Multilayer assembly

Cross-Reference to Related Application

[0001] This application claims priority to European application No. 17201499.5 filed November 14, 2017, the whole content of this application being incorporated herein by reference for all purposes.

Technical Field

[0002] The present invention pertains to a multilayer assembly, to a process for the manufacture of said multilayer assembly, to a pipe comprising said multilayer assembly and to uses of said multilayer assembly or pipe in various applications.

Background Art

[0003] Off-shore pipelines, used to pump oil and gas ashore from off-shore

drilling rigs and terminals, are required to be capable of withstanding very high internal pressures and temperatures and are therefore typically made of metals such as iron and steel.

[0004] However, among major issues encountered with metal pipelines in

general, and on-shore and off-shore pipelines in particular, is the problem of corrosion due to the severe environment, which causes a deterioration of the material and, as a consequence, reduces its thermal and chemical resistance.

[0005] Thus, in the development of metal pipelines and other oil and gas recovery shaped parts, the selection of appropriate coating materials is of ultimate importance for conferring to these pipeline and shaped parts some critical properties in order to resist the extreme conditions associated with the above mentioned severe operating conditions of high temperature, harsh chemicals and other extreme conditions.

[0006] In this field, hence, polyaryletherketone (PAEK) polymers could be

regarded as polymeric materials which could protect as coatings the said parts, as they are known for their exceptional balance of technical properties, namely high melting point, good thermal stability, good stiffness and strength, good toughness and really excellent chemical resistance.

[0007] However, polyaryletherketone have been generally shown low adhesion to metal substrates, so that alternative solutions for adhering

polyaryletherketone to metal substrates have to be considered, so as to ensure that, despite harsh conditions of high temperature and/or pressure, which coated metal pipelines are subjected to, in particular in the oil and gas industry, the adhesion of the polyaryletherketone coating to the metal substrate is not adversely affected.

[0008] In particular, solutions aimed at avoiding disbondment of coated layers are required; in the domain of metal parts for oil and gas, disbondment is generally understood to be caused by permeation of moisture or oxygen through the coating layer, which may cause embrittlement and detachment of the coating from the metal substrate, resulting in an increased corrosion of the same.

[0009] WO 2014/018530 30/01/2014 is directed to certain anti-wear coatings for compressor wear surfaces, said anti-wear coating including substantially PEEK and additives, whereas according to certain embodiments, a PAI primer layer may be applied onto the substrate, before proceeding with the application of PEEK-based layer by powder coating.

[0010] WO 2014/198684 (SOLVAY SPECIALTY POLYMERS USA ) 18/12/2014 is directed to certain improved mobile electronic parts, comprising a shaped metal part, coated with at least one polymer selected from a polyamide-imide polymer and a poly(ethersulfone) polymer, said coated part being overmolded (notably by injection molding) with at least one thermoplastic polymer, which may be a poly(aryletherketone).

Summary of invention

[0011] It has been now surprisingly found that the multilayer assembly of the

invention advantageously withstand severe environment conditions and successfully exhibits outstanding interlayer adhesion properties, while maintaining good anti-corrosion properties and good thermal insulation properties, being hence particularly adapted to use in Oil&Gas domain. [0012] In a first instance, the present invention pertains to a multilayer assembly [assembly (ML)] comprising:

- a substrate, said substrate having a first surface and a second surface,

- a layer [layer (L1)] consisting of a composition [composition (C1 )], said composition comprising:

(i) at least one polyamideimide polymer [polymer (PAI)], in an amount of at least 5 % wt, with respect to the total weight of composition (C1);

(ii) optionally at least one first poly(aryl ether ketone) [polymer (PAEK)], in an amount of at most 60 % wt, with respect to the total weight of composition (C1), and

(iii) optionally at least one aromatic sulfone polymer [polymer (SP)];

said layer (L1) having a first surface and a second surface, wherein the first surface of said layer (L1) is at least partially adhered to at least one of the first surface and the second surface of the substrate, and

- a layer [layer (L2)] consisting of a composition [composition (C2)], said composition (C2) comprising at least one second poly(aryl ether ketone) [polymer (PAEK)], in an amount of at least 70 % wt,

said layer (L2) having a first surface and a second surface, wherein the first surface of said layer (L2) is at least partially adhered to the second surface of said layer (L1).

[0013] The substrate

[0014] The nature of the substrate is not particularly limited. Plastic, glass, wood, composite substrates may be used, although preferred embodiments are those wherein the substrate is a metal substrate.

[0015] The metal substrate which can be used in this invention may be any of those metal materials which are generally used in various apparatuses, appliances and instruments, and the metal substrate is not limited in particular.

[0016] Suitable metal substrates include for example, structural materials,

electrically conductive materials, valve metals with corrosion resistance such as titanium, tantalum, zirconium and niobium, alloys composed mainly, e.g., containing more than about 50% by weight, of these valve metals, e.g. Ti-Ta alloys, Ti-Ta-Nb alloys, Ti-Ta-Zr alloys, Ti-Pd alloys, etc., and lower-cost metal materials with good workability, such as iron, nickel, cobalt, copper or alloys composed mainly, e.g., containing more than about 50% by weight, of these metals, e.g., carbon steel, stainless steel, Ni-Cu alloys, brass, etc.

[0017] Low-melting metals such as aluminium, magnesium and lead can also be used.

[0018] Metal substrate may be solely constituted by an individual metallic material (be it a metal in its zero oxidation state, or an alloy of metals in their zero oxidation state, or a composition including one or more than one metals in their zero oxidation state) or may comprise a superficial anti-corrosion coating, such as e.g. anodized layers or other metal coating layers.

[0019] Anodized layers are created on the metal substrate through an

electrochemical process that converts the surface of the metal substrate into durable, corrosion-resistant, anodic oxide finish. Aluminum is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized. So, metal substrates of Aluminum, Magnesium, Titanium may comprise anodized surfaces.

[0020] Anodizing is accomplished by immersing the metal support into an acid electrolyte bath and passing an electric current through the medium. A cathode is mounted to the inside of the anodizing tank; the metal support acts as an anode, so that oxygen ions are released from the electrolyte to combine with the metal atoms at the surface of the metal support being anodized.

[0021] Otherwise, suitable metals which can be coated on the surface of the

metal substrate are any of those metals which have excellent corrosion resistance and can be alloyed with the metal substrate. Suitable coating metals include tantalum, zirconium, niobium, titanium, molybdenum, tungsten, vanadium, chromium, nickel, silicon, and alloys composed mainly of these metals.

[0022] Generally, the metal substrate is a steel substrate, generally a stainless steel or carbon steel substrate. [0023] The substrate may have any shape; e.g. it may be under the form of a wire, a sheet or film or may have a different three-dimensional shape. E.g. it may have a tubular shape.

[0024] The polymer (PAI)

[0025] To the purpose of the present invention, the term“aromatic polyamide- imide polymer [polymer (PAI)]” is intended to denote any polymer comprising more than 50% by moles of recurring units comprising at least one aromatic ring, at least one imide group, as such and/or in its amic acid form, and at least one amide group which is not included in the amic acid form of an imide group [recurring units (RPAI)].

[0026] The recurring units (RPAI) are advantageously selected from the group consisting of:

(amic acid form)

(imide form)

wherein:

Ar is a trivalent aromatic group; typically Ar is selected from the group consisting of the following

structures:

and corresponding optionally substituted structures, with X being -O-, - C(O)-, -CH2-, -C(CF3)2-, -(CF2) _n -, with n being an integer from 1 to 5;

R is a divalent aromatic group; typically R is selected from the group consisting of the following structures:

and corresponding optionally substituted structures, with Y being -0-, -S- , -SO2-, -CH2-, -C(O)-, -C(CF3)2-, -(CF2) _n , n being an integer from 0 to 5.

[0027] Preferably, the polymer (PAI) comprises more than 50% by moles of

recurring units (R _PAI ) comprising an imide group wherein the imide group is present as such, like in recurring units (Rp _Ai -a), and/or in its amic acid form, like in recurring units (Rp _Ai -b).

[0028] Recurring units (R _PAI ) are preferably selected from recurring units (I), (m) and (n), in their amide-imide (a) or amide-amic acid (b) forms:

wherein the attachment of the two amide groups to the aromatic ring as shown in (l-b) will be understood to represent the 1 ,3 and the 1 ,4 polyamide-amic acid configurations;

wherein the attachment of the two amide groups to the aromatic ring as shown in (m-b) will be understood to represent the 1 ,3 and the 1 ,4 polyamide-amic acid configurations; and

(amide-imide form)

(amide-amic acid form) wherein the attachment of the two amide groups to the aromatic ring as shown in (n-b) will be understood to represent the 1 ,3 and the 1 ,4 polyamide-amic acid configurations.

