LIQUID COMPOSITION FOR FILAMENT WINDING, ITS POLYMERIZATION PROCESS, USE AND OBJECT OBTAINED AFTER POLYMERIZATION OF THE COMPOSITION

Abstract

LIQUID COMPOSITION FOR FILAMENT WINDING, ITS POLYMERIZATION PROCESS, USE, AND OBJECT OBTAINED AFTER POLYMERIZATION OF THE COMPOSITION. The present invention relates to a liquid composition for filament winding comprising a monomer, a (meth)acrylic polymer, and at least one initiator. The present invention further relates to a liquid composition for filament winding comprising a monomer, a (meth)acrylic polymer, and at least one or two initiators having different half-lives, its polymerization process, a system for the polymerization process, and an object obtained. The present invention also relates to a process for manufacturing thermoplastic composites, mechanical parts, or structural elements made of composite material, and to mechanical parts or structural elements made of composite material obtained by the process using such a liquid composition.The thermoplastic composite is a hollow body, and preferably an axisymmetric hollow body.

Description

Title of the invention: LIQUID COMPOSITION FOR FILAMENT WINDING, ITS POLYMERIZATION PROCESS, USE AND OBJECT OBTAINED AFTER POLYMERIZATION OF THE COMPOSITION technical field

[0001] The present invention relates to a liquid composition for filament winding comprising a monomer, a (meth)acrylic polymer and at least one initiator.

[0002] The present invention relates in particular to a liquid composition for filament winding comprising a monomer, a (meth)acrylic polymer and at least one or two initiators having a different half-life, its polymerization process, a system for the polymerization process and an object obtained.

[0003] The present invention further relates to a method for manufacturing thermoplastic composites, mechanical parts or structural elements made of composite material, and mechanical parts or structural elements made of composite material obtained by the method using such a liquid composition. The thermoplastic composite is a hollow body, and preferably an axisymmetric hollow body. Previous technique

[0004] Thermoplastic polymers are materials that are widely used today in several fields and applications, for example in the construction, aeronautical, automotive or railway sectors, where they are part of mechanical parts.

[0005] These mechanical parts, which must withstand high stresses during their use, are largely manufactured from composite materials. A composite material is a macroscopic combination of two or more immiscible materials. The composite material consists of at least one material that forms the matrix, that is, a continuous phase that ensures the cohesion of the structure, and a reinforcing material.

[0006] The objective of using a composite material is to obtain performance qualities that cannot be obtained from each of its constituents when used separately. Therefore, composite materials are widely used in several industrial sectors, for example, construction, automotive, aerospace, transport, leisure, electronics, and sports, particularly because of their superior mechanical performance (higher tensile strength, higher tensile modulus, higher toughness to break) and low density, compared to homogeneous materials.

[0007] In order to enable and facilitate recycling, thermoplastic polymers are preferred to be used also in composite materials, instead of thermoset sand materials.

[0008] Thermoplastic polymers consist of linear or branched polymers, which are not usually cross-linked. Thermoplastic polymers are heated to mix the constituents necessary for manufacturing the composite material and are then cooled to take their final shape. The problem with these molten thermoplastic polymers is their very high viscosity. To prepare a polymeric composite material based on a thermoplastic polymer, a liquid composition or a liquid thermoplastic polymer composition, commonly called a "syrup," is used to impregnate the reinforcing material, for example, a fibrous substrate. Once polymerized, the thermoplastic polymer composition forms the matrix of the composite material.

[0009] During the impregnation process in the preparation of polymeric composites, the viscosity of the impregnation syrup must be controlled and adjusted so that it is neither too fluid nor too viscous, in order to properly impregnate each fiber of the fibrous substrate. When impregnation or wetting is incomplete, depending on whether the syrup is too fluid or too viscous, either so-called "dry" areas, i.e., unimpregnated areas, or areas in which larger polymer droplets form on the fibers, which cause bubble formation, respectively, appear. These "dry" areas and these bubbles lead to the appearance of defects in the final composite material, which are the cause, among other things, of a loss of mechanical strength in the final composite material.

[0010] Similarly, particularly in the case of filament winding where the object is made of several layers of impregnated fibrous material, a reduction in volume during polymerization to obtain a thermoplastic matrix leads to defects in the structure. These defects consist of a certain porosity and delamination between the respective layers.

[0011] A liquid composition or syrup comprising a (meth)acrylic monomer and a (meth)acrylic polymer is described in document WO 2014 / 013028. The polymerization of the monomer(s) is achieved with one or more radical generation initiators or initiation systems comprising one or more radical generation initiator systems. In both documents, benzoyl peroxide is used in the examples.

[0012] Document WO2014 / 174098 describes a liquid (meth)acrylic syrup. The syrup comprises an initiation system including an accelerator, an organic aldehyde, a peracid, and a liquid peroxy compound. The polymerization time in the examples in this document is a few hours or a few dozen minutes.

[0013] Document WO2020 / 007919 discloses a fiber-reinforced polymer tube. The tube is manufactured by a filament winding process that includes a thermosetting epoxy resin, as well as polyesters, polyurethane resins, or poly(vinyl ester) resins.

[0014] US2018 / 0265659 discloses a pressure vessel reinforced with a filament-prepreg composite material and its manufacturing process. The matrix resin is an epoxy, and the process includes a filament winding step.

[0015] None of these documents suggest a liquid (meth)acrylic composition suitable for the preparation of thermoplastic composites by filament winding, or a method for manufacturing a thermoplastic composite by filament winding. [TECHNICAL PROBLEM]

[0016] The objective of the invention is, therefore, to remedy at least one of the drawbacks of the prior art.

[0017] An objective of the present invention is to obtain a liquid composition comprising a monomer, a (meth)acrylic polymer, and at least one initiator to obtain a composition that can be rapidly polymerized with sufficient conversion while preparing thermoplastic compounds by filament winding. Sufficient conversion means that at least 10% of the monomers have been polymerized during the filament winding step, preferably at least 15%. Rapidly means that the partial polymerization is carried out in less than 60 minutes, preferably less than 50 minutes, even more preferably less than 40 minutes, and advantageously less than 30 minutes.

[0018] An objective of the present invention is also to have a system and a method for polymerizing a liquid composition comprising a monomer, a (meth)acrylic polymer and at least one initiator until sufficient conversion.

[0019] Another objective of the present invention is to use a liquid composition comprising a monomer, a (meth)acrylic polymer and at least one initiator for a process of manufacturing thermoplastic composites by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably an axisymmetric hollow body.

[0020] Yet another objective of the present invention is to provide a composition, a system and a method for preparing thermoplastic composites by winding filamentary, the thermoplastic composite being preferably a hollow body, and more preferably an axisymmetric hollow body.

[0021] Another objective of the present invention is to provide a composition, a system, and a method for preparing a thermoplastic composite object by filament winding, the thermoplastic composite object preferably being a hollow body, and more preferably an axisymmetric hollow body, to obtain a recyclable object with low porosity and reduced delamination. Low porosity is understood to mean a porosity of less than 10% by volume, preferably less than 5% by volume. Reduced delamination is understood to mean that there are fewer areas with delamination. [BRIEF DESCRIPTION OF THE INVENTION]

[0022] It has been discovered that a liquid composition (LC1) comprising

[0023] a) a (meth)acrylic polymer (PI),

[0024] b) a (meth)acrylic monomer (Ml), and

[0025] c) at least one initiator (Inil),

[0026] said liquid (meth)acrylic syrup having a dynamic viscosity between 10 mPa*s and 10,000 mPa*s at 25 °C, is suitable for the preparation of thermoplastic composites by filament winding, the thermoplastic composite being preferably a hollow body, and more preferably an axisymmetric hollow body, having low porosity and reduced delamination.

