Method for preparing a pressure vessel

Abstract

The invention is related to a method for preparing a composite pressure vessel (200) comprising the steps of providing a container (100) comprising a liner (101) having at least one open end, which liner encloses a solid material configured to function as a filtration system, a reactor system or a battery system (102); providing a radiation curable liquid resin comprising ethylenically unsaturated compounds; providing glass fiber material; impregnating the glass fiber material with the radiation curable liquid resin; winding the container with the impregnated glass fiber to form a non-cured pressure vessel; bringing the non-cured pressure vessel under exposure of a UV light source or an EB source that is able to cure the radiation curable resin to provide the composite pressure vessel enclosing the solid material.

Description

[0001] Method for preparing a pressure vessel

[0002] The present invention relates to a method for preparing a composite pressure vessel comprising solid material the composite pressure vessel prepared according to the method and the use of radiation curable resins for preparing the composite pressure vessel comprising solid material.

[0003] Background of the invention

[0004] Pressure vessels made with composite materials are known from US 2016 / 0084438 Al and US 2011 / 0309074 Al. A composite or a composite material is a combination of two or more non miscible materials typically comprising a plastic or resin matrix and a filler material whereby the resin holds the filler together and forms a continuous phase for cohesion of the structure and the filler material. Composites can have various shapes and properties depending on the application fields and on the type of fillers and resin matrix that are used. There are numerous application fields such as automotive, aerospace, transport, building, electronics, batteries, process equipment. Composite materials can also be used to make vessels, such as reinforced pressure vessels that are able to withstand pressure from in- or outside the vessel.

[0005] State of the art composite manufacturing of composite pressure vessels involve the use of continuous fibers and a two component thermoset resin composition. The continuous fibers are pulled by a winder through an impregnation bath in which the thermoset resin composition is present. Typically, during the manufacturing process, the viscosity of the two component resin composition needs to be carefully monitored, as it has a limited potlife. Often, the viscosity increases throughout the process, which adversely impacts the impregnation quality of the fibers. The non-cured composite materials are made and brought to an oven at high temperatures for curing, which takes several hours. Often such curing processes are continuous, whereby precured vessels pass one after the otherthrough an oven system. In case quality issues occur, this can only be noticed after several hours and leads to an enormous waste.

[0006] It is known from US 2016 / 0084438 Al to utilize a UV cure resin system instead of thermoset resin, resulting in shorter processing times and additional safety since the pressure vessel being cured is not subjected to elevated temperatures. In some applications, the composite pressure vessels are made with an open end and the composite pressure vessel is filled afterwards and sealed. Such a process may be timeconsuming.

[0007] There is a need to provide methods for making composite pressure vessels that overcomes at least the above drawbacks.

[0008] Summary of the invention

[0009] It is an object of the present invention to develop a method for preparing or manufacturing a composite pressure vessel, that comprises solid material.

[0010] In a first aspect, the present invention relates to a method for preparing a composite pressure vessel comprising the steps of:

[0011] • providing a container comprising a liner having at least one open end, which liner comprises or encloses a content of solid material ;

[0012] • providing a radiation curable liquid resin comprising ethylenically unsaturated compounds;

[0013] • providing glass fiber material;

[0014] • impregnating the glass fiber material with the radiation curable liquid resin;

[0015] • winding the container with the impregnated glass fiber to form a non-cured pressure vessel;

[0016] • bringing the non-cured pressure vessel under exposure of an ultra violet (UV) light source or an electron beam (EB) source that is able to cure the radiation curable resin to provide the pressure vessel.

[0017] Advantageously, the solid material is configured to function as a filtration system, a reactor system or a battery system, particularly a battery system or a filtration system.

[0018] In a second aspect, present invention relates to a composite pressure vessel obtained by the method of the first aspect.

[0019] In a third aspect, the present invention relates to the use of radiation curable resins comprising ethylenically unsaturated compounds for the manufacture of a composite pressure vessel according to the method of the first aspect. Radiation curable composites, made from actinic radiation curable resin material and fibers, can be cured in a very fast way, at ambient temperature. Besides the fast curing time and thus gaining time in the process for making the pressure vessels, methods of the present disclosure can be used to make pressure vessels that may enclose temperature sensitive solid material. Indeed, since the non-cured pressure vessel, prefilled with the solid material is cured via an UV light source, or an EB source, whereby no higher temperature is required for curing, the vessel may be filled with temperature sensitive solid material.

[0020] Advantageously, prefilling the container (liner) with the solid material, which can be a battery system, a filtration system or a reactor system, prior to wrapping the container with the impregnated glass fiber reduces manufacturing effort and cost, since the container can be sealed (e.g., with end caps) prior to wrapping, avoiding costly pressure-resistant seals, such as flanges for the end caps. These end caps are advantageously wrapped with impregnated glass fiber as well to provide composite pressure vessels that may have improved pressure resistance.

[0021] Further it is surprisingly found that this method provides pressure vessels that prevents bending through, which can be caused by the weight of the solid material inside the vessel. Indeed, in case a thermo-curable composite material is used and the non-cured vessel enters the oven, the viscosity of the composite resin decreases at first instance because of the increase of the temperature. This may result in a pressure vessel that is deflected by gravity, especially when the solid material in the vessel is heavy and the vessel has a significant length so that gravity enables the non-cured vessel to deflect. The type of material of the liner may in some cases prevent this deflection, but using the method of the invention, the liner material can also be cheap thermoplastic material. The bending of the pressure vessel during oven curing may also lead to deforming of inner parts of the vessel, such as connections between the solid material and the liner.

