JP2019048456A - Digital binder and powder-based printing - Google Patents

Abstract

To apply and bond a powder-based colorant to a surface such that digital printing is formed on the surface, in fields of ornamental surfaces of construction panels such as floor panels and wall panels.SOLUTION: In a method and a device for eternally bonding a colorant to a surface, for the purpose of applying a liquid binder 11 to a surface 2 of a panel, the panel is arranged on the lower side of a digital liquid drop applying head 30', a colorant is applied to the surface, a portion of the colorant is bonded to the surface with the liquid binder, a non-bonded colorant is removed, and digital printing is formed thereon, which is subjected to heat and pressure.SELECTED DRAWING: Figure 2d

Description

  The present disclosure relates generally to the field of digitally fabricated decorative surfaces for architectural panels such as floor panels and wall panels. The present disclosure relates to methods and apparatus for applying and bonding powder based colorants such that digital prints are formed on such surfaces.

Embodiments of the invention are particularly suitable for use in floors formed with floor panels comprising a core or body, a decorative layer and, preferably, a transparent abrasion resistant structure layer above the decorative layer. It is
Preferred embodiments are conventional laminate floors, powder floors, wood floors, plastic LVT floors and ceramic tiles. Thus, the various technologies, problems of the known art and the following description of the objects and features of the present invention, by way of non-limiting example, inter alia It is intended for floorings similar to floorings with.

  It should be noted that embodiments of the present invention may be used to generate digital images and / or digitally formed structures on any surface, for example, generally wall panels, ceilings, furniture components, And flat panels such as architectural panels such as similar products generally having large surfaces with high decorative patterns are preferred. The basic principle of the present invention is used to apply prints on paper, foil, textile, metal, solid wood, wood veneer, wood based sheet material, cork, linoleum, polymer material, ceramic, wallpaper and similar surfaces May be

  The following description is used to illustrate the background art and articles of manufacture, materials and methods of manufacture that may include certain portions of the preferred embodiments of the present disclosure.

a) Laminate Flooring Most of all laminate floors are made according to a manufacturing method commonly referred to as Direct Pressed Laminate (DPL). Such a laminate floor comprises a core of 6 to 12 mm fiberboard, a 0.2 mm thick upper decorative surface of the laminate, a 0.1 to 0.2 mm thick lower equilibrium layer of the laminate, plastic, paper or It has the same material.

  The surface layer of the laminate floor is generally characterized in that two separate paper layers are superimposed on one another to obtain decorative and wear properties. The decorative layer is generally a printing paper, and the wear layer is a clear overlay paper containing small aluminum oxide particles.

Decorative paper is the most important of the laminated papers as it gives the visual appearance of the laminate. The weight of the decorative paper is generally in the range of 60 to 150 g / m ² .

The overlay paper is generally made of pure cellulose of delignified pulp based, with a weight of about 20 to 50 g / m ² thin paper. The overlay paper is almost completely transparent after lamination so that the appearance of the decorative paper is visible. High wear resistance can be obtained when the thickness of the overlay paper is increased by a considerable amount of aluminum oxide particles. However, there is a disadvantage that the transparency of the overlay paper is reduced, and the decorative pattern is covered with the grayish layer, and becomes in the way of the printing pattern.

  Decorative paper printing is very cost effective. A rotogravure printing press having a width of 3 meters and having a printing cylinder capable of operating at a maximum speed of 600 m / min is used. Printing cylinders are generally made by conventional mechanical engraving. Recently, digital laser engraving has been introduced which speeds up the development of the decoration and improves the quality of the decoration. In many cases, a solventless ink containing an organic pigment is used, and the surplus ink is reused.

  Printed decorative paper and overlays are commonly impregnated with melamine formaldehyde resin, called melamine resin, and laminated to the HDF core in a large discontinuous or continuous laminate printing press, where the high temperature (about 170 ° C.) and Curing of the resin under high pressure (40 to 60 bar) and lamination of the paper to the core material take place. An embossed printing plate or steel belt forms the surface structure. Structured paper may also be used as a press matrix. Embossing is applied in register with the pattern on a high quality floor. The depth of embossing is limited to 0.1 to 0.2 mm (100 to 200 microns).

  Laminated floors may also be manufactured by direct printing techniques. One advantage is that the pressing action can be avoided, thus eliminating the need for printing paper to provide the decorative surface. A fluid printing ink is used which prints a decoration on a core pre-sealed by a multi-color printer equipped with rollers, the print being covered with a transparent protective wear layer which may be an overlay, a plastic foil or a lacquer. This manufacturing process is very complicated and can only be cost effective in mass production.

  As an alternative to direct printing techniques, digital printing techniques may be used which are more flexible and can be manufactured economically even in low volume production. The difference between these two methods is mainly that the printing steps are different, and a digital non-contact printing process is used instead of printing rollers.

  Digital printing may also be used for printing on paper sheets used in conventional laminate production and laminated under heat and pressure. Digital printing may be performed before or after impregnation. Thus, digital printing prior to impregnation complicates printing and impregnates in small amounts is not cost effective because the paper may expand and contract during the printing impregnation step. Printing after impregnation onto melamine impregnated paper is very difficult because pigments coated on the melamine surface float during the pressing step when the melamine resin is in the liquid phase state. Such a problem is preferably that the base paper containing the base color is applied and fixed to the core prior to printing, and the resin from the impregnated paper penetrates into the base paper under the base paper and / or over the base paper during the pressing step It may be partially eliminated by the method of applying impregnated paper or melamine powder.

  Also, the laminate floor may have a surface of paper or plastic foil, and such foil material may be digitally printed. In general, a wear resistant protective clear layer, which is a polyurethane lacquer, is used to cover the printed decoration.

b) Powder bed (WFF)
New "paper-free" with a solid surface now called WWF (Wood Fiber Floor (WFF)), which comprises a substantially homogeneous powder mixture of fibers, binders and wear-resistant particles Floor types are being developed.

  The powder mixture may comprise aluminum oxide particles, melamine formaldehyde resin and wood fibers. For most applications, decorative particles such as, for example, colored pigments are included in the mixture. Generally, all these materials are applied in dry form as a mixed powder on an HDF core and cured under heat and pressure to a 0.1-1.0 mm solid layer. The powder is stabilized with moisture and an IR lamp to form an upper skin layer similar to the paper layer prior to pressing so that the powder does not blow off during the press. Thermoplastic particles may be used instead of melamine formaldehyde powder and wood fibers.

  Several advantages may be obtained over known techniques, in particular conventional laminate flooring, such as increased wear and impact resistance, deep embossing, increased production flexibility and lower costs. Embossed depths of 0.2 to 0.7 mm can be easily obtained.

Powder technology is very suitable for producing decorative surface layers which are copies of stone and ceramic. So far, for example, it has been difficult to create designs such as wood decorations.
However, with the recent development of digital powder printing, it is possible to create any type of very sophisticated design by injecting the ink into the powder before pressing. Because no impregnation is required, the various problems associated with paper impregnation can be completely eliminated. The surface structure is made in the same way as in the case of a laminated flooring with a structured printing plate, a steel belt or an embossed base paper pressed against a powder. The main advantage is that the powder provides a base color as compared to other digital printing techniques and that the ink can penetrate the powder, so there is no need to provide a protective layer on the print. However, this penetration is quite limited as it will bind to the particles to which the ink drop first strikes, mainly the wood fibers. High abrasion resistance can be obtained if several printing powder layers are applied one over the other or if a powder overlay is used as a protective layer provided on a digital print.

c) Melamine formaldehyde resin The basic substance of the laminate bed and the WFF bed is a thermosetting melamine formaldehyde resin used as a binder. Melamine resin or melamine formaldehyde resin (generally melamine for short) is a rigid thermosetting plastic material made from melamine and formaldehyde by polymerization. Such resins, hereinafter referred to as melamine, have three basic steps. These steps, step A, step B, step C, are described in Principles of Polymerization, George Odian, 3rd edition, and, in particular, the same document, which includes pages 122-123, is incorporated herein by reference. Incorporated by reference. The first uncured stage A is a stage in which melamine, formaldehyde and water are boiled to obtain a liquid content of about 50% dry content.
The second semi-curing step B is a step obtained when a liquid resin is used, for example, to impregnate the thermally dried overlay paper after application of the liquid resin. The molecules have begun to crosslink, but in the final stage the resin can be cured if the resin is dried with heat for about 90-120 ° C. for a fairly short time, eg, 1 minute.

  Stage B may be obtained by blowing a liquid resin with hot air so that the droplets are dry, dried comprising round spherical small particles about 30 to 100 microns (0.03 to 0.10 mm) in diameter A semi-cured melamine formaldehyde powder is obtained.

  The final third full curing stage C is the stage obtained, for example, when melamine impregnated paper or WFF powder is heated to about 160 ° C. under pressure for 10 to 20 seconds. The dried melamine formaldehyde resin softens, melts and hardens in a fixed form as the temperature rises during the press. The curing is dependent on temperature and heating time. Curing may be obtained at a lower temperature for a longer time or at a higher temperature for a shorter time than described above. The spray dried melamine powder may be cured at high temperature.

d) Wood floors Wood floors are made in a very different way. Conventional solid wood floors have been developed as engineered floors that apply a wood ply to a core made of wood lamella, HDF or plywood. Most of such floors are distributed in the factory as pre-finished floors with several layers of clear layer coatings on the wood surface. The coating may be applied using a UV curable polyurethane, oil or wax. Recently, wood flooring using digital printing patterns has also been made which improves the texture of wood grain structures of inferior surface quality.

e) Ceramic tile Ceramic tile is one of the main materials used for flooring and wallpaper. The raw materials used to form the tile consist of clay minerals, feldspar and the chemical additives needed in the forming process. One common method of making ceramic tiles uses the following manufacturing steps. The raw materials are crushed into powder and mixed. In some cases, water is added to wet-mill the material. Remove water with a filter press and spray dry to a powder. The powder thus obtained is then dry pressed under high pressure (about 400 bar) into tile bodies 6-8 mm thick. The tile body is further dried to remove residual moisture and the tile body is stabilized to a homogeneous solid material. Recently, a large thin panel dry press has been introduced. The dried particulate material can be pressed at high pressure up to 400 bar, and panels of size at least a few mm thick can be made cost-effectively in the size of 1 m × 2 m. Such panels may be used for wall panels or tops. Also, production time has been reduced from a few days to less than an hour. Such panels may be cut and molded with manufacturing tolerances superior to conventional methods, and may be placed floating using a mechanical locking system. One or more glaze layers, which are glass-like substances, are applied to the tile body by dry or wet methods. The thickness of the glaze layer is about 0.2 to 0.5 mm. The glaze layer on the tile may be two layers, first an opaque glaze layer on the tile body and then a transparent glaze layer on its surface. The purpose of tile glazing is to protect the tiles. Glades are available in various colors and designs. There are also glazes that can produce various textures. After glazing, the tiles are fired at a very high temperature (1300 ° C.) in a furnace or kiln. During firing, the glaze particles harden and melt and unite with one another to form a wear resistant layer. Roller screens are often used to create decorative patterns. The contact features of the rotating screen printing have many drawbacks, such as breakage and long setup times. Thus, recently, some tile manufacturers have used digital inkjet printing technology that offers several advantages in place of such conventional printing technology. Generally, oil-based inks are used and the print is applied on a pressed tile body or on a base glazing that is applied in wet form and dried prior to printing. A transparent glaze layer may be applied over the digital print to improve abrasion resistance. Digital non-contact printing means that it is possible to use thinner tile bodies without damage. Other major advantages are the ability to set up in a short amount of time, the possibility of random printing without repeat effects, and the ability to print on a surface of a variable structure or on a tile with diagonal corners. A further situation that has led to the introduction of digital printing technology into the tile industry is, for example, the size of ceramic tiles in comparison to laminated or powder-based floors, which are manufactured as large pressboards of about 2.1 m × 2.7 m. It is mentioned that it is quite small. In the tile industry, small printers with a limited number of printheads may be used, and initial investment can be significantly reduced. Oil-based inks have a very long drying time, and nozzle clogging can be eliminated. Another advantage relates to glazing which provides a base color. In general, it is better to use a smaller amount of pigment to form a tile pattern in the base color than to apply a high wood grain pattern to HDF and paper materials used in laminate flooring where impregnation and lamination create additional problems It's over.

f) LVT flooring Generally, high-grade vinyl tiles called LVT (Luxury Vinyl Tile) flooring are configured as layered products. Because the main part of the LVT floor has a plank size with a woody pattern, the name LVT is somewhat misleading. The base layer is made of several individual base layers containing various mixtures of PVC powder and chalk filler mainly to reduce the cost of the material. The thickness of the individual base layers is generally about 1 mm. The base layer has a thin high quality printed decorative PVC foil on top. On the decorative foil, a transparent wear vinyl layer of a thickness of 0.1 to 0.6 mm is applied. Glass fibers are often used to enhance thermal stability. The individual base layers, glass fibers, decorative foils and transparent layers are fused under heat and pressure in a continuous or discontinuous press. The transparent layer may include a polyurethane coating that provides additional abrasion and staining resistance. Some manufacturers use polyurethane layers applied directly to decorative foils instead of clear vinyl layers. Recently, a new type of LVT floor has been developed, with a base layer thickness of 3 to 6 mm and a mechanical locking system with an edge that allows floating installation. The LVT floor has several advantages over, for example, laminated floors, such as deep embossing, flexibility, dimensional stability, moisture resistance, low soundability. Digital printing of LVT floors is only an experimental step, but if implemented, would offer advantages over conventional printing techniques.

  It should also be mentioned in summary that digital printing may be used for several floor types to decorate. However, due in particular to the high cost of the ink and the high investment costs for industrial printers, the quantities in particular for wood flooring and laminate flooring applications are still very low. The flexibility obtained by digital printing technology is limited by embossing, which is fixed and can not be adapted to various kinds of digital printing decorations. This flexibility reduces ink costs, uses industrial-scale, cost-effective printing equipment, provides high wear resistance without the need for a separate protective layer, and is compatible with various types of digital printing patterns The ability to form different types of embossed structures can be a major advantage.

(Definition of some terms)
In the following description, the visual surface of the floor panel to be installed is referred to as "front side", and the opposite side of the floor panel facing the subfloor is referred to as "back side".

  "Up" means the front side, and "down" means the back side. "Vertical direction" means perpendicular to the surface and "horizontal direction" means parallel to the surface.

"Pigment" means a fine powder of solid colored particles.
"Pigment ink" means an ink comprising a pigment suspended or dispersed through a carrier fluid.

  "Binder" means a substance that binds or contributes to binding two particles or materials. The binder may be a liquid, a powder system, a thermosetting or thermoplastic resin and the like. The binder may consist of two components that react when in contact with one another. One of these components may be liquid and the other may be dry.

  By “matrix”, also referred to as “mat” is meant a material that forms a surface structure that is embossed when the material is pressed onto the surface.

  "Aligned embossing", so-called EIR (Embossed In Register), means that the printed decoration is in alignment with the embossed structure.

  "Digital inkjet printing" refers to the digital control and ejection of droplets of fluid containing colorant from a print head onto a surface.

  "Digital print" means a digital control method that places colorants on a surface.

  The “colorant” is preferably any material (dye, organic or inorganic pigment, any material) that may be used to color the surface by selectively absorbing or reflecting light of different wavelengths. Mean minute colored particles etc.).

  "Panel" means a sheet-like material that is greater in length and width than thickness. Panels broadly include, for example, laminate floors, wood floors, tiles, LVTs, sheet-like wallpaper and furniture components and the like.

  The following describes generally known techniques that may be used to provide digitally printed and embossed surface structures. These methods may be used partially or completely in various combinations with the preferred embodiments of the present invention to create digital prints or digital embossments according to the present disclosure.

  High definition digital inkjet printers use a non-impact digital printing process. The printer has a printhead which "drops" ink droplets from the printhead to the surface with very high accuracy.

  Multi-pass printing, also referred to as scan printing, is a printing method in which the printer head traverses the surface many times to produce an image. Such printers are slow but can produce larger images with one small printhead.

  Industrial printers are generally based on a single pass printing method using a fixed printer head having a width corresponding to the width of the print medium. The printing surface moves under the head. Such a printer has a large capacity and comprises a stationary print head arranged one after the other in the feed direction. In general, each head print prints one color. Such printers may be customized for each application.

  FIG. 1a shows a side view of a single pass digital inkjet printer 35 for industrial use, wherein the digital inkjet printer 35 comprises five digital prints connected via an ink pipe 32 to an ink container 31 filled with inks of different colors. The heads 30a to 30e are provided. The ink head is connected to the digital control unit 34 via the digital data cable 33, the digital control unit 34 controls the application of ink droplets and the speed of the conveyor 21, and the conveyor 21 is a high quality image consisting of several colors In order to ensure that the panel must be displaceable with high precision under the print head.

  FIG. 1 b shows a plan view of the wood grain print P provided on the panel surface 2. In many cases, the surface of the floor panel is embossed to have the same basic structure 17 for several basic decorations as shown in FIG. 1c. In the modified floor, a so-called EIR (alignment embossing) embossing 17 is used which is aligned with the printing pattern P as shown in FIG. 1d.

  The typical width of an industrial print head is about 6 cm, and any length may be printed. A large area of 1 to 2 m may be printed using a digital printer aligned with several rows of print heads. In order to print 5 colors on a 2m wide laminated floor panel, 166 print heads may be required, and if some of the nozzles of one print head are clogged with dry ink, printing can not be performed There are also times when

  In order to define the resolution and print quality of digital printers, the number of dots per inch, so-called DPI, is used. In general, for example, 300 DPI is sufficient for printed wood grain structures of the same quality as those currently used in conventional laminate flooring. Industrial printers can print patterns at resolutions of 300-600 DPI and higher and speeds greater than 60 m / min.

  The print may be a "full print". That is, the visual print decoration is mainly made of ink pixels applied on the surface. In such embodiments, the effect of the powder layer color or paper base color on the visual pattern or decoration is generally limited.

  Also, the print may be a "partial print". Another underlying layer color is one of the colors visible in the final decoration. The area covered by print pixels and the amount of ink used may be reduced, and compared to a full print design, cost may be reduced due to the reduced amount of ink used and the improved printability. However, partial prints are not as flexible as full prints because it is more difficult to change the base color than when full prints are used.

  The print may be based on a surface CMYK color scheme in which white is provided on the surface. The CMYK color is a four-color configuration consisting of cyan, magenta, yellow and black. Combining these colors results in a relatively small color space / color gamut. Spot colors may be added to increase the specific color or full gamut. The spot color may be any color. The colors are mixed and controlled by a combination of software and hardware (print engine / printhead). Also, white may be added to the printer to significantly enhance flexibility.

