WO2005025828A1

WO2005025828A1 - Method and apparatus for decorating

Info

Publication number: WO2005025828A1
Application number: PCT/IB2004/003011
Authority: WO
Inventors: Carlo Antonio Camorani
Original assignee: Mira Di Algeri Maris
Priority date: 2003-09-17
Filing date: 2004-09-16
Publication date: 2005-03-24
Also published as: ITMO20030251A1

Abstract

A method for transferring a decorating material (8, 24, 28, 39, 45) defining a pattern on a receiving surface (13, 35) comprising in sequence: applying said decorating material (8, 24, 28, 39, 45) to a transfer surface (3, 37) according to a prefiguration (7, 8a) of said pattern, making said transfer surface (3, 37) bearing said decorating material (8, 24, 28, 39, 45) face said receiving surface (13, 35) in such a way as to define a gap (D) between said transfer surface (3, 37) and said receiving surface (13, 35), detaching said decorating material (8, 24, 28, 39, 45) from said transfer surface (3, 37) by means of separating means (14, 46, 55, 57) materially arranged in said gap (D); moving said decorating material (8, 24, 28, 39, 45) towards said receiving surface (13, 35); a decorating apparatus (1) for transferring a decorating material (8, 24, 28, 39, 45) defining a pattern onto a receiving surface (13, 35) comprising a transfer surface (3, 37) provided with at least a portion facing said receiving surface (13, 35) in such a way that a gap (D) is defined between said transfer surface (3, 37) and said receiving surface (13, 35), applying means (5, 9, 11, 21, 26) suitable for applying said decorating material (8, 24, 28, 39) onto said transfer surface (3, 37) according to a prefiguration (7, 8a) of said pattern, separating means (14, 46, 55, 57) materiall arranged in said gap (D) and suitable for detaching said decorating mateiral (8, 24, 28, 39, 45) from said transfer surface (3, 37).

Description

METHOD AND APPARATUS FOR DECORATING

The invention relates to a method and to an apparatus for transferring decorating material to a surface to be decorated, particularly to create decorations on ceramic tiles, optionally also according to a pattern controlled in real time by computerised means.

Different decorating technologies are known that provide for the use of a transfer surface in which the decorating material is first associated with the transfer surface, movable along a circuit path, and then passes from the latter to the surface to be decorated.

The transfer surface may have a hollowed surface and the decorating material may be transported inside the hollows, in this case a matrix bearing the pattern is configured in the transfer surface.

Numerous applications exist that differ from one another above all in the manner of associating the decorating material with the transfer surface and in the manner of then transferring it to the surface to be decorated. This transfer may occur through contact, using the adhesive effect towards the surface to be decorated, or without contact with the assistance of other forces.

Examples of transfers with contact are disclosed in EP530627, EP635369, EP677364, EP727778, EP769728, EP834784, US5890043, IT1287473, ITI104942, IT1310834 and IT1314624. One common features of all these cited examples is that the decorating material must at the moment of transfer be in a state of liquid suspension or possibly in a melted state, in order to exploit the adhesive effect on the surface to be decorated. The inevitable direct interaction with the surface to be decorated thus constitutes a great operating limit, for example, loose, wet or rough surfaces cannot be decorated. In IT1262691, the wet or dry decorating material is first incorporated in cavities of a belt-transfer surface and is then projected onto the surface to be decorated through the effect of an ultrasonic vibration transmitted through the transfer surface. Using ultrasonic equipment involves complications, high costs and energy expenditure. Furthermore, problems may exist that are due to low operating speed, incomplete transfer of the decoration, poor definition, damage to the transfer surface caused by the energy dissipated by the ultrasonic devices. IT1262691 furthermore discloses a system that incorporates decorating material in a latticed matrix with through cavities and then projecting the decorating material onto the surface to be decorated without contact, through the effect of an air jet. The ejection by means of an air jet is not always achievable in a regular manner and above all the air current tends to inevitably decompose the arrangement of the decoration on the surface to be decorated.

EP1170104 provides for inserting decorating powders inside cavities of a rotating matrix and then dropping the powders when they are facing the surface to be decorated. Along the approach path the powders are kept inside the cavities by support retaining means consisting of sliding or rotating enveloping screens.

One limit of EP1170104 is the uncertain detachment of the decoration when the effect of the retaining means terminates, especially if fine powders are used in small cavities to obtain high-definition patterns. Furthermore, in the case of a sliding screen, significant wear and leaks are inevitable, whereas in the case of a rotating screen, as the lower enveloping means must have certain overall dimensions, during the drop a certain decomposition of the decoration is inevitable.

EP0927687 provides for selectively lifting up decorating material in powder by vacuum through a rotating latticed matrix and dropping the aforementioned decorating material onto the surface to be decorated by interruption of the vacuum. EP0927687 has a limit in that powders that are too fine cannot be used as they tend to pass through the matrix, furthermore, these fine, powders have difficulty detaching themselves from the matrix if appropriated configured devices that encourage detaching are not used. The prior art disclosed until now also has a great limit in that the transfer surface is also the pattern matrix and it is not therefore possible to vary the pattern except by replacing the transfer surface.

IT13114624 provides for applying at a rotating transfer surface, a pattern formed by microdrops of liquid projected by an ink-jet head. Subsequently, the decorating material in powder is made to adhere to the microdrops, which is then transferred to the surface to be decorated. This transfer is obtained either by direct contact or otherwise by ultrasonic vibration of the transfer surface and without contact between the transfer surface and the surface to be decorated. IT13114624 has the advantage of not requiring a matrix with a preformed pattern, nevertheless, during the phase of transfer of the decoration to the surface to be decorated it has some of the drawbacks already mentioned, namely contact or use of ultrasonic devices.

