Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
  • B28B11/04—Apparatus or processes for treating or working the shaped or preshaped articles for coating or applying engobing layers
  • B28B11/048—Apparatus or processes for treating or working the shaped or preshaped articles for coating or applying engobing layers by spraying or projecting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
  • B05B1/14—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with multiple outlet openings; with strainers in or outside the outlet opening
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
  • B05B1/14—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with multiple outlet openings; with strainers in or outside the outlet opening
  • B05B1/20—Arrangements of several outlets along elongated bodies, e.g. perforated pipes or troughs, e.g. spray booms; Outlet elements therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B9/00—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour
  • B05B9/03—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material
  • B05B9/04—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material with pressurised or compressible container; with pump
  • B05B9/0403—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material with pressurised or compressible container; with pump with pumps for liquids or other fluent material
  • B05B9/0416—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material with pressurised or compressible container; with pump with pumps for liquids or other fluent material with pumps comprising rotating pumping parts, e.g. gear pump, centrifugal pump, screw-type pump
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B9/00—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour
  • B05B9/03—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material
  • B05B9/04—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material with pressurised or compressible container; with pump
  • B05B9/0403—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material with pressurised or compressible container; with pump with pumps for liquids or other fluent material
  • B05B9/0423—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material with pressurised or compressible container; with pump with pumps for liquids or other fluent material for supplying liquid or other fluent material to several spraying apparatus
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
  • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
  • B41J2/01—Ink jet
  • B41J2/17—Ink jet characterised by ink handling
  • B41J2/18—Ink recirculation systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J3/00—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed
  • B41J3/407—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B15/00—Details of spraying plant or spraying apparatus not otherwise provided for; Accessories
  • B05B15/50—Arrangements for cleaning; Arrangements for preventing deposits, drying-out or blockage; Arrangements for detecting improper discharge caused by the presence of foreign matter
  • B05B15/58—Arrangements for cleaning; Arrangements for preventing deposits, drying-out or blockage; Arrangements for detecting improper discharge caused by the presence of foreign matter preventing deposits, drying-out or blockage by recirculating the fluid to be sprayed from upstream of the discharge opening back to the supplying means

Definitions

• the present invention relates to a method for coating at least one print medium, comprising the step of providing at least one coating head with a fluid supply channel, a plurality of nozzles, each with a nozzle channel and an inflow opening, which form the connection between the respective nozzle channels and the fluid supply channel, with the respective nozzles being stationary on a side wall of the fluid supply channel are arranged; the step of filling the fluid supply channel with liquid fluid; the step of transporting the at least one print medium along a transport direction and the step of subjecting the liquid fluid to pressure at least during the time intervals in which the at least one print medium is to be coated, at least in the area of each inflow opening of the nozzles, with a respective overpressure relative to the ambient air pressure, such, that the liquid fluid is applied to the at least one pressure medium in the form of continuous columnar fluid jets.
• Processes for coating print media are typically used in order to provide print media with at least one coating as uniformly as possible, which is able to fulfill specific functional and/or decorative purposes and is intended to improve the surface properties of the print media.
• Non-contact methods for coating are preferably used when relatively high coating speeds are to be used, and are very preferably used when a relief-like decoration provided on the surface of a print medium, in particular a ceramic print medium, is to be coated.
• a process known for several decades for coating ceramic surfaces of tiles comprises the step of providing a bell-shaped application system with a bell neck and bell rim and the step of applying a glaze suspension over the bell neck by using this starting from the bell neck to the edge of the bell and then poured over this in the form of a curtain onto the print media running in a transport direction underneath.
• this method has the problem that due to the semicircular glaze curtain formed in combination with the relative movement between the glaze curtain and the print medium, more quantity is applied to the surfaces of the print media over the edge areas of the curtain than over it the center area of the curtain to the surfaces of the print media. Since the tiles usually have a temperature of over 40°C during this process, the coating dries quickly so that only shell-shaped, curved layer thicknesses can be achieved.
• the currently most widespread coating method in the ceramics industry comprises the step of applying a glaze suspension to ceramic surfaces while atomizing it, i.e. distributing it into fine droplets, by means of one or more atomizing nozzles in the direction of the respective printing media.
• the suspension is applied by periodically moving the one or more nozzles, offset from one another, if necessary, back and forth along predetermined paths and spray patterns.
• one or more stationary fluid-atomizing nozzles are provided in order to apply the glaze suspension to the surface of the respective print media with the formation of glaze strips lying directly next to one another.
• the aforementioned devices and methods are available, for example, either from Airless Italia S.R.L. marketed under the name "airless” or by Airpower Group S.R.L under the name "slim cover”.
