阅读说明：本技术 制造热塑性聚合物复合材料部件的方法，和通过所述方法获得的物体 (Method for manufacturing a thermoplastic polymer composite part, and object obtained by said method ) 是由 V.博茨扎克 G.克莱达 P.格拉尔 M.格洛坦 于 2018-03-13 设计创作，主要内容包括：本发明涉及由至少两个由热塑性聚合物复合材料制成的部件(10)来制造由热塑性聚合物复合材料制成的物体(1)的方法(100),所述热塑性聚合物复合材料包含纤维增强材料和热塑性聚合物基质,所述方法包括以下步骤：在组装界面区域(11)处相邻或重叠布置(120)两个由热塑性聚合物复合材料制成的部件(10),在所述组装界面区域(11)处加热(130)以熔融该热塑性聚合物基质,从而形成包含焊接界面(12)的由热塑性聚合物复合材料制成的物体(1)。(The invention relates to a method (100) for manufacturing an object (1) made of a thermoplastic polymer composite from at least two parts (10) made of a thermoplastic polymer composite, said thermoplastic polymer composite comprising a fibrous reinforcement and a thermoplastic polymer matrix, said method comprising the steps of: two parts (10) made of thermoplastic polymer composite are arranged (120) adjacently or overlappingly at an assembly interface area (11), and the thermoplastic polymer matrix is heated (130) at said assembly interface area (11) to melt it, thereby forming an object (1) made of thermoplastic polymer composite comprising a welding interface (12).)

1. Method (100) for manufacturing an object (1) made of a thermoplastic polymer composite from at least two parts (10) made of a thermoplastic polymer composite, the thermoplastic polymer composite comprising a fibrous reinforcement and a thermoplastic polymer matrix, the method comprising the steps of:

-arranging (120) two parts (10) made of thermoplastic polymer composite adjacent or overlapping at an assembly interface area (11),

-heating (130) at the assembly interface region (11) to melt the thermoplastic polymer matrix, thereby forming an object (1) made of thermoplastic polymer composite comprising a welding interface (12).

2. A manufacturing method as claimed in claim 1, characterized in that said at least two parts made of thermoplastic polymer composite are parts made of (meth) acrylic thermoplastic polymer composite.

3. A manufacturing process as claimed in claim 1 or 2, characterized in that it comprises a preceding step of manufacturing (110) at least two parts (10) made of a (meth) acrylic thermoplastic polymer composite comprising a fibrous reinforcement and a (meth) acrylic thermoplastic polymer matrix.

4. A manufacturing process as claimed in any one of claims 1 to 3, characterized in that the fibrous reinforcement comprises fibres selected from carbon fibres or glass fibres or basalt fibres or polymer-based fibres or plant fibres, alone or in a mixture.

5. A manufacturing process as claimed in any one of claims 1 to 4, characterized in that the fibrous reinforcement is based on fibres having an aspect ratio of at least 1000.

6. A manufacturing process as claimed in any one of claims 1 to 5, characterized in that it further comprises, after the heating step (130), a step of applying (140) pressure at the interface in order to weld together at least two parts (10) made of thermoplastic polymer composite.

7. A manufacturing process as claimed in any one of claims 2 to 6, characterized in that the (meth) acrylic thermoplastic polymer is chosen from poly (methyl methacrylate) (PMMA) or copolymers of Methyl Methacrylate (MMA), or mixtures thereof.

8. The production process as claimed in any one of claims 2 to 7, characterized in that the (meth) acrylic thermoplastic polymer has a glass transition temperature (Tg) of 50 ℃ to 160 ℃.

9. A manufacturing process as claimed in any one of claims 2 to 8, characterized in that the (meth) acrylic thermoplastic polymer matrix further comprises one or more additives or fillers.

10. A manufacturing method as claimed in any one of claims 3 to 9, characterized in that the step of manufacturing (110) at least two parts (10) made of a (meth) acrylic thermoplastic polymer composite comprises the sub-steps of:

-impregnating (111) a fibrous reinforcement with a liquid (meth) acrylic composition,

-polymerizing (112) the liquid (meth) acrylic composition.

11. The production process as claimed in claim 10, characterized in that the liquid (meth) acrylic composition comprises a (meth) acrylic monomer, a precursor (meth) acrylic polymer and a radical initiator.

12. The production method as claimed in claim 10, characterized in that the liquid (meth) acrylic composition comprises a (meth) acrylic monomer or a mixture of (meth) acrylic monomers, a precursor (meth) acrylic polymer.

13. The manufacturing process as claimed in claim 11 or 12, characterized in that the (meth) acrylic monomer or the mixture of (meth) acrylic monomers in the liquid (meth) acrylic composition or the liquid (meth) acrylic syrup is present in an amount of at least 40% by weight, preferably at least 45% by weight, more preferably at least 50% by weight, advantageously at least 60% by weight and more advantageously at least 65% by weight of the liquid (meth) acrylic composition.

14. The manufacturing process as claimed in claim 11 or 12, characterized in that the precursor (meth) acrylic polymer in the liquid (meth) acrylic composition or the liquid (meth) acrylic syrup is present in an amount of at least 10% by weight, preferably at least 15% by weight, advantageously at least 18% by weight and more advantageously at least 20% by weight of the liquid (meth) acrylic composition.

15. The manufacturing process as claimed in claim 11 or 12, characterized in that the precursor (meth) acrylic polymer in the liquid (meth) acrylic composition or the liquid (meth) acrylic syrup is present in an amount of at most 60% by weight, preferably at most 50% by weight, advantageously at most 40% by weight and more advantageously at most 35% by weight in the liquid (meth) acrylic composition.

16. The production method as claimed in claim 11 or 12, characterized in that in the liquid (meth) acrylic composition, the compound is blended in the following weight percentage:

the (meth) acrylic monomer in the liquid composition or the (meth) acrylic syrup is present in a proportion of 40 to 90% by weight and preferably 45 to 85% by weight of the composition composed of the (meth) acrylic monomer and the (meth) acrylic polymer,

the (meth) acrylic polymer in the liquid composition or in the (meth) acrylic syrup is present in a proportion of from 10% to 60% by weight and advantageously from 15% to 55% by weight of the composition consisting of one or more (meth) acrylic monomers and (meth) acrylic polymer; preferably, the (meth) acrylic polymer in the liquid composition is present in a proportion of 18 to 30 wt%, more preferably 20 to 25 wt% of the composition consisting of the (meth) acrylic monomer and the (meth) acrylic polymer.

17. A manufacturing method as claimed in any one of claims 1 to 16, characterized in that the part (10) made of thermoplastic polymer composite is manufactured at a temperature of less than 150 ℃, preferably less than 100 ℃.

