KR102193522B1 - Method of producing a building panel using digital printing - Google Patents

Abstract

The present invention provides a carrier 3 comprising a thermoplastic material, applying a primer comprising at least one salt, preferably a metal salt on the first surface of the carrier 3, and using digital printing to apply the carrier ( Printing a first print 10 with an aqueous pigment ink composition on the first surface of 3), applying a protective layer 4 on the carrier 3 and applying the carrier 3 to a core comprising a thermoplastic material ( 2) a building panel (1) comprising applying on top and applying heat and pressure to press the protective layer (4), carrier (3) and core (2) together to form the building panel (1), eg For example, it relates to how to produce floor panels. In addition, the present invention relates to a method of forming a decorative substrate.

Description

How to produce a building panel using digital printing {METHOD OF PRODUCING A BUILDING PANEL USING DIGITAL PRINTING}

The present invention relates to a method of producing a building panel comprising a core and a printed carrier of a thermoplastic material forming a decor layer. The invention also relates to a method of forming a decorative substrate.

In recent years, so-called Luxury Vinyl Tiles and Planks (LVT) have gained increasing success. Floor panels of this type usually comprise a thermoplastic core, a thermoplastic decor layer arranged on the core, a protective layer on the decor layer, and a coating applied on the protective layer. The thermoplastic material is often PVC. Patterns resembling natural stone, wood, ceramics, etc. are printed on the decor layer. These patterns are often printed by rotogravure printing or direct printing. However, rotogravure printing or direct printing does not provide the desired flexibility in changing the design of the pattern and adjusting the pattern for different needs of the client. In addition, certain repetitions of the pattern cannot be avoided by rotogravure printing or direct printing.

In recent years, digital printing offers new possibilities to the flooring industry to customize decorative patterns for flooring applications and to print a small amount of decorative layers. Digital printing typically refers to printing using non-contact printing, for example using Drop-on-Demand (DOD) technology. A drop of ink is placed very accurately on a paper or wood surface. Examples of DOD technology are piezoelectric DOD inkjet and thermal DOD inkjet. In piezoelectric DOD inkjet printers, piezoelectric materials change shape when voltage is applied. The change in shape of the piezoelectric material generates a pressure pulse in the fluid, thereby ejecting a drop of ink from the nozzle. In a thermal DOD inkjet printer, ink droplets are ejected by heating the ink to form ink vapor bubbles.

Different classes of inks can be used for digital printing, such as UV curable inks, solvent-based inks and water-based inks (also referred to as water-based and water-based inks). When printed on a thermoplastic surface, for example a layer configured to form a decor layer of LVT, printing is facilitated by using UV curable inks or solvent-based inks compared to aqueous inks. Printing with aqueous inks on thermoplastic surfaces has proven difficult. A drop of aqueous ink does not stay on the thermoplastic surface and tends to smudge, resulting in poor quality prints. However, for environmental reasons, it is preferred to replace UV curable inks and solvent-based inks.

When the floor panel is assembled, the protective layer is bonded to the thermoplastic decor layer. Accordingly, it is important that the print does not adversely affect the bonding between the layers.

It is an object of at least certain embodiments of the present invention to provide an improvement or at least an alternative to the above-described and prior art.

A further object of at least certain embodiments of the present invention is to provide a method for producing a building panel comprising a thermoplastic decor layer comprising printing with an aqueous pigmented ink composition.

A further object of at least certain embodiments of the present invention is to provide improved printing with water-based pigment inks on thermoplastics.

A further object of at least certain embodiments of the present invention is to reduce bleeding of aqueous pigmented inks on thermoplastics.

A further object of at least certain embodiments of the present invention is to provide improved printing with aqueous pigment inks on thermoplastics without adversely affecting the bonding of the printed thermoplastic surface to other layers, such as a protective layer arranged on the printed surface. To provide.

At least some of these and other purposes and advantages, which are clear from the description, are methods of producing building panels, such as floor panels,

Providing a carrier comprising a thermoplastic material,

Applying a primer comprising at least one salt, preferably a metal salt, on the first surface of the carrier,

Printing a first print with an aqueous pigment ink composition on the first surface of the carrier using digital printing,

Applying a protective layer on the carrier and the carrier on the core comprising a thermoplastic material,

This has been achieved by a method comprising pressing the protective layer, carrier and core together to form a building panel by applying heat and pressure.

In building panels, the printed carrier forms the decor layer of the floor panel. Preferably, the protective layer is arranged on the first surface of the carrier. Preferably, the second surface of the carrier faces the core.

Water-based inks may also be referred to as water-based or water-based inks.

The building panel can be a floor panel. The floor panel may be of a type usually referred to as Luxury Vinyl Tile (LVT) or Luxury Vinyl Plank.

According to another aspect of the invention, the core may be formed of a material different from the thermoplastic material, for example a wood-based material such as MDF or HDF. The core according to the first aspect of the invention may comprise a layer comprising a thermoplastic material arranged on a substrate, for example a wood-based substrate, for example MDF or HDF.

By means of at least certain embodiments of the method of the present invention it is possible to form the advanced design of the decor layer in a more flexible and inexpensive manner compared to rotogravure printing or direct printing. The design of the print can be customized, and repeating of the pattern can be prevented.

The advantage is that the aqueous ink composition can also be used when printing on a carrier of thermoplastic material. When printing with an aqueous ink composition without applying any primer to the surface prior to printing, the ink droplets tend to migrate on the surface of the carrier and tend to mix with each other, resulting in poor quality and blurry prints. do.

The primer is configured to change the surface properties of the carrier so that in one embodiment the surface becomes more suitable for printing with an aqueous pigment ink composition. The primer can be configured, for example, to increase the wetting capacity of the carrier surface so that the surface of the carrier acquires hydrophilic properties.

The primer comprises at least one salt, preferably an inorganic salt, more preferably a metal salt. These salts can be polyvalent metal salts.

