Method for producing a ceramic tile with an iridescent effect and resulting ceramic tile according to the method

Abstract

The present invention relates to a ceramic tile with an iridescent effect and a method for producing iridescent effects on ceramic tiles subjected to a firing cycle at a maximum temperature of between 850°C and 1250°C.

Description

[0001] METHOD FOR PRODUCING A CERAMIC TILE WITH IRIDESCENT EFFECT AND RESULTING CERAMIC TILE ACCORDING TO THE METHOD

[0002] DESCRIPTION

[0003] The present invention relates to a ceramic tile with an iridescent effect and a method for producing ceramic tiles with an iridescent effect after being subjected to a firing cycle at a maximum temperature of between 850 °C and 1250 °C.

[0004] STATE OF THE ART

[0005] The ceramics sector is currently immersed in the development and application of technologies, processes, and products that provide a wide variety of aesthetic effects to ceramic tiles. Such is the case of effects that take advantage of the interaction with light. In this regard, the state of the art is widely known for the existence of ceramic tile manufacturing processes with effects based on light reflection. Patent application CN11184822A1 describes a production process for a ceramic tile with a metallic luster, comprising: preparing dry metal particles, depositing a dry granular glaze containing the metal particles on the ceramic tile, applying a protective glaze, firing the piece, and finally, polishing it, obtaining a metallic luster effect.In this case, the metallic particles responsible for the metallic luster effect are Fe2O3, SnO2, NiO, and Cr2O3, which, when combined with B2O3, generate crystals of different colors. However, application CN11184822A1 presents several limitations. First, the effect achieved is not iridescent through the presence of discrete particles that cause iridescence, but rather a metallic luster effect (metallic mirror) over the entire surface. In other words, it is a ceramic tile with a mirror-like surface with non-localized iridescence. Another limitation is that application must be dry and direct to the ceramic tile; that is, it cannot be applied wet in the form of a suspension, and it is not possible to take advantage of combining the desired effect on previously glazed surfaces that provide gloss, matte, etc. effects.This limits the aesthetic possibilities of the resulting ceramic tile. A third limitation is that it does not use frit in the dry granular glaze. This requires the application of a protective glaze that binds the particles together and acts as a base for subsequent polishing. Finally, it is also worth noting that the particles that provide a luster effect are characterized by color (red FeO, white SnO, black NiO, and green CrO), again limiting the aesthetic possibilities of ceramic tiles as it prevents the application of additional decoration. All this without forgetting the toxicity of oxides such as NiO and CrO.

[0006] For its part, patent application CN106518029A1 discloses the preparation of a ceramic tile with a metallic luster effect and relief textures. The method described consists of preparing a spray-dried and pressing ceramic tile support, depositing a base glaze using a bell, applying a metallic luster effect glaze suspension using screen printing, printing a marble design using inkjet on the areas where the metallic luster effect glaze has been deposited, printing a relief effect glaze using inkjet on the areas where the metallic luster effect glaze has been deposited, applying a transparent glaze using a bell and finally, firing the ceramic tile. Likewise, patent application CN106518029A1 describes a glaze composition with a metallic luster effect consisting of a mixture of bentonite, calcite, kaolin, zinc oxide, cerium oxide and praseodymium oxide.However, application CN106518029A1 presents several limitations. First, achieving the metallic luster effect requires the presence of a base glaze on which to deposit the metallic luster glaze. A second limitation is that the metallic luster effect is achieved only through the combination of the aforementioned raw materials, which limits the aesthetic possibilities of ceramic tiles. This is because the effect is the result of generating crystallizations during the firing cycle, the precursors of which are the raw materials described.

[0007] The present invention solves the limitations of the state of the art described above by means of a method for producing a ceramic tile with an iridescent effect and a resulting ceramic tile according to the method.

[0008] EXPLANATION OF THE INVENTION

[0009] Throughout the invention and the claims, the word "comprises" and its variants are not intended to exclude other technical features, additives, components, or steps. Furthermore, the word "comprises" includes the word "consists of." For those skilled in the art, other objects, advantages, and features of the invention will be apparent partly from the description and partly from the practice of the invention.

[0010] This invention makes it possible to overcome the limitations of the state of the art by means of a method comprising the combination of the following technical aspects: the presence of iridescent particles with a refractive index between 1.5 and 2.7, the presence, together with the iridescent particles, of frit particles which, during heat treatment, act as a binder for the iridescent particles, and the selection of the grammage of frit deposited and the thermal properties of said frit, specifically the softening temperature and the half-sphere temperature. All of this makes it possible to obtain, after heat treatment, a ceramic tile with an iridescent effect.

