FR2990156A1 - Digital transfer unit for transferring viscous material in offset machine, has head assemblies projecting viscous material on transfer area so that projections produce image/text in transfer area corresponding to image/text in digital file - Google Patents

Abstract

The unit (0) has a transfer area (1) moved by a mechanical unit. Head assemblies (6a-6c) comprise a nozzle, which is individually controlled by a computer system. The head assemblies are designed to project viscous material on the transfer area such that projections produce an image and/or text in the transfer area corresponding to the image and /or text in the digital file. The viscous material projected on the transfer area is carried on a substrate (5) by contacting the transfer area moved by the mechanical unit. Independent claims are also included for the following: (1) a digital material projection system (2) a method for transferring modifiable viscous material.

Description

The present invention relates to the field of material transfer. The present invention more particularly relates to a group and a digital viscous material transfer system and the associated method. It is known in the prior art of digital printing groups, by jets of material, composed of a set of heads emitting jets of controlled material and used to project directly, at specific points and without contact, when a relative displacement controlled by a set of mechanical, electrical, electronic and computer elements, the material or materials to be deposited on said substrate. This non-contact process has a number of disadvantages.

For example, when one or more materials are to be deposited on the extreme edge of the substrate, or when a system combines jets of different materials, this procedure requires extremely precise relative positioning and displacements between the substrate and the emitting devices. the jets of matter.

This process becomes more complex as: - the substrate has dimensional variations due, for example, to its nature, such as, for example, in the case of flexible objects, to its manufacturing tolerances, or to temperature conditions or humidity, - the resolution of the deposition sites is high, - a reduced space makes it difficult to use jets of different materials, - or that due to the bulk of the heads of jets of material, their points of impacts are far apart.

The object of the present invention is to overcome certain disadvantages of the prior art by proposing a digital transfer group intended to be integrated into existing machines, for example of the offset type, or new ones. This object is achieved by a group of digital transfer of viscous material, by jet, characterized in that it comprises at least: a transfer surface set in motion by mechanical means, a jet unit comprising a first set of heads, each head having at least one nozzle individually controlled by a computer system and a digital file, each head being intended to project at least one viscous material on the transfer surface so that all the projections produce an image and / or a text on the transfer surface corresponding to the image and / or the text of the digital file, the viscous material or materials projected on the transfer surface being transferred onto a substrate by contacting the transfer surface moved by the means mechanical, with the substrate driven by drive means of a machine.

According to another feature, the viscous material jet unit further comprises at least a second set of heads, each head of the second set of heads comprising at least one nozzle individually controlled and intended to project one or more colored materials on all or part of the viscous material projected on the transfer surface, the viscous material of the first set of heads being transparent. According to another feature, the first set of heads is subdivided into a number of groups of heads, each group of heads projecting a colored viscous material. According to another particularity, the number of groups of heads corresponds at least to the number of fundamental colors.

In another feature, the transfer surface is a continuous surface. According to another feature, the transfer surface is composed of one or a set of surfaces moved in a cyclic motion by the mechanical means. According to another particularity, the transfer surface is associated with a device for modifying the viscosity of the projected viscous material or materials. According to another feature, the device for modifying the viscosity of the projected viscous material or materials consists of an element causing a partial polymerization of the projected viscous material or materials. According to another feature, the device for modifying the viscosity of the projected viscous material or materials is able to maintain the viscous material with a glass transition point above its vitreous transition point in a perfectly liquid state. According to another feature, the transfer unit has a cooling device for bringing the viscous material (s) below their glass transition point. According to another feature, the material forming the transfer surface, on which the projections of viscous material and colored materials are made, is such that the coefficient of adhesion between the material of the transfer surface and the materials to be deposited is less than that between the materials to be deposited and the substrate to receive said materials. According to another particularity, the transfer unit has a plurality of intermediate transfer surfaces, each located opposite a set of heads and receiving an intermediate image, each transfer surface being in contact two by two and each transfer surface having the same linear velocity as that of the substrate.

According to another particularity, the transfer group comprises at least two transfer surfaces each carrying out one or more transfer steps, by contact, of the deposition of the materials on the intermediate transfer surfaces.

According to another feature, the different transfer surfaces have a coefficient of adhesion defined between the materials to be sprayed and the material constituting the transfer surface, these coefficients being increasing when one moves from the transfer surface, receiving the projections of materials to the transfer surface in contact with the substrate, each of the preceding coefficients being less than the coefficient of adhesion between the materials to be sprayed and the substrate. According to another feature, each transfer surface is thermostated. According to another feature, the hardness of the transfer surface in contact with the substrate is able to match the imperfections of said substrate. According to another feature, the transfer unit comprises adjustment means for making the distance between the transfer surface, in contact with the substrate, and said substrate adjustable. According to another feature, the transfer unit comprises means for regulating the respective speed of the transfer and displacement surface of the substrate, the regulation means being controlled so that the linear speed of the transfer surface, at the moment when the transfer surface contacts the substrate, is identical, in direction and intensity, to the speed of displacement of said substrate.

According to another feature, each transfer surface is associated with a cleaning device arranged after the contact with the substrate on the path of the transfer surface to allow the removal of non-reported material residues on the substrate.

