DE3817224A1 - Sandwich panel - Google Patents

Abstract

To improve the appearance of a sandwich panel having a core of wood-based material which is arranged between two layers of plastic, at least one of the layers of plastic being formed by a polymer casting compound containing an inorganic filler, it is proposed to arrange a colouring layer on the filled layer of plastic, adjacent to the core.

Description

The invention relates to a sandwich panel with a Core of wood material, between two plastic layers is arranged, wherein at least one of Plastic layers of one of an inorganic Filler-containing Polymergießmasse is formed.  

From the prior art are such sandwich panels in the form of melamine resin or polyester resin coating teten wood panels known, the plastic layer either as a pigmented topcoat on the wood plate is applied or as a protective layer for the underlying surface of the wooden plate is used.

A big disadvantage of such sandwich panels, esp dere when using these plates as Arbeitsflä In the kitchen area, they are not are fire and impact resistant.

On the other hand, especially in the construction industry reversible moldings known, consisting essentially of Polymers of methyl methacrylate and a content of Aluminum hydroxide or alumina trihydrate or also quartz flour are formed.

These shaped bodies are fire-resistant and impact-resistant and represent high quality products that especially by their flame resistance and their high resistance to etching by acids distinguished. Such shaped bodies are for example made DE-PS 20 06 197 and from DE-PS 24 49 656 known.

These shaped bodies are, in particular, when the polymer filled with alumina trihydrate, very good ge suitable for use as a tabletop or worktop in all areas of application. The preference is  the alumina filler is given in particular then if the molding still after its completion must be edited, which is much easier here can happen as with the filled with quartz flour Polymer, with the addition of alumina trihydrate-filled polymer, a translucency occurs, which gives the molded body the appearance of marble.

Problematic with these filled plastic Formkör However, pern is that this thermal expansion have a coefficient of multiplication, many times over larger than that of wood, especially chip plates. When using these moldings together with wooden components must in the fixed connection of Shaped body and wooden part to be taken to ensure that the glue compound on a sufficient elasticity points, so that with temperature fluctuations over the Glue layer the different extent of the mate can be compensated. It was also previously only possible, the filled moldings as Plat one with the design of the production plant ge established plate width produce. wider Plates had to be assembled in expensive manual work become.

The sandwich panels described above have a wood core and a polyester applied thereon layer, which is filled with alumina trihydrate is.  

The disadvantage of these plates is their appearance, since filled with alumina trihydrate Kunststoffschich th have a translucency, which is why the substrate the layer shines through. A general pigmentation this filled layers does not help, because the Transluzenzeffekt thereby essentially canceled ben and the sandwich panel looks dull receives.

Such sandwich panels are used by consumers especially as table or worktops in the kitchen or eating area not acceptable due to their appearance advantage.

That's why the stuffed art has always been so far Preference given fabric-shaped bodies.

The object of the invention is to provide a sandwich panel of initially described type with a color effect too provided such that the plate has an improved Appearance.

This object is achieved in that on the side of the filled plastic layer, neigh beard to the core a coloring layer is arranged.

The sandwich panels with the wood material core are in the embodiment of the invention from its Ausse  hen equivalent to the known filled Plastic moldings.

In cases where the sandwich panels are a two-sided ge usable surface are both Plastic layers of one with an inorganic one Filler filled polymer formed.

In the sandwich panels according to the invention was except found that the previously discovered Pro bleme with the well-known filled plastic Formkör pern, which are provided with a wooden base, at Sandwich panels according to the invention do not exist. Despite of course still existing different thermal expansion coefficient the plastic layer and the wood core are important the sandwich panels according to the invention not to a Detachment of the plastic layers from the wood core, without that between plastic layer and wood core ver average elastic glue layer can be used would. Now, as already stated above, the sandwich panels of the invention in appearance no longer the filled plastic molded panels to stand up, this surprising result offers now a variety of ways sandwich panels with the advantageous properties of the previously known produce filled plastic molded body. in particular In particular, the determination falls on a particular plat width, because here with little additional effort Plat th of various dimensions, for example  can be made with 2 m width and 3.5 m length NEN. Due to the sandwich construction receives the manufacturer te plate an additional strength, so that the Sandwich panels according to the invention in an ideal manner are suitable, large-scale work surfaces, for example in laboratories or household kitchens form.

The flame resistance of these materials is the same as seen from the well-known filled plastic mold bodies ago is known. The impact resistance against it surprisingly takes on the known form bodies at the sandwich plate yet, so that the of the previously known filled plastic moldings Known excellent impact resistance by the Sandwich plate according to the invention even exceeded the.

The coloring layer can be either separate Layer can be applied to the core or a integral part of the filled plastic layer his. In the latter case, one can in the production the plates first a layer of casting compound with pigments apply to the core and then unpigmented casting mass over it.