18. A manufacturing method as claimed in any one of claims 1 to 17, characterized in that the part (10) made of thermoplastic polymer composite is manufactured by low-pressure injection moulding, infusion moulding or by moulding a strip pre-impregnated with (meth) acrylic thermoplastic polymer composite.

19. A manufacturing process as claimed in any one of claims 1 to 18, characterized in that at least one of said two parts (10) made of thermoplastic polymer composite comprises, on the surface intended to be welded, a layer (13) of (meth) acrylic thermoplastic polymer at least 0.5 mm thick.

20. The manufacturing method as claimed in any one of claims 1 to 19, characterized in that the temperature at the welding interface (11) during the heating step is 160 to 300 ℃.

21. A manufacturing process as claimed in any one of claims 1 to 20, characterized in that said thermoplastic polymer matrix is melted (130) by a technique selected from: ultrasonic welding, induction welding, resistance wire welding, friction stir welding, laser welding, heating by infrared or ultraviolet radiation, and preferably by resistance wire welding.

22. The manufacturing method as claimed in any one of claims 1 to 21, characterized in that at least one of the two parts (10) made of thermoplastic polymer composite comprises at least one resistance wire located at the assembly interface (11).

23. Object (1) made of a polymer composite made of at least two parts (10) made of a polymer composite, characterized in that the thermoplastic polymer composite comprises a fibrous reinforcement and a thermoplastic polymer matrix, preferably a (meth) acrylic thermoplastic polymer matrix, and in that the at least two parts (10) made of a thermoplastic polymer composite are connected by a welding interface (12).

24. An object made of a polymer composite as claimed in claim 23, characterized in that it does not contain more than 50% by weight, preferably not more than 30% by weight, of thermosetting polymer.

25. An object made of a polymer composite as claimed in claim 23, characterized in that it does not contain more than 15% by weight, preferably not more than 10% by weight, of thermosetting polymer.

26. Object made of a polymer composite as claimed in one of claims 23, 24 or 25, characterized in that it does not contain more than 10% by weight, preferably not more than 8% by weight, of a binder, preferably a thermosetting binder.

27. An object made of a polymer composite as claimed in any one of claims 23, 24 or 25, characterized in that it does not contain more than 6% by weight, preferably not more than 5% by weight, of a thermosetting binder.

28. An object made of a polymer composite as claimed in any one of claims 23 to 27, characterized in that the (meth) acrylic thermoplastic polymer is selected from poly (methyl methacrylate) (PMMA) or a copolymer of Methyl Methacrylate (MMA), or a mixture thereof.

29. An object made of a polymer composite as claimed in any one of claims 23 to 28, characterized in that it is selected from: cladding consisting of a plurality of panels, rails, window profiles, aircraft fuselages, reinforcements for buildings, cross-members, in particular for vehicles, body-in-white parts, nacelles, empennages, ribs, spoilers, flaps, turbine blades for ships, hulls, bridges, bulkheads for ships and trim panels (covers) for automobiles.

[Prior Art]

Objects based on polymer composites comprising fibrous reinforcements fixed in a rigid polymer matrix are increasingly used in all fields, in particular in the construction, automotive, aeronautics and astronautics fields. This is because these fiber-reinforced polymer composites have high strength to weight ratios and desirable mechanical properties, making them increasingly widely used for the manufacture of objects such as skins, stiffeners, beams, body-in-white, profiles, nacelles, doors, empennages, fins, spoilers or flaps.

The polymers used to produce these objects are typically thermosetting polymers, and the techniques for producing these objects typically include manufacturing the components to be assembled by processes such as low pressure injection molding, impregnation, infusion molding, Vacuum Assisted Resin Infusion (VARI), pultrusion, vacuum infusion molding, pressurized infusion molding, resin transfer molding and variations thereof, or molding of prepregs.

Various techniques are used to assemble these parts made of polymer composites. These attachment techniques mainly include mechanical fastening and adhesive bonding (adhesives). Rivet assembly is relatively expensive (e.g., in terms of labor) and complex to implement, and the rivets used increase overall weight. Adhesive bonds (e.g., epoxy or polyester or polyurethane adhesives) are also expensive and complex because they require special preparation of the surfaces to be adhesively bonded together and often require specific curing and/or equipment to be performed. Furthermore, these thermoset polymer composites are not recyclable except for less than optimal attachment means.

In order to cope with these problems, it has been proposed to produce parts made of thermoplastic material (which are assembled by welding techniques). In welding, the temperature of the parts to be assembled is raised above the melting or softening point of the polymer matrix, and the parts are placed in the assembly position until the resin cools to obtain a mechanical bond in the assembly area.

Thus, objects made of thermoplastic polymers have been developed. They are generally recyclable and can be attached by welding techniques. However. These objects made of thermoplastic polymers are formed by methods that are incompatible with the machines developed for objects made of thermoset polymer composites. Furthermore, such systems require the use of high temperatures (typically above 100 ℃) in order to create the parts to be assembled. Such constraints limit in particular the production of large-size parts.

Accordingly, there is a need for a method of manufacturing an object made of a thermoplastic polymer composite that can address the problems posed by prior methods, that is easy to implement, and that does not require high temperatures to manufacture the components that make up the object made of the thermoplastic polymer composite.

[ problem of the invention]

The present invention therefore aims to overcome the disadvantages of the prior art. In particular, it is an object of the present invention to provide a method for manufacturing a part made of a thermoplastic polymer composite faster than in the prior art, and which is also capable of being assembled, repaired or adjusted quickly and easily.

It is another object of the present invention to provide an object made of a thermoplastic polymer composite which can be manufactured more quickly than conventional objects made of thermosetting polymer composites, while being preferably mainly recyclable, and resistant to the mechanical and chemical stresses which the object may encounter during its use.

[ summary of the invention]

To this end, the invention relates to a method for manufacturing an object made of a thermoplastic polymer composite from at least two parts made of a thermoplastic polymer composite, said thermoplastic polymer composite comprising a fibrous reinforcement and a thermoplastic polymer matrix, said method comprising the steps of:

-arranging two parts made of thermoplastic polymer composite adjacent or overlapping at an assembly interface area,

-heating at said assembly interface area to melt the thermoplastic polymer matrix, thereby forming an object made of thermoplastic polymer composite comprising a welding interface.

In fact, the use of thermoplastic polymer composites comprising (meth) acrylic thermoplastic polymers enables a reduction in cycle times, in particular compared with the thermosetting polymers conventionally used. Thus, the method can save production time as compared with the conventional method using a thermosetting polymer.

Furthermore, unlike objects made of thermosetting polymer composite materials that are commonly used in these fields, objects made of thermoplastic polymer composite materials obtained from the manufacturing method of the present invention are easy to recycle. Finally, the presence of a welding interface provides the possibility to manufacture the assembly, to make part position adjustments or to repair via increasing the interface temperature without the need for special installation.

