EP4633936A1

EP4633936A1 - Multilayer structure and articles for the storage and transportation of gasses

Info

Publication number: EP4633936A1
Application number: EP23821655.0A
Authority: EP
Inventors: Florence Clement; Yves Vanderveken; Bryan Benson; Didier Delimoy
Original assignee: Syensqo Specialty Polymers USA LLC
Current assignee: Syensqo Specialty Polymers USA LLC
Priority date: 2022-12-14
Filing date: 2023-12-12
Publication date: 2025-10-22
Also published as: CA3276290A1; CN120359120A; WO2024126470A1; TW202436457A; KR20250126746A; JP2026508802A

Abstract

A multilayer structure suitable for the manufacture of articles, in particular pressure vessels, for the storage and transportation of gasses. The vessel is particularly adapted for the storage and transportation of compressed gasses in vehicles.

Description

MULTILAYER STRUCTURE AND ARTICLES FOR THE STORAGE AND TRANSPORTATION OF GASSES

Reference to related applications

This application claims priority to U.S. provisional application No. 63/387314 - filed December 14^th, 2022 - and to European patent application No. 23158670.2 - filed February 27^th, 2023 -, the whole content of each of these applications being incorporated herein by reference for all purposes.

Technical Field

[0001 ] The invention relates to a multilayer structure suitable for the manufacture of articles adapted for the storage and transportation of gasses, in particular of pressure vessels. The invention further relates to the articles, such as pressure vessels, comprising the multilayer structure. The invention further relates to a method for manufacturing a pressure vessel.

Background Art

[0002] Pressure vessels characterized by high gas barrier properties have been used for storing various gasses such as oxygen, carbon dioxide, nitrogen, argon, LPG (liquefied petroleum gas), methane, hydrogen, over a long period of time. Pressure vessels comprising a non-structural inner layer or liner surrounded with a structural fiber reinforced composite material for containing the fluid or gas under pressure are known. The liner acts as a barrier between the fluid or gas and the fiber reinforced composite material, thus preventing leaks and/or other degradations of the structure of the fiber reinforced composite material. The use of structural fiber reinforced composite materials comprising a thermoplastic polymer matrix is advantageous to facilitate recycling of the pressure vessel. Pressure vessels comprising a polyamide-based liner and an outer layer, which is a composite material that contains a continuous fiber and a polyamide resin impregnated into the continuous fiber, are disclosed for instance in EP3225888 A1 , EP3390016 A1 , and WO21152254 A1 .

[0003] However the need still exists to develop articles for the transport and storage of hydrogen and gasses in general, in particular pressure vessels, which combine high performance qualities in terms of impermeability to the stored gas, mechanical properties, at both low and high temperature, and high thermal degradation temperature, for ease of processing. An additional advantage for the application would be the non-flammability of the pressure vessel.

[0004] The objective of the invention is thus providing articles, such as pressure vessels, having very low permeability to gasses, such as hydrogen, and good mechanical resistance over a wide range of temperatures without requiring the use of structural layers made of metal or other nonthermoplastic polymeric materials. The objective is achieved by the multilayer structure of the invention.

Summary of invention

[0005] A first object of the invention is thus a multilayer structure comprising at least one barrier layer, [Layer (BL)], and at least one composite layer, [Layer (CL)] in contact with the at least one barrier layer wherein:

- Layer (BL) comprises a poly(arylene sulfide) polymer; and

- Layer (CL) comprises continuous reinforcing fibers and a poly(arylene sulfide) polymer.

[0006] A second object of the invention is an article for storing or transporting a gas comprising the multilayer structure of the first object. Layer (BL) represents the internal layer of the article which is in contact with the gas being stored or transported, hereinafter also referred to as “internal layer” or “liner”, while Layer (CL) represents the external layer of the article. The article may be a vessel, preferably a pressure vessel, that is a vessel for the storage of a gas under pressure.

[0007] A third object of the invention is a compressed gas in a vessel comprising the multilayer structure of the first object, wherein Layer (BL) is in contact with the compressed gas. Further objects of the invention are a method for making the vessel as well as the use of the vessel in vehicles. Description of invention

[0008] In the present application:

- any description, even though described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present disclosure;

- where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list;

- any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges as well as the endpoints of the range and equivalents;

- the indeterminate article “a” in an expression like “a poly(arylene sulfide) polymer”, is intended to mean “one or more”, or “at least one” unless indicated otherwise; and

- the use of brackets “( )” before and after names of compounds, symbols or numbers, e.g. “Layer (BL)”, “Layer (CL)”, etc... , has the mere purpose of better distinguishing that name, symbol or number from the rest of the text; thus, said parentheses could also be omitted.

[0009] A first object of the invention is a multilayer structure comprising at least one barrier layer, [Layer (BL)], and at least one composite layer, [Layer (CL)] in contact with the at least one barrier layer wherein:

- Layer (BL) comprises a poly(arylene sulfide) polymer; and

[0010] The polyfarylene sulfide) polymer

[0011] Layer (BL) and Layer (CL) comprise a poly(arylene sulfide) polymer. The poly(arylene sulfide polymer) in Layer (BL) may be the same or different from the poly(arylene sulfide) polymer used in Layer (CL). [0012] When more than one Layer (BL) is present, each Layer (BL) may comprise the same or a different poly(arylene sulfide) polymer, preferably the same poly(arylene sulfide) polymer.

