GENERAL FIELD OF THE INVENTION The invention in general pertains to methods for decorating a surface of a rigid carrier, in particular methods to individually colour separate segments of the carrier, such as known for example from painting preformed mandala patterns on glass, rock, board or wood.

BACKGROUND OF THE INVENTION

Painting preformed patterns on carriers is a common technique, commercially known i.a. as“painting by numbers”. In the known process, typically a painting template is created from a picture, e.g. uploaded by a customer to a central server of a company producing the template. Then a computer program converts the picture into a line pattern forming contiguous segments having individual shades of colour, and numbers every shade. The generated lines and numbers will be applied to a carrier such as a canvas, glass or wood panel using for example an inkjet printer. The result looks like a labyrinth of individual segments. As the numbered segments are individually painted, it becomes an individual picture corresponding to the original picture. Other technologies are also available for providing the line pattern on surfaces, such as alternative printing technologies or even manually applying the line pattern. The type of technology typically used depends i.a. on the type of carrier.

The individual painting of the various segments is particularly difficult on rigid carriers having an outer layer made of a porous fibrous material, such as a wooden panel or a panel made from recycled wood or paper. Due to the porous fibrous constitution, the material has superficial and internal channels that act to transport the paint by capillary forces beyond the borders of the segments. In other words, the paint is drawn into the structure away from the exact location of applying the paint, which is particularly disturbing when applying paint along the border of a segment, that is, when the paint flows into or onto the neighbouring segment. The extent to which this happens, i.e. the distance over which the paint is drawn into the structure away from the site of application while still being visible with the naked human eye, depends i.a. on the exact type of material, the exact type of paint (aqueous or non-aqueous, the viscosity, pigment load etc.), the method of painting, and the skills of the painter (typically in case the painting is done manually). However, to consistently make sure the paint does not spread outside of the segment for which it is intended is very difficult, if not impossible, for a rigid carrier having an outer layer of a porous fibrous material.

Although many types of carriers are used for this type of painting, the main type of carriers are flexible carriers like paper or canvas (optionally lain on board). Since these materials have been used for ages to allow high quality painting, the materials have been optimized to decrease the effect of unwanted spreading of paint by using all kinds of sophisticated coatings. These coatings however are not suitable for arriving at the same effect for rigid carriers having a porous fibrous outer layer such as wood panels, laminates of wood, panels made from recycled paper or cartons (such as FlatCOR panels, available from ECOR, San Diego USA) and panels made of the fibrous residue of sugarcane, beets, grain etc. Although such panels can be made non-porous by providing an impermeable veneer, or by impregnating the porous material with phenolic resin, melamine, acrylic, urea or other resins and/or blends thereof, this makes the carrier far less suitable for durably applying paint, in particular by manually applying paint in a non-factory (e.g. a household) environment, such as for example in a D.I.Y. setting using simple brushes.

OBJECT OF THE INVENTION

It is an object of the invention to provide a way that enables improved methods of decorating a surface of a rigid carrier having an outer layer made of a porous fibrous material. SUMMARY OF THE INVENTION

In order to meet the object of the invention, a method for decorating a surface of a rigid carrier having an outer layer made of a porous fibrous material has been devised, the method comprising as is known in the art the provision of a line pattern forming contiguous segments on the said surface, the pattern comprising borders common for contiguous segments, and thereafter applying paint to the surface by individually painting at least part of the segments, the improvement being that the pattern is provided by cutting through at least part of the outer layer of the porous fibrous material at the said borders using a photonic beam, thereby physically separating the segments from each other at the surface of the rigid carrier.

Applicants have found that using a photonic beam, the fibrous structure of the surface material can be cut through sufficiently, such that the capillary process of drawing liquid paint along the porous fibre structure can be prevented. The advantage of this method is that using a photonic beam, which is precise bundle of high energy, the material can be removed by simply evaporation or burning away (depending on the type of material and intensity of the beam), leaving an open slot in the outer surface. This is a great advantage when comparing the present method with a method using for example a sharp knife to cut through the fibrous structure: using a method wherein a sharp object is actually used to cut through the outer layer leads to at least partly pushing the material of the outer layer upwardly, leading to ribs of material along the borders.

Although this may also prevent paint from being drawn along the fibrous structure, the ribs have to be removed to provide an aesthetic surface. This necessitates an extra process step, potentially leading not only to removal of the ribs but also altering or even damaging the surface structure of the rigid carrier. The non-contact method of the present invention using the photonic beam thus is highly advantageous, also due to the fact that the width dimensions of the slot can be controlled precisely along its length, ranging from the micrometre up to the millimetre range. This is not possible with a contact method using a mechanical means to cut through the outer layer using for example a knife, blade, mill, drill etc. Also, as with the width, the depth can be easily controlled along the length of the slot using art known methods to control photonic cutting beams.