[0029] Very preferably, the polymer (PAI) comprises more than 90% by moles of recurring units (RPAI). Still more preferably, it contains no recurring unit other than recurring units (RPAI). Polymers (PAI) are commercialized by Solvay Specialty Polymers USA, L.L.C. under the trademark name

TORLON ^® .

[0030] The polymer (PAEK)

[0031] As used herein, the expression“poly(aryl ether ketone)” or polymer

(PAEK)” is hereby used to denote any polymer comprising more than 50 % moles of recurring units (RPAEK) comprising a

-0-Ar’-C(=0)-Ar ^* - group, where Ar’ and Ar ^* , equal to or different from each other, are aromatic groups, the % moles being based on the total number of moles in the polymer (PAEK). The recurring units (RPAEK) are generally selected from the group consisting of units of formulae (K-A) to (K-O) below, and mixtures of two of more than two of the same:

wherein in each of formulae (K-A) to (K-O) above, each of R’, equal to or different from each other, is independently selected at each occurrence from a C1-C12 group optionally comprising one or more than one

heteroatoms; sulfonic acid and sulfonate groups; phosphonic acid and phosphonate groups; amine and quaternary ammonium groups; and each of j’, equal to or different from each other, is independently selected at each occurrence from 0 and an integer of 1 to 4, preferably j’ being equal to zero.

[0032] Each phenylene moiety of the recurring unit (RPAEK) may, independently from one another, have a 1 ,2-, a 1 ,3- or a 1 ,4-linkage to the other moieties. According to an embodiment, each phenylene moiety of the recurring unit (RPAEK), independently from one another, has a 1 ,3- or a 1 ,4-linkage to the other phenylene moieties. According to another embodiment yet, each phenylene moiety of the recurring unit (RPAEK) has a 1 ,4-linkage to the other phenylene moieties.

[0033] According to preferred embodiment’s, j’ is zero for each R’ in formulae (K- A) to (K-O) as above detailed.

[0034] According to preferred embodiment’s, the recurring units (RPAEK) are

selected from the group consisting of units of formulae (J’-A) to (J’-D):

[0035] In some embodiments, the polymer (PAEK) is a poly(ether ether ketone) [polymer (PEEK)]. As used herein, the expression“poly(ether ether ketone)” or“polymer (PEEK)” denotes any polymer of which more than 50 % moles of the recurring units (RPAEK) are recurring units of formula (K’-A): the % moles being based on the total number of moles of recurring units in the polymer (PEEK).

[0036] According to these embodiments, at least 60 % moles, at least 70 %

moles, at least 80 % moles, at least 90 % moles, at least 95 % moles, at least 99 % moles, or even substantially all recurring units (RPAEK) are recurring units (K'-A), as above detailed. Preferred polymers (PEEK) are those wherein substantially all recurring units are units of formula (K’-A), being understood that end-groups, defects and minor amounts of impurities may be present.

[0037] In other embodiments, the polymer (PAEK) is a poly(ether ketone ketone) [polymer (PEKK)]. As used herein, the expression“poly(ether ketone ketone)” or“polymer (PEKK)” denotes any polymer of which more than 50 % moles of the recurring units (RPAEK) are recurring units of formula (K’-B) and/or recurring units of formula (K”-B):

, the % moles being based on the total number of moles of recurring units in the polymer (PEKK).

[0038] According to these embodiments, at least 60 % moles, at least 70 % mole, at least 80 % moles, at least 90 % moles, at least 95 % moles, at least 99 % moles, or even substantially all of the recurring units (RPAEK) are recurring units (K’-B) or (K”-B), or preferably a combination thereof.

Preferred polymers (PEKK) are those wherein substantially all recurring units are units of formula (K’-B) and/or (K”-B), being understood that end- groups, defects and minor amounts of impurities may be present.

[0039] In yet other embodiments, the polymer (PAEK) is a poly(ether

ketone) [polymer (PEK)]. As used herein, the expression“poly(ether ketone)” and“polymer (PEK)” denotes any polymer of which more than 50 % moles of the recurring units (R _PAEK ) are recurring units of formula (K’ ■-C):

the % moles being based on the total number of moles of recurring units in the polymer (PEK).

[0040] According to these embodiments, at least 60 % moles, at least 70 % mole, at least 80 % moles, at least 90 % moles, at least 95 % moles, at least 99 % moles, or even substantially all of the recurring units (R _PAEK ) are recurring units (K’-C). Preferred polymers (PEK) are those wherein substantially all recurring units are units of formula (K’-C), being

understood that end-groups, defects and minor amounts of impurities may be present.

[0041] In some embodiments, the polymer (PAEK) is a poly(ether diphenyl ether ketone) [polymer (PEDEK)]. As used herein, the expression“poly(ether diphenyl ether ketone)” or“polymer (PEDEK)” denotes any polymer of which more than 50 % moles of the recurring units (RK) are recurring units of formula (K’-D):

the % moles being based on the total number of moles of recurring units in the polymer (PEDEK).

[0042] According to these embodiments, at least 60 % moles, at least 70 %

moles, at least 80 % moles, at least 90 % moles, at least 95 % moles, at least 99 % moles, or even substantially all recurring units (RK) are recurring units (K'-D), as above detailed. Preferred polymers (PEDEK) are those wherein substantially all recurring units are units of formula (K’-D), being understood that end-groups, defects and minor amounts of impurities may be present.

[0043] In some other embodiments, the polymer (PAEK) is a poly(ether diphenyl ether ketone)-poly(ether ether ketone) copolymer [polymer (PEEK- PEDEK)]. As used herein, the expression“poly(ether diphenyl ether ketone)-poly(ether ether ketone) copolymer” or“polymer (PEEK-PEDEK)” denotes any polymer of which more than 50 % moles of the recurring units (RK) are a mixture of recurring units of formula (K’-A) and (K’-D), in the relative molar proportions (K’-A):(K’-D) of 95:5 to 5:95, preferably of 80:20 to 20:80.

[0044] Preferably, the polymer (PAEK) exhibits a melt viscosity measured

according to ASTM D3835 at 400°C and 1000 s ^-1 using a tungsten carbide die of 0.5 x 3.175 mm of at least 0.07 kPa x s, more preferably at least 0.09 Pa x s, most preferably at least 0.12 kPa x s, and/or of at most 0.65 kPa x s, more preferably at most 0.55 kPa-s, more preferably at most 0.50 kPa x s, most preferably at most 0.45 kPa x s.

[0045] According to a preferred embodiment, the PAEK is PEEK. PEEK is notably commercially available as KetaSpire® PEEK from Solvay Specialty Polymers USA, LLC.

[0046] The polymer (SP)

[0047] For the purpose of the invention, the term“aromatic sulfone polymer

[polymer (SP)]” is intended to denote any polymer wherein at least 50% by moles of the recurring units thereof comprise at least one group of formula (SP) [recurring units (RSP)]:

-Ar-S0 ₂ -Ar’- formula (SP)

wherein Ar and Ar’, equal to or different from each other, are aromatic groups.

[0048] Recurring units (RSP) are typically of formula:

-Ar ¹ -(T’-Ar ² ) _n -0-Ar ³ -S0 ₂ -[Ar ⁴ -(T-Ar ² ) _n -S0 ₂ ] _m -Ar ⁵ -0- wherein:

- Ar ¹ , Ar ² , Ar ³ , Ar ⁴ , and Ar ⁵ , equal to or different from each other and at each occurrence, are independently aromatic mono- or polynuclear groups;

- T and T, equal to or different from each other and at each occurrence, is independently a bond or a divalent group optionally comprising one or more than one heteroatom; preferably T’ is selected from the group consisting of a bond, -CH2-, -C(O)-, -C(CH3)2-, -C(CF3)2-, -C(=CCl2)-, -SO2- -C(CH ₃ )(CH ₂ CH ₂ COOH)-, and a group of formula: ; and preferably T is selected from the group consisting of a bond, -CH2-, -C(O)-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -C(=CCI ₂ )-, -C(CH ₃ )(CH ₂ CH ₂ COOH)-, and a group of

formula: ;

- n and m, equal to or different from each other, are independently zero or an integer of 1 to 5.

[0049] Recurring units (RSP) may be notably selected from the group consisting of those of formulae (S-A) to (S-D) herein below:

wherein:

- each of R’, equal to or different from each other, is selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium;

- j’ is zero or is an integer from 0 to 4;

- T and T, equal to or different from each other are a bond or a divalent group optionally comprising one or more than one heteroatom; preferably T’ is selected from the group consisting of a bond, -CH2-, -C(O)-, -C(CH ₃ ) ₂ - , -C(CF ₃ ) ₂ -, -C(=CCI ₂ )-, -C(CH ₃ )(CH ₂ CH ₂ COOH)-, -SO2-, and a group of

formula: ; preferably T is selected from the group consisting of a bond, -CH ₂ -, -C(O)-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -C(=CCI ₂ )-, -

C(CH ₃ )(CH ₂ CH ₂ COOH)-, and a group of formula:

[0050] The polymer (SP) typically has a glass transition temperature of

advantageously at least 150°C, preferably at least 160°C, more preferably at least 175°C.

