EP4759438A1

EP4759438A1 - Method and apparatus for generating textures

Info

Publication number: EP4759438A1
Application number: EP24383364.7A
Authority: EP
Inventors: Jesus Francisco Barberan Latorre
Original assignee: Barberan SA
Current assignee: Barberan SA
Priority date: 2024-12-12
Filing date: 2024-12-12
Publication date: 2026-06-17
Also published as: WO2026125790A1

Abstract

Texture generating process and system (3). Radiation curing by polymerisation is applied to a base layer (cb) differentially in zones (7, 7', 7") in which curing radiation is inhibited with respect to zones (8) laterally adjacent to the inhibition zones (7, 7', 7"). Textures (3) comprise cavities (4) which are formed by the removal of removable material from the base layer (cb) in the inhibition zones (7, 7', 7‴), in which the base layer (cb) has a substantially lower degree of curing than in the respective adjacent zones (8). The invention is characterized in that the base layer (cb) is spread over a separation layer (cs, cs', cs"), so that, when the removable material is removed, it is substantially separated out through the interface between the base layer (cb) and the separation layer (cs, cs', cs").

Description

OBJECT OF THE INVENTION

The present invention relates to a process and a system for generating textures, that is embossed surfaces, which can be applied to substrates such as, for example, panels or cardboard. The invention may for example be applied to floor panels, coverings, furniture, packaging, etc.
More specifically, the invention relates to making improvements in the generation of textures by digital printing, and in particular inkjet printing.

BACKGROUND TO THE INVENTION

Processes and systems for generating textures by digital printing are well known in the prior art.
Patent document WO 2010070485 A2 discloses a process for generating indented textures by means of inkjet printing, in which droplets of print are deposited on a resin base layer which can be solidified by curing radiation to create cavities.
According to this process, the droplets of print are configured to inhibit curing radiation, so that the cavities are formed by the removal of removable material from the base layer in the inhibition zones, for example by brushes. The material can be removed because in such zones the extent of solidification by curing is less than in laterally adjacent zones.
To inhibit the curing radiation the droplets of print may incorporate a product inhibiting curing radiation which physically inhibits the curing radiation either by wholly blocking or masking the radiation, or by partly blocking or filtering the radiation.
The solidification gradient that occurs at the interface between the inhibition zones and adjacent zones is associated with a difference in cohesion forces between the two zones, which, when the material is removed, for example by the mechanical drag of brush bristles, tends to cause the inhibition zones and the adjacent zones to separate from each other laterally at the interface between the zones.
This type of process for generating textures, in which cavities are formed by the removal of removable material from the base layer, has useful advantages, largely due to the fact that the processes can be performed by inkjet printing. The latter's flexibility, precision and speed, as well as its ability to produce textures of high mechanical strength and chemical resistance, are outstanding.
Also this type of process makes it possible to generate visual, tactile and matt textures depending on the depth of the inhibition zones and the amount of material removed, allowing micrometre-sized textures in particular to be generated.
In this respect visual textures are considered to be those whose relief can be distinguished with the naked eye, in particular by having cavities with a depth of the order of 100 microns or more. Tactile textures are considered to be those which can be distinguished by touch, in particular by having cavities with a depth of the order of 10 to 100 microns. Matt textures are considered to be those which can be distinguished visually by their degree of gloss, in particular by having cavities with a depth of the order of 10 microns or less.
However, known processes of this type have the disadvantage that because the material that can be removed from the base layer in the inhibition zones must have a lower degree of solidification than in the adjacent zones in order that it can be removed, it is difficult to remove the material when the curing radiation has been applied beyond a certain degree of solidification of the base layer.
The removal of insufficiently solidified removed material results in the residue consisting of this material being difficult to handle when because of its tack it adheres to the surfaces of the equipment for removing the material, such as the surfaces of the brush bristles or the extraction ducts for the material removed.
Another disadvantage of known processes of this type is that it is difficult to obtain textures with deep cavities, as the removable material tends to separate out at an intermediate depth and at some distance from the sides within the inhibition zone. This is because the adhesion forces between the masking zones and the adjacent zones at the interface tend to be stronger than the cohesive forces of the removable material on account of the viscoelastic properties of the removable material.
Patent document WO 2020039361 A1 also discloses a process for generating cavity textures by means of inkjet printing, in which droplets of print which can be solidified by curing radiation to create the cavities are deposited on a base layer of resin.
According to this process, the droplets of print are configured to inhibit curing. That is, in contrast to the process described above, in this process the droplets of print inhibit curing of the base layer itself, not necessarily the curing radiation which causes curing. For this purpose the droplets of print include agents that inhibit curing, that is chemical substances that slow down or impede the polymerisation curing reactions.
The cavities are formed by removing removable material from the base layer in the zones where the droplets of print penetrate, for example using brushes. The material can be removed because in such zones it has a lower degree of solidification due to curing than in the zones laterally adjacent to them.
This patent document also discloses other processes related to the above, insofar as they relate to facilitation of the removal of material to generate texture.
According to one such process the droplets of print are configured to reduce the glass transition temperature (Tg) of the base layer at room temperature. For this purpose the droplets of print incorporate monomers that have a low Tg at room temperature.
According to another such process the droplets of print incorporate non-miscible or partly miscible liquids, such as water or PEG-acrylate, in the resin.
However the processes disclosed in this second patent document mentioned have the disadvantage that they only allow shallow cavities to be obtained, as they are limited by the depth to which the droplets of print penetrate the base layer when deposited.
In order to be able to increase the depth of the cavities, the patent document itself proposes that droplets of print having a surface tension that is sufficiently different from the surface tension of the base layer resin should be used. The patent document also proposes to this end that the impact velocity of the droplets of print on the base layer should be increased.
However, the processes disclosed in this second patent document mentioned do not alone make it possible to obtain cavities with the depths allowed by the process disclosed in the first patent document mentioned, even with the measures it discloses to increase the depth to which the droplets of print penetrate.
The object of the present invention is to overcome the limitations of the prior art, especially by allowing textures to be produced with cavities of different depths, in particular deeper cavities, facilitating removal of the material removed as well as its subsequent handling, especially by avoiding the accumulation of residue of such material on the surfaces of the means for removal of the material, such as surfaces of the bristles of the brushes or the extraction ducts for the material removed.