According to other optional features of the method:

-the at least two parts made of thermoplastic polymer composite are parts made of (meth) acrylic thermoplastic polymer composite. Furthermore, the method preferably comprises a prior step of manufacturing at least two parts made of a (meth) acrylic thermoplastic polymer composite comprising a fibrous reinforcement and a (meth) acrylic thermoplastic polymer matrix. Indeed, in the context of the use of (meth) acrylic thermoplastic polymer composites, the manufacturing process of the invention can be carried out using thermoplastic polymer composite parts manufactured with the currently most commonly used industrial equipment (e.g. low-pressure injection moulding, infusion moulding), and therefore, unlike parts made of thermoplastic polymer composites such as polyamides, it does not require modifications of the industrial equipment currently used for the various fields of application of the invention. Thus, in this embodiment, unlike the method using a conventional thermoplastic polymer (e.g., polyamide), the manufacturing method of the present invention does not involve raising the temperature to a high temperature (e.g., >200 ℃) in all parts, and thus parts having a large size can be easily assembled.

-the fibrous reinforcement comprises fibres selected from carbon fibres or glass fibres or basalt fibres or polymer-based fibres or plant fibres, alone or in a mixture.

-the fibrous reinforcement is based on fibres having an aspect ratio of at least 1000. Such aspect ratios enable objects made of thermoplastic polymer composites with improved mechanical properties to be obtained.

The step of manufacturing at least two parts made of thermoplastic polymer composite material comprises the sub-steps of:

-impregnating the fibrous reinforcement with a liquid (meth) acrylic composition,

-polymerizing the liquid (meth) acrylic composition.

The manufacturing method further comprises the step of applying pressure at the assembly interface. This enables at least two parts made of thermoplastic polymer composite to be welded together with an enhanced welding interface.

-the (meth) acrylic thermoplastic polymer is chosen from (meth) acrylic thermoplastic polymers consisting of liquid (meth) acrylic compositions commonly known as "slurries" or thermoplastic polymer resins. This liquid (meth) acrylic composition is used to impregnate the fibrous reinforcement, followed by polymerization. After polymerization, it constitutes the matrix of the polymer composite. The polymerization is rapidly carried out with good conversion (e.g., 30 seconds to 3 hours) to improve productivity. Liquid compositions or slurries comprising (meth) acrylic monomers and a precursor (meth) acrylic polymer are described in WO 2013/056845 and WO 2014/013028. For example, the precursor (meth) acrylic thermoplastic polymer is selected from a copolymer of poly (methyl methacrylate) (PMMA) or Methyl Methacrylate (MMA), or a mixture thereof. Preferably, the precursor (meth) acrylic thermoplastic polymer may be selected from a homopolymer of Methyl Methacrylate (MMA) or a copolymer comprising at least 50%, preferably at least 70%, more preferably at least 80%, advantageously at least 90% and more advantageously at least 95% by weight of methyl methacrylate. The (meth) acrylic polymers, for example obtained from poly (methyl methacrylate) (PMMA) or copolymers of Methyl Methacrylate (MMA), or mixtures thereof, are particularly suitable for the existing industrial processes for manufacturing objects made of polymer composite materials, and impart satisfactory mechanical and chemical properties to objects made of polymer composite materials.

-the (meth) acrylic thermoplastic polymer has a glass transition temperature (Tg) of from 50 ℃ to 160 ℃, preferably from 70 ℃ to 140 ℃ and even more preferably from 90 ℃ to 120 ℃. Furthermore, the (meth) acrylic thermoplastic polymer or a part of the (meth) acrylic thermoplastic polymer has a Melt Flow Index (MFI) according to ISO 1133 (230 ℃/3.8 kg) of less than 20 g/10 min. The melt flow index is preferably less than 18 g/10 min, more preferably less than 16 g/10 min, advantageously less than 13 g/10 min. This makes it possible to facilitate the production of objects made of polymer composite material and to easily carry out assembly, adjustment or maintenance.

-the (meth) acrylic thermoplastic polymer matrix further comprises one or more additives or fillers. All optional additives and fillers are added to the liquid (meth) acrylic syrup prior to impregnation and/or polymerization. As additives, organic additives such as impact modifiers or block copolymers, heat stabilizers, UV stabilizers, lubricants and mixtures thereof may be mentioned. The impact modifier is in the form of fine particles having an elastomeric core and at least one thermoplastic shell, the size of the particles generally being less than 1 μm and advantageously being from 50 to 300 nm. The impact modifier is preferably prepared by emulsion polymerization. The proportion of impact modifier in the thermoplastic polymer matrix is from 0 to 50% by weight, preferably from 0 to 25% by weight, advantageously from 0 to 20% by weight. As fillers, mention may be made of carbon nanotubes or mineral fillers, including mineral nanofillers (TiO)₂Silicon dioxide).

-parts made of thermoplastic polymer composite are manufactured at a temperature of less than 150 ℃, preferably less than 120 ℃, even more preferably less than 100 ℃. In fact, the liquid (meth) acrylic compositions used in the manufacturing process of parts made of polymer composite materials are liquid at temperatures well below the conventional melting point of conventional thermoplastics. This thus enables the production of very large-sized parts made of thermoplastic polymer composite materials without the need to carry out a process of heating the parts to high temperatures.

-the part made of thermoplastic polymer composite is manufactured by low pressure injection moulding, infusion moulding or by moulding a strip pre-impregnated with a (meth) acrylic thermoplastic polymer composite.

-at least one of said two parts made of thermoplastic polymer composite comprises, on the surface intended to be welded, a (meth) acrylic thermoplastic polymer layer at least 0.5 mm, preferably 1 mm, more preferably at least 2 mm thick. This makes it possible in particular to avoid regions with a lower concentration of resin at the welding interface, which may lead to embrittlement of the object made of the thermoplastic polymer composite.

-the temperature at the assembly interface during the heating step is 160 to 300 ℃, preferably 200 to 250 ℃.

-the thermoplastic polymer matrix, preferably a (meth) acrylic thermoplastic polymer matrix, is melted by a technique selected from: ultrasonic welding, induction welding, resistance wire welding, friction stir welding, laser welding, heating by infrared or ultraviolet radiation, preferably by resistance wire welding.

-at least one of said two parts made of thermoplastic polymer composite comprises at least one resistive wire at the assembly interface.

The invention further relates to an object made of a thermoplastic polymer composite made of at least two parts made of a thermoplastic polymer composite, characterized in that the thermoplastic polymer composite comprises a fibrous reinforcement and a thermoplastic polymer matrix, preferably a (meth) acrylic thermoplastic polymer matrix, and in that the at least two parts made of a thermoplastic polymer composite are connected by a welding interface.

