BR112019006637B1 - MANUFACTURE OF DECORATIVE SURFACES - Google Patents

Abstract

A method for manufacturing decorative surfaces is disclosed which includes, in order, the steps of: a) inkjet printing inkjet printing (19) an image on a first thermoplastic tinsel (12) by means of sandblasting and curing by UV one or more free radical UV curable inkjet inks pigmented on the first thermoplastic tinsel (12); b) applying to the inkjet printed image a second thermoplastic tinsel (12) carrying a layer containing a vinyl chloride-vinyl acetate-vinyl alcohol copolymer with the layer facing the inkjet printed image on the first thermoplastic tinsel; and c) hot pressing (20) the first and second thermoplastic tinsel into a decorative laminate; wherein at least one of the first and second thermoplastic tinsel is comprised of a transparent thermoplastic tinsel; and wherein the one or more pigmented free-radical UV-curable inkjet inks contains a polymerizable composition that is endowed with: 30 to 90% by weight of one or more compounds having a group ethylenically unsaturated polymerizable; 10 to 70%, by weight, of one or more compounds with two ethylenically unsaturated polymerizable groups; and 0 to 10%, in (...).

Description

TECHNICAL FIELD

[001] The present invention relates to the manufacture of decorative surfaces, preferably decorative panels or tiles, using inkjet technology. The invention relates in particular to decorative PVC (polyvinyl chloride) panels, also called vinyl tiles or vinyl strips. Often the abbreviation LVT is also used for these tiles, which stands for Luxurious Vinyl Tile. PREVIOUS TECHNIQUE

[002] Rotogravure, offset and flexography are increasingly being replaced for different applications by industrial inkjet printing systems, due to flexibility of use, such as variable data printing, short production run and customized products at low cost, and improved reliability. allowing inclusion in production lines.

[003] Document EP 2865527 A (AGFA GRAPHICS) discloses a method for manufacturing a decorative surface that includes the steps of: a) impregnating a paper substrate with a thermosetting resin; b) blasting a colored pattern with one or more aqueous inkjet inks that include a polymeric latex binder onto paper impregnated with thermosetting resin; c) drying the one or more aqueous inkjet inks; and d) hot pressing the thermosetting paper carrying the colored pattern onto a decorative surface.

[004] A major disadvantage of these wood and paper-based decorative panels is their limited water resistance, which prevents their use in bathrooms and kitchens.

[005] One approach is to use a water-resistant decorative surface, for example, applying a roll of PVC coating wall to wall. However, as room walls and entrances are often fitted with numerous corners and notches, applying such a large floor roll requires experienced workers and removal of all furniture from the room or room.

[006] Another approach is to resolve the issue of water resistance by replacing layers of wood and paper in decorative panels with water-resistant polymeric layers. Such polymer-based floor panels employing polymers such as polyvinyl chloride are disclosed, for example, in document WO 2011/077311 A (FLOORING INDUSTRIES). These polymeric floor panels feature interlocking structures that interlock with similar panels with similar interlocking structures, allowing for easy do-it-yourself assembly of a glueless floor surface covering. The decorative layer on such floor panels is carried out by rotogravure printing using water-based or solvent-based inks having a relatively high viscosity on a thermoplastic tinsel made of PVC.

[007] Inkjet inks in general have a relatively low viscosity, which causes problems with image quality, for example, “running”, when printing with solvent-based or water-based inkjet inks. water-based in a thermoplastic tinsel made of PVC.

[008] The unpublished patent application PCT/EP2016/060507 (AGFA & UNILIN) discloses a method for manufacturing decorative surfaces that includes the steps of: a) inkjet printing (19) an image on a first thermoplastic tinsel ( 12) using a UV-curable pigmented inkjet ink; b) applying a second thermoplastic tinsel (12) to the inkjet printed image; and c) hot pressing (20) the first and second thermoplastic tinsels into a decorative laminate; wherein the UV-curable pigmented inkjet ink contains a polymerizable composition comprising 30 to 70% by weight of monofunctional polymerizable compounds and 30 to 70% by weight of polyfunctional polymerizable compounds, wherein the weight percentage is based on the total weight of the polymerizable composition; and wherein at least one of the first and second thermoplastic tinsels is comprised of a transparent tinsel. The decorative panels of the invention exhibit good adhesion and are free from cracks. However, sometimes greater flexibility is still required for highly curved surfaces, for example around columns or pillars.

[009] Therefore, there is still a need to provide improved decorative surface manufacturing methods using inkjet technology.

SUMMARY OF THE INVENTION

[0010] In order to overcome the aforementioned problems, preferred embodiments of the present invention were carried out with a method for manufacturing decorative surfaces as defined by claim 1.

[0011] The use of specific pigmented UV-curable inkjet inks in combination with a specific copolymer of vinyl chloride and vinyl acetate, allowed the obtaining of decorative panels with excellent image quality, adhesion, high flexibility and no cracks on the printout during recording.

[0012] The manufacturing process was made much simpler, allowing it to be completely carried out at the decorative panel manufacturer's facilities.

[0013] An advantage for the manufacturer of decorative panels lies in the fact that the large stock of non-digitally printed decorative rolls could be eliminated, since the inclusion of UV products in the inkjet at the right time was realized in the process of manufacturing. Another advantage arising from this was that it became possible to react much faster to market trends and that the waste of decorative rolls was eliminated, as they did not need to be ordered from a decoration printer with a minimum purchase quantity and in advance.

[0014] In-house printing allows for a wide variety of personalized products and articles, for example decorative panels, including the company logo, and this without substantial financial costs.

[0015] Another advantage of inkjet printing is that the manufacturing process can be controlled to such a degree that, for example, a raised wood grain is in perfect alignment with the inkjet printed wood color pattern .

[0016] Other advantages and embodiments of the present invention will be evident from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 shows the prior art production process for manufacturing polymeric decorative panels, in which a PVC roll manufacturer (11) supplies a PVC roll (12) under a decoration printer (13) using color printing. engraving (14) to deliver a roll of decorative PVC (15) to a warehouse (16) of a floor panel manufacturer (18). The PVC roll manufacturer (11) also supplies PVC rolls (12) to a warehouse (17) of the flooring panel manufacturer (18), which makes a set of layers from the PVC roll (12), the Decorative PVC (15) and a base layer (21) which after hot pressing (20) in a single unit is cut into decorative panels (22) which are collected in a set of decorative panels (23) ready for sale .

[0018] Figure 2 shows a production process for manufacturing decorative polymeric panels, in which a PVC roll manufacturer (11) supplies PVC rolls (12) to a warehouse (15) of a floor panel manufacturer (18 ), which prepares a decorative PVC roll (15) from a PVC sheet. (12). The floor panel manufacturer (18) then produces a set of layers from the PVC roll (12), the decorative PVC roll (15) and a base layer (21) which after heat compression (20) decorative panels (22) are cut into a single unit, which are then collected into a set of decorative panels (23) ready for sale.

[0019] Figure 3 shows a cross-section of a decorative panel (22) that includes a base layer (35) with a tongue (31) and groove (32) laminated on the top side by a transparent or opaque thermoplastic tinsel (34 ) and a transparent thermoplastic tinsel (33). DETAILED DESCRIPTION Settings

[0020] The term “alkyl” means all possible variants for each number of carbon atoms in the alkyl group that is, methyl, ethyl, for three carbon atoms: n-propyl and isopropyl; for four carbon atoms: n-butyl, isobutyl and tertiary butyl; for five carbon atoms: n-pentyl, 1,1-dimethyl-propyl, 2,2-dimethylpropyl and 2-methyl-butyl, and so on.

[0021] Unless otherwise specified, a substituted or unsubstituted alkyl group is preferably comprised of a C1 to C6- alkyl group.

[0022] Unless otherwise specified, a substituted or unsubstituted alkluenyl group is preferably comprised of a C2 to C6-alkenyl.

[0023] Unless otherwise specified, a substituted or unsubstituted alkynyl group is preferably comprised of a C2 to C6-alkynyl group,

[0024] Unless otherwise specified, a substituted or unsubstituted aralkyl group is preferably comprised of a phenyl or naphthyl group that includes one, two, three or more C1 to C6-alkyl groups.

[0025] Unless otherwise specified, a substituted or unsubstituted alkaryl group is preferably comprised of a C7 to C20-alkyl group that includes a phenyl group or naphthyl group.

[0026] Unless otherwise specified, a substituted or unsubstituted aryl group is preferably comprised of a phenyl group or naphthyl group.

[0027] Unless otherwise specified, a substituted or unsubstituted heteroaryl group is preferably comprised of a five- or six-element ring substituted by one, two or three oxygen atoms, nitrogen atoms, sulfur atoms, of selenium or its combinations.