• Fluid atomizing methods are advantageous compared to the bell method, since they can apply significantly less glaze suspension compared to the latter, which means that costs can be saved.
• they also have the disadvantage that it is not possible to apply the suspension to the surface in a highly homogeneous manner. This is due to the partially overlapping glaze stripes and/or the glaze stripes that are directly lined up by the spray pattern - especially on relatively wide formats of a ceramic printing medium - in which the realization of homogeneous transitions between the respective glaze stripes is practically impossible. This is due to the spray patterns of the individual nozzles, which cannot produce homogeneous stripes of glaze.
• Another disadvantage is the high loss of material associated with the necessary suction of the spray mist formed over the print media goes hand in hand, which would otherwise lead to greater inhomogeneity of the order in addition to contamination of the environment.
• Banding effects are known to be visible impairments in the quality of a coating and are characterized by the fact that abrupt or continuous transitions of attributes, such as gloss and/or color and/or structure (height), become visible and visible in a coating applied to a surface unpleasantly noticeable where no transitions of this kind are desired but occur due to the process.
• attributes such as gloss and/or color and/or structure (height)
• the prior art also includes coating systems with an elongated slit or an elongated tear-off edge, each usually at least 50 cm wide, for coating print media with a liquid fluid in the form of a freely falling curtain, i.e. only due to the force of a sword.
• the methods carried out with these systems have the disadvantage that a highly uniform application of liquid fluid is not possible due to the inherent mechanical shortcomings of an elongate slot or an elongate tear-off edge. This occurs, for example, when the respective printing media to be coated are at a relatively high temperature, so that the applied coating dries before the liquid fluid fleas equalize, if such a flee compensation would have been possible at a lower temperature.
• EP1252937A1 discloses such a coating system in FIG. 2 and a corresponding method in which, in a first step for coating, a liquid coating composition is pumped into a reservoir located above a print head, from where in a second step it is poured solely through the coating composition gravitational force flows down into a header and then flows through the slot in the form of a free-falling curtain-like film to be applied to the respective print media.
• This method uses the same principle as the bell method, except that it uses an open fluid circuit, in which the liquid coating composition not applied to the respective print media is returned to the fluid circuit.
• a novel process for fully coating ceramic surfaces includes the step of applying a glaze suspension using a drop-on-demand (DOD) inkjet printing process, in which the glaze is dispensed in the form of drops from a custom-built printhead of an inkjet printing system.
• DOD drop-on-demand
• the systems that make such processes possible are suitable for solving the above-mentioned disadvantages of the non-uniform delivery and application of the glaze suspension to the printing medium.
• they have many parts and a complicated structure, so that the purchase and in particular the maintenance is and will be disproportionately expensive for the customer.
• systems and processes working with DOD are actually geared to the purpose of not printing full areas, but an infinite variety of patterns and thus only partial areas of print media.
• An alternative method for the complete coating of ceramic print media provides for the application of glaze suspension by means of a print head with a row of nozzles, each of which is assigned an electronically controllable closure body for opening and closing the same, and which method is designed to apply several glaze strips to the ceramic surface to be applied in such a way that the glaze suspension is applied to the surface in the form of a plurality of essentially continuous glaze threads.
• the ink in the print head is always subjected to overpressure, with the closure bodies being moved from a shut-off position, in which each of them closes the nozzle assigned to it in a fluid-tight manner, to an open position and remaining in this position, in order to dispense the suspension.
• a glaze suspension is to be applied to the respective pressure media with these methods, deposits and accumulations of the solid particles also occur on the valve seat, i.e. in the area of the inflow opening of the nozzle channel of the respective nozzle. If, after a while, during which no suspension has been dispensed, it is dispensed again, it is not uncommon for the nozzles to become at least partially clogged by the accumulated particles, and as a result there are either streaks on the print media running in one transport direction, or the affected nozzles fail completely.
• particles of the glaze suspension flowing between the closure body and the valve seat of the respective nozzle have a negative effect in that the sealing step can no longer be carried out properly, i.e. suspension is still dispensed via the nozzles even in the actual sealing step, even if in smaller quantities.
• Coating systems of simple design enables the production of coatings in an economical manner.
• the present invention is therefore based on the object of specifying a simple method for coating at least one print medium as uniformly as possible, which can work with a wide variety of coating systems, in particular with systems of a simple design, and can therefore be used flexibly, and in particular with
• Coating systems of simple design enables the production of coatings in an economical manner.
