EP1381518B1

EP1381518B1 - A support for the decorative printing of surfaces, particularly of ceramic materials and the like

Info

Publication number: EP1381518B1
Application number: EP02722678A
Authority: EP
Inventors: Mauro Cestari
Original assignee: Sacmi Imola SC
Current assignee: Sacmi Imola SC
Priority date: 2001-04-26
Filing date: 2002-03-25
Publication date: 2006-04-26
Anticipated expiration: 2022-03-25
Also published as: WO2002090120A1; DE60210947D1; ATE324268T1; EP1381518A1; ES2259081T3

Abstract

A support for the decorative printing of surfaces (2) is described, having a plate-like silicone structure on one face (3) of which is distributed a colouring substance to be transferred onto said surface (2), and comprising a reinforcing structure (6) at least partially embedded in the plate-like structure.

Description

Technical field

The present invention relates to a support for the decorative printing of surfaces, particularly of ceramic materials and the like.

Technological background

The invention is particularly, although not exclusively, designed for the decorative printing of surfaces of ceramic materials and the like, but equally advantageously it lends itself to being applied in all those fields in which it is necessary to print characters or decorative figures on surfaces for example of products or in the field of advertising posters.
In the technical field of decorative printing of surfaces, so-called "contact" printing is known, in which provision is made for there to be contact between the support or printing means and the surface to be decorated.
A first known printing methodology provides for the use of printing rollers on the outer surface of which is wound a silicone tape. On the tape is distributed the colouring substance, for example an ink or similar pigment, which is transferred onto the surface to be decorated by contact of the silicone tape on the surface itself. The advantage of selecting a silicone-based printing support in tape form lies on the one hand in the distinct water-repellent characteristics of the silicone which facilitate the distribution and the transfer of the typically water-based inks onto the surfaces to be decorated, and on the other hand in its relative elasticity, which avoids the occurrence of localised overloads on the surface to be decorated as a consequence of the contact of the printing roller. This methodology, however, allows the printing and decorating of surfaces of limited dimensions, dictated principally by the extent and overall dimensions of the printing rollers, which have objective structural limits of construction.
A second methodology provides for the use, as an alternative to printing rollers, of silicone supports in plate form, substantially flat and mounted on respective frames. These make it possible to print and decorate surfaces which are also larger than those obtainable with conventional roller printing. Such supports, however, have the drawback of excessive elasticity in directions substantially parallel to the printing plane, which involves undesirable elongation of the support, with the result that smudging of the distributed colours is caused, which compromises their final quality. This has proved even more obvious in so-called multi-channel printing, in which several colours are superimposed on the printing surface.
Similarly to the flat plate form, the behaviour of a closed tape in ring form, and therefore endless, which rotates on driven cylinders may be considered.

Description of the invention

The problem underlying the present invention is that of providing a support for the decorative printing of surfaces, structurally and functionally designed to remedy the drawbacks mentioned with reference to the prior art cited.
This problem is solved by the invention by means of a support for the decorative printing of surfaces and a method according to the present claims.

Brief description of the drawings

The characteristics and advantages of the invention will become clear from the detailed description of one of its preferred exemplary embodiments illustrated by way of non-limiting example with reference to the appended drawings, in which:

Figure 1 is a diagrammatic view in section and on an enlarged scale of a plate-like printing support,
Figure 2 is a diagrammatic partial plan view from above of the support in Figure 1,
Figure 3 is a view corresponding to Figure 1 of a first alternative embodiment of the plate-like support,
Figure 4 is a view corresponding to Figure 1 of a second alternative embodiment of the plate-like support,
Figures 5 and 6 are views of embodiments of the support according to the invention,
Figures 7 and 8 are diagrammatic views corresponding respectively to Figures 1 and 5 whereby Fig. 8 illustrating the support according to the invention in the presence of a discontinuous surface to be printed.
Figure 9 is a partial view in side elevation and on an enlarged scale of a further variant of the invention,
Figure 10 is a partial view in plan of the base of the variant of the invention of Figure 9,
Figures 11 and 12 are sectional views on an enlarged scale along the lines XI-XI and XII-XII of Figure 10,
Figures 13 and 14 are views corresponding to that of Figure 9 in two different embodiments.
Figure 15 is a partial view in side elevation of a further variant of the support of Figure 9, wherein the support is anchored to a cylindrical load-bearing structure,
Figure 16 is a partial diagrammatic view of a step of the method of manufacture of the support according to the invention.