The primer preferably forms a layer of salt crystals evenly distributed on the surface of the carrier. Preferably, the primer adheres and/or forms a film.

The primer comprising the salt is configured to impinge the ink composition. The salt of the primer precipitates or aggregates the pigment in the ink composition. The salt reacts with the aqueous ink composition, whereby the pigment in the ink composition precipitates. By colliding the aqueous pigment ink composition, the ink droplets are fixed at a predetermined position on the carrier, where the ink droplets are placed by a nozzle. By colliding the aqueous pigmented ink composition, ink drops are prevented from mixing with each other. The primer keeps the ink droplets on the location where they are applied on the surface of the carrier. The primer prevents ink droplets from collecting and mixing into large ink droplets. The primer prevents ink droplets from moving on the surface of the carrier. Thereby, it is possible to print with the aqueous pigment ink composition on the thermoplastic surface. In addition, by applying a primer prior to printing, a high-quality print made with an aqueous pigment ink composition can be obtained using digital printing. Thereby, it is possible to produce a building panel such as an LVT type floor panel with a high quality print obtained in an environmentally friendly manner.

In addition, the use of a primer comprising a salt does not adversely or at least substantially adversely affect the bonding of the printed carrier to the protective layer when applying heat and pressure to form the building panel. The primer and print do not reduce, or at least substantially reduce, the strength of the bond between the layers. Thereby, the desired bonding between the carrier and the protective layer is still achieved.

Further, the print is unaffected, or at least substantially unaffected, by applying heat and pressure to press the layers together to form a building panel, such as a floor panel. The primer has already agglomerated the ink so that the ink droplets are fixed on the carrier and not affected by pressure.

The primer may be an aqueous solution containing the at least one salt. The primer is applied prior to printing the print. The composition of the primer may be configured to match the composition of the ink. The primer can be applied as a coating layer on the carrier. Alternatively, the primer does not completely cover the surface of the carrier. The primer can be applied to a portion of the surface of the carrier. For example, if only part of the carrier is printed, for example a second print is printed on an already printed surface, the primer is only applied to this part of the carrier.

The primer can be applied using digital printing. Thereby, the application of the primer can be controlled with high accuracy. For example, by applying a primer to only specific areas of the carrier, the smearing of the ink can be adjusted to achieve the desired effect.

The primer may be an aqueous solution containing the salt.

The salt concentration of the primer may be at least 50% of the saturation point of the salt, preferably at least 70% of the saturation point of the salt, more preferably at least 90% of the saturation point of the salt. In one embodiment, the primer is a nearly saturated salt dispersion. The primer can be heated to a temperature above room temperature, for example 40 to 60°C.

The primer applied on the carrier may have a contact angle with water of less than 50°, preferably less than 40°, more preferably less than 35°, and about 30°. By reducing the contact angle, the spreading of the primer, and thereby the diffusion of the salt of the primer, on the surface of the carrier is improved. Thereby, the salt is evenly distributed on the surface so that a uniform base for the ink is formed.

The primer may comprise a humectant. Wetting agents increase the wetting capacity of the surface of the carrier. The wetting of the surface is thereby promoted. The wetting agent of the primer allows the surface of the carrier coated by the primer to obtain hydrophilic properties. By increasing the wetting of the surface, the salt crystals are homogeneously distributed over the surface of the carrier, which improves the print result. The wetting agent does not adversely affect the bonding of the printed carrier to the protective layer.

The humectant can be a non-ionic surfactant. The primer may comprise, for example, about 0.5 to 4% by weight of a wetting agent, preferably 1 to 4% by weight, for example, about 2% by weight of a wetting agent. The type and amount of wetting agent can be adjusted for the surface tension of the carrier.

The primer can be applied using digital printing. Thereby, the application of the primer can be controlled with high accuracy. For example, by applying a primer to only certain areas of the carrier, the smearing of the ink can be adjusted to achieve the desired effect.

The method may further comprise drying the primer applied on the first surface of the carrier prior to printing. Alternatively, printing in a wet primer may also be possible, depending on the primer used.

More than one layer of primer can also be applied to the surface of the carrier. The step of applying the primer may include applying the primer, drying the applied primer, applying an additional layer of primer, and drying the applied primer prior to printing. By applying more than one layer of primer, coating of the carrier surface by the primer is facilitated.

In one embodiment, the salt is applied in solid form on the carrier. Preferably, the solid salt crystals are evenly distributed over the surface of the carrier. Solid salt crystals can be attached to the surface of the carrier in several ways. In one embodiment, the carrier is heated before and/or during application of the salt in solid form. In one embodiment, the carrier is electrically charged such that the surface of the carrier attracts salt particles. In one embodiment, the plasticizer is applied to the surface of the carrier. The solid salt particles are applied to the plasticized surface of the carrier. In one embodiment, the solid salt particles are mechanically attached to the surface of the carrier. For example, the surface of the carrier can be porous to facilitate bonding of salt particles to the surface of the carrier.

The aqueous pigment ink composition may be a heat activated curing ink. The heat activated curing ink cures when exposed to heat. When heat is applied to the ink composition, the binder in the ink composition cures, whereby the ink is fixed to the surface. When the binder is cured, bleeding of the ink is reduced. By using a heat activated curing ink instead of a UV curing ink, a more environmentally friendly process is obtained.

The aqueous pigment ink composition may include a binder, water and a pigment. The binder can be dispersed in the ink composition. The binder can be a polymer or cellulose. Alternatively, the pigment can be coated with a binder, preferably a polymer. The pigment can be dispersed in the ink composition.

The method may further include applying heat to the print. By applying heat, the binder of the aqueous ink composition is cured. In addition, heat dries the aqueous ink composition faster. As an alternative or supplement, the carrier can also be heated before and/or during printing on the surface of the carrier.