[0011] In accordance with the above description, the present invention has as its first object a method for producing a ceramic tile with an iridescent effect comprising: a. Supplying an unglazed or glazed ceramic tile. b. Depositing on the unglazed or glazed ceramic tile: i. Iridescent particles, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2 , where the iridescent particles have a refractive index between 1.5 and 2.7 and a particle diameter between 75 micrometres and 600 micrometres. ii. Frit particles, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2, where the frit particles have a diameter between 100 micrometres and 600 micrometres, a softening temperature between 840 °C and 1180 °C and a half-sphere temperature between 870 °C and 1235 °C. c. Introduce the ceramic tile resulting from the previous stages into an oven and carry out a heat treatment at a maximum temperature between 850 °C and 1250 °C, resulting in a fired ceramic tile with an iridescent effect

[0012] Both iridescent particles and frit particles are deposited by powder deposition station and / or inkjet and / or airbrushing and / or die and / or bell and / or disc and / or screen printing and / or roller and / or digital dry decoration.

[0013] Advantageously, the iridescent particles and frit particles are deposited by means of a powder deposition station and the method for producing a ceramic tile with an iridescent effect comprises: a. Supplying an unglazed or glazed ceramic tile. b. Depositing on the unglazed or glazed ceramic tile: i. Iridescent particles, by means of a powder deposition station, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2 , where the iridescent particles have a refractive index between 1.5 and 2.7 and a particle diameter between 75 micrometres and 600 micrometres. ii. Frit particles, by means of a powder deposition station, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2, where the frit particles have a diameter between 100 micrometres and 600 micrometres, a softening temperature between 840 °C and 1180 °C and a half-sphere temperature between 870 °C and 1235 °C. c. Introduce the ceramic tile resulting from the previous stages into a kiln and carry out a heat treatment at a maximum temperature between 850 °C and 1250 °C, resulting in a fired ceramic tile with an iridescent effect.

[0014] The term “predefined design,” as used herein, refers to a printing or deposition pattern that defines the area where the iridescent particles, frit particles, glaze, or ink referred to herein are to be printed or deposited. This pattern may cover a percentage of the ceramic tile surface or 100% of the ceramic tile surface.

[0015] An advantage of the present invention is that it allows the ceramic tile supplied at the beginning of the method to be unglazed or glazed, since in both cases the desired iridescent effect is obtained. The difference is appreciated in the effect of the surface on which the iridescent particles are deposited. In the case of unglazed ceramic tiles, the iridescent effect is obtained on a surface that displays the color of the support. For example, if a ceramic tile is used that is formulated with raw materials that provide a white support, the ceramic tile resulting from applying the method according to the present invention is a fired ceramic tile with an iridescent effect on the white background of the ceramic tile.If, alternatively, the ceramic tile is glazed, the ceramic tile resulting from applying the method according to the present invention is a fired ceramic tile with an iridescent effect on a background with an effect resulting from the composition of the previously deposited ceramic glaze. Examples of effects of the previously deposited ceramic glaze, by way of example but not limited to, are transparent gloss, opaque gloss, opaque matte, transparent matte, satin matte, white, luster, metallic, among others. Furthermore, this ceramic glaze previously deposited on the ceramic tile comprises both a single layer of ceramic glaze and several layers resulting from the combination of various types of ceramic glaze.

[0016] The iridescent effect in the present invention requires the selection of particles, called iridescent particles, which are characterized by having a refractive index between 1.5 and 2.7 and a particle size between 75 micrometers and 600 micrometers. Thus, the iridescent particles are selected from the group comprising, but not limited to, tungsten (III) oxide, sillimanite, manganese dioxide, cordierite, sodium feldspar, potassium feldspar, corundum, mullite, wollastonite, zirconium silicate, tin dioxide, zirconium (IV) oxide, kyanite, micas, rutile, anatase, grit and quartz, or a mixture thereof. The term "grit" as used herein refers to a frit that has been ground and sieved to fit within a certain particle diameter range.

[0017] Since the combination of iridescent particles and frit particles is necessary, in a preferred embodiment, the present invention contemplates the option of both types of particles being deposited on the unglazed or glazed ceramic tile, from a mixture thereof, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2 This mixture comprises iridescent particles between 1% and 50% by weight of the total mixture and frit particles between 50% and 99% by weight of the total mixture. The iridescent effect is more or less intense depending on the quantity of iridescent particles deposited. Furthermore, the fact that it starts from a mixture allows both types of particles to be deposited in a single step and with a single deposition equipment.

[0018] In any case, the method according to the present invention makes it possible to obtain the iridescent effect on the ceramic tile regardless of the deposition technique for the different components. Thus, both the iridescent particles and the frit particles or the mixture comprising iridescent particles and frit particles can be deposited, as mentioned above, in addition to using a powder deposition station, by inkjet, airbrushing, die-casting, bell-shaped, disc, screen printing, roller, or digital dry decoration.