Preferably, as polymers of Kunststoffschich th polyester or acrylic resins used. It is in particular the acrylic resin to give preference, as the Acrylic resin for a cheaper than the polyester and  on the other hand has better UV resistance and therefore much less prone to yellowing.

The yellowing effect can indeed with an admixture of pigments in the casting compound for the plastic layers are covered, but this is almost automatically a hard organic filler, namely Titanium dioxide as a carrier material for the dyes in the casting compound is incorporated, whereby the surface the plastic layers becomes abrasive, in particular also against metallic objects. The pros and disadvantages of different hard inorganic Fillers will be discussed below who the.

Preferably, the filled plastic layer forms at the same time the surface of the sandwich panel.

Preferably, the casting material from which the art fabric layers are produced, 20-85 weight percent filler added.

Preference is given to fillers having a Mohs hardness of 2.0 to 7.0 used. This includes in particular Quartz flour or titanium dioxide to be expected, which is the Plastic layer a very hard and scratch-resistant upper lend area.

The disadvantage of this hard filler is all However, the surface now has an abrasive effect  also shows against metallic objects, wes half of these surfaces a so-called write effect occurs, i. a shifting of metallic Objects on these surfaces leaves traces of metal debris that is difficult to remove. Another disadvantage, by the hardness of this Plastic layers is conditional, which is very bad te machinability of such surfaces, so that thus formed sandwich panels mainly recommended there where a prefabricated plate can be used, who no longer edited who must.

Far more favorable, especially in the Verwen home-use inorganic filler, whose Mohs hardness is less than 4.0. A typical one Filler that has these properties, that is Alumina trihydrate, although the plastic still strikes a hard and scratched surface gives essential resistant surface, but so soft is that it is not abrasive to metals Effect or writing effect, so that just in Household area, for example, a move from Cooking pots on the work surface no visible Leaves traces. Another advantage of the anor ganic filler alumina trihydrate over has the quartz flour fillers, is the easy machinability. With alumina trihydrate ge filled polymers can still after curing be easily edited and so when installing  slightly adapted to given spatial conditions become.

Preference is given to sandwich panels whose plastic be cured chemically. To the Aushär to be kept within reasonable limits. the casting material of the plastic layers becomes a poly merisationsbeschleuniger added, preferably from Cadmium compounds and / or amines.

For use here z. B. Cd-thioglycolate or dimethyl-p-toluidine in combination with peroxide Initiators.

The wood-based material core of the sandwich panel, which in the we considerably determined the dimensions of the sandwich panel and over its thickness, the thickness of the sandwich panel without a large cost factor can be selected preferably formed from a plywood board.

More economical is the use of a wood fiber plate, which also has the advantage of having a rela tively low specific gravity. alternative For this purpose, paper layer plates can be used the.

A likewise preferred sandwich plate has as Holzwerkstoffkern a chipboard on the insbesonde because of their mechanical properties and because of their low tendency to delay is preferred.  

Above all, chipboard with greater thickness will be forthcoming given from a core with coarse chips and surfaces layers built up with fine chips. In this way can reduce the specific gravity of the chipboard while at the same time ensuring that that the surfaces of the chipboard very smooth and without larger holes and pores are.

Although suitable for use in the manufacture Development of the sandwich panel according to the invention also formal dehyd-bonded chipboards, however, isocyanate or phenolic resin-glued chipboard preferred, in special then, if the front sides of the chipboard not covered.

Especially when the plastic layers in Be rich of a few millimeters in thickness and in the production as Holzwerkstoffkern a Chipboard is used, the strong color differences has, shimmers through the structure of the chipboard the plastic layer, which in itself is a light white having colorant through. This irregular and especially when used as a worktop in Household area unwanted coloring of the art Fabric layers is through the coloring layer covered.

As already described above, can be through appear of the wood-based substrate through pigmentation  Remove the casting compound. As in pigmentation Titanium dioxide is often used as a color carrier and since this material has a relatively high hardness, can be even in the sandwich according to the invention plates caused by the titanium dioxide particles Do not prevent writing effect. That's why it's recommended the pigmentation of the casting compound only in combination with the use of quartz powder as an inorganic filler fabric, as such sandwich panels by default one Show writing effect.

A better solution to the problem of shimmering through Structure of the wood core is the attachment of a Zwi between the wood core and the plastic layer. With the intermediate layer between wood core and Plastic layer can have various advantages be enough.

For example, the intermediate layer of a such material is responsible for the ingredients the Polymergießmasse substantially impermeable is. As constituents of the polymer casting compound for the in particular impermeability should exist Monomers and oligomers and any existing Solvent to call the casting. With the im essential impermeable interlayer is the Coating of the wood-based material core significantly unite and the quality of the sandwich panels significantly improved, in that a source of woodwork Stoffkerns by absorbing monomers and Oli  gomeren and optionally of in the casting solvent can no longer take place, so that the wood-based material core when applying the art material layers its dimensions by swelling does not change.