According to other optional features of the object:

objects made of thermoplastic polymer composites do not contain more than 50%, preferably not more than 40%, more preferably not more than 30%, even more preferably not more than 20%, more advantageously not more than 15% and even more advantageously not more than 10% by weight of thermosetting polymers such as epoxy resins. Thus, the object made of thermoplastic polymer composite material of the present invention has a very significant gain in production time and has an improved recycling capacity. Likewise, objects made of thermoplastic polymer composites do not comprise more than 10 wt.%, preferably not more than 8 wt.%, advantageously not more than 7 wt.%, more advantageously not more than 6 wt.% and even more advantageously not more than 5 wt.% of a binder, preferably a thermosetting binder.

-said object made of thermoplastic polymer composite is selected from: cladding consisting of a plurality of panels, rails, window profiles, aircraft fuselages, reinforcements for buildings, cross-members (especially for vehicles), body in white parts, nacelles, empennages, ribs, spoilers, flaps, turbine blades for ships, ship hulls, ship bridges, cabin walls for ships and trim panels (covers) for automobiles.

Other advantages and characteristics of the present invention will become apparent upon reading the following description, given as an illustrative and non-limiting example, with reference to the accompanying drawings, which depict:

FIG. 1: flow chart of a preferred embodiment of the manufacturing process of the present invention. The step with the dotted line is optional.

Fig. 2A to 2E: a cross-sectional schematic of an assembly of parts made from a thermoplastic polymer composite.

Fig. 3A and 3B: two simplified illustrations in top view of a longitudinal section of two parts of a window profile assembled according to the method of the invention.

Fig. 4A and 4B: a schematic perspective view of the vehicle cross member of the present invention.

FIG. 5: a schematic perspective view of the aircraft fuselage section of the invention.

[ detailed description of the invention]

In the remainder of the description, a "weld interface" corresponds to a weld joint between components, or a portion of components. It is meant to be a molten zone, that is to say a zone in which the thermoplastic polymer becomes liquid during the welding operation. The welding of the present invention may be carried out with or without the provision of a thermoplastic filler material, in particular a (meth) acrylic thermoplastic filler material.

For the purposes of the present invention, the term "resistance wire" is intended to encompass a resistivity greater than 1X 10 at 20 ℃ C^-2Omega mm/m, for example filaments of material larger than 0.1 omega mm/m at 20 ℃. The resistance wire may for example comprise a metal or metal alloy or any other organic conductive element based on carbon, such as carbon black, carbon nanotubes, stoneConductive polymer films or wires of graphene. Preferably, the resistance wire has a high melting point, greater than the softening point or pour point (e.g. glass transition temperature) of the (meth) acrylic thermoplastic polymer of the present invention. The melting point of the resistance wire is preferably greater than 300 deg.C, more preferably greater than 500 deg.C, for example greater than 750 deg.C. In the case of a conductive polymer film or wire, it must have a pour point at least equal to that of the thermoplastic polymer, preferably a (meth) acrylic thermoplastic polymer.

For the purposes of the present invention, the expression "polymer composite" denotes a multicomponent material comprising at least two immiscible components, at least one of which is a polymer, the other component possibly being, for example, a fibrous reinforcing material.

For purposes of the present invention, "fibrous reinforcement" or "fibrous substrate" refers to a plurality of fibers, unidirectional rovings or continuous filament mats, fabrics, felts or non-woven fabrics, which may be in the form of tapes, webs, ribbons, strands or parts.

By "matrix" is meant a material that acts as a binder, which is capable of transferring forces to the fibrous reinforcement material. The "polymer matrix" comprises a polymer, but may also comprise other compounds or materials. Thus, the "(meth) acrylic polymer matrix" refers to any type of compound, polymer, oligomer, copolymer, or block copolymer of acrylic and methacrylic. However, it would not depart from the scope of the invention if the (meth) acrylic polymer matrix comprises up to 10% by weight, preferably less than 5% by weight, of other non-acrylic monomers selected, for example, from: butadiene, isoprene, styrene, substituted styrenes such as alpha-methylstyrene or tert-butylstyrene, cyclosiloxanes, vinylnaphthalene and vinylpyridine.

"Polymer" refers to a copolymer or a homopolymer. "copolymer" refers to a polymer of several different monomer units combined together, and "homopolymer" refers to a polymer of the same monomer units combined together. "Block copolymer" refers to a polymer comprising one or more uninterrupted sequences of each individual polymer entity, which polymer sequences are chemically different from each other and are bonded to each other by covalent bonds. These polymer sequences are also referred to as polymer blocks.

For the purposes of the present invention, the term "free radical initiator" refers to a compound which can initiate the polymerization of one or more monomers.

For the purposes of the present invention, the term "polymerization" refers to the process by which a monomer or a mixture of monomers is converted into a polymer.

For the purposes of the present invention, the term "monomer" refers to a molecule which can be polymerized.

For the purposes of the present invention, a "thermoplastic polymer" is a polymer which is generally solid at room temperature, crystalline, semi-crystalline or amorphous, which softens during the course of increasing the temperature, in particular after reaching its glass transition temperature (Tg), flows at higher temperatures and can exhibit a marked melting at the point of reaching its "melting point" (Tm) (when it is semi-crystalline) and become solid again during the course of decreasing the temperature below its melting point and below its glass transition temperature. This also applies to thermoplastic polymers that are slightly crosslinked by the presence of polyfunctional monomers or oligomers in the formulation of a (meth) acrylate "syrup" in a percentage by weight of preferably less than 10%, preferably less than 5% and more preferably less than 2%, which can be thermoformed when heated above the softening point.

For the purposes of the present invention, "thermosetting polymer" means a plastic material which is irreversibly converted into an insoluble polymer network by polymerization.

"(meth) acrylic monomer" refers to any type of acrylic and methacrylic monomer.

"(meth) acrylic polymer" means a polymer substantially comprising (meth) acrylic monomers that constitute at least 50% by weight or more of the (meth) acrylic polymer.

For the purposes of the present invention, the term "PMMA" denotes homopolymers and copolymers of Methyl Methacrylate (MMA), the weight ratio of MMA in PMMA preferably being at least 70% by weight for the MMA copolymer.

Like reference numerals are used to refer to like elements throughout the remainder of the specification.

According to a first aspect, as shown in fig. 1, the present invention relates to a method 100 of manufacturing an object 1 made of a thermoplastic polymer composite from at least two parts made of a thermoplastic polymer composite comprising a fibrous reinforcement and a thermoplastic polymer matrix. Preferably, the process is carried out starting from at least two parts made of a (meth) acrylic thermoplastic polymer composite comprising a fibrous reinforcement and a (meth) acrylic thermoplastic polymer matrix.