[0027] It was also discovered that a liquid composition (LC1) comprising

[0028] a) a (meth)acrylic polymer (PI),

[0029] b) a (meth)acrylic monomer (Ml), and

[0030] c) at least two initiators (Ini1) and (Ini2),

[0031] said liquid (meth)acrylic syrup having a dynamic viscosity between 10 mPa*s and 10,000 mPa*s at 25 °C, is suitable for the preparation of thermoplastic composites by filament winding, the thermoplastic composite being preferably a hollow body, and more preferably an axisymmetric hollow body, having low porosity and reduced delamination.

[0032] It has also been discovered that a process for manufacturing thermoplastic composites by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably axisymmetric hollow body composite parts, by a process comprising the following steps:

[0033] i) impregnation of fibers or a fibrous substrate with the liquid composition (LC1) comprising

[0034] a) a (meth)acrylic polymer (PI),

[0035] b) a (meth)acrylic monomer (Ml), and

[0036] c) either at least one initiator (Inil), or at least two initiators (Inil) and (Ini2),

[0037] said liquid (meth)acrylic syrup having a dynamic viscosity between 10 mPa*s and 10,000 mPa*s at 25 °C,

[0038] ii) polymerization of at least a portion of the liquid composition (LC1) during winding onto a mandrel,

[0039] provides a thermoplastic composite that is a hollow body, and more preferably an axisymmetric hollow body, having low porosity and reduced delamination, compared to a process in which non-partial polymerization takes place during winding.

[0040] It has also been discovered that 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:

[0041] - possibly a step of supplying (105) fibers or fibrous material,

[0042] - possibly a supply step (110) of a liquid composition (LC1) including

[0043] a) a (meth)acrylic polymer (PI),

[0044] b) a (meth)acrylic monomer (Ml), and

[0045] c) either at least one initiator (Inil), or at least two initiators (Inil) and (Ini2),

[0046] said liquid (meth)acrylic syrup having a dynamic viscosity between 10 mPa*s and 10,000 mPa*s at 25 °C;

[0047] - a step of impregnating (120) a fibrous material with the liquid composition (LC1) comprising

[0048] a) a (meth)acrylic polymer (PI),

[0049] b) a (meth)acrylic monomer (Ml), and

[0050] c) either at least one initiator (Inil), or at least two initiators (Inil) and (Ini2),

[0051] said liquid (meth)acrylic syrup having a dynamic viscosity between 10 mPa*s and 10,000 mPa*s at 25 °C;

[0052] - a winding step (130) of the impregnated fibrous material around a mandrel, said winding being carried out for a winding time tl; and

[0053] - a heating step (140) of the wound fibrous material to a temperature Th, said heating being carried out for a heating time t2 to polymerize a part of the (meth)acrylic monomer (Ml) of the liquid composition (LC1),

[0054] provides a thermoplastic composite which is a hollow body, and more preferably an axisymmetric hollow body, having low porosity and reduced delamination, compared to a process in which heating takes place during winding.

[0055] Furthermore, it has also been discovered that a composite part obtained by the manufacturing process exhibits significantly lower porosity and reduced delamination.

[0056] 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:

[0057] Fig. 1 represents a flow diagram of a process according to an embodiment of the invention.

[0058] Figure 2 shows a schematic view of one embodiment of the system (1). Description of the figures

[0255] Figure 1 represents a flow diagram of the process (100) according to an embodiment of the invention. It includes the optional steps surrounded by dashed lines and the essential steps surrounded by solid lines.

[0256] Figure 2 shows a schematic view of an embodiment of the system (1), including fiber reels (10), fibers (15), an impregnation means (20), a mandrel (30), a heating means (40), and a temperature control means (50). In Figure 2, the winding step (130) has just begun because the surface (60) of the mandrel (30) is not yet completely covered by the impregnated fibers (25). The mandrel rotates at a speed vr, and the distance di between the heating means (40) and the surface (60) is also shown. [Processes]

[0257] The conversion of methyl methacrylate to (Ml) is measured by gas chromatography. A sample is cut from the obtained material, weighed, and extracted. The extraction is carried out with THF. The monomer ratio is measured from the solution extracted from the sample by gas chromatography.

[0258] The weight-average molecular weight can be measured by size-exclusion chromatography (SEC). The chromatography column is calibrated with PMMA references having a molecular weight between 402 g / mol and 1,900,000 g / mol. The weight-average molecular weight is expressed in g / mol for the number and average molecular weights Mn and Mw, respectively. For the measurement, the concentration is 1 g / L.

[0259] The viscosity of the liquid composition comprising at least components a) and b) is measured using a Brookfield viscometer at 23 °C, according to ISO 2555:2018 “Plastics — Resins in liquid state or in emulsions or dispersions — Determination of apparent viscosity by the method of the single-cylinder type rotary viscometer”.

[0260] Porosity and delamination in the object are evaluated by tomography. X-ray tomography is used. [Examples]

[0261] First step: preparation of a liquid composition (LC1)

[0262] A liquid composition is prepared by dissolving 20 wt% of PMMA (BS520, an MMA copolymer comprising ethyl acrylate as a comonomer) as (PI) in 80 wt% of methyl methacrylate as (Ml), which is stabilized with HQME (hydroquinone monomethyl ether).

[0263] To this liquid composition are added different initiators (Inil) only or mixtures of two different initiators (Inil) and (Ini2). As initiators (Inil) or (Ini2) are di(4-tert-butylcyclohexyl) peroxydicarbonate (PI6 - Perkadox® 16 from Akzo Nobel) and benzoyl peroxide (BPO - Perkadox® CH50X from Akzo Nobel).

[0264] Second step: partial polymerization of a liquid composition by filament winding.

[0265] Carbon fibers from reels are impregnated in a bath containing the liquid composition prepared in step 1 and wound onto a mandrel. For the illustrated winding process, an infrared source was heated to 65 °C to initiate polymerization. For a comparative process, no heating was applied during winding. After 1 hour, the wound composites obtained were collected.

[0266] Third stage: hardening - The recovered objects are placed in an oven at 80 °C for 2 hours.

[0267] The resulting objects are evaluated for porosity and delamination using tomography. The symbol: — indicates a relatively high presence of this characteristic. The symbol: oo indicates an intermediate presence of this characteristic. The symbol: ++ indicates a low presence of this characteristic.

[0268] [Table 1]

[0269] Table 1 compositions and results at 110 °C. Inil [phr] Ini2 [phr] porosity delamination Comparative example 1 P16 0.6 BPO 1 No complete polymerization during the winding step Example 1 P16 0.6 BPO 1 ++ ++

[0270] Heating during winding, which leads to polymerization, significantly reduces the porosity and delamination of the resulting object. Comparative example 1 exhibits higher porosity and delamination. Description of the implementation methods

[0059] According to a first aspect, the present invention relates to a liquid composition (LC1) adapted for the preparation of thermoplastic composites by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably an axisymmetric hollow body, said composition comprising:

[0060] a) a (meth)acrylic polymer (PI),

[0061] b) a (meth)acrylic monomer (Ml), and

[0062] c) at least one initiator (Inil),

[0063] said liquid composition (LC1) having a dynamic viscosity between 10 mPa*s and 10,000 mPa*s at 25 °C.

[0064] According to a second aspect, the present invention relates to a liquid composition (LC1) adapted for the preparation of thermoplastic composites by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably an axisymmetric hollow body, said composition comprising:

[0065] a) a (meth)acrylic polymer (PI),

[0066] b) a (meth)acrylic monomer (Ml), and

[0067] c) at least two initiators (Ini1) and (Ini2),

[0068] said liquid composition (LC1) having a dynamic viscosity between 10 mPa*s and 10,000 mPa*s at 25 °C.

[0069] According to a third aspect, the present invention relates to the use of a liquid composition (LC1) for the manufacture of thermoplastic composite parts by filament winding.

