Device and method for drying printed substrates in a printing machine

Abstract

Device and method for drying printed substrates in a printing machine. The present invention relates to the field of printing, in particular to the field of digital printing of inks / varnishes, and more particularly to a device and method for drying the inks / varnishes of printed substrates in a printing machine comprising at least one substrate printing station followed by a printed substrate drying station and a substrate transport station through said printing and drying stations. Figure for the abstract: Fig. 1

Description

Title of the invention: Device and method for drying printed substrates in a printing machine

[0001] The present invention relates to the field of printing, in particular to the field of digital printing of inks / varnishes, and more particularly to a device and a method for drying the inks / varnishes of the printed substrates in a printing machine comprising at least one substrate printing station followed by a station for drying the printed substrate as well as a station for transporting the substrate through said printing and drying stations. INTRODUCTION

[0002] The transport of substrates and, in particular, the drying of the inks / varnishes printed on the substrates during their transport using automated processing or industrial manufacturing is a particular technical challenge. As printing rates and therefore the associated transport speed of the substrates become increasingly important in order to meet production / marketing requirements, all stations of the printing machine must be continuously improved.

[0003] For illustration purposes, optimized and efficient drying is a significant challenge in this process. Drying may include an infrared (IR) and / or near-infrared (NIR) and / or heated airflow drying oven, and / or ultraviolet (UV) and / or UV light-emitting diode (LED) drying and / or a photonic process.

[0004] The present invention relates in particular to the infrared (IR) and / or near-infrared (NIR) drying station which is generally positioned above the printed substrate so as to cover its entire width or its entire useful width as defined below and arranged close to the printing station; this drying station thus usually comprises several infrared drying lamps which remain lit during a printing job in order to avoid damage caused by too frequent switching on / off. Useful width is understood to mean the minimum width of the portion of the printed substrate requiring drying.

[0005] Although drying stations already exist whose drying efficiency can be adapted according to the desired drying, the Applicant has encountered numerous problems when implementing them in the printing machines described below. We will cite by way of illustration the problems of premature aging of all the parts linked to the transport of the substrate and located near the drying station leading to potential inaccuracies not only at the level of the station transport but also in the processing stations located downstream and / or upstream of the drying station; problems linked to premature aging of the printing stations, in particular of the print heads located near the drying station leading to blockages of the printing nozzles and corresponding printing inaccuracies; problems of uniformity of drying across the printed areas of the substrate.

[0006] Drying station manufacturers have also developed their equipment to better control energy dissipation phenomena, for example by developing air channeling and / or blowing devices within the drying station. However, there is still a need that the Applicant has set out to resolve in the present invention. INVENTION - device

[0007] To this end, the invention relates to a substrate printing device comprising at least one ink / varnish printing station, followed by a station for drying the printed substrate without contact with the printed substrate as well as a station for transporting the substrate through said printing and drying stations, in which - the three printing, drying and transport stations are controlled by means of at least one control station, - the drying station is a drying station which comprises infrared (IR) and / or near-infrared (NIR) drying means and a removable opening / closing means controlled by a control station, said removable opening / closing means being positioned between the drying means and the printed substrate.

[0008] The transport of the substrate in the printing machine is preferably carried out flat, horizontally. An essential characteristic of the present invention is that it makes it possible to subject to infrared radiation only the longitudinal and / or transverse portions of the substrate which must be dried, namely those onto which the ink and / or varnish has just been sprayed, while avoiding subjecting the other portions of the substrate or nearby equipment to these same radiations. In the description and claims which follow, the longitudinal direction corresponds to the direction of advancement of the substrate in the plane of the substrate transport path and the transverse direction corresponds to the direction perpendicular to the advancement of the substrate in the plane of the substrate transport path.Any type of substrate transport may advantageously be used within the scope of the present invention; for example, sheet-to-sheet transport in which the substrate is generally stationary on a support which is transported / moved through the printing and drying stations or reel-to-reel transport in which it is the substrate itself which is transported / moved through the printing and drying stations and which therefore plays a role. its supporting role, knowing that the advantages provided by the invention are greater in sheet-by-sheet transport due to the inherent distance separating each printed substrate. In the remainder of the description and the claims which follow, the useful surface of the substrate is defined as being the printed portion(s) of the printed substrate, said portion itself being preferably defined as being the smallest rectangle which surrounds said printed portion(s). INVENTION - process