[0013] When more than one Layer (CL) is present, each Layer (CL) may comprise the same or a different poly(arylene sulfide) polymer, typically the same poly(arylene sulfide) polymer.

[0014] The poly(arylene sulfide) polymer typically contains at least 50.0 mol% of a recurring unit (RPAS) having at least one aromatic ring bonded to a sulfur atom. In some embodiment, the amount of recurring unit (RPAS) is at least 60.0 mol%, at least 70.0 mol%, at least 80.0 mol%, at least 90.0 mol%, at least 95.0 mol%, at least 97.0 mol%, at least 98.0 mol%, at least 99.0 mol% or at least 99.9 mol%. As used herein, mol% is relative to the total number of recurring units in the poly(arylene sulfide) polymer, unless explicitly noted otherwise.

[0015] Recurring unit (RPAS) is represented by a formula selected from the following group of formulae:

(3), in which: - R is, at each instance, independently selected from the group consisting of a C1-C12 alkyl group, a C7-C24 alkylaryl group, a C7-C24 aralkyl group, a C6-C24 arylene group, and a Ce-C-is aryloxy group;

-T is selected from the group consisting of a bond, -CO-, -SO2-, -O-, - C(CHS)2, phenyl and -CH2-;

- i is , at each instance, independently 0 or an integer from 1 to 4; and

- j, is , at each instance, independently 0 or an integer from 1 to 3.

[0016] For the sake of clarity, when i or j is zero, the corresponding aromatic rings are unsubstituted.

[0017] Unless specifically expressed otherwise, the term “alkyl”, as well as derivative terms such as “alkoxy” and “alkylaryl”, as used herein, include within their scope straight chain, branched chain and cyclic moieties. Examples of alkyl groups are methyl, ethyl, 1 -methylethyl, propyl, 1 ,1 dimethylethyl, and cyclo-propyl. Unless specifically stated otherwise, each alkyl and aryl group may be unsubstituted or substituted with one or more substituents selected from but not limited to halogen, hydroxy, sulfo, C1 - C6 alkoxy, C1 -C6 alkylthio, C1 -C6 acyl, formyl, cyano, C6-C15 aryloxy or C6-C15 aryl, provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied. The term “halogen” or “halo” includes fluorine, chlorine, bromine and iodine, with fluorine being preferred.

[0018] The term “aryl” refers to a phenyl, indanyl or naphthyl group. The aryl group may comprise one or more alkyl groups, and are called sometimes in this case “alkylaryl”; for example may be composed of a cycloaromatic group and two C1 -C6 groups (e.g. methyl or ethyl). The aryl group may also comprise one or more heteroatoms, e.g. N, O or S, and are sometimes called “heteroaryl” group; these heteroaromatic rings may be fused to other aromatic systems. Such heteroaromatic rings include, but are not limited to furanyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, isoxazolyl, oxazolyl, thiazolyl, isothiazolyl, pyridyl, pyridazyl, pyrimidyl, pyrazinyl and triazinyl ring structures. The aryl or heteroaryl substituents may be unsubstituted or substituted with one or more substituents selected from but not limited to halogen, hydroxy, C1 -C6 alkoxy, sulfo, C1 - C6 alkylthio, C1 -C6 acyl, formyl, cyano, C6-C15 aryloxy or C6-C15 aryl, provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied.

[0019] The poly(arylene sulfide) polymer can be amorphous or semi-crystalline. As used herein, an amorphous polymer has an enthalpy of fusion of no more than 5 J/g. The person of ordinary skill in the art will recognize that when the poly(arylene sulfide) polymer is amorphous, it lacks a detectable melting temperature. Accordingly, where a poly(arylene sulfide) polymer has a melting temperature, the person of ordinary skill in the art will recognize that it refers to a semi-crystalline polymer. Preferably, the poly(arylene sulfide) polymer is semi-crystalline. In some embodiments, the poly(arylene sulfide) polymer has an enthalpy of fusion of at least 10 J/g, at least 20 J/g, or at least 25 J/g. In some embodiments, the poly(arylene sulfide) polymer has an enthalpy of fusion of no more than 90 J/g, no more than 70 J/g or no more than 60 J/g. In some embodiments, the poly(arylene sulfide) polymer has an enthalpy of fusion of 10 J/g to 90 J/g or 20 J/g to 70 J/g. The enthalpy of fusion can be measured using differential scanning calorimetry (DSC), according to ASTM D3418 employing a heating and cooling rate of 20°C/min. Advantageously, three scans are used for each DSC test: a first heat up to 350°C, followed by a first cool down to 30°C, followed by a second heat up to 350°C.

[0020] Preferably, the poly(arylene sulfide) polymer has a melt flow rate of at most 700 g/10 min, more preferably of at most 500 g/10 min. Preferably, the poly(arylene sulfide) has a melt flow rate of at least 1 g/10 min, more preferably of at least 5 g/10 min. In the present specification, the melt flow rate of any poly(arylene sulfide) polymer refers to the value measured at 5 kg and 315.6°C as detailed in the experimental section.

[0021 ] As noted above, each layer of the multilayer structure comprises a poly(arylene sulfide) polymer.

[0022] According to an embodiment of the present invention, the poly(arylene sulfide) polymer is poly(phenylene sulfide) (hereinafter referred to as “PPS”). The expression “poly(phenylene sulfide)” or PPS, is used to refer to a poly(arylene sulfide) polymer where the recurring unit (RPAS) is represented by formula (1 ). More preferably, recurring unit (RPAS) is represented by formula (4):

[0023] Most preferably in PPS, the recurring unit (RPAS) is represented by formula (4) in which i = 0.