Furthermore, the intermediate layer as a color carrier Serve by using a pigmented material is formed, it can also be printed or durchge to be colored.

Especially easy and safe and above all for the Coloring reproducible can Zwischenschich use of a glue and a paper layer or a glue-soaked paper layer best hen.

Preference is given as intermediate layers, with or without additionally lying paper layer, melamine resin, Polyurethane or phenolic resin layers. These layers can be very easily as slides on the woodwork Apply core.

When using plastic layers of acrylic Resin should be the intermediate layer or the glue layer methylmetacrylate be.

The paper layer preferably consists of a paper with the basis weight of 70 to 150 g / m ² . When using white paper, the use of paper with a basis weight of at least 80 g / m ² is indicated, otherwise with strong differences in color of the chipboard surface is still a lucidity of these color differences through the paper layer is possible, please include, so that the plastic layer has a slightly stained appearance receives. Paper weights with a basis weight of 80 g / m ² and more are sufficient with their color coverage, so that the plastic layer applied above receives a uniform white appearance.

The use of a paper layer in between layer provides a very cost effective way Sandwich panels with different color effects and with the property of filled plastic moldings Produce without the problems with the Reproduzier availability of color, as with the filled plastic moldings is the case and especially without worrying for it must that the pigments with the remaining components harmonize with the casting compound. It also avoids in art filled with soft inorganic fillers layers of a pigment carrier such as titanium dioxide to enter, which has a writing effect on the surface the plastic layers would produce. also the translucency remains with alumina trihydrate fully preserved filled plastic layers.

The glue layer with the paper layer on the  Wood core is attached, expediently has a Thickness of 0.1 to 0.4 mm, where usually one Glue layer thickness of 0.2 to 0.3 mm is preferred.

Instead of a paper and a glue layer you can also impregnated with a binder or vorbe used paper layers alone, for example wise melamine or urethane-soaked paper.

Preferred sandwich panels have a thickness of Plastic layer of at least 1 mm. This Un tergrenze is necessary to the property of Impact resistance of the plastic layer full to the gel to bring about.

Optimal results in terms of impact resistance and also the temperature resistance of the finished sand Wichplatte be at thicknesses of the plastic layer of reached about 3 to 7 mm. Of course, too thicker plastic layers possible, but improve the mechanical and thermal properties above the specified limit is no longer material, so that a further increase in the thickness of the art is ultimately uneconomical.

Sandwich panels, used as table or countertops be used, and in which the end faces in built-in state remain visible, are preferred equipped with a molded edge from the same material is formed, from which the ge  filled plastic layer of the sandwich panel is made.

Preference is given to the molded edge of the sandwich plate designed so that the surface of the edge is continuous merges into the surface of the sandwich panel, so that no seams and bumps in the transition of the edge to the plastic layer are present.

To make this smooth stepless transition of the edge in the surface of the plastic layers of the sandwich To achieve plate, must when using quartz flour are used as a filler greatest care, because such a filled polymer is very difficult to edit. Unlike when using of alumina trihydrate, because of its softness allows processing of the finished product, so that here with much lower accuracy requirement gene can be produced.

A particularly decorative appearance receives the sand wichplatte in that the cast edge color deposed, which is the case of the sandwich according to the invention plate is very easily possible.

An edge is usually attached to the sandwich panel the front sides are molded, the built-in sand Wichplatte are visible. Is the sandwich panel for provided a table that should be free in the room, this is how the sandwich panel gets at its forehead Covered by a molded edge, so that  in this plate one completely by an art fabric surface sealed wood-based core plate is present. Such a plate is no difference to look for more to a filled plastic mold plate hen while the plate in the overall production cheaper is because the plates in the desired forma can be made and therefore expensive Nachar saved by hand.

The variations in the sandwich panels however, exist not only in terms of surface area Dimensions, also a variation in the thickness of the Plate is possible at no great cost, as only one thicker core in the production of the sandwich panel must be used. Likewise, the variation of Color of the sandwich panel opposite the filled one Plastic mold plate very simplified.

The best appearance and the best material properties th has a sandwich plate, the core as a Chipboard contains, on which a coloring paper is glued by melamine resin. The plastic layers are preferably from a Gießmas se formed, as described in DE-OS 20 06 197 in single NEN is described. The essential and for the Material properties of the sandwich plate responsli The constituents of the casting compound are methyl methacrylate monomer or a Mischpolimerisation of methylmet acrylate with alpha-beta-ethylenically unsaturated Ver compounds and alumina trihydrate as inorganic  Filler. The plastic layers have a thickness of about 4 mm, which on the one hand is sufficient to optima le mechanical and thermal properties of the sand to ensure wichplatte and on the other hand a any variation of the color effect through the paper the intermediate layer allows.