The method mainly comprises the following steps:

-arranging 120 two parts 10 made of thermoplastic polymer composite adjacently or overlappingly at an assembly interface region 11,

-heating 130 at said assembly interface zone 11 to melt the thermoplastic polymer matrix so as to form an object 1 made of thermoplastic polymer composite comprising a welding interface 12.

The (meth) acrylic thermoplastic polymer constituting part of the matrix associated with the fibrous reinforcement may be chosen from acrylic polymers and copolymers, such as polyacrylates. They are more particularly chosen from polymethyl methacrylate (PMMA) or derivatives thereof or copolymers of Methyl Methacrylate (MMA), or mixtures thereof.

Preferably, the (meth) acrylic thermoplastic polymer constituting the (meth) acrylic thermoplastic polymer matrix has a glass transition temperature (Tg) of 50 ℃ to 160 ℃, preferably 70 ℃ to 140 ℃ and even more preferably 90 ℃ to 120 ℃, which is advantageous compared to other thermoplastic polymers such as polyamines. In fact, polyamines generally have very high melting points, i.e., 200 ℃ to higher, which is not as advantageous for field assembly as the process of the present invention. The glass transition temperature or melting point can be measured by methods known to those skilled in the art. Preferably, these temperatures are measured by differential scanning calorimetry according to the conditions specified in standard ISO 11357-2/2013 for Tg and standard ISO 11357-3/2011 for Tm. Furthermore, the (meth) acrylic thermoplastic polymer or a part of the (meth) acrylic thermoplastic polymer has a Melt Flow Index (MFI) according to ISO 1133 (230 ℃/3.8 kg) of less than 20 g/10 min. Preferably, the melt flow index is less than 18 g/10 min, more preferably less than 16 g/10 min, advantageously from 0.1 g to 13 g/10 min.

As will be described in detail below, the (meth) acrylic thermoplastic polymer matrix may be obtained from the polymerization of a liquid (meth) acrylic composition comprising a (meth) acrylic monomer or a mixture of (meth) acrylic monomers, a (meth) acrylic polymer, and at least one free radical initiator.

The (meth) acrylic thermoplastic polymer matrix is composed of a (meth) acrylic thermoplastic polymer, but may further comprise one or more additives and/or one or more fillers.

The carbonaceous filler may in particular be activated carbon, natural anthracite, synthetic anthracite, carbon black, natural graphite, synthetic graphite, carbonaceous nanofillers or mixtures thereof. They are preferably selected from carbonaceous nanofillers, in particular graphene and/or carbon nanotubes and/or carbon nanofibrils or mixtures thereof. These fillers are capable of conducting electricity and heat and thus of improving the lubrication of the polymer matrix when heated. They can then shorten cycle times or facilitate assembly, adjustment or maintenance at the installation site.

The mineral filler comprises in particular a metal hydroxide, more particularly alumina trihydrate (Al (OH)₃) Or in the form of magnesium hydroxide (mg (oh)), and mineral nanofillers such as calcium carbonate, titanium dioxide or silica.

As additives, organic additives such as impact strength modifiers or block copolymers, heat stabilizers, UV stabilizers, lubricants, viscosity modifiers, pH adjusters (sodium hydroxide), particle size adjusters (sodium sulfate), biocides and mixtures thereof may be mentioned. These additives are capable of improving, in particular, the rheological, chemical and adhesion properties of the (meth) acrylic thermoplastic polymer matrix.

The weight percentage of all additives and fillers with respect to the total weight of the (meth) acrylic thermoplastic polymer matrix is preferably less than 30%, preferably less than 10%.

Fibrous reinforcement generally refers to a plurality of fibers, unidirectional rovings or continuous filament mats, fabrics, felts or non-woven fabrics, which may be in the form of strips, webs, braids, strands or parts. More particularly, the fibrous reinforcement comprises one or more fibers, typically an assembly of several fibers, which can have different forms and dimensions; one, two or three dimensional. The one-dimensional form corresponds to linear long fibers. The fibers may be discontinuous or continuous. The fibers may be arranged randomly or parallel to each other in the form of continuous filaments. The two-dimensional form corresponds to a non-woven reinforcement or fiber mat or woven roving or fiber bundle, which may also be braided. Even if the two-dimensional form has a certain thickness and is therefore three-dimensional in principle, it is considered two-dimensional according to the invention. Three-dimensional form for example corresponding to a stacked or folded non-woven fibrous reinforcement or a fibrous mat or a woven roving or a bundle of fibers, or a mixture thereof; an assembly of two-dimensional forms in three dimensions.

The fibers may be discontinuous or continuous. When the fibers are continuous, the assembly thereof forms a fabric. Preferably, the fibrous reinforcement is based on continuous fibers. 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 obtained from continuous 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 advantageously at least 10000. The continuous fibers have an aspect ratio of at least 1000. The size of the fibers can be measured by methods known to those skilled in the art. Preferably, these dimensions are measured by microscopy according to standard ISO 137.

The source of the fibers making up the fibrous reinforcement may be natural or synthetic. Natural materials which may be mentioned include vegetable fibres, wood fibres, animal fibres or mineral fibres. Plant fibers are, for example, sisal, jute, hemp, flax, cotton, coconut and banana fibers. Animal fibres are for example wool or fur. The mineral fibres may also be chosen from glass fibres (in particular of the E, R or S2 type), basalt fibres, carbon fibres, boron fibres or silica fibres.

Synthetic materials which may be mentioned include polymer fibers selected from thermosetting polymer fibers, thermoplastic polymers or mixtures thereof. The polymer fibers may be comprised of polyamides (aliphatic or aromatic), polyesters, polyvinyl alcohol, polyolefins, polyurethanes, polyvinyl chloride, polyethylene, unsaturated polyesters, epoxies, and vinyl esters.

Preferably, the fibrous reinforcement of the present invention comprises plant fibers, wood fibers, animal fibers, mineral fibers, synthetic polymer fibers, glass fibers, basalt fibers and carbon fibers, alone or in a mixture. More preferably, the fibrous reinforcement of the present invention comprises carbon fibers or glass fibers. More preferably, the fibrous reinforcement of the present invention consists essentially of natural fibers (textile fibers or wood fibers), carbon fibers or glass fibers.

The fibers of the fibrous reinforcement material have a diameter of, for example, 0.005 to 100 μm, preferably 1 to 50 μm, more preferably 5 to 30 μm and advantageously 10 to 25 μm.

Preferably, the fibers of the fibrous reinforcement of the invention are selected from continuous fibers for the one-dimensional form of the fibrous reinforcement or from long fibers or continuous fibers for the two-dimensional or three-dimensional form of the fibrous reinforcement.

