EA041198B1 - INJET PAPER - Google Patents

Description

The present invention relates to a method for manufacturing panels having a decorative surface, or so-called decorative panels. The invention also relates to a process for producing an inkjet printable paper or film for use as a decorative paper or film in such panels, as well as to a paper or film obtained in this way. In one embodiment, the resulting decorative paper or decorative film can be used in a laminated prefab other than the panel, such as in a so-called CPL (compact laminate) or heterogeneous full-width vinyl flooring.

More specifically, the invention relates to a process for the manufacture of laminated panels, said panels comprising at least a base material and a decor printed overlay created thereon. In a first possibility, the method could be used to produce panels whose top layer is formed from a thermosetting resin and one or more paper layers, said paper layers comprising decorative paper having a printed design. In a second possibility, the method could be used to make panels whose top layer is formed from a thermoplastic material such as polyvinyl chloride (PVC), including at least one thermoplastic decorative film having a printed pattern. Panels according to the invention may refer to furniture panels, ceiling panels, floor panels, or the like, these panels preferably comprising a wood-based backing such as MDF or HDF (medium or high density fibreboard) backing or backing material. , consisting or essentially made of chipboard. According to an alternative embodiment, which is of particular interest in combination with the above second possibility, the panels comprise a filled synthetic composite backing or a mineral backing. These last panels are also called LVT panels (Luxury Vinyl Tiles, designer vinyl tiles).

The decor or pattern on such panels is traditionally printed on paper or thermoplastic film by offset or rotogravure printing. The resulting paper or film is regarded as decorative paper or decorative film in a so-called laminated panel or LVT panel. The DPL (Direct Press Process) process can be used to manufacture the panels according to the first possibility mentioned above. According to the DPL (Direct Press Laminate) process, already printed paper, or decorative paper, is impregnated with melamine resin to form a decorative layer. After that, a package is formed, including at least a base in the form of a plate, the specified decorative layer and, possibly, a protective layer on top of the specified decorative layer, and the basis of the specified protective layer, or cover layer, is resin and/or also paper. Said pouch is pressed, and the press treatment causes the decorative paper, base and backing layer to be interconnected or glued together, and the resin present in the pouch to be cured. As a result of the pressing operation, a decorative panel having a melamine surface which can be highly wear resistant is obtained. On the underside of the panel-shaped base, an anti-layer or balancing layer could be applied or, alternatively, a decorative layer could also be attached to the underside, in particular in the case of laminated panels for furniture. Such an anti-layer, or balancing layer, or any other layer on the underside of the laminated panel limits or prevents the decorative panel from possible bending, and is applied in the same press treatment, for example, by placing a resin-containing paper layer as the bottommost layer of the bag, on the side of the bag, opposite to said decorative layer. For examples of the DPL process, reference is made to patent document EP 1290290, from which, moreover, it is known to create a relief in said melamine surface during the same press treatment or pressing operation, namely by bringing said melamine surface into contact with a structured press element, for example, structured press plate. To produce the panels according to the above second possibility, the decorative film and the transparent thermoplastic wear layer are also preferably laminated to form the top layer of the panel. The interconnection or bonding of the decorative film and the transparent wear layer is preferably achieved by a thermal lamination process, for example using one or more press rolls. The resulting top layer can then be glued or layered onto the base. In order to be able to form a pattern in the top layer, a pressing treatment or a pressing operation may be used. Namely, by bringing the thermoplastic top layer into contact with a structured press element, for example a structured press roll. The pressing element is preferably cooled while the thermoplastic top layer is in a heated state in contact with the roller, so that the thermoplastic top layer can be cooled and solidified while in contact with the pressing element, thereby acquiring a structure that is negative with respect to the structure of the pressing element. .

Printing paper or thermoplastic film using an analog printing process such as rotogravure or offset printing inevitably results in large minimum order quantities for a particular decorative paper or film at an affordable cost, and

- 1 041198 limits the achievable technological flexibility. Changing the decor or pattern requires the printing equipment to stop for about 24 hours. This downtime is required to change the print rollers, clean the printing equipment, and adjust the colors of the new printed decor or pattern.

Instead of analog printing methods, digital printing methods, in particular inkjet printing methods, are becoming increasingly popular for creating decors or patterns, whether on paper, film, or directly on a plate-shaped substrate, possibly with preparatory layers applied in between. Such digital technologies can significantly increase the flexibility when printing decors. Among other things, references are made to patent documents EP 1872959, WO 2011/124503, EP 1857511, EP 2431190, EP 2293946, WO 2014/084787, WO 2015/140682 and WO 2015/118451, where such methods are disclosed.

Patent document EP 2132041 discloses a method comprising at least the step of impregnating a paper layer with a thermosetting resin and the step of providing said resin-impregnated paper layer with at least a portion of said printed pattern. Preferably, multi-colour prints, for example, depicting a wood grain, are applied to the aforementioned paper layer in order to create a decor. Such decor occupies most, or even the entire resin-impregnated paper layer. EP 2132041 uses a digital printer, more specifically an inkjet printer. However, it has been very difficult to reliably post-process such printed laminated paper in a manner such as the DPL process, since pressing can create defects in the surface of the resin, and milling, drilling, or sawing through the surface of the laminated material or at its edge often results in peeling of the top layer. In addition, the inks or inks of EP'041 may excessively wet the paper layer and cause puckering or bleeding effects during further processing of the printed paper, leading to instability and/or slowdown in the manufacturing process. To solve this problem, patent document EP'041 proposes immediate drying of the printed paper layer.

Patent documents EP 1044822, EP 1749676 and EP 2274485 disclose the use of an inkjet-receptive coating to improve print quality on original decorative paper. Such an inkjet-ready coating includes pigments and a polymer such as polyvinyl alcohol. Although, when increased, the resulting print color density on such processed paper is still inferior to that of analog printing.

As recognized in patent document WO 2015/118451, the use of paper treated with an inkjet-ready coating can lead to malfunctions of printing equipment. Dust can be released from the inkjet-ready coating and cause all sorts of damage to critical parts of the inkjet printer. For example, dust can clog one or more nozzles and cause print defects. In order to minimize dust emissions, WO 2015/118451 suggests avoiding too much paper bending in printing equipment.

In the course of his own research, the inventor of the present invention has also encountered problems with the subsequent impregnation of the dust-generating paper layers, even in cases where the paper layers have already been printed. The released dust can contaminate the resin tank, rollers, chambers and other equipment in or near the impregnation channel, resulting in defects in the final product or damage to the equipment in use.

Patent document WO 2015/140682 discloses printing materials that reduce the problems encountered when laminating digitally printed thermoplastic decorative films with transparent thermoplastic wear layers, for example when applied over a print. The decorative film may be digitally printed with an inkjet-receptive coating in between. Patent document WO 2014/084787 discloses an inkjet-receptive coating for a plastic film, wherein the inkjet-receptive coating essentially comprises an aqueous solution of a metal salt such as NaCl or CaCl ₂ .

The present invention aims primarily to provide an alternative method for the manufacture of panels having a decorative surface, or paper, respectively, thermoplastic film, for use in such panels, and seeks, in accordance with its preferred embodiments, to solve one or more of the problems encountered in the prototype .

Therefore, the present invention, according to its first independent aspect, relates to a method for producing paper or a thermoplastic film or a vitrimer film suitable for printing in an inkjet printer, for use as a decorative paper or, respectively, a decorative film in a laminated panel, the method comprising at least the following steps:

the step of providing a paper layer or, respectively, a thermoplastic or vitrimer film;

the step of applying to at least one side of said paper layer or said film, respectively, an inkjet-receptive coating comprising at least

- 2 041198 pigment and binder;

with the characteristic that said inkjet-receptive coating further comprises a reactive ink component.

Ink jet ink pigments are stabilized to achieve good dispersion in the ink binder and to prevent coagulation of the pigments, in particular to avoid clogging of the nozzles in the print heads. This stabilization in inkjet inks is obtained by the electrosteric effect between the pigments. The reactive ink component is preferably a substance that disrupts the stabilization of the pigments in the ejected droplets, or in other words, is an ink destabilizing agent. The inventors of the present invention have found that the addition of such a reactive ink component to an inkjet receptive coating based on a mixture of pigment and binder greatly improves the resulting print quality, more specifically the achievable color density, when printed on a paper layer or on a film. The reactive component of the paint captures the paint, more specifically the pigments, as a result of the first interaction with them. The disruption or elimination of the electrosteric effect on the pigments results in the pigments rapidly settling out of the ink mixture and only minimally moving deeper into the coating along with the ink binder. This immediate immobilization of the pigment results in superior print color density. The pigment/binder system in the inkjet-ready coating absorbs the ink binder, thereby also preventing bleeding, especially during paper printing, or ink washout during printing on films, which itself can also result in improved print quality.