[0024] The PPS may be acid washed or not acid washed. In some embodiments, the PPS is acetic acid washed PPS.

[0025] In a preferred embodiment, the PPS polymer is such that at least 90.0 mol% of the recurring units are recurring units of formula (4) in which i= 0. The PPS polymer may consist essentially of recurring units of formula (4) in which i = 0.

[0026] Suitable PPS is commercially available under the trade name Ryton® PPS from Solvay Specialty Polymers USA, LLC.

[0027] The melt flow rate (at 5 kg and 315.6°C) of the PPS may be from 1 to 400 g/10 min, for example from 5 to 300 g/10 min or from 5 to 200 g/10 min.

[0028] Laver (BL)

[0029] Layer (BL) is formulated to provide the barrier to permeation of gasses.

[0030] Layer (BL) does not contain any continuous reinforcing fiber.

[0031 ] Layer (BL) has a thickness which provides the required value of gas permeation required for the application. Layer (BL) typically has a thickness of at least 100 microns, generally at least 250 microns. Layer (BL) may have a thickness of up to 10.0 mm, even 8.5 mm, 7.5 mm. Layer (BL) may have a thickness of 100 microns to 10.0 mm, generally from 250 microns to 10.0 mm, even from 300 microns to 8.5 mm, still from 500 microns to 6.0 mm.

[0032] In a first embodiment, the poly(arylene sulfide) polymer is the sole polymer in Layer (BL). In such an embodiment, Layer (BL) comprises 75.0 wt% or more of the poly(arylene sulfide), even 80.0 wt% or more, still 85.0 wt% or more with respect to the total weight of Layer (BL). In such an embodiment Layer (BL) may contain 25.0 wt% or less of one or more additives commonly employed in the formulation of poly(arylene sulfide) polymers. Non limiting examples of suitable additives are antioxidants (e.g. ultraviolet light stabilizers and heat stabilizers), processing aids, nucleating agents, lubricants, flame retardants, smoke-suppressing agents, anti-static agents, anti-blocking agents, colorants, and pigments.

[0033] The total amount of additives may be 20.0 wt% or less, even 10.0 wt% or less with respect to the total weight of Layer (BL). When present the amount of one or more additives is at least 1 .0 wt%, even at least 2.0 wt%, relative to the total weight of the poly(aryl sulfide) polymer.

[0034] In a preferred aspect of said embodiment, the poly(arylene sulfide) polymer is PPS.

[0035] The PPS suitable for Layer (BL) advantageously has a melt flow rate (at 5 kg and 315.6°C) of 5 to 200 g/10 min, for example from 5 to 180 g/10 min. In some instances the melt flow rate may be from 5 to 50 g/10 min, even from 5 to 40 g/10 min.

[0036] In a second embodiment, Layer (BL) comprises the poly(arylene sulfide) polymer, preferably PPS, and at least one other thermoplastic polymer.

[0037] In an advantageous aspect of said embodiment, Layer (BL) comprises the poly(arylene sulfide) polymer, preferably PPS, and an impact modifier.

[0038] Suitable impact modifiers are for instance functionalized polyolefins with a glass transition temperature lower than 25°C.

[0039] The polymer backbone of the impact modifier can be selected from elastomeric backbones comprising polyethylenes and copolymers thereof, e.g. ethylene-butene; ethylene-octene; polypropylenes and copolymers thereof; polybutenes; polyisoprenes; ethylene-propylene-rubbers (EPR); ethylene-propylene-diene monomer rubbers (EPDM); ethylene-acrylate rubbers; butadiene-acrylonitrile rubbers, ethylene-acrylic acid (EAA), ethylene-vinylacetate (EVA); acrylonitrile-butadiene-styrene rubbers (ABS), block copolymers styrene ethylene butadiene styrene (SEBS); block copolymers styrene butadiene styrene (SBS); core shell elastomers of methacrylate-butadiene-styrene (MBS) type, or mixture of one or more of the above.

[0040] When the impact modifier is functionalized, the functionalization of the backbone can result from the copolymerization of monomers which include the functionalization or from the grafting of the polymer backbone with a further component. [0041 ] Specific examples of functionalized impact modifiers are notably terpolymers of ethylene, acrylic ester and glycidyl methacrylate, copolymers of ethylene and butyl ester acrylate; copolymers of ethylene, butyl ester acrylate and glycidyl methacrylate; ethylene-maleic anhydride copolymers; EPR grafted with maleic anhydride; styrene copolymers grafted with maleic anhydride; SEBS copolymers grafted with maleic anhydride; styreneacrylonitrile copolymers grafted with maleic anhydride; ABS copolymers grafted with maleic anhydride.

[0042] Functionalized polyolefin impact modifiers are available from commercial sources, including maleated polypropylenes and ethylene-propylene copolymers available as Exxelor® PO and maleic anhydride-functionalized ethylene-propylene copolymer rubber comprising about 0.6 weight percent pendant succinic anhydride groups, such as Exxelor® VA 1801 from the ExxonMobil Chemical Company; acrylate-modified polyethylenes available as Surlyn®, such as Surlyn® 9920, acrylic or methacrylic acid-modified polyethylene from Dow Inc.; maleic anhydride-modified SEBS block copolymer, such as Kraton® FG1901X, a SEBS that has been grafted with about 2 wt% maleic anhydride, available from Kraton Polymers; maleic anhydride-functionalized EPDM terpolymer rubber, such as Royaltuf® 498, a 1 % maleic anhydride functionalized EPDM, available from the SI Group.