As shown in fig. 1, a first optional step of manufacturing 110 at least two parts 10 made of a (meth) acrylic thermoplastic polymer composite may comprise the following sub-steps:

-impregnating 111 a fibrous reinforcement with a liquid (meth) acrylic composition,

-polymerizing 112 the liquid (meth) acrylic composition impregnating the fibrous reinforcement.

One of the advantages of the present invention is that the part 10 made of thermoplastic polymer composite can be manufactured at a temperature of less than 150 ℃, preferably less than 140 ℃, even more preferably less than 125 ℃, advantageously less than 120 ℃, more advantageously less than 110 ℃ and even more advantageously less than 100 ℃. For example, the step of impregnating the fibrous reinforcement with the liquid (meth) acrylic composition is carried out at a temperature of less than 150 ℃, preferably less than 120 ℃, even more preferably less than 100 ℃ or less than 80 ℃. In fact, the liquid (meth) acrylic composition used to make the part 10 made of the thermoplastic polymer composite is liquid at temperatures well below the conventional melting point of conventional thermoplastics. This thus enables the production of very large-sized parts 10 made of thermoplastic polymer composite materials without having to carry out a process of heating the parts to high temperatures. Thus, it should be understood that the processes that can be used to manufacture these parts do not require the step of heating at elevated temperatures as is the case with conventional thermoplastics.

Step 110 of manufacturing a part 10 made of a thermoplastic polymer composite may further comprise a substep 113 of depositing a layer of a (meth) acrylic thermoplastic polymer. Such deposition may be preferred at assembly interface areas intended to form future weld-type interfaces. Alternatively, the deposition is performed on the entire part 10 made of the thermoplastic polymer composite.

With respect to step 110 of manufacturing the parts 10 made of thermoplastic polymer composite, different methods may be employed to manufacture the parts. Vacuum Assisted Resin Infusion (VARI), pultrusion, vacuum infusion molding, pressurized infusion molding, autoclave molding, Resin Transfer Molding (RTM) and variants thereof (e.g. HP-RTM, C-RTM, I-RTM), Reaction Injection Molding (RIM), enhanced reaction injection molding (R-RIM) and variants thereof, punch molding, compression molding, Liquid Compression Molding (LCM) or Sheet Molding (SMC) or Bulk Molding (BMC) may be mentioned.

A first preferred manufacturing method for manufacturing a part 10 made of a thermoplastic polymer composite is a method of transferring a liquid (meth) acrylic composition onto the fibre-reinforcement by impregnating the fibre-reinforcement in a mould. Methods requiring a mold are listed above and include the word molding.

A second preferred method of manufacturing a part 10 made of a thermoplastic polymer composite is a method of using the liquid composition in a pultrusion process. The fiber is guided through a resin bath containing the composition of the invention (the original batch is suspected of being a mistake of the batch). The fibers in the form of a fibrous reinforcement are for example in the form of unidirectional rovings or continuous filament mats. After immersion in the resin bath, the wet fibers are drawn through a heated die where polymerization occurs.

A third preferred manufacturing method is Vacuum Assisted Resin Infusion (VARI).

The method of manufacturing a part 10 made of a thermoplastic polymer composite material and a mechanical or structural part or product may further comprise a post-forming step. Post-forming includes bending and modifying the shape of the composite part. The method of manufacturing a part 10 made of a thermoplastic polymer composite may further comprise a rolling step.

The thermoplastic parts obtained by the process of the invention may be post-formed after polymerization of the liquid composition of the invention. Forming includes bending and modifying the shape of the composite part.

As for the liquid (meth) acrylic composition, it may contain a (meth) acrylic monomer, a precursor (meth) acrylic polymer, and a radical initiator as described in WO 2013/056845 and WO 2014/013028.

Furthermore, during the impregnation process, the viscosity of the liquid (meth) acrylic composition or the impregnation slurry must be adjusted and adjusted so as not to be too fluid or too viscous in order to correctly impregnate each fiber of the fibrous reinforcement material when preparing the polymer composite. When partially wetted due to too high fluidity or too high viscosity of the slurry, "bare" areas (i.e., unimpregnated areas) and areas where polymer droplets are formed on the fibers, respectively, occur, which is the cause of bubble formation. These "bare" areas and these air bubbles lead to defects in the final composite material, which are responsible, among other things, for the reduction of the mechanical strength of the final composite material. Further, in the case of use without impregnation, it is desirable to have a liquid composition that polymerizes rapidly with good conversion in order to increase productivity.

Thus, the dynamic viscosity of the liquid (meth) acrylic composition at 25 ℃ is preferably from 10 to 10000 mPa s. The liquid composition or the (meth) acrylic syrup has a dynamic viscosity of from 10 to 10000 mPas, preferably from 20 to 7000 mPas and advantageously from 20 to 5000 mPas. The viscosity of the liquid (meth) acrylic composition or the liquid (meth) acrylic syrup can be easily measured with a rheometer or a viscometer. The dynamic viscosity was measured at 25 ℃. If the liquid (meth) acrylic syrup exhibits Newtonian behavior, i.e., no shear thinning occurs, the dynamic viscosity is independent of the shear in the rheometer or the velocity of the viscometer's center shaft. If the liquid composition exhibits non-Newtonian behaviour, i.e. shear thinning occurs, the dynamic viscosity is 1 s at 25 DEG C^-1Shear rate measurement of (2).

The liquid (meth) acrylic composition comprises at least one (meth) acrylic monomer or a mixture of (meth) acrylic monomers, a precursor (meth) acrylic polymer.

The (meth) acrylic monomer or mixture of (meth) acrylic monomers in the liquid (meth) acrylic composition or the liquid (meth) acrylic syrup is present in an amount of at least 40 wt%, preferably at least 45 wt%, more preferably at least 50 wt%, advantageously at least 60 wt% and more advantageously at least 65 wt% in the liquid (meth) acrylic composition.

The precursor (meth) acrylic polymer in the liquid (meth) acrylic composition or the liquid (meth) acrylic syrup is present in an amount of at least 10 wt%, preferably at least 15 wt%, advantageously at least 18 wt% and more advantageously at least 20 wt% in the liquid (meth) acrylic composition.

The precursor (meth) acrylic polymer in the liquid (meth) acrylic composition or the liquid (meth) acrylic syrup is present in an amount of at most 60 wt%, preferably at most 50 wt%, advantageously at most 40 wt% and more advantageously at most 35 wt% in the liquid (meth) acrylic composition.