[0028] The term “substituted”, in, for example, substituted alkyl group means that the alkyl group can be replaced by atoms other than the atoms normally present in that group, that is, carbon and hydrogen. For example, a substituted alkyl group may include a halogen atom or a thiol group. An unsubstituted alkyl group contains only carbon and hydrogen atoms.

[0029] Unless otherwise specified a substituted alkyl group, a substituted alkenyl group, a substituted alkynyl group, a substituted aralkyl group, a substituted alkaryl group, a substituted aryl group and a substituted heteroaryl group, preferably , is substituted by one or more constituents selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butio, isobutyl and tertiary-butyl, ester, amide, ether, thioether, ketone, aldehyde, sulfoxide, sulfone, sulfonate ester, sulfonamide, -Cl, -Br, -I, -OH, -SH, -CN and -NO2.

MANUFACTURING METHODS OF DECORATIVE SURFACES

[0030] A method for manufacturing decorative surfaces includes, in order, the steps of: a) inkjet printing (19) an image on a first thermoplastic tinsel (12) by means of jetting and UV curing one or more pigmented, free-radical, UV-curable inkjet inks in the first thermoplastic tinsel (12); b) apply to the inkjet printed image a second thermoplastic tinsel (12) carrying a layer containing a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol with the layer facing the inkjet printed image on the first thermoplastic tinsel; and c) hot pressing (20) the first and second thermoplastic tinsels into a decorative laminate; wherein at least one of the first and second thermoplastic tinsels is comprised of a transparent thermoplastic tinsel; and wherein the one or more pigmented free radical UV-curable inkjet inks contain a polymerizable composition that is provided with: 30 to 90%, by weight, of one or more compounds with an ethylenically unsaturated polymerizable group; 10 to 70%, by weight, of one or more compounds with two ethylenically unsaturated polymerizable groups; and from 0 to 10%, by weight, of one or more compounds with three or more ethylenically unsaturated polymerizable groups, wherein all percentages, by weight, are based on the total weight of the polymerizable composition.

[0031] According to a more preferred embodiment, the aforementioned method includes a step d) of cutting the laminate in the form of a decorative panel (22). The method of the invention can also be used to manufacture wide-line decorative surfaces (e.g. vinyl rolls), but is preferably used to manufacture decorative panels, since these do not require experienced workers for their application and removal from all furniture. of a room or room.

[0032] The tinsel is thermoplastic so that it can be melted during hot pressing (20). Hot pressing is preferably carried out by preheating the first and second thermoplastic tinsel, preferably at a temperature above 130°C, more preferably between 140 and 170°C, and preferably then using a cooled press for casting. them into a decorative laminate. Alternatively, the press containing the first and second thermoplastic tinsels may be heated to a temperature above 130°C, followed by cooling the press to fuse the first and second thermoplastic tinsels into the form of a decorative laminate. The pressure used in both methods is preferably greater than 10 bar, more preferably between 15 and 40 bar.

[0033] Thermoplastic tinsels are preferably selected from the groups consisting of polyvinyl chloride (PVC), polyolefins such as polyethylene (PE) and polypropylene (PP), polyamides (PA), polyurethane-urethane (PU), polystyrene -silicon (PS), acrylonitrile -butadiene-styrene (ABS), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyether ketone (PEEK) or mixtures or copolymers thereof.

[0034] According to a preferred embodiment, the first and second thermoplastic tinsels are comprised of polyvinyl chloride tinsels. Polyvinyl chloride tinsels are preferably of the rigid type which includes less than 10% by weight of plasticizer, more preferably these PVC tinsels contain from 0 to 5% by weight of plasticizer. The plasticizer may be a phthalate plasticizer, but is preferably a non-phthalate plasticizer for health reasons.

[0035] Preferred non-phthalate plasticizers include diisononyl-cyclohexane-1,2-dicarboxylate (DINCH), dipropylene glycol dibenzoate (DGD), diethylene glycol dibenzoate (DEGD), triethylene glycol dibenzoate (TEGD) , acetylated mono glycerides of fully hydrogenated castor oil isosorbide (COMGHA) esters, bis-(2-ethylhexyl terephthalate), vegetable oil-based plasticizers such as EcolibriumTM from DOW, and mixtures thereof.

[0036] According to a preferred embodiment, the pigmented UV-curable inkjet ink is cured using UV LEDs. DECORATIVE SURFACES

[0037] In the present case below, the invention will be disclosed for decorative panels, but, with the exception of tongue and groove profiles, the invention is equally applicable to a wide-edge decorative surface, such as a vinyl roll.

[0038] A decorative panel (22) obtained by means of the method according to the present invention includes an inkjet printed image between two thermoplastic products, wherein at least one of the two thermoplastic tinsels is comprised of a transparent sheet. A transparent sheet is necessary to make the inkjet printed image visible, as it is located inside the decorative laminate.

[0039] According to a preferred embodiment, the decorative panel (22) includes an inkjet printed image on a first thermoplastic tinsel (34), which is preferably an opaque thermoplastic tinsel, while the second thermoplastic tinsel (33) It is transparent and carries a layer that contains a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol.

[0040] According to an alternative embodiment, the decorative panel (22) includes an inkjet printed image on a first transparent thermoplastic tinsel (33), while the second thermoplastic tinsel (34) is preferably opaque and bears a layer containing a vinyl chloride, vinyl acetate, vinyl alcohol copolymer.

[0041] The advantage of having an opaque thermoplastic tinsel is that the color vibrancy of the inkjet printed image is enhanced and that any defects and irregularities in the optional base layer are concealed and therefore cannot influence the quality of the image. The opaque thermoplastic tinsel is preferably an opaque white opaque, but it can also be an opaque to be yellowish or brownish to reduce ink consumption during inkjet printing.

[0042] According to a more preferred embodiment, the decorative panel (22) includes a tongue (31) and a groove (32) for interlocking without the use of glue with decorative panels provided with a similar tongue and groove. According to a more preferred embodiment, the tongue (31) and the groove (32) form part of a base layer (35).

[0043] Decorative panels that include a tongue and a groove of a special shape (see Figure 3) can be fitted together. The advantage of this is quick and easy assembly of a floor or wall that does not require glue. The shape of the tongue and groove necessary to obtain a good mechanical joint is well known in the laminated flooring art, as exemplified in patent documents EP 2280130 A (FLOORING IND), WO 2004/053258 (FLOORING IND), US 2008010937 (VALINGE ) and US 6,418,683 (PERSTORP FLOORING).

[0044] Tongue and groove profiles are especially preferred for floor panels and wall panels, but in the case of furniture panels, such a tongue and groove profile is preferably absent for aesthetic reasons of furniture doors and drawer fronts . However, a tongue and groove profile can be used to click together with the other panels of the furniture, as illustrated by US 2013071172 (UNILIN).

[0045] A decorative panel, such as a floor panel, has a single inkjet printed image on a thermoplastic tinsel. However, an inkjet printed image can also be present on both sides of a base layer. The latter is especially desirable in the case of decorative panels for furniture. In this case, preferably the inkjet printed images are located between two thermoplastic tinsels on both sides of a base layer.

[0046] The decorative panels can have any desired shape, such as a square, a rectangle or an octagon. For floor covering, the decorative panels preferably have a rectangular shape, for example 18 cm x 140 cm and a thickness of 2 to 6 mm. At a thickness of no more than 6 mm, a large floor surface can be covered by a very limited total weight of decorative panels. The low weight increases comfort when installing the decorative panels and provides a financial benefit when transporting them to warehouses, compared to heavier wooden decorative panels.

[0047] . According to a preferred embodiment, the decorative panels are made in the form of oblong rectangular strips. Their dimensions can vary enormously. Preferably the panels are greater than 1 meter long, and greater than 0.1 meter wide, for example, the panels may be about 1.3 meters long and about 0.15 meters wide. According to a special embodiment the length of the panels is greater than 2 meters, with the width preferably being about 0.2 meters or more. The printing of these panels is preferably free from repetitions.

[0048] According to a preferred embodiment the decorative panels are selected from the group consisting of kitchen panels, floor covering panels, furniture panels, ceiling panels and wall panels.

[0049] The decorative panels may also include a sound-absorbing layer. An example of such a sound-absorbing layer is disclosed in US patent 8196366 (UNILIN). FIRST THERMOPLASTIC TINSELS

[0050] The first thermoplastic tinsel includes a thermoplastic tinsel and an image, generally a color pattern, printed thereon by means of an inkjet.

[0051] There is no real restriction on the content of the color pattern. The color pattern can also contain information such as text, arrows, logo and the like. The advantage of inkjet printing is that this information can be printed in low volume at no extra cost, unlike rotogravure printing.

[0052] According to a preferred embodiment, the color pattern is a wooden reproduction or a stone reproduction, but it can also be a fantasy or a creative pattern, such as an ancient map of the world or a geometric pattern, or even a single color to make, for example, a floor composed of black and red tiles or a single-colored furniture door.

