WO2024068232A1

WO2024068232A1 - Pressing tool with a nickel layer

Info

Publication number: WO2024068232A1
Application number: PCT/EP2023/074656
Authority: WO
Inventors: Berthold Thölen
Original assignee: Hueck Rheinische Gmbh
Priority date: 2022-09-30
Filing date: 2023-09-07
Publication date: 2024-04-04
Also published as: DE102022125373B4; DE102022125373A1

Abstract

The invention relates to a pressing tool (1) designed for pressing sheets of material in heating presses and comprising: - a substrate (2) made up of a metal pressing sheet or a continuous strip; - a surface structure (3) for embossing a surface; - a surface coating (4); wherein the surface coating (4) is formed by means of a layer (5) of nickel or a nickel alloy and has a uniform layer thickness (6). The invention also relates to a method for treating a surface of a pressing tool.

Description

Press tool with a nickel layer

The invention relates to pressing tools for pressing material panels in heating presses, comprising:

- a substrate made of a pressed sheet or an endless belt;

- a surface structure for embossing a surface;

- a surface coating.

The invention further relates to a method for treating a surface of a pressing tool.

Material panels, for example wood-based panels, are required for the furniture industry and for interior design, for example for laminate floors. The material panels have a core made of MDF (medium density fiberboard) or HDF (high density fiberboard), onto which core various material layers are placed at least on one side, for example an (optical) decorative layer and a protective layer (overlay layer).

In order to avoid warping in the material panels produced, such material panels are usually provided with the same number of material layers on both sides; in order to connect the individual layers of the material panels (core, material layers, etc.) to one another, they are pressed together in a press using special pressing tools, in particular press plates or endless belts (or rollers). The surface of the material panels is also embossed in the process. Hot presses are usually used to connect the various material layers made of thermosetting resins, for example melamine resin, to the surface of the core under the influence of heat by fusing the plastic materials.

The decorative layers determine the pattern and color design of the material panels; a desired surface structure can be achieved by using suitable pressing tools. For example, a Wood or tile decor can be printed on the decorative layer (decorative paper), or decorative layers with patterns and color schemes can be used that are artistically designed according to the respective intended use. Overlay layers can also be used that are printed on the top or bottom.

To improve a lifelike reproduction, especially for material panels with wood, tile or natural stone decor, the pressing tools are provided with a surface structure that conforms to the decorative layer and forms a negative image of the desired surface structure. The pressing tools therefore have a 3D profile (depth structuring) that is modeled on the wood veins of a wooden surface, for example, in order to give the decorative layer of the material panel the appearance of such a wooden surface.

To further improve a lifelike reproduction, especially of wood, tile or natural stone surfaces, pressing tools are used that also have certain levels of gloss or mattness. By setting a certain level of gloss or mattness in a selected surface area of the pressing tool, it is possible to create any reflections or shades in the material plate that give the viewer the impression of a natural wood, tile or natural stone surface of other materials, for example.

In order to achieve the embossing of the material plates in accordance with the coverage - i.e. the required accuracy of fit of the decorative layer(s) and the surface structure of the material plate - a high quality standard is required for the production of the pressing tools. In particular, the pressing plates or endless belts are used as upper and lower tools in short-cycle presses, which are covered with pressing plates, or in double-belt presses with endless belts, whereby the embossing and heating of the material plates takes place at the same time, so that the thermosetting resins of the decorative and/or overlay layers of the material plates are first melted, the surface structure corresponding to the surface structuring of the pressing tools is introduced into the external material layers, and the structured material layers are bonded to the core of the material plate by subsequent curing.

In order to produce the desired surface structuring in or on the pressing tools, digitized image data of a decorative template can be used to apply an etching resist for structuring the pressed sheets or endless belts. For this purpose, an etching resist is applied to the pressed sheets or endless belts, for example using a digital printer, in order to then carry out an etching process. After removing the etching resist, further processing of the pressing tool can be carried out, preferably in the case of surface structures with particularly deep/high structures, several etching processes can be carried out one after the other. For this purpose, an etching resist is applied to the already etched pressed sheet or endless strip and etching is carried out again until the desired deep structure has been produced. In the individual etching processes, a rough or fine structuring of the surface structuring can also be carried out, depending on which surface structure is to be given to the material plate.

