EP1977872A2

EP1977872A2 - Method for decorating a ceramic base support, in particular a tile

Info

Publication number: EP1977872A2
Application number: EP08103145A
Authority: EP
Inventors: Roberto Schianchi
Original assignee: Tsc SpA
Current assignee: Tsc SpA
Priority date: 2007-04-04
Filing date: 2008-03-28
Publication date: 2008-10-08
Also published as: ITBO20070248A1; EP1977872A3

Abstract

The invention relates to a method for decorating a ceramic base support, in particular a tile, the method comprising the following steps:
- firstly depositing a powdery layer in a mould (S), in order to provide a "soft" ceramic base support (1);
- then applying liquid ceramic enamels on the surface (2) of the "soft" ceramic base support (1) in order to provide a decoration proof (D);
- and final pressing the "soft" ceramic base support (1) and the related decoration proof (D) in order to provide a "compressed" ceramic base support (10).

Description

The technical field relating to the present invention is that concerning methods for decorating a ceramic base support, in particular a tile.
Ceramic field experts know many wet or dry systems to apply decorations on ceramic tiles, which are then transported in a suitable furnace for stably fixing the structure of the tile thus decorated.
Generally such decorations are applied on crude tiles comprising base supports made up of ceramic powders, which are first subjected to preliminary pressing.
A first known wet system comprises a decorating roller made up of a cylindrical sleeve, preferably in silicone, wound on a rigid support and with a plurality of pits defining a decoration on the outside.
The sleeve cooperates with a feeding apparatus, which feeds the pits with a liquid, enamel based substance and with a doctor which acts on the outer surface of the sleeve itself to remove the enamel in excess.
The upper arm of a conveyor, located beneath the decorating roller, carries the tiles to decorate, which are constituted by pressed ceramic powders.
Since the rim speed of the decorating roller and that of the upper arm of the conveyor are the same, together with a slight pressure of the decorating roller acting on the tile, leads to the release of at least a portion of the enamel contained in the pits on the upper surface of the tile.
One variant of such a system provides fixing of the sleeve to two heads keyed on the axis of the decorating roller, the heads enabling stretching of the sleeve; and the usage of two idle rollers internally of the sleeve, respectively to abut the doctor and press the sleeve on the tiles.
A second known wet system comprises the usage of the so-called "silk screens", with flat or folded configuration, to provide a cylindrical film fixed at two heads, which allow its stretching, keyed on the shaft of a decorating roller.
The screen comprises a plurality of micro-holes, defining a predetermined decoration, through which a liquid enamel based substance is forced to pass, which substance then deposits itself on the surface of the tile, made up of pressed ceramic powders.
It is understood that the relative speed between screen and surface of the decoration receiving tile must be null.
If the screen is cylindrical, this implies that its rim speed is the same as that of the moving tiles on which the screen is slightly pressed.
The known dry systems provide for the usage of the so-called "sleeve", made up of an endless belt, on which a plurality of pits are made which are filled with enamel, in granulated and/or powdery form, by means of a prefixed feeder; the enamel in excess being removed by a suitable apparatus.
The ceramic tiles to decorate, made up of pressed ceramic powders, are transported by the upper arm of a conveyor, located beneath the lower tip end of the "sleeve".
By the preceding description is easily apparent the complexity of the apparatuses required to implement the known systems for decorating tiles.
In many applications, the desired decoration on a tile, made up of pressed ceramic powders, is the result of the combination of a plurality of elementary decorations, each being obtained by means of a corresponding apparatus, for example of the above-described type.
As a result, the decoration assembly derives form the combination of more apparatuses, arranged in cascade, and this means disadvantages in terms of implementation costs and subsequent maintenance costs.
A very important disadvantage concerning the decoration assemblies is their extremely low and limited flexibility, because a change of decoration requires intervening on the corresponding apparatus, for example substituting the decorating roller, the silicone sleeve or the screen in wet systems, or the "sleeve" in dry systems.
Such substitution leads to non-negligible technical times, during which the apparatuses are not productive (so-called "machine stops") and, not less important to the need to stock a plurality of decorating rollers, silicone sleeves, silk screens or sleeves.
Such decorating systems, as previously stated, work on crude tiles made up of ceramic powders base supports, which have already been subjected to pressing.
Further dry systems are known as well, which comprise the following steps: preliminary depositing a "soft" base layer of ceramic powders; subsequently depositing at least one powdery layer of decoration; and then pressing the complete layer made up of the base layer and the decoration one.
It is easily understood that the excess thickness provided locally due to the decoration layer leads, at the end of pressing, to a very bad fixing of the predetermined final decoration.
This problem is principally a result of the coarse granulometry size caused by this kind of decoration, based on the usage of powder enamels, and the more the decoration is thin and/or filiform, the more it is problematic.
In addition to this non-negligible problem, these assemblies are extremely expensive and bulky as a result of many silos (so-called "technological towers") which can be as much as twenty units, to contain each decorating powder, and of many conveyors and weighing machines required to transport, batch, and/or mix the decorating powders to apply on the "soft" base layer.
It is an object of the invention to overcome the above mentioned disadvantages providing a method for decorating a ceramic base support, in particular a tile; the method allowing to realize extremely clear and defined decorations, independently from the types of the same.
Another object of the invention is to provide a method for decorating a ceramic base support, whose implementation implies rotating means-free assemblies.
A still another object of the present invention consists in providing an extremely reliable and versatile method which enables a clear and defined decoration of the ceramic base support prior to pressing step.
Yet, another object of the invention is to provide a decorating method which enables to obtain a ceramic base support characterized by quality and production costs parameters, respectively superior and inferior to the ones achievable by means of the known systems.
Moreover, a further object consists in providing a method particularly flexible, such that it allows to change easily and quickly the decoration to realize, and to avoid the non-productive steps of the operating process characterizing the known systems (so called "machine stops").
Said above-mentioned objects are obtained by a method for decorating a ceramic base support, characterized in that it comprises the following steps: depositing a powdery layer of ceramic material, in order to define a "soft" ceramic base support; applying liquid ceramic enamels on the surface of the "soft" ceramic base support in order to provide a decoration proof; pressing the "soft" ceramic base support and the related decoration proof in order to provide a decorated "compressed" ceramic base support.
The features of the present invention will become evident from the following detailed exemplary description of some embodiments in relation to the attached drawings, in which:

figures 1-3 show schematically operating steps in sequence of the proposed method in a preferred embodiment;
figure 4 shows a schematic top view of a decorated ceramic base support at the end of the process;
figures 5-7 show schematically operating steps in sequence of the proposed method in a further embodiment;
figure 8 shows a schematic prospective view of a particular apparatus able to implement the proposed method.

Referring particularly to figures 1-3, the operating steps of a preferred embodiment of the proposed method for decorating a ceramic base support, in particular a tile, are the following:

depositing a powdery layer of ceramic material, for example in a mould S, in order to define a "soft" ceramic base support 1 (figure 1);
applying liquid ceramic enamels on the surface 2 of the "soft" ceramic base support 1 in order to provide a decoration proof D (figure 2);
pressing the "soft" ceramic base support 1 and the related decoration proof D in order to provide a "compressed" ceramic base support 10 (figures 3, 4).

Referring particularly to figure 2, the application step of liquid ceramic enamels is carried out by means of a head 3, of the ink jet type, provided with a plurality of nozzles 4, able to dispense said enamels on the surface 2 of the "soft" base support 1.
After final pressing the "soft" ceramic base support 1, the "compressed" ceramic base support 10 thus obtained is advantageously introduced in a known baking furnace (not shown for sake of clarity) to stabilize its structure and to give it the predetermined mechanical properties.
It is understood that the "compressed" ceramic base support 10 can be subjected to further operating steps prior to its introduction in the baking furnace.
Referring particularly to figure 1 and figures 5-7, the operating steps of a further embodiment of the present method are the following:

depositing a powdery layer of ceramic material, for example in a mould S, in order to define a "soft" ceramic base support 1 (figure 1);
preliminary compacting the "soft" ceramic base support 1 to provide a "pre-compacted" ceramic base support 17 (figure 5);
applying liquid ceramic enamels on the surface 2a of the "pre-compacted" ceramic base support 17 in order to provide a decoration proof D (figure 6);
pressing the "pre-compacted" ceramic base support 17 and the related decoration proof D in order to provide a decorated "compressed" ceramic base support 10 (figure 7).