[0009] The invention also relates to a printing, transporting and drying method, implemented by the substrate printing device according to the invention, in which the control station of the drying station receives instructions from the transport station and / or the printing station to control the opening of the removable opening / closing means during the passage of the useful surface of the substrate and to control the closing of the removable opening / closing means after the passage of the useful surface of the substrate. Figures - illustrations

[0010] The invention, with its characteristics and advantages, will emerge more clearly on reading the description given with reference to the appended drawings in which:

[0011] Figures 1 to 4 schematically illustrate several aspects and several embodiments of the invention, by way of example.

[0012] [Fig-1] shows a device according to the invention, comprising an infrared cassette and a rotating carpet.

[0013] [Fig.2] shows examples for the carpet.

[0014] [Fig.3] shows the arrival of the substrate and the advancement of the belt for a belt whose cutting surface corresponds to that of the cassette.

[0015] [Fig.4] shows the advancement of the belt, for a belt whose sealing surface corresponds to that of the cassette.

[0016] The present invention has numerous advantages over prior art techniques. These advantages provided by the present invention will be further highlighted in the detailed description of the figures.

[0017] A first illustration of the present invention relates to sheet-by-sheet transport due to the inherent distance separating each printed sheet as explained above; indeed, in this illustration, the control station of the drying station will be able to control the removable opening / closing means between each printed sheet pass. For example, the control station of the drying station will be able to synchronize the closing / opening of the removable opening / closing means depending on the presence or absence of the printed sheet to be dried depending on the distance information between each substrate (for example of the order of a few centimeters; for example between 3 and 50 cm) and substrate transport speed transmitted to it by the transport station.

[0018] A second illustration of the present invention relates to sheet-by-sheet transport when the longitudinal dimension of the useful surface of the printed sheet is less than the dimension of the sheet itself. For example, the control station of the drying station will be able to synchronize the closing / opening of the removable opening / closing means not only as a function of the presence or absence of the printed sheet to be dried as a function of the information on the distance between each substrate and the substrate transport speed transmitted to it by the transport station but also as a function of the information on the printing positioning on the sheet transmitted to it by the printing station.

[0019] This second illustration will also advantageously relate to the reel-to-reel illustration of the present invention because the use of the present invention in the reel-to-reel application will depend on the longitudinal distance which separates each useful surface of the reel. Indeed, in the event that a print to be dried is carried out over the entire length of the reel, this second illustration is of no use because the drying will also have to operate continuously.However, and this is what most often characterizes reel-to-reel applications, the image printed on reel-to-reel is generally repeated at regular intervals, which justifies the advantageous use of the invention; thus, the control station of the drying station will be able to synchronize the closing / opening of the removable opening / sealing means not only as a function of the transport speed of the reel transmitted to it by the transport station but also as a function of the printing positioning information on the sheet transmitted to it by the printing station.

[0020] A third illustration of the present invention relates to both sheet-to-sheet application and / or reel-to-reel application, when the transverse dimension of the useful surface is less than the width of the reel and / or the sheet. For example, in sheet-to-sheet application, the control station of the drying station will be able to synchronize the closing / opening of the removable opening / closing means not only as a function of the presence or absence of the printed sheet to be dried as a function of the information on the distance between each substrate and the substrate transport speed transmitted to it by the transport station but also as a function of the information on the printing positioning on the sheet transmitted to it by the printing station.For example, in reel-to-reel mode, the control station of the drying station will be able to synchronize the closing / opening of the removable opening / sealing means not only as a function of the transport speed of the reel transmitted to it by the transport station but also as a function of the printing positioning information on the sheet transmitted to it by the station. printing.

[0021] It will also be understood from the above that a fourth illustration will advantageously correspond to the combination of the second and third illustrations mentioned above.