According to another feature, the cleaning device is composed of blowing means and / or a set of scrapers and rollers, some of which are in contact with the transfer surface. In another feature, the cleaning device comprises a heat source and / or a wetting device with water and / or at least one solvent to make the residues more fluid before removal. The invention also relates to a digital material projection system characterized in that it comprises at least one jet material digital transfer unit, a preparation station, a control station, a reading station and a drying system. . In another feature, the substrate passes between a transfer group and a counterpressure cylinder. According to another feature, the system comprises at least two digital jet material transfer groups arranged to simultaneously report the deposition of material thus made on both sides of the substrate. According to another feature, the number of transfer groups of the system corresponds to at least the number of fundamental colors, each transfer group being arranged one after the other on the same side and in the direction of displacement of the substrate to carry over. one after another the deposition of material on the face of the substrate. According to another feature, the system comprises a unwinding system and a continuous substrate coiling system.

In another feature, the system includes a sheet feed device and a sheet receiving device on which the material (s) has been transferred.

According to another feature, the preparation station establishes the size of the drops of viscous material and / or colored materials to be sprayed so as to achieve the desired rendering. According to another particularity, the control station controls the sets of heads so as to synchronize the projections of viscous and colored materials with the displacement of the substrate taking into account the delay induced by the displacement of the transfer surface or surfaces. The invention also relates to a process for the digital transfer of material with modifiable viscosity, characterized in that it comprises: a step of selective and controlled spraying, on the transfer surface, of transparent or non-transparent viscous material in a state of defined viscosity ensuring the maintenance and preservation of the information (image, text) formed on the transfer surface, - a transfer step, by contact, of the transfer surface with a substrate. According to another feature, the method further comprises a selective and controlled projection step, on the viscous material projected onto the transfer surface (1), of colored materials, the viscous material having a viscosity capable of retaining the colored material. According to another feature, the method comprises a step of modifying the viscosity of the viscous material (s) to be sprayed. According to another feature, the method comprises a step of cleaning each transfer surface (1, 10). The invention also relates to a use of the transfer unit, on an offset machine, characterized in that it comprises a step of replacing a lithographic drum of the offset machine by the transfer unit, the mechanical drive means lithographic drum being connected to the mechanical means of the transfer unit. Other features and advantages of the present invention will emerge more clearly on reading the following description, made with reference to the appended drawings, in which: FIG. 1 represents a sectional view of an exemplary embodiment of FIG. FIG. 2 represents a perspective view of an alternative embodiment of a transfer unit according to the invention, FIG. 3 represents a perspective view of a variant of a transfer device according to the invention. embodiment of a transfer group according to the invention, - Figure 4 shows a perspective view of an alternative embodiment of a transfer unit according to the invention, - Figure 5 shows a configuration of the use of FIG. 6 shows a sectional view of the digital material projection system according to an alternative embodiment, FIG. 7 represents a sectional view of the digital projection system. FIG. According to another embodiment variant, FIG. 8a represents a step of a use of the transfer group according to an alternative embodiment, FIG. 8b represents another following step of the use of the transfer group according to a variant of FIG. FIG. 9a shows the transfer unit according to an alternative embodiment with a mobile cleaning system remote from the transfer surface; FIG. 9b represents the transfer unit according to an alternative embodiment with a mobile cleaning system close to the transfer surface.

In what follows, the term "material" denotes any type of material that can be emitted by jet, for example and without limitation, inks of any kind, varnishes, coating products, adhesives. For example, the viscous material may be varnish or ink, the transparent viscous material may be varnish and the colored material or colored viscous material may be ink. Similarly, the term "substrate" will denote any type of flexible or rigid substrate such as cellulosic substrates (paper, cardboard, wood), composites, textile or synthetic in continuous mode or sheet-sheet mode and whose thickness may vary. from a few tens of micrometers to several centimeters. The invention will now be described according to the previously cited figures.

A digital transfer unit (0) according to the invention consists essentially of a transfer surface (1) and one or more jets of viscous material. Unlike jet devices of commonly used materials, the material to be deposited is not directly projected on the substrate (5) but is deposited on an intermediate surface called transfer surface (1). This transfer surface (1) is moved by mechanical means. This transfer surface (1) is then directly brought into contact, by pressure by mechanical means, with the substrate (5) thus causing the transfer of the material or materials of the transfer surface (1) onto the substrate (5). . The material deposition process is therefore carried out at least in two successive stages, a step of depositing the viscous material (s) by selective and controlled spraying on the transfer surface (1), then a step of transferring this deposit by contact. of the transfer surface (1) with the substrate (5).

