EP0761135A1 - Usage of a hollow panel made of acrylic glass - Google Patents

Abstract

Furniture is made using plates of acrylic glass, contg. cavities, in place of MDF boards. Pref. the hollow cavity plates include at least two flanges (2a, 2b), forming the cavities with webs (3a, 3b), the end webs (3b) being thickened. Thickness of the flanges is pref. 2 - 6 mm and thickness of the end webs is larger than the thickness of the thickest flange. At least the parts which are visible after assembly are pref. not transparent but are coloured.

Description

The invention discloses a novel use of known twin-wall sheets made of acrylic glass.

Twin-wall sheets made of thermoplastic materials have been used in transparent versions for almost 25 years for glazing in commercial and private areas. Hollow chamber panels basically consist of two or more belt panels with vertical and / or diagonal webs in between. This structure gives the panels high rigidity with a low weight and good thermal insulation properties. Because of these properties and the high light permeability and weather resistance with good fire behavior, twin-wall sheets, preferably made of the plastics polymethyl methacrylate, polycarbonate or polyvinyl chloride, are usually used in the commercial sector, for. B. for greenhouses, industrial and sports halls, and in the private sector, for. B. for pergolas, patio roofs and conservatories.

Up to now, polyolefin hollow chamber sheets have been used as packaging material.

Hollow chamber panels are produced by extrusion using a tool corresponding to the cross-section by simultaneously forming the outer and middle layers (outer and middle straps) and the webs. After the hollow strand emerges from the extrusion die, the outer belts cooled down below the softening temperature when passing through a vacuum forming channel (calibration). The middle layers and webs remain thermoplastic longer than the outer layers. Since they are not supported, the middle layers tend to sag between the webs when extruded horizontally. This effect can be reduced if the middle layers are made very thin, because then less heat has to be dissipated below the softening temperature and if extrusion is also carried out very slowly.

The most common embodiment is the double-wall / triple-wall plate, in which the webs run at regular intervals from one another perpendicularly to the plane of the plate, so that in cross section the image of rows of rectangular chambers is arranged.

Because of the anisotropic behavior of such plates with regard to the bending stiffness, other geometries such as, for example, B. developed the so-called truss geometry.

With these geometries, the webs form an angle of approximately 45 ° with the plates, which leads to lower stresses and higher rigidity with a similar weight per unit area due to the improved transfer of transverse forces.

As a result of these requirements, additional support spacing of the load-bearing elements can be selected when installing these products, which increases the material expenditure for the Reduce the supporting structure and the time required for installation.

Multi-slanting web plates have become known for polycarbonate (EP-A-0 530 545), in which two plates arranged at a predetermined distance from one another are connected by both sloping webs and vertical webs running perpendicularly.

The fact that one part of the webs - seen in cross section - connects the upper and lower plate in a zigzag, while the other part starts at the nodes of the inclined webs with the upper or lower plate and runs perpendicular to the opposite plate, the inclined web multiple plate made of polycarbonate have a sufficient load capacity, since the buckling is shifted beyond the maximum load, which is defined so that the deflection at a load of 750 N / m ^{2 is} not more than 5%, based on the width of the plate.

EP-A 0 054 856 discloses many possible cross-sections for twin-wall sheets, in which at least some of the webs are inclined in each periodically recurring section. Figures 3e and 3f according to EP-A-0 054 856 show geometries with 3 belts each, which, however, only mature for production in the case of the embodiment according to Figure 3e.

Furthermore, there have also been attempts to achieve multi-wall sheets with increased thermal insulation with largely exclusion of light losses, among other things from the EP-A-0 286 003 a multi-wall sheet has become known which, compared to, for example, multi-wall sheets, has a k value reduced by 30% of approximately 1.8 W / m ² K. Despite the avoidance of an increase in the basis weight, the plate presented in EP-A-0 286 003 has not established itself on the market.