  CeraLoc Innovation Belgium BVBA, a subsidiary of Valinge International AB, has developed a new technology that can spray digital liquid prints onto powder layers. This new type of "digital injection print", so-called DIP, is printed on powder that is cured after printing. The ink and print are embedded in the hardened layer and not applied on the layer as when conventional printing methods are used. The prints may be positioned at various dimensions in the horizontal direction and at different depths in the vertical direction. This may be used, for example, to produce a 3D effect if clear, preferably bleached wood fibers are used. Also, two-layer printing may be used to enhance abrasion resistance. For example, no overlay protective layer is required which interferes with the original design of gray shadings.

  The DIP method may be used for all powder-based materials that may be cured after printing. However, the DIP method is particularly suitable for use where the powder comprises a mixture of wood fibers, small hard wear particles and melamine resin. The surface layer may further comprise a thermoplastic material, for example vinyl particles, applied in powder form on the surface. This allows the print to be jetted onto the vinyl powder particles. Such materials may also provide improved design and high wear resistance.

  In order to obtain high print quality and speed in powder based layers and other layers as described above, it is necessary to use an appropriate printer head. The printer head has a number of small nozzles that control ink drop ejection and application.

  Industrial inkjet systems are broadly classified as either continuous jet (CIJ) systems or drop on demand (DOD) systems.

  The CIJ ejects droplets continuously from the print head. The droplets pass through the electrode set, which provides charge to each droplet. The charged droplets then pass through a deflector that selects the droplets printed using the electrostatic field and the droplets collected and recovered for reuse.

  The DOD ejects droplets from the printhead only when necessary, and all droplets are applied to the surface.

  CIJ is mainly used for product marking and marking. DOD inkjet technology is currently used in most existing industrial inkjet applications where high quality decoration is required.

The normal size of the ink drop is about 2 to 4 picoliter (= 1 × 10 ⁻¹² liter or 0.000001 mm ³ ). The size of each droplet may vary depending on the type of ink and the type of head, and is usually 1 to 40 picoliter, which corresponds to a droplet having a diameter of about 10 to 30 microns. The smaller the droplets, the higher the resolution of the image obtained. Some printer heads can eject different droplet sizes and print gray scale. Other print heads can only fire one predetermined drop size. Printhead designs that can eject larger drops up to 100 to 200 picoliters or more are also possible.

  Several techniques may be used to eject droplets from the nozzles.

  In thermal print head technology, commonly referred to as bubble jet printing, a series of small chambers use print cartridges each containing a heater. In order to eject droplets from each chamber, a current pulse is applied to the heating element to rapidly evaporate the ink in the chamber to form a bubble, causing a large pressure rise and causing the surface to pass through the nozzle. Advance the ink drop. Most consumer inkjet printers use a thermal printer head. Such thermal printers are generally configured to apply aqueous inks of a viscosity of 2 to 5 centipoise (cps).

  Recently, Memjet has developed a large thermal print head having a printable width of 223 mm and a printing speed of about 20 m / min or more. The print head includes five ink channels and two rows of nozzles per channel. The individual nozzle structures are each approximately 30 microns wide, to achieve 800 dpi, and the nozzles of the second row of each color and the first row are slightly offset to a total of 1600 dpi. The Memjet print head can continuously eject 750 million droplets per second of 14 micron diameter, 2 picoliter droplets. The cost of the print head is less than 10% of the cost of a conventional piezo head with similar capabilities. Such a thermal printer may apply an aqueous material having a viscosity of 0.7 to 1.5 centipoise similar to the viscosity of water (1 centipoise at 20 ° C.). The Memjet print head is equipped with a self-cooling system having a heating element at the center of the ink chamber. As the droplets are ejected, fresh ink flows into the ink chamber and cools the heating element.

  Thermal technology has the limitation that the ink generally needs to have a heat resistance up to 300 ° C., since the embossing process is thermal based. This makes it very difficult to produce pigmented multicolor thermal heads. Because Memjet printheads are designed for dye-based inks, they are not used in applications in the flooring industry or in industrial areas where high quality pigment-based inks are required.

  Most commercial and industrial inkjet printers and some consumer printers use piezoelectric printer head technology, which is the main technology used in the flooring industry. Piezoelectric crystal material (generally referred to as piezo) in the ink fill chamber behind each nozzle is used instead of the heating element. When a voltage is applied, the piezoelectric material deforms to generate pressure pulses in the fluid and push ink droplets out of the nozzle. The piezo print head configuration may use different basic deformation principles to eject droplets from the nozzles. These principles are generally classified as squeeze, bend, press, shear printhead technology. Piezoelectric crystals may be used so that vibration produces an acoustic wave, and the ink breaks up into droplets at regular intervals. Piezo inkjets can use a wider variety of inks than thermal inkjets and can tolerate higher viscosities. The inks generally have viscosities in the range of 2 to 12 centipoise and are very suitable for applying pigmented inks. In many cases, printheads capable of handling high viscosity inks in industrial applications raise temperatures up to 40 ° C. or higher and when low initial viscosity can be below the minimum level required for proper functioning of the printhead. , Is used to reduce the initial viscosity of the ink.

  FIG. 1e shows the appearance of the ink droplet 56 ejected according to the bending state of the piezoelectric material. The piezo print head 30 is comprised of an array of very small holes, commonly referred to as jets 50, from which droplets 56 of ink 58 containing pigment 12 are ejected onto the paper surface.

  The ink 58 flows from the ink container into the ink chamber 52 through the ink inlet 55. An electrical pulse bends the piezo crystal 51 and the film 53. Such deformation results in pressure pulses that eject ink droplets 56 from the nozzles 54. By varying the charge, different droplet sizes may be formed. The diameter of the nozzle is typically about 10 microns. Typical drop volumes are in the range of 2 to 5 picoliters, and the ink spot size 57 printed on the surface will be 10 to 20 microns. Each droplet may contain about 20% pigment. The remaining part is the liquid carrier and the resin necessary to bind the pigment to the surface.

  A digital image includes pixels arranged in a predetermined number of grids, and the pixels are the smallest unit elements of the digital image. This grid is called a raster. The size and shape of the pixels representing the image as a computer file are uniform. The pixels do not overlap each other, and all sides of the pixel are in contact with adjacent pixels. Raster images may be created by various input devices, such as digital cameras. All known printers use raster image processing (RIP) software, which accepts image file input and produces color profile, screened bitmap output, which controls the print head Ink droplets are applied onto the surface to provide the data necessary to achieve a predetermined raster pattern R1-R4 as shown in FIG. 1e.

  Various types of ink may be used. The main components are a coloring colorant, a binder to bind the colorant to the surface, and a liquid to transfer the colorant and binder to the surface with a well-defined droplet from the print head in a non-contact application method And a carrier. The colorant is either a dye or a pigment, or a combination of both. The carrier fluid may be aqueous or solvent based. The carrier fluid evaporates, leaving a colorant on the surface. UV curable inks are similar to solvent based inks, but the carrier fluid cures when exposed to intense UV light.

  The main problem common to all types of inks and print heads is that as the ink dries by evaporation it can dry and solidify causing nozzle clogging. Industrial printers circulate ink through jets to lengthen the amount of time that ink drops can be ejected properly, so-called "decap" time, while the cap on the print head is uncapped and not in use. Some have an ink circulation system. Short decap times and clogging can result in permanent loss of the nozzles and, if a single pass printer is used, undesirable lines can appear across the surface. In particular, pigment-based inks comprising a polymer binder system have the property of being easy to dry, and if the decap time is long and nozzle clogging is eliminated, that property can be a major advantage.

  The dye is a colorant completely dissolved in the carrier fluid and the ink is a true solution.

  The pigment is a fine powder of solid colorant particles suspended or dispersed in a liquid carrier. Pigment-based inks are generally blended individually using colored pigments and several chemicals. The pigments used in digital inks are very fine, having an average particle size of about 0.1 microns. The common size of the nozzles is about 10 to 20 microns, i.e. the pigment particles have a space which can pass through the nozzle channels of the print head. Even so, the nozzles may be blocked by the ink itself and by the pigment forming a mass of particles. High quality pigmented inks should leave the pigment suspended in the carrier fluid for an extended period of time. This is difficult, especially for very low viscosities, which are required for good functionality of the print head. Pigments have an inherent tendency to precipitate and descend in the liquid carrier. In high quality pigmented inks, pigment precipitation generally does not occur. High performance ink circulation systems are used to eliminate these problems associated with high pigment content inks.

  Pigmented inks are generally more light stable, particularly when exposed to UV light, and are more fade resistant than dye based inks. Thus, pigmented inks are used in almost all flooring applications. Water based digital inks containing colored pigments are particularly suitable for flooring applications and may provide high quality printing methods with many different materials.

  In general, pigments do not adhere to smooth surfaces. The pigment is similar to sand particles and can be easily removed from most dry smooth surfaces. Thus, the aqueous carrier fluid is generally mixed with small amounts of some other additives such as binders, for example, pigment adherence to the surface, dot gain, pH level, droplet formation, print head Provides special ink and print properties that provide corrosion resistance, fade resistance, etc. Containing a resin that acts as a binder in the ink composition limits the possible content of the pigment. This is because both the resin and the pigment increase the viscosity of the ink.

Colored pigments as raw materials are particularly cost competitive as large particles of about 1 micron, but the production of pigment-based inks containing microparticles and other inks for digital printers is very complex and expensive In general, the cost of the ink, which can be in the range of about 50 to 100 euros / liter, becomes very high. If high quality full print is applied, about 50 to 100 m ² of floor material can be printed per liter (20 to 10 g / m ² ), in this case the printing cost will be 1 to 2 euros / m ² . The cost of conventional printing floor surfaces where printing cylinders are used is only 10% of the cost of digital printing floor surfaces. In other words, digital printing based on conventional pigment-based liquid inks has little continuity in cost competitiveness when high production flexibility is required.

  Digital inkjet printers use a non-contact method of applying ink to the surface. However, laser printing is generally based on the method of contact in which the laser beam projects an image onto a charged rotating drum called a photoconductor drum. Generally, dry ink particles, called toner, are electrostatically trapped by the charged areas of the drum. The ink comprises, for example, well-defined spherical microparticles of dry plastic powder such as styrene acrylate copolymer or polyester resin mixed with carbon black or colorant. The particles have a diameter of about 8 to 10 microns if a printing resolution of 600 DPI is required. Some laser printers use smaller particles of about 5 microns in diameter. The thermosetting plastic material acts as a binder. The drum prints an image on the paper by direct contact and heat, which fuses the ink to the paper by bonding the plastic powder to the paper. Color laser printers use a pigmented dry ink, typically the cyan, magenta, yellow and black CMYK systems, mixed to provide high quality color images.

  Laser technology using impact methods has not been used to print flat panel surfaces such as floor panel surfaces.

  3D printing is a known technique used to apply and overlay several layers of liquid material, powder or foil on top of one another to create advanced three-dimensional structures. This technology is mainly used to make small composite product prototypes. Hundreds of layers may be applied one on top of the other. Several principles are used to construct a layered structure. According to one main principle, powder layers are applied one on top of the other and several parts are bound by a liquid UV-cured material applied by a digital print head on each powder layer. Unbound powder is removed when the entire structure of the product is formed. Another principle is to use a small glue gun that applies several layers of high temperature liquid plastic material to several layers. 3D printers have very low productivity and it can take several hours just to make a small object. 3D printers are not used to create flat decorations on surfaces to which colorants are applied side-by-side or surfaces that need to be cleaned of non-bonded powder each time a layer is applied. The structure of the layers applied one over the other will be destroyed if a pressing operation is used to cure the layers.

  Dye sublimation printers use long, round, transparent films of red, blue, yellow, and gray cellophane sheets that are connected end to end. Solid dyes corresponding to the four basic colors cyan, magenta, yellow and black are embedded in this film consisting of a plurality of sheets attached to one another, and each sheet contains only one color. The "printhead" contains thousands of small heating elements that generate varying amounts of heat, and the dye is "sublimated" and transferred to the coated paper, where sublimation and liquid are heated when heated. It means becoming a gas without passing through. Such thermal print heads are hereinafter referred to as heated print heads to distinguish such thermal print heads from those used in bubble jet printing, and are heated as they pass over the film. The dye evaporates before returning to solid on paper. By this method, the use of liquid ink is eliminated, and high photographic quality can be obtained with a transparent dye adapted to continuous tone colors. However, this method has many drawbacks. Each sheet must have the same size as the printing surface, and the entire sheet is used even if a small portion of the surface is printed in a particular color. In order to eliminate some of the drawbacks, sublimation thermal transfer imprinting printers have been developed which use special inks containing sublimation particles. Conventional ink jet printers may be used to print the image with such sublimation ink on special paper or foil. The image is then transferred by pressure and heat to the surface with the polyester material or polymer coating.

  Also, thermal printing with a heated print head is used to create digital prints directly on the thermal paper or indirectly using a thermal transfer printing method that applies heat to the thermal transfer film. These printing methods are mainly used to apply a single color to paper, for example to print labels. A heated print head has several advantages. The heated print head is highly reliable because there is no risk of ink clogging and cost is also cost competitive. The main drawbacks relate to the high cost of the paper or transfer film, to the fact that the colors are mainly limited to single color and so on. Thermal print heads are available up to 200 mm wide and resolutions can be provided up to 600 DPI.

  Digital printing is a very flexible method that can provide high quality prints, but the high cost of the ink, especially problems with drying and clogging of the nozzles when using pigmented inks, The need for special protective layers that are costly and not completely transparent makes them completely unusable in industrial applications, in particular in flooring. The main reason for the high cost of the ink is the need to grind the color pigments to very small, well-defined particles and to disperse the particles throughout the carrier fluid. It could be a major advantage if the digital image could be made of colored pigments which may be of larger size and which are not dispersed in the carrier fluid and which are not applied as droplets by the small nozzle. Also, it can be a major advantage if the digital image has higher wear resistance and is formed without a protective layer.

  All floorings mentioned above, in particular most of the digital printing floors, have an embossed surface structure, in particular when the decoratively printed decoration is a wood grain pattern. Heretofore, embossed structures have been provided as separate general structures used for many different decoration types. Nowadays, most floor manufacturers use so-called aligned embossing, where the embossed surface structure is specially formed for each type of wood type and aligned with the printed decoration for embossing. Introduces the (EIR) method. This provides an excellent design that is indistinguishable from natural materials such as wood and stone. Embossing is obtained when the surface is pressed against a structured substrate, which may be a steel plate, steel belt, metal roller, plastic foil or coated paper. The decoration needs to be positioned with high accuracy with respect to the press base material. Such positioning is generally performed using digital cameras and machinery that adjust the final position of the panel to match the decoration prior to pressing. One particular problem associated with laminate flooring is that it is not possible to control the expansion and contraction of the printing paper during impregnation, which may result in variations in the size of the decoration between different impregnated paper sheets. is there.

  Also, the flexibility of digital printing is limited relative to the EIR surface, as the printed decoration must always be adapted to the embossed base material. A feature common to all floors as mentioned above is that all surfaces of the production batch have the same basic structure and can not adjust for any change in the decoration and to adapt to that change. The floor surface provided by such repeated effects of the embossed structure, in particular, is not similar to a wood floor in which all panels in practice have a different design or structure due to the wood grain structure. It is not possible to make a copy of stone or other natural material, as designs and structures are generally perfectly combined, and all panels are different natural material copies.

  Digital inkjet technology is mainly used to gain the advantage of being able to flexibly create high resolution images. However, other aspects of this technology, mainly related to the ability to apply liquid materials with very high precision using non-impact methods, are not fully utilized or developed, and are in production This is especially so in applications where after printing, large sized panels that include surfaces that receive the final shape and characteristics in production steps involving high pressure and heating are decorated.

  It is known that powders applied to the liquid material can be used to create raised portions or images primarily on paper substrates, and that the liquid material can be digitally applied by inkjet. 3D printing, including several powder layers locally connected with digital devices such as ink heads, where excess powder particles not bound are removed in the final step, creates an embossed structure on the panel Are well known techniques that can be used to It is also known that the powder particles may be applied directly on the surface comprising the binder using a non-contact method or indirectly using a contact method in which a transfer method is used It is done. There is also known a combination in which a noncontact transfer method is used and the powder is peeled off from the transfer surface by heat or scraping.

  In U.S. Pat. No. 3,083,116, a powdery resin is sprinkled on a freshly printed sheet, excess powder not adhering to the wet ink is removed from the sheet, and the powder held on the sheet is used. A raised printing process and raised printing powder is described which involves the application of heat to melt the powder, causing the particles of the powder to flow and stick to the sheet. The powder may comprise phenolic resins such as phenol, urea and melamine.

  U.S. Pat. No. 3,440,076 describes a method of forming raised hard printed characters on paper. The ink composition is printed on paper and contacted with the dry material. One of the ink composition and the dry material comprises a thermosetting resin, and the other material comprises a blowing agent and a curing agent. The dry powder material not adhering to the ink is removed, and the resin associated with the print character is cured with heat at a temperature sufficient to melt the powder.

  U.S. Pat. No. 3,446,184 describes a method of forming tacky image copies. Toner powder is applied onto the liquid formation and a portion of the powder is retained by the liquid coating to form a visible image. The unconnected powder is removed and the sheet passes through a heating unit that melts the retained powder to form a permanent image.

  U.S. Pat. No. 4,312,268 describes a method of digitally applying a water-based ink to a continuous web and applying a meltable monochrome powder material to the web and the ink. A portion of the powder material combines with the liquid, and the non-bonded powder material is removed from the web prior to heating the web to dry the liquid and melt the powder material into the web by melting the powder. Fix it. The powder material may be of a particle size in the range of 5 to 1000 microns, and may have a melting point or melting point in the range of 50 to 300 ° C. The powder material may be produced by dissolving or dispersing the dye or pigment in the resin or resin formulation, respectively, followed by grinding, spray cooling or the like to reduce the material to a fine powder. The powder material may provide an abrasion resistant quality to the ink which may include phenolic resin. The liquid material applied through the jet may be clear or colorless water.

  British Patent No. 2128898 describes a method of forming raised decorative portions on a plastic tile. The tiled decorative floor has a design printed on top of the floor. Particles, such as inorganic sand particles, are placed on top of the plastic tile, and at least some of these particles are placed on the tile surface in alignment with the design printed on the tile surface. Excess sand particles are removed. A hardened wear layer is provided on the raised particles and the plastic substrate such that the wear layer surface in the area containing the particles and the area not containing the particles has different gloss characteristics. The process requires that the adhesive coated surface be dusted with particles to keep the particles aligned with the print design on the tile surface.