[0022] In a particular embodiment according to the present invention, the transport speed of the substrate is between 10 and 300 meters per minute. Drying Station

[0023] The drying station according to the present invention follows the printing station along the substrate transport station in the claimed printing device. In general, the distance between the printing station and the drying station along the transport station is between 300 mm and 2000 mm. The drying station according to the present invention therefore comprises infrared (IR) and / or near-infrared (NIR) drying means and a removable opening / closing means controlled by a control station, said removable opening / closing means being positioned between the drying means and the printed substrate.

[0024] The dimensions of the drying means facing the transported printed substrate are generally selected so as to allow efficient drying of the inks / varnishes that may be located over the entire width (or transverse dimension) of the substrate. Illustratively, a transverse dimension (i.e. perpendicular to the longitudinal axis in the plane of the substrate transport path) at least equivalent to the transverse size of the largest substrate used will be cited; as for the longitudinal dimension (in the direction of movement of the substrate), it is generally defined during the design of the printing machine, when all the factors that may impact it are known.As an illustration of the said influencing factors, we will cite the dimensions and types of substrates that will be processed in the printing machine, and / or the types and quantities of inks / vinyls that will be printed on the said substrates, and / or the size of the infrared (IR) and / or near-infrared (NIR) curing lamps as well as their power. An illustration of a transverse dimension ranging from 300 mm to 2000 mm will be cited. An illustration of a longitudinal dimension ranging from 300 mm to 2000 mm will also be cited.

[0025] As regards the dimensions of the drying station, they obviously depend on the sizing of its components, for example the drying means and the removable opening / closing means(s) as well as optionally the cooling means described below.

[0026] The distance between the printed substrate and the drying station can be adjustable depending on the case so as to adapt to substrates of varying thickness. Generally speaking, a distance of the order of a few mm (for example between 2 and 20 mm) is preferred so as to concentrate the effects of the irradiation on the printed substrate and limit environmental irradiation.

[0027] The power range of the heating means will preferably be adapted to the quantity of ink / varnish deposited per unit of surface to be dried, to the content and type of solvent of the inks / varnishes used as well as to the transport speed of the substrate. Illustratively, a power ranging from 1 to 100 kW per square meter, for example from 10 to 50 kW per square meter will be cited; these values ​​being particularly adapted to running speeds of 1 m / s, it will also be possible to illustrate ranges of power values ​​per square meter multiplied by the running speed of the substrate under the heating means of between 1 and 100 kW per square meter second, for example from 10 to 50 kW per square meter second.

[0028] Thus, in a particular embodiment, the present invention relates to a substrate printing device and / or a corresponding implementation method in which the power of the heating means is controlled as a function of the quantity of ink / varnish deposited per unit of surface to be dried, and / or the content and type of solvent contained in the ink / varnish, and / or the speed of transport of the substrate through the drying station; these three criteria are preferably taken into account in the control of the heating means. Removable opening / sealing means

[0029] Any removable opening / closing means positioned between the drying means and the printed substrate may advantageously be selected in the present invention. Mention may be made, by way of illustration, of a system of closable sliding grilles (like ventilation or water evacuation grilles), adjustable blades (like slatted shutters), etc.

[0030] Optionally, the removable opening / closing means is fully mobile.

[0031] Optionally, the removable opening / sealing means is a flat surface, flexible and rotating around the heating means.

[0032] Optionally, the removable opening / closing means is a rotating mat having at least one cutting surface, preferably adapted to the surface of the heating means.

[0033] Optionally, the opening / closing of the removable opening / sealing means is controlled by the control station of the drying station according to the information transmitted by the printing station and / or the transport station.

[0034] Optionally, this information is the transport speed of the substrate through the drying station and / or the distance between each portion of substrate and / or between each substrate to be dried.

[0035] Optionally, the drying station control station controls the rotation speed of a rotating belt.

[0036] Preferably, the maximum opening and closing dimensions are su- greater than or coincide with the transverse and longitudinal dimensions of the heating means; preferably, these dimensions are greater than or coincide with the entire irradiation surface of the heating means. In a particular embodiment according to the present invention, the opening dimensions coincide with the dimensions of the useful surface of the printed substrate(s).

[0037] The emitters of the heating means are generally in the form of tubes with or without an integrated reflector and whose diameter is close to one cm, for example a diameter between 0.5 and 3 cm; for reasons related to their thermal regulation, these tubes are generally spaced apart from each other by an equivalent distance, for example a distance between 0.5 and 3 cm.

