EP2497650A1 - Method for processing a structured surface of an embossing tool - Google Patents

Abstract

The method involves providing a surface with a metallic coating (6) and providing another metallic coating with different gloss levels in selected areas (7,8,9,10,11). The different gloss levels are produced on the former coating in the multiple selected areas. The gloss levels are produced by combination of metallic coating and mechanical or chemical finishing operations.

Description

The invention relates to a method for processing a structured surface of an embossing tool, in which the surface is provided with a first metallic coating over the entire surface and in selected areas at least one further metallic coating having a different degree of gloss.

Generic embossing tools are needed in the woodworking industry, especially in the manufacture of wood-based panels. With the help of the embossing tools, the visible surface of the wood-based panels is characterized insofar that a desired motif, preferably a lifelike replica of a natural surface structure, can be produced. For this purpose, are applied to wood-based panels, which are preferably made of pressboard, for example, resin films, which are then pressed under pressure and temperature in hydraulic Heizpressenanlagen with the wood-based panel. During the pressing process, the resin film becomes liquid under pressure and temperature and polycondensation takes place. The pressing time and temperature determine the degree of crosslinking of the resins and their surface quality. After the pressing time, the resin has reached the desired degree of crosslinking and is in a solid phase. In this process, the resin surface assumes the desired lifelike surface due to the surface structure of the embossing tool. As the coating material thermosetting resins are used, for example melamine, phenolic or melamine / urea resins. For the purpose of surface design, a structured metallic press plate, preferably a steel sheet, is used for this purpose as an embossing tool. In order to improve the wear resistance and release properties of the metal surface, the embossing tools are additionally provided with a coating. Preferably, embossing tools are used in this method, which were produced by means of digital printing technology, so that the decorative papers used are also produced to scale according to the digital printing process and congruent can. Thus, a passagenaue arrangement of the decorative paper and the embossed structure can be achieved, whereby much better results than in the prior art can be achieved.

Embossing tools in the form of press plates or endless belts are produced according to the prior art by appropriate machining of the surface, by producing a desired surface structure. In the past, for this purpose, the pretreated sheet was provided with a matrix, for example by means of a screen printing process, so that subsequently an etching of the sheet can take place. An etching of the sheet takes place here only in the areas that are not covered by the matrix. Due to the sheet size used in this case a very accurate processing and especially congruent processing is required, as far as the production of the surface structure takes place in several steps. In this case, all areas which are to form the raised surface structure later are masked by the mask, so that a surface etching takes place only in the areas that can be attacked directly by the etching liquid. The etched areas then form the profile valleys of the desired structure, after completion of the respective etching process, the surfaces are cleaned and the mask is removed. This procedure can be repeated several times, whereby the accuracy in screen printing processes generally causes considerable difficulties for a precisely fitting application of further masks.

An alternative method is first to apply a photo layer, which is then subjected to an exposure to rinse the press plates or endless belts after the final development of the photo layer, so that only those parts of the photo layer remain, which form the mask for the subsequent etching process , The reproducibility of the masks produced in this way is very difficult and problematic because the negative or positive used for exposure of the photosensitive layer must always be arranged exactly in the same position relative to the existing structuring. Around For example, to simulate complicated three-dimensional structures on the surface of the press plate or the endless belt, therefore, several exposure and etching operations are required. Due to the fact that they are extremely large press plates, even the slightest deviation leads to considerable shifts in the structures. The reproducibility of the application of the mask is therefore associated, in particular in the photographic process to achieve a high imaging accuracy with considerable difficulties. The difficulties can be further increased if a three-dimensional structure has to be achieved by a plurality of exposure and etching processes which are required in succession and there is the need to apply a plurality of masks in succession and to perform an etching process between each mask application. Due to the required exact positioning and the required number of corresponding masks, the production of the press plates or endless belts is very complicated and expensive. The achievable results are also very much dependent on the methods used, which due to the size of the press plates or endless belts a complex handling must be considered.