• the object is achieved according to the invention with a method of the type mentioned in that the liquid fluid is subjected to a respective negative pressure relative to the ambient air pressure at least in the region of each inflow opening of the nozzles during the time intervals in which no liquid fluid is to be dispensed from the nozzles.
• the method according to the invention is a method for coating at least one print medium, comprising the steps: a) providing at least one coating head with a fluid supply channel, a plurality of nozzles, each with a nozzle channel and an inflow opening, which form the connection between the respective nozzle channels and the fluid supply channel, the respective nozzles being fixedly arranged on a side wall of the fluid supply channel; b) filling the fluid supply channel with liquid fluid; c) transport of the at least one print medium along a transport direction; d) Subjecting the liquid fluid at least during the time intervals in which the at least one printing medium is to be coated, at least in the area of each inflow opening of the nozzles, to a respective excess pressure relative to the ambient air pressure, such that the liquid fluid can be applied in the form of continuous columnar fluid jets onto the at least one print medium takes place.
• a step e) during the time intervals in which no liquid fluid is to be discharged from the nozzles, the liquid fluid is subjected to a respective negative pressure relative to the ambient air pressure, at least in the area of each inflow opening of the nozzles, as a result of which liquid fluid flows out of the nozzle channels also prevented in step e) and made possible in step d) without or without the participation of the respective closure bodies assigned to the nozzles.
• a fluid circuit system for supplying the at least one coating head with liquid fluid, comprising the at least one coating head is provided, which system during operation forms a fluid circuit closed to the atmosphere except for the nozzles of the at least one coating head the liquid fluid is pumped in a flow direction RF, preferably permanently.
• This development offers the advantage that contamination of the liquid fluid by ambient air loaded with accumulation and a change in the composition of the liquid fluid by evaporation into the atmosphere is avoided.
• this development has the advantage that the risk of the liquid fluid drying out in the nozzle channels and/or at the nozzle openings can be drastically reduced or even prevented, as a result of which oblique jets or clogged nozzles can be partially or completely avoided.
• the liquid fluid can also be pumped at times in a second flow direction opposite to the flow direction RF mentioned, in order to To enable entrainment of particles of a suspension stuck in the circuit at certain points, which could not be entrained by pumping the liquid fluid in the first flow direction RF.
• the fluid pressure in combination with the capillary pressure is to be set in such a way that no air is sucked into the fluid supply channel through the respective nozzle channels and that no liquid fluid escapes from the nozzle channels unintentionally.
• the fluid pressure is the sum of the circulation pressure and the negative meniscus pressure.
• the liquid fluid can be pumped, preferably permanently, through the fluid circulation system by means of a pump, preferably a peristaltic pump or a centrifugal pump.
• the centrifugal pump can be a circulating pump, for example.
• This development has the advantage that if at least one coating head is filled with a suspension as a liquid fluid, sedimentation of the particles of the suspension is also prevented in the area of the inflow opening of the respective nozzles, which in turn reduces the risk of the particles agglomerating with one another and/or the Risk of clogging of the respective nozzle is effectively reduced or even prevented by the particles.
• the liquid fluid is subjected to overpressure using a first means for subjecting the liquid fluid to overpressure and the liquid fluid is subjected to negative pressure using a second means to subject the liquid fluid to negative pressure, with a transition from step e) to step d) in that a first fluidic connection between the fluid supply channel and the first means is opened and a second fluidic connection between the fluid supply channel and the second means is closed and during step d) the first fluidic connection remains open and the second fluidic connection remains closed, wherein a The transition from step d) to step e) takes place by closing the first active fluid connection between the fluid supply channel and the first means and opening the second active fluid connection between the fluid supply channel and the second means et is and during step e) the first fluidic connection remains closed and the second fluidic connection remains open.
• step d) to step e) and from step e) to step d) preferably take place abruptly and in particular simultaneously, for example in that during the first-mentioned transition the first fluidic connection is abruptly closed by means of a first valve provided in the first fluidic connection and the second Fluid operative connection is opened abruptly by means of a second valve provided in the second fluid operative connection, with the second-mentioned transition correspondingly opening the first valve abruptly and closing the second valve abruptly.
• the desired pressure states can be set even more quickly in the respective area of the inflow openings of the nozzles. Consequently, the amount of liquid fluid that should not be applied to the at least one print medium can be further reduced.
• the liquid fluid can be pressurized using an excess gas pressure reservoir of the first means, while the excess pressure prevailing in the excess gas pressure reservoir is controlled, preferably automatically, relative to the ambient air pressure with a compressor of the first means, and the liquid fluid being pressurized with Negative pressure takes place with the aid of a negative gas pressure reservoir of the second means, during which the negative pressure prevailing in the negative gas pressure reservoir is controlled, preferably automatically, relative to the ambient air pressure with a vacuum pump of the second means.
