EP2292436B1 - Method for producing a component having a printed real wood surface and component produced according to the method - Google Patents

Description

The invention relates to a method for producing a component with a real wood surface, which is printed by means of an inkjet printing process such that its appearance corresponds to that of an original with a predetermined Wunschholzart corresponding grain and Porung and a predetermined color.

Real wood surfaces are enjoying increasing popularity, be it on furniture, kitchens, wood applications in automobiles, etc. Here are surfaces of exotic woods, especially tropical precious woods, particularly popular. The consumption of such generally slow-growing wood leads to serious ecological disadvantages. It is therefore for example from the DE 103 23 412 A1 known to provide components with real wood surfaces of less valuable and, for example, in plantations rapidly renewable woods and printed by an inkjet printing process so that they get an appearance that corresponds to a precious wood surface.

From the DE 103 23 412 A1 A method is known for producing a planar component having a predetermined surface appearance, in which a planar component with a surface consisting of wood is printed by means of a printing process which is programmable with regard to the resulting appearance to form a predetermined pattern, its appearance of a predetermined type of wood having a predetermined coloring equivalent.

In the DE 600 09 141 T2 For example, there is described a method of fabricating a surface element decor in which a segmentation pattern is formed having segmentation of at least two decor segments on each surface element. Furthermore, for each segment, a segment decoration is selected from a group consisting of a digitized and simulated representation of different types of wood, minerals, stone, etc. Each selection will be at one Terminal, where a selection is made from a database visualized at the terminal.

From the DE 10 2004 051 828 A1 For example, there is known a method of producing a decorative wood material in which an image of a surface of a wood material is stored, the surface of the wood material is bleached, and the stored image is printed congruently on the bleached surface after electronic processing, for example, suppression of stains on the surface ,

The invention has for its object to provide a method for producing a component with a real wood surface, in particular a real wood surface of a low-cost timber, which is printed by means of an injection printing process such that their appearance to the appearance of a surface of a predetermined timber, especially a precious wood, possibly in a corresponding to a customer request predetermined color, as much as possible.

This object is achieved by a method according to claim 1.

The dependent claims 2 to 8 are directed to advantageous embodiments and refinements of the method according to the invention.

The invention is explained below with reference to schematic drawings, for example, and with further details.

Fig. 1

eine Prinzipdarstellung eines Systems zur Herstellung erfindungsgemäßer Bauteile zur Erläuterung verschiedener Schritte zur Durchführung des erfindungsgemäßen Verfahrens,

Fig. 2

Querschnitte durch ein erfindungsgemäßes Bauteil zur Erläuterung einzelner Bearbeitungsschritte und

Fig. 3

eine schematische Darstellung zur Erläuterung der Erzeugung eines Datensatzes zur Bedruckung einer großen Fläche aus einem Grunddatensatz.

In the figures represent:

Fig. 1

a schematic diagram of a system for the production of components according to the invention for explaining various steps for carrying out the inventive process

Fig. 2

Cross sections through an inventive component for explaining individual processing steps and

Fig. 3

a schematic representation for explaining the generation of a data set for printing a large area from a basic data set.

• Mit A ist eine Kundenwunschvorlage bezeichnet, deren Aussehen dem entspricht, was ein Kunde haben will. Das Aussehen der Oberfläche einer Kundenwunschvorlage A lässt sich hinsichtlich einer vorbestimmten Wunschholzart durch ihre Maserung, die im Wesentlichen durch das Linienmuster des Holzes gegeben ist, die Porung, die die Porengröße, Porendichte usw. angibt, und die Färbung der Oberfläche, angegeben im Wesentlichen durch die Färbung der hellsten, der mittleren und der dunkelsten Bereiche nach Farbe und Kontrast, beschreiben.

In Fig. 1 is a system for producing a printed component using the method according to the invention sketched:

• A is a customer request template whose appearance corresponds to what a customer wants to have. The appearance of the surface of a customer's request original A is substantially indicated by a grain type predetermined by the grain pattern of the wood, the pore indicating the pore size, pore density, etc., and the coloring of the surface the coloring of the brightest, the middle and the darkest areas after color and contrast, describe.

B denotes a supply of desired wood pattern data sets, which essentially contain grain images of different types of wood, especially types of precious wood.

C denotes a timber warehouse in which inexpensive wood species, for example in the form of cut or peeled veneer with a thickness between 0.25 mm to 8 mm store or in the form of to be printed components with surfaces from the timber available.