[0043] Other desirable functionalized impact modifiers include, but are not limited to, ethylene-higher alpha-olefin polymers and ethylene-higher alpha-olefin- diene polymers grafted or copolymerized with reactive carboxylic acids or their derivatives such as, for example, acrylic acid, methacrylic acid, maleic anhydride or their esters. Suitable higher alpha-olefins include, but are not limited to, C3 to C8 alpha-olefins such as, for example, propylene, 1 -butene, 1 -hexene and styrene.

[0044] Among reactive impact modifiers mention may be made of a random terpolymer of ethylene, acrylic ester and glycidyl methacrylate which is commercially available from Arkema (Bristol, PA, USA) under the trade name Lotader® AX8900. Another example of the aforementioned reactive impact modifier is commercially available from Dow Inc. (Midland, Ml, USA) under the trade name Paraloid™ EXL 2314, which is a core-shell type acrylate based impact modifier comprised of a core primarily comprised of cross-linked poly(n-butyl acrylate) rubber and having a shell phase comprised primarily of a poly(methyl methacrylate)-poly(glycidyl methacrylate) copolymer.

[0045] In said second embodiment, Layer (BL) comprises from 1.0 wt% to 25.0 wt% of the at least one thermoplastic polymer and/ or impact modifier with respect to the total weight of the Layer (BL). The impact modifier can be at least 2.0 wt % or at least 3.0 wt%, even at least 5.0 wt% of the total weight of Layer (BL). The impact modifier typically is not more than 20.0 wt %, not more than 15.0 wt%, not more than 12.0 wt%, even not more than 10.0 wt%. Suitable ranges may be for instance from 1 .0 to 15.0 wt%, even from 1 .0 to 12.0 wt%, or even 2.0 to 10.0 wt%.

[0046] In the second embodiment Layer (BL) may additionally comprise additives as detailed above. The total amount of additives may be 20.0 wt% or less, even 10.0 wt% or less with respect to the total weight of Layer (BL) and/or at least 1.0 wt%, even at least 2.0 wt% with respect to the total weight of Layer (BL).

[0047] Layer (BL) may be prepared using common techniques for the manufacture of films or sheets of poly(phenylene sulfide) polymers, as known to the person skilled in the art. For instance, Layer (BL) may be produced by rotomoulding, injection molding and optionally welding, pipe extrusion and extrusion blow molding.

[0048] Films of poly(phenylene sulfide) polymers may be optionally mono-axially or bi-axially oriented. Biaxial orientation may be performed on tenterframe biaxial orientation equipment as known in the art.

[0049] Laver (CL)

[0050] The multilayer structure of the invention comprises at least one Layer (CL). Layer (CL) comprises continuous reinforcing fibers and a poly(arylene sulfide) polymer.

[0051] The poly(arylene sulfide) polymer is as defined above. It may be the same or a different one with respect to the poly(arylene sulfide) polymer used in Layer (BL). In a preferred embodiment the poly(arylene sulfide) polymer in Layer (CL) is PPS. [0052] The PPS suitable for Layer (CL) advantageously has a melt flow rate (at 5 kg and 315.6°C) of 10 to 200 g/10 min, for example from 30 to 150 g/10 min.

[0053] In an advantageous embodiment, the poly(arylene sulfide) polymer is the sole polymer in Layer (CL).

[0054] Layer (CL) comprises continuous reinforcing fibers impregnated with the poly(arylene sulfide) polymer as detailed hereafter. As used herein, the expression “continuous reinforcing fiber” refers to a fiber having a length of at least 5 mm. The length of the fiber corresponds to the longest dimension of the fiber.

[0055] In some embodiments, the continuous reinforcing fiber has a length, in the longest dimension, of at least 1 cm, at least 25 cm or at least 50 cm. The length of the continuous reinforcing fiber is dependent on the shape and size of the finished part.

[0056] The continuous reinforcing fiber is selected from the group consisting of glass fiber, carbon fibers, aluminum fiber, metallic fibers, ceramic fiber, titanium fiber, magnesium fiber, boron carbide fibers, rock wool fiber, steel fiber, aramid fiber and natural fiber (e.g. cotton, linen and wood). Preferably, the continuous reinforcing fiber is selected from the group consisting of glass fiber, carbon fiber, aramid fiber, and ceramic fiber. Advantageously, the continuous reinforcing fiber is carbon fiber.

[0057] In some embodiments, Layer (CL) may include one or more additional continuous reinforcing fibers, each distinct in compositions and as described above.

[0058] Overall, the continuous reinforcing fibers constitute at least 5.0% of the total volume of Layer (CL). Typically the continuous reinforcing fibers represent at least 10.0%, even at least 15.0%, even at least 20.0%, at least 25.0%, even at least 30.0% of the total volume of Layer (CL). The continuous reinforcing fibers are no more than 80.0%, no more than 75.0%, even no more than 70.0% of the total volume of Layer (CL). The continuous reinforcing fibers may conveniently represent from 20.0% to 75.0%, from 25.0% to 70.0%, from 25.0% to 65.0% and even from 30.0% to 60.0% of the total volume of Layer (CL). The polymer matrix represents the remainder of the volume of Layer (CL). [0059] The continuous reinforcing fibers in Layer (CL) are generally aligned along a single direction. Generally aligned fibers are oriented such that at least 70%, at least 80%, at least 90% or at least 95% of the fibers have a direction that is within 30 degrees, within 25 degrees, within 20 degrees, within 15 degrees, or within 10 degrees along the direction of the other fibers.