Printing can be performed by an inkjet printer, preferably a piezoelectric Drop on Demand (DOD) inkjet printer.

The surface of the carrier can be pre-treated by corona, flaming or plasma. Corona, plasma, and flame treatment of the carrier surface enhances the chemical bonding of the carrier to the resin matrix. Thereby, bonding of the ink to the carrier is improved. Corona, flame or plasma treatment increases the wetting capacity of the surface of the carrier. Corona, flame or plasma treatment can be combined with applying a primer after corona, flame or plasma treatment.

The first surface of the carrier can face the core. The print is thereby printed on the lower surface of the carrier.

The first surface of the carrier may not face the core. The print is thereby printed on the upper surface of the carrier.

The method may further include printing a second print on the second surface of the carrier using digital printing. As a result, the carrier is provided with prints on both surfaces thereof. The same pattern or design can be printed on both surfaces of the carrier. Alternatively, the prints or designs can be different. The first and second prints can together form a specific design.

The method may further include printing a second print on the first print using a digital print. The first and second prints can be of the same design or pattern. Alternatively, the first and second prints can be different. The first and second prints can together form a specific design.

The method may further include arranging an additional carrier on the first carrier and printing a second print on the surface of the second carrier using digital printing.

The method may further include applying a decorative element on the carrier. The decorative member may be, for example, mineral particles, plastic particles, glass particles, colored fibers, or mother of pearl, which form a decorative effect. The mineral particles may be Granostar ^® or similar. The decorative member may be solid particles, preferably solid particles having a size exceeding 1 μm.

The protective layer is a thermoplastic material such as polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), polyethylene terephthalate (PET), polyacrylic Rate, polyvinyl butyral, or combinations thereof. The protective layer may be provided with a coating, preferably a UV curable coating, more preferably a coating comprising an acrylate oligomer, a methacrylate oligomer, or an unsaturated polyester. It is also contemplated that only the coating forming the protective layer is applied on the carrier forming the decor layer.

The thermoplastic material of the carrier is polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), polyethylene terephthalate (PET), polyacrylate, polyvinyl Butyral, or a combination thereof. The thermoplastic material of the core can be polyvinyl chloride (PVC) or polypropylene (PP). The thermoplastic core may be a Wood Plastic Composite (WPC).

The method may further comprise pressing the core, the carrier with the print thereon, and the protective layer with an embossed press plate. Thereby, a building panel having an embossed structure is formed.

The method may further include forming a mechanical locking system for horizontal and/or vertical fixing of the building panel adjacent at least one edge of the building panel.

According to a second aspect of the invention, a building panel, for example a floor panel, is provided. The building panel comprises a core comprising a thermoplastic material, a printed decor layer comprising a thermoplastic material, and a protective layer arranged on the printed decor layer, wherein the decor layer comprises a primer layer arranged on the surface of the decor layer. Provided, and the print is arranged on a primer layer, wherein the print comprises an aqueous pigment ink composition and the primer layer comprises a salt, preferably a metal salt.

The aqueous pigment ink composition may be a heat activated curing ink. The metal salt can be a polyvalent metal salt.

According to a third aspect of the present invention, a method of forming a decorative substrate is provided. The method provides a carrier comprising a thermoplastic material, applying a primer comprising at least one salt, preferably a metal salt on a first surface of the carrier, preferably on the first surface of the carrier by digital printing. Printing a first print with an aqueous pigmented ink composition on the carrier, applying a protective layer comprising a thermoplastic material on the first surface of the carrier, and pressing the protective layer and the carrier together to form a decorative substrate.

Embodiments according to the third aspect of the invention introduce all the advantages of the first aspect of the invention discussed above, whereby the above discussion is also applicable to the method according to the third aspect.

For example, a primer comprising a salt is configured to impinge the ink composition. The salt of the primer precipitates or aggregates the pigment in the ink composition. The salt reacts with the aqueous ink composition so that the pigment of the ink composition precipitates. By colliding the aqueous pigmented ink composition, the ink droplets are fixed at a predetermined position on the carrier, where the ink droplets are disposed by a nozzle. By colliding the aqueous pigment ink composition, the ink drops are prevented from mixing with each other. The primer causes the ink droplets to stay on the location where the ink droplets are applied on the surface of the carrier. The primer prevents ink droplets from accumulating and mixing into large ink droplets. The primer prevents ink droplets from moving on the surface of the carrier. Thereby, it is possible to print with the aqueous pigment ink composition on the thermoplastic surface. In addition, by applying a primer prior to printing, a high quality print made with an aqueous pigment ink composition can be obtained by digital printing. Thereby, it is possible to produce LVT type floor panels with high quality prints obtained in an environmentally friendly manner.

Further, the use of a primer comprising a salt does not adversely or at least substantially adversely affect the bonding of the printed carrier to the protective layer when applying heat and pressure to form the building panel. The primer and print do not reduce, or at least substantially reduce, the bonding strength between the layers. Thereby, the desired bonding between the carrier and the protective layer continues to be achieved.

Further, the print is unaffected or at least substantially unaffected by applying heat and pressure to press the layers together to form a building panel. The primer already agglomerates the ink so that the ink droplets are fixed on the carrier and not affected by pressure.

Pressurization can be performed by applying heat and pressure. By applying heat and pressure, the carrier with the print and the protective layer are bonded together. The decorative substrate can be bonded to the core. The core may comprise, for example, a thermoplastic material, or a wood-based material, such as MDF or HDF.

The salt can be applied in solid form on the carrier.

The primer may be an aqueous solution containing the salt.

The salt concentration of the primer may be at least 50% of the saturation point of the salt, preferably at least 70% of the saturation point of the salt, more preferably at least 90% of the saturation point of the salt.

The primer applied on the carrier may have a contact angle of less than 50°, preferably less than 40°, more preferably less than 35°, for example about 30°.