• the liquid fluid in the area of each inflow opening of the nozzles is subjected to a respective excess pressure relative to the ambient air pressure, such that in step d) per unit of time between 1/50 and 1/2, preferably between 1/15 and 1/3 of the volumetric amount of liquid fluid pumped through the fluid supply channel is discharged through the nozzles, wherein the cross-sectional area of the fluid supply channel of the at least one coating head is preferably at least 1 cm 2 , in particular at least 2 cm 2 .
• the delivery of fluid via the respective nozzles only causes a pressure loss over the length of the supply channel, which is negligible compared to the pressure loss caused by friction if the cross-sectional area of the fluid supply channel of the at least one coating head is at least 1 cm 2 , in particular at least 2 cm 2 , and the nozzles of the at least one coating head are provided as micro-nozzles.
• the method further comprises the steps:
• the fluid circuit system with a fluid path that fluidly connects a fluid tank to the at least one coating head, wherein the fluid path fluidly connects the at least one coating head between a supply line and a return line, which are each coupled to the fluid tank, so that liquid fluid from the fluid tank via the supply line is pumped through the coating head and via the return line back to the fluid tank, preferably permanently,
• the fluid tank is provided with a sufficiently large capacity for the liquid fluid and with a free liquid fluid surface to the cross-sectional area of the fluid supply channel in a ratio of >10:1, preferably in a ratio of >20:1.
• a cross-sectional area of a fluid supply channel of a coating head is understood to mean that area in the fluid supply channel that is aligned transversely to the flow direction R F and through which the liquid fluid flows.
• This further development has the advantage of a very short adjustment time for the desired pressure state in the area of each inflow opening of the nozzles, both during the transition from step e) to step d) and during the transition from step d) to step e).
• the selection of such a ratio causes, for example, in the transition from step e) to step d) an acceptable, deviating volume flow from the specified target volume flow per nozzle, which results in an optically, i.e. with the naked eye, imperceptible application height change compared to a predetermined target application height of the liquid fluid on the at least causes a pressure medium.
• the transition from step d) to Step e) initiated or carried out the transition from step d) to Step e) initiated or carried out.
• an edge region of the print medium that is leading in the transport direction of the same or the edge regions of the same that are leading in the transport direction of the print media are each coated with slightly less liquid fluid, but a very small or no amount of liquid fluid is not applied to the respective print media.
• the first fluid operative connection can be provided as a direct first gas operative connection between the fluid circuit system and the first means, in particular as a direct first gas operative connection between the fluid tank and the first means, and/or the second fluid operative connection can be provided as a direct second gas operative connection between the fluid circuit system and the second means, in particular as a direct first gas connection between the fluid tank and the second means, are provided.
• the coating of liquid fluid applied to the at least one printing medium prefferably be concentrated and/or hardened, preferably immediately after application.
• a further layer or a colored image can be applied to the narrowed and/or hardened layer without loss of time.
• the method according to the invention further comprises the step that a coating head arrangement with a plurality of coating heads is provided, each coating head having at least one row of nozzles aligned at a certain angle to the transport direction of the at least one printing medium and the coating head arrangement having an effective row length, and wherein the coating head arrangement is designed in such a way that the coating heads can be fluidically connected to the fluid path, in particular to the supply and return line, parallel to one another and/or in series with one another and at least one coating head can be fluidically separated from the fluid circuit system, with at least temporarily during the transport of the at least one print medium through the effective range of the effective row length of the coating head arrangement in step d), preferably all the time in step d), at least that coating head of the meh reren coating heads is fluidically separated from the fluid circuit system, in particular from the supply and return line, preferably automatically, to which the at least one pressure medium is not exposed.
• the at least one coating head of the fluid circuit system can have a valve upstream of the coating head and a valve in the flow direction of the fluid be provided downstream of the coating head, which are controlled in particular automatically.
• This development has the advantage that the amount of fluid that is not applied to the at least one print medium or to the respective print media can be further reduced if the print medium or the print media each have a width that corresponds to the effective row length of the coating head arrangement undercut or undercut.
• the at least one coating head is provided, in which the plurality of nozzles are arranged relative to one another and during step d) such a large quantity of liquid is discharged from the nozzle channels that the directly adjacent nozzles onto the print medium or the liquid fluid applied to the respective print media flows into one another during and/or immediately after the corresponding application to the at least one print medium or to the respective print media, in order to form a flat coating that is homogeneous throughout the entire width of the print medium or the respective print media to train.