[0070] According to a fourth aspect, the present invention relates to a system (1) for preparing thermoplastic composites by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably an axisymmetric hollow body, said system (1) comprising:

[0071] one or more reels of fibre (10),

[0072] an impregnation means (20) for impregnating the fibers (15) with the liquid composition (LC1),

[0073] a chuck (30),

[0074] a heating means (40), and

[0075] possibly a means of temperature regulation (50).

[0076] According to a fifth aspect, the present invention relates to a method for manufacturing thermoplastic composites by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably axisymmetric hollow body composite parts, by a method comprising the following steps:

[0077] i) impregnation of fibers or a fibrous substrate with the liquid composition (LC1) according to the first or second aspect,

[0078] ii) polymerization of at least part of the liquid composition (LC1) during winding onto a mandrel.

[0079] According to a sixth aspect, the present invention relates to a method (100) for manufacturing a thermoplastic composite, preferably a hollow body, preferably an axisymmetric hollow body, comprising a layer of composite material, said method comprising the following steps:

[0080] - possibly a step of supplying (105) fibers or fibrous material,

[0081] - possibly a step of supplying (110) the liquid composition (LC1) according to the first or second aspect;

[0082] - an impregnation step (120) of a fibrous material with the liquid composition (LC1);

[0083] - a winding step (130) of the impregnated fibrous material around a mandrel, said winding being carried out for a winding time ti; and

[0084] - a heating step (140) of the wound fibrous material to a temperature Th, said heating being carried out for a heating time t2 in order to polymerize a part of the (meth)acrylic monomer (Ml) of the liquid composition (LC1).

[0085] The term “fibrous substrate”, in this context, refers to several fibers, unidirectional strands or a continuous filament mat, fabrics, felts or non-wovens which may be in the form of strips, sheets, braids, strands or pieces.

[0086] The term “(meth)acrylic”, in the present context, refers to any type of acrylic or methacrylic monomer.

[0087] The term “PMMA”, in the present context, refers to homopolymers and copolymers of methyl methacrylate (MMA), the weight ratio of MMA in PMMA being at least 70% by weight for the MMA copolymer.

[0088] The term “monomer”, in the present context, refers to a molecule that can undergo polymerization.

[0089] The term “polymerization”, in this context, refers to the process of converting a monomer or a mixture of monomers into a polymer.

[0090] The term “thermoplastic polymer,” in this context, refers to a polymer that becomes liquid or more liquid or less viscous or soft when heated and that can take on new shapes by the application of heat and pressure. This also applies to slightly cross-linked thermoplastic polymers that can be thermoformed when heated above their softening temperature.

[0091] The term “polymer composite”, in this context, refers to a multicomponent material comprising several different phase domains, at least one type of phase domain being a continuous phase and at least one component being a polymer.

[0092] The term “initiator”, in the present context, refers to a compound that can start / initiate the polymerization of a monomer or monomers.

[0093] The term "half-life" 11 / 2, in this context, refers to the time required for an initial quantity of initiator to decrease in concentration by half. This time is a function of temperature.

[0094] The abbreviation "phr" designates 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.

[0095] The abbreviation "ppm" stands for 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.

[0096] By specifying that a range goes from x to y in the present invention, this means that the upper and lower limits of this range are included, which is equivalent to at least x and up to y.

[0097] By specifying that a range is between x and y in the present invention, this means that the upper and lower limits of this range are excluded, which is equivalent to more than x and less than y.

[0098] The liquid composition (LC1) or (meth)acrylic syrup according to the invention comprises a (meth)acrylic monomer (Ml) or a mixture of (meth)acrylic monomers (Ml) and (Ml+x), a (meth)acrylic polymer (PI) and at least one initiator (Inil).

[0099] According to a first preferred embodiment, the liquid composition (LC1) includes an initiator (Inil).

[0100] According to a second preferred embodiment, the liquid composition (LC1) comprises at least two initiators (Inil) and (Ini2).

[0101] According to a third preferred embodiment, the liquid composition (LC1) comprises more than two initiators.

[0102] The dynamic viscosity of the liquid composition or (meth)acrylic syrup 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 syrup can easily be measured with a rheometer or viscometer. The dynamic viscosity is measured at 25 °C. If the liquid (meth)acrylic syrup exhibits Newtonian behavior, meaning that it does not display In the absence of shear flow, the dynamic viscosity is independent of shear rate in a rheometer or of the moving part's velocity in a viscometer. If the liquid composition exhibits non-Newtonian behavior, meaning it flows under shear, the dynamic viscosity is measured at a shear rate of 1 s⁻¹ at 25 °C.

[0103] The liquid composition (LC1) or (meth)acrylic syrup according to the invention, for impregnating the fibrous substrate, comprises in particular a (meth)acrylic monomer or a mixture of (meth)acrylic monomers, a (meth)acrylic polymer and either at least one initiator (Inil), or at least two initiators (Inil) and (Ini2).

[0104] With regard to the liquid composition (LC1) of the invention, it comprises a (meth)acrylic monomer (M1), a (meth)acrylic polymer (PI), and either at least one initiator (Inil) or at least two initiators (Inil) and (Ini2). Once polymerized, the (meth)acrylic monomer (M1) is transformed into a (meth)acrylic polymer (P2) comprising the monomer units of the (meth)acrylic monomer (M1).

[0105] The amount of either at least one initiator (Inil) or at least two initiators (Inil) and (Ini2) together in the composition is at least 0.1 phr relative to the sum of the (meth)acrylic monomer (Ml) and the (meth)acrylic polymer (PI). Preferably, the amount of either at least one initiator (Inil) or at least two initiators (Inil) and (Ini2) together in the composition is at least 0.12 phr, more preferably at least 0.15 phr, even more preferably at least 0.17 phr and advantageously at least 0.2 phr relative to the sum of the (meth)acrylic monomer (Ml) and the (meth)acrylic polymer (PI).

[0106] The quantity of either at least one initiator (Inil) or at least two initiators (Inil) and (Ini2) together in the composition is at most 15 phr relative to the sum of the (meth)acrylic monomer (Ml) and the (meth)acrylic polymer (PI). Preferably, the quantity of either at least one initiator (Inil) or at least two initiators (Inil) and (Ini2) together in the composition is at most 12 phr, more preferably at most 10 phr, even more preferably at most 8 phr and advantageously at most 5 phr relative to the sum of the (meth)acrylic monomer (Ml) and the (meth)acrylic polymer (PI).

[0107] The amount of either at least one initiator (Inil) or at least two initiators (Inil) and (Ini2) together in the composition is between 0.1 phr and 15 phr relative to the sum of the (meth)acrylic monomer (Ml) and the (meth)acrylic polymer (PI). Preferably, the amount of either at least one initiator (Inil) or at least two initiators (Inil) and (Ini2) together in the composition is between 0.12 phr and 12 phr, more preferably between 0.15 phr and 10 phr, even more preferably between 0.17 phr and 8 phr, and advantageously at most between 0.2 phr. and 5 phr relative to the sum of the (meth)acrylic monomer (Ml) and the (meth)acrylic polymer (PI).

[0108] With regard to the (meth)acrylic (Ml) monomer, the monomer is selected from acrylic acid, methacrylic acid, alkyl acrylic monomers, alkyl methacrylic monomers, hydroxyalkyl acrylic monomers and hydroxyalkyl methacrylic monomers and mixtures thereof.

[0109] Preferably, the (meth)acrylic monomer (Ml) is selected from acrylic acid, methacrylic acid, hydroxyalkyl acrylic monomers, hydroxyalkyl methacrylic monomers, alkyl acrylic monomers, alkyl methacrylic monomers and mixtures thereof, the alkyl group containing from 1 to 22 linear, branched or cyclic carbons; the alkyl group preferably containing from 1 to 12 linear, branched or cyclic carbons.

[0110] Advantageously, the (meth)acrylic monomer (Ml) 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.