The primer may comprise a humectant. The primer may comprise, for example, 0.5 to 4% by weight of a wetting agent, preferably 1 to 4% by weight, for example about 2% by weight of a wetting agent. Wetting agents may include non-ionic surfactants.

The primer can be applied using digital printing.

The method may further comprise drying the primer applied on the first surface of the carrier prior to printing.

The aqueous pigment ink composition may be a heat activated curing ink.

The aqueous pigment ink composition may include a binder, water and a pigment.

The method may further include applying heat to the print.

Printing can be performed by an inkjet printer, preferably a piezoelectric Drop on Demand (DOD) inkjet printer.

The protective layer may be a thermoplastic material such as polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), or polyethylene terephthalate (PET), poly Acrylate, polyvinyl butyral, or combinations thereof.

The thermoplastic material of the carrier is polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), or polyethylene terephthalate (PET), polyacrylate, poly Vinyl butyral, or combinations thereof.

The present invention will be described in more detail with reference to the accompanying schematic drawings, by way of example, showing embodiments of the present invention.
1 shows a plan view of an embodiment of a building panel, such as a floor panel.
2A shows a cross-section of one embodiment of a building panel, such as a floor panel.
2B shows a cross-section of one embodiment of a building panel, such as a floor panel.
2C shows a cross-section of one embodiment of a building panel, such as a floor panel.
2D shows a cross-section of one embodiment of a building panel, such as a floor panel.
3A shows a side view of a printing line.
3B shows a side view of an alternative printing line.
FIG. 3C shows a plan view of the printing line in FIG. 3A.
Figure 4 shows the bonding of layers to form a building panel.
5 shows a decorative substrate.

A building panel such as a floor panel 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2A to 2D. The floor panel 1 comprises a core 2, a carrier 3 provided with a print forming the decor layer 6, and a protective layer 4. The core 2, the carrier 3 and the protective layer 4 are bonded together to form the floor panel 1. The bottom panel 1 may also be provided with a back layer (not shown) arranged on the lower surface of the core 2. The coating 5 can be provided on top of the protective layer 4.

The core 2 comprises a thermoplastic material. The thermoplastic may be polyvinyl chloride (PVC) or polypropylene (PP). The core 2 may further contain fillers such as calcium carbonate, and additives such as plasticizers, impact modifiers, stabilizers, processing aids, pigments, lubricants and the like. Alternatively, the core may be a Wood Plastic Composite (WPC) comprising a thermoplastic binder and wood fibers or particles.

The core 2 may also comprise more than one layer. The layers can be of similar or different materials. The core 2 may comprise several layers comprising a thermoplastic material, or may comprise at least one layer comprising a thermoplastic material arranged on a substrate of a wood-based material, for example MDF or HDF.

The carrier 3 is a thermoplastic material such as polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), polyethylene terephthalate (PET), Polyacrylate, polyvinyl butyral, or combinations thereof. The carrier may further comprise additives, for example plasticizers. The carrier 3 may be in the form of a thermoplastic foil or film. The thickness of the carrier 3 may be 0.01 to 1 mm. The carrier 3 can be transparent, colored or opaque. The color of the carrier 3 can form a basic color for printing.

The protective layer 4 is arranged on the carrier 3. The protective layer 4 is bonded to the carrier 3. The protective layer 4 can be in the form of a thermoplastic foil or film. The protective layer 4 is a thermoplastic material, such as polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), polyethylene terephthalate (PET) , Polyacrylate, polyvinyl butyral, or combinations thereof. The protective layer 4 may further comprise additives, for example plasticizers. The thickness of the protective layer 4 may be 0.01 to 1 mm. Wear-resistant particles, for example aluminum oxide particles, may be included in the protective layer 4. The protective layer 4 is preferably transparent.

The coating 5 can be arranged on the protective layer 4. The coating 5 is preferably a UV curable coating, more preferably a coating comprising an acrylate oligomer, a methacrylate oligomer, or an unsaturated polyester.

In an alternative embodiment, the protective layer 4 is formed by a coating applied directly onto the printed carrier 3 forming the decor layer 6.

The bottom panel 1 may be provided with a back layer (not shown) on the lower surface of the core. The back layer comprises a thermoplastic material such as polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), or polyethylene terephthalate (PET). can do.

The carrier 3 is provided with a print 10 which gives the carrier its decorative properties. The printed carrier 3 forms the decor layer 6. The print 10 can be a decorative design. The decorative design can be a natural design and pattern, for example a wood pattern or a stone pattern. The decorative design can also be a fantasy design or pattern or photo.

The print is applied to the primer layer comprising at least one salt, preferably a metal salt. The salt crystals form a primer layer, on which the pigment of the ink is injected. The salt crystals preferably form a uniform layer. Prints and primers are described in more detail with reference to FIGS. 3A to 3C.

The floor panel 1 is provided with a mechanical locking system for fixing the floor panel 1 horizontally and/or vertically to an adjacent floor panel. The mechanical locking system comprises a tong groove 16 configured to receive a tong 15 of a floor panel adjacent a first edge of the floor panel, and a locking groove of the adjacent floor panel. And a locking strip 12 provided with a locking member 13 configured to cooperate with 14 and secure the floor panel 1 in a horizontal direction relative to an adjacent floor panel. The mechanical locking system cooperates with the second edge, a locking groove 14 configured to receive the locking member 13 of the adjacent floor panel, and the barrel groove 16 of the adjacent floor panel, and fixes the panel 1 in a vertical orientation. It further comprises a tong (15) configured to allow. A mechanical locking system is formed in the core 2 of the floor panel 1. Both the long side edge and the short side edge of the floor panel 1 may be provided with a mechanical locking system. Alternatively, the long side edge of the floor panel 1 may be provided with a mechanical locking system for fixing horizontally and vertically, and the short side edge may be provided with a mechanical locking system for fixing only horizontally. It is also contemplated that other locking systems can be used, for example of the type described in WO2007/015669.