Alternatively, it is known from the prior art to produce a mask by a wax application by means of a print head instead of a Slebdruckverfahrens. In this case, the wax application is chemically resistant to the etchants used, so that etching can take place in the areas in which the surface is not covered by the wax. For this purpose, a spray head is used, which sprays the wax onto the surface and is movable along an x and y axis in order to simulate the required structure. However, the use of wax to apply a matrix has been found to be detrimental because the wax is difficult to remove from the surface and the required cleaning is very costly. The resulting costs and the dissolution of a wax matrix have led to the need for further digitized printing techniques. Thus, it is known, for example, a UV varnish with the aid of a print head on the surface of the embossing tools to be machined, in particular press plates or to apply endless ribbons. The particular advantage of the digitized printing technique is that almost identical masks can be repeatedly applied to existing structures again and thus several etching operations, for example, to achieve a deep structure, successively passagenau can be performed.

From the DE 102 24 128 A1 For example, a method for applying coatings to surfaces is known in which a nozzle head is used and the individual nozzles are controlled by control signals. Either the nozzle head can be moved over the surface or the surface to be treated is moved relative to the nozzle head. Preference is given here a UV varnish is used, which is cured after application to the surface by irradiation with UV light.

Regardless of the way in which the structuring of the surfaces of the press plates or endless belts was carried out, these are subjected to a plurality of cleaning process and can additionally be coated with a nickel layer, which is then refined by further metallic coatings. The metallic coatings give the surface a desired degree of gloss and a necessary surface hardness. The degree of gloss is responsible for the fact that after compression of the materials to be processed with the help of the press plates or endless belts hereby pressed structure receives different shades and color reflections.

In order to improve the appearance, it has furthermore been proposed to provide partial areas of the surface with different metallic coatings in order to vary the degree of gloss. By this measure, desired shading effects can be achieved.

The present invention has for its object to provide a further improved embossing tool and a method for producing the same to a To enable a variety of shading possibilities with appropriate transfer to a wood material.

According to the invention, it is provided for achieving the object that different degrees of gloss are produced on the first coating in a plurality of selected regions, wherein the gloss levels are produced by a combination of metallic coatings and mechanical or chemical aftertreatments. Further advantageous method steps can be taken from the subclaims.

In order to produce a large number of degrees of gloss on an embossing tool and to keep the costs as low as possible, it is proposed, in addition to the use of metallic coatings of different gloss levels, to carry out a partial aftertreatment of individual areas of the surface by mechanical or chemical processes. It is thus a combination of individual treatment methods to provide on a structured surface of the embossing tools certain areas, which are represented for example by the wood grain of the surface, with a certain degree of gloss and other areas with deviating degrees of gloss, with several different gloss levels on a Surface can be present. On the one hand, these gloss levels are produced by a metallic coating and on the other hand by mechanical or chemical processing, wherein between the individual treatment steps, a digitized mask is applied to only edit or coat the areas that should receive a different gloss level. Thus, it is possible to apply a hard chrome plating with a certain degree of gloss over the entire surface after completion of the structuring measures, then after application of a matrix, a part of this surface with a different degree of gloss can be achieved by mechanical, chemical or possibly further application of a metallic coating. Following this, at least once, if necessary, a mask can be applied several times to further partial areas of the surface structure with further of the first Gloss levels to provide different degrees of gloss. In this case, a metallic coating may also be applied in individual cases, but also a mechanical or chemical treatment method may be used. By combining the different treatment methods, there is the particular advantage that the finest gloss level differences can be produced and, moreover, cost-effective production is possible even with multiple gloss leveling.

To achieve the different degrees of gloss, in this case a digital printing technique is used to apply the protective layer (mask), which guarantees the exact pass-through application of the protective layer, even with repeated repetition. The application of the protective layer can be carried out in subsequent steps in the form that this is applied at least partially overlapping or non-overlapping to the already completed areas. Depending on the present structuring of the surface of the pressing tool, it may be necessary for the partial areas with different degrees of gloss to be arranged next to one another, but there is also the possibility that an overlapping is desired from an aesthetic point of view.