[0053] An advantage of printing a wood color pattern is that a floor can be manufactured imitating in addition to oak, pine and beech, also very expensive wood such as black walnut that would not normally be available for home decoration.

[0054] An advantage of printing a stone color pattern is that a floor can be manufactured that is an exact imitation of a stone floor, but without the feeling of cold when walking barefoot on it and is easy to replace when over time according to fashion.

[0055] The first thermoplastic tinsel preferably has a thickness of at least 80 μm. When the inkjet image is printed on a transparent thermoplastic tinsel used as an outer protective layer of the decorative laminate, it preferably has a thickness of no more than 100 μm, more preferably 200 to 700 μm, and even greater preferably 300 to 500 μm.

[0056] If the first thermoplastic tinsel is used as a protective outer layer of the decorative laminate, it may include additional finishing layers on the surface, as described below for the second thermoplastic.

ACCORDING TO THERMOPLASTICS TINSEL

[0057] The second thermoplastic tinsel carries a layer that contains a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol. This layer ensures optimum adhesion to the inkjet printed image while flexibility can be maximized by the use of pigmented, free-radical UV-curable inkjet inks endowed with high amounts of compounds with an ethylenically unsaturated polymerizable group in the polymerizable composition of inkjet inks. The layer preferably includes a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol containing more than 80% by weight of vinyl chloride and 1 to 15% by weight of vinyl alcohol over the total weight of the copolymer. Another advantage of including vinyl alcohol in the specific vinyl chloride, vinyl acetate copolymer lies in the fact that the layer is not sticky and the second thermoplastic tinsel can be stored as a roll without causing adhesion problems.

[0058] The application of the layer containing a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol is preferably carried out using a coating technique selected from spray coating, dip coating, spatula coating, extrusion coating, spin coating, sliding hopper coating and curtain coating.

[0059] The layer containing a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol is applied to have a dry weight of preferably 1 to 10 g/m2, more preferably 2 to 7 g/m2, and more preferably 3 to 6 g/m2. Less than 1 g/m2 did not provide good adhesion, while above 10 g/m2, adhesion and viscosity problems could be observed again. A very consistent quality was achieved when coated under a dry weight of 2 to 6 g/m2.

[0060] A coating solution of the copolymer of vinyl chloride, vinyl acetate, vinyl alcohol is prepared preferably using an organic solvent that has a boiling point of no more than 95°C under normal pressure. This allows for fast drying, which is especially necessary in a single-pass inkjet printing process. The organic solvent for the copolymer of vinyl chloride, vinyl acetate, vinyl alcohol is preferably selected from methyl ethyl ketone or ethyl acetate to reduce the risk of explosion to a minimum.

[0061] The second thermoplastic tinsel is preferably used in the decorative laminate in the form of the outer layer, thereby forming a transparent protective layer for the visible inkjet image. However, additional finishing layers may be applied over the protective layer.

[0062] According to a preferred embodiment, an antistatic layer is applied to the protective layer. Techniques for making decorative panels anti-static are widely known in the art of decorative laminates, as exemplified by document EP 1567334 A (FLOORING IND).

[0063] In a particularly preferred embodiment, the decorative panel is provided with a polyurethane finishing layer on the protective layer.

[0064] The top surface of a decorative surface, i.e. at least the protective layer, is preferably provided with a relief that corresponds to the color pattern, such as, for example, wood grain, cracks and knots in a wooden print. Engraving techniques to obtain this relief are widely known in the art of covering panels, as set out, for example, in patent documents EP 1290290 A (FLOORING IND), US 2006144004 (UNILIN), EP 1711353 A (FLOORING IND) and US 2010192793 (FLOORING IND).

[0065] Most preferably, the relief is formed by pressing a digital recording plate, roller or belt against thermoplastic tinsel, which forms the protective layer during hot pressing.

[0066] A digital recording plate is comprised of a plate comprising elevations that can be used to form a relief on the decorative panel by pressing the digital recording plate against the protective layer of the decorative panel or nested decorative panels. The elevations may be cured inkjet droplets blasted by an inkjet printing device and, most preferably, UV-cured inkjet droplets. The elevations are preferably formed by printing and curing inkjet droplets onto already cured or pin-cured inkjet droplets. The plate is preferably stiffened using metal or rigid plastic.

[0067] An alternative to a digital recording plate can be comprised of a digital recording cylinder, which is a cylinder that comprises elevations to form a relief on the decorative panels, pressing and rotating the digital recording cylinder against the protective layer of decorative panels.

[0068] A topcoat, preferably a polyurethane topcoat, may include hard particles, such as corundum, to avoid scratching the top surface. The total amount of hard particles is preferably between 1 g/m2 and 100 g/m2, preferably 2 g/m2 to 50 g/m2.

[0069] Preferred hard particles are ceramic or mineral particles chosen from the group of aluminum oxide, silicon carbide, silicon oxide, silicon nitride, tungsten carbide, boron carbide and titanium dioxide, or any other oxide of metal, carbide, metal nitride or metal carbide. The most preferred hard particles are corundum and so-called Sialon ceramics. In principle, a variety of particles can be used. Of course, any mixture of the above-mentioned hard particles can also be applied.

[0070] The amount of hard particles can be determined depending on the desired scratch resistance.

[0071] Hard particles with an average particle size between 1 and 200 µm are preferred. Preferably, an amount of such particles between 1 and 40 g/m2 is applied above the printed pattern. An amount less than 20 g/m2 may be sufficient for lower grades.

[0072] The second thermoplastic tinsel preferably has a thickness of at least 80 μm. When the second thermoplastic tinsel is used as an external protective layer of the decorative laminate, it is preferably provided with a thickness of not more than 100 μm, more preferably 200 to 700 μm, and even more preferably 300 to 500 μm. BASE LAYERS

[0073] According to a preferred embodiment, the decorative panel (22) includes a base layer (35). A base layer provides sufficient rigidity to the decorative panel so that when, for example, a long rectangular decorative panel bends under its own weight, the panel does not break. For this reason, a base layer is preferably reinforced with fibers.

[0074] On a decorative surface (22), a base layer (21, 35) is attached to the opaque side of the thermoplastic tinsel of the first and second thermoplastic tinsel or attached to the side of a transparent thermoplastic tinsel in the event that both the first as the second thermoplastic tinsel is understood as transparent thermoplastic tinsel.

[0075] According to a preferred embodiment, the base layer (35) substantially includes polyvinyl chloride and reinforcing fibers. More preferably, the base layer substantially includes polyvinyl chloride and glass fibers.

[0076] The base layer may be composed of two tinsels, preferably polyvinyl chloride tinsels, interposed by a fiberglass fleece.

[0077] The base layer may contain mineral. Particularly suitable in the present case are talc or calcium carbonate (chalk), aluminum oxide, silica. The base layer may include a flame retardant agent.

[0078] The base layer can also be comprised of a so-called wood plastic composite (WPC), preferably containing one or more polymers or copolymers selected from the group consisting of polypropylene, polyethylene and polyvinyl chloride. PIGMENTED FREE RADICAL UV CURRABLE INKJET INKJETS

[0079] The color pattern is printed using one or more pigmented free radical UV-curable inkjet inks that contain a polymerizable composition that is comprised of: 30 to 90%, by weight, of one or more compounds with an ethylenically unsaturated polymerizable group; 10 to 70%, by weight, of one or more compounds with two ethylenically unsaturated polymerizable groups; and 0 to 10% by weight of one or more compounds with three or more ethylenically unsaturated polymerizable groups, wherein all percentages by weight are based on the total weight of the polymerizable composition.

[0080] According to a particularly preferred embodiment, the amount of the one or more compounds with an ethylenically unsaturated polymerizable group is greater than 72% by weight, more preferably greater than 80% by weight, wherein the percentage $, by weight, is based on the total weight of the polymerizable composition.

[0081] According to a preferred embodiment, the polymerizable compounds consist of more than 80% by weight, preferably more than 90% by weight, of acrylates and optional N-vinyl lactams, wherein the percentage by weight is based on the total weight of the polymerizable composition. These inkjet inks exhibit a high curing speed and are especially useful for UV LED curing.

[0082] In the most preferred embodiment, inkjet inks do not contain water or intentionally added organic solvents, but may contain a very small amount of water, generally less than 5% by weight of water based on total weight of the ink. This water was not intentionally added, but entered the formulation through other components as contamination, such as, for example, polar organic solvents. Amounts of water greater than 5% by weight of water based on the total weight of the ink often make inkjet inks unstable, preferably the water content is less than 1% by weight based on in the total weight of the paint and, most preferably, there is no water at all.

[0083] According to a less preferred embodiment, the pigmented UV-curable inkjet ink contains from 20 to 60% by weight of organic solvent based on the total weight of the inkjet ink. In such a case, in addition to UV curing, extra drying means for solvent evaporation become necessary.