• This preferred solution has the advantage that it enables the formation of a homogeneous coating over the entire application width in the flea, so that a coating with a substantially flat surface or flat surface is achieved.
• the method further comprises the step that at least some nozzles of the at least one coating head each have an actuator with an end face located in the fluid supply channel for the respective control of the flow rate of the liquid fluid between the end face of the actuator and an end face surrounding the inflow opening is assigned to the nozzle, wherein a pressure drop of the liquid fluid present along the fluid supply channel in the flow direction R F of the liquid fluid at the respective inflow openings of the nozzles while it is being pumped from an inlet opening to an outlet opening of the fluid supply channel, by adjusting the respective distance between the respective end faces of the actuators and the respective end faces of the nozzles surrounding the inflow opening is partially compensated with respect to a selected nozzle by corresponding to nde distance, preferably once for a liquid test fluid, is reduced or increased by moving the end face of the respective actuators in the direction of the nozzle.
• This preferred development offers the advantage that differences in the volume flow of the fluid through the respective nozzle channels, which differences corresponding volume flows resulting from nozzles arranged along the fluid supply channel can be partially reduced. Due to the partial reduction of these volume flow differences, an even more homogeneous fluid coating can be implemented on the respective print media.
• the setting of the respective distance between the respective end faces of the actuators and the respective end faces of the nozzles surrounding the inflow opening is typically set once after the fluid supply channel has been filled with a liquid test fluid, which is preferably a liquid fluid.
• a control valve is formed for the respective nozzle, which serves to regulate the flow by changing the distance between the end face of the actuator and the end face of the nozzle surrounding the inflow opening, and thereby also the volume flow of the fluid through the nozzle channel to regulate.
• the respective actuators with the end face lying in the fluid supply channel are also designed to work together with the nozzles assigned to them to close the nozzles, with at least part of the time, preferably all the time, during the transport of the at least one print medium through the effective range of the effective row length of the coating head arrangement in step d), those nozzle or nozzles are or are closed in a fluid-tight manner, preferably automatically, to which the at least one print medium is not exposed during its transport through the effective range of the effective row length of the coating head arrangement, by the end faces of the respective actuators moved towards the nozzles assigned to it and arranged in a fluid-tight manner.
• This development offers the advantage that the delivery width of the fluid can be precisely matched to the width of the print medium to be coated, so that the amount of fluid that is not to be applied to the print medium is further reduced.
• a liquid composition or a suspension which is preferably a non-Newtonian fluid, can be used as the liquid fluid.
• the nozzles of the at least one coating head preferably all coating heads, to be provided as micro-nozzles.
• a micronozzle is understood to mean a nozzle comprising a nozzle channel, which is defined by a lateral surface and two base areas, the length of the jacket being longer than the width of the respective base area, and the width of the respective base area > 15 pm and ⁇ 1000 pm, preferably > 50 pm and ⁇ 500 pm, particularly preferably > 80 pm and ⁇ 500 pm, very particularly preferably > 200 pm and ⁇ 400 pm, and one base area forms the inflow opening to the nozzle channel and the base area opposite the inflow opening forms the outflow opening of the nozzle channel.
• the liquid fluid is subjected in step d), at least in the area of each of the inflow openings of the nozzles, in particular the micro-nozzles, to a respective excess pressure relative to the ambient air pressure, which is in a range between 10 mbar and 1500 mbar, preferably in a range between 200mbar and 400mbar, above atmospheric pressure, so that preferably an output volume flow of the fluid from the respective nozzle channels is achieved in a range between dmI/sec and 100mI/sec.
• a plurality of print media are transported along the transport direction, with at least some of the print media being transported at a distance in the transport direction from at least one of their closest neighbors to be coated, which creates gaps in the transport direction between these spaced-apart adjacent print media, the respective gaps in the transport direction being fictitious can be divided into a central area and a leading and trailing edge area, and wherein in step d) the liquid fluid is also applied before, and preferably also after, the time intervals in which the respective print media are to be coated, at least in the area of each inflow opening of the Nozzles with a respective overpressure relative to the ambient air pressure takes place in such a way that liquid fluid in the form of continuous columnar fluid jets also, however, exclusively in predetermined fictitious leading Ran d-areas and/or is delivered from the nozzles, however, exclusively in predetermined fictitious trailing edge areas of the respective gaps.
• the liquid fluid with negative pressure according to step e) only in the imaginary central area, and preferably also only in the leading edge areas and/or also only in the imaginary trailing edge areas, of the respective gaps is applied.