[0060] In certain embodiments the continuous reinforcing fibers in Layer (CL) may be arranged at an angle the ones with respect to the others. The continuous reinforcing fibers might be arranged as a woven fabric or a layered fabric or any combination of one or more.

[0061 ] Layer (CL) can be fabricated by methods well known in the art. In general, the method of fabrication includes a step of impregnation of the continuous reinforcing fibers with the poly(arylene sulfide) polymer composition, and subsequent cooling or drying to form a Layer (CL).

[0062] Impregnation of the continuous reinforcing fibers with the poly(arylene sulfide) polymer composition may take place, for instance, by means of a melt impregnation process, which includes contacting the continuous reinforcing fibers with a melt of the polymer material. Subsequent to melt impregnation, the impregnated continuous reinforcing fibers are cooled to form a solid composite.

[0063] Impregnation may take place by means of a solution process or a slurry process. In a solution process, a solution is formed by dissolving the polymer in a liquid medium. The solution is coated onto a surface of the continuous reinforcing fibers, for example, by passing the fibers through a bath of the solution. Subsequently, the coated fibers are then heated and consolidated. In a slurry process, the continuous fibers are impregnated with particles of the polymer, for example, by passing the fibers through a suspension of the particles or a fluidized bed of the particles. Subsequently, the fibers containing the polymer particles are heated and consolidated.

[0064] Layer (CL) has a thickness which is usually between 100 microns and 500 microns. The thickness is adapted to provide multilayer structures which can be easily shaped to provide an article, such as a vessel.

[0065] The multilayer structure

[0066] The multilayer structure of the invention comprises at least one Layer (BL) and at least one Layer (CL) in contact with the at least one barrier layer as defined above. More than one Layer (BL) may be present in the multilayer structure. More than one layer (CL) may be present in the multilayer structure.

[0067] The multilayer structure can comprise up to ten Layers (BL) and up to ten or even more than ten Layers (CL).

[0068] The multilayer structure does not comprise a binder or adhesive layer between Layer (BL) and Layer (CL).

[0069] The multilayer structure can include more Layers (BL) than Layers (CL) or vice versa. Typically, the multilayer structure does not comprise alternating Layers (BL) and Layers (CL).

[0070] The multilayer structure may consist of one or more Layers (BL) and one or more Layers (CL).

[0071] Advantageously, the multilayer structure comprises one, two, three, four, five, six, seven, eight, nine or ten Layers (BL) and one, two, three, four, five, ten, 50, 100 or even more Layers (CL) such as 200 or 300.

[0072] In one embodiment, the multilayer structure comprises a single Layer (BL) and several Layers (CL). The multilayer structure may consist of a single Layer (BL) and one or more Layers (CL), the layer (BL) representing one of the outer surfaces of the multilayer structure.

[0073] In some embodiments, the multilayer structure may comprise additional layers in contact with Layer (CL) on the opposite side of Layer (BL). Said additional layers may or may not comprise reinforcing fibers. The additional layers may or may not comprise a poly(arylene sulfide) polymer. Preferably, the additional layers are not made of metallic strips of material.

[0074] The article

[0075] A further object of the invention is an article for the storage and/or transportation of a gas, comprising the multilayer structure as defined above. Notable non-limiting examples of articles are hoses, pipes, tubes, joints, tanks, reservoirs or, in general, vessels.

[0076] Of these, the multilayer structure of the present invention, for its excellence in both flexibility and heat cycle resistance, is suitable for use as a hose for compressed gas, in particular hydrogen. The hose for compressed hydrogen is used as a hose for charging a fuel-cell vehicle or the like with hydrogen from a hydrogen station. Since the hose for compressed hydrogen is subject to repeated temperature changes (heat cycles) from -40°C or lower to 90°C or higher due to charging and discharging of high-pressure hydrogen, it is required to have high heat cycle resistance , pressure cycle resistance as well as flexibility.

[0077] The hose for high-pressure hydrogen is a hose comprising the multilayer structure of the first object, wherein Layer (BL) is in contact with the compressed gas and layer (CL) represents the outside of the hose.

[0078] The inventive multilayer structure is characterized by high thermal resistance, good hydrogen barrier, very good resistance to pneumatic cycling and decompression and non-flammability. These features make the multilayer structure particularly well adapted for the use in vessels for storing gasses under pressure.

[0079] The term “vessel” is used herein to refer to a hollow container. The vessel of the invention is in particular a hollow container for containing a gas, preferably a pressurized or compressed gas.

[0080] Advantageously, the vessel obtained from the multilayer structure according to the invention exhibits no signs of explosive decompression (blistering), neither in cyclic testing nor in static testing.

[0081 ] Hence a further object of the invention is a vessel for the storage or transportation of a gas comprising the multilayer structure as defined above.

[0082] Layer (BL) represents the internal layer of the vessel which is in contact with the gas to be transported or stored, hereinafter referred to as “inner layer” or “liner”. Layer (CL) represents the external layer of the vessel. All the definitions and preferences provided for Layer (BL), layer (CL) and the multilayer structure apply to the vessel.

[0083] The vessel is preferably a pressure vessel, that is a vessel suitable for the storage and/or transportation of a gas under pressure.