It should furthermore be noted that the ultrasonic vibration devices as used in the prior art are applicable only to a transfer surface constituted by a thin belt, this makes these machines rather complicated and vulnerable. Furthermore, blurring of the pattern may occur as the transfer zone is not well concentrated and defined as the vibration is transmitted to the belt also in zones on the periphery of the point of application of the vibration.

Systems are known for the transfer of the decoration from a transfer system based on the use of electrostatic forces. Such systems are limited by the fact that they can be used only with specific and particular decorating powders and only for certain products to be decorated.

Ink-jet decorating systems for the ceramics field are furthermore known in which the decorating ink is projected directly onto the surface of the product. The ceramic pigment that passes through the ejectors of the ink-jet device can be a fine solid suspension or a dissolved metal complex. In the former case significant wear and dangers of clogging occur, in the latter case the chromatic power is rather limited, there also existing a risk of chemical corrosion to the ink- jet apparatus, in both cases, inks are necessary that are made according to particular formulas so that the inks are very expensive.

One object of the invention is to improve the apparatuses and the methods for transferring decorating material to a surface to be decorated.

Another object is to enable the depositing of decorating substances on a surface to be decorated according to a well- defined pattern, possibly controllable directly in real time by computerised means, without problems of clogging and/or wear, also using conventional decorating materials. A further object of the invention is to improve definition in the transfer without contact of decorating material from a transfer surface to a surface to be decorated.

A further object of the invention is to simplify the transfer without contact of decorating material from a transfer surface to a surface to be decorated.

A further object of the invention is to diminish energy expenditure in transfer without contact of decorating material from a transfer surface to a surface to be decorated.

A further object of the invention is to make more efficient and faster transfer without contact of decorating material from- a transfer surface to a surface to be decorated. A further object of the invention is to enable the use of a matrix normally used for wet decoration with contact, to apply, without contact being necessary, decorating material in powder onto a surface to be decorated.

A further object of the invention is to permit the use of a gravure-engraved or latticed matrix, normally used for wet decoration with contact, to apply, without contact being necessary, decorating material in powder on a surface to be decorated in such a way that the volume of said decorating material deposited on the decorated surface is noticeably greater than the corresponding volume of the hollows of the matrix. A further object of the invention is to enable the operation of a decorating machine with control of the image optionally assigned to a preformed pattern matrix and/or computer- controlled ink-jet devices.

A further object of the invention is to enable the use of decorating materials in powder form in a liquid suspension during the initial cycle phase and in dry state during final transfer to the surface to be decorated.

A further object of the invention is to simplify and to improve the dry transfer to a surface to be decorated with several colours with mixing together between the different colours to obtain a decoration having a great thickness. A further object of the invention is to enable the wet transfer to a decorating surface of different colours with mixing together between the different colours to obtain a decoration having a great thickness.

In a first aspect of the invention a method is provided for transferring a decorating material defining a pattern onto a receiving surface in which in sequence:

-applying said decorating material to a transfer surface according to a prefiguration of said pattern; making said transfer surface bearing said decorating material face said receiving surface in such a way as to define a gap between said transfer surface and said receiving surface; detaching said decorating material from said transfer surface by means of separating means materially arranged in said gap;

- moving said decorating material towards said receiving surface.

In one advantageous embodiment, said transfer surface is movable along a circuit path.

In a further advantageous embodiment, said transfer .surface is smooth.

In a second aspect of the invention a decorating apparatus is provided for transferring a decorating material defining a pattern onto a receiving surface comprising: a transfer surface provided with at least one stretch facing said receiving surface in such a way that a gap is defined between said transfer surface and said receiving surface; applying means suitable for applying said decorating material to said transfer surface according to a prefiguration of said drawing; separating means materially arranged in said gap suitable for detaching said decorating material from said transfer surface.

In one advantageous embodiment, said transfer surface extends along a circuit path.

In a further advantageous embodiment said transfer surface is smooth.

The invention will be better understood with the help of the attached tables of drawings that show some embodiments by way of non-limiting example, in which:

Figure 1 is a schematic side view of the device according to the invention;

Figure 2 is a schematic side view of a detail of Figure 1; Figure 3 is a schematic side view taken along a line III-III of Figure 1;

Figure 4 is a schematic side view of the device according to the- invention in a different embodiment;

Figure 5 is a schematic side view of the device according- to the invention in a further different embodiment; Figure 6 is a schematic side view of the device according to the invention showing a particular operating mode; Figure 7 is a schematic side view of the device according to the invention showing the detail in Figure 2 in a different configuration;

Figure 8 is a schematic side view of the device according to the invention in a different embodiment for applying different colours;

Figure 9 is a greatly enlarged detail of a device like the one in Figure 8 but in a different operating mode with material in a wet state; Figures 10 to 13 show the detail in Figure 9 in different versions .

Figure 14 is a schematic side view of a detail of the device according to the invention in a further different version;

Figure 15 is a perspective view of the device of Figure 14;

Figure 16 is as view as in Figure 14 in a further different version;

Figure 17 is a perspective view of the device of figure 16.

The decorating machine 1 consists of a cylindrical body 2 with a horizontal axis Z provided with a side surface 3 made to rotate in the direction of the arrow 4. In particular, the side surface 3 may be made with chromed steel with mirror finish. Around said surface 3, starting from the top part and in a clockwise direction, the following are arranged in order: an ink-jet head 5, controlled by computerised means, not shown, and suitable for projecting a pattern 7 in the form of microdrops of liquid 6 onto the surface 3; distributing means of decorating powders 8 arranged downstream of the head 5; recovery means of excess decorating powders 8, consisting of a belt conveyor 9, arranged parallel to the axis Z of the cylinder 2 and provided with movement rollers 10, a deviating baffle 11 slightly distanced from the surface 3, lifting means, optional conditioning devices not shown such as grading screens and drying devices; drying means 12 consisting of radiant devices arranged near the surface 3.

