Printing apparatus and printing method

A printing apparatus includes: a printing plate having a recessed portion formed therein shaped corresponding to a pattern to be formed on a substrate; an inking unit including an inkjet head that performs an inking process of ejecting a liquid into the recessed portion, the liquid having particles as a material of the pattern dispersed therein; a laminating unit that performs a laminating process of laminating the substrate on a surface having the recessed portion formed therein after the inking process; a post-drying unit that performs a drying process on the liquid inside the recessed portion in a state in which the substrate is laminated on the surface having the recessed portion formed therein, thereby to reduce the fluidity of the liquid; and a peeling unit that peels off the substrate from the printing plate after the drying process by the post-drying unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a printing apparatus and a printing method, and more particularly to an inking technique for intaglio plate printing to which an inkjet system is applied.

2. Description of the Related Art

Recent years have seen a use of a technique for forming a micropattern such as metal wiring and electrical wiring patterns for a thin film transistor in a glass substrate, a resin substrate, and other substrates using a printing process. Such a substrate having a micropattern formed by a liquid containing conductive particles such as metal is used for a thin display device such as a liquid crystal display, a portable communication device, and other devices.

Japanese Patent Application Laid-Open No. 2005-081726 (PTL 1) discloses a pattern forming apparatus that forms a color filter for a liquid display and a silver electrode for a plasma display by applying a printing process using a flexible metal flat plate-shaped intaglio plate. The pattern forming apparatus disclosed in PTL 1 fills an intaglio plate with ink (inking) by an inkjet system, evaporates a solvent of the ink filled in the intaglio plate, aligns the intaglio plate with a printing substrate so as to be in close contact with each other, and then transfers the ink onto the printing substrate by pressing the intaglio plate.

Japanese Patent Application Laid-Open No. 2010-201906 (PTL 2) discloses a printing method of filling the substrate with ink to 100% by filling the intaglio plate with ink, removing the ink on a planar portion of the intaglio plate, and evaporating the ink inside a recessed portion thereby to make the ink adhesive and cohesive.

SUMMARY OF THE INVENTION

However, the pattern forming apparatus disclosed in PTL 1 evaporates the solvent of the ink filled in the intaglio plate, but prevents the ink from losing viscosity.

Thus, when the ink is transferred from the intaglio plate to the printing substrate, the ink has viscosity (liquidity), which causes the ink to flow after the intaglio plate is peeled off from the printing substrate, resulting in that it is difficult for the ink to maintain the shape of the intaglio plate.

The printing method disclosed in PTL 2 is configured to apply ink to the entire surface of the intaglio plate and remove unnecessary ink by a blade or the like, resulting in that it is difficult to reduce the consumption of ink. In addition, it is difficult to achieve a balance between preventing scumming (ink remaining on a planar portion) and ensuring reproducibility of the micropattern.

For example, assuming the case where unnecessary ink is removed from the intaglio plate by a blade or the like in order to prevent scumming, if the pressing force against the intaglio plate by the blade or the like is increased, the ink may be removed even from the recessed portion, which causes a problem with reproducibility of the micropattern. Meanwhile, if the pressing force against the intaglio plate is reduced by giving priority to the reproducibility of the micropattern, scumming may occur.

Further, since the intaglio plate is made of silicone rubber, when unnecessary ink is removed from the planar portion of the intaglio plate, the intaglio plate is worn, which causes a problem with durability. In addition, there is still another problem with pattern dependence that occurs when the ink is removed, resulting in that it is difficult to form any pattern.

More specifically, in the case of a long straight line shaped pattern extending in a direction perpendicular to a longitudinal direction of the blade, when the ink is removed from the intaglio plate by a blade or the like, a cutting edge of the blade is slightly entered into the recessed portion of the intaglio plate, which may cause the ink to be removed from the recessed portion. Therefore, it is difficult to form a long straight line shaped pattern extending in a direction perpendicular to a longitudinal direction of the blade with good accuracy, which may restrict the pattern formation.

In view of such circumstances, the present invention has been made, and an object of the present invention is to provide a printing apparatus and a printing method capable of forming a preferable micropattern by a printing process using an intaglio plate.

In order to achieve the above object, a printing apparatus according to the present invention includes: a printing plate having a recessed portion formed therein shaped corresponding to a pattern to be formed on a substrate; an inking unit including an inkjet head that performs an inking process of ejecting a liquid into the recessed portion of the printing plate, the liquid having particles as a material of the pattern dispersed therein; a laminating unit that performs a laminating process of laminating the substrate on a surface having the recessed portion of the printing plate formed therein in a state in which the liquid is placed inside the recessed portion of the printing plate; a drying unit that performs a drying process on the liquid inside the recessed portion in a state in which the substrate is laminated on the surface having the recessed portion of the printing plate formed therein, thereby to reduce fluidity of the liquid; and a peeling unit that peels off the substrate from the printing plate following the drying process by the drying unit.

