DE202016008997U1 - Composition for use in a process for the manufacture of inkjet printable paper for use as decorative paper - Google Patents

Abstract

Composition for use in a process for the production of paper (1) printable with an inkjet printer, the paper being intended for use as a decorative paper in a laminate panel, at least one side of the paper layer (1) being coated with an inkjet receptive coating (3 ) is coated, a first layer (4) with the composition and subsequently a second layer (5) with a second composition being applied, both compositions comprising at least one binder (7), characterized in that the composition is a liquid substance which is a water-based suspension of at least one binder (7) and preferably pigments (6), the dry matter content of the first composition being 8 to 25 percent by weight of the liquid substance.

Description

The present invention relates to a method for producing panels with a decorative surface, or so-called decorative panels. The invention also relates to a method for producing paper which can be printed with an inkjet printer for use as decorative paper in such panels and to the paper which can be obtained using such a method.

In particular, the invention relates to a method of manufacturing laminate panels, the panels comprising at least a substrate material and a top layer provided thereon with a printed decoration. The top layer is formed from thermosetting resin and one or more paper layers, the paper layers comprising a decorative paper with a printed pattern. The panels of the invention can relate to furniture panels, ceiling panels, floor panels or the like, these panels preferably being a wood-based substrate, such as an MDF or HDF substrate (medium-density or high-density fibreboard) or a substrate material consisting of chipboard or essentially is made from these include.

Traditionally, the decor or pattern of such panels is printed on paper using offset or rotogravure printing. The paper obtained is taken up in a so-called laminate panel as a decorative paper. According to the DPL process (direct printing laminate), the already printed paper or decorative paper is coated with a melamine resin to form a decorative layer. A stack is then formed, comprising at least one plate-shaped substrate, the decorative layer and possibly a protective layer on top of the decorative layer, the protective layer or the overlay also being based on resin and / or paper. The stack is pressed, and the pressing treatment leads to a mutual connection or gluing of the decorative paper, the substrate and the protective layer, as well as a hardening of the resin present in the stack. As a result of the pressing process, a decorative panel is obtained with a melamine surface which can be highly abrasion resistant. A counter-layer or leveling layer can be applied to the underside of the plate-shaped substrate, or, as an alternative, a decorative layer can also be attached to the underside, especially in the case of laminate panels for furniture. Such a counter-layer or leveling layer or any other layer on the underside of the laminate panel limits or prevents possible bending of the decorative panel and is applied during the same pressing treatment, for example by providing a resin-bearing paper layer as the bottom layer of the stack side of the stack opposite the decorative layer. For examples of a DPL process, see EP 1 290 290 Reference, which is further known to provide a relief in the melamine surface during the same pressing treatment or pressing operation by bringing the melamine surface into contact with a structured pressing element, for example a structured pressing plate.

Printing on paper using an analog printing process, such as rotogravure or offset printing, at affordable prices inevitably leads to large minimum order quantities of a particular decorative paper and limits the flexibility that can be achieved. A change in the decor or pattern requires the printing equipment to be shut down for around 24 hours. This downtime is needed to change the printing rollers, to clean the printing equipment and to adjust the colors of the new decoration or pattern to be printed.

Adding a resin to the printed paper can cause the paper to expand, which is difficult to control. Problems can arise, especially in cases where, as in EP 1 290 290 , a correspondence between the relief and the printed decoration is desired.

With the aim of limiting the cost of the decorative paper and preventing it from expanding, a method is known, such as from US Pat DE 197 25 829 C1 , in which the analog printing process, for example an offset process, is used to print directly on the plate-shaped substrate, be it with intermediate preparatory layers, such as melamine-based layers, or not. The printed decor is covered with melamine-based layers and the whole created is cured using a pressing process. Printing directly on the panel can result in poor print quality. With any internal inhomogeneity in the panel or on its surface, there is a high risk of showing through to the upper surface, with a visual flaw being formed on the surface of the covered decorative panel. The printing process also presents the same problems of attainable flexibility as printing on paper. Ultimately, any quality problems result in a loss of valuable panel material.

Instead of analog printing techniques, digital printing techniques, in particular inkjet printing techniques, are becoming increasingly popular for the production of decorations or patterns, be it on paper or directly on a plate-shaped substrate, possibly with intermediate ones preparatory shifts. Such digital techniques can significantly increase the flexibility in printing decorations. Reference is made to EP 1 872 959 , WO 2011/124503 , EP 1 857 511 , EP 2 431 190 , EP 2 293 946 and WO 2015/118451 where such techniques are disclosed.

EP 2 132 041 discloses a method comprising at least the step of providing the paper layer with thermosetting resin and the step of providing the resinized paper layer with at least a portion of the printed pattern. Preferably, multicolored printed patterns are used for the implementation of a decor, e.g. B. represents a wood pattern, applied to the above-mentioned paper layer. Such decor extends over most, or even all, of the resinous paper layer. Such a technique is off as such, for example EP 2 132 041 known where a digital printer, particularly an ink jet printer, is applied. However, it was very difficult to process such printed paper reliably in order to produce laminate panels, as in a DPL process, since pressing errors can occur in the resin surface and milling, drilling or sawing through the laminate surface or on the edge thereof often leads to cracks in the upper one Shift leads. Furthermore, the inks or dyes from EP'041 can excessively wet the paper layer and cause wrinkling effects or bleeding during the further treatment of the printed paper, which leads to an unstable and / or slow production process. In order to solve this problem, EP'041 suggests drying the printed paper layer immediately.

EP 1 044 822 , EP 1 749 676 and EP 2 274 485 disclose the use of an inkjet receptive coating to improve print quality on rough decorative paper. Such an inkjet receptive coating comprises pigments and a polymer such as polyvinyl alcohol.

As in WO 2015/118451 It is recognized that the use of paper treated with an inkjet receptive coating can lead to malfunction of the printing equipment. Dust can peel off the inkjet receptive coating and cause all sorts of deleterious effects on the critical parts of an inkjet printer. For example, the dust can clog one or more of the nozzles and cause printing errors. WO 2015/118451 suggests avoiding excessive bending of the paper in the printing equipment to minimize the release of dust.

During his own research, the inventor also encountered problems with subsequent impregnation of dust-releasing paper layers, even in cases in which the paper layers were already printed. The released dust can contaminate the resin bath, rollers, cameras and other equipment in, or in the immediate vicinity of, the impregnation channel, leading to defects in the end product or the equipment used.

WO 2015/118451 further recognizes that non-uniform application of the inkjet receptive coating can result in unacceptable defects that will only become apparent after printing. In fact, if the inkjet receptive coating is applied unevenly, the amount of bleeding of the subsequently applied inks may vary in accordance with the distribution of the inkjet receptive coating. Typically, zones of lower print quality can be observed which extend in the direction in which the coating is applied. WO 2015/118451 suggests to mitigate this problem by also extending the printed wood pattern with its wood nerves in the direction of application, so that the unintended production variation can be mistaken for a natural aspect of the wood grain.

The present invention is primarily directed to an alternative method of making panels having a decorative finish or paper for use in such panels and, in accordance with several of its preferred embodiments, seeks one or more problems encountered in the prior art , to solve.

• - den Schritt des Bereitstellens einer Papierschicht;
• - den Schritt des Beschichtens zumindest einer Seite der Papierschicht mit einer Tintenstrahlaufnahmebeschichtung, umfassend Pigment und Bindemittel;

mit der Charakteristik, dass die Tintenstrahlaufnahmebeschichtung in mindestens zwei Teilschritten aufgetragen wird, wobei entsprechend eine erste Schicht mit einer ersten Zusammensetzung und, nachfolgend, eine zweite Schicht mit einer zweiten Zusammensetzung aufgetragen werden, wobei beide Zusammensetzungen zumindest das Bindemittel umfassen.Therefore, in accordance with its first independent aspect, the present invention relates to a method for producing ink-jet printable paper for use as a decorative paper in a laminate panel, the method comprising at least the following steps:

• the step of providing a paper layer;
• the step of coating at least one side of the paper layer with an ink jet receptive coating comprising pigment and binder;

having the characteristic that the ink jet receiving coating is applied in at least two sub-steps, a first layer having a first composition and, subsequently, a second layer having a second composition being applied accordingly, both compositions comprising at least the binder.