From EP-A-0 109 388 the use of a composite plate is known, which contains a multi-wall sheet made of plastic, in which at least two continuous plates are connected to one another by webs, the multi-wall sheet on at least one of its two sides with a hardening layer made of one of Plastic material of the multi-wall sheet is connected to different plastic, that in particular an adhesion-promoting compensating layer is provided between the multi-wall sheet and the hardening layer and that the cavities in the multi-wall sheet are optionally foamed with a plastic foam. The composite plate shown is used for the production of curved plates, especially for glass domes and. Like., Used by deformation in the heat or for the production of curved, preferably covered with textile material molded articles by deformation in the heat.

Although there are a large number of other publications which deal with the production and use of hollow chamber panels, all the areas of application which have hitherto become known have in common that they essentially relate to external roofing.

It has now been found that twin-wall sheets made of acrylic glass are excellent as a replacement for wood-based boards, especially MDF boards, suitable for furniture production. Here, hollow chamber panels made of acrylic glass can be used according to the invention both as front parts and as a body.

Today, wood-based panels, in particular the coated MDF panel (i.e. medium-density fiberboard), are used as standard in furniture and especially in kitchen furniture. The MDF board usually consists of lignocellulose fibers and a synthetic binder and has the advantage that it combines high stability with relatively easy processing. However, z. B. if you want a visible side with a high-gloss surface, the MDF board must either be high-gloss lacquered or glued with a high-gloss veneer. Other decors and surface structures are created by applying printed and / or embossed foils, usually made of PVC, or by high pressure laminated papers.

The core of the MDF board is then relatively durable due to coating or varnishing and the surface can also be scratch-resistant, but the materials required for this make the disposal or recycling of the composite body considerably more difficult, even making it almost impossible without prior separation of the components. Separation by type is, if at all possible, associated with high costs and therefore not practical. In addition, the wood-based panels, but especially the MDF panels, are usually not moisture-resistant.

A material that is known to have both surfaces of the highest gloss and one hundred percent Recyclability connects, is cast or extruded acrylic glass. There have already been attempts to use this material in the form of cast acrylic glass plates when creating furniture fronts that meet the requirement profile: "high-gloss surface and complete recyclability", but acceptance on the market has so far been rather low. Solid acrylic glass can satisfy the demands for complacency and high-gloss surface as well as for complete reusability without the dreaded effect of "downcycling", but it is very heavy and expensive in massive execution and so far mostly only for sample pieces, but not for mass production of parts suitable for the furniture industry, especially furniture fronts. In any case, the advantage of acrylic glass is that it is insensitive to moisture.

• 1. den Wunsch nach Glanz-Oberflächen zu befriedigen;
• 2. einen vollständig recyclierbaren Werkstoff bereitzustellen, und zwar ohne die Notwendigkeit vorhergehender Trennoperationen;
• 3. eine Platte zu schaffen, deren Oberfläche leicht dekorierbar ist, und zwar sowohl während der Fertigung (d. h. während der Extrusion durch Strukturierung) als auch nachträglich (Bedruckung); und
• 4. die ein relativ günstiges Gewicht bei ausreichender Stabilität aufweist.

By using hollow chamber panels made of acrylic glass as a replacement for the MDF panels, it is particularly advantageous according to the invention to

• 1. to satisfy the desire for glossy surfaces;
• 2. to provide a fully recyclable material without the need for previous separation operations;
• 3. to create a plate whose surface is easy to decorate, both during manufacture (ie during the extrusion by structuring) and subsequently (printing); and
• 4. which has a relatively favorable weight with sufficient stability.

In the context of the invention, it is fundamentally particularly advantageous that due to the presence of hollow chambers, the plates of the invention provide a significant weight saving compared to a solid embodiment, while the surface of the acrylic glass can provide the high gloss or any decor for the pleasing appearance of the entire plate .

