Thermoplastic composite profile, frame and manufacturing process for said profile

Abstract

A composite profile comprises a body (70) having unidirectional fiber strands forming a first reinforcing material, the first reinforcing material being coated with a first thermoplastic matrix, the body (70) being at least partially covered by an outer layer (71). The outer layer (71) comprises a second reinforcing material formed of short, randomly oriented fibers, the second reinforcing material being coated with a second matrix of a second thermoplastic material. Frame made of such profiles. Pultrusion process for producing such profiles. Figure for the abstract: Fig. 1

Description

[0001] Title of the invention: Thermoplastic composite profile, frame and method for manufacturing said profile. Technical field

[0002] The invention relates to a thermoplastic matrix composite profile of the type comprising a reinforcing material embedded in a thermoplastic synthetic matrix and a reactive thermoplastic pultrusion process for manufacturing said profile. It also relates to a frame obtained by assembling several profile sections produced by the process. Previous technique

[0003] In the field of manufacturing photovoltaic or thermal solar panels, it is common practice to create a frame surrounding a glass plate which serves as a support for the cells or as a pane of glass to obtain a greenhouse effect.

[0004] For the manufacture of frames, a common technique is the use of profiles comprising a tubular section surmounted by a groove. The groove is designed to receive the glass plate, which then rests on the tubular section and is held in the groove.

[0005] Document EP 4 258 542 A1 shows an example of such a profile produced by a thermosetting matrix pultrusion process. The profiles are mitered to form a frame with brackets inserted into the tubular sections. The profile incorporates thin sheets of textile on its surface for reinforcement and to facilitate the attachment of the brackets. These sheets are fed into the pultrusion tooling along with longitudinal fiber strands. Examples of such sheets are known as "Unifilo" by Owens Corning. Joining sheets when a roll is exhausted creates a discontinuity in the profile that may need to be eliminated, generating significant stresses during production. Furthermore, since the sheets are supplied in predetermined widths, they must be slit, which always leaves some waste.

[0006] The assembly of the brackets and profiles uses nails, which induces mechanical stresses within the profiles and tends to weaken them. Furthermore, such profiles are made of thermosetting resin, resulting in low recyclability of panels made with these profiles.

[0007] Pultrusion has already been proposed using thermoplastic synthetic material. Liquid precursors are mixed to form a reactive liquid mixture which is introduced into a tool containing continuously moving fibers. The temperature inside the tool is controlled to induce a polymerization reaction of the reactive mixture, generating the thermoplastic matrix. Although recyclability is improved, the issue of fragility in the transverse direction is not resolved. Description of the invention

[0008] It is therefore an objective of the invention to provide a composite profile that is recyclable and has improved transverse strength. Another objective is to provide a frame using such a profile and a method for manufacturing the profile.

[0009] With these objectives in view, the invention relates to a composite profile comprising a body having strands of unidirectional fibers forming a first reinforcing material, the first reinforcing material being coated with a first matrix in a first thermoplastic material, the body being at least partially covered with an external layer, characterized in that the external layer comprises a second reinforcing material formed of short fibers of random orientation, the second reinforcing material being coated with a second matrix in a second thermoplastic material.

[0010] The body is thus manufactured using a conventional reactive thermoplastic pultrusion method, and an outer layer is added to it, which provides significant transverse strength because a substantial portion of the short fibers of the second reinforcing material are oriented in directions other than the longitudinal direction of the profile. The advantage of using a reactive thermoplastic pultrusion process is that it allows for the use of a body with a very high density of reinforcing material, resulting in a profile with very desirable mechanical properties. The outer layer is easily applied by a co-extrusion process over the already formed body.For the fibers of the first and second reinforcing materials, all types of fibers commonly used as composite reinforcement can be used, such as glass, carbon, aramid, or natural fibers like hemp or flax. There is no longer a need to feed the process with sheets to be cut and spliced; the process is continuous and does not require managing discontinuities.

[0011] According to an advantageous feature, the second reinforcing material represents at least 20% of the outer layer by volume. Such a proportion is significant and adds substantial strength compared to the second pure thermoplastic material. The proportion could be greater than 30%, or even greater than 40%, to increase the mechanical properties.

[0012] According to one embodiment, the body comprises at least one chamber such that the body is hollow. This allows for the creation of a hollow profile with very good mechanical characteristics for a limited mass, or which can also serve as a conduit.

[0013] According to an advantageous feature of the hollow profile, the chamber being delimited by tube walls, the thickness of the outer layer is between 10% and 60% of the total thickness of the tube walls. The layer represents a significant portion of the walls so as to be decisive in the mechanical characteristics of the wall.