The inventor has observed that the application of the ink jet receiving coating in two sub-steps leads to better integration or binding of the pigment. The risk of dust being released from the paper is reduced compared to a situation where the same amount of pigment is applied in just one coating step. According to the inventor, this surprising effect is due to the fact that the first layer forms a type of barrier for the binder of the second layer to prevent penetration into the paper layer. The second layer binder is more effective at binding pigments that would otherwise be loosely or poorly bound to the surface of the paper. The reduction of loose or poorly adhering pigments leads to a significant reduction in the release of dust from the paper during further treatment, e.g. B. Printing, impregnation with resin, thereof.

The two-step application of the inkjet receptive coating can also result in a more uniform application of the entirety of the inkjet receptive coating. Where the first composition can be partially absorbed in the paper layer in a non-uniform manner, which can therefore lead to a non-uniform first layer, the second composition at least to some extent offsets the possible non-uniformity.

The method of the invention is of particular interest when starting from layers of paper whose average air resistance is low, e.g. With a Gurley value of 30 seconds or less, e.g. B. 25 seconds or less. In such cases, the binder contained in the first layer tends to be absorbed to a large extent in the paper pulp, leaving the pigment content largely unbound on the surface. Preferably the paper layer is a standard printing base paper or other untreated paper layer with an average air resistance, expressed by a Gurley value of 30 seconds or less. It is of course not to be ruled out that, in the method of the invention, according to an alternative embodiment, this is started from a paper which has been treated with a thermosetting resin before the application of the ink jet receiving coating. Preferably, in this latter case, the resin-coated paper layer has an average air resistance with a Gurley value of 100 seconds or less. Also in such a case, the application of an inkjet receptive coating in two sub-steps has significant advantages, e.g. In terms of dust release, minimizing bleeding of the ejected inks, uniform application of the ink jet receptive coating.

Preferably the paper layer to which the inkjet receptive coating is applied has a basis weight of 50 to 100 grams per square meter, e.g. B. between 60 and 80 grams per square meter.

Preferably, the side of the paper layer to which the inkjet receptive coating is to be applied has been smoothed, preferably during paper production. The smoothing of the paper reduces the amount of binder of the first composition which penetrates into the core of the paper, so that the pigments contained in the first composition can be better bound by the available binder substance and that the variations in the absorption can be smaller.

Preferably the paper obtained using the method of the invention has, i. H. comprising the inkjet receptive coating, a Gurley value between 60 and 120 seconds, and preferably between 80 and 100 seconds. Such a paper layer results in excellent print quality because the deposited inks tend to bleed less into the paper and because the positional correspondence, or so-called register, between printed patterns applied with different inkjet printheads can be more easily achieved and maintained . In fact, a relatively high Gurley value leads to a more dimensionally stable paper because it is less susceptible to being soaked up by water. Regarding thermosetting resin impregnation of such a high Gurley value paper, consideration might be given to slowing down the impregnation channel speed, employing pressurized impregnation techniques, and lowering the viscosity of the impregnating resin.

In general, the method of the invention allows the application of an inkjet receptive coating having a higher pigment content, and hence a higher performance or higher rate of absorbing the carrier of the applied inks, e.g. B. water in the case of aqueous pigmented inks, while maintaining or even reducing the dust release from the treated printable surface. The higher power or speed of absorbing the carrier can lead to a higher pressure definition. Since the carrier is absorbed essentially vertically in the inkjet receptive coating, ie without substantial lateral bleeding, the pigments are held at the point where the ink was applied, ie the pigments are not driven sideways along with the carrier of the ink. As noted above, any bleeding that may still be present can turn itself into manifest in a more even manner due to the application of the second layer of the inkjet receptive coating, which partially or fully offsets the first layer.

1. 1. - die Eigenschaft, dass sowohl die erste Schicht als auch die zweite Schicht Pigment und Bindemittel umfassen, allerdings mit einem unterschiedlichen Pigment-Bindemittel-Verhältnis;
2. 2. - die Eigenschaft, dass das Trockengewicht des für die erste Schicht und für die zweite Schicht aufgetragenen Materials unterschiedlich ist;
3. 3. - die Eigenschaft, dass sowohl die erste Schicht als auch die zweite Schicht Pigment und Bindemittel umfassen, wobei die durchschnittliche Partikelgröße der in der ersten Schicht enthaltenen Pigmente verschieden von der, vorzugsweise größer als die in der zweiten Schicht enthaltene durchschnittliche Partikelgröße ist.

According to a preferred embodiment, the first layer and the second layer differ in that they exhibit one or more of the following properties:

1. 1. The property that both the first layer and the second layer comprise pigment and binder, but with a different pigment-binder ratio;
2. 2. the property that the dry weight of the material applied for the first layer and for the second layer is different;
3. 3. The property that both the first layer and the second layer comprise pigment and binder, the average particle size of the pigments contained in the first layer being different from, preferably greater than, the average particle size contained in the second layer.

In view of the first mentioned property, the first composition preferably has a pigment-to-binder ratio which is greater than the pigment-to-binder ratio of the second composition. In this way, the binder of the second layer primarily binds the pigments of the first layer and evens out irregularities in the first layer.

The pigment to binder ratio in the second composition is preferably less than 2: 1 and is preferably between 0.2: 1 and 2: 1. When the ratio in the second composition is below 1.5: 1, extremely low dust release was observed.

Whether in combination with the mentioned preferred second composition or not, the pigment-binder ratio in the first composition can be selected between 1: 1 and 10: 1 or 2: 1 and 10: 1 and is preferably 3.5: 1 or greater than 3.5: 1, and more preferably 5.5: 1 or greater than 5.5: 1, although preferably less than 7: 1.

A good combination of the first and the second composition is achieved when the ratio of pigment to binder in the second composition is between 0.2: 1 and 2: 1 and the ratio of pigment to binder in the second composition is between and including 3, 5: 1 and 7: 1 is.

With regard to the second property mentioned, it is of course not excluded that the same dry weight would be applied to both layers. In such a case, however, it is preferred to apply different pigment-binder ratios in the first and second compositions. Preferably, a dry weight of between 5 and 20 grams per square meter of material is applied to the paper layer for both layers, and more preferably between 8 and 18 grams per square meter. In cases where the dry weight of material applied for the first layer and the second layer is different, preferably the first layer comprises the highest dry weight of material, e.g. B. at least 20% more than the second layer.

With regard to the third property mentioned, the larger pigment particles are preferably contained in the first composition. The use of large particles in the first layer offers excellent absorption of the ink carrier, while the use of small particles in the second layer offers a balancing effect and a good reduction in dust release on the surface of the paper layer. Preferably, in such a case, the pigment particles in the first composition have an average particle size between 1 and 20 micrometers. The pigment particles in the second composition preferably have an average particle size between 100 nanometers and 1 micrometer.

According to the most preferred embodiment, at least or mainly silicon dioxide particles are used for the pigment of the ink jet receiving coating and / or at least or mainly polyvinyl alcohol is used for the binder. The silicon dioxide particles are preferably treated with silane. Silane treatment of the pigments further improves the dust-release properties of the ink-jet receiving coating obtained and thus of the paper being treated. The silane treatment can refer to a treatment with a coupling agent such as amino-organosilanes, hydroxysilanes, dipodal silanes and / or other silanes. The adhesion promoter is preferably selected in such a way that the risk of yellowing on aging of the ink jet receptive coating obtained is low. The adhesion promoter preferably forms 0.1 to 10% of the total wet weight of the first and / or the second composition.

