WO2006134079A1

WO2006134079A1 - Composite part such as a panel, comprising a honeycomb structure

Info

Publication number: WO2006134079A1
Application number: PCT/EP2006/063065
Authority: WO
Inventors: Antoine Antoine
Original assignee: Antoine Antoine
Priority date: 2005-06-15
Filing date: 2006-06-09
Publication date: 2006-12-21
Also published as: DE202006020359U1; FR2887174B1; FR2887174A1

Abstract

The invention concerns a composite part such as a panel, comprising a honeycomb cellular structure (20), a synthetic foam material (21) filling at least partly the cells. The honeycomb structure (20) is made of synthetic material whereof the surface tension prior to the surface being treated does not allow the foam to adhere, and at last part of the inner surface of the cells is treated such that the foam adheres thereto directly or indirectly. The invention also concerns a method for making such a part.

Description

Composite part such as a panel, having a honeycomb honeycomb structure.

The invention relates to a panel or composite part comprising honeycomb honeycomb structure.

In the construction of buildings, land vehicles, air vehicles or boats, panels are frequently used for which good qualities of mechanical strength, lightness, sound and heat insulation are desired. For example, insulating panels made of expanded or extruded polystyrene are used. However, these panels have low mechanical properties. For example, if one wishes to realize an isolated floor, one can use such plates distributed on the ground and on which a screed is made. The load acceptable by such an embodiment is limited because of the compressibility of the panels.

So-called "sandwich" panels are known which comprise external faces, parallel to each other, connected by a core of expanded synthetic material, such as polystyrene or polyurethane. The facings are for example plaster, sheet metal, wood or composite synthetic material. Such panels make partitions, walls or roofs. These panels also have limited mechanical strength. In EP 8 960, there is provided a panel comprising two facings connected by a core having a honeycomb honeycomb structure and cells filled with synthetic foam. Such a panel combines the mechanical properties of a honeycomb structural panel with the thermal insulation properties of the foam. However, to maintain assembly between the facings, the foam is reinforced with fibers from a layer covering the inner face of the facing. The use of fibers is expensive and decreases the facilities for recycling materials at the end of the life of the panel or the product.

The invention aims to provide a composite part such as a panel having good properties of mechanical strength and thermal and sound insulation. It is also an object of the invention to provide a composite part easy to recycle at the end of life. With these objectives in view, the subject of the invention is a composite part such as a composite panel comprising at least one honeycomb honeycomb structure, a synthetic foam material at least partially filling the cells. The honeycomb structure is made of synthetic material whose surface tension before treatment does not allow the adhesion of the foam, at least a portion of the internal surface of the cells being treated so that the foam adheres directly or indirectly thereto. Some synthetic materials normally have a surface on which it is difficult, if not impossible, to adhere foam or glue. However, by a suitable surface treatment, the surface of the honeycomb structure is modified so that the foam adheres to it. Thus, after curing the foam, the structure and the foam form a complex combining the mechanical properties and insulation. The foam is for example polyurethane foam or polystyrene. It may also be expanded polystyrene or expanded polypropylene. In this case, the expansion is carried out when the balls are in the cells, and a glue suitable for adhering the foam against the treated walls is used.

Among the materials that can be used to produce the cellular structure, mention may be made, for example, of polyethylene, polypropylene, polyester or polyester. polyamide. The material can be chosen for its recycling facilities.

By way of example, the surface tension of the cellular structure before treatment is less than 38 mN / r. Foams or adhesives generally do not adhere to materials having such surface tension, such as polypropylene.

After the surface treatment, the value of the surface tension of the honeycomb structure increases, reaching for example a value greater than 38 mN / m (milli-Newton per meter, or dynes per square centimeter).

In a particular embodiment, the foam completely fills the cells. In this case, the inner surface of the honeycomb structure is preferably treated completely, so that the foam adheres to the largest possible area. The rigidity of such a piece is greater than that of a honeycomb structure alone, due to the filling of the cells with the foam and the attachment of said foam to the inner surface of the cells.