[0084] The vessel, or preferably the pressure vessel, comprises a hollow body and at least one boss. A boss is known by a person skilled in the art and it refers to the opening in which a closure is attached which allows flow of gas or fluid in and out the vessel. A boss is usually made of metal. [0085] The hollow body may have any shape suitable for the storage of a gas, in particular of a gas under pressure.

[0086] In certain conventional embodiments, the vessel has a cylindrical shape and a boss is placed at the end. Often, a vessel has two bosses at each end of the cylindrical shape. The shape of the hollow body is determined by the desired use and is usually but not exclusively cylindrical. The hollow body may have a diameter of between 10.0 cm and 1 .0 m. The diameter may be at least 15.0 cm.

[0087] The length of the hollow body also depends on the end use. The hollow body may have a length of 50.0 cm to 10.0 m. These higher lengths are usually employed for gas transport. As an example, for vessels in trucks the length is usually between 1 .0 m and 3.0 m.

[0088] The vessel of the invention may have an internal volume between 3.5 dm³ and 5.0 m³, even from 5.0 dm³ to 1 .0 m³ The internal volume of the vessel may be at least 10.0 dm³, even at least 15.0 dm³. The internal volume may be up to 1 .0 m³, even up to 0.5 m³.

[0089] The vessel comprises a hollow body comprising from the inside to the outside of the vessel: at least one barrier layer or liner which is Layer (BL) as defined above, and at least one composite layer, which is Layer (CL) as defined above, in contact with the at least one barrier layer. Layer (BL) is in contact with the gas contained in the vessel.

[0090] The liner intends to provide a barrier between the fluid or gas and the Layer (CL), preventing leaks. In general, Layer (CL) is provided around the liner to provide mechanical properties, such as burst pressure resistance.

[0091 ] The vessel may be prepared according to any method known in the art.

[0092] For instance, the liner may be prepared by blow molding, tube extrusion, injection molding and welding and/or roto-molding. Layer (CL) may then be applied on the outer surface of the liner by winding a tape comprising continuous reinforcing fibers and a poly(arylene sulfide) polymer around the hollow body made of the liner.

[0093] Other manufacturing processes as known in the art for the manufacture of pressure vessels may be used.

[0094] Accordingly, the invention also relates to a process for preparing a vessel comprising the following steps: a. providing a liner in the form of a hollow body; b. providing a tape comprising continuous reinforcing fibers and a poly(arylene sulfide) polymer; c. winding the tape around the liner while consolidating the tape by heat; d. cooling the body obtained at the end of step c. to become solid.

[0095] The term tape is understood herein to refer to an elongated body having a longitudinal direction, a width, a thickness and a cross-sectional aspect ratio, i.e. the ratio of thickness to width. Said cross-section is defined as substantially perpendicular to the longitudinal direction of the tape. The longitudinal direction or machine direction of the tape essentially corresponds to the orientation of the endless fibers. The length dimension of a tape is not particularly limited. The length may exceed 10 km and mainly depends on the continuous fibers and the process used to produce the tape. Nevertheless said tape can for convenience reasons be manufactured to smaller sizes, according to the requirements of the envisioned applications.

[0096] Tapes usually have a thickness of between 100 micrometer and 500 micrometer as thicker tapes are more difficult to wrap. Thinner tapes have the disadvantage that more wrapping is required to attain the hollow body.

[0097] The support may be a liner. The support thus becomes a part of the hollow body.

[0098] Winding may be performed in the form of a tape which comprises the continuous reinforcing fibers and a poly(arylene sulfide) polymer.

[0099] Consolidation is performed preferably by heat, such as provided by a laser, as for example an infrared laser, or a hot gas torch or heating elements such as an oven. Possibly a post annealing is done.

[00100] The vessel according to the invention exhibits a nominal pressure of at least 2.5 MPa, typically at least 20.0 MPa, even at least 30.0 MPa. The nominal pressure may be up to 70.0 MPa, 100 MPa, even 150.00 MPa and more. Advantageously, the vessel of the invention has a nominal pressure of 20.0 to 70.0 MPa.

[00101 ] A burst pressure of at least 157.5 MPa may be reached for the storage of hydrogen gas with a vessel according to the invention. Vessels for the storage of compressed hydrogen typically require nominal pressures of 35.0 MPa or 70.0 MPa. Burst pressures, measured according to ECE R134, are typically up to 78.8 MPa and 157.5 MPa, respectively.

[00102] A further object of the invention is a compressed gas in a vessel comprising the multilayer structure of the first object, wherein Layer (BL) is in contact with the compressed gas. The gas is advantageously selected from the group consisting of hydrogen, oxygen, nitrogen, argon, helium, methane, propane, compressed natural gas, CO2 and ammonia.

[00103] The gas is typically at a pressure of at least 5.0 MPa, preferably at least 10.0 MPa. Depending on the gas, the pressure may be up to 150.0 MPa.

[00104] Still another object of the invention is a vehicle comprising the vessel or the compressed gas stored in the vessel.

[00105] The vehicle may be a car, a truck, a train, a ship, an urban mobility vehicle, an airplane, a helicopter or any other vehicle that could be powered using the conversion of a gas into energy by any means.

[00106] The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the inventive concepts. In addition, although the present invention is described with reference to particular embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention.