By applying a second partial coating or mechanical or chemical treatment on an existing first coating thus different gloss levels can be achieved, the degree of gloss of an embossing tool, in particular a press plate or an endless belt, at least partially deviate from each other in partial areas. By this measure it is possible to provide raised structures or optionally deeper structures with a different degree of gloss, so as to emphasize the structure particularly. By this measure, the visual impression is sustainably improved and leads to a surface that is congruent executable due to the passport-accurate artwork and passport-accurate matrix and thus not only a different depth structure can be achieved, but also a different gloss level to highlight certain structural areas. This gloss level difference can be optionally provided, for example, the raised Areas have a higher gloss level than the lower-lying areas or vice versa. The multiple application of different degrees of gloss, be it by further coatings or by mechanical or chemical methods, the structured areas of the surface of the press plate or endless belt can be highlighted even more clearly than was previously possible. Thus, a significant improvement of a detailed structuring is possible. For example, a lacquered real wood surface can be modeled, wherein the raised surfaces have a certain degree of matt and the deeper wood pore, due to the light reflection, show a shiny area. The wood pore structures required in this case are produced with the aid of the pass-through-accurate matrix and known etching technologies. By using the digital printing technique, a multiple passagenaue arrangement and coverage of the respective structure is possible, so that a variety of gloss levels on an existing structured profiling can be achieved that leaves nothing to be desired. For example, a variation of the gloss level on a single wooden pore may be provided. It is also possible to provide individual wood pores with different degrees of gloss, which are either arranged adjacent or have greater distances from each other. Thus, it is possible to provide several adjacent wood pores each with a different gloss level to improve the overall look.

For the production of the surface structure, a deep etching is usually carried out first and then a circular etching in order to emphasize the shape of the pore structure. After that, a mechanical polish can be done before the surface is cleaned and degreased. For better adhesion of the metallic layers, in particular the chromium layer, the structured surface can be additionally activated before the application of the coatings, or other coatings which ensure better adhesion, for example a nickel layer, can be applied.

A first applied metallic coating usually consists of a chrome plating, which is a high-gloss chrome plating or a matt chrome plating can act. It is in any case conceivable that instead of a chrome plating other metal coatings are made. However, as far as a first coating has been applied by means of a chrome plating, it is imperative that the protective layer (mask) to be applied consists of a chromic acid-resistant material, so that the protective layer is not affected during the chrome plating or further chromium plating steps.

For better adhesion of the protective layer to the already existing chromium plating, the protective layer can be provided as a further intermediate step, the protective layer being completely removed after the second treatment has been carried out. To achieve the respective gloss levels, a method step by matte etching, sandblasting or mechanical polishing can be provided in addition to a metallic coating.

• Auftragen einer ersten Maske auf die Oberfläche mittels einer digitalen Drucktechnik,
• chemisches Bearbeiten der mit der Maske versehenen Oberfläche zur Erzielung einer Oberflächenstruktur,
• erneutes Auftragen einer zweiten passgenauen Maske auf die chemisch bearbeitete Oberfläche mittels einer digitalen Drucktechnik,
• erneutes chemisches Bearbeiten der mit der zweiten Maske versehenen Oberfläche,
• Polieren der chemisch bearbeiteten Oberfläche,
• Aktivieren der polierten Oberfläche,
• Reinigen der aktivierten Oberfläche,
• Verchromen der gereinigten Oberfläche,
• erneutes Auftragen einer dritten passgenauen Maske auf die verchromte Oberfläche,
• erneute metallische Beschichtung oder mechanische oder chemische Nachbehandlung der mit der Maske versehenen verchromten Oberfläche,

wobei die beiden zuletzt genannten Schritte für partielle Bereiche zumindest einmal wiederholt werden, um auf der strukturierten Oberfläche unterschiedliche Glanzgrade zu erzielen.According to the invention, a method is provided for achieving a plurality of different degrees of gloss, which method comprises the following steps:

• Applying a first mask to the surface by means of a digital printing technique,
• chemically processing the masked surface to provide a surface texture;
• reapplying a second tailored mask to the chemically processed surface using a digital printing technique;
• retreating the surface provided with the second mask,
• Polishing the chemically treated surface,
• Activate the polished surface,
• Cleaning the activated surface,
• Chrome plating the cleaned surface,
• re-applying a third accurate mask to the chrome-plated surface,
• re-metallic coating or mechanical or chemical post-treatment of the masked chromed surface,

wherein the last two steps are repeated at least once for partial areas in order to achieve different gloss levels on the structured surface.

