DE29712684U1 - Multi-layer composite panel - Google Patents

Description

Lederer. Keller & Riederer, PO Box 2664. D-84010 Landshut

Max Joseph Graf v. Montgelas, 84175 Gerzen PO Box 26 64

(84028 Landshut, Freyuog 615)

Karl Harald Erlinghagen, 91338 Igensdorf Telephone (os 71)2 21 70

Fax (08 71) 2 21 43

Udo Finke, 84175 Gerzen

Multilayer composite panel

The innovation relates to a multi-layer composite panel with at least one profiled layer, namely a corrugated profile with crest lines lying in one plane on each side.

Such a composite panel has already been proposed (European patent application 97 100 947.7, Fig. 4). It has the special feature of a grid of welding points at which the apex lines of adjacent profiled layers are welded together. Depending on the application and production possibilities, the design of the composite panel can be varied, for example with only two profiled layers and corrugated outer surfaces or with a large number of profiled layers and flat outer layers, as well as with different corrugation steepness and different layer thicknesses, which also varies the density of the welding points. The composite panels can also be manufactured with a certain degree of flexibility, for example for packaging purposes, and have bending and cutting lines to form a cardboard blank. If there is a very low number of welding points in relation to the area, the result can be that the strength of the composite panel, i.e. the cohesion of the layers, suffers.

On the one hand, the possibilities of welding, on the other hand, the aspects of strength may make a variation of the previously proposed multi-layer composite plate appear to be appropriate in that an intermediate plate is inserted between at least two adjacent layers, which is aligned with the apex lines of the

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welded to the profiled layers that abut it. Line welding can result in a stronger weld than spot welding, at least if the same penetration depth is achieved. The aim of achieving the same penetration depth is of course only sensible if this is possible without such a pressing force that the multi-layer structure would be damaged. The intermediate plates can be used between all the profiled layers, between some profiled layers or at least as the only intermediate plate between two of the profiled layers. The profiled layers are thus welded to this intermediate plate not only spot-wise but along lines, which requires a modified and, depending on the equipment available, possibly simpler welding technique and which influences the strength and rigidity properties. The insertion of the intermediate plate is particularly important if due to a lower steepness or small amplitude of the waviness, e.g. a relatively flat zigzag, the density of the welding points would be relatively low without the intermediate plate, which can be the case in particular with flexible composite panels.

The application of folding and cutting lines and also the gluing and welding of bending hinge strips for the production of, for example, packaging and moving boxes is also, and even particularly, useful for multi-layer composite panels that do not have the intermediate panel described and are somewhat flexible. For smaller boxes, thinner composite panels, e.g. with only a single profiled layer, are preferred. Packaging units produced accordingly are water-resistant and can be easily reused.

The profiled layers themselves consist of a multi-layer, in particular three-layer composite. The intermediate plates are preferably also made of this composite, but this is not absolutely necessary. In addition, the profiled plates welded to both sides of the intermediate plates can be oriented differently, in particular at right angles to one another, but also with parallel apex lines, and these can in turn be welded directly opposite one another or offset from one another.

The individual profiled layer and preferably also the intermediate layer is initially structured in the form of a single-layer plate as a multi-layer extruded composite, the middle layer of which consists of a highly crystalline polymer with

built-in tensile fibers, in particular steel, glass or carbon fibers, whose melting point is at least 15°, preferably at least 30° higher than the melting points of the polymers of the outer layers and whose modulus of elasticity is at least 10% lower than the modulus of elasticity of the polymers of the outer layers, depending on the technical load. The at least three plate layers are held together with very high adhesion by being made from the same material group and extruded in multiple layers, a technique known for flexible films; the middle layer provides the mechanical strength and the outer layers are easy to weld by selecting appropriately modified variants of the polymer and are relatively soft or relatively hard depending on the intended application. They can consist of foam of the same material as the other layers or be covered with it and thus be shock-absorbing. The lower modulus of elasticity creates a damping effect under impact loads and at lower temperatures. Polyolefins, and in particular polypropylene, are preferred as materials for the composite panel. They have proven to be particularly useful in the context of the innovation, although other, but usually more expensive, plastics can also be used with special properties; for example, linear polyester, polyethylene terephthalate and polybutylene terephthalate, which can also be used in combination, have better resistance even at extreme temperatures and can also be produced transparently, but are more expensive than polypropylene. Other materials include polyethylene, ketone plastics including polyether ketone, which, however, should only be used in exceptional cases due to its high price, or PVC and polyurethane.