In FIG. 2A, the carrier 3 is provided with a print 10 on its upper surface not facing the core 2.

In FIG. 2b the carrier 3 is provided with a print 10 on its lower surface facing the core 2. In this embodiment, the protective layer 4 and/or the coating 5 may be excluded. In the described embodiment, the protective layer 4 is arranged over the carrier 3 forming the decor layer 6 and the coating 5 is excluded. In the embodiment shown in Fig. 2b, the floor panel 1 comprises a core 2 of the type described above with reference to Figs. 1 and 2a, and a carrier 3 of the type described above with reference to Fig. 1a do. In all other aspects, the floor panel 1 corresponds to the floor panel 1 described with reference to FIGS. 1 and 2A.

In Fig. 2c, the carrier 3 is provided with two prints 10, 11 of the type described above. The first print 10 is arranged on the first surface of the carrier 3 facing the core 2. A second print 11 is printed on a second surface of the carrier 3 that does not face the core 2. The first and second prints 10 and 11 may have the same pattern or design. Alternatively, the first and second prints 10 and 11 may be different. As another alternative, the first and second prints 10, 11 may be of similar patterns or designs. The protective layer 4 is arranged on the carrier 3. The coating 5 can be applied on top of the protective layer 4. The floor panel 1 in Fig. 2c comprises a core 2, a carrier 3 and a protective layer 4 of the type described above with reference to Figs. 1 and 2A. In all other aspects, the floor panel 1 corresponds to the floor panel 1 described with reference to FIGS. 1 and 2A.

In FIG. 2d an additional carrier 7 is arranged on the carrier 3. The first print 10 is printed on the carrier 3, preferably on the upper surface of the carrier 3 not facing the core 2. The second print 11 is printed on the further carrier 7, preferably on the upper surface of the further carrier 7 not facing the core 2. By printing two layers, a print of an advanced design can be obtained. The first and second prints 10 and 11 may have the same pattern or design. As an alternative, the first and second prints 10, 11 can be different. As another alternative, the first and second prints 10, 11 may be of similar patterns or designs. Preferably, the protective layer 4 is arranged on the further carrier 7. The coating 5 can be applied on top of the protective layer 4. The additional carrier 7 is of the same type as the carrier 3.

Alternatively, the second print 11 is printed on the lower surface of the additional carrier 7. In this embodiment, the protective layer 4 and/or the coating 5 may be excluded. Accordingly, the additional carrier 7 also functions as a protective layer.

In all other aspects, for example the composition of the core 2, the carrier 3, the protective layer 4 and the coating 5, the floor panel 1 is described with reference to FIGS. 1 and 2A. Corresponds to the floor panel (1).

A method for producing a building panel, such as a floor panel 1 according to an embodiment of the present invention, and in particular for printing a decorative design, is described with reference to Figs. 3A, 3B and 3C. A carrier 3 in the form of a foil or film for forming a decor layer 6 of the type described above is provided. The carrier is a thermoplastic material such as polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), polyethylene terephthalate (PET), polyacrylate , Polyvinyl butyral, or combinations thereof. The carrier 3 is arranged on a roll 8.

The primer is applied on the first surface of the carrier 3. A primer is applied on the surface of the carrier 3 configured to form the decor layer 6. The primer is applied on the carrier 3 by means of an applying device 20.

In one embodiment, the primer is an aqueous solution, a salt, preferably at least one metal salt. The metal salt may be a monovalent metal salt, for example a monovalent metal salt comprising a monovalent ion such as Na ⁺ . The metal salt can be a polyvalent metal salt. Preferably, the polyvalent metal salt is a ^{Ca 2 +, Cu 2+, Ni} 2 +, Mg 2 +, Zn 2 +, or Ba ^{+ 2} and divalent ion, or Al ^{3 +,} or a trivalent ion such as Fe ^{+ 3,} such Includes. The metal salt can be, for example, sodium chloride or calcium chloride. The metal salt collides with the ink composition and precipitates the pigment of the ink composition. The salt can also be a non-metal salt, such as ammonium chloride.

The salt concentration of the primer may be at least 50% of the saturation point of the salt, preferably at least 70% of the saturation point of the salt, more preferably at least 90% of the saturation point of the salt. The primer can be a saturated solution, or a nearly saturated solution.

The primer may further comprise a humectant. The wetting agent increases the wetting capacity of the surface of the carrier 3. The humectant can be a non-ionic surfactant. The humectant may be a silicone surfactant, preferably a non-ionic silicone surfactant. The wetting agent may be a polyether modified siloxane. The wetting agent may be a polyether modified polysiloxane. The wetting agent may be a polyether modified polymethyl siloxane. As an alternative, the wetting agent can be a polydimethylsiloxane co-polymer. The primer may comprise 0.5 to 4% by weight of wetting agent, preferably 1 to 4% by weight, for example about 2% by weight of wetting agent.

The contact angle of the primer on the carrier may be less than 50°, preferably less than 40°, more preferably less than 35°, for example about 30°.

The primer is preferably applied homogeneously to the surface of the carrier 3 so that a uniform layer of salt crystals is formed on the surface of the carrier 3. The wetting agent promotes wetting of the surface by the carrier 3. The salt crystals are preferably evenly distributed over the surface of the carrier. Preferably, the primer coalesces and/or forms a film.

The primer may further include a binder. The binder of the primer may be different from the binder of the ink composition.

The aqueous primer dispersion is applied by spraying using a spraying device 20 in the embodiment shown in FIG. 3A. Alternatively, the primer can be applied by digital printing, curtain coating, roller application, blasting, and mechanical application.

The primer may form a layer coating the surface of the carrier 3 or the primer may coat only a part of the surface of the carrier 3. By adjusting the amount of primer, and by applying the primer on a portion of the carrier 3, certain properties of the print, such as smearing of ink, can be controlled, and the design of the print can be changed.