• the liquid fluid when the method according to the invention is at a standstill, in particular when the pressure media is not being transported, the liquid fluid is usually subjected to a corresponding vacuum according to step e) in order to prevent it from flowing out of the nozzle channels without or without the participation of the To prevent nozzles associated closure bodies.
• An exception to this is when an outflow for cleaning purposes of at least the at least one coating head is desired.
• the liquid fluid which is discharged from the nozzles in step d) and is not applied to the at least one printing medium is collected and disposed of, preferably by means of a collecting device.
• fluid applied to the at least one printing medium is not fed back to the fluid supply channel, so that the risk of contamination, e.g. due to dust-laden air and/or the change in concentration, e.g. due to evaporation of volatile components of the fluid into the atmosphere, is ruled out.
• contamination e.g. due to dust-laden air and/or the change in concentration, e.g. due to evaporation of volatile components of the fluid into the atmosphere.
• a plurality of print media are transported along the transport direction, with at least some of the print media being transported at a distance in the transport direction from at least one of their closest neighbors to be coated, as a result of which gaps arise in the transport direction between these spaced-apart adjacent print media, with step d ) the liquid fluid occurs at least in the area of each inflow opening of the nozzles with a respective overpressure relative to the ambient air pressure, such that the coating head activates continuous columnar fluid jets in a synchronized manner exclusively in the area of the pressure medium, so that the liquid fluid in the form of continuous columnar fluid jets exclusively in the area of the respective print media is discharged from the nozzles.
• the coating head prefferably stationary and for the at least one print medium to be transported uniformly along the transport direction at a speed greater than zero, at least during step d) and preferably also during step e).
• the coating head prefferably be arranged in a stationary manner and for the transport of the at least one print medium to take place uniformly along the transport direction at least during step d), and preferably also during step e), at an adjustable speed greater than zero, with the desired speed being multiple available speeds selected.
• the method can be used to coat a number of ceramic printing media with a glaze or engobe or smaltobe as a liquid fluid, each in the form of a suspension, by applying it to the respective ceramic printing media and then at least partially concentrating it.
• concentration refers to the absorption of the liquid fluid by a layer that is in contact with it, in particular a particle layer, and/or the removal of at least one volatile component of the liquid fluid by evaporation and/or vaporization, i.e. by drying, Understood.
• Narrowing and/or hardening of the coating is advantageous, as this allows a further layer to be applied to the narrowed and/or hardened coating without the materials of the two layers mixing before the firing process and consequently resulting in blurred images when the on the coated layer is a colored image.
• the engobe suspension is a thin clay mineral mass. This can be slip.
• a suspension of “Smaltobe” means a mixture of a glaze suspension and an engobe suspension.
• the object of the present invention is also achieved in particular by a method for producing relief-like decorations on ceramic print media.
• the method according to the invention for producing relief-like decorations on ceramic printing media comprises the steps: f) transporting a plurality of ceramic printing media along a transport direction; g) Delivering drops of a first glazing suspension, which comprises glazing material in the form of particles containing at least one frit, with a large number of nozzles of an inkjet printer on a partial area of the respective print media and concentrating the drops applied on the respective partial area in such a way that at least partially condensed glazing material Forms surveys, whereby a relief-like decoration is formed, with a continuous during the dispensing of the drops unidirectional relative movement occurs between the nozzles of the inkjet printer and the print media; h) Firing the ceramic print media to produce baked relief-like decorations on the print media.
• a first glazing suspension which comprises glazing material in the form of particles containing at least one frit
• a covering glaze or engobe or smaltobe each in the form of a suspension, is applied as a liquid fluid to the entire surface of the relief-like decorations of the respective print media and concentrated.
• a priming glaze or engobe or smaltobe each in the form of a suspension, is applied to the entire surface of the respective ceramic printing media using a method according to the invention for coating the ceramic printing media upset and constrained.
• At least one coating head is provided in which no side wall of the fluid supply channel is made in one piece together with the respective nozzles and the end face of the respective nozzles surrounding the inflow opening is flush with an inner surface of a side wall of the fluid supply channel that is in contact with the fluid is trained.
• a predetermined single-color or multicolored image motif is applied to the surface of the covering glaze layer using an application device, which is preferably an inkjet printer.
• a protective layer comprising a frit, which is or becomes transparent after baking, is applied to the applied image motif.
• the protective layer can be formed from a composition suitable for increasing the mechanical resistance of the image subject to abrasion and/or chemical resistance to acids and alkalis.
• the corresponding materials are known to the person skilled in the art.
• the nozzles of the at least one coating head are made of ceramic, flart metal or surface-treated steel and/or the end face of the respective actuators are made at least in sections of ceramic, flart metal or surface-treated steel.