The high-tensile fibers of the middle layer are preferably chemically coupled to the polymer, i.e. by chemical bonding.

The wave profile of the profiled layers is preferably a zigzag profile, the apex lines of which are parallel edges, between which there are flanks, the outer sides of which converge at an angle of inclination between 30° and 60° at the apex line. The profiled layer preferably has a volume filling ratio of 30% to 50%.

The multilayer composite panel according to the invention consists, according to one of the preferred embodiments, of a plurality of layers, of which the two

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The outer layers are three-layer flat composite panels, between which there are four profiled layers, between which there are in turn a total of three flat intermediate panels, whereby the profiled layers are welded directly to the intermediate panels or flat composite panels on both sides and each of the profiled layers has vertex lines that are parallel to one another and the vertex lines of the profiled layers that are each adjacent to one another via an intermediate panel form an angle of over 20°, preferably a right angle. With this stack of flat and profiled panels welded together, a relatively rigid, but also elastic composite can be created, the material consumption and weight of which are relatively low. Preferably, the troughs of the profiled layers are filled with foam, which initially makes it easier to maintain the temperature during the welding process until the welding process is carried out and later has the advantage that the plate is protected from water running into it, which increases the weight and could cause damage to the plate in the event of frost.

The shape of the profiled layers is expediently such that they have a zigzag profile with slightly thinner apex areas, along which the outer layer can then be heated and melted more easily, while the slightly thicker flanks do not yet begin to soften. To increase the surface pressure at the contact and then connection lines during mutual penetration into the respective outer layer of the neighboring layer, the zigzag profile can be selected so that the angle in the apex area is even more acute than the angle of inclination of the flanks to each other, i.e. in the sense of a "donkey's back shape".

Further details, advantages and developments of the innovation can be found in the following description of preferred embodiments with reference to the drawing. They show:

Fig. 1 shows a perspective view of a corner of a seven-layer composite panel, which has a layer in the middle in the form of an intermediate panel;

Fig. 2 shows a schematic perspective view of a still flat plate used for the individual layers, as well as an indication of the installation

their production;
Fig. 3 a section through a composite of several profiled layers, partly with and partly without an intermediate plate, showing a

connection point and several connecting lines;
Fig. 4 in front view a section of a modified plate profile of a layer

a composite panel in two different designs.
Fig. 5 shows a perspective view of a piece of a six-layer composite panel,

which has a crease line;
Fig. 6 shows a perspective schematic representation of a folding box made of the material of Fig. 5.

Fig. 1 shows a composite panel 24 consisting of seven layers that is flat overall. It is universal and can be used, for example, as a formwork panel. Its seven layers are an external first layer 25, consisting of a flat base plate 1 according to Fig. 2; a second, profiled layer 26, consisting of a zigzag plate; a third, profiled layer 27, also consisting of a zigzag plate, but in an arrangement rotated by 90 degrees, such that the lower apex lines 14 of the layer 26 and the upper apex lines 14 of the layer 27 intersect at right angles; a fourth, again profiled layer 28, which is oriented in the same way as the panel of the second layer 26; a fifth, also profiled layer 29, which is the same as the third layer 27; a sixth layer 30, consisting of a flat base plate 1; and, inserted between the layers 27 and 28, a layer made of a flat intermediate plate 31, which is welded to the adjacent profiled layers 27 and 28 along their apex lines 14 touching the intermediate plate 31, while in the embodiment shown, the layers 26 and 27 as well as 28 and 29 are welded to one another at certain points. However, such intermediate plates 31 could also be inserted between these layers, and the welding can be limited, for example, to every second, third, etc. apex line 14 of the adjacent profiled plates. The layers 25 and 30 are the outer plates of the composite plate 24. In Fig. 1, the plates of the layers 26 and 28, as well as the plates of the layers 27 and 29, are each shown approximately in phase, i.e. with apex lying straight above or below one another. This is not necessary in itself,

The panels could also be installed offset perpendicular to their vertex lines.

