EP1351818A2

EP1351818A2 - Multilayered shaped bodies with locally defined reinforcing elements

Info

Publication number: EP1351818A2
Application number: EP01989531A
Authority: EP
Inventors: Thomas Engels; Bernd Mayer; Werner Opitz
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 2000-12-07
Filing date: 2001-11-28
Publication date: 2003-10-15
Also published as: WO2002045954A2; DE10060816A1; AU2002227955A1; WO2002045954A3; US20040091723A1

Abstract

The invention relates to multilayered shaped bodies with locally defined reinforcing elements (V1, V2). The multilayered shaped bodies consist of two outer metal layers (M1, M2) and at least one intermediate layer (P). The intermediate layer (P) consists of an organic binding agent and anisotropically distributed reinforcing elements arranged therein. The anisotropic reinforcing elements (V1, V2) are disposed at points of the intermediate layer (P) of the component which are exposed to particularly high structural strain or effects of forces (F1, F2) or where high acoustic radiation occurs. The multilayered shaped bodies enable specifically light layered bodies with high structural resistance to be produced. Preferably, said bodies can be used in the construction of machines, vehicles or devices.

Description

"Multi-layer molded body with locally limited reinforcement elements"

The present invention relates to multi-layer molded articles composed of two outer metallic layers and at least one intermediate layer, processes for their production and use of these molded articles. Multilayer moldings and methods for producing multilayer moldings are widely used wherever it is important to use specifically light structures with a high level of strength and / or rigidity.

Specifically light materials are increasingly being used in machine, vehicle or device construction, especially in automobile construction, in order to reduce the weight of the components or vehicles. For a variety of reasons (legislation, fuel consumption, fuel prices), an increasingly important requirement in the design and construction of motor vehicles is the increase in the structural strength of an automobile construction or a special component while reducing the weight. However, due to the structural strength of the respective construction, a further reduction in the sheet thicknesses of conventional metal constructions in order to save weight can only take place if one switches to either lighter (e.g. aluminum) or structurally stronger metals (e.g. multi-phase steels) as the construction material. The lightweight construction with increasingly thin sheet thicknesses reaches its limits especially where geometrically due to reduced cross-sections of the components, the rigidity of which no longer meets the requirements for usability. The route via lighter or structurally stronger metals is also only pursued to a small extent for reasons of production technology and price, since the forming behavior is less favorable than normal steel sheets, and higher tool costs can also occur. For safety reasons, too, these materials have so far been used only to a limited extent, since these materials have less favorable properties than the conventional materials in terms of energy absorption and material failure in the event of a crash. Although plastics have a low specific weight, they have so far not been able to achieve the performance level of metallic materials by far, and are therefore not used today in the area of structurally stable and load-bearing components.

Since the ideal construction principle or material for an optimum in relation to the performance / weight ratio has not yet been found, the following types of implementation can currently be found in vehicle constructions: conventional construction using sheet steel as a material, aluminum constructions, mixed construction, ie Combinations of different metals including plastics and sandwich structures. The general structure of the latter structures is a combination of two metal cover layers with an organic one Intermediate layer made of plastic. In addition, further intermediate layers in the form of fiber inlays or flat structures, for example made of glass fibers or expanded metal sheets, can be installed.

From EP-A-13146 a metal / thermoplastic / metal laminate is known which has a basis weight below 9.76 kg / m ² and which is made of a thermoplastic core material based on partially crystalline polyamides or polyester with a crystalline melting point> 130 ° C consists of and a metal layer laminated on both sides of the core material, the metal layer having a melting point above the crystalline melting point of the thermoplastic core layer and the metal layer having a minimum thickness of 0.0127 mm. The construction industry, appliance industry, automotive industry and aircraft construction are specified as use for these sandwich materials.

US-A-4759994 describes a sandwich-like structure consisting of two outer metal plates and an inner core between the two outer plates. The core consists of a metallic network or grid. This sandwich structure has an adhesive layer between the metal plates, which connects the two plates and the core to one another, which improves the punching behavior. The adhesive should only be inside the latticework of the core material, while the contact zones between the core and metal plates should remain adhesive-free in order to enable the composite material to be weldable.