Since webs and straps are made of acrylic glass, the component according to the invention particularly advantageously fulfills the requirement for 100% recyclability. Since a twin-wall sheet used in furniture manufacturing according to the invention depolymerizes 100% into its components under the depolymerization conditions of the acrylic glass, no effort is required in the form of separation of any components when reprocessing used sheets. Rather, the entire material can be recovered as a valuable material. After the corresponding preparation of old panels or fronts, for example by shredding or crushing in suitable mills or, if appropriate, also completely uncrushed, the hollow chamber panels used according to the invention can be subjected to a standard recycling process for acrylic glass. The acrylic glass depolymerizes and is recovered as a monomer by extraction, distillation and / or rectification without any loss of quality.

Within the scope of the invention, all hollow-chamber panel geometries known for acrylic glass can in principle be used as furniture panels. Sheets with two, three or four belts with vertical webs or inclined webs or combinations thereof can be used.

In any case, however, the use of hollow-chamber plates is preferred, which have at least two belts and webs spacing them from one another to form adjacent hollow chambers, the end webs of the edge-side chambers being reinforced. A thicker design of the terminal webs of the respective outer chambers makes it particularly advantageous to facilitate use for the production of furniture, since the thicker edges enable the shapes to be reworked. In addition, the overall impact resistance of the hollow-chamber panels that can be used as a wood-based material and, above all, MDF panel is also improved.

The thickness of the straps is generally not critical. However, the thickness should be sufficiently large, on the one hand, to ensure adequate overall stability of the hollow chamber plate, and, on the other hand, the flatness of the entire plate should be achieved. If the thickness of the straps is too small, fluctuations in the thickness, particularly in the areas of the webs, arise in the manufacturing process of the hollow chamber plate, which should be avoided if possible. Hollow chamber panels made of acrylic glass are therefore preferably used as a replacement for MDF panels in furniture manufacturing, in which the thickness of the straps is between approximately 2 and 6 mm. Is the thickness of the straps over 6 mm, the components as furniture fronts are already too heavy, while with a thickness below 2 mm, as mentioned, a u. U. insufficient stabilization of the belt thickness in the area of the webs is achieved.

The thickness or thickness of the end webs of the twin-wall sheets to be used according to the invention is preferably to be chosen in relation to the thickness of the straps such that the thickness of the end webs of the edge-side chambers of the twin-wall board is equal to or greater than the thickness of the straps, in particular as that of strongest belt. This provides sufficient material padding for the entire post-processing of the molds on the edges and edge sides, as a result of which inadvertent damage to the twin-wall sheets is avoided in particular during post-processing or during assembly.

Due to the simplicity of manufacture and the low price, twin-wall sheets with vertical webs are sufficient and particularly preferred for the use according to the invention. Furthermore, the use of a hollow chamber plate, which is designed in the form of an inclined web double plate or a truss plate, is particularly preferred.

Although the use of transparent twin-wall sheets in the furniture industry would also be conceivable, for aesthetic reasons it is by far preferred to use sheets that are not transparent but colored, at least in the parts of the sheets that are visible after assembly of the twin-wall sheets. With the series of pigments familiar to the person skilled in the art, a large number of produce aesthetically pleasing colors. These can also be combined with certain effects, such as gloss, structure, metallic, etc. In principle, all compounds available on the market and known to the person skilled in the art are suitable for coloring acrylic glass compositions.

The known hollow chamber panels made of acrylic glass are preferably used according to the invention as furniture fronts. Such fronts can be combined with all standard materials. For example, the front can consist of a hollow panel, while the body is made of wood-based panels.

However, the acrylic hollow chamber panels can just as well be used to manufacture carcasses, i.e. for the production of the solid part that makes up the actual shape of the furniture. This embodiment has the advantage of being particularly light with sufficient stability. In this case, the fronts can also be made of hollow-cell acrylic sheets, but also of a different material.

The acrylic twin-wall sheets are preferably suitable for creating pieces of furniture or entire furniture systems that consist entirely of acrylic glass. In this context, it is possible to combine with partially or completely solid sheets of cast acrylic glass. The body is expediently made of solid acrylic glass while the front or door is made of twin-wall sheet material.