[0111] According to a preferred embodiment, at least 50% by weight and preferably at least 60% by weight of the (meth)acrylic monomer (Ml) is methyl methacrylate.

[0112] 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 (Ml) is a mixture of methyl methacrylate with optionally at least one other monomer.

[0113] With regard to the (meth)acrylic (PI) polymer, mention may be made of poly(alkyl methacrylate) or poly(alkyl acrylate). According to a preferred embodiment, the (meth)acrylic polymer is poly(methyl methacrylate) (PMMA).

[0114] The term “PMMA” refers to a homopolymer or copolymer of methyl methacrylate (MMA) or mixtures thereof. The (meth)acrylic (PI) polymer comprises at least 50% by weight of methyl methacrylate (MMA).

[0115] According to one embodiment, the methyl methacrylate (MMA) homopolymer or copolymer comprises at least 70%, preferably at least 80%, advantageously at least 90% and more advantageously at least 95% by weight of methyl methacrylate.

[0116] 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.

[0117] The methyl methacrylate (MMA) copolymer comprises from 70% to 99.7% by weight of methyl methacrylate and from 0.3% to 30% by weight of at least one monomer containing at least one ethylenic unsaturation which can copolymerize with methyl methacrylate.

[0118] These monomers are well known, and in particular include acrylic and methacrylic acids and alkyl (meth)acrylates in which the alkyl group contains from 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 from 1 to 4 carbon atoms.

[0119] According to a first preferred embodiment, the methyl methacrylate (MMA) copolymer comprises from 80% to 99%, advantageously from 90% to 99.7%, and more advantageously from 90% to 99.5% by weight of methyl methacrylate and from 0.3% to 20%, advantageously from 0.3% to 10%, and more advantageously from 0.5% 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.

[0120] The average molecular mass by weight of the (meth)acrylic (PI) polymer must be high, meaning greater than 50,000 g / mol and preferably greater than 100,000 g / mol.

[0121] The average molecular mass by weight can be measured by size exclusion chromatography (SEC).

[0122] 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 referred to as a "syrup" or "prepolymer." The dynamic viscosity of the liquid (meth)acrylic syrup ranges from 10 mPa·s to 10,000 mPa·s. The viscosity of the syrup can be easily measured using a rheometer or viscometer. The dynamic viscosity is measured at 25 °C.

[0123] Advantageously, the liquid (meth)acrylic syrup contains no additional solvents intentionally added.

[0124] With regard to the two initiators (Inil) and (Ini2), the initiators generate radicals which initiate the monomer(s) to start a radical polymerization of the monomer in order to form the polymer chains by propagation.

[0125] Preferably, the initiators (Inil) and (Ini2) are activated by heat.

[0126] The heat-activated initiators (Inil) and (Ini2) are preferably radical initiators.

[0127] The radical initiators (Inil) and (In2) can be chosen from a compound comprising a peroxy group or compounds comprising an azo group and, preferably, from a compound comprising a peroxy group.

[0128] Preferably, the compound comprising a peroxy group comprises from 2 to 30 carbon atoms.

[0129] Preferably, the compound comprising a peroxy group is selected from diacyl peroxides, peroxyesters, peroxydicarbonates, dialkyl peroxides, peroxyacetals, a hydroperoxide or a peroxyketal.

[0130] Preferably, if two initiators are present in the liquid composition (LC1), the two initiators (Inil) and (Ini2) have different half-lives ti / 2 at any given temperature Ti.

[0131] Even more preferably, the second initiator (Ini2) has, at a given temperature Tb, a half-life ti / 2 that is at least twice the half-life ti / 2 of the first initiator (Inil). Even more preferably, the second initiator (Ini2) has, at a given temperature Tl, a half-life ti / 2 that is at least three times, advantageously four times, more advantageously five times, and even more advantageously six times the half-life ti / 2 of the first initiator (Inil).

[0132] Preferably, the temperature Ti is between 20 °C and 160 °C, more preferably between 40 °C and 140 °C and advantageously between 50 °C and 130 °C.

[0133] More preferably, the first initiator (Inil) has a half-life ti / 2 of 1 hour at a temperature between 40 °C and 90 °C, more preferably between 45 °C and 80 °C, and even more preferably between 50 °C and 75 °C.

[0134] More preferably, the second initiator (Ini2) has a half-life ti / 2 of 1 hour at a temperature of at least 70 °C, even more preferably of at least 75 °C.

[0135] More preferably, the second initiator (Ini2) has a half-life ti / 2 of 1 hour at a temperature between 70 °C and 150 °C, more preferably between 75 °C and 140 °C, and even more preferably between 75 °C and 130 °C.

[0136] Preferably, the temperature difference for a given half-life between the initiators (Ini2) and (Inil) is at least 5 K. This means, if, for a time of half-life ti / 2 of 1 hour, the temperature of (Inil) is 75 °C, that the temperature of (Ini2) for a half-life time ti / 2 of 1 hour is at least 80 °C.

[0137] Preferably, the temperature difference for a given half-life between the initiators (Ini2) and (Inil) is at most 50 K. This means that, if, for a half-life ti / 2 of 1 hour, the temperature of Inil is 50 °C, the temperature of Ini2 for a half-life ti / 2 of 1 hour is at most 100 °C.

[0138] More preferably, the temperature difference for a given half-life between the initiators (Ini2) and (Inil) is between 5 K and 50 K, more preferably between 6 K and 40 K, and even more preferably between 7 K and 30 K.

[0139] The initiators (Ini2) and (Inil) are selected from diisobutyryl peroxide, cumyl peroxyneodecanoate, di(3-methoxybutyl) peroxydicarbonate, 1,1,3,3-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) peroxydicarbonate, tert-butyl peroxyneodecanoate, di-n-butyl peroxydicarbonate, diketyl peroxydicarbonate, dimyristyle peroxydicarbonate, the 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, 1,1,3-peroxy-2-ethylhexanoate3-Tetramethylbutyl, tert-amyl peroxy-2-ethylhexanoate, 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, tert-butyl peroxy-3,5,5-trimethylhexanoate, 2,2-di-(tert-butylperoxy)-butane, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxybenzoate, tert-butyl peroxyacetate, butyl 4,4-di(tert-butylperoxy)valerate, tert-butyl peroxybenzoate, di-tert-amyl peroxide, dicumyl peroxide, di-(2-tert-butyl-peroxyisopropyl)benzene, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3,di-tert-butyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azodi-(2-methylbutyronitrile), azobisisobutyramide, 2,2'-azobis(2,4-dimethylvaleronitrile), l,l'-azodi(hexahydrobenzonitrile) or 4,4'-azobis(4-cyanopentanoic acid).

[0140] Preferably, the initiator (Inil) is selected from cumyl peroxyneodecanoate, di(3-methoxybutyl) peroxydicarbonate, 1,1,3,3-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) peroxydicarbonate, tert-butyl peroxyneodecanoate, di-n-butyl peroxydicarbonate, diketyl peroxydicarbonate, dimyristyle peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxypivalate, peroxyneoheptanoate tert-butyl, 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.

[0141] Preferably, the initiator (Ini2) is selected from 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, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxydiethyl acetate, tert-butyl peroxyisobutyrate, l,l-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane, the l,l-di(tert-amylperoxy)cyclohexane, l,l-di-(tert-butylperoxy)-cyclohexane, tert-amyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxyacetate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 2,2-di-(tert-butylperoxy)-butane, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxybenzoate, tert-butyl peroxyacetate, 4,4-Di(tert-butylperoxy)butyl 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-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, di-tert-butyl peroxide, or 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane.

[0142] If two initiators are present in the liquid composition (LC1), the weight ratio between the two initiators (Ini2) and (Inil) is between 1 / 10 and 10 / 1, preferably between 1 / 5 and 5 / 1 and more preferably between 1 / 4 and 4 / 1.