DE 19729566 C2 describes a metal composite panel with two outer sheets which are kept at a distance by elevations of a lightweight structural panel arranged therebetween, the lightweight structural panel and the outer panels being connected to one another at the elevations by soldering, welding or gluing. An expanded metal is proposed as a lightweight structural panel.

EP-A-895852 describes a multi-layer steel sandwich structure consisting of two metal plates which are laminated to a core. This core is made of stainless steel wool. The sandwich structure is achieved by soldering, welding or gluing. Phenolic resins, epoxy resins or polyethylene or polypropylene-maleic anhydride copolymers are proposed as adhesives.

DE-A-3905871 discloses a composite material for thermal insulation and / or sound absorption that has a structurally stable covering layer made of a thermally stable metal foil on at least one side. A thermally resistant, highly porous, inorganic material is proposed as the insulation layer, for example foamed glass with a sponge-like structure or gas concrete or foamed ceramic or clay mineral materials. Exhaust areas of an automobile are proposed as an application for this composite material in the automotive sector. From DE-A-3935120 a method for the production of multilayer composite panels is known, in which this composite panel consists of a top and bottom panel and in between a web material made of wire or a metal grid as web material, which prior to its connection to the outer Metal plates is deformed by flattening its lattice nodes. This creates enlarged connection areas between the metal grid and the metal panels, which should also enable reshaping. Although the document states that the connection of the metal grid to the cover plates can in principle be done by adhesive processes, it should preferably be done by welding processes. This document does not provide any further information on suitable adhesives.

WO 00/13890 describes glued multilayer composite panels and methods for producing multilayer composite panels which consist of two outer metal plates which serve as upper and lower base plates and which are bonded to a deformable connecting intermediate layer. The deformable web material lying in the intermediate layer is connected to the cover and base plate by means of a foaming adhesive which fills the cavities remaining in the composite. The web material lying between the metal plates can consist of an expanded metal mesh, a wire mesh or a web plate and it can include a multi-layer sequence of expanded metal meshes, wire meshes, web plates with intermediate plates that are impermeable or permeable to the adhesive. There is no teaching of suitable compositions of the adhesive in this document.

EP 636517 B1 discloses a production method for a vehicle body part, at least in some areas, having a double sheet metal structure with an insulating layer in between. In this method, the base plate and the cover plate of the double-sheet structure are first fixed to one another with the interposition of an insulation layer and then formed together, in particular deep-drawn. A suitable insulation layer material should only be placed on selected surface sections of the flat base plate and a flat cover plate extending over a larger surface section is placed thereon, the insulation layer initially being sufficiently pressure-stable in the edge region to withstand the deformation. The insulation layer material is to be glued to the base plate and the cover plate, the adhesive required for the gluing being applied by foil, sealing cord, rolling / rolling, spray film, adhesive beads or drops.

Furthermore, a method is known from the prior art for reinforcing thin-walled metal structures at highly stressed points, in which so-called "metal patches" are glued to the base plate. Structures of this type are described, for example, in JP 2000/135923 A, DE 19819697 A1, DE 4445943 C1, DE 4445942 C1 or DE 2932027 A. The disadvantage of this method is that at least one side of such sheet metal structures has no flat surface. In view of this prior art, the inventors have set themselves the task of providing multilayer molded articles and a method for their production which are suitable for structural areas of vehicle construction.

The object of the invention can be seen from the claims, it essentially consists in the provision of multilayered molded articles from two outer metallic layers and at least one intermediate layer, in which the entire surface of the laminated article has an anisotropic structure.

Another object of the present invention is a method for producing such multilayer molded articles and the use of multilayer laminates or molded articles for producing components in automobile construction.