[0022] Brief description of the drawings

[0023] Aspects of the present disclosure will be described in the following with reference to the appended drawings. In the drawings, corresponding components are designated with same reference numerals. Figure 1 illustrates a longitudinal sectional view of a container comprising a liner comprising a content of solid material which is here a battery system according to some embodiments.

[0024] Figure 2 represents a longitudinal sectional view of the container of Fig. 1 with a composite wrap formed with impregnated glass fiber to form a composite pressure vessel according to aspects of the present disclosure.

[0025] Figure 3 represents a longitudinal sectional view of a composite pressure vessel according to aspects of the present disclosure, enclosing a filtration system comprising hollow fiber membranes.

[0026] Figure 4 represents a cross sectional view of yet another composite pressure vessel according to aspects of the present disclosure, enclosing a filtration system comprising spiral membrane cartridges.

[0027] Figure 5 represents a longitudinal sectional view of a composite pressure vessel according to aspects of the present disclosure, enclosing a reactor system.

[0028] Detailed description

[0029] As described, a first aspect is related to a method for preparing a composite pressure vessel comprising the steps of

[0030] • providing a container comprising a liner having at least one open end, which liner comprises or encloses a content of solid material;

[0031] • providing a radiation curable liquid resin comprising ethylenically unsaturated compounds;

[0032] • providing glass fiber material;

[0033] • impregnating the glass fiber material with the radiation curable liquid resin;

[0034] • winding the container with the impregnated glass fiber to form a non-cured pressure vessel;

[0035] • bringing the non-cured pressure vessel under exposure of a UV light source or an EB source that is able to cure the radiation curable resin to provide the pressure vessel that comprises the solid material. In one embodiment the solid material comprises a configuration that functions by means of higher pressure; generates gas upon functioning and / or that uses gas for functioning. Typical examples of such configurations are filtration systems, reactor systems or battery systems. A filtration system, may use higher pressure for functioning, such as mechanical pressure that helps fluids passing through the filtration system. In some known battery systems, gas can be used or produced. In a preferred embodiment, the configuration is a battery system, such as a battery electrode stack system using metal hydrogen battery. While functioning of the metal hydrogen battery, hydrogen gas is produced or used depending on the charging cycle or discharging cycle of the battery. Since the pressure vessel prepared according to the method of the invention does not require increased temperatures for curing, it is possible that parts of the solid material are temperature sensitive.

[0036] Typically the pressure that is generated in the composite pressure vessel, while functioning, can be 1 bar or more such as at least 5, 50, 100, 300, 400, or even 500 bar or more. Advantageous working pressures within the composite pressure vessel according to the present disclosure are between 1 bar and 500 bar, advantageously between 5 bar and 400 bar, such as between 50 barand 300 bar. Composite pressure vessels accordingto the present disclosure advantageously have a burst pressure exceeding 500 bar. The burst pressure can also be lower, depending of the application and requirement of the pressure vessel.

[0037] In one embodiment the main portion of the liner has the form of a hollow cylinder with an internal diameter. The diameter is chosen so that the liner can fit around the solid material. The solid material may comprise several portions. It may be that some portions fit in the liner, by having a diameter or by having a size that is about or is slightly smaller than the internal diameter of the liner so that the solid material can slide in the liner, when bringing the solid material in the liner, in a way that there is direct contact between the liner and these portions of the solid material. It is also possible that some portions of the solid material that contact the liner are attached to the liner. The attachment can be by means of welding, including plastic welding, gluing or other means known in the art. This is to prevent movement of the solid material in the liner.

[0038] Advantageously, the container comprises a cap that fits on the open end of the liner. The cap may have a substantially hemispherical dome portion. Preferably, at least one cap comprises a connector element such as a pipe, valve, a feedthrough element, a discharge and / or a filling element, which connector element is attached through the cap and is extending outside the container. Often the container comprises two caps, that fit on opposite sides (ends) of the liner. Preferably the cap fits on the liner in a way that there is barely a gap or protrusion visible at the outside of the liner.

[0039] In case the container comprises only one cap, the liner advantageously has a substantially hemispherical dome portion at the opposite side of the cap. The top of the dome portion can be closed or can be open. When open, the top of the dome portion may comprise a connector element such as a pipe, valve, a feedthrough element, a discharge and / or a filling element, which connector element is attached through the cap and is extending outside the container.

[0040] The connector element can be an electrical connector element providing electrical connection to the solid material through the cap or a fluid communication element providing fluid communication with the solid material through the cap (e.g., a through-opening between the inside of the container and the outside). The connector element can be used for filling or discharging gas or liquids from the pressure vessel.

[0041] In some examples, the container comprises (encloses) as solid material a metal hydrogen battery configuration. The container can comprise at each side of the container a connector element which is a feedthrough element. At one end the feedthrough element can function as an anode terminal , and at the other terminal the feedthrough element can function as a cathode terminal. Such type of metal hydrogen battery is e.g. described in patent application No. US2024072338 Al. It is alternatively possible to provide both (electrical) connector elements at a same side or end of the container.