  U.S. Pat. No. 6,387,457 describes the use of dry pigments for automotive coatings, security printing, general painting and cosmetic printing applications. A binder material is applied to the surface of the substrate uniformly or in a pattern. The binder is applied by ink jet, spray, screen, offset or gravure printing. The dry pigment is applied to the binder material in a pattern or uniformly. The dry pigment material comprises flakes of non-metallic material having a particle size of less than about 100 microns. The foil may be aligned in a direction parallel to the surface of the substrate, and a protective coating may be applied on the foil.

  European Patent Application Publication No. 0 403 264 (A2) describes a transfer method for forming a multi-colored image on a drum which transfers the image to paper. Subsequently, the fluid digital latent image is developed at a development station where the colored powder is applied to the flowable latent image and fixed to produce a permanent visible image. Several digital printheads may be used that print with fluid without dyes, including polyhydric alcohols and subsets thereof ethylene glycol, glycerol, diethylene glycol and mixtures of polyethylene glycol and water. Powder toner is applied to the surface of the paper, and a voltage is applied during this development. The voltage is then reversed to remove the toner from the background area. Fixing is accomplished using conventional copier fuser methods.

  U.S. Pat. No. 5,627,578 describes a method for producing raised characters and graphics in desktop printing applications using a thermographic powder and an inkjet printer to apply a liquid binder . This method is similar to the method described above for generating raised text.

  European Patent Application Publication No. 0 657 309 (A1) describes a multi-color transfer method similar to the method described above, using a transfer paper carrying a pattern formed by inkjet and powder. The transfer method is for ceramic decoration.

  WO 2007/096746 relates to a system and apparatus for transferring particulate material to a surface to be decorated in a contactless or contact manner, in particular for obtaining a decoration on a ceramic tile. A liquid digital pattern is provided by inkjet on a transfer surface, which may be a drum or a belt. The particulate material is applied and bonded to the transfer surface, and only the bound particulate material is transferred to the transfer zone, where the transfer zone is used to peel the particulate material from the transfer surface and to apply the particulate material to the receiving surface. Heat is applied to one particular portion of the transfer surface. The granules may be peeled off by scraping. The main advantage of this method is that only the particles forming the final image are applied to the receiving surface. Also, the main drawback of this method is that in order to obtain a high resolution image, rapid heating, release of particles from the transfer zone and drop of particles onto the receiving surface must be well controlled. is there. Also, high resolution may only be obtained when using heavy particles that fall to the receiving surface by gravity. Particulate materials which may be used in the present invention include non-porous particulates such as fine glassy materials or sintered mixtures, sand, etc., with various particle size distributions ranging from 30 μm to 800 μm, preferably from 50 μm to 150 μm. It is of the type. It also describes transfer printing using the contact method.

  WO 2011/107610 describes a method of creating an embossing or embossing on a floor panel so that expensive printing plates do not have to be used. This method is the same as the known method of making raised print. The same document describes a method of producing a floorboard by printing a curable material to create an embossing on a panel. The embossing may be applied on a basic decorative pattern printed or laminated directly on the panel. The curable material may comprise wear resistant particles. The curable material may be digitally printed on the panel by first printing the liquid in a predetermined pattern and then providing an intermediate which may contain powder. The curable material may be cured by UV radiation or may be a varnish.

  In EP-A 22 13 476 A1, a predetermined pattern may be digitally printed on a carrier with a curable liquid so as to form an embossing decorative pattern to be pressed onto the overlay. Have been described. The curable liquid may be a plastic that becomes rigid after curing, for example a plastic-containing ink. This method is not suitable for floor applications. Digital printing heads can only print very thin layers of about 10 to 20 microns thick. A thickness of at least 100 to 200 microns necessary to form an emboss in the laminate and a thickness of 200 to 700 microns to meet the powder based floor requirements are economically impossible to manufacture.

  WO 2012007230 describes a method for forming 3D structures on furniture or floor panels with digitally controllable devices. A decoration is provided having a flat three-dimensional structure of a powder based coating material comprising one or more layers which are locally solidified by a digitally controllable device under the action of light and heat radiation. Excess coating material that has not solidified is removed in the final production step. The three dimensional structure may be digitally printed. Liquid coating material is applied over the 3D structure as a protective layer.

Most of the known methods are based on applying the powder directly onto the surface containing the binder pattern. Known methods are mainly used to create raised text or three-dimensional decorations that are cured and protected by liquid coating. Such methods are not suitable for flooring applications where it is necessary to incorporate a colored powder on the surface in order to provide sufficient abrasion resistance. These direct application methods are not combined with the pressing step which compresses the applied powder, in particular with the pressing step which hardens the whole surface so that the powder particles melt on the surface.
Some known methods are based on applying the powder indirectly, using a transfer method. The press is used only to transfer the powder from the carrier, and the pressing step does not cause hardening of the powder and the surface.

  The known methods require the use of architectural panels, in particular UV-resistant pigments, and are suitable for producing high-quality multi-colored images on floor panels where the image must be incorporated into the abrasion-resistant surface Absent. It is not known that the principles described above may be used to create digital images on panels cured under high heat and pressure after the printing step, in particular powders, inks and coating methods But need to be adapted to the specific thermosetting resin, wood fiber material and press parameters needed to cost-effectively form high quality multicolored surfaces with abrasion resistance, impact resistance and stain resistance There is also no known method of adapting the known principles to the printing of floor surfaces similar to certain laminates and wood fiber beds (WFF).

  The known methods do not provide a solution to the main problems with the bondability between the powder and the liquid binder applied on the surface. In order to remove the excess particles applied, generally a strong air flow has to be used, which will also remove even the particles to be bound by the binder.

  The above description of the various known aspects characterizes the aspects as described above by the applicant, in which the products, methods and devices described above are used partially or completely in various combinations. It is not admitted that the above description is prior art.

  The main object of at least some embodiments of the present invention is to use a digital ink head, which may apply a liquid substance on the panel surface, on the surface, preferably on the floor panel surface It is an object of the present invention to provide a cost effective and improved printing method for applying colorants in a well-defined pattern.

  A particular purpose is to provide an apparatus for forming digital prints according to the main purpose.

  The above objects are exemplary, and embodiments of the present invention may achieve different or further embodiments.

Embodiments of the invention are based on the main principle of dividing the conventional digital printing method into two separate steps consisting of separately applying a liquid binder and a dry colorant.
Colored particles are applied on the panel surface. Some of the particles are combined by the digitally formed pattern. Other particles that are not bound are removed and the remaining bound particles form a digital pattern. This two-step process may be repeated and multiple colors may be applied to form a highly multicolored high definition digital print. The bound colored particles and the panel surface are pressed to obtain high bondability. The pressing is carried out at high temperature so that the colored particles and the surface are cured into an abrasion resistant layer.

  The advantage compared to conventional digital inkjet printing is that the colored particles are not dispersed in the liquid substance and are not applied by the digital print head on the surface. According to an embodiment of the invention, the print head is only used to apply a pigment-free, cost-effective, predominantly water-based binder. Embodiments of the present invention allow both cost reduction of the ink and digital print head, as well as improved productivity.

  The pigmented colorant may be combined with a very cost effective print head which may be a thermal print head. The colored particles may be pigment coated wood fibers or mineral particles, with a very realistic copy of the wood or stone design, along with such decorative materials arranged in an improved high quality pattern It may be obtained.

  An advantage compared to known powder-based printing methods is that the colored particles are applied directly to the panel surface. Handling and transport of separate printed sheets that can cause powder shedding can be avoided. The positioning of separate surface layers, such as a sheet of paper on the panel, can be avoided, and digital prints can be positioned with high accuracy relative to the panel. The advantage is that the material composition and properties of the surface layer bonded by heat and pressure are used to obtain permanent bonding of the colored particles to the surface, such bonding curing the surface layer on the panel core and It can be obtained in the same pressing step used to laminate. The bonding of particles by the use of pressure, heat and surface properties to provide bonding is superior to most other curing methods used in known powder-based printing methods. A strong bond between the application and removal of the powder may be obtained with a liquid binder that reacts the resin contained in the surface and the powder.

  A particular advantage is that the method is based on a liquid binder which may be a very simple substance which is suitable for bonding with heat and pressure and which allows for a long decap time . Because no solvents or UV curable chemicals are required, a very environmentally friendly and cost effective production method can be provided.

A first aspect of the invention is a method of forming a digital print on a panel having a surface comprising:
Placing the panel below a digital drop application head;
Applying a liquid binder on the surface with the digital droplet application head;
Applying a colorant onto the liquid binder and the surface;
Bonding a portion of the colorant with the liquid binder to the surface;
Removing the non-bonded colorant from the surface such that a digital print is formed by the combined colorant;
Applying heat and pressure to the panel, the surface and the associated colorant such that the colorant is permanently bonded to the surface.

  The surface and / or the colorant may be compressed by the step of applying heat and pressure to the panel, the surface and the associated colorant.

  The liquid binder may include glycol or glycerin.

  The surface may comprise a material that is curable under heat and pressure.

  The surface may comprise a material that is meltable under heat and pressure.

  The surface (2) may comprise wood fibers (61).

  The colorant may be pressed into the surface when heat and pressure are applied to the panel.

  The surface may comprise a thermosetting resin that is cured in the step of applying heat and pressure so that the colorant is permanently bonded to the surface with the cured thermosetting resin.

  The surface may be part of a building panel.

  The surface may be part of a floor panel.

  The surface may be a paper layer or foil.

  The surface may include a powder layer.

  The surface may comprise another color different from the colorant.

  The liquid binder may include water.

  The applied liquid binder may be exposed to IR light or hot air.

  The digital droplet application head may be a piezo ink head.

  The liquid binder may be applied by arranging the droplets in a raster, and the colorant may be combined with several droplets.

  The liquid binder may comprise, by weight, 10 to 70% water and 30 to 90% glycol and / or glycerin.

  The surface may include a dry melamine formaldehyde resin that melts when the liquid binder is applied and bonds the colorant to the surface.

  The colorant may comprise a pigment mixed with a dry binder that interacts with the liquid binder.

  The dry binder may include a thermosetting resin.

  Each of the colorants may have granules containing wood fibers.

  The method comprises the steps of applying a new colorant of a different color onto the first combined colorant and the surface, bonding a portion of the new colorant to the surface using a binder, and The method may further comprise the step of removing unbonded new colorant from the surface such that the combined colorant of 1 and the new colorant are placed side by side on the surface to form a digital print.

  The colorant may be applied by scattering.

  The digital print may include colorants arranged in a woodgrain pattern or a stone pattern.

  The colorant may be applied onto the liquid binder.

  The surface with bound colorant may be pressed at a pressure of about 40 to 60 bar and heated with heat above about 160 ° C.

  The surface and the colorant may be a hard surface having a embossed and embossed structure such that a portion of the colorant is disposed below the top of the surface.

  All known devices intended to apply powder-based printing use flexible sheets such as paper as coated surfaces. There is no known cost effective device that may be used to provide high quality powder based printing on panels by application of digitally formed binder patterns.

A second aspect of the invention is an apparatus for providing digital prints on a panel comprising a surface. The equipment comprises a conveyor, a digital drop application head, a dry ink application station and a dry ink removal station,
The conveyor is configured to displace the panel essentially horizontally below the digital drop application head,
The digital drop application head is configured to apply a liquid blank ink on the surface,
The dry ink application station is configured to apply a dry ink comprising a dry colorant onto the blank ink, and the liquid blank ink is configured to bond a portion of the colorant to the surface;
The dry ink removal station is an apparatus configured to remove the non-bonded colorant from the surface after application of the blank ink and the dry ink, respectively.

  The digital drop application head may be configured to apply a liquid blank ink comprising glycol or glycerin onto the surface.

  The apparatus further comprises a press, wherein the press is not bonded such that at least one of the surface and the colorant is compressed and the surface and the colorant are bonded together. It may be configured to apply heat and pressure to the panel, the surface and the associated colorant when the colorant is removed.

  The digital drop application head may be digitally connected to a digital control unit that controls the application of the blank ink, the speed of the conveyor and the function of the dry ink application station.

  The dry ink application station may include a roller.

  The dry ink application station may include an engraved, embossed, etched, sandblasted or needle-based roller surface and may act as a dispensing device configured to move a predetermined amount of dry ink to the surface .

  The dry ink removal station may be configured to remove the colorant by an air stream.

  The dry ink removal station may be configured to remove the colorant by blowing off the colorant and by aspirating air flow and vacuum.

  The digital drop application head may be a digital piezo print head.

  A plurality of said digital drop application heads may be arranged side by side such that the entire width of said surface is essentially covered by the head.

  The apparatus further comprises a stabilization station configured to supply moisture and heat to stabilize the powder surface comprising wood fiber and dry melamine resin, the stabilization being done before the application of the blank ink. Good.

  The digital drop application head may be configured to apply a blank ink comprising water.

  The apparatus may further comprise an IR lamp configured to dry the blank ink after application.

  The dry ink application station and the dry ink removal station may be configured to apply and remove wood fiber based dry ink particles.

  The invention will now be described in more detail in connection with preferred embodiments and with reference to the attached exemplary drawings.

FIG. 2 illustrates a known method of producing a printed and embossed surface. FIG. 2 illustrates a known method of producing a printed and embossed surface. FIG. 2 illustrates a known method of producing a printed and embossed surface. FIG. 2 illustrates a known method of producing a printed and embossed surface. FIG. 2 illustrates a known method of producing a printed and embossed surface. FIG. 1 illustrates the first principle of an embodiment of the present invention. FIG. 1 illustrates the first principle of an embodiment of the present invention. FIG. 1 illustrates the first principle of an embodiment of the present invention. FIG. 1 illustrates the first principle of an embodiment of the present invention. FIG. 1 illustrates the first principle of an embodiment of the present invention. FIG. 2 illustrates the second principle of an embodiment of the present invention. FIG. 2 illustrates the second principle of an embodiment of the present invention. FIG. 2 illustrates the second principle of an embodiment of the present invention. FIG. 2 illustrates the second principle of an embodiment of the present invention. FIG. 3 illustrates the third principle of an embodiment of the present invention. FIG. 3 illustrates the third principle of an embodiment of the present invention. FIG. 3 illustrates the third principle of an embodiment of the present invention. FIG. 3 illustrates the third principle of an embodiment of the present invention. FIG. 1 shows digital application of a pigment according to the first principle of an embodiment of the present invention. FIG. 1 shows digital application of a pigment according to the first principle of an embodiment of the present invention. FIG. 1 shows digital application of a pigment according to the first principle of an embodiment of the present invention. FIG. 1 shows digital application of a pigment according to the first principle of an embodiment of the present invention. FIG. 1 shows digital application of a pigment according to the first principle of an embodiment of the present invention. FIG. 1 shows digital application of a pigment according to the first principle of an embodiment of the present invention. FIG. 1 shows digital application of a pigment according to the first principle of an embodiment of the present invention. FIG. 1 shows digital application of a pigment according to the first principle of an embodiment of the present invention. Fig. 2 shows a generation method according to the first principle of an embodiment of the invention and a panel with a decorative pattern formed according to an embodiment of the invention. Fig. 2 shows a generation method according to the first principle of an embodiment of the invention and a panel with a decorative pattern formed according to an embodiment of the invention. Fig. 2 shows a generation method according to the first principle of an embodiment of the invention and a panel with a decorative pattern formed according to an embodiment of the invention. Fig. 2 shows a generation method according to the first principle of an embodiment of the invention and a panel with a decorative pattern formed according to an embodiment of the invention. FIG. 2 shows the application of a colorant on a surface. FIG. 2 shows the application of a colorant on a surface. FIG. 2 shows the application of a colorant on a surface. FIG. 1 shows a preferred embodiment of a macro colorant. FIG. 1 shows a preferred embodiment of a macro colorant. FIG. 1 shows a preferred embodiment of a macro colorant. FIG. 1 shows a preferred embodiment of a macro colorant. FIG. 1 shows a preferred embodiment of a macro colorant. FIG. 1 shows a preferred embodiment of a macro colorant. FIG. 1 shows a preferred embodiment of a macro colorant. FIG. 1 shows a preferred embodiment of a macro colorant. FIG. 2 shows the application and pressing of macro colorants. FIG. 2 shows the application and pressing of macro colorants. FIG. 2 shows the application and pressing of macro colorants. FIG. 2 shows the application and pressing of macro colorants. FIG. 2 shows the application and pressing of macro colorants. FIG. 2 shows the application and pressing of macro colorants. FIG. 2 shows the application and pressing of macro colorants. FIG. 2 shows the application and pressing of macro colorants. FIG. 7 illustrates the application of multiple colors with one printhead and the removal of colorant using an intermediate prepress. FIG. 7 illustrates the application of multiple colors with one printhead and the removal of colorant using an intermediate prepress. FIG. 7 illustrates the application of multiple colors with one printhead and the removal of colorant using an intermediate prepress. FIG. 6 shows a transfer printing method and a panel with a preferred surface. FIG. 6 shows a transfer printing method and a panel with a preferred surface. FIG. 6 shows a transfer printing method and a panel with a preferred surface. FIG. 6 shows a transfer printing method and a panel with a preferred surface. FIG. 7 illustrates pattern application of colorants using a method that does not use liquid blank ink to bond the colorants. FIG. 7 illustrates pattern application of colorants using a method that does not use liquid blank ink to bond the colorants. FIG. 7 illustrates pattern application of colorants using a method that does not use liquid blank ink to bond the colorants. FIG. 7 illustrates pattern application of colorants using a method that does not use liquid blank ink to bond the colorants. The figure which shows the digital embossing using a press particle. The figure which shows the digital embossing using a press particle. The figure which shows the digital embossing using a press particle. The figure which shows the digital embossing using a press particle. FIG. 7 shows digital embossing combined with digital transfer printing. FIG. 7 shows digital embossing combined with digital transfer printing. FIG. 7 shows digital embossing combined with digital transfer printing. FIG. 7 shows digital embossing combined with digital transfer printing.

  FIGS. 2a to 2d show a schematic view of an embodiment of the invention and digitize the binder pattern BP or the image by means of an ink head which preferably only applies the binder 11 on the surface 2 as shown in FIG. 2a. It is based on the 1st principle to form. The finely colored particles, for example, the colorant 7 which may also contain the pigment 12, are applied in a dry form, preferably randomly, by means of a second device so as to be in contact with the binder pattern BP. FIG. 2b shows a preferred embodiment in which the pigment 12 in dry form is scattered over the binder pattern BP. FIG. 2 c shows that the binder 11 is linked to the part 12 of the pigment forming the same pattern as the binder 11 and on the surface 2 when the other non-bonded pigments 12 are removed from the surface 2, for example by vacuum. Indicates that a print P is to be formed.