According to variants, the ink jet receiving layer comprises, as a binder, a polymer selected from the group consisting of: hydroxyethyl cellulose; Hydroxypropyl cellulose; Hydroxyethyl methyl cellulose; Hydroxypropyl methyl cellulose; Hydroxybutylmethyl cellulose; Methyl cellulose; Sodium carboxymethyl cellulose; Sodium carboxymethyl hydroxyethyl cellulose; water soluble ethyl hydroxyethyl cellulose; Cellulose sulfate; Vinyl alcohol copolymers; Polyvinyl acetate; Polyvinyl acetal; Polyvinyl pyrrolidone; Polyacrylamide; Acrylamide / acrylic acid copolymer; Polystyrene, styrene copolymers; Acrylic or methacrylic polymers; Styrene / acrylic copolymers; Ethylene-vinyl acetate copolymer; Vinyl methyl ether / maleic acid copolymer; Poly (2-acrylamide-2-methylpropanesulfonic acid); Poly (diethylenetriamine-co-adipic acid); Polyvinyl pyridine; Polyvinylimidazole; Polyethyleneiminepichlorohydrin modified; Polyethyleneimines ethoxylated; ether bond-containing 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; Chitins; Chitosans; Strength; Collagen derivatives; Collodion and agar-agar.

As stated above, preferred binders for the ink jet receiving layer include polyvinyl alcohol (PVA), but a vinyl alcohol copolymer or a modified polyvinyl alcohol can be used according to variants. The modified polyvinyl alcohol may be a cationic type polyvinyl alcohol such as the cationic polyvinyl alcohol grades from Kuraray such as POVAL C506, POVAL C118 from Nippon Goshei.

The binder contained in the first and / or the second composition can also be formed by a mixture of the options listed above for such a binder. 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, the main component of the binder preferably being polyvinyl alcohol and where e.g. B. at least 5 wt .-% EVA and / or PVAc can be used. The inventor has found an increased flexibility of the paper treated in this way in comparison with papers in which the binder is essentially polyvinyl alcohol. Similar effects can be achieved by adding, e.g. B. at least 5 wt .-%, vinyl acetate-ethylene (VAE) and / or vinyl ester ethylene can be achieved. Increased flexibility with reduced dust release is advantageous for further handling of the paper treated in this way, e.g. B. in printing equipment.

Preferably the binder in the first and second compositions is the same, or at least the main component of the binder is the same. As indicated above, the main ingredient is preferably polyvinyl alcohol.

As a pigment in the first and / or the second composition, any inorganic pigment, and most preferably a porous inorganic pigment, can actually be used. Mixtures of two or more pigments can also be used. The pigment used is preferably an inorganic pigment which can be selected from neutral, anionic and cationic pigment types. Useful pigments include e.g. B. silicon dioxide, talc, clay, hydrotalcite, kaolin, kieselguhr, calcium carbonate, magnesium carbonate, basic magnesium carbonate, aluminosilicate, aluminum trihydroxide, aluminum oxide (alumina), titanium oxide, zinc oxide, barium sulfate, calcium sulfate, zinc sulfide, gloss white, aluminum 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 silicon dioxides. Particularly preferred inorganic pigments are silica particles, colloidal silica, alumina particles and pseudo-boehmite because they form better porous structures. When used herein, the particles can be primary particles used as they are, or they can constitute secondary particles. A preferred type of alumina hydrate is crystalline boehmite or γ-AlOP (OH). Useful types of boehmite include DISPERAL HP14, DISPERAL 40, DISPAL 23N4-20, DISPAL 14N-25, and DISPERAL AL25 from Sasol; as well as MARTOXIN VPP2000-2 and GL-3 from Martinswerk GmbH. Useful cationic alumina types include α-Al2O3 types such as NORTON E700 available from Saint-Gobain Ceramics & Plastics, Inc, and γ-Al2O3 types such as ALUMINUM OXID C from Degussa. Other useful inorganic pigments include aluminum trihydroxides such as bayerite, or α-Al (OH) 3 such as PLURAL BT available from Sasol and gibbsite, or γ-Al (OH) 3 such as MARTINAL products and MARTIFIN products from Martinswerk GmbH, MICRAL products from JM Huber Company; HIGILITE products from Showa Denka KK As indicated above, the preferred type of inorganic pigment is silica, which can be used as such, in its anionic form or after cationic modification. The silica can be selected from various types, such as crystalline silica, amorphous silica, precipitated silica, fumed silica, silica gel, spherical and non-spherical silica. The silicon dioxide can 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 process particles and dry process particles (vapor phase process or pyrogenic particles). In the wet process, active silica is formed by acidolysis of silicates, and these are polymerized and flocculated to an appropriate degree to obtain hydrous silica. A vapor phase process includes two types; one includes high temperature vapor phase hydrolysis of silicon halide to obtain anhydrous silica (flame hydrolysis), and the other includes thermal reduction evaporation of silica sand and coke in an electric furnace, followed by oxidation in air to also obtain anhydrous silica (arc process). "Pyrogenic silicon dioxide" stands for silicon dioxide particles free of water of crystallization, which are obtained in the vapor phase process.

For the silica particles which are preferably used in the ink jet receiving layer of the invention, the fumed silica particles are particularly preferable. The fumed silica differs from the hydrous silica in the density of the surface silanol group and the presence or absence of pores therein, and the two different types of silica have different properties. The fumed silicon dioxide is suitable for forming a three-dimensional structure of high porosity. Since the fumed silica has a particularly large specific surface area, its ink absorption and retention are high.

Alternatively, organic pigments can be used in the optional ink jet receiving layer, which are preferably selected from the list consisting of: polystyrene, polymethyl methacrylate, silicones, melamine-formaldehyde condensation polymers, urea-formaldehyde condensation polymers, polyesters and polyamides. Mixtures of inorganic and organic pigments can be used. However, the pigment is preferably an inorganic pigment.

The pigments contained in the ink jet receiving layer preferably have an average particle size of 100 nm to 20 μm, with 1 to 12 μm, and more preferably 2 to 7 μm, being ideal. Pigments with a small particle size can easily be bound to the paper, while particles with a large particle size show large water absorption, which leads to a good print quality. The optimal average particle size is in the range between 1 and 12 µm, preferably 2 to 7 µm.

The pigments contained in the ink jet receiving layer preferably have an average surface area of 20 to 420 m ² / g, and preferably between 300 and 420 m ² / g, in order to obtain good absorption of the ink carrier.

The pigments contained in the ink jet receiving layer preferably have an average pore volume of 0.5 to 2 ml / g, preferably between 1 and 2 ml / g.

Pigments with an average particle size between 2 and 7 µm, an average surface area of 300 to 420 m2 / g and an average pore volume between 1 and 2 ml / g give an ideal combination of absorbency, print quality and binding, i. H. the absence of dust release from the treated paper.

Preferably, the inkjet receptive coating either in the first composition or in the second composition or in both the first and the second composition further comprises a crosslinking agent which is 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 release of dust from the paper thus printed. The availability of crosslinker in one of the compositions also increases the pot life of the relevant composition significantly. The first and / or the second composition preferably comprise crosslinking agents in an amount which makes up 0.1 to 10% of the total wet weight of the first and / or second composition.

The first and / or the second composition can further comprise additives which are not crosslinkers in a total amount which makes up 0.1 to 2% of the total wet weight of the first or second composition. Such additives can be one or more of a defoaming agent, a leveling agent, a wetting agent such as alkylphenol ethoxylates, thickeners such as hydroxylethyl cellulose or xanthan gum, pH adjusters such as NaOH, KOH, NH ₃ , HNO ₃ or H ₂ SO, cationic additives such as PolyDADMAC, preservatives and / or dispersants such as acrylates, polyphosphates or sodium aluminates.

APEO (alkylphenol ethoxylates) can be used for the leveling agent.

BIT or MIT (benzisothiazolinone or methylisothiazolinone) can be used as preservatives.

Polyether siloxane copolymer can be used as a defoaming agent.