At the bottom of the cylinder 2 where the surface 3 faces the surface 13 to be decorated a steel blade 14 with an appropriately curved contour in the same direction as the curve of the surface 3 is present.

The blade 14, kept in position by a support 15, extends on the surface 3 of the cylinder 2 parallel to the Z axis, it has a cutting end 16 turned in the direction opposite the rotation direction 4. The end 16 is kept pressed on the surface 3 by force F, through the effect of the bending elastic deformation of the blade 14.

The operation is explained as follows: whilst the cylinder 2 rotates at a constant speed clockwise according to the arrow 4, the ink-jet head 5 projects onto the surface 3 a pattern 7 formed of microdrops of liquid 6 that substantially consists of a sole liquid phase, for instance demineralized water. On the surface 3 the decorating material in powder form 8 is dropped, which adheres only at the liquid microdrops 6 whereas the excess non-adhering powder 8 is collected by the recovery means 9, 11. During the passage on the drying zone 12 the liquid 6 is removed by evaporation and on the surface 3 there remains only the decorating material 8, arranged according to a formation 8a corresponding to the pattern 7 of liquid microdrops 6, adhering weakly but in a sufficient manner to prevent detachment and without undergoing alterations, through the effect of its own adhesion and/or through slight adhesion produced by residues of the liquid 6. Subsequently, during the passage against the blade 14, the decorating material 8 is forced to detach itself from the surface 3 and fall by gravity onto the surface 13 to be decorated in movement concordant with that of the transfer surface 3.

The particular arched conformation of the blade 14 enables a minimum distance D to be obtained without the support 15 being able to interfere with the surface 13, thereby obtaining the maximum pattern definition.

The blade 14 may consist of metal, for example stainless steel, or of suitable plastic material that is highly resistant to abrasion and has a low friction coefficient. From experimental tests it has been possible to ascertain that with a steel blade 0.2 mm thick .all the decorating material 8 is detached and the surface 3 remains completely clean. The contact between the blade 14 and the surface 3 with chromed mirror finish prevents any infiltration of powders between these surfaces, this makes the device extremely resistant to abrasion and reliable. In order to prevent decorating material residues 8 from being able to remain attached to the blade 14, the latter can consist of or be clad with material with non-stick properties. For this purpose, vibrating means may also be present that consists of hammers 20 arranged at the ends of the support member 15 that alternately hit said support member 15 first on one side and then on the other to transmit to the blade 14 a sharp vibration in a direction parallel to the Z axis. Alternatively or additionally, said impulsive vibration can be transmitted in a direction substantially parallel to the rotation direction 4 of the surface 3 by hammers 19 acting on the support member 15 along its longitudinal extent. This vibration may nevertheless be advantageously directed in any direction included in the plane tangential to the surface 3 in the point of contact with the blade 14. This vibration can also be an ultrasonic frequency. Furthermore, automatic devices can be advantageously provided to activate said vibration only at given moments and only with the transfer surface moving to prevent overheating and/or damage. As shown in Figure 4, the liquid drops 6 are applied to the surface 3 with a gravure-engraved belt matrix 21 - that is provided with cavities defining, in particular, a pre- established pattern - the operating phases of the apparatus being similar to the example in Figure 1. This embodiment is useful when one wishes to use a gravure-engraved matrix 21, or silkscreen matrix, which are normally used in contact decoration with decorating material in liquid suspension, to reproduce the same design without contact and with the use of dry-state decorating materials. In this way, furthermore, in accordance with one of the objects of the invention, the decorating material 22 arranged on the surface 13 will have a volume V noticeably greater than the volume VI of the corresponding recesses 23 of the matrix 21. This is made possible by the fact that the recesses 23 are completely filled only with liquid 6, which, after transferring to the surface 3, may incorporate or make adhere a volume V of powder 8 greatly superior to the volume VI of the relative recess in the matrix 21.

According to one of the objects of the invention and as illustrated in Figure 4, control of the image obtained through the application of the liquid 6 may be optionally assigned to a matrix 21, or to an ink-jet head 5. Both devices, the matrix 21, and the ink-jet head 5, may also be activated simultaneously as the ink jet head 5, by working without contact, does not interfere with any liquid drops 6 that may already be present on the surface 3. This embodiment has the advantage of significant operating versatility and may enable aesthetic and productive results to be obtained that are not otherwise obtainable.

As illustrated in Figure 5, a decorating material 24 inserted into the recesses 25 of a gravure-engraved matrix 26 by means of a doctor blade 27, is deposited onto the transfer surface 3. The decorating material 24 is a suspension consisting of a solid colouring phase 28 and of a liquid phase L that can evaporate by heating. The surface 3 cooperates with heating means 12 that cause removal of the liquid phase, leaving only the solid phase 28 adhering to the surface 3 weakly but in a sufficient manner to prevent detachment. As in the preceding examples, a blade 14 causes the detachment of this solid phase .28 and the transfer to the surface 13 to be decorated. This embodiment enables the use of a gravure-engraved or lattice matrix 26, which is normally used for wet decoration by contact, to place decorating material in powder form 28 on a surface to be decorated 13, without contact being necessary.

Furthermore, this embodiment enables the use of decorating materials in powder form, in liquid suspension during the initial phase of the cycle and in a dry state in the final transfer onto the surface 13 to be decorated. This is advantageous because, for example, the decorating material in powder form can be prepared in a liquid suspension (thereby obtaining notable benefits in the limitation of environmental dust and better control of the movement of the decorating material) , simultaneously having the advantage of being able to decorate dry' and without contact even on loose surfaces such as layers of powders to be pressed.