D denotes a station for the pretreatment of the later to be printed timber surfaces.

E denotes a station for scanning the grain of the customer original A.

F denotes a station for detecting the coloring of the customer's original.

H denotes a computer system in which input data can be processed in accordance with well-known data processing programs in terms of coloring, contrasting, formats, etc.

K denotes a controlled by the computer system control device for an inkjet printing device.

N denotes a detection station for detecting the appearance of the surface of a sample pattern M printed in the inkjet station L.

P denotes a station for assembling the components.

In the following, aspects of the aforementioned stations and their interaction will be explained. The invention can be used for substantially all components with real wood surfaces, such as lightweight panels, furniture, floors, facade or support plates, these components may consist of solid wood or contain the real wood surface in the form of applied to a base made of a variety of material veneer.

It is assumed that the customer request template A would correspond in appearance to a natural or in a predetermined manner colored precious wood (wish wood).

• Die Porung des Nutzholzes muss der Porung des Wunschholzes möglichst ähnlich sein. Weiter sollte das Nutzholz möglichst farbhomogen sein und nur eine geringe Textur haben. Die natürliche Färbung des Nutzholzes sollte nicht dunkler als die des Wunschholzes sein. Wegen ihrer kontrastarmen Durchfärbung werden Splinthölzer als Nutzhölzer bevorzugt.

Based on the desired wood species, which can be determined from the grain of the original recorded by scanning (Scanstation E) and comparison with a wood type grain file, a low-cost timber species is determined from a file under the following criteria:

• The piling of the timber must be as similar as possible to the piling of the desired wood. Next, the timber should be as homogeneous as possible color and have only a small texture. The natural color of the timber should not be darker than that of the desired wood. Because of their low-contrast coloring, sapwoods are preferred as useful woods.

From the above-mentioned point of view, a cost-effective timber is selected from the timber storage C, which can be equal to the desired wood at cost timber desired.

For example, deciduous broadleaf foliage trees that grow in North America, Europe or Asia include ash (constant, low contrast, bright coloration with pronounced porosity, good hardness, fast growing), birch (very light color, low in contrast, fast growing, through Glossy strip particularly suitable for mirror effects), linden and maple. Broad-leaved hardwoods that grow in Africa, South America, Asia and Australia include limba, koto and eucalyptus. Due to a continuous growth and low-contrast coloring, these hardwoods are well suited as useful woods.

Broad-leaved deciduous trees, which grow in North America, Europe and Asia, are beech (low-contrast, medium growth, good toughness, constant regular porosity, particularly suitable for dark decors), oak, elm, alder, poplar. A broad-leaved hardwood, which grows in Africa, South America, Asia and Australia, is Gabon, which is characterized by uniform pores and a muted homogenous color scheme.

Softwoods with a light base tint are pine, spruce, fir and Douglas fir.

The later surfaces to be printed on the timber need not necessarily be flat, but may be curved, as it is required for automotive applications. The timber can be applied over corners, curves and surfaces passing on edges.

The wish wood should be darker at its brightest point than the base wood. For example, the lumber can be imprinted with rosewood or zebrano as desired wood, or the Gabon timber can be printed with mahogany.

It is also possible to print a darker pattern of the same type of wood on a light-colored timber, for example, to print the beech wood beech on beech wood or to print oak wood as desired wood for bog oak. It is also possible to print on a timber another, dyed wood decor as desired wood, for example, to print on the birch timber a blue-colored stone pine or print on the timber ash a whitewashed pine as wish wood.

The timber should be a low-cost wood whose consumption is harmless from a sustainability point of view. As wood also a wood-based veneer can be used, which is produced by gluing or compound of residual wood, which are pressed in the same direction of fiber flow into a block and then cut into cut or peeled veneers. Such a wood material has a constant color with depending on the used woods specific Porung.

The selection of the timber can be done automatically by the relevant data of the customer request template, such as grain and / or pores are scanned, from the desired wood species is determined, from the desired wood species from a file to the desired wood species among the above-described aspects of the most suitable timber species is determined or directly on the basis of the Porung the customer request template a type of timber with a suitable pore is determined.