As an alternative or in addition to the described etching processes or other material-removing processing processes, material-applying processes can also be used to produce the surface structure (layer by layer) on the surface of the pressing tools. Most of these processes use masks (masking) to protect the surface of the pressing tool from subsequent material application or removal. By repeatedly applying appropriate masks and then applying or removing material, surface structures of various designs can be produced.

Regardless of the process chosen, a surface structure is ultimately created on the pressing tool, which represents the negative of the surface structure to be embossed into the material plate. Raised areas in the surface structure correspond to the depressions to be embossed in the surface structure of the material plate, or depressions in the Surface structuring the elevations which the surface structure of the material plate should have.

WO 2009/062488 A2 discloses a press plate with a structured press surface. The structured press surface comprises a structure that has a mountain-like surface with valleys and peaks. Using the press surface, a workpiece designed as a material plate with a structured surface can be produced. The structured press surface comprises a full-surface chrome layer that lies against the material plate during pressing. The structured press surface is produced by deep etching.

WO 2008/120058 A1 discloses a pressing tool whose pressing surface is formed by a layer which consists of a metal matrix with mineral or ceramic particles embedded therein.

Furthermore, additional surface coatings are provided on the pressing tools, which serve to improve the properties of the tool in the pressing process, in terms of chemical resistance, wear resistance and its hardness. These are often provided to ensure uniform properties of the pressing tool for the pressing process itself.

A disadvantage of state-of-the-art pressing tools is that, due to the surfaces produced and the protective coatings applied to them, they often exhibit undesirable distortions or tolerance deviations in the structure or relief to be embossed, which results in qualitative losses in the material plates, particularly with regard to their appearance.

The object of the present invention was to overcome the disadvantages of the prior art and to provide a pressing tool and a method for processing a pressing tool, by means of which a user is able to avoid unintentional deviations from the desired surface contour and yet to be able to meet the mechanical and chemical requirements for protective or surface coatings. This task is solved by a device and a method according to the claims.

The pressing tool according to the invention is characterized in that the surface coating is formed by a layer of nickel or a nickel alloy and has a uniform or constant layer thickness.

By means of the measure according to the invention, on the one hand, a particularly contour-true tool surface can be obtained and at the same time the necessary properties with regard to the requirements for corrosion protection or chemical resistance, as well as the required surface hardness, can be met. Depending on the design of the surface of the substrate located directly under the layer, its optical properties can be reproduced directly, for example a matt impression with a certain mattness. In particular, the use of a layer of chemical nickel has proven to be particularly advantageous. Chemical nickel is a layer obtained using a deposition method that was deposited without the use of an external electric current.

A further advantage of the invention is that it is possible to provide a chromium-free pressing tool and a chromium-free process for producing such a pressing tool, since chromium is increasingly being avoided entirely in applications due to its environmentally and health-damaging properties.

In one embodiment, it can be provided that the layer has evenly distributed pores, which can be introduced, for example, in a coating process. By means of this measure, a matte structure can be provided using simple methods without requiring additional forming steps for the coating.

It can also be advantageous if the pores have an average pore diameter of 0.1 pm to 1 pm, in particular 0.1 pm to 0.5 pm. This measure can produce a particularly matt impression on a material plate. In an advantageous embodiment, the layer can have a pore content of at least 100 pores/cm ² .

In addition, it can be provided that the layer has a phosphorus content of 1-13%. By means of these measures, improved hardness and chemical resistance of the layer can be achieved, with higher hardness being achievable with lower phosphorus contents, and better chemical resistance being achievable with higher phosphorus contents.

In addition, the layer can have a thickness of 2-50 pm, in particular 5 to 25 pm. Thin layers have the advantage that targeted pores can be created more easily. With thicker layers, improved wear and corrosion resistance can be achieved.

In order to increase the wear resistance of the pressing surface, mineral particles can be embedded in the layer of the pressing tool. The mineral particles of the metal layers in particular have a Mohs hardness of at least 8.