Physically separating the segments from each other at the surface of the rigid carrier in the sense of the invention means that there is (at least) a physical barrier which prevents liquid paint applied on a first segment adjacent the border with a contiguous second segment, from freely flowing onto or into this second segment. Such a barrier in line with the invention is a slot of a predetermined width and depth created by removing fibrous material with the photonic beam. The amount of physical separation needed between the segments to prevent the free flowing of the liquid paint, i.e. the actual width and depth of the slot at the border of the segments, depends i.a. on the type of porous material and type of paint. A more open structure and less viscous paint typically (but not necessarily) needs a larger width and/or depth of the slot. The required width and depth of the slot can easily be established doing routine experimentation to arrive at the required resistance against free flowing of applied paint. Typical required width and depths in natural wood when using acrylic paint is less than 100 - 200pm, for example as low as 40-50pm. In each case, the physical separation is such that the segments remain mechanically connected via the main body of the rigid carrier. In other words, the beam cutting is not such that the segments become separate jig-saw puzzle pieces, but such that at the surface of the carrier slots are made that have a certain depth into the carrier but not completely through the carrier main body.

Applicants have recognised that the provision of the slots and the actual painting may take place at remote locations, the method steps thus being separated in place and time. For example, a customer may order a rigid carrier with a line pattern via the internet, where after the carrier is made at a remote manufacturing location. After actual manufacturing of the carrier by providing the line pattern, the carrier is packed and shipped to the customer, which customer after receipt thereof can paint the carrier at any convenient time and location. Given the option of separating in time and/or place the provision of the line pattern and the actual painting, the invention is also embodied in a method for preparing at a first location a rigid carrier having an outer layer made of a porous fibrous material to be decorated by painting the surface of the material at a second location remote from the first location, the method comprising providing at the first location a line pattern forming contiguous segments on the said surface, the pattern comprising borders common for contiguous segments, and thereafter packing the rigid carrier and shipping it to the second location, wherein the pattern is provided at the first location by cutting through at least part of the outer layer of the porous fibrous material at the said borders using a photonic beam, thereby physically separating the segments from each other at the surface of the rigid carrier.

The invention is also embodied in the carrier itself, i.e. a rigid carrier having an outer layer made of a porous fibrous material, the surface of said material being provided with a line pattern forming contiguous segments on the said surface, the pattern comprising borders common for contiguous segments, wherein in that the pattern consists of slots of porous fibrous material taken away from the outer layer of the porous fibrous material at the said borders, thereby physically separating the segments from each other at the surface of the rigid carrier. The photonic beam enables to take away material at the outer surface to from the slot, instead of pushing away and displacing material when using a sharp knife to cut the borders. Depending on the type of fibrous material, the material can be taken away for example by evaporation or by being burnt.

DEFINITIONS

A photonic beam is a beam of radiant energy whose quantum unit is the photon. Using such a beam in practice typically involves the use of lasers, optics, fibre-optics, and electro-optical devices.

A fibrous material is a material comprising fibres as (one of) its basic constituent(s). Examples of fibrous materials are boards pressed of wood fibres, wood particles, wood chips or of other plant materials.

A porous material is a material having many (at least partly) interconnected small holes, so that liquid or air can pass through the material.

Painting is the art of providing a surface with a pigmented liquid, which liquid dries to become a solid, providing a stable coloured appearance to the surface. Painting can be done using various techniques such as by hand using a (paint-)brush, by a printing process (e.g. inkjet), pressing process (e.g. screen or rotary printing) etc.

A polysaccharide fibre is a macromolecule composed of long chains of at least 10 monosaccharide units bound together by glycosidic linkages. Polysaccharides fibres belong to the class of so called structural polysaccharides (as opposed to storage polysaccharides such as starch and glycogen) and range in structure from linear to highly branched. Examples include cellulose, chitin, arabinoxylan and pectin. Typical polysaccharide fibre based rigid carriers are for example plywood-, oriented strandboard- , particleboard- , and fibreboard objects.

Cellulosic means made from cellulose or a derivative of cellulose (such as for example viscose or rayon).

FURTHER EMBODIMENTS OF THE INVENTION In a further embodiment of the method according to the invention the porous fibrous material comprises polysaccharide fibres (either of natural or artificial origin). Applicant found that in such a material the slots are created by burning away the fibres when using a photonic beam. The advantage is that the walls of the slot (side and bottom walls) are sooted (i.e. covered with a thin layer of soot) after the treatment with the photonic beam. This means that the slot can be very easily seen with the naked eye (in case the carrier is not black) as a dark line, but also, due to the typical chemical and physical properties of soot, this provides an extra barrier for paint to cross, which means that the slots can be made even less deep and wide while still providing an adequate physical separation of the segments.

In yet a further embodiment, the porous fibrous material comprises cellulosic fibres, in particular natural cellulose fibres. Such fibres are highly abundant, relatively

inexpensive, are easy to obtain through recycling of consumer goods such as paper, cardboard, drink cartons etc. and thus have a low environmental foot print. Moreover, they are able to provide a rigid carrier with a natural look which is highly appealing to many people.