• Erhöhung der Druckbelastbarkeit durch Einschluss von härtenden Substanzen oder Zugabe von mineralhaltigen, z.B. korrundartigen Substanzen zu einer Grundflüssigkeit,
• Schutz vor biotischen Einflüssen durch Zugabe entsprechender Substanzen zu der Grundflüssigkeit,
• Resistenz gegen Umwelteinflüsse, insbesondere durch pH-Wert Einstellung,
• UV-Stabilisierung im Holzkern und der Oberfläche, insbesondere damit keine Farbveränderungen auftreten oder Lignin herausgelöst wird,
• Unterdrückung der hygroskopischen Eigenschaften durch Füllen des feinstkapillaren Fasermaterials mit ggf. aushärtenden Füllsubstanzen,
• Stopp der Holzschwindung,
• Erhöhte Biegefähigkeit durch Einbringen von nach Polymerisieren nachgiebig bleibenden Kunststoffen.

When a timber species compatible with the customer's request is selected, a corresponding component to be further processed is provided from the timber storage C and subjected to a pre-treatment in the pre-treatment station D in which it is prepared for inkjet printing. This pretreatment concerns the physical and chemical preparation of the timber surface for later use. Depending on the intended use, for example, the following properties can be achieved by introducing liquids into the later-to-be-printed surface of the timber:

• Increasing the compressive strength by inclusion of hardening substances or adding mineral-containing, for example, corrosive substances to a base liquid,
• Protection against biotic influences by adding appropriate substances to the base liquid,
• Resistance to environmental influences, in particular by pH adjustment,
• UV stabilization in the wood core and the surface, in particular so that no color changes occur or lignin is leached out,
• Suppression of the hygroscopic properties by filling the ultrafine capillary fiber material with optionally hardening filling substances,
• Stop the wood shrinkage,
• Increased bending capacity by introducing plastic which remains flexible after polymerisation.

• Das Nutzholz wird zunächst getrocknet, damit es die Funktionsflüssigkeit, die ihm die erwünschten Eigenschaften verleiht, gut aufnimmt.

For example, the pretreatment is as follows:

• The timber is first dried so that it absorbs the functional fluid that gives it the desired properties, well.

After drying, the surface may be sandblasted or brushed in the fiber direction to aid the three-dimensionality of the wood structure.

The respective functional fluid is then applied, depending on the desired properties, the base wood can be completely saturated or treated only superficially with the functional fluid.

In any case, care must be taken to ensure that the functional fluid is so fluid and so that it does not completely fill the superficially exposed pores of the timber or its inner channels or pores after drying. The functional fluid can be based on synthetic resin, water or another solvent (Nitro) and its the timber the desired function imparting ingredients in dissolved or in the form of sufficiently finely divided particles, eg also in the form of nanoparticles.

After drying the functional fluid, the wood surface is finely ground in several stages, where it can be moistened before the final fine sanding, so that by the moisture pre-swelling fibers are sanded with. As a result, no fibers protrude during later inkjet printing and the surface finish is maintained. Already between the grinding steps, but necessarily after the last grinding step, the surface is carefully cleaned of grinding residues, so that the three-dimensionality of the surface is exposed and the surface has no impurities.

After the pretreatment, a component provided with the pretreated timber surface or at least a sample of the timber surface of the inkjet station L is supplied.

In the following, the generation of the desired wood pattern data records B which are stored in a corresponding database B will be explained. Typical request wood patterns are mahogany, teak, rosewood, makassar, gapelli, iroko kambalá, framiere, sapele, amaranth, abachi, makore, wenge, bongossi, afzelia, Baukirai, walnut, stone pine, bog oak, eucalyptus, olive, rose oak, etc .. The Wunschholzmuster are obtained by scanning a sample surface of the desired wood surfaces, wherein the respective desired wood surface may be present as a veneer. Similar to the surface of the timber to be printed, the surface is sanded in several stages before being scanned, whereby moistening can be carried out before a final fine sanding, which can then be wet-sanded wet. Again, the sanded surface is carefully freed from abrasive residue so that the pore or three-dimensionality of the surface of the desired wood is exposed. Subsequently, the desired wood surface is scanned in, whereby the scanned data contain above all the grain of the surface in the form of the grain lines and their contrast. When scanning, preferably only half and midtones of the surface are detected. It For example, you can work with a known SCAN program "SilverFast".

The respective desired wood pattern data record can be automatically selected from the data record stock B by comparing the grain of the original A scanned in a step E by selecting a sample data record from the stock B which is closest to the pattern of the original A.

