METHOD FOR MANUFACTURING A HOLLOW BODY BY FILAMENT WINDING, MANUFACTURING SYSTEM AND HOLLOW BODY OBTAINED

Abstract

The invention relates to a method (100) for manufacturing a hollow body, preferably an axisymmetric hollow body, comprising a layer of composite material, said method comprising the following steps: a step of supplying (110) a polymer composition; a step of impregnating (120) a fibrous material with the polymer composition; a step of winding (130) the impregnated fibrous material around a mandrel, said winding being carried out for a winding time; and a step of heating (150) the wound fibrous material, said heating being carried out for a heating time in order to polymerize the layer of composite material; wherein: the polymer composition comprises a combination of a photoinitiator and a heat-activated initiator; it further comprises a step of exposing (140) the polymer composition to UV light; and the heating time is shorter than the winding time. FIGURE 1

Description

Title of the invention: METHOD FOR MANUFACTURING A HOLLOW BODY BY FILAMENT WINDING, MANUFACTURING SYSTEM AND HOLLOW BODY OBTAINED Scope of the invention

[0001] The present invention relates to the field of filament winding and the production of hollow bodies, such as axisymmetric hollow bodies, by filament winding. The manufactured hollow bodies can be used as high-pressure gas storage tanks.

[0002] In particular, this invention proposes a new method for manufacturing a hollow body comprising a layer of composite material, a new system for manufacturing this material, and a hollow body obtainable by this method. Description of the prior art

[0003] Filament winding technology has a wide range of applications, making a significant contribution to various industries thanks to its unique capabilities, particularly in the production of composite pressure vessels and pipes. This filament winding technology generally involves winding fibrous materials, often pre-impregnated with a polymer composition, around a mandrel to obtain the desired shape. This process is primarily used to create hollow cylindrical structures such as high-pressure vessels. The mechanical strength of the structure depends not only on the composition of the composite material, but also on process parameters such as the winding angle, fiber tension, resin type, and curing cycle (Blachut, et al., Composite Structures, Volume 304, Part 1, 15 January 2023, 116337).

[0004] The application of filament winding technology is particularly important in the production of high-pressure tanks, such as those used to store gases under high pressure. These tanks generally require materials with a high strength-to-weight ratio, and filament winding provides an efficient way to use materials such as carbon or glass fibers combined with polymer compositions to meet these requirements. Filament winding technology is one of the new manufacturing practices that has revolutionized the doctrine of gas storage and transportation. Over the past few decades, various pressure vessels have evolved from metal to fiber-reinforced tanks, primarily for reasons of weight reduction and high pressure.For example, type 4 composite pressure vessels (CPVs) can reduce the weight of combustible gas tanks by 75% compared to . to metal tanks. Several advances have been made in the applications of filament winding, addressing various process parameters, optimization techniques and challenges in the context of high pressure gas storage and cryogenic fluids (Azeem et al., Journal of Energy Storage, Volume 49, May 2022, 103468).

[0005] In particular, the integration of computer numerical control (CNC) systems has been a significant advancement in filament winding technology. CNC technology has enabled greater precision in controlling key winding parameters, such as fiber tension, winding angle, and speed. This precision contributes to the structural integrity and uniformity of high-pressure vessels, which directly impacts their safety and performance. This advancement also makes it possible to create more complex shapes, crucial for high-pressure vessel applications. The integration of advanced technologies such as automated fiber placement and continuous fiber structural 3D printing has further expanded the range of applications for filament winding.Furthermore, the selection of materials (such as glass, carbon, or aramid fibers) and their combination with various polymer systems are crucial in determining the strength and functionality of the final product.

[0006] The process, while efficient, still lacks a streamlined approach for the rapid production of high-pressure tanks. The complexity of the manufacturing process, combined with the need for precise control of various parameters, contributes to longer production times. Furthermore, the increasing use of filament winding technology is placing growing emphasis on reducing its environmental impact. The manufacturing process, involving polymers and fibers, can have a considerable ecological footprint. Therefore, it is urgent to develop more environmentally sustainable practices in this area.

[0007] Recent innovations have focused on developing more environmentally friendly polymer systems and on processes for recycling composite materials. Efforts are also being made to minimize waste and energy consumption during the manufacturing process. These advances aim to align filament winding technology with the broader objective of sustainable industrial practices.

[0008] However, there is still a need for a solution to address the need to balance manufacturing efficiency and environmental considerations. Summary of the invention

[0009] The following is a simplified summary of selected aspects, embodiments, and examples of the present invention to provide a basic understanding of the invention. However, the summary does not constitute a complete overview of all aspects, embodiments, and examples of the invention. The sole purpose of the summary is to present selected aspects, embodiments, and examples of the invention in a concise form as an introduction to the more detailed description of the aspects, embodiments, and examples of the invention that follows the summary.

[0010] The invention aims to overcome the drawbacks of the prior art. In particular, the invention proposes a method for manufacturing a hollow body, preferably an axisymmetric hollow body, comprising a layer of composite material, said method comprising the following steps: - a step of making a polymer composition available; - a step of impregnating a fibrous material with the polymer composition; - a step of winding the impregnated fibrous material around a mandrel, said winding being carried out for a winding time; and - a heating step of the wound fibrous material, said heating being carried out for a heating time to polymerize the layer of composite material; in which: - the polymer composition comprises a combination of a photoinitiator and a heat-activated initiator; - it further includes a step of exposing the polymer composition to UV light; and - the heating time is shorter than the winding time.

[0011] The process developed by the inventors improves production efficiency and allows for easier and faster production with more environmentally sustainable practices.

[0012] According to other optional elements of the process according to the invention, it may optionally comprise one or more of the following features, alone or in combination: - the heating step of the wound fibrous material is carried out at a heating temperature and the heat-activated initiator has a half-life at the heating temperature of the heating step which is shorter than the winding time, - the impregnation step is carried out at an impregnation temperature, and the impregnation temperature is chosen such that the initiator is activated by the heat has a half-life at the impregnation temperature greater than the winding time, The heating stage is carried out at a heating temperature, and the heat-activated initiator has a half-life at the heating temperature at most equal to the heating time. The heat-activated initiator is chosen from among heat-activated initiators having a half-life at the heating temperature at least 10 times shorter than its half-life at the winding temperature. The heat-activated initiator is chosen from heat-activated initiators having a half-life of less than 1 hour at a temperature of 150 °C; the heating step is carried out at a temperature less than or equal to 100 °C. The polymer composition has a dynamic viscosity greater than 10 mPa*s as measured at 25 °C. The polymer composition has a dynamic viscosity of less than 5,000 mPa*s as measured at 25 °C. Preferably, the polymer composition has a dynamic viscosity of more than 10 mPa*s and less than 5,000 mPa*s as measured at 25 °C. The fibrous material is chosen from either carbon fibers or glass fibers. The contact between the impregnated fibrous material and the mandrel can be direct or indirect. The heating step is carried out while the wound fibrous material is stationary. The heating stage is carried out while the wound fibrous material is positioned vertically, i.e., the axis of symmetry of the wound fibrous material is perpendicular to the ground. It also includes, after the heating stage, a stage of coating the composite material layer, The hollow body is a tube, a storage tank, a pressure vessel, a pipe, a pressurized or high-pressure storage tank, utility poles, a drive shaft, or wind turbine blades. The hollow body comprises several layers, including a lining, The polymer composition is a thermoplastic composition. The polymer composition includes a thermoplastic polymer from the family composed of polyamide, polyurea, polyacrylic, poly(aryletherketones), polyimides, aromatic polyetherimides, polysulfides, polysulfones, polyolefins, poly(lactic acid), polyvinyl, polyvinyl alcohol, fluoropolymers, styrenes, cellulosics, polyester and / or polycarbonates, - the thermoplastic composition includes a (meth)acrylic polymer, - the composite material layer comprises 20% to 50% by volume of a polymer composition including (meth)acrylic polymers and 50% to 80% by volume of fibers, - the composite material layer comprises at most 35% by volume of a thermoplastic matrix comprising a (meth)acrylic polymer and at least 65% by volume of fibers.

