FR2848143A1 - Laminated component manufacturing procedure uses perforated wood-based panel applied over protective and resin-impregnated reinforcing layers - Google Patents

Abstract

The procedure consists of stages in which successive layers are applied against the surface (1) of a mould (2): first a protective layer (3) for the laminated component, followed by at least one reinforcing layer (4) with fibres in a resin compound, and at least one structural layer in the form of a panel (6) of wood or derivatives, pre-drilled with perforations (7) and pre-impregnated with resin, after which the layers are pressed against the wall of the mould by a vacuum. The protective layer (3) can be a paint, varnish or UV protective resin, and this layer and/or the resin-impregnated reinforcing layer can contain colloidal silica or micro-balls of glass or polymer. The first and second stages can be followed by drying, and a vacuum can be applied between the application of the reinforcing and timber-based layers, the perforations in the latter being between 0.5 and 3 mm in diameter and spaced at intervals of 1 - 8 cm. For greater buoyancy the timber-based panel can be replaced by a foam or honeycomb layer, e.g. of aluminium cardboard or polymer.

Description

The present invention relates to a method of manufacturing elements

laminates,

  the elements thus manufactured and the use of this process in various fields of construction, in particular for architecture, in particular naval.

  Conventionally, the manufacture of a building element based on wood 5 and in particular of a boat element (for example of the hull) firstly comprises fixing by nailing or gluing of plywood panel (s) to the frame (of the boat). The following steps consist of covering these panels with layers of plaster to plug the pores, hide any roughness, surface irregularities or any excess thicknesses. The application of each layer of plaster is followed by drying, then by dry sanding. Then one or more coats of primer are applied. And finally the whole must be painted by a professional for a perfect exterior appearance.

  However, the finishes are very long and tedious, in particular the repeated cycles of application of plaster / drying / sanding, and can represent from 70 to 80% of the working time of the total construction of a boat hull. In addition, the sanding operations induce significant harmful dust for personnel working at or near this construction.

  Furthermore, composite molding techniques have also been used. They involve the application, on a mold, of multiple successive layers 20 of fibers and of polymer (for example polyester).

  The techniques attempting to combine the above methods have failed so far, due to the difficulties associated with "hanging" the wooden panels with the other layers, and in particular due to the formation of bubbles between the layers. resin matrix reinforcement and panel surface.

  One of the aims of the present invention is therefore to propose a method for manufacturing a laminated element, for example for a wooden boat hull, which does not have the drawbacks described above, and which makes it possible to produce these elements quickly, without producing any sanding waste, with constant quality and good adhesion between the different layers of said laminated element.

  To this end, the method according to the present invention for manufacturing a laminated element comprises the following successive stages of application against the wall of a mold: a) at least one protective layer of said element, b) at least at least one reinforcing layer in a resin composition, c) at least one structural layer comprising at least one wooden panel 5 or one derived from wood, through which a network of perforations is previously produced then a plating step under vacuum of the layers a) to c) above against the internal wall of the mold, by means of a vacuum bag.

  All the layers of the laminated element are thus assembled in said mold, including the final protective layer or layers, usually called "finishing", which are first introduced here into the mold. After demoulding of the laminated element, no coating or final treatment is necessary, nor any finishing work: this element is immediately usable in the desired construction. Indeed, it also has the characteristic of being self-structuring, that is to say that it does not need to be associated or joined to additional stiffening parts. The combination of the three minimum layers described above gives it sufficient rigidity, each of the layers contributing to this property.

  The main purpose of the perforations made through the so-called "structural" layer, which constitutes the "soul" of the laminated element, is to eliminate the air bubbles trapped at the panel interface. of wood / resin by allowing them to drain towards the vacuum pump via the perforations during the evacuation. Thus the adhesion between these layers of different nature is reinforced.

  The perforations also allow a certain penetration of the resin into the wood, thus impregnating the fibers of the wood towards the very heart of the panel, humidifying it and therefore making it a little more malleable, and therefore deformable according to the desired curvature. , when it is placed in the mold and especially when the assembly is placed under vacuum.

  This network of perforations is preferably a regular network. The size and number of the perforations depends in particular on the thickness and the appearance of the wooden panel. The perforations are advantageously spaced from 1 to 8 cm approximately from each other, preferably from 2 to 5 cm and their diameter is approximately between 0.5 and 3 mm, preferably between 1 and 2 mm.

  The method according to the present invention also makes it possible to give this laminate element shapes or curvatures that are impossible to achieve in conventional construction (for example of a wooden boat). This advantage is particularly accentuated when the panel 5 made of wood or derived from wood is previously impregnated with resin before its application in step c).

