tube for transporting or storing gas or for exploiting offshore oil or gas deposits, said multi-layer structure comprising, from the inside to the outside, at least one sealing layer and at least one composite reinforcing layer; The innermost composite reinforcement layer is welded to the adjacent outermost sealing layer; the sealing layer consists of a composition comprising mainly at least one semi-crystalline thermoplastic polymer P1i (i=1 to n, n is the number of sealing layers) having a Tm of less than 280°C, measured according to ISO 11357-3:2013, the at least one thermoplastic polymer of each sealing layer may be the same or different, and at least one of the composite reinforcing layers consists of a fibrous material in the form of continuous fibers impregnated with a composition comprising mainly at least one thermoplastic polymer P2j (j=1 to m, m is the number of reinforcing layers), the thermoplastic polymer P2j having a Tg, measured according to ISO 11357-3:2013, higher than the maximum use temperature (Tu) of the structure, Tg≧Tu+20°C, Tu being higher than 50°C; Gas transport or gas storage excludes hydrogen, and excludes multi-layer structures selected from reservoirs, pipes, or tubes for transporting or storing hydrogen; the polymer P1i is a polyamide, the polymer P2j is a polyamide, each polymer P1i of each sealing layer is partially or completely miscible with each polymer P1i of the layer adjacent thereto; each polymer P2j of each reinforcing layer is partially or completely miscible with each polymer P2j of the layer adjacent thereto; and polymer P21 is partially or completely miscible with polymer P11 adjacent thereto; The complete or partial miscibility of the polymers is defined by the difference in the glass transition temperatures of the two resins in the mixture relative to the difference in the glass transition temperatures of the two resins before mixing, whereby complete miscibility is achieved when the difference is equal to 0, and partial miscibility is achieved when the difference is less than 30% in absolute value and is different from 0. Multilayer structure.

2. 10. The multi-layer structure of claim 1, wherein each sealing layer comprises the same type of polymer.

3. 10. The multi-layer structure of claim 1, wherein each reinforcing layer comprises the same type of polymer.

4. 4. A multilayer structure according to claim 2 or 3, characterized in that each sealing layer comprises the same type of polymer and each reinforcing layer comprises the same type of polymer.

5. 10. The multi-layer structure of claim 1, comprising a single sealing layer and a single reinforcing layer.

6. 6. A multilayer structure according to any one of claims 1 to 5, characterized in that the structure is a flexible pipe.

7. 7. A multilayer structure according to any one of claims 1 to 6, characterized in that the composition comprising the polymers P1i and P2j also contains an additive that enables them to absorb radiation for welding.

8. 8. A multilayer structure according to claim 1, characterized in that the composition comprising the polymer P2j is transparent to the welding radiation.

9. 9. A multilayer structure according to claim 7 or 8, characterized in that the welding is carried out by a system selected from laser, IR heating or induction heating.

10. 10. Multilayer structure according to any one of claims 1 to 9, characterized in that the polymer P1i is a long-chain aliphatic polyamide or a semi-aromatic polyamide.

11. 10. A multilayer structure according to any one of claims 1 to 9, characterized in that the polymer P2j is a semi-aromatic polyamide.

12. 12. A multilayer structure according to any one of claims 1 to 11, characterized in that the polymers P1i are long-chain aliphatic or semi-aromatic polyamides and the polymers P2j are semi-aromatic polyamides.

13. 13. A multilayer structure according to any one of claims 1 to 12, characterized in that the structure further comprises a metallic carcass located within the sealing layer.

14. 14. The multilayer structure of any one of claims 1 to 13, wherein the structure further comprises at least one outer layer, said layer being the outermost layer of the multilayer structure.

15. 15. A multilayer structure according to any one of the preceding claims, characterized in that the fibrous material is selected from glass fibres, carbon fibres, basalt fibres and basalt-based fibres.

16. 16. A method for manufacturing a multilayer structure as defined in any one of claims 1 to 15, characterized in that it comprises the step of welding a reinforcing layer as defined in claim 1 to a sealing layer as defined in claim 1.

17. 17. The method of claim 16, wherein the welding step is performed by a system selected from laser, infrared heating or induction heating.

18. 18. A method according to claim 16 or 17, characterized in that it comprises the steps of extruding the sealing layer onto a metal carcass and welding a reinforcing layer to the sealing layer.

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