[0013] According to another aspect, the invention may also relate to a hollow body that can be obtained by a process according to the invention. Such a structure has better reinforcement and may have a longer lifespan.

[0014] According to another aspect, the invention may also relate to the use of a hollow body according to the invention for gas storage, gas transport, pressure vessels, water transport, wastewater transport, aerospace components or automotive components.

[0015] According to another aspect, the invention may also relate to a system for manufacturing a hollow body comprising a layer of composite material, said system comprising: - an impregnation device configured to wet a fibrous material with a polymer composition, said polymer composition comprising a combination of a photoinitiator and a heat-activated initiator, - at least one UV lamp configured to expose the polymer composition to UV light, - a winding device configured to wind the fibrous material around a mandrel according to a winding duration, - a heating device configured to heat the wound fibrous material in order to polymerize the layer of composite material according to a heating time, the heating time being shorter than the winding time.

[0016] Preferably, the system comprises at most as many heating devices as winding devices.

[0017] Preferably, the heating device and the winding device are configured to operate continuously. Brief description of the drawings

[0018] The foregoing and other objects, elements and advantages of the present invention will become clearer upon reading the following detailed description considered in conjunction with the accompanying drawings in which:

[0019] [Fig.1] represents a flow diagram of a process according to an embodiment of the present invention.

[0020] Several aspects of the present invention are described by reference to functional diagrams and / or principle diagrams of processes and devices according to embodiments of the invention.

[0021] In the figures, the functional diagrams and / or the principle diagrams show the architecture, the functionality and the possible implementation of devices or systems or processes, according to several embodiments of the invention.

[0022] For this purpose, each box in the functional diagrams or the principle diagrams can represent a system, a device, a module which includes several executable instructions to implement the specified logic function(s).

[0023] In some implementations, the functions associated with the box may appear in a different order than shown in the drawings.

[0024] For example, two boxes presented successively can be executed in a substantially simultaneous manner, or boxes can sometimes be executed in reverse order, depending on the functionality involved.

[0025] Each box in the functional diagrams or principle diagrams, and combinations of boxes in the functional diagrams or principle diagrams can be implemented by special systems which perform the specified functions or actions or perform specific combinations of equipment and computer instructions. Detailed description

[0026] Exemplary embodiments of the invention will now be described.

[0027] The term "polymer" means either a copolymer, a homopolymer, or a block copolymer. The term "copolymer" refers to a polymer comprising several different monomer units, and the term "homopolymer" refers to a polymer comprising identical monomer units. The term "block copolymer" means a polymer comprising one or more uninterrupted blocks of each of the distinct polymer species, the polymer blocks being chemically different from one another and being linked together by a covalent bond. These polymer blocks are also called polymer blocks.

[0028] The term “polymer composite”, as used in the invention, refers to a multicomponent material comprising at least two immiscible components, among which at least one component is a polymer and the other component can, for example, be a fibrous reinforcement.

[0029] For the purposes of this invention, "fibrous reinforcement" or "fibrous substrate" or "fibers" means several fibers, unidirectional fibers or braids, or a continuous filament mat, fabrics, felts, or nonwovens which may take the form of strips, sheets, braids, strands or pieces.

[0030] The term "monomer", in the sense of the invention, may refer to a molecule that can undergo polymerization.

[0031] For the purposes of the invention, the expression "thermoplastic polymer" may refer to a polymer that is generally solid at room temperature, that may be crystalline, semi-crystalline or amorphous, and that softens upon a rise in temperature, in particular after exceeding its glass transition temperature (Tg), and that is fluid at a higher temperature, and / or that may exhibit a clear melting upon exceeding its so-called melting temperature (Tf) (when it is semi-crystalline), and that becomes solid again when the temperature falls below its melting point and below its glass transition temperature.This also applies to thermoplastic polymers lightly crosslinked by the presence of multifunctional monomers or oligomers in the formulation of (meth)acrylate "syrup", in a mass percentage preferably less than 10%, preferably less than 5%, and even better less than 2%, and which may be at least 0.5%, which can be thermoformed when heated above the softening temperature. The Tg and Tm values ​​can be determined by differential scanning calorimetry (DSC) according to standards EN 11357-2:2013 and EN 11357-3:2013, respectively.

[0032] The expression "polymer composition" may refer to a composition comprising polymers and / or polymer precursors.

[0033] The expression "thermoplastic composition" may refer to a composition comprising a thermoplastic polymer and / or a thermoplastic polymer precursor.

[0034] The expression "(meth)acrylic monomer" can refer to any type of acrylic and methacrylic monomer.

[0035] The expression "(meth)acrylic polymer" may refer to a polymer comprising essentially (meth)acrylic monomers which represent at least 50% by weight or more of the (meth)acrylic polymer.

[0036] The term “PMMA”, in the sense of the invention, may refer to homopolymers and copolymers of methyl methacrylate (MMA), the weight ratio between MMA and PMMA preferably being at least 70% by weight for the MMA copolymer.

[0037] The term "axisymetric" in the context of the invention may refer to a body, preferably a hollow body, which is symmetrical about a central axis.

[0038] The term “matrix” can refer to a material that serves as a binder and can transfer forces to the fibrous reinforcement.

[0039] The term “polymer matrix” may include polymers, but may also encompass other compounds or materials.

[0040] The term “(meth)acrylic polymer matrix” can refer to all types of acrylic and methacrylic compounds, polymers, oligomers, copolymers or block copolymers. However, it would not depart from the scope of the invention if the (meth)acrylic polymer matrix comprised up to 10% by weight, preferably less than 5% by weight, of other non-acrylic monomers, selected for example from the following group: butadiene, isoprene, styrene, substituted styrene such as α-methylstyrene or β-butylstyrene, cyclosiloxanes, vinylnaphthalenes and vinylpyridines.

[0041] The term “initiator” or “precursor”, in the sense of the invention, may refer to a compound that can start / initiate the polymerization of a monomer or monomers.

[0042] The term “polymerization”, in the sense of the invention, may refer to the process of transforming a monomer or a mixture of monomers into a polymer.

[0043] The abbreviation "phr" can denote parts by weight per hundred parts of composition. For example, 1 phr of initiator in the composition means that 1 kg of initiator is added to 100 kg of composition.

[0044] The abbreviation "ppm" can denote parts by weight per million parts of composition. For example, 1000 ppm of a compound in the composition means that 0.1 kg of the compound is present in 100 kg of the composition.

[0045] The term "approximately", as used in the description, may permit a degree of variability in a value or range, for example within 10%, within 5%, or within 1% of a stated value or a stated limit of a range.

[0046] The term “a” or “an” used herein may refer to “one or more”, unless explicitly stated otherwise.

[0047] As mentioned, the current process and filament winding do not allow for easier and faster production. Furthermore, current processes do not guarantee a balance between manufacturing efficiency and environmental considerations.

[0048] Current manufacturing processes for hollow tanks, such as pressure vessels or storage containers, are often very inefficient due to production bottlenecks. These bottlenecks can result from various factors, including, but not limited to, limitations inefficiencies in materials handling, process delays, or suboptimal design and manufacturing techniques are common. Furthermore, these conventional processes typically involve significant energy consumption and environmental impact, leading to increased operating costs and environmental concerns. There is an urgent need to develop an improved manufacturing process that not only addresses these inefficiencies and production bottlenecks but also promotes a more sustainable and environmentally friendly approach. The present invention aims to provide a novel solution to these problems by introducing an innovative method for manufacturing hollow tanks that significantly improves production efficiency and reduces environmental impact.

[0049] According to a first aspect, the invention relates to a method 100 for manufacturing a hollow body, preferably an axisymmetric hollow body, comprising a layer of composite material.

[0050] The hollow body, preferably axisymmetric, can correspond to a container, a tank or a reservoir having an internal volume.