The viscous material to be deposited is projected on the transfer surface (1) by one or more viscous material emission units, comprising at least one set of emission heads (2a1, ..., 2an; 2b1, ..., 2bn), viscous material management systems, viscous material tanks and control units. Each head (2a1, ..., 2an; 2b1, ..., 2bn) may comprise one or more nozzles (s) from which the viscous material (s) are ejected, for example by compression or vaporization or by vibration or any other technique. Each set of heads (2a1, ..., 2an; 2b1, ..., 2bn) may comprise one or more rows (2a, 2b) of heads according to the desired accuracy. The heads (2a1, ..., 2an) of the first row are spaced across the width of an image area and / or text to be printed. The print heads (2b1, ..., 2bn) of the second row are also spaced across the width, but are offset from the print heads (2a1, ..., 2an) of the first row. Thus, the first (2a1, ..., 2an) and the second rows (2b1, ..., 2bn) are capable of printing a continuous line across the entire width of the image area and / or text. Each head (2a1, ..., 2an; 2b1, ..., 2bn) comprises at least one nozzle individually controlled by a computer system and a digital file. Each head (2a1, ..., 2an; 2b1, ..., 2bn) is intended to project at least one viscous material onto the transfer surface (1) so that all the projections produce an image and / or a text on the transfer surface (1) corresponding to the image and / or the text of the digital file. The emitting unit (s) of jets of viscous materials and / or the emitting heads of jets of colored materials may for example be in communication with a control station (16) so as to be able to send information to this station. control (16) and receive instructions from the latter. The computer system may be the computer system of the control station (16).

According to a first variant embodiment of the transfer unit (0) according to FIG. 3, the transfer unit (0) comprises a viscous material jet unit comprising a first set of heads (2a1, ..., 2an; 2b1, ..., 2bn) intended to project colored viscous material. In this variant, the first set of heads (2a1, ..., 2an; 2b1, ..., 2bn) is subdivided into a number of groups of heads. Each group of heads projects a colored viscous material. The number of groups of heads corresponds, for example, to at least the number of basic colors. According to a second variant embodiment of the transfer unit according to FIGS. 1, 2 and 4, the transfer unit (0) comprises a viscous material jet unit comprising a first set of heads (2a1, ..., 2an; 2b1 , ..., 2bn) intended to project transparent viscous material. In this variant, the viscous material jet unit further comprises a second set of heads (6a, 6b, 6c) disposed after the first set of heads (2a1, ..., 2an; 2b1, ..., 2bn ) in the direction of rotation of the transfer surface (1), each head of the second set of heads being intended to project one or more colored materials on all or part of the viscous material projected on the transfer surface (1). In this variant, the transparent viscous material or substances already deposited on the transfer surface (1) makes it possible to retain the colored material (s) so that, for example, it (s) do not spread after it has been deposited. The area covered by the transparent viscous material of the transfer surface (1) does not necessarily correspond to the area covered by the colored matter (s).

The first set of heads (2a1, ..., 2an; 2b1, ..., 2bn) and / or the second set of heads (6a, 6b, 6c) are arranged orbital at a small distance from the surface of the transfer (1), for example and not limited to a few millimeters of the latter. These sets of heads (2a1, ..., 2an; 2b1, ..., 2bn, 6a, 6b, 6c) are arranged parallel to the axis of the volume carrying the transfer surface (1). The emission of material by each of the heads of the assembly is controlled selectively and quantitatively by a program managing and controlling the plurality of heads. The transfer surface (1) may consist of a continuous surface such as the surface of a form of revolution. FIG. 1 shows a transfer surface (1) formed by the peripheral surface of a cylinder, but this example is in no way limiting, the transfer surface (1) can be frustoconical or partially frustoconical or any other surface having a shape of revolution. The transfer surface may also be continuous, for example and without limitation a belt or any continuous set of surfaces. An advantage of a transfer surface formed by a continuous surface is that the deposition of material can be carried out continuously. At the same time as a deposit is made on a part of the transfer surface (1), the deposit previously made on another part of the transfer surface (1) is transferred to the substrate (5) with a corresponding delay. the time taken by the deposition of the materials to reach the substrate (5). According to another embodiment of the transfer surface (1), the transfer surface (1) is composed of one or a set of surfaces that can be moved with a cyclic movement.

Depending on the application and / or the desired effect, the transfer surface (1) may be of various nature both by its geometry, its hardness and its composition. In order to increase the transfer rate of the material or materials from the transfer surface (1) to the substrate (5), the material, in contact with the substrate (5), constituting the transfer surface (1) will be selected with a coefficient of adhesion between the material of the transfer surface (1) and the transparent viscous materials and / or the colored materials to be deposited lower than the coefficient of adhesion between the substrate (5) and the substances to be deposited.

The material of the transfer surface (1) may also be chosen so as to be able to match any imperfections of the substrate (5). To do this, the material of the transfer surface (1) will be chosen so that its hardness is less than that of the substrate (5) on which the deposition of materials is reported. Thus, the invention combines the advantages of inkjet with those of offset printing to constitute an offset-jet machine of viscous and / or colored materials. According to another embodiment, the volume carrying the transfer surface (1) will comprise at least one layer of compressible material, such as a rubbery material, so as to correct any surface defects of the substrate (5). The volume may also, in addition, comprise a surface layer made of a material whose coefficient of adhesion between the material and the materials to be deposited is less than that between the materials to be deposited and the substrate (5). In some cases, the emission heads (2a1, ..., 2an; 2b1, ..., 2bn) of the first set of heads of the transfer unit do not allow the viscous material (s) to be projected with a sufficient viscosity for example, so that the adhesion of drops deposited on the transfer surface (1) opposes the resulting forces of the displacement of said transfer surface (1) and the gravity. The transfer unit may therefore comprise a device (4) for locally modifying the viscosity of the material (s) so as to project the material (s) in a state of defined viscosity ensuring the maintenance and preservation of the information (image, text) formed on the transfer surface (1). This device (4) can be placed near the heads (2a1, ..., 2an; 2b1, ..., 2bn) of the first set of heads of the transfer unit and close to the transfer surface (1 ). Preferably, this device (4) will be placed just after the emission heads, in the direction of rotation of the transfer surface (1), so as to avoid any movement of material relative to the transfer surface (1). ) when rotating the latter.