[0084] Inkjet inks are composed into an inkjet ink set that is provided with differently colored inkjet inks. The inkjet ink set may be a standard CMYK ink set, but is preferably a CRYK ink set in which the magenta (M) ink is replaced by the red inkjet ink. Using a red inkjet ink enhances the color gamut for wood-based color patterns, which represent the majority of decorative floor panels.

[0085] The inkjet ink set can be extended with extra inks such as brown, magenta, red, green, blue, and/or orange for the purpose of further expanding the color range of the ink set. The inkjet ink set can also be extended by combining full-density inkjet inks with light-density inkjet inks. The combination of light and dark color inks and/or black and gray inks improves image quality with reduced grain. However, preferably the inkjet ink set consists of no more than 3 or 4 colors of inkjet inks, allowing the design of high-yield single-pass inkjet printers at an acceptable cost.

[0086] In addition to polymerizable compounds, free radical-free pigmentation inkjet inks include one or more photoinitiators, one or more co-initiators, one or more inhibitors and one or more surfactants in amounts that are desired to be jetted and heal. through inkjet printers.

[0087] According to a preferred embodiment, the monofunctional polymerizable compounds consist of monoacrylates and optionally N vinyl lactams. The use of mono acrylates and vinyl lactams instead of, for example, methacrylates, allows for high curing speeds.

[0088] Pigmented UV curable inkjet ink is a free radical curable inkjet ink. Industrial inkjet printing systems have been found to cationically cure inkjet inks, presenting jet reliability issues due to stray UV light. UV curing of ink has caused UV light reflections, including UV light that strikes the nozzle plate of an inkjet printhead and results in nozzle failures due to cured ink clogging in the nozzle. Unlike free radical ink, where the radical species have a much shorter shelf life, cationic curable ink continues to cure once an acid species has been generated by the UV light in the nozzle.

POLYMERIZABLE COMPOUNDS

[0089] The polymerizable compounds are preferably present in pigmented UV-curable inkjet inks in an amount of at least 60% by weight, more preferably at least 70% by weight, wherein the % by weight weight, is based on the total weight of the inkjet ink.

[0090] Any monomer and oligomer capable of polymerization by free radicals can be used as a polymerizable compound. The viscosity of UV-curable inkjet ink can be adjusted by varying the ratio of monomers to oligomers. Polymerizable compounds can be comprised of any monomer and/or oligomer found in the Polymer Handbook Vol 1 + 2, 4th edition, edited by J. BRANDRUP et al., Wiley-Interscience, 1999.

[0091] The ethylenically unsaturated polymerizable group is preferably selected from the group consisting of an acrylate, a methacrylate, an acrylamide, a methacrylamide, a styrene group, a maleate, a fumarate, an itaconate, a vinyl ether, an ester vinyl, an allyl ether and an allyl ester.

[0092] According to a preferred embodiment, polymerizable compounds with an ethylenically unsaturated polymerizable group are selected from acrylic acid, methacrylic acid, maleic acid (or its salts), maleic anhydride, alkyl (meth) acrylates (linear, branched and cycloalkyls) such as methyl (meth) acrylate, n-tert-butyl (meth) acrylate, tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate and 2-ethyl hexyl (meth) acrylate; aryl (meth) acrylates such as benzyl (meth) acrylate and phenyl (meth) acrylate; hydroxyalkyl (meth)acrylates, such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; (meth)acrylates with other types of functionalities (e.g., oxiranes, amino, fluorine, polyethylene oxide, substituted by phosphate) such as glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, (meth)acrylate methoxypoly ethylene glycol acrylate and tripropylene glycol (meth) acrylate phosphate; allyl derivatives such as allylglycid ether; styrenes such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetostyrene and styrenesulfonic acid; (meth) acrylonitrile; (meth) acrylamides (including N-mono and N,N-disubstituted) such as N-benzyl (meth) acrylamide; maleimides such as N-phenyl maleimide; vinyl derivatives such as vinylcaprolactam, vinylpyrrolidone, vinylimidazole, vinylnapthalene and vinyl halides; vinyl ethers such as vinyl methyl ether; vinyl esters of carboxylic acids, such as vinyl acetate, vinyl butyrate and vinyl benzoate.

[0093] In a more preferred embodiment, polymerizable compounds with an ethylenically unsaturated polymerizable group are selected from monoacrylates and vinyl lactams.

[0094] N-Vinyl lactams are monomers well known in the art and, therefore, a detailed description is not necessary. N-vinyl lactams have a vinyl group attached to the nitrogen atom of an amide group that can be further substituted in a manner analogous to (meth) acrylate monomers. Preferred examples are comprised of N-vinyl caprolactam (NVC) and N-vinyl pyrrolidone (NVP), with NVC being particularly preferred.

[0095] According to a preferred embodiment, the polymerizable compounds with an ethylenically unsaturated polymerizable group include at least one acyclic hydrocarbon monofunctional acrylate monomer, preferably selected from octadecyl acrylate (ODA), tridecyl acrylate (TDA) , isodecyl acrylate (IDA), lauryl acrylate (LA)).

[0096] According to a preferred embodiment, polymerizable compounds with two or more ethylenically unsaturated polymerizable groups are selected from the group consisting of triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1-6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentylglycol diacrylate, dimethylol-tricyclodecane diacrylate, bisphenol AEO (ethylene oxide) adductor diacrylate, bisphenol A PO adduct diacrylate (propylene oxide), neopentyl glycol hydroxy pivalate diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethylol tricyclodecane diacrylate and polytetramethylene glycol diacrylate, trimethylolpropane triacrylate, EO modified trimethylolpropane triacrylate, tri-(propylene glycol), caprolactone-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxy tetraacrylate, dipentaerythritol hexacrylate, ditrimethylol propane tetraacrylate, glycerinpropoxy triacrylate, alkoxylated cyclohexanone dimethanol, dipentaerit modified caprolactam diacrylate ritol hexacrylate, alkoxylated diacrylate cycle -hexanone dimethanol, alkoxylated hexanediol diacrylate, dioxane glycol diacrylate, dioxane glycol diacrylate, cyclohexanone dimethanol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, vinylether acrylates, propoxylated glycerin triacrylate and propoxylated trimethylolpropane triacrylate , di-trimethylolpropane tetracrylate, dipentaerythritol pentaacrylate, ethoxylated pentaerythitol tetraacrylate, methoxylated glycol acrylates and acrylate esters.

[0097] The preferred vinyl ether acrylates are those described in US 6310115 (AGFA). A particularly preferred compound is 2-(2-vinyloxyethoxy)ethyl acrylate. Other suitable vinyl ether acrylates are those set out in columns 3 and 4 of US 6767980 B (NIPPON SHOKUBAI).

DYES

[0098] The color pigments can be black, cyan, magenta, yellow, red, orange, violet, blue, green, brown, mixtures thereof and the like. A color pigment may be chosen from those set forth by HERBST, Willy, et al. Industrial Organic Pigments, Production, Properties, Applications. 3rd edition. Wiley - VCH, 2004. ISBN 3527305769.

[0099] A particularly preferred pigment for a cyan inkjet ink is a copper phthalocyanine pigment, most preferably C.I. Pigment Blue 15:3 or C.I. Pigment Blue 15:4.

[00100] Particularly preferred pigments for red or magenta paint are comprised of C.I. Pigment Violet 19, C.I. Pigment Red 254, C.I. Pigment Red 176, C.I. Pigment Red 202 and C.I. Pigment Red 122, and their mixed crystals.

[00101] Particularly preferred pigments for yellow inkjet ink are comprised of C.I Pigment Yellow 150, C.I. Pigment Yellow 155, C.I. Pigment Yellow 120 and C.I. Pigment Yellow 180, and their mixed crystals.

[00102] For black ink, suitable pigmented materials include carbon blacks such as RegalTM 400R, MogulTM L, ElftexTM 320 from Cabot Co., or Carbon Black FW18, Special BlackTM 250, Special BlackTM 350, Special BlackTM 550, PrintexTM 25, PrintexTM 35, PrintexTM 55, PrintexTM 90, PrintexTM 150T from DEGUSSA Co., MA8 from MITSUBISHI CHEMICAL Co., and C.I. Pigment Black 7 and C.I. Pigment Black 11.

[00103] Mixed crystals can also be used. Mixed crystals are also referred to as solid solutions. For example, under certain conditions, different quinacridones mix with each other to form solid solutions, which are quite different from physical mixtures of the compounds and the compounds themselves. In a solid solution, the component molecules enter the same crystal lattice, usually, but not always, in one of the components. The X-ray diffraction pattern of the resulting crystalline solid is characteristic of that solid and can be clearly differentiated from the pattern of a physical mixture of the same components in the same proportion. In such physical mixtures, the X-ray pattern of each of the components can be distinguished, and the disappearance of many of these lines is one of the criteria for the formation of solid solutions. A commercially available example is CinquasiaTM Magenta RT-355-D from Ciba Specialty Chemicals.