[0019] Likewise, the present invention also contemplates the possibility that the iridescent particles and / or the frit particles are deposited in a ceramic glaze by means of a glazing station, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2The glazing station can be applied using various techniques, such as inkjet, airbrushing, die-casting, bell-shaped, disc, screen printing, or roller. This option offers the possibility of simultaneously achieving iridescent effects on glazed or unglazed ceramic tiles, as well as other effects provided by the other components of the ceramic glaze. Examples of ceramic glaze effects containing iridescent particles and / or frit particles, including but not limited to, include transparent gloss, opaque gloss, opaque matte, transparent matte, satin matte, opaque white, luster, metallic, and colored, among others.

[0020] Another option to add aesthetic value to ceramic tiles is by decorating the unglazed or glazed ceramic tiles with at least one decorative ink that provides chromatic effects (cyan, cobalt blue, brown, red, magenta, yellow, green, black, opaque white, grey, etc.) or ceramic effects (transparent gloss, opaque gloss, opaque matte, transparent matte, satin matte, opaque white, metallic, lustre, etc.).In this sense, the present invention contemplates a preferred embodiment where, prior to the step of depositing the iridescent particles and / or prior to the step of depositing the frit particles and / or prior to the step of depositing the mixture comprising the iridescent particles and the frit particles and / or prior to the step of depositing the ceramic glaze, at least one decorative ink is printed, by means of an inkjet or airbrush printing station or die or bell or disc or screen printing or roller, with a predefined design and a weight between 10 g / m. 2 and 1000 g / m 2 .

[0021] Advantageously, the thickness of the frit layer that totally or partially covers the iridescent particles, at least in one of the Cartesian planes along the X, Y or Z axes, must be between 50 micrometres and 1000 micrometres.

[0022] In those cases where the deposition of the particles is carried out dry, that is, without the use of a suspension of the particles in a liquid medium, it is possible in the present invention to use an adhesive ink that helps to fix the particles on the surface of the ceramic tile. Thus, a preferred embodiment is characterized in that prior to the step of depositing the iridescent particles and / or prior to the step of depositing the frit particles and / or prior to the step of depositing the mixture of the iridescent particles and the frit particles, an ink with adhesive properties is printed by means of an inkjet or airbrush printing station or die or bell or disc or screen printing or roller, with a predefined design and a weight between 20 g / m 2 and 250 g / m 2. Additionally, after the step of fixing the particles with adhesive ink, that is, after depositing the ink with adhesive properties and the iridescent particles and / or the frit particles and / or the mixture comprising the iridescent particles and the frit particles, there is the option of redepositing the ink with adhesive properties by means of an inkjet or airbrush printing station or die or bell or disc or screen printing or roller, with a predefined design and a weight between 20 g / m 2 and 250 g / m 2This adhesive ink printing station can be either the same one used previously or an additional printing station. This allows for greater particle fixation power in cases where, for various reasons, there is a risk that the ceramic tile, prior to heat treatment, may be subjected to sudden movements that could displace the deposited particles according to the predefined design. It should be noted that currently, this entire process described can also be carried out using digital dry decoration equipment where both the printing of the adhesive ink, using inkjet technology, and the deposition of the particles are performed in a single unit. As a possible complementary step to all the previous ones, the present invention also includes the option of removing excess or non-adhering particles from the adhesive ink using a suction or blowing device, after each deposition stage.

[0023] As indicated above, the present invention includes a heat treatment at a temperature between 850°C and 1250°C. The temperature selection will be determined by the type of frits and glazes used. In this regard, this heat treatment can be performed in a natural gas firing kiln commonly used in the ceramic tile industry.

[0024] According to the above, during the heat treatment the frit particles melt and surround the iridescent particles, such that once said heat treatment is completed, a surface is obtained that totally or partially covers the ceramic tile, where the iridescent particles are embedded in the matrix comprising the frit resulting from said heat treatment. If the frit particles have been applied in the form of ceramic glaze, the surface where the iridescent particles are embedded is the result of the heat treatment of said ceramic glaze, that is, of the frit particles and other components of a vitreous or crystalline nature that said ceramic glaze may comprise.Thus, the technical result in either case is that each of the iridescent particles is totally or partially surrounded in the Cartesian planes along the X and / or Y and / or Z axes by a layer comprising the frit particles, the thickness of which is between 50 micrometres and 1000 micrometres. Additionally, said thickness can also be adjusted by means of a polishing stage following heat treatment, using a polishing station. In this sense, the polishing stage is a technique widely used in the ceramic tile sector to achieve different objectives such as reducing the thickness of the most superficial layer, reducing its roughness, generating surfaces with greater shine and specular reflection, among others.

[0025] Taking into account all that has been described above, the second object of the present invention is a ceramic tile with an iridescent effect according to the method described. In particular, a ceramic tile in which each of the iridescent particles is totally or partially surrounded by a layer of frit such that the thickness (E) of said layer of frit is between 50 micrometers and 1000 micrometers, in the Cartesian planes along the X and / or Y and / or Z axes.

[0026] Finally, it should be noted that the method for producing a ceramic tile with an iridescent effect according to the present invention does not limit the inclusion or incorporation of other processes or steps that provide additional aesthetic, technical or functional properties to those protected in this invention, both before and after heat treatment.