[0143] Preferably, the initiator (Inil) is chosen from peroxydicarbonates. Preferably, the initiator (Inil) has a maximum storage temperature of 20 °C or less.

[0144] More preferably, the initiator (Inil) has the following general formula (1): * S (1) R;--

[0145] wherein Ri and R2 each have an alkyl group, which may be linear, branched, or cyclic, or a combination of the three, having at least 6 carbon atoms, preferably 8 carbon atoms, and more preferably at least 10 carbon atoms. Advantageously, groups Ri and R2 each have between 10 and 30 carbon atoms, and more advantageously between 10 and 20 carbon atoms. Groups Ri and R2 may be different or the same.

[0146] In a first preferred embodiment, the initiator (Inil) is chosen from di(4-tert-butylcyclohexyl) peroxydicarbonate, dicetyl peroxydicarbonate and dimyristyle peroxydicarbonate.

[0147] Even more preferably, if two initiators are present in the liquid composition (LC1), the initiator (Inil) is chosen from di(4-tert-butylcyclohexyl) peroxydicarbonate, diketyl peroxydicarbonate and dimyristyle peroxydicarbonate and the initiator (Ini2) is chosen from benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, dilauroyl peroxide, 2,5-dhnethyl-2,5-di(2-ethylhexanoylperoxy)hexane and didecanoyl peroxide.

[0148] In a first, even more preferred embodiment, the initiator (Inil) is chosen from di(4-tert-butylcyclohexyl) peroxydicarbonate.

[0149] The initiator (Ini2), in this first even more preferred embodiment, is chosen from benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, dilauroyl peroxide and didecanoyl peroxide.

[0150] In a second, even more preferred embodiment, the initiator (Inil) is chosen from dicetyl peroxydicarbonate.

[0151] The initiator (Ini2), in this second, even more preferred embodiment, is chosen from benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, dilauroyl peroxide and didecanoyl peroxide.

[0152] In a third, even more preferred embodiment, the initiator (Inil) is chosen from dimyristyle peroxydicarbonate.

[0153] The initiator (Ini2), in this third even more preferred embodiment, is chosen from benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, dilauroyl peroxide and didecanoyl peroxide.

[0154] In order to maintain a dynamic viscosity of the liquid composition or (meth)acrylic syrup, which also allows good impregnation of the fibrous substrate, if necessary, and to maintain the thermoplastic properties of the matrix obtained after polymerization of the fibrous substrate impregnated with the liquid composition (LC1), the syrup components are incorporated in the following mass percentages:

[0155] The (meth)acrylic monomer(s) (Ml) in the liquid composition LC1 or the (meth)acrylic syrup are present in proportions of between 40% and 95% by weight, preferably between 40% and 90% by weight and advantageously between 45% and 85% by weight of the composition comprising one or more (meth)acrylic monomers (Ml) and the (meth)acrylic polymer (PI).

[0156] The (meth)acrylic polymer(s) (PI) in the liquid composition (LC1) or (meth)acrylic syrup are present in a proportion of at least 5% by weight, preferably at least 10% and advantageously at least 15% by weight of the composition comprising one or more (meth)acrylic monomers (Ml) and the (meth)acrylic polymer (PI).

[0157] The (meth)acrylic (PI) polymer(s) in the liquid (meth)acrylic composition are present in a proportion of not more than 50% by weight, preferably not more than 40% and advantageously not more than 30% by weight of the composition comprising one or more (meth)acrylic (Ml) monomers and the (meth)acrylic (PI) polymer.

[0158] All optional additives and fillers are added to the liquid (meth)acrylic syrup before impregnation and / or polymerization.

[0159] The liquid composition according to the invention may optionally also include an activator for polymerization.

[0160] The polymerization activator or accelerator is chosen from tertiary amines such as N,N-dimethyl-p-toluidine (DMPT), N,N-dihydroxyethyl-p-toluidine (DHEPT), organic-soluble transition metal catalysts or mixtures thereof.

[0161] Advantageously, the liquid (meth)acrylic composition contains no metal-based catalyst. No additive comprising a metal as an activator to catalytically accelerate the polymerization reaction is added to the liquid (meth)acrylic composition according to the invention. This includes, in particular, tin-based compounds such as tin chloride.

[0162] The content of the activator relative to the (meth)acrylic monomer (Ml) of the liquid (meth)acrylic composition is from 100 ppm to 10,000 ppm (by weight), preferably from 200 ppm to 7,000 ppm by weight and advantageously from 300 ppm to 4,000 ppm.

[0163] Regarding the process for manufacturing the liquid composition or syrup (methacrylic), a first step consists of preparing a first syrup comprising the (meth)acrylic monomer (Ml) or a mixture of (meth)acrylic monomers and a (meth)acrylic polymer (PI). The initiators (Ini2) and (Inil) are then added to the syrup, in the proportions indicated above in order to maintain a dynamic viscosity between 10 mPa*s and 10,000 mPa*s, at 25 °C.

[0164] Preferably, the (meth)acrylic polymer (PI) is added to the (meth)acrylic monomers and solubilized.

[0165] The initiator (Inil) is added, or the initiators (Ini2) and (Inil) may be added jointly or separately, one after the other. If they are added separately, the order does not matter.

[0166] Preferably, the initiator (Inil) or the initiators (Ini2) and (Inil) are added at a temperature Tadd below 50 °C, more preferably below 40 °C, advantageously below 30 °C and more advantageously below 25 °C.

[0167] The liquid composition according to the invention, detailed in the preceding paragraphs, can be used for the impregnation of fibers or a fibrous substrate or for the manufacture of thermoplastic parts or composite parts, in particular for the preparation of thermoplastic composites by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably an axisymmetric hollow body.

[0168] With regard to the fibers or fibrous substrate, one can mention several fibers, unidirectional strands or a mat of continuous filaments, fabrics, felts or nonwovens which may be in the form of strips, sheets, braids, strands or pieces. The fibrous material may have different shapes and dimensions, namely one-dimensional, two-dimensional or three-dimensional. A fibrous substrate comprises an assembly of one or more fibers. When the fibers are continuous, their assembly forms fabrics.

[0169] The one-dimensional form corresponds to long linear fibers. The fibers may be discontinuous or continuous. The fibers may be arranged randomly or parallel to each other, in the form of a continuous filament. A fiber is defined by its aspect ratio, which is the ratio between the length and the diameter of the fiber. The fibers used in the present invention are long fibers or continuous fibers. The fibers have an aspect ratio of at least 1000, preferably at least 1500, more preferably at least 2000, advantageously at least 3000, and more advantageously at least 5000, even more advantageously at least 6000, even more advantageously at least 7500, and most preferably at least 10,000.

[0170] The two-dimensional form corresponds to fibrous mats or reinforcements or bundles of non-woven or woven fibers, which may also be braided. Even if the two-dimensional form has a certain thickness and, consequently, in principle a third dimension, it is considered to be two-dimensional according to the present invention.

[0171] The origins of the fibrous material can be natural or synthetic. As natural materials, one can mention plant fibers, wood fibers, animal fibers or mineral fibers.

[0172] Natural fibers include, for example, sisal, jute, hemp, flax, cotton, coconut fibers and banana fibers. Animal fibers include, for example, wool or hair.

[0173] As a synthetic material, mention may be made of polymer fibres selected from thermosetting polymer fibres, thermoplastic polymers or mixtures thereof.

[0174] Polymer fibers can be made of polyamide (aliphatic or aromatic), polyester, polyvinyl alcohol, polyolefins, polyurethanes, polyvinyl chloride, polyethylene, unsaturated polyesters, epoxy resins and vinyl esters.

[0175] Mineral fibers can also be selected from glass fibers, in particular of type E, R or S2, carbon fibers, boron fibers, basalt fibers or silica fibers.