  The above three-step process is referred to as a "print formation cycle" when the process relates to a single color application and as "binder and powder (or BAP) printing" when the process refers to the entire print. The particles are preferably bonded after being separately applied and dried particles comprising liquid binder 11, also referred to hereinafter as "blank ink", and colorant 7, hereinafter referred to as "dry ink" 15, Is a process in which the digital print P of the same or better quality as conventional digital printing techniques can be provided.

  The surface 2 may be a paper layer or a foil or powder layer.

  The surface 2 may be part of a building panel or floor panel 1.

  The binder may be a blank ink 11, preferably comprising a liquid substance applied by a digital ink head.

  The liquid substance may be aqueous.

  The surface 2 with the attached colorant 7 may be heated and pressed.

  The surface 2 and the coloring agent 7 may be pressed and cured to form a hard surface having an embossed structure.

  The colorant 7 may be macro colorant particles larger than 20 microns and may be pressed onto the surface 2.

  The surface 2 may be part of a panel 1 which may be a laminated floor or a wood floor, a powder based floor, a tile or an LVT floor.

  The liquid blank ink may be replaced by a digital heating process in which heat from a digitally heated print head or laser acts on the dried ink and / or the binder contained on the surface.

  The blank ink and the dry ink may be applied in many different ways. The surface 2 may be facing upward or downward, and the blank ink and / or the drying ink may be applied from above or below. The surface 2 with the blank ink may, for example, be facing downwards and be brought into contact with the dry ink layer. Unbound dry ink may be removed by gravity once the surface is separated from the dry ink layer. For the sake of brevity, most of the preferred embodiments are directed upward to show the surface attached to the panel prior to printing. A separate surface 2 not having the support panel 1 may be printed in accordance with the principles of the present invention.

  The method preferably comprises a large amount of colorants, preferably pigments, on a large flat panel to form an advanced large print or decorative pattern with abrasion resistance, impact resistance and UV resistance. The application to be applied and the pattern are particularly suitable for copying wood or stone patterns. Such patterns are generally used, for example, to form the wood grain structures, knots, cracks and various defects found on the surface of trees, and cracks and other defects in the crystal structure in stone patterns. It is formed using one basic color which gives the wood or stone a distinctive appearance and several spot colors. Also, the method prints a printed laminate floor and a powder based floor with a copy of the tile floor including, for example, tiles having different colors and grout lines between the tiles to form a pattern on the tiles Very suitable for

  In contrast to known methods, digital ink heads, hereinafter referred to as "digital drop application heads" 30 ', have not been used to apply any conventional type of ink with colored pigments or dyes. This is preferred as the digital drop application head 30 'does not have to handle expensive inks containing pigment dispersions and binder resins. The blank ink is preferably a substantially clear liquid substance which preferably contains mainly water.

  The blank ink, also referred to as liquid substance, preferably contains no pigment.

  The print provided by the blank ink or liquid material may also be referred to as liquid print P. The liquid print may be formed from droplets of blank ink applied on the surface.

  The colorant is preferably bound to the surface in two steps. The first bonding step is a coating bonding step where the colorant is associated with the binder pattern BP in order to be able to remove excess residual colorant applied to the outer area of the binder pattern. In order to achieve this, the combination of colorants should be sufficient.

  The second bonding step is a permanent bonding to permanently bond the applied bonded colorant to the surface 2.

  The first application bond and the second permanent bond include, for example, an intermediate stabilization step in which the structure of the colorant formed by heat and / or pressure is modified such that a new print formation cycle can be initiated. May be. The intermediate stabilization step allows any new non-bonded colorant applied on the surface during the second print formation cycle to be easily removed from the first print formation cycle also on the surface portion containing the colorant.

  The first application bonding step is preferably obtained using a liquid substance, also referred to as a blank ink, which preferably comprises mainly distilled water or deionized water. Water deposition may, depending on the application, attach the colorant to the surface with some effort to remove non-bonded colorant, especially if only one color is applied. The production cost of such liquid substances is very low and clogging of the nozzle during drying of the binder can be eliminated. Some of the chemicals needed to achieve the viscosity and surface tension of the liquid material may be added, such as glycol or glycerin, which may be required for proper functioning of the print head. Water-soluble polyethylene glycols (PEGs), available at many different molecular weights, are particularly suitable for modifying water, for example, so that a blank ink with the appropriate viscosity to work with a piezo head can be obtained . For example, low monocular formulations such as PEG 400 are particularly suitable for use with blank inks and, preferably, with dry inks or on surfaces comprising thermosetting resins such as melamine. Water and PEG are compatible (compatible) with the melamine resin and can be cured easily and rapidly when heat and, preferably, further pressure is applied. Suitable non-drying solvents compatible with the thermosetting resin should be miscible with water, having a boiling point above 100 ° C. and a melting point below the application temperature. Examples of such solvents are, but not limited to, ethylene glycol, propylene glycol, polyethylene glycol, diethylene glycol, butanediol and glycerin. It is also possible to use a combination. In some applications, the blank ink may contain some other minor amount of chemicals, eg, a wetting agent necessary to prevent bleeding (blanking) when the blank ink is applied to the surface And other chemicals may be included. The blank ink may also be provided with a release agent, in particular the direct application of the colorant, also referred to as "direct BAP printing" as described above, in the first step, the blank ink and the colorant on the transfer surface. A release agent may be provided if it is replaced by a transfer coating which is applied to and pressed against and bonded to the surface, hereinafter also referred to as "transfer BAP printing". Most such additives are cost effective and blank inks can be produced at a fraction of the cost of conventional pigmented inks.

  Most piezo print heads are configured to handle viscosities in the range of 2 to 12 centipoise (cps). Water based blank inks may be easily adapted to meet all possible viscosity requirements.

  Suitable blank inks that may preferably be used in low viscosity printheads configured to operate at a viscosity of about 5 cps, such as Kyocera printheads, for example, are about 75% (by weight) ethylene glycol or 55% diethylene glycol or It may be an aqueous glycol solution containing 50% propylene glycol or 38% polyethylene glycol PEG400. An aqueous glycerin solution containing about 40% glycerin may be used. Deionized water may be mixed with glycerin and glycol. Blank inks suitable for low viscosity print heads may include, for example, about 40% water, 50% glycerin and 10% diethylene glycol.

  Suitable blank inks that may preferably be used in high viscosity printheads configured to operate with a viscosity of about 10 to 12 cps, such as Fuji printheads, for example, are about 95% (by weight) ethylene glycol or 75% It may be an aqueous glycol solution containing diethylene glycol or 70% propylene glycol or 50% polyethylene glycol PEG400. An aqueous glycerin solution containing about 65% glycerin may be used. Deionized water may be mixed with glycerin and glycol. Blank inks suitable for high viscosity print heads may include, for example, about 30% water, 60% glycerin and 10% diethylene glycol.

  The water content of blank inks adapted to low and high viscosity piezo printheads may be further increased if high viscosity glycols, such as polyethylene glycol of higher molecular weight than PEG 400, are used. Preferred blank inks, which are preferably suitable for piezo print heads, may comprise 0-70% water and 30-100% glycol and / or glycerin. Formulations containing 10-70% water and 30-90% glycol and / or glycerin are more preferred. Blank inks suitable for thermal bubble jet print heads configured for very low viscosities, for example, 2 to 4 cps viscosity, may contain more than 70% water.

  All blank ink formulations may contain small amounts, for example about 1% of a wetting agent such as BYK or Surfinol and chemicals such as Actidice to control bacteria and fungi.

  The blank ink preferably obtains coating bond essentially until the final permanent bonding takes place, preferably with heat and pressure, with the resin being part of the substrate and / or dry ink particles. Is a non-curable liquid substance used to bind the colorant. Such blank inks do not bond with the particles when dried or when heat is applied.

  The blank ink may comprise a special curable binder compatible with water, glycol or glycerin, preferably a water based acrylic emulsion. The preferred binder content is 5 to 20%. Acrylic emulsions combine with the particles as the water content evaporates, resulting in strong bonding under high heat and pressure.

  A high water content of at least 50% has the advantage of low material costs. The decap time is quite short, less than one hour from the evaporation of water. The combination of low water content and high glycol or glycerin content significantly increases the decap time. Blank inks with a water content of less than 40% may have a decap time of several hours. If the water content is less than 20%, the decap time can be very long, sometimes exceeding 6 hours. It is possible to use a blank ink containing more than 90% glycol, which may increase the decap time, which may be several days. The blank ink may be made free of water, and the high viscosity printhead may, for example, handle blank ink containing 100% ethylene glycol.

  An ink circulation system may be avoided in industrial printers when blank inks are used which do not contain any pigment dispersions or binders and which are mainly aqueous solutions as described above. This significantly reduces the cost of printing equipment.

FIG. 2 e shows the viscosity cps of a water soluble propylene glycol (PG) solution at a temperature of 20-30 ° C. W1 shows the viscosity of water. Pg1 contains 50% PG and 50% water.
Pg2 contains 70% PG and 30% water. The viscosity of the blank ink applied to the low viscosity print head may vary between 4 and 6 cps within the temperature range of 20-30 ° C. The viscosity of the blank ink applied to the high viscosity print head may vary between 8 and 14 cps, which may be outside the normal operating conditions of the print head. This problem may be solved using printing equipment comprising a temperature control system which is preferably combined with an air conditioning control system to control humidity. The decap time of the water-based blank ink can be long if the relative humidity around the print head exceeds 50%.

  The binder that binds the colorant to the surface may comprise two components. The first binder component may be included in the blank ink. The second binder component may be included in the dry ink or surface and may be activated by the blank ink. Thereby it is possible to use water, for example, to obtain application bonding, stabilization and permanent bonding. Water may be reacted with the colorant or binder which may be included on the surface. It goes without saying that the blank ink may contain a binder which may give the same bond as the two components described above.

  The blank ink may be any surface 2, for example an opaque paper layer, an essentially transparent overlay, a powder layer, a stabilized powder layer, a wood veneer or wood sheet, tile glazing, plastic foil, or a wood or polymer material May be applied to the base color applied to the sheet-like material, which preferably comprises

  Applying surface 2 to a sheet-like material, such as panel 1, provides several advantages. The handling and positioning of the loose coupling layer, which may expand and contract during application of the liquid blank ink, may be omitted. The application bond of the colorant 7 is horizontally directed on the conveyor directly towards the press where the surface 2 is supported by the flat panel and displaced horizontally on the conveyor under heat and pressure causing permanent bonding. As it may be displaced it may be done with very low bond strength. Rolling, cutting and lamination of paper and foil surfaces may be omitted. Some surface and tile glazings, such as uncured powder, can not be handled without the support of panel 1.

  BAP printing on LVT floors may, for example, be made when individual base layers, preferably comprising glass fiber layers, and decorative plastic foils with base color are fused together into a panel. A transparent protective layer may be fused under heat and pressure onto the BAP print and decorative plastic foil so that the dried ink particles are permanently bonded and fused to the surface. The blanking ink may be adapted to avoid droplet floating on a smooth plastic foil. It is preferred if the blank ink has a high viscosity, preferably 10 cps or more.

  BAP printing on ceramic tiles is preferably done when powder is pressed into the tile body to form a panel. Preferably, a glazing having a base color is applied on the tile and a BAP print is applied on dry glazing. The BAP print and tile body are then pressed and applied over the protective clear glazing pressed print. After glazing, the tiles are fired in a furnace or kiln at ultra-high temperatures so that the dried ink particles cure and melt into tile bodies and glazings.

  The embodiment described above forms part of the panel 1 and BAP printing is applied on the surface 2 further including the material composition so that the panel, the surface and the print are permanently coupled when heat and pressure are applied. It is based on the main principles to be done. Such surfaces may comprise thermosetting resins, preferably melamine formaldehyde resins, which are generally curable and fusible mineral materials used in WFF or paper based laminate floors, ceramic tiles, Or used in thermoplastic materials used in LVT beds.

  Direct and transfer BAP printing may also be used on textile surfaces. Dry inks and blank inks may in particular be applied to various textile surfaces. The binder, viscosity and size of the dry ink or colorant may be adapted to properly bind and remove the colorant.

  Application on some specific surfaces may be improved by so-called corona treatment, sometimes referred to as air plasma. It is a surface modification technology that uses low temperature corona discharge plasma that changes the surface characteristics. Corona plasma is created by applying a high voltage to the sharp electrode tip to form a plasma at the end of the sharp tip. Materials such as plastic, glass or paper may pass through the corona plasma curtain to modify the surface energy of the material. It may be surface treated with various types of mineral salts.

  The surface may include a first base color that may be used to create a major portion of a colored visible surface. Powder-based surfaces, which preferably include a thermosetting resin, may be pre-pressed and formed to have a smooth surface that facilitates the application and removal of colorants. Such pre-pressing is preferably carried out under pressure and heat, during the press cycle time which ensures that the melamine resin is at the semi-cured level and is in step B described in the introduction.

  The colorant, in a preferred embodiment, comprises mainly the colored pigment 12 scattered as a dry powder layer over the wet binder pattern BP as shown in FIG. 2b. The pigment may be mixed with other particles, such as melamine powder particles 13, which melt on contact with the liquid binder pattern BP and bond the pigment to the surface. Unbonded dry pigment and melamine powder 13 may be removed, for example, by air flow or gravity, and the remaining wet melamine 13 and color pigment 12 are essentially identical to the binder pattern BP made by the blank ink Form a print P as shown in FIG. The dry ink may have the same material composition as the surface layer 2 of the powder-based WFF bed and may comprise a mixture of woofer fibers, dry melamine formaldehyde resin powder, aluminum oxide particles and color pigments.

  Stabilization of the print may be obtained partially or completely, for example, by exposure to IR, hot air, UV light, microwaves, prepress or similar methods, or a combination of such methods. In this preferred embodiment, the binder, which is water or wet melamine, is preferably stabilized by pre-press bonding the color pigment to the surface 2 by drying the wet melamine or by melting the melamine particles. Ru. The preliminary press compresses the surface of the printing pattern P. A second pattern may be printed with blank ink on surface 2 and a second layer of pigment and melamine powder may be applied over the surface and the first print. This may be repeated, and a high degree of decoration may be created using multiple colors, such that the digital image includes colorants arranged horizontally offset in different planes in different colors.

The blank ink is preferably an essentially clear liquid material that does not disturb the color of the bound colorant. A blank ink with the same liquid substance may be used together with a dry ink containing many different colorants, whereby it is applied, for example, in several steps of intermediate application of the digital pattern formed by the blank ink One print head may be used with the same blank ink to apply several different colors that may also be. This allows one printhead with one ink channel to apply the same blank ink to be used to apply a substantially unlimited number of dry inks that differ in color, structured particle size, etc. The number of print heads can be significantly reduced.
The simple composition of the blank ink makes it possible to use a more cost-effective printhead, since the color pigments are not ejected through the small nozzles of the printhead.

  In some applications, the stabilization step may be sufficient to create a permanent bond. Also, preferably, it is preferable to press and cure the surface under heat and pressure depending on the method used to cure the laminate including the thermosetting resin, the powder-based surface, or the surface including the thermoplastic layer. Final permanent bonding may be performed. A UV curable clear lacquer may be used which is coated on a colorant and cured in a UV oven after application. This transparent layer may be applied in liquid form by means of a roller or by means of a digital piezo head and in one or more steps using an intermediate UV curing. Also, a thermoplastic resin or thermoplastic particles may be used to obtain a first application bond or a second permanent bond. Paper-based or powder-based overlays comprising aluminum oxide and melamine resin may be used as a protective layer and permanent bond.

  The low cost of the liquid substance applied by the droplet application head and the simple chemical composition make it possible to use very simple digital printhead technology to apply the liquid binder substance become. Continuous ink jet (CIJ) may be used, as water reuse is easy and collected droplets may be disposed of without recycling. Because of the ease of water handling in bubble jet technology, cost effective thermal print heads may be used. Because of the absence of pigments and preferably fast-drying resins that need to be handled, the longevity can be enhanced by highly desirable liquid substances that do not interfere with production as has occurred when using conventional pigment-based inks. A very simple, drop-on-demand (DOD) type of very simple piezo head may be used, which can be implemented and whose maintenance can be minimized.

  The binder may include various thermosetting and thermoplastic materials that may be used as particles or chemicals on the surface, in dry ink, or as a dispersion of blank ink applied by a digital droplet application head . Most such materials may be produced in dry powder form or as a liquid dispersion. Preferably, the chemistry that provides bonding after drying is included on the surface or in the dry ink, and the blank ink is a simple liquid chemical that does not use any resin or other chemicals that can clog the nozzle in dry form .

  For example, as an alternative to thermosetting materials such as melamine or thermoplastic materials such as, for example, PVC powder, UV-cured polyurethane may be used in powder form or as a dispersion.

  A UV curable polyurethane material with a viscosity adapted to the digital drop application head 30 'may be used. Aqueous polyurethane dispersions are preferred as liquid materials in digital droplet application heads because they do not cure until exposed to UV light. Polyurethane dispersions are finely divided polyurethane / polyurea discrete polymer particles that have been fully reacted, such particles may be produced to be about 0.01 to 5.0 microns in size, and thus It may be handled with a digital print head or other similar head. Polyurethane dispersions may be mixed with, for example, acrylic emulsions and other emulsions for cost reduction.

  In some applications, preferably, the digital droplet application head, which may be a piezo head, preferably has the ability to eject droplets having a droplet size of about 1 to 200 picoliters or more. The droplet size and droplet strength may vary, and this head may be used to change the color intensity and produce the so-called "gray scale" with the same base color. Larger droplets are associated with a thicker dry ink layer, and smaller droplets are associated with a thinner layer.

  Also, water based adhesives such as soluble adhesives or water dispersible adhesives may be used.

  Other UV curable materials such as epoxies, urethanes, polyesters, polyethers, amine modified polyether acrylics and acrylates of various acrylate oligomers may be used as powdery binders or as dispersions.

  Also, the blank ink may be applied on the surface by a spray nozzle or by an engraving roller.