Such a panel can be used as a building block for building other products. For example, a door is made by placing the panel in a box or between two facings attached by gluing. It is also used to make a floor by interposing it between a floor and a screed. Compared to a foam board according to the prior art, the mechanical resistance to compression is greatly increased by the presence of the honeycomb structure, while maintaining good sound and heat insulation properties.

It is found that, even in the absence of siding, this panel does not disperse, because the foam present in the cells is retained by the adhesion to the walls of the cells. In addition, when the panel is cut for example, the foam remains in the cells, even if these are open. The song then has a continuous surface on which we can stick a siding or by which we can assemble the panels between them. According to a second embodiment, the panel or the part comprises at least one facing extending along the honeycomb structure so as to close the cells and adhering to the foam. The facing is attached to the honeycomb structure by means of the foam which adheres to the walls of the honeycomb structure and on the inner surface of the cladding. Depending on the destination of the panel or the room, the facing may be of conventionally used material, such as wood, plaster, sheets of synthetic composite material or metal sheets. If the facing has an inner face that does not allow sufficient adhesion of the foam, the inner face can also be treated beforehand.

The piece may have only one facing or siding on each face. The two facings are not necessarily of the same nature. One of the facings may be a sheet having an adhesive outer face covered by a silicone paper. Thus, the panel can be attached to a support surface after removing the silicone film and applying the adhesive side to the support surface. This reinforces the support and improves the insulation qualities.

This panel may be used directly as a partition, wall or floor element, roof, in a building or an air vehicle, land or sea. You can also make a pontoon or a buoy, because of its insubmersibility. You can also give it a shape like the inside of a car bumper. Compared to a foamless panel, the compression damping properties are improved by the that the air is better trapped in the bubbles of the foam that adheres to the cells of the honeycomb.

In a particular way, the panel or the composite part has two facings parallel to each other, extending along the honeycomb structure so as to close the cells, the foam being distributed in two layers respectively adhering to the facings. Thus, there remains an empty space between the two layers of foam. A light panel is obtained, which has mechanical damping properties of a shock perpendicular to the panel, ie in the axis of the cells. Indeed, the panel or the piece can crash during a localized shock by the approximation of the foam layers between them and the crushing of the median portion of the honeycomb structure.

According to a third embodiment, the part comprises two honeycomb structures separated by a sheet and sandwiched by two parallel sections to the sheet so as to seal the cells, the sheet and the facings adhering to the foam. The sheet can serve as a metal shield, such as steel or aluminum, and a particularly strong panel is thus obtained. Such a panel can be used as a fire-fighting element. According to a particular arrangement, the honeycomb structure is formed by tubular elements juxtaposed and interconnected by the foam. A honeycomb structure is thus reconstituted with the tubular elements, and by assembling them together with the foam that acts as glue between them.

According to another particular arrangement, the part comprises a fastener inserted in at least one cell and held by the foam. The insert can be a nut or a screw and is anchored to the honeycomb structure by means of the foam which acts as glue. The invention also relates to a method of manufacturing a part as described above, wherein the method of depositing synthetic material expanding in the cells of the honeycomb structure. At least a portion of the internal surface of the cells is pretreated in order to increase the surface tension of the surface and thus the adhesion of the foam.

The treatment of the cellular structure is carried out by one of the methods among a corona treatment, a plasma treatment or a chemical treatment.

Corona treatment is also referred to as a corona effect and involves subjecting the synthetic material to an electric field to ionize the atmosphere on the surface of the material. The chemical structure on the surface is modified, in a manner known per se, in particular by the creation of peroxide functions (00H), so that the surface tension of the surface is increased.