They preferably have a size in the nanometer or micrometer range, e.g. 0.1 pm to 5 pm. This allows the mineral particles to be embedded relatively homogeneously in the metal layers, giving the pressing tool a relatively homogeneous wear resistance over its entire pressing surface. The size of the individual mineral particles can be different or essentially the same.

The mineral particles preferably have a volume fraction of at least 20% - 80%, in particular 50% - 70%, based on the volume of the layer with mineral particles embedded therein. Based on the size, the volume fraction and the type of minerals of the mineral particles, the desired degree of hardness or wear resistance of the layer can be adjusted.

The mineral particles include in particular diamond particles. The diamond particles are preferably industrial diamond particles, ie the diamond or generally the mineral particles can be artificially produced. However, in particular the minerals silicon carbide, boron nitride, boron carbide, aluminum oxide and titanium oxide are suitable as Mineral particles can also be used. The mineral particles can also preferably be in the form of mineral powder, in particular diamond powder and preferably industrial diamond powder. The particles can preferably have a size of 0.5 pm to 1 pm, depending on the layer thickness.

In one embodiment, it can be provided that the layer is a partial layer. The partial layer can preferably be provided in those areas of the surface that have elevations. This refers to those elevations that primarily come into contact with a workpiece in a pressing process.

The partial layer can also have a different degree of gloss compared to the surface underneath.

Particularly preferably, the layer can also be a hardened layer, preferably with a Vickers hardness of 700 to 1100 HV. At this point, it should be mentioned that the hardness can also exceed this, depending on the processes used to produce the layers.

In a further measure, it can be provided that the substrate has a blasted surface on which surface the layer is arranged. By means of a blasted surface, an improved adhesion of the layer can be achieved, as well as a matting.

Furthermore, a method according to the invention for treating a surface of a pressing tool is characterized in that the surface coating is applied in a coating process using a layer of nickel or a nickel alloy with a uniform layer thickness. This measure ensures a uniform coating to maintain the surface structure.

In a particularly advantageous embodiment, it can be provided that the layer is applied in an electrolyte without external current during the coating process. This measure makes it possible to achieve a contour-accurate coating and to control the layer thickness during the coating process. Electroless processes are electroplating applications in which coating is carried out without an external circuit. This process technology enables a particularly uniform layer thickness to be achieved. Another advantage of this method is that even large-area pressing tools with severe unevenness can be used to apply uniform layers, as the chemical nickel is deposited evenly, especially in the areas that have not yet been coated.

In this regard, a substrate material which is less noble than a metal to be deposited by means of an electrolyte can, for example, be introduced into said electrolyte by means of reduction deposition and coated by means of the metal from the electrolyte.

It can be advantageous if the pH value of the electrolyte is monitored and regulated. By controlling the pH value, the coating can be optimally regulated.

In addition, it can be provided that an acid content of the electrolyte is adjusted. The speed of the separation process can be determined by regulating the acid content.

In one embodiment, it can be provided that pores which have a desired pore property are introduced in the layer in a uniformly distributed manner by using a pore adjustment process. Using this measure, matting can be carried out using particularly simple means, since the matting can be adjusted using the pore properties. The pore adjustment process preferably includes a method for actively influencing the pores during coating.

A possible embodiment provides that the pore properties of the pores in the pore adjustment process are maintained by ending the coating process early. With this measure, an even distribution of the pores can be achieved, as well as a particularly economical method for producing the pores. Furthermore, it can be provided that the pore properties of the pores in the pore adjustment process are maintained by regulating a nickel concentration of the electrolyte. For example, deposition can also be controlled by reducing the nickel concentration in the electrolyte.

Furthermore, it can be provided that phosphorus is introduced into the layer in a proportion of 1-13% during the coating process.

Hypophosphite (H2PO2), for example, can be used to produce nickel layers with phosphorus content. In this regard, it is advantageous to measure the pH value during the coating process in order to be able to better control the phosphorus content.

It can be advantageous for a surface of the substrate to be blasted before the coating process.

Furthermore, it can be provided that the surface coating is partially applied by masking at least one area of a surface of the substrate, thereby obtaining a partial layer. By means of this measure, different impressions can be produced on a material plate to be pressed.