  FIG. 2 d schematically shows one BAP printing station 40 of a binder printing machine which may be used to make a digital print P on a panel 1 comprising a surface 2, a core 3 and a backing layer 4. Shown in. A blank ink application station 36 comprising a digital droplet application head 30 ′, which is preferably a piezo head or a thermal print head, applies a binder pattern BP with the blank ink 11. Several heads 30 'may be arranged side by side so as to span the width of the surface to be printed. The binder pattern is digitally created in the same manner as conventional digital printing. The colors are separated, and each blanking ink application station 36 primarily applies the same liquid material or blanking ink used to combine one particular color in each print formation cycle. The digital drop application head is connected via a supply pipe 32 to a container 31 with blank ink. The digital drop application head 30 'provides digital control 34 which controls the functions of application of droplets, speed of conveyor 21, dry ink application unit 27 and all other equipment used for binding and removal of pigment, Preferably, it is digitally connected via data cable 33 or wirelessly.

  In this embodiment, the water-based droplets of blank ink 11 acting as a coating binder need to be wet until passing through the dry ink application station 27, which in the preferred embodiment is the scattering station. In this preferred embodiment, the dried ink 15 comprising the colorant of the colored pigment 12 mixed with the resin of the spray dried melamine powder 13 is scattered by the liquid blank ink 11.

  The scattering device moves a predetermined amount of dry ink 15 from the hopper 45 to the surface 2 together with a roller 46 comprising a hopper 45 comprising dry ink 15 and preferably a roller surface 44 which is engraved, embossed, etched or sandblasted And a doctor blade 47 acting as a dispensing device. The roller 46 may have a roller surface 44 with a small needle. Also rotating and vibrating rollers may be used. In some applications, a material removal device may be used, which may be a vibrating or rotating brush 48, with one or more rotating or vibrating mesh 49 that may vibrate or rotate in different directions.

  The doctor blade 47 may be rigid or flexible and may have a cutting edge adapted to the structure of the roller surface. A vibrating mesh or rotating mesh 49 may be formed to spread the dry ink 15 in a predetermined manner, and may be used to screen particles prior to being applied as a layer with one of several nets It may be combined. In order to control the thickness of the layer, the rotation of the rollers, the position of the doctor blade and the speed of the surface that the dry ink is to cover may be used.

  In this embodiment, the liquid blank ink 11 and the dry ink comprising the pigment 12 and the molten melamine particles 13 are preferably positioned behind the digital drop application head 30 'in the feed direction, preferably a high temperature IR lamp 23 When it is displaced downward, it is heated and stabilized.

  In this embodiment, a dry ink removal station 28 based on air flow and vacuum removes pigment 12 and melamine particles 13 which are not wet and not bound by the binder pattern BP so that a perfect color print P is obtained. can get. A dry ink removal station may be positioned behind the IR light 23 or between the IR light and the scattering station 27. This production step may be repeated, and a second scattering station 27 containing another color may be applied by the same print head or by a new print head used in a second print forming cycle A second color may be applied on the agent pattern. The dried pigment and melamine particles removed may pass through a sieve or filter, and may be reused and reused many times.

  The panel 1 with the surface 2 is preferably displaced essentially horizontally below the digital drop application head 30 ′, the dry ink application station 27 and the dry ink removal station 28 by one or more conveyors 21. Ru. Alternatively, the digital drop application head 30 ′, the dry ink application station 27 and the dry ink removal station 28 may be displaced over the panel 1 during BAP printing.

  The dry ink further comprises, in addition to the pigment and melamine particles, wear resistant particles such as small aluminum oxide particles, and fibers, preferably wood fibers, which may preferably consist of bleached transparent or translucent fibers. May be Such dry inks may be used to make a solid print with pigments located above and below each other with binders and abrasion resistant particles above and below the pigments. Blank ink droplets penetrate the dry ink by capillary action and by a combination of surface tension and adhesion, and a greater amount of drying than with conventional ink applications where the pigment is applied as small droplets on the surface It can bind the ink.

  A preferred embodiment of BAP printing is characterized in that the vertical extent of the colorant exceeds the extent of the blank ink drop. Another preferred embodiment is characterized in that the digitally applied blank ink drops penetrate downward and upward from the surface after application. The high abrasion resistance print may be obtained using a printing method comprising a blank ink and a dry ink, preferably incorporating wear particles in the dry ink.

  Multiple print layers may be positioned one above the other, and such an arrangement may be used to further enhance wear resistance and provide a 3D decorative effect.

  Electrostatic or ultrasonic waves may be used to apply and / or remove non-bonded powder particles. An air flow and vacuum that blows off and / or aspirates the particles may preferably be combined with the brush. Generally, all dry and wet methods used for dust removal may be used separately or in various combinations to remove non-bonded dry ink portions. However, dry and / or non-contact methods are preferred.

  Controlled or complete removal of non-bonded dry ink particles is essential for high quality prints with a given decorative image. Advanced removal systems may be used that remove only the colorant, eg, only the color pigment, while the essential portion of the clear melamine powder particles remain on the surface. This may be accomplished by a two step application where the first layer only has melamine resin or particles applied to the surface prior to applying the blank ink with colorant. This first layer is preferably stabilized. The first layer may be sprayed with water and dried, for example by IR or hot air. This separate binder layer, which preferably contains melamine, may be replaced by a pre-impregnated paper which may be used as the surface layer 2 in some applications, for example in some applications, or has a base color or Only non-impregnated paper that does not have may be used as surface 2 of the print application cycle.

  The moisture content of the surface layer needs to be precisely controlled to facilitate removal of non-bonded powder particles. The water content is preferably less than 8%, more preferably 6% or less. The surface layer 2 may be dried by, for example, an IR lamp before application of the blank ink. Special to seal the top of the surface 2 or the combined colorant to form a sealing or release layer that prevents the colorant from adhering to specific parts of the surface layer where blank ink is not applied Chemicals may be applied.

  The floor panel 1 generally comprises a lower balancing layer 4 of laminate, plastic foil, coated paper or similar material. Such an equilibrium layer may be applied as a dry mixture of melamine powder and wood fibers stabilized by moisture and heat prior to pressing. Pigments may be included in the powder mixture to provide a base color. In addition, the equilibrium layer may contain only melamine powder or liquid melamine resin applied directly to the back surface of the core 3, and no paper or wood fiber is required for equilibration of the surface layer. The melamine content of the surface layer is preferably higher than that of the equilibrium layer. The back of the panel is very suitable for providing specific information to floor installers and end consumers. Conventional digital printing or BAP printing may be used to create digital patterns or text on the balancing layer. Installation and maintenance instructions, logos, other types of instructions, graphics and information may be included, and will generally replace the information applied to the package or described in the individual instruction manual. Good. In the case of digital printing and, in particular, BAP printing, in general, the color to be digitally applied may be very cost effective as only one color besides the base color is required. The backing layer may also have a decorative only digital print.

  FIGS. 3 a to 3 d show a second principle in which a dry ink 15 comprising a colorant 7 and preferably a binder which may be melamine 13 is applied on the surface 2 in a first step. 1 shows one embodiment of the present invention based on. After the first step, as a second step, a digital print is formed by a digital droplet application head, which applies the blank ink pattern BP on the dry ink with the blank ink. The main difference between the first principle and the second principle is the order in which the blank ink and the dry ink are applied. According to a first principle, the blank ink 15 is applied in a first step, whereas according to a second principle the blank ink 15 is applied in a second step. The first principle is hereinafter referred to as "binder under powder (BUP)" printing, and the second principle is referred to as "binder on powder (BOP)" printing. BUP digital prints and BOP digital prints may be direct prints or transfer prints as described above.

  These two principles BUP and BOP may provide different images with different color intensities. When applied according to the first BUP principle, the blank ink drop 11 forms an ink spot when it strikes the surface, such ink spot covering an area much larger than the diameter of the drop. Only a portion of the liquid material from the ink spot penetrates into the dry ink from the surface. When blank ink droplets are applied according to the second BOP principle, the droplets first penetrate into the dried ink particles that will bond together in small particle clusters, and the smaller part of the liquid blank ink droplets is surface 2 Where small clusters are attached to the surface. Such an application may be used to prevent bleed in applications where the open structure on the surface dispenses liquid material. Bleeding is not always a problem because it may be used to produce a decorative effect. When the BOP principle is used, the application of the dry ink needs to be controlled with high precision, and the maximum thickness of the dry ink layer is such that the blank ink penetrates the surface through the dry ink layer It needs to be adapted to the size and drop strength. Preferably, the thickness of the dried ink layer does not exceed the maximum penetration level of the dried ink droplets.

  When the thickness of the dry ink layer fluctuates significantly because excess non-bound particles exceeding the penetration level of the blank ink drop applied on the surface are automatically removed when the first BUP principle is used And the liquid material on top of the dry ink particles may dry. The thickness of the dry ink layer may be thicker or thinner than the penetration level of the blank ink drop if the BUP principle is used. This allows the use of a combination of blank ink drop intensity and vertical range of dry ink to produce a change in color.

  Both principles have advantages and disadvantages depending on the application.

  The blank ink 11 may also include water that melts the melamine particles 13 mixed with the pigment 12 or the melamine particles coated under the pigment, for example, when applied in this embodiment. The binder links the pigments forming the same pattern as the binder pattern BP and the other non-bonded pigments are removed. FIG. 3 a shows a dry ink 15 comprising a mixture of melamine powder 13 and pigment 12 scattered on the surface 2. FIG. 3 b shows a digitally applied blank ink pattern BP applied on dry ink. FIG. 3 c shows that the non-bonded pigment and, in this preferred embodiment, the melamine particles 13 have been removed. FIG. 3 d shows a BAP printing station 40 comprising a scattering station 27, a blanking ink application station 36, an IR furnace 23 and a dry ink removal station 28 based on air flow and vacuum.

  The first and second principles may be combined. The blank ink 11 may be applied before or after applying the dry ink 15 and is used to combine thicker colorant layers to create a solid print with a large vertical range and high abrasion resistance It may be done. The binder printing machine may comprise a binder printing station for applying the drying and blank ink according to the first and second principles.

  FIGS. 4 a to 4 d show that digitally controlled thermal activation of the thermosensitive resin to bond the dry ink 15 to the surface 2 so that when the non-bonded dry ink particles are removed, a digital print P is formed. 8 illustrates an embodiment of the present invention based on the third principle in which the bonding of the dry ink 15 is achieved. In a first step, as shown in FIG. 4 a, a dry ink 15 comprising a colorant 7, preferably a pigment 12, may be applied to the surface 2. The binder pattern BP or image is then digitally formed by the drying method and thereafter the non-binding colorant 7 is removed as shown in FIG. 4c. Several methods may be used. FIG. 4 d shows a laser beam 29 for melting or curing a binder which may be mixed with the blank ink or contained on the surface 2, for example a thermosetting or thermoplastic resin 13. Also, the dry ink may be electrostatically attached to the surface by the laser beam. The non-bonded or non-connected colorant is removed to obtain a digitally produced print P. The laser beam is used to apply heat or electrostatically to create the binder pattern before and / or after application of the colorant, according to the first and second principles described above for applying the blank ink May be

  FIG. 4 d shows a binder printing station 40 comprising a dry ink application station 27, a laser 29 and a dry ink removal station 28 based on air flow and vacuum. The laser 29 may be replaced, for example, with a heating lamp which may be used to create an image comprising a large area of the same color of the stone pattern or of the woodgrain pattern.

  FIG. 4d further illustrates that a heated bonding station 26 with a heated print head 80 with several small heating elements may be used to create high resolution prints using a dry bonding method. The heated print head 80 may apply heat directly to bind the particles of the dried ink 15, which preferably comprises a pigment 12 and a heat sensitive resin. The heated print head 80 may also apply heat indirectly by heating the thermal transfer foil 81 which may be in contact with the heated print head 80 and the dried ink particles 15. The thermal transfer foil 81 may be a copper foil or an aluminum foil, and may be provided with small elements having high thermal conductivity, such as elements made of copper or aluminum, which elements are among the individual elements. It is embedded in an adiabatic carrier that prevents the spread of heat. Thermal transfer foil 81 may be used to enhance printability. The heat pulse from the heating print head heats a portion of the foil so that the foil continues to follow the surface and heat is transferred to the dried ink particles.

  Conventional laser systems based on the impact method described above may be used to apply a partial or complete digital print on a construction panel or in combination with the binder printing method described above.

  The principles described above may all be partially or completely combined, and the production line may comprise several digital binder printing stations according to the first, second or third principles.

  Figures 5a to 5h show schematic side views of the application of two different colors according to the first BUP principle. In this embodiment, the spot of the first binder or blank ink 11a, which essentially comprises water, is thermally digital on the surface 2, which may be a stabilized powder layer or paper as shown in FIG. 5a. It is applied by a droplet application ink head. The jet 50 from the head applies a droplet of the blank ink 11 by the nozzle 54 when the heater 59 creates the bubble 60 in the ink chamber 52 and forms a liquid spot 11 a when the blank ink droplet 11 hits the surface 2 . The digital drop application head may also be a piezo head and the water based blank ink may comprise a thickening material. The aqueous blank ink may contain glycol or glycerin.

  A first dry ink layer comprising color pigment 12a and dry particles of binder, in this preferred embodiment melamine particles 13a, is applied onto surface 2 and liquid blank ink spot 11a, as shown in FIG. 5b. Ru. Melamine particles 13a in contact with the wet aqueous droplets melt. A first IR lamp 23a may be used to dry the wet melamine and attach the pigment to the surface, as shown in FIG. 5c, and then unbonded melamine and pigment, as shown in FIG. 5d. The particles are removed to obtain a pigment image or decoration 12a corresponding to the applied binder pattern formed by the blank ink drop 11a. As shown in FIGS. 5e to 5h, the same application is achieved by a new application of the dried ink comprising the pigment 12b of another color and mixed with the melamine particles 13b and the new binder pattern 11b. May be repeated, as shown in FIG. 5h, a two-color image is obtained with two types of colorants or coloring pigments 12a, 12b bound to the two patterns of blank inks 11a, 11b.

  FIG. 6a shows an embodiment in which the digital BAP printing device 40 comprises a digital blank ink application station 36, a dry ink application station 27, IR drying or curing 23, and a dry ink removal vacuum station 28. The BAP printing device 40 is combined with a conventional inkjet printer 35 in this preferred embodiment. Although a portion of the final print is made with a conventional ink jet printer, the BAP printing method may be used with such a combination to make the main part of the digital print. Thus, for example, a cost-effective BAP method that does not require pigment handling by a digital droplet application head applies, for example, 90% of the fully printed digital decorations or pigments that require the creation of a pattern. Ink costs can be significantly reduced. Powder-based beds are particularly suitable for this combination process. The first base color may be provided by the powder layer 2a. A second colored pattern may be applied by a BAP printing device, and a third color may be applied by a conventional digital printing device. A second color stabilization is not necessary as there is no further application and removal of dry colorant. This embodiment is preferably characterized in that a tri-color image is formed by the base color contained in the powder or in the paper layer, the dry colorant and the liquid ink. The same type of printhead may be used to apply the blank ink and the conventional liquid ink.

  Conventional digital printers may be used to apply conventional liquid inks, including blank inks and colorants used as binders for dry inks. For example, one or more ink channels may be filled with blank ink with different drying and / or bonding characteristics than other channels containing conventional pigment-based inks. The blank ink droplets may be in a wet state when the pigmented droplets are dried. Blank inks may be used to apply a colorant that forms the major part of the color of the digital print.

  FIG. 6 b shows, for example, a dry ink 15 comprising a mixture of pigment 12 and melamine powder 13 is applied by means of a scattering station 27 which preferably comprises an embossed roller 22 and preferably a vibrating brush 42. A binder and powder printing apparatus 40 is shown. Unbound colorants, such as pigments and melamine particles, are removed by the dry ink removal station 28 which recycles the mixture 12, 13 or blank ink to the scattering station 27. The air flow can produce a pigment / melamine dust cloud, and only the pigment and melamine powder in contact with the wet binder 11 are bound to the surface 2.

  FIG. 6 c is a cross-sectional view of the floor panel 1 and the BAP printing method is particularly suitable for applying digital BAP printing on the floor panel to the floor panel with a paper or powder based surface 2 and a mechanical locking system. The mechanical locking system comprises a strip 6 which locks with the locking elements 14 at the adjacent edges of another panel to lock the adjacent edges horizontally The element 8 is provided at one edge and in conjunction with the tongue groove 9 at the other edge a tongue 10 is provided at one edge which locks in the vertical direction of the panel. Such floor panels are generally accurate to the highly embossed wood or stone decorations that require a large amount of different colored pigments and to the embossed structure and panel edges where the mechanical locking system is formed. And a decoration that needs to be positioned. In general, the decoration needs to be applied to the edge of the surface part that is removed once the locking system is formed. FIG. 6c shows a woodgrain pattern with first and second surface portions S1 and S2 having different colors. In this embodiment, a second surface portion S2 which mainly extends in the longitudinal direction L of the floor panel is applied on the base layer 2 comprising the first surface portion S1.

  FIG. 6d shows, in this embodiment, a dry ink removal station 28 based on an air flow and vacuum that blows and aspirates particles. One or more vacuum suction profiles 41 with openings that span the full width of the coated dry ink layer may be used to remove essentially all non-bonded dry ink particles 11. Similarly, one or more air knives 42 that span the full width may apply air pressure to the remaining unbound particles so that the unbound particles are released from the panel surface 2 and blown into the vacuum suction profile. The main advantage of this combined method is that high air pressure is more efficient and produces a stronger air flow than vacuum. This method may be used to remove essentially all visible dry ink particles from rough surfaces such as stabilized powder surfaces and rough paper surfaces. Very small particles, such as small pigments or very small wood fibers may also be removed. A two step process may be used to recycle the dried ink. The first removal is performed at a dry ink removal station that includes only a vacuum suction device and removes all very weak links, which may be about 90% or more of the non-combined dry ink particles. Such particles are generally very clean and may be recycled. As shown in FIG. 6d, a second combined dry ink removal station 28 based on vacuum and air pressure removes remaining particles that may partially contain particles from the powder based surface 2 or from a valuable application of another color. May be used to Such particles may not be suitable for reuse.

  All the above mentioned methods may be combined partially or all.

  Figures 7a to 7c describe the application and removal of different sized colorants 64 and the manner in which solid prints P may be formed by pressing particles of dry ink 11.

  The application and removal of colorants is important for high quality images in some applications. In some other applications, it may be preferable for some colorants to remain on the surface, for example, in woody surfaces, in general always some small defects or color spots are randomly distributed Because it may be used to make a more realistic copy of the wood grain pattern. Also, small particles are difficult to see, and in many applications, especially when not applied to a raster pattern, do not interfere with the overall decorative imprint.