[0042] As is illustrated in Fig. 1, the battery system 102 is located in a liner 101, which is a hollow cylinder and has two caps 106, which are substantially hemispherical dome portions, that are located at opposite ends of the liner 101. The liner 101 and the caps 106 form the container 100. Through one cap 106 is a filling / discharge tube 104, that is attached to the cap 106. Through each cap 106, a feedthrough element 105 and 107 is attached, respectively. Feedthrough element 105 functions as an anode terminal and the feedthrough element 107 at the other side, functions as a cathode terminal. The portions 103 are connected with the battery system 102 and enable that the battery system 102 fits in the liner 101. The battery system 102 can comprise a stack of electrodes 121 and 122 connected between the anode terminal (element 105) and the cathode terminal (element 107).

[0043] Referring to Fig. 2, a composite pressure vessel 200 is obtained when the container 100 is wound with impregnated glass fiber which forms a composite wrap 110 overlying at least a portion of the liner 101 and possibly at least a portion of the caps 106. Advantageously, the composite wrap 110 wraps the liner 101 and the caps 106 completely, except for the feedthrough elements 104, 105, 107. The composite wrap 110 is cured via UV light or an EB source.

[0044] Referring to Fig. 3, a composite pressure vessel 300 comprises a container 100 formed by a liner 101 and caps 106 provided at one or both longitudinal ends of the liner 101. Like composite pressure vessel 200, the composite pressure vessel 300 comprises a composite wrap 110 formed by the impregnated glass fiber wrapping the container 100 and subsequently cured. The container 100 / liner 101 encloses a filtration system 310.

[0045] In some examples, like the one illustrated in Fig. 3, filtration system 310 comprises a bundle of hollow fiber membranes 311 the ends of which are potted in permeate manifolds 312, 313. Alternatively, one end of the hollow fiber membranes 311 can be potted in a permeate manifold and the opposite end can be closed and may be free to float or (fixedly) secured to a support. The hollow fiber membranes 311 are advantageously filtration membranes, such as microfiltration, nanofiltration or ultrafiltration membranes as known in the art. The hollow fiber membranes 311 comprise a tubular semipermeable membrane wall defining an internal lumen. The permeate manifolds 312, 313 are in fluid communication with the internal lumens of the hollow fiber membranes 311. In addition, the permeate manifolds are in fluid communication with one or more permeate outlets 314, 315 extending through cap 106 or alternatively through liner 101. The permeate manifolds 312, 313 are advantageously secured to the liner 101 and / or the cap 106 through one or more securing members 303.

[0046] Composite pressure vessel 300 further comprises one or more feedthrough elements 305, 307 extending through cap 106 or alternatively through liner 101. The feedthrough elements 305, 307 which can be arranged at opposite ends of the container 100, or at a same side, provide a fluid communication with the outer surfaces of the hollow fiber membranes 311. At least one of the feedthrough elements, e.g. feedthrough element 305, is a feed inlet. Another one of the feedthrough elements, e.g. feedthrough element 307, can be a feed (concentrate) outlet. As a result, the feed inlet and outlets can provide a flow of feed along the hollow fiber membranes 311.

[0047] In use, an advantageously liquid feed is supplied through the at least one feed inlet (e.g. feedthrough element 305). A pressure difference, referred to as transmembrane pressure, is applied across the semipermeable membrane wall of the hollow fiber membranes 311, i.e., between the outer surface and the interior (internal lumen) of the hollow fiber membranes, to perform filtration through the hollow fiber membranes. The pressure difference can be applied by any appropriate means, such as a feed pump upstream of the feed inlet(s) and / or a vacuum pump downstream the permeate outlet(s) 314, 315. Permeate (filtrate) is collected in the hollow lumens of the hollow fiber membranes 311 and conveyed to the permeate manifold(s) 312, 313 and further evacuated through respective permeate outlet(s) 314, 315.

[0048] It is alternatively possible to reverse the direction of flow in the filtration system 310. Particularly, the permeate outlets 315, 314 can function as feed inlet / outlet and the feedthrough elements 305, 307 are permeate outlets.

[0049] Manufacturing the composite pressure vessel according to the present disclosure advantageously enables the filtration system 310 to be enclosed in a composite pressure vessel having a high pressure resistance in an easy and economical way thereby reducing risk of membrane damage due to handling or elevated temperatures. As a result, high transmembrane pressures can advantageously be applied, particularly by increasing the pressure of the feed. This can result in improved permeate flow rates. In addition, for many types of filtration membranes, it is critical that these membranes remain wet during installation to avoid collapse of the internal pore structure when pressure is applied across the membrane. Since methods of manufacturing the composite pressure vessel according to the present disclosure can fully occur at room temperature there is significantly less chance that the membranes would dry out during curing compared to oven cured pressure vessels.

[0050] Referring to Fig. 4, in some examples, the filtration system 310 comprises one or a plurality of spiral membrane cartridges 320 enclosed in the container 100 / liner 101. Each spiral membrane cartridge 320 comprises a plurality of membrane sheets 321 that are spirally wound on a permeate collector tube 322. Within each cartridge, the plurality of spirally wound membrane sheets 321 are spaced apart creating an alternation of a permeate channel 323 and feed channel 324 separated by a membrane sheet 321. The permeate channel 323 is in fluid communication with the permeate collector tube 322. The feed channel 324 is in fluid communication with a feed inlet to the container 100, such as feedthrough element 305 (Fig. 3), and possibly with a feed outlet, such as feedthrough element 307 (Fig. 3). The space between membrane cartridges 320 in the container 100 can be filled with feed. As a result, the transmembrane pressure can be increased without damage to the membrane cartridges. Alternatively, the container 100 can enclose a single membrane cartridge 320 filling the internal volume of the liner 101, i.e., the liner 101 forms the membrane cartridge.