[0014] According to an advantageous feature, the thickness of the outer layer is between 0.2 mm and 2 mm. Even if these limits can be exceeded, it is within this thickness range that the best overall characteristics of the profile are obtained.

[0015] According to an improvement, the outer layer includes an ultraviolet protection additive. Only the surface portion exposed to the outside receives the additive, thus avoiding the need to add the additive to the body mass, which is sufficiently protected by the outer layer.

[0016] According to one embodiment, the profile comprises a substantially flat bearing face, a first flange extending to the edge of said bearing face in a direction substantially perpendicular to the bearing face, and comprising a return extending parallel and opposite the bearing face to define a groove. A groove is thus formed directly in the profile, capable of receiving and retaining a flat element. This arrangement is particularly advantageous when using the profile to manufacture a frame, as the bearing faces, aligned in the same plane, allow the flat element to be held in place.

[0017] According to an improvement, a second wing extends opposite the first wing in the same direction as the return and parallel to the bearing face. This second wing can be useful for fixing the object made with this profile or for the mechanical reinforcement of the profile.

[0018] Depending on the application, the profile is used to make a frame for a photovoltaic or thermal solar panel, a strip for thermal bridge, a battery support, a frame or a threshold for a window or door.

[0019] The invention also relates to a panel frame, characterized in that it is formed by assembling sections of pultruded profiles as described above with at least one chamber, with brackets inserted into the chamber of the profiles to connect the sections together. The shape of the frame can be rectangular or any polygonal shape.

[0020] According to one embodiment, each section is welded with the brackets inserted therein.

[0021] The invention also relates to a pultrusion process in which a body is formed by passing strands of unidirectional fibers forming a first A reinforcing material is used in a pultrusion mold. The first reinforcing material is impregnated with a reactive thermoplastic mixture. The body is hardened after pultrusion, and the hardened body is then coated with an outer layer by passing through a co-extrusion die. This process is characterized in that the co-extrusion die is fed with a second thermoplastic material mixed with short fibers to form the outer layer. The use of co-extrusion allows for the direct application of the outer layer in continuity with the pultrusion process, resulting in very good adhesion of the outer layer to the profile with very high productivity. Furthermore, the extrusion process allows for the incorporation of functional shapes more easily than the pultrusion process. Such shapes include, for example, grooves designed to accommodate seals in the case of window profiles.

[0022] According to one embodiment, offcuts from thermoplastic matrix profiles are recycled to form at least part of the second thermoplastic material. In any manufacturing process, it is practically inevitable to have offcuts, for example, when a profile bar is too short for a new section after the bar has been cut into sections. Such offcuts can be reused, for example, after being ground into granules and fed into an extruder that melts the thermoplastic material and mixes it with the reinforcing material already incorporated into the offcuts. This recycled material is optionally supplemented with virgin material.

[0023] According to one embodiment, the reactive mixture produces a thermoplastic material selected from a group comprising polyamide and polymethyl methacrylate. Existing reactive systems for pultrusion are mainly based on anionic polymerization mechanisms of monomers, such as polyamide 6 from ε-caprolactam, polyamide 12 from lauryllactam, or radical polymerizations, such as PMMA from methyl methacrylate.

[0024] According to an advantageous feature, the first thermoplastic material and the second thermoplastic material are chosen to achieve good adhesion of the outer layer to the body. Since the first and second materials may be of different natures, it is important to choose the material pair such that good adhesion is obtained between the outer layer and the body.

[0025] According to a first option, the second thermoplastic material is of the same nature as the first thermoplastic material or is a mixture with at least one material of the same nature as the first thermoplastic material. Good adhesion is thus practically guaranteed.

[0026] According to a second option, the first thermoplastic material is based on polyamide-6 and the second thermoplastic material is chosen from a group comprising polypropylene, polyethylene, and polyvinylidene fluoride, the second thermoplastic material being modified by the grafting of maleic acid. It has been demonstrated that modifying the second thermoplastic material into polypropylene modified by the addition of maleic anhydrous also provides good adhesion despite the different nature of the first and second thermoplastic materials. Brief description of the figures

[0027] The invention will be better understood and other features and advantages will become apparent upon reading the following description, the description referring to the accompanying drawings, among which:

[0028] - [Fig. 1] is a cross-sectional view of a profile according to a first embodiment of the invention; - [Fig.2] is a view of a frame made with profiles from [Fig.1]; - [Fig.3] is a cross-sectional view of a profile according to a second embodiment of the invention; - [Fig.4] is a schematic view of a production installation for a profile conforming to an embodiment of the invention. Detailed description

[0029] A composite profile 7 according to a first embodiment is shown in [Fig. 1]. The profile 7 comprises a body 70 entirely covered by an outer layer 71. The body 70 includes a tube 700 delimiting a chamber 72 and from which a first and a second flange 701, 702 protrude. The body 70 is made of unidirectional fiber strands forming a first reinforcing material, the first reinforcing material being coated with a first matrix of thermoplastic synthetic material. The outer layer 71 comprises a second reinforcing material formed of short fibers with random orientation, the second reinforcing material being coated with a matrix of a second thermoplastic material.