[0051] In a first preferred embodiment of the invention, at least 50% by moles of the recurring units of the polymer (SP) are recurring units (RSP-I ), in their imide form (RSP-I -A) and/or amic acid forms [(RSP-I -B) and (RSP-I -C)] :

wherein:

the denotes isomerism so that in any recurring unit the groups to which the arrows point may exist as shown or in an interchanged position;

Ar” is selected from the group consisting of:

and corresponding substituted structures, with Y being -0-, -C(O)-, - (ChteV, -C(CF3)2-, -(CF2) _n -, wherein n is an integer from 1 to 5, and mixtures thereof.

[0052] In a second preferred embodiment of the invention, at least 50% by moles of the recurring units of the polymer (SP) are recurring units (Rsp-2) and/or recurring units (Rsp-3):

wherein:

Q and Ar ^* , equal to or different from each other and at each occurrence, are independently a divalent aromatic group; preferably Ar ^* and Q, equal to or different from each other and at each occurrence, are independently selected from the group consisting of the following structures:

and corresponding substituted structures, with Y being -0-, -CH=CH-, - CºC-, -S-, -C(O)-, -(CH ₂ ) _n -, -C(CF ₃ )2-, -C(CH ₃ )2-, -SO2-, -(CF ₂ ) _n -, wherein n is an integer from 1 to 5 and mixtures thereof; and mixtures thereof.

[0053] Recurring units (Rsp-2) are preferably selected from the group consisting of:

and mixtures thereof.

[0054] Recurring units (RS _P -3) are preferably selected from the group consisting of:

and mixtures thereof.

[0055] Polymers (SP) according to the second preferred embodiment of the

invention comprises at least 50% by moles, preferably at least 70% by moles, more preferably at least 75% by moles of recurring units (Rsp-2) and/or (Rsp-3), still more preferably, it contains no recurring unit other than recurring units (Rsp-2) and/or (Rsp-3). [0056] Good results have been obtained with polymers (SP) comprising recurring units (ii) (polybiphenyldisulfone, hereinafter), with polymers (SP) comprising recurring units (j) (polyphenylsulfone or polymer (PPSU), hereinafter), with polymers (SP) comprising recurring units (jj)

(polyetherethersulfone, hereinafter), with polymers (SP) comprising recurring units (jjj) and, optionally, in addition, recurring units (jjj)

(polyethersulfone or polymer (PES), hereinafter), and with polymers (SP) comprising recurring units (jv) and, optionally in addition, recurring units (jj) (polysulfone, or [polymer (PSU)] hereinafter).

[0057] Polyphenylsulfone [polymer (PPSU)] is notably commercially available under the trademark name RADEL ^® R PPSU from Solvay Specialty Polymers USA, L.L.C.

[0058] Polysulfone [polymer (PSU)] is notably commercially available under the trademark name UDEL ^® PSF from Solvay Specialty Polymers USA, L.L.C.

[0059] Polyethersulfone [polymer (PES)] is notably commercially available under the trademark name RADEL ^® A PES or as VIRANTAGE ^® r-PES from Solvay Specialty Polymers USA, L.L.C.

[0060] The composition (C1)

[0061] As said, the composition (C1) comprises at least one polymer (PAI) in an amount of at least 5 %wt, optionally at least one polymer (PAEK) in an amount of at most 60 %wt, with respect to the total weight of composition (C1).

[0062] The composition (C1) may comprise at least one aromatic sulfone polymer [polymer (SP)], as above detailed. The amount of polymer (SP) is not particularly critical; when used, it will be present in composition (C1) in an amount of at least 1 %wt, preferably at least 3 wt%, more preferably at least 5 %wt, with respect to the total weight of composition (C1).

Preferably, when the composition (C1) comprises a polymer (PAEK), as above detailed, it also comprises at least aromatic sulfone polymer

[polymer (SP)].

[0063] According to a first embodiment, the composition (C1) comprises at least one polymer (PAI), at least one polymer (PAEK), and at least one polymer (SP). [0064] According to this embodiment, preferred compositions (C1) are those comprising:

- from 1 to 60 % wt, preferably from 10 to 50 % wt of at least one polymer (PAEK), preferably a polymer (PEEK), as above detailed.

- from 10 to 50 % wt, preferably from 12 to 45 % wt of at least one polymer (PAI); and

- from 10 to 55 % wt, preferably from 15 to 45 % wt of at least one polymer (PS), preferably a polymer (PES), as above detailed.

[0065] According to a second embodiment, the composition (C1) does not

comprise any polymer (PAEK). According to this embodiment, the composition (C1) comprises said polymer (PAI) in an amount of

advantageously at least 10 % wt, preferably at least 20 %wt, more preferably in an amount of at least 30 % wt, even more preferably in an amount of at least 50 % wt, still more preferably in an amount of at least 70 % wt. The composition (C1) according to this second embodiment may comprise one polymer (SP); if the composition (C1) according to this embodiment comprises polymer (SP), the weight ratio between polymer (PS) and polymer (PAI) is generally comprised between 4:1 to 1 :4.

Particularly good results were obtained when composition (C1) comprised polymer (PAI) as sole aromatic polymer ingredient, and even better with composition (C1) essentially consisting of polymer (PAI).

[0066] The composition (C1), in general, may further comprise at least one

reinforcing filler.

[0067] In the present invention, the term "reinforcing filler" is intended to denote, in particular, a material added to a polymer composition to improve its properties, such as stiffness, tensile strength, impact resistance and dimensional stability, and/or to reduce the cost. By appropriately selecting these materials, not only the economics but also other properties such as processing and mechanical behaviour can be improved. Although these fillers retain their inherent characteristics, very significant differences are often observed depending on the molecular weight, compounding technique and the presence of other additives in the formulation.

Therefore, once the basic property requirements are established, the optimum type and the loading level of the filler for the balance between cost and performance must be determined.

[0068] Reinforcing fillers may be organic materials or may be inorganic

compounds. From morphological perspective, they may be notably under the form of particulate reinforcing filler or maybe in the form of fibrous reinforcing filler.

[0069] A fibrous reinforcing filler is a material having length, width and thickness, wherein the average length is significantly larger than both the width and thickness. Preferably, such a material has an aspect ratio, defined as the average ratio between the length and the smallest of the width and thickness of at least 5. Preferably, the aspect ratio of the fibrous reinforcing filler is at least 10, more preferably at least 20, still more preferably at least 50. Conversely, the particulate fillers have an aspect ratio of at most 5, preferably at most 2, and their shape is hence, although possibly irregular, not characterized by a predominant dimension.

[0070] Preferably, the reinforcing filler is selected from mineral fillers, such as talc, mica, kaolin, calcium carbonate, calcium silicate, magnesium carbonate; glass fibers; carbon fibers, boron carbide fibers; wollastonite; silicon carbide fibers; boron fibers, graphene, carbon nanotubes (CNT), and the like. Most preferably, the reinforcing filler is glass fiber, preferably chopped glass fiber, which may be circular glass fibers or flat glass fibers, or carbon fiber, preferably chopped carbon fibers.

[0071] Should the composition (C1) further comprise at least one filler, said

composition (C1) typically comprises at least one filler in an amount of from 0.5% to 25% by weight, preferably from 1 % to 20% by weight, with respect to the total weight of the composition (C1).

[0072] Composition (C1) may comprise at least one pigment, preferably selected from the group consisting of titanium dioxide which is notably available form Whittaker, Clark & Daniels, South Plainfield, New Jersey, USA; Artie blue #3, Topaz blue #9, Olympic blue #190, Kingfisher blue #211 , Ensign blue #214, Russet brown #24, Walnut brown #10, Golden brown #19, Chocolate brown #20, Ironstone brown #39, Honey yellow #29, Sherwood green #5, and Jet black #1 available from Shepherd Color Company, Cincinnati, Ohio, USA; black F-2302, blue V-5200, turquoise F-5686, green F-5687, brown F-6109, buff F-6115, chestnut brown V-9186, and yellow V-9404 available from Ferro Corp., Cleveland, Ohio, USA and METEOR ^® pigments available from Engelhard Industries, Edison, New Jersey, USA.

[0073] Further, additional additives of polymer (PAI), and where applicable,

polymer (PAEK) and polymer (SP) may be included in the composition (C1), generally in an amount not exceeding 3 % wt, preferably 2 % wt, more preferably 1 % wt, with respect to the total weight of composition (C1).

[0074] The layer (L1) typically has a thickness of at least 5 pm, preferably at least 7 pm, more preferably at least 8 pm, and/or of advantageously at most 80 pm, preferably at most 75 pm, more preferably at most 70 pm.