[0051] As illustrated in [Fig.1], a process 100 according to the invention comprises the following steps: supplying 110 of a polymer composition; impregnating 120 of a fibrous material with the polymer composition; winding 130 of the impregnated fibrous material onto a mandrel; exposing 140 of the polymer composition to UV light and heating 150 of the wound fibrous material.

[0052] A process 100 according to the invention may further include a cooling step 160 of the composite material layer and / or a coating step 170 of the composite material layer.

[0053] As mentioned, a process 100 according to the invention includes a step of supplying 110 a polymer composition.

[0054] the polymer composition comprises a combination of a photoinitiator and a heat-activated initiator;

[0055] The combination of at least two initiators, each working on at least two modalities, makes it possible to reduce the total duration of the manufacturing process and to improve the surface properties of the hollow body produced. Photoinitiator

[0056] As it comprises at least one photoinitiator, the polymer composition according to the invention can be polymerized or crosslinked under the effect of electromagnetic radiation.

[0057] The composition according to the invention may comprise from 0.1 percent to 5 percent by weight, preferably from 0.5 percent to 3 percent by weight, or even more preferably 1 percent to 2 percent by weight of photoinitiator(s) relative to the total weight of the polymer composition.

[0058] The photoinitiator can be any radical photoinitiator known to those skilled in the art, in particular any radical photoinitiator known to those skilled in the art. Under the action of UV / visible radiation, the radical photoinitiator generates radicals that will be responsible for initiating the photopolymerization reaction and, in particular, increase the efficiency of the photopolymerization reaction. It is, of course, chosen according to the light source used, based on its ability to efficiently absorb the selected radiation. It will be possible, for example, to choose the appropriate radical photoinitiator based on its UV / visible absorption spectrum. Advantageously, the radical photoinitiator is suitable for use with irradiation sources emitting in the area close to the visible region. Advantageously, the UV or visible radiation source can be an LED or a UV lamp.

[0059] Preferably, said at least one radical photoinitiator is chosen from the group consisting of: - Type I radical photoinitiators selected from: • the family of acetophenones and alkoxyacetophenones, such as, for example, 2,2-dimethoxy-2-phenylacetophenone and 2-diethyl-2-phenylacetophenone; • the hydroxyacetophenone family, such as, for example, 2,2-dimethyl-2-hydroxyacetophenone, 1-hydroxycyclohexyl phenylketone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone and 2-hydroxy-4'-(2-hydroxypropoxy)-2-methylpropiophenone; • the alkylaminoacetophenone family, such as, for example, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, 2-benzyl-2-(dimethylamino)-4-morpholinobutyrophenone and 2-(4-methylbenzyl)-2-(dimethylamino)-4-morpholinobutyrophenone; • the family of benzoin ethers, such as, for example, benzil, benzoin methyl ether and benzoin isopropyl ether; • the family of phosphine oxides, such as, for example, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), ethyl(2,4,6-trimethylbenzoyl)phenylphosphine oxide (TPO-L) and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylphenylphosphine oxide (BAPO); • the family of metallocenes, such as, for example, ferrocene, bis(eta5-2,4-cyclopentadien-l-yl)bis(2,6-difluoro-3-(lH- pyrrol-l-yl)phenyl)titanium and (cumene)(cyclopentadienyl)he iron xafluorophosphate; - Type II radical photoinitiators selected from: • the benzophenone family, such as, for example, 4-phenylbenzophenone, 4-(4'-methylphenylthio)benzophenone or l[4-[(4-benzoylphenyl)thio]phenyl]-2-methyl-2-[(4-methylphenyl)sulfonyl]-1-propanone; • the thioxanthone family, such as, for example, risopropylthioxanthone (ITX), 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2-chlorothioxanthone and l-chloro-4-isopropylthioxanthone; • the quinone family, such as, for example, anthraquinones, including 2-ethylanthraquinone, and camphorquinones; • the family of benzoylformate esters, such as, for example, methyl benzoylformate; • the family of dibenzylidene ketones, such as, for example, p-dimethylamino ketone; • the coumarin family, such as, for example, 5-methoxy- and 7-methoxycoumarin, 7-diethylaminocoumarin and N-phenylglycine coumarin; - radical photoinitiators from the dye family, such as, for example, triazines, fluorones, cyanines, safranins, 4,5,6,7-tetrachloro-3',6'-dihydroxy-2', 4',5',7'-tetraiodo-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one, pyryliums and thiopyryliums, thiazines, flavins, pyronines, oxazines or rhodamines; - and their mixtures.

[0060] More preferably, said at least one radical photoinitiator is chosen from the group consisting of: - Type I radical photoinitiators selected from: • the family of acetophenones and alkoxyacetophenones, such as, for example, 2,2-dimethoxy-2-phenylacetophenone and 2-diethyl-2-phenylacetophenone; • the hydroxyacetophenone family, such as, for example, 2,2-dimethyl-2-hydroxyacetophenone, 1-hydroxycyclohexyl phenylketone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone and 2-hydroxy-4'-(2-hydroxypropoxy)-2-methylpropiophenone; • the alkylaminoacetophenone family, such as, for example, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, 2-benzyl-2-(dimethylamino)-4-morpholinobutyrophenone and 2-(4-methylbenzyl)-2-(dimethylamino)-4-morpholinobutyrophenone; • the family of benzoin ethers, such as, for example, benzil, benzoin methyl ether and benzoin isopropyl ether; • the family of phosphine oxides, such as, for example, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), ethyl(2,4,6-trimethylbenzoyl)phenylphosphine oxide (TPO-L) and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylphenylphosphine oxide (BAPO); • the family of metallocenes, such as, for example, ferrocene, bis(eta5-2,4-cyclopentadien-l-yl)bis(2,6-difluoro-3-(lH-pyrrol-l-yl)phenyl)titanium and (cumene)(cyclopentadienyl)he iron α-fluorophosphate; Type II radical photoinitiators selected from: • the benzophenone family, such as, for example, 4-phenylbenzophenone, 4-(4'-methylphenylthio)benzophenone or l[4-[(4-benzoylphenyl)thio]phenyl]-2-methyl-2-[(4-methylphenyl)sulfonyl]-1-propanone; • the thioxanthone family, such as, for example, risopropylthioxanthone (ITX), 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2-chlorothioxanthone and l-chloro-4-isopropylthioxanthone; • the family of benzoylformate esters, such as, for example, methyl benzoylformate; • the family of dibenzylidene ketones, such as, for example, p-dimethylamino ketone; • the coumarin family, such as, for example, 5-methoxy- and 7-methoxycoumarin, 7-diethylaminocoumarin and N-phenylglycine coumarin; radical photoinitiators of the dye family, such as, for example, triazines, fluorones, cyanines, safranins, 4,5,6,7-tetrachloro-3',6'-dihydroxy-2', 4',5',7'-tetraiodo-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one, pyryliums and thiopyryliums, thiazines, flavins, pyronines, oxazines or rhodamines; and their mixtures.

[0061] More preferably, the radical photoinitiator is chosen from among the following radical photoinitiators: - the family of phosphine oxides, such as, for example, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), ethyl(2,4,6-trimethylbenzoyl)phenylphosphine oxide (TPO-L) and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylphenylphosphine oxide (BAPO); - the thioxanthone family, such as, for example, risopropylthioxanthone (ITX), 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2-chlorothioxanthone and l-chloro-4-isopropylthioxanthone; the radical photoinitiator is even more preferentially chosen from diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), ethyl-(2,4,6-trimethylbenzoyl)phenylphosphine oxide (TPO-L) and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylphenylphosphine oxide (BAPO).