The design of this device depends on the physicochemical composition of the transparent viscous materials to be sprayed. For example, for the materials having an aqueous base or solvent, the device (4) may consist of an element causing partial evaporation of the base. This element may be for example and without limitation a heat source (103) placed near the transmission head (2a1, ..., 2an; 2b1, ..., 2bn). The material, when projected on the transfer surface (1) will undergo partial drying so as to freeze the drop on the transfer surface (1) and stabilize its shape. This drying may be carried out by a heat source (103), such as for example an ultraviolet source, or any other drying means placed near the transfer surface. In the case of using glass transition point material, the material to be projected may, for example, be stored in the solid state (at room temperature). During the projection, the material (s) may be heated, agitated and stored in thermostatic inkwells. The emission heads (2a1, ..., 2an; 2b1, ..., 2bn) may be heated, for example and without restriction, to around 40 ° Celsius, so as to maintain the material above its vitreous transition point in perfectly liquid state. Once projected, the material may for example be brought into contact with a transfer surface (1) thermostatically so as not to completely freeze or projected materials. The deposition of material is then transferred to the substrate (5) in contact with which the material or materials solidify. According to another variant embodiment, the substrate (5) on which the material or materials has been transferred passes in front of a cooling means intended to cool said substrate (5) so as to bring the deposition of material below the transition point vitreous and set it on the substrate (5). In the case of materials containing oils, the device (4) for changing the viscosity of the material to be sprayed may consist of a cooling element to partially freeze the base. For other materials, the device (4) may, for example, consist of an element causing partial polymerization of the material (s) to be sprayed. This element may be for example and without limitation an ultraviolet source, an infrared source or any other source allowing a partial polarization of material. For the second embodiment of the transfer unit, for the second set of heads (6a, 6b, 6c) arranged after the first set of heads (2a1, ..., 2an; 2b1, ..., 2bn) in the direction of rotation of the transfer surface, the heads comprise at least one nozzle for projecting one or more colored materials contained in tanks on the viscous material already projected on the transfer surface (1). Each nozzle projects, for example, a colored material. For example, one nozzle projects a black colored material and the other three each a colored material among the fundamental colors such as cyan (C), magenta (M) and yellow (Y). The colored materials are projected, for example, by compression, vaporization or sublimation or any other technique. By way of example, for sublimation projection, the colored material is in the form of ink ribbons. Each ink ribbon includes sublimable ink, for example, for each fundamental color, such as magenta, cyan, and yellow, and for black. Each ribbon passes micro resistors distributed over the printheads. The micro-resistors receive electrical signals of variable intensity which heat them strongly to heat points of the ribbon. At these points, the ribbon ink sublimates. It is then projected towards the printed surface on which it solidifies, the surface to be printed may be the transparent viscous materials deposited on the transfer surface or the transfer surface. Each transfer surface of the transfer unit according to the invention may also be associated with a cleaning device (3) disposed after contact with the substrate (5) on the path of the transfer surface. This device (3) is intended to recover the residues of projected materials remaining on the transfer surface (1) and which have not been transferred onto the substrate (5). This device (3) thus allows a permanent cleaning of the transfer surface (1) before projection of new jets of materials. H also makes it possible to change the image and / or text at each sector of the transfer surface corresponding to the length of the substrate (5).

For example and without limitation, in Figures 8a and 8b, the transfer surface (1) can be divided into three sectors (I, 11, III), each sector corresponding to the length of the substrate to be printed. FIG. 8a shows the first printed substrate (51) printed by a first sector (I) of the transfer surface (1) and a step in which a second substrate Io (511) is printed by a second sector (II) of the transfer surface (1), wherein the first sector (1) is cleaned of residual viscous materials (100) by the cleaning device (3) and in which the jet device (2a, ..., 2n) projects or viscous material (100) on a third sector (111) of the transfer surface (1). Fig. 8b shows a step in which a third substrate (5111) is printed by a third sector (III) of the transfer surface (1), in which the second sector (11) is cleaned of residual viscous materials (100). by the cleaning device (3) and in which the letting device (2a 2n) projects viscous material (100) onto the first sector (1) of the transfer surface (1). Figure 8b also shows the second substrate (511) output printed by the second sector (II) of the transfer surface (1). In this example, it is possible to print different text and / or images for each substrate. This device (3) may for example be composed of a set of squeegees and rollers as shown in Figure 1. Some rollers and squeegees may be in direct contact with the transfer surface (1). With reference to FIG. 1, the cleaning device (3) may also comprise a blowing means such as, for example, a blower. Depending on the physicochemical characteristics of the projected materials, this assembly 30 may be completed, for example, and in a nonlimiting manner, by means of adding water, or solvents, by heating means or cooling means. The transfer unit cleaning device (3) may comprise a combination of these various devices so as to be versatile and able to clean different types of material residue.