For the manufacture of furniture, fronts and carcasses made of hollow chamber panels can be combined with massive acrylic glass parts or other materials can be processed in a known manner. So a front in the form of a hollow panel with any body (hollow panel made of acrylic glass, solid acrylic glass, wood-based panel, MDF board, etc.) z. B. connected by so-called hinge tapes or concealed hinges. To fasten these connecting elements, as is known from other conventional furniture materials, corresponding openings are made in a belt of the hollow chamber panel, for example by drilling or milling. It should be emphasized here in particular that the strength of the twin-wall sheets with a belt thickness of 2 to 6 mm is easily sufficient to absorb the forces occurring when using the furniture elements.

The twin-wall sheets to be used according to the invention are advantageously produced by continuous extrusion. By appropriate design of the outlet nozzle profile of the extruder used to manufacture the plate, any lattice or truss-like arrangement of the webs (stiffening intermediate walls) can be obtained which give the hollow plate profile a high section modulus not only in the longitudinal direction but also in its width with relatively little material expenditure, even with a relatively low overall profile height. You get a piece of goods with a width that can be adjusted to the requirements of the furniture industry. Would be preferred, for. B. widths which are adapted to the grid dimensions (standard width for kitchen furniture), for example about 600 mm. The web distances are generally free selectable, since the webs essentially serve as spacers between the individual belts. Particularly for use as a furniture element, web spacings are preferred which correspond approximately to the entire panel thickness.

In the following, the invention is explained in more detail using an exemplary embodiment with reference to the accompanying drawing.

The figure shows a schematic, partially broken cross section through a hollow plate profile with vertical stiffening webs.

In the figure, the reference numeral 1 denotes a hollow chamber panel to be used as a replacement for wood-based panels, preferably MDF panels, in the manufacture of furniture. The twin-wall sheet is made of acrylic glass. The cut was made transversely to the longitudinal direction of the plate 1.

The plate 1 has so-called belts 2a, 2b, which are arranged essentially plane-parallel to one another. The straps 2a, 2b are spaced apart by essentially vertical webs 3a, 3b. Belts 2a, 2b and webs 3a, 3b are integrally formed with one another. Two adjacent webs 3a, 3a or 3a, 3b each form a hollow chamber 4a, 4b with the upper belt 2a and the lower belt 2b.

The chambers 4a, 4b are arranged next to one another and parallel to one another in the longitudinal direction of the plate 1. If a chamber has only a single immediately adjacent chamber, then it is a chamber 4b on the edge. The edge-side chambers 4b are delimited by webs 3a and one end web 3b in each case. It can be seen that the The thickness of the webs 3b is greater than the thickness of the webs 3a, the thickness of the webs 3b roughly corresponding to the thickness of the belts 2a or 2b.

Claims (7)

Use of hollow chamber panels made of acrylic glass as a replacement for wood-based panels, especially MDF panels, in furniture manufacturing. Use according to claim 1,
characterized by
that the hollow chamber plates (1) have at least two belts (2a, 2b) and these spacing webs (3a, 3b), forming adjacent hollow chambers (4a, 4b), the terminal webs (3b) of the edge-side chambers (4b) being reinforced . Use according to claim 1 or 2,
characterized by
that the thickness of the straps (2a, 2b) is between 2 and 6 mm. Use according to claim 3,
characterized by
that the thickness of the terminal webs (3b) of the edge-side chambers (4b) is greater than the thickness of the strongest belt (2a, 2b). Use according to claims 1 to 4,
characterized by
that the webs (3a, 3b) of the hollow chamber plate (1) are vertical. Use according to claims 1 to 4,
characterized by
that the twin-wall sheet is a double-slanted web. Use according to claims 1 to 6,
characterized by
that at least the parts of the plate that are visible after assembly of the hollow chamber plate are not transparent but colored.

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