In the method according to the invention, the paper or film is preferably intended to be printed with water-based or UV-curable inks. First, the papers or films produced according to the first aspect are intended to be printed using inkjet printing equipment. However, the inventors of the present invention have also found an improvement in print quality using papers and films thus treated in analog printing equipment.

According to the invention, the reactive paint component can be selected as one or many of several possibilities, of which the most important possibilities are listed below.

According to a first possibility, said reactive paint component comprises a polyionic polymer, preferably polyDADMAC (polydiallyldimethylammonium chloride). The ionic polymer completely or partially neutralizes the electrosteric effect of the pigment in the ink, causing rapid pigment deposition.

According to a second possibility, said reactive ink component comprises a substance that changes, and more specifically, lowers, the pH value of said inkjet-receptive coating. The pH value of the inkjet-ready coating composition is reduced to pH 3 or below by selection of the amount and type of said substance, which selection is within the skill of the skilled artisan. Said substance is preferably selected from the list consisting of formic acid, tartaric acid, acetic acid, hydrochloric acid, citric acid, phosphoric acid, sulfuric acid, AlCl ₃ and boronic acid. An adjusted, more specifically reduced pH, preferably to pH 3 or less, increases the chemical affinity of the inkjet-receptive coating for the ink and will inhibit electrosteric action on the pigment such that the dispersion of pigments in the ink quickly becomes destabilized.

According to a third possibility, said reactive paint component comprises a metal salt, preferably a salt with a metal cation. Said metal salt is preferably selected from the list consisting of CaCl2, MgCl2, CaBr2, MgBr2, CMA (calcium magnesium acetate), NH ₄ Cl, calcium acetate, ZrCl ₄ and magnesium acetate. The positively charged ion of the dissolved metal salt will tend to neutralize the electrosteric stabilizing function of the pigment. The most preferred metal cation salts are CaCl2, MgCl2, CMA, calcium acetate and magnesium acetate, as the present inventors have obtained the best results with these reactive paint components.

According to a fourth possibility, said reactive paint component comprises a coagulant. Said coagulant is preferably selected from the list consisting of sodium aluminate, a double sulfate salt such as alum, polyaluminum chloride, polyacrylate, dicyandiamide (eg Floquat DI5 from SNF) and polyacrylamide. The coagulant displaces the paint pigments from the paint dispersion. This prevents the pigments from penetrating far into the inkjet-receptive coating. Deeper in the inkjet-ready coating, it is mainly the ink binder, such as water in the case of water-based inks, that is absorbed.

Said paper or film is preferably provided with an ink reactive component having a dry weight of 0.2 to 10 g/m ² , and preferably between 0.5 and 5 g/m ² , more particularly an ink destabilizing agent, in said inkjet receptive agent. cover printing.

Said paper or film is preferably provided with a hygroscopic component or pigment with a dry coating weight of 0.2 to 10 g/m ² , and preferably between 0.5 and 5 g/m ² , in

- 3 041198 specified accepting inkjet printing coating. Said pigment preferably has a BET (Brunauer-Emmett-Teller) specific surface area between 10 and 1600 m ² /g and preferably between 15 and 500 m ² /g. The coating is preferably such that the pigments create a surface of 100 m ² to 16,000 m ² per m ² surface area of the paper or film, or even better between 150 and

500 m ² of pigment surface per m of paper or film surface.

In a most preferred embodiment, the pigment of said inkjet-receptive coating uses at least or primarily silica particles. The silica particles are preferably silane treated. Silane treatment of pigments generally improves the dust release characteristics of the resulting inkjet-receptive coating and the paper or thermoplastic film thus treated. The silane treatment may be related to the treatment with a coupling agent such as aminoorganosilanes, hydroxysilanes, dipodal silanes and/or other silanes. The coupling agent is preferably chosen such that there is a low risk of yellowing as the resulting inkjet-receptive coating ages. The binding agent preferably comprises 0.1 to 10% of the total weight of the wet inkjet-ready coating.

In embodiments, the pigment of said inkjet-receptive coating uses at least or primarily particles selected from the list consisting of calcium carbonate, silica, alumina, aluminosilicates, ordered mesoporous materials, modified silica, organosilica, modified organosilica, organoalumina, modified alumina. , aluminates, modified aluminates, organoaluminates, modified organoaluminates, zeolites, organometallic framework structures and porous polar polymers.

Said paper or film is preferably provided with a binder having a dry coating weight of 0.2 to 10 g/m ² and preferably between 0.5 and 5 g/m ² in said inkjet-receptive coating. In a most preferred embodiment, the binder component in said inkjet-receptive coating is at least or predominantly polyvinyl alcohols.

In embodiments, the inkjet-ready coating comprises, as a binder, a polymer selected from the group consisting of hydroxyethyl cellulose; hydroxypropyl cellulose; hydroxyethylmethylcellulose; hydroxypropyl methylcellulose; hydroxybutyl methylcellulose; methylcellulose; sodium salt of carboxymethyl cellulose; sodium salt of carboxymethylhydroxyethylcellulose; water-soluble ethylhydroxyethylcellulose; cellulose sulfate; vinyl alcohol copolymers; polyvinyl acetate; polyvinyl acetal; polyvinylpyrrolidone; polyacrylamide; acrylamide-acrylic acid copolymer; polystyrene, styrene copolymers; acrylic or methacrylic polymers; styrene-acrylic copolymers; ethylene-vinyl acetate copolymer; copolymer of simple vinyl methyl ether and maleic acid; poly(2-acrylamido-2methylpropane)sulfonic acid; polycondensation product of diethylenetriamine and adipic acid; polyvinylpyridine; polyvinylimidazole; epichlorohydrin-modified polyethyleneimine; ethoxylated polyethyleneimine; ether-linked polymers such as polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), and polyvinyl ether (PVE); polyurethane; melamine resins; gelatin; carrageenan; dextran; gum arabic; casein; pectin; albumin; chitin; chitosan; starch; collagen derivatives; collodion and agaragara. The most preferred options for the binder are polyvinyl acetates; ethyl vinyl acetates, polyvinyl acetate-based block copolymers, polyvinyl alcohol-based block copolymers, acrylates, latexes, polyvinyl derivatives, VCVAC (vinyl chloride-vinyl acetate copolymer) derivatives, polyol and isocyanate based polyurethanes, polycarbamates and polyaldehyde based polyurethanes, e.g. in the form of an aqueous dispersion / emulsion, and a solution in water or in a solvent.

As indicated above, preferred binders for the inkjet-ready coating include polyvinyl alcohol (PVA), but in embodiments, vinyl alcohol copolymers or modified polyvinyl alcohol may be used. The modified polyvinyl alcohol may be a cationic type polyvinyl alcohol such as cationic polyvinyl alcohol grades from Kuraray such as POVAL C506, POVAL C118 from Nippon Goshei.

Said inkjet-receptive coating preferably has, in the most general sense, a ratio of pigment to binder between 0/1 or 0.01/1 and 25/1, preferably between 0/1 or 0.01/1 and 20/1. It is possible that the inkjet receptive coating is heterogeneous and exhibits differences in composition layer by layer or in individual areas, in which case the above values are average values for the entire inkjet receptive coating as a whole.

In addition, the inkjet printable coating preferably includes one or more of the following agents.

- 4 041198

Cross-linking agents: between 0.05 and 5 g/m ² , preferably between 0.2 and 2 g/m ² , for example selected from the list consisting of aldehydes, polyaldehydes, dialdehydes, alcohols, boronic acid, borax, polyalcohols, carbamates , polycarbamates, carboxylic acids, glyoxal-based reagent, zirconium-based reagents, and polycarboxylic acids.

Particle surface modifying agents or crosslinkers: 0.05 and 5 g/m ² , preferably between 0.2 and 2 g/m ² , for example selected from the non-limiting list consisting of aminosilanes, ureidosilanes, aldehyde and silane derivatives, tetraethylorthosilicate, Silazane, organically modified silanes, organically modified silanes, chlorosilanes, organically modified chlorosilanes, organobissilanes, silsesquioxanes, polysilsesquioxanes, silane oligomers, organically modified silane oligomers, bissilane oligomers, organically modified bissilane oligomers, oligomeric silsesquioxanes, and oligomeric polysilsesquioxanes.

Additives: wetting agent, between 0.005 and 2 g/m ² , preferably between 0.05 and 1 g/m ² ; and/or defoamer, between 0.005 and 2 g/m ² , preferably between 0.05 and 1 g/m ² ; and/or fungicide, between 0.005 and 2 g/m ² , preferably between 0.05 and 1 g/m ² .

The paper layer or thermoplastic film on which the inkjet-receptive coating has been applied preferably has a basis weight of 50 to 100 g/m ² , for example between 60 and 80 g/m ² .