With reference to FIG. 1, in the case of use of vitreous transition material, the cleaning device (3) may use a heating means so as to raise the temperature of the transfer surface (1) and thus that of the residues. of material present on said transfer surface (1). Once heated, the material residues return to a more liquid state facilitating its elimination. The cleaning may for example be carried out by a stream of air, for example, formed by a blowing means, directed tangentially to the transfer surface (1) so as to project the drops, for example, into a recovery trough ( 18). FIG. 1 shows an exemplary embodiment of such a device in which the blowing means is a hot air cyclone. In the case of use of solvent-based material, the transfer surface will be, for example, first cleaned by a device spraying a solvent on the residues of frozen material to make them fluid again. The material residues will then be removed, for example, by a set of squeegees and rollers or by a violent air stream projecting the drops for example into a recovery container (18). In the second variant, the cleaning device (3) may be, for example, a cleaning means (3) movable moved by mechanical means (31) as shown in Figures 9a and 9b. The movable doctor blade (3) is moved away from the transfer surface (1) when the transparent viscous material (100), for example cured by a heat source (103), and / or the colored material (102) not carried on the substrate (15) after one or more prints is reusable to print other substrates (5). The movable doctor blade is brought closer to the transfer surface (1) to clean the transfer surface (1) of any material when the transparent viscous material (100) and / or the colored material (102) not carried on the substrate after one or more several prints are no longer reusable to print other substrates (5). With reference to FIG. 4, according to an alternative embodiment, the transfer group may comprise an additional transfer surface called the intermediate transfer surface (10). This intermediate transfer surface (10) is intended to be brought into contact with the transfer surface (1) and the substrate (5). The material forming the intermediate transfer surface (10) will be chosen so that the coefficient of adhesion between the material of the intermediate transfer surface (10) and the substrate (5) is greater than that between the material of the transfer surface (1) and the material of the intermediate transfer surface (10) but less than the transfer coefficient between the material of the transfer surface (1) and the projected material (s) in order to guarantee a good transfer of the the subjects. The embodiment variant illustrated in FIG. 4 is in no way limiting and the transfer unit according to the invention may comprise a plurality of intermediate transfer surfaces (10), each of which is brought into contact two by two. As previously, in order to ensure a maximum transfer rate, the materials constituting the various intermediate transfer surfaces (10) will be chosen so as to respect a rule of increasing adhesion of the transfer surface (1) receiving the jets of materials. at the intermediate transfer surface (10) in contact with the substrate (5). For this, the different transfer surfaces (1, 10) will have a coefficient of adhesion defined between the material or materials to be sprayed and the material constituting the transfer surface (1, 10). These coefficients will be chosen increasing when moving from the transfer surface (1), receiving the projections of material, to the transfer surface (1, 10) in contact with the substrate (5), each of the preceding coefficients being less than the coefficient of adhesion between the material to be sprayed and the substrate (5). Each intermediate transfer surface (10) may be vis-à-vis a set of heads and may receive an intermediate image.

In the case of transfer surfaces (1) and intermediate transfer surface (10) supported by cylinders, the cylinders will be chosen so that the diameters are identical so that each cylinder has the same peripheral speed. In general, the transfer surfaces (1, 10) and their support, will be chosen so that they have the same dimensions and thus avoid any offset, deformation or other transfer defect during deferrals. material. The transfer unit may have mechanical means for setting each intermediate transfer surface (10) in motion, such as, for example, motors whose speed can be adjusted so that each transfer surface (1, 10) rotates at the same time. same speed. Each intermediate transfer surface (10) may comprise a cleaning device (3) identical to that described above so as to continuously remove each intermediate transfer surface (10) from any unreferenced material residues. In order to be able to adapt to different types of substrates (5) or different materials or substrate thicknesses (5), the transfer unit may have adjustment means for adjusting the distance between the transfer surface (1, 10) in contact with the substrate (5) and said substrate (5). This device may, for example and without limitation, be set manually by an operator or automatically, for example, by a control station. In addition, this function can also be used to adjust the pressure exerted on the substrate (5) on which the material or materials are reported. The transfer unit comprises mechanical means for moving the transfer surface (1). These mechanical means controlled by a control station are associated with means for regulating the respective speed of the transfer surface (1) and displacement of the substrate (5). The regulating means are controlled so that the linear velocity of the transfer surface, at the moment when the transfer surface comes into contact with the substrate (5) is identical in direction and intensity, at the speed of movement of the substrate (5).