[0027] Other features of the present invention are derived from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures and / or described in the preferred embodiments, are usable not only in the combination indicated in each case, but also in other combinations, without leaving the scope of the invention. Therefore, it is to be understood that those embodiments of the invention are also encompassed and disclosed by the invention, which are not explicitly shown in the figures or explained, but which can be extracted through combinations of features separate from the embodiments described and which can be generated from them.Therefore, those embodiments and combinations of features that do not have all the features of an originally formulated independent claim will also be considered disclosed.

[0028] Where technical features recited in any claim are followed by reference symbols, such reference symbols have been included for the sole purpose of enhancing the intelligibility of the claims and accordingly, these reference signs have no limiting effect on the interpretation of each element identified by way of example by these reference signs.

[0029] DESCRIPTION OF FIGURES In the figures, the same elements or those with the same function are accompanied by the same reference symbols.

[0030] FIG. 1 schematically represents the method for producing a ceramic tile with an iridescent effect according to the invention. The method follows the direction indicated by the arrow, i.e., from left to right, beginning with the supply of the unglazed ceramic tile 2 or glazed tile 2e. Said ceramic tile 2 / 2e then passes to the powder deposition station 4 where the iridescent particles 3 are deposited in a predefined design and with a weight of between 10 g / m 2 and 2500 g / m 2 The ceramic tile then passes to a powder deposition station 6 where frit particles 5 are deposited, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2The method concludes with the ceramic tile entering a kiln 7, where it undergoes heat treatment at a maximum temperature of between 850°C and 1250°C. Once the heat treatment is complete, a fired ceramic tile 2a with an iridescent effect is obtained, resulting from the method according to the invention.

[0031] FIG. 2 schematically represents the method for producing a ceramic tile with an iridescent effect, which includes, in addition to the method shown in FIG. 1, a printing station 11 for printing at least one decorative ink, according to the invention. Thus, the method follows the direction indicated by the arrow, that is, from left to right, starting with the supply of the unglazed ceramic tile 2 or glazed 2e. Said ceramic tile 2 / 2e then passes to the inkjet or airbrush or die or bell or disc or screen printing or roller printing station 11, where at least one decorative ink 10 is printed, with a predefined design and a weight between 10 g / m 2 and 1000 g / m 2 . Subsequently, the ceramic tile 2 / 2e passes to the powder deposition station 4 where the iridescent particles 3 are deposited with a predefined design and a weight between 10 g / m 2 and 2500 g / m2 The ceramic tile then passes to a powder deposition station 6 where frit particles 5 are deposited, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2. The method ends with the ceramic tile entering a kiln 7 where it undergoes heat treatment at a maximum temperature of between 850 °C and 1250 °C. Once the heat treatment is complete, a fired ceramic tile 2a with an iridescent effect combined with decoration is obtained, resulting from the method according to the invention. FIG. 3 schematically represents the method for producing a ceramic tile with an iridescent effect, which includes, in addition to the method shown in FIG. 1, a printing station 13 for printing an ink with adhesive properties, according to the invention. Thus, the method follows the direction indicated by the arrow, that is, from left to right, starting with the supply of the unglazed ceramic tile 2 or glazed 2e.Then, said ceramic tile 2 / 2e passes to the printing station 13, where an ink with adhesive properties 12 is printed by means of an inkjet or airbrush or die or bell or disc or screen printing or roller printing station, with a predefined design and a weight between 20 g / m. 2 and 250 g / m 2 The ceramic tile then passes to the powder deposition station 4 where iridescent particles 3 are deposited with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2 . Subsequently, the ceramic tile passes to a powder deposition station 6 where the frit particles 5 are deposited, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2The method concludes with the ceramic tile entering a kiln 7, where it undergoes heat treatment at a maximum temperature of between 850°C and 1250°C. Once the heat treatment is complete, a fired ceramic tile 2a with an iridescent effect is obtained, resulting from the method according to the invention.