Preferred method of execution of the invention

With reference to the drawings mentioned, 1 indicates as a whole a support for the decorative printing of a surface 2 according to the present invention.
The support 1 has a plate-like structure having a thickness indicated by S comprised between opposed faces 3 and 4 and is produced with a silicone matrix. On the surface of the face 3 are provided, for example by means of laser technology, a plurality of impressions, all indicated by 5, constituting seats for receiving one or more colouring substances with which the surface 2 is decorated. For this reason the face 3 will also be indicated in the following description as the printing face.
Owing to the distinct water-repellent characteristics of the silicone, the colouring substance, typically a water-based ink or similar pigment, is easily transferred onto the surface 2 by flowing from the impressions 5, without any problem of formation of deposits or layers of colorant within the impressions.
According to a preferred embodiment of the invention, the support 1 comprises a reinforcing armature 6 embedded within the thickness S in the plate-like silicone structure.
The armature 6 is formed by a network of glass fibres 7 distributed in a random so-called "MAT" configuration, or without any preferential orientation in predetermined directions, as illustrated in Figure 2.
More particularly, the armature 6 is disposed within the thickness S of the plate-like support on the opposite side from the printing face 3.
The glass-fibre reinforcement 6 is such as to impart to the plate-like support, characteristics of distinct rigidity (and consequently limited elasticity) in directions parallel to the plane of the plate-like support. At the same time, the armature 6 does not confer rigidity in a direction perpendicular to the plane of the support, indicated by.the axis X in Figure 1, along which adequate elasticity is ensured owing to the silicone matrix (or even silicone foam matrix) having the thickness S.
The plate-like support 1 may be fixed at the perimeter on a frame 8, only partially illustrated in Figure 2, through which it is handled during the operations of printing the surface 2.
To this end, prior to the printing step, the colouring substance is distributed in the impressions 5 according to a preselected configuration correlated to the decorative figure to be obtained on the surface 2. The printing face is then brought into contact with the surface 2 with consequent distribution of the colorant. It should be noted that owing to the elasticity conferred by the silicone in a direction perpendicular to the plane of the printing support, contact between the surfaces 2 and 3, during printing, takes place without the occurrence of localised overloads due to non-uniform bearing of the support on the surface to be decorated. This proves particularly advantageous in the presence of specific materials, such as, for example, ceramic materials or the like.
On the other hand, as a result of the rigidity conferred by the reinforcement with glass fibres in directions contained within the plane of the support, deformations in said directions are prevented or at most extremely limited within very narrow tolerances, imparting dimensional stability to the support itself. This makes it possible also to limit within said tolerances the dimensions of the decorative figures printed, and this proves advantageous for example in multi-channel printing, where several colours are printed in succession, superimposed one upon the other. Such rigidity conferred in the plane of the support thus makes it possible to observe predetermined dimensional tolerances, preventing smudging at the outlines of the decorative figures printed due to undesirable elongation of the support itself.
Owing, then, to the provision of the armature of glass fibre in random arrangement without any preferential orientation, any breakage of one or more fibres, due for example to the formation of the holes or the impressions for distribution of the colour, is not such as to compromise the stability and overall rigidity of the plate-like structure of the support.
It should further be noted that the armature embedded in the plate-like support may be produced with reinforcing fibres of a different chemical nature, although the choice of glass fibres represents a preferred choice, owing to the compatibility between the silicone matrix, with which the printing support 1 is produced, and silica, the basic component of the glass fibres. It should be noted that the armature may also be produced with fibres disposed substantially regularly, as long as they ensure dimensional stability.
In an alternative embodiment of the invention, shown diagrammatically in Figure 3, provision is made for the support 1 to be formed from an open porosity silicone foam having characteristics of permeability and porosity to air and vapour but not directly to water. Such a structure makes it possible to subject the plate-like support to one or more jets of compressed air directed onto the face 4 opposed to the printing face, with consequent squeezing of the impressions 5 to obtain the outflow of the colouring substance and also its transfer onto the surface to be decorated. Such printing methodology is usable precisely owing to the porosity of the silicone material which facilitates the pressure action of the compressed air through the thickness S to obtain the discharge of the impressions and pits filled with colorant.