The various transfer group embodiments described above can be intended to be integrated into existing or new machines. FIG. 5 represents an exemplary embodiment of a material transfer system. In this example, the transfer unit is integrated in a rotating machine coil / coil. This example is in no way limiting and the transfer group could very well be integrated, for example and without limitation, to a sheet-fed press or a rotary press comprising a cutting module. In this exemplary embodiment, the transfer system comprises a transfer group, a unwinding system (14) and a coiling system (15) of the substrate (5) onto which the material (s) is projected. In order to facilitate the transfer of material onto the substrate (5), a backpressure cylinder (12) is placed under the transfer unit, the substrate (5) passing between the transfer unit and the backpressure cylinder (12). . This counter-pressure cylinder (12) acts as support for the substrate (5) at the moment of transfer of the material deposit. According to an alternative embodiment shown in FIG. 6, the transfer system may comprise two transfer groups (0) arranged on either side of the transport path of the substrate (5) in order to transfer the material on both sides substrate (5). Preferably, the two transfer groups (0) will be placed one above the other so as to transfer the material at the same time on both sides of the substrate (5). This arrangement also makes it possible to eliminate the backpressure cylinder (12), each pressure group ensuring, for the other transfer group (0), the support function for the substrate (5).

According to another variant embodiment shown in FIG. 7, the transfer system may comprise a number of transfer groups corresponding at least to the number of fundamental colors. In this variant, each transfer group is arranged one after the other in the direction of displacement of the substrate to defer one after another the deposition of material on the surface of the substrate (5). In this variant, the jet unit of the transfer unit comprises, for example, at least one set of transmission heads (2a1, ..., 2an; 2b1, ..., 2bn) intended to project material transparent viscous material and a second set of heads (6a, 6b, 6c) arranged after the first set of heads (2a1, ..., 2an; 2b1, ..., 2bn) in the direction of rotation of the transfer surface ( 1), each head of the second set of heads being intended to project a fundamental colored material. For example, the second set of heads (6a) of the first transfer group (0) is intended to project, for example, cyan (C); the second set of heads (6b) of the second transfer group (0) being intended to project, for example, magenta (M) and the second set of heads (6c) of the third transfer group (0) is intended to project for example, yellow (Y). The system also comprises a reading station (11), in communication with a control station (16), whose role is to analyze the substrate (5) and send back, to the control station (16), the representative signals different information on said substrate (5). This information may be, for example and without limitation, the presence or absence of said substrate (5) under the reading station (11), the speed of the substrate (5) and / or that of marks on said substrate (5) , the position, the composition, the thickness of said substrate (5) or any other information relating to this substrate (5). Referring to Figure 5, between the transfer unit and the winding system (15) is a drying station (13) of the material or deposited on the substrate (5). In the case where the transfer system comprises two transfer groups head to tail, two drying devices (13) will be inserted after said transfer groups. Depending on the characteristics of the materials used, the drying system (13) may, for example and without limitation, be a heat source, a system for polymerization by ultraviolet, infrared, electron beams, or any other source of polymerization. . The advantage of drying by polymerization is that a dry matter is obtained without spending a lot of energy. In addition, the film of polymerizing material, after polymerization, is very resistant to abrasion, aging, light, moisture ...

In another embodiment, the transfer system may comprise a cooling unit between the drying device (13) and the winding device (15). This cooling device makes it possible to lower the temperature of the substrate (5) at the outlet of the drying device (13) before being coiled. The cooling device may for example consist of a set of non-contiguous rollers, on which the substrate (5) will flow, the cooling being provided by the ambient air. Before starting production, the operator prepares the files determining the orders that will have to be sent to the material jet units on the preparation station (17). The files will be produced for example and without limitation, from a set of fixed or variable information such as images and / or texts, from information contained in databases, parameters related to the type of materials to be projected and / or the type of substrate (5) on which these materials are deposited.

The preparation station (17) can also establish, for example, the size of the droplets of material to be sprayed as a function, for example and in a non-limiting manner, of the crushing they undergo during the transfer to the substrate (5), of their composition, properties of the substrate (5) or any other parameter so as to achieve the desired rendering.

These files are then transferred from the preparation station (17) to the control station (16) during a production initialization process. From these parameters, for example and without limitation, depending on the composition and the thickness of the substrate (5), a program, for example, stored in a memory zone of the control station (16), automatically fixes the distance between the transfer surface and the counterpressure cylinder. The control station (16) then sends, to the transfer group, the signals representative of the distance to be set between the transfer surface (1, 10) in contact with the substrate (5) and the counterpressure cylinder. In the case where the counterpressure cylinder (12) is not present, the control station (16) calculates the distance between the two transfer groups and sends the signals representative of this distance to the two transfer groups so as to adjust their distance.

When the production is started, in the case of a transfer system according to the embodiment illustrated in FIG. 4, the substrate (5) flows continuously from the uncoiling group to the rewinding group, passing between a transfer surface. and the counterpressure cylinder (12).