It is pointed out that the heating means 12 may also be integrated into the cylinder 2 in such a way as to keep the entire surface 3 at a suitable temperature, for example at about 70 °C or even more, depending on the type of liquid 6 used.

As the microdrops 6 on the surface 3 have to be rather small and be arranged in a fairly thinned out manner to prevent harmful running and agglomeration phenomena of the microdrops 6 caused by gravity and surface tension, there is a limit to the quantity of decorating material 8 that is transferable to the surface 13. Furthermore, as the decorating material 8 is stuck to the surface 3 in the form of small distinct agglomerates, this thinned out ^''pixel'^' conformation tends to be similarly reproduced on the surface 13.

The embodiment shown in Figure 6 overcomes these drawbacks by providing a speed Ul of the transfer surface 3 that is relatively higher than the speed U3 of the surface 13 to be decorated. In this way, the frequency of ejection of the microdrops 6 can be proportionally increased without giving rise to agglomeration phenomena. In the subsequent transfer from the transfer surface 3 to the surface 13 to be decorated, the different particles of decorating material 8 are thus able to become superimposed thereby forming controlled thicknesses SI, S2 of decorating material 8. In other words, whilst on the transfer surface 3 the particles of decorating material 8 (corresponding to the formation 7 of microdrops 6) are arranged in sequence and spaced from one another, on the surface 13 the particles can be superimposed and form a stratification of modulated and controlled thickness SI, S2 depending on the U1/U3 ration and the programmed pattern. The modulation of the thickness SI, S2 will be determined by a different relative distance between the microdrops 6 arranged on the transfer surface 3 and/or by a different dimension of the microdrops 6. This embodiment of the invention illustrated in Figure β enables thorough control of the thickness SI, S2 of the decorating material 8 placed on the surface 13, thus enabling delicate variations in the intensity of colour to be obtained and if necessary also makes it possible to obtain great thicknesses SI, S2.

The speed ratio U1/U3 may be conveniently chosen between the values 1.5 and 20. Higher or lower values of the U1/U3 ratio may be applied in all cases.

It is pointed out that this difference between the speeds Ul and U3 can also be adopted in all the other embodiments of the present invention.

As shown in Figure 6, the terminal part of the blade 14 has a relatively low rake B. This rake B influences the horizontal speed component U2 that the particles 8 have in the fall path towards the surface 13. With a high rake B, i.e. near 90°, the material will be only modestly slowed down and the horizontal speed component U2 will be only slightly lower than the speed Ul . With a low rake B, i.e. near zero degrees, the horizontal speed component U2 may even be cancelled. The adoption of an appropriate rake B is therefore useful for obtaining a speed U2 that is substantially the same as U3 and avoid phenomena of uncontrolled flow of the particles 8 on the surface 13, thereby favouring obtaining a more sharply defined image.

The choice of correct rake B to have U2=U3 depends on numerous parameters such as for example: U1/U3 ratio, Ul speed, distance D, thickness 30 of the blade 14, dimensions and specific weights of the particles 8, friction coefficient between the particles 8 and the front slide surface 29 of the blade 14.

The best way to precisely determine this rake B is by experiment, nevertheless a rake B with a value of 60° to 15° will in most cases be optimal for U1/U3 speed ratios between 2 to 10.

The front surface 29 of the blade 14 may be flat or be appropriately curved as in Figure 6 with a rake Bl in the zone near the surface 3 with a value above 60-70° and with a rake B in the bottom zone of a noticeably lower value. This conformation may be advantageous because the material 8 tends to be in contact with the surface 29 along the entire path, taking on a more precise direction at the outlet. As illustrated in Figure 7, the blade 14 has a seal 31 that cooperates with the surface 3 in such a way as to define a closed chamber 32. The chamber 32 is supplied with pressurised air, the air thus introduced flows through a small slit 33 that is formed by the elastic deformation of the blade 14 as it moves away from the surface 3 at its end part 16. The flow of air 34 leaving the slit 33 thus causes the detachment of decorating material 8 from the surface 3. By suitably regulating the size of the force F an air flow will be obtained that is more or less incisive because increasing force F will tend to diminish the dimension of the slit 33 and to increase the internal pressure of the chamber 32 and vice versa. This makes an effective detachment of the decorating material 8 possible with the use of minimal volumes of air in such a way as not to decompose the pattern 8a.

The flow of air through the slit 33 may contribute to diminishing the friction between the blade 14 and the surface 3, between which an air cushion is formed. The flow of air can also be useful for avoiding the intrusion of powders into the interface and for keeping the surfaces clean. The decorated surface 13 may also constitute a further transfer surface. The decorating material 8 may in other words be applied to the surface 13 and be transferred by the latter to a different subsequent surface 35.