In the case of the paper layer, the side on which the inkjet-receptive coating is to be applied has preferably been ironed (in German: polished), preferably at the time of its manufacture. Smoothing reduces the degree of penetration of the binder into the core of the paper so that the pigments contained therein can be better bound by the binder present and there may be less absorption variation. The paper produced by the process according to the invention, ie comprising an inkjet-receptive coating, preferably has a Gurley value between 30 and 120 s and preferably between 30 and 80 s. Such a paper layer provides excellent print quality because the applied inks are less likely to be absorbed into the paper and position matching, and the so-called registration between printed patterns produced by different inkjet printheads, is more easily achieved and maintained. Indeed, a relatively high Gurley porosity results in a paper with greater dimensional stability because it is less likely to absorb water. When it comes to thermosetting resin impregnation of paper with this Gurley porosity value, one can take into account the possibility of adjusting the impregnation channel to a lower speed, applying pressure impregnation methods and reducing the viscosity of the impregnating resin.

In a most preferred embodiment, said inkjet-receptive coating is applied in at least two separate steps, with a first layer from a first composition and then a second layer from a second composition respectively being applied, both compositions at least including said binder component.

The inventor of the present invention has found that applying an inkjet-ready coating in two separate steps results in better incorporation or binding of the pigment. The risk of dust emission from the paper is reduced compared to a situation where the same amount of pigment is applied in only one coating step. According to the inventor of the present invention, this unexpected effect can be attributed to the fact that the first layer creates a kind of barrier to the penetration of the binder component of the second layer into the paper layer. The binder component of the second layer is more effective in binding the pigments, since otherwise they would be released or bond worse to the surface of the paper. Better-embedded pigments lead to significantly less dust emission from the paper during post-processing, eg printing, resin impregnation.

In addition, applying the inkjet-receptive coating in two steps can result in more uniform deposition over the entire inkjet-receptive coating. Where the first composition may be partially absorbed by the paper layer in an uneven manner, and thus may result in an inhomogeneous first layer having less saturated areas, the second composition evens out the inhomogeneities, at least to some extent.

The application of the inkjet-ready coating in at least two stages allows the creation of gradients of certain components of the coating in the direction of its thickness, since the first and second composition may have different components, or both of them may have components that are present at different concentrations, as will be explained below. . The application of an inkjet-receptive coating in at least two stages additionally makes it possible to create cover layers with different thicknesses.

The method according to the invention, and in particular those embodiments where the inkjet-ready coating is applied in two separate steps, is of particular interest when it starts from paper layers whose average drag is low, for example at a Gurley porosity value of 30 s or lower, for example, 25 s or lower. In such cases

- 5 041198 the binder contained in the first layer tends to be intensively absorbed by the paper stock, leading to a high content of non-surface pigment. The paper layer is preferably a standard print base paper or another untreated paper layer having an average drag, as expressed by a Gurley porosity index, of 30 seconds or less. Of course, this does not exclude that in the method according to the invention, according to an alternative embodiment, the source paper is treated with a thermosetting resin before applying said inkjet receptive coating. In this latter case, the resin-impregnated paper layer preferably has an average drag at a Gurley porosity value of 100 s or less. In addition, in such a case, applying the inkjet-receptive coating in two separate steps has significant advantages, for example, in terms of dust emission, minimization of bleeding of applied inks, uniformity of application of the inkjet-receptive coating.

In general, the method according to the invention, in cases where the inkjet-receptive coating is applied in two separate steps, allows the inkjet-receptive coating to be applied with a higher pigment content, and therefore with a higher capacity, or faster absorption rate, of the applied ink binder, for example , water in the case of water-based pigmented inks, while maintaining or even reducing dust emissions from the treated printable surface. A higher capacity, or faster rate, of absorption of the binder may result in higher print definition. Because the binder soaks into the inkjet-ready coating substantially vertically, i.e., without significant lateral flow, the pigments are held in place where the ink was applied, i.e., the pigments do not spread apart with the ink binder. As noted above, any bleeding that still exists can be made even more uniform by applying a second layer of inkjet-ready coating to partially or completely equalize the first layer. The presence of the reactive ink component in the inkjet-ready coating assists in the direct fixation of the ink pigment to the surface of the treated paper or film.

In the case where the inkjet receptive coating is applied in two separate steps, said first layer and said second layer are preferably different in that they exhibit one or more of the following properties:

the property that said first layer as well as said second layer comprise a pigment and a binder, albeit with a different ratio of pigment to binder;

- the property that the dry weight of the material applied for said first layer and said second layer is different;

the property that said first layer and said second layer include a pigment and a binder, wherein the average particle size of the pigments contained in said first layer is larger than the average particle size of the pigments contained in said second layer;

- the property that said first layer as well as said second layer include a reactive paint component, albeit with a different composition;

- the property that said first layer includes at least a pigment and a binder, while the second layer does not contain pigments, or contains at least less pigment than said first layer, or contains less than 10% pigment relative to the pigment content in the specified first layer.

With respect to the first mentioned property, said first composition preferably has a ratio of pigment to binder that is greater than the ratio of pigment to binder in said second composition. Thus, the binder of the second layer mainly binds the pigments of the first layer and evens out the heterogeneity in the first layer.

The ratio of pigment to binder in said second composition is preferably less than 2:1 and preferably between 0:1 and 2:1. When the ratio in the second composition is less than 1.5:1, exceptionally low dust emission was found. As presented above, this does not exclude that in some embodiments, said second composition does not contain pigments.

Whether in combination or not with said preferred second composition, the ratio of pigment to binder in said first composition may be chosen between 1:1 and 25:1, or between 2:1 and 10:1, and preferably 3.5:1 , or more than 3.5:1, and even better 5.5:1, or more than 5.5:1, although less than 10:1 is preferred.

A good combination of the first and second composition is achieved when the ratio of pigment to binder in the second composition is between 0:1 and 2:1, and the ratio of pigment to binder in the first composition is between 3.5:1 and 10:1 and inclusive. However, it is clear that within the scope of the present invention, the ratio of pigment to binder in the first and second compositions may be equal or substantially equal.

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With regard to the second property mentioned, it is of course not excluded that both layers are applied with the same dry weight. However, in this case, it is preferable to have a different ratio of pigment to binder in the applied first and second compositions. Each of these two layers is applied to the paper layer preferably with a dry weight of between 0.5 and 5 g/m ² of the material, and even better between 0.8 and 4.5 g/m ² . In cases where the dry weights of said first layer and said second layer applied differ, the first layer preferably includes a material with a higher dry weight, for example at least 20% higher than the second layer. The composition of each layer preferably comprises between 12 and 20% by weight of solid material, so that in terms of wet weight an amount of preferably between 4 and 23 g/m ² of wet cover material is applied to the paper layer.

With respect to the third property mentioned, the larger pigment particles are preferably contained in said first composition. The use of coarse particles in the first layer provides excellent absorption of the ink binder, while the use of fine particles in the second layer has the effect of leveling and good dust reduction on the surface of the paper layer. In such a case, the pigment particles in said first composition preferably have an average particle size between 1 and 20 µm. The pigment particles in said second composition preferably have an average particle size between 100 nm and 1 µm. Of course, it is not generally excluded that the first and second compositions would contain pigment particles with a similar or the same average particle size.

With respect to the fourth property mentioned, said second layer preferably includes a larger amount of said reactive paint component than said first layer. The presence of a reactive paint component in the top layer of the coating leads to effective interaction with the pigments of the sprayed paint droplets. The reactive ink component preferably includes a coagulant or another ink destabilizing agent such as a metal cation salt.

The binder component used in the invention in general, or the binder component contained in the first and/or second composition, can also be formed by a mixture of the above possible such binder components. According to a special embodiment, a mixture of polyvinyl alcohol with ethylene-vinyl acetate (EVA) and/or polyvinyl acetate (PVAc) is used as a binder, preferably the main ingredient of the binder is polyvinyl alcohol, and, for example, at least 5% by weight of EVA are used. and/or PVAc. The author of the present invention noted the increased flexibility of the thus treated paper or film, compared with papers or films, where the binder is mainly polyvinyl alcohol. The increased flexibility with reduced dust generation is advantageous for the subsequent processing of the paper or film thus treated, for example in printing equipment.

The binder in the first and second compositions is preferably the same, or at least the main constituent of the binder is the same. As mentioned above, the main constituent of the binder component is polyvinyl alcohol.