During the travel of the substrate (5), the control station (16) comprises means for sending different electrical signals to the various devices of the transfer system from the information transmitted by the preparation station (17) and those sent by the reading position (11). For example, the control station (16) comprises means for sending different signals representative of a speed reference to the means generating the movements of the transfer group (s) so as to synchronize the linear speed of the one or more transfer surfaces (1, 10) in contact with the substrate (5), with the speed of travel of the substrate (5) in the nip zone, that is to say at the point where the transfer surface (1) , 10) contacts the substrate (5). In parallel, the reading station (11) analyzes, at regular intervals, the traveling speed of the substrate (5) and sends the signals representative of this speed to the control station (16) so as to inform it, in real time, on the running speed of said substrate (5) so that the control station (16) can adjust the speed instructions to be sent to the transfer surface or surfaces (1, 10). The control station (16) also controls the material jet emission units according to the transfers to be made. For this purpose, the control station (16) sends different control signals to the different nozzles of the at least one set of heads (2a1, ..., 2an; 2b1, ..., 2bn, 6a, 6b, 6c), for ejecting or not material on the transfer surface (1), according to the commands established from the parameters sent by the preparation station (17). The commands sent to the or to the set of heads (2a1, ..., 2an; 2b1, ..., 2bn, 6a, 6b, 6c) will also be synchronized, in real time, as a function of the speed of the substrate, from the velocity information of the substrate (5) sent by the reading station (11). The control station (16) can also control the material projection units so as to synchronize the material deposits on the transfer surface (1) with the relative displacement of the substrate (5) on which the material deposits are reported in taking into account the delay caused by the displacement of the transfer surface (1). The control station (16) can also control the colored material projection units to synchronize the material deposits on the transfer surface (1) with the relative displacement of the substrate (5) on which the material deposits are reported in taking into account the delay caused by the displacement of the transfer surface (1) and to project the colored materials on transparent viscous materials already deposited on the transfer surface (1). It also makes it possible to distribute the projection of the different colors according to the files prepared by the operator. For example, the file includes at least one matrix for each primary color.

Each matrix has the coordinates of the colored dots of the image for a color.

The control station (16) can also control the power of the dryer (13). Depending, for example, on the speed of displacement of the substrate (5), its composition, the characteristics of the projected materials and other parameters sent by the preparation station, the control station (16) sends various signals representative of the power instructions to the stations. sources of the dryer, for example and not limited to heat sources, infrared or ultraviolet or a combination of these sources. The advantage of the invention is that it makes it possible to improve, for example and without limitation, offset machines and to give them more flexibility by replacing one or more of the offset printing rollers with a series of heads. material emission by keeping the transfer surface and also attaching material removal means on the transfer surface or surfaces. The transfer group (0) can be used on an offset machine. A lithographic drum of the offset machine is replaced by a transfer unit according to the invention. The mechanical means for driving the lithographic drum are then put in relation with the mechanical means of the transfer group (0). It should be obvious to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed. Therefore, the present embodiments should be considered by way of illustration, but may be modified within the scope defined by the scope of the appended claims, and the invention should not be limited to the details given above.

Claims (11)