  FIG. 7a shows that very small particles of size 10-20 microns and even smaller have a tendency to adhere to surface 2, which may be, for example, an uncoated paper surface comprising wood fibers 61 with a rough fiber structure. Indicates that it is possible. FIG. 7a further shows the pressed part A of the panel surface 2 and the part B not pressed. Blank ink droplets are applied in raster patterns R1 to R4. The non-pressed part B is not bonded by the blank ink with the pigment 12a bonded to the blank ink after removal of the dry ink, but it remains attached to the paper surface even after removal by friction or static electricity, for example. And the pigment 12b. The pressed part A shows a pigment 12c permanently bonded to the surface 2 by pressure and heat. The pigments 12c applied one over the other are pressed into a flat solid print P with overlapping pigments. BAP printing offers the possibility of producing a print corresponding to virtually unclear resolution by using a lower resolution, for example 300 DPI, when applying the blank ink 11. Such a printing pattern may be virtually identical to the actual wood grain structure or the actual stone stone pattern, and the pattern is formed by different natural fibers or crystal structures.

  FIG. 7 b shows, for example, that the problem of adhesion can be eliminated by using a dry ink comprising colorant 7 larger than the conventional pigment 12. The colorant is preferably in the range of 30 to 100 microns. In some applications, depending on the decoration, colorants of up to 300 microns or more in size may be used. Such relatively large macro colorant particles 64 may be formed in a variety of different ways. The macro colorant 64 comprises the pigment 12 attached to the granules 66 according to one preferred embodiment. The granules are spray-dried melamine particles 13 in this preferred embodiment. Such macro-colorant particles 64 of size greater than 20 microns are much easier to scatter and remove than small pigments of sizes less than a few microns. The main advantage is that as shown in FIG. 7c, which is a side view of the macro colorant 64 from the top of FIG. It is to be attached. The spots 57 of the liquid blank ink 11 bind macro colorant particles 64 containing several pigments 12. The pigments 12 are positioned perpendicular to each other on both sides of the granules 66, such an embodiment may provide a deeper print with high color strength and abrasion resistance. Another advantage is that small blank ink spots 57 may be used to combine large amounts of colorants or pigments, the mass and size of these colorants or pigments being indeed digital droplet application It may be larger than the mass or size of the blank ink spot applied as a droplet from the head 30 '. Thus, a large amount of pigment or colorant may be combined with small blank ink droplets. For example, 1 gram of blank ink may bind 1 to 5 grams of colorant. This is a major difference when compared to conventional digital printing where the liquid ink generally contains only 20% pigment and the ink drop always contains a smaller amount of colorant than the ink drop itself. Generally, to apply 1 gram of pigment on a surface, about 5 grams of conventional pigmented ink needs to be applied.

  Figures 8a to 8h show a preferred embodiment of macro colorant particles 64. Such particles may comprise or consist of a plurality of individual colorant particles 69, which may be linked together to form macro colorant particles 64 having a particular color. May be Also, the macro colorant particles 64 may be produced by a combination of several materials and chemicals, and the particles 66 and the pigment contained in the particles 66 or attached to the surface of the particles Have. FIG. 8a shows an embodiment comprising several individual colorants 69, for example pigments 12, which are connected to one another with a binder to form macro colorant particles 64. FIG. Such macro colorants may be produced, for example, by mixing pigment 12 with a liquid thermosetting resin, such as melamine. The mixture is dried, milled and sieved to a macro colorant comprising pigment clusters of a predetermined size.

  Figure 8b shows macro colorant particles 64 having spray dried thermosetting or thermoplastic resin granules 66 containing pigments 12a, 12b in the granules 66 and on the surface thereof. The pigments may be of different colors. The colorant of the granules 66 may be a dye. For example, to produce such particles, a mixture of liquid thermosetting resins, such as melamine and pigments or dyes may be used prior to spray drying. Alternatively, the pigment on the surface may be deposited by mixing the spray-dried particles with the pigment. The pigment adheres to the surface of the spray dried granules. Bonding strength increases when mixing occurs in high humidity and heat, especially when the granules contain melamine. The melamine based particles may be heated in the final stage where the pigment is firmly bonded to the powder. The cure level of the melamine particles may be increased, which prevents bleeding of the pigment during final pressing and curing of the printing surface. The macro colorant particles 64 preferably have a diameter of about 30 to 100 microns, and the pigment content may be 10 to 50% of the total weight. The resin may be melamine or polyacrylate. Also, a binder may be added to the mixture to enhance the bonding between the pigment and the granules.

  FIG. 8 c shows macro colorant particles 64 comprising thermosetting or thermoplastic particles 66 together with the coloring pigment 12 of the particles 66.

Figure 8d shows, for example, that the macro colorant particles 64 may be mineral particles comprising a natural color. Sand powder or stone powder, or different types of minerals obtained from different types of minerals such as oxygen, silicon, aluminum, iron, magnesium, calcium, sodium, potassium and glass powder etc. may also be used Good. The preferred material in some applications for copying stone is sand, which naturally results in particulate material consisting of finely divided rock and mineral particles. Although the composition and color of sand vary widely depending on the local rock source and conditions, the most common types of sand are usually silica in the form of quartz (silicon dioxide, so-called SiO ₂ ) including.

  The preferred embodiment is aluminum oxide 63 which is very suitable for bonding and coating with melamine resin.

Mineral glass particles similar to glazing powders used in tile manufacture, and in particular pigmented glass particles comprising pigments, are very suitable for BAP printing on tiles, but may be used in other BAP applications. BAP prints may be applied on the tile body with a glaze base layer having a base color. Such glaze base layers may be pre-pressed or applied in wet form and dried. BAP prints may be melted into the glaze base layer during tile launch. A transparent glaze layer may be applied over the BAP print. A binder may be applied to the glaze base layer, the colored glass particles or the dried ink such that the blank and the dried ink may be exposed to, for example, IR light or hot air to obtain a coated bond.
Figure 8e shows that essentially all minerals, for example aluminum oxide particles 63, may be coated with a thermoplastic or thermosetting resin, for example melamine 13. A resin may be used to bond the color pigment 12 to the granules 66. Such macro colorants 64 are very easy to apply to and remove from the surface and can provide a very wear resistant print with pigment applied to the top and bottom of the granules 66. The preferred average size of the mineral macro colorant is about 100 microns. This particle size may be used to create an abrasion resistant print with a particle depth of 100 microns. The binder content is preferably 10 to 30% and the pigment content is preferably 5 to 25%, based on the total weight of the macro colorant particles.

  Mineral particles comprising aluminum oxide particles 66 coated with pigment and melamine resin are particularly suitable for use as a dry ink when bonding is performed using a heated print head 80. The aluminum oxide particles have high thermal conductivity, and the melamine resin may be bonded with heat of about 100 ° C.

  FIG. 8 f shows that the macro colorant particles 64 may comprise natural fibers, for example wood fibers 61. Pigments are unnecessary because natural fibers may have a natural color. Fibers from many different woody species may be used, for example, from softwoods such as pine, spruce and hardwoods such as ash, beech, birch, oak and the like. The color may be changed by heat treatment. Cork particles may be used. Such natural colorants may be coated with a binder, preferably a thermoplastic or thermosetting resin, such as melamine. The coating may be used as a binder to enhance the scattering properties and / or to bind the macro colorant to the surface and binder pattern created by the blank ink.

  Figures 8g and 8h show macro colorant particles 64 comprising wood fibers 61 and wood chips 62 coated with resin and pigment 12.

  Fiber based macro colorants may be used to make copies nearly identical to wood. Wood fibers having different colors form a woodgrain pattern on actual wood planks. With the BAP printing method, the same principle can be used with various fibers that actually form a woodgrain pattern, rather than placing small ink drops in a raster pattern. This is shown in Figure 6c. On the surface of the panel 1 there is a woodgrain decoration comprising a first surface portion S1 formed by a base layer 2 comprising wood fibers 61a of a first color. The second surface portion S2 is formed by wood fibers 61b of a second color. Wood fibers of a second color are applied onto the substrate and bonded to the substrate. The base layer is preferably continuous. The second surface portion S2 preferably covers a portion of the first surface portion S1. The base layer 2 may be a thermosetting resin, a colored paper, or a powder mixed with a colored wood-based core. The fibers of the two surface parts S1, S2 are preferably of different average sizes. Preferably, the fibers in the second surface portion S2 are smaller than the fibers in the first surface portion S1. The second surface portion S2 preferably includes a pattern in which the length L is longer than the width W.

  Coatings with resins may be used to bind the pigment to the granules and to bind the macro colorant particles to the surface by means of a blank ink. The coating may be performed in several steps with intermediate drying and curing of the resin. It is preferred that the first coating with a thermosetting resin, for example melamine resin, drying and curing be carried out at a temperature higher than the second curing. The first curing may be performed essentially such that the melamine resin is cured to stage C, where there is no bleeding of the pigment due to the fact that the melamine does not float during the final pressing operation. The second coating is preferably cured to stage B, where the melamine can be melted with the dry ink. Dry ink particles may be produced from wood fibers 61 mixed with pigment and melamine resin, and then pressed under increased temperature to cure the melamine resin. The pressed mixture is ground into small particles, coated with liquid melamine resin and dried in step B so that an outer melamine coating is present. A binder layer may be applied between the pigment and the granules and on the pigment so that the pigment and the granules are completely coated with the binder layer. Several layers of pigments of different colors may be bonded to the granules of macro colorant.

  The dry ink may also comprise macro colorant particles, for example a mixture of several different types of melamine / mineral, melamine / fiber, fiber / mineral etc, the macro colorant's structure and size being special May be used to create various decorations.

  The coating of the granules 66 is preferably applied, for example, in several steps in which particles such as fibers and minerals are mixed in a first step with a resin, preferably a spray-dried melamine and a pigment . The mixture may be applied as a very thin layer, eg, 1 to 3 mm thick, on a conveyor. This mixture is sprayed with water as a third step and dried by hot air or IR lamp. Granules, in this embodiment, fibers or minerals are coated, impregnated with wet melamine, and pigments are bound to the granules. The reduced layer thickness allows the layer to be dried in a short drying time, for example, 1 minute, and the resin may remain semi-cured stage B. The dried mixture is removed from the conveyor, for example by scraping, and the dried flakes are crushed and sieved to the desired particle size. Spray dried melamine particles and water may be sprayed onto the mixture comprising the pigment and particles forming granules 66, for example, replaced with moist melamine.

  The pigment may be bonded to the granules 66 using a binder comprising an aqueous acrylic emulsion.

  In particular, when fibers are used to copy woodgrain patterns and minerals are used to copy stone patterns, the macro colorants produce prints that are very similar to the original patterns of wood and stone May be Conventional rotogravure printing methods using printing cylinders may be used to apply the blank ink to the surface. A dry ink comprising macro colorant particles may be applied to the blank ink and non-bound particles may be removed according to the BAP printing principle described above. Such printing methods may be used to provide advanced prints, including designs that can not be made with conventional inks.

  Macro colorants may be used to create a pattern, preferably a wood or stone pattern of the LVT floor. The BAP printing method may be used to apply a print on the underside or over the core, foil, transparent protective layer. The colorant may be melted into the layer during the pressing operation. Prints in which different layers in the vertical direction are arranged overlapping one another can produce a 3D effect. Printing on transparent layers can produce even more realistic 3D effects.

  Figures 9a to 9e show BAP printing using a dry ink comprising macro colorant 64 with fiber system 61 granules 66 coated with melamine resin 13 and pigment 12. Preferably, the jets 50 from the thermal ink head form blank ink spots 57 on the surface 2, which in this embodiment is a pre-pressed powder layer applied on the core 3, as shown in FIG. 9a. The droplets of the blank ink 11 are applied to the raster patterns R1 to R4 to be printed.

  FIG. 9 b shows a dry ink layer 15 comprising a fibrous macro-colorant 64 applied on the surface 2 and FIG. 9 c shows the dry ink layer when non-bonded macro-colorant particles have been removed. The blank ink 11 penetrates into the dry ink layer 15 upwards from the surface due to capillarity and the nature of the binding agent, and some macro colorants, which lie one on top of the other in the vertical direction, are combined by the blank ink spot 57 It is also good. The horizontal range H2 of the individual colorants, preferably macro colorant particles 64, preferably exceeds the vertical range H1 of the ink spot 57 and the vertical range V2 of the dry ink layer and is non-bonded After removing the particles, it is preferable to exceed the vertical range V1 of the blank ink spot 57. The vertical range V1 of the blank ink spots is generally about 10 microns or less. The vertical range V2 of the applied and bonded blank ink layer may be at least 50 microns or more, preferably greater than 100 microns, after removal of non-bound particles. This is a major difference compared to conventional inkjet printing where the ink droplets contain pigments. BAP printing may form a print that contains more colorant than the amount of blank ink applied by the digital drop application head.

  FIG. 9 d shows the BAP print P after the stabilization step, which in this embodiment is a prepress operation. Macro colorant 64 may be partially pressed onto powder-based surface 2.

  FIG. 9e shows the powder-based surface in the full curing stage after the final pressing operation. Macro colorant 64 is pressed into powder-based surface 2. The print P includes a pigment 12a located in a first horizontal plane Hp1 at the top of the surface 2a and a pigment 12b located in a second horizontal plane Hp2 below the granules 66 and below the first horizontal plane Hp1. The macro colorant 64 comprises pigments 12 a, 12 b on the upper and lower sides of the granules 66.

  The macro colorant particles are randomly applied and preferably offset with respect to raster patterns R1-R4 in which each row and column represents one pixel and one dry ink spot 57. The prints P may be solid prints in which several macro colorants are connected to one another and / or overlapping one another. The BAP print in this preferred embodiment is characterized in that the blank ink 11 is applied to the raster pattern (R1 to R4) and the dry ink 15 is applied randomly with the overlapping colorant 7 or macro colorant 64. . Preferably, the size of the macro colorant particles 64 is such that it covers several pixels in a raster pattern.

  The thickness (diameter) of the fibers 61 is preferably about 10 to 50 microns, and the length may be 50 to 150 microns. This length may exceed 150 microns in some applications, and fibers of about 100-300 microns in length may be used to form a realistic wood grain pattern.

  Figures 10a to 10c show BAP prints that are very wear resistant. A macro colorant 64a comprising particles 66 of aluminum oxide particles 63 coated with pigment 12a and melamine resin 13 is applied on the surface, which in this embodiment is melamine powder and pigment and preferably wood fibres. And the powder-based surface 2a. This surface preferably contains a base color. The layer containing the macro colorant which gives the panel a basic color may form the surface 2a, directly on the wood- or plastic-based core, the tile body, or the surface containing the powder, paper, foil and similar surfaces It may be applied. FIG. 10 a shows macro colorant 64 a bound to surface 2 a by blank ink 11. FIG. 10b shows a second layer of macro colorant 64b comprising pigments 12b having different colors. FIG. 10 c shows the final effect surface with macro colorant, which is pressed onto the powder-based surface 2 a, preferably a transparent layer, which may be applied after the prepress operation and before the final press step, Preferably, it is covered with the melamine layer 2b. The transparent melamine layer 2b may contain bleached transparent wood fibers. The transparent melamine layer 2b may be overlay, lacquer, foil or glazing. High wear resistance may be obtained, since most of the surfaces 2a, 2b, including the particles 66 of aluminum oxide particles 63, need to remain before all the pigments 12a, 12b of the print P are removed. Also, aluminum oxide particles are preferably contained in the powder-based surface layer 2a and / or the transparent melamine layer 2b regardless of the presence or absence of a pigment (not shown). This method may be used to apply the abrasion resistant digital print on many other surfaces such as paper, foil, tiles and other surface layers described in the present disclosure.

  FIG. 11a shows a BAP machine comprising several BAP printing stations 40a, 40b, each used in a print formation cycle applying one particular color. Each BAP station is applied and removed according to the principles described above, with digital drop application heads 30'a, 30'b, combined dry ink application removal stations 27a, 28a, 27b, 28b and a new dry ink layer Thus, the preliminary press units 37a and 37b for stabilizing the dry ink 15 are provided. One embodiment of the unit may be replaced with an IR lamp. One embodiment of the unit 37a preferably comprises a heating roller 38c and a cooling roller 38d, a belt 20 and a preliminary press table 39. These parts may be replaced with only one roller in some applications. The liquid release agent 19 may be applied on the belt 20 by rollers 38a, 38b or brushes or similar devices. Preferably, the drop application heads 30a ', 30b' use the same blank ink 11 to give the print P several colors. This is a major advantage compared to conventional printing. In fact, the BAP printing method allows mixing and production of the final printing ink, together as the colorants 7 from the blank ink 11 and the dry ink 15 adhere to each other on the surface 2.

  FIG. 11 b schematically shows a small BAP printing station 40, for example, one set of aligned digital drop application heads 30 ′, each with one ink channel, and one set An IR lamp 23 or a prepress unit may be combined with several dry ink 15 application stations 27a, 27b, 27c positioned behind the drop application head 30 'in the feed direction. A row of drop application heads 30 'may apply colorants having a variety of different colors. The blank ink, which is preferably an essentially transparent liquid substance, preferably comprises a color different from the first color, preferably comprises a second digital pattern formed by the droplet application head 30 ' . This is the main difference as compared to conventional digital printing, where each print head applies a specific color and this color is always the same as the liquid material applied by the print head. The surface which is part of the surface layer 2 or the floor panel 1 may be displaced in two directions, each cycle being used to apply one specific color with the same drop application head May be The BAP printing station may be equipped with IR lamps or prepress units and a drying ink application station on both sides of the digital droplet application head, and when the surface 2 is displaced below the head 30 'in each direction, different colors may be present It may be applied. This means that, for example, when the panel 1 is displaced below the head 30 ', returned to the initial position and again displaced below the head, three colors are applied by the same droplet application head 30' on the base color It also means good. The speed may be different between the various application steps. This may be used to increase capacity. Woodgrain patterns generally consist of varying amounts of a specific colorant. Because only a small amount of blank ink is applied to the surface, the speed may be increased if the amount of specific colorant is low. A digital control system may be used to optimize the volume and adapt the speed to the amount of blank ink 11 required to form a particular digital pattern. Several alternatives may be used to combine one blank drop application head with several dry ink application and removal stations. After the first print forming cycle, the panels may be displaced vertically or laterally to a conveyor that carries the prints to an initial position. Intermediate stack units may be used. The paper and foil material of the roll may be printed multiple times using the same droplet application head and the same blank ink.