The aforementioned method describes the possibility of applying a first mask to the existing surface of the embossing tool to carry out a chemical processing of the surface to achieve a surface structure and then to perform a re-processing of the surface provided with the second mask after applying a second passagenauen mask. After that, the surface can be polished, activated, cleaned, and chrome plated before applying another third matte mask to the chrome surface. The third mask covers the areas which are no longer subject to further treatment, while the exposed areas are subsequently given a different degree of gloss by a renewed metallic coating or mechanical or chemical aftertreatment. The application of further masks and further aftertreatments by a metallic coating or mechanical or chemical aftertreatment can hereby be repeated as desired.

• Auftragen einer ersten Maske auf die Oberfläche mittels einer digitalen Drucktechnik zur Feinstrukturierung,
• chemisches Bearbeiten der mit der Maske versehenen Oberfläche zur Erzielung einer Oberflächenstruktur,
• Auftragen einer zweiten passgenauen Maske auf die Oberfläche mittels einer digitalen Drucktechnik zur Porenstrukturierung,
• chemisches Bearbeiten der mit der Maske versehenen Oberfläche zur Erzielung einer Oberflächenstruktur,
• erneutes Auftragen einer dritten passgenauen Maske auf die chemisch bearbeitete Oberfläche mittels einer digitalen Drucktechnik,
• erneutes chemisches Bearbeiten der mit der dritten Maske versehenen Oberfläche,
• Polieren der chemisch bearbeiteten Oberfläche,
• Aktivieren der polierten Oberfläche,
• Reinigen der aktivierten Oberfläche,
• Verchromen der gereinigten Oberfläche, .
• erneutes Auftragen einer vierten passgenauen Maske auf die verchromte Oberfläche,
• erneute metallische Beschichtung oder mechanische oder chemische Nachbehandlung der mit der Maske versehenen verchromten Oberfläche,

wobei die beiden zuletzt genannten Schritte für partielle Bereiche zumindest einmal wiederholt werden, um auf der strukturierten Oberfläche unterschiedliche Glanzgrade zu erzielen.Alternatively, it is possible to supplement the method by further steps, which provides a multiple application of a mask and a treatment of the surface to achieve the desired surface structure and gloss levels, namely

• Applying a first mask to the surface by means of a digital printing technique for fine structuring,
• chemically processing the masked surface to provide a surface texture;
• Applying a second tailored mask to the surface by means of a digital printing technique for pore structuring,
• chemically processing the masked surface to provide a surface texture;
• re-applying a third accurate mask to the chemically processed surface by means of a digital printing technique,
• retreating the surface provided with the third mask,
• Polishing the chemically treated surface,
• Activate the polished surface,
• Cleaning the activated surface,
• Chrome plating of the cleaned surface,.
• reapplying a fourth accurate mask on the chromed surface,
• re-metallic coating or mechanical or chemical post-treatment of the masked chromed surface,

wherein the last two steps are repeated at least once for partial areas in order to achieve different gloss levels on the structured surface.

The abovementioned methods are characterized in that there is a structure-conforming overlap and that no deviation from the desired structure results over the entire surface of the press plates or endless belts. The number of masks is determined here by the number of necessary processing steps, with the structuring of the surface being the main focus in order to then be able to make a desired degree of gloss adjustment. According to the invention, it is provided here that at least a first degree of gloss is predetermined by metallic coating, while further partial gloss levels are given a different degree of gloss either by metallic coating or by mechanical or chemical treatment methods. The frequency of the applied masks and processing operations depends essentially on the surface structuring, whether it is, for example, a lifelike replica of a wooden pore or a rock surface or graphic artificial structures are to be reproduced faithfully.