After applying the primer, the primer is dried in the heating device 30. Heat is applied to the surface of the carrier 3 configured to form the decor layer 6 so that the applied primer dries. Heat may be applied in the form of, for example, infrared (IR), near infrared (NIR), heated air, or a combination thereof. By drying the primer so that the aqueous portion of the primer evaporates, the risk of starting to smear the applied ink during printing is reduced.

If the primer is heated before it is applied to the surface of the carrier 3, the evaporation of water in the primer can take place at a faster rate.

The carrier 3 can also be heated before and/or after the primer is applied in order to accelerate evaporation of the water in the primer. Heating of the carrier 3 can be achieved by arranging the carrier 3 on a heated plate.

In one embodiment, an additional layer of primer is applied to the surface of the carrier 3. The primer can be dried between each application step.

After the primer has dried, the carrier 3 can be rolled on a roller for storage until it is printed, or it can enter the printing process.

In another embodiment shown in Figure 3B, the primer comprises a salt applied in solid form on the surface of the carrier. The salt is applied using an application device 20, preferably a scattering device. The salt is preferably at least one metal salt. The metal salt may be a monovalent metal salt, for example a monovalent metal salt comprising a monovalent ion such as Na ⁺ . The metal salt can be a polyvalent metal salt. Preferably, the polyvalent metal salt is a ^divalent ion such as Ca ^{2 +} , Cu ^{2 +} , Ni ^{2 +} , Mg ^{2 +} , Zn ^{2 +} , or Ba ^{2 +} , or a ^trivalent ion such as Al ^{3 +} or Fe ^{3 +} Includes. The metal salt can be, for example, sodium chloride or calcium chloride. The metal salt collides with the ink composition and precipitates the pigment of the ink composition.

The salt crystals forming the primer are preferably evenly distributed over the surface of the carrier 3. The salt crystals preferably form a uniform layer on the surface of the carrier 3.

The primer containing the salt in solid form can be bonded to the surface of the carrier 3 in several ways. In one embodiment, the carrier 3 is heated before and/or during application of the primer so that the salt binds to the carrier. In one embodiment, the carrier 3 is electrically charged such that the carrier attracts salt crystals of the primer. In one embodiment, a plasticizer is applied on the surface of the carrier 3 such that the salt crystals are bonded to the plasticized surface of the carrier 3. Alternatively, a solvent can be applied to the surface of the carrier 3. In one embodiment, the salt crystals are mechanically attached to the surface of the carrier 3, for example by making the surface of the carrier 3 porous.

It is also contemplated that a combined pre-treatment may be used. In an alternative embodiment, the pre-treatment comprises applying a corona, flame or plasma treatment on the first surface of the carrier 3 prior to printing. Corona, flame or plasma treatment increases the wetting capacity of the surface. Thereafter, any of the above-described types of primers are applied to the treated surface. The primer is subsequently dried before entering the printing process. As described above, the carrier 3 is rolled on a roller or enters a printing process.

In the embodiment shown in Figures 3a, 3b and 3c, the carrier 3 enters the printing process after the primer is applied. In the embodiment shown in Fig. 3A, the carrier 3 enters the printing process after drying the primer. In a similar printing process for both embodiments shown in FIGS. 3A and 3B, the print 6 by digital printing is pre-existing of the carrier 3 configured to form the decor layer 6 of the floor panel 1. It is printed on the treated surface.

The printer 40 is preferably an inkjet printer. Preferably, the printer 40 is a Drop on Demand (DOD) piezoelectric inkjet printer. Thermal DOD inkjet printers can also be used. The print 6 is applied in a non-contact manner.

The printer 40 includes at least one inkjet print head 45. Preferably, the printer 40 includes several inkjet print heads 45. CMYK colors or spot colors can be used. In case CMYK is used as the color system, at least four inkjet print heads 45 are required, one per color. In case a spot color is used, one print head 45 is required for each spot color. The number of spot colors and thereby the number of print heads 45 can vary. The printer 40 shown in Figs. 3A and 3B includes four print heads 45, which correspond to CMYK-color or four spot colors.

Preferably, a plurality of print heads 45 are arranged after extending perpendicular to the conveying direction of the carrier 3 through the printer in one row. Print heads arranged in the same row contain inks having the same color. The width of the row of print heads preferably corresponds to the width of the carrier 3 to which the print 6 is applied.

In the shown digital printer 40, the first, second, third and fourth rows 41, 42, 43, 44 of the print heads are arranged in sequence in the conveying direction D of the carrier. The first color is applied by the print head in the first row 41, the second color is applied by the print head in the second row 42, and the third color is applied to the print head in the third row 43. The fourth color is applied by the print head in the fourth row 44.

Alternatively, a printer 40 comprising print heads having different channels could be used. In this case, one print head can print one color or several colors. This allows more than one color to be printed by individual print heads provided with different channels. One channel is provided for each color. Thus, only one row of print heads can be provided in the printer.

The ink applied using the inkjet printer 40 described above is an aqueous pigment ink composition. Ink compositions include pigments that provide the ink with its specific color. Preferably, the aqueous ink composition is a heat activated curing ink. The ink composition may include a binder, water and a pigment. The binder can be, for example, a polymer or cellulose. The binder can be dispersed in the ink composition. Alternatively, the pigment is coated with a binder, preferably a polymer. Polymers can have carboxyl groups. The polymer may be a styrene, acrylic or methacrylic polymer or copolymer, or an unsaturated monomer, polyester, vinyl polymer or copolymer, aromatic and aliphatic polyurethane, or alkyd resin.

The decorative design printed on the carrier 3 configured to form the decor layer 6 can be both a natural design and a pattern such as a wood pattern or a stone pattern. The decorative design can also be an imaginary design or pattern.