  FIG. 11 c shows a pre-pressing unit 37 which may be used to pre-press a powder layer having a basic color prior to BAP printing. Such a prepress unit may be used to stabilize the print or to press and bond the powder-based backing layer 4 to the back side of the core 3 in advance. When melamine is used as a binder, the heating roller 38c and the preliminary press table 39 may be subjected to heat, for example, 90 to 120 ° C., and the cooling roller 38d preferably has a semi-cured layer 2 It may be cooled to a temperature below 80 ° C. The pressing operation may be performed at a low pressure, for example 5 bar or less, and the pressing time may be up to about 10 seconds. The melamine is pre-pressed into a semi-curing step B which may be further pressed and cured in the final printing operation. Sheet material having a pre-pressed powder-based surface and a backing layer may be produced and used as a pre-finishing panel. Other binders, such as thermoplastic binders, may be pre-pressed at other temperatures specifically adapted to the properties of the binder.

  FIG. 12 a shows that the BAP printing station 40 and the prepress unit 37 are combined into a BAP transfer printing station 41 and may be used in combination to create a digital BAP transfer print P on the surface 2. A dry ink comprising blank ink 11 and colorant 7, preferably pigment 12, is applied onto transfer surface 18, which may be, for example, a steel or plastic belt. The print P is pressed onto the surface 2 by the rollers 38c, 38d and preferably by the prepress table 38. The BAP transfer printing unit may comprise a cleaning device 71, rollers 38a, 38b or brushes for applying the release agent 19, and preferably an IR lamp 23 for drying the release agent prior to application of the blank ink 11. The release agent may be mixed into the dry ink 15.

  The BAP transfer printing method applies the blank ink in high definition without the possibility of bleeding, and the blank and dry ink on the predetermined transfer surface 18 may be particularly adapted for easy application and removal of the dry ink. It has the advantage that it may be applied. This allows, for example, BAP prints to be easily applied on rough surfaces such as, for example, textiles, carpets, various board materials and similar surfaces. BAP transfer printing may be combined with all the other above mentioned methods, for example the one shown in FIG. 11 b where one drop application head 30 ′ is used to apply several colors.

  FIG. 12 b shows a BAP transfer printing station 41 in which the belt has been replaced by a roller 38 comprising a transfer surface 18. The roller preferably comprises a heating zone 25a and a cooling zone 25b. Unbound dry ink may be removed by gravity, which may be combined with ultrasound, vibration or air flow. This method may also be used to apply BAP prints directly on flexible surface 2a, which may be paper, foil or the like. The application may be performed with the press operation or as a separate production step.

  Figure 12c shows a preferred embodiment of the floor panel 1 according to the invention. The panel 1 comprises a backing layer 4 on the back side of the core 3 and an upper surface 2 of the core comprising a sublayer 2c, a paper or foil 2b, and a wear layer 2a on paper. The backing layer 4 and the sublayer 2c may be applied as a dry melamine formaldehyde powder, and the wear layer may be applied as a dry melamine formaldehyde powder containing aluminum oxide particles. The paper may contain a base color. BAP prints or conventional digital prints may be applied on paper. Such drying processes may be used to form very cost effective panels without impregnation of decorative paper or protective overlays. The spray dried melamine particles melt during pressing and impregnation of the paper. It is clear that this drying method may be used for cost reduction even if a conventional decorative paper is used.

  FIG. 12 d shows a method of forming a base layer on a rough core material 3 comprising voids, cracks, fissures or defects 3 a, 3 b. Such core material may, for example, be made of plywood or OSB. The problem is that the thickness of the powder layer is generally the same at the void and at the top of the core surface, and the density of the surface layer is reduced at the surface part where the void is present, thus forming a high quality surface after pressing There is not enough powder amount to do. This problem is achieved, for example, by using a first powder layer 2a which is applied as a filler and which is pressed into the voids by means of rollers or rulers, such that an essentially flat powder-based surface layer 2a is formed. It can be eliminated. The second powder-based layer 2b may be applied onto the first filling layer 2a. The two layers may be pre-pressed as described above, and in the second step a base layer may be formed which may preferably be cured with heat and pressure after being printed with BAP printing. This method may also be used without printing, and only powder layers comprising fibers, binders and preferably pigments may be used. This embodiment is characterized in that the powder content above the voids is greater than the powder content above the top of the core. The powder content may be determined by weighing the powder above the void and above the surface. The base layer comprising the first filler layer 2a and the second powder layer 2b may be covered by a conventional decorative paper, preferably with a protective layer, such as a conventional overlay or clear lacquer.

  FIG. 13a is also adapted that conventional laser printing techniques using a charge to pull away the dry ink particles may be provided with a digital print on the core material 3 including the surface 2 which preferably has a base color. Show good things. A negatively charged dry ink particle 15, which may be a conventional laser toner pigment, is applied by the development roller 72 onto the photoconductor drum 70 in contact with the charge roller 71. The laser beam 29 projects an image onto the charged photoconductor drum 70 and discharges the negatively charged areas to create an electrostatic image. Dry ink particles are electrostatically trapped by the discharge area of the drum. The drum prints the print P on the surface 2 by direct contact. A charge may be applied to the surface or core such that the pigment is released from the drum and applied on the surface. A fuser roller 73 welds the dried ink particles to the surface and bonds the dried ink particles. A roller cleaning device 74 may be used to clean the photoconductor drum. The dry ink particles may comprise a thermoplastic resin or thermosetting resin that may be used to bond the particles to the surface with heat and pressure.

  FIG. 13 b shows that laser printing techniques may be used to apply transfer print P on surface 2. The dry ink particles are applied onto a belt 20 having a transfer surface 18 and released from the photoconductor drum 70 by an electrical application roller 75 which applies a charge to the belt 20. The dried ink particles are melted by means of a prepress table 39 which applies heat and pressure onto the belt 20 and the transfer surface 15. A heating roller 38c and a cooling roller 38d may be used. The belt may be replaced by a transfer roller as shown in FIG. 12b.

  FIG. 13 c shows several other preferred principles that may be used to apply particles on surface 2 in a well-defined pattern, without a digital droplet application head applying a liquid binder for the blank ink Is schematically shown.

  The first principle is a method of creating a base layer comprising at least two different colors. A first layer 2a having a first base color is provided as a powder or as a colored paper. The second color of the dried ink 15 is scattered onto the first base color. For example, a dry ink removal station 28 comprising several air nozzles 77a, 77b which may remove the dry ink particles by vacuum before some of the dry ink 15 particles reach the surface with the base color 2a. Removed. The air nozzles 77a, 77b may preferably be digitally controlled with several valves, and a dry ink pattern P may be formed. This may be repeated and several color patterns may be formed without any digital drop application head or blank ink. This method is particularly suitable for forming patterns which may be used partially or completely for copying wood or stone patterns. This method may be combined with digital BAP printing or conventional digital printing. This method may be used to create high resolution digital prints. The dry ink 15 may comprise a high density of particles, such as minerals, in particular aluminum oxide particles or glass particles, which fall towards the surface 2 in a defined, essentially linear direction during scattering. The precise partial removal may be performed with vacuum as it passes through the air nozzles 77a, 77b. The applied dried ink is preferably stabilized by spraying water before or after application.

  The dry ink particles pass through the electrode set that charges some particles according to the second principle. The charged particles may pass through a deflector 79 that utilizes an electrostatic field to sort particles that are applied to the surface and particles that are collected and recycled to the dry ink application system.

  According to a third principle, a heated print head 80 with a small heating element producing variable amount of heat similar to the print head used in dye sublimation technology or thermal printing technology is used to apply the colorant to the surface It may be used. Several heated print heads 80 may be mounted side by side so as to cover the full width of the printing surface. A low temperature of about 100 ° C. may be used to obtain a coating bond of the dried ink particles. The heat may also be, for example, as high as 200-250 ° C., such heat does not destroy the wood fibers of the paper and the powder-based layer. Such methods may be used to form digital prints using dry ink, where dry ink particles are bonded to the surface of a given digital print. In contrast to known techniques, such heating heads in combination with dry inks may be used to apply a variety of different colors without using thermal paper or transfer foils. Thermosensitive binders, which may be thermosetting or thermoplastic resins, waxes and similar low melting point materials, may be included in the colorant of the surface layer or dry ink. Powders containing dye sublimation particles of different colors may be used as a dry ink. The heated print head 80 may apply digitally controlled heat on a clear portion of the dry ink after application or on the surface layer before application of the dry ink. The heating ink head may comprise a heating element disposed on an essentially flat surface, or on a cylinder that rotates when the surface with the dry ink is displaced below the heating print head. Alternatively, a thermal transfer foil 81 as shown in FIG. 4 d may be applied between the dry ink and the heated print head 80 and may slide relative to the heating element of the heated print head and the ceramic substrate. Unbound colorants or non-evaporated dyes may be removed and recycled.

  FIG. 12 a shows that a heated print head 80 may be used to provide heat on the transfer surface 18 to heat the dried ink 15. The transfer surface may be used as a thermal transfer foil 81. The heated print head 80 may be positioned to apply heat through the transfer surface 18 or onto the dry ink 15 applied onto the transfer surface 18. The heated print head 80 may heat portions of the surface prior to application of the dry ink. The surface may be board material, powder, paper, foil, base coat, transfer surface and all other surface materials described in the present disclosure.

  Figure 13d shows that the heated print head 80 and the dry ink 15 are particularly suitable for forming the digital print P on the flexible thin surface 2, which flexible thin surface 2 May preferably be paper, foil, textile materials and similar materials, generally with sufficient thermal transfer capability and heat resistance to function as the thermal transfer foil 81. A scatter station 27 where powder and heated printing equipment apply blank ink 12 on the surface, a heated print head 80 which applies heat to a portion of blank ink 15 to bond to surface 2 and non-bonded dry ink 15 And a dry ink removal station 28 for removing. In some applications, the prepress unit 37 may use a vacuum or vibration applied to the underside of the surface to enhance the contact between the dry ink particles and the surface during heat bonding. Another heat transfer foil as shown in FIG. 4 d may be used to enhance the printability. The prepress unit 37 may comprise a heated print head and may be heated from above and / or below.

  The heated print head 80 may be substituted for all digital drop application heads 30 'in the embodiments of the present disclosure, with or without the thermal transfer foil 81.

  The three principle embodiments described above are based on the main method in which the colorant is applied as powder in dry form on the surface and combined in a predetermined pattern to form a print. The surface may be transfer surface 18 and three principles may be used to provide a transfer print.

  14a to 14d show a method of forming on the surface 2 a digital emboss, preferably an EIR structure, hereinafter referred to as BAP emboss. A digital drop application head applies a pattern of blank ink onto the carrier 68, as shown in FIG. 14a. Pressed particles 67 similar to the colorants shown in FIGS. 8 d to 8 h may be applied on a carrier 68 which may be aluminum foil, plastic foil, paper and the like. This application may be the same as for BAP printing, and all the methods described above may be used to apply the pressed particles 67 in a pattern on the carrier 68. However, the press particles 67 do not have to be coated with a pigment. Pressed particles 67 may be coated with thermosetting resin 13 or a thermoplastic resin. In some applications, the blank ink is sufficient to provide a coating bond. A heated print head may be used to bind the press particles 67 to the carrier. The carrier 68 and / or the blank ink may comprise a binder. The particles are preferably hard minerals such as aluminum oxide, sand, stone powder and the like. Such particles, which essentially retain their original shape during pressing and are not compressed during the pressing operation, are called hard pressing particles. The size of the particles needs to be adapted to the depth of embossing. For example, particles of about 0.2 mm diameter may be used to create an embossment of at least 0.2 mm depth. The carrier 68 with the press particles 67 is arranged and aligned with the printing pattern P, which may be, for example, a powder or a conventional print or BAP print applied on the paper surface 2. FIG. 14 b shows a pressing step in which the pressing particles 67 and the carrier 68 are pressed into the surface 2 by the pressing table 24. FIG. 14 c shows the embossed structure 17 when the carrier 68 with pressing particles 67 is removed after pressing, and aligned with any type of digital print P without using any conventional printing plate Also a fully digitally formed EIR surface is obtained. A part of the surface structure, in particular the microstructure 16 providing the degree of gloss, may be formed by the carrier. The deeply embossed structure 17 is formed by the press particles and the carrier 68.

  BAP embossing has the advantage that deep embossing can be formed with only one or several BAP application steps, since a large amount of press particles 68 may be applied with a thin layer of blank ink 11. By this method, an embossing depth D is obtained which is deeper than the vertical range V of the blank ink spot 57 which binds the press particles to the carrier.

  Figure 14d shows how to form the surface 2 of the panel with BAP embossing. Blank ink application station 36 applies blank ink 11 onto carrier 68, which in this embodiment is preferably aluminum foil or coated release paper. A dry ink application station 27 is used to apply the press particles 67 onto the carrier. In some applications, an IR lamp 23 may be used to cause application bonding. The press particles are removed by the dry ink removal station 28 and the carrier with press particles is pressed against the substrate by the press table 24. The carrier and press particles are then removed to form a BAP embossed structure.

  This method may be used to form conventional embossing or EIR embossing.

  The surface of the carrier 68 which is pressed to the embossed surface 2 may be coated such that different gloss levels or microstructures may be obtained. Such coatings are preferably applied digitally according to the method described in the present disclosure.

  Pressed particles 67 may be bound to the carrier using any of the methods described above. For example, a heated print head 80 and a laser 29 may be used.

  15a-15d show that the BAP transfer printing method may be combined with the BAP embossing method. Pressed particles 67 may be applied to one side of the carrier 68, and BAP prints may be applied to the opposite side of the carrier 68 with the transfer surface 18 shown in FIG. 15a. The carrier 68 may be foil, paper and the like as described above. BAP prints may be replaced by conventional digital prints or prints with conventional rollers. Preferably, the patterns of print P and press particles 67 are aligned such that an EIR structure can be formed. FIG. 15 b shows that the carrier 68 and the pressing particles 67 are pressed on the surface 2 with the print P. FIG. 15 c shows that the print P is bonded to the surface 2 and the carrier 68 with the pressing particles 67 forms an embossed structure 17 when removed after the pressing operation. The application of the press particles 67 and the dry ink print may be performed with the press operation as shown in FIG. 15 d or preprinted and pre-embossed as individual carriers, preferably supplied as a foil It may be performed as another operation in which the carrier 68 is formed. The combined BAP printing and embossing equipment comprises a blank ink application station 36, a dry ink application station 27, and a dry ink removal station 28, these stations comprising dry ink 15 and press particles 67 as carrier 68. Apply and remove on both sides.

  Also, the particles may be attached to the carrier with a laser beam, a heated print head and all other methods described above.

  The surface of the carrier 68 in contact with the panel surface 2 may be pre-pressed and may have different gloss levels or microstructures. Such prepress may be performed with conventional embossing cylinders or BAP embossing methods. Also, various gloss levels and microfabrication may be formed with digital printing, and coatings may be applied according to any of the methods described in the present disclosure. A carrier 68 with pressed particles 67, preferably transfer prints P, may be supplied as a press matrix 78, for example embossed on tiles and LVT floors as well as on laminates, wood-based and powder-based floors May be used to form a structure. The press base material 78 may be used multiple times. The prints P may be conventional prints, digital inkjet prints, digital BAP prints or the like.

  This method is also used to form a more resistant "mirror-like" press matrix, in which the protrusions on the carrier 68 may be sheet material forming voids in the sheet-like press matrix. May be The carrier with press particles may be pressed against impregnated paper, preferably a phenol impregnated kraft paper or powder comprising a thermosetting resin, and may be used as a press base material in a second step A structured sheet matrix may be formed. Metal powders and glass fibers may be included to enhance strength and thermal transfer properties.

  All the above mentioned methods may be combined partially or completely to create a digital print or and / or a digital emboss partially or completely.

  Water-based blank inks may be combined or replaced by oil-based or solvent-based inks in some applications. An advantage of oil-based inks may be that the drying time is very long, which may enhance the functionality of the digital drop application head.

  Although the exemplary embodiments of the present invention have been described herein, the present invention is not limited to the various preferred embodiments described herein, and can be made by those skilled in the art based on the present disclosure. It includes any and all embodiments that have equivalent elements, modifications, omissions, combinations (e.g., combinations of aspects of the various embodiments), adaptations and / or variations that will be recognized. The limitations of the claims should be construed broadly based on the language used in the claims, and should be limited to the embodiments described in this specification and at the examination stage of this application. Rather, these examples should be construed as non-exclusive.

Example 1 Black Ink Containing Water and Glycol
A blank ink formulation was made for a Kyocera piezo print head for inks with a viscosity of 5-6 cps. 60.8% deionized water was mixed with 38.0% polyethylene glycol PEG 400, 1.0% Surfynol wetting agent, and 0.2% Actidice MBS to control bacteria and fungi.

Example 2 Dried Fiber-Based Ink
20% (by weight) spray-dried melamine formaldehyde particles, 20% dark brown colored pigment and 60% pine wood fiber with an average length of about 0.2 mm and a thickness of about 0.05 mm The mixing produced a dry ink powder. The mixture was applied as a 1 mm thick layer on a steel belt by means of a scattering device. The powder mixture was then heated and water was added with steam from deionized water. The mixture was dried with hot air to obtain a hard powder-based surface layer stabilized with a semi-cured melamine binder. The dry layer was removed from the belt by scraping and the dry wood particles coated with pigment and melamine resin were crushed and sieved to obtain dry ink colorants of similar size to the size of the individual wood fibers. A dry ink is obtained comprising a colorant having a wood fiber body and a surface covered with a pigment bonded to the fiber by the semi-cured melamine resin.