[0051] It will be appreciated that the permeate collector tubes 322 can be in fluid communication with a permeate manifold 312, 313 and associated permeate outlet 314, 315 as shown in the example of Fig. 3.

[0052] Referring to Fig. 5, a composite pressure vessel 400 comprises a container 100 formed by a liner 101 and caps 106 provided at one or both longitudinal ends of the liner 101. Like composite pressure vessel 200, the composite pressure vessel 300 comprises a composite wrap 110 formed by the impregnated glass fiber wrapping the container 100 and subsequently cured. The container 100 / liner 101 encloses a reactor system 410.

[0053] In some examples, the reactor system 410 comprises a reactor module 411 possibly secured to the container 100 (liner 101 and / or cap 106) through appropriate securing members 303. The reactor module 411 is advantageously a porous module enabling reagents to penetrate into the reactor module 411 and possibly to flow through the reactor module 411, from one end, e.g. inlet end 412, to an opposite end, e.g. outlet end 413. The inlet end 412 is advantageously in fluid communication with a feedthrough element 405 extending through the container 100 (cap 106 and / or liner 101) and configured as a reagent inlet. The outlet end 413 is advantageously in fluid communication with a feedthrough element 407 extending through the container 100 (cap 106 and / or liner 101) and configured as a reaction product outlet. Feedthrough elements 405, 407 can be arranged at opposite sides of the container 100, or alternatively at a same side.

[0054] The reactor module 411 is configured to make the reagents react to produce one or more reaction products. Advantageously, the reactor module 411 comprises a catalyst material 414 which is advantageously immobilized in the reactor module 411. The catalyst material 414 can be a porous and possibly monolithic structure with a catalyst compound embedded in the porous structure. Alternatively, the catalyst material 414 can be a granular material that is packed in a bed which is immobilized in the reactor module 411. The reactor module can further comprise appropriate further means for carrying out the reaction(s), such as (electrical) heating means.

[0055] In one embodiment, the liner and / or the cap is made from plastic, composite and / or metal. Suitable examples of plastic material are ABS, ABS / PC, AMMA, ASA, CA, CAB, EP, UF, CF, MF, MPF, PC, PF, PAN, PA, PE, HDPE, LDPE, LLDPE, UHMWPE, PET, PMMA, PP, PS, SB, PUR, PVC, RF, SAN, PBT, PPE, POM, PUR-RIM, SMC, BMC, PP-EPDM and UP (abbreviations in accordance with DIN 7728T1). Suitable examples of metal are thin sheeted iron, aluminum, stainless steel. The liner or cap can also be made from composite material, and is preferably thin walled composite material.

[0056] The glass fiber material is preferably continuous glass fiber material, which is suitable for use in filament winding. The glass fiber can be monofilament or multifilament.

[0057] Before the winding of the container occurs, the glass fiber material is impregnated with the radiation curable liquid resin. This impregnation can occur by immersing the glass fiber material directly in the radiation curable liquid resin, which is present in a bath. Another way of impregnation is by guiding the glass fiber on an impregnation roll that is partially immersed in a bath comprising the radiation curable liquid resin. By pulling on the glass fiber material, the roll turns and as the roll is covered with the liquid resin the glass fiber can be impregnated once it is in contact with the resin on the roll. It is also possible to use pre-impregnated glass fiber material which is known in the art as towpreg or pre-preg. The actinic radiation curable resin has already impregnated respectively the tows and the glass fiber textile in a pre-process.

[0058] As used herein "radiation curable resin" refers to a resin that can be, at least partially, preferably fully cured by UV light or radiation such as an electron beam (EB). As used herein "UV light radiation" is radiation via an ultraviolet light source including high or low-pressure mercury vapour lamps, cold cathode tubes, xenon lamps, black lights, ultraviolet lasers, and a flash lights, and LED light sources. Typically the wavelength of a UV light source is between 200 and 450 nm. With radiation using LED light sources is meant irradiation via a light-emitting diode source, whereby a semiconductor light source is used. Typically a wavelength of 365, 385, 395 or 405 nm is used. The electron beam principle consists of a vacuum chamber containing a cathode and anode between which a potential creates a steam of electrons. The electrons pass through a Titanium window, that maintains the vacuum and through an inert atmosphere to the substrate. The voltage of an EB system determines how far into a layer the electrons will travel. "Voltage" refers to the electric potential used to accelerate the electrons and determines the energy of the accelerated electrons that strike the substrate. For inerting, nitrogen is usually used. UV curable resins containing species (photoinitiator) which absorb UV light to create radicals and initiate the reaction. C=C double bonds are affected directly by EB irradiation to form radicals.

[0059] After impregnation, the container is winded with the impregnated glass fiber to form a noncured pressure vessel. The winding, also called filament winding occurs according to a predefined program to form a specific pattern and thickness. The winding pattern and composite thickness will determine the strength of the composite. Typically, the thickness of the pressure vessel wall, without the thickness of the container, is between 1 mm and 30 mm, preferably between 1 and 15 mm.