The main advantages of such a sandwich panel are:

• a) A translucency that gives the product a marmorarti looks good;
• b) the possibility of varying the color effect through the translucent, dyed or printed te paper, whereby the differences in color of the Surface of the wood-based material core itself not shine through more;
• c) no writing effect on the surface, as hard inorganic fillers, such as Ti Tandioxid can be omitted, since no pigments in the plastic layer itself can be used have to;
• d) a very low expansion coefficient of Sandwich plate, since this only the one of the Wood material corresponds, the much smaller is the one of a plate that is complete from the casting material of the plastic layer  is made; through the liability of the art material layer on the wood material core despite the different coefficients of expansion ducks of plastic layer and core temperature avoided problems, especially if hot pots on the sandwich according to the invention plate, that is, none arise Stress cracks in the plastic layer;
• e) a very high ball drop resistance, which still is better than a pure filled art Fabric mold plate (test values see detailed description environment);
• f) the possibility of relatively large plate thicknesses too realize, without causing substantial Mehrko arise because only a thicker wood material or chipboard core can be used got to; In addition, each plate width is achievable without individual plates or plate parts aneinan be launched mounted or glued have to;
• g) very high temperature resistance of the sandwich plate, which is surprisingly even better as that of a plate that is completely out made of the filled plastic material.

The sandwich panels are preferably made  that the surface has a dull appearance, what on the one hand the appearance of the slab of a marble slab approaches and to the second opposite a high luster surface greater insensitivity to Scratches caused, the high gloss surfaces very much easier to notice.

The sandwich plate according to the invention thus opens the Possibility to create surfaces that are filled Plastic articles and moldings according to DE-PS 20 06 197 correspond, but their disadvantages in avoid different uses, so that new applications for these surfaces be opened. Avoided are in particular the Problems caused by the different expansion coefficients of filled plastic moldings and Wooden substructures arise as well as in the coloring of the Surface the problems with the color fidelity, which at the pure filled plastic sheets mainly then occur when larger plate widths by Aneinan derstoßen different plate parts have arisen.

It is a further object of the invention to provide a method ren suggest, with the sand of the invention wichplatten with a wood material core between two Plastic layers can be produced, wherein at least one of the plastic layers by means of a a casting material containing an inorganic filler will be produced.  

This object is achieved in that on the side of the filled plastic layer, adjacent to the core a coloring layer is applied.

In a preferred method, the casting composition contains 20 to 85% by weight of the inorganic filler material.

Conveniently, the inorganic filler a Mohs hardness of 2.0 to 7.0.

A well-suited filler for this casting material represents quartz flour, which because of its hardness extremely robust and scratch-resistant surface of the sand wichplatte results.

However, in certain applications it is preferred Filler used that has a Mohs hardness smaller than 4.0. In particular falls into this category the filler alumina trihydrate, opposite the quartz flour is much softer and therefore kei NEN abrasive effect against metal objects generated, so that a "writing effect", as in the quartz flour-filled plastic layers occurs at avoid the aluminum oxide trihydrate-filled layers can become. This is especially true of Inter eat, if by the method according to the invention manufactured sandwich panels in the household sector, especially in the kitchen and as dining table tops Ver should find application.  

In a preferred method, as the polymer, the builds up a matrix for the inorganic filler, Polyester or acrylic resin used. The processable Both materials are excellent, each one being but acrylic resin among other things because of its better UV Stability and the lower price preferred becomes.

Preferably, the on the wood material core applied chemically cured plastic layers tet, so that the sandwich panels out in the stacking warehouse can be stored until the curing process ends is, where the stacked warehouse in contrast to thermal Curing process kept at ambient temperature can be.

It is expedient here, the casting mass Polymerisa tion accelerator, in particular Cadmium compounds and / or amines are added. In combination with peroxide starters, for example Benzoyl peroxide, in particular Cd thioglycolate or dimethyl-p-toluidine used.

As a wood-based material core, in principle, any wood-containing Plate use, depending on the application purpose of sandwich panel plywood panels, fiber plates, paper sheets or chipboards find a solution. However, preference is given to the manufacturer development of sandwich panels as worktops in kitchen  and laboratory area wood-based cores made of chipboard, the inner part of the chipboard made of coarse chips and the surface layers of the chipboard made of fine chips are already built, so that already the core of Sandwich plate on a very even surface has.

Since the hardened casting material the underground of the Plastic layers can shine through and thus the Surface usually a restless or spotty Appearance, for example, the casting material Added pigments. This is especially true in the case of Use of quartz flours or other hard anorga niche fillers be the case as these plates inherently have a writing effect. At alumi niumoxidtrihydrat-filled plastic layers is one usually of a pigmentation of the casting material refrain because the pigments are usually on the Base of titanium dioxide are built up for the Plastic layer is a hard inorganic filler represents. Such plates are added by the pigment set also an abrasive effect or Schreibef Have surface on the surface, what just by the Choice of alumina trihydrate can be prevented should.

Especially in these cases it is recommended before applying the casting compound an intermediate layer to apply to the core.  