  The role of the protective layer of said element is to protect it against ..

  external agents of its environment, for example bad weather, sea water, ultraviolet rays, and to give it a certain seal. It corresponds to the classic 10 "finishing" layer, but as indicated above, it is applied here first. Advantageously, the protective layer can be a paint, a varnish or a protective resin, in particular against UV rays. It can be applied in a single pass or in several passes, whether or not followed by drying.

  This first layer, which may for example be based on polyurethane or on an epoxy compound, may also contain collodal silica (advantageously up to approximately% by weight) which makes it possible to increase its thixotropy during application (avoiding thus the phenomena of leakage) and to give it a certain hardness once dry. The protective layer can also be a layer also having a decorative function such as a layer of fabric (for example silk fabric) or printed paper, impregnated with a resin, a layer of wood (for example teak slats for a boat deck element), or other decorative sheet or panel.

  Advantageously, the reinforcing layer b) contains fibers, which can be plant fibers, synthetic organic fibers, mineral fibers such as carbon or glass fibers.

  The resin composition impregnating these fibers to constitute the reinforcing layer advantageously comprises a resin chosen from acrylic, polyurethane, epoxy, phenolic resins or vegetable gums. This resin composition can also, like the protective layer, contain collodal silica, as well as fillers such as glass microspheres, solid or hollow, and / or PVC, making it possible to lighten the mixture. and give it volume. In addition, the presence of these microspheres leads to matt and slightly abrasive layers and thus allows better adhesion with the neighboring layers.

  If necessary, the application of the layers of steps a) and b) of the process according to the present invention is followed by drying; this drying is recommended in cases where the solvents used in the compositions of the different layers are incompatible with each other, their residual presence being liable to cause delamination. This drying can be carried out at room temperature or in an oven, for example between 40 ° C. and about C.

  In addition, a first evacuation can be carried out between steps b) and c) of the process, making it possible to strengthen the adhesion of the first layers to each other, in particular when the laminated element to be produced is of large dimensions. This first evacuation is advantageously carried out under a vacuum of between 200 and 400 millibars approximately, preferably close to 300 millibars.

  The wood or wood-based panel can be a solid wood panel, plywood, glulam, a panel of fibers and / or agglomerated particles, etc. The process according to the present invention can be adapted to any panel thickness.

  However, if the total thickness required is too large, it is possible to apply several thinner panels instead of just one.

  In situations where it is desired, for example, to improve the buoyancy, or the thermal or acoustic insulation, of the laminated element, it is advantageous to replace the single wooden panel with a lighter or insulating layer such as '' a layer of cellular material, such as foam (preferably rigid) or a material with a honeycomb structure (aluminum, PVC, cardboard, aramid, etc.), sandwiched between a wooden panel or derived from wood, possibly of finer thickness, and another wood panel or a new layer of resin matrix reinforcement. In this case, the structural layer then comprises at least one layer of cellular material (preferably rigid) surrounded by at least two wooden or wood-based panels, the layer of cellular material and the panels being pre-perforated, and assembled with glue.

  It can also be envisaged to incorporate, in this sandwich structure layer 30, a metal frame or a metallic sheet, for example of aluminum or lead, or panels or profiles of PVC or other polymers, between at least two panels wood, in order to give the whole of the particular properties. The only requirement is that this additional layer or sheet is also provided with a network of perforations, allowing the drainage of the bubbles during the evacuation.

  It is also possible to pass, within this sandwich structure, cables, such as electric cables, during the superposition of the different layers.

  The vacuuming step is carried out by means of a vacuum pump, under the highest possible vacuum, that is to say advantageously at least about 700 millibars, preferably up to 1000 millibars, when the process is carried out under ambient atmosphere and temperature. The process according to the invention can also be carried out in an autoclave, if necessary.

  The method according to the invention also allows the assembly between them of wooden panels or wood derivatives juxtaposed by means of joints called leave joints. In this case, the basic composition used in step b) can be used to make these connection pieces and punctual reinforcement: the resin can contain fillers such as collodal silica, cotton micro fibers, micro-spheres glass and / or PVC, mineral or organic fibers, wood powder, etc. ., According to the case.

  This point reinforcement is also incorporated in the mold, on the layers already applied to the wall of this mold, without taking care if there are extra thicknesses or not at these joints, because the latter will then be masked by the layers subsequent and will be found at the heart of the final laminate element. This type of joint makes it possible to link together, at the very moment of their assembly, laminated elements, or parts thereof, which are not necessarily identical (in their constitution, their thickness, etc.). the method according to the invention is therefore not limited to the manufacture of laminated elements with continuous layers, but makes it possible to join sets of superimposed layers forming angles between them.