REVENDICATIONS1. Digital transfer group (0) of viscous material, by jet, characterized in that it comprises at least: a transfer surface (1) set in motion by mechanical means, a jet unit comprising a first set of heads ( 2a1, 2an; 2b1, ..., 2bn), each head having at least one nozzle individually controlled by a computer system and a digital file, each head being intended to project ad least a viscous material on the transfer surface (1 ) for all the projections to produce an image and / or a text on the; transfer surface (1) corresponding to the image and / or the text of the digital file, the viscous material or materials projected on the transfer surface (1) being transferred to a substrate (5) by bringing into contact the the transfer surface (1) moved by the mechanical means with the substrate (5) driven by drive means of a machine. 2. Transfer unit (0) according to claim 1, characterized in that the viscous material jet unit further comprises at least a second set of heads (6a, 6b, 6c), each head of the second set of heads (6a, 6b, 6e) having at least one nozzle individually controlled and intended to project one or more colored materials on all or part of the viscous material projected on the transfer surface (1), the viscous material of the first set of heads (6a, 6b, 6e) being transparent. 3. Transfer group (0) according to claim 1, characterized in that the first set of heads (2a1, 2an; 2b1, ..., 2bn) is subdivided into a number of groups of heads, each group of heads projecting a colorful viscous material. 4. Transfer group (0) according to claim 3, characterized in that the number of groups of heads corresponds at least to the number of fundamental colors 5. Transfer group (0) according to claims 1 to 4 characterized in that the transfer surface (1) is a continuous surface. Transfer unit (0) according to at least one of Claims 1 to 2, characterized in that the transfer surface (1) is composed of one or a plurality of surfaces which are moved cyclically by mechanical means. 10 7. Transfer unit (0) according to one of claims 1 to 6, characterized in that the transfer surface (1) is associated with a device (4) for modifying the viscosity of the projected viscous material or materials. 8. Transfer unit (0) according to claim 7 characterized in that the device for modifying the viscosity of the projected viscous material or substances consists of an element causing a partial polymerization of the projected viscous material or materials. 9. Transfer unit (0) according to claim 7, characterized in that the device for modifying the viscosity of the projected viscous material or materials is capable of maintaining the viscous material with a glass transition point above its transition point. vitreous in perfectly liquid state. 10. Transfer unit (0) according to claim 9 characterized in that it has a cooling device for bringing the viscous material or materials below their glass transition point. 25 11.Transfer group (0) according to one of claims 1 to 10, characterized in that the material forming the transfer surface (1), on which projections of viscous material and colored materials are made, is such that the coefficient adhesion between the material of the transfer surface (1) and the materials to be deposited is less than that between the materials to be deposited and the substrate (5) to receive said materials. Claims 1 to 11, characterized in that it has a plurality of intermediate transfer surfaces (10), each located opposite a set of heads and receiving an intermediate image, each transfer surface (1 , 10) being in contact two by two and each transfer surface (1, 10) having the same linear speed as that of the substrate (5). 13. Transfer group (0) according to claim 1, characterized in that the transfer group (0) comprises at least two transfer surfaces (1, 10) each performing one or more stages of transfer, by Icontact, of Deposit of materials on intermediate transfer surfaces (10). 14.Transfer group (0) according to one of revendicatioris 1 to 12, characterized in that the different transfer surfaces (1,; 10) have a coefficient of adhesion defined between the materials to be sprayed and the material constituting the surface of transfer (1, 10), these coefficients being increasing as one moves from the transfer surface (1), receiving the material projections, to the transfer surface (1, 10) in contact with the substrate (5). ), each of the preceding coefficients being lower than the coefficient of adhesion between the substances to be sprayed and the substrate (5). 15. Transfer group (0) according to one of claims 1 to 14 characterized in that each transfer surface (1, 10) is thermostated. 16.Transfer group (0) according to one of claims 1 to 15, characterized in that the hardness of the transfer surface (1, 10) in contact with the substrate (5) is less than the hardness of the surface of said substrate (5). 17.Transfer group (0) according to one of claims 1 to 16, characterized in that the transfer unit (0) comprises adjusting means for adjusting the distance between the transfer surface (1, 10), contact with the substrate (5), and said substrate (5). 18. Transfer group (0) according to one of claims 1 to 17, characterized in that the transfer group (0) comprises means for regulating the respective speed of the transfer surface and displacement of the substrate, the means of wherein the linear speed of the transfer surface (1, 10), at the moment when the transfer surface contacts the substrate (5), is identical in direction and intensity to the speed moving said substrate (5). 19.Transfer group (0) according to one of claims 1 to 18, characterized in that each transfer surface (1, 10) is associated with a cleaning device (3) arranged after contact with the substrate on the the transfer surface to allow the removal of the unreferenced material residues on the substrate (5). 20. Transfer group (0) according to claim 19, characterized in that the cleaning device (3) is composed of blowing means and / or a set of doctor blades and rollers some of which are in contact with the surface transfer (1, 10). 21. Transfer group (0) according to one of claims 19 or 20, characterized in that the cleaning device (3) comprises a heat source and / or a wetting device with water and / or at least a solvent to make the residues more fluid before they are removed. 22. Digital material projection system characterized in that it comprises at least one digital transfer group (0) of jet material 20 according to one of claims 1 to 21, a preparation station (17) commands to be sent to the material jet units, a control station (16) for at least the exchange of information between the different devices of the transfer system, a reading station (11) analyzing the substrate (5) and a system of drying (13) the material deposited on the substrate (5). 23. System according to claim 22, characterized in that the substrate (5) passes between a transfer unit (1, 10) and a counterpressure cylinder (12). 24. System according to one of claims 22 or 23, characterized in that it comprises at least two digital transfer groups (0) of jet material arranged to simultaneously report the deposition of material thus made on both sides of the substrate (5). ). 25. System according to claims 22 and 23, characterized in that the number of transfer groups (0) of the system corresponds to at least the number of fundamental colors, each transfer group (0) being arranged one after the other on the same side and in the direction of movement of the substrate (5) to transfer one after the other the deposition of material on the face of the substrate (5). 26. System according to one of claims 22 to 24, characterized in that it comprises a unwinding system (14) and a coiling system (15) of the substrate (5) continuous. 27. System according to one of claims 22 to 24, characterized in that it comprises a sheet sheet feed device and a sheet receiving device on which the material or materials have been transferred. 28. System according to one of claims 22 to 27, characterized in that the preparation station (17) establishes the size of the drops of viscous material and / or colored materials to be sprayed so as to achieve the desired rendering. 29. System according to one of claims 22 to 28, characterized in that the control station (16) controls the sets of heads (2a1 2an 2b1, ..., 2bn, 6a, 6b, 6c) so as to synchronize the projections of viscous and colored materials with the displacement of the substrate (5) taking into account the delay induced by the displacement of the transfer surface or surfaces (1,10). 30.A method for the digital transfer of modifiable viscosity material, characterized in that it comprises: a selective and controlled projection step, on the transfer surface (1), of transparent or non-transparent viscous material in a defined viscosity state; ensuring the maintenance and preservation of the information (image, text) formed on the transfer surface (1), - a transfer step, by contact, of the transfer surface with a substrate (5). 31. A process for the digital transfer of viscosity material, modifiable according to claim 30, characterized in that it further comprises a selective and controlled projection step, on the viscous material projected onto the transfer surface (1), of materials colored, the viscous material having a viscosity able to retain the colored matter. 32. A method for the digital transfer of viscosity modifiable material according to at least one of claims 30 to 31, characterized in that it comprises a step of modifying the viscosity of the viscous material (s) to be sprayed. 33. A method for the digital transfer of modifiable viscosity material according to at least one of claims 30 to 32, characterized in that it comprises a step of cleaning each transfer surface (1, 15). 34. Use of the transfer unit according to claims 1 to 21, on an offset machine, characterized in that it comprises a step of replacing a lithographic drum of the offset machine by the transfer unit, the mechanical means of The lithographic drum is connected to the mechanical means of the transfer unit.