The intermediate layer can in the process in two lei regard be exploited in an advantageous manner:

• - On the one hand, an intermediate layer can be chosen that they are responsible for the constituents of the Gießmas se, in particular the monomers and oligomers and possibly existing solvent in wesentli is impermeable, so that sources and Warping of the wood-based material core in the product tion can be avoided with certainty and
• - Second, the intermediate layer as Farbträ ger, in particular pigmented, printed or dyed through can be used.

In the latter case, therefore, the intermediate layer serves as Color carrier for the above applied plastic layer while ensuring that the color different surface of the wood core not up shines through to the surface of the plastic layer. With the possibility of pigmentation or coloring the intermediate layer is also able to aluminum oxide trihydrate-filled plastic layers to provide with a color effect, without therefore the Casting pigments must be added and removed Thus, the above-mentioned disadvantages are avoided can.

Preferably, the intermediate layer is auflami as a film ned.  

When using acrylic resin as a polymer in the Plastic layer is recommended as an intermediate layer a melamine resin, polyurethane or phenolic resin layer, all of which are methyl methacrylate-solid and one Penetration of the monomer to the core prevented.

A particularly wide range of variation with respect to Coloring and especially a particularly large Color fidelity in colored sandwich panels can thereby be achieved that one of the intermediate layer of a Glue layer and a layer of paper builds. The glue layer is again preferred in the form of a Foil applied to the core and with the paper covered layer.

The glue layer preferably has a thickness of 0.1 to 0.3 mm, usually a thickness of 0.2 to 0.3 mm for the desired properties of the glue are sufficient.

The paper layer is preferably formed by a paper having a basis weight of 70 to 150 g / m ² . Although thinner paper layers can also be used, however, these require more careful handling in the manufacture of the sandwich panels and, especially when the sandwich panel is to be white, can no longer completely cover the wood-based core underlay with its color-different surface so that the finished sandwich panel is still gets a slightly stained appearance. Paper layers from a surface weight of 80 g / m ² are also completely sufficient for the desired white color of the sandwich plate, so that paper of the quality 80 to 120 g / m ^{2 is} generally used. Thick are possible, however, provide no further advantages for the material properties.

In a preferred method, first Glue layer as a foil on the core and then the Paper layer applied to the glue layer, wherein then in a further operation, the paper layer and the size coat using pressure and higher temperatures with the wood-based core below reason.

Of course, it is also possible to have one already coated with a glue layer paper in one Operation on the core using pressure and higher temperatures by means of laminating rollers bring.

Just as well can be instead of with a glue layered paper with a condensate use paper soaked in binders, melamine or urethane being preferred as the binder becomes. In both procedures, one operation saved compared to the separate application of glue and paper layer.  

A very simple and effective method is ever but, glue the paper layer to the core using a heated platen press, Similar to the melamine resin coating of Chipboard or veneer presses is known.

The preferred temperature range for gluing the Paper layer with the core ranges from approx. 80 to 160 ° C, especially when using melamine Resin glue layers temperatures of 100 to 120 ° C are completely sufficient.

The plate presses are preferably operated in a Druckbe range of 10-25 kg / cm ² . The application of the casting material on the cores, with or without intermediate layer, can now in principle be done so that the core is taken in a casting frame, then introduced into the casting compound and evenly distributed. At the same time, however, only one side of the core can be coated with the casting compound. This method is used in particular when pigmented and unpigmented casting compound is applied in separate operations.

A much more rational method of coating the cores with the casting material is now that for applying the plastic layers to the core, optionally already with the intermediate layer is occupied, first with a flat plate, the  by spacers parallel to the core surface ge hold, a mold is formed.

Such a mold can now be used simultaneously on both Sides of the core are applied, so that in one Production step coating both sides of the core are. Preferably, the casting material is in a volume pumped in a predetermined amount in the mold, which ensures that under certain circumstances initially between the gebil through the spacers Deten bearing points slightly sagging cover plate the mold by the pressing of a predetermined Quantity casting material is raised again, so that a consistently constant layer thickness of the plastic layer is ensured.

Conveniently, the mold with the core is currency during the pumping of the casting compound against the horizon tale tilted at an acute angle. It recommends this case for the holder of the mold with the Kern to use a hydraulic table, with the one Such tilting of the mold is easy to implement.

The acute angle with which the mold against the Horizontal tilted should be about 10 to 15 ° be wear, which is sufficient to a completely uniform and Bubble-free filling of the two chambers of the mold guarantee. Conveniently, the mold is so inclined over an overhead longitudinal edge can be filled.  

Of course, in all cases where With flat plates a mold is formed which frontal edges by a circumferential frame sealed.

As plane plates are preferably melamine resin be used layered plates, which is a slight Entfor allow the mung sandwich plate without the Casting a release agent is added or the Plate pretreated with such an agent got to.

Alternatively, as a flat plate and glass plates are used, in which case hardened Glass is preferred. When the glass plates turn has the choice between a high-gloss surface the sandwich panel or, if desired is, a matte surface, in which case mattier here te glass plates are used.