Such an example is useful if one wishes to use different decorating materials and is illustrated in Figure 8. A belt 36 with a smooth external surface 37 is positioned on movement rollers 38. Four devices 1 like those illustrated in Figure 1 are arrayed in sequence above the top branch of the belt 36 and each of these devices 1 is suitable for depositing on the surface 37 a material 39 of a different colour 39b, 39c, 39d, 39e. Upstream of the devices 1, in a treatment station 40, the surface 37 is treated with a light layer of a suitable liquid 41 in which the materials 39 are integrated. The function of this treatment station 40 is to fix the material 39 on the surface 37. Alternatively, a plurality of treatment stations arranged downstream or upstream of any of the devices 1 may be provided. Alternatively it may be also provided a single treatment station 40 arranged downstream of all devices 1. Downstream of the devices 1, in a drying station 42, the liquid 41 is removed by evaporation. The materials 39, although dried, remain adherent to the surface 37. This light but stable adherence (that remains also in a position 43 when the surface 37 is turned downwards) can be favoured by the presence of a certain percentage of clay material (at least 1%) in the composition of the material 39. Near to the surface 35, a blade 14 causes the transfer of the material 39 to the surface 35. Also in this case it is provided for that the speed Ul of the surface 37 is noticeably greater than the speed U3 of the surface 35. This brings a further advantage as mixing of the different colours 39b, 39c, 39d, 39e of material that each device 1 has deposited is obtained. As shown in the enlarged details of Figure 8, on the surface 37 the different colours 39b, 39c, 39d, 39e are deposited in thin layers and are superimposed with a total thickness S3. In the surface 35 the different colours 39b, 3.9c, 39d, 39e are by contrast in a layer 44 with a greater thickness S4, with substantially uniform colouring in a direction H perpendicular to the surface 35, and with very varied colouring (caused by the infinity of possible weight combinations of the different colours 39b, 39c, 39d, 39e) in a direction M parallel to the surface 35.

In Figure 8, very schematic, the different layers 39b, 39c, 39d, 39e arranged on the surface 37 are illustrated superimposed, distinct and each with a uniform thickness. In practice, as these different colours 39b, 39c, 39d, 39e can be arranged on the surface 37 in the form of small, distinct and thinned out agglomerates (corresponding to the microdrops 6) , this layer 39 will be a single thin layer constituted by particles of different colours 39b, 39c, 39d, 39e that are already mixed according to ° the different proportions determined by the control program. Similarly, also the vertical layers 44 arranged on the surface 35 will in practice be indefinitely thin and arrayed in direction M without interruption.

In conformity with one of the objects of the invention, it is pointed out that in comparison with IT MO2000A000117 the transfer of powders from the high-speed surface to the low- speed surface is in the present invention more precise because the two surfaces can be extremely near, the only limit being the very modest thickness of the blade 14. As already said, the decorating material 8 remains attached to the surface 3, 37 according to the pattern 7 in a well- defined and stable manner, it is not inclined to become decomposed if stressed below a determined threshold value 8, (which could be the stress caused by centrifugal forces, vibrations, air currents, etc) whereas it is detached in a decisive and precise manner as soon as it is moved because the threshold value has been exceeded.

This important feature is a consequence of the fact that the decorating material 8, 39 has been attached to the surface 3, 37 by means of a liquid phase 6, 41, L that initially acted as a binder and aggregant between the different particles 8, 39 and the surface 3, 37. Thereafter, this binding effect is reduced by the solidification or removal of the liquid phase 6, 41, L, but the decorating material 8, 37 still remains attached to the surface 3, 37 through the intimate contact that has been created between the different particles and the surface 3, 37.

In Figure 9, the decorating material is incorporated into a liquid phase 41, also at the moment of the transfer to the surface 35. It is attached to the transfer surface 37 in the form of small agglomerates 45, each of which consists of one of the base colours. The stop 46 deviates these small agglomerates towards the surface 35, where they meet to form a layer of wet glaze 47 in different colours according to the preset proportion between the different base colours. The sliding of the small agglomerates 45 on the stop 46 is facilitated by a cladding 48 in self-cleaning material such as for example that disclosed in EP0772514. This self- cleaning effect is increased and made durable by an air cushion supplied by a pressurised chamber 32 through a microporous diffuser material 49.

Figure 10 shows how the union of the small agglomerates 45 can already occur on the surface 37. The thin layer 50 that is thus formed flows on the surface 48 and transfers to the surface 35 to be decorated. Depending on operating parameters, this union may also take place on the slide surface 48.

Figure 11 illustrates an operation similar to that of Figure 10 but with movement of the surface 35 to be decorated in the opposite direction to that of the transfer surface 37, this may be advantageous for not altering the pattern reproduced on the surface of the layer 47 - designed to adorn the visible face of an article - by rubbing of said surface of the layer 47 against the stop 46.

The precise detachment of the decorating material 45 from the stop 46 is also favoured by a wedge-shaped protuberance 51 at the bottom end of the stop 46.

In Figure 12 the deviator 46 comprises a propulsor 52 consisting of a conduit 53 leading near the wedge-shaped protuberance 51 through a thin slit 54. This slit 54 is normally closed because of the contact with the wedge shaped protuberance 51, due to a force Fl, of a wall bounding the conduit 53 at its bottom, but opens automatically with the air pressure in the conduit 53. By adjusting the force Fl, the variation of the dimensions of the slit 54 and the adjustment of the air pressure, rate and speed values of a flow P discharged from the slit 54 are obtained. The function of this flow P is to increase the precision and projection speed of the material 8, 45 and to keep the deviator 46 clean.

Figure 13 shows a similar propulsor 52, but which terminates with a U-shaped wall on which the flow P reverses the direction by about 140°. In this case, unlike the example in Figure 12, the movement directions of the transfer surface 37 and of the decorated surface 35 coincide.

The two examples also differ in that in the first case decorating material in wet state is treated and in the second material in dry state is treated, but this can also be inverted. Equally, both the examples of Figures 12 and 13 may function with an already formed coat 50 on the deviator 46, as shown in Figures 10 and 11.

If necessary, through the slit 54 of the propulsor 52 liquid can also be projected, this may be useful for having greater effectiveness and/or for obtaining a fixing effect of the dry decorating material on the surface 35.