[0075] The composition (C2)

[0076] As said, composition (C2) comprises at least one second poly(aryl ether ketone) [polymer (PAEK)], in an amount of at least 60 % wt,

[0077] When composition (C1) includes a first polymer (PAEK), at least one of second polymer (PAEK) of composition (C2) may be identical to said first polymer (PAEK) or may be different from the same. In particular, the first polymer (PAEK) may comprise same or different recurring units as second polymer (PAEK), or first and second polymer (PAEK) may differ because, for instance, of molecular weight or other structural features.

[0078] The composition (C2) comprises polymer (PAEK) in an amount of at least 60 %wt, with respect to the total weight of composition (C2), that is to say that polymer (PAEK) is the major ingredient of the said composition (C2).

[0079] Minor amount of polymers, in particular aromatic polycondensation

polymers, other than polymer (PAEK) may be present in minor amount on said composition. For instance, a polymer (PS), as above detailed, and more particularly a polymer (PPSU), as detailed above, can be present in composition (C2).

[0080] Should the composition (C2) comprises one aromatic polycondensation polymer different from polymer (PAEK), it generally comprises such aromatic polycondensation polymer (e.g. polymer (PPSU)) in an amount of at most 40% wt, preferably in an amount of at most 38 % wt.

[0081] Good results have been obtained when the composition (C2) comprised no polymer ingredient other than polymer (PAEK).

[0082] Composition (C2) may comprise at least one reinforcing filler, as detailed above. Should the composition (C2) further comprise at least one reinforcing filler, said composition (C2) typically comprises at least one filler in an amount of from 5% to 30% by weight, preferably from 10% to 30% by weight, with respect to the total weight of the composition (C2).

[0083] Similarly, composition (C2) may comprise at least one pigment, as above detailed, and/or at least one additive of polymer (PAEK), as above detailed.

[0084] All features described above for the reinforcing filler, pigment and additive, in connection with composition (C1) are also applicable to the reinforcing filler of the composition (C2).

[0085] Good results have been obtained when the composition (C2) comprised more than 80 % wt, preferably more than 90 % wt of polymer (PAEK) (preferably of polymer (PEEK)), as above detailed. Very good results have been obtained with a composition (C2) essentially consisting of polymer (PAEK), as above detailed, most preferably of polymer (PEEK), as above detailed. Other minor ingredients, like stabilizers, anti-oxidants, pigments, flow-modifiers, etc. may be present in minor amounts (e.g. less than 5 % wt, preferably less than 3 % wt, more preferably less than 1 % wt) in the compositions (C2) essentially consisting of polymer (PAEK) as above detailed, without these ingredients substantially modifying properties of composition (C2).

[0086] The layer (L2) typically has a thickness of at least 5 pm, preferably at least 10 pm, more preferably at least 15 pm, and/or of advantageously at most 500 pm, preferably at most 350 pm, more preferably at most 300 pm.

[0087] The assembly (ML)

[0088] The multilayer assembly of the invention may further comprise a layer

[layer (L3)] consisting of a composition [composition (C3)], said layer (L3) having a first surface and a second surface, wherein the first surface of said layer (L3) is at least partially adhered to the second surface of said layer (L2).

[0089] The choice of composition (C3) is not particularly critical, and will depend upon the target function required from layer (L3).

[0090] Depending upon the“finish” required, composition (C3) may be formed of polymer materials conferring thermal insulation, brilliance, scratch resistance, friction and wear properties, chemical resistance, etc., or any combination of the foregoing.

[0091] Method of making a multilayer assembly

[0092] In a second instance, the present invention pertains to a method for the manufacture of a multilayer assembly, said process comprising:

(i) providing a substrate, as detailed above, said substrate having a first surface and a second surface;

(ii) applying on at least a part of at least one of said surfaces a liquid composition [composition (C1 _L )], so as to obtain a wet layer on said surface and

drying the said wet layer so as to obtain a coating layer [layer (LT)] on said surface,

whereas said composition (C1 _L ) comprises:

- at least one liquid medium [medium (L)];

- at least one polyamideimide polymer [polymer (PAI)], as described above;

- optionally at least one first poly(aryl ether ketone) [polymer (PAEK)], as described above; and

- optionally at least one aromatic sulfone polymer [polymer (SP)], as described above; and

(iii) forming a layer (L2) as defined above onto the layer (LT) as provided in step (ii).

[0093] All features described above for the different elements of the multilayer assembly are also applicable to the method as detailed above.

[0094] In step (i) of the method of the invention, the substrate may be:

(i-a) cleaned using a suitable solvent, preferably an alcohol or an inorganic solvent, and/or (i-b) treated by any of abrasive blasting techniques including, but not limited to, wet abrasive blasting, hydro-blasting and micro-abrasive blasting using either an organic solvent or a mineral solvent, such as for example HsP0 ₄ .

[0095] The liquid medium

[0096] For the purpose of the present invention, the term“liquid medium [medium (L)]” is intended to denote a medium comprising one or more compounds in liquid state at 20°C under atmospheric pressure.

[0097] The liquid medium comprises generally one or more than one organic

solvent. The medium (L) typically comprises one or more organic solvents selected from the group consisting of diesters of formula (Ide), esteramides of formula (l _ea ) and diamides of formula (Ida):

R ¹ 0(0)C-Z _de -C(0)0R ² (Ide)

R ³ 0(0)C-Zea-C(0)NR ⁴ R ⁵ (lea)

R ⁵ R ⁴ N(0)C-Z _da -C(0)NR ⁴ R ⁵ (l _da )

wherein:

- R ¹ and R ² , equal to or different from each other, are independently selected from the group consisting of C1-C3 hydrocarbon groups,

- R ³ is selected from the group consisting of C1-C20 hydrocarbon groups, and

- R ⁴ and R ⁵ , equal to or different from each other, are independently selected from the group consisting of hydrogen and C1-C36 hydrocarbon groups, optionally substituted, being understood that R ⁴ and R ⁵ might be part of a cyclic moiety including the nitrogen atom to which they are bound, said cyclic moiety being optionally substituted and/or optionally comprising one or more heteroatoms, and mixtures thereof, and

- Zde, Zea and Zda, equal to or different from each other, are independently linear or branched C ₂ -C ₁₀ divalent alkylene groups.

[0098] The medium (L) typically comprises a total amount of one or more organic solvents selected from the group consisting of diesters of formula (Ide), esteramides of formula (l _ea ) and diamides of formula (Ida) as defined above of at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, with respect to the total weight of the medium (L).

[0099] In formula (I _de ), R ¹ and R ² , equal to or different from each other, are

preferably independently selected from the group consisting of C1-C3 alkyl groups such as methyl, ethyl and n-propyl groups, more preferably being methyl groups.

[0100] In formula (l _ea ), R ³ is preferably selected from the group consisting of C1- C20 alkyl groups.

[0101] In formulae (l _ea ) and (l _da ), R ⁴ and R ⁵ , equal to or different from each other, are preferably independently selected from the group consisting of C1-C20 alkyl, Ci-C2o aryl, Ci-C2o alkyaryl and C1-C20 arylalkyl groups, all said groups optionally comprising one or more substituents, optionally comprising one or more heteroatoms, and cyclic moieties comprising both R ⁴ and R ⁵ and the nitrogen atom to which they are bound, said cyclic moieties optionally comprising one or more heteroatoms such as oxygen atoms or additional nitrogen atoms.

[0102] The expression“Ci-C2o alkyl” is used according to its usual meaning and it encompasses notably linear, cyclic, branched saturated hydrocarbon groups having from 1 to 20 carbon atoms, preferably from 1 or 2 to 10 carbon atoms, more preferably from 1 to 3 carbon atoms.

[0103] The expression“Ci-C2o aryl” is used according to its usual meaning and it encompasses notably aromatic mono- or poly-cyclic groups, preferably mono- or bi-cyclic groups, comprising from 6 to 12 carbon atoms, preferably phenyl or naphthyl groups.

[0104] The expression“Ci-C2o arylalkyl” is used according to its usual meaning and it encompasses linear, branched or cyclic saturated hydrocarbon groups comprising, as substituent, one or more aromatic mono- or poly- cyclic groups such as benzyl groups.

[0105] The expression“Ci-C2o alkylaryl” is used according to its usual meaning and it encompasses aromatic mono- or poly-cyclic groups comprising, as substituent, one or more alkyl groups such as linear, cyclic, branched saturated hydrocarbon chains having from 1 to 14 carbon atoms and preferably from 1 or 2 to 10 carbon atoms. [0106] In formula (l _ea ), R ³ is more preferably selected from the group consisting of methyl, ethyl, hydroxyethyl, n-propyl, isopropyl, n-butyl, isobutyl, terbutyl, n-pentyl, isopentyl, n-hexyl and cyclohexyl groups, most preferably from the group consisting of methyl, ethyl and hydroxyethyl groups.