The first layer 25 and the sixth layer 30 have hard and cold-resistant layers on their outer sides and softer, easily weldable layers on their inner sides facing layers 26 and 29. The plates of layers 26 to 29 and 31 have easily weldable layers on both sides. Layers 26 and 29 are connected to layers 25 and 30 along welding lines 33 which coincide with the edge-shaped apex lines 14; layer 26 is connected to layer 27 and layer 28 is connected to layer 29 via welding points 34, namely the intersection points of the respective upper and lower apex lines 14 which intersect at 90°. Layers 27 and 28 are connected to the intermediate plate 31 via welding lines 35. In the example shown, which corresponds to a total plate thickness of 21 mm, the welding points 34 have a density of 9 welding points/cm ² . The number of welding points varies depending on the plate variant.

In Fig. 1, a foam filling 37 is shown in a part of the panel shown by means of dot hatching. The foam density in the example described is in the order of 20 kg/m ³ . The foam filling therefore hardly increases the weight of the panel, but prevents water from entering and is sound-absorbing. These properties can be of particular importance, for example, when installed in a screed to reduce impact noise or in the case of permanent formwork. The foam also connects any individual cold, i.e. unsuccessful, welds.

The composite plate 24 according to Fig. 1 has excellent properties in terms of bending stiffness, surface pressure resistance and point pressure resistance, abrasion resistance, heat and cold resistance and handling. It is lightweight, easy to process, namely the possibility of sawing, drilling and nailing, with a high modulus of elasticity, and a surface finish adjusted to the intended use, namely smooth, rough, blunt, with a pattern and the like. The only intermediate plate 31 in the example shown influences the bending properties and the thickness tensile strength of the composite plate 24 and proves to be important, for example, when the apex lines are at a greater distance from one another, so that without an intermediate plate only a low weld point density would result, or when only a selection of the apex lines

14 can be used as welding lines 35.

To produce the composite panel 24, base panels 1 are first produced and partially converted into profiled panels. According to Fig. 2, the individual base panel 1 consists of three layers, namely an outer layer 2, a middle layer 3 and another outer layer 4. The base panel 1 is shown as it exits a triple extrusion nozzle 8, which is fed from two raw material tanks 9 and 10, of which the tank 9 supplies the material for the outer layers 2 and 4 and the tank 10 supplies the material for the middle layer 3.

The three layers 2, 3 and 4 of the base plate 1 consist of polypropylenes, namely the outer layers 2 and 4 of a soft polypropylene with a melting point of approx. 130° C and the middle layer 3 of a mechanically very tensile polypropylene, with which long glass fibers are chemically coupled, with a melting point of approx. 165° C. The melting point difference of approx. 35° C is relatively generous, but it should not be below 30° if possible and is practically no longer usable in the sense of the innovation if it is below 15° C.

In the base plate 1 according to Fig. 2, the material of the outer layers 2 and 4 is the same. However, there is also a need for base plates 1 with different materials of the outer layers 2 and 4. The properties of the plastic materials are adjusted in a known manner using copolymer components, for example the outer layer 2 can be very hard, impact-resistant and temperature-resistant down to e.g. -20°, while the outer layer 4 is still a soft, easily weldable layer. For various applications, for example as a floor plate, it may again be necessary to produce the outer layer 2 from a material with high static friction, or when used as a wall plate from a material that has certain flow properties and closes holes that arise, such as nail holes, after the cause of the hole has been removed. With such different material properties of the outer layers 2 and 4, a third raw material tank is required for one of the outer layers.