In Figure 14, the separating means consists of a wire 55 that is tensioned and kept in axial rotation C in such a way that its contact surface on the surface 37 is continuously renewed in such a way as to make the system self-cleaning. Contact with the transfer surface 37 is assured by magnetic attraction in direction 61 exerted by the roller 56 on the wire 55, which for this purpose comprises a material that is subjectable to magnetic attraction. In the example in Figure 14 the wire 55 has a circular cross section but may have any other polygonal shape or star shape to have a more effective scraping effect. In the latter cases, the polygonal or star sections may be advantageously developed axially in a helical manner. As illustrated in Figure 15, the wire 55 is wound on two tensioning reels 55a that alternately wind and unwind by rotation the wire 55 from one reel 55a to the other. This solution reduces wear to the wire 55 and furthermore enables the use of optional cleaning means of the wire 55 arranged in a zone that does not interfere with the powders to be transferred. In the example in Figure 16 and 17, the separating means consists of a metal belt 57 that is kept tensioned by rotating supports 58 and has an axial movement in a direction 59. An external station 60 is provided for cleaning the belt 57. As is the case in Figure 14, contact is assured by magnetic attraction in the direction 61 exerted by the roller 56. The attraction in the direction 61 can be advantageously exerted electromagnetically in the direction 61 alternately at a suitable frequency so as to induce a self-cleaning vibrating effect on the belt 57. The belt 57 has a loop shape that is closed with a return path 57a, nevertheless, it can also be constructed with two free ends spirally wound on two reels, being equipped with alternate winding and unwinding movement 59 on the coils. The axial speed of the belt 57 (or of the wire 55) , depending on the other operating parameters, may be very varied, it may for example vary by a few centimetres per minute to several dozens of metres per minute. This axial movement may also be exerted only during the inactive moments of the device, for example during the passage between one tile 35 and the next.

The belt 57 advantageously has an arched cross section with concavity turned to the surface 37 with a curvature radius R that is less than the curvature radius RI that the surface 37 has in the zone of contact with the belt 57. This favours a contact of both edges of the belt 57 with the surface 37 and enables more effective electromagnetic vibration. The devices of Figures 14 to 17 have the advantage of not having near the surface to be decorated 35 any static surface but only continuously movable and renewed surfaces. This makes the device self-cleaning, thus preventing accumulation of powder, formation of condensate or other similar drawbacks. The belt 57 or the wire 55 may be traversed by a suitable low-voltage electric current in order to obtain their heating through the Joule effect.

As shown in Figure 14, the transfer surface 37 and the decorating material 45 applied thereto are electrostatically charged with the same polarity. This solution enables a more precise transfer of the decorating material 45 to the surface 35. In fact, as soon as the particles of decorating material 45 are detached from the surface 37 through mechanical intervention of the separating means 55 they are induced to travel along a well defined trajectory 62 through the repulsive effect exercised by the surface 37. Furthermore, this solution makes it possible to operate at a greater distance D.

Obviously, in the invention numerous other modifications of a practical application nature of the constructional details can be made without thereby falling outside the protective scope of the inventive idea claimed below.

For example, the transfer of the decorating materials 39 from the high-speed surface 37 to the low-speed surface can be obtained in another manner, for example as provided for in IT MO2000A000117.

In the device shown in Figures 1 and 4 distributing means of decorating powders 8 and the relative recovery means of the excess decorating powders 8 can for example be substituted by the supply means provided for in IT13314624.

The surface 3, 37 can also be an elastomer or a soft silicone material, in this way the detachment of the decorating material 8, 39 can be encouraged by deformation of the surface 3, 37 caused by contact of the blade 14, or by a different deforming element.

The liquid 6, 41 applied to the surface 3, 37 can perform its temporary adhesive function by solidification on the surface 3, 37 without removal by evaporation. The liquid 6, 41 will thus be kept at the right temperature during the application phase, but during the inclusion phase of the powder 8, 39 will be solidified by lowering of the temperature before the phase of detachment from the transfer surface 3, 37. The decorating material 8, 39 will thus be transferred to the surface to be decorated 13, 35, together with the solidified liquid 6, 41. This solidification can be obtained either by heating of the liquid 6, 41 in the initial phase of application to the surface 3, 37 and/or by cooling in the final phase before transfer onto the surface to be decorated 13, 35.

This can also be applied to the example in Figure 5 in which the liquid phase L will not be removed but be solidified on the surface 3.

A different method, not shown, for achieving the removal of the liquid phase 6, 41, L and the consequent drying of the decorating material 8a, 28, 39 provides for the use of a microporous surface 3, 37 that acts by absorbing the liquid phase 6, 41 L by capillarity.

It is pointed out that the use of mechanical grazing means such as the blade 14, 46 enable an detachment of the material 8 and its deposition onto the surface to be decorated, which enables a high definition to be obtained. Furthermore, the detachment of the material 8 is substantially complete even at very high operating speeds 4, Ul, U3.

The invention may also be applied for surfaces 13, 35 to be decorated that are not only horizontal but also vertical or however slanted, i.e. in particular in the case of Figure 9. The force of gravity has little effect here, because the decorating material can be projected at high speed towards the surface 35 to be decorated. Furthermore the decorating material being in the wet state can remain firmly attached to the surface 35 even if the surface is arranged vertically. Cleaning means of the transfer surface 3, 37 may be provided, arranged downstream the transfer zone, in order to remove traces of non-transferred decorating material 8, if any. In addition, cleaning means without contact may be provided, advantageously cleaning means with a light air stream and/or suction, arranged downstream the inclusion zone of the powders 8 into the liquid 6, L, in order to remove fine particles of powder which may irregularly adhere in a precarious way to the surface 37.

In the examples shown in Figures 9, 10, 11 the agglomerates of decorating material 45 can be applied to the surface 37 in any known manner. For example, they can be projected onto this surface 37 by different sequentially located ink jet devices, each one of which projects an agglomerate (microdrop) of decorating material 45 (in suspension or in solution) of different colour.