A second alternative embodiment of the invention, shown diagrammatically in Figure 4, differs from the example in Figure 3 in that it further comprises a non-porous silicone layer 9 at the face 3, which layer is perforated to form the impressions 5 constituting seats for the printing ink. Said alternative form allows the compressed air which passes through the porous layer to emerge only through the impressions (5), expelling the ink deposited therein.
In a further variant of the invention, proposed with reference to Figures 5 to 8, provision is made for the porosity in the porous silicone layer to be obtained by processing the latter with formation of a plurality of blind holes 50 which involve said layer, and are preferably obtained by laser perforation. A suitably calibrated laser beam is guided substantially perpendicularly to the surface of the face 4 (opposed to the printing surface) such as to provide a dense network of parallel and non-intersecting holes, having a mean diameter of 0.2 - 2 mm and with a mean distance between centres of 0.4 - 2.5 mm.
In the example of Figure 5 the aforesaid holes are interrupted at a distance from the cavities of the impressions 5, rendering the support suitable for contact printing, as already indicated previously. In the example of Figure 6, on the other hand, the holes communicate with the printing surface through one or more capillary holes 51 which start from the bottom of the blind holes 50. The capillary holes 51 are also preferably produced by laser perforation, in a manner analogous to that of the execution of the holes 50.
With the porosity provided by means of the holes 50 the further advantage is obtained of improved flexibility of the support 1 in a direction perpendicular to the printing surface, facilitating the absorption of superficial roughness and/or irregularities of the surface to be printed, by means of localised deformation of the support almost exclusively in the perpendicular direction indicated above, or without substantial deformation in directions parallel to the printing surface. This is indicated with reference to Figures 7 and 8, in which it can be seen that the support of Figure 8, relative to that of Figure 7, permits better adherence to superficial roughness and unevenness of the surface to be printed 2 owing to the improved deformability conferred by the blind holes 50.
Preferably, the silicone-based elastomer with which the support 1 is produced (case of single-layer support) or at least one of the layers thereof (case of multi-layer support) is modified by the addition of reactive and/or interpolant groups and/or of fillers having a chemical base of SiO₂ - SiCH₃ - SiOH.
In the invention, proposed with reference to Figures 9 to 12, provision is made for the surface of the face 4, opposed to the printing face, to comprise a plurality of foot appendages 60, raised in the same direction from the support 1 and mutually spaced from one another. Each foot appendage 60 is developed from a base surface 61 and tapers in the direction of a corresponding free end 62.
More particularly, the foot appendages 60 are disposed, at a pitch P, in rows parallel to one another, in which adjacent rows are offset by half a pitch with a configuration of the staggered type as clearly illustrated in Figure 10. Said appendages 60 are further elongate in the direction of development of each of the rows, which direction is indicated by the axis Y in Figure 10. Preferred dimensions in plan for each appendage are of the order of approximately 2 mm in the direction of the axis Y and of approximately 1 mm in a direction perpendicular to the axis Y. It should further be noted that the direction of development of each row (axis Y) is such as to be perpendicular to the direction of movement of the support in the printing operations relative to the surface to be decorated. Said direction of movement is indicated by the arrow F in Figure 10. In other words, the foot appendages 60 are suitably elongate in a direction transverse to the direction of travel of the support.
Although the aforesaid dimensions constitute a preferred choice, it is obviously possible to choose different dimensions and preselected values of the pitch P, of the depth of the foot, and also of the distance between adjacent rows and if necessary different materials in order consequently to vary the characteristics of compressibility of the support.
By the provision of foot appendages disposed as described above in a preselected concentration per unit of surface of the support 1, an improved print quality is advantageously obtained owing to the fact that, in the printing step, the presence of the feet provides a more limited distribution of the pressure forces induced by the contact between the support and the surface to be decorated. As a consequence, the surface of the support in contact with the surface to be printed is reduced compared with a support devoid of feet, with less friction and creep between the support and the surface to be printed.