[0038] Although closable sliding grids already make it possible to meet some of the challenges mentioned above, their use is not preferred in the context of the present invention because the opening surface of this type of grid (one face of which is fixed) represents only a part of the irradiation surface of the heating means, which drastically reduces the advantages and therefore the interest in their use; in fact, this characteristic implies that the printed substrate only benefits from a part of the irradiation of the heating means and therefore a loss of efficiency. The same applies to orientable blades which, although they are more advantageous than grids, have the same characteristic of partial opening due to their fixed edges.

[0039] Furthermore, the production of these removable opening / closing means composed of closable sliding grids or adjustable blades is complex when it is desired to produce dryers with a high energy density (for example 30kW per m2) due to the high temperatures (which can reach 1000°C or more) to which they are subjected and which cause strong expansion and aging phenomena.

[0040] In a particular embodiment, the removable opening / closing means is, unlike the aforementioned grids and / or blades, entirely mobile which, as explained below in the description, provides an additional advantage in terms of controlling energy dissipation. As an illustration of a mobile removable opening / closing means, at least one mobile element capable of obscuring the heating means in the absence of a useful surface area of ​​substrate to be dried and capable of leaving the necessary opening for the drying means in the presence of a useful surface area of ​​substrate to be dried may be used. In one embodiment, the mobile removable opening / closing means is (or is) a flat surface; for example, a flat, flexible surface that rotates around the heating means.This rotation around the heating means will preferably be carried out in the same direction and in the same sense as that of the substrate transport during the passage of the element. mobile between the heating means and the substrate.

[0041] In a particular embodiment according to the present invention, the control station of the drying station comprises a means for controlling the speed of the movable removable opening / closing means as a function of the substrate transport speed transmitted to it by the transport station. By way of illustration, the transport speed of the movable removable opening / closing means will be between 1 and 400 meters per minute when it is in motion, knowing that it can also remain stationary for very short periods of time so as to guarantee the synchronization objectives described below.

[0042] The following description is given in relation to an exemplary embodiment of a movable removable opening / closing means of the carpet type and, more particularly, of the rotating carpet type, but it is understood that other movable elements as suitable as a carpet could also be used within the framework of the present invention.

[0043] As an illustration of a movable removable opening / closing means, the rotating mat around the heating means will have at least one cutting surface. For illustration purposes, the cutting surface of the mat is rectangular in shape and has a transverse dimension corresponding for example to that of the heating means; for illustration purposes, the cutout of the rotating mat has a shape and dimensions corresponding to those of the entire irradiation surface of the heating means; examples of this type of mat will be described by means of the figures attached and detailed below.The use of several (for example two or three) movable removable opening / closing means (for example mats, (partially) superimposed or not) is also possible even if it will generate additional adjustments in order to achieve the desired effects, namely the generation of a surface which is sometimes closing and sometimes open when implementing the claimed device.

[0044] In a particular embodiment, the drying station also comprises a means for controlling the temperature of the removable opening / closing means because, as indicated above, the temperatures within the drying station can reach 1000°C or even exceed them. To this end, any cooling device may advantageously be used within the scope of the present invention; one or more fans may be cited as an illustration. An additional advantage associated with the selection of a movable removable opening / closing means is that the movement generated by its mobility will contribute to the dissipation of energy; in addition, a cooling device may advantageously be positioned outside the areas located between the heating means and the substrate. Carpet

[0045] In a particular embodiment, when the movable removable opening / closing means is a belt which may be a rotating belt, it is advantageously consisting of one or more layers of woven or non-woven textile materials which preferably have low thermal conductivity and are resistant to high temperatures (e.g. several hundred degrees or more than a thousand or two thousand degrees).

[0046] By way of illustration, high-temperature textile materials are understood to mean a melting point higher than 750°C, 1000°C, 1250°C, 1500°C and even 1750°C.