Preferably, the paper obtained by the method of the invention is provided with thermosetting resin, such as melamine resin, preferably after it has been provided with a pattern printed by means of ink-jet printing. Out for this reason, the paper layer is preferably provided with an ink jet receptive coating only on one side thereof, namely the side which is provided to be printed on. The other, opposite side is preferably untreated, so that this opposite side shows the original porosity of the paper layer from which it was started. The resin can then be introduced into the paper core essentially from the underside. In order to enable sufficient impregnation of the paper with the inkjet receptive coating, the speed of the impregnation channel can be reduced, the resin can be provided with a lower viscosity, the impregnation can take place under pressure, and / or the resin can be heated, e.g. B. to between 45 and 85 ° C.

In general, it should be noted that although the paper obtained by the method of the invention is printable with an ink jet printer, it is not excluded that the paper will ultimately be printed using other techniques, such as rotogravure or offset printing. In addition, in such a case, the reduced dust release and the potentially better print quality are of interest. This is particularly the case when aqueous inks are used.

Preferably the first and / or the second composition is a liquid substance which is applied to the paper layer, and it is preferably used e.g. B. forcibly dried in a hot air oven or by means of infrared or near-infrared light or by means of microwave drying. Preferably, at least one such drying operation takes place between the sub-steps of the first aspect of the invention. Preferably the liquid substance is a water-based suspension of at least the binder and possibly the pigments. The first composition preferably has a dry matter content of 8 to 25 percent by weight of the liquid substance. The second composition preferably has a dry matter content of 4 to 20 percent by weight of the liquid substance. Preferably, the dry matter content, which is expressed by a percentage by weight, is higher in the first composition than in the second composition.

The application of the liquid substance of the first and / or second composition can take place in any desired manner, possibly by printing, e.g. B. inkjet printing, but preferably by means of coating techniques such as roller coating, spraying, metering rollers, bead coating, scattering, slot nozzle coating. With the latter techniques a coating is preferably obtained which covers at least 80% of the surface of the paper layer. Preferably, an excess of the liquid substance is first applied to the paper layer, and then the excess material is removed again, e.g. B. squeezed until the desired weight is obtained. In-line measurement systems may be desirable to guide the inkjet receptive coating and control its weight. Such a technique entails the risk that uncoated areas of the paper are preserved, which can lead to local errors in the printed pattern. Preferred equipment for applying the liquid substance is a coating device comprising counter-rotating metering rollers. Such rollers can produce a smooth coating surface.

The application of the liquid substance for the first and / or second composition can be carried out in an impregnation channel or, alternatively, on the printing equipment, immediately before the printing operation. The latter case solves all sorts of problems with limited shelf life of the ink jet receptive coating. The application of the liquid substance is preferably carried out while the paper is still in an "endless" form and is removed from the roll without cutting. Such techniques allow the inkjet receptive coating to be applied more evenly. In the case in which the coating takes place wholly or partially on the printing equipment, the printing equipment is preferably a roll-to-roll or a roll-to-web printer, comprising a coating device upstream of the print heads, for example a roll coater and / or additional print heads suitable for printing the liquid substance for the corresponding underlayer of the ink jet receiving coating. Such additional printheads, such as an additional row of printheads, may have larger diameter nozzles than those used to actually print the pattern. A resolution of 1 in 100, or even 1 in 25 dots per inch, may be sufficient for these nozzles. The larger diameter allows more viscous substances to be expelled. According to a special embodiment, the first layer is applied to the paper using rollers, while the second layer is applied using additional printheads. Such an embodiment is of particular interest when the pigment / binder ratio in the second composition is low, e.g. H. under 2: 1. In such a case, the liquid substance for the second layer can be applied more easily with the additional print heads.

The liquid substance for the first and / or second composition preferably has a viscosity of 10 to 75 seconds in the Din beaker 4 at 20 ° C. Such a property enables one direct application of the liquid substance to the surface of the paper layer. In experiments, a solids content of about 12% and a viscosity of about 24 seconds brought a sufficiently uniform coating on a previously untreated paper layer, e.g. B. applied by means of a roll coater.

• - den Schritt des Bereitstellens einer thermoplastischen Folie;
• - den Schritt des Beschichtens zumindest einer Seite der thermoplastischen Folie mit einer Tintenstrahlaufnahmebeschichtung, umfassend Pigment und Bindemittel;

mit der Charakteristik, dass die Tintenstrahlaufnahmebeschichtung in mindestens zwei Teilschritten aufgetragen wird, wobei entsprechend eine erste Schicht mit einer ersten Zusammensetzung und, nachfolgend, eine zweite Schicht mit einer zweiten Zusammensetzung aufgetragen werden, wobei beide Zusammensetzungen zumindest das Bindemittel umfassen. Im Allgemeinen können die gleichen ersten und zweiten Zusammensetzungen, wie oben in Verbindung mit der Behandlung von Papierschichten beschrieben, in diesem zweiten Aspekt der Erfindung verwendet werden. Das bevorzugte Bindemittel zur Verwendung auf solchen Folien ist polyurethanbasiert, acrylatbasiert oder polyvinylacetatbasiert. Ferner kann der Bindemittelgehalt in der ersten Zusammensetzung etwas verringert sein im Vergleich mit der Behandlung von Papierschichten, da weniger Absorption in den Kern der Schicht erwartet wird. Vorzugsweise ist das Pigment-Bindemittel-Verhältnis in der ersten Zusammensetzung in einem solchen Fall zwischen 1:1 und 6:1.According to a variant and an independent method according to the invention, instead of a paper layer, a thermoplastic film, such as a polyvinyl chloride (PVC) film, a polypropylene (PP) film, a polyethylene (PE) film, a polyethylene terephthalate is used (PET) film or a thermoplastic polyurethane (TPU) film is treated with an inkjet receptive coating using two coating sub-steps. Therefore, in accordance with a second independent aspect thereof, the present invention relates to a method of manufacturing an inkjet printer printable thermoplastic film for use as a decorative film in a laminated panel, the method comprising at least the following steps:

• the step of providing a thermoplastic film;
• the step of coating at least one side of the thermoplastic film with an ink jet receiving coating comprising pigment and binder;

having the characteristic that the ink jet receiving coating is applied in at least two sub-steps, a first layer having a first composition and, subsequently, a second layer having a second composition being applied accordingly, both compositions comprising at least the binder. In general, the same first and second compositions as described above in connection with treating paper layers can be used in this second aspect of the invention. The preferred binder for use on such films is polyurethane-based, acrylate-based or polyvinyl acetate-based. Furthermore, the binder content in the first composition can be somewhat reduced compared with the treatment of paper layers, since less absorption into the core of the layer is expected. In such a case, the pigment-binder ratio in the first composition is preferably between 1: 1 and 6: 1.

It is clear that the present invention also relates to paper layers and thermoplastic films obtained using the methods of the first and second aspects of the present invention, respectively.

With the same aim as in the first aspect, according to a third independent aspect, the invention also relates to a paper for inkjet printing, the paper being provided on at least one side with an inkjet receiving coating comprising at least pigment and binder with a characteristic that the proportion of free or unbound pigment is less than 10 percent by weight of the total amount of pigment in the ink jet receiving coating and / or that the surface of the ink jet receiving coating is essentially free of pigment. Such paper can, although not necessarily, be obtained using the method of the first aspect of the invention. It is clear that such a paper layer can further exhibit features that are identical to features inherent in paper layers obtained using the method of the first aspect.

With the same aim as in the first aspect, according to a fourth independent aspect, the invention also relates to a paper for ink jet printing, the paper being provided on at least one side with an ink jet receiving coating comprising at least pigment and binder with a characteristic that the ink jet receiving coating is essentially formed on its surface by the binder. Such paper can, although not necessarily, be obtained using the method of the first aspect of the invention. It is clear that such a paper layer can further exhibit features that are identical to features inherent in paper layers obtained using the method of the first aspect.

The invention also relates to thermoplastic films showing the characteristics of the third and / or the fourth aspect of the invention.