[0030] The profile 7 has a substantially flat bearing surface 73 on the tube 700. The first flange 701 extends to the limit of said bearing surface 73 in a direction substantially perpendicular to the bearing surface 73 and has a return 7010 extending parallel and opposite the bearing surface 73 to define a groove 74. A second flange 702 extends opposite the first flange 701 in the same direction as the return 7010 and parallel to the bearing surface 73. By way of example, the cross-section of the tube 700 is 30 x 15 mm, the first flange 701 is 10 mm high and the second flange 702 is 15 mm wide. The wall thickness of tube 700 is 1.2 mm, as is that of the flanges 701 and 702, excluding the outer layer 71. The outer layer 71, for example, is 1 mm thick throughout, representing 45% of the total thickness of the tube wall, but the thickness can be modulated according to the locations of the profile section 7. A profile can be obtained with a Young's modulus of more than 10 GPa and a flexural strength of more than 150 MPa.

[0031] Such a profile 7 is used to make a frame 9 for a photovoltaic or thermal solar panel as shown in [Fig. 2]. Such a frame 9 comprises four mitered sections 90 of the profile 7 joined in the form of a rectangle. At each corner, a bracket 91 with two arms 910 is used to join two profile sections 90 together. For this purpose, one of the arms 910 of the bracket is inserted into the chamber 72 of the tube 700 of the profile 7, preferably with a tight fit. In addition, each arm 910 is welded to the profile section 7 it receives, for example, by ultrasonic welding through the wall of the profile 7 in contact with the arm 910 of the bracket 91. In an alternative embodiment not shown, the bracket has straight stops against which the ends of the sections bear. The angle of the frame is then formed by the brackets which are thus at least partially visible.The advantage is that the sections are cut straight and there is no waste as in the case of a miter cut.

[0032] According to a second embodiment, as shown in [Fig. 3], the profile 7' has an H-shaped cross-section. Thus, the body 70' comprises a web 75 that connects two flanges 76 extending parallel to each other and perpendicular to the web 75. The flanges 76 and the web 75 are covered by the outer layer 71'. In this embodiment, the body 70' is solid. Such a profile 7' can be used as a structural element in any type of construction.

[0033] A pultrusion manufacturing installation for a profile 7 will now be described with reference to [Fig. 4]. The pultrusion installation comprises successively:

[0034] - a unwinding unit 1 for unwinding strands M of fibers forming the first reinforcing material, also called "rovings" in English, - a preheating unit 3 for the rovings M which allows the fibers from the unwinding unit 1 to be dried and brought to a temperature favorable for polymerization; - a straight pultrusion tool 4 consisting of an impregnation unit 41 for impregnating the rovings M with a reactive mixture and a polymerization unit 42 from which the body 70 of the profile emerges; - a mixing unit 5 to mix precursors and supply the reactive mixture in liquid form to the impregnation unit 41; - a co-extrusion unit 2 which deposits the outer layer 71 onto the body 70 of the profile; - a cooled calibration unit 6 which determines the final section of the profile 7; - and a pulling unit 8 to pull the profile 7 out of the calibration unit 6, drawing the drill bits M through the installation from their unwinding.

[0035] In the mixing unit 5, precursors are stored in liquid form in tanks A, B, C. The precursors are conveyed to the mixing unit 5 at a controlled flow rate and mixed to form the liquid reactive mixture. The reactive mixture is injected into the impregnation unit 41 to wet the wicks M throughout their cross-section and form an intermediate composite material 7a.

[0036] In the polymerization unit 42, the intermediate composite material 7a is mounted and maintained at temperature. The reactive mixture reacts under the effect of temperature and polymerizes at least partially to form the first thermoplastic material.