[0047] By way of illustration, textile materials with low thermal conductivity are understood to mean values ​​of less than 0.5 (measured in W / m°C at a temperature of 500°C), for example less than 0.35, or even less than 0.2. This thermal conductivity may be measured by any appropriate method. Illustratively, the method carried out in accordance with ASTM C-177-76 (“Steady State Heat Transmission Properties by means of the Guarded Hot Plate”) will be cited.

[0048] The thickness of the carpet will advantageously be between 0.1 and 2 mm. This thickness may be measured by any appropriate method. Illustratively, the ASTM D1777 Option 1 method will be cited.

[0049] Illustrative examples include textile materials based on aramid, fiberglass, carbon, graphite, silica, and / or vermiculite.

[0050] The textile materials used are preferably woven textile materials made of continuous filament ceramic fibers. These are advantageously metal oxide fibers which can be easily converted into textiles. The characteristics of these metal oxide fibers may advantageously be selected from one or more of the following characteristics: Refractory fibers of metal oxide such as aluminum oxide, silicon oxide and / or boron oxide, and / or a mixture of two or more of said metal oxides; Refractory fibers of a mixture of metal oxide of Al2O3 / SiO2 / B2O3; Fibers with a diameter of between 5 and 20 microns.

[0051] Optionally, at least one face of the mat will advantageously be aluminized to return part of the energy received, preferably only the inner face of the mat (the one facing the heating means).

[0052] Optionally, the mat may include stiffeners (for example, slats placed transversely), preferably made of materials also having low thermal conductivity.

[0053] The moving belt can be driven by any suitable drive system; by way of illustration, a system comprising two chains or two parallel belts along which it is fixed directly or by means of tensioners (for example springs) will be cited. Impression

[0054] The present invention may prove beneficial for the drying of any type of printing carried out with inks and / or varnishes, whether printing with or without a printing form. The present invention is particularly suitable for digital printing according to the present invention; this printing technique without a printing form uses computer data from a control computer to the printing machine. Any type of digital printing may advantageously be used within the scope of the present invention. By way of illustration, this digital printing may advantageously be selected from processes such as inkjet (continuous or on demand), electrophotography or xerography, magnetography, ionography, elcography, and thermography.Inkjet, however, is the preferred printing technique in the present invention because accidental drying of ink in the nozzles of inkjet print heads represents an additional critical problem for this technology, a problem which has been advantageously solved by the present invention. Substrate

[0055] The present invention may prove beneficial for the drying of any type of printed substrate; by way of illustration, mention may be made of substrates of variable nature (paper, plastic, organic or inorganic, etc.), and / or of variable thickness, and / or of variable dimension (for example and in a non-limiting manner for the sheet-by-sheet application of a format whose sides are of the order of a centimeter, for example an A10 type format, as a more precise example a credit card type format; up to the format whose sides are of the order of several meters, for example an A0 type format or a 2 x 2 meter format). Support

[0056] As already explained above, any type of support may advantageously be used within the framework of the present invention, knowing that in the case of reel-to-reel transport, it is generally the substrate itself which acts as the support; this could also be the case for sheet-by-sheet transport when the transport system consists of means for gripping and moving the substrates, for example clamps arranged on rails or rotating chains.

[0057] In a particular embodiment, the support has at least a dual function, namely that of transporting the substrate as well as that of holding the substrate in a stationary position relative to the substrate during its transport. As an illustration of a system for holding the substrate in a stationary position (for example flat) on the support, we will cite means for gripping or pressing the substrate, for example clamps and / or pinching strips. We will cite as an illustration a belt, for example a rotating belt, for example a suction rotating belt; a rotating belt suction will advantageously be pierced with a multitude of holes allowing the carpet to exert suction and therefore maintain, thanks to this suction force, the substrate on said carpet during transport. This rotating carpet will advantageously be made of materials such as those defined above for the carpet of the removable opening / closing means.