[0060] By bringing the non-cured pressure vessel underexposure of a UV light source or an EB source that is able to cure the radiation curable resin to provide the pressure vessel, the composite pressure vessel comprisingthe solid material is formed. It is preferable to bringthe non-cured pressure vessel under exposure of a UV light source or an EB source in a curing regime such that the energy is released slowly during curing. Preferably, the curing regime is set up in a way that the peak exotherm temperature of the curing is below a preset temperature. This way it is possible to control the heating of the pressure vessel that may be caused by the exothermic curing reaction. A person skilled in the art is aware of such curing regimes.

[0061] The radiation curable liquid resin in which the glass fiber material is impregnated, comprises ethylenically unsaturated compounds. As used herein, "ethylenically unsaturated compounds " refers to compounds comprising a polymerizable ethylenically unsaturated group. By polymerizable ethylenically unsaturated group is meant a carbon-carbon double bond which under influence of an initiator and / or irradiation, eventually in the presence of a photoinitiator, can undergo radical polymerization. Typically for UV curable resins the light is absorbed by a photoinitiator to create radicals and initiate reaction at carbon-carbon double bond, while EB irradiation initiates the reaction directly at the carbon-carbon double bonds.

[0062] The polymerizable ethy lenical ly unsaturated groups are generally chosen from (meth)acrylic groups. In the present invention, the term "(meth)acrylic" is to be understood as to encompass both acrylic and methacrylic groups present on compounds either separately or as mixtures thereof.

[0063] In one embodiment ethy lenica I ly unsaturated compounds comprise oligomer selected from the group consisting of amino (meth)acrylate oligomers, polyester (meth)acrylates, (poly)urethane (meth)acrylates; polyether (meth)acrylates, polycarbonate (meth)acrylate; epoxy (meth)acrylate and / or mixtures thereof.

[0064] Preferably, the ethylenica I ly unsaturated compounds have a molecular weight of from 500 to 5000 g / mol (500 to 5000 Daltons). Preferably, the ethylenically unsaturated compounds comprise at least two ethylenically unsaturated groups per molecule.

[0065] As used herein, the expression "molecular weight" can refer to the number-average molecular weight (Mn). The number-average molecular weight can be determined by conventional gel permeation chromatography (GPC) with Polystyrene standards EasyCal from Polymer Laboratories. A sample is dissolved (1.0% wt. / wt.) in tetrahydrofuran (THF) containing 0.5% toluene as Flow rate marker. Analysis is performed by liquid chromatography (Agilent 1260) equipped with 3 PLGel Mixed-D LS polystyrene-divinylbenzene GPC columns (300 X 7.5mm X 5pm). The components of the sample are separated by the GPC columns based on their molecular size in solution and detected by a Refractive Index detector. Data can be gathered and processed by Agilent GPC / SEC software. The sample is filtrated over 0.45 pm Whatman filter prior to injection into the GPC system.

[0066] Polyester (meth)acrylate oligomers are well known. These (meth)acrylated polyesters can be obtained by reacting a hydroxyl group-containing polyester backbone with (meth)acrylic acid, or by reacting a carboxyl group-containing polyester backbone with a hydroxy functional alkyl (meth)acrylate such as for example 2-hydroxyethyl acrylate, 2- or 3-hydroxypropyl acrylate, etc. or with glycidyl (meth)acrylate. The polyester backbone can be obtained in a conventional manner by polycondensation of at least one polyhydroxy alcohol, such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, hexanediol, trimethylolpropane, bisphenol A, pentaerythritol, isosorbide, etc, or / and the ethoxylates and / or propoxylates thereof, with at least one polycarboxylic acid or anhydride thereof such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, etc. By using unsaturated compounds for the polyester synthesis, such as for example fumaric acid, maleic acid, itaconic acid, etc., polyesters bearing both (meth)acrylic and ethylenic unsaturations in the polymer chain, can be obtained. In addition polylactones and / or polylactides can be used as polyester backbone. For example poly(e-caprolactone), polylactide and / or poly(lactide, caprolactone) can be obtained by ring-opening polymerization of e-caprolactone and / or lactide optionally in the presence of one or more polyhydroxy alcohols. Preferred are the polyester (meth)acrylate oligomers commercialized as EBECRYL® 450, EBECRYL® 452, EBECRYL® 5849, EBECRYL® 657, EBECRYL® 837, EBECRYL® 895, EBECRYL® 810, EBECRYL® 830, EBECRYL® 854, EBECRYL®1885, EBECRYL®1872 and EBECRYL® 870 all available from Allnex.

[0067] Polyether (meth)acrylate oligomers can be prepared by esterification of hydroxyfunctional polyethers with (meth)acrylic acid. Hydroxyfunctional polyethers can be obtained by ringopening homo- or copolymerization of cyclic ethers such as tetrahydrofuran, ethylene oxide and / or propylene oxide, or can be prepared by reacting polyhydroxy alcohols with ethylene and / or propylene oxide.

