Method of producing decorative papers for laminated materials

The invention relates to a method of producing a decorative paper for a laminated material. The method comprises the steps of scanning a sample of a natural material for generating a digital image (10, 11, 12, 13), constructing a decorative motif (15, 16, 17, 18) by means of computer-assisted processing of the digital image (10, 11, 12, 13), and generating the decorative paper by printing the decorative motif (15, 16, 17, 18). The invention suggests that the step of digital image processing involves adapting the scanned digital image (10, 11, 12, 13) to a reference image (14). The object of the invention is to provide a design technique that allows to offer an almost arbitrarily large variety of decors to the consumers at low production costs.

CROSS REFERENCE TO RELATED APPLICATIONS

The invention relates to a method of producing a decorative paper for a laminated material.

Traditional building and finishing materials, such as wood and stone, are generally preferred by consumers because of their highly valued look and feel. However, such natural materials are expensive to produce and to install. A solid wood floor may have a very high-quality luxury appearance, but the required materials and the labor required to install such floors tend to be prohibitively expensive.

Laminated materials, such as, e.g., so-called high-pressure or direct-pressure laminate boards (HPL, DPL) are known as alternatives to traditional building and finishing materials. These laminated materials comprise a decorative motif, preferably a printed decorative paper. This paper is arranged on a substrate fibre material. The laminate further comprises a top layer based on synthetic material. The decorative motif may, e.g., imitate a wood grain pattern.

One problem of known laminated materials is that their surface texture does not match their decorative motif. For example, a visual depiction of a wood nerve does not match the surface texture characteristics of a wood nerve. As a consequence, these materials look fake and can readily be identified as something other than a traditional building or finishing material.

A prior art approach to matching the surface texture of a laminated material to its decorative motif is forming a surface texture by means of mechanical embossing. A press machine is used during production of the laminated material. The mechanical embossing is achieved by means of a corresponding press plate having a three-dimensional surface comprising ridges and/or depressions that are aligned with the decorative motif of the printed decorative paper. High-quality laminated materials produced in this way are referred to as ‘embossed-in register’ laminates. These materials have the realistic look and feel of traditional building and finishing products.

The decorative papers for laminated materials of the type described before are usually produced by starting from a sample of a natural material, such as, e.g., wood or stone. The sample is scanned for generating a digital image of its surface. The raw image data then undergoes an elaborate digital image processing step in order to construct the final decorative motif. This decorative motif determines the natural appearance of the material. Finally, the decorative motif is printed on paper. This printed decorative paper is provided to the further laminate manufacturing process.

For the production of embossed-in register laminates, the decorative motif information is provided to a press plate manufacturer who applies an embossing pattern to the press plate of the press machine used in the laminate production process. This embossing pattern includes elevated ridges, dots, depressions, etc. of an appropriate design which is aligned (when the press plate is hot) with the decorative motif formed on the decorative paper.

One problem of the above-described method of manufacturing embossed-in register laminates is that the step of making the press plate for mechanical embossing the surface of the laminated material is comparatively expensive. A large variety of decors is demanded by the consumers. Consequently, a corresponding large number of press plates (one press plate for each decorative motif) is required because the embossing pattern, which is aligned with the decorative motif, is different for each decor.

Therefore it is readily appreciated that there is a need for an improved method that enables to produce embossed-in register laminates at reduced manufacturing costs. It is thus the object of the invention to provide a method that allows to offer an almost arbitrarily large variety of decors to the consumers without the need to produce an expensive press plate for each individual decorative motif.

In accordance with the present invention, a method of producing a decorative paper for a laminated material is disclosed. The method comprises the steps of scanning a sample of a natural material for generating a digital image, constructing a decorative motif by means of computer-assisted processing of the digital image, generating the decorative paper by printing the decorative motif. The method of the invention is characterised in that the step of digital image processing involves adapting the scanned digital image to a reference image.

The insight of the invention is that the scanned digital images of the material samples can be adapted to a common reference image by appropriate digital image processing techniques such that each constructed decorative motif finally matches the embossing pattern of a single press plate used during the further production process. The gist of the invention is thus the use of a single common reference for the design of a set of decorative motifs. If a set of decorative motifs is prepared according to the invention using a common reference image, a single embossing pattern can be used for each decorative motif from this set because the technique of the invention reliably ensures that the embossing pattern will be aligned with the respective decorative motif. Only a single press plate can be used for an arbitrarily large set of decorative motifs. The manufacturing costs of embossed-in register laminates are significantly reduced in this way.

In accordance with the invention, the match of a visual depiction of the scanned natural material in the adapted digital image with a visual representation of material characteristics contained in the reference image should be as good as possible in order to obtain an optimum quality of the final laminated material. However, a perfect alignment of the scanned image with the reference image is not necessary. Certain deviations can be tolerated without compromising the quality appearance of the laminated material. The match of the adapted digital image with the reference image determines the degree of coincidence of the embossed texture with the respective decorative motif of the printed paper. A higher degree of coincidence results in a better imitation of the natural material.