[00104] Pigment mixtures can also be used. For example, a black inkjet ink may include a carbon black pigment and at least one pigment selected from the group consisting of a blue pigment, a cyan pigment, a magenta pigment and a red pigment. A black inkjet ink has been found to allow for easier and better color management for wood colors.

[00105] The pigment particles in pigmented inkjet ink must be small enough to allow free flow of ink through the inkjet printing device, especially at the ejection nozzles. It is also desirable to use small particles to obtain maximum color strength and delay sedimentation.

[00106] The average particle size of the pigment in pigmented inkjet ink should be between 0.005 μm and 15 μm. Preferably, the average pigment particle size is between 0.005 and 5 μm, more preferably between 0.005 and 1 μm, particularly preferably between 0.005 and 0.3 μm and most preferably between 0.040 and 0.150 μm.

[00107] The pigment is most preferably used in inkjet ink in an amount of 0.1 to 20% by weight, more preferably 1 to 10% by weight, and even more preferably 2 to 6% by weight, based on the total weight of the pigment inkjet ink. A pigment concentration of at least 2% by weight is preferable to reduce the amount of jet ink required to produce the color pattern, while a pigment concentration greater than 5% by weight reduces the color gamut to print color pattern with print heads with a diameter of 20 to 50 μm.

[00108] A white ink inkjet ink preferably includes a pigment with a high refractive index, preferably a refractive index greater than 1.60, preferably greater than 2.00, more preferably greater than 2 .50 and with greater preference even higher than 2.60. Such white pigments generally have a very high hiding power, that is, a limited amount of white paint is needed to hide the color and defects of the central layer. The most preferred white pigment is comprised of titanium dioxide.

[00109] The white jet ink preferably contains the white pigment in an amount of 5% by weight to 30% by weight, more preferably 8 to 25% by weight of white pigment based on the total weight of white inkjet ink.

[00110] The numerical average particle diameter of the white pigment preferably ranges from 50 to 500 nm, more preferably from 150 to 400 nm, and most preferably from 200 to 350 nm. Sufficient hiding power cannot be obtained when the mean diameter is less than 50 nm, and the storage capacity and blastability of the ink tend to be degraded when the mean diameter is greater than 500 nm. POLYMER DISPERSING AGENTS

[00111] Typical polymeric dispersing agents are comprised of copolymers of two monomers, but may contain three, four, five or even more monomers. The properties of the polymeric dispersing agent depend on both the nature of the monomers and their distribution in the polymer. The copolymeric dispersing agent preferably has the following polymeric compositions: • statistically polymerized monomers (for example, monomers A and B polymerized in ABBAABAB); • alternating polymerized monomers (for example, monomers A and B polymerized in ABABABAB); • polymeric monomers with a gradient (conical) (for example, monomers A and B polymerized in AAABAABBABBB); • block copolymers (e.g. monomers A and B polymerized to AAAAABBBBBB) in which the block length of each of the blocks (2, 3, 4, 5 or more) is important to the dispersibility of the polymeric dispersing agent ; • graft copolymers (graft copolymers consist of a polymeric backbone with polymeric side chains attached to the backbone); and • mixed forms of these polymers, for example gradient block copolymers.

[00112] Suitable polymeric dispersing agents are listed in the “Dispersing agent” section, more specifically [0064] to [0070] and [0074] to [0077], in document EP 1911814 A (AGFA GRAPHICS).

[00113] The polymeric dispersion agent preferably has a numerical average molecular weight Mn situated between 500 and 30000, more preferably between 1500 and 10000.

[00114] The polymeric dispersing agent preferably has an average molecular weight Mw of less than 100,000, more preferably less than 50,000 and even more preferably less than 30,000.

[00115] The polymeric dispersing agent preferably has a PD polydispersity of less than 2, more preferably less than 1.75 and even more preferably less than 1.5.

[00116] Commercial examples of polymeric dispersing agents are as follows: • DISPERBYKTM dispersing agent available from BYK CHEMIE GMBH; • SOLSPERSETM dispersing agents available from NOVEON; • TEGOTM DISPERSTM dispersion agents from EVONIK; • EDAPLANTM dispersing agent from MÜNZING CHEMIE; • ETHACRYLTM dispersing agent from LYONDELL; • GANEXTM dispersion agent from the ISP; • DISPEXTM and EFKATM dispersing agents from CIBA SPECIALTY CHEMICALS INC; • DISPONERTM dispersion agent from DEUCHEM; and • JONCRYLTM dispersing agent from JOHNSON POLYMER.

[00117] Particularly preferred polymeric dispersing agents are comprised of SolsperseTM dispersing agent from NOVEON, EfkaTM dispersing agent from CIBA SPECIALTY CHEMICALS INC and DisperbykTM dispersing agent from BYK CHEMIE GMBH. Particularly preferred dispersing agents are NOVEON's SolsperseTM 32000, 35000 and 39000 dispersing agents.

[00118] The polymeric dispersing agent is preferably used in an amount of 2 to 600% by weight, more preferably 5 to 200% by weight, and even more preferably 50 to 90% by weight, based on weight of the pigment.

PHOTOINITIATION SYSTEM

[00119] A photoinitiator system is used to initiate polymerization of the polymerizable composition in inkjet inks. The photoinitiator system includes one or more photoinitiators and, optionally, one or more co-initiators.

[00120] The photoinitiator is a free radical initiator. A free radical photoinitiator is a chemical compound that initiates the polymerization of monomers and oligomers when exposed to actinic radiation by the formation of a free radical.

[00121] Two types of free radical photoinitiators can be distinguished and used in the inkjet ink of the present invention. A Norrish I type initiator is an initiator that cleaves upon excitation, producing the initial radical immediately. A type II Norrish initiator is a photoinitiator that is activated by actinic radiation and forms free radicals by hydrogen abstraction from a second compound that becomes the actual free radical initiator. This second compound is called a synergist or polymerization co-initiator. Both type I and type II photoinitiators can be used in the present invention, alone or in combination.

[00122] In order to further increase photosensitivity, the UV-curable inkjet ink may additionally contain co-initiators. Suitable examples of co-initiators can be categorized into three groups: 1. tertiary allylic amines, such as methyldiethanolamine, dimethylethanolamine, triethanolamine, triethylamine and N-methylmorpholine; 2. Aromatic amines such as amylparadimethyl aminobenzoate, 2-n-butoxyethyl-4-(dimethylamino)benzoate, 2-(dimethylamino)ethylbenzoate, ethyl-4-(dimethylamino)benzoate and 2-ethylhexyl-4-(dimethylamino)benzoate ; and 3. (meth)acrylated amines, such as dialkylamino alkyl (meth)acrylates (e.g., diethylaminoethyl acrylate) or N-morpholinoalkyl (meth)acrylates (e.g., N-morpholinoethyl acrylate). Preferred co-initiators are aminobenzoate

[00123] Suitable photoinitiators are set out in CRIVELLO, J.V., et al. VOLUME III: Photoinitiators for Free Radical Cationic. 2nd edition. Edited by BRADLEY, G.. London, UK: John Wiley and Sons Ltd, 1998. p.287-294.

[00124] Specific examples of photoinitiators may include, but are not limited to, the following compounds or combinations thereof: benzophenone and substituted benzophenones, 1-hydroxycyclohexyl phenyl ketone, thioxantones such as isopropylthioxanthone, 2-hydroxy-2-methyl -1-phenylpropane- 1-one, 2-benzyl-2-dimethylamino-(4-morpholinophenyl)butan-1-one, benzyl dimethylketal, bis(2,6-dimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2,2-dimethoxy-1,2-diphenylethan-1-one or 5,7-diiodo-3-butoxy-6-fluorone.

[00125] Commercial photoinitiators that are suitable include IrgacureTM 184, IrgacureTM 500, IrgacureTM 907, IrgacureTM 369, IrgacureTM 1700, IrgacureTM 651, IrgacureTM 819, IrgacureTM 1000, IrgacureTM 1300, IrgacureTM 1870, Daro curTM 1173, DarocurTM 2959, DarocurTM 4265 and DarocurTM ITX available from CIBA SPECIALTY CHEMICALS, LucerinTM TPO available from BASF AG, EsacureTM KT046, EsacureTM KIP150, EsacureTM KT37 and EsacureTM EDB available from LAMBERTI, H-NuTM 470 and H-NuTM 470X available from SPECTRA GROUP Ltd .