EXPLANATION OF THE INVENTION

In order to achieve the object mentioned, and the additional technical advantages that may be derived from this description, the invention provides a process for generating textures comprising cavities formed by the removal of removable material from a base layer.
For this purpose curing radiation which acts differentially in zones in which the curing radiation is inhibited in contrast to zones laterally adjacent to the inhibited zones is applied to the base layer, which can be cured by polymerisation through curing radiation.
Texture cavities are formed by removing removable material from the base layer in the inhibition zones in which the base layer has a substantially lower degree of curing than in the respective adjacent zones.
In accordance with the invention the base layer is spread over another layer, here referred to as the separation layer. It is called this because the layer serves to help separate the removable material from the base layer, as is explained below. The separation layer can also be cured by polymerisation through radiation curing, and when the base layer is spread over the separation layer, it is partly cured.
Thus, according to the invention, at least one inhibition zone reaches the separation layer. The curing radiation acts differentially on the separation layer in said at least one inhibition zone with respect to its adjacent zones; in particular, the curing radiation applied to the base layer acts differentially on said at least one inhibition zone. Thus when the removable material is removed it is substantially separated out at the interface between the base layer and the separation layer, said interface having substantially less adhesion due to polymerisation in the at least one inhibition zone than in the respective adjacent zones.
In the context of the present invention 'inhibition zones' mean zones in which the curing radiation is inhibited; these may not necessarily be part of only the base layer, but also the separation layer, other lower layers or even the substrate on which these layers are spread and, in general, any part of the finished product after application of the process.
Also, the existence of an 'inhibition zone' is by definition not limited to the time interval in which inhibition of the radiation occurs, but may also be understood to be an 'inhibition zone' in a broad sense, as the zone in which the inhibition of has occurred or will occur because of application of the process. For example, at the time when the base layer has not been spread and therefore inhibition has not yet occurred, conceptually part of the inhibition zone may extend into the separation layer in which radiation is subsequently inhibited.
The material of the base layer can be removed in inhibition zones because in these zones the base layer has a degree of solidification due to curing that is substantially lower than in the adjacent zones of the base layer.
In this respect, the part removed can be removed from a base layer environment that is in a, for example, highly gelled state, while the rest of the base layer around it may be solid. For this purpose the means for removing the removable material, for example brushes, act by dragging off the highly gelled part, while the rest of the base layer remains fixed.
In contrast to the prior art, the existence of a separation layer according to the invention also makes it possible to separate or peel off the removable material, substantially at the interface between the base layer and the separation layer, thus facilitating removal of the removable material.
For this purpose the invention makes use of the creation of differential adhesion at the interface between the base layer and the separation layer, so that the adhesion produced in the inhibition zones which reach the separation layer is substantially lower than in the respective laterally adjacent zones of the separation layer.
This creation of adhesion is generally due to two main natural mechanisms relating to the process of polymerising polymer materials, in particular cross-linking, as explained below.
Polymer materials that can be used in the base layer and the separation layer are, for example, resins that can be cured by light, in particular by UV radiation. For example, epoxy acrylates, urethane acrylates, polyester acrylates, etc.
The first mechanism is based on the fact that the application of curing radiation to the separation layer means that the free radicals of polymer chains available for cross-linking or interlinking with other polymer chains decrease as the degree of curing increases.
The second mechanism is based on the fact that the application of curing radiation to the interface between the base layer and the separation layer, when the base layer is spread over the separation layer, results in the free radicals of available polymer chains binding to each other, forming bonds, that is cross-linking or interlinking the polymer chains, as the degree of curing increases.
The application of curing radiation to the separation layer, in particular before spreading of the base layer, affects the presence of free radicals to form available bonds on the surface of the separation layer. As the degree of curing increases, the presence of free radicals decreases.
The application of curing radiation at the interface between the base layer and the separation layer affects the formation of bonds between the base layer and the separation layer due to the available free radicals. Increasing the degree of curing increases the number of bonds formed from the free radicals present.
Preferably, the invention envisages that the curing radiation acting differentially on the base layer also acts differentially on the separation layer for at least part of the time during which the separation layer is still partly cured.
A sufficiently high degree of curing of the separation layer, before spreading of the base layer, allows the presence of available free radicals to be low and therefore the application of differential curing radiation at the interface to be relatively more effective.
Vice versa, a lower degree of curing of the separation layer allows the presence of available free radicals to be greater, and therefore more differential curing radiation energy to be required at the interface to produce separation at the interface.
Likewise, preferably, the invention also envisages that, before spreading of the base layer, the curing radiation acts differentially on the separation layer in zones where curing radiation is promoted, substantially coinciding with the at least one inhibition zone at said interface, with respect to its adjacent zones. In particular, it is contemplated that the separation layer is fully cured selectively in such promotion zones by curing radiation, before the base layer is spread.
Thus the separation layer is partly cured before the base layer is spread, not necessarily along the entire length of the separation layer. In particular, the separation layer may be fully cured exclusively in the promotion zones and partly cured in their adjacent zones. In particular, for example, the separation layer may be partly cured throughout the entire separation layer before applying differentially curing radiation in the promotion zones.
By promoting the curing radiation in the promotion zones of the separation layer, before the base layer is spread, the effect of decreasing the presence of free radicals within this zone to form bonds at the interface with the base layer is intensified. This effect can even be maximised by fully curing the separation layer selectively or exclusively in these promotion zones.
This differential action of curing radiation in the promotion zones may be complementary or alternative to the action of the differentially curing radiation in the inhibition zones of the interface between the base layer and the separation layer when the separation layer is partly cured.
In the light of the technical rules mentioned and the explanation in this description, a person skilled in the art will be able set precise limits for implementing the invention according to the results desired, so process design variables may be adjusted without excessive experimentation. Process design variables in accordance with the invention are, for example, those indicated below.
The nature of the means for removing removable material from the base layer, such as, for example, brushes, influences the tearing force exerted on the material in order to remove it. In accordance with the invention, any means for removing removable material may be used, including brushing means, contact transfer means, in particular in the form of contact transfer rollers, suction means, blowing or fluid drive means (by compressed air, water jet, sand jet, etc.), etc.
The pressure exerted on the base layer by the means to remove the removable material, in particular, for example, due to the tractive force of the brushes, may also be regulated and can therefore be adjusted, influencing the design of the process according to the invention.
Contact transfer means, in particular in the form of rollers, are disclosed in patent document WO 2022180292 A1 . In particular, a contact transfer roller may, for example, be used in a first step for the removal of material to remove a more liquid or less gelled part of the removable material, followed by a brush to remove the rest of the material down to the separation layer. In general, in accordance with the invention, any transfer means may be used, in particular transfer rollers of any type, for example absorbent rollers.