In the EDP system H, it is thus preferable to work with a desired wood pattern data set which is produced by scanning in accordance with the above-described method from a genuine desired wood surface after its surface treatment. This desire wood pattern data set is processed with color data obtained by detecting reference tone values of the surface of the customer request form A by means of color densitometry measurement. The reference tone values may be, for example, cyan, magenta, yellow and black, their proportions measured and with which the selected desire wood pattern data set for generating a control record for the control device K of the inkjet printing device L according to well-known programs, such as those used in the graphics industry, mixed together , For example, you can work with a known under the name "Photoshop ^® " image editing program. Alternatively, it is also possible to directly use a data record for controlling the inkjet printing device which is obtained by completely scanning the customer request template.

After a print data set produced from the desired wood pattern data record and the color data or a print data record produced directly by scanning the customer request template A is available in the EDP system, a sample pattern M is printed in the inkjet method. In this case, the color liquid quantities are adjusted so that the three-dimensionality of the surface of the sample pattern is maintained.

Fig. 2 schematically shows a cross section through a component in various of the above-described processing steps.

A designated as a whole with 10 component includes a base body 12, on which a veneer 14 is applied from timber.

Fig. 2a shows the base body 12 in the raw state. The veneer 14 or the timber is cut parallel to the grain or grain, wherein in the timber channels are both parallel to the grain as well as perpendicular to the grain. The perpendicular to the grain channels extending in the radial direction, for example, a trunk and are used to supply in the radial direction, for example, in branches. In Fig. 2a Visible is an exposed pore 16 and a pore 18 present in the interior of the veneer 14 or a channel present in the interior, both pores being perpendicular to the actual grain. Naturally, pores or channels running parallel to the grain are not visible in the illustrated cutting direction.

Denoted at 20 are superficially exposed fibers of the timber, giving a rough surface.

Fig. 2b shows the impregnated with a functional liquid veneer 14, wherein the functional fluid 22 is symbolized by small circles. The functional fluid is adjusted so that the pores 16 and 18, which have a smaller capillarity than the finest-capillary fibers of the wood itself, remain open or free from functional fluid.

Still in the wet state, but preferably after drying, the surface of the veneer 14 is finely ground and completely freed from grinding residues, the grinding depth in Fig. 2b indicated by dashed lines. According to Fig. 2c has the superficially finished ground and cleaned component 10 a with the exception of the now exposed pore 18 level surface 24, wherein the veneer 14 is filled with the dried residues of the functional fluid, so that in its surface no or only minimal amounts of other liquid can penetrate.

The moistening step between fine grinding steps described above is not mandatory in the preparation of a timber surface for printing as well as in the preparation of an original surface for scanning when working with modern grinding machines.

The in the state according to Fig. 2c surface is now printed by the inkjet method, wherein, as in Fig. 2d shown, there are different print layer thicknesses, namely a thin print layer thickness 26 with weak coloration, a medium print layer thickness 28 with medium coloration and a thick print layer thickness 30 with strong coloration or a thin print layer thickness 26, if only one of the basic colors of the inkjet process is necessary an average print layer thickness 28 for two base colors applied to the same surface elements and a thick print layer thickness 30 for three base colors. If four basic colors are used, the result is an even thicker print layer.

Preferably, the surface is printed such that the maximum print layer thickness is smaller than the maximum depth of the exposed pores, which in Fig. 2d is denoted by -T. In this way, the three-dimensionality of the surface of the component 10 in inkjet printing is maintained.

Fig. 2e shows the printed component 10 according to Fig. 2d with an additional cover layer 32, which can also be applied by the ink jet method or by another method and forms, for example, a hard protective layer, which additionally protects against the effects of ultraviolet light or chemical influences. The cover layer 32 may, as in Fig. 2e be relatively thin so that it does not change the three-dimensionality of the surface. It can also be so thick that it covers the three-dimensionality and is just what is desired for reflective surfaces. Such surfaces also give a three-dimensional impression when considered accordingly.

After its printing, the sample pattern M is detected superficially in the detection station N, for example, similar to the color detection station F the Color values of the customer request template A are recorded, and are compared in the computer system H with the color values of the customer request template A. In the event of a deviation, the data record for controlling the inkjet printing device L can be modified accordingly, so that a new sample can be printed. Once the correspondence between the appearance of the surface of a printed sample sample and the appearance of the customer request template A is satisfactory, the control data set for controlling the inkjet printer L is set.