As the pigment used in the invention in general, or as the pigment in the first and/or second composition, any inorganic pigment can in fact be used, and most preferably a porous inorganic pigment. Mixtures of two or more pigments may also be used. The pigment used is preferably an inorganic pigment which may be selected from neutral, anionic and cationic type pigments. Pigments used include, for example, silica, organosilica, talc, clay, hydrotalcite, kaolin, diatomaceous earth, calcium carbonate, magnesium carbonate, basic magnesium carbonate, aluminosilicate, aluminum trihydroxide, alumina (alumina), titanium oxide, zinc oxide, barium sulfate , calcium sulfate, zinc sulfide, satin white pigment, alumina hydrate such as boehmite, zirconium oxide, or mixed oxides. The inorganic pigment is preferably selected from the group consisting of alumina hydrates, aluminum oxides, aluminum hydroxides, aluminum silicates, and silicas. Particularly preferred inorganic pigments are silica particles, colloidal silicon dioxide, alumina particles and pseudoboehmite, as they form better porous structures. As used here, the particles may be primarily particles that are directly used as is, or they may form secondary particles. The preferred type of alumina hydrate is crystalline boehmite, or y-AlO(OH). Boehmite types used include DISPERAL HP14, DISPERAL 40, DISPAL 23N4-20, DISPAL 14N25 and DISPERAL AL25 from Sasol; and MARTOXIN VPP2000-2 and GL-3 from Martinswerk GmbH. Useful types of cationic alumina (alumina) include α-Al ₂ O ₃ types such as NORTON E700 available from Saint-Gobain Ceramics & Plastics, Inc, and y-A1 ₂ O ₃ types such as ALUMINUM OXID C from by Degussa. Other useful inorganic pigments include aluminum trihydroxides such as bayerite or a-Al(OH) ₃ such as PLURAL BT available from Sasol and gibbsite or y-A1(OH) ₃ such as MARTINAL grades and MARTIFIN grades, from Martinswerk GmbH,

- 7 041198 grade MICRAL from JM Huber company; HIGILITE varieties from Showa Denka K.K. As stated above, the preferred type of inorganic pigment is silica, which can be used as is, in its anionic form, or after cationic modification. The silica may be selected from various types such as crystalline silica, amorphous silica, precipitated silica, fumed silica, silica gel, spherical and non-spherical silica. The silicon oxide may contain small amounts of metal oxides from the group Al, Zr, Ti. In general, depending on their production method, silica particles are grouped into two types, wet-processed particles and dry-processed particles (vapour-forming or pyrogenic). In the wet process, two types of reactions can be used to form these precipitated silica materials. The first is a process where sodium silicate is treated with mineral acids to form precipitated silicas. In the second method, pure silica materials are obtained by polycondensation of alkoxy or halosilanes. The vapor deposition method includes two types; one involves high temperature vapor phase hydrolysis of silicon halide to produce anhydrous silica (flame hydrolysis), and the other involves thermal reductive evaporation of quartz sand and coke in an electric furnace followed by air oxidation of the product, also to produce anhydrous silica (arc process). Pyrogenic silica refers to particles of anhydrous silica obtained by a vapor deposition process.

With respect to the silica particles preferably used in the ink jet printable coating, precipitated silica particles are particularly preferred. Precipitated silica differs from fumed silica in terms of the density of surface silanol groups and the presence or absence of pores, and the two different types of silica have different properties. The inventors of the present invention have surprisingly noted that the use of precipitated silica as a pigment in an inkjet-receptive coating, as compared to fumed silica, results in a higher color density printed on such a coating, and better adhesion is achieved with transparent layers subsequently layered over the print. The present inventors believe that the higher smoothness of the fumed silica inkjet-ready coating results in lower color density and lamination strength.

Alternatively, organic pigments, preferably selected from the list consisting of polystyrene, polymethyl methacrylate, silicones, melamine formaldehyde condensation polymers, polyesters and polyamides, may be used in the inkjet printable coating. Mixtures of inorganic and organic pigments may be used. In addition, hybrid pigments such as organosilica materials may be used. However, the most preferred pigment is an inorganic pigment.

The pigments included in the inkjet-ready coating preferably have an average particle size of 100 nm to 20 µm, in particular 1-12 µm, and even better 2 to 7 µm, which is ideal. Pigments with small particles can readily bond to paper or film, while pigments with large particles exhibit high water absorption capacity, thereby resulting in good print quality. The optimum average particle size is between 1 and 12 µm, preferably 2 to 7 µm.

The pigments included in the inkjet-receptive coating preferably have an average specific surface area of 20 to 1600 m ² /g and preferably between 250 and 1600 m ² /g in order to obtain good ink binder absorption capacity.

The pigments included in the inkjet-receptive coating preferably have an average pore volume of 0.2 to 3 ml/g, preferably between 1 and 3 ml/g.

Pigments having an average particle size between 2 and 7 µm, an average specific surface area between 300 and 800 ^m2 /g and an average pore volume between 1 and 2 ml/g create an ideal combination of absorbency, print quality and binding, i.e. no dust emissions from treated paper.

Preferably, the inkjet-ready coating in general, either in said first composition or said second composition, or both of the first and second compositions, further comprises a crosslinking agent, preferably selected from the list consisting of aldehydes, aziridines, isocyanates, epoxides. and borates. Such a crosslinker further binds the pigments in the inkjet-receptive coating and further limits the emission of dust from the paper or thermoplastic film thus printed. The presence of a crosslinking agent in any of the compositions further significantly increases the shelf life of the respective composition. The first and/or second composition preferably includes crosslinking agents in an amount of up to 0.1 to 25% of the total wet weight of the first and/or second composition.

The inkjet receptive coating as a whole, or said first and/or second composition, may further include additives other than crosslinking agents, in a total amount,

- 8 041198 comprising from 0.1 to 2% of the total weight of the first and/or second composition in the wet state, respectively. Such additives may be one or more of a fungicide, a defoamer, a leveling agent, a wetting agent such as alkylphenol ethoxylates, thickeners such as hydroxyethyl cellulose or xanthan gum.

With respect to the leveling agent, AREO (Alkylphenol ethoxylates) could be used.

As a preservative, BIT or MIT (benzisothiazolinone or methylisothiazolinone) could be used.

A copolymer of polyether and siloxane could be used as an antifoam agent.

The paper obtained by the method according to the invention is preferably impregnated with a thermosetting resin such as melamine resin, preferably after being printed on it by an inkjet printing process. For this purpose, the inkjet-receptive coating is preferably applied to the paper layer on only one side thereof, namely the side to be printed on. The other, opposite side is preferably untreated so that this opposite side exhibits the original porosity of the paper layer, which remains the original. The resin can then be embedded substantially from the underside of the paper core. In order to ensure sufficient impregnation of paper having an inkjet-receptive coating, the speed of the impregnation channel may be adjusted to a lower value, the resin may be made less viscous, the impregnation may be carried out under pressure, and/or the resin may be heated, for example, to a temperature between 45 and 100°C.

In general, it should be noted that although the paper and film obtained by the method according to the invention are printable using an inkjet printer, this does not exclude that the paper or film can eventually be printed using other methods, such as rotary gravure or offset printing. In addition, dust reduction and potentially better print quality are of interest in such a case. This is especially the case when water-based paints are used.

Said inkjet-receptive coating is preferably a liquid substance which is deposited on said paper layer and which is preferably force dried, for example in a duct drying oven, or by irradiation with infrared or near-infrared radiation, or by microwave drying. In the case of applying such an inkjet-receptive coating in at least two stages, at least one such drying operation is preferably carried out between said separate stages according to the first aspect of the invention. The liquid substance is preferably an aqueous suspension of at least said binder, and optionally said pigments. The first composition preferably has a dry matter content of 8 to 25% by weight, based on liquid matter. The second composition preferably has a dry matter content of 4 to 20% by weight, based on liquid matter. The dry matter content, as expressed in weight percent, is preferably higher in the first composition than in the second composition.

The deposition of the inkjet-receptive coating as said liquid substance can be carried out in any way, possibly by printing, for example inkjet printing, but preferably using a coating method, such as roller coating, for example, using one or more engraved rollers, sputtering , using dosing rollers, bead coating method, scattering, coating through a slot die. By the latter method, a coating is preferably obtained which covers at least 80% of the surface of the paper layer or film. Preferably, an excess amount of liquid substance is applied to the paper layer first, and then the excess material is again removed, for example extruded, until the desired weight is obtained. Inline measuring systems may be desirable for controlling and monitoring the weight of the inkjet-ready coating. Such methods reduce the risk of uncoated areas of the paper, which would lead to local defects in the printed pattern. The preferred liquid application equipment is a coater including reversible metering rollers. Such rollers can create a smooth coating surface.