[00126] According to a preferred embodiment, the photoinitiator is selected from the group consisting of non-polymeric multifunctional photoinitiators, oligomeric or polymeric photoinitiators and polymerizable photoinitiators. This diffusion-impeded photoinitiator exhibits much lower mobility in a cured layer of UV-curable inkjet inks than a low molecular weight monofunctional photoinitiator such as benzophenone. Including hindered diffusion photoinitiators, and also hindered diffusion co-initiators have a safety advantage for the inkjet printer operator.

[00127] Most preferably, the diffusion-impeded photoinitiator is a polymerizable photoinitiator, preferably with at least one acrylate group. And even more preferably, the hindered diffusion co-initiator is a polymerizable co-initiator, preferably having at least one acrylate group.

[00128] The suitable diffusion-impeded photoinitiator may contain one or more photoinitiator functional groups derived from a Norrish type I photoinitiator selected from the group consisting of benzoin ethers, benzylacetals, α,α-dialkoxyacetophenones, α-hydroxyalkylphenones, α-aminoalkylphenones, acylphosphine oxides, acylphosphine sulfides, α-haloketones, α-halosulfones and phenylglyoxalates.

[00129] A suitable diffusion-impeded photoinitiator may contain one or more photoinitiator functional groups derived from a Norrish type II initiator selected from the group consisting of benzophenones, thioxanthones, 1,2-diketones and anthraquinones.

[00130] Suitable delayed diffusion photoinitiators are also those described in document EP 2053101 A (AGFA GRAPHICS) in paragraphs [0074] and [0075] for difunctional and multifunctional photoinitiators, in paragraphs [0077] to [0080] for polymeric photoinitiators and in paragraphs [0081] to [0083] for polymerizable photoinitiators.

[00131] Other preferred polymerizable photoinitiators are those set forth in documents EP 2065362 A (AGFA) and EP 2161264 A (AGFA).

[00132] A preferred amount of photoinitiator ranges from 0 - 50% by weight, more preferably 0.1 - 20% by weight, and most preferably 0.3 - 15% by weight of the total weight of the dispersion or curable pigment ink.

[00133] Preferred hindered diffusion co-initiators are the polymerizable co-initiators set out in patent document EP 2053101 A (AGFA GRAPHICS) in paragraphs [0088] and [0097].

[00134] Preferred hindered diffusion co-initiators include a polymeric co-initiator having a dendritic polymeric architecture, more preferably a hyper-branched polymeric architecture. Preferred hyperbranched polymeric co-initiators are those set forth in US patent document 2006014848 (AGFA).

[00135] The UV-curable ink preferably comprises the hindered diffusion co-initiator in an amount of 0.1 to 50% by weight, more preferably in an amount of 0.5 to 25% by weight, more preferably in an amount of 1 to 10%, by weight, of the total weight of the paint.

POLYMERIZATION INHIBITORS

[00136] Inkjet ink that can be cured by UV may contain a polymerization inhibitor. Suitable polymerization inhibitors include phenol-type antioxidants, hindered amine light stabilizers, phosphorous-type antioxidants, hydroquinone monomethyl ether commonly used in (meth)acrylate and hydroquinone monomers, t-butylcatechol, pyrogallol can also be used.

[00137] Commercial inhibitors that are suitable are comprised, for example, by SumilizerTM GA-80, SumilizerTM GM and SumilizerTM GS produced by Sumitomo Chemical Co. Ltd.; GenoradTM 16, GenoradTM 18 and GenoradTM 20 from Rahn AG; IrgastabTM UV10 and IrgastabTM UV22, TinuvinTM 460 and CGS20 from Ciba Specialty Chemicals; FloorstabTM UV range (UV-1, UV-2, UV-5 and UV-8) from Kromachem Ltd, AdditolTM S range (S100, S110, S120 and S130) from Cytec Surface Specialties.

[00138] Since excessive addition of these polymerization inhibitors will decrease the paint's sensitivity to curing, it is preferred that the amount capable of preventing polymerization is determined before mixing. The amount of polymerization inhibitor is preferably less than 2% by weight based on the total weight of the inkjet ink.

SURFACTANTS

[00139] Surfactants are used in inkjet inks to reduce the surface tension of the ink in order to reduce the contact angle on the thermoplastic tinsel, that is, to improve the wetting of the tinsel by the ink. On the other hand, inkjet ink must meet stringent performance criteria in order to be properly jetted with high precision, reliability and over an extended period of time. To achieve both wetting of the substrate by the ink and high blasting performance, typically the surface tension of the ink is reduced by the addition of one or more surfactants. In the case of UV-curable inkjet inks, however, the surface tension of the inkjet ink is not only determined by the amount and type of surfactant, but also by the polymerizable compounds, the polymeric dispersing agent and others. additives in the paint composition.

[00140] Surfactants can be anionic, cationic, non-ionic or zuiterionic and are generally added in a total amount of less than 20% by weight based on the total weight of the inkjet ink and particularly by a total of less than 10% by weight based on the total weight of the inkjet ink.

[00141] Surfactants that are suitable include fluorinated surfactants, fatty acid salts, ester salts of a higher alcohol, alkylbenzene sulfonate salts, sulfosuccinate ester salts and phosphate esters of a higher alcohol (for example, dodecyl benzene sodium sulfonate and sodium dioctyl sulfosuccinate), ethylene oxide adducts of a higher alcohol, ethylene oxide adducts of an alkylphenol, ethylene oxide adducts of a polyhydric alcohol fatty acid ester and their acetylene glycol and ethylene oxide (e.g., polyoxyethylene nonylphenyl ether, and SURFYNOLTM 104, 104H, 440, 465 and TG available from AIR PRODUCTS & CHEMICALS INC.).

[00142] Preferred surfactants include fluoro surfactants (such as fluorinated hydrocarbons) and silicone surfactants. Silicones are typically siloxanes and can be alkoxylated, polyether modified, polyester modified, polyether modified hydroxy functional, amine modified, epoxy modified and other modifications or combinations thereof. Preferred siloxanes are polymeric, for example, polydimethyl siloxanes.

[00143] The fluorinated or silicone compound used as a surfactant can be comprised of a crosslinkable surfactant. Suitable copolymerizable compounds that have surfactant effects include, for example, polyacrylate copolymers, silicone-modified acrylates, silicone-modified methacrylates, acrylated siloxanes, polyether-modified acrylic-modified siloxanes, fluorinated acrylates and fluorinated methacrylate. These acrylates can be mono-, di-, tri- or higher functional (meth) acrylates.

[00144] Depending on the application, a surfactant can be used with a high, low or intermediate dynamic surface tension. Silicone surfactants are generally known to be endowed with low dynamic surface tensions, while fluorinated surfactants are known to be endowed with higher dynamic surface tensions.

[00145] Silicone surfactants are often preferred in curable inkjet inks, especially reactive silicone surfactants, which can be polymerized together with the polymerizable compounds during the curing step.

[00146] Examples of useful commercial silicone surfactants are those supplied by BYK CHEMIE GMBH (including BykTM-302, 307, 310, 331, 333, 341, 345, 346, 347, 348, UV3500, UV3510 and UV3530), those supplied by TEGO CHEMIE SERVICE (including Tego RadTM 2100, 2200N, 2250, 2300, 2500, 2600 and 2700), EbecrylTM 1360 a polysilicon hexa acrylate from CYTEC INDUSTRIES BV and EfkaTM-3000 series (including EfkaTM-3232 and EfkaTM -3883) from EFKA CHEMICALS B.V.

PREPARATION OF INKJET INKS

[00147] The preparation of pigmented UV-curable inkjet inks is well known to the person skilled in the art. Preferred preparation methods are set out in paragraphs [0076] to [0085] of document WO 2011/069943 (AGFA).

INKJET PRINTING DEVICES

[00148] Inkjet inks can be jetted by means of one or more print heads that eject small drops (droplets) of ink in a controlled manner through nozzles onto an ink-receiving surface, which moves relative to the printhead(s).

[00149] A preferred print head for printing by the inkjet system is comprised of a piezoelectric head. Piezoelectric inkjet printing is based on the movement of a piezoelectric ceramic transducer when a voltage (voltage) is applied to it. Applying a voltage changes the shape of the ceramic piezoelectric transducer in the print head creating a void, which is then filled with ink. When the voltage is removed again, the ceramic expands to its original shape, ejecting a drop of ink from the print head. However, the inkjet printing method according to the present invention is not restricted to piezoelectric inkjet printing. Other inkjet printheads can be used and include various types, such as continuous type and thermal, electrostatic, and acoustic droplet types.

[00150] The inkjet print head normally moves back and forth in a transverse direction across the surface of the moving ink receiver. Many times the inkjet print head does not print on the way back. Preference is given to di-directional printing to obtain a high yield per area. Another preferred printing method is through a “single-pass printing process,” which can be accomplished using wide-page inkjet printheads or multiple staggered inkjet printheads that cover the entire width. from the surface of the ink receiver. In a single-pass printing process, the inkjet printheads generally remain stationary and the substrate surface is transported under the inkjet printheads. UV CURING DEVICE

[00151] UV-curable inkjet inks are cured by exposing them to ultraviolet radiation.