The sandwich plate made with matt glass plates th have the advantage that on its surface Krat less easily visible than on the high gloss surfaces.

The spacers that par the plates of the mold allel to the core surface, are preferred in the Attached edge region of the core, in which case the introduction of a volumetrically predetermined amount  the casting material in the mold of great importance tion, since this is particularly the case for large Dimensions of the sandwich panel much more likely the Risk of sagging of the mold the plane plates results.

For introducing the casting material in the mold to be attached to the front of the core holes, the up to the surface of the woodwork to be coated fabric core are formed throughout, and by the the casting material in the otherwise sealed mold is filled. It can for each casting chamber of Casting mold, i. for each of the two plastic layers th, a separate hole may be provided so that the two sides of the wood-based material core with under different casting compounds can be coated.

The holes are preferably on one longitudinal side of the Kerns attached.

Preferably, in the holes approach pieces, In particular, plastic hoses introduced and befe which connects to a pump represents, which is the casting material in the mold into it inflated.

After completion of the curing process, the plastic layers is particularly in such Sandwichplat in which, when installed, an edge remains visible, one the end faces of the core abdec  kender edge to the sandwich plate.

If the sandwich panels in one of the above beschrie give molds for simultaneous coating of both Surfaces of the core are made, so are preferred wise before casting the edge of the Ab stand holders and, where appropriate, the sprues ends containing bores containing the sand separated wichplatte.

Preferably, the at the end faces of the wood core attached edge seamlessly to the surfaces of the sand Wichplatte poured.

This must in quartz flour-filled Kunststoffschich special care must be taken as the ses material very bad post-processing, where on the other hand, aluminum oxide trihydrate filled art less care when casting the material layers Demand Rand, because possibly occurring seams and Transfers in the transitional area of edge and art material layer removed by a Nachbearbeitungsgang can be.

Thus produced plates can thus a seamless sealing of wood-based core aufwei sen, so that they are also under very harsh Einsatzbedin under which otherwise warping of the core to would be expected to be used without problems.  

These and other advantages of the invention will be apparent in the The following explained in more detail with reference to the drawing.

They show in detail:

Fig. 1 is a perspective view of he inventive sandwich plate and

Fig. 2 is a sectional view of the sandwich plate ent long line 2-2 in Fig. 1st

The sandwich panel 10 according to the invention shown in FIG. 1 is constructed on the basis of a chipboard 12 which has a core 14 consisting of coarse chips and surface areas 16 , 17 of fine chips.

The particle board 12 can, as it is obtained, di rectly in the production process for the sandwich plate 10 are used. The chipboard 12 is coated on the sides over its entire surface with a melamine resin film 18 , which has a thickness of about 0.3 mm. On this film layer, a paper layer 20 is placed, usually paper with a basis weight of 80 to 120 g / m ^{2 is} used.

This paper can be printed or for coloring the fact fol lowing plastic layer 22 colored now, which opens up a Farbgebungsmöglichkeit for the plastic layer 22 ideally. An advantage of this Farbgebungsmöglichkeit is in particular that the plastic layer itself no pigments are added, which are usually constructed on the basis of titanium dioxide, so that as a result of Pigmentie tion of the plastic layer in these cases often adjusts a writing effect on an abrasion of metal based on the plastic surface layer.

The plastic layer 22 will generally have at least a thickness of 1 mm, preferably about 3 to 7 mm. From a layer thickness of about 3 mm, an optimum of impact resistance of the plastic layer is already reached, above 7 mm, the color will be visible only slightly by the underlying paper layer, but this is not a problem with white Shen plastic layers.

In the present example, the thickness is the art fabric layer 4 mm and leaves the color of darun The paper still has a good effect.

At the thickness of the art shown in the example Fabric layer are only large-scale color pattern visible; should detail through the plastic layer If motives remain recognizable, art must material layer can be significantly reduced and in the area from about 1 to 2 mm.

At the end face of the sandwich plate shown in Fig. 1 are two sprues 24 , 26 can be seen, which have been used to fill the mold used in the production.

In Fig. 2, the structure of such a mold is shown in more detail. The mold is composed first of the be coated with the glue film 18 and the paper layer 20 chipboard 12 , on which 28 spacers 30 are placed in their edge regions. On these spacers 30 then stored in each case a glass plate 32 made of tempered, frosted glass, which together with the particle board 12 form two chambers for a casting material to be filled for the plastic layer 22 . For larger dimensions of the sandwich plate to be produced glass plates are preferably used with a thickness of about 5 mm. The casting chambers are laterally sealed by a circulating on the front sides of the chipboard lipping or frame, which can be formed, for example, by a plate on the two surfaces of the chip surrounding frame, which also serves as a spacer 30 .