The deposition of the liquid substance for the inkjet-receptive coating may be carried out in the impregnation channel or, alternatively, on the printing equipment immediately prior to the printing operation. In this latter case, any possible problems with the limited life of the inkjet receptive coating are solved. Preferably, the precipitation of the liquid substance is carried out while the paper or film is still in the form of an endless web, namely when unrolled without cutting. Such methods allow the inkjet-ready coating to be applied more evenly. In the case where the coating is wholly or partly carried out on the printing equipment, the printing equipment is preferably a roll-to-roll or roll-to-sheet printing machine, including a coater upstream of the printheads, for example, a coater - 9 041198 face, and / or additional print heads suitable for printing a liquid substance for the corresponding sublayer of the inkjet-receptive coating. Such additional printheads, such as an additional row of printheads, may have nozzles with a larger diameter than the heads used to actually print the pattern. For these nozzles, a resolution of 1 to 100 or even 1 to 25 dpi may suffice. Larger diameter allows jets of more viscous materials. According to a special embodiment, said first layer is applied to the paper or film using rollers, while the second layer is applied using such additional printheads. Such an embodiment is of particular interest when the ratio of pigment to binder in said second composition is low, ie below 2:1. In such a case, the liquid substance for said second layer will be easier to apply with said additional printheads.

Said liquid substance for said inkjet-receptive coating preferably exhibits a viscosity of 10 to 75 s as measured on a Din cup 4 funnel at 20°C. This property allows the liquid substance to be applied directly to the surface of the paper layer or film. In experiments, a solids content of about 12% and a viscosity of about 24 s provided a sufficiently uniform coating on a pre-treated paper layer, for example, when application was carried out by means of a roller coater.

Clearly, instead of a paper layer, according to the first aspect, a thermoplastic film such as a polyvinyl chloride (PVC) film, a polypropylene (PP) film, a polyethylene (PE) film, a polyethylene terephthalate (PET) film is processed with an inkjet printable coating. ) or thermoplastic polyurethane (TPU) film.

The preferred binder for the use of such films is a material based on polyurethane, based on acrylate or based on polyvinyl acetate. Also, in the case where the inkjet-ready coating is applied in at least two separate steps, the binder content of the first composition may be somewhat reduced compared to the paper ply treatment, as less absorption into the ply core is expected. The ratio of pigment to binder in the first composition is then preferably between 1:1 and 6:1.

It should be noted that the use of an inkjet receptive coating having a pH value of 3 or less constitutes in itself a specific independent patentable aspect of the present invention, whether or not such a pH value was obtained according to the second possibility for the aforementioned reactive ink component, and regardless of any other possible components of the inkjet-receptive coating. This particular patentable aspect can be defined as a process for producing an inkjet-printable paper or thermoplastic film or vitrimer film for use as a decorative paper or decorative film in a laminated panel, the process comprising at least the following steps:

a step of forming a paper layer, respectively a thermoplastic or vitrimer film;

the step of applying to at least one side of said paper layer, respectively said film, a coating of the composition to form an inkjet-receptive coating;

with such a characteristic that said composition has a pH value of 3 or less.

As explained above, the low pH of the composition and the resulting coating shows a strong tendency to disrupt the electrosteric stabilization of pigments in inkjet inks, thereby resulting in high print quality. It is clear that such a composition can be obtained in accordance with the second possibility described above, and that this specific independent aspect can have preferred embodiments corresponding to the preferred embodiments of the first independent aspect of the invention listed above, optionally, but not necessarily, containing the above one or many reactive paint components, binders or pigments. Said composition preferably includes at least a binder such as PVA and a pH lowering agent to 3 or less.

It is clear that the present invention also relates to paper layers and thermoplastic films, which are obtained using the methods according to the first aspect of the present invention. For the same purpose as in said first aspect, according to a second independent aspect, the invention also relates to paper or thermoplastic film or vitrimer film for inkjet printing, said paper or film being provided on at least one side with an inkjet receptive coating comprising at least a pigment and a binder, with the characteristic that said inkjet receptive coating further comprises a reactive ink component, and that said inkjet receptive coating preferably has a ratio of pigment to binder between 0/1 or 0.01/1 and 25 /1, preferably between 0/1 or 0.01/1 and 20/1. Said paper or film preferably comprises from 0.2 to 10 g/m ² , and even better between 0.5 and 5 g/m ² , of said reactive ink component, based on the weight of the dry coating. Said reactive paint component preferably comprises at least

- 10 041198 coagulant.

In addition, said paper or film preferably comprises from 0.2 to 10 g/m ² of pigment, based on the dry weight of the coating. More preferably, said paper preferably comprises from

0.2 to 10 g/m ² and preferably between 0.5 and 5 g/m ² of binder.

In addition, said paper or film may additionally exhibit one or more of the following properties:

said paper or film on its surface is substantially formed by said binder and/or said reactive ink component;

said paper or film is provided with a pigment in an amount that creates a specific surface area of the particles between 100 and 16000 m ² pigment surface/m ² surface area of the paper or film, or preferably between 150 and 500 m ² /m ² ;

said paper or film comprises from 0.05 to 5 g/m ² , preferably between 0.2 and 2 g/m ² of crosslinking agent based on the weight of the dry coating;

said paper or film comprises from 0.05 to 5 g/m ² , preferably between 0.2 and 2 g/m ² of particle surface modifying agent, based on the weight of the dry coating;

said paper or film comprises from 0.005 to 2 g/m ² , preferably between 0.05 and 1 g/m ² of wetting agent, based on the dry weight of the coating;

said paper or film comprises from 0.005 to 2 g/m ² , preferably between 0.05 and 1 g/m ² of defoamer, based on the dry weight of the coating;

said paper or film comprises from 0.005 to 2 g/m ² , preferably between 0.05 and 1 g/m ² of the fungicide, based on the weight of the dry coating.

In accordance with a third independent aspect, the invention further relates to a method for manufacturing a laminated panel, said panel comprising a base material and a top layer placed thereon with a printed decor, said top layer being substantially formed from a thermosetting resin and one or more paper layers, wherein said the paper layers comprise an inkjet based decorative paper according to a second independent aspect, and/or are obtained by a method according to the first independent aspect, and/or through the preferred embodiments of these aspects. In accordance with its fourth independent aspect, the invention also relates to a method for manufacturing a laminate or laminated panel, and said laminate or laminated panel at least includes a base, such as a sheet of non-woven material, or a base material, and placed on it a top layer with a printed décor, wherein said top layer is substantially formed from a thermoplastic material comprising one or more thermoplastic films, said thermoplastic films comprising a decorative film based on an inkjet thermoplastic film produced by a method according to a first independent aspect and/or by means of preferred embodiments implementation of this first aspect, as far as they relate to the processing of thermoplastic films.

In said third aspect, the inkjet paper is preferably printed by an inkjet printer, impregnated with an amount of said thermosetting resin, and bonded to said base material by hot pressing treatment. In said fourth aspect, the inkjet thermoplastic film is preferably printed by an inkjet printer and bonded to said base material by hot pressing processing. Said inkjet printer is preferably operable using water-based inks, more specifically the inkjet printer is of the single pass type and/or the inkjet printer operating in single pass mode is preferred.

Obviously, a paper layer having an inkjet receptive layer according to the invention can be used in a method for manufacturing panels having a decorative surface, said panels at least including a base and a top layer comprising a thermosetting resin, said top layer including a paper layer, having a printed pattern, with such a characteristic that pigment-containing inks applied to said paper layer using a digital inkjet printer are used to create said part of said printed pattern, and that the dry weight of the total volume of said pigment-containing inks applied to said paper layer is 9 g/m ² or less, preferably 3 to 4 g/m ² or less, wherein a water-based or so-called water-based ink is used for said pigment-containing ink. Limiting the dry weight of the applied ink results in a layer of ink that reduces the risk of press defects and delamination of the top coat. Indeed, the possible interactions between the ink layer and the thermosetting resin during the pressing operation are limited. Since the amount of ink applied is limited to a maximum of 9 g/m ² , ink-induced wrinkling or spreading of the paper can be brought to an acceptable level, which ensures stable further processing. For said pigment-containing ink, organic pigments are preferably used. Organic pigments are known to be more stable when exposed to sunlight or other sources of UV radiation. Said pigments of said pigment-containing paint preferably have an average particle size of less than 250 nanometers. Said dry weight of the pigmented ink applied is 5 g/m ² or less, for example 4 or 3 g/m ² or less. The printed pattern is preferably wholly or at least substantially such a pigmented ink, the printed pattern covering most, and preferably 80% or more, of the surface of said paper layer. Said total volume of applied pigment-containing ink is preferably less than 15 ml, or even better less than 10 ml or even less, for example 5 ml or less.

The paper layer according to the invention is preferably opaque and/or contains titanium oxide as a white color generating material.

The printed pattern applied to the paper layer according to the invention preferably covers most and preferably 80% or more of the surface of said paper layer.

Said paper layer, before or after printing and before or after application of the inkjet-receptive coating, is preferably provided with a thermosetting resin in an amount of 40 to 250% by dry weight of the resin relative to the weight of the paper. Experiments have shown that this range of resin application provides sufficient impregnation of the paper to prevent delamination to a large extent, and thereby stabilize the dimensions of the paper to a high extent.