[00152] In inkjet printing, the curing means can be arranged in combination with the print head of the inkjet printer, moving with it in such a way that the curable composition is exposed to radiation of healing soon after being expelled.

[00153] In an arrangement of this type, it may be difficult to provide a sufficiently small radiation source, connected and moving with the print head. Therefore, a fixed static radiation source may be used, for example, a UV curing light source, connected to the radiation source by means of flexible radiation conductors, such as an optical fiber bundle or a flexible internally reflecting tube. .

[00154] Alternatively, actinic radiation can be delivered from a fixed source to a radiation head by means of a mirror arrangement that includes a mirror over the radiation head.

[00155] The radiation source arranged not to move with the print head, may also be an elongated radiation source that extends transversely across the ink-receiving surface to be cured and adjacent to the transverse path of the print head, of so that subsequent rows of images formed by the print head are caused to pass, gradually or continuously, beneath this radiation source.

[00156] Any source of ultraviolet light, as long as part of the emitted light can be absorbed by the photoinitiator or photoinitiator system, can be used as a radiation source, such as a high or low pressure mercury lamp, tube cold cathode, a black light, an ultraviolet LED, an ultraviolet laser and a UV flash light. Of these, the preferred source is one that has a relatively long wavelength UV contribution endowed with a dominant wavelength of 300-400 nm. Specifically, a UV-A light source is preferred due to reduced light scattering, resulting in more efficient interior curing.

[00157] UV radiation is generally classified as UV-A, UV-B, and UV-C as follows: • UV-A: 400 nm to 320 nm • UV-B: 320 nm to 290 nm • UV-C: 290 nm to 100 nm.

[00158] Furthermore, it is possible to cure the image by using, consecutively or simultaneously, two light sources of different wavelengths or illuminance. For example, the first UV source may be selected to be rich in UV-C, in particular in the range 260 nm-200 nm. The second UV source can then be rich in UV-A, e.g. a gallium-doped lamp, or a different lamp, high in both UV-A and UV-B. It was found that the use of two UV sources has advantages, for example, a fast curing speed and a high degree of curing.

[00159] To facilitate curing, the inkjet printer generally includes one or more oxygen depletion units. Oxygen depletion units place a blanket of nitrogen or other relatively inert gas (e.g. CO2), with adjustable position and adjustable inert gas concentration, to reduce the oxygen concentration in the curing environment. Residual oxygen levels are generally kept as low as 200 ppm, but are generally in the range of 200 ppm to 1200 ppm.

Example Materials

[00160] All materials used in the following examples were readily available from standard suppliers such as Sigma-Aldrich (Belgium) and Acros (Belgium), unless otherwise specified.

[00161] PB15:4 is an abbreviation used for a C.I. Pigment Blue 15:4 pigment, available as HostapermTM Blue P-BFS from CLARIANT.

[00162] S35000 is an abbreviation used for SOLSPERSETM 35000, a polyethylene imine polyester hyperdispersion agent from LUBRIZOL.

[00163] DB162 is an abbreviation used for the polymeric dispersing agent DisperbykTM 162 available from BYK CHEMIE GMBH from which the solvent mixture of 2-methoxy-1-methylethyl acetate, xylene and n-butylacetate has been removed. The polymeric dispersing agent is comprised of a polyester-polyurethane dispersing agent based on caprolactone and toluene diisocyanate which is endowed with an amine value of 13 mg KOH/g, an Mn of about 4.425 and an Mw of about of 6,270.

[00164] EFKA is comprised of a polyacrylate dispersing agent, available as EfkaTM 7701 from BASF.

[00165] NVC is comprised of N-vinyl caprolactam available from BASF BELGIUM, NV.

[00166] IBOA is comprised of isobornylacrylate, available as SartomerTM SR506D from ARKEMA.

[00167] ACMO is comprised of acryloyl morphorline, available at

[00168] IDA from RAH. is comprised of isodecyl acrylate, available as SartomerTM SR395 from SARTOMER.

[00169] PEA is comprised of 2-phenoxyethyl acrylate, available as SartomerTM SR339C from ARKEMA.

[00170] THFA is tetrahydrofurfuryl acrylate available as SartomerTM SR285 from ARKEMA.

[00171] TBCH is comprised of 4-tert.butylcyclo hexylacrylate available under the trade name SartomerTM CD217 from ARKEMA.

[00172] EPA is comprised of ethoxylated nonylphenol acrylate available as SartomerTM SR504D from ARKEMA.

[00173] GenomerTM 1122 is comprised of a monofunctional urethane acrylate from RAHN.

[00174] PEG400DA is comprised of polyethylene glycol diacrylate, available as SartomerTM SR344 from ARKEMA.

[00175] VEEA is comprised of 2-(2'-vinyloxyethoxy) ethyl acrylate, a difunctional monomer available from NIPPON SHOKUBAI, Japan.

[00176] DPGDA is comprised of dipropylene glycoldiacrylate, available as LaromerTM DPGDA from BASF.

[00177] MPDA is comprised of 3-methyl-1,6-pentanediyl diacrylate available as SartomerTM SR341 from ARKEMA.

[00178] TMPTA is comprised of trimethylolpropane triacrylate available as SartomerTM SR351 from ARKEMA.

[00179] SR9035 is comprised of an ethoxylated tetracrylate (15) trimethylolpropane containing fifteen ethoxy units having a molecular weight of 956 and available as SartomerTM SR9035 from SARTOMER.

[00180] TPO is comprised of 2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide available as OmniradTM TPO by IGM.

[00181] TPO-L is comprised of an acylphosphine oxide photoinitiator, available as OmniradTM TPO-L from IGM RESINS.

[00182] IrgacureTM 819 is comprised of a bisacyl phosphine oxide photoinitiator available from BASF.

[00183] DarocurTM ITX is an isomeric mixture of 2- and 4-isopropylthioxanthone from BASF.

[00184] DETX is an abbreviation for GenocureTM DETX, a photoinitiator available from RAHN.

[00185] IrgacureTM 184, IrgacureTM 379 and IrgacureTM 907 are photoinitiators available from BASF.

[00186] Benzophenone is available as OmniradTM BP from IGM RESINS.

[00187] PBZ is comprised of 4-phenyl benzophenone, a photoinitiator available as GenocureTM PBZ from RAHN AG.

[00188] EPD is comprised of ethyl 4-dimethyl aminobenzoate, available as GenocureTM EPD from RAHN AG.

[00189] EHA is comprised of 2-ethulhexyl 4-dimethylamino benzoate available as GenocureTM EHA from RAHN.

[00190] CN963B80 is comprised of a difunctional co-initiator available as SartomerTM CN963B80 from ARKEMA.

[00191] CN3755 is comprised of a diacrylated co-initiator available as SartomerTM CN3755 from SARTOMER.

[00192] PMF is comprised of p-methoxy phenol.

[00193] BHT is an abbreviation for 2,6-di-tert.butyl-4-methylphenol (CASRN128-37-0) from ALDRICH CHEMICAL CO.

[00194] CupferronTM AL is comprised of N-nitrosophenyl aluminum hydroxylamine, from WAKO CHEMICALS LTD.

[00195] IrgastabTM UV10 is comprised of 4-hydroxy-2,2,6,6-tetramethylpiperidinooxy sebacate, from BASF.

[00196] BYKTM UV3510 is comprised of a modified polydimethylsiloxane polyether wetting agent, available from BYK CHEMIE GMBH.

[00197] TegoglideTM 410 and TegoglideTM 450 are comprised of surfactants from EVONIK.

[00198] SilwetTM L7500 is comprised of a silicone surfactant available from MOMENTIVE PERFORMANCE MATERIALS.

[00199] SolbinTM AL is comprised of a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol from NISSIN CHEMICAL CO LTD.

[00200] UAGHTM is comprised of a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol from UNIVAR.

[00201] UMOHTM is comprised of a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol from WUXI HONGHUI RESIN CO LTD.

[00202] SunvacTM GH is comprised of a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol from YANTAI SUNY CHEM INTERNATIONAL CO LTD

[00203] LPOHTM is comprised of a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol from WUXI HONGHUI RESIN CO LTD.

[00204] SolbinTM TA3 is comprised of a copolymer of vinyl chloride, vinyl adetate, hydroxypropylacrylate, from NISSIN CHEMICAL CO LTD.

[00205] VinnolTM E22-48A is comprised of a copolymer of vinyl chloride, hydroxypropylacrylate, from WACKER-CHEMIE.

[00206] VinnolTM E15-40A is comprised of a copolymer of vinyl chloride, hydroxypropylacrylate, from WACKER-CHEMIE.