The two outer metallic layers of the multi-layer molded body are usually metal sheets. These sheets can be normal steel sheets, but they can also be steel sheets refined by the various galvanizing processes, such as the electrolytically or hot-dip galvanized sheets and the corresponding thermally post-treated or galvanized or subsequently phosphated steel sheets and aluminum sheets. The thickness of these outer sheets can be adapted to the structural conditions. It can be between 0.1 and 1.0 mm, preferably between 0.1 and 0.5 mm, preferably between 0.2 and 0.3 mm. The intermediate layer consists of a polymeric binder composition and the reinforcing elements anisotropically distributed therein. The binder of the intermediate layer can be selected from a variety of thermoplastic polymers or from reactive binders. Examples of thermoplastic polymers are polyethylene, polypropylene, polyamide, polystyrene, styrene copolymers such as e.g. Acrylonitrile-butadiene-styrene (ABS) or thermoplastic elastomers based on block copolymers of styrene with butadiene or isoprene, optionally also in their hydrogenated form, both preferably as three-block copolymers. Further examples of thermoplastic polymers to be used according to the invention for the intermediate layer are vinyl chloride homo- and / or copolymers - e.g. Vinyl chloride / vinyl acetate copolymers, ethylene-vinyl acetate copolymers (EVA), polyester or polycarbonate. Particularly suitable as reactive binders are those based on epoxy resins, reactive rubbers or polyurethanes.

As epoxy resin - binder composition are a variety of - preferably flexible - epoxy compositions. The compositions mentioned in EP-A-354498, EP-A-591307, WO 00/20483, WO 00/37554 and the as yet unpublished applications DE 10017783.2 and DE 10017784.0 may be mentioned as examples. The binder compositions to be used according to the invention contain at least one epoxy resin, a flexible epoxy compound, elastomer-modified Epoxy resin and possibly a reactive thinner and usually a latent hardener, which causes the crosslinking of the binder when the compositions are heated.

Compositions of natural and / or synthetic rubbers (i.e. elastomers containing olefinic double bonds) and vulcanizing agents are suitable as the binder matrix based on reactive rubbers. These contain at least one of the following substances: one or more liquid rubbers and / or solid rubbers or elastomers, finely divided powders made of thermoplastic polymers, vulcanizing agents, vulcanization accelerators, catalysts, fillers, tackifiers and / or adhesion promoters, blowing agents, extender oils, anti-aging agents, rheology aids. Suitable binders are e.g. described in WO 96/23040.

In addition to the aforementioned one-component thermosetting binders, two-component epoxy, rubber or even polyurethane binders which cure at room temperature can also be used.

The anisotropically distributed reinforcing elements of the intermediate layer can be constructed from conventional metal sheets, hardened metal alloys, multi-phase steels, aluminum, expanded metals, organic foams based on epoxides or polyurethanes, which may be fiber-reinforced, or other plastics. These reinforcing elements are preferably arranged at those locations to which the molded body is exposed to high structural loads or forces. These reinforcement elements are already installed during the production of the multilayered molded article as a semi-finished product ("multilayer laminate") in such a way that they are later present exactly at the points of the construction or component where the particularly high structural loads or forces act on the component , These reinforcement elements are preferably tailored in their geometric shape specifically to the load case.

Furthermore, the multilayer molded articles according to the invention can additionally contain functional built-in elements such as Cable channels included. This procedure is particularly useful when these moldings are to be used as roof structures or underbody groups in vehicle construction.

The possible embodiments of the multilayer moldings according to the invention will now be explained in more detail with reference to drawings. It shows:

Figure 1 shows the general structure of an anisotropic multilayer laminate

Figure 2 shows the additional installation of functional elements

Figure 3 shows the exemplary structure of a hood

Figure 4 shows an embodiment of a weldable component. In the general structure of the multilayer laminate according to FIG. 1, the two outer metal layers (M1) and (M2) are metal sheets with a thickness of 0.1 to 1.0 mm. The intermediate polymer layer (P) usually has a layer thickness of 0.3 to 5.0 mm, its thickness depends on the intended use of the component made from the multilayer laminate. All of the aforementioned types of polymers can be used as polymers. The thicker reinforcing element (V1) is arranged at a point where the greatest force (F1) is expected later in the component. The reinforcing element (V2) is located at a point where a lower force (F2) will act. No reinforcement element is provided in places with even less force (F3).