[0037] The body 70 exits the polymerization unit 42 and enters, sufficiently hardened, the co-extrusion die 20 forming part of the co-extrusion unit 2. The co-extrusion unit 2 includes an extruder 21 capable of preparing a mixture of the second thermoplastic material and short fibers forming the second reinforcing material and of delivering the mixture under pressure to the co-extrusion die 20. The co-extrusion die 20 then deposits the outer layer 71 around the body 70 of the profile.

[0038] The calibration unit 6 is a temperature-controlled block comprising a passage of constant cross-section. This passage imposes the cross-section on the profile 7, which becomes fixed under the effect of cooling.

[0039] The pulling unit 8 draws the profile 7 and the fibers through the installation by exerting tension. A cutting unit, not shown, cuts the profile 7 into bars, also not shown. After the profiles 7 have been cut, the bars are stored in a temperature-controlled chamber so that polymerization can continue.

[0040] The pulling unit 8 includes, for example, a pair of tracks which grip the profile 7 during pulling.

[0041] The extruder can be fed at least in part with scraps of thermoplastic matrix profiles 7 ground into granules to form the outer layer 71.

[0042] The invention is not limited to the embodiments described above by way of example only. The outer layer could be modulated in thickness depending on its location within the profile section. It could even be interrupted, so that parts of the body would remain exposed. The calibration unit 6 is optional, so that cooling would be natural.

Claims

Demands

1. Composite profile comprising a body (70) having strands of unidirectional fibers forming a first reinforcing material, the first reinforcing material being coated with a first matrix of thermoplastic material, the body (70) being at least partially covered with an outer layer (71), characterized in that the outer layer (71) comprises a second reinforcing material formed of short fibers of random orientation, the second reinforcing material being coated with a second matrix of a second thermoplastic material.

2. Profile according to claim 1, wherein the second reinforcing material represents at least 20% of the outer layer (71) by volume.

3. Profile according to any one of claims 1 or 2, wherein the body (70) comprises at least one chamber (72) such that the body (70) is hollow.

4. Profile according to claim 3, in which the chamber (72) is delimited by tube walls, the thickness of the outer layer (71) is between 10% and 60% of the total thickness of the tube walls.

5. Profiled according to any one of the preceding claims, wherein the thickness of the outer layer (71) is between 0.2 mm and 2 mm.

6. Profiled according to any one of the preceding claims, wherein the outer layer (71) comprises an anti-ultraviolet protective additive.

7. Profile according to any one of the preceding claims, characterized in that it comprises a substantially flat bearing face (73), a first wing (701) extending to the limit of said bearing face (73) in a direction substantially perpendicular to the bearing face (73) and comprising a return (730) extending parallel and opposite the bearing face (73) to delimit a groove (74).

8. Profile according to claim 7, wherein a second wing (702) extends opposite the first wing (701) in the same direction as the return (730) and parallel to the bearing face (73).

9. Profile according to any one of the preceding claims, characterized in that it is used to make a solar panel frame photovoltaic or thermal, a thermal bridge strip, a battery support, a window or door frame or threshold.

10. Panel frame, characterized in that it is formed by the assembly of sections (90) of pultruded profiles (7) according to any one of the preceding claims in combination with claim 3, with brackets (91) inserted into the chamber (72) of the profiles (7) to connect the sections (90) together.

11. Frame according to claim 10, in which each section (90) is welded with the brackets (91) inserted therein.

12. Pultrusion process in which a body (70) is formed by passing strands (M) of unidirectional fibers forming a first reinforcing material through a pultrusion tool (4), and impregnating the first reinforcing material with a reactive thermoplastic mixture, the body (70) being hardened after the pultrusion tool (4), the hardened body (70) being covered with an outer layer (71) by passing through a co-extrusion die (20), characterized in that the co-extrusion die (20) is fed with a second thermoplastic material mixed with short fibers to form the outer layer (71).

13. A method according to claim 12, in which offcuts of thermoplastic matrix profiles (7) are recycled to form at least in part the second thermoplastic material.

14. A process according to claim 12 or 13, wherein the reactive mixture produces a thermoplastic material selected from a group comprising polyamide and polymethyl methacrylate.

15. A method according to any one of claims 13 to 14, wherein the first thermoplastic material and the second thermoplastic material are chosen to obtain good adhesion of the outer layer (71) to the body (70).

16. A method according to claim 15, wherein the second thermoplastic material is of the same nature as the first thermoplastic material or is a mixture with at least one material of the same nature as the first thermoplastic material.

17. A method according to claim 15, wherein the first thermoplastic material is based on polyamide-6 and the second thermoplastic material is selected from a group comprising polypropylene, polyethylene, and polyvinylidene fluoride, the second thermoplastic material being modified by the grafting of maleic acid.

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