The benefits obtainable with this support structure are particularly evident in the presence of surfaces to be decorated with particularly low ultimate breaking strengths, such as those typical of tiles and similar products. In the printing process, as a result of the contact of the support 1 with the surface to be printed, an area of contact with localised distribution of the pressure forces in the thickness of the support is determined. As illustrated in Figures 13 and 14, said distribution of forces is more restricted in the support provided with feet compared with a support devoid of the same, with the consequence of a smaller area of contact which therefore induces less relative creep, wear and friction between the contact surfaces. A and A' (where A is less than A') indicate the profiles of the areas of contact diagrammatically illustrated for each of the two structures of the support, with and without foot appendages.
It should further be noted that the rows of feet 60 are aligned in rows transversely to the direction of travel of the support in order to guarantee greater flexibility of the support, in particular when the support is mounted on a printing roller. The offset between adjacent rows of feet likewise allows the presence of void areas in the direction of travel with consequent increased flexibility of the support.
In a further variant of the invention, proposed with reference to Figure 15, provision is made for the printing support 1 not to be provided with any armature partially embedded on the side opposed to the printing surface. As illustrated in Figure 15, the support is suitably anchored, at the surface 4 (provided with the foot appendages 60), to a load-bearing support structure 65, for example in the shape of a cylindrical jacket (printing roller). Preferably the support 1 is anchored to the cylindrical jacket 65 by being adhesively secured.
A method for the manufacture of the support according to the invention, in the variants described above, provides for the support 1 to be obtained by centrifugal action, as described in present claims. With reference to Figure 16, a hollow centrifuge cylinder 70 is provided, preferably metallic, provided with rotational motion about its principal axis. In the cylinder 70 there is indicated an inner surface 70a on which is fixed a die 71, made of resin, including on the side radially opposed to the surface 70a, a surface 71a having surface reliefs 72 of a shape and arrangement such as to reproduce in negative form the appendages 60 of the support. The method provides for the arrangement of a layer of silicone at the surface 71 a, and a subsequent centrifugal action of the cylinder, by means of which there is obtained a silicone skin 73 of substantially uniform thickness defined between the opposed faces 3 and 4, where the face 4 is provided with the foot appendages 60.
The silicone skin 73 is then removed from the die 71 in the form of a particularly flexible cylindrical sheath-like product and is turned inside out so as to have the face 3 as the outer surface of the product and the face 4 as the inner surface. The method further provides for fixing, for example by being adhesively secured, the surface of the face 4 onto a cylindrical support (of the type illustrated in Figure 15).
It should be noted that, with the method described above, the printing face 3 of the support is obtained substantially devoid of surface defects, owing to the fact that said surface is produced exclusively by centrifugal action without any contact with surfaces of the die. Therefore in the presence of any defects or scoring of the die 71, the surface which can possibly be damaged is the surface 4 bearing the foot appendages 60, without compromising instead the quality of the surface finish of the printing face 3.
The invention thus solves the problem posed, by providing numerous advantages with respect to the known solutions.
A first advantage lies in the fact that printing supports according to the invention allow the decorative printing of surfaces much larger than those obtainable with conventional printing rollers, guaranteeing, however, dimensional stability within the typically accepted tolerances.
A second advantage lies in the fact that the relative rigidity of the support in directions parallel to the plane of the support itself guarantees optimum superimposition of the colours distributed, in particular in multi-channel printing, devoid of smudging even in the case of large dimensions of the surface to be printed.
A further advantage is that the high degree of rigidity in the plane of the support does not prejudice the characteristics of elasticity of the support in a direction perpendicular to the plane itself for optimum bearing contact of the support on the surface to be printed.
A still further advantage lies in being able to use a porous printing means, which assists the expulsion of the ink through compressed air which filters through the porosity, to the point of no longer making contact between the printing means and the surface to be printed necessary.