[0062] For example, when the UV or visible radiation source is an LED or UV lamps, the radical photoinitiator can be chosen from 2,4,6-trimethylbenzoyldiphenylphosphine or TPO, available, for example, from Lambson under the trade name Speedcure® TPO (CAS: 75980-60-8), ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate or TPO-L, available, for example, from Lambson under the trade name Speedcure® TPO-L (CAS: 84434-11-7), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide or BAPO (CAS: 162881-26-7), available, for example, from BASF under the trade name Irgacure® 819, the 2-benzyl-2-dimethylamino-l-(4-morpholinophenyl)-1-butanone (CAS: 119313-12-1) available, for example, from BASF under the trade name Irgacure(R) 369, 2-methyl-l[4-(methylthio)phenyl]-2-(4-morpholinyl)-l-propanone (CAS: 71868-10-5) available, for example, from BASF under the trade name Irgacure(R) 907,1-Hydroxycyclohexyl phenylketone (CAS: 947-19-3), available, for example, from BASF under the trade name Irgacure(R) 184, 2-Isopropylthioxanthone or ITX (CAS: 5495-84-1), available, for example, under the trade name Speedcure(R) 2-ITX, or mixtures thereof. Heat-activated initiator

[0063] The polymer composition may include a heat-activated precursor or initiator that can start the polymerization of monomers in the polymer composition when exposed to a specific temperature range. The heat-activated initiator is preferably a heat-activated radical initiator.

[0064] In a first preferred embodiment, the heat-activated initiator is chosen from among the heat-activated initiators whose half-life at the temperature heating is at least 10 times shorter than its half-life at winding temperature.

[0065] In a second preferred embodiment, the heat-activated initiator is chosen from among heat-activated initiators whose half-life at the heating temperature is at least 20 times shorter than its half-life at the winding temperature,

[0066] In a third preferred embodiment, the heat-activated initiator is chosen from among heat-activated initiators whose half-life at the heating temperature is at least 40 times shorter than its half-life at the winding temperature,

[0067] In a fourth preferred embodiment, the heat-activated initiator is chosen from among heat-activated initiators whose half-life at the heating temperature is at least 80 times shorter than its half-life at the winding temperature.

[0068] The heat-activated initiator can be selected from heat-activated initiators having a half-life of less than 1 hour at a temperature of 150 °C. In a first preferred embodiment, the heat-activated initiator is selected from heat-activated initiators having a half-life of less than 1 hour at a temperature of 125 °C. In a second preferred embodiment, the heat-activated initiator is selected from heat-activated initiators having a half-life of less than 1 hour at a temperature of 100 °C. In a third preferred embodiment, the heat-activated initiator is selected from heat-activated initiators having a half-life of less than 1 hour at a temperature of 95 °C.

[0069] Heat-activated initiators can be chosen from compounds comprising a peroxy group or compounds comprising an azo group, and preferably from compounds comprising a peroxy group.

[0070] Preferably, the compound comprising a peroxy group comprises from 2 to 30 carbon atoms.

[0071] Preferably, the compound comprising a peroxy group is chosen from diacyl peroxides, peroxyesters, peroxydicarbonates, dialkyl peroxides, peroxyacetals, a hydroperoxide or a peroxyketal.

[0072] The heat-activated initiator is selected from diisobutyryl peroxide, cumyl peroxyneodecanoate, di(3-methoxybutyl) peroxydicarbonate, 1,1,1,3-tetramethylbutyl peroxyneodecanoate, cumyl peroxyneoheptanoate, di-n-propyl peroxydicarbonate, tert-amyl peroxyneodecanoate, di-sec-butyl peroxydicarbonate, diisopropyl peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di(2- ethylhexyl), tert-amyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, di-n-butyl peroxydicarbonate, diketyl peroxydicarbonate, dimyristyle peroxydicarbonate, 1,1,1,3-tetramethylbutyl peroxypivalate, tert-butyl peroxyneoheptanoate, tert-amyl peroxypivalate, tert-butyl peroxypivalate, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, didecanoyl peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, 1,1,1,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2-ethylhexanoate tert-amyl, dibenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxydiethyl acetate, tert-butyl peroxyisobutyrate, l,l-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, l,l-di(tert-amylperoxy)cyclohexane, l,l-di(tert-butylperoxy)cyclohexane, tert-amyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxyacetate, peroxy-3,5,tert-butyl 5-trimethylhexanoate, 2,2-di(tert-butylperoxy)butane, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxy-2-ethylhexylcarbonate, tert-amyl peroxybenzoate, tert-butyl peroxyacetate, butyl 4-di(tert-butylperoxy)valerate, tert-butyl peroxybenzoate, di-tert-amyl peroxide, dicumyl peroxide, di(2-tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl and cumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, di-tert-butyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-l,4,7-triperoxonane, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azodi(2-methylbutyronitrile), azobisisobutyramide, 2,2'-azobis(2,4-dimethylvaleronitrile), l,r-azodi(hexahydrobenzonitrile) or 4,4'-azobis(4-cyanopentanoic acid).

[0073] Preferably, the heat-activated initiator is selected from cumyl peroxydecanoate, di(3-methoxybutyl) peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxydecanoate, cumyl peroxyneoheptanoate, di-n-propyl peroxydicarbonate, tert-amyl peroxydecanoate, di-sec-butyl peroxydicarbonate, diisopropyl peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, tert-amyl peroxydecanoate, tert-butyl peroxydecanoate, di-n-butyl peroxydicarbonate, diketyl peroxydicarbonate, peroxydicarbonate dimyristyle, 1,1,3,3-tetramethylbutyl peroxypivalate, tert-butyl peroxyneoheptanoate, tert-amyl peroxypivalate, tert-butyl peroxypivalate, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, didecanoyl peroxide, 2,5-dimethyl-2,5-Di(2-ethylhexanoylperoxy)hexane or 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate.

[0074] The polymer composition may comprise between 0.1 phr and 5 phr of a heat-activated initiator to induce the polymerization of monomers, preferably the polymerization of the (meth)acrylic monomer and the (meth)acrylic comonomer.

[0075] The polymer composition

[0076] The polymer composition may have a dynamic viscosity greater than 10 mPa*s, preferably greater than 25 mPa*s, more preferably greater than 50 mPa*s, even more preferably greater than 100 mPa*s.

[0077] The polymer composition may have a dynamic viscosity of less than 10,000 mPa*s, preferably less than 7,000 mPa*s, more preferably less than 5,000 mPa*s, even more preferably less than 2,000 mPa*s.

[0078] Preferably, the dynamic viscosity of the polymer composition is in the range of 10 mPa*s to 10,000 mPa*s, preferably from 20 mPa*s to 7,000 mPa*s, and advantageously from 20 mPa*s to 5,000 mPa*s, and more advantageously from 20 mPa*s to 2,000 mPa*s, and even more advantageously between 20 mPa*s and 1,000 mPa*s. The viscosity of the polymer composition can be easily measured using a rheometer or a viscometer. The dynamic viscosity is measured at 25 °C. If the polymer composition exhibits Newtonian behavior, meaning that it does not undergo shear flow, the dynamic viscosity is independent of shear in a rheometer or of the velocity of the moving part in a viscometer. If the polymer composition has non-Newtonian behavior, meaning that it exhibits fluidization under shear, the dynamic viscosity is measured at a shear rate of 1 s⁻¹ at 25 °C.

[0079] The polymer composition may be a thermoplastic composition or a thermosetting composition. Advantageously, the polymer composition is a thermoplastic composition.

[0080] The polymer composition, preferably the thermoplastic composition, may comprise at least 50% by weight of monomers of a polymer, preferably a thermoplastic polymer. The thermoplastic composition may comprise up to 90% by weight of monomers of the thermoplastic polymer. The polymer matrix may comprise a (meth)acrylic polymer. The composition may comprise a polymer and a monomer. Preferably, the thermoplastic composition is a mixture of monomers and polymers.

[0081] The thermoplastic composition may include a thermoplastic polymer from the family composed of polyamide, polyurea, polyacrylic, poly(aryletherketones), polyimides, aromatic polyetherimides, polysulfides, polysulfones, polyolefins, poly(lactic acid), polyvinyl, poly(vinyl alcohol), fluoropolymers, styrenes, cellulosics, polyester and / or polycarbonates,

[0082] Preferably, the monomer of the thermoplastic composition is chosen from alkylacrylic monomers, alkylmethacrylic monomers, hydroxyalkylacrylic monomers and hydroxyalkylmethacrylic monomers and mixtures thereof.