The most widely varying systems of cleaning can be applied to the blade 14 that are able to prevent fouling and maintain efficiency. For this purpose, in addition to the systems of impulsive and ultrasonic vibration 19, 29 already disclosed, the following may be adopted: cleaning means by contact or with thin and intense air flow scanning along the blade 14, 46 that is able to occasionally intervene during downtime during the productive cycle; heating means for keeping the blade 14, 46 at a high temperature, for example 200 °C and above.

Claims

1. Method for transferring a decorating material (8, 24, 28, 39, 45) defining a pattern on a receiving surface (13, 35) comprising in sequence: applying said decorating material (8, 24, 28, 39, 45) to a transfer surface (3, 37) according to a prefiguration (7, 8a) of said pattern; making said transfer surface (3, 37) bearing said decorating material (8, 24, 28, 39, 45) face said receiving surface (13, 35) in such a way as to define a gap (D) between said transfer surface (3, 37) and said receiving surface (13, 35) ; detaching said decorating material (8, 24, 28, 39, 45) from said transfer surface (3, 37) by means of separating means (14, 46, 55, 57) materially arranged in said gap (D) ; - moving said decorating material (8, 24, 28, 39, 45) towards said receiving surface (13, 35) .

2. Method according to claim 1 further comprising moving said transfer surface (3, 37) along a circuit ^"path.

3. Method according to claim 1, or 2, wherein as said transfer surface (3, 37) is smooth, said detaching comprises stripping said transfer surface (3, 37) with grazing means (14, 46, 55, 57) .

4. Method according to any preceding claim, wherein said detaching occurs whilst said transfer surface (3, 37) is distanced from said receiving surface (13, 35) .

5. Method according to any preceding claim, wherein said applying comprises treating said transfer surface (3, 37) with said decorating material (28) in solution or suspended in a liquid (L) .

6. Method according to any preceding claim, wherein said applying comprises treating with a liquid (6, 41, L) zones of said transfer surface (3, 37) corresponding to said prefiguration (7, 8a) of said pattern.

7. Method according to any of claims 1 to 5, wherein said applying comprises treating with a liquid (6, 41, L) said transfer surface (3, 37) in a substantially uniform manner.

8. Method according to any of claims 5 to 7, wherein said treating comprises using a computer-controlled ink jet device (5) .

9. Method according to any of claims 5 to 8, wherein said treating comprises using a matrix (21, 26) .

10. Method according to any of claims 5 to 9 and further comprising including in said liquid (6, 41, L) said decorating material (8, 24, 28, 39, 45) on said transfer surface (3, 37) .

11. Method according to any of claims 5 to 10 and further comprising, before said detaching, removing said liquid (6, 41, L) from said transfer surface (3, 37) by evaporation.

12. Method according to any of claims 5 to 11 and further comprising, before said detaching, solidifying said liquid (6, 41, L) on said transfer surface (3, 37) .

13. Method according to any of claims 5 to 12 wherein said detaching comprises detaching said decorating material (8, 24, 28, 39, 45) together with said liquid (6, 41, L) .

14. Method according to any preceding claim, and further comprising moving said transfer surface (3, 37) at a speed (Ul) that is greater than the speed (U3) of said receiving surface (13, 35) .

15. Method according to claim 14, wherein the ratio (U1/U3) between said speed (Ul) of said transfer surface (3, 37) and said speed (U3) of said receiving surface (13, 35) is comprised between the values 1,5 and 20.

16. Method according to any preceding claim, wherein said applying comprises applying said decorating material (8, 24, 39) in the form of distinct agglomerates (8a, 28, 45) selected from at least two different types of said decorating material (8, 24, 39) .

17. Method according to claim 16, and further comprising joining said distinct agglomerates (8a, 28, 45) on said receiving surface (13, 35) .

18. Method according to any preceding claim, wherein said applying comprises applying said decorating material (8, 24, 39) in the form of a thin layer (8a, 28, 39, 45) and said transferring comprises thansferring said decorating material in the form of a layer (8, 22, 44, 47) with a thickness (SI, S2, S4) significantly higher than the thickness (S3) of said thin layer (8a, 28, 39, 45) .

19. Method according to any preceding claim, wherein said moving comprises making said decorating material (8, 24, 28, 39, 45) move along a trajectory grazing deviator means (14, 29, 48) with interposition of an air cushion (48, 49) .

20. Method according to any preceding claim, wherein said moving comprises accelerating said decorating material (8, 24, 28, 39, 45) with fluid-flow (P, 34) propulsion means (32, 33, 53, 54).

21. Method according to any preceding claim, comprising make said separating means (14, 46) and/or deviators (14, 46, 55, 57) vibrate.

22. Method according to any preceding claim, and further comprising moving said separator means (14, 46, 55, 57) parallely to their longitudinal axis.

23. Method according to claim 22, and further comprising moving said separator means (14, 46, 55, 57) parallely to their longitudinal axis only during inactive phases of said separator means (14, 46, 55, 57).

24. Method according to any preceding claim, and further comprising rotating said separator means (14, 46, 55, 57) around a longitudinal axis thereof.

25. Method according to any preceding claim and further comprising magnetically attracting said separator means (14, 46, 55, 57) toward said transfer surface (3, 37) .

26. Method according to one of preceding claims, wherein said moving comprises acting on said decorating material (8, 24, 28, 39, 45) by means of electrostatic forces .

27. Decorating apparatus (1) for transferring a decorating material (8, 24, 28, 39, 45) defining a pattern onto a receiving surface (13, 35) comprising: a transfer surface (3, 37) provided with at least a portion facing said receiving surface (13, 35) in such a way that a gap (D) is defined between said transfer surface (3, 37) and said receiving surface (13, 35) ; applying means (5, 9, 11, 21, 26) suitable for applying said decorating material (8, 24, 28, 39, 45) onto said transfer surface (3, 37) according to a prefiguration (7, 8a) of said pattern; separating means (14, 46) materially arranged in said gap (D) and suitable for detaching said decorating material (8, 24, 28, 39, 45) from said transfer surface (3, 37).