The application of the method according to the invention leads to an embossing tool with a structured surface which extends over the entire surface over the entire surface of the embossing tool and has different gloss levels with the aid of metallic coatings and aftertreatment methods. Frequently, a material coating with chrome is made for this purpose, since these is particularly hard and is most suitable for the pressing operations to be carried out. However, it is readily possible to press other materials that do not have a particularly high degree of hardness and whose surface is elastic and soft, so that other metallic coatings come into question to achieve a different degree of gloss.

The particular advantage of the method according to the invention and the embossing tool presented here is to produce identical structures, as they are known from nature, with different degrees of gloss, which have a particularly appealing look and feel, giving the impression that it has grown, for example natural wood acts. Due to the different degree of gloss, certain areas, for example, raised areas or even lower areas, can additionally be provided with several different degrees of gloss, so that the structure emerges very concisely and produces an optical effect which leads to a material surface which, for example, hardly grows from grown wood to distinguish. Alternatively, it is possible to feel other, lifelike surfaces accordingly.

The invention will be explained again with reference to the figures.

Fig. 1

in einer perspektivischen Ansicht ein erfindungsgemäßes Press-blech und

Fig. 2

in einer vergrößerten Seitenansicht die vorhandene Struktur auf der Pressblechoberfläche mit unterschiedlichen Glanzgraden.

It shows

Fig. 1

in a perspective view of an inventive press sheet and

Fig. 2

in an enlarged side view, the existing structure on the press plate surface with different gloss levels.

FIG. 1 shows a perspective view of an inventive press plate 1, which is flat in the embodiment shown. In the case of an endless belt, however, this embossing tool can also be curved. The

Press plate 1 shows a grain 2 which is modeled on the shape of a wood structure. However, it is conceivable that other grains or other surface textures are produced in this way by the method according to the invention and the etching process required for this purpose.

FIG. 2 shows in an enlarged side view a part of the front edge region of the press plate 1 and the structure thereon 3, which has a mountain-like surface with valleys 4 and heights 5. In this case, the surface is produced by one or more etching processes, after which a matrix has previously been applied in a standard process or a digitized printing technique, the regions which are not to be subjected to the etching processes being masked by the mask. With the aid of the etching process, for example, fine surface structures and deep structures can be produced, which are then optionally additionally rounded off by mechanical processing or etching processes. After the surface has been etched, the surface structure is completed by further chemical processing, polishing and, where appropriate, activation of the polished surface, so that subsequent cleaning takes place before a first metallic coating 6 with a certain degree of gloss is applied.

The metallic coating 6 has a certain degree of gloss, which depends on the customer's wishes. Subsequently, a mask is applied to this first metallic coating 6 which covers the areas which are not to be subjected to any further treatment. In contrast, the exposed areas can be provided with a different degree of gloss by further processing methods, for example matte etching, sand blasting or mechanical polishing or repeated application of a metallic coating. In this case, the method according to the invention provides that in each case a mask is applied for specific partial areas and the exposed areas are subjected to a further treatment process. After removal of the applied mask, this process can be repeated several times, so that the structure 3 of the press plate 1 receives different degrees of gloss in selected areas.

In the exemplary embodiment shown, different degrees of gloss have been produced on the first metallic coating 6 by applying different masks and subsequent treatment methods. In the area of the valleys 4, for example, no treatment is carried out, so that the areas marked in white 7 have the gloss level of the first metallic coating 6, while on the other hand the tips of the heights 5 have different degrees of gloss. These different degrees of gloss are characterized by completely colored areas 8 and by hatched areas 9 and 10. In the transition regions of the valleys 4 and heights 5, a gloss level deviating therefrom has been created by applying a corresponding mask through a subsequent process step. These areas 11 are shown in dots.