Furthermore, it can be provided that the masking is carried out by passivation of at least one area of the surface of the substrate. This measure makes it possible to achieve simple masking for a (chemical) coating process. In principle, chromium is suitable for passivation. However, as is known from the prior art, aluminum, nickel, titanium, lead, zinc and silicon are also suitable as alternatives to avoid passivation.

In the case of aluminum, for example, an anodized layer can be provided for masking.

In a preferred embodiment, it can be provided that mineral particles are introduced into the layer. This is preferably done in the coating process. In an advantageous application, the layer can be heat treated after the coating process. Heat treatment can be used to achieve improved adhesion properties of the surface coating, as well as to increase hardness and wear resistance.

It can be provided that the layer is hardened at a temperature of 250°C to 500°C. With tempering at these temperature ranges, Vickers hardnesses of up to 1100 HV can be achieved.

Furthermore, it can be provided that the pores are subsequently treated by means of heat treatment, since thermal expansion and relaxation of the material in the area of the pores, in the direction of the pores, is used to influence the pore size. This makes it possible to subsequently change the pores by means of heat input, by using the lower resistance of the material of the layer in the area of the pores.

For a better understanding of the invention, it is explained in more detail with reference to the following figures.

They show in a highly simplified, schematic representation:

Fig. 1 A diagrammatic representation of a pressing tool;

2 shows a substrate with a surface coating according to the invention;

Fig. 3 is a plan view of an embodiment of a surface coating;

Fig. 4 a coating process for producing a surface coating;

Fig. 5 shows an embodiment of a layer according to the invention with mineral particles

Fig. 6 shows a possible manufacturing process for a partial layer.

By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or identical component designations, whereby the disclosures contained in the entire description refer analogously to identical parts with identical reference symbols. or the same component designations can be transferred. The position information chosen in the description, such as top, bottom, side, etc., also refers to the figure directly described and shown, and these position information must be transferred to the new position accordingly if the position changes.

1 shows a pressing tool 1 with a substrate 2 and a surface structure 3 attached thereto, which transfers the structure to the workpiece when pressing a workpiece with the pressing tool 11, for example in a heating press. This allows the structure, which corresponds to the grain of a wood, for example, to be transferred to the workpiece, giving the workpiece a wooden look.

In order to produce this surface structure 3 on the pressing tool 11, the pressing tool 1, which can be, for example, a pressed sheet or an endless belt, is processed. This processing can be carried out by any one of sandblasting, chemical treatment, pressing, embossing, etching, polishing, laser processing, grinding, milling and application of coatings, or a combination of several of these.

2 shows a possible embodiment of a surface structure 3 on a substrate 2, which is provided with a surface coating 4 according to the invention, comprising a layer 5 made of nickel or nickel alloy with a uniform layer thickness 6. The layer 5 preferably has a layer thickness 6 of 2 -50 pm, especially 5 to 25 pm.

As mentioned at the beginning, contour-accurate embossing can be ensured by means of the uniform layer thickness 6, since the surface structure 3 formed on the substrate 2 is retained in the layer 5 by the uniform layer thickness 6.

As shown, the surface structure 3 itself can have a different and multi-part layer structure, with different layers 13. Furthermore, the surface structure 3 can also only be formed by means of a further layer 13 or can only be formed in the substrate 2. To produce the surface structure 3, use the possible methods mentioned at the beginning and Applications noted. The surface structure 3 can be designed as a fine or coarse structure and, as shown, form different valleys and elevations and be formed into different layers 13 or penetrate them.

As mentioned at the beginning, the nickel layer 5 according to the invention can preferably be made from chemical nickel, which ensures a particularly contour-true design corresponding to the surface structure 3, as well as a consistently uniform layer thickness 6.

Furthermore, the substrate 2 can have a blasted surface 9, on which surface 9 the layer 5 is arranged. As mentioned at the beginning, the adhesive properties of the layer 5 can be improved, but a special mattness can also be achieved for the optics of the pressing tool to be transferred.

3 shows a top view of an embodiment of a surface coating 4 with a layer 5 according to the invention.