The invention further relates, according to its fifth aspect, to a method of manufacturing a laminate panel, the panel comprising at least a substrate material and a top layer provided thereon with a printed decoration, the top layer consisting essentially of thermosetting resin and one or more Paper layers is formed, wherein the paper layers comprise a decorative paper based on a paper for inkjet printing in accordance with the third and / or the fourth independent aspect and / or obtained by means of a method in accordance with the first independent aspect and / or the preferred embodiments of these aspects . In accordance with its sixth independent aspect, the invention also relates to a method for Production of a laminated panel, the panel comprising at least one substrate material and a top layer provided thereon with a printed decoration, the top layer being essentially formed from thermoplastic material comprising one or more thermoplastic films, the thermoplastic films having a decorative film Basis of a thermoplastic film for ink jet printing, obtained by means of a method in accordance with the second independent aspect and / or the preferred embodiments of this second aspect.

Preferably, in the fifth aspect, the paper for ink jet printing is printed by an ink jet printer, is impregnated with an amount of the thermosetting resin, and is attached to the substrate material by a hot press treatment. Preferably, in the sixth aspect, the thermoplastic sheet for ink jet printing is printed by an ink jet printer and is attached to the substrate material by a hot press treatment. Preferably, the inkjet printer operates on the basis of water-based inks, with, in particular, a single pass type inkjet printer and / or an inkjet printer operated in a single pass mode being preferred. Single pass printing operations exhibit valuable synergistic effects with the treated paper or thermoplastic films of the invention. The reduced release of dust from the treated layers minimizes the risk of clogging the nozzles in the inkjet printer. Clogged nozzles in single pass printing operations are particularly troublesome because they lead to defects in the printed pattern; H. so-called missing nozzles, the errors of which generally cannot be hidden or masked by subsequent printing operations, as is the case with multi-pass printers or plotters. Missing nozzles in equipment that is operated with a single pass can still be masked by creating redundancy in the printer, e.g. B. in which two or more printers, which are operated with a single pass, are placed one behind the other, which is extremely expensive. The present invention is therefore extremely valuable for operations that use single pass printing and results in a manufacturing process that is fluid and less prone to printing errors.

With the same aim as the previous aspects of the invention, the invention in accordance with its seventh aspect relates to equipment for manufacturing paper and / or thermoplastic films in accordance with any of the previous aspects or for use in a method in accordance with one of the previous aspects, with a characteristic that the equipment comprises at least two separate coaters for applying the ink jet receiving coating in separate sub-steps. Preferably the equipment further comprises an ink jet printer, preferably a single pass type ink jet printer or an ink jet printer capable of operating in a single pass mode.

As made clear in the fifth independent aspect of the invention, the paper layer with the ink jet receiving layer of the invention can be used in a method of making panels with a decorative surface, the panels comprising at least a substrate and a top layer comprising a thermosetting resin , wherein the top layer comprises a paper layer having a printed pattern, with a characteristic that pigment-containing inks are used to provide the part of the printed pattern, which are applied to the paper layer by means of a digital inkjet printer, and that the dry weight of the total volume of the pigment-containing inks, which are applied to the paper layer, is 9 grams per square meter or less, preferably 3 to 4 grams per square meter or less, a water-based or so-called aqueous ink being used for the pigment-containing ink. Limiting the dry weight of the ink applied results in a layer of ink that reduces the risk of press defects and cracks in the top layer. Indeed, possible interference between the ink layer and the thermosetting resin during the pressing operation is limited. Since the ink load is limited to a maximum of 9 grams per square meter, wrinkling or expansion of the paper due to the ink can be brought to an acceptable level, which ensures stable further processing. Organic pigments are preferably used for the pigment-containing ink. Organic pigments are known to be more stable when exposed to sunlight or other sources of UV radiation. The pigments of the pigment-containing ink preferably have an average particle size of less than 250 nanometers. Preferably the dry weight of the pigmented ink applied is 5 grams per square meter or less, for example 4 or 3 grams per square meter or less. Preferably, the printed pattern consists entirely, or at least substantially, of such pigmented ink, the printed pattern covering most, and preferably 80 percent or more, of the surface of the paper layer. Preferably the total volume of pigment-containing ink applied is less than 15 milliliters, or more preferably less than 10 milliliters or even less, e.g. B. 5 milliliters or less.

The paper layer of the invention is preferably opaque and / or contains titanium oxide as a whitening agent.

Preferably, the pattern printed on the paper layer of the invention covers most, and preferably 80 percent or more, of the surface of the paper layer.

Preferably, the paper layer, before or after printing and before or after the application of the ink jet receiving coating, is provided with an amount of thermosetting resin which corresponds to 40 to 250% dry weight of the resin compared to the weight of the paper. Experiments have shown that this area of applied resin provides sufficient impregnation of the paper, which prevents cracks to a great extent, and which stabilizes the dimension of the paper to a high degree.

The paper layer is preferably provided with such an amount of thermosetting resin that at least the paper core is saturated with the resin, before or after printing and before or after the application of the ink jet receiving coating. Such saturation can be achieved if an amount of resin is provided which is at least 1.5 or at least 2 times the weight of the paper. It should be understood that the resin provided on the paper layer is not necessarily only available in the core of the paper, but can form surface layers on both flat sides of the paper. The ink jet receptive coating can then be present on the surface of the paper with the intervening layer of such a surface layer of thermosetting resin. According to a special embodiment, the paper layer is first impregnated or saturated, and then, at least on the side to be printed thereof, resin is partially removed and possibly the ink jet receiving coating is provided.

Preferably, the resin provided on the paper has a relative humidity of less than 15% when printing, and more preferably 10% by weight or less.

Preferably, the step of providing the paper layer with thermosetting resin includes applying a mixture of water and the resin to the paper layer. Application of the mixture may include dipping the paper layer in a bath of the mixture and / or spraying, ejecting, or otherwise coating the paper with the mixture. Preferably the resin is provided in a metered manner, for example using one or more nip rollers and / or doctor blades to determine the amount of resin that is added to the paper layer.

Preferably, the thermosetting resin is a melamine-based resin, particularly a melamine-formaldehyde resin having a formaldehyde-melamine ratio of 1.4 to 2. Such a melamine-based resin is a resin that polycondenses while being exposed to heat in the pressing operation. The polycondensation reaction creates water as a by-product. In particular, these types of thermosetting resins, especially those in which water is by-produced, are of interest to the present invention. The water produced and all water residues in the thermosetting resin before pressing must largely leave the hardening resin layer before they are enclosed and lead to a loss of transparency in the hardened layer. The available ink layer can hinder the diffusion of vapor bubbles into the surface, but the invention provides measures to limit such a hindrance. The inkjet receptive coating is advantageous in this regard because it can provide an additional buffer to catch such escaping vapor. When using an ink jet receiving coating that is porous and / or hydrophilic, which is the case when e.g. If, for example, silicon dioxide and / or polyvinyl alcohol are used, some of the water vapor that is generated when the thermosetting resin of the paper layer hardens in the press can be absorbed by this coating, so that the process is less prone to the formation of pressing defects such as trapped water vapor bubbles . Other examples of such thermosetting resins which result in similar polycondensation include urea-formaldehyde-based resins and phenol-formaldehyde-based resins.

The paper layer is preferably not impregnated until after the inkjet receptive coating has been applied and after printing. In this way, the inkjet receptive coating is not affected at all by the water contained in the water-resin mixture applied for impregnation.

As can be seen from the foregoing, the method of the fifth aspect preferably comprises the step of hot-pressing the printed and resin-coated paper layer at least to cure the resin of the obtained resin-coated decorative paper. Preferably, the method of the invention forms part of a DPL process as described above, wherein the printed resinized paper layer of the invention is incorporated into the stack to be pressed as the decorative layer. It is of course not ruled out that the Invention would form part of a CPL (compact laminate) or an HPL (high pressure laminate) process, in which the decorative layer with at least several resin-impregnated core paper layers, e.g. B. of so-called Kraft paper, is hot-pressed, forming a substrate under the decorative layer, and wherein the pressed and cured laminate layer obtained, or the laminate panel, in the case of an HPL, on a further substrate such as a chipboard or an MDF - or HDF board is glued in place.