  The present invention also relates to the laminated elements obtained by the method described above, which have the property of being self-structuring. Are concerned in particular the self-structuring laminate elements comprising the following successive layers: - at least one protective layer - at least one resin matrix reinforcement layer - at least one structural layer comprising at least one wooden or wood-based panel provided with a network of perforations.

  Advantageously, the so-called structural layer may comprise at least one layer of cellular material (as described above) sandwiched between at least two wooden or derived panels, the layer of cellular material and the panels being each provided of a network of perforations. Such laminated elements 5 are for example particularly useful for the design of unsinkable parts in boats, or for the improvement of acoustic: or thermal insulation in various types of constructions.

  In certain laminated elements according to the invention, the structural layer may be covered with at least one new resin matrix reinforcement layer on its free 1o face, itself being optionally coated with at least one finishing layer. The finishing layer can be a layer of paint, a varnish, a gel-coat, a protective resin, or a decorative layer.

  The method according to the invention finds interesting uses for the manufacture of elements intended in particular for naval architecture, in the field of building (and in particular prefabricated buildings), in the construction or fitting out of vehicles, in the field of indoor or urban furniture, or even in the aeronautical field, without these examples of use being limiting.

  Other advantages and characteristics of the present invention will emerge from the following description of several alternative embodiments, given by way of nonlimiting examples, of the process for manufacturing laminated elements, with reference to the appended drawings in which: - Figure 1 is a partial cross-sectional view of a laminated element manufactured according to a first variant of the method of the invention, intended for shipbuilding, - Figure 2 is a partial cross-sectional view of a laminated element manufactured according to a second variant of the method of the invention, also intended for shipbuilding, and - Figure 3 is a partial sectional representation of a laminated element manufactured according to another variant of the method of the invention, intended for the field from 30 building

Example 1:

  Referring to FIG. 1, a two-component polyurethane paint 3, loaded with collodal silica, about 0.5 mm thick, is applied to the internal wall 1 of a female mold 2 covered with a release agent. by spraying with a spray gun. This application is followed by drying for 72 hours at 20 ° C. A reinforcing layer consisting of glass fibers 4 impregnated and covered with epoxy resin 5, containing collodal silica and loaded with glass microspheres, is then applied to the dry paint layer 3, with a thickness of approximately 0 , 3 mm. Then is immediately applied, before the setting of the epoxy resin, a first panel 6 of 10 plywood 5 mm thick, having a network of perforations 7 of 3 mm in diameter about 3 to 5 cm apart from each other other. Then a second plywood panel 9 of 5.mm thick covers the panel 6 previously installed, a new layer of uncharged epoxy resin 8 playing the role of glue between these two wooden panels 6, 9. The panel 9 is also pre-punched with holes 10 of 15 3.mm in diameter, spaced 3 to 5 cm from each other. The vacuum devices, as well as a vacuum bag (not shown) are placed in the immediate vicinity of the superimposition of the layers shown diagrammatically in FIG. 1 and suction under vacuum corresponding to a vacuum of 700 millibars minimum is applied to the by means of a vacuum pump for approximately 5. hours, that is to say during a time corresponding at least to the setting of the paint and of the various layers of resin introduced. After demolding, a self-structuring laminate element is obtained, corresponding here to a wooden hull part of the "Corsair" type.

  Example 2: A deck element of this same type of wooden boat is prepared according to the same method as that described above, the superposition of the layers being presented in FIG. 2 (identical parts bearing identical reference numbers on the figures shown). The steps for applying paint 3, glass fibers 4 in a resin matrix 5, then the first plywood panel 6 5 mm thick, provided with perforations 7, are carried out in a similar manner to those of the example of FIG. 1. Then a layer 12 of PVC foam at 45 kg / m2, 15 mm thick and provided with perforations 13, is bonded by means of epoxy resin 8 to the first wooden panel 6, then a second plywood panel 14 5mm thick, provided with perforations 15 2mm in diameter, identical to the first panel 6, is applied thereto, by means of a layer 16 of the same epoxy resin.

  The whole is placed under a vacuum of 700 millibars for 5 hours until the resin sets. The laminated element obtained after demolding has unsinkable properties, and can be incorporated immediately, without any additional finishing, into the construction of the boat.