Claims

A support for the decorative printing of surfaces (2), having a plate-like silicone structure on one face (3) of which is distributed a colouring substance to be transferred onto said surface (2), characterised in that it comprises on a surface (4), opposed to the printing surface (3), a plurality of foot appendages (60) extending in the same direction and mutually spaced from one another.
A support according to claim 1, wherein said appendages (60) are disposed at a pitch (P) In parallel rows.
A support according to claim 2, wherein adjacent rows of said appendages (60) are offset by half a pitch, in an overall staggered arrangement.
A support according to claim 2 or 3, wherein each appendage (60) has a configuration in plan elongate in the direction of development of the corresponding row.
A support according to one or more of the preceding claims, wherein said appendages (60) taper from a base surface (61) in the direction of a corresponding free end (62).
A support according to one or more of the preceding claims, wherein said surface (4) provided with said appendages (60) is capable of being anchored to a load-bearing support structure (65).
A support according to claim 6, wherein said support structure Is In the shape of a cylindrical jacket.
A support according to one or more of the preceding claims, comprising a reinforcing structure (6) at least partially embedded in the plate-like structure of said support.
A support according to claim 8, wherein said reinforcing structure (6) comprises a plurality of fibres (7) embedded In the silicone structure.
A support according to claim 8 or 9, wherein the fibres (7) of said reinforcing structure (6) are glass fibres distributed In a MAT configuration, without any prevalent orientation in predetermined directions.
A support according to claim 9 or 10, wherein said reinforcing structure (6) with fibres (7) is disposed within the thickness (S) of said plate-like structure on the opposite side from the printing face (3).
A support according to claim 8, wherein the surface of the printing face (3) comprises a plurality of impressions (5) adapted to receive the colouring substance distributed thereon in order to transfer it onto the surface to be decorated (2).
A support according to claim 12, wherein the silicone of said plate-like structure has characteristics of porosity to air such that the action of a jet of compressed air directed onto the plate-like structure, on the opposite side from the printing face (3), effects the squeezing of said impressions (5) with the emptying of the latter and consequent transfer of the colouring substance onto the surface to be decorated (2).
A support according to claim 13, further comprising a layer (9) of non-porous silicone at the printing face (3), said impressions (5) being formed by perforation of said layer (9), such that the compressed air, once it has passed through the porous layer, can emerge to the outside exclusively through the impressions (5), taking with it the colouring substance deposited therein.
A support according to claim 8, comprising, on the opposite side from the printing surface (3), a plurality of blind holes (50), interrupted at a predetermined distance from said printing surface.
A support according to daim 15, wherein said holes (50) extend perpendicularly to the printing surface (3) and are obtained by laser perforation.
A support according to claim 15 or 16, wherein each of said holes (50) communicates with the printing surface (3) through one or more capillary holes (51).
A support according to claim 17, wherein said capillary holes (51) are obtained by laser perforation.
A support according to claim 8, produced from silicone-based elastomer with the addition of reactive and/or interpolant groups and/or of fillers having a chemical base of SiO₂-SiCH₃-SiOH.
A method for the manufacture of a support for the decorative printing of surfaces according to one or more of claims 1 to 19, comprising the steps of:
- prearranging a hollow centrifuge cylinder (70), rotatable about its axial axis of symmetry, Inside which is disposed a silicone matrix layer constituting said support (1), characterised in that it provides for the further steps of:

- prearranging a die (71) with hollow cylindrical jacket mounted inside the centrifuge cylinder (70), on the inner surface (71a) of which is disposed said silicone matrix layer, so as to obtain by centrifugal action said support (1) in the form of a hollow cylindrical product having a smooth inner surface and an outer surface shaped in a corresponding and opposed manner to that of the surface (71a) of the die, said die (71) being provided with reliefs (72) raised from the surface (71a) so as to obtain in the face (4), opposed to the printing face (3), said plurality of foot appendages (60).
A method according to claim 20, wherein said hollow cylindrical product is subsequently turned inside out, after extraction from the centrifuge cylinder (70), so as to have as the outer surface the smooth face (3) intended for the printing contact, and as the inner surface the opposed face (4) shaped by the die and intended for fixing onto a printing support.