[0068] By epoxy (meth)acrylate oligomers is meant to designate the (meth)acrylic esters of epoxides, preferably polyepoxides, i.e. compounds comprising at least one, preferably at least two epoxide functions. Epoxy (meth)acrylate oligomers are generally obtained from the reaction of (meth)acrylic acid with epoxides. This reaction product can be elongated by reacting with a di- and / or polyisocyanate, such as hexamethylene-diisocyanate, isophorone-diisocyanate, toluene-diisocyanate, or an anhydride such as phthalic anhydride. The epoxides are generally chosen from epoxidized olefins, glycidyl esters of saturated or unsaturated carboxylic acids, glycidyl ethers of aromatic or aliphatic alcohols or polyols and from cycloaliphatic polyepoxides. Preferred epoxides are diglycidy lethers of aromatic and aliphatic diols and cycloaliphatic diepoxides such as diglycidyl ether of bisphenol-A, diglycidyl ether of bisphenol- F, diglycidylether of poly(ethylene oxide-co-propylene oxide), diglycidylether of polypropylene oxide, diglycidylether of hexanediol, diglycidylether of butanediol. Particularly preferred is diglycidyl ether of bisphenol-A. Also epoxidized natural oils or epoxidized phenolformaldehyde copolymers can be used. Examples of natural oils include soybean oil, linseed oil, peril la oil, fish oil, dehydrated castor oil, tung oil, coconut oil, corn oil, cottonseed oil, olive oil, palm oil, palm kernel oil, peanut oil, sunflower oil, safflower oil, castor oil. Examples of suitable epoxy acrylates include EBECRYL® 600, EBECRYL® 860, EBECRYL® 3420, EBECRYL® 608, EBECRYL® 3608, EBECRYL® 3702, EBECRYL® 3701, EBECRYL® 3700, EBECRYL® 6100 and EBECRYL®5848 all available from Allnex.

[0069] Polycarbonate (meth)acrylate oligomers are known. They can be prepared by esterification of hydroxyfunctional polycarbonates with (meth)acrylic acid.

[0070] (Poly) urethane (meth)acrylate oligomers can be prepared by reacting a di- and / or polyisocyanate, such as hexamethylene-diisocyanate, isophorone-diisocyanate, toluenediisocyanate, with hydroxyl functional (meth)acrylate. Use can be made exclusively of hydroxyl functional (meth)acrylates such as those mentioned above, but in order to extend the chain, mono- or polyhydroxy alcohols can also be added, such as those mentioned above for the synthesis of polyesters polyesters, polyethers or polycarbonates containing hydroxyl groups. Most preferred are urethane acrylates commercialized as EBECRYL® 1258, EBECRYL® 1259, EBECRYL® 220, EBECRYL® 2220, EBECRYL® 1290, EBECRYL® 1290N, EBECRYL® 1291, EBECRYL® 220, EBECRYL® 270, EBECRYL® 264, EBECRYL® 294 / 25HD, EBECRYL® 8254, EBECRYL® 4680, EBECRYL® 4513, EBECRYL® 8465, EBECRYL® 4666, EBECRYL® 4738, EBECRYL® 4740, EBECRYL® 4883, EBECRYL® 5129, EBECRYL® 8210, EBECRYL® 8602, EBECRYL® 8415, EBECRYL® 8814, EBECRYL® 225 all available from Allnex.

[0071] The ethylenically unsaturated compounds can also be amino (meth)acrylates. Examples of suitable amino (meth)acrylates include EBECRYL® 7100, EBECRYL® 80, EBECRYL® 81, EBECRYL® 83, EBECRYL® 85, EBECRYL® LEO 10551, EBECRYL® LEO 10552 & EBECRYL® LEO 10553, all available from Allnex.

[0072] As is known in the art, often monomers, also called reactive diluents are included in the radiation curable liquid resin to obtain the required viscosity. They usually have a molecular weight of 600 g / mol or less, preferably below 500 g / mol (500 Daltons). Monomers used can be mono- and / or poly-functional (meth)acrylates. Preferably, monomers are selected from mono(meth)acrylates, di(meth)acrylates and / or tri(meth)acrylates and / or tetraacrylate and / or pentaacrylates and / or hexaacrylates.

[0073] Examples of suitable compounds monomers include but are not limited to butyl(meth)acrylate, methyl(meth)acrylate, isobutyl(meth)acrylate, 2- ethylhexyl(meth)acrylate, cyclohexyl(meth)acrylate, n-hexyl(meth)acrylate, isobornyl(meth)acrylate, iso-octyl(meth)acrylate, n-lauryl(meth)acrylate, octyl / decyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, phenoxyethyl(meth)acrylate, nonylphenolethoxylate mono(meth)acrylate, 2-(-2- ethoxyethoxy)ethyl(meth)acrylate, 2-butoxyethyl(meth)acrylate, 1,6-hexanediol di(meth)acrylate (HDD(M)A), di or tri propylene glycol di(meth)acrylate (DPGD(M)A, TPGD(M)A), ethoxylated and / or propoxylated neopentylglycoldi(meth)acrylate, pentaerythritoltri(meth)acrylate (PETI(M)A) and the ethoxylated and / or propoxylated derivatives thereof, trimethylolpropanetri(meth)acrylate (TMPT(M)A) and the ethoxylated and / or propoxylated derivatives thereof, di-trimethylolpropanetri(meth)acrylate (diTMPT(M)A) glycerol tri(meth)acrylate and the ethoxylated and / or propoxylated derivatives thereof, the di(meth)acrylate of a dianhydrohexitol (like isosorbide di(meth)acrylate) and the ethoxylated and / or propoxylated derivatives thereof, phenylglycidylether(meth)acrylate and the ethoxylated or / and propoxylated derivatives thereof, the (meth)acrylates obtained from the esterification with (meth)acrylic acid of aliphatic glycidyl ethers, especially those wherein the alkyl chain comprises from 6 to 24 carbon atoms, more preferably from 8 to 18 carbon atoms, and / or of glycidyl esters of saturated and unsaturated carboxylic acids, especially the glycidyl esters of long chain alkyl carboxylic acids wherein the alkyl chain comprises from 6 to 24 carbon atoms, more preferably from 8 to 18 carbon atoms.