FIG. 2 also shows the installation of a functional element, for example a channel (K) for receiving electrical cables. The remaining structural components of this laminate correspond to the elements shown in FIG. 1.

FIG. 3 shows an exemplary schematic structure of a bonnet in a top view. The geometrical dimensions of the reinforcement elements (V1) to (V5) are adapted to the requirements for the forces acting on the bonnet or the vibration behavior of the bonnet itself. This is important for the mechanical rigidity and / or to minimize the acoustic radiation of the hood. For the sake of completeness it should be mentioned that the reinforcing elements are not visible from the outside.

FIG. 4 shows an exemplary embodiment of a multi-layer molded body which is to be used as a weldable component. Here, too, the anisotropically distributed reinforcing elements (V1) and (V2) are arranged in the polymeric binder matrix (P), but the metal sheet (M1) does not reach into the edge area. The edge areas of the lower metal layer (M2) are provided with welding points (S1) and (S2), so that this component can be installed using conventional welding methods, in particular electrical welding methods. These welds are preferably separated from the metal sheet (M1) by areas of the polymeric binder matrix (P1) and (P2). Of course, multilayered molded articles according to FIG. 4 can also be inserted into the body using structural adhesives instead of welding them together.

The multilayer molded articles according to the invention can in principle be produced by continuous or discontinuous production. In continuous production, a lower cover plate runs horizontally into the production system, then a first binder layer made of the aforementioned polymeric binders is applied from above to the lower cover plate running below using a slot die or a roller. The reinforcing elements and / or functional built-in elements are then applied to the binder layer at the predetermined locations, preferably using a robot. Subsequently, a second binder layer is also applied from above onto the semi-finished product, consisting of a lower cover plate, binder layer and reinforcing elements, using a slot die or a roller. An upper cover sheet is joined to a complete laminate on the semifinished product formed in this way and the entire laminate is pressed onto the final layer thickness using rollers, if necessary with heating. In the case of reactive binder systems, the heating during the joining and / or pressing can be designed in such a way that the crosslinking of the binder system is carried out at an intermediate stage, ie to a pre-hardening step, so that the binder - and thus the multilayer laminate - is still highly deformable and the multilayer laminate produced in this way can be easily deformed in conventional forming processes. A final curing can then take place after the installation of the component thus produced, for example in a motor vehicle body, in the oven for the electrocoating.

In the discontinuous mode of production, a molded part is punched from a lower cover plate, a first binder layer made of the aforementioned polymeric binders is applied to the stamped lower cover plate with the aid of a slot die or a roller or a doctor blade, the reinforcing elements and / or functional built-in elements are attached to the predetermined ones Place, if necessary with the help of a robot, on the binder layer. This is followed by the application of a second binder layer using the abovementioned application methods, the upper cover plate is joined to the layer body thus formed and the entire layer body is pressed, if necessary with heating, to the final layer thickness using rollers or presses. The laminate produced in this way can then be pressed or deep-drawn by shaping into a three-dimensional shaped body.

Even with this discontinuous production method, reactive binders can be cured in two stages, so that forming is facilitated, and the final hardness only takes place after the molded part has been installed in the complete assembly.