[0058] In a particularly preferred embodiment according to the present invention, the substrate transport device in the printing machine comprises carriages which move through the printing and drying stations, for example by means of a motorization system which allows the movement of said carriages on a fixed rail along a transport path; these carriages which hold the substrates in a stationary position (for example stationary and flat) preferably comprise a table (preferably a suction table) for holding the substrate in a stationary position relative to the table (for example stationary and flat), along the transport path during printing and drying of the substrate (and optionally during any prior, intermediate or subsequent treatment of the substrate).Downdraft tables and their operation are well known to those skilled in the art and the latter will therefore be able to easily use a downdraft table suitable for the present invention. The construction and dimensions of the downdraft table are not critical as long as it fulfills its role of holding the substrate in a stationary position (for example flat). Thus, according to a particular embodiment of the present invention, the force holding said substrate in a stationary position on the downdraft table will be greater than any other force which could cause the substrate to move during treatments of said substrate and / or during movements of the carriage; by way of illustration and non-limiting example, the case of the influence which drying with a heated air current could have on the position of the substrate on the downdraft table will be mentioned, an influence which must therefore be eliminated thanks to the holding force of the downdraft table.The upper part of the suction tables is generally called the suction bed pierced with a multitude of holes allowing the table to exert suction and therefore to hold thanks to this suction force of the substrate on the bed; this bed is usually made mainly of metal (for example aluminum), steel and / or any plastic material and / or polytetrafluoroethylene (also known as Teflon) and / or other suitable composite material and / or ceramic. In an alternative embodiment of the present invention, another type of suction table is used, namely a suction table comprising a honeycomb structural layer.This honeycomb structural layer not only allows the surface temperature to be homogenized but also allows said temperature to be better dissipated throughout the table, which in combination with the drying station according to the present invention provides a synergy of advantages when implemented. This . honeycomb structural layer has several additional functions / advantages among which we will cite for illustrative and non-limiting purposes

[0059] • an upper surface sufficiently flat to hold the substrate in position,

[0060] • to allow the passage of air so as to ensure a depression behind the substrate and therefore optimal support in the suction table option,

[0061] • to limit the effects of thermal conduction with the substrate due to its low contact surface,

[0062] • to limit the effects of thermal conduction with the lower and upper layers above the table (which has proven particularly relevant for certain processing stations, for example the infrared drying station),

[0063] • to participate in the elimination of vibration problems encountered with the dis prior art transport positives,

[0064] which therefore makes it possible to improve the transport of printable and printed substrates across all the processing stations included in a printing machine, in particular a printing machine without contact with the substrate, such as inkjet printing machines.

[0065] By way of illustration and without limitation, the honeycomb structural layer has a thickness “e” of between 1 and 100 mm, for example between 5 and 30 mm, preferably between 5 and 15 mm, for example 8 mm; the size of the cells (for example alveoli) is between 10 microns and 10 mm, for example between 1 and 8 mm, preferably between 2 and 5 mm, for example 3.6 mm; the thickness of the walls of the cells (for example alveoli) is between 0.5 microns and 5 mm, for example between 10 and 200 microns, preferably between 30 and 100 microns, for example 50 μm.

[0066] By way of illustration and not limitation, the honeycomb structural layer has regular hexagonal paving; it is therefore made up of right prisms with a hexagonal base (which therefore preferably do not include holes in their vertical walls).

[0067] The surface dimensions of the honeycomb structural layer will be selected according to the needs and applications and will preferably correspond at least to the surface of the substrate (or substrates if there are several held on the same table); we will cite by way of illustration dimensions (1 / L) in mm of the order of 760 / 1070. The widths / lengths of this honeycomb structural layer (for example a frame of rectangular parallelepiped shape with a height corresponding to the aforementioned thickness "e") will preferably coincide with those of the lower suction layer.

[0068] In a particular embodiment of the present invention, the honeycomb structural layer is removably fixed to the table, which allows it to be replaced and / or changed depending, for example, on the types of substrates used. Any removable fixing system may advantageously be used; we will cite as illustrating a toggle-type and / or clip-on type attachment.

[0069] According to an alternative embodiment of the present invention, the honeycomb structural layer is made of aluminum; it is obvious that those skilled in the art will know how to select other materials, similar or not to aluminum, which will also meet the requirements of the present invention, for example steel and / or any suitable plastic and / or composite and / or ceramic material. LATTICE

[0070] In a particular embodiment of the present invention, the sole or table (for example the suction table) comprises a structural overlayer consisting of a substrate holding mesh, a mesh resistant to high temperatures. By way of illustration and not limitation, this mesh can advantageously be used for low-grammage substrates; which makes it possible to avoid any possible "marking" of said substrates when they are immobilized on the table. In fact, without wishing to be limited by this explanation, the Applicant believes that the use of a substrate holding mesh of this type also makes it possible to avoid premature aging of the sole or the holding table while guaranteeing and improving the homogenization of the suction.