According to a preferred embodiment of the invention, a visual representation of material characteristics (such as the surface texture of the respective material) may be contained in the reference image. This depiction may, as mentioned above, serve as a basis for the design of the embossing pattern applied to the press plate. It is also possible to design the press plate on the basis of a set of decorative motifs adapted to a single common reference image in accordance with the invention. The embossing pattern may include elevated ridges, dots, depressions, etc. of a design which is aligned with the respective decorative motifs. As a consequence, the surface texture of the laminated materials optimally enhances the decorative motifs of the decorative papers.

The natural material scanned according to the invention may be wood, wherein the reference image may contain a corresponding visual depiction of a wood grain pattern, such as wood nerves, wood knots, or wood pores. Two or more samples of different types of wood, such as, e.g., oak, cherry, or walnut, may be scanned, wherein the digital images of the two or more samples are adapted to a single reference image. The reference image can advantageously be generated by simply extracting the visual depictions of the surface texture of one of the scanned samples. As described above, only a single press plate is required for producing embossed-in register laminates on the basis of the two or more wood motifs in accordance with the invention.

The step of digital image processing of the method of the invention may involve at least one of the following techniques: geometric transformation; correction of color, brightness, and/or contrast; registration of the scanned digital image and the reference image; removal of unwanted image elements; image skew; image distortion. Each of these techniques may be applied locally or globally to the image data. Appropriate software products for digital image processing according to the invention, such as, e.g. Adobe Photoshop, are commercially available.

The following drawings disclose preferred embodiments of the present invention. It should be understood, however, that the drawings are designed for the purpose of illustration only and not as a definition of the limits of the invention.

The method shown inFIG. 1starts from a sample of a natural material, such as, e.g., wood, which is scanned for generating a digital image in step1. A reference image containing a visual representation of the surface texture of a laminated material is provided in step2. The reference image is provided in the preferred embodiment by extracting the visual depictions of the surface texture from the digital image of (at least one) further wood sample. The visual depictions contained in the reference image may be lines running along the course of the wood nerves in the scanned digital image. In step3a decorative motif is constructed by means of computer-assisted processing of the digital image generated in step1. The digital image processing in step3involves adapting the scanned digital image to the reference image provided in step2. This adaptation may be performed, e.g. by local geometric transformation, skew, and/or distortion of the digital image scanned in step1, such that the wood nerves depicted in the image scanned in step1are (to a greater or lesser extent) in coincidence with the wood nerve pattern contained in the reference image. The result of the image processing step3is a decorative motif which is printed on paper in step4. The decorative motif information and/or the reference image are provided to a press plate manufacturer in step5, who applies an embossing pattern to a press plate of a press machine used in the final step6of laminate production. The embossing pattern includes elevated ridges, dots, depressions, etc. of an appropriate design which is aligned with the decorative motif formed on the decorative paper. The press plate manufacturer can create the design of the embossing pattern at his discretion on the basis of the image data provided to him such that the surface texture of the finally produced laminated material optimally enhances the decorative motifs of the printed papers.

FIG. 2schematically shows digital images10,11,12, and13which are generated by scanning four different types of wood, such as, e.g., oak, walnut, cherry, and beech. As can be seen inFIG. 2, each type of wood has its own individual wood grain pattern. The scanned images10,11,12, and13constitute the basis for decorative motifs for the production of laminates in accordance with the invention. The wood grain pattern of image12, the scanned cherry sample, is selected as a reference. A reference image14is extracted from image12. The reference image14contains a line pattern representing the course of the wood nerves in image12. Images10,11, and13are processed by means of common image processing techniques in order to adapt their wood grain pattern to the pattern depicted in the reference image14. The result is a set of four different decorative motifs15,16,17, and18for laminates imitating oak, walnut, cherry, and beech. The wood grain patterns of the four decorative motifs15,16,17, and18essentially coincide with the reference image14. Embossed-in register laminates can be produced on the basis of these motifs using only a single press plate. The embossing pattern of the press plate can advantageously be designed on the basis of all four motifs15,16,17, and18. The surface texture of the final laminated material matches each decorative motif15,16,17, and18because of the alignment of each image10,11,12, and13with the reference image14. The oak, walnut, cherry, and beech laminates all have the realistic look and feel of traditional building and finishing products and can be manufactured at low cost.

While the decorative motifs illustrated inFIG. 2represent wood grains, it should be appreciated that other embossed-in register designs, such as ceramic tiles, concrete, marble, abstracts, textile, leather, etc. may be produced according to the invention.