PRESSING TOOL DESIGNED AS A PRESS PLATEN

Abstract

The invention relates to a pressing tool for coating wood panels in hydraulic hot presses, which is designed as a press platen (1) made of a high temperature-resistant polyether ether ketone (PEEK)-type synthetic material and the surface (2) of which is structured or smooth with different degrees of gloss.

Claims

1-13. (canceled)

14: A pressing tool for coating wood panels in hydraulic hot presses, which is designed as a press platen (1) made of a high temperature-resistant synthetic material of the polyether ether ketone (PEEK)-type and the surface (2) of which is structured or smooth with different degrees of gloss, wherein the press platen (1) made of polyether ether ketone PEEK is reinforced with at least 10% to 50% of a carbon fiber or with at least 10% to 50% of a graphite powder or with at least 10% to 50% of a thermally conductive material.

15: The pressing tool according to claim 14, wherein the press platen (1) is made of a polyimide (PI).

16: The pressing tool according to claim 14, wherein the press platen (1) is made of a polyamide imide (PAI).

17: The pressing tool according to claim 14, wherein the press platen (1) is made of a polyether ketone (PEK).

18: The pressing tool according to claim 14, wherein the press platen (1) is made of a polyether ketone ether ketone ketone (PEKEKK).

19: The pressing tool according to claim 14, wherein the press platen (1) is made of a polyphenylene sulfide (PPS).

20: The pressing tool according to claim 14, wherein the press platen (1) is made of a polyarylether ketone (PAEK).

21: The pressing tool according to claim 14, wherein the press platen (1) is made of a polybenzimidazole (PBI).

22: The pressing tool according to claim 14, wherein the press platen (1) is made of a liquid crystal polymer (LCP).

23: The pressing tool according to claim 14, wherein the structuring of the surface (2) of the press platen (1) is produced by a die pressing process.

24: The pressing tool according to claim 14, wherein the structuring of the surface (2) of the press platen (1) is produced by a fused deposition modeling method (FDM).

25: The pressing tool according to claim 14, wherein the structuring of the surface (2) of the press platen (1) is produced by means of a CO.sub.2 laser (3) and digitized data of a 3-D topography of a previously removed structure corresponding to the structuring of the surface (2) is used for a controller of X-, Y- and Z-coordinates of the CO.sub.2 laser (3).

Description

[0006] The objective of the invention is achieved by a pressing tool for coating wood panels in hydraulic hot presses that is designed as a press platen made from a high temperature-resistant polyether ether ketone (PEEK)-type synthetic material and the surface of which is structured or smooth with different degrees of gloss. The objective of the invention is achieved in particular by a pressing tool designed as a press platen for coating wood panels in hydraulic hot presses, the surface of which is structured or smooth with different degrees of gloss, and the press platen is made from a high temperature-resistant polyether ether ketone (PEEK)-type synthetic material, the softening point of which lies above the processing temperature of the press machines.

[0007] Polyether ether ketones are relatively light and more practical in terms of handling, and more processes are available for the structuring operation which are less damaging to health and more reliable in terms of processing, and the negative properties of metal press platens can therefore be eliminated. Surprisingly, PEEK sheets have exhibited a high strength in spite of a significantly lower density of 1.31 kg/dm.sup.3 and PEEK containing 30% CA of 1.41 kg/dm.sup.3. A steel sheet conforming to a quality specified by DIN 1.4542 or AISI 630 has a density of 7.8 kg/dm.sup.3. This means that a press platen of the format 6200?2400 mm with a 5 mm thickness has a total weight of ca. 580 kg whereas a PEEK sheet of the same size weighs only 97 kg and a PEEK sheet containing 30% CA weighs 105 kg. The steel sheet is therefore almost 6 times heavier than a synthetic material sheet. Synthetic material sheets can therefore be more easily mechanically secured in the press machine and do not cause the problems described above which can occur when using metal press platens. However, it is also possible to secure synthetic material sheets in the press machine directly by means of the press pads using a chemical mechanism. Due to the lower degree of sagging of the sheets and the advantageous friction factor, the press pads, especially their metal threads, are protected from abrasion, thereby extending the service life of the pads. Different production processes are available for structuring the surfaces of synthetic material sheets. Since they do not involve treatment using etching media, for example FeCl.sub.3, the methods are more environmentally friendly and not harmful to health. One type of structuring is fused deposition modeling, FDM, also known as fused filament fabrication, FFF. In the fused deposition method, similarly to a normal printer, a pattern of dots is firstly applied to a surface, the dots being formed by liquefying a filamentous synthetic material by heating, applying it by extrusion by means of a nozzle, followed by setting by cooling in the desired position to create a pattern in the working plane. The structure is usually built up by repeatedly passing line by line across a working plane and then shifting the working plane upwards in a stacking arrangement so that a structure is created in layers. Depending on the desired structure depth, the layer thicknesses are between 25 and 1250 ?m. Data transmission is handled by means of CAD technology.

[0008] The press platen may be made of polyether ether ketone PEEK reinforced with at least 10 to 50% of a carbon fiber or with at least 10 to 50% of a graphite powder or with at least 10 to 50% of a thermally conductive material.