[0071] By way of illustration and not limitation, a ceramic fiber grid may advantageously be used as a trellis; said trellis will advantageously be made of materials such as those defined above for the mat of the removable opening / closing means. An additional characteristic of this trellis / mat will be to guarantee good suction of the suction elements for holding the substrates; thus, the air permeability of said trellis / mat will be sufficient to allow this holding; by way of illustration, an air permeability (in (cm3 / cm2 / sec)@ 125Pa) greater than 10, for example greater than 25 will be cited.

[0072] For illustrative and non-limiting purposes, the mesh of the lattice will be selected from fine meshes to avoid a textured printed paper. Inks / varnishes

[0073] Any type of material to be dried by a drying station as defined above may advantageously benefit therefrom. As already explained above, the invention is particularly suitable for inks / varnishes printed on a substrate.

[0074] In a particular embodiment, the inks / varnishes are solvent-based and / or water-based; preferably with a solvent and water content greater than 15% by weight of the ink, greater than 30% by weight of the ink, or even greater than 45% by weight of the ink, or even greater than 80% by weight of the ink (weight of the solvent and water, divided by the weight of the ink). Figures

[0075] Figures 1 to 4 schematically illustrate an overall view of the drying means and a removable opening / closing means according to the present invention. As a drying means, one can see an infrared cassette (represented by the rectangular parallelepiped and which advantageously comprises lamps and reflectors) around which a rotating mat rotates; as well as a cutout of the mat of rectangular shape whose transverse dimension corresponds to the transverse dimension of the irradiation surface of the heating means (in this case the length of the infrared cassette) while its longitudinal dimension corresponds to or is greater than the longitudinal dimension of the irradiation surface of the heating means (in this case, the width of the infrared cassette).

[0076] Thus, when the printed substrate to be dried passes under the cassette, the control station of the heating station will control in the most appropriate manner not only the power / temperature emitted by the drying means (for example the infrared lamps) but also the positioning and rotation speed of the belt according to the information received by said control station, information such as the position of the substrate (or the useful surface of the substrate) to be dried in the printing machine, its transport speed as well as the length of the area to be dried (in the direction of travel of the substrate).This information will not only define the passage of the cutting of the carpet under the heating means but also the presence of the carpet under the heating means between two successive drying operations, which makes it possible to avoid dissipating heat towards the transport station and the printing station when drying is not necessary even though the heating means remain switched on for the reasons already mentioned in this introduction.

[0077] By proceeding in this way, the Applicant has not only managed to optimize the drying while protecting itself from the harmful effects linked to heating such as mechanical problems (for example expansion and / or aging) within the transport station or even problems of ricochet drying of the printing means (for example the print heads themselves). In addition, the Applicant believes that maintaining the heating atmosphere within the drying station when the removable opening / closing means is closed contributes, when the removable opening / closing means is reopened, to better homogeneity or even efficiency of the drying.

[0078] In Figures 1 and 3, the cutting surface of the mat corresponds to that of the infrared cassette. This is also true in the sub-figures at the top left and bottom of [Fig.2]; the bottom sub-figure illustrates a mat with 2 identical spaced cutouts.

[0079] In [Fig.4], it is the sealing surface of the carpet which corresponds to that of the infrared cassette. The same is true in the sub-figures at the top right of [Fig.2]

[0080] In [Fig.3], it can be described starting from the sub-diagram at the bottom right which illustrates the arrival of the printed substrate (which is transported from right to left) in the drying station as well as the clockwise rotation of the opening / closing belt; the front cutting edges of the belt and of the portion of substrate to be dried (in this case in the illustration the front edge of the substrate) coincide during their respective advance which allows the progressive opening of the surface located under the heating means.Then three cases may arise, namely that the longitudinal dimension (in the direction of transport) of the portion of substrate to be dried is less than, equal to or greater than the longitudinal dimension of the opening surface of the belt because this factor can advantageously be taken into account by the belt drive system; in fact, as there is a means of controlling the speed of the movable removable opening / closing means as a function of the substrate transport speed transmitted to it by the transport station, it will be sufficient to ensure that the speed of the belt is less than, identical to or greater than the substrate transport speed so that the rear cutting edges of the belt and of the portion of substrate to be dried (in this case in the illustration the rear edge of the substrate) coincide during their respective advancement which allows the correct progressive closing of the surface located under the heating means.