[0032] FIG. 4 schematically represents the method for producing a ceramic tile with an iridescent effect, which includes, in addition to the method shown in FIG. 1, a polishing station 14, according to the invention. Thus, the method follows the direction indicated by the arrow, that is, from left to right, starting with the supply of the unglazed ceramic tile 2 or glazed 2e. Said ceramic tile 2 / 2e then passes to the powder deposition station 4 where the iridescent particles 3 are deposited with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2The ceramic tile then passes to a powder deposition station 6 where frit particles 5 are deposited, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2. Subsequently, the ceramic tile enters a kiln 7 where it undergoes heat treatment at a maximum temperature of between 850 °C and 1250 °C. The method ends with the ceramic tile entering a surface polishing station 14. Once the polishing is complete, a fired ceramic tile 2a with an iridescent effect is obtained, resulting from the method according to the invention. FIG. 5 schematically represents the method for producing a ceramic tile with an iridescent effect, which includes, in addition to the method shown in FIG. 1, a printing station 11 for printing at least one decorative ink, a printing station 13 for printing an ink with adhesive properties, as well as the deposition of a mixture comprising iridescent particles 3 and frit particles 5, according to the invention.Thus, the method follows the direction indicated by the arrow, that is, from left to right, starting with the supply of the unglazed ceramic tile 2 or glazed 2e. Then said ceramic tile 2 / 2e passes to the printing station 11 of inkjet or airbrushing or die or bell or disc or screen printing or roller, where at least one decorative ink 10 is printed, with a predefined design and a weight between 10 g / m. 2 and 1000 g / m 2 . Subsequently, the ceramic tile passes to the printing station 13, where an ink with adhesive properties 12 is printed by means of an inkjet or airbrush or die or bell or disc or screen printing or roller printing station, with a predefined design and a weight between 20 g / m 2 and 250 g / m 2The ceramic tile then passes to the powder deposition station 4 where the mixture comprising iridescent particles 3 and frit particles 5 is deposited, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2 . The ceramic tile then passes to the printing station 13, where an ink with adhesive properties 12 is printed using an inkjet or airbrush or die or bell or disc or screen printing or roller printing station, with a predefined design and a weight between 20 g / m 2 and 250 g / m 2 The method concludes with the ceramic tile entering a kiln 7, where it undergoes heat treatment at a maximum temperature of between 850°C and 1250°C. Once the heat treatment is complete, a fired ceramic tile 2a with an iridescent effect is obtained, resulting from the method according to the invention.

[0033] FIG. 6 schematically represents the method for producing a ceramic tile with an iridescent effect, which includes, in addition to the method shown in FIG. 1, a printing station 11 for printing at least one decorative ink, a printing station 13 for printing an ink with adhesive properties, the deposition of a mixture comprising iridescent particles 3 and frit particles 5, and a final step of polishing the surface 14, according to the invention. Thus, the method follows the direction indicated by the arrow, that is, from left to right, starting with the supply of the unglazed ceramic tile 2 or glazed 2e. Said ceramic tile 2 / 2e then passes to the inkjet or airbrush or die or bell or disc or screen printing or roller printing station 11, where at least one decorative ink 10 is printed, with a predefined design and a weight between 10 g / m 2 and 1000 g / m 2. Subsequently, the ceramic tile passes to the printing station 13, where an ink with adhesive properties 12 is printed by means of an inkjet or airbrush or die or bell or disc or screen printing or roller printing station, with a predefined design and a weight between 20 g / m 2 and 250 g / m 2 The ceramic tile then passes to the powder deposition station 4 where the mixture comprising iridescent particles 3 and frit particles 5 is deposited, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2 . The ceramic tile then passes to the printing station 13, where an ink with adhesive properties 12 is printed using an inkjet or airbrush or die or bell or disc or screen printing or roller printing station, with a predefined design and a weight between 20 g / m 2 and 250 g / m 2. Subsequently, the ceramic tile enters a kiln 7 where it undergoes heat treatment at a maximum temperature of between 850 °C and 1250 °C. The method ends with the ceramic tile entering a surface polishing station 14. Once the polishing process is complete, a fired ceramic tile 2a with an iridescent effect is obtained, resulting from the method according to the invention.

[0034] FIG. 7 schematically represents the method for producing a ceramic tile with an iridescent effect, which includes, in addition to the method shown in FIG. 1, a printing station 11 for printing at least one decorative ink, and the powder deposition station 4 is replaced by a glazing station 9 for deposition of a ceramic glaze comprising at least the iridescent particles and the frit particles, according to the invention. Thus, the method follows the direction indicated by the arrow, that is, from left to right, starting with the supply of the unglazed ceramic tile 2 or glazed 2e. Next, said ceramic tile 2 / 2e passes to the inkjet or airbrush or die or bell or disc or screen printing or roller printing station 11, where at least one decorative ink 10 is printed, with a predefined design and a weight between 10 g / m 2 and 1000 g / m 2. Subsequently, the ceramic tile 2 / 2e passes to the glazing station 9 of inkjet or airbrushing or die or bell or disc or screen printing or roller, where a ceramic glaze is deposited comprising at least the iridescent particles 3 and the frit particles 5, with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2 The method concludes with the ceramic tile entering a kiln 7, where it undergoes heat treatment at a maximum temperature of between 850°C and 1250°C. Once the heat treatment is complete, a fired ceramic tile 2a with an iridescent effect is obtained, resulting from the method according to the invention.

[0035] Fig. 8 schematically represents the section of a ceramic tile with an iridescent effect once it has been subjected to heat treatment 2a, where a deposition design of iridescent particles 3 on the XY plane of the unglazed 2 or glazed 2e ceramic tile is shown, and a design of frit particles 5 resulting from the heat treatment, such that they totally or partially envelop the iridescent particles 3 with a thickness E comprised between 50 micrometers and 1000 micrometers in the Cartesian planes along the X and / or Y and / or Z axes, according to the invention. Additionally, the thickness E can be adjusted by means of a polishing process after the heat treatment, according to the invention.