[00107] EXAMPLES

[00108] MATERIALS

[00109] PPS1 is Ryton® XE-5500 BL a poly(phenylene sulfide) polymer commercially available from Solvay Specialty Polymers USA, LLC with a melt flow rate of 10 g/10 min (5 kg, 315.6°C)

[00110] PPS2 was synthesized in a 340 liter reactor with 41 .3 kg of aqueous sodium hydrosulfide (57.0 wt %, Nouryan), 30.8 kg of aqueous sodium hydroxide (50.6 wt %, Columbus), 12.1 kg of sodium acetate (Jarchem), and 123.1 kg of N-methyl-2-pyrrolidone (Ashland). Following a dehydration step, 58.6 kg of 1 ,4-dichlorobenzene and 0.108 kg 1 ,2,4-trichlorobenzene were added under nitrogen pressure and the sealed reactor was heated to a maximum temperature of 275°C. After addition of 7.7 kg of additional NMP, the mixture was cooled gradually to obtain granular PPS which was rinsed with NMP, water, and an acetic acid solution at 60°C - 75°C, affording 35.3 kg of a white, granular PPS resin. The resin had a melt flow rate of 11 g/10 min (5 kg, 315.6°C).

[00111] PPS3 is Ryton® QA 200 P a poly(phenylene sulfide) polymer commercially available from Solvay Specialty Polymers USA, LLC.

[00112] PA12 is Grilamid® L25 NZ commercially available from EMS Chemie [00113] MTM® 57: is a carbon fiber/epoxy resin UD prepreg commercially available from Solvay SA

[00114] Melt flow rate

[00115] Melt flow rate of poly(aryl sulfide) polymers was measured in an extrusion plastomer at 315.6°C using a weight of 5 kg and a 0.21 cm x 0.80 cm die after a 5 minute equilibration period, according to ASTM D1238, procedure B.

[00116] Tensile testing

[00117] Tensile properties were measured according to ISO 527-2 using samples meeting the requirements of ISO 1 BA at a test speed of 5 mm/min.

[00118] H2 permeation coefficient determination

[00119] Samples for hydrogen permeation testing were prepared as follows. PPS polymers were dried overnight at 107°C in a desiccant drying oven with a - 40°C dew point to ensure material was dry prior to injection molding into plates.

[00120] PA 12 polymer samples were dried at 70°C.

[00121] The material was injection molded into 10 cm x 10 cm x 0.32 cm plates using a 250 ton Sumitomo SE 250 EV-A HD all electric injection molding machine, following the polymer suppliers recommended injection molding processing guidelines. The molding machine was fitted with a 45 mm screw size with a maximum screw speed of 250 rpm with a maximum shot capacity of 0.34 dm3. The machine had a maximum shot size of 21 cm and the maximum injection pressure was 215 MPa. The plates were annealed at a temperature of 20°C above their glass transition temperatures for a period of 2 h to ensure full crystallinity prior to hydrogen permeation testing.

[00122] The molding conditions are summarized in the table below:

60123] Sheets of PPS1 , PPS2 and PPS3 were annealed at 110°C during 2 h.

Sheets of PA 12 were annealed at 70°C during 2 h.

[00124] The samples thus obtained were mounted in a sealed chamber and a check was made to ensure that the chamber was leak tight by applying hydrogen at 1 MPa on the feed side. Subsequently the chamber was conditioned at the temperature of testing. On the feed side H2 was fed at 1 MPa. On the permeate side, synthetic air was fed at a controlled throughput and H2 was measured using a calibrated Inficon Sentrac H2 Leak Detector, until a stable value for H2 was obtained to assure a stationary regime.

[00125] The permeation coefficient was calculated taking into account the thickness of the sample, the exposed surface, the concentration of H2, the flow rate of the carrier gas and the pressure.

[00126] The results of the mechanical properties and the hydrogen permeation coefficients are shown in Table 1 .

Table 1

[00127] The data in Table 1 show that PPS1 and PPS2 have a significantly lower permeation coefficient, which results in higher barrier properties, than an aliphatic polyamide like PA12.

[00128] The difference in the permeation coefficient becomes more and more pronounced at increasing temperatures. The lower dependence of the permeation coefficient from temperature for the sheets made of PPS1 and PPS2 is very advantageous as vessels for gasses under pressure are exposed to high temperatures.

[00129] In parallel, PPS1 and PPS2 have higher modulus than PA12.

[00130] The combination of the properties above allows the design of thinner liners without compromising either the barrier properties or the mechanical properties of the vessel.

[00131] Static & Dynamic blistering tests on multilayer structures

[00132] Preparation of multilayer structure of Example 1 and 2

[00133] Composite samples of 4 mm thickness were prepared starting from unidirectional PPS carbon fiber tapes prepared using a commercial PPS polymer sold under the trade name of Ryton® QA 200 N by Solvay Specialty Polymers USA LLC and approximately 55 % volume fraction of carbon fibers, in a press at 320 °C, 2.5 MPa and a holding time of 20 min.

[00134] Samples of PPS sheets PPS1 (Example 2) and PPS3 (Example 1 ) prepared above, and the PPS/CF composite samples were coconsolidated in a press with limited contact time (to simulate conditions of a winding process) under the following operating conditions: preheating of the mold at 300 °C; contact time of 3’, contact pressure of 0.7 MPa.

[00135] Preparation of multilayer structure of Comparative Example 1

[00136] Multilayer structures comprising a liner of PA 12 and a carbon fiber/epoxy resin reinforcement layer were prepared by co - curing sheets of PA12 with MTM® 57 carbon fiber/epoxy resin prepreg as follows : 4 plies 150mm x 150mm of MTM® 57 were used as a reinforced epoxy substrate in 0/90 orientation. [00137] 125mm x 125mm square of polymer plaque PA 12 were applied on the epoxy substrate. No special preparation was carried out on the epoxy prepreg or the polymer square.