[0107] According to a first embodiment of the invention, Zde in formula (Ide), Z _ea in formula (l _ea ) and Zd _a in formula (ld _a ) are branched C2-C10 divalent alkylene groups, preferably branched C3-C6 divalent alkylene groups.

[0108] According to this first embodiment of the invention, Zde in formula (Ide), Z _ea in formula (l _ea ) and Zd _a in formula (ld _a ) are preferably selected from the group consisting of:

- ZMG groups of formula -CH(CH ₃ )-CH ₂ -CH ₂ - (MG _a ) or -CH ₂ -CH ₂ -CH(CH ₃ )- (MG _b ),

- ZES groups of formula -CH(C ₂ H ₅ )-CH ₂ - (ES _a ) or -CH ₂ -CH(C ₂ H ₅ )- (ES _b ), and

- mixtures thereof.

[0109] According to a first variant of this first embodiment of the invention, the medium (L) comprises:

(a’) at least one diester of formula (I’de), at least one diester of formula (I” de) and, optionally, at least one diester of formula (l’”de), or

(b’) at least one esteramide of formula (l’ _ea ), at least one esteramide of formula (l” _ea ) and, optionally, at least one esteramide of formula (l”’ _ea ), or

(o’) at least one esteramide of formula (l’ _ea ), at least one esteramide of formula (l” _ea ), at least one diamide of formula (l'd _a ), at least one diamide of formula (l”d _a ) and, optionally, at least one esteramide of formula (l’”e _a ) and/or at least one diamide of formula (l’”d _a ), or

(d’) combinations of (a’) and/or (b’) and/or (o’),

wherein:

- (I’de) is R ¹ -0(0)C-Z _MG -C(0)0-R ²

- (I’ea) is R ³ -0(0)C-ZMG-C(0)NR ⁴ R ⁵

- (I’ _da ) is R ⁵ R ⁴ N(0)C-Z _MG -C(0)NR ⁴ R ⁵

- (I ’de) is R ¹ -0(0)C-ZES-C(0)0-R ²

- (I” _ea ) is R ³ -0(0)C-Z _ES -C(0)NR ⁴ R ⁵

- (I” _da ) is R ⁵ R ⁴ N(0)C-Z _ES -C(0)NR ⁴ R ⁵ - (I’” _de ) is R ¹ -0(0)C-(CH ₂ ) ₄ -C(0)0-R ² and

- (I”’ea) is R ³ -0(0)C-(CH ₂ )4-C(0)NR ⁴ R ⁵

- (I’” _da ) is R ⁵ R ⁴ N(0)C-(CH ₂ ) ₄ -C(0)NR ⁴ R ⁵

wherein:

- ZMG is of formula -CH(CH ₃ )-CH ₂ -CH ₂ - (MG _a ) or -CH ₂ -CH ₂ -CH(CH ₃ )- (MG _b ),

- ZES is of formula -CH(C ₂ H ₅ )-CH ₂ - (ES _a ) or -CH ₂ -CH(C ₂ H ₅ )- (ES _b ),

- R ¹ and R ² , equal to or different from each other, are independently selected from the group consisting of Ci-C ₃ alkyl groups,

- R ³ is selected from the group consisting of Ci-C ₂ o alkyl, Ci-C ₂ o aryl, Ci- C ₂ o alkyaryl and Ci-C ₂ o arylalkyl groups, and

- R ⁴ and R ⁵ , equal to or different from each other, are independently selected from the group consisting of Ci-C ₂ o alkyl, Ci-C ₂ o aryl, Ci-C ₂ o alkyaryl, Ci-C ₂ o arylalkyl groups, all said groups optionally comprising one or more substituents, optionally having one or more heteroatoms, and cyclic moieties comprising both R ⁴ and R ⁵ and the nitrogen atom to which they are bound, said cyclic moieties optionally comprising one or more heteroatoms such as oxygen atoms or additional nitrogen atoms.

[0110] In above mentioned formulae (l’ _de ), (l” _de ), (l’” _de ), (l ea), (l”ea), (l”’ea), (I da), (I” da), (l ” _d a), R ¹ , R ² and R ³ , equal to or different from each other, are preferably methyl groups, and R ⁴ and R ⁵ , equal to or different from each other, are preferably selected from the group consisting of methyl, ethyl and hydroxyethyl groups.

[0111] According to this first variant of the first embodiment of the invention, the medium (L) may comprise:

(aa’) a diester mixture consisting essentially of:

- from 70% to 95% by weight of at least one diester of formula (l’ _de ),

- from 5% to 30% by weight of at least one diester of formula (l” _de ) and

- from 0 to 10% by weight of at least one diester of formula ( ” _de ), as defined above, or

(bb’) an esteramide mixture consisting essentially of:

- from 70% to 95% by weight of at least one esteramide of formula (I’ea),

- from 5% to 30% by weight of at least one esteramide of formula (l” _ea ) and

- from 0 to 1 0% by weight of at least one esteramide of formula (T ea), as defined above, or

(cc’) a diester/esteramide/diamide mixture consisting essentially of:

- from 1.4% to 1.9% by weight of at least one diester of formula (I’de),

- from 0.1 % to 0.6% by weight of at least one diester of formula (l”de),

- from 0 to 0.2% by weight of at least one diester of formula (l”’de),

- from 70% to 95% by weight of at least one esteramide of formula (I’ea),

- from 5% to 30% by weight of at least one esteramide of formula (l”ea),

- from 0 to 10% by weight of at least one esteramide of formula (T ea),

- from 0.01 % to 10% by weight of at least one diamide of formula (I da),

- from 0.01 % to 5% by weight of at least one diamide of formula (l”da) and

- from 0 to 1 % by weight of at least one diamide of formula (l’”da), or (dd’) mixtures of (aa’) and/or (bb’)and/or (cc’), as defined above.

[0112] Non limiting examples of suitable media (L) wherein Zde in formula (Ide) and/or Z _ea in formula (l _ea ) and/or Zda in formula (Ida) are branched C2-C10 divalent alkylene groups, preferably branched C3-C6 divalent alkylene groups, include, notably, RHODIASOLV ^® IRIS solvents and

RHODIASOLV ^® POLARCLEAN solvents.

[0113] RHODIASOLV ^® IRIS solvent is a mixture consisting essentially of at least 80% by weight of H ₃ C0(0)C-CH(CH ₃ )-CH2-CH2-C(0)0CH3 and

H ₃ C0(0)C-CH(C ₂ H ₅ )-CH ₂ -C(0)0CH ₃ .

[0114] RHODIASOLV ^® POLARCLEAN solvent is a mixture consisting essentially of at least 80% by weight of H ₃ C0(0)C-CH(CH ₃ )-CH2-CH ₂ -C(0)N(CH ₃ )2 and H ₃ C0(0)C-CH(C ₂ H5)-CH2-C(0)N(CH ₃ )2.

[0115] According to a second embodiment of the invention, Zde in formula (Ide), Zea in formula (l _ea ) and Zda in formula (Ida) are linear C2-C10 divalent alkylene groups, preferably linear C ₃ -C6 divalent alkylene groups.

[0116] According to a variant of this second embodiment of the invention, the medium (L) comprises:

(a”) at least one diester of formula (l l ⁴ de), at least one diester of formula

(I l ³ de) and at least one diester of formula (l l ² de), or

(b”) at least one esteramide of formula (l l ⁴ ea), at least one esteramide of formula ( 11 ³ _ea ) and at least one esteramide of formula (l l ² ea), or

(c”) at least one esteramide of formula (l l ⁴ ea), at least one esteramide of formula ( 11 ³ _ea ) , at least one esteramide of formula (l l ² ea), at least one diamide of formula (l l ⁴ da), at least one diamide of formula (l l ³ da) and at least one diamide of formula (l l ² da), or

(d”) mixtures of (a”) and/or (b”) and/or (c”),

wherein:

- (I l ⁴ _de ) is R ¹ -OOC-(CH ₂ ) ₄ -COO-R ²

- (I l ³ de) is R ¹ -OOC-(CH ₂ ) ₃ -COO-R ²

- (I l ² _de ) is R ¹ -OOC-(CH ₂ ) ₂ -COO-R ²

- (I l ⁴ _ea ) is R ³ -00C-(CH ₂ ) ₄ -C(0)NR ⁴ R ⁵

- ( 11 ³ _ea ) is R ³ -00C-(CH ₂ ) ₃ -C(0)NR ⁴ R ⁵

- (I l ² _ea ) is R ³ -00C-(CH ₂ ) ₂ -C(0)NR ⁴ R ⁵

- (I l ⁴ _da ) is R ⁵ R ⁴ N(0)C-(CH ₂ ) ₄ -C(0)NR ⁴ R ⁵

- (I l ³ _da ) is R ⁵ R ⁴ N(0)C-(CH ₂ ) ₃ -C(0)NR ⁴ R ⁵

- (I l ² _da ) is R ⁵ R ⁴ N(0)C-(CH ₂ ) ₂ -C(0)NR ⁴ R ⁵

wherein:

- R ¹ and R ² , equal to or different from each other, are independently selected from the group consisting of Ci-C ₃ alkyl groups,

- R ³ is selected from the group consisting of Ci-C ₂ o alkyl, Ci-C ₂ o aryl, Ci- C ₂ o alkyaryl and Ci-C ₂ o arylalkyl groups, and

- R ⁴ and R ⁵ , equal to or different from each other, are independently selected from the group consisting of Ci-C ₂ o alkyl, Ci-C ₂ o aryl, Ci-C ₂ o alkyaryl, Ci-C ₂ o arylalkyl groups, all said groups optionally comprising one or more substituents, optionally having one or more heteroatoms, and cyclic moieties comprising both R ⁴ and R ⁵ and the nitrogen atom to which they are bound, said cyclic moieties optionally comprising one or more heteroatoms such as oxygen atoms or additional nitrogen atoms.