The specific composition of the separation layer also influences the radiation energy required to obtain a particular degree of curing or a particular presence of free radicals on the surface to which the curing radiation is applied. For example, when using a light-curable resin, the addition of photoinitiators generally allows the rate of curing to be increased.
Likewise the specific composition of the base layer influences the curing of both the base layer and the separation layer. For example, when using a UV-curable resin, the addition of photoinitiators generally allows the rate of curing and the depth at which the radiation acts to be increased.
The thickness of the base layer also influences curing of both the base layer and the separation layer. The greater the thickness of the base layer, that is the depth at which the separation layer is located, generally the less radiation energy reaches this layer.
Furthermore the way in which the differential curing radiation is applied to the base layer also influences the curing of both the base layer and the separation layer. In this respect, for example, the degree of inhibition of the radiation, the amount of energy radiated, the radiation power, the type of radiation, the processing speed, etc., are factors that can have an influence.
For example, in relation to the type of radiation used for UV-curable resins, Ga lamps allow curing to a deeper depth than Hg lamps.
Specifically, the invention makes it possible for the material of the base layer to be easily removable to form the cavities of the textures, it being easy to detach from its lateral surfaces because of the difference in the state of solidification and from its lower surface on account of the lesser adhesion produced with the separation layer.
In particular, the removal of the base layer material for deeper cavities is made easier in comparison with the processes known in the prior art. In this respect, the process according to the invention in particular makes it possible to obtain more precise textures as it allows no more material than is necessary to be removed from the base layer.
Also, since the cavities thus obtained reach all the way through the base layer to the separation layer, cavities with a precise depth can be obtained, since this is equivalent to the thickness of the base layer.
In any event the invention envisages that the texture may include cavities of lesser depth in addition to the cavities that reach the separation layer, depending on the depth of the respective inhibition zones. In this way, depending on the depth, visual, tactile and/or matt textures can be obtained on the same surface of the base layer, providing a wide variety of texturing ranges.
The invention is also compatible with obtaining textures consistent with other patterns, for example decorative or coloured patterns. In particular, the base layer and the separation layer may be transparent and be spread over a decoration layer provided with decorative patterns, so that the generated textures are consistent with or correspond to these patterns.
The configuration of texture layers consistent with decoration layers also offers the possibility of producing a wide variety of patterns, for example patterns imitating natural patterns such as wood grain.
A number of definitions and clarifications of terms used in this description are provided below. The terms used should in principle be interpreted according to their common technical meaning and in a broad manner, allowing for a flexible understanding appropriate to each associated concept.
In the context of the present invention, "inhibition of curing radiation " includes both the concept of "decrease in applied radiation energy" and the concept of "suppression of applied radiation energy" in inhibition zones, with respect to their laterally adjacent zones.
In particular, the term "inhibition" of radiation includes both "masking" or total blocking of radiation and "filtering" or partial blocking of radiation.
Also, in the context of the present invention, "promotion of curing radiation" includes the concept of "increasing applied radiation energy" in promotion zones, with respect to their laterally adjacent zones. In particular, the term "promotion" of radiation includes the concept of "concentration" of radiation.
'Curing radiation' means in particular electromagnetic curing radiation, for example UV radiation. The term 'curing' includes the concept of 'polymerisation', that is the formation of polymer chains (polymerisation per se) and of cross-links between polymer chains (cross-linking).
The "degree of curing" of a material is the degree of transformation that the material has acquired, quantified with respect to its total curing, in which the monomers of the material have been totally transformed into polymer chains. Thus, for example, a degree of curing of 100 % corresponds to a fully cured material and 0 % to a material in the state of monomer.
In the context of the present invention, the concept of "degree of curing" includes the concept of "degree of solidification". The "degree of solidification" of a material can be used to quantify its solidification with respect to maximum solidity on a preset scale. Thus, a degree of solidification of 100 % corresponds to a material that is substantially solid and 0 % to a material that is substantially liquid.
As the degree of curing increases, the degree of solidification of a material increases. Normally use is made of polymer materials in which the glass transition temperature (Tg) of the fully cured material is higher (preferably 10-20° higher) than the ambient temperature for use of the final product, so the degree of curing corresponds to the degree of solidification.
The degree of curing or solidification may be measured with reference to a scale of applied radiation energy per unit area, considering, for example, the power of the curing radiation being radiated and the processing speed.
A hardness scale may also be used to measure degree of solidification. For example, using an H-B scale indentation pencil, where 6H corresponds to the maximum hardness (degree of solidification 100 % or substantially solid) and 3B the minimum hardness (degree of solidification 0 % or substantially liquid).
The degree of solidification may also be observed qualitatively. For example, a distinction may be made between liquid (L), gel (G), solid gel (G+) or solid (S) states. A material in the gel state (G) is such that it can be touched without being dragged, in contrast to the liquid state (L), which can be dragged when touched. A material in the solid gel state (G+) would be in an intermediate state between gel (G) and solid (S). Thus, a liquid state (L) would be approximately equivalent to a degree of solidification of 0-33 %, a gel state (G) to 34-66 %, a solid gel state (G+) to 67-99 % and a solid state (S) to 100 %.
In this sense, measuring or observing the degree of curing or solidification, for example, as indicated above, will especially allow those skilled in the art to carry out tests to adjust process design variables.
The following clarifications need to be made with regard to the previously mentioned descriptive terms referred to below that appear throughout this description.
The term "at least one", referring for example to "at least one inhibition zone", includes, in particular, "all", that is, for example, "all inhibition zones".
The term "sufficiently", for example referring to "sufficiently high", includes, in particular, "substantially" or at least the value referred to, that is also any higher value.
The term "on/to", for example, referring to "on/to the separation layer", includes, in particular, "directly on/to" or "substantially on/to".
Returning to the technical explanation of the invention, additional preferred embodiments are explained below. In these embodiments the process according to the invention is applied including features complementary to those described so far which bring additional advantages.
Preferably, according to the invention it is contemplated that, when removing the removable material, the material removed has a degree of curing, in particular a degree of solidification, that is sufficiently high to substantially prevent it from adhering to surfaces of means for removal of the removable material. These surfaces may be, in particular, the surfaces of the bristles of removing brushes, the surfaces of ducts for the extraction of material removed, etc.
In particular, it is envisaged that, when the removable material is removed from the base layer the removed material will have a degree of solidification due to curing which is substantially greater than or equal to 70 %, preferably 80 %, more preferably 85 %.
On the other hand, when removing the removable material from the base layer, the material removed will preferably have a degree of solidification lower than a maximum degree of solidification which would prevent it from being conveniently removed because of excessive cohesion in the base layer. In particular, it is conceivable that the material removed will have a degree of solidification due to curing that is substantially less than 100 %, preferably less than 90 %, more preferably less than 85 %.
Qualitatively, it may be seen that the removed material with a degree of solidification between 80 % and 85 % will have a rubbery appearance, similar to a residue left on a piece of paper after erasing a pencil line with an eraser.