According to the present invention, a liquid is placed inside a recessed portion of a printing plate by an inking unit, the printing plate is laminated on a substrate, a drying process is performed in a state in which the printing plate is laminated on the substrate to reduce fluidity of the liquid to a degree at which the shape of the liquid inside the recessed portion of the printing plate is maintained, the fluidity of the liquid on the substrate is suppressed after the printing plate is peeled off from the substrate, and thus the shape of the liquid on the substrate corresponding to the shape of the recessed portion of the printing plate is maintained.

Therefore, the present invention can achieve a balance between preventing scumming of the printing plate (residual liquid remaining on the planar portion thereof) and ensuring reproducibility of the micropattern formed on the substrate.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, preferable embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1is an entire configuration view illustrating a schematic configuration of a printing apparatus according to an embodiment of the present invention.FIG. 1illustrates a printing apparatus10which is applied particularly to printed electronics technology. The printing apparatus10uses a printing plate (intaglio plate)12having a fine pattern portion (recessed portion)12A formed therein to transfer (form) a pattern from the printing plate12to a substrate (base material)14serving as a printing substrate.

The printing apparatus10is configured to include: an inking unit20that places ink into (performs an inking process on) the recessed portion12A of the printing plate12; a pre-drying unit22that performs a drying process on the printing plate12following the inking process; a laminating unit24that laminates the substrate14on the printing plate12following the pre-drying process; a post-drying unit26(drying unit) that performs the drying process on the printing plate12and the substrate14following the laminating process; and a peeling unit28that peels off the substrate14from the printing plate12following the drying process by the post-drying unit26.

In addition, although not illustrated, the printing apparatus10illustrates a substrate supply unit that supplies the substrate14to be printed and a substrate discharge unit that discharges the printed substrate14to outside the apparatus.

A so-called inkjet system is applied to the inking unit20illustrated inFIG. 1. More specifically, a liquid (ink)31A is placed (supplied) inside the recessed portion (pattern portion)12A of the printing plate12wound around an outer peripheral surface of the plate cylinder16(relative movement unit) using the inkjet system for ejecting the liquid from an inkjet head30.

The printing plate12is an intaglio plate including the recessed portion12A having the same shape as that of the pattern to be formed on the substrate. Examples of the material forming the printing plate12include resin, metal, glass, and the like.

When a brittle material such as glass is applied to the substrate14, an elastic material is applied to the printing plate12. For example, various kinds of elastomers such as fluorosilicone rubber, butyl rubber, ethylene-propylene rubber, nitrile rubber, neoprene rubber, hypalon rubber, and urethane rubber can be applied.

From the point of view of a good releasing property from the substrate14, the printing plate12may be made of a material having liquid repellency such as silicone rubber made of a polymer such as polydimethylsiloxane (PDMS) and fluororubber. When the printing plate12is made of a material having a good releasing property (material having liquid repellency) from the substrate14, the transferability of the liquid (micropattern) is improved and the liquid is prevented from remaining on the printing plate12following the transfer (following the peeling step), thus enabling continuous printing by omitting a step of cleaning the printing plate12following the peeling step.

Examples of the liquid for use in the present embodiment include a metal liquid (metal ink) prepared by dispersing metal particles in a solvent, a semiconductor liquid (semiconductor ink) prepared by dissolving a polymer semiconductor in a solvent, and the like.

The liquid for use in the present embodiment has a viscosity (1×10−3Pa·s to 20×10−3Pa·s) capable of being ejected from the inkjet head30, and may include a liquid whose solvent is evaporated by a drying process such as heating and air flow blowing, a liquid causing curing reaction by irradiation with actinic rays, and a liquid causing agglutination reaction by reaction with an aggregation treatment liquid.

FIG. 2is a schematic configuration view of the inking unit20. As illustrated in the figure, the inkjet head30is disposed in an upper portion of the printing plate12, and a predetermined distance is maintained between a liquid ejection surface30A of the inkjet head30and a surface12B (a surface in which the recessed portion12A (seeFIG. 1) is formed) of the printing plate12.

The inkjet head30is a full-line type head having a length corresponding to an entire length (entire width of the substrate14) in a direction (hereinafter may be referred to as an “X direction”) parallel to the printing plate12, that is, a direction parallel to a rotation shaft16A of a plate cylinder16. The inkjet head30is placed in a position in which a constant clearance is maintained between the liquid ejection surface (nozzle surface)30A and a surface12B of the printing plate12.