[0083] Preferably, the polymer of the thermoplastic composition is chosen from all types of compounds, polymers, oligomers, copolymers or block copolymers, acrylic and methacrylic. However, it would not depart from the scope of the invention if the (meth)acrylic polymer matrix comprised up to 10% by weight, preferably less than 5% by weight, of other non-acrylic monomers, chosen for example from the following group: butadiene, isoprene, styrene, substituted styrene such as α-methylstyrene or β-butylstyrene, cyclosiloxanes, vinylnaphthalenes and vinylpyridines.

[0084] The thermoplastic composition according to the invention may comprise between 10% by weight and 50% by weight of a (meth)acrylic polymer and between 50% by weight and 90% by weight of a (meth)acrylic monomer. Preferably, the thermoplastic composition comprises between 10% by weight and 40% by weight of a (meth)acrylic polymer and between 60% by weight and 90% by weight of a (meth)acrylic monomer, and more preferably between 10% by weight and 30% by weight of a (meth)acrylic polymer and between 70% by weight and 90% by weight of a (meth)acrylic monomer.

[0085] As regards the thermoplastic composition of the invention, it comprises a (meth)acrylic monomer and a (meth)acrylic polymer. Once polymerized, the (meth)acrylic monomer is transformed into a (meth)acrylic polymer comprising the monomer units of the (meth)acrylic monomer and other possible monomers.

[0086] With regard to the (meth)acrylic polymer, one can mention poly(alkyl methacrylates) or poly(alkyl acrylates). According to a preferred embodiment, the (meth)acrylic polymer is poly(methyl methacrylate) (PMMA).

[0087] According to one embodiment, the homopolymer or copolymer of methyl methacrylate (MMA) comprises at least 70%, preferably at least 80%, advantageously at least 90% and more advantageously at least 95% by weight of methyl methacrylate.

[0088] According to another embodiment, PMMA is a mixture of at least one homopolymer and at least one copolymer of MMA, or a mixture of at least two homopolymers or two copolymers of MMA having a different average molecular weight, or a mixture of at least two copolymers of MMA having a different monomer composition.

[0089] The methyl methacrylate (MMA) copolymer comprises 70% to 99.9% by weight of methyl methacrylate and 0.1% to 30% by weight of at least one monomer containing at least one ethylenic unsaturation which can copolymerize with methyl methacrylate.

[0090] These monomers are well known, and mention may be made in particular of acrylic and methacrylic acids and alkyl (meth)acrylates in which the alkyl group contains 1 to 12 carbon atoms. Examples include methyl acrylate and ethyl, butyl, or 2-ethylhexyl (meth)acrylate. Preferably, the comonomer is an alkyl acrylate in which the alkyl group contains 1 to 4 carbon atoms.

[0091] According to a first preferred embodiment, the methyl methacrylate (MMA) copolymer comprises 80% to 99.9%, advantageously 90% to 99.9%, and more advantageously 90% to 99.9% by weight of methyl methacrylate and 0.1% to 20%, advantageously 0.1% to 10%, and more advantageously 0.1% to 10% by weight of at least one monomer containing at least one ethylenic unsaturation that can copolymerize with the methyl methacrylate. Preferably, the comonomer is selected from methyl acrylate and ethyl acrylate and mixtures thereof.

[0092] The average molecular mass by weight of the (meth)acrylic polymer must be high, meaning greater than 50,000 g / mol and preferably greater than 100,000 g / mol.

[0093] The average molecular mass by weight can be measured by size exclusion chromatography (SEC).

[0094] The (meth)acrylic polymer is completely soluble in the (meth)acrylic monomer or in the mixture of (meth)acrylic monomers. This increases the viscosity of the (meth)acrylic monomer or the mixture of (meth)acrylic monomers. The resulting solution is a liquid composition generally called a "syrup," "liquid (meth)acrylic syrup," or "prepolymer."

[0095] Advantageously, the composition or liquid (meth)acrylic syrup does not contain any additional solvent voluntarily added.

[0096] With regard to the (meth)acrylic monomer, the monomer is chosen from alkylacrylic monomers, alkylmethacrylic monomers, hydroxyalkylacrylic monomers and hydroxyalkylmethacrylic monomers and mixtures thereof.

[0097] Preferably, the (meth)acrylic monomer is selected from hydroxyalkylacrylic monomers, hydroxyalkylmethacrylic monomers, alkylacrylic monomers, alkylmethacrylic monomers and mixtures thereof, the alkyl group containing 1 to 22 linear, branched or cyclic carbon atoms; the alkyl group preferably containing 1 to 12 linear, branched or cyclic carbon atoms.

[0098] More preferably, the (meth)acrylic monomer is chosen from alkylacrylic monomers or alkylmethacrylic monomers and mixtures thereof, the alkyl group containing 1 to 22 linear, branched or cyclic carbon atoms; the alkyl group preferably containing 1 to 12 linear, branched or cyclic carbon atoms.

[0099] Advantageously, the (meth)acrylic monomer is selected from methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, methacrylic acid, acrylic acid, n-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, hydroxyethyl acrylate and hydroxyethyl methacrylate and mixtures thereof.

[0100] More advantageously, the (meth)acrylic monomer is selected from methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, methacrylic acid, acrylic acid, n-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate and mixtures thereof.

[0101] According to a preferred embodiment, at least 50% by weight and preferably at least 60% by weight of the (meth)acrylic monomer is methyl methacrylate.

[0102] According to a first, more preferred embodiment, at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, advantageously at least 80% by weight, and even more advantageously 90% by weight of the monomer are a mixture of methyl methacrylate with optionally at least one other monomer. For example, said at least one other monomer may be a polyfunctional (meth)acrylic monomer.

[0103] Preferably, the (meth)acrylic monomer is chosen from a compound comprising at least two (meth)acrylic groups. The (meth)acrylic monomer may also be chosen from mixtures of at least two compounds, each comprising at least two (meth)acrylic groups.