The multilayer molded articles produced according to the invention can be used for a large number of applications in which specifically light materials are required which have high structural strength. The areas of application mentioned at the beginning in mechanical engineering, in device construction and in vehicle construction, here in particular in automobile construction, may be mentioned as examples. Specific examples from the automotive industry are the manufacture of roof structures, bonnets, door side panels, walls to the engine compartment ("firewall"), underbody assemblies and walls to the trunk. Compared to the components used hitherto, the multilayer according to the invention have

Molded parts have the following advantages: low specific weight, low overall weight, the structural reinforcement performance can be significantly improved locally in flat areas of a body at the highly stressed points, through the laminate structure - e.g. For roof constructions, bonnets or door side parts, improved acoustic properties can be achieved, in addition, the structural depth of such components can be reduced and thus additional usable space can be obtained. With the selection of suitable polymeric binders, improved heat and heat resistance up to 300 ° can be achieved C, this is important for use in the underbody area or as a wall to the engine compartment ("firewall") the installation of functional elements such as Cable ducts in the organic intermediate layer are possible, e.g. for use in the roof or underbody area, thanks to a staggered production method in which the components are created separately from the production line ("preformed laminate"), individual high-performance modules or high-performance components can be created very quickly and flexibly.

Claims

claims

1. Multi-layer molded body made of two outer metallic layers and at least one intermediate layer, characterized in that the entire surface of the layered body has an anisotropic structure.

2. Multi-layer molded body according to claim 1, characterized in that the intermediate layer consists of a polymeric binder composition and anisotropically distributed reinforcing elements therein.

3. Multi-layer molded body according to claim 2, characterized in that the anisotropically distributed reinforcing elements of the intermediate layer are arranged at those points at which the molded body is exposed to high structural loads or forces and / or the acoustic radiation of the molded body or component is significantly reduced by such reinforcing elements becomes.

4. Multi-layer molded body according to claim 1 to 2, characterized in that the anisotropically distributed reinforcing elements of the intermediate layer made of conventional metal sheets, hardened metal alloys, multi-phase steels, aluminum, expanded metals, plastics, organic, possibly fiber-reinforced foams, based on epoxies or polyurethanes are built up.

5. Multi-layer molded body according to claim 1 or 2, characterized in that the intermediate layer additionally contains functional built-in elements, in particular cable ducts.

6. Multi-layer molded body according to at least one of the preceding claims, characterized in that the binder of the intermediate layer made of thermoplastic polymers selected from polyethylene, polypropylene, polyamide, polystyrene, styrene copolymers, vinyl chloride homo- and / or copolymers, EVA, polyesters, polycarbonate or reactive binders selected from epoxy resins, reactive rubbers or polyurethanes.

7. A method for producing a multi-layer molded body in the form of a multi-layer laminate according to at least one of the preceding claims, characterized by the following essential method steps a) a lower cover plate runs horizontally into the production system, b) a first binder layer according to claim 6 is made using a Wide slot nozzle or a roller applied from above to the lower cover plate running underneath, c) the reinforcing elements according to claim 4 and / or the functional built-in elements are applied to the binder layer at the predetermined locations, if necessary with the aid of a robot, d) a second binder layer according to claim 6 is applied from above with the aid of a slot die or a roller the lower cover sheet running according to a) to c) is applied underneath, e) an upper cover sheet is attached to the laminate formed according to a) to d), f) the entire laminate is, if necessary. with heating, pressed to the final layer thickness using rollers.

8. A method for producing a multi-layer molded body according to at least one of claims 1 to 6, characterized by the following essential process steps: a) a molded part is punched from a lower cover plate, b) a first binder layer according to claim 6 is made using a slot die or a Roller applied from above to the lower cover plate running below it, c) the reinforcing elements according to claim 4 and / or the functional built-in elements are applied to the binder layer at the predetermined locations, if necessary with the aid of a robot, d) a second binder layer according to claim 6 is applied with the aid of a slot die or a roller from above onto the lower cover plate running according to a) to c) and e) an upper cover plate is attached to the laminate formed according to a) to d), f) the entire laminate is possibly. with heating, with the help of rollers or! Pressing to the final layer thickness g) the laminate produced according to a) to f) is pressed or deep-drawn by shaping into a three-dimensional shaped body.

9. Use of multilayer laminates or moldings according to claim 7 or 8 for the production of components for automotive engineering.

10. Use according to claim 9 for the manufacture of roof structures, bonnets, door side panels, boundary wall to the engine compartment ("firewall"), underbody assemblies.