Advantageously, the invention thus makes it possible to generate textures without soiling the surfaces of the means for removing the removable material, unlike processes for the generation of textures, especially of deeper textures, in the prior art, which tend to leave sticky residues on surfaces that are difficult to clean.
Furthermore, once the material removed has been removed, the invention has the advantage that the residue consisting of such material is easier to store and process, given its more solid state. In general, the removed material according to the invention can be recycled or reused.
In this respect, processes and systems which apply additional curing radiation to the surfaces of the means for removing removable material to solidify the residues and thus facilitate their cleaning from these surfaces are known in the prior art.
The invention has the advantage that these processes or systems can be dispensed with, since the removable material can be removed directly already in a sufficiently solid state. However, these processes and systems may also be applied to the present invention.
However, in the processes for the generation of textures in the prior art it is not possible to remove the removable material when it is as cured or solidified as it can be when the process according to the invention is applied. This is because, in the absence of a separation layer configured as in the invention, the only mechanism for removing the base layer material is by softening the material in the inhibition zone with respect to its laterally adjacent zones, since its hardening or solidification inherently prevents its removal.
Various embodiments associated with the action of curing radiation by differential polymerisation are described below. According to the invention, the curing radiation may act differentially on the base layer and the separation layer.
Preferably the invention relates to the selective deposition of a product that inhibits curing radiation on the inhibition zones and/or on the zones adjacent to the promotion zones. Alternatively or additionally, the invention relates to the selective deposition of a product that promotes curing radiation onto the promotion zones and/or the zones adjacent to the inhibition zones.
'Product inhibiting radiation' means any product which, when placed on the inhibition zones or zones adjacent to the promotion zones, inhibits, in particular masks or filters radiation in said zones.
'Product promoting radiation' means any product which, when placed on the promotion zones or zones adjacent to the inhibition zones, promotes, in particular concentrates, radiation in those zones.
On the other hand, the invention also envisages that the product inhibiting curing radiation deposited on the inhibition zones additionally comprises an agent inhibiting curing and/or an agent lowering the glass transition temperature (Tg). This helps to reduce the degree of curing, in particular the degree of solidification or softening, of the removable material in the inhibition zones of the base layer, thus facilitating its removal and withdrawal.
In this respect, it is also conceivable that the inhibiting product may be configured to cure through radiation curing, to be immiscible or partly miscible in the base layer and/or to sublimate. These options additionally allow for easier removal and withdrawal of the removable material in a more solid state.
The promoting product and/or inhibiting product deposited on the separation layer may be removed by suitable means for removing material before the base layer is spread and after application of the corresponding curing radiation.
According to other embodiments, the invention also envisages that, before the base layer is spread, a curing radiation polymerisation barrier product is deposited on the separation layer in zones substantially coinciding with the at least one inhibition zone.
Polymerisation barrier product' means any product which by itself, and/or in combination with other products, is incapable of polymerisation, and/or renders it impossible. The polymerisation barrier product may comprise, or consist of, in particular, an agent inhibiting curing and/or an agent inert to curing. For example, water or specific solvents may be used.
In this way, once the base layer is spread over the separation layer, a barrier is created at the interface, where the curing radiation acts differentially in the inhibition zones where the barrier product is deposited in comparison to the zones adjacent to it, resulting in reduced adhesion due to polymerisation in these zones.
On the other hand, the deposited product inhibiting radiation, product promoting curing radiation and/or polymerisation barrier product may be configured so that once deposited they remain on the layer, are mixed with the layer material or are introduced into the layer, base layer or separation layer as appropriate. This may be influenced, for example, by selecting a chemical composition of the droplets of print as well as of the base layer, in particular to provide a suitable surface tension and/or viscosity.
Likewise this can also be influenced, for example, by whether the inhibiting product can be cured, since a higher degree of solidification of the droplets of print can encourage the droplets to remain on the surface of the base layer, whereas in a more liquid state they tend to enter the base layer.
In particular a greater or lesser barrier effect can be achieved, depending on the chosen configuration of the polymerisation barrier product in terms of its ability to remain on, mix with or be introduced into the separation layer once deposited.
For example, if the barrier product consists of an agent inert to curing, a higher barrier effect can be achieved if it remains on the surface of the separation layer. In this case, once the base layer is spread over the separation layer, the barrier product will be embedded between the two layers, breaking the adhesive bridge between the two brought about by polymerisation.
On the other hand, for example, if the barrier product consists of an agent inert to curing and is mixed with the separation layer, breakdown of the adhesive bridge between the two layers brought about by polymerisation will be reduced, as the barrier product is dispersed within the separation layer.
Also, for example, if the barrier product consists of an agent inhibiting curing and is mixed with the separation layer, reduced breakdown of the adhesive bridge may also be expected, because of the inhibition of curing caused by the barrier product in the mixing zone.
The invention also envisages that the product promoting radiation and the polymerisation barrier product can be combined on the same separation layer. In particular, a barrier product may be a promoting product at the same time.
Preferably, according to the invention, the product inhibiting radiation, the product promoting radiation and/or the polymerisation barrier product are deposited in the form of droplets of print by means of inkjet printing. Inkjet printing provides flexibility, precision and speed for the process.
Digital inkjet printing also makes it easier to obtain cavities having predetermined levels of depth by selecting the volumes of droplets of print per printing dot and/or the separation between printing dots. Generally, the greater the droplet volume per printing dot, the greater the depth of the inhibition or promotion zone and, therefore, the greater the depth of the cavities obtained may be. Also, generally, the greater the separation between printing dots, the smaller the depth of the inhibition or promotion zone and, therefore, the smaller the depth of the cavities obtained may be.
As described above, the texture generation process according to the invention allows textures to be obtained with cavities that can span the entire thickness of the base layer in depth. In particular, base layers with a thickness 100 microns or more, preferably 150 microns or more, and more preferably 200 microns or more may be used.
A finished product made in accordance with the invention comprises a substrate on which the texture is generated through a process as described in this description.
According to another aspect, the invention also provides a system for generating textures suitable for the conduct of a process as described in this description.
According to the invention, the system comprises means for spreading a base layer, means for applying curing radiation configured to act differentially on the base layer and means for removing removable material from the base layer.
Characteristically, the system comprises means for spreading a separation layer, means for applying curing radiation to the separation layer and a controller configured to implement such means (for spreading layers, for applying curing radiation and for removing material) by conducting a process according to one of the claims.
Preferably, said means for applying curing radiation which is configured so that the radiation acts differentially on the base layer comprises an inkjet printer, in particular a single-pass inkjet printer. For this purpose, the inkjet printer is configured to inject product inhibiting curing radiation onto the base layer.
The system benefits from the effects and technical advantages of the process according to the invention and, advantageously, allows it to be automated, in addition to enabling the generation of textures on substrates to be mass-produced.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below in greater detail in an illustrative and non-limiting manner, as well as with respect to a preferred embodiment by way of example, with reference to the accompanying drawings. In the drawings:

Figure 1 shows a representation of the digital information of an example texture which is to be generated.
Figure 2 shows a texture generated on the basis of the representation in figure 1, in plan view.
Figures 3 to 6 show a first embodiment of the texture in figure 2 according to the invention in cross-section views along A'-A' or B'-B'.
Figures 7 and 9 show a second embodiment of the texture in figure 2 according to the invention, seen in cross-section along A'-A'.
Figures 8 and 10 show a third embodiment of the texture in figure 2 according to the invention, seen in cross-section along A'-A'.
Figures 11 and 12 show a fourth embodiment of the texture in figure 2 according to the invention, seen in cross-section along A'-A'.
Figure 13 shows a fifth embodiment of the texture in figure 2 according to the invention, seen in cross-section.
Figure 14 shows a sixth embodiment of the texture in figure 2 according to the invention, seen in cross-section.
Figure 15 shows a curing diagram for three example embodiments of the process according to the invention, based on the embodiment in figure 14.
Figure 16 shows diagrammatically an example embodiment of a system according to the invention suitable for carrying out an example embodiment of the process based on figure 15.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows a representation of the digital information for an example texture (3) with cavities (4) which can be generated by a process or system (1) according to the invention. It is a matrix representation in which, for a given row and column, each cell corresponds to a pixel or unit of information about the depth of the cavities (4) in the texture (3) that is to be generated.
In this example, each pixel can have one of four possible values, where each value is assigned a level of the cavity depth in texture (3) which is to be obtained. These four values are: level 0 (the cell appears empty), level 1 (the cell appears with a circle of smaller diameter), level 2 (the cell appears with a circle of intermediate diameter) and level 3 (the cell appears with a circle of larger diameter).
Level 0 means no cavity (4), a higher level means a greater depth of the cavity (4) which is to be generated, ranging from a minimum depth (level 1) to a maximum depth (level 3) via an intermediate depth (level 2).
Figure 2 shows an example texture (3) generated on a substrate (2) based on the representation in figure 1. For simplicity of explanation, a texture (3) which has been made with a scaling of one pixel per dot is shown. Textures of greater or lesser precision may be obtained with a higher or lower number of pixels per dot, respectively.
When viewed along cross-section A'-A', generated texture (3) is that obtained for (imaginary) cross-section A-A in the representation in Figure 1. Similarly, cross-section B'-B' is that obtained for (imaginary) cross-section B-B in the representation in Figure 1.
Figures 3 to 6 refer to a first embodiment of the texture in figure 2.
On the one hand, figures 3 and 4 show different cross-sections of substrate (2), corresponding to A'-A' and B'-B' respectively, at an instant in time before the generation of texture (3), that is when the curing radiation acts differentially on the base layer (cb).
On the other hand, figures 5 and 6 show the true cross-sections of substrate (2), A'-A' and B'-B' respectively, that is when texture (3) has already been generated.
With reference to figures 3 and 4, as may be seen, in order to reach the instant in time represented in the figures, the stages of spreading a separation layer (cs) onto the substrate (2), spreading a base layer (cb) onto the partly cured separation layer (cs) and the application of product (5) inhibiting curing radiation onto the base layer (cb) have previously been carried out.
The inhibiting product (5) can be applied, for example, by inkjet printing, in particular by means of a single-pass inkjet printer. In such a case, in particular, a desired quantity of inhibiting product (5) can be distributed onto the base layer (cb), in particular by choosing the volume of print droplet ejected per printing dot and/or the spacing between printing dots.
The distribution of the amount of inhibiting product (5), in particular as droplets of print, influences the shape and size of the zones (7, 7', 7") in which the curing radiation is inhibited.
As depicted in the figures, generally, through the intrinsic inhibiting effect of the inhibiting product (5), a larger amount of product (5) at one point produces deeper inhibition zones (7, 7', 7") and a wider dispersion of inhibiting product (5) around a point produces shallower inhibition zones (7, 7', 7").
Thus, in figures 3 and 4, inhibition zones (7) are the deepest, reaching the separation layer (cs) and even substrate (2). Inhibition zones (7') reach an intermediate depth and inhibition zones (7") the shallowest depth.
Inhibition zones (7, 7', 7") are laterally confined by their adjacent zones (8). Inhibition zones (7, 7', 7"), as well as adjacent zones (8), may extend into the base layer (cb) and even into lower layers or substrate (2).
The texture (3) already generated, with the cavities (4) formed may be seen in figures 5 and 6. In order to reach the instant represented in these figures from the instant represented in figures 3 and 4 following the process according to the invention, material has been removed from the base layer (cb), for example by brushing, resulting in the various cavities (4) after the curing radiation has been applied differentially to the base layer (cb). The removable material is removed on account of the effect of the lesser degree of curing or solidification in inhibition zones (7, 7', 7") in relation to the laterally adjacent zones (8) of the base layer (cb).
Characteristically, inhibition zones (7) extend to the separation layer (cs) and when material is removed from the base layer (cb) the material is substantially separated out at the interface between the base layer (cb) and the separation layer (cs).
When this material is removed, the interface between the base layer (cb) and the separation layer (cs) has substantially less polymerisation adhesion in the inhibition zone (7) than in the zones (8) adjacent to it, which facilitates detachment or separation of the base layer (cb) at the interface.
As may be seen in figures 3 and 4, in which inhibition zones (7, 7", 7'") have been delimited, the curing radiation acting differentially on the base layer (cb) also acts differentially on the separation layer (cs) during at least part of the time when the separation layer (cs) is still partly cured. In this way, the available free radicals cross-link at the interface to a lesser extent in inhibition zone (7) than in zones (8) adjacent to it.
Figures 7 and 9 relate to a second embodiment of the texture in figure 2 according to the invention.
On the one hand, figure 7 shows a cross-section of substrate (2) along A'-A' at an instant in time before the generation of texture (3), corresponding to when the curing radiation acts differentially on the base layer (cb).
On the other hand, figure 9 shows the actual cross-section of substrate (2), A'-A', that is when texture (3) has already been generated.
In contrast to the first embodiment, here the base layer (cb) comprises a plurality of base sublayers (cb1, cb2) spread one above the other. In the particular case of the embodiment shown there are two base sublayers (cb1, cb2) constituting the base layer (cb). Intermediate partial curing of the base layer (cb1) can take place between base layer (cb1) and base layer (cb2) in order to increase its cohesion and thus avoid a detrimental dragging effect on base layer (cb1) by base layer (cb2), in particular between any successive layers and especially with thicker layers.
This embodiment is advantageous in that it offers greater modularity when obtaining textures with base layers (cb) of different thicknesses. It also has the advantage of making it possible to produce base layers (cb) of greater thickness, as when base layer (cb) is spread it does not go over the edges of substrate (2), in addition to more precise thicknesses.
Figures 8 and 10 relate to a third embodiment of the texture in figure 2 according to the invention.
In contrast to the first or second embodiments, here a plurality of base layer (cbl, cbll, cblll) and separation layer (csl, csll, cslll) pairs are spread one above the other, so that different inhibition zones (7) reach respective separation layers (csl, csll, cslll). In the particular case of the embodiment shown, three base layer (cbl, cbll, cblll) and corresponding separation layer (csl, csll, cslll) pairs have been spread.
In particular, the spread of the individual layers involves the selective differential application of curing radiation with respect to each separation layer (csl, csll, cslll) and the base layer (cbl, cbll, cblll) immediately above it. In this respect it is envisaged that the material that can be removed from the immediately uppermost base layer can be removed together with the material from the other uppermost layers in inhibition zone (7).
Advantageously this embodiment makes it possible to obtain more precise levels of depth by being able to link them to corresponding base layer thicknesses, in particular to discrete values of levels of depth. In the particular case of the embodiment shown there are three discrete levels of depth, obtained for respective inhibition zones (7), according to their depth.