Preferably, after printing, another layer of resin is applied over the printed pattern, e.g. B. by means of an overlay, d. H. a resin-provided carrier layer or a liquid coating, preferably while the decorative layer is on the substrate, either loosely or already connected or glued to it.

The paper layer of the invention can be a colored, pigmented and / or colored base paper. The use of colored and / or colored paper enables further limiting of the dry weight of the applied ink in order to achieve a certain pattern or color. Preferably the dye or pigment is added to the pulp before the paper web is formed. According to an alternative, the ink-receiving layer on the paper layer to be printed is colored or pigmented with colored pigments. In accordance with the general disclosure, however, the pigments contained in the inkjet receptive coating are preferably colorless or white.

Preferably, a digital ink jet printer is used for printing the paper layer of the invention which enables ink droplets with a volume of less than 50 picoliters to be ejected. The inventors have found that working with droplets with a volume of 15 picoliters or less, for example 10 picoliters, has significant advantages in terms of limiting the dry weight of the inks applied. A digital inkjet printer is preferably used which makes it possible to work with ink droplets of different volumes in one and the same print or with so-called halftones or gray levels. The ability to print in halftones and grayscale further limits the dry weight of the ink applied while maintaining excellent print definition. A digital inkjet printer is preferably used which makes it possible to achieve a definition of at least 200 dpi, or even better of at least 300 dpi (dots per inch). Preferably the digital ink jet printer is of the single pass type wherein the paper layer is provided with the printed pattern in a single continuous relative movement of the paper layer with respect to the printer or printheads. It is not excluded that other digital inkjet printers may be used to practice the invention, such as so-called multi-pass printers or plotters. In the case of printers of the single pass type as well as in the case of printers of the multiple pass type, the printheads preferably extend over the entire width of the paper to be printed on. This is not the case with a plotter arrangement where the printheads must perform a scanning movement in the width direction of the paper layer. However, such printers are not excluded from being used in the method of the invention. It should be noted that multiple pass type printers have the advantage that failing nozzles can be hidden by the subsequent pass printing. In this type of printer, the nozzles can be shifted a little between the passages so that the paper dots are printed by several nozzles at a specific location. With multi-pass equipment, or even with a plotter, it is possible to perform automatic maintenance or cleaning between successive passes if necessary. The problem with failing nozzles is particularly relevant when water-based or so-called aqueous pigment-containing inks are used. In fact, nozzles can become clogged with the ink pigment as the water has dried off. The risks of failing nozzles are e.g. B. less with UV-curable ink. Additionally, the use of an inkjet receptive coating can increase the risk of nozzle failing. However, the double layer application of the ink jet receptive coating in accordance with the first aspect of the present invention improves autonomous production time due to reduced dust release.

It is clear that, according to the most preferred embodiment of the present invention, the paper layer is still flexible during printing and that the paper layer is only attached or placed on the plate-shaped substrate after printing. According to a variant, the paper layer is already attached to the plate-shaped substrate during printing or is placed loosely on it. The possible attachment to the substrate can be achieved by means of urea-based, phenol-based, melamine-based, polyurethane-based adhesives or similar adhesives. Such attachment can be achieved by means of a press treatment, whether it is a hot press treatment or not.

The method of the fifth aspect of the invention preferably further comprises the step of applying a counter-layer or leveling layer to the surface of the substrate opposite the printed paper layer. The counter layer or leveling layer preferably comprises a paper layer and a thermosetting resin, preferably the same resin as the top layer.

Mutual adhesion of the plate-shaped substrate, the possible counter layer and the possible transparent or translucent layer is preferably obtained in one and the same pressing treatment. According to the most preferred embodiment, the steps of the fifth aspect of the method are included in a DPL process.

According to the most important example of the invention, a standard printing paper, such as what is used for rotogravure printing, weighing between 60 and 90 grams per square meter in accordance with the first aspect of the invention is provided with an inkjet receptive coating and is using a digital inkjet printer with aqueous pigmented inks printed with a wood pattern. The printed paper layer is then provided with melamine resin by means of a standard impregnation channel; by means of roller, dipping, ejecting and / or spraying equipment. The resin-provided paper layer is then dried until a residual moisture of less than 10%, preferably about 7%, is reached. A stack of a resin-coated counter layer, a plate-shaped substrate, the printed resin-coated paper layer and a resin-coated paper layer forming a so-called overlay is formed. The stack is then pressed for less than 30 seconds at a temperature of about 180-210 ° C. and a pressure of more than 20 bar, for example 38 bar. During the pressing, the surface of the stack comes into contact with a structured pressing element, such as a structured pressing plate, and a relief is formed in the upper layer of the resulting laminate panel. Possibly the relief obtained can be precisely formed with the printed pattern of the resin-coated paper layer.

It is also clear that the paper obtained in the first aspect of the invention is suitable for use as decorative paper in a method for producing floor panels, furniture panels, ceiling panels and / or wall panels.

It will be understood that the printed pattern, plate-shaped substrates and paper layers mentioned above may have to be split during the methods of the invention to obtain their respective final dimensions. The panels obtained by means of a DPL pressing treatment or the like are preferably sawn or otherwise divided. Other treatments of the panels obtained are of course not excluded.

• 1 schematisch eine Ausführungsform einer Papierschicht zeigt, die mit einer Tintenstrahlaufnahmebeschichtung versehen wurde, in Übereinstimmung mit dem Verfahren des ersten Aspekts der Erfindung;
• 2 und 3 in einem größeren Maßstab eine Ansicht des in 1 dargestellten Bereichs F3 bereitstellen, wobei, im Fall von 2, nur die erste Schicht auf die Papierschicht aufgetragen wurde;
• 4 einige Schritte in einem Verfahren in Übereinstimmung mit dem fünften Aspekt der Erfindung zeigt;
• 5 perspektivisch eine mittels des Verfahrens aus 4 erhaltenes Paneel zeigt;
• 6 eine Ansicht gemäß der auf 5 angezeigten Linie VI-VI zeigt;
• 7 ein Stück Ausrüstung zur Verwendung unter anderen im ersten Aspekt der Erfindung zeigt; und
• 8 schematisch eine Draufsicht auf einen im Einmaldurchgangsmodus betriebenen Drucker zeigt.

With the intention of better showing the characteristics according to the invention, in the following, as an example without limiting character, an embodiment is described with reference to the accompanying drawings, in which:

• 1 shows schematically an embodiment of a paper layer provided with an ink jet receptive coating in accordance with the method of the first aspect of the invention;
• 2 and 3rd on a larger scale a view of the in 1 area shown F3 provide, where, in the case of 2 , only the first layer was applied to the paper layer;
• 4th Figure 8 shows some steps in a method in accordance with the fifth aspect of the invention;
• 5 perspective one by means of the method 4th shows preserved panel;
• 6th a view according to the 5 indicated line VI-VI shows;
• 7th Figure 12 shows a piece of equipment for use among others in the first aspect of the invention; and
• 8th Figure 3 shows schematically a top view of a printer operated in single pass mode.

1 represents schematically a treated paper layer 1 represents, which is printable with an inkjet printer. The printable paper layer 1 includes a paper web 2 that have an inkjet receptive coating 3rd is provided which is a first layer 4th having a first composition and a second layer 5 with a second composition. The paper web 2 is, in this case, a base printing paper weighing about 70 grams per square meter and having an average drag as expressed by a Gurley value of less than 30 seconds.

It should generally be noted that the dimensions of the paper web shown 2 and the layers 4-5 , in the figures, are not drawn to scale in order to better illustrate the invention.

2 and 3rd show that the inkjet receptive coating 3rd Pigments 6th and binder 7th includes. The composition of the first layer 4th and the composition of the second layer 5 comprise both binders in accordance with the first aspect of the invention.

2 represents a semi-finished product 8th dar, with only the first layer 4th onto the paper web 2 was applied. The binder 7th becomes partially, and thus in a non-uniform manner, into the paper web 2 absorbed. On the surface 9 are loose and / or poorly bound pigments 6th available. Such pigments 6th lead to further processing of such a semi-finished product 8th to dust release. The surface obtained 9 the first layer 4th also suffers from unevenness.