28. Decorating apparatus (1) according to claim 27, wherein said transfer surface (3, 37) is movable along a circuit path in an advance direction (4, Ul).

29. Decorating apparatus (1) according to claim 27 or 28, wherein said transfer surface (3, 37) is smooth.

30. Decorating apparatus (1) according to one of claims 27 to 29, wherein said separating means comprises grazing means (14, 46, 55, 57) .

31. Decorating apparatus (1) according to claim 30 wherein said grazing means comprises a blade (14, 46, 57) .

32. Decorating apparatus (1) according to claim 31, wherein said blade (14, 46, 57) has a curved profile with concavity turned towards said transfer surface (3, 37).

33. Decorating apparatus (1) according to one of claims 27 to 32, wherein said separating means (14, 46, 55, 57) cooperates with vibration promoting means (19, 20) .

34. Decorating apparatus (1) according to one of claims 27 to 33, wherein said separating means (14, 46, 55, 57) cooperates with deviating means (29, 48, 51, 53, 54) .

35. Decorating apparatus (1) according to one of claims 27 to 34, wherein said separating means (14, 46, 55, 57) and/or said deviating means (29, 48, 51, 53, 54) comprise materials (48) with water-repellent properties .

36. Decorating apparatus (1) according to one of claims 27 to 35, wherein said separating means (14, 46, 55, 57) and/or said deviating means (29, 48, 51, 53, 54) comprise conduits (32, 33, 49, 53, 54) designed for the passage of pressurised fluid.

37. Decorating apparatus (1) according to one of claims 27 to 36, wherein said separating means (14, 46, 55, 57) and/or said deviating means (29, 48, 51, 53, 54) comprise an air-cushion sliding surface (48) .

38. Decorating apparatus (1) according to one of claims 27 to 37, wherein said separating means (14, 46, 55, 57) and/or said deviating means (29, 48, 51, 53, 54) comprise a wedge-shaped protuberance (51) projecting towards said receiving surface (13, 35) .

39. Decorating apparatus (1) according to one of claims 27 to 38, wherein said separating means (14, 46, 55, 57) and/or said deviating means (29, 48, 51, 53, 54) comprise heating means.

40. Decorating apparatus (1) according to one of claims 27 to 39, wherein said transfer surface (3, 37) is a chromed surface.

41. Decorating apparatus (1) according to one of claims 27 to 39, wherein said transfer surface (3, 37) comprises elastomeric material.

42. Decorating apparatus (1) according to one of claims 27 to 41, wherein said transfer surface (3, 37) comprises silicone material.

43. Decorating apparatus (1) according to one of claims 27 to 42, wherein said transfer surface (3, 37) cooperates with thermal control means (12) .

44. Decorating apparatus (1) according to one of claims 27 to 43, wherein said transfer surface (3, 37) is the surface of a cylinder (2) .

45. Decorating apparatus (1) according to one of claims 27 to 43, wherein said transfer surface (3, 37) is the surface of a belt (36) .

46. Decorating apparatus (1) according to one of claims 27 to 45, wherein said applying means (5, 9, 11, 21, 26) comprises ink jet devices (5) turned towards said transfer surface (3, 37).

47. Decorating apparatus (1) according to one of claims 27 to 46, wherein said applying means (5, 9, 11, 21, 26) comprises matrix means (21, 26) cooperating with said transfer surface (3, 37).

48. Decorating apparatus (1) according to one of claims 27 to 47, wherein said applying means (5, 9, 11, 21, 26) comprises decorating powder distribution means (8) arranged downstream of said matrix means and/or of said ink jet devices (5) .

49. Decorating apparatus (1) according to one of claims 27 to 48, wherein said transfer surface (3, 37) cooperates with movement means suitable for moving it at a speed (Ul) that is significantly greater than the speed (U3) of said receiving surface (13, 35) .

50. Decorating apparatus (1) according to one of claims 27 to 49, wherein said transfer surface (3, 37) cooperates with a plurality of said applying means (5, 9, 11, 21, 26) , each one of which is suitable for applying a different type of decorating material (39b, 39c, 39d, 39e) .

51. Decorating apparatus (1) according to one of claims 27 to 50, an further comprising at least one treatment station (40) for fixing said decorating material (8, 24, 39, 39b, 39c, 39d, 39e) on said transfer surface (3, 37) .

52. Decorating apparatus (1) according to one of claims 27 to 51, and further comprising moving means (55a, 58) suitable for moving said separating means (14, 46, 55, 57) parallel to a longitudinal axis thereof.

53. Decorating apparatus (1) according to one of claims 27 to 52, wherein said separating means (14, 46, 55, 57) may be wound on moving means (55a, 58) .

54. Decorating apparatus (1) according to one of claims 27 to 53, and further comprising suitable for rotating said separating means (14, 46, 55, 57) around a longitudinal axis thereof.

55. Decorating • apparatus (1) according to one of claims 27 to 54, and further comprising magnetic attraction means (56, 61) suitable for promoting contact of said separating means (14, 46, 55, 57) with said transfer surface (3, 37) .

56. Decorating apparatus (1) according to one of claims 27 to 55, wherein said separating means (14, 46, 55, 57) comprises a belt (57) having an arched cross section with concavity turned to said transfer surface (3, 37) and both longitudinal edges in contact with said transfer surface (3, 37) .

57. Decorating apparatus (1) according to one of claims 27 to 56, and further comprising means for electrostatically charging said transfer surface (3, 37) and said decorating material (8, 24, 28, 39, 45).