[0036] Fig. 9 schematically represents the section of a ceramic tile with an iridescent effect once subjected to heat treatment 2a, where a decorative ink printing design 10 is shown on the XY plane of the unglazed 2 or glazed 2e ceramic tile, an iridescent particle deposition design 3 in the same plane and a frit particle design 5 resulting from the heat treatment, such that they totally or partially envelop the iridescent particles 3 with a thickness E comprised between 50 micrometers and 1000 micrometers in the Cartesian planes along the X and / or Y and / or Z axes, according to the invention. Additionally, the thickness E can be adjusted by a polishing process after the heat treatment, according to the invention.

[0037] Fig. 10 schematically represents the iridescent effect ceramic tile once subjected to heat treatment 2a, where a decorative ink printing design 10 is shown on the XY plane of the unglazed 2 or glazed 2e ceramic tile and a ceramic glaze deposition design 8 in the same plane comprising the iridescent particles and the frit particles resulting from the heat treatment. Thus, as a result of the heat treatment, the frit particles 5 totally or partially envelop the iridescent particles 3 with a thickness E comprised between 50 micrometers and 1000 micrometers, in the Cartesian planes along the X and / or Y and / or Z axes, according to the invention. Additionally, the thickness E can be adjusted by a polishing process after the heat treatment, according to the invention.

[0038] PREFERRED EMBODIMENTS The present invention is explained in more detail by means of preferred embodiments. The following examples are provided for illustrative purposes and are not intended to be limiting of the present invention. In addition, the present invention covers all possible combinations of particular and preferred embodiments indicated herein.

[0039] Example 1.

[0040] A ceramic tile with an iridescent effect according to the invention was prepared by following the steps below: a. Supplying an unglazed porcelain ceramic tile 2 formulated with raw materials that provide a white support. b. Depositing iridescent corundum particles 3 on the ceramic tile 2 using a powder deposition station 4, with a predefined design and a weight of 200 g / m 2, where the corundum particles have a refractive index between 1.76 and 1.78 and a particle size between 75 micrometres and 600 micrometres. c. Depositing a frit 5 on the ceramic tile 2 using a powder deposition station 6, with a predefined design and a grammage of 2200 g / m 2 , where the frit particles have a particle size between 200 micrometres and 500 micrometres, a softening temperature of 1068 °C and a half-sphere temperature of 1138 °C. d. Introduce the ceramic tile 2 into a kiln 7 and carry out a heat treatment at a maximum temperature of 1230 °C. e. Introduce the ceramic tile resulting from the heat treatment into a polishing station 14 and carry out the polishing.

[0041] As a result of this process, a fired ceramic tile with an iridescent effect (2a) according to the invention was obtained.

[0042] Example 2.

[0043] A ceramic tile with an iridescent effect according to the invention was prepared, the following steps being followed: a. Supplying a porcelain ceramic tile comprising an engobe-type glaze 2e. b. Printing a predefined design comprising decorative inks 10 in blue, brown, yellow, black and with a gloss effect on the ceramic tile 2e, using an inkjet printing station 11 and a weight of 30 g / m 2 . c. Printing a predefined design on the ceramic tile with an ink with adhesive properties 12, using an inkjet printing station 13 and a grammage of 100 g / m 2. d. Depositing on the ceramic tile a mixture comprising 10% by weight of the total mixture, of iridescent cordierite particles, characterized by having a refractive index between 1.55 and 1.60, a particle size between 100 micrometers and 450 micrometers; and 90% by weight of the total mixture, of a frit characterized by having a particle size between 200 micrometers and 500 micrometers, a softening temperature of 1090 ° C and a half-sphere temperature of 1145 ° C. Said mixture was deposited by means of a powder station 4 with a predefined design and a weight of 500 g / m 2 . e. Depositing an ink with adhesive properties 12 on the ceramic tile, using an airbrush printing station 13, with a predefined design and a weight of 100 g / m 2. f. Place the ceramic tile in a kiln 7 and heat treat it at a maximum temperature of 1200 °C. g. Place the ceramic tile resulting from the heat treatment in a polishing station 14 and polish it.

[0044] As a result of this process, a fired ceramic tile with an iridescent effect (2a) according to the invention was obtained.

[0045] Example 3.

[0046] A ceramic tile with an iridescent effect according to the invention was prepared, where the following steps were followed: a. Supplying a porous ceramic tile comprising an engobe-type glaze 2e. b. Depositing iridescent particles 3 of grit onto the ceramic tile 2e by means of a powder deposition station 4, with a predefined design and a weight of 300 g / m 2, where the grit particles have a refractive index between 1.5 and 2.7 and a particle size between 100 micrometres and 300 micrometres. c. Depositing a frit 5 on the ceramic tile 2e using a powder deposition station 6, with a predefined design and a weight of 500 g / m 2 , where the frit particles have a particle size between 250 micrometres and 400 micrometres, a softening temperature of 990 °C and a half-sphere temperature of 1150 °C. d. Place the ceramic tile in a kiln 7 and carry out a heat treatment at a maximum temperature of 1140 °C.