In particular, these second and third embodiments are compatible with each other, as each base layer (cbl, cbll, cblll) may comprise a plurality of base sublayers (cb1, cb2).
Figures 11 and 12 relate to a fourth embodiment of the texture in figure 2 according to the invention.
On the one hand, figure 11 shows a cross-section of substrate (2) along A'-A' at an instant in time before the spreading of base layer (cb), corresponding to when the curing radiation acts differentially on separation layer (cs).
On the other hand, figure 12 shows a cross-section of substrate (2) along A'-A' at an instant in time before the generation of texture (3), corresponding to when the curing radiation acts differentially on base layer (cb).
Before base layer (cb) is spread, curing radiation acts differentially on the separation layer (cs) in promotion zones (9), substantially coinciding with inhibition zone (7) at the interface between the base layer (cb) and the separation layer (cs).
The curing radiation acts differentially on the separation layer (cs) in promotion zone (9) in relation to zones (8) laterally adjacent to it. In this way the amount of free radicals available for cross-linking during the subsequent phase of binding with the base layer (cb) in promotion zones (9) is reduced in comparison with adjacent zones (8).
In this example promotion zones (9) are produced by depositing radiation promoting product (6) onto the separation layer (cs), for example by means of inkjet printing, in particular by means of a single-pass inkjet printer.
In this case the radiation promoting product (6) also behaves as a polymerisation barrier product, as for example it contains an agent inhibiting curing that acts on the material of the separation layer (cs) when mixed with it. Thus, as shown in figure 12, said product (6) is embedded between the separation layer (cs) and the base layer (cb) in a zone that substantially coincides with inhibition zone (7) at the interface, reducing adhesion due to polymerisation in said zone.
In particular, this fourth embodiment is compatible with any of the embodiments described above, since the method of decreasing adhesion at the interface in inhibition zones (7) with respect to zones (8) adjacent to them by the differential action of curing radiation in radiation promoting zones (9) and/or polymerisation barrier zones can be applied to interfaces between different base layers (cb, cbl, cbll, cblll) and separation layers (cs, csl, csll, cslll).
Figure 13 refers to a fifth embodiment of the texture in figure 2 according to the invention. The figure shows a cross-section of substrate (2) at an instant in time before the differential action of the curing radiation on the base layer (cb).
According to this embodiment, the separation layer (cs) incorporates reinforcing particles (pr) and/or thickening agents. In this way the cohesion of the separation layer (cs) can be increased when the base layer (cb) is spread.
Subsequent to the instant depicted in figure 13 the differential action of the curing radiation may, for example, take place as described for any of the above embodiments when the separation layer (cs) in such embodiments is arranged in this configuration.
In particular, this fifth embodiment is also compatible with any of the embodiments described above, as a separation layer (cs, csl, csll, cslll) configured in this way can be applied in any of them.
Figure 14 relates to a sixth embodiment of the texture in figure 2 according to the invention. The figure shows a cross-section of substrate (2) at an instant in time before the differential action of the curing radiation on the base layer (cb).
According to this embodiment, the separation layer (cs) is spread on substrate (2) through the intermediary of a decoration layer (cd) and a protecting layer (cp) for the decoration layer (cd). The decoration layer (cd) may, for example, be inkjet printed, in particular by means of a single-pass inkjet printer.
In accordance with the invention, any other arrangement of intermediate layers between a separation layer (cs) and substrate (2) is also possible. In general, the separation layer (cs) may be spread on substrate (2) directly or by means of at least one intermediate layer, which, for example, may be selected from at least one primer layer for decoration or texture layers, at least one decoration (cd) or texture layer, at least one protecting layer (cp) for decoration or texture layers and a combination of the above.
The differential action of the curing radiation subsequent to the instant depicted in figure 14 may, for example, take place as described for any of the above embodiments, by arranging intermediate layers between the respective separation layer (cs) and substrate (2).
In particular, this sixth embodiment is also compatible with any of the embodiments described above, as, in particular, a decoration layer (cd) and a protecting layer (cp) may be first applied to any of them.
Figure 15 shows a curing diagram for three example embodiments of the process according to the invention. Each of the example embodiments corresponds to a separation layer (cs, cs', cs") having different rates of curing.
By way of example, the example embodiments are based on an embodiment as shown in Figure 14, in association with any of the embodiments shown in figures 3 to 10 in which a product inhibiting curing radiation (5) is applied. In this respect, texture (3) is generated on a substrate (2) on which a decoration layer (cd) is applied. A protecting layer (cp) is spread on top of the decoration layer (cd). A separation layer (cs, cs', cs") is applied on top of the protecting layer (cp) and a base layer (cb) in which texture (3) is generated is applied on top of it.
The curing diagram shows the degree of curing or solidification of the different layers used (as a %) along the ordinate and time (in time units, t.u.) along the abscissa. Each layer (cd; cp; cs, cs', cs", cb) is represented by one graph. Three graphs, each of which relates to one of the three example embodiments, are shown for the separation layers (cs, cs', cs").
As may be seen, the graph for curing of the decoration layer (cd) extends from the instant (tcd) that layer (cd) is spread, at which time layer (cd) is liquid. As the curing time increases, the degree of curing increases. At instant (tcp) the protecting layer (cp) is spread over the decoration layer (cd). Because of the covering effect of the protecting layer (cp) on the decoration layer (cd), the decoration layer cures at a slower rate as the time for which the protecting layer (cp) is exposed to curing increases, as may be seen in the decrease in the gradient of the curing graph for the decoration layer (cd).
In order for the protecting layer (cp) to be able to spread over the partly cured decoration layer (cd), the degree of curing of the decoration layer (cd) will be sufficiently high to avoid effects in which the decoration layer (cd) is dragged when the protecting layer (cp) is spread. At the same time, the degree of curing of the decoration layer (dc) is not so high that the bond between the layers due to polymerisation deteriorates.
The separation layer (cs, cs', cs") is spread over the protecting layer (cp) at time (tcs). Similarly to what has been explained for the protecting layer (cp), spreading of the separation layer (cs) modifies the rate at which the protecting layer (cp) cures - and this would also modify the rate of curing of the decoration layer (cd) if it was partly cured.
Likewise, at the time (tcs) when the separation layer (cs) is spread, the protecting layer (cp) will be sufficiently cured to avoid effects in which the protecting layer (cp) is dragged but not too cured for the bond between the layers due to polymerisation to deteriorate.
The base layer (cb) is spread over the separation layer (cs, cs', cs") at time (tcb). Also, as explained for the previous layers, spreading of the base layer (cb) modifies the rate at which the previous layers cure. Also, at time (tcb) the separation layer (cs, cs', cs") is sufficiently cured to avoid effects in which the separation layer (cs, cs', cs") is dragged but not too cured for the bond between the layers due to polymerisation to deteriorate.
In particular, an inhibiting product (5) is applied to the base layer (cb) at time (tpi). In the curing graph for the base layer (cb) this is reflected in a bifurcation of the graph into two branches from time (tpi) onwards. On the one hand, the branch corresponding to curing of the part of the base layer (cbi) in inhibition zone (7), which reaches the separation layer (cs, cs', cs"), rises. The other branch corresponds to curing of the part of the base layer (cba) in adjacent zones (8), that is not influenced by the inhibiting product (5).
At instant (tr) the removable material is removed. Preferably, this instant (tr) occurs within a range represented by brackets in the diagram. In this range the degree of curing is sufficiently high (approximately 80 %) to avoid adhesion to surfaces of the means for the removal of material, but not so high that removal is hindered by bonds between the material in the inhibition zone and the material in its adjacent zones that are too strong, in particular such that removal is impossible after the material has fully cured.
Different complementary technical effects can be achieved in the invention with different types of separation layers (cs, cs', cs"). In particular, as shown in the curing diagram, separation layers configured with different rates of curing may be used, for example, by varying the amount of photoinitiators present in their composition.