Also in this case, referring particularly to figure 6, the application step of liquid ceramic enamels is carried out by means of a head 3, of the ink jet type, provided with a plurality of nozzles 4, able to dispense said enamels on the surface 2a of the "pre-compacted" ceramic base support 17.
Similarly, after final pressing the "pre-compacted" ceramic base support 17, the "compressed" ceramic base support 10 thus obtained is introduced in a known baking furnace (not shown) to stabilize its structure and to give it the predetermined mechanical properties.
The "compressed" ceramic base support 10 can be subjected to further operating steps prior to its introduction in the baking furnace, as well.
In both embodiments, the head 3 moving step with respect to the "soft" ceramic base support 1 or the "pre-compacted" one 17, is controlled by means of a processing software of the predetermined decoration proof D.
The movement of the head 3 with respect to the ceramic base support (1, 17) can be carried out in an unique longitudinal direction, or in two longitudinal and transverse orthogonal directions.
In the first case (not shown), the nozzles 4 of the head 3 cover all the transverse extension of the ceramic base support (1, 17) and the relative movement is provided in the longitudinal direction of the relative advancement.
In the second case, shown in the figures 2-6, the head 3 is advantageously movable relative to the ceramic base support (1, 17), both longitudinally, in the direction of the relative advancement, and transversely.
It is to be pointed out that storing a plurality of decoration proofs D in an electronic file allows selecting the same each time required, by means of a known computer, according to the type of the ceramic base support.
In such manner, it is extremely easy to change the decoration D, even between a ceramic base support (1, 17) and the following one, by setting for example the change timing.
The description and the appended drawings refer, purely by way of example, to a "soft" base support 1 obtained in a mould S, which provides the form of a final tile; it is to be understood, however, that the inventive method can be applied to any "soft" ceramic base support 1 obtained starting from the deposit of a powdery layer of ceramic material, as for example the case of the so-called "continuous layer" of "soft" ceramic base support, schematically shown in figure 8.
Similarly, it is important to stress that the ceramic enamels in liquid form applied on the surface (2, 2a) of the "soft" ceramic base support 1 or the "pre-compacted" one 17 can be absorbed partially or totally by the same ceramic base support (1, 17) prior to its pressing.
From the above description, it is easily understood that the inventive method for decorating a ceramic base support, in particular a tile, allows the realization of extremely defined and complex decorations in very short times.
In such case, the decorations fixing is controlled by the resolution power achievable by means of the ink jet type head, and therefore by the number of nozzles required.
The minimum thickness of the decoration, in contrast to the known art, allows to maintain the maximum clearness and definition values of the same even after the final pressing step.
The high speed with which any type of decoration can be achieved, affects positively the method productivity and its costs.
In contrast to the decoration processes known by those skilled in the art, the proposed method does not advantageously require to be actuated by means of apparatuses equipped with rotating components, consequently offering more flexibility and reliability of the operating steps.
This allows to avoid the "machine stops" non-productive steps of the operating process characterizing the known systems.
It is clear that such a decorating method allows to attain a ceramic tile characterized by quality and production costs parameters, respectively superior and inferior to those achievable by the known systems.
It has to be underlined that the inventive method allows extremely defined and complex decorations also on projecting or recessed portions of the ceramic tile by means of a final pressed plate provided with a corresponding and appropriate known shaping to realize such portions.
In such cases, the high definition is guaranteed by an unique pressing step of the "soft" or "pre-compacted" ceramic base support, on which the decoration proof has already been applied; while in the known art, the "soft" base support is generally pressed first and decorated only after.
Referring to the known systems in which the "soft" base support is decorated by means of powdery enamels and later pressed, the method according to the invention assures not only optimal definition and clearness parameters of the decorations, but also allows to strongly limit costs and dimensions of the assemblies thanks to the lack of silos and of conveyors and weighing machines required in such known assemblies.
Moreover, the inventive method allows to prevent possible fouling of the head and relative nozzles since the application of the liquid ceramic enamels is provided on relatively low temperature base supports and without high humidity rates.
The present invention has obviously been described as purely exemplary and non limiting with reference to the appended drawings, and it is therefore evident that is possible every change and variation, which falls into the scope defined by the following claims.

Claims

Method for decorating a ceramic base support, characterized in that it comprises the following steps:
- depositing a powdery layer of ceramic material, in order to define a "soft" ceramic base support (1);

- applying liquid ceramic enamels on the surface (2) of the "soft" ceramic base support (1) in order to provide a decoration proof (D);

- pressing the "soft" ceramic base support (1) and the related decoration proof (D) in order to provide a decorated "compressed" ceramic base support (10).
Method according to claim 1, characterized in that the application of liquid ceramic enamels is carried out by means of at least a head (3), of the ink jet type, provided with at least a nozzle (4) to dispense said enamels on the surface (2) of the "soft" ceramic base support (1).
Method according to claim 1 or 2, characterized in that the decorated "compressed" ceramic base support (10) is introduced in a baking furnace after pressing the "soft" ceramic base support (1).
Method for decorating a ceramic base support, characterized in that it comprises the following operating steps:
- depositing a powdery layer of ceramic material in order to define a "soft" ceramic base support (1);

- preliminary compacting the "soft" ceramic base support (1) to provide a "pre-compacted" ceramic base support (17);

- applying liquid ceramic enamels on the surface (2a) of the "pre-compacted" ceramic base support (17) in order to provide a decoration proof (D);

- final pressing the "pre-compacted" ceramic base support (17) and the related decoration proof (D) in order to provide a decorated "compressed" ceramic base support (10).
Method according to claim 4, characterized in that the application of liquid ceramic enamels is carried out by means of at least a head (3), of the ink jet type, provided with at least one nozzle (4) to dispense said enamels on the surface (2a) of the "pre-compacted" ceramic base support (17).
Method according to claim 4 or 5, characterized in that the decorated "compressed" ceramic base support (10) is introduced in a baking furnace after pressing the "pre-compacted" ceramic base support (17).
Method according to claim 1 or 4, characterized in that the "soft" ceramic base support (1) is obtained by depositing a powdery layer of ceramic material in a mould (S).
Method according to claim 2 or 5, characterized in that the movement of head (3) with respect to the "soft" ceramic base support (1) or the "pre-compacted" one (17) is controlled by means of a software processing the predetermined decoration proof (D).
Method according to claim 8, characterized in that the movement of the head (3) with respect to the "soft" ceramic base support (1) or the "pre-compacted" one (17) is carried out at least in a longitudinal direction.
Method according to claim 8, characterized in that the movement of the head (3) with respect to the "soft" ceramic base support (1) or the "pre-compacted" one (17) is carried out in two longitudinal and transverse orthogonal directions.