Layers 2, 3 and 4 consist of materials from the same material group, namely propylene, which makes the bond between them very strong. The middle layer 3 provides the required mechanical strength properties and the outer layers 2 and 4 provide the desired contact properties.

To produce the multi-layer composite panel, suitable embodiments of the base plate 1 are then provided with a corrugated profile, for example by deep drawing. For this purpose, an embossing calender is preferably used, the profiled rollers of which emboss the base plate 1 and lengthen it in the direction transverse to the running direction, which is carried out in a given temperature range, which for polypropylene is in the order of about 120° C, and in the course of cooling from a previous, considerably higher temperature, preferably about 170° C. This previous temperature can, for example, be the one during extrusion, so that the embossing calender is arranged shortly after the extrusion nozzle and after controlled cooling. For economic reasons, however, it usually seems more practical to initially store the extruded base plates, heat them up again for later deep-drawing, and then cool them down to approx. 120° C, in order to then stretch the plate during deep-drawing or, after this cooling, "cold-stretch". The processes involved in cold stretching are well known and are used in particular for films. After calendering, the profiled plates are best left to cool down and stored until further processing.

The profiled plates are usually made from base plates 1 with similar, easily meltable outer layers 2 and 4. If the base plate has a thickness of e.g. 1.5 mm, the profiled plate only has a thickness of the order of 0.75 mm. It has the apex lines 14 on both sides and flanks 15 in between. The strict zigzag shape shown in Fig. 2 with flat flanks 15 and sharp edges as apex lines 14 proves to be advantageous, but is by no means the only possible wave shape. For example, a sinusoidal shape would also be possible as a wave shape, although this is not so easy to weld due to the relatively large contact surfaces, or the plate step profiles described later.

The welding of the layers can be achieved by heating the plates forming the layers by irradiation with long-wave infrared light on the sides of the plates facing each other to a temperature that lies between the melting temperature of the outer layers 2 and 4 that are to be contacted with each other and the melting temperature of the two middle layers 3. Furthermore,

9.

- optionally - hot foaming polypropylene material is applied to the opposing surfaces, whereby additional heat is introduced and the welding temperature is preserved during subsequent transport steps. The outer layers are thus at least plasticized or even completely melted, after which the panels are pressed together using pressure. This is conveniently done by passing them through a press calender with a precisely adjusted roller gap, whereby the contacting outer layers 2 and 4 flow into one another through pressure and heat, preferably until the two middle layers 3 touch each other.

It is advisable to first weld layers 26 and 27 and then layers 28 and 29 together in the same way and then the double layer 26 + 27 on the one hand and the double layer 28 + 29 on the other hand are welded to the intermediate plate 31. Then layers 25 and 30 are welded on in the same way one after the other or at the same time, whereby the top and bottom apex lines 14 of the already produced composite become the welding lines 33. Before or during the respective welding processes, the plastic foam is introduced and fills the cavities. After cooling, the plate is ready. The welding of the individual layers can of course also be carried out in a different order. The described production in the successive work steps is recommended for economic reasons. Technically, production in a single work step is also possible.

The plate 24 can be subjected to special treatments on its outer surfaces by passing the base plate 1 through an embossing calender while it is still warm. It is also possible to first apply a glass fiber fabric to the outer layer 2 of the base plate, which is connected to the outer layer 2, which is still soft from extrusion, by passing it through a calender arrangement, and then to apply a smooth plastic layer to this again by means of an extruder. Such an additional design of the base plate 1 is then only useful for the outer layers 25 and 30, but not for producing the profiled layers.