The liquid (meth) acrylic composition or the slurry, the slurry compound being mixed in the following weight percentages:

the (meth) acrylic monomer in the liquid composition or the (meth) acrylic syrup is present in a proportion of 40 to 90% by weight and preferably 45 to 85% by weight of the composition composed of the (meth) acrylic monomer and the (meth) acrylic polymer,

the (meth) acrylic polymer in the liquid composition or the (meth) acrylic syrup is present in a proportion of 10% to 60% by weight and advantageously 15% to 55% by weight of the composition consisting of (meth) acrylic monomer and (meth) acrylic polymer; preferably, the (meth) acrylic polymer in the liquid composition is present in a proportion of 18 to 30 wt%, more preferably 20 to 25 wt% of the composition consisting of the (meth) acrylic monomer and the (meth) acrylic polymer.

As the (meth) acrylic monomer, the monomer is selected from the group consisting of acrylic acid, methacrylic acid, alkyl acrylic monomers, alkyl methacrylic monomers, hydroxyalkyl acrylic monomers, and hydroxyalkyl methacrylic monomers, and mixtures thereof.

Preferably, the (meth) acrylic monomer 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 contains 1 to 12 straight, branched or cyclic carbons.

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.

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.

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 is a mixture of methyl methacrylate, optionally with at least one other monomer.

As the precursor (meth) acrylic polymer, mention may be made of polyalkyl methacrylate or polyalkyl acrylate. According to a preferred embodiment, the precursor (meth) acrylic polymer is poly (methyl methacrylate) (PMMA).

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.

According to another embodiment, the 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 different average molecular weights, or a mixture of at least two copolymers of MMA having different monomer compositions.

Copolymers of Methyl Methacrylate (MMA) comprise 70 to 99.7 wt.% methyl methacrylate and 0.3 to 30 wt.% of at least one monomer containing at least one ethylenic unsaturation copolymerizable with the methyl methacrylate.

These monomers are well known and mention may in particular be made of acrylic and methacrylic acid and alkyl (meth) acrylates in which the alkyl group contains from 1 to 12 carbon atoms. Mention may be made, for example, of methyl acrylate and ethyl, butyl or 2-ethylhexyl (meth) acrylate. Preferably, the comonomer is an alkyl acrylate, wherein the alkyl group contains 1 to 4 carbon atoms.

According to a first preferred embodiment, the copolymer of Methyl Methacrylate (MMA) comprises from 80% to 99.7% by weight, advantageously from 90% to 99.7% by weight and more advantageously from 90% to 99.5% by weight of methyl methacrylate and from 0.3% to 20% by weight, advantageously from 0.3% to 10% by weight and more advantageously from 0.5% to 10% by weight of at least one monomer containing at least one ethylenic unsaturation copolymerizable with the methyl methacrylate. Preferably, the comonomer is selected from methyl acrylate and ethyl acrylate and mixtures thereof.

The weight average molecular weight of the precursor (meth) acrylic polymer should be relatively high, meaning more than 50000 g/mol, preferably more than 100000 g/mol. The weight average molecular weight can be determined by size exclusion chromatography.

The precursor (meth) acrylic polymer is completely soluble in the (meth) acrylic monomer or in a mixture of (meth) acrylic monomers. This can increase the viscosity of the (meth) acrylic monomer or the mixture of (meth) acrylic monomers. The resulting liquid composition or solution is commonly referred to as a "slurry" or "prepolymer". The liquid (meth) acrylic syrup has a dynamic viscosity value of 10 to 10000 mPa.s. The viscosity of the slurry can be easily measured with a rheometer or viscometer. The dynamic viscosity was measured at 25 ℃. Advantageously, the liquid (meth) acrylic syrup is free of intentionally added additional solvent.

As the radical initiator, there may be mentioned preferably a water-soluble radical polymerization initiator or a fat-soluble or partially fat-soluble radical polymerization initiator.

Water-soluble free-radical polymerization initiators, in particular sodium, potassium or ammonium peroxodisulfate, are used alone or in the presence of reducing agents such as sodium metabisulfite or sodium dithionite, sodium thiosulfate, sodium formaldehyde sulfoxylate, 2-hydroxy-2-sulfinatoacetic acid, mixtures of sodium sulfite and the disodium salt of 2-hydroxy-2-sulfoacetic acid, or mixtures of the disodium salt of hydroxysulfinatoacetic acid and the disodium salt of hydroxysulfoacetic acid.

Fat-soluble or partially fat-soluble free-radical polymerization initiators are, in particular, peroxides or hydroperoxides and derivatives of azobisisobutyronitrile. Peroxides or hydroperoxides are used in combination with the reducing agents described above to lower their activation temperature.

The weight percentage of the initiator relative to the total weight of the monomer mixture is preferably from 0.05 to 3% by weight, preferably from 0.1 to 2% by weight.

In fig. 2, the step of arranging 120 two parts 10 made of thermoplastic polymer composite material adjacently or overlappingly at an assembly interface region 11 is shown. Thus, fig. 2A shows two parts 10 made of thermoplastic polymer composite material positioned adjacent to each other and separated by an assembly interface region 11. The ends of the components made of thermoplastic polymer composite are positioned adjacent to form an assembly interface region 11. As shown in fig. 2B, the end may be formed from a cross-section of the part 10 made from the thermoplastic polymer composite, thereby forming a transverse weld interface 12.

As shown in fig. 2C to 2E, the parts 10 made of thermoplastic polymer composite material may also be positioned so as to overlap and thus form a footprint corresponding to the future weld interface 12 shown in these figures.

Furthermore, the component 10 made of a thermoplastic polymer composite may comprise a layer 13 of a (meth) acrylic thermoplastic polymer. As previously mentioned, the layer 13 may preferably be positioned at an assembly interface area intended to form a future welding interface 12 (fig. 2D). Alternatively, as shown in fig. 2E, a layer 13 is deposited over the entire part 10 made of the thermoplastic polymer composite. The deposition makes it possible in particular to obtain a layer 13 of (meth) acrylic thermoplastic polymer at least 0.5 mm thick on the surface intended to be welded.

In particular, the welding or weldability interface 12 has a thickness greater than or equal to 1 mm, preferably greater than or equal to 2 mm. The thickness of the weld interface 12 may be measured by conventional methods, for example, from a vertical cross-section of the weld interface 12.

Fig. 2A to 2E depict only cross-sectional views of the welding interface 12, but the latter preferably extends over a larger length of the component 10 made of the thermoplastic polymer composite. Thus, the welding interface 12 may have a length of more than 1 meter, preferably more than 5 meters and even more preferably more than 10 meters. Furthermore, the method of the present invention is particularly suited for large components 10 made of thermoplastic polymer composites. Thus, preferably, at least one of the two parts 10 made of thermoplastic polymer composite comprises a dimension greater than 1 meter, preferably greater than 2 meters.