The paper layer before or after printing and before or after application of the inkjet-receptive coating is preferably provided with a thermosetting resin in such an amount that at least the core of the paper is saturated with the resin. Such saturation can be achieved when the resin is introduced in an amount that corresponds to at least 1.5 - or at least 2 times the weight of the paper. It should be clear that the resin that is introduced into the paper layer is not necessarily present only in the core of the paper, but may also form surface layers on both flat sides of the paper. The inkjet-ready coating may then be present on the surface of the paper with an intermediate surface layer of thermosetting resin. According to a special embodiment, the paper layer is first impregnated through or saturated, and then, at least on the printed side, its resin is partially removed, and an inkjet-receptive coating can be applied.

The resulting resin-impregnated paper layer, ie after incorporation of the thermosetting resin, preferably has a relative humidity below 15% and even more preferably 10% by weight or below.

Typically, the paper and inkjet-receptive coating, whether impregnated with resin or not, has a relative humidity below 15% and even better 10% by weight or less at the time of printing.

The step of impregnating said paper layer with a thermosetting resin preferably comprises applying a mixture of water and resin to said paper layer. Application of said mixture could involve immersing the paper layer in a bath of said mixture and/or spraying, jet or otherwise coating said mixture onto said paper. The resin is preferably applied in a metered manner, for example using one or more squeeze rollers and/or doctor blades, to control the amount of resin added to the paper layer.

Said thermosetting resin is preferably a melamine-based resin, more particularly a melamine-formaldehyde resin, with a formaldehyde to melamine ratio of 1.4 to 2. Such a melamine-based resin is a resin that undergoes polycondensation when subjected to heat in a pressing operation. . The polycondensation reaction produces water as a by-product. Of particular interest to the invention are thermosetting resins of these types, namely those which release water as a by-product. The escaping water, as well as any remaining water in the thermoset resin prior to pressing, must be substantially removed from the curable resin layer before it is entrapped and causes the cured layer to become opaque. The ink layer present may prevent vapor bubbles from diffusing into the surface, however, the present invention provides measures to limit this difficulty.

An inkjet-ready coating is advantageous in this respect as it can provide an additional buffer to trap such escaping vapor. When an inkjet-ready coating is used that is porous and/or hydrophilic, as is the case when, for example, silica and/or polyvinyl alcohol are used, some of the water vapor generated by the curing of the thermosetting resin in the paper layer in the press may be absorbed by this coating so that the process becomes less prone to the formation of defects during pressing, such as due to blocked vapor bubbles. Other examples of such thermosetting resins formed by such a polycondensation reaction include urea-formaldehyde resins and phenol-formaldehyde resins.

The paper layer is preferably impregnated with resin only after application of the inkjet-receptive coating and after printing. Thus, the inkjet-receptive coating is not at all affected by the water contained in the aqueous resin mixture applied for the purpose of impregnation.

As is evident from the above, the method according to the third aspect of the invention is preferred

- 12 041198 but includes the step of hot pressing the printed and resin-impregnated paper layer, at least for curing the resin in the resulting resin-impregnated decorative paper. The method according to the invention preferably forms part of a DPL process as described above, in which the printed and resin-impregnated paper layer according to the invention is placed in a press bag as a decorative layer. Of course, this does not exclude that the process according to the invention would form part of a process for the manufacture of CPL (Compact Laminate) or HPL (High Pressure Laminate) in which the decorative layer is not pressed with at least numerous resin-impregnated core paper layers, for example of so-called kraft paper, forming a base under the decorative layer, and in which the resulting pressed and cured laminated layer, or laminated board, in the case of HPL, is glued to an additional substrate, such as particle board or MDF or HDF board.

An additional layer of resin is preferably applied over the printed design after printing, for example by means of an outer layer, i.e. a resin-impregnated carrier layer or liquid coating, preferably while the decorative layer is layered on the substrate, either without bonding or already being attached or glued. to him.

The paper layer or film according to the invention may be a colored, pigmented and/or dye-dyed base paper or film. The use of a colored and/or dye-dyed base layer makes it possible to further limit the dry weight of the applied paint to form a particular pattern or color. In the case of paper, a dye or pigment is preferably added to the stock prior to forming the paper sheet. Alternatively, the ink-receiving layer on said printable paper layer or film is dyed or pigmented with color pigments. However, according to the general spirit of the invention, the pigments contained in the inkjet-receptive coating are preferably colorless or white.

For printing the paper layer or film according to the invention, a digital inkjet printer is preferably used, which allows the creation of ink droplets with inkjet printing with a volume of less than 50 pl. The present inventors have found that working with droplets having a volume of 15 pl or less, such as 10 pl, provides significant advantages in terms of limiting the dry weight of applied paints. Preferably, a digital inkjet printer is used which allows multiple volumes of ink droplets to be handled in the same print, or with a so-called halftone or greyscale scale. The ability to print in gray scale or greyscale allows you to further limit the dry weight of the applied ink while maintaining excellent print clarity. Preferably, a digital inkjet printer is used which achieves a resolution of at least 200 dpi, or even better at least 300 dpi (dots per inch). Said digital inkjet printer is preferably of the single pass type in which the paper layer or film is provided with said printed pattern in a single continuous relative movement of the paper layer relative to the printer or printheads. This does not rule out that other digital inkjet printers, such as so-called multi-pass printers or plotter-type printers, are used for the practice of the invention. With single-pass type printers as well as multi-pass type printers, the printheads are preferably extended across the entire width of the paper to be printed. This is not the case with the plotter design, in which the print heads must perform a scanning motion in the direction of the width of the paper layer. However, the use of such printers is not excluded in the method according to the invention. It should be noted that multi-pass type printers have the advantage that a failed nozzle can be compensated for by printing in a subsequent pass. In printers of this type, the nozzles can be slightly shifted between passes so that at a particular place on the paper, dots are printed by several nozzles. With multi-pass equipment, or even in the case of a plotter, it is possible to perform automated maintenance or cleaning between successive passes when required. The problem with failed nozzles is particularly significant when water-based paints, or so-called aqueous pigmented paints, are used. Indeed, the nozzles can become clogged with colorful pigment due to the drying of the water. The risks of nozzle failure are reduced, for example, by using UV curable inks. In addition, when an inkjet receptive coating is used, the risk of nozzle failure can generally be increased. However, application of the two-layer inkjet receptive coating according to the first aspect of the present invention increases battery life by reducing dust generation.

Obviously, according to the most preferred embodiment of the present invention, the paper layer is still flexible during printing, and that the paper layer is attached to the substrate or takes the form of a board only after printing has been performed. According to one embodiment, the paper layer is already attached or loosely laid on the board-shaped substrate at the time of printing. Possible attachment to the substrate can be achieved by means of adhesives on

- 13 041198 urea-based, phenol-based, melamine-based, polyurethane-based and similar adhesives.

Such attachment can be achieved by compression treatment, whether it is a heat compression treatment or not.

The method according to the third aspect of the invention preferably further comprises the step of applying an anti-layer, or balance layer, to the surface of the substrate opposite the printed paper layer. In the case of a paper-based decorative layer, the counter or balance layer preferably includes a paper layer and a thermosetting resin, preferably the same resin as in the top layer.

Joint gluing of the backing in the form of a plate, the possible counterlayer and the possible transparent or translucent layer is preferably carried out in the same pressing treatment. According to the most preferred embodiment of the third aspect, these steps are performed in a DPL process mode.

According to the most important example of the invention, a standard printing paper, such as that used for rotogravure printing, having a basis weight between 60 and 90 g/m ² , is provided with an inkjet receptive coating according to the first aspect of the invention, and is printed to form a wood grain pattern. textures using a digital inkjet printer with water-based pigmented inks. The printed paper layer is then impregnated with melamine resin through a standard impregnation channel, namely roll, dip, inkjet and/or spray equipment. The resin impregnated paper layer is then dried to a residual moisture content of less than 10%, preferably about 7%. A package is formed from a resin-impregnated backsheet, a board-shaped base, a printed resin-impregnated paper layer, and a resin-impregnated paper layer forming a so-called top layer. The package is then pressed for less than 30 seconds at a temperature of about 180-210°C and a pressure of more than 20 bar (2 MPa), for example 38 bar (3.8 MPa). During pressing, the surface of the package is in contact with a structured pressing element, such as a structured pressing plate, and a relief is formed in the top layer of the resulting laminated panel. It is possible that the resulting embossing may be formed in a printed register on the resin-impregnated paper layer.

Furthermore, it is clear that the paper or thermoplastic film obtained according to the first aspect of the invention is suitable for use as decorative paper or decorative film in a process for the manufacture of floor panels, furniture panels, ceiling panels and/or wall panels.