[0047] As a result of this process, a fired ceramic tile with an iridescent effect (2a) according to the invention was obtained.

[0048] Example 4.

[0049] A ceramic tile with an iridescent effect according to the invention was prepared, the following steps being followed: a. Supplying a porcelain ceramic tile comprising an engobe-type glaze 2e. b. Printing a predefined design comprising decorative inks 10 in cobalt, brown, yellow, black and transparent matte effect on the ceramic tile 2e, using an inkjet printing station 11 and a weight of 150 g / m 2. c. Depositing on the ceramic tile 2e a ceramic glaze with a transparent gloss effect comprising a mixture comprising 50% by weight of the total mixture, of iridescent quartz particles 3, characterized by having a refractive index between 1.50 and 1.55, a particle size between 75 micrometers and 300 micrometers; and 50% by weight of the total mixture, of a frit 5 characterized by having a particle size between 150 micrometers and 300 micrometers, a softening temperature of 1150 ° C and a half-sphere temperature of 1160 ° C. Said mixture was deposited by means of an airbrush glazing station 9, with a predefined design and a weight of 800 g / m 2 . d. Place the ceramic tile in a kiln 7 and heat treat it at a maximum temperature of 1200 °C.

[0050] As a result of this process, a fired ceramic tile with an iridescent effect (2a) according to the invention was obtained.

[0051] Example 5. A ceramic tile with an iridescent effect according to the invention was prepared, where the following steps were followed: a. Supply a glazed, decorated and fired ceramic tile 2e. b. Print an ink with adhesive properties 12 on the ceramic tile, using a roller printing station 13, with a predefined design and a weight of 100 g / m 2. c. Depositing on the ceramic tile a mixture comprising 5% by weight of the total mixture, of iridescent mica particles 3, characterized by having a refractive index between 1.5 and 2.7, a particle size between 40 micrometers and 100 micrometers; and 95% by weight of the total mixture, of a frit 5, characterized by having a particle size between 150 micrometers and 300 micrometers, a softening temperature of 846 ° C and a half-sphere temperature of 875 ° C. Said mixture was deposited by means of a powder deposition station 4, with a predefined design and a weight of 500 g / m 2 . d. Place the ceramic tile in a kiln 7 and heat treat it at a maximum temperature of 850 °C.

[0052] As a result of this process, a fired ceramic tile with an iridescent effect (2a) according to the invention was obtained.

[0053] Example 6.

[0054] A ceramic tile with an iridescent effect according to the invention was prepared, with the following steps: a. Supplying a porcelain ceramic tile glazed with a transparent gloss glaze of black color 2e. b. Printing on the ceramic tile 2e a predefined design comprising decorative inks 10 of cobalt, brown, yellow and opaque white, using an inkjet printing station 11 and a grammage of 75 g / m 2. c. Depositing on the ceramic tile a mixture comprising 30% by weight of the total mixture, of iridescent particles 3 comprising in turn 80% of quartz particles, characterized by having a refractive index between 1.50 and 1.55 and 20% of tungsten (III) oxide particles, characterized by having a refractive index between 1.92 and 1.99. This mixture of quartz particles and tungsten (III) oxide has a particle size between 100 micrometers and 300 micrometers. The other 70% by weight of the total mixture is a frit, characterized by having a particle size between 1 micrometer and 50 micrometers, a softening temperature of 1142 ° C and a half-sphere temperature of 1153 ° C. This mixture was deposited using a 9-row glazing station with a predefined design and a grammage of 1200 g / m 2. d. Place the ceramic tile in a kiln 7 and heat treat it at a maximum temperature of 1200 °C. e. Place the ceramic tile resulting from the heat treatment in a polishing station 14 and polish it. This process resulted in a fired ceramic tile with an iridescent effect (2a) according to the invention.

Claims

CLAIMS 1. A method for producing a ceramic tile with an iridescent effect comprising at least the following steps: a. Supplying an unglazed (2) or glazed (2e) ceramic tile. b. Depositing on the unglazed (2) or glazed (2e) ceramic tile: i. Iridescent particles (3), with a predefined design and a weight of between 10 g / m 2 and 2500 g / m 2 , where the iridescent particles have a refractive index between 1.5 and 2.7 and a particle diameter between 75 micrometres and 600 micrometres. ii. Frit particles (5), with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2, where the frit particles have a diameter between 100 micrometres and 600 micrometres, a softening temperature between 840 °C and 1180 °C and a half-sphere temperature between 870 °C and 1235 °C. c. Introduce the ceramic tile resulting from the previous stages into an oven (7) and carry out a heat treatment at a maximum temperature between 850 °C and 1250 °C, resulting in a fired ceramic tile with an iridescent effect (2a).