The layer 5 preferably has evenly distributed pores 7. By means of the pores 7, a matt surface can be produced on a material plate, as mentioned at the beginning. It is advantageous if the pores 7 have an average pore diameter 8 of 0.1 pm to 1 pm, in particular 0.1 pm to 0.5 pm, in order to achieve a desired matt appearance. The pores 7 can penetrate the layer 5 to the surface underneath, or can only penetrate into the layer 5.

The pores can be created, for example, by controlling a coating process, which will be discussed in more detail below.

For completeness, it should be mentioned that the layer 5 with the pores 7 is shown roughly schematically and is not limited to the conditions shown.

Fig. 4 schematically shows a method for treating a surface 9 of a pressing tool, wherein a surface coating 4 is applied to a substrate 2. The surface coating 4 is applied in a coating process 10 by means of a layer 5 made of nickel or a nickel alloy with a uniform layer thickness.

As mentioned at the beginning, the layer 5 can preferably be deposited in an electrolyte 11 without external current. The electrons required to separate or reduce the nickel ions by means of a redox reaction are generated in the bath itself. The substrate 2 or the pressing tool acts as a heterogeneous catalyst.

The reducing agent is oxidized on the surface 9 of the substrate 2 to be coated and thus releases electrons. The released electrons reduce the metal ions on the surface 9 of the substrate 2 to metal atoms, which are deposited on the surface 9 as a metal layer, in the application of the invention as a nickel layer 5.

If the concentration of metal ions in the electrolyte solution is low, the redox reaction occurs very slowly because only a proportion of metal ions and reducing agent leads to an exchange of electrons. At higher concentrations of metal ions, the redox reaction occurs much faster. The coating process can therefore also be controlled via the concentration.

Hypophosphite (H2PO2-) can be used to introduce phosphorus or to achieve a phosphorus content, for example in the range of 1-13%. Nickel sulfate, for example, can be used as an electrolyte.

By oxidation of the hypophosphite the electrons are released according to the following reaction equation.

[H2PO2]- + H2O -> [H2PO3]- + 2H ⁺ + 2e-

The reduction takes place according to: Ni ²⁺ + 2e ^_ -> Ni

Thus, due to the following overall reaction;

[H2PO2]- + H2O + Ni ²⁺ -> Ni + [H2PO3]- + 2H ⁺ The pH value influences the reaction rate, whereby an increased acid content of the electrolyte slows down the deposition of nickel. The deposition of phosphorus, on the other hand, is accelerated with a higher acid content.

It may be useful if the pH value of the electrolyte 11 is monitored and regulated in order to ensure constant deposition conditions. In this regard, a pH measurement can be provided in the coating process 10. Furthermore, an acid content of the electrolyte 11 can be set in order to specifically achieve and control the phosphorus content.

Preferably, a central control device 14 is provided which monitors and regulates the process parameters and can optionally operate dosing devices (not shown). For example, it can be provided that the Ni concentration of the electrolyte is regulated by means of additional dosing of Ni-poor or Ni-rich electrolytes.

Furthermore, and independently of this, the aforementioned evenly distributed pores can be introduced into the layer 5, which pores have a desired pore property by using a pore adjustment process. As also already mentioned, these can be used to produce a matte structure of the pressing tool. In one possible embodiment, the pores or the pore property can be obtained by prematurely ending the coating process 10, whereby the layer 5 is incompletely deposited and a pore size and distribution is established depending on the time of termination.

Furthermore, the pores or the pore property can be obtained by depleting the electrolyte 11 of nickel by controlling the nickel concentration of the electrolyte 11.

Alternatively or additionally, to produce the matt structure, the surface 9 of the substrate 2 can be blasted before the coating process 10, for example by means of sandblasting.

In addition, it can be provided that the layer 5 is not deposited on the entire surface 9 of the substrate 2 by at least one area 12 the surface 9 is masked. For example, a coating or a paint finish can be applied in this area 12 before the coating process 10. Furthermore, it is possible to passivate the surface 9 in the area 12.