[0074] Preferred monomers are di- and / or tri-(meth)acrylated monomers such as 1,6-hexanediol di(meth)acrylate (HDD(M)A), di or tri propylene glycol di(meth)acrylate (DPGD(M)A, TPGD(M)A), trimethylolpropanetri(meth)acrylate (TMPT(M)A) and the ethoxylated and / or propoxylated derivatives thereof, pentaerythritoltri(meth)acrylate (PETI(M)A) and the ethoxylated and / or propoxylated derivatives thereof, glyceroltri(meth)acrylate and the ethoxylated and / or propoxylated derivatives thereof, the di(meth)acrylate of a dianhydrohexitol (like isosorbide di(meth)acrylate). Particularly preferred are dipropyleneglycol diacrylate (DPGDA), tripropyleneglycol diacrylate (TPGDA) and / or trimethylolpropane tri(meth)acrylate (TMPTA). Another preferred compound (I) is dipentaerythritol hexaacrylate (DPHA).

[0075] Also mixtures of monomers can be used.

[0076] In a very preferred embodiment, the ethy lenical ly unsaturated resin comprises oligomers that are a mixture of epoxy di(meth)acrylate and urethane (meth)acrylate and monomers. The monomers are preferably hydroxy (meth)acrylates, or a mixture of hydroxy (meth)acrylates and a difunctional (meth)acrylate.

[0077] In one embodiment, the ethylenically unsaturated resin comprises from 15 - 95 wt% of the oligomer (mixture) and from 5 to 85 wt% of the monomer (mixture) in view of the total weight of the oligomer and monomer.

[0078] In one specific example, the ethylenically unsaturated resin comprises from 10 - 50wt % epoxy di(meth)acrylate, from 5 - 40 wt% urethane (meth)acrylate and from 5-50 wt% hydroxy (meth)acrylate monomer and from 0-35 wt% of a difunctional (meth)acrylate monomer, in view of the total weight of the oligomers and monomers. It has been shown that this example provides excellent composite material for pressure vessels.

[0079] In another embodiment the radiation curable liquid resin further comprises a photoinitiator. Typically, the compositions of the invention comprise at least one photoinitiator. Any photoinitiator or mixtures thereof capable of generating free radicals when exposed to radiation may be used. Preferred photoinitiators include alpha-hydroxy ketone, for example 1-HydroxyCycloHexyl-Phenyl Ketone (CPK) and 2-Hydroxy-2-Methyl-l-Phenyl Propanone (HDMAP); acyl phosphine oxides, for example Bis(2,4,6-TrimethylBenzoyl)PhenylPhosphine Oxide; benzilketals such as 2,2-dimethoxy-2-phenylacetophenone,; benzophenones or derivatives thereof,

[0080] When present, the amount of photoinitiators in the resin is preferably from 0.01 to 10 wt%, preferably from 0.05 to 8 wt%, more preferably from 0.1 to 3 wt% relative to the total weight of the of the radiation curable liquid resin.

[0081] In one embodiment the viscosity of the radiation curable liquid resin at the temperature of impregnation of the glass fiber material is between 30 mPa.s and 1000 mPa.s, preferably between 50 mPa.s and 800 mPa.s, more preferably between 100 and 600mPa.s. The temperature of impregnation of the glass fiber material can be between 10°C and 80°C, preferably between 20 and 60°C, or is at ambient temperature such as between 25°C and 40°C.

[0082] In yet another embodiment the radiation curable liquid resin further comprises further additives such as wetting agents, defoaming agents, deaerator agents, agents to enhance glass fiber-resin interaction and or mixtures thereof. Examples thereof are TEGO® Foamex 810, TEGO® Airex 920, TEGO® Airex 922 available from Evonik; BYK® W 996, BYK® A355, BYK ®A515, BYK® 1790, BYK® C8000, BYK® C8001, BYK® C8003, BYK® P 9920, BYK® 9076 from BYK; Additol® XL 122N, Additol® VXW 6503N, EBECRYL®168, EBECRYL®170 available from allnex; Silquest™ A-171, Silquest™ A-174, Silquest™ A-186, Silquest™A-187 available from Momentive Performance Materials.

[0083] In one specific embodiment, the method according to the first aspect comprises a further step of pre-gelling the radiation curable liquid resin impregnated glass fiber, either after impregnation of the glass fiber and before winding; or during winding the container with the impregnated glass fiber. This can be done by exposing the impregnated glass fiber to UV light with a dosage and wavelength that is sufficient to initiate polymerization and increases the viscosity to a stage that the resin remains at liquid state. This stage can be defined by the viscosity of the radiation curable liquid resin being 300000 mPa.s (300 Pa.s) or less, preferably between 5000 mPa.s (5 Pa.s) and 250000 mPa.s (250 Pa.s) at a temperature of pre-gelling, preferably at room temperature, such as 25°C. This pre-gelling helps to improve control over the resin / fiber ratio in the composite and the ability for the impregnated glass fiber to remain at the same place where it was laid down during winding.

[0084] This pre-gelling occurs after short exposure to low intensity UV LED light and is typically done using UV irradiance with lower energy wavelengths such as above 365nm, preferably above 385nm.