Obviously, the above-mentioned printed pattern, board-shaped substrates, paper layers and thermoplastic layers can be cut using the methods according to the invention to obtain their respective final dimensions. Panels obtained by pressing in a DPL process or the like are preferably sawn or otherwise cut. Of course, other processing of the obtained panels is not excluded.

The base paper of the decorative paper produced by the method according to the invention preferably has a specific gravity of the base paper, i.e. without an inkjet-receptive coating, above 20 g/m ² , whereby, in the case of floor panels, a specific gravity between 55 and 95 g/m ² is obtained. .

The base film of the decorative film or the base paper of the decorative paper produced by the method of the invention preferably has a thickness of 0.05 mm or more, with a thickness between 0.05 and 0.5 mm being preferred.

With the intention of better illustrating the characteristics of the invention, the following, by way of non-limiting example, describes an embodiment with reference to the accompanying drawings, in which:

fig. 1 schematically shows a paper layer in one embodiment which has been coated with an inkjet-receptive coating in accordance with a preferred embodiment of the method according to the first aspect of the invention;

fig. 2 and 3 is an enlarged view of the region F3 illustrated in FIG. 1, and in the case of FIG. 2, only the first layer of the two-layer inkjet receptive coating has been applied to the paper layer;

fig. 4 shows some steps of the method according to the third aspect of the invention;

fig. 5 shows in perspective a panel obtained by the method of FIG. 4;

fig. 6 shows a view along the line VI-VI indicated in FIG. 5;

fig. 7 shows a piece of equipment for use among others in the first range of the invention;

fig. 8 schematically shows a plan view of the printer operating in single pass mode;

fig. 9 contains a graph of the obtained color densities with treated papers according to the invention compared to papers not related to the invention.

Fig. 1 schematically illustrates a processed paper layer 1 which is printable with an inkjet printer. The printable paper layer 1 includes a paper sheet 2 provided with

- 14 041198 inkjet receptive coating 3, which includes the first layer 4 of the first composition and the second layer 5 of the second composition. The paper layer 3 in this case is a printable base paper having a specific weight of about 70 g/m ² and with an average drag, as expressed by the Gurley porosity value, below 30 s.

In a general sense, it should be noted that the dimensions of the illustrated paper sheet 2 and layers 4-5 in the figures are not drawn to scale in order to better illustrate the invention.

Fig. 2 and 3 show that the inkjet receptive coating 3 includes pigments 6 and a binder 7. Both the composition of the first layer 4 and the composition of the second layer 5 both include a binder. The inkjet receptive coating 3, more specifically at least its second layer 5, further comprises a reactive ink component, more specifically a coagulant, such as in accordance with the first aspect of the invention. However, it is clear that the figures are also illustrative of many aspects of the present invention in cases where a reactive paint component, more specifically a paint destabilizing agent other than a coagulant, such as a metal cation salt, has been used.

Fig. 2 illustrates a semi-finished product 8 in which only the first layer 4 has been applied to the paper sheet 2. The binder 7 is partially absorbed by the paper sheet 2 and this is uneven. Unbound and/or poorly bound pigments 6 are present on the surface 9. Such pigments 6 lead to the release of dust during further processing of such a semi-finished product 8. The resulting surface 9 of the first layer 4 is also uneven.

Fig. 3 shows a paper layer 1 in which a second layer 5 has also been deposited on top of the first layer 4. FIG. 3 shows that the second layer 5 evens out the surface 9, resulting in a more uniform surface 10 of the second layer and paper layer 1. In this case, the composition of the second layer 5 has a lower ratio of pigment to binder than the composition of the first layer 4, and in addition , includes a reactive paint component. It is clear that this does not exclude that the first layer 4 may also contain a reactive paint component, either the same as or different from the reactive paint component of the second layer 5, and possibly in different concentrations.

It should be noted that FIG. 3 shows an example of a paper layer in which, on the surface of the treated paper layer, less than 10 weight percent of the total amount of pigment 6 is unbound or free, and in which the surface 10 of the second layer is substantially, and in this case completely, formed by the binder component 7.

Fig. 4 illustrates a method for manufacturing laminated panels 11 of the type shown in FIG. 5 and 6. The method is presented as illustrating a third independent aspect of the invention as described in the introduction to this patent application. The resulting decorative panels 11 at least include a base 12 and a top layer 13. The top layer 13 includes a paper layer 1 made in accordance with the first aspect, and provided with a printed pattern or digitally printed ink layer 14 depicting the texture of wood, as here in this case. The method according to an exemplary embodiment includes at least the step S1 of obtaining said paper layer 1 having an inkjet-receptive layer and a printed pattern with a thermosetting resin 15. the layer is immersed in a bath 18 with said resin 15, more specifically with a mixture of water and resin 15. The paper layer 1 is then passed through with aging, for which in this case it is carried upwards. The aging allows the resin 15 to be absorbed into the core of the paper. The paper layer 1 then enters the second impregnation station 19 where the paper layer 1 in this case is again immersed in a bath 18 with resin 15, more specifically a mixture of water and resin 15. layer 1.

In the example, several squeegees 21 are present to partially remove the resin from the surface of the paper layer 1 impregnated with resin.

In the second step S2, the resin-impregnated paper layer 1 is dried and its residual moisture content is brought to a value below 10%. In the example, channel drying ovens are used, but other heating equipment such as microwave or infrared drying equipment may alternatively be used.

Fig. 4 also illustrates that the continuous paper layer 2 is cut into sheets 23 and stacked.

In addition, FIG. 4 illustrates that in the subsequent step S3, the resulting sheets 23 or paper layer 1 are placed in a stack for pressing in a deck press 24 with a short stroke between the upper and lower press plates 25-26. Said package includes, from bottom to top, a backsheet 27, a board-shaped backing 12, the aforementioned paper layer 1 and a backsheet 28, both of the backsheet 27 and backsheet 28 including paper sheet 2 and resin 15. leads to mutual connection between the layers 1-12-27-28 that make up the package, including with the base 12, and also to solidification, or curing, of the resin 15 present. More specifically, the polycondensation reaction of the melamine-formaldehyde resin proceeds here

- 15 041198

15, with the release of water as a by-product.

The upper press platen 25 is a structured press platen which creates a pattern in the surface of the melamine on the panel 1 during the same press treatment in step S3 by bringing the structured surface 29 of the upper press platen 25 into contact with the melamine of the cover layer 28.

Fig. 5 and 6 illustrates that the resulting decorative panel or laminated panel 11 may be in the form of a rectangular and oblong laminated floor panel, with a pair of long sides 30 and a pair of short sides 31, and having an HDF or MDF base 12. In this case, the panel 11 is at least on the long sides 30 is provided with connecting elements 32 that allow fixing the respective sides 30 together with the sides of a similar panel both in the direction R1 perpendicular to the plane of the connected panels, and in the direction R2 perpendicular to the connected sides, and in the plane of the connected panels. As illustrated in FIG. 6, such connecting elements or connecting parts can in principle be in the form of a tongue 33 and a groove 34 provided with additional joint fastening elements 35, providing said fixation in the direction R2.

Fig. 7 shows that, in accordance with a preferred embodiment, at least one of the first layer 4 and the second layer 5 of the inkjet receptive coating 3 can be obtained by coating in one of these two separate stages of applying the liquid substance 36 to the paper sheet 2. In this case, the deposition of the first layer is illustrated. A device 37 is used, including reversible metering rollers 38. Such a device 37 can initially apply an excess of liquid substance 36, which is extruded to the desired weight by means of rollers 38, which can also create a smooth coating surface. The resulting semi-finished product 8 is then preferably dried, for example by means of a duct drying oven, until a residual moisture level is preferably below 10%, or about 7%. The resulting processed paper is then further processed by applying a second layer 5 of the inkjet receptive coating 3. Although this is not illustrated here, it can be done in a similar way to some extent. It is clear that, as an alternative to the device 37, other application methods can be used, such as application with one or more engraved rollers, possibly also moving in the opposite direction.

Fig. 8 illustrates that a paper layer 1 having an inkjet receptive coating according to the first aspect of the invention can be printed using an inkjet printer 39, which in this example includes several rows 40 of printheads that are placed over the entire printable area of the paper sheet 1. Printer 39 in this example refers to a printer of a single pass type, and the creation of a printed pattern involves the relative movement of the specified inkjet printer 39, more specifically the rows 40, and the specified paper layer 1 during printing in the direction of printing D. In this case, the rows 40 and the printheads are stationary while the paper layer 1 moves during ink spraying onto the paper sheet 1, more specifically the inkjet receptive coating 3 applied to the paper sheet. The paper layer 1 is printed during a single continuous movement of the paper layer 1 relative to the printer 39 or rows 40 of printheads. The resulting printed pattern 14 includes in this example a wood motif having wood veins 41 extending generally in the direction D of the print. A drying station 42 is preferably located downstream of the printer 39.