After the coating process 10, the pressing tool or the layer 5 can be subjected to a heat treatment. As mentioned at the beginning, the wear resistance and hardness of the layer 5 can be further increased by means of a heat treatment. In addition, better adhesion properties of the layer 5 to the surface 9 can be achieved.

To improve the adhesion properties on the base material, a heat treatment in the range of 150 to 250°C can be carried out, in a range of 1 to approx. 4 hours.

The heat treatment or tempering for hardening is preferably carried out in a range of over 250°C to 500°C, depending on the duration or treatment time, which can preferably be between 0.5 and 4 hours.

For example, by tempering at around 400°C for just 60 minutes, a Vickers hardness of over 800 to 1100 can be achieved. An untreated nickel layer usually has a hardness of up to max. 500 HV.

Depending on the use of mineral particles or Ni/P layers, the hardness can of course be increased even further

Furthermore, it can be provided that the pores are subsequently treated by means of a heat treatment, since a thermal expansion of the material and a relaxation of the material in the area of the pores, in the direction of the pores, is used to influence the pore size.

5 shows a possible development of a layer 5 according to the invention, in which mineral particles are embedded in the layer 5.

The mineral particles 15 are preferably introduced in the coating process. As is also indicated by dashed lines, further layers 13 of the substrate 2 can be provided, which preferably consist of metal layers. The additional layers 13 can also have mineral particles 15. For example, individual layers can be produced using different coating processes, whereby mineral particles 15 can optionally be introduced into the respective layers in the coating process. The mineral particles of the additional layers 13 can also differ from those mineral particles 15 of the nickel layer.

Alternatively, to introduce the mineral particles 15 into the layer 5, it can be provided that they are applied to the surface 9 of the substrate 2 before the coating process, for example with an adhesive, and then the layer 5 is applied. In this way, a targeted introduction of the particles can be provided in certain areas of the layer 5, for example only in the elevations. The layer preferably has a layer thickness selected for the particle size.

6 shows a possible embodiment for producing a layer 5 according to the invention, the layer being a partial layer and thus having recesses 19. The recesses 19 of the layer can be produced by means of masks 18, which are arranged on the surface 9 of the substrate 2 in order to partially mask them.

The masks 18 can preferably be arranged in the depressions 16 of the surface structure 3, so that the partial layer 5 is deposited on the elevations 17 of the surface structure 3. The partial layer can in turn have mineral particles 15, as is also indicated.

During the production of a workpiece, the pressing surface is in contact with the workpiece and is therefore subject to wear. This wear is particularly pronounced in the areas of the elevations, at least preferably in the area of certain elevations, which is why the mineral particles are preferably embedded in the partial layer. This increases the wear resistance of the partial layer and thus the wear resistance of the pressing surface at least in the predetermined areas and thus preferably at least in the areas associated with the elevations or certain elevations of the pressing surface. Furthermore, it can be provided that in a second step in the area of the recesses 19, after removal of the masks 18, a nickel layer without mineral particles is applied, as indicated by the layer 5a, whereby a full-surface nickel layer is obtained which only partially has mineral particles 15. In the example shown, namely only in the area of the elevations.

The masks can be applied, for example, using a print head. If the pressing tool is a pressing sheet, then the masks are preferably applied with such a print head, which is arranged above the pressing surface to be produced and which is moved in a plane parallel to the pressing surface during the application of the masks. Depending on the surface, it is preferably provided that the print head is moved in a direction perpendicular to the surface, so that the distance between the currently applied mask and the print head is kept constant. Due to the constant distance, the currently applied mask can be applied better with the print head.

However, the masks can also be realized using the passivation mentioned above.

The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not restricted to the embodiments specifically shown, but rather various combinations of the individual embodiments with each other are also possible and this possibility of variation lies within the skill of the person skilled in the art in this technical field due to the teaching of technical action through objective invention.

The scope of protection is determined by the claims. However, the description and the drawings must be used to interpret the claims.

Individual features or combinations of features from the different exemplary embodiments shown and described can represent independent inventive solutions in their own right. The task underlying the independent inventive solutions can be found in the description. All information on value ranges in this description should be understood to include any and all sub-ranges, e.g. the information 1 to 10 should be understood to include all sub-ranges, starting from the lower limit 1 and the upper limit 10 , that is, all subranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, for example 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

For the sake of order, it should finally be pointed out that in order to better understand the structure, elements have sometimes been shown out of scale and/or enlarged and/or reduced in size.