Example 3 Digital Binder and Powder Print
Small water droplets of deionized water were sprayed onto an 8 mm HDF board, and a 300 g / m 2 powder mixture containing wood fibers, melamine particles, light brown colored pigment and aluminum oxide particles was applied by a scattering device onto the HDF core . Stabilized, partially semi-cured hard powder-based surface having a light brown base color, bonded to the HDF core by spraying deionized water containing a release agent back onto the mixture and drying the mixture with IR light I got A panel with a stabilized powder surface was placed on a conveyor and moved under a digital Kyocera piezo print head. The digital print head is a stabilized powder-based surface which is coated with a droplet of a blank ink containing mainly water and glycol in the formulation described in Example 1 above on the light brown stabilized powder-based surface. A clear liquid wood grain pattern was printed on top. A woodgrain pattern was positioned at a predetermined distance from the long and short sides of the panel. The subsurface melamine below the applied clear pattern melted when the digital piezo coating head applied the aqueous droplets onto the powder based surface. A second step of drying ink as described in Example 2 above, comprising a dark brown powder-based surface darker than basic light brown using a drying ink application station comprising a hopper and a 5 cm diameter rotary oscillating engraving roller At the surface of the powder system and on the transparent pattern. A dry ink layer of about 30 gr / m 2 was applied to the panel surface. The melamine on the dried ink fibers in contact with the clear blank ink pattern melted and bonded the dried ink particles to the stabilized powder surface. The conveyor was then moved a panel with a clear blank ink pattern and a dry ink layer below the IR lamp. The clear pattern of melamine was again dried to obtain a stronger bond of fiber to pigment above the clear pattern. The panel is then moved by conveyor below the dry ink removal station and the dry ink removal station has an opening covering the full width of the coated dry ink layer where essentially all non-bonded fibers with pigment are removed A vacuum suction profile and an air knife pneumatically acting on the non-bonded particles peeled off the panel surface and sprayed into the vacuum suction profile such that essentially all visible dry ink particles are removed. A woodgrain pattern was obtained including a light brown base color and a brownish wood grain structure. A protective layer comprising a mixture of dry melamine and aluminum oxide particles was scattered across the surface using a scattering station of the same type as described above for the blank ink. The protective layer was sprayed with a microdroplet containing a release agent and dried under an IR lamp. Then place the panel with the print and protective layer in place relative to the long and short sides of the hydraulic press, and on the embossed steel plate for 20 seconds at a temperature of 170 ° C. and a pressure of 40 bar It was pressed against and the powder based surface with the wood grain pattern and the protective layer was cured to obtain a high wear resistant surface with high quality digital prints aligned with the embossed surface structure. The decoration of the panel was made with a base color and a wood grain pattern containing wood fibers and pigments. The natural wood fiber was used to create the visible pattern, resulting in a very realistic wood pattern.

(Embodiment)
1. A method of forming a digital print (P) on a surface (2), comprising
Applying a colorant (7) on the surface (2),
Bonding a portion of the colorant to the surface (2) with a binder (11),
Removing non-binding colorant (7) from the surface (2), such that the combined colorant (7) forms a digital print (P);
Forming method.
2. The method according to embodiment 1, wherein the colorant (7) comprises a pigment (12) mixed with a binder (11).
3. The method according to embodiment 1 or 2, wherein the binder (11) comprises a thermosetting resin.
4. The method according to any one of embodiments 1 to 3, wherein the binder (11) comprises a thermoplastic resin.
5. The method according to any one of the preceding embodiments, wherein the binder (11) is a powder.
6. The method according to any one of the preceding embodiments, wherein the surface (2) is a paper layer or foil.
7. The method according to any one of the preceding embodiments, wherein the surface (2) comprises a powder layer.
8. The method according to any one of the preceding embodiments, wherein the surface (2) is part of a building panel (1).
9. 9. The method according to any one of the embodiments 1 to 8, wherein the surface (2) is part of a floor panel (1).
10. The method according to any one of the preceding embodiments, wherein the colorant (7) is removed by an air stream.
11. 11. A method according to any one of the preceding embodiments, wherein the binder is a blank ink (11) comprising a liquid substance applied by a digital droplet application head (30 ').
12. 11. A method according to any one of the preceding embodiments, wherein the bonding occurs with a laser beam (29) or a heated print head (80).
13. The method according to embodiment 11, wherein the liquid substance is a water system.
14. The method according to embodiment 11 or 13, wherein the liquid substance is exposed to IR light (23) or hot air.
15. Embodiment 15. The method according to embodiment 14, wherein the liquid substance (11) is exposed to UV light.
16. 15. The method of embodiment 14, wherein the liquid substance is applied with a piezo ink head.
17. 15. The method of embodiment 14, wherein the liquid substance is applied with a thermo ink head.
18. The method according to embodiments 16 or 17, wherein the liquid substance is applied by arranging the droplets (56) in rasters (R1 to R4) and the colorant (7) is combined with a few droplets .
19. The method according to any one of the preceding embodiments, wherein the colorant (7) comprises granules (66) comprising fibers (61) or an inorganic substance (63).
20. Embodiment 20. The method according to any one of the embodiments 1-19, wherein the surface (2) with the bound colorant (7) is pressed.
21. Embodiment 21. The method according to any one of the embodiments 1 to 20, wherein the surface (2) with the bound colorant (7) is heated and pressed.
22. The method according to any one of the embodiments 1-21, wherein the surface (2) comprises another color different from the colorant (7).
23. Applying a new colorant (7, 12b) of different color onto the first combined colorant (7, 12a) and the surface (2) and a new colorant (7, 12b) using a binder Bonding a portion of the surface to the surface and arranging the first bonded colorant (12a) and the new colorant (12b) side by side on the surface (2) to form a digital print (P), The method according to any one of the embodiments 1-22, further comprising the step of removing the new colorant (7, 12b) which is not bound from the surface.
24. The method according to any one of the embodiments 1-23, wherein the colorant (7) is applied by scattering.
25. 27. The method according to any one of the embodiments 1-24, wherein the colorant (7) is arranged in a woodgrain pattern or stone pattern.
26. 26. The method according to any one of the embodiments 1-25, wherein the surface and the colorant are pressed and cured on a hard surface having an embossed (17) structure.
27. 27. The method according to any one of the embodiments 1 to 26, wherein the colorant (7) is macro colorant particles (64) larger than 20 microns.
28. The method according to any one of the embodiments 1-27, wherein the colorant (7) is pressed to the surface (2).
29. 29. A method according to any one of the embodiments 1 to 28, wherein the surface (2) is part of a panel (1) which is a laminated or wood floor, a powder based floor, a tile or an LVT floor.
30. An apparatus (40) for providing a digital print (P) on a surface (2) comprising a digital droplet application head (30 '), a dry ink application station (27) and a dry ink removal station (28) ,
The digital droplet application head (30 ') is configured to apply the liquid blank ink (11) on the surface (2),
The dry ink application station (27) is configured to apply the dry ink (15) comprising the colorant (7) onto the surface (2),
The blank ink (11) is configured to bond a portion of the dry ink (15) to the surface (2),
• An apparatus wherein the dry ink removal station (28) is configured to remove non-binding colorant (7) from the surface (2).
31. The device according to embodiment 30, wherein the surface (2) is part of a panel (1).
32. The device according to embodiment 30 or 31, wherein the dry ink (15) comprises a resin.
33. The device according to any one of the embodiments 30-32, wherein the blank ink (11) is aqueous.
34. The apparatus according to any one of the embodiments 30-33, wherein the blank ink (11) is subjected to high temperatures after application.
35. The macro colorant particles (64) are provided with granules (66) and granules (66) for coupling with the liquid print (P) applied to the surface (2). A dry ink (15) comprising colored pigment (12) deposited.
36. 36. The dried ink of embodiment 35, wherein the macro colorant particles (64) are greater than 20 microns.
37. 37. A dried ink according to embodiment 35 or 36, wherein the granules (66) are mineral particles (63), fibers (61) or a thermosetting resin (13).
38. 37. A dried ink according to embodiment 35 or 36, wherein the granules (66) are mineral particles (63).
39. 37. A dried ink according to embodiment 35 or 36, wherein the granules (66) are fibers (61).
40. 40. The dry ink of any one of embodiments 35-39, wherein the granules (66) are coated with a resin.
41. The dried ink of embodiment 40, wherein the resin is a thermosetting resin (13).
42. 42. The dried ink of any one of embodiments 35-41, wherein the liquid print is water based and is applied by a digital drop application head (30 ').
43. Panel with surface (2) comprising digitally formed print (P) of macro colorant (64) comprising granules (66) and colored pigment (12) deposited on the surface of granules (66) (1) A panel in which the colorant (7) is disposed in a pattern together with the pigments (12) attached to the upper and lower surfaces of the particles (66).
44. Embodiment 45. The panel according to embodiment 43, wherein the particles (66) comprise fibers (61).
45. The panel according to embodiment 43, wherein the particles (66) are mineral particles (63).
46. 46. The panel according to any one of the embodiments 43-45, wherein the macro colorant (64) has a particle size of greater than 20 microns.
47. 47. A panel according to any one of the embodiments 43 to 46, wherein the macrocoolant (64) forms a solid print with the overlapping decorative particles.
48. The panel according to any one of the embodiments 43 to 47, wherein the panel (1) is a laminate or wood floor, a powder based floor, a tile or an LVT floor.
49. A method of forming digital embossments (17) on a surface (2) by bonding hard pressed particles (67) to a carrier (68),
Providing a liquid binder pattern (BP) on the carrier (68) by means of a digital droplet application head (30 ') applying the liquid substance (11) on the carrier,
Applying the hard press particles (67) on the carrier (68) and the binder pattern (BP) such that the hard press particles are bound to the carrier (68) by means of a liquid bonding pattern (BP);
Removing unbonded hard pressed particles (67) from the carrier (68),
Pressing the carrier (68) with bound hard press particles (67) against the surface (2),
Removing the carrier (68) with hard press particles (67) from the pressed surface (2),
Forming method.
50. Embodiment 50. The method according to embodiment 49, wherein the pressed particles (67) are mineral particles (63).
51. 51. The method according to embodiment 49 or 50, wherein the carrier is paper or foil.
52. 52. The method according to any one of the embodiments 49-51, wherein the liquid substance is aqueous.
53. Embodiment 53. The method according to any one of the embodiments 49 to 52, wherein the surface (2) is powder or paper or foil.
54. 56. The method of any one of embodiments 49-53, wherein the surface (2) is part of a panel (1).
55. A panel (1) having a surface (2) with woodgrain decoration, a first surface portion (S1) formed by a continuous base layer with wood fibers (61a) of a first color; A second surface portion (S2) formed by two colored wood fibers (61b), wherein the second colored wood fibers (61b) are applied and bonded onto the continuous base layer; The surface portion (S2) covers a portion of the first surface portion (S1).
56. 56. A panel according to embodiment 55, wherein the continuous base layer is a powder comprising a thermosetting resin.
57. The panel according to embodiment 55 or 56, wherein the continuous base layer is paper.
58. The panel according to any one of the embodiments 55-57, wherein the second surface portion (S2) comprises fibers smaller than the first surface portion (S1).
59. An apparatus for providing a digital print (P) on a surface (2) by a transfer printing method, comprising: a digital droplet application head (30 '), a dry ink application unit (27), and a dry ink removal station (28); With a transfer surface (18),
The digital droplet application head (30 ') is adapted to apply the liquid blank ink (11) on the transfer surface (18),
The dry ink application unit (27) is adapted to apply a dry ink (15) comprising colorant onto the transfer surface (18);
The blank ink (11) is adapted to bind a portion of the dry ink (15) to the transfer surface (18),
The dry ink removal station (28) is adapted to remove unbound dry ink from the transfer surface (18)
-An apparatus wherein the transfer surface (18) with the combined dry ink is adapted to be pressed against the surface (2).
60. 60. An apparatus according to embodiment 59, wherein the dry ink (15) comprises a resin.
61. 61. An apparatus according to embodiment 59 or 60, wherein the blank ink (11) is aqueous.
62. The apparatus according to any one of the embodiments 59-61, wherein the blank ink is exposed to high temperatures after application.
63. Press base (78) forming an embossed structure (17) on the panel (1), which is arranged in a pattern and is bonded to a carrier (68) which is a coated paper or foil Press base material provided with (67).
64. 64. Press base material (78) according to embodiment 63, wherein the hard press particles (67) are arranged on one side of the carrier and the print (P) is arranged on the opposite side of the carrier.
65. The hard press particles (67) and the print (P) are aligned such that when the press base is pressed against the panel surface (2), an aligned embossed print surface can be obtained The press base material (78) as described in 63 or 64.
66. A method of forming a digital print (P) on a surface (2), the steps of applying a powder of a dry ink (15) containing a colorant (7) on the surface, and combining the digital print (P) Bonding a portion of the dry ink (15) powder to the surface (2) by means of a digital heating print head (80) as formed by the dry ink colorant (7), non-bonded drying from the surface (2) Removing the ink (15).
67. The method according to embodiment 66, wherein the dry ink (15) comprises a thermosensitive resin.
68. The method according to embodiment 66 or 67, wherein the surface (2) comprises a thermosensitive resin.
69. Embodiment 69. The method according to embodiment 67 or 68, wherein the heat sensitive resin is a thermosetting resin or a thermoplastic resin.
70. Embodiment 70. The method according to embodiment 69, wherein the heat sensitive resin is a thermosetting resin comprising melamine.
71. 70. The method as set forth in any one of embodiments 66-69, wherein the heated print head (80) applies heat onto the thermal transfer foil (81).
72. 71. The method according to embodiment 70, wherein the thermal transfer foil (81) comprises copper or aluminum.
72. Embodiment 69. The method according to any one of the embodiments 66 to 68, wherein the surface (2) is part of an architectural panel, preferably part of a floor panel (1).
73. Embodiment 73. The method according to any one of embodiments 66 to 72, wherein the dry ink (15) comprises mineral particles.
74. Embodiment 74. The method according to embodiment 73, wherein the dry ink (15) comprises aluminum oxide particles.
75. A method of forming a digital print (P) on a surface (2) comprising applying a droplet (57) of blank ink (11) on the surface (2) by means of a digital droplet application head (30 ') And applying a colorant (7) to the blank ink droplets (57) to form a digital print (P), the digital print (P) being separate from the blank ink (11) Forming method including color.
76. 76. A method according to embodiment 75, wherein the other color is formed by the colorant (7) bound to the surface (2) by the blank ink (11).
77. The method according to embodiment 75 or 76, wherein the blank ink (11) is essentially a clear liquid substance comprising water.
78. 78. The blank ink (11) forms a first part and a second part of the print (P), wherein the blank ink, the first part and the second part all contain different colors. The method according to any one.
79. 79. A method according to any one of the embodiments 75-78, wherein the digital print (P) comprises different color colorants (7) positioned horizontally offset in the same plane.
80. 80. A method according to any one of the embodiments 75 to 79, wherein the vertical range (V2) of the colorant (7) exceeds the vertical range (V1) of the blank ink drop (57).
81. The method according to any one of the embodiments 75-80, wherein the digitally applied blank ink drop (57) penetrates downward and upward from the surface (2) after application.
82. 76. From embodiment 75, droplets of blank ink (11) providing blank ink spots (57) on surface (2) combine colorant (7) having a size larger than the size of blank ink spots (57). 81. A method according to any one of 81.
83. The blank ink (11) is applied to a raster pattern (R1 to R4) and the dry ink (15) is randomly applied with overlapping colorants (7) according to any one of the embodiments 75 to 82 the method of.
84. The horizontal range (H2) of the individual colorant (7) exceeds the horizontal range (H1) of the ink spot (57) and the vertical range (V2) of the dry ink layer is the blank ink spot after removal of non-bound particles The method according to any one of the embodiments 75-83, wherein it is preferred to exceed the vertical range (V1) of (57).

Claims (15)

A method of forming a digital print (P) on a panel (1) having a surface (2), wherein the surface (2) is a part of a floor panel (1) and the surface is a wood fiber ( 61), and
Placing the panel under a digital drop application head (30 ');
Applying a liquid binder (11) on the surface (2) with the digital droplet application head (30 ');
Applying a coloring agent (7) onto the liquid binder (11) and the surface (2);
Bonding a portion of the colorant (7) to the surface (2) with the liquid binder (11);
Removing the non-bonded colorant (7) from the surface (2), such that the combined colorant (7) forms a digital print (P);
Applying heat and pressure to the panel (1), the surface (2) and the combined colorant (7) such that the colorant (7) is permanently bonded to the surface (2) And steps.   The surface (2) and / or the colorant is compressed by the step of applying heat and pressure to the panel (1), the surface (2) and the associated colorant (7) The method according to Item 1.   The method according to claim 1 or 2, wherein the liquid binder (11) comprises glycol or glycerin.   The method according to any one of the preceding claims, wherein the surface (2) comprises a material that is curable under heating and pressure or a material that is meltable under heating and pressure.   The method according to any of the preceding claims, wherein the coloring agent (7) is pressed into the surface (2) when heat and pressure are applied to the panel (1).   Said surface (2) is cured in said step of applying heat and pressure such that said colorant (7) is permanently bonded to said surface (2) with a cured thermosetting resin 6. A method according to any one of the preceding claims, comprising a sexing resin (13).   Said surface (2) is a part of building panel (1), a part of floor panel (1), or a paper layer or foil, or said surface (2) comprises a powder layer A method according to any one of the preceding claims, or comprising another color different from the colorant (7).   The liquid binding agent (11) is applied by arranging the droplets (56) in rasters (R1 to R4), the colorant (7) being combined with a few drops of droplets. The method according to any one of 7 to 8.   The surface (2) comprises a dry melamine formaldehyde resin (13) which melts when the liquid binder (11) is applied and bonds the colorant (7) to the surface (2). 8. The method according to any one of 8.   The colorant (7) comprises a pigment (12) mixed with a dry binder (13) that interacts with the liquid binder (11), and / or each of the colorant (7) is 10. A method according to any one of the preceding claims, wherein the granules (66) comprise wood fibers (61).   The colorant (7) comprises a pigment (12) mixed with a dry binder (13) that interacts with the liquid binder (11), the dry binder (13) being a thermosetting resin 11. A method according to any one of the preceding claims, comprising   Applying a new colorant (7, 12b) of different color onto the first combined colorant (7, 12a) and said surface (2), and using the binder a new colorant (7, 12b) Bonding a portion of the surface to the surface, the first bonding colorant (12a) and the new colorant (12b) being arranged side by side on the surface (2) to form a digital print (P) The method according to any one of the preceding claims, further comprising the step of removing from the surface the new colorant (7, 12b) which is not bound.   The method according to any one of the preceding claims, wherein the colorant (7) is applied onto the liquid binder (11).   The surface (2) with associated colorant (7) is pressed at a pressure of about 40 to 60 bar and / or heated with a heat above about 160 ° C. The method according to any one of the preceding claims. An apparatus (40) for providing a digital print (P) on a panel (1) including a surface (2), comprising a conveyor (21), a digital droplet application head (30 ') and a dry ink application station ( 27) and a dry ink removal station (28),
Said surface (2) is part of a floor panel (1), said surface comprising wood fibers (61),
The conveyor is configured to displace the panel (2) essentially horizontally below the digital drop application head;
The digital droplet application head (30 ') is configured to apply a liquid blank ink (11) onto the surface (2),
The dry ink application station (27) is configured to apply a dry ink (15) containing a dry colorant (7) onto the blank ink (11), and the liquid blank ink (11) comprises the coloring Configured to couple a portion of the agent (7) to the surface (2),
The dry ink removal station (28) is configured to remove the non-bonded colorant (7) from the surface (2) after application of the blank ink (11) and the dry ink (15) respectively Yes, the equipment.