[00207] SolbinTM M5 is comprised of a copolymer of vinyl chloride, vinyl acetate, hydroxy alkylacrylate from NISSIN CHEMICAL CO LTD.

[00208] P2 is comprised of an 80 μm thick opaque soft polyvinyl chloride tinsel.

[00209] C3 is comprised of a 500 μm thick transparent polyvinyl chloride tinsel. MEASUREMENT METHODS 1. Adhesion

[00210] Adhesion was determined by testing the peel force in accordance with EN431: 1994 on a 50 mm wide sample at a speed of 100 mm / min., but with a measuring angle of 360°. For good adhesion, a peeling force of 75 N is desirable. 2. Flexibility

[00211] A UV-curable inkjet ink was applied to a MetamarkTM MD5-100 substrate using a coating bar and a 10 m bar. The coated sample was fully cured using a Fusion DRSE-120 conveyor, equipped with a Fusion VPS/I600 lamp (D-bulb), which transported the samples under the UV lamp on a conveyor belt at a speed of 20 m/min.

[00212] Flexibility was determined using a custom-built apparatus to stretch a 1 cm wide strip obtained from the coated sample using a cutter. The strip was mounted between a first fixed wall and a second wall that could be horizontally moved by rotating a handle.

[00213] The strip was lengthened from an original length L1 of 5 cm to the length L2 at which the strip broke. Elongation was calculated as a percentage according to the following mathematical formula: Elongation(%) = (L2 - L1 / L1) x 100

[00214] The flexibility assessment was carried out according to the classification described in Table 2.

Example 1

[00215] This example illustrates that a combination of specific pigmented UV-curable inkjet inks in combination with a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol provided good adhesion and high flexibility in hot pressing a panel decorative using polyvinyl chloride tinsel. CYAN PIGMENT DISPERSION PREPARATION

[00216] UV-curable pigmented inkjet inks were prepared using a PB15:4 cyan pigment dispersed according to the following method. The components according to D-1 or D-2 in Table 3 were mixed for 30 minutes using a DISPERLUXTM disperser from DISPERLUX SARL, Luxembourg. The dispersions were then milled using a Bachofen DYNOMILL ECM mill filled with 0.4 mm yttrium stabilized zirconia globules ("high wear resistance zirconium grinding media" sourced from TOSOH Co.). The mixtures were circulated in the mill for 2 hours. After grinding, the pigment dispersions were discharged over a 1 μm filter into a vessel. PREPARATION OF INKJET INKS

[00217] Comparative inkjet inks C1 to C-7 and inkjet inks of the invention I-1 to I-3 were prepared by combining the components according to Table 4 and Table 5. The %, by weight, is based on the total weight of the inkjet ink.

[00218]

[00219]

[00220] All inks had a viscosity and surface tension suitable for inkjet printing. MANUFACTURING OF DECORATIVE PANEL

[00221] Inkjet inks were applied to the matte side of a P2 thermoplastic tinsel at a thickness of 10 μm. The samples were UV cured using a Fusion DRSE-120 conveyor, equipped with a Fusion VPS/I600 lamp (D-bulb), which transported the samples under the UV lamp on a conveyor belt under a speed of 20 m/min. The maximum lamp power was 1.05 J/cm2 and a peak intensity of 5.6 W/cm2.

[00222] A C3 thermoplastic tinsel was coated with a SolbinTM AL MEK solution to a dry thickness of 3 g/m2. Each of the P2 coated thermoplastic tinsel was combined with a C3 clear thermoplastic tinsel by having the paint layer on the P2 tinsel facing the layer containing the vinyl chloride, vinyl acetate, vinyl alcohol tinsel copolymer on the C3 tinsel. Together with a 4 mm thick PVC tinsel containing glass fibers as a base layer, tinsel P2 and C3 were hot pressed for 1 minute using an embossing plate under a temperature of 200°C and a pressure of 12 bar and then cut into the shape of a decorative panel.

EVALUATION AND RESULTS

[00223] The hot-pressed samples were evaluated for adhesion and flexibility. The results are shown in Table 6. Compounds with one, two and three ethylenically unsaturated polymerizable groups are represented by respectively “1 =”, “2 =” and “3 =”, on which their weight percentages are based in the total weight of the polymerizable composition.

[00224]

[00225] From Table 6, it can be seen that only pigmented UV-curable inkjet inks I-1 to I-3 were able to provide decorative panels endowed with good flexibility and good adhesion.

Example 2

[00226] This example illustrates the effect of the type of vinyl chloride, vinyl acetate copolymer on adhesion when heat pressing a decorative panel using polyvinyl chloride tinsel. DECORATIVE PANEL MANUFACTURING

[00227] Inkjet inks C-1, I-2 and I-3 were used for preparing decorative panels in the same way as shown in Example 1, with the exception that the SolbinTM AL copolymers were replaced by a copolymer of vinyl chloride, vinyl acetate as shown in Table 7.

[00228]

[00229] The vinyl chloride (VC) vinyl acetate (VA) copolymer may contain different types of a third monomer. It can be seen from Table 7 that only vinyl alcohol (VOH) is capable of providing sufficient adhesion with the specific UV-curable inkjet inks according to the invention I-2 and I-3. Omitting vinyl acetate (VA) or including other types of monomer such as 2-hydroxy acrylate or decarbonic acid results in inferior adhesion. LIST OF REFERENCE NUMBERS

[00230]

Claims (15)

1. Method for manufacturing decorative surfaces that includes, in order, the steps of: a) inkjet printing (19) an image on a first thermoplastic tinsel (12) by means of jetting and UV curing one or more inks free-radical, pigmented, UV-curable inkjet inkjets on the first thermoplastic tinsel (12); b) apply to the inkjet printed image a second thermoplastic tinsel (12) carrying a layer containing a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol with the layer facing the inkjet printed image on the first thermoplastic tinsel; and c) hot pressing (20) the first and second thermoplastic tinsel into a decorative laminate; characterized by the fact that at least one of the first and second thermoplastic tinsels is comprised of a transparent thermoplastic tinsel; and that the one or more pigmented free radical UV-curable inkjet inks contains a polymerizable composition that is endowed with: 30 to 90%, by weight, of one or more compounds with an ethylenically unsaturated polymerizable group; 10 to 70%, by weight, of one or more compounds with two ethylenically unsaturated polymerizable groups; and 0 to 10%, by weight, of one or more compounds with three or more ethylenically unsaturated polymerizable groups, wherein all percentages, by weight, are based on a total weight of the polymerizable composition. 2. Method according to claim 1, characterized by the fact that it further includes step d) of cutting the laminate in the form of a decorative panel (22). 3. Method according to claim 1 or 2, characterized by the fact that the first and second thermoplastic tinsel are comprised of polyvinyl chloride tinsel. 4. Method according to any one of claims 1 to 3, characterized in that the one or more pigmented free radical UV-curable inkjet inks are printed on a transparent thermoplastic tinsel. 5. Method according to any one of claims 1 to 3, characterized in that the one or more pigmented free radical UV-curable inkjet inks are printed on an opaque thermoplastic tinsel. 6. Method according to any one of claims 1 to 5, characterized in that the decorative surface (22) includes a base layer (21, 35) attached to the opaque thermoplastic tinsel side of the first and second thermoplastic tinsel or attached next to a transparent thermoplastic tinsel if both the first and second thermoplastic tinsels are comprised of transparent thermoplastic tinsels. 7. Method according to claim 6, characterized in that the base layer (21, 35) substantially includes polyvinyl chloride and reinforcing fibers. 8. Method according to claim 7, characterized in that the reinforcing fibers are comprised of glass fibers. 9. Method according to any one of claims 1 to 8, characterized in that the one or more pigmented free radical UV-curable inkjet inks include at least one monomer selected from N-vinyl lactam and an acyclic hydrocarbon monoacrylate. 10. Method according to any one of claims 1 to 9, characterized by the fact that hot pressing (20) is carried out by preheating the first and second thermoplastic tinsel to a temperature above 130°C. 11. Method according to any one of claims 1 to 10, characterized in that the layer contains a copolymer of vinyl chloride, vinyl acetate, vinyl alcohol containing more than 80% by weight of vinyl chloride. vinyl and 1 to 15% by weight of vinyl alcohol based on the total weight of the copolymer. 12. Method according to any one of claims 1 to 11, characterized in that the vinyl chloride, vinyl acetate, vinyl alcohol copolymer layer has an anhydrous weight of 1 to 10 g/m2. 13. Decorative panel (22), characterized by the fact that it is obtained by means of the method according to any one of claims 1 to 12. 14. Decorative panel according to claim 13, characterized in that it is provided with a tongue (31) and groove (32) for glueless interlocking of similar decorative panels. 15. Decorative panel according to claim 13 or 14, characterized in that it is provided with a polyurethane finishing layer on a transparent thermoplastic tinsel of the first and second thermoplastic tinsel.