[0104] The multifunctional (meth)acrylic monomer can be selected from 1,3-butylene glycol dimethacrylate; 1,4-butanediol dimethacrylate; 1,6-hexanediol diacrylate; 1,6-hexanediol dimethacrylate; diethylene glycol dimethacrylate; dipropylene glycol diacrylate; ethoxylated bisphenol A diacrylate (10); ethoxylated bisphenol A dimethacrylate (2); ethoxylated bisphenol A diacrylate (3); ethoxylated bisphenol A dimethacrylate (3); ethoxylated bisphenol A diacrylate (4); ethoxylated bisphenol A dimethacrylate (4); ethoxylated bisphenol A dimethacrylate; ethoxylated bisphenol A dimethacrylate (10); ethylene glycol dimethacrylate; polyethylene glycol diacrylate (200); polyethylene glycol diacrylate (400); polyethylene glycol dimethacrylate (400); polyethylene glycol dimethacrylate (400); the polyethylene glycol diacrylate (600); polyethylene glycol dimethacrylate (600); polyethylene glycol diacrylate 400; neopentyl glycol propoxylated diacrylate (2); tetraethylene glycol diacrylate; tetraethylene glycol dimethacrylate; tricyclodecanedimethanol diacrylate; tricyclodecanedimethanol dimethacrylate; triethylene glycol diacrylate; triethylene glycol dimethacrylate; tripropylene glycol diacrylate; ethoxylated trimethylolpropane triacrylate (15); ethoxylated trimethylolpropane triacrylate (3); ethoxylated trimethylolpropane triacrylate (6); ethoxylated trimethylolpropane triacrylate (9); ethoxylated pentaerythritol triacrylate 5; ethoxylated trimethylolpropane triacrylate (20); glyceryl propoxylated triacrylate (3); trimethylolpropane triacrylate; glyceryl propoxylated triacrylate (5,5); pentaerythritol triacrylate; glyceryl propoxylated triacrylate (3);propoxylated trimethylolpropane triacrylate (3); trimethylolpropane triacrylate; trimethylolpropane trimethacrylate; tris(2-hydroxyethyl) isocyanurate triacrylate; ditrimethylolpropane tetraacrylate; dipentaerythritol pentaacrylate; ethoxylated pentaerythritol tetraacrylate (4); pentaerythritol tetraacrylate; dipentaerythritol hexaacrylate; 1,10-decanediol diacrylate; 1,3-butylene glycol diacrylate; 1,4-butanediol diacrylate; 1,9-nonanediol diacrylate; 2-(2-vinyloxyethoxy)ethyl acrylate; 2-butyl-2-ethyl-1,3-propanediol diacrylate; 2-methyl-1,3-propanediol diacrylate; 2-Methyl-1,3-propanediyl ethoxyacrylate; 3-Methyl-1,5-pentanediol diacrylate; alkoxylated cyclohexanedimethanol diacrylate; alkoxylated hexanediol diacrylate; cyclohexanedimethanol diacrylate; ethoxylated cyclohexanedimethanol diacrylate; diethylene glycol diacrylate; dioxane glycol diacrylate; ethoxylated dipentaerythritol hexaacrylate; ethoxylated glycerol triacrylate; ethoxylated neopentyl glycol diacrylate; hydroxypivalyl hydroxypivalate diacrylate; neopentylglycol diacrylate; poly(tetramethyleneglycol) diacrylate; polypropyleneglycol 400 diacrylate; polypropyleneglycol 700 diacrylate; propoxylated ethoxylated bisphenol A diacrylate (6); propoxylated ethyleneglycol diacrylate; propoxylated pentaerythritol tetraacrylate (5); and propoxylated trimethylolpropane triacrylate.

[0105] Preferably, the multifunctional (meth)acrylic monomer is selected from ethylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, triethylene glycol dimethacrylate and triethylene glycol diacrylate, tricyclodecanemethanol dimethacrylate or mixtures thereof.

[0106] The multifunctional (meth)acrylic monomer may be present in the (meth)acrylic composition between 0.01 and 10 phr by weight, preferably is present between 0.1 and 9.5 phr per 100 parts of a liquid (meth)acrylic syrup, more preferably between 0.1 and 9 phr, even more preferably between 0.1 and 8.5 phr and advantageously between 0.1 and 8 phr.

[0107] In a first preferred embodiment, the multifunctional (meth)acrylic monomer is present in the (meth)acrylic composition between 0.01 and 9 phr and is chosen from compounds comprising two (meth)acrylic functions.

[0108] In a second, more preferred embodiment, the multifunctional (meth)acrylic monomer is present in the (meth)acrylic composition between 0.01 and 9 phr and is selected from mixtures of compounds comprising two (meth)acrylic functions.

[0109] In a third, more preferred embodiment, the multifunctional (meth)acrylic monomer is present in the (meth)acrylic composition between 0.01 and 9 phr and is selected from mixtures of compounds comprising at least two (meth)acrylic functions.

[0110] In a fourth, more preferred embodiment, the multifunctional (meth)acrylic monomer is present in the (meth)acrylic composition between 0.01 and 9 phr and is selected from mixtures of compounds comprising at least two (meth)acrylic functions. At least one compound in the mixture comprises only two (meth)acrylic functions and represents at least 50% by weight of the methacrylic monomer mixture, preferably at least 60% by weight. The other compound in the mixture comprises more than two (meth)acrylic functions.

[0111] Preferably, the polymer formed by the polymer composition used has a glass transition temperature (Tg) between 50 °C and 160 °C, preferably between 70 °C and 140 °C, and even more preferably between 90 °C and 120 °C. This characteristic gives it an advantage over other polymers such as polyamines. Indeed, polyamines generally have very high melting points, in particular 200 °C and above, which complicates the process. The glass transition temperatures or melting points can be measured by methods well known to those skilled in the art. Preferably, these temperatures are measured by differential scanning calorimetry under the conditions specified in ISO 11357-2 / 2013 for Tg and ISO 11357-3 / 2011 for Tf.

[0112] As mentioned, a process 100 according to the invention includes an impregnation step 120 of a fibrous material with the polymer composition, preferably with the thermoplastic composition.

[0113] Impregnation is preferably carried out using an impregnation device such as a bath device, a roller impregnation device, a spray impregnation device.

[0114] The impregnation process may consist of soaking or coating the fibers with a polymer composition to ensure that they are completely wetted and / or encapsulated. The impregnation step allows the fibers to be impregnated with the polymer composition.

[0115] The fiber impregnation step (i.e., fibrous material) may include passing fibers through a polymer composition. For example, the fibers are guided through a bath or injection chamber comprising the thermoplastic composition.

[0116] Preferably, the impregnation step is carried out in such a way that the composite material layer comprises 20% to 50% by volume of a polymer composition and 50% to 80% by volume of fibers. FIBROUS MATERIAL

[0117] The fibrous material according to the invention can be of biological, mineral or synthetic origin.

[0118] Examples of biological materials include plant fibers, wood fibers, and animal fibers. Biological fibers include, for example, sisal, jute, hemp, flax, cotton, coconut fibers, and banana fibers. Animal fibers include, for example, wool or hair.

[0119] Synthetic materials may include polymer fibers selected from thermosetting polymer fibers, thermoplastic polymers, polyamide (aliphatic or aromatic), polyester, polyvinyl alcohol, polyolefins, polyurethanes, poly(vinyl chloride), polyethylene, unsaturated polyesters, epoxy resins and vinyl esters and / or carbon fibers, or mixtures thereof.

[0120] Mineral fibers can be selected from glass fibers, in particular of type E, R or S2, boron fibers, basalt fibers or silica fibers.

[0121] Preferably, the fibers are mineral fibers. More preferably, the fibers are glass fibers or carbon fibers.

[0122] The fibers may have a diameter between 0.005 pm and 100 pm, preferably between 1 pm and 50 pm, more preferably between 5 pm and 30 pm and advantageously between 10 pm and 25 pm.

[0123] Preferably, the fibers of the present invention are chosen from continuous fibers (meaning that the aspect ratio does not necessarily apply as it does for long fibers) for the one-dimensional shape, or from long fibers or continuous for the two-dimensional or three-dimensional form of the fibrous reinforcement.

[0124] As mentioned, a method 100 according to the invention includes a winding step 130 of the impregnated fibrous material around a mandrel.

[0125] The mandrel can be considered a core mold. This mandrel can represent the internal shape of the hollow body. In general, it directly reflects the internal shape of the hollow body. Its shape can range from a simple cylindrical shape to more complex geometric shapes, depending on the application.

[0126] Commonly used materials for the mandrel are steel, aluminum, and the composite materials themselves. The choice of material depends on the size of the hollow body, the application, and the required precision. A release agent can be applied to the mandrel to prevent the composite layer from adhering to it, thus facilitating the removal of the finished hollow body. Similarly, the mandrel can be lined before being coated with the composite layer.

[0127] Winding is generally carried out using automated systems comprising multi-axis control (e.g., 3 to 6 axes) enabling the creation of complex winding patterns required for different tank geometries. The systems generally include computer numerical control of the winding paths, angles, and tension. Several parameters can influence the quality of the resulting hollow body.

[0128] The fiber orientation during winding can significantly influence the mechanical properties of a hollow body. Therefore, the winding angle can be optimized according to the expected load conditions for the produced hollow body. The winding angle can generally be selected between 10° and 90° with respect to the longitudinal axis of the hollow body. Furthermore, the winding can include loop winding, helical winding, and polar winding.

[0129] The tension applied to the fibers during winding can affect the compaction and overall quality of the laminate. The optimal tension depends heavily on the fiber type and filament thickness. It is generally adjusted to ensure good alignment and compaction without damaging the fibers.