FIG. 3Ais a plan view illustrating an arrangement of nozzles40provided in the inkjet head30. As illustrated in the figure, the liquid ejection surface30A of the inkjet head30has the nozzles (nozzle openings)40formed therein to eject liquid.

The inkjet head30illustrated inFIG. 3Ahas the nozzles40in plural provided at regular intervals in the X direction over a length corresponding to the entire width of the printing plate12.

The inkjet head30illustrated inFIG. 3Ahas two rows of nozzles in the Y direction (moving direction of the printing plate12) perpendicular to the X direction and the plurality of nozzles40are arranged in a staggered manner.

As illustrated inFIG. 3A, the staggered arrangement of the nozzles in two rows allows the nozzles40to be arranged at high density. Note that the nozzles40can be arranged in three or more rows. The arrangement of the nozzles40in three or more rows allows the nozzles40to be arranged at higher density.

Specifically, the nozzle array applicable to the present invention is not limited to a staggered arrangement of two rows, but may have a structure having a single nozzle row in the Y direction or may have a structure having a plurality of nozzles40arranged in matrix.

FIG. 3Bis a plan view illustrating another structure example of the inkjet head. The inkjet head33illustrated inFIG. 3Bhas a structure having a plurality of head modules (head assemblies)33A joined together in the X direction over the length corresponding to the entire width of the printing plate12.

FIG. 3Billustrates a configuration of joining the head modules33A in plural in a row, but the plurality of head modules33A may be configured to be joined together in a staggered manner.

The inkjet head30may be formed by a piezoelectric system for ejecting liquid using flexural deformation, shear deformation, longitudinal vibration, and the like of a piezoelectric element, or may be formed by various methods such as a thermal system using a film boiling phenomenon to eject liquid and an electrostatic system using an electrostatic force.

The inking unit20having such a structure places (fills) a predetermined amount (volume) of liquid inside the recessed portion12A formed in the printing plate12by ejecting liquid while relatively moving the inkjet head30and the printing plate12in the Y direction.

Note that the structure of the inkjet head30(33) is not limited to the structure illustrated inFIGS. 3A and 3B. For example, the inkjet head30(33) may be formed by a serial system in which the inkjet head having a plurality of nozzles arranged at a predetermined arrangement interval in the Y direction is moved in the X direction over the entire length of the substrate14to eject liquid in the X direction, and when one liquid ejection in the X direction ends, the substrate14is moved by a predetermined amount in the Y direction to eject liquid in the X direction over a next region, whereby the series of operations is repeated to place liquid over the entire surface of the substrate14(entire surface of the region on which the liquid is placed).

Referring back toFIG. 1, the pre-drying unit22illustrated in the figure is arranged on a subsequent stage side (downstream side in the moving direction of the printing plate12) of the inking unit20. The pre-drying unit22performs a drying process (pre-drying process) on a liquid31B placed inside the recessed portion12A of the printing plate12to remove part of the solvent.

The drying process by the pre-drying unit22may be either natural drying or forced drying. The term “natural drying” refers to a process of evaporating the solvent of the liquid31B placed inside the recessed portion12A of the printing plate12without performing a forced drying process such as air blowing or heating.

Meanwhile, the term “forced drying” refers to a process of evaporating a solvent component of the liquid31B placed inside the recessed portion12A of the printing plate12by promoting evaporation of the solvent by a forced drying process such as air blowing and heating.

Examples of air blowing include air blowing by air blowing means such as a fan. Examples of heating include heating by an infrared heater and heating by irradiation with high frequency or microwave. Alternatively, warm air (hot air) may be blown by a combination of air blowing and heating.

Note that the drying process by the pre-drying unit22assumes that the liquid31B placed inside the recessed portion12A of the printing plate12is not completely dried, but in a state of fluidity.

The laminating unit24is arranged on a subsequent stage side of the pre-drying unit22. The laminating unit24laminates the surface12B of the printing plate12on a pattern forming surface14A of the substrate14by aligning the printing plate12subjected to the drying process by the pre-drying unit22with the substrate14supplied from an not illustrated substrate supply unit.

The position of the printing plate12can be obtained from a signal outputted from an encoder attached to the rotation shaft of the plate cylinder16. In addition, the position of the substrate14can be obtained from a signal outputted from an encoder (illustrated by a reference numeral144inFIG. 4) attached to a drive system (motor) of a transport unit (not illustrated) for transporting the substrate14.

A position sensor for detecting a starting end position of the printing plate12and a position sensor for detecting a leading end position of the substrate14may be provided. Then, the positions of the printing plate12and the substrate14may be obtained using