The result of the welding is shown in more detail using an example in Fig. 3. The figure shows a section of the plate, with parts of

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four profiled layers 45, 46, 47 and 48. Between layers 46 and 47 there is an intermediate plate 51 and between layers 47 and 48 there is an intermediate plate 52. In the embodiment shown, the middle layers 3 of layers 45 and 46 touch at the welding points 34 and of layers 46 and 47 and intermediate plate 51, and also of layers 47 and 48 and intermediate plate 52 at the respective welding lines 35. The material of the lower outer layer 4 or the upper outer layer 2 of layers 45 and 46, 46 and 51, 51 and 47, 47 and 52 and 52 and 48 is displaced in the welding point or welding line area between the middle layers 3. This contact between the middle layers 3 significantly increases the modulus of elasticity in the thickness direction. If a certain modulus of elasticity is desired, material from the outer layers 2 and 4 can remain between the middle layers 3 by adjusting the gap width of the press calender accordingly. The mutual penetration into the respective adjacent outer layer 2 or 4 is facilitated by an acute angle in the apex area, which enables the use of a lower pressing force and thus the use of a lighter calender. Relatively steep flanks 15 of the profiled layers also increase the modulus of elasticity in the thickness direction, but on the other hand lead to a higher volume filling level and thus to a higher weight of the plate. Depending on the characteristics of the plates required in the individual case, an optimum can be determined here.

In the representation of Fig. 3, to illustrate the variety of possibilities, the relative orientations of layers 45 and 46 on the one hand and layers 47 and 48 on the other hand are each shown rotated by 90°, while layers 46 and 47 on both sides of the intermediate plate 51 are oriented parallel, but offset from each other by half a wave period. The significance of this offset lies in the possibility of influencing the flexibility of the composite plate in a bending direction.

When depicting the intermediate plate 52 and the layer 48, it should be noted that the lower outer layer 4 of the intermediate plate 52 and the upper outer layer 2 of the layer 48 are fused into a common layer. The depiction is therefore similar to that between the layers 45 and 46.

Fig. 4 shows a waveform of the profiled plates, where the requirements

for an acute angle in the area of the apex lines 14 and for a flatter flank angle to reduce the plate weight by additional bend lines 39 or (shown on the left in the figure) curved areas 40 in the flanks 15 combined are fulfilled.

Fig. 5 shows a variant of the composite panel which differs from the composite panel according to Fig. 1 on the one hand by the absence of the intermediate panel 31 and on the other hand by the presence of a fold line 55 which has the property of a hinge. The fold line 55 is formed by thermoforming in which linear stamps heated above the softening point of the plastic used penetrate into the composite panel from above and below, if necessary only from one side, and approach each other at a distance of, for example, 0.5 mm, whereby the profile structures are melted down at this point and the thickness of the panels forming the layers is also reduced if necessary. With polypropylene, for example, a fold number of up to 2000 can be achieved. If individual linear stamps are brought closer to each other to a distance of zero, the composite panel is cut through at this point and a cutting line 56 is created (Fig. 6). By means of a suitable grid of such linear stamps, some of which protrude more, some of which protrude less, a pattern of folds and cut lines can be embossed into the composite panel, which allows the composite panel to be unfolded as a packaging unit such as a cardboard box or a box. Fig. 6 shows an example of such a box, in which a bending hinge strip 57 made of flexible, i.e. easily foldable, material is glued or welded along one edge in order to create a hinge line at this point. If such connections are to be detachable, they can be made, for example, by means of knotted connecting means such as knobs and recesses.

Fig. 5 shows the cardboard material as a flexible, relatively strong material, which has four profiled layers. By reducing the number of profiled layers, a lighter, even more flexible material can be created, which is particularly suitable for smaller boxes. Compared to boxes made of cardboard or corrugated cardboard, the cartons and boxes made of the composite panel according to the invention represent significantly more durable, water-resistant and puncture-resistant packaging.