3rd shows the paper layer 1 , also taking the second layer 5 on top of the first layer 4th was applied. 3rd shows that the second layer 5 the surface 9 evens out, resulting in a more even surface 10 the second layer and the paper layer 1 leads. The composition of the second layer 5 in this case has a lower pigment-to-binder ratio than the composition of the first layer 4th .

It should be noted that 3rd is an example of the third and fourth aspects of the present invention wherein the surface of the treated paper layer is less than 10 percent by weight of the total pigment 6th unbound or free and being the surface 10 the second layer essentially, and in this case completely, by binding agents 7th is formed.

4th provides a process for the production of laminate panels 11 of the in 5 and 6th The method forms a representation of the fifth independent aspect of the invention as described in the introduction of the present patent application. The received decorative panels 11 comprise at least one substrate 12th and an upper layer 13th . The top layer 13th includes a paper layer 1 made in accordance with the first aspect and provided with a printed pattern or a digitally printed ink layer 14th representing a wood pattern, as is the case here. The method of the exemplary embodiment comprises at least the step S1 of adding the paper layer 1 with the ink jet receiving layer and the printed pattern with thermosetting resin 15th . This is done using the paper layer 1 of a role 16 and taken to a first impregnation station 17th transported where the paper layer in a bath 18th made of resin 15th , even more specifically from a mixture of water and resin 15th is immersed. The paper layer 1 is then left to rest, in which case it is transported upwards. Letting it rest enables the resin 15th to penetrate the paper core. The paper layer 1 then comes to a second impregnation station 19th where the paper layer 1 , in this case, again in a bath 18th made of resin 15th , even more specifically from a mixture of water and resin 15th is immersed. A set of nip rollers 20th allows the amount of resin 15th to dose that on the paper layer 1 is applied.

In the example there are several squeegees 21 for partially removing resin on the surface of the resin-coated paper layer 1 available.

In a second step S2 becomes the resin coated paper layer 1 dried, and their residual moisture is brought to below 10%. In the example, convection ovens 22nd is used, but other heating equipment, such as microwave drying equipment, may alternatively be used.

4th also represents the continuous paper layer 2 in arcs 23 is cut and stacked.

4th also shows that in a subsequent step S3 the arches preserved 23 or the paper layer 1 be picked up in a stack in a short platen press 24 between upper and lower press plates 25-26 is to be pressed. The stack comprises, from bottom to top, a counter-layer 27 , a plate-shaped substrate 12th , the above-mentioned paper layer 1 and a protective layer 28 , being the opposite layer 27 and the protective layer 28 both a paper web 2 and a resin 15th include. The stack is then pressed, and the pressing treatment results in mutual bonding between the constituent layers 1-12-27-28 , comprising the substrate 12th , the stack, as well as hardening or hardening of the available resin 15th . A polycondensation reaction of the melamine-formaldehyde resin takes place here even more specifically 15th , with water as a by-product.

The upper press plate 26th is a textured press plate that, during the same press treatment of step S3 , a relief in the melamine surface of the panel 1 provides by the textured surface 29 the upper press plate 26th in contact with the melamine of the protective layer 28 is brought.

5 and 6th represent that the decorative panel or laminate panel obtained 11 may be in the shape of a rectangle or an elongated laminate flooring panel with a pair of long sides 30th and a pair of short pages 31 and an HDF or MDF substrate 12th having. In this case the panel is 11 at least along the long sides 30th with coupling agents 32 provided that allow the relevant pages 30th together with the sides of a similar panel both in one direction R1 perpendicular to the plane of the coupled panels, as well as in one direction R2 lock perpendicular to the mated sides and in the plane of the mated panels. As in 6th shown, such coupling means or coupling parts can basically be in the form of a spring 33 and a groove 34 have that with additional cooperating locking means 35 are provided that the locking in the direction R2 enable.

7th shows that, in accordance with a preferred embodiment, at least one of the first layer 4th and the second layer 5 the inkjet receptive coating 3rd , by coating, in one of the two sub-steps, a liquid substance 36 onto the paper web 2 can be obtained. In this case the application of the first layer is shown. One device 37 , comprising counter-rotating metering rollers 38 , is applied. Such a device 37 may initially be an excess of liquid substance 36 apply that by means of the rollers 38 is squeezed to the desired weight, which can also provide a smooth coating surface. The semi-product obtained is preferably 8th then dried, e.g. B. by means of a hot air oven in order to achieve a residual moisture of preferably below 10%, or of about 7%. The treated paper obtained is then further treated by applying the second layer 5 the inkjet receptive coating 3rd . Such is not shown here, but it can be done in a fairly similar manner.

8th that represents the paper layer 1 with the inkjet receptive coating of the first aspect of the invention by means of an inkjet printer 39 can be printed, which, in this example, several rows 40 comprised of printheads that extend over the surface of the paper layer to be printed 1 extends. The printer 39 refers, in this example, to a single pass type printer wherein the provision of the printed pattern is relative movement of the inkjet printer 39 , even more special of the series 40 , and the paper layer 1 includes in a printing direction D during printing. In this case the ranks are standing 40 and the printheads still while the paper layer is moving 1 while the inks are being ejected onto the paper layer 1 , more specifically to the ink jet receptive coating applied to the paper web 3rd emotional. The paper layer 1 becomes during a single continuous movement of the paper layer 1 relative to the printer 39 or the ranks 40 printed by printheads. The printed pattern obtained 14th includes, in the example, a wood motif with wood nerves 41 which generally extend in the printing direction D. Preferably there is a drying station 42 the printer 39 provided downstream. After the inks have dried, the printed paper layer is preferably rolled up and placed in the in 4th presented method as the role 16 used.

The present invention is in no way limited to the embodiments described above, but such methods, equipment, paper layers and thermoplastic films can be implemented in several variants without departing from the scope of the invention.

The invention is further disclosed by the following list of paragraphs as defined by the items numbered below.

1. - A composition for use in a process for the production of paper printable with an inkjet printer, the paper being intended for use as a decorative paper in a laminate panel, at least one side of the paper layer being coated with an inkjet recording coating in at least two sub-steps, wherein correspondingly a first layer with the composition and subsequently a second layer with a second composition is applied, both compositions comprising at least one binder, characterized in that the composition is a liquid substance which is a water-based suspension of at least one binder and preferably pigments , wherein the dry matter content of the first composition 8th to 25th Weight percent of the liquid substance is.

2.- Composition according to point 1 , characterized in that the dry matter content of the second composition 4th to 20th Weight percent of the liquid substance is.

3.- A composition for use in a process for the production of paper printable with an inkjet printer, the paper being intended for use as a decorative paper in a laminate panel, at least one side of the paper layer being coated with an inkjet receptive coating in at least two sub-steps, wherein correspondingly a first layer with a first composition and subsequently a second layer with the composition are applied, both compositions comprising at least one binder, characterized in that the composition is a liquid substance which is a water-based suspension of at least one binder and preferably pigments , wherein the dry matter content of the second composition 4th to 20th Weight percent of the liquid substance is.

4.- Composition according to point 3rd , characterized in that the dry matter content of the first composition 8th to 25th Weight percent of the liquid substance is.

5. Composition according to any one of the preceding points, characterized in that the dry matter content, expressed as a percentage by weight, is higher in the first composition than in the second composition.

• - die Eigenschaft, dass sowohl die erste Zusammensetzung als auch die zweite Zusammensetzung Pigment und Bindemittel umfassen, allerdings mit einem unterschiedlichen Pigment-Bindemittel-Verhältnis;
• - die Eigenschaft, dass sowohl die erste Zusammensetzung als auch die zweite Zusammensetzung Pigment und Bindemittel umfassen, wobei die durchschnittliche Partikelgröße der in der ersten Zusammensetzung enthaltenen Pigmente größer als die in der zweiten Zusammensetzung enthaltene durchschnittliche Partikelgröße ist.