[0130] The winding speed and the degree of automation can impact production efficiency and consistency. The winding speed can vary from a few meters per minute to several tens of meters per minute, depending on the equipment and the complexity of the part. In the context of the invention, winding is performed for a predetermined duration. For example, the filament winding speed is strictly less than 1 m / sec. However, in the case of an axisymmetric hollow body, the filament winding speed can be greater than 1 m / sec, preferably greater than 2 m / sec, for example, greater than 3 m / sec. When the hollow body is not axisymmetric, the filament winding can be lower, for example with a speed of at least 0.1 m / sec, preferably at least 0.3 m / sec.

[0131] The winding step can be carried out at a winding temperature. The winding temperature can be ambient temperature such as 20 °C, or any other temperature suitable for the polymer composition used. Preferably, the winding step is carried out at ambient temperature.

[0132] Preferably, the winding step is carried out at a winding temperature for which the half-life of the heat-activated initiator is greater than 10 hours.

[0133] As mentioned, a process 100 according to the invention comprises a step 140 of exposing the polymer composition to UV light. For example, the wavelength of the UV light is from 300 to 475 nm, preferably from 325 to 450 nm, more preferably from 350 to 425 nm.

[0134] It therefore induces a first polymerization step of the compounds of the polymer composition.

[0135] The step 140 of exposing the polymer composition to UV light generally involves the use of UV lamps.

[0136] The polymer composition may be exposed to UV light before or after the first contact of the impregnated fibrous material with the mandrel. Preferably, the UV light is maintained throughout the winding step. The duration depends on the power and wavelength of the UV light. For example, the exposure time to UV light may be at least 1 second.

[0137] The step of exposing the polymer composition to UV light activates the photoinitiator preferably in order to polymerize the polymer composition.

[0138] As mentioned, a process 100 according to the invention includes a heating step 150 of the wound fibrous material.

[0139] Preferably, the heating step is carried out by a heating device such as a mold, an enclosure, a microwave source, an IR (NIR / MIR) source, an air blower and / or an induction source. The heating step may include convection heating, conduction heating, IR (infrared (including NIR and MIR (near and mid-infrared)), microwave heating, UV (ultraviolet) heating and / or induction heating.

[0140] The heating step enabling activation of the heat-activated initiator can be preceded by an acceleration of the polymerization of the polymer composition; preferably of the thermoplastic composition which has impregnated the fibers.

[0141] The heating step 150 is carried out at a heating temperature and the heat-activated initiator has a half-life at the heating temperature at most equal to the heating time,

[0142] The heating step can be carried out at a heating temperature of 100 °C or less, preferably at about 90 °C and more preferably at about 80 °C. According to one embodiment, the heating time is a function of the winding time.

[0143] The heating step can be carried out while the wound fibrous material is stationary. Preferably, the heating step is carried out while the wound fibrous material is positioned vertically, i.e., the axis of symmetry of the wound fibrous material is perpendicular to the ground.

[0144] According to one embodiment of heating step 150, polymerization can take place at a temperature generally below 140 °C, preferably below 130 °C and even more preferably below 125 °C.

[0145] According to one embodiment of the heating step, the polymerization can take place at a temperature of at least 40 °C, preferably at least 50 °C and more preferably at least 60 °C.

[0146] Preferably, polymerization can take place at a temperature between 40 °C and 140 °C, preferably between 50 °C and 130 °C, even more preferably between 60 °C and 125 °C.

[0147] Advantageously, the heating step can be implemented continuously or not, preferably it is implemented continuously.

[0148] The heating and polymerization step allows the transition from a polymer composition that has impregnated the fibers.

[0149] Once the composite material is wound around the mandrel and cured, the mandrel must be removed from the finished hollow body. This operation can be carried out by shrinkage (for metal mandrels), by mechanical extraction, or, in some cases, the mandrel is designed to collapse or segment into several parts to facilitate its removal.

[0150] The process according to the invention may include a cooling step 160 of the composite material layer. In a particular embodiment, the cooling step may be carried out by a cooling device such as a convection cooling system or a system comprising one or more heat exchangers. Furthermore, the cooling step may be carried out at a given cooling temperature and / or over a given cooling time. The cooling step allows a switch from a heated composite (i.e., a hollow body) to a cooled composite, which is easier to handle.

[0151] According to one embodiment, the cooling temperature and / or the cooling time can be chosen based on the glass transition temperature (Tg) and / or the melting temperature of the heated thermoplastic composite. Preferably, the cooling step takes place at a cooling temperature lower than the glass transition temperature of the heated thermoplastic composite. For example, the Tg can be lower than 130 °C, preferably lower than 120 °C, and more preferably lower than 110 °C.

[0152] As mentioned, a process 100 according to the invention may include a coating step 170 of the composite layer. The coating step may be carried out by a coating device such as spray coating, roller coating, or powder coating.

[0153] The coating step protects the hollow body against fire and / or impact. It is carried out directly after winding, or after the heating step, or after the cooling step, preferably directly after the cooling step. These coatings could also be polymerized using photochemical sources.

[0154] According to one embodiment, the coating step is carried out after the heating step.

[0155] The coating step may include the application of silicon dioxide (SiO2) as an intermediate layer and / or silicon dioxide / titanium dioxide (SiO2 / TiO2), such as hybrid coatings, as top layers as a sealing coating.

[0156] According to another aspect, the invention relates to a hollow body, preferably an axisymmetric hollow body, which can be obtained by a process according to the invention. More preferably, the invention relates to a hollow body, such as an axisymmetric hollow body, which is obtained by a process according to the invention.

[0157] The hollow body, such as an axisymmetric hollow body, according to the invention can be selected from: a tube, a storage tank, a vessel, a pressure vessel, a pipe, a pressure or high-pressure storage tank, electric poles, a drive shaft or wind turbine blades.

[0158] The hollow body according to the invention may comprise several layers, including a lining.

[0159] According to another aspect, the invention relates to the use of a hollow body, preferably an axisymmetric hollow body, according to the invention. The hollow body can be used as a tank, in particular as a pressure tank.

[0160] In particular, the hollow body can be used in gas storage, gas transport, water transport, wastewater transport, aerospace components or automotive components.

[0161] According to another aspect, the invention relates to a system for manufacturing a hollow body, preferably an axisymmetric hollow body comprising a layer of composite material according to the invention.

[0162] In particular, the manufacturing system for an axisymmetric hollow body may include an impregnation device, at least one UV light, a winding device, and a heating device. The manufacturing system for a hollow body may include a cooling device and a coating device.

[0163] The system can operate continuously or not, preferably continuously. Thus, the various elements and devices of the system can be configured to cooperate with each other. That is to say, to work together.

[0164] The system may include an impregnation device. An impregnation device allows a fibrous material to be impregnated with a polymer composition, preferably with a polymer composition according to the invention and as described above. An impregnation device may be configured to wet fibers (fibrous material) with a polymer composition and preferably a thermoplastic composition as indicated above. For example, an impregnation device may include one or more baths, one or more injection chambers, one or more soaking tanks, and one or more impregnation chambers. The impregnation device may be configured to receive the fibers and to wet the fibers by absorption or injection so as to ensure complete impregnation of the fibers with the thermoplastic composition, preferably in liquid form.

[0165] According to one embodiment, the impregnation device may include a comb, a scraper, a succession of rings of decreasing diameter, a tubular channel, so as to eliminate excess polymer composition.

[0166] The system according to the invention may include at least one UV light, such as UV lamps. The UV light is configured to expose the polymer composition, preferably according to the invention, to UV light. A UV light may be configured to operate at a wavelength of 300 to 475 nm, preferably 325 to 450 nm, and more preferably 350 to 425 nm. A UV light may be arranged upstream or downstream of the impregnation device. A UV light activates the photoinitiator to initiate polymerization. Advantageously, the UV light may be configured to operate for a longer duration than the duration of the heating device.

[0167] A system according to the invention includes a winding device. A winding device can be configured to wind the impregnated fibrous material around a mandrel.