In a departure from the exemplary embodiment, however, there is the freedom to provide all heights 5 with a uniform degree of gloss or, if appropriate, to provide the transition areas with divergent degrees of gloss. In principle, by applying a digitized mask and the process steps provided for producing a degree of gloss, the present invention makes it possible to vary the arrangement of the individual gloss levels as desired. Insofar as a wood structure is reproduced on the press sheet 1 by the etching methods used, it is possible, for example, to provide the raised areas 7 with a matt degree of gloss and to provide the lower areas forming the wood pores with a higher degree of gloss. By the possibility of applying a plurality of masks and to achieve a certain degree of gloss in a subsequent process step, for example, adjacent raised areas can be provided with different degrees of gloss. It is also possible to provide the flanks of individual elevated areas with a different degree of gloss to clearly express the appearance of the wood pores. By this measure, the wood pore structures that match exactly register with the wood decor print are highlighted and give the with The products produced on press plates appear to have the appearance of a real wood character, which is very close to the natural product.

Bezugszeichentiste

1

press plate

2

Grain

3

structure

4

valley

5

height

6

coating

7

Area

8th

Area

9

Area

10

Area

11

Area

Claims (12)

Method for processing a structured surface of an embossing tool, in which the surface is provided with a first metallic coating (6) over the entire surface and in selected areas (7, 8, 9, 10, 11) has at least one further metallic coating with a different gloss level,
characterized,
that different gloss levels are produced on the first coating (6) in several selected areas (7, 8, 9, 10, 11), the gloss levels being produced by a combination of metallic coatings and mechanical or chemical aftertreatments. Method according to claim 1,
characterized,
in that on the first coating (6) for fixing the selected regions (7, 8, 9, 10, 11), a protective layer (mask) is partially applied by means of a digital printing technique. Method according to claim 2,
characterized,
that the protective layer is applied in subsequent steps at least partially overlapping or non-overlapping on already completed areas (7, 8, 9, 10, 11). Method according to one of the preceding claims,
characterized,
that a chromic acid-resistant material is used for the protective layer. Method according to one of claims 2 to 4,
characterized,
that the protective layer is baked in the first coating (6). Method according to one of claims 2 to 5,
characterized,
in that the metallic coatings (6) are produced by chromium plating. Method according to one of claims 2 to 5,
characterized,
that further gloss levels are achieved by matte etching, sandblasting, or mechanical polishing. Method according to one of the preceding claims,
characterized,
that the gloss levels are at least partially partially juxtaposed or that the gloss levels are at least partially spaced from each other. Method according to one of the preceding claims,
characterized,
that the structured surface is activated before the application of the coatings (6). Method for processing a surface of an embossing tool, comprising the steps: Applying a first mask to the surface by means of a digital printing technique, - chemically processing the masked surface to obtain a surface texture, re-applying a second tailored mask to the chemically processed surface by means of a digital printing technique, re-chemical working of the surface provided with the second mask, Polishing the chemically processed surface, - activate the polished surface, - cleaning the activated surface, - chrome plating of the cleaned surface, - re-applying a third accurate mask on the chrome-plated surface, - renewed metallic coating (6) or mechanical or chemical
Aftertreatment of the masked chromed surface, wherein the last two steps are repeated at least once for partial areas in order to achieve different gloss levels on the structured surface. Method for processing a surface of an embossing tool, comprising the steps: Applying a first mask to the surface by means of a digital printing technique for fine structuring, - chemically processing the masked surface to obtain a surface texture, Applying a second tailored mask to the surface by means of a digital printing technique for pore structuring, - chemically processing the masked surface to obtain a surface texture, re-applying a third accurate mask to the chemically processed surface by means of a digital printing technique, re-chemical working of the surface provided with the third mask, Polishing the chemically processed surface, - activate the polished surface, - cleaning the activated surface, - chrome plating of the cleaned surface, - re-applying a fourth accurate mask to the chromed surface, - renewed metallic coating (6) or mechanical or chemical
Aftertreatment of the masked chromed surface, wherein the last two steps of the last two steps are repeated at least once for partial areas in order to achieve different gloss levels on the structured surface. Embossing tool with at least one structured surface,
characterized,
that a metallic coating (6) of a first material and partly a metallic coating of a second material in selected areas (7, 8, 9, 10, 11) is arranged over the entire surface of the structured surface or further regions (7, 8, 9, 10, 11) obtained by mechanical polishing, matte etching, sandblasting or chemical treatments a gloss level, wherein the gloss levels of the areas (7, 8, 9, 10, 11) differ from each other.

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