In another embodiment the rigid carrier is in essence completely made of the porous fibrous material. In this embodiment the carrier is for example a laminate of wood sheets, or a panel made from recycled and pressed paper or cartons (such as the

ECOR panels). Since some other materials may be needed such as adhesive or resin to laminate the layers, a small percentage of the carrier may be of another type of material. However, at least 85 weight % of the carrier is made of the porous fibrous material in this embodiment, for example 86, 87, 88, 89, 90, 91 , 92, 93, 94, 95, 96, 97, 98, 99 up to 100 (weight) %. In still another embodiment the photonic beam is a laser beam. Laser beams are commonly known in the art for cutting materials and were found to be useful for providing slots in a porous fibrous material for use in the present invention.

In again another embodiment the said at least part of the segments are painted individually by hand. The present method has been in particular useful for a method wherein the segments are painted by hand. Painting by hand gives rise to an increased risk of paint unwantedly arriving at neighbouring segments. This risk can be severely decreased using the present method.

However, in an alternative method the said at least part of the segments are painted individually using a printing machine. Also in such an industrial method, as opposed to a D.I.Y. type method, the present invention may be advantageous, increasing the possibilities of types of materials and paints to be used, without leading to less sharp borders for the various painted segments.

The invention will now be further explained using the following examples.

EXAMPLES

Figure 1 is a work piece provided with a so-called mandala pattern that can be used in a painting by numbers method.

Figure 2 is an experimental set up for providing a line pattern on the surface of a rigid carrier.

Example 1 is a method for preparing a wooden rigid carrier for arriving at a line pattern with physically separated segments.

Example 2 is a method corresponding to the method of example 1 , however using other rigid carriers.

Example 3 describes methods of painting the carrier obtained using a preparation method of the invention.

Figure 1

Figure 1 schematically depicts a rigid carrier 1 provided with a so-called mandala line pattern 100. Once the pattern is cut into the workpiece, it can be used in a painting by numbers method as commonly known in the art, or any other method to paint the various segments.

Figure 2

Figure 2 is an experimental set up of a nozzle system 2 for providing a line pattern on the surface of a rigid carrier 1. The rigid carrier 1 is the work piece into which the nozzle system cuts a line pattern using focussed laser light. For this, the nozzle system 2 comprises a C02 laser 3, which emits laser light 4 into the system. The laser light is reflected onto focussing lens 5, after which the laser light turns into a focussed beam 4’ that is suitable to cut the line pattern into the work piece 1. The system is provided with a guide 6 for allowing gas to enter the system as known in the art for laser cutting devices.

Example 1

Example 1 is a method for preparing a wooden rigid carrier for arriving at a line pattern with physically separated segments, such as for example the line pattern of figure 1. The laser cutting machine used is the BRM100160 (BRM Lasers, Winterswijk, The

Netherlands), a water cooled cutter having a 150W C02 laser source. The settings used for cutting a 5 mm thick piece of multiplex wood are“40 mm per second, 8-20% power”. Using these settings, a line pattern is cut in the multiplex workpiece having a depth of about 0.2 mm and a width of about 0.1 mm.

Example 2

This examples describes the cutting of line patterns in various other materials that can be used as rigid carriers. A further example is medium-density fibreboard (MDF), a type of particle board made of small particles of wood. Using the same laser cuter device as mentioned here above in Example 1 , a line pattern can be cut into the MDF having a depth of 0.3 mm and a width of 0.2 mm.

Yet another example of a rigid carrier that can be used in line with the invention is ECOR FlatCOR panel (ECOR, San Diego, USA). Using the same laser cuter device as mentioned here above in Example 1 , a line pattern can be cut into the ECOR panel having a depth of 0.5 mm and a width of 0.3 mm.

Typical depths that are advantageously arrived at in a porous fibrous material, in particular a material based on polysaccharide fibres such as cellulose fibres, are 0.1 to 1.0 mm. Typical widths are 0.05 to 0.5 mm.

Example 3

In this example various methods of painting the carrier obtained using a preparation method of the invention are described. The surface of the carrier is provided with a line pattern forming contiguous but (due to the laser cutting) physically separated segments on the said surface, is suitable for applying paint to the surface by individually painting each of the segments (or part of these segments).

The segments can be painted by hand, for example using a regular aqueous paint (such as HB65285 HYDRO KLEURLAK) diluted with water until an adequate viscosity is arrived at. Such paint can be applied by hand using a brush (such as the DaVinci Nova Sleper sr.1270). This way, the segments can be individually painted by hand.

In an alternative method, the segments are painted using an automatic inkjet printer. Depending on the type of rigid carrier and the type of ink (aqueous, solvent, hot melt, curable etc) the ink dots are deposited in the segments at a distance of 0.05 to 0.5 mm of the lines of the line pattern.

In still an alternative method, the segments are painted using a screen printer as commonly known in the art.