[0168] A winding device may include at least one automated system comprising multi-axis control (e.g., 3 to 6 axes) for performing complex windings required for different tank geometries. The systems generally include computer numerical control of winding paths, angles, and tension. Several parameters can influence the quality of the resulting hollow body. Advantageously, the winding device may include a winding angle controller. A winding device may be configured to operate loop winding, helical winding, and polar winding. Advantageously, the winding device may include a controller for the tension applied to the fiber. Consequently, the winding device can be configured to ensure proper alignment and compaction without damaging the fibers.Advantageously, the winding device can include a controller for the speed of the winding process and the degree of automation.

[0169] A system according to the invention includes a heating device. A heating device can be configured to heat the wound fibrous material. The heating device may include an enclosure, a microwave source, an IR (NIR / MIR) source, an air blower, and / or an induction source. The heating device must ensure sufficiently uniform heating of the wound fibrous material within relatively short timeframes.

[0170] Advantageously, the heating device may include one or more IR-type heating sensors or a thermometer to regulate the various heating temperatures and / or a timer to control the heating time. Advantageously, the heating device may be configured to heat the wound fibrous material to polymerize the composite material layer according to a heating time and / or a heating temperature. A heating device may be configured to operate at a heating temperature of 100 °C or less, preferably about 90 °C, and preferably about 80 °C.

[0171] A heating time can be predetermined based on the heat-activated initiator. The heat-activated initiator can have a half-life at the heating temperature of at most the heating time. The heating device can be configured to operate according to the winding time. Advantageously, the heating device is configured so that the heating time is shorter than the winding time, thereby reducing the number of heating devices or their capacity.

[0172] The heating device can be configured to heat the wound fibrous material while the wound fibrous material is stationary. Preferably, the heating device is configured to heat the wound fibrous material while the wound fibrous material is positioned vertically, i.e., the axis of symmetry of the wound fibrous material is perpendicular to the ground.

[0173] Advantageously, a system according to the invention may include a heating device configured to heat the continuously wound fibrous material. Preferably, a system may include a heating device and a winding device configured to operate continuously, preferably together.

[0174] Advantageously, the system according to the invention can comprise at most as many heating devices as winding devices. Indeed, since the heating time is shorter than the winding time, the system requires fewer heating devices than prior art systems. In particular, once winding is complete, the mandrel with the wound fibers can enter an in-line heating zone.

[0175] The system according to the invention may include a cooling device. A cooling device may be configured to a cooling temperature lower than the glass transition temperature of the wound fibrous material, preferably of the heated and wound fibrous material.

[0176] A system according to the invention may include a coating device. A coating device may be configured to coat the layer of composite material preferably as shown above.

[0177] The invention may be subject to numerous variations and applications other than those described above. In particular, unless otherwise indicated, the various structural and functional features of each of the embodiments described above should not be considered as combined and / or closely and / or inextricably linked to one another, but rather as mere juxtapositions. Furthermore, the structural and / or functional features of the various embodiments described above may be subjected, in whole or in part, to any different juxtaposition or combination.

Claims

Demands

1. A method (100) for manufacturing a hollow body, preferably an axisymmetric hollow body, comprising a layer of composite material, said method comprising the following steps: - a step of providing (110) a polymer composition; - a step of impregnating (120) a fibrous material with the polymer composition; - a step of winding (130) the impregnated fibrous material around a mandrel, said winding being carried out for a winding time; and - a step of heating (150) the wound fibrous material, said heating being carried out for a heating time to polymerize the layer of composite material; in which: - the polymer composition comprises a combination of a photoinitiator and a heat-activated initiator; - it further comprises a step of exposing (140) the polymer composition to UV light;and - the heating time is shorter than the winding time.;

2. A method according to claim 1, wherein the heating step (150) of the wound fibrous material is carried out at a heating temperature and the heat-activated initiator has a half-life at the heating temperature of the heating step (150) that is less than the winding time.

3. A method according to claim 1 or 2, wherein the impregnation step (120) is carried out at an impregnation temperature and the impregnation temperature is chosen such that the heat-activated initiator has a half-life at the impregnation temperature greater than the winding time.

4. A method according to any one of claims 1 to 3, wherein the heating step (150) is carried out at a heating temperature and the heat-activated initiator has a half-life at the heating temperature at most equal to the heating time.

5. A method according to any one of claims 1 to 4, wherein the heat-activated initiator is selected from heat-activated initiators whose half-life at a heating temperature is at least 10 times shorter than its half-life at a winding temperature.

6. A method according to any one of claims 1 to 5, wherein the heat-activated initiator is selected from heat-activated initiators having a half-life of less than 1 hour at a temperature of 150 °C.

7. A method according to any one of claims 1 to 6, wherein the heating step (150) is carried out at a temperature of 100 °C or less.

8. A method according to any one of claims 1 to 7, wherein the polymer composition has a dynamic viscosity greater than 10 mPa*s and less than 5,000 mPa*s as measured at 25 °C.

9. A method according to any one of claims 1 to 8, wherein the fibrous material is selected from: carbon fibers or glass fibers.

10. A method according to any one of claims 1 to 9, wherein the contact of the impregnated fibrous material with the mandrel can be direct or indirect.

11. A method according to any one of claims 1 to 10, wherein the heating step is carried out while the wound fibrous material is stationary.

12. A method according to any one of claims 1 to 11, wherein the heating step is carried out while the wound fibrous material is positioned vertically, for example the axis of symmetry of the wound fibrous material is perpendicular to the ground.

13. A method according to any one of claims 1 to 12, wherein it further comprises, after the heating step, a coating step.

14. A method according to any one of claims 1 to 13, wherein the hollow body is a tube, a storage tank, a pressure vessel, a pipe, a pressurized or high-pressure storage tank, electric poles, a drive shaft, or wind turbine blades.

15. A method according to any one of claims 1 to 14, wherein the hollow body comprises several layers, including a lining.

16. A method according to any one of claims 1 to 15, wherein the polymer composition is a thermoplastic composition.

17. A method according to any one of claims 1 to 16, wherein the polymer composition comprises a thermoplastic polymer of the family composed of polyamide, polyurea, polyacrylic, poly(aryletherketones), polyimides, aromatic polyetherimides, polysulfides, polysulfones, polyolefins, poly(lactic acid), polyvinyl, poly(vinyl alcohol), fluoropolymers, styrenes, cellulosics, polyester and / or polycarbonates.

18. A method according to the preceding claim, wherein the thermoplastic composition comprises an acrylic (meth) polymer.

19. A method according to any one of claims 1 to 18, wherein the composite material layer comprises 20% to 50% by volume of a polymer composition comprising (meth)acrylic polymers and 50% to 80% by volume of fibers.

20. A method according to the preceding claim, wherein the composite material layer comprises at most 35% by volume of a thermoplastic matrix comprising a (meth)acrylic polymer and at least 65% by volume of fibers.

21. Hollow body obtainable by a process according to any one of claims 1 to 20, comprising at least one layer of composite material of a polymerized polymer composition and a fibrous material, said polymer composition comprising a combination of a photoinitiator and a heat-activated initiator selected from compounds comprising a peroxy or azo group.

22. Use of a hollow body according to the preceding claim in gas storage, gas transport, water transport, wastewater transport, aerospace components or automotive components.

23. A system for manufacturing a hollow body comprising a layer of composite material, said system comprising:

24. - an impregnation device configured to wet a fibrous material with a polymer composition, said polymer composition comprising a combination of a photoinitiator and a heat-activated initiator, - at least one UV lamp configured to expose the polymer composition to UV light, - a winding device configured to wind the fibrous material around a mandrel for a specified winding time, and - a heating device configured to heat the wound fibrous material in order to polymerize the layer of composite material according to a heating time, the heating time being shorter than the winding time, and the heating device and the winding device are configured to operate continuously. System according to claim 23, wherein it comprises at most as many heating devices as winding devices.

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