[0176] The fibrous substrate of the present invention is selected from plant fibers, wood fibers, animal fibers, mineral fibers, synthetic polymer fibers, glass fibers and carbon fibers, and mixtures thereof.

[0177] Preferably, the fibrous substrate is chosen from mineral fibers.

[0178] The fibers of the fibrous substrate 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.

[0179] Preferably, the fibers of the fibrous substrate of the present invention are chosen from continuous fibers (meaning that the aspect ratio does not necessarily apply as for long fibers) for the one-dimensional shape, or from long or continuous fibers for the two- or three-dimensional shape of the fibrous substrate.

[0180] According to another additional aspect, the invention relates to a polymer composite material comprising a thermoplastic (meth)acrylic matrix and a fibrous substrate used as reinforcement, the fibrous substrate being made up of long fibers, said composite material being characterized in that the thermoplastic (meth)acrylic matrix is ​​obtained after polymerization of said fibrous substrate impregnated with said liquid composition (LC1) according to the invention.

[0181] Another aspect of the present invention is a method for manufacturing thermoplastic composites by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably axisymmetric hollow body composite parts, by a method comprising the following steps:

[0182] i) impregnation of fibres or a fibrous substrate with the liquid composition (LC1),

[0183] ii) polymerization of at least a part of the liquid composition (LC1) during winding onto a mandrel.

[0184] The process may include an additional heating step.

[0185] By polymerization of at least a part of the liquid composition (LC1), it is understood that a part of the (meth)acrylic monomer (Ml) of the liquid composition (LC1) is polymerized, i.e. that the conversion of the monomer of the liquid composition (LC1) is at least 10%, preferably 15%.

[0186] The at least partial polymerization of the liquid composition (LC1), which impregnated the fibers or fibrous substrate during the manufacturing process of step ii), takes place at a temperature between 40 °C and 140 °C, preferably between 50 °C and 130 °C. In a first preferred embodiment, the temperature is between 50 °C and 100 °C, in a second preferred embodiment, the temperature is between 60 °C and 100 °C, and in a third preferred embodiment, the temperature is between 60 °C and 110 °C. The polymerization step ii) is more or less isothermal.Isothermal, in the present invention, means that the temperature during polymerization is maintained within a 20 K AT range of the polymerization temperature and does not include temperature ramps, where the temperature is, for example, decreased during polymerization or increased at the end and the temperature difference during polymerization is greater than 30 K. For example, the impregnated fibrous substrate is heated to 70 °C on the mandrel and the temperature at the end does not exceed 90 °C. Or, for example, the impregnated fibrous substrate is heated to 70 °C and the temperature during at least the polymerization step remains within a 20 K range: between 60 °C and 80 °C or also between 65 °C and 85 °C.

[0187] Advantageously, the temperature during polymerization is maintained within an AT range of 28 K, more advantageously 26 K, even more advantageously 24 K, even more advantageously 22 K and most advantageously 20 K.

[0188] As regards the step of the process (105) of supplying fibers, it can be carried out, for example, by means of a spool of fibers (10). There could be one spool of fibers or several spools of fibers. For example, two spools of fibers (10) are shown in system (1) of [Fig. 2].

[0189] There could be from one reel of fiber up to 100 reels of fiber. Usually, there are between 1 and 50 reels.

[0190] In a first preferred embodiment, there are between 1 and 40 reels.

[0191] In a second preferred embodiment, there are between 2 and 40 reels.

[0192] As regards the step of the process (110) of supplying the liquid composition (LC1), it can be carried out, for example, by means of a conduit. Said conduit brings the liquid composition (LC1) to the impregnation medium, which is for example a bath (20) in the system (1) of the [Fig.2].

[0193] As regards the step of the process (120) of impregnating the fibers or fibrous substrate, it consists of impregnating the fibrous substrate with the liquid composition (LC1).

[0194] This impregnation step (120) is carried out using an impregnation means (20). It can, for example, take place in a bath or a die or an impregnation head.

[0195] If the viscosity of the liquid composition (LC1) at a given temperature is slightly too high for the impregnation process, it is possible to heat the syrup so as to obtain a more liquid syrup for sufficient wetting and correct and complete impregnation of the fibrous substrate.

[0196] With regard to the step of the process (130) of winding the impregnated fibrous material around a mandrel, said winding is carried out for a winding time tb and at least partial polymerization of the liquid composition (LC1) takes place during the winding onto a mandrel. The winding time ti could be from 5 minutes to several hours.

[0197] Preferably, the winding takes place for a winding time ti to obtain a thickness between 1 mm and 100 mm.

[0198] The winding is carried out layer by layer around the mandrel until the desired thickness is obtained.

[0199] With regard to the step of the process (140) of heating the wound fibrous material to a temperature Th, said heating is carried out for a heating time t2 to polymerize a part of the (meth)acrylic monomer (Ml) of the liquid composition (LC1).

[0200] The heating of the heating stage (140) is carried out by a heating means (40). Preferably, the heating means (40) is chosen from an infrared heating means.

[0201] The distance di between the heating means (40) and the surface (60) of the chuck or the highest area is at least 10 mm. The distance di is between 10 mm and 500 mm and also depends on the power of the heating means (40). Usually, the distance di is between 10 mm and 500 mm; preferably, the distance di is between 20 mm and 300 mm.

[0202] The temperature Th is chosen according to the initiator (Inil). The temperature Th is preferably higher than the half-life at temperature ti / 2 of 10 hours of the initiator (Inil). The temperature Th is preferably lower than the half-life at temperature ti / 2 of 0.1 hours of the initiator (Inil).

[0203] In a first preferred embodiment, the temperature Th is between the half-life at temperature ti / 2 of 10 hours of the initiator (Inil) and the half-life at temperature ti / 2 of 0.1 hours of the initiator (Inil).

[0204] In a second preferred embodiment, the temperature Th is greater than the half-life at temperature ti / 2 of 1 hour of the initiator (Inil).

[0205] In a third preferred embodiment, the temperature Th is between 10 °C below the half-life at temperature ti / 2 of 1 hour of the initiator (Inil) and 15 °C above the half-life at temperature ti / 2 of 1 hour of the initiator (Inil).

[0206] The partial polymerization of the liquid composition (LC1) that has impregnated the fibers or fibrous substrate due to the heating step (140) takes place at a temperature Th between 40 °C and 140 °C, preferably between 50 °C and 130 °C. In a first preferred embodiment, the temperature Th is between 50 °C and 100 °C, in a second preferred embodiment, the temperature Th is between 60 °C and 100 °C, and in a third preferred embodiment, the temperature Th is between 60 °C and 110 °C. The polymerization is more or less isothermal.Isothermal, in the present invention, means that the temperature during polymerization is maintained within a 20 K AT range of the polymerization temperature and does not include temperature ramps, where the temperature is, for example, decreased during polymerization or increased at the end and the temperature difference during polymerization is greater than 30 K. For example, the impregnated fibrous substrate is heated to 70 °C on the mandrel and the temperature at the end does not exceed 90 °C. Or, for example, the impregnated fibrous substrate is heated to 70 °C and the temperature during at least the polymerization step remains within a 20 K range: between 60 °C and 80 °C or also between 65 °C and 85 °C.

[0207] Advantageously, the temperature Th during polymerization is maintained within an AT range of 28 K, more advantageously 26 K, even more advantageously 24 K, even more advantageously 22 K and most advantageously 20 K.

[0208] Polymerizing a portion of the (meth)acrylic monomer (Ml) of the liquid composition (LC1) means that the conversion of the monomer (Ml) of the liquid composition (LC1) that has impregnated the fibrous material is at least 10%, preferably 15%. This conversion ratio applies to the monomer (Ml) of the entire manufactured hollow body.

[0209] In a first preferred embodiment, the conversion of the monomer (Ml) from the liquid composition (LC1) is 20%.