For example, different chemical formulations of the separation layer (cs, cs', cs") may be used; in particular, higher concentrations of photoinitiators lead to faster curing. The thickness of the base layer (cb) can also influence the rate of curing of the separation layer (cs, cs', cs") from the time the base layer (cb) is spread.
With regard to the type of separation layer (cs), with a larger quantity of photoinitiators the type of separation layer (cs') - with a steeper gradient - may be obtained, while with a lower quantity of photoinitiators the type of separation layer (cs") - with a shallower gradient - may be obtained.
According to a first example embodiment shown in the curing diagram for the separation layer (cs), the separation layer (cs) is configured to cure fully substantially no later than the base layer (cb) fully cures in inhibition zones (7) and substantially later than it fully cures in adjacent zones (8).
According to a second example embodiment shown in the curing diagram for the separation layer (cs'), the separation layer (cs') is configured to fully cure substantially no later than the base layer (cb) fully cures in adjacent zones (8).
According to a third example embodiment shown in the curing diagram for the separation layer (cs"), the separation layer (cs") is configured to fully cure substantially later than the base layer (cb) fully cures in said inhibition zones (7).
In the three example embodiments shown in the curing diagram, the separation layer (cs, cs', cs") is treated with differential curing radiation such that, when the removable material is removed, the removable material is substantially separated off at the interface between the base layer (cb) and the separation layer (cs, cs', cs"). This interface has a substantially lower adhesion due to polymerisation in the at least one inhibition zone (7) than in the respective adjacent zones (8) because of the differential action of the curing radiation applied to the base layer (cb) on the separation layer (cs, cs', cs").
The curing radiation which acts differentially on the base layer (cb) because of the product inhibiting radiation (5) at the same time acts differentially on the separation layer (cs, cs', cs") for at least part of the time (td, td', td") during which the separation layer (cs, cs', cs") is still partly cured.
Comparatively, at the time when the base layer (cb) is spread, the separation layer (cs') in the second example is the most cured and the separation layer (cs") in the third example the least cured of the three, the separation layer (cs) in the first example having an intermediate degree of curing. Consequently, in separation layer (cs') there are fewer free radicals available for binding to base layer (cb) than to separation layer (cs), and to this than to separation layer (cs").
On the other hand, since the time intervals (td, td', td") during which the curing radiation acts differentially are different, with the separation layer (cs, cs', cs") being partly cured, the bonding with the base layer (cb) formed by cross-linking of the available free radicals is different in the three cases.
Thus, separation of the removable material can in particular be achieved with the three types of separation layer (cs, cs', cs"), with those in which the least adhesion due to polymerisation is achieved at the interface between the base layer (cb) and the separation layer (cs, cs', cs") in inhibition zones (7) in relation to zones (8) adjacent to them.
If the type of separation layer (cs') in the second example is used, when the removable material is removed with a sufficiently high degree of curing, the separation layer (cs') is already fully cured and therefore the base layer (cb) can be more strongly bonded to the separation layer (cs').
If the type of separation layer (cs") in the third example is used, when the removable material with a sufficiently high degree of curing is removed, the separation layer (cs") is still partly cured, so that removal of the material is additionally facilitated by the difference in the degree of curing between the base layer (cb) and the separation layer (cs"). Moreover, if the base layer (cbi) in inhibition zone (7) is more cured than the separation layer (cs"), removal of the material can be facilitated to a greater extent, for example with less brushing drag force.
Preferably, if the type of separation layer (cs) in the first example is used, in particular, a balanced technical effect can be achieved between an adequate bonding strength between base layer (cb) and separation layer (cs) while at the same time optimally facilitating removal of the material in a sufficiently cured or solidified state.
Figure 16 shows diagrammatically an example embodiment of a texture generating system (3) according to the invention. In particular, an example embodiment of the process depicted in figure 15 can be conducted through this embodiment of the system.
According to this embodiment, the system (1) for generating texture (3) comprises means for spreading (32) a base layer (cb), means for applying curing radiation (23, 24) configured to act differentially on the base layer (cb) and means (50, 51) for removing removable material from the base layer (cb).
Characteristically, system (1) comprises means for spreading (31) a separation layer (cs), means for applying curing radiation (22) to the separation layer (cs, cs', cs") and a controller (70) configured to actuate said means (31, 32; 22, 23, 24; 50, 51) carrying out a process according to the invention.
The means (30, 31, 32) for spreading layers may, for example, comprise spreading rollers, as shown in the figure. The means (20, 21, 22, 23, 24, 25) for applying curing radiation may, for example, comprise UV radiation lamps, as shown in the figure. The means (50, 51) for removing removable material may, for example, as in the figure, comprise removal brushes (51) and/or transfer rollers (50). The means (60) for transporting substrate may, for example, as shown in the figure, comprise conveyor belts (60) on which the substrates (2) are transported.
As shown in Figure 16, the substrate (2) on which the texture (3) is generated is transported along the various stations of the system (1) for conducting the process through means for the transport of substrate in the form, for example, as shown in the figure, of a conveyor belt (60).
First, a decoration layer (cd) is spread onto substrate (2), for example as shown in the figure, by means of a single-pass inkjet printer (10). The printer (10) comprises print heads (11, 12, 13) for injecting inks of different colours and, preferably, pinning lamps (15) for fixing ("pinning") the deposited droplets of print.
After applying curing radiation to the decoration layer (cd) by means of a UV lamp (20), the protecting layer (cp) is spread onto substrate (2) by means of a spreading roller (30). Afterwards, curing radiation is again applied to the protecting layer (cp) by means of a UV lamp (21).
The separation layer (cs) is then spread by means of a spreading roller (31). After that, curing radiation is again applied to the separation layer (cs) by means of a UV lamp (22). The base layer (cb) is then spread over the separation layer (cs) again by means of a spreading roller (32). Curing radiation is then again applied to the base layer (cb) by means of a UV lamp (23).
Curing radiation is then applied to substrate (2), and this acts differentially on the base layer (cb). For this purpose, system (1) may, as shown in the figure, comprise a single-pass inkjet printer (40) for inhibiting product. Printer (40) comprises print heads (41) for injecting inhibiting product and, preferably, pinning lamps (42) for fixing ("pinning") the deposited droplets of print.
Once the product inhibiting radiation (5) has been deposited on the base layer (cb), the application of curing radiation to the product inhibiting radiation (5) and the base layer (cb) by means of a UV lamp (24) makes it possible to obtain the zones (7) in which radiation is inhibited.
Cavities (4) of texture (3) are then formed by removing the removable material from the base layer (cb), which is separated out through the interface between the base layer (cb) and the separation layer (cs) in inhibition zones (7). For this purpose, as shown in the figure, a transfer roller (50) which facilitates removal of the more liquid part of the removable material may first be used, followed by a removal brush (51) which facilitates removal of the deeper part of the removable material.
Finally, curing radiation is applied, for example as shown in the figure, by means of a UV lamp (25), to complete curing of the final product.
System (1) is configured to carry out a process according to the invention. Thus, in the context of the present disclosure, it is to be understood that any process feature set forth herein may be provided by physical features of the system in the form of means, devices or elements suitable therefor. Accordingly, the technical effects and advantages of the process according to the invention also apply to the system.
Specifically, as described in this description, the invention provides a process and a system that allow the limitations of the prior art to be overcome and offer additional technical advantages.
To this end, the invention is not limited to the presented embodiments, but includes all variants, modifications and combinations within the scope of the appended claims.