The heating step 130 is able to melt the (meth) acrylic thermoplastic polymer matrix at said assembly interface region 11, thereby forming an object 1 made of thermoplastic polymer composite comprising a welding interface 12. The (meth) acrylic thermoplastic polymer matrix may be melted by a technique selected from the group consisting of: ultrasonic welding, induction welding, resistance wire welding, friction stir welding, laser welding, heating by infrared or ultraviolet radiation. Preferably, the (meth) acrylic thermoplastic polymer matrix is melted by resistance wire welding.

The welding of the present invention may be performed with or without the provision of a (meth) acrylic thermoplastic filler material. In fact, during the heating, the (meth) acrylic thermoplastic polymer material may be provided, for example, in the form of a rod made of (meth) acrylic thermoplastic polymer. This is advantageous when a hollow or empty space is formed during the step 120 of providing two parts made of thermoplastic polymer composite material. Supplying the thermoplastic filler material via a rod made of a (meth) acrylic thermoplastic polymer enables filling any hollow or space.

Preferably, the temperature at the assembly interface 11 during the heating step 230 is 160 to 300 ℃. This temperature can be measured conventionally by an infrared thermometer.

Fig. 3A and 3B show two simplified illustrations in top view of longitudinal sections of two parts 20 of a window profile assembled according to the method of the invention. In fig. 3A, two parts 20 of a window profile made of a thermoplastic polymer composite are separated by a hot plate 24. When the melting point is reached, the hot plate 24 is removed and the two parts 20 of the window profile of thermoplastic polymer composite are brought into contact with each other (see fig. 3B), thereby forming the window profile 2 of thermoplastic polymer composite comprising the welding interface 22.

An optional step 140 of applying pressure includes creating pressure at the assembly interface 11. This pressure generated after the heating step 130 is capable of strengthening the welding interface between the at least two parts 10 made of polymer composite material, thereby forming an object made of thermoplastic polymer composite material comprising a welding interface 12. The two parts 10 made of thermoplastic polymer composite material may also be firmly joined together in a desired position or form and held until the thermoplastic polymer matrix cools, thereby forming a strong weld interface 12. This pressure may be generated, for example, by applying a partial vacuum at the area of assembling 11 at least two parts 10 made of thermoplastic polymer composite. The pressure may also be generated by applying a force substantially perpendicular to the assembly interface region 11, for example by depositing a template on the at least two parts made of thermoplastic polymer composite.

The optional cooling step 150 can improve the mechanical properties of the weld interface 12. This cooling step 150 may be performed at room temperature (e.g., 15 ℃ to 25 ℃), or at a temperature below the Tg of the (meth) acrylic thermoplastic polymer.

According to a second aspect, the invention relates to an object made of thermoplastic polymer composite material made of at least two parts 10 made of thermoplastic polymer composite material. As mentioned above, the thermoplastic polymer composite comprises a fibrous reinforcement and a (meth) acrylic thermoplastic polymer matrix, and the at least two parts 10 made of thermoplastic polymer composite are connected by a weld interface 12. Objects made of the thermoplastic polymer composite of the present invention can be used in many fields, preferably in the construction, aerospace, marine, automotive and leisure fields. The object made of a thermoplastic polymer composite according to the invention can thus preferably be selected from the group consisting of coverings consisting of a plurality of plates, rails, window profiles, aircraft fuselages, reinforcements of buildings, cross members (in particular for vehicles), body-in-white parts for vehicles, nacelles, empennages, ribs, spoilers, flaps, turbine blades for ships, hulls, bridges, bulkheads for ships and trim panels (covers) for automobiles.

In the remainder of the description, three other examples of objects are given.

Fig. 4A and 4B depict objects 3, 4 made of the thermoplastic polymer composite of the present invention. Fig. 4A depicts a bumper-reinforced beam 3 for an automobile, made of a thermoplastic polymer composite of the present invention, including a weld interface 32. These parts 30, made of thermoplastic polymer composite material, constitute structural elements for vehicles and are joined by a plurality of welding interfaces 32. The invention is not limited to these particular components 30 and may be practiced in the manufacture of other components that make up, for example, a vehicle body such as a vehicle body, floor, fender, door, cross member 40 as shown in FIG. 4B that connects the rear wheels.

Fig. 5 depicts an aircraft fuselage portion 5 comprising a plurality of fuselage parts 50 made of a thermoplastic polymer composite, some of which comprise a layer 53 of a (meth) acrylic thermoplastic polymer.

Furthermore, it is preferred that the object 1, 2, 3, 4, 5 made of a thermoplastic polymer composite according to the invention does not comprise more than 50 wt. -%, more preferably not more than 40 wt. -%, more preferably not more than 30 wt. -%, advantageously not more than 20 wt. -%, more advantageously not more than 15 wt. -% and even more advantageously not more than 10 wt. -% of a thermosetting polymer, such as an epoxy or polyester or polyurethane resin. However, thermosetting polymers have hitherto generally been used for the manufacture of objects 1 made of polymer composites. Likewise, the object 1 made of thermoplastic polymer composite material of the present invention preferably does not comprise more than 10 wt. -%, more preferably not more than 9 wt. -% and even more preferably not more than 8 wt. -%, advantageously not more than 7 wt. -%, more advantageously not more than 6 wt. -% and even more advantageously not more than 5 wt. -% of a binder, preferably a thermosetting binder. In practice, adhesive bonding of different object parts made of polymer composite materials is usually carried out with thermosetting structural adhesives of the epoxy type.

Preferably, the thermoplastic polymer composite of the component 10, 20, 30, 40, 50 of the invention is at least partially covered with a layer of (meth) acrylic thermoplastic polymer at least 0.5 mm, preferably at least 1 mm, more preferably at least 2 mm thick, for example on the surface intended to be welded. The polymer composite is more particularly covered with a layer of (meth) acrylic thermoplastic polymer at the assembly interface area intended to form the future welding interface 12. This makes it possible in particular to avoid regions with a lower concentration of thermoplastic polymer. Alternatively, the component 10, 20, 30, 40, 50 made of a thermoplastic polymer composite may have at least one face covered with a layer of (meth) acrylic thermoplastic polymer.

Particularly advantageously, the object 1, 2, 3, 4, 5 made of polymer composite material according to the invention comprises a welding interface 12, 22, 32, 42 having a length greater than 1 meter, preferably greater than 5 meters.

In the context of the present invention, the use of a part 10 made of a thermoplastic polymer composite comprising a fibrous reinforcement and a (meth) acrylic thermoplastic polymer matrix enables a significant reduction in the amount of thermosetting polymer used in objects 1, 2, 3, 4, 5 made of polymer composite and opens up possibilities that cannot be envisaged with thermosetting materials, such as recycling of objects 1, 2, 3, 4, 5 made of most thermoplastic polymer composites and easier assembly or maintenance.