[0210] In a second preferred embodiment, the conversion of the monomer (Ml) from the liquid composition (LC1) is 30%.

[0211] In a third preferred embodiment, the conversion of monomer (Ml) from the liquid composition (LC1) is 40%.

[0212] In a fourth preferred embodiment, the conversion of monomer (Ml) from the liquid composition (LC1) is 50%.

[0213] In a fifth preferred embodiment, the conversion of monomer (Ml) from the liquid composition (LC1) is 60%.

[0214] In a sixth preferred embodiment, the conversion of monomer (Ml) from the liquid composition (LC1) is 70%.

[0215] In a seventh preferred embodiment, the conversion of monomer (Ml) from the liquid composition (LC1) is 80%.

[0216] In an eighth preferred embodiment, the conversion of monomer (Ml) from the liquid composition (LC1) is 90%.

[0217] In a tenth preferred embodiment, the conversion of monomer (Ml) from liquid composition (LC1) is 95%.

[0218] In an eleventh preferred embodiment, the conversion of monomer (Ml) from liquid composition (LC1) is 99%.

[0219] As previously stated, the winding is carried out layer by layer around the mandrel until the desired thickness is obtained, so the difference in monomer conversion (Ml) could depend on the respective layer. For example, in an outermost layer, the conversion may be lower because this layer was heated for a shorter time than an innermost layer that was exposed to the heating medium for a longer time. There could be a conversion gradient throughout the thickness of the partially polymerized wound composite material.

[0220] Preferably, the winding step (130) and the heating step (140) take place at least partially in parallel. Heating could begin before winding onto the mandrel, or simultaneously with winding, or once the first wound fibrous material is already present on the mandrel. Heating could also be stopped shortly before the winding is complete. Heating could also be continued after winding is complete and the desired thickness is achieved.

[0221] With regard to the possible process step (150) of regulating the temperature on the surface (60) of the chuck, said regulation is carried out using a temperature regulation means (50) such as, for example, a temperature sensor.

[0222] By "on the surface (60) of the mandrel," we mean the highest area. At the very beginning of the winding step (130), this refers primarily to the mandrel itself, since the wound fibrous material does not yet cover the entire mandrel. This is the case, for example, in [Fig. 2], where only part of the mandrel is covered by the impregnated fibrous material. As winding continues, the wound fibrous material covers the entire mandrel, and the thickness increases layer by layer, with the highest area then corresponding to the outermost layers of the wound fibrous material.

[0223] Regulation is necessary if it is not expected that the temperature Th will remain within the upper and lower temperature limits as defined previously.

[0224] With regard to the possible adaptation process step (160), this step is only carried out if, during the regulation step (150), the temperature Th must not remain within the upper and lower limits as defined previously.

[0225] The adaptation can be achieved either by changing the rotation speed vr of the chuck during the winding step (130), or by changing the distance di between the heating means (40) and the surface (60) of the chuck, or by changing the power of the heating means (40).

[0226] If the temperature Th becomes too low, either the rotation speed vr of the chuck during the winding step (130) is also lowered, or the distance di between the heating means (40) and the surface (60) of the chuck is decreased, or the power of the heating means (40) is increased.

[0227] If the temperature Th becomes too high, either the rotation speed vr of the chuck during the winding step (130) is also increased, or the distance di between the heating means (40) and the surface (60) of the chuck is increased, or the power of the heating means (40) is reduced.

[0228] The adaptation can also be carried out by a combination of at least two of the possibilities described above.

[0229] In a first preferred embodiment, the adaptation consists of modifying the rotation speed vr of the chuck during the winding step (130).

[0230] In a second preferred embodiment, the adaptation consists of modifying the distance di between the heating means (40) and the surface (60) of the chuck or the highest zone.

[0231] In a third preferred embodiment, the adaptation consists of modifying the power of the heating means (40).

[0232] With regard to the eventual process step (170) of hardening, this step is only carried out if the conversion of monomer (Ml) is not sufficiently high, namely if the conversion of monomer (Ml) is less than 90%.

[0233] In a first preferred embodiment, the hardening step (170) takes place if the conversion of the monomer (Ml) is less than 95%.

[0234] In a second preferred embodiment, the hardening step (170) takes place if the conversion of the monomer (Ml) is less than 98%.

[0235] In a second preferred embodiment, the hardening step (170) takes place if the conversion of the monomer (Ml) is less than 99%.

[0236] Hardening (170) can for example take place in an oven.

[0237] The temperature Te during the hardening step (170) is greater than the temperature Th during the heating step (140).

[0238] Preferably, the hardening step (170) takes place if at least two initiators (Inil) and (Ini2) are present in the liquid composition (LC1).

[0239] More preferably, the hardening step (170) takes place if the initiator (Ini2) has, at a given temperature Tb, a half-life ti / 2 greater than that of the first initiator (Inil) present in the liquid composition (LC1).

[0240] Even more preferably, the hardening step (170) takes place if the second initiator (Ini2) has, at a given temperature Tb, a half-life ti / 2 which is at least twice the half-life ti / 2 of the first initiator (Inil).

[0241] A first preferred process (100) for manufacturing thermoplastic composites includes the steps of impregnation (120), winding (130) and heating (140).

[0242] A second preferred process (100) for manufacturing thermoplastic composites includes the steps of supplying (105) fibers, supplying (110) the liquid composition (LC1), impregnating (120), winding (130) and heating (140).

[0243] A third preferred process (100) for manufacturing thermoplastic composites includes the steps of supplying (105) fibers, supplying (110) the liquid composition (LC1), impregnating (120), winding (130) and heating (140).

[0244] A fourth preferred process (100) for manufacturing thermoplastic composites includes the steps of supplying (105) fibers, supplying (110) the liquid composition (LC1), impregnating (120), winding (130), heating (140) and curing (170).

[0245] A fifth preferred process (100) for manufacturing thermoplastic composites includes the steps of supplying (105) fibers, supplying (110) the liquid composition (LC1), impregnating (120), winding (130), heating (140), regulating (150) and curing (170).

[0246] A sixth preferred process (100) for manufacturing thermoplastic composites includes the steps of supplying (105) fibers, supplying (110) the liquid composition (LC1), impregnating (120), winding (130), heating (140), regulating (150), adapting (160) and curing (170).

[0247] A seventh preferred process (100) for manufacturing thermoplastic composites includes the steps of supplying (105) fibers, supplying (110) the liquid composition (LC1), impregnating (120), winding (130), heating (140), regulating (150) and adapting (160).

[0248] After the process or method (100) of manufacturing thermoplastic composites, as well as mechanical or structured parts or products, there may also be a postforming step. Postforming includes bending, compression, and modification of the shape of the composite part.

[0249] With regard to the use of mechanical parts made of composite material thus manufactured, examples include sports applications, energy applications, transport applications, in particular the transport of liquids and gases, and storage applications, in particular the storage of liquids and gases.

[0250] The invention also relates to an object obtained with a liquid composition or by a process or method (100).

[0251] The object is a mechanical part made of or comprising composite material.

[0252] The mechanical part made of composite material is in particular a shaft, a tube, a pipe or a tank.

[0253] In a first preferred embodiment, the mechanical part made of composite material is in particular a material for a storage tank.

[0254] In a second preferred embodiment, the mechanical part made of composite material is in particular a high-pressure storage tank.

Claims

Demands

1. Liquid composition (LC1) suitable for the preparation of thermoplastic composites by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably an axisymmetric hollow body, said composition comprising: a) a (meth)acrylic polymer (PI), b) a (meth)acrylic monomer (Ml), and c) at least one initiator (Inil), said liquid composition (LC1) having a dynamic viscosity between 10 mPa*s and 10,000 mPa*s at 25 °C.

2. Liquid composition (LC1) according to claim 1, characterized in that the composition comprises at least two initiators (Inil) and (Ini2).