List of references

1: Texture generating system

2: Substrate

3: Texture
4: Cavity

5: Product inhibiting radiation
6: Product promoting radiation

7, 7', 7": Radiation inhibition zones
8: Zones adjacent to the inhibition zones
9: Radiation promotion zone
10: Decorative inkjet printer
11, 12, 13: Colour print heads
15: Radiation lamp for fixing colour print

20, 21, 22, 23, 24, 25: Curing radiation lamps

30: Protective layer spreading roller
31: Separation layer spreading roller
32: Base layer spreading roller

40: Inkjet printer for inhibiting product
41: Print head for inhibiting product
42: Fixing lamp for inhibiting product

50: Roller for the transfer of material
51: Brush for the removal of material

60: Belt for the transport of substrate
70: Controller for the texture generating process

cb, cbl, cbll, cblll: Base layers
cb1, cb2: Base sublayers
cs, cs', cs", csl, csll, cslll: Separation layers
pr: Reinforcing particles
cp: Protective layer
cd: Decoration layer

L: liquid state
G: gel state
G+: solid gel state
S: solid state

cba: Base layer in adjacent zones
cbi: Base layer in inhibition zones

td, td', td": Time intervals in which the separation layer is partly cured after the application of differentially inhibited curing radiation
tcd: Instant of time at which the decoration layer is spread
tcp: Instant of time at which the protective layer is spread
tcs: Instant of time at which the separation layer is spread
tcb: Instant of time at which the base layer is spread
tpi: Instant of time at which the inhibitor is applied
tr: Instant of time at which the removable material is removed

Claims

Texture generating process (3), in which radiation curing by polymerisation is applied to a base layer (cb), differentially in the zones (7, 7', 7") in which curing radiation is inhibited with respect to the zones (8) laterally adjacent to the inhibition zones (7, 7', 7"), the textures (3) comprising cavities (4) are formed by the removal of removable material from the base layer (cb) in the inhibition zones (7, 7', 7"), in which the base layer (cb) has a substantially lower degree of curing than in the respective adjacent zones (8), characterized in that the base layer (cb) is spread over a separation layer (cs, cs', cs"), in which said separation layer (cs, cs', cs") is partly cured by radiation curing by polymerisation such that at least one inhibition zone (7) reaches the separation layer (cs, cs', cs") and on the separation layer (cs, cs', cs") the curing radiation acts differentially on the at least one inhibition zone (7) in relation to its adjacent zones (8) so that when the removable material is removed it is substantially separated out at the interface between the base layer (cb) and the separation layer (cs, cs', cs"), the interface having substantially less adhesion due to polymerisation in the at least one inhibition zone (7) than in its adjacent zones (8).
Texture generating process (3) according to the preceding claim, characterized in that the curing radiation acting differentially on the base layer (cb) at the same time acts differentially on the separation layer (cs, cs', cs") during at least part of the time (td, td', td") in which the separation layer (cs, cs', cs") is still partly cured.
Texture generating process (3) according to either of the preceding claims, characterized in that, before the base layer (cb) is spread, curing radiation acts differentially on the separation layer (cs, cs', cs") in the zones (9) in which curing radiation is promoted, which substantially coincide with the at least one inhibition zone (7) in said interface with respect to its adjacent zones (8), in particular the separation layer (cs, cs', cs") being fully cured selectively in the promotion zones (9) through curing radiation before the base layer (cb) is spread.
Texture generating process (3) according to any one of the preceding claims, characterized in that when the removable material is removed, the material removed has a sufficiently high degree of curing to substantially prevent it from adhering to surfaces of the means for the removal of removable material.
Texture generating process (3) according to any one of the preceding claims, characterized in that the separation layer (cs, cs', cs") is configured so that the separation layer (cs) cures fully substantially no later than the base layer (cb) cures fully in said inhibition zones (7) and substantially later than it cures fully in the adjacent zones (8), or
the separation layer (cs') is substantially fully cured no later than the base layer (cb) is fully cured in the adjacent zones (8), or

the separation layer (cs") fully cures substantially later than the base layer (cb) fully cures in said inhibition zones (7).
Texture generating process (3) according to any one of the preceding claims, characterized in that the base layer (cb) comprises a plurality of base sub-layers (cb1, cb2) spread one above the other.
Texture generating process (3) according to any one of the preceding claims, characterized in that a plurality of base layer (cbl, cbll, cblll) and separation layer (csl, csll, cslll) pairs are spread over each other in such a way that said inhibition zones (7) reach respective separation layers (csl, csll, cslll).
Texture generating process (3) according to any one of the preceding claims, characterized in that the separation layer (cs) incorporates reinforcing particles (pr) and/or thickening agents to increase the cohesion of the separation layer (cs) when the base layer (cb) is spread.
Texture generating process (3) according to any one of the preceding claims, characterized in that it comprises depositing a product inhibiting curing radiation selectively onto the inhibition zones (7) and/or on the zones adjacent (8) to the promotion zones (9) and/or a product promoting curing radiation (6) selectively onto the promotion zones (9) and/or the zones (8) adjacent to the inhibition zones (7).
Digital texture printing process according to Claim 9, characterized in that the product inhibiting curing radiation deposited on the inhibition zones additionally comprises an agent inhibiting curing and/or an agent lowering the glass transition temperature (Tg), and/or
is configured to cure by curing radiation, and be immiscible or partly miscible in the base layer and/or sublimate.
Texture generating process (3) according to any one of the preceding claims, characterized in that, before the base layer (cb) is spread, a barrier product to polymerisation by curing radiation comprising a curing inhibition agent and/or an agent inert to curing is deposited on the separation layer (cs, cs', cs") in zones substantially coinciding with the at least one inhibition zone (7), the polymerisation barrier product being in particular a promoting product (6) at the same time.
Texture generating process (3) according to any one of Claims 9 to 11, characterized in that the product inhibiting curing radiation, the product promoting curing radiation (6) and/or the polymerisation barrier product are deposited in the form of droplets of print (5) by means of inkjet printing.
Texture generating process (3) according to the preceding claim, characterized in that it comprises selecting print droplet volumes per print dot and/or print dot spacing to obtain cavities (4) having predetermined levels of depth.
Texture generating process (3) according to any one of the preceding claims, characterized in that the thickness of the base layer (cb) is greater than or equal to 100 microns, preferably 150 microns, more preferably 200 microns.
Texture generating system (3), comprising means for spreading (32) a base layer (cb), means for applying curing radiation (23, 24) configured to act differentially on the base layer (cb) and means for removing removable material (50, 51) from the base layer (cb), characterized in that it comprises means for spreading (31) a separation layer (cs), means for applying curing radiation (22) to the separation layer (cs) and a controller (70) configured to implement said means (31, 32; 22, 23, 24; 50, 51) carrying out a process according to any one of claims 1 to 14.