[0117] In above mentioned formulae (l l ⁴ de), (N ³ de), (N ² de), (N ⁴ ea), (N ³ ea), (N ² ea),

(I l ⁴ da), (I l ³ da), (N ² da), R ¹ , R ² and R ³ , equal to or different from each other, are preferably methyl groups, and R ⁴ and R ⁵ , equal to or different from each other, are preferably selected from the group consisting of methyl, ethyl and hydroxyethyl groups. [0118] According to certain preferred variants of this second embodiment of the invention, the medium (L) may comprise:

(aa”) a diester mixture consisting essentially of H ₃ C0(0)C-(CH ₂ ) ₄ - C(0)OCH ₃ , H ₃ C0(0)C-(CH ₂ )3-C(0)0CH ₃ and H ₃ C0(0)C-(CH ₂ ) ₂ - C(0)OCH ₃ , or

(bb”) an esteramide mixture consisting essentially of H ₃ C0(0)C-(CH ₂ ) ₄ - C(0)N(CH ₃ ) ₂ , H ₃ C0(0)C-(CH ₂ ) ₃ -C(0)N(CH ₃ ) ₂ and H ₃ C0(0)C-(CH ₂ ) ₂ - C(0)N(CH ₃ ) ₂ , or

(cc”) a diester mixture of consisting essentially of H ₅ C ₂ 0(0)C-(CH ₂ ) ₄ - C(0)OC ₂ HS, H ₅ C ₂ 0(0)C-(CH ₂ ) ₃ -C(0)0C ₂ H ₅ and H ₅ C ₂ 0(0)C-(CH ₂ ) ₂ - C(0)OC ₂ HS, or

(dd”) an esteramide mixture consisting essentially of H ₅ C ₂ 0(0)C-(CH ₂ ) ₄ - C(0)N(CH ₃ ) ₂ , H ₅ C ₂ 0(0)C-(CH ₂ ) ₃ -C(0)N(CH ₃ ) ₂ and H ₅ C ₂ 0(0)C-(CH ₂ ) ₂ - C(0)N(CH ₃ ) _2, or

(ee”) an esteramide mixture consisting essentially of H ₉ C ₄ 0(0)C-(CH ₂ ) ₄ - C(0)N(CH ₃ ) ₂ , H ₉ C ₄ 0(0)C-(CH ₂ ) ₃ -C(0)N(CH ₃ ) ₂ and H ₉ C ₄ 0(0)C-(CH ₂ ) ₂ - C(0)N(CH ₃ ) _2, or

(ff”) mixtures thereof.

[0119] An exemplary embodiment of the variant listed above under section (aa”) is a diester mixture consisting essentially of:

- from 8% to 22% by weight of H ₃ C0(0)C-(CH ₂ ) ₄ -C(0)0CH ₃ ,

- from 57% to 67% by weight of H ₃ C0(0)C-(CH ₂ ) ₃ -C(0)0CH ₃ and

- from 18% to 28% by weight of H ₃ C0(0)C-(CH ₂ ) ₂ -C(0)0CH ₃ .

[0120] Non limiting examples of suitable diester-based mixtures wherein Z _de in formula (Ide) and/or Z _ea in formula (l _ea ) and/or Zd _a in formula (ld _a ) are linear C ₂ -Cio divalent alkylene groups, preferably linear C ₃ -C6 divalent alkylene groups, include, notably, RHODIASOLV ^® RPDE solvents.

[0121] RHODIASOLV ^® RPDE solvent is a mixture consisting essentially of at least 70% by weight of H ₃ C0(0)C-(CH ₂ ) ₃ -C(0)0CH ₃ and H ₃ CO(0)C- (CH ₂ ) ₂ -C(0)0CH ₃ .

[0122] According to a third embodiment of the invention, the medium (L)

comprises:

(a’”) at least one diester of formula (Ide) and (b’”) at least one alkyl acetate of formula (l _aa ):

R ⁹ -0C(0)CH ₃ (laa)

wherein R ⁹ is a linear, branched or cyclic C3-C ₁₅ alkyl group, preferably a C6-C ₁₅ alkyl group, more preferably a C6-C ₁₃ alkyl group, even more preferably a C6-C ₁₂ alkyl group.

[0123] According to a variant of this third embodiment of the invention, the

medium (L) comprises:

(aa’”) a diester mixture consisting essentially of:

- from 70% to 95% by weight of at least one diester of formula (I’ _de ),

- from 5% to 30% by weight of at least one diester of formula (l” _de ) and

- from 0 to 10% by weight of at least one diester of formula (l’” _de ), as defined above, and

(bb’”) at least one alkyl acetate of formula (l _aa ):

R ⁹ -0C(0)CH ₃ (l _aa )

wherein R ⁹ is a linear, branched or cyclic C3-C ₁₅ alkyl group, preferably a C6-C ₁₅ alkyl group, more preferably a C6-C ₁₃ alkyl group, even more preferably a C6-C ₁₂ alkyl group.

[0124] According to a preferred variant of this third embodiment of the invention, the medium (L) comprises:

(aa’”) from 50% to 80% by weight, preferably from 60% to 80% by weight of a diester mixture consisting essentially of:

- from 70% to 95% by weight of at least one diester of formula (I’ _de ),

- from 5% to 30% by weight of at least one diester of formula (l” _de ) and

- from 0 to 10% by weight of at least one diester of formula (l’” _de ), as defined above, and

(bb’”) from 20% to 50% by weight, preferably from 20% to 40% by weight of at least one alkyl acetate of formula (l _aa ):

R ⁹ -0C(0)CH ₃ (l _aa )

wherein R ⁹ is a linear, branched or cyclic C3-C15 alkyl group, preferably a C6-C15 alkyl group, more preferably a C6-C13 alkyl group, even more preferably a C6-C12 alkyl group.

[0125] Diesters of formula (I _de ) which can be used in the composition of the

invention can be prepared notably according to the teachings of US 5688885 (DUPONT) 18/11/1997 . Esteramides of formula (l _ea ), which can be used in the composition of the invention optionally in combination with diamides of formula (Ida), can be prepared notably according to the teachings of WO 2011/154661 (RHODIA OPERATIONS) 15/12/2011 and WO 2009/092795 (RHODIA OPERATIONS) 30/07/2009 .

[0126] The medium (L) may further comprise dimethylsulfoxide (DMSO) and, optionally, at least one further organic solvent different from DMSO and from diesters of formula (Ide), esteramides of formula (l _ea ) and diamides of formula (Ida) as defined above.

[0127] Should the medium (L) comprise at least one further organic solvent

different from DMSO and from diesters of formula (Ide), esteramides of formula (l _ea ) and diamides of formula (Ida) as defined above, the weight ratio between the total amounts of organic solvents selected from the group consisting of diesters of formula (Ide), esteramides of formula (l _ea ) and diamides of formula (Ida) as defined above and DMSO is preferably from 1 :99 to 99:1 , preferably from 20:80 to 80:20, more preferably from 70:30 to 30:70.