A similar effect can be achieved by creating a plasma near the surface of the material. The chemical modification of the surface can also be obtained by bathing in a chromite solution. According to a particular method, the foam is formed by balls of material to be foamed, the honeycomb structure being coated with glue, and then the balls are expanded by adhering to the structure via the glue and between them. Methods of making plates by bead expansion such as polystyrene, polypropylene or polyethylene are known. Having pre-glued the honeycomb structure, the expansion is carried out in the cells, which allows the balls to fill the cells and agglomerate together. In addition, thanks to the glue, this formed foam also adheres to the walls of the cells. The process can also be perfected by also coating or only the balls with glue, to increase their adhesion between them. The expansion is for example 20 to 50% of volume. For a foam and a polypropylene honeycomb structure, it is possible for example to use a vinyl glue such as Bostik Vinycol 1520 glue.

(registered trademark) with 5% hardener Desmodur RC

(trademark) .

In order to manufacture a panel with two facings and two layers of foam, it is possible, for example, to use a method according to which a first layer of expanding synthetic material is deposited on a first facing, the honeycomb structure is deposited on the first face through the first layer, to form a first set, is deposited on the second facing a second layer of synthetic material expanding, and depositing the first set on the second facing, the honeycomb structure passing through the second layer. Preferably, to manufacture a composite part with the tubular elements, the entire inner and outer surface of the tubular elements is treated.

The invention will be better understood and other features and advantages will appear on reading the description which follows, the description referring to the appended drawings in which: FIG. 1 is a sectional view of a panel according to a first embodiment embodiment of the invention; Figure 2 is a view similar to Figure 1 of a panel according to a second embodiment of the invention; Figure 3 is a sectional view during a manufacturing phase of a panel according to a third embodiment; FIG. 4 is a view similar to FIG. 1 of the panel according to the third embodiment of FIG. the invention; Figure 5 is a view similar to Figure 1 of a panel according to a fourth embodiment of the invention; FIG. 6 is a perspective view of a tubular element for producing a panel according to a fifth embodiment of the invention; Figure 7 is a sectional view parallel to the facings of a panel according to the fifth embodiment of the invention.

Composite panels or technical parts according to the invention are made with honeycomb honeycomb structure and synthetic foam.

The honeycomb structure may be made conventionally, for example by extrusion of thermoplastic material, or by assembly of continuous strips joined alternately with one or the other of two adjacent strips, as described in the WO document.

98/41388. The structure can also be achieved by the assembly by gluing or welding of tubular elements of hexagonal or circular section. The material is for example polypropylene.

The inner surface of the honeycomb structure is corona treated, for example by passing the end of the cells near an electrode. The document FR 2 443 753 describes an example of a machine and method capable of treating the honeycomb structure. To allow the treatment of honeycomb internal ducts at heights of 50 mm and above, the electrical voltage used may be up to 50 kilovolts or more and the frequency may be less than

15 kilohertz. The foam is for example polyurethane, conventionally obtained by foaming a mixture of a polyol and a diisocyanate with a swelling agent type HFC.

According to a first embodiment, shown on the FIG. 1, the foamable mixture is spread on a first molding plate, not shown, then the honeycomb structure 10 is deposited on the molding plate, and the honeycomb structure is sandwiched with a second molding plate, not shown, parallel at the first plate. The entire foaming of the mixture is expected throughout the volume of the cells and the hardening of the foam 11. Then the plates are removed to extract the panel 1 formed by the cellular structure 10 and the foam 11. The plates are for example covered by a Silicone or PTFE-based coating to prevent adhesion of the foam to the plates. In a variant, the honeycomb structure 10 is deposited on the first plate and then the mixture is deposited on the plate or introduced directly into each cell.

According to a second embodiment, shown in FIG. 2, the molding plates are replaced by facings 22, 23. The foam 21 then adheres to the facings 22, 23 as well as to the walls 25 of the honeycomb structure, which gives a cohesion to the panel 2. It is also possible to manufacture a panel with a single facing.

According to a third embodiment, shown in FIG. 2, the mixture is first spread on a first face 32 and then the honeycomb structure 30 is placed on the first face 32. The mixture is transformed into a foam 31 which develops in the lower part 301 of the cells. The foam adheres to the walls 35 of the cells in said lower portion 301. After curing of this first layer 31 of foam, the second layer 33 is prepared with a layer of mixture and the assembly 36 formed by the first layer 32 and the honeycomb structure 30 is applied to the second layer 33. A second layer 37 of foam is formed symmetrically to the first layer 31, leaving a vacuum 38 between the two layers 31, 37 of foam. For to limit the expansion of the foam, it is possible to treat only the lower part and the symmetrical part of the cells.