• the nozzles arranged on the side wall or on a part of the side wall of the coating head and the side wall or the part of the side wall itself are each made of ceramic, flart metal or surface-treated steel, with preferably the nozzles on the side wall or on the Nozzles arranged part of the side wall of the coating head and the side wall or the part of the side wall can be provided together in one piece.
• the method can be used for coating a print medium, in particular a textile web, by using a primer, preferably without solid particles, as the fluid and in step c) one print medium instead of several print media being transported along a transport direction.
• the method can also be used for coating a textile web as a printing medium with a suitable liquid fluid to form a primer layer or an ink-receiving layer on the textile web.
• FIG. 1A shows a specific point in time in method step d) of a particularly preferred embodiment of the method according to the invention, in which a particularly preferred coating head arrangement was provided.
• FIG. 1B shows method step e) of the particularly preferred embodiment of the method according to the invention, in which the particularly preferred coating head arrangement from FIG. 1A was provided.
• FIG. 1B shows method step e) of the particularly preferred embodiment of the method according to the invention, in which the particularly preferred coating head arrangement from FIG. 1A was provided.
• FIG. 1A shows a specific point in time in method step d) of a particularly preferred embodiment of a method according to the invention.
• a plurality of print media 1 are transported along a transport direction, with at least some of the print media 1 being transported in the transport direction at a distance from at least one of their closest neighbors to be coated.
• the transport direction of the print media 1 is that direction which goes into the image plane (and therefore not visible in Figure 1A). This creates gaps in the transport direction between these spaced-apart adjacent print media 1, with the respective gaps in the transport direction being notionally divisible into a central area and a leading and trailing edge area.
• a fluid circuit system for supplying two coating heads 2, 2' with liquid fluid, comprising the two coating heads 2, 2' was provided in the particularly preferred embodiment of the method according to the invention.
• Each of the two coating heads 2, 2' comprises a fluid supply channel 3, 3', several nozzles 4, 4', each with a nozzle channel and an inflow opening 5, 5', which form the connection of the respective nozzle channels to the respective fluid supply channel 3, 3'.
• the respective nozzles 4, 4' are stationarily arranged on a side wall 6, 6' of the respective fluid supply channel 3, 3'.
• the reference numbers for only one nozzle 4, 4' of the nozzles shown have been included in FIGS. 1A and 1B.
• the liquid fluid is shown in dashed lines in the two fluid supply channels 3, 3'.
• Each of the coating heads 2, 2' of a coating head arrangement has a row of nozzles aligned at a 90° angle to the transport direction of the print medium 1, and the coating head arrangement has an effective row length.
• the effective row length corresponds to the total length of the effective range of the coating head arrangement transversely to the transport direction of the print medium 1 and corresponds in the present case to the sum of the two effective ranges of the coating heads 2, 2'.
• the coating heads 2, 2' can be fluidically connected parallel to one another with the supply line 10 and a return line 11 of the fluid circuit, the coating head 2' being fluidically separable from the fluid circuit system and, as shown in Figures 1A and 1B, it was used in the present method both in step d) as well as in step e) separated from the supply line 10 and from the return line 11 of the fluid circuit system.
• the print medium 1 has a width that is less than the effective row length of the coating head arrangement and during step d) is only transported into the effective range of the coating head 2, so that the respective print media 1 only the coating head 2 are to be coated.
• the coating head 2' is fluidically separated from the fluid circuit system to which the respective print media 1 are not exposed, in that both the valve 10a and the Valve 11a are automatically blocked.
• the valve 10a is provided upstream with respect to the coating head 2' in the supply line 10 and the valve 11a is provided downstream with respect to the coating head 2 in the return line 11.
• step d) at least during the time intervals in which the at least one printing medium 1 is to be coated, the liquid fluid is subjected to a respective overpressure relative to the ambient air pressure, at least in the region of each inflow opening 5 of the nozzles 4, such that application of the liquid fluid in Form continuous columnar fluid jets F s on the pressure medium 1 takes place (see Figure 1A).
• the reference numerals in FIG. 1A have only been included for a continuous columnar fluid jet Fs.
• the liquid fluid is also applied before and also after the time intervals in which the respective print media 1 are to be coated, at least in the area of each inflow opening of the nozzles 4, with a respective overpressure relative to the ambient air pressure, such that liquid fluid in the form continuous columnar fluid jets F s is also delivered from the nozzles 4, however, exclusively in predetermined fictitious leading edge regions and also exclusively in predetermined fictitious trailing edge regions of the respective gaps.