  Example 3: The method according to the invention is used here for the construction of a hemispherical building having the shape of a dome of 30 meters in diameter constituted by the assembly, on a voting key, of 16 identical triangular prefabricated elements . Each of these elements has the structure shown in section in Figure 3 (the thicknesses of the various constituents are not shown to scale). 15 On the internal wall 1 of a female mold 2, a layer 20 of 500 micrometers thick of polyurethane-based paint, successively containing collodal silica, was successively applied, - a glass fabric 21 of 600 g / m2, impregnated with an epoxy resin, containing collodal silica and loaded with glass microspheres, - two panels 22, 23 of plywood, 5 mm thick each, separated by a layer of epoxy resin (not shown) , loaded, serving as glue, - a layer 24 of fire-retardant PVC foam 150 mm thick in which is inserted a skeleton 25 of glued laminated wood to reinforce the structure, the two sides of this layer of foam 24 being covered with 25 epoxy resin loaded (not shown), - two panels 26, 27 of plywood 5 mmn thick each, separated by a layer of epoxy resin (not shown), loaded, serving as glue, - a fabric 28 of glass of 600 g / m2, impregnated with a resin not epoxy, containing collodal silica and loaded with glass microspheres, - and finally a layer 29 of interior paint with a classic finish, based on polyurethane. Each plywood panel (22, 23, 26 and 27), as well as the foam layer (24) were previously perforated with a network of holes 30 of 3 mm in diameter, uniformly distributed every 8 cm approximately.

  A vacuum corresponding to a vacuum of between 200 and 400 millibars was applied after the installation of each of the two glass fabrics, and a deeper vacuum, corresponding to a vacuum close to 1 bar, was applied after the installation of the double layers of plywood, for periods sufficient for setting the resin.

  The laminated elements thus manufactured according to the process of the present application allowed the construction of this self-supporting insulating frame, of large area.

Claims (19)

  1. Method for manufacturing a laminated element, comprising the following successive stages of application against the wall (1) of a mold (2): a) at least one protective layer (3, 20) of said element, b) at least one reinforcing layer (4, 21) in a resin composition, c) at least one structural layer comprising at least one panel (6, 22) made of wood or derived from wood, through from which a network of perforations (7, 30) is previously produced, then a step of vacuum plating the layers a) to c) above 10 against the wall (1) of the mold (2), by means of a vacuum bag.   2. Method according to claim 1, characterized in that the panel (6) made of wood or derived from wood is previously impregnated with resin before its application.   3. Method according to any one of the preceding claims, characterized in that the protective layer (3, 20) is a paint, a varnish or a resin for protection against UV rays.   4. Method according to any one of the preceding claims, characterized in that the protective layer (3, 20) and / or the resin composition of the reinforcing layer (4, 21) contains (s) collodal silica .   5. Method according to any one of the preceding claims, characterized in that the reinforcing layer (4, 21) contains fibers.   6. Method according to any one of the preceding claims, characterized in that the resin composition of the reinforcing layer (4, 21) comprises a resin chosen from acrylic, polyurethane, epoxy, phenolic resins, or vegetable gums. 7. Method according to any one of the preceding claims, characterized in that steps a) and / or b) are followed by drying.   8. Method according to any one of the preceding claims, characterized in that a first evacuation is carried out between steps b) and c).   9. Method according to any one of the preceding claims, characterized in that the perforations (7, 30) are spaced from 1 to 8 cm approximately from each other and their diameter is approximately between 0.5 and 3 mm.   10. Method according to any one of the preceding claims, characterized in that the protective layer and / or the resin composition contains (s) glass and / or PVC microspheres.   11. Method according to any one of the preceding claims, characterized in that the structural layer comprises at least one layer of rigid cellular material 5 (12, 24) surrounded by at least two panels (6,14, 23, 26 ) made of wood or wood derivatives, the layer of cellular material (12, 24) and the panels (6, 14, 23, 26) being pre-punched and assembled using an adhesive.   12. Self-structuring laminate element obtained by the method according to any one of the preceding claims, comprising the following successive layers: - at least one protective layer (3, 20) - at least one reinforcing layer (4, 21 ) with resin matrix - at least one structural layer comprising at least one panel (6) made of wood or derived from wood provided with a network of perforations (7, 30).   13. A laminated element according to claim 12, characterized in that the structural layer comprises at least one layer of rigid cellular material (12, 24) sandwiched between at least two wooden panels (6,14, 23, 26) or derivatives, the layer of cellular material (12, 24) and the panels (6, 14, 23, 26) each being provided with a network of perforations (7, 13, 15, 30).   14. Laminated element according to one of claims 12 or 13, characterized in that the structural layer is covered with at least one new reinforcing layer (28) with resin matrix on its free face, itself possibly being coated with at least one top coat (29).   15. Use of the method according to any one of claims 1 to 11 for the manufacture of elements intended for naval architecture.   16. Use of the method according to any one of claims 1 to 1 1 for the manufacture of elements intended for the building sector.   17. Use of the method according to any one of claims 1 to 11 for the manufacture of elements intended for the construction or arrangement of vehicles.   18. Use of the method according to any one of claims 1 to 11 for the manufacture of elements intended for the field of interior or urban furniture.   19. Use of the method according to any one of claims 1 to 11 for the manufacture of elements intended for the aeronautical field.