[0009] The press platen may be made of a polyimide PI, a polyamide imide PAI, a polyether ketone PEK, a polyether ketone ether ketone ketone PEKEKK, a polyphenylene sulfide PPS, a polyarylether ketone PAEK, a polybenzimidazole PBI or a liquid crystal polymer LCP.

[0010] Laser technology offers another technology for producing structure. By contrast with producing press platens using metal, a CO.sub.2 laser may be used when working with PEEK sheets which requires substantially higher ablation times than is the case when removing a metal. In the case of the metal sheet produced as specified by EP 2 289 708 B1, it is proposed that the structuring be produced by means of a laser, and the laser is a pulsed fiber laser. In practice, however, it has been found that the removal rate of the pulsed fiber laser is very low. In the case of the CO.sub.2 laser, as with every laser, a so-called active laser medium, in this case carbon dioxide CO.sub.2, is pumped by feeding in external energy. In the medium itself, atomic processes then take place which ultimately case a chain reaction using a complex apparatus and hence the emission of laser light. The CO.sub.2 laser is also referred to as a gas laser. A gas laser can much more easily produce a larger volume of active laser material than a solid-state laser, for example because the container used for this purposes merely has to be of sufficiently large dimensions and accordingly allows an inflow of a large amount of gas. The volume has a direct bearing on the intensity of the lasers that can be obtained and greater power ratings can therefore also be achieved as a result. The CO.sub.2 laser has a long wavelength and is therefore readily absorbed by synthetic materials, whereas metal surfaces are highly reflective and removal is therefore lower. A power of 200 to 300 Watt is already sufficient to obtain good removal rates in the case of synthetic materials. By setting up digitized data of a 3-D topography of a structure removed beforehand, the laser is controlled in an x-coordinate and a y-coordinate and the depth is determined by the z-coordinate of the 3-D topography perpendicular to the surface structure.

[0011] Another option for producing structure is die pressing. By contrast with metals, structures can be produced in synthetic materials due to the effect of temperature and pressure. A negative structure serving as the prototype is produced in a steel sheet first of all. This prototype serves as a means of imparting structure to all the other synthetic material press platens. Subjected to pressure and a temperature below the melting point of the synthetic material but still above the softening point, the negative structure is embossed in the synthetic material sheet and thus receives a positive structure. The product being pressed is cooled under pressure and to just below the softening point of the synthetic material used and the pressed product is then removed.

[0012] Reproducible structures can be produced by these methods. By contrast with the structures produced in metal press platens by the chemical etching process, these structures are all identical and exhibit no deviations. In this manner, a structure production process is possible which is reliable in terms of processing and poses no risk to health. After structuring, the sheet surfaces can also be additionally processed in the same way as metal press platens. The degree of gloss is set by means of radiation media at a specific radiation pressure, depending on the desired degree of gloss. To protect the surfaces, the synthetic material sheets may also be chromed but it is recommendable to apply a Cu-layer. This may be achieved by a reductive copper plating for synthetic materials for example, or by an electroless process of copper plating of synthetic materials using Baymetec and Baycoflex. After copper plating, the usual chrome plating can be applied in galvanic baths. Tests have demonstrated that not every synthetic material is suitable for use as press platens in hydraulic hot presses for coating synthetic materials. The softening point of the synthetic materials must be far above the processing temperature prevailing in the hot presses. As a rule, this is between 190 and 220? C. The polyether ether ketone (PEEK)-type synthetic material reinforced with ca. 30% carbon fiber or with graphite has been found to be surprisingly good for producing press platens. Although synthetic materials have a poorer thermal conductivity than metals, it was possible to largely compensate for these differences by adding a carbon fiber or by graphite powder. Furthermore, due to their lightness, it was possible to secure the synthetic material sheets more effectively and tightly to the heating plates so that the heat loss which occurs in the case of metal press platens due to their high degree of sagging did not occur in this instance. These advantages also compensate for the different thermal conductivities.

[0013] The different degrees of gloss can also be obtained by different coatings of the surface of the press platen made of a high temperature-resistant synthetic material of the polyether ether ketone type, as described in EP 2 060 658 B1.

[0014] An example of an embodiment of the invention is illustrated in the appended schematic drawing, which illustrates a pressing tool designed as a press platen 1.

[0015] The press platen 1 is made from a high temperature-resistant polyether ether ketone synthetic material and comprises a surface 2 which is structured or smooth with different degrees of gloss.

[0016] In the case of this example of an embodiment, the press platen 1 is reinforced with at least 10 to 50% of a carbon fiber or with at least 10 to 50% of a graphite powder or with at least 10 to 50% of a thermally conductive material.

[0017] The press platen 1 may be made of a polyimide, a polyamide imide, a polyether ketone, a polyether ketone ether ketone ketone, a polyphenylene sulfide, a polyarylether ketone, a polybenzimidazole or a liquid crystal polymer LCP for example.

[0018] In the case of this example of an embodiment, the structuring of the surface 2 of the press platen 1 was produced by means of a CO.sub.2 laser 3. In particular, digitized data of a 3-D topography of a previously removed structure corresponding to the structuring of the surface 2 was used for a controller of X-, Y- and Z-coordinates of the CO.sub.2 laser 3.

[0019] The structuring of the surface 2 of the press platen 3 may also be obtained by means of a die pressing process or by the fused deposition modeling method.