After the inks have dried, the printed paper sheet is preferably wound onto a roll and used in the method illustrated in FIG. 4 as roll 16.

With the intention of further illustrating the invention, hereinafter, without any limitation, some exemplary embodiments of the invention are listed with reference to FIGS. 9.

Example C.

kg of commercially available amorphous silica (Syloid ED5) was dispersed in 41 kg of water and heated to a temperature of 80°C. To this mixture was added 2.7 kg of silane (Dynasilan) acting as a particle surface modifying agent or coupling agent and allowed to stir for 30 minutes. Then 2.3 kg of a 40% solution of glyoxal (BASF) was added as a crosslinker and mixed for an additional 30 minutes. Then 0.5 kg of boronic acid, also acting as a crosslinker, was added and mixed for 10 minutes.

Separately, 2.5 kg of polyvinyl alcohol (mowiol 20/98 from Kuraray) was dissolved in 26.4 kg of water at 90° C. and stirred until completely dissolved (2 hours).

After that, a dispersion of silica was added to the Moviol solution and mixed thoroughly. To this mixture was added 0.04 kg of leveling agent, 0.04 kg of defoamer and 0.03 kg of fungicide and mixed for an additional 5 minutes before the coating composition was bottled and cooled. The resulting coating composition does not contain any reactive paint component or

- 16 041198 paint destabilizing agent. In particular, boronic acid is present in an amount that is not capable of lowering the pH value of the inkjet-receptive coating composition to pH 3 or below.

The ratio of pigment to binder was 2.4/1 and the solids content was 13.5% by weight.

The coating composition was brought to the proper viscosity for coating with a reverse engraved roller (30 seconds as measured on a Din cup 4 funnel at 23° C.) by adding water. The solids content was adjusted to 10% by weight.

Bare paper (Technocel MPK 3723) with a specific weight of 20 g/m ² was coated with a reverse engraved roller and dried.

Example D.

kg of commercially available amorphous silica (Syloid ED5) was dispersed in 41 kg of water and heated to a temperature of 80°C. To this mixture was added 2.7 kg of silane (Dynasilan) acting as a particle surface modifying agent or coupling agent and allowed to stir for 30 minutes. Then 2.3 kg of a 40% solution of glyoxal (BASF) was added as a crosslinker and mixed for an additional 30 minutes. Then 0.5 kg of boronic acid, also acting as a crosslinker, was added and mixed for 10 minutes. Thereafter, 5 kg of a 40% aqueous solution of polyDADMAC (polyquat40U05 from Katpol) was added and mixed for an additional 10 minutes. The polyDADMAC material is a polyionic polymer that acts as an ink destabilizing agent in accordance with the invention.

Separately, 2.5 kg of mowiol 20/98 (Kuraray) were dissolved in 26.4 kg of water at 90° C. and stirred until completely dissolved (2 hours).

After that, a dispersion of silica was added to the Moviol solution and mixed thoroughly. To this mixture was added 0.04 kg of leveling agent, 0.04 kg of defoamer and 0.03 kg of fungicide and mixed for an additional 5 minutes before the coating composition was bottled and cooled.

The ratio of pigment to binder was 2.4/1 and the solids content was 18.5% by weight.

The coating composition was brought to the proper viscosity for coating with a reverse engraved roller (30 seconds as measured on a Din cup 4 funnel at 23° C.) by adding water. The solids content was adjusted to 15% by weight.

Bare paper (Technocel MPK 3723) with a specific weight of 20 g/m ² was coated with a reverse engraved roller and dried.

Example E.

Two coating compositions were obtained.

First cover composition:

13.4 kg of commercially available amorphous silica (Syloid ED5) was dispersed in 41 kg of water and heated to a temperature of 80°C.

To this mixture was added 6 kg of silane (Dynasilan) and left to stir for 30 minutes. Then 5.2 kg of a 40% solution of glyoxal (BASF) was added as a crosslinker and mixed for an additional 30 minutes. Then 0.5 kg of boronic acid, also acting as a crosslinker, was added and mixed for 10 minutes. Then 5 kg of polyquat40U05 (Katpol) was added and mixed for an additional 10 minutes.

Separately, 2.5 kg of mowiol 20/98 (Kuraray) were dissolved in 26.4 kg of water at 90° C. and stirred until completely dissolved (2 hours).

After that, a dispersion of silica was added to the Moviol solution and mixed thoroughly. To this mixture was added 0.04 kg of leveling agent, 0.04 kg of defoamer and 0.03 kg of fungicide and mixed for an additional 5 minutes before the coating composition was bottled and cooled.

The ratio of pigment to binder was 5.5/1 and the solids content was 26% by weight.

Second cover composition:

kg of the first coating composition was mixed with 54 kg of an 8% mowiol 20/98 mixture in water.

The ratio of pigment to binder was 0.95/1 and the solids content was 17% by weight.

Both coating compositions were brought to the proper viscosity for coating with a reverse engraved roller (30 seconds as measured on a Din cup 4 funnel at 23°C) by the addition of water. The solids content of the first coating composition was 20% by weight and the second coating composition had a solids content of 11% by weight.

A blank paper (Technocel MPK 3723) was coated with an inkjet receptive coating in two successive stages, with the first layer having a specific weight of 12 g/m ² respectively the first

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Claims (9)

of the coating composition was applied with a reverse etched roller and then dried, and then a second layer with a specific gravity of 12 g/m ² of the second coating composition was applied over it, also with a reverse etched roller, and then dried. Get proof prints. The treated papers of Examples C to E, as well as the untreated base paper (Technocel MPK 3723) labeled A paper and the commercially available inkjet quality paper labeled B paper, were inked using a pre-dosed application method. . The strong absorption by the papers precluded the coating by the Meyer rod method. For this reason, a K printing proofer from RK printcoat instruments was used with a 100 lines/inch printing plate and water-based red digital ink. The prints were then analyzed on a Byk Spectro guide handheld spectrophotometer to measure L, a and b values. Then, the CD value (color density) was calculated by multiplying the values a by b and dividing the result by L. Then, all papers from A to E were classified according to the CD value, which is shown in FIG. 9. The abscissa contains various test papers, where A represents the raw base paper, B represents the commercially available inkjet quality paper, and C-E correspond to the treated papers of examples C-E. The ordinate gives the CD values for each security. A higher CD value corresponds to better optical density and means better print quality. This simplified color density (CD) value allows you to quickly evaluate and qualify coatings. From FIG. 9, it can be seen that the use of ink destabilizing agents in the inkjet receptive coating has a significant effect on the resulting color density. In the preferred embodiment, where the inkjet-ready coating is applied in two stages with different coating compositions, a particularly high color density is achieved. The present invention is in no way limited to the embodiments described above, but such methods, paper layers, thermoplastic films and vitrimer films can be practiced in several ways without departing from the scope of the invention. CLAIM 1. An inkjet printable paper for use as decorative paper in a laminated panel, wherein the paper is a paper layer (1) containing a base paper (2) having an average aerodynamic drag with a Gurley porosity value of 30 s or below, and at the same time, at least one side of the paper layer (1) contains an inkjet receptive coating (3), including at least a pigment (6) and a binder component (7), characterized in that said inkjet receptive coating (3) further comprises a reactive ink component, more specifically an ink destabilizing agent that interferes with the stabilization of pigments in ejected droplets, and in that the paper containing said inkjet receptive coating (3) has a Gurley porosity value between 30 and 120 s . 2. Paper according to claim 1, characterized in that said reactive ink component comprises a polyionic polymer, preferably polyDADMAC. 3. Paper according to claim 1, characterized in that said reactive ink component comprises a substance that changes the pH value of said inkjet-receptive coating (3), preferably such that the composition of the inkjet-receptive coating has a pH value of 3 or lower. 4. Paper according to claim 3, characterized in that said substance is selected from the list consisting of formic acid, tartaric acid, acetic acid, hydrochloric acid, citric acid, phosphoric acid, sulfuric acid, AlCl ₃ and boronic acid. 5. Paper according to claim 1, characterized in that said reactive ink component comprises a metal salt, preferably a salt with a metal cation. 6. Paper according to claim 5, characterized in that said metal salt is selected from the list consisting of CaCl ₂ , MgCl ₂ , CaBr ₂ , MgBr ₂ , CMA (calcium magnesium acetate), NH ₄ Cl, calcium acetate, ZrCl 4 and magnesium acetate. 7. Paper according to claim 1, characterized in that said reactive ink component includes a coagulant. 8. Paper according to claim 7, characterized in that said coagulant is selected from the list consisting of sodium aluminate, a double sulfate salt such as alum, polyaluminum chloride, polyacrylate, dicyandiamide and polyacrylamide. 9. Paper according to claim 1, characterized in that said inkjet receptive coating (3) comprises a first layer (4) from a first composition and a second layer (5) from a second composition, both compositions at least including said binder component (7). -