Reference symbol list

Press tool

Substrat

Surface structure

Surface coating

layer

Layer thickness

Pores

Pore diameter

Surface

Coating process

electrolyte

Area

Layers

Control device

Mineral particles

Deepenings

surveys

Mask

Recesses

Claims

Patent claims

1. Pressing tool (1), designed for pressing material panels in heating presses, comprising:

- a substrate (2) made of a pressed sheet or an endless belt;

- a surface structure (3) for embossing a surface;

- a surface coating (4); characterized in that the surface coating (4) is formed by a layer (5) made of nickel or a nickel alloy and has a uniform layer thickness (6).

2. Pressing tool according to claim 1, characterized in that the layer (5) has pores (7) arranged evenly distributed.

3. Press tool according to claim 1 or 2, characterized in that the layer (5) is a nickel layer deposited without external current.

4. Pressing tool according to claim 2, characterized in that the pores (7) have an average pore diameter (8) of 0.1 pm to 1 pm, in particular 0.1 pm to 0.5 pm.

5. Press tool according to one of the preceding claims, characterized in that the layer has a pore content of at least 100 pores/cm ² .

6. Pressing tool according to one of the preceding claims, characterized in that the layer (5) has a phosphorus content of 1-13%.

7. Pressing tool according to one of the preceding claims, characterized in that the layer (5) has a layer thickness (6) of 2-50 pm, in particular 5 to 25 pm.

8. Press tool according to one of the preceding claims, characterized in that mineral particles are embedded in the layer (5).

9. Press tool according to one of the preceding claims, characterized in that the layer (5) is a partial layer.

10. Press tool according to one of the preceding claims, characterized in that the layer (5) is hardened.

11. Pressing tool according to one of the preceding claims, characterized in that the substrate (2) has a blasted surface (9), the layer (5) being arranged on the surface (9).

12. A method for treating a surface (9) of a pressing tool (1), wherein the pressing tool (1) comprises a substrate (2) made of a pressed sheet or an endless belt and is designed for pressing material panels in heating presses and wherein a surface coating (4) is applied to the pressing tool (1); characterized in that the surface coating (4) is applied in a coating process (10) by means of a layer (5) made of nickel or a nickel alloy with a uniform layer thickness (6).

13. The method according to claim 12, characterized in that the layer (5) is deposited in the coating process (10) by means of an electrolyte (11) without external current.

14. The method according to claim 13, characterized in that the pH value of the electrolyte (11) is monitored and regulated.

15. The method according to claim 14, characterized in that an acid content of the electrolyte (11) is adjusted.

16. Method according to one of claims 12 to 15, characterized in that pores (7) having a desired pore property are introduced in the layer (5) in a uniformly distributed manner by using a pore adjustment process.

17. The method according to claim 16, characterized in that the pore properties of the pores (7) are maintained in the pore adjustment process by means of early termination of the coating process (10).

18. The method according to claim 16 or 17, characterized in that the pore property (7) is obtained in the pore adjustment process by regulating a nickel concentration of the electrolyte (11).

19. Method according to one of claims 12 to 18, characterized in that a phosphorus content of 1-13% is introduced into the layer (5) in the coating process (10).

20. Method according to one of claims 12 to 19, characterized in that a surface (9) of the substrate (2) is blasted before the coating process (10).

21. Method according to one of claims 12 to 20, characterized in that the surface coating (4) is partially applied by masking at least one region (12) of a surface (9) of the substrate (2).

22. The method according to claim 21, characterized in that the masking is carried out by passivating the at least one region (12) of the surface (9) of the substrate (2).

23. Method according to one of claims 12 to 22, characterized in that mineral particles are introduced into the layer (5).

24. The method according to any one of claims 12 to 23, characterized in that the layer (5) is heat treated after the coating process (10).

25. The method according to claim 24, characterized in that the layer (5) is hardened at a temperature of 250°C to 500°C.