3. Liquid composition (LC1) according to claim 1 or 2, characterized in that the amount of at least one initiator (Inil) or the amount of at least two initiators (Inil) and (Ini2) jointly in the composition is between 0.1 phr and 15 phr relative to the sum of the (meth)acrylic monomer (Ml) and the (meth)acrylic polymer (PI).

4. Liquid composition (LC1) according to claim 2 or 3, characterized in that the initiator (Inil) or the two initiators (Inil) and (Ini2) have, at any given temperature Tl, different half-lives ti / 2.

5. Liquid composition according to any one of claims 1 to 4, characterized in that the initiator (Inil) or both initiators (Inil) and (Ini2) are selected from diacyl peroxides, peroxyesters, peroxydicarbonates, dialkyl peroxides, peroxyacetals, a hydroperoxide or a peroxyketal.

6. Liquid composition according to any one of claims 1 to 5, characterized in that the initiator (Inil) or both initiators (Inil) and (Ini2) are selected from diisobutyryl peroxide, cumyl peroxyneodecanoate, di(3-methoxybutyl) peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, cumyl peroxyneoheptanoate, di-n-propyl peroxydicarbonate, tert-amyl peroxyneodecanoate, di-sec-butyl peroxydicarbonate, peroxydicarbonate

7. diisopropyl, di(4-tert-butylcyclohexyl) peroxydicarbonate, di-(2-ethylhexyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, di-n-butyl peroxydicarbonate, diketyl peroxydicarbonate, dimyristyle peroxydicarbonate, 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, peroxy-2-ethylhexanoate 1,1,3,3-tetramethylbutyl, tert-amyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxydiethyl acetate, tert-butyl peroxyisobutyrate, 1,1-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, tert-butyl peroxy-3,5,5-trimethylhexanoate, 2,2-di-(tert-butylperoxy)-butane, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxy-2-ethylhexylcarbonate, tert-amyl peroxybenzoate, tert-butyl peroxyacetate, butyl 4,4-di(tert-butylperoxy)valerate, tert-butyl peroxybenzoate, di-tert-amyl peroxide, dicumyl peroxide, di-(2-tert-butyl-peroxyisopropyl)-benzene, 2,5-dimethyl-2,5-di-(tert-butylperoxy)-hexane, tert-butylcumyl peroxide, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexyne-3, di-tert-butyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azodi-(2-methylbutyronitrile), Fazobisisobutyramide, 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azodi(hexalihydrobenzonitrile) or 4,4'-azobis(4-cyanopentanoic acid). Liquid composition according to any one of claims 1 to 6, characterized in that the initiator (Inil) is selected from cumyl peroxydecanoate, di(3-methoxybutyl) peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxydecanoate, cumyl peroxyheptanoate, di-n-propyl peroxydicarbonate, tert-amyl peroxydecanoate, di-sec-butyl peroxydicarbonate, diisopropyl peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di-(2- ethylhexyl), tert-butyl peroxyneodecanoate, di-n-butyl peroxydicarbonate, diketyl peroxydicarbonate, dimyristyle peroxydicarbonate, 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.

8. Liquid composition according to any one of claims 2 to 6, characterized in that the initiator (Ini2) is selected from 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, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, 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, 1,1-di-(tert-butylperoxy)-cyclohexane, tert-amyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxyacetate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 2,2-di-(tert-butylperoxy)-butane, tert-butyl peroxyisopropyl carbonate,tert-butyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxybenzoate, tert-butyl peroxyacetate, butyl 4,4-di(tert-butylperoxy)valerate, tert-butyl peroxybenzoate, di-tert-amyl peroxide, dicumyl peroxide, di-(2-tert-butyl-peroxyisopropyl)benzene, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, di-tert-butyl peroxide, or 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane.

9. Liquid composition according to any one of claims 1 to 8, characterized in that the (meth)acrylic polymer (PI) comprises at least 50% by weight of methyl methacrylate (MMA).

10. Liquid composition according to any one of claims 1 to 9, characterized in that 50% by weight of the (meth)acrylic monomer (Ml) is methyl methacrylate.

11. Use of the liquid composition according to any one of claims 1 to 10 for the manufacture of thermoplastic composite parts by filament winding.

12. System (1) for preparing thermoplastic composites by filament winding, the thermoplastic composite being preferably a hollow body, and more preferably an axisymmetric hollow body, said system (1) comprising: one or more spools of fibers (10), an impregnation means (20) for impregnating the fibers (15) with a liquid composition (LC1) according to any one of claims 1 to 10, a mandrel (30), a heating means (40), and optionally a temperature control means (50).

13. System according to claim 12, characterized in that it comprises a temperature control means (50).

14. A method for manufacturing a thermoplastic composite by filament winding, the thermoplastic composite preferably being a hollow body, and more preferably an axisymmetric hollow body, by a method comprising the following steps: i) impregnation of fibers or a fibrous substrate with the liquid composition (LC1) according to any one of claims 1 to 10, ii) polymerization of at least a portion of the liquid composition (LC1) during winding onto a mandrel.

15. A method according to claim 14, characterized in that the method comprises a heating step.

16. A process according to claim 14 or 15, characterized in that the conversion of monomer (Ml) from the liquid composition (LC1) during the polymerization step is at least 10%.

17. A method according to claim 14 or 15, characterized in that the temperature during step ii) is between 40 °C and 140 °C.

18. A method according to claim 14 or 15, characterized in that the thermoplastic composite is a hollow body, preferably an axisymmetric hollow body.

19. A method (100) for manufacturing a thermoplastic composite, preferably a hollow body, more preferably a body axisymmetric hollow, comprising a layer of composite material, said process comprising the following steps: - optionally a step of supplying fibers or fibrous material, - optionally a step of supplying (110) the liquid composition (LC1) according to any one of claims 1 to 10; - a step of impregnating (120) a fibrous material with the liquid composition (LC1) according to any one of claims 1 to 10; - a step of winding (130) the impregnated fibrous material around a mandrel, said winding being carried out for a winding time ti; and - a step of heating (140) the wound fibrous material to a temperature Th, said heating being carried out for a heating time t2 to polymerize a portion of the (meth)acrylic monomer (Ml) of the liquid composition (LC1); - optionally a step of regulating the temperature;- possibly an adaptation stage (160), - possibly a hardening stage (170).;

20. Method according to claim 19, characterized in that the heating (140) is carried out with a heating means (40), the heating means (40) preferably being chosen from an infrared heating means.

21. A process according to claim 19, characterized in that the conversion of the monomer (Ml) from the liquid composition (LC1) which has impregnated the fibrous material is at least 10%.

22. A process according to claim 19, characterized in that the conversion of the monomer (Ml) from the liquid composition (LC1) which has impregnated the fibrous material is at least 90%.

23. A method according to claim 19, characterized in that the temperature Th is between 40 °C and 140 °C, preferably between 50 °C and 130 °C.

24. A method according to any one of claims 19 to 23, characterized in that the method (100) comprises the hardening step (170).

25. A method according to any one of claims 19 to 23, characterized in that the method (100) comprises the temperature control step (150).

26. A method according to any one of claims 19 to 25, characterized in that the method (100) comprises the adaptation step (160).

27. ​​A process according to any one of claims 19 to 23, characterized in that the process (100) comprises the steps of supplying (105) fibers, supplying (110) the liquid composition (LC1), impregnation (120), winding (130), heating (140), regulating (150) and curing (170).

28. A process according to any one of claims 19 to 23, characterized in that the process (100) comprises the steps of supplying (105) fibers, supplying (110) the liquid composition (LC1), impregnation (120), winding (130), heating (140), regulating (150), adapting (160) and curing (170).

29. Mechanical part made of composite material or comprising a composite material obtained via the process according to claims 19 to 28.

30. Part according to claim 29, said part being a shaft, tube, pipe or tank or storage tank or high pressure storage tank.

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