From one end side of a longitudinal side of the chipboard extending at an acute angle to the surfaces to be coated chipboard bores 34 , 36 which are formed continuously from the front side of the chipboard to the surfaces to be coated chipboard. In these holes 34 , 36 hoses 38 are glued, through which the casting mass for the plastic layer in the casting chambers 40 , 41 of the mold is filled (arrows in Fig. 2). In a finished sandwich plate 10 ver then remain the remains of the tubes 38 , which are filled with the casting compound as sprues 24 , 26 back.

In the preparation of the sandwich according to the invention for example, the procedure is as follows:

On the untreated particle board 12 , a glue layer film 18 is placed, which is covered by a paper layer 20 . The paper layer 20 is joined together with the size coat film 18 to the chipboard 12 in a heated platen press, wherein the temperature of the press when using a Mela minharz glue film with a thickness of 0.3 mm and a Papierschicht paper quality with a WING chengewicht of about 120 g / m ² at 100 to 120 ° C is maintained and a pressure is exerted by the press on the plate of about 12 to 20 kg / cm². In this heated platen press the chipboard remains for about 8 minutes.

Is used as an intermediate layer impregnated with melamine 70 g paper, it can be at a pressure of 25 kg / cm ² and a temperature of 145 ° C, the pressing time to 45 sec shorten.

The chipboard is provided in a next step on an end face with holes 24 , 26 which extend at an acute angle to the surface to be coated surfaces of the chipboard and also the glue and paper layer 18 , 20 prevail. In these holes, the connecting hoses 38 are then glued, which can be connected to the casting material pump.

The so prepared on both sides chipboard 12 is then provided on both sides with the spacers 30 , which can serve as a lateral boundary for the chamber volume of the casting chambers 40 , 41 at the same time. On these spacers 30 glass plates 32 are set up, which are held together with the chipboard 12 in a frame, not shown.

The thus completed mold is placed on a hydrau lictic, which is tilted during the introduction of the casting material into the casting chambers 40 , 41 by an amount of about 10 to 15 ° from the horizontal.

During casting, the casting material is pumped through a pump, not shown in the connecting hoses 38 and the casting chambers 40 , 41 . The casting material is in a volumetrically predetermined amount in the Gießkam chambers 40 , 41 promoted, which has the particular advantage that any deflections of the glass plates 32 are canceled by the pressing of the predetermined volume, so that there is a very uniform thickness of the plastic layers. By tilting the mold on the hydraulic table uniform filling of the casting chambers 40 , 41 , in particular while avoiding air bubbles in the chambers is achieved.

After the complete filling of the mold, the Molds lifted off the hydraulic table and into a spent simple stacking warehouse, where the plates up for complete curing of the plastic layers be stored.

Thereafter, the frame holding the glass plates 32 is detached from the mold and the two glass plates 32 are removed from the sandwich plate.

In a subsequent operation, the edge regions 28 of the sandwich panel are separated, the ter ter 30 and the sprues 24 , 26 included. This com pletted sandwich plate can now be provided in a further operation with a rim 42 who the who surrounds the front side of the particle board together with the front sides of the plastic layers 22 above and below half of the chipboard and preferably with its surface steadily and without heels in the upper surface of the plastic layers passes.

Casting compositions in which the polymer is formed by acrylic resin and the inorganic filler consists of aluminum oxide trihydrate are preferred. The content of alumina trihydrate varies from 20 to 85% by weight of the casting composition and is dependent on the later intended use of the sandwich plate 10 .

Because of the lower production costs, the plastic layers of the sandwich panel 10 are preferably chemically cured, because then the finished cast panels can be left in a simple stacking warehouse until fully permanent curing of the plastic layers, without these stacked storage would have to be particularly tempered. To accelerate the curing process of the plastic layers, the casting mass is added to a polymerization accelerator in the form of cadmium compounds or certain amines.

Table 1 shows the results of a falling ball test a sandwich plate according to the invention, the from a 34 mm thick chipboard and 3 mm thick with Alumina trihydrate filled acrylic resin layers was produced. As an intermediate layer, a 70 g Paper impregnated with melamine used.

The size of the tested plates was 2500 mm × 1300 mm; both plastic layers were simultaneity tig applied. The metal ball used had one Weight of 254 g. The ones listed in the table Findings were only possible with obliquely incident light observe, but not in a vertical Be trachtungsweise. In addition, self-added a drop height of the ball of 1200 mm no cracks in the plastic layer.  

Table 2 gives the results of a stain test such as the, wherein the indication removably with abrasive means that the stains with household shyness determine without leaving traces to be removed could. These tests were related to Table 1 defined sandwich plate use.

In addition, a test was carried out for the Temperaturbe Durability of the sandwich panels carried out:

In a hot-well test was on the above-described Sandwich plate a cook filled with 180 ° C hot oil pot turned off without leaving any traces on the plate to let. Even with a pot of 230 ° C hot oil no cracks occur in the plastic layer, single Lich when oblique view of the plate, the stand the hot pot are detected, these tracks but with a common household scourer ent are removable.