[0085] In a second aspect, the invention is related to a composite pressure vessel obtained by the method according to the first aspect. Every embodiment and preferably descriptions also applies to this aspect of the invention.

[0086] In a third aspect, the invention is related to the use of the above described radiation curable resin comprising ethylenically unsaturated compounds for the method as described in the first aspect of the invention. Every embodiment and preferably descriptions also applies to this aspect of the invention, mutatus mutandis.

Claims

CLAIMS1. A method for preparing a composite pressure vessel (200, 300, 400), comprising the steps of• providing a container (100) comprising a liner (101) having at least one open end, wherein the liner encloses a solid material configured to function as a filtration system (310), a reactor system (410) or a battery system (102);• providing a radiation curable liquid resin comprising ethylenically unsaturated compounds;• providing glass fiber material;• impregnating the glass fiber material with the radiation curable liquid resin to obtain impregnated glass fiber;• winding the container with the impregnated glass fiber to form a non-cured pressure vessel;• bringing the non-cured pressure vessel under exposure of a UV light source or an EB source that is able to cure the radiation curable resin to provide the composite pressure vessel enclosing the solid material.

2. The method according to claim 1, wherein the filtration system, the reactor system or the battery system comprises a configuration that functions by means of higher pressure, generates gas upon functioning and / or uses gas for functioning.

3. The method according to claim 1 or 2, wherein the solid material is configured to function as a battery system (102) and comprises a battery electrode stack, preferably a metal hydrogen battery electrode stack.

4. The method according to claim 1 or 2, wherein the solid material is configured to function as a filtration system (310) and comprises a filtration membrane.

5. The method accordingto anyone of the preceding claims, wherein the container (100) comprisingthe linerfurthercomprises a cap (106) at each of the at least one open end of the liner.

6. The method according to the preceding claim, wherein a feedthrough element (104, 105, 107, 305, 307, 405, 407) is attached through the cap and is extending outside thecontainer, preferably wherein the feedthrough element is a connector element, a discharge element and / or a filling element.

7. The method according to the preceding claim, wherein the solid material is configured to function as a battery system (102) and wherein the composite pressure vessel comprises the feedthrough element configured to function as an anode terminal (105) or a cathode terminal (107).

8. The method according to claim 6, wherein the solid material is configured to function as a filtration system (310) and wherein the composite pressure vessel comprises a plurality of feedthrough elements being respectively a permeate outlet (314, 315) and a feed inlet and / or outlet (305, 307).

9. The method according to claim 6, wherein the solid material is configured to function as a reactor system (410) and wherein the composite pressure vessel comprises a plurality of feedthrough elements being respectively a reagent inlet (405) and a reaction product outlet (407).

10. The method according to anyone of the preceding claims, wherein the liner is made from plastic, composite and / or metal.

11. The method according to anyone of the preceding claims, further comprising pregelling the impregnated glass fiber after impregnation of the glass fiber and before winding, or during winding the container with the impregnated glass fiber, wherein pre-gelling the impregnated glass fiber comprises exposing the impregnated glass fiber to UV light with a dosage and a wavelength to initiate polymerization to increase a viscosity of the radiation curable liquid resin to a stage in which the radiation curable liquid resin remains in a liquid state and wet.

12. The method according to the preceding claim, wherein the stage is defined by the viscosity ofthe radiation curable liquid resin at room temperature being300000 mPa.s or less, preferably between 5000 mPa.s and 250000 mPa.s.

13. The method according to anyone of the preceding claims wherein the radiation curable liquid resin comprises oligomers selected from the group consisting of amino (meth)acrylate oligomers, polyester (meth)acrylates, (poly)urethane (meth)acrylates; polyether (meth)acrylates, polycarbonate (meth)acrylate; epoxy (meth)acrylate and / or mixtures thereof;14. The method according to claim 13 wherein the radiation curable liquid resin further comprises monomers selected from mono- and / or poly-functional (meth)acrylates, preferably having a molecular weight of 600 g / mol or less, preferably below 500g / mol.

15. The method according to claim 13 or 14, wherein the radiation curable liquid resin further comprises a photoinitiator, preferably at a concentration of from 0.01 to 10 wt%, preferably from 0.05 to 8 wt%, more preferably from 0.1 to 3 wt% relative to the total weight of the radiation curable liquid resin.

16. The method accordingto any one of the claims 13 to 15 , wherein the radiation curable liquid resin further comprises wetting agents, defoaming agents, agents to enhance glass fiber-resin interaction, or mixtures thereof.

17. The method according to anyone of the preceding claims wherein a viscosity of the radiation curable liquid resin at a temperature of impregnation of the glass fiber material is between 30 mPa.s and 1000 mPa.s, preferably between 50 mPa.s and 800 mPa.s, more preferably between 100 and 600mPa.s.

18. Composite pressure vessel obtained by the method according to anyone of the preceding claims.

19. Use of a radiation curable resin comprising ethylenically unsaturated compounds for manufacturing a composite pressure vessel (200, 300, 400), comprising impregnating a glass fiber material with the radiation curable resin to obtain impregnated glass fiber, winding a container (100) comprising a liner (101) prefilled with a solid material configured to function as a filtration system (310), a reactor system (410) or a battery system (102) with the impregnated glass fiber to form a non-cured pressure vessel and exposing the non-cured pressure vessel to UV light or an EB source to cure the radiation curable resin and thereby obtain the composite pressure vessel filled with the solid material.

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