[0081] The present invention also relates to the use of the device and / or the printing method according to any one of the embodiments already described in an inkjet printing machine which projects a solvent-based and / or water-based ink or varnish.

[0082] The present application describes various technical features and advantages with reference to the figures and / or to various embodiments. Those skilled in the art will understand that the technical features of a given embodiment may in fact be combined with features of another embodiment unless the opposite is explicitly mentioned or it is obvious that these features are incompatible. Furthermore, the technical features described in a given embodiment may be isolated from the other features of this embodiment unless the opposite is explicitly mentioned.

[0083] It should be apparent 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. Accordingly, the present embodiments should be considered illustrative, 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

Claims

1. Substrate printing device comprising at least one ink / varnish printing station, followed by a station for drying the printed substrate without contact with the printed substrate as well as a station for transporting the substrate through said printing and drying stations, characterized in that the three printing, drying and transport stations are controlled by means of at least one control station, the drying station is a drying station which comprises infrared and / or near-infrared drying means, a control station and a removable opening / closing means controlled by the control station of the drying station, said removable opening / closing means being positioned between the drying means and the printed substrate.

2. Device according to claim 1, characterized in that it is configured to control the power of the drying means as a function of the quantity of ink / varnish deposited per unit of surface to be dried, and / or the content and type of solvent contained in the ink / varnish, and / or the speed of transport of the substrate through the drying station.

3. Device according to one of the preceding claims, characterized in that the removable opening / closing means is entirely movable.

4. Device according to any one of the preceding claims, characterized in that the removable opening / closing means is a flat, flexible surface which rotates around the drying means.

5. Device according to any one of the preceding claims, characterized in that the removable opening / sealing means is a rotating mat.

6. Device according to any one of the preceding claims, characterized in that the removable opening / sealing means is a rotating mat consisting of one or more layers of woven or non-woven textile materials.

7. Device according to any one of the preceding claims, characterized in that the removable opening / sealing means is a rotating mat made of high-temperature textile materials having a melting point above 750°C, or even above 1000°C, 1250°C, 1500°C and even 1750°C.

8. Device according to any one of the preceding claims, characterized in that the removable opening / closing means is a rotating belt made of textile materials having thermal conductivity values measured in W / m°C at a temperature of 500°C of less than 0.5, for example less than 0.35, or even less than 0.

2.

9. Device according to any one of the preceding claims, characterized in that the removable opening / closing means is a rotating belt having at least one cutting surface, preferably adapted to the surface of the drying means.

10. Device according to any one of the preceding claims, characterized in that the opening / closing of the removable opening / sealing means is controlled by the control station of the drying station as a function of the information transmitted by the printing station and / or the transport station.

11. Device according to the preceding claim, characterized in that this information is the speed of transport of the substrate through the drying station and / or the distance between each portion of substrate and / or between each substrate to be dried.

12. Device according to any one of claims 9, 10 and 11, characterized in that the control station of the drying station controls the rotation speed of the rotating belt.

13. Device according to any one of the preceding claims, characterized in that the printing is of the sheet-to-sheet or reel-to-reel type.

14. A method of printing, transporting and drying, implemented by the substrate printing device according to any one of the preceding claims, characterized in that the control station of the drying station receives instructions from the transport station and / or the printing station to control the opening of the removable opening / closing means during the passage of the useful surface of the substrate and to control the closing of the removable opening / closing means after the passage of the useful surface of the substrate, the useful surface of the substrate being the printed portion of the printed substrate.

15. Use of the device and / or method according to any one of the preceding claims for an inkjet printing machine which projects a solvent-based and / or water-based ink or varnish.

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