The Wunschholzmusterdatensätze B or a record as it is used to produce a sample pattern M, initially is often only for printing a predetermined limited area. If large areas are to be printed, it is necessary to generate from such a data record a data set with which a sufficiently large area can be printed using the inkjet method. This will be explained below on the basis of Fig. 3 explained, in which at 40 a basic data set is designated, which is suitable for printing a given by him area, in the example shown a rectangle. The foundation data set is preferably a dataset containing essentially only the grain of the desired wood. In order to be able to generate a data record 42 of arbitrarily large extent with the basic data record 40, which has a predetermined limited area, the basic data record 40 is respectively mirrored and combined with the mirrored basic data records in such a way that steady grain crossings are achieved at the edges, so that the impression arises that the entire grain of the data set 42 is obtained from a single wood surface.

If surfaces are to be printed, which are larger than the area to be printed with the basic data set 40, the color processing of the basic data set takes place only after generation of the large-area data set 42, since otherwise no continuous transitions at the edges of the mirrored basic data sets are guaranteed.

With the large-scale and color finished record 42, a large plate 44 can be printed, which was pretreated in the pretreatment station D, as described. From the large-area plate 44, in the packaging station N (FIG. Fig. 1 ) Items are assembled, for example, parquet elements 46, kitchen front elements 48, etc. The assembly can be made directly according to customer requirements. The made-up units can give the impression that they all come from the same piece of wood, giving them an aesthetically peculiar, valuable and appealing appearance. The large-area data set 42 can also be used for printing on the surfaces of cuboids 50 or other three-dimensional components, wherein the surfaces of the different sides merge into one another continuously.

LIST OF REFERENCE NUMBERS

10

component

12

body

14

veneer

16

pore

18

pore

20

fiber

22

working fluid

24

surface

26

thin print layer thickness

28

average print layer thickness

30

thick printing layer thickness

32

topcoat

40

Basic data set

42

record

44

plate

46

A flooring element

48

Kitchen front element

50

cuboid

A

Customer request original

B

Desired wood pattern data records

C

Nutzholzlager

D

pretreatment station

e

ScanStation

F

Color detection station

H

Computer system

K

control device

L

Inkjet printing device

M

sample pattern

N

Konfektionierstation

Claims (8)

1. Method for producing a component having a real wood surface which is printed by means of an inkjet printing process such that its appearance corresponds to that of a model having a grain and porosity corresponding to a predetermined desired wood type and having a predetermined colour, comprising the following steps:

   - providing the model,

   - entering model data into an EDP system, which data describes the appearance of the surface of the model,

   - providing a component having a timber surface, the porosity of which is similar to that of the predetermined desired wood type, characterised by printing the timber surface in an inkjet printing process corresponding to the model data such that the porosity-dependent three-dimensional surface structure of the timber surface is maintained at least in part,

   the reference tonal values of a printed pattern of the timber surface being recorded and compared with the reference tonal values of the model surface, and the data used to control the printing being readjusted if there is a difference in the reference tonal value.
2. Method according to claim 1, wherein the model surface is scanned into the EDP system while primarly recording the half tones and midtones thereof, and reference tonal values of the model surface are recorded and processed in the EDP system, together with the scanned-in data, into control data for the inkjet printing.
3. Method according to claim 1, wherein a desired wood pattern having a surface made of the predetermined desired wood type is provided, the surface of the desired wood pattern is scanned into the EDP system, while primarly recording the half tones and midtones thereof, to produce a desired wood pattern dataset, and reference tonal values of the model surface are recorded and processed in the EDP system, together with the scanned-in data, into control data for the inkjet printing.
4. Method according to claim 3, wherein the surface of the desired wood pattern is precision-ground before the scanning and, after the precision grinding, grinding residues are removed such that the three-dimensional surface structure of the desired wood surface is exposed.
5. Method according to any of claims 1 to 4, wherein the timber surface is the surface of a cut or rotary-cut veneer.
6. Method according to any of claims 1 to 5, wherein the timber surface has a basic tone that is not darker than that of the predetermined type of fine wood.
7. Method according to any of claims 1 to 6, wherein the timber surface is precision-ground before the printing and grinding residues are removed such that the three-dimensional surface structure is exposed.
8. Method according to either claim 4 or claim 7, wherein the precision grinding takes place in a plurality of steps, including a step that takes place in between grinding steps and in which the surface is wetted.

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