The above tests show that with the invention proper sandwich plate and in the production applied inventive method a very mechanically and thermally robust worktop erhal was also chemically against a variety of Fabric is resistant and slightly worn to be liberated.  

fall height Effect on sandwich panel 200 mm little visible impact in the form of a shiny spot 400 mm little visible impact in the form of a shiny spot 600 mm little visible impact in the form of a shiny spot 800 mm visible impact point in the form of a glossy spot with a light white yard 1000 mm visible impact point in the form of a glossy spot with a white yard 1200 mm visible impact point in the form of a glossy spot with a white yard

Table 2

Claims (32)

1. Sandwich plate with a core of wood-based material, which is arranged between two plastic layers, wherein at least one of Kunststoffschich th from an inorganic filler ent holding polymer casting compound is formed, characterized in that on the side of the filled plastic layer, adjacent to the core, a color-imparting layer is arranged. 2. Sandwich panel according to claim 1, characterized marked records that the filled plastic layer a Surface of the sandwich plate forms. 3. sandwich panel according to claim 1 or 2, characterized characterized in that the coloring layer is a Part of the filled plastic layer is. 4. sandwich panel according to claim 1 or 2, characterized characterized in that the coloring layer as  separate intermediate layer between the core and the filled plastic layer is arranged. 5. Sandwich panel according to claim 4, characterized marked draws that the intermediate layer a pigmen colored, printed or printed plastic film is. 6. sandwich panel according to claim 4, characterized draws that the intermediate layer one on the Core glued pigmented, dyed or printed paper layer. 7. Sandwich panel according to claim 6, characterized marked records that the paper layer as a glue drink tes paper is applied. 8. Sandwich panel according to claim 6, characterized marked records that the intermediate layer a glue film and a paper layer arranged above it summarizes. 9. Sandwich panel according to one or more of the An Claims 4 to 8, characterized in that the Interlayer for the components of Gießmas se, in particular monomers and oligomers and optionally solvent, essentially is impermeable. 10. Sandwich panel according to one or more of the An Proverbs 4 to 9, characterized in that the  Intermediate layer a melamine resin, polyurethane or phenolic resin layer. 11. sandwich panel according to one or more of the An Claims 4 to 10, characterized in that the Intermediate layer is methylmetacrylate-solid. 12. Sandwich panel according to one or more of claims 7 to 11, characterized in that the paper layer is formed from a paper with the WET weight of about 70 to 150 g / m ² . 13. Sandwich panel according to one or more of the An Claims 8 to 12, characterized in that the glue layer is 0.1 to 0.4 mm thick. 14. sandwich panel after one or more of the above pending claims, characterized that the thickness of the filled plastic layer at least 1 mm. 15. sandwich panel after one or more of the above pending claims, characterized that the thickness of the filled plastic layer is approx. 3 to 7 mm. 16. sandwich panel after one or more of the above pending claims, characterized that at the sandwich plate one the end faces of Kerns covering edge is cast.   17. Sandwich panel according to claim 16, characterized marked records that the surface of the cast Edge steadily into the surface of the plastic layers of sandwich panel passes. 18. sandwich panel after one or more of the before pending claims, characterized that the plastic layers on both sides of the Kerns are about the same thickness. 19. sandwich panel after one or more of the above pending claims, characterized the polymer is a polyester or an acrylic resin is. 20. Sandwich panel according to claim 19, characterized marked records that the polymer is chemically cured. 21. Sandwich panel according to claim 20, characterized marked records that for the production of the plastic layer serving casting a polymerization accelerator, in particular cadmium compounds or amines. 22. sandwich panel after one or more of the above pending claims, characterized that the casting compound 20 to 85 percent by weight anor contains ganic filler. 23. sandwich panel after one or more of the above pending claims, characterized  that the filler has a Mohs hardness of 2.0 to 7.0 having. 24. Sandwich panel according to claim 23, characterized marked characterized in that the filler essentially from Quartz flour exists. 25. Sandwich panel according to claim 23, characterized marked characterized in that the filler kleh a Mohs hardness ner than 4.0 has. 26. Sandwich panel according to claim 25, characterized marked characterized in that the filler essentially from powdered alumina trihydrate. 27. sandwich panel after one or more of the above pending claims, characterized that the core is a plywood panel. 28. sandwich panel according to one or more of the An Claims 1 to 26, characterized in that the Core is a fiberboard. 29. Sandwich panel according to one or more of the An Claims 1 to 26, characterized in that the Core is a paper layer plate. 30. Sandwich panel according to one or more of the An Claims 1 to 26, characterized in that the Core is a chipboard.   31. Sandwich panel according to claim 30, characterized marked records that the chipboard from a core with coarse chips and surface layers with fine Chips is built up. 32. sandwich panel according to claim 30 or 31, characterized characterized in that the chipboard is phenolic resin or isocyanate-glued.