The inkjet printer 40 prints a print 10 in the form of a decorative design on a primer applied on the surface of the carrier 3 configured to form the decor layer 6.

Heat is applied to the print so that the water in the aqueous pigment ink composition evaporates. The heating device 50 can be arranged after the digital printer 40, as can be seen by the transport direction D of the carrier. The heating device 50 may include infrared (IR) heating, near infrared (NIR) heating, heated air, or a combination thereof.

In case the printing takes place in an offline process, the carrier 3 can be rolled on a roller 8 for storage when the print 6 has dried. It is also contemplated that the printing is performed inline.

In one embodiment, the carrier 3 is printed on only one surface. In an alternative embodiment, the carrier 3 is printed on both surfaces. In such an embodiment, a primer as described above is applied to the first surface of the carrier 3, the first surface is printed, a primer as described above is applied to the second surface of the carrier 3, and a second The surface is printed. As an alternative, pre-treatment of both surfaces of the carrier 3 is carried out prior to printing on both surfaces of the carrier 3.

The carrier 3 for forming the decor layer 6 may be cut or punched to a size corresponding to the size of the floor panel 1. Further, a film or foil configured to form the protective layer 4 may be cut or punched to a size corresponding to the size of the floor panel 1. The protective layer 4 is a thermoplastic material, such as polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), polyethylene terephthalate (PET) , Polyacrylate, polyvinyl butyral, or combinations thereof. The core material configured to form the core 2 can also be cut or punched to a size corresponding to the size of the floor panel 1. The core may comprise polyvinyl chloride (PVC) or polypropylene (PP), or may be WPC. Alternatively, a decor layer and/or a protective layer are provided on the rollers to be bonded together in a continuous process.

As shown in FIG. 4, the printed carrier 3 is arranged on a core 2 comprising at least a layer of thermoplastic material to form a decor layer 6. The print 10 may face the core 2 or may not face the core 2. In case more than one carrier 3, 7 is provided, the carriers 3, 7 are arranged in layers to form the decor layer 6. The protective layer 4 is arranged on the printed carrier 3 forming the decor layer 6. The core 2, the printed carrier 3 configured to form the decor layer 6, and the protective layer 4 are pressed together to form the floor panel 1. The embossed press plate can be used to form the embossed surface of the floor panel 1. Heat and pressure can be used to press the layers together. The temperature may be 120 to 200 ℃. The pressure can be 5 to 10 bar. The carrier 3 provided with the print is bonded to the protective layer 4. The print is placed between the carrier 3 and the protective layer 4 to be bonded. The carrier 3 is also bonded to the core 2.

A coating 5, for example a radiation curing coating, preferably a UV curing coating, can be applied to the protective layer 4 after pressing. The coating 5 may comprise an acrylate oligomer, a methacrylate oligomer, or an unsaturated polyester.

The floor panel 1 can be further divided into a floor panel or a floorboard. Mechanical locking systems of the type described above can be formed on at least one edge of the floor panel. In one embodiment shown in FIG. 5, the printed carriers 3 are bonded to the protective layer 4 by pressing them together to form a decorative substrate 9. Heat and pressure can be used to press the layers together. The print is placed between the carrier 3 and the protective layer 4 to be bonded. The decorative substrate 9 can be bonded by pressing it to any type of core in a subsequent step, or it can be bonded by simultaneously bonding the printed carrier 3 to the protective layer 4.

The core may comprise a thermoplastic material, or a layer comprising at least a thermoplastic material, or may be a wood-based material.

The decorative substrate 9 comprising a printed carrier and a protective layer can be stored, for example on a roller, and then adhered to the core. The core may comprise a material other than a thermoplastic material.

The decorative substrate forms a printed thermoplastic laminate.

Several variations of the embodiments described herein are contemplated, which are within the scope of the invention as defined by the appended claims.

For example, it is contemplated that a panel as described above may be a floor panel as well as a building panel such as a panel, a ceiling panel, a wall panel, a furniture component, and the like.

It is also contemplated that the printing and primer application steps can be performed in an in-line process or in an off-line process.

It is contemplated that printing may be performed by rotogravure printing, screen printing, etc. as an alternative to digital printing.

It is also contemplated that drying of the primer may be excluded depending on the properties of the primer. When using certain classes of primers, it is possible to print as described above on primers that have not yet dried.

It is further contemplated that the layer may be arranged between the core and the carrier forming the decor layer. As an example, a layer with a uniform color can be arranged between the carrier and the core.

Example

Reference example

White PVC foil for LVT was printed directly with water based ink using a digital printer. The print was dried at 60° C. for 10 minutes. The printed foil was bonded to the transparent protective foil of PVC for LVT in a hot/cold-pressing step at 185° C. for 70 seconds at a pressure of approximately 6 bar, then cooled to 25° C. at a pressure of approximately 5 bar. The bonding between the printed PVC foil and the protective foil was good.

The resulting print shows poor quality due to the difference in surface tension between the ink and the LVT-foil. Ink droplets agglomerated into large ink droplets. The ink droplets started to smear each other.

Example One

The white PVC foil for LVT was treated with a primer containing 30 g/100 ml NaCl dissolved in deionized water, corresponding to 84% of the saturation point for NaCl in water. The foil was dried before further steps. The contact angle of the primer on the PVC foil was measured to be about 90°.

The foil treated with the primer was printed with water-based ink using a digital printer. The print was dried at 60° C. for 10 minutes. The printed foil was bonded to the transparent protective foil of PVC for LVT in a hot/cold-pressing step at 185° C. for 70 seconds at a pressure of approximately 6 bar, then cooled to 25° C. at a pressure of approximately 5 bar. The bonding between the printed PVC foil and the protective foil was good.

It was not possible to uniformly apply the primer over the surface of the foil due to the difference in surface tension between the primer and the LVT-foil. The printed image was not uniformly fixed due to poor application of the primer.