[00138] All lay-up stacks were cured using standard vacuum bag consumables. Curing was carried out under vacuum (below 50 mbar) in an oven. The temperature was controlled with a ramp, dwell and cool down using a Eurotherm controller. The curing temperature was 120°C and the curing time was one hour.

[00139] Conditions for testing

[00140] Samples of Example 1 and 2 and Comparative Example 1 were submitted to a dynamic cycling test to detect blistering between the liner and the fiber reinforced layers. The samples were introduced in the testing apparatus and submitted to repeated pressurization and depressurization cycles as follows:

° Condition to 50 ± 2 °C

° Perform 250 cycles

■ Pressurize to >= 44 MPa

■ Hold at >= 44 MPa for 24.8 min

■ Depressurize to <= 0.5 MPa at ca. 1 ,000 MPa/hr

■ Hold at <= 0.5 MPa for 24.8 min

° Depressurize to ambient pressures

° Remove samples from pressure vessel

• Measure weight after 60 minutes and 24 hours

Report weight difference before I after testing and report blistering.

[00141] At the end of the tests samples were analyzed by RX tomography using a 150 kV source and a focal spot of 20 p. The presence of blisters at the liner (BL) I composite (CL) interface was noted.

[00142] Static blistering tests were performed under the following conditions:

° Condition to 50 ± 2 °C

° Pressurize to 87.5 MPa

° Soak for 48 h (exposure)

° Depressurize to ambient pressure as fast as possible (target: < 1s) Report weight difference before I after testing and report blistering.

[00143] The results are shown in Table 2. Table 2

[00144] The results show very stable mass for the inventive multilayer structures of Example 1 and Example 2. A weight loss was measured for the comparative multilayer structure containing a PA12 liner and an thermoset carbon fiber composite layer.. The inventive multilayer structures maintain a very good interface showing no bubbles, no blistering at the interface between liner and the fiber reinforced structural layer both in dynamic and static blistering tests. Several blisters and cracks were observed in the multilayer structure of Comparative Example 1 .

Claims

1 . A multilayer structure comprising at least one gas barrier layer, [Layer (BL)], and at least one composite layer, [Layer (CL)] in contact with the at least one gas barrier layer wherein:

- Layer (BL) comprises a poly(arylene sulfide) polymer; and

2. The multilayer structure of claim 1 wherein the poly(arylene sulfide) polymer contains at least 50 mol% of a recurring unit (RPAS) represented by a formula selected from the following group of formulae:

(3), where:

R is, at each instance, independently selected from the group consisting of a C1-C12 alkyl group, a C7-C24 alkylaryl group, a C7-C24 aralkyl group, a C6-C24 arylene group, and a Ce-C-is aryloxy group;

T is selected from the group consisting of a bond, -CO-, -SO2-, -O-, -C(CH3)2, phenyl and -CH2-; i is, at each instance, independently 0 or an integer from 1 to 4; and j, is, at each instance, independently 0 or an integer from 1 to 3. The multilayer structure of claim 2 wherein recurring unit (RPAS) is represented by formula (4): in which R and i are as defined in claim 2, preferably in formula (4) i is 0 at all instances. The multilayer structure of any one of claims 1 to 3 in which Layer (BL) comprises the poly(arylene sulfide) polymer and from 1 .0 wt% to 25.0 wt% of at least one impact modifier with respect to the total weight of the Layer (BL). The multilayer structure of any one of the preceding claims in which the continuous reinforcing fibers have a length of at least 5 mm. The multilayer structure of any one of the preceding claims in which the continuous reinforcing fibers are selected from the group consisting of glass fiber, carbon fiber, aramid fiber, and ceramic fiber. The multilayer structure of any one of the preceding claims in which the continuous reinforcing fibers in Layer (CL) are present in an amount of 15.0% to 80.0% by volume with respect to the total volume of Layer (CL). The multilayer structure of any one of the preceding claims which consists of one or more Layers (BL) and one or more Layers (CL), preferably it consists of one Layer (BL) and one or more layers (CL). An article for storing and/or transporting a gas comprising the multilayer structure any one of the preceding claims. The article of claim 9 in the form of a vessel or a hose. The vessel or hose of claim 10 in which Layer (BL) represents the internal layer and Layer (CL) represents the external layer of the vessel or hose. The vessel of any one of claims 10 or 11 which is in the shape of a hollow body which has one or more of the following:

- a diameter of 10.0 cm to 1 .0 m;

- a length of 50.0 cm to 10.0 m; and

- an internal volume of 3.5 dm³ to 5.0 m³. A compressed gas contained in the vessel of any one of claims 10 to 12, wherein the compressed gas is in contact with Layer (BL). The compressed gas of claim 13 which is selected from the group consisting of hydrogen, oxygen, nitrogen, argon, helium, methane, propane, compressed natural gas, CO2, ammonia. The compressed gas of claims 13 or 14 which is at a pressure of 1 .0 MPa to 150.0 MPa. A vehicle comprising the vessel of any one of claims 10 to 12 or the compressed gas of any one of claims 13 to 15. Use of the vessel of any one of claims 10 to 12 for the storage or transportation of a compressed gas. Use of the hose of claim 10 or 11 for the transport of a gas, preferably a compressed gas.