According to a fourth embodiment, illustrated in FIG. 5, a panel is obtained by completing the panel 2 according to the second embodiment with a layer of mixture deposited on one of the facings 23 which is a sheet or other metal part such as aluminum, then a second honeycomb structure 40 and finally another facing 42. The honeycomb structure 40 is filled with foam 41. A panel could be made with only the sheet and the two cellular structures, without the facings 22, 42.

In a fifth embodiment, the procedure is as in the second embodiment, but the honeycomb structure consists of the juxtaposition of tubular elements 5, not interconnected before laying on the facing, as shown in Figure 6 The section of the tubular elements is substantially hexagonal, with curved faces towards the outside. The tubular elements 5 are made of polypropylene or other synthetic material and are treated over their entire surface, both inside 50 and outside 51. The tubular elements are arranged in contact with each other by their curved faces so that there remains a space between them, as shown in Figure 7 The polyurethane 52 then wraps the tubular elements 5 and fills them so that they are finally glued together and at the siding. This honeycomb structure can also be used with the other embodiments.

Claims

Composite part comprising at least one cellular honeycomb structure (10), a synthetic foam material (11) at least partially filling the cells, characterized in that the honeycomb structure (10) is made of synthetic material whose surface tension before treatment does not allow the adhesion of the foam, at least a portion of the inner surface of the cells being treated so that the foam adheres directly or indirectly.

2. Part according to claim 1, wherein the surface tension of the honeycomb structure (10) before treatment is less than 38 mN / r.

3. Part according to claim 1, wherein the foam (11) completely fills the cells.

4. Part according to claim 3, characterized in that it comprises at least one facing (22, 23) extending along the honeycomb structure (20) so as to seal the cells and adhering to the foam

(21).

5. Part according to claim 1, characterized in that it comprises two facing (32, 33) parallel to each other, extending along the honeycomb structure (30) so as to close the cells, the foam being distributed in two layers (31, 37) respectively adhering to the facings (32, 33).

6. Part according to claim 1, characterized in that it comprises two honeycomb structures (20, 40) separated by a sheet (23) and sandwiched by two facing (22, 42) parallel to the sheet (23) so as to close the cells, sheet metal and siding adhering to the foam.

7. Part according to claim 1, wherein the honeycomb structure is formed by tubular elements (5) juxtaposed and bonded together by the foam (52), the outer surface (50) of the tubular elements (5) being treated as the inner surface (51).

8. Part according to claim 1, characterized in that it comprises a fastener inserted in at least one cell and held by the foam.

9. A method of manufacturing a workpiece according to claim 1, wherein the expanding synthetic material is deposited in the cells of the honeycomb structure (10), characterized in that before processing at least a portion of the internal surface of the cells to increase the surface tension of the surface and thus the adhesion of the synthetic material

(H) •

10. The manufacturing method according to claim 9, wherein the treatment of the honeycomb structure (10) is carried out by one of the methods among a corona treatment, a plasma treatment or a chemical treatment.

11. The manufacturing method according to claim 9, wherein the foam is formed by balls of material to be foamed, the structure or the beads being coated with glue, then the balls are expanded by adhering to the structure via the glue and between them.

12. Manufacturing method according to claim 9, for manufacturing a part according to claim 4, wherein: a first layer (31) of expanding synthetic material is deposited on a first face (32), deposited on the first facing. the honeycomb structure (30) through the first layer (31), to form a first assembly (36), is deposited on the second facing (33) a second layer (37) of synthetic material expanding, the first set is deposited (36) on the second facing (33), the honeycomb structure (30) passing through the second layer (37).

13. The manufacturing method according to claim 9, for manufacturing a part according to claim I ₁ wherein the entire surface (50, 51) of the tubular elements (5).