6.- Composition according to one of the preceding points, characterized in that the first layer and the second layer differ in that they exhibit one or more of the following properties:

• the property that both the first composition and the second composition comprise pigment and binder, but with a different pigment-binder ratio;
• the property that both the first composition and the second composition comprise pigment and binder, the average particle size of the pigments contained in the first composition being greater than the average particle size contained in the second composition.

7.- Composition according to point 6th , characterized in that the first composition has a pigment to binder ratio that is greater than the pigment to binder ratio of the second composition.

8.- Composition according to point 6th or 7th , characterized in that the pigment to binder ratio in the second composition is lower than 2 is and preferably between 1 and 2 lies.

9.- Composition according to point 7th or 8th , characterized in that the pigment-binder ratio in the first composition is greater than 3.5 and preferably greater than 5.

10.- Composition according to one of the points 7th to 9 , characterized in that the first composition has a pigment to binder ratio which is at least 20% greater than the pigment to binder ratio of the second composition.

11.- Composition according to one of the points 6th to 10 , characterized in that the larger pigment particles are contained in the first composition.

12.- Composition according to point 11 , characterized in that the pigment particles in the first composition have an average particle size between 1 and 20 microns.

13.- Composition according to point 11 or 12th , characterized in that the pigment particles in the second composition have an average particle size between 100 nanometers and 1 Have micrometers.

14. Composition according to one of the preceding points, characterized in that the binder in the first and second compositions is the same, or that at least the main component of the binder is the same.

15. Composition according to one of the preceding points, characterized in that an inorganic pigment and most preferably a porous inorganic pigment is used as a pigment in the first and / or second composition.

16. Composition according to one of the preceding points, characterized in that silicon dioxide particles are used for the pigment and / or that polyvinyl alcohol is used for the binder.

17. Composition according to one of the preceding points, characterized in that the pigment comprises amorphous and / or precipitated silicon dioxide.

18.- Composition according to one of the preceding points, characterized in that the pigments have an average particle size of 100 nm to 20 µm, with 1-12 µm, and even better 2 to 7 µm, being ideal.

19.- Composition according to any one of the preceding points, characterized in that the pigments have an average surface area of between 20 and 420 m ² / g and preferably between 300 and 420 m 2 / g.

20. Composition according to one of the preceding points, characterized in that the pigments have an average pore volume of 0.5 to 2 ml / g, preferably between 1 and 2 ml / g.

21. Composition according to one of the preceding points, characterized in that the pigments have an average particle size between 2 and 7 µm, an average surface area of 300 to 420 m2 / g and an average pore volume between 1 and 2 ml / g.

22. Composition according to one of the preceding points, characterized in that the first composition and / or the second composition comprise a crosslinker.

23.- Composition according to point 22nd , characterized in that the crosslinker is selected from the list consisting of: aldehydes, aziridines, isocyanates, epoxides and borates.

24.- Composition according to point 22nd or 23 , characterized in that the crosslinkers are present in an amount which makes up 0.1 to 10% of the total wet weight of the first and / or second composition.

25.- Composition according to one of the points 22nd to 24 , characterized in that it comprises additives which are not crosslinkers in an amount which makes up 0.1 to 2% of the total wet weight of the first or second composition.

26.- Composition according to point 25th , characterized in that the additive has one or more of a defoaming agent, a leveling agent, a wetting agent such as alkylphenol ethoxylates, thickeners such as hydroxylethyl cellulose or xanthan gum, pH adjusters such as NaOH, KOH, NH3, HNO3 or H2 SO, cationic Additives such as PolyDADMAC,

Preservatives and / or dispersants such as acrylates, polyphosphates or sodium aluminates.

27.- Composition according to one of the preceding points, characterized in that the binder contained in the first and / or second composition is formed by a mixture of polyvinyl alcohol with ethylene vinyl acetate (EVA) and / or polyvinyl acetate (PVAc), preferably the main component of the Binder is polyvinyl alcohol and, e.g. B., at least 5 wt .-% EVA and / or PVAc can be used.

28.- Composition according to one of points 1 to 26, characterized in that the binder contained in the first and / or second composition is formed by a mixture of polyvinyl alcohol with vinyl acetate ethylene (VAE) and / or vinyl ester ethylene, preferably the main component of the Binder is polyvinyl alcohol and, e.g. B., at least 5 wt .-% vinyl acetate ethylene (VAE) and / or vinyl ester ethylene can be used.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 1290290 [0003, 0005]
• DE 19725829 C1 [0006]
• EP 1872959 [0007]
• WO 2011/124503 [0007]
• EP 1857511 [0007]
• EP 2431190 [0007]
• EP 2293946 [0007]
• WO 2015/118451 [0007, 0010, 0012]
• EP 2132041 [0008]
• EP 1044822 [0009]
• EP 1749676 [0009]
• EP 2274485 [0009]

Claims (15)

Composition for use in a process for the production of paper (1) printable with an inkjet printer, the paper being intended for use as a decorative paper in a laminate panel, at least one side of the paper layer (1) being coated with an inkjet receptive coating (3 ) is coated, a first layer (4) with the composition and subsequently a second layer (5) with a second composition being applied, both compositions comprising at least one binder (7), characterized in that the composition is a liquid substance which is a water-based suspension of at least one binder (7) and preferably pigments (6), the dry matter content of the first composition being 8 to 25 percent by weight of the liquid substance. Composition according to Claim 1 , characterized in that the dry matter content of the second composition is 4 to 20 percent by weight of the liquid substance. Composition for use in a process for the production of paper (1) printable with an inkjet printer, the paper being intended for use as a decorative paper in a laminate panel, at least one side of the paper layer (1) being coated with an inkjet receptive coating (3 ) is coated, a first layer (4) with the composition and subsequently a second layer (5) with a second composition being applied accordingly, both compositions comprising at least one binder (7), characterized in that the composition is a liquid substance which is a water-based suspension of at least one binder (7) and preferably pigments (6), the dry matter content of the second composition being 4 to 20 percent by weight of the liquid substance. Composition according to Claim 3 , characterized in that the dry matter content of the first composition is 8 to 25 percent by weight of the liquid substance. Composition according to any one of the preceding claims, characterized in that the dry matter content, expressed as a percentage by weight, is higher in the first composition than in the second composition. Composition according to any one of the preceding claims, characterized in that the first layer and the second layer differ in that they exhibit one or more of the following properties: the property that both the first composition and the second composition contain pigment (6) and binders (7), but with a different pigment-to-binder ratio; - The property that both the first composition and the second composition comprise pigment (6) and binder (7), the average particle size of the pigments (6) contained in the first composition being greater than the average particle size contained in the second composition . Composition according to Claim 6 , characterized in that the first composition has a pigment (6) -binder (7) ratio which is greater than the pigment-binder ratio of the second composition. Composition according to Claim 6 or 7th , characterized in that the pigment-binder ratio in the second composition is less than 2 and is preferably between 1 and 2. Composition according to Claim 7 or 8th , characterized in that the pigment-binder ratio in the first composition is greater than 3.5 and preferably greater than 5. Composition according to one of the Claims 7 to 9 , characterized in that the first composition has a pigment to binder ratio which is at least 20% greater than the pigment to binder ratio of the second composition. - Composition according to one of the Claims 6 to 10 , characterized in that the larger pigment particles (6) are contained in the first composition. Composition according to Claim 11 , characterized in that the pigment particles (6) in the first composition have an average particle size between 1 and 20 micrometers. Composition according to Claim 11 or 12th , characterized in that the pigment particles (6) in the second composition have an average particle size between 100 nanometers and 1 micrometer. Composition according to any one of the preceding claims, characterized in that the binder (7) in the first and the second composition is the same, or that at least the main component of the binder (7) is the same. Composition according to one of the preceding claims, characterized in that silicon dioxide particles are used for the pigment (6) of the ink jet receiving coating and / or that polyvinyl alcohol is used for the binder (7).

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