[0128] Non limiting examples of suitable further organic solvents include, notably, the followings:

- aliphatic hydrocarbons including, more particularly, the paraffins such as, in particular, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane or cyclohexane, and naphthalene and aromatic hydrocarbons and more particularly aromatic hydrocarbons such as, in particular, benzene, toluene, xylenes, cumene, petroleum fractions composed of a mixture of alkylbenzenes,

- aliphatic or aromatic halogenated hydrocarbons including more particularly, perchlorinated hydrocarbons such as, in particular,

tetrachloroethylene, hexachloroethane; partially chlorinated hydrocarbons such as dichloromethane, chloroform, 1 ,2-dichloroethane, 1 ,1 ,1- trichloroethane, 1 ,1 ,2,2-tetrachloroethane, pentachloroethane,

trichloroethylene, 1-chlorobutane, 1 ,2-dichlorobutane,

monochlorobenzene, 1 ,2-dichlorobenzene, 1 ,3-dichlorobenzene, 1 ,4- dichlorobenzene, 1 ,2,4-trichlorobenzene or mixture of different chlorobenzenes,

- aliphatic, cycloaliphatic or aromatic ether oxides, more particularly, diethyl oxide, dipropyl oxide, diisopropyl oxide, dibutyl oxide,

methyltertiobutylether, dipentyl oxide, diisopentyl oxide, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether benzyl oxide; dioxane, tetrahydrofuran (THF),

- glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether,

- glycol ether esters such as ethylene glycol methyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate,

- alcohols such as methyl alcohol, ethyl alcohol, diacetone alcohol,

- ketones such as acetone, methylethylketone, methylisobutyl ketone, diisobutylketone, cyclohexanone, isophorone,

- linear or cyclic esters such as methyl acetoacetate, dimethyl phthalate, y- butyrolactone,

- linear or cyclic carboxamides such as N,N-dimethylacetamide (DMAC), N,N-diethylacetamide, dimethylformamide (DMF), diethylformamide or N- methyl-2-pyrrolidone (NMP),

- organic carbonates for example dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, ethylmethyl carbonate, ethylene carbonate, vinylene carbonate,

- phosphoric esters such as trimethyl phosphate, triethyl phosphate,

- ureas such as tetramethylurea, tetraethylurea.

[0129] For embodiments wherein the medium (L) comprises one or more further organic solvents, the medium (L) is preferably free from organic solvents qualified as Carcinogenic, Mutagenic or Toxic to Reproduction according to chemical safety classification (CMR solvents); more specifically, the medium (L) is advantageously substantially free from NMP, DMF and DMAC. [0130] The medium (L) is preferably free from any further organic solvent, other than DMSO and from diesters of formula (Ide), esteramides of formula (l _ea ) and diamides of formula (Ida) as defined above

[0131] Non limiting examples of other ingredients of medium (L) suitable for use in the composition (C1 _L ) include the following compounds:

- at least one rheology modifier, preferably selected from the group consisting of modified polyamides, modified urea, polyethylene waxes and organic derivatives of clays, e.g. bentonite clays;

- at least one defoaming agent, preferably selected from the group consisting of polydimethyl siloxanes, in particular modified polydimethyl siloxanes, fluorinated silicones; and

- at least one surfactant, preferably selected from the group consisting of alkyl ethoxylated alcohols and alkylphenol ethoxylated alcohols.

[0132] All other features above described in connection with composition (C1) are applicable to composition (C1 _L ), mutatis mutandis.

[0133] In particular, polymer (PAI), and, when present, polymer (SP) and polymer (PAEK) are comprised in said composition (C1 _L ) in such amount that, upon drying (causing substantial removal of volatile ingredients), their respective amounts are as described above in composition (C1).

[0134] It can be said, hence, for simplicity, that composition (C1 _L ) comprises

(preferably consists of) components of composition (C1), in amounts described above, and medium (L).

[0135] Composition (C1 L) comprises an amount of medium (L) of at least 60 % wt, preferably at least 63 % wt, more preferably at least 65 % wt, with respect to the total weight of composition (C1 L), and/or of at most 95 % wt, preferably at most 94 %wt, more preferably at least 93 % wt, with respect to the total weight of composition (C1 L).

[0136] As said, composition (C1 _L ) comprises components of composition (C1) in the amounts as above detailed for composition (C1) of layer (L1), that is to say, when measuring said amounts based on solids intended to remain in composition (C1 ) of layer (L1 ) of assembly (ML).

[0137] Step (ii) [0138] Under step (ii) of the process of the invention, the composition (C1 L) is typically applied by any suitable techniques. Roll coating, casting, spray coating may be used, depending upon the geometry of the substrate.

[0139] The wet layer so obtained is dried in step (ii); drying is carried out

advantageously for substantially removing medium (L). Drying is generally performed under heating, at a temperature of at least 35 °C, preferably at least 40°C, more preferably at least 45 °C.

[0140] Drying may be performed by exposing the wet layer to a pressure lower than atmospheric pressure; otherwise drying can be carried out at atmospheric pressure, e.g. in a ventilated oven.

[0141] As a result of drying a layer (LT) is obtained, which typically has a

thickness of at least 5 pm, preferably at least 7 pm, more preferably at least 8 pm, and/or of advantageously at most 80 pm, preferably at most 75 pm, more preferably at most 70 pm.

[0142] All features described above in connection with layer (L1) are applicable to layer (L1’).

[0143] Step (iii)

[0144] In step (iii), a layer (L2) as defined above is formed onto the layer (L1’) as provided in step (ii).

[0145] Layer (L2) consists of a composition [composition (C2)], said composition (C2) comprising at least one poly(aryl ether ketone) [polymer (PAEK)], as above detailed, in an amount of at least 70 % wt, with respect to the total weight of composition (C2).

[0146] The layer (L2) is formed by applying on the surface of layer (LT) a

composition (C2’); composition (C2’) may be under the form of a liquid composition or may be under the form of a solid composition.

[0147] Preferably, composition (C2’) is in the form of a solid composition; said solid composition advantageously comprises polymer (PAEK) under the form of particles, i.e. of discrete three-dimensional objects, which can be characterized by dimensional features through appropriate analytical techniques.

[0148] Advantageously, particles of polymer (PAEK) of the composition (C2’) possess an average particle size dso of at least 1 pm, preferably at least 3 mhh, more preferably at least 5 pm, even more preferably at least 10 pm and/or of at most 180 pm, preferably at most 150 pm, more preferably at least 120 pm.

[0149] The expression“average particle size dso” is used within the context of the present invention according to its usual meaning, i.e. is the size that 50 % in volume of the particles of the polymer (PAEK) is smaller and 50 % in volume of the particles of the polymer (PAEK) is larger.

[0150] Similarly, the expression“average particle size dio” is the size at which 10% in volume of the polymer (PAEK) is comprised of particles with a diameter less than this value; and the expression“average particle size d9o ” is the size at which 90% in volume of the polymer (PAEK) is comprised of particles with a diameter less than this value.

[0151] Particles of polymer (PAEK) of the composition of the present invention possesses an average particle size dio of at least 0.5 pm, preferably at least 1 pm, more preferably at least 2 pm and/or of at most 45 pm, preferably at most 40 pm, more preferably at least 35 pm.

[0152] Particles of polymer (PAEK) of the composition of the present invention possesses an average particle size d9o of at least 10 pm, preferably at least 12 pm, more preferably at least 15 pm and/or of at most 250 pm, preferably at most 225 pm, more preferably at least 200 pm.

[0153] The average particle size dio, dso, d9o are determined by laser light

scattering according to ISO 13320.

[0154] Polymer (PAEK) is comprised in said composition (C2’) in such amount that once composition (C2') is processed to provide for layer (L2), said layer (L2) consists of composition (C2), as described above.

[0155] This means that composition (C2’) may comprise, in addition to the

components of composition (C2), adjuvant for processing the same into a film, which may be advantageously removed during processing.

[0156] All other features described above for composition (C2) in connection with the multilayer assembly of the invention are hereby applicable mutatis mutandis.

[0157] Under step (iii), layer (L2) can be formed by a step of applying the

composition (C2’) as a solid composition, more preferably in the form of powder, followed by a step of baking said composition (C2’), so as to obtain a layer (L2).

[0158] Preferably, composition (C2’) does not comprise any additional ingredient than composition (C2), as described above.

[0159] Under step (iii), the composition (C2’) is typically applied by electrostatic powder coating.

[0160] Electrostatic powder coating is usually performed by means of an

electrostatic spray gun, which uses the principle of electrophoresis that electrically polarized particles are attracted to a grounded or oppositely charged surface.

[0161] When electrostatic powder coating is used, the skilled person will select the proper output settings depending on the nature of the composition to be applied. Good results have been obtained by working between 10 and 60 kV and between 5 mA and 40 mA.

[0162] Optionally, in order to achieve a desired thickness of the layer (L2), step (iii) may be repeated, for example two or more than two times.

[0163] When composition (C2’) is under the form of a powder, step (iii) comprises a step of baking the particles of polymer (PAEK) at a temperature of from 280°C to 450°C, preferably from 300°C to 420°C. Good results have been obtained when baking at temperatures of 350 to 400°C.

[0164] The multilayer assembly as provided in step (iii) is typically baked for a period of from 1 minute to 5 hours, preferably from 5 minutes to 30 minutes.

[0165] The pipe

[0166] The invention further pertains to a pipe comprising the assembly (ML) as above detailed.

[0167] Generally, the pipe of the invention will comprise a multilayer assembly whereas the support has a tubular shape, possessing an inner surface and an outer surface.

[0168] In the pipe of the invention, hence, the first surface of said layer (L1) may be at least partially adhered to at least one of the inner surface and the outer surface of said tubular-shaped substrate. [0169] When it is adhered to the inner surface, the pipe may further comprise at least one outer layer at least partially adhered to the outer surface.