• the fluid circuit system was provided with a fluid path that fluidly connects a fluid tank 9a to the coating head 2, the fluid path connecting the coating heads 2, 2' between the supply line 10 and the return line 11, each connected to the fluid tank 9a are coupled, are fluidly connectable, so that, however, due to the blocked valves 10a and 10b liquid fluid is only pumped permanently from the fluid tank 9a via the supply line 10 through the coating head 2 and via the return line 11 back to the fluid tank 9a.
• the fluid supply channels 2, 2' were filled before the valves 10a and 11a were blocked for step d), by filling the fluid tank 9a with liquid fluid in such a way that a free liquid fluid surface 9b was formed in the fluid tank 9a with respect to a gaseous fluid.
• the fluid circuit system forms a fluid circuit that is closed to the outside except for the nozzles 4 of the coating head 2 and through which liquid fluid is permanently pumped with the aid of a centrifugal pump 13 in a flow direction RF (see supply line 10 and fluid supply channel 3).
• step d) the liquid fluid is subjected to excess pressure using a gas excess pressure reservoir 8b of a first means for applying excess pressure to the liquid fluid, during which the excess pressure prevailing in the gas excess pressure reservoir 8b relative to the ambient air pressure is controlled with a compressor 8c of the first means.
• step d) a second fluidic connection 7a between fluid tank 9a and a gas underpressure reservoir 7b of the second means is kept closed by a valve 7d keeping the second fluidic connection 7b closed, while a first fluidic connection 8a between fluid tank 9a and the gas overpressure reservoir 8b of the first means is kept open by a valve 8d keeping the first fluidic connection 8a open.
• the second active fluid connection 7a is shown schematically in broken lines in FIG. 1A in its closed state.
• a transition from step d) to step e) takes place during the transition from the leading edge area of the respective gap to the fictitious central area of the respective gap between the respective pressure medium 1 and its neighbor by the first fluid connection 8a between the fluid supply channel 3 and the gas pressure reservoir 8b of the first medium being closed and the second fluidic connection 7a between fluid supply channel 3 and the gas vacuum reservoir 7b of the second means is opened and during step e) the second fluidic connection 7a is kept open and the first fluidic connection 8a is kept closed.
• step e in which the liquid fluid is subjected to a negative pressure relative to the ambient air pressure at least in the area of each inflow opening 5 of the nozzles 4 during the time intervals in which no liquid fluid is to be discharged from the nozzles 4 , whereby an outflow of liquid fluid from the nozzle channels is prevented even without the participation of the respective closure bodies assigned to the nozzles 4 in step e).
• the liquid fluid forms a meniscus 5b in each of the nozzle channels of the nozzles 4.
• step e) a second fluidic connection 7a between fluid tank 9a and a gas underpressure reservoir 7b of the second means is kept open by a valve 7d keeping the second fluidic connection open, while the first fluidic connection 8a between fluid tank 9a and the gas overpressure reservoir 8b of the first means is kept closed in that a valve 8d keeps the first fluid operative connection 8a blocked.
• the first active fluid connection 8a is shown schematically in broken lines in FIG. 1B in its closed state.
• step e) to step d) takes place during the transition from the imaginary central area of the respective gap to the imaginary trailing edge area of the respective gap between the respective print medium 1 and its neighbor, in that the first fluidic connection 8a between the fluid tank 9a and the overpressure reservoir 8a of the first Is opened means and the second fluid operative connection 7a between the fluid tank 9a and the vacuum reservoir 7a of the second means is closed.
• steps d) and e) and the transitions between steps d) to e) and e) to d) are carried out repeatedly as mentioned above.
• the fluid tank 9a is filled with liquid fluid by coupling an external fluid canister to the fluid line 14 and opening the valve 14c in order to allow liquid fluid to flow into the fluid tank 9a until the fluid tank 9a has been filled with the desired amount of liquid fluid. It is self-explanatory that even when the fluid tank is being filled, the liquid fluid is subjected to a vacuum relative to the ambient air pressure, at least in the area of each inflow opening 5 of the nozzles 4, which means that liquid fluid can flow out of the nozzle channels even without the involvement of the nozzles 4 associated closure bodies in step e) is prevented.

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• Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Mechanical Engineering (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Ink Jet (AREA)

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• 2021
  • 2021-07-15 IT IT102021000018653A patent/IT202100018653A1/it unknown
• 2022
  • 2022-06-20 WO PCT/EP2022/025284 patent/WO2023284996A1/de active Application Filing
  • 2022-06-20 US US18/567,998 patent/US20240239009A1/en active Pending
  • 2022-06-20 EP EP22733855.5A patent/EP4370295A1/de active Pending

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