Claims (17)

Protection claims 1. Multi-layer composite panel, with at least two profiled layers (26-29, 45-48) having a corrugated profile with apex lines (14) lying in one plane on each side, characterized in that the individual profiled layers (26-29, 45-48) are corrugated plastic composite layers made of a multi-layer extruded composite (1), comprising two outer layers (2, 4) and a middle layer (3) made of polymers from the same material group, in which the middle layer (3) consists of a highly crystalline polymer with built-in tensile fibers, the melting point of which is at least 15° C higher than the melting points of the polymers of the outer layers (2, 4) and the modulus of elasticity of which is at least 10% lower than the modulus of elasticity of the polymers of the outer layers, and that an intermediate plate (31, 51, 52) is inserted between at least two adjacent profiled layers, which intermediate plate is connected to the apex lines (14) of the adjacent profiled layers are welded. 2. Composite panel according to claim 1, characterized in that the intermediate plate (31, 51, 52) also consists of the multilayer extruded composite (1). 3. Multi-layer composite panel, with at least one profiled layer (26-29, 45-48) having a corrugated profile with apex lines (14) lying in one plane on each side, optionally according to claim 1 or 2, characterized in that the individual profiled layers (26-29, 45-48) are corrugated plastic composite layers made of a multi-layer extruded composite (1), comprising two outer layers (2, 4) and a middle layer (3) made of polymers from the same material group, in which the middle layer (3) consists of a highly crystalline polymer with built-in tensile fibers, the melting point of which is at least 15° C higher than the melting points of the polymers of the outer layers (2, 4) and the modulus of elasticity of which is at least 10% lower than the modulus of elasticity the polymers of the outer layers, and that at least one bend line (55) runs across the composite plate (24), in which the layers are locally melted to form a bending hinge. 4. Composite panel according to claim 3, characterized in that cutting lines (56) and/or cutouts with edges are also formed in the panel and a pattern of the folding and cutting lines (55, 56) results in a cardboard blank. 5. Composite panel according to claim 4, characterized in that detachable knotting connection means for connecting cutout edges that can be placed against one another are formed along at least part of the cutout edges. 6. Composite panel according to claim 4 or 5, characterized in that edge parts of the composite panel (24) are connected to one another by glued or welded bending hinge strips to form a tubular structure. 7. Composite panel according to one of claims 1 to 6, characterized in that the apex lines (14) of each profiled layer are parallel to one another and the apex lines of adjacent profiled layers facing one another form an angle of more than 20°, preferably a right angle. 8. Composite panel according to one of claims 1 to 7, characterized in that the polymers are polyolefins, preferably polypropylenes. 9. Composite panel according to one of claims 1 to 8, characterized in that the tensile fibers in the polymer of the middle layer are chemically coupled steel, glass or carbon fibers. 10. Composite panel according to one of claims 1 to 9, characterized in that at least one of the outer layers (2, 4) of the composite (1) consists of a " ^: 1 Compared to the middle layer, it consists of a relatively soft, easily weldable variant of the polymer. 11. Composite panel according to one of claims 1 to 10, characterized in that, in addition to the profiled layers (26-29), it has at least one flat layer (25, 30) on the outside and that this flat layer is welded to the adjacent profiled layer along the apex lines (14) on one side (at 33). 12. Composite panel according to claim 11, characterized in that the outer layer (2, 4) of the flat layer (25, 30) facing away from the profiled layer (26, 29) consists of a relatively hard, abrasion-resistant variant of the polymer with a cold resistance adjusted to lower temperatures compared to the opposite layer (4, 2). 13. Composite panel according to one of claims 1 to 12, characterized in that the wave profile is a zigzag profile and the apex lines (14) are edges parallel to one another, between which flanks (15) lie. 14. Composite panel according to claim 13, characterized in that the outer sides of the flanks (15) of the wave profile converge at an angle of inclination between 30° and 60° at the apex line (14). 15. Composite panel according to one of claims 1 to 14, characterized in that the profiled layers (26-29) have a volume filling ratio of 30% to 50%. 16. Composite panel according to one of claims 1 to 15, characterized in that it has more than two profiled layers (26, 27, 28, 29), of which at least two are welded to the intermediate plate (31) on each side thereof. 17. Composite panel according to one of claims 1 to 16, characterized in that the corrugation valleys on both sides of the profiled layer(s) are filled with foam (37).