[0170] The pipe may be notably a flexible riser, which may further comprise at least one of an outer sheath, a buoyant layer, a tensile armor, a pressure armor, an inner pipe and an interlock conduit, with the provision that the tubular-shaped substrate included in the assembly (ML) may embed any of these layers.

[0171] Otherwise, the pipe may be an umbilical hose, which may contain at least one of electrical conductor, fiber optic or other elements suitably for carrying electric power, video, and data signals between a remotely operated device and a management system. The umbilical hose may comprise the assembly (ML) under the form of a coated conductor or may alternatively comprise the assembly (ML) as a structural sheath.

[0172] Uses of the assembly (ML) and/or of the pipe

[0173] The invention further pertains to the use of the assembly (ML) and/or of the pipe as above detailed in various applications.

[0174] In particular, the invention pertains to a method for recovering oil and/or gas from a subterranean formation including using the assembly (ML) or the pipe as above detailed, said method comprising at least one of the operations selected from the group consisting of :

1. drilling at least one borehole for exploring or exploiting an oil and/or gas reservoir in a subterranean formation using at least one assembly (ML) or at least one pipe as defined above;

2. completing at least one well using at least one assembly (ML) or at least one pipe as defined above;

3. transporting oil and/or gas from an oil and/or gas reservoir in a

subterranean formation to the ground level using at least one assembly (ML) or at least one pipe as defined above.

[0175] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence. [0176] The invention will be now described in more detail with reference to the following examples whose purpose is merely illustrative and not limitative of the scope of the invention.

[0177] Raw materials

Polymer (PAI-1) is intended to denote TORLON ^® PAI AI10 polyamideimide commercially available from Solvay Specialty Polymers USA, LLC.

Solvent (S-1) is intended to denote POLARCLEAN ^® esteramide mixture consisting essentially of at least 80% by weight of H3C0(0)C-CH(CH3)- CH ₂ -CH ₂ -C(0)N(CH ₃ )2 and H ₃ C0(0)C-CH(C ₂ H ₅ )-CH ₂ -C(0)N(CH ₃ )2 commercially available from Rhodia.

Solvent (S-2) is intended to denote DMSO.

Polymer (PES-1) is intended to denote Virantage® VW10200RP PES, which is a hydroxyl-functionalized PES with a molecular weight of about 45000, commercially available from Solvay Specialty Polymers USA, LLC Polymer (PEEK-1) is KETASPIRE® PEEK KT880 under the form of powder having a dso of about 40 pm.

Polymer (PEEK-2) is KETASPIRE® PEEK KT880 under the form of powder having a dso of about 10 pm.

30C 965 is a black pigment commercially available as DYNAMIX™

BLACK 30C965 from Shepherd Color Company.

Airex 931 stands for TEGO ^® Airex 931 , which is a deaerator/defoaming agent for solvent-based coating systems, based on a fluorinated silicone commercially available from Evonik Tego Chemie GmbH.

Nubirox 106 is an anticorrosive pigment consisting in organophilized zinc phosphate-molybdate commercially available from Ferro Pigments.

Disperbyk®-161 is a wetting and dispersing additive consisting in a solution of a high molecular weight block copolymer with pigment affinic groups

commercially available from BYK.

[0178] Preparative Example 1 : Manufacture of the primer composition comprising (PES-1), (PAI-1) and (PEEK-2)

A liquid medium comprising solvents (S-1) and (S-2), as above detailed, was prepared by blending and shaking the ingredients in a bottle at a temperature comprised between 20°C and 35°C. The polymer (PES-1) and the polymer (PAI-1) were added at room temperature and solubilised in the solvent mixture through agitation on a bottle roller at a temperature comprised between 20°C and 90°C. Once complete dissolution of said polymer(s) was achieved, the other ingredients were added in the following order: Disperbyk 161 ; Airex 931 ; 30C 965 black pigment ; and Nubirox 106. Then, polymer (PEEK-2) was added to the resulting solution, and the bottle was agitated on a bottle roller for additional 10 minutes. Amounts used are specified in Table 1 below.

The resulting mixture was finally homogeneized and milled in a glass beads blender, by adding an amount of glass beads equal to the volume of the obtained mixture, and blending the resulting dispersion in a Dispermat CV3 mixer for 10 minutes. Appropriate homogeneization was checked by evaluation on grind gauge grooves so as to detect, if any, presence of aggregates/particles with dimension higher than 10 pm. In case any particle(s)/aggregate(s) of dimension higher than 10 pm was/were detected, additional grinding for 10 minutes was performed. Formulation was considered completed and well-dispersed only when after the composition was distributed with a scraper in the grooves of the grind gauge, no detected scratches or film discontinuities above 10 pm were detected.

[0179] Example 2: Manufacture of a multilayer assembly

Carbon steel substrates (15 x 4 x 0.5 cm panels) were cleaned and treated by grit blasting using aluminium oxide (10 mesh). The composition prepared in Preparative Example 1 was applied via spray coating using a gun with a die of 1.2 mm and air pressure of 2.5 bar.

The wet layer so obtained was dried under heating at a temperature of 220 °C for 10 minutes in order to evaporate the solvents. A thin layer of polymer (PEEK-1) was then applied via electrostatic powder coating; the powder coated assembly was baked in an oven at 390°C for 15 minutes. A second layer of polymer (PEEK-1) was applied as top coat via electrostatic powder coating and again baked in oven at 390°C for 15 minutes. The thickness of the complete coating was comprised between 150 and 350 pm.

[0180] Preparative Example 3: Manufacture of the primer composition comprising (PAI-1 )

[0181] A composition was prepared using the starting materials and procedure of preparative example 1 , except that polymer (PAI-1) alone was dissolved in the liquid medium, and no use was made of polymer (PES-1) nor (PEEK- 2).

[0182] Example 4: Manufacture of a multilayer assembly

[0183] The same procedure as detailed in Example 2 was also followed for the manufacture of the multilayer assembly, except that primer of Preparative Example 3 was used instead of primer of Preparative Example 1.

[0184] Comparative Example 5: monolayer PEEK coating

[0185] Carbon steel substrates (15 x 4 x 0.5 cm panels) were cleaned and treated by grit blasting using aluminium oxide (10 mesh). Then steel panels were preheated at 420°C for 15 minutes and then polymer (PEEK-1) was applied via electrostatic powder coating and baked in oven at 390°C for 15 minutes. The thickness of the complete coating was comprised between 100 and 350 pm.

[0186] Comparative Preparative Example 5: Manufacture of the primer

composition comprising (PES-1)

[0187] A comparative composition was prepared using the starting materials and procedure of preparative example 1 , except that polymer (PES-1) was dissolved in the liquid medium and no use was made of polymer (PAI-1) nor (PEEK-2).

[0188] Comparative Example 6: Manufacture of a multilayer assembly

[0189] The same procedure as detailed in Example 2 was also followed for the manufacture of the multilayer assembly, except that primer of Comparative Preparative Example 5 was used instead of primer of Preparative Example 1.

[0190] Compositions of the primer compositions are detailed in table 1 herein below:

[0191] Table 1

[0192] Evaluation of adhesion properties (including initial adhesion and after 7 days of hot water exposure)

[0193] Adhesion performances of the coatings onto the substrates were

determined via cross-cut test. The coating formed onto the substrate as detailed above was cut making two incision lines of about 20 mm long, crossing each other in the middle with an angle of about 60°. The coating in proximity of the cross point was scratched: if a continuous polymer film was detached from the substrate, the adhesion was qualified as poor. If, on the contrary, it was not possible to peel the coating, the adhesion was quoted as good. This test for assessing adhesion was performed on at least 3 coated panels shortly after completion of the coating procedure (about 1 hour).

The Hot-Wet Exposure test was performed on at least additional 3 coated panels, after having exposed the same to hot water vapour for 7 days at 75°C. Before starting the test the specimens were perforated by drilling a 3 mm diameter hole in the centre of each sample until the metal part was exposed. After 7 days, adhesion was evaluated 60 minutes after interrupting heat treatment via blade-test, by cutting, with a knife, 8 edges of at least 20 mm from the centre of the hole, such that each cut reached the metal panel. Then, the tip of a blade was inserted under the coating at the hole and the coating was chipped off, continuing until the coating showed a definitive resistance. The distance of chipping was measured from the edge of the original hole along each cut. If the medium of the distances from each edge was less than 6 mm, the adhesion was evaluated as good. Otherwise the adhesion was evaluated as poor. If the coating was completely removed from the steel, the evaluation was valued as total delamination.

[0194] Results obtained on various assemblies manufactured as above detailed are summarized in Table 2 below

[0195]

Table 3

[0196] ^* Cross-cut test measuring initial (to) adhesion to substrate; ^** Blade-test measuring adhesion to substrate after hot/wet exposure (7 days at 75°C).