2. The method according to claim 1, wherein both the iridescent particles (3) and the frit particles (5) are deposited by means of a powder deposition station and / or ink injection and / or airbrushing and / or die and / or bell and / or disc and / or screen printing and / or roller and / or dry digital decoration.

3. The method according to any of the preceding claims, wherein the iridescent particles (3) and the frit particles (5) are deposited by means of a powder deposition station according to the following steps: a. Supplying an unglazed (2) or glazed (2e) ceramic tile. b. Depositing on the unglazed (2) or glazed (2e) ceramic tile: i. Iridescent particles (3), by means of a powder deposition station (4) with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2 , where the iridescent particles have a refractive index between 1.5 and 2.7 and a diameter of particle size between 75 micrometres and 600 micrometres. ii. Frit particles (5), by means of a powder deposition station (6), with a predefined design and a weight between 10 g / m 2 and 2500 g / m 2, where the frit particles have a diameter between 100 micrometres and 600 micrometres, a softening temperature between 840 °C and 1180 °C and a half-sphere temperature between 870 °C and 1235 °C. c. Introduce the ceramic tile resulting from the previous stages into an oven (7) and carry out a heat treatment at a maximum temperature between 850 °C and 1250 °C.

4. The method according to any of the preceding claims wherein the iridescent particles are selected from the group comprising tungsten (III) oxide, sillimanite, manganese dioxide, cordierite, sodium feldspar, potassium feldspar, corundum, mullite, wollastonite, zirconium silicate, tin dioxide, zirconium (IV) oxide, kyanite, micas, rutile, anatase, grit and quartz, or mixtures thereof.

5. The method according to any of the preceding claims, wherein the iridescent particles (3) and the frit particles are deposited mixed after performing a mixing step (M) to generate a mixture comprising said iridescent particles (3) between 1% and 50% by weight of the total mixture and said frit particles (5) between 50% and 99% by weight of the total mixture.

6. The method according to claim 1, wherein the iridescent particles (3) and / or the frit particles (5) are deposited on the unglazed (2) or glazed (2e) ceramic tile in a ceramic glaze (8) by means of an inkjet or airbrush or die or bell or disc or silkscreen or roller glazing station (9), with a predefined design and a weight comprised between 10 g / m 2 and 2500 g / m 2 .

7. The method according to any of the preceding claims, wherein, prior to the step of depositing the iridescent particles (3) and / or prior to the step of depositing the frit particles and / or prior to the step of depositing the mixture comprising the iridescent particles (3) and the frit particles (5) and / or prior to the step of depositing the ceramic glaze (8), at least one decorative ink (10) is printed by means of an inkjet or airbrush or die or bell or disc or screen printing or roller printing station (11), with a predefined design and a weight comprised between 10 g / m 2 and 1000 g / m 2 .

8. The method according to any of the preceding claims, wherein, prior to the step of depositing the iridescent particles (3) and / or prior to the step of depositing the frit particles (5) and / or prior to the step of depositing the mixture comprising the iridescent particles (3) and the frit particles (5), an ink with adhesive properties (12) is printed by means of an inkjet or airbrush or die or bell or disc or screen printing or roller printing station (13), with a predefined design and a weight comprised between 20 g / m 2 and 250 g / m 2 .

9. The method according to the preceding claim, wherein after the step of depositing the iridescent particles (3), or after the step of depositing the frit particles (5), or after the step of depositing the mixture comprising the iridescent particles (3) and the frit particles (5), the ink with adhesive properties (12) is printed again by means of an inkjet or airbrush printing station or die or bell or disc or screen printing or roller, with a predefined design and a weight comprised between 20 g / m 2 and 250 g / m 2 .

10. The method according to any of claims 8 or 9, wherein the printing of the ink with adhesive properties (12) and the iridescent particles (3) and / or the frit particles (5) and / or the mixture comprising the iridescent particles (3) and the frit particles (5) is carried out by means of a dry digital decoration equipment.

11. The method according to any of the preceding claims, wherein the heat treatment is carried out with a natural gas cooking oven (7), commonly used in the ceramic sector.

12. The method according to any of the preceding claims, wherein, after firing, each of the iridescent particles is totally or partially surrounded by a layer of frit such that the thickness (E) of said layer of frit is between 50 micrometers and 1000 micrometers, in the Cartesian planes along the X and / or Y and / or Z axes.

13. The method according to the preceding claim wherein the thickness of the frit layer is obtained by a surface polishing step after the heat treatment, using a polishing station (14).

14. Ceramic tile with iridescent effect (2a) manufactured according to the method described in any one of the preceding claims.

15. Ceramic tile according to claim 14, characterized in that each of the iridescent particles is totally or partially surrounded by a layer of frit such that the thickness (E) of said layer of frit is between 50 micrometers and 1000 micrometers, in the Cartesian planes along the X and / or Y and / or Z axes.

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