Example 2

The white PVC foil for LVT was treated with a primer containing 30 g/100 ml NaCl dissolved in deionized water, corresponding to 84% of the saturation point for NaCl in water. 2.0% by weight of BYK 345 as a wetting agent was added to the primer solution. The contact angle of the primer on the PVC foil was measured to be less than 40°. The foil was dried before further steps.

The foil treated with the primer was printed with water-based ink using a digital printer. The print was dried at 60° C. for 10 minutes. The printed foil was bonded to the transparent protective foil of PVC for LVT in a hot/cold-pressing step at 185° C. for 70 seconds at a pressure of approximately 6 bar, then cooled to 25° C. at a pressure of approximately 5 bar. The bonding between the printed PVC foil and the protective foil was good.

The primer was applied evenly over the surface on the LVT-foil. The printed images were not uniformly fixed due to insufficient NaCl concentration in the primer.

Example 3

The white PVC foil for LVT was treated with a primer containing 35 g/100 ml NaCl dissolved in deionized water, corresponding to 97% of the saturation point for NaCl in water. 2.0% by weight of BYK 345 as a wetting agent was added to the primer solution. The contact angle of the primer on the PVC foil was measured to be less than 40°. The foil was dried before further steps.

The foil treated with the primer was printed with water-based ink using a digital printer. The print was dried at 60° C. for 10 minutes. The printed foil was bonded to the transparent protective foil of PVC for LVT in a hot/cold-pressing step at 185° C. for 70 seconds at a pressure of approximately 6 bar, then cooled to 25° C. at a pressure of approximately 5 bar. The bonding between the printed PVC foil and the protective foil was good.

The primer was applied evenly over the surface on the LVT-foil. The printed image was fixed evenly over the surface of the foil, and a print result with good color intensity and resolution was achieved.

The amount of wetting agent applied in the above examples is adjusted according to the foil used and the surface tension of the foil in the examples, and may vary when using different substrates and/or different wetting agents.

The amount of salt applied in the above examples is adjusted according to the ink used in the examples, and may vary when different inks and/or different types of salts are used.

Claims (29)

As a method of producing building panels (1),
To provide a carrier (3) comprising a thermoplastic material,
Applying a primer containing a salt on the first surface of the carrier 3,
Printing a first print 10 with an aqueous pigment ink composition on the first surface of the carrier 3 using digital printing,
A protective layer 4 is applied on the first surface of the carrier 3 and the carrier 3 is applied on a core 2 comprising a thermoplastic material,
Applying heat and pressure to press the protective layer 4, the carrier 3 and the core 2 together to form the building panel 1,
A primer is applied on the first surface of the carrier 3 in the form of an aqueous solution containing the salt and a wetting agent, the wetting agent containing a nonionic silicone surfactant,
The method wherein the concentration of the salt in the aqueous primer solution is 90% or more of the concentration of the saturated salt in the aqueous primer solution. The method according to claim 1, wherein the building panel (1) is a floor panel. The method of claim 1, wherein the salt is a metal salt. delete delete The method according to claim 1, wherein the aqueous primer solution applied on the carrier (3) has a contact angle of less than 50° with the first surface of the carrier (3). The method of claim 1, wherein the aqueous primer solution is applied using digital printing. The method according to claim 1, further comprising drying the primer applied on the first surface of the carrier (3) prior to printing the first print (10). The method of claim 1, wherein the aqueous pigment ink composition is a heat activated curing ink. The method of claim 1, wherein the aqueous pigmented ink composition comprises a binder, water and pigment. 2. The method of claim 1, further comprising applying heat to the first print (10). The method of claim 1, wherein printing is performed by an inkjet printer. The method of claim 1, wherein the thermoplastic material of the carrier (3) is polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), polyethylene terephthalate ( PET), polyacrylate, or polyvinyl butyral. The method of claim 1, wherein the protective layer (4) is polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), polyethylene terephthalate (PET). , Polyacrylate, or polyvinyl butyral. As a method of forming a decorative substrate (9),
Providing a carrier 3 comprising a thermoplastic material,
Applying a primer containing a salt on the first surface of the carrier 3,
Printing a first print 10 with an aqueous pigment ink composition on the first surface of the carrier 3,
Applying a protective layer 4 comprising a thermoplastic material on the first surface of the carrier 3,
And applying heat and pressure to press the protective layer 4 and the carrier 3 together to form a decorative substrate 9,
A primer is applied on the first surface of the carrier 3 in the form of an aqueous solution containing the salt and a wetting agent, the wetting agent containing a nonionic silicone surfactant,
The method wherein the concentration of the salt in the aqueous primer solution is 90% or more of the concentration of the saturated salt in the aqueous primer solution. 16. The method according to claim 15, wherein the first print (10) is printed by digital printing. 16. The method of claim 15, wherein the salt is a metal salt. delete delete delete 16. The method according to claim 15, wherein the aqueous primer solution applied on the carrier (3) has a contact angle of less than 50° with the first surface of the carrier (3). The method of claim 15, wherein the aqueous primer solution is applied using digital printing. 16. The method according to claim 15, further comprising drying the primer applied on the first surface of the carrier (3) prior to printing the first print (10). 16. The method of claim 15, wherein the aqueous pigment ink composition is a heat activated curing ink. 16. The method of claim 15, wherein the aqueous pigmented ink composition comprises a binder, water and pigment. 16. The method of claim 15, further comprising applying heat to the first print (10). 16. The method of claim 15, wherein printing is performed by an inkjet printer. The method of claim 15, wherein the thermoplastic material of the carrier (3) is polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), polyethylene terephthalate ( PET), polyacrylate, or polyvinyl butyral. 16. The method of claim 15, wherein the thermoplastic material of the protective layer (4) is polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), or polyethylene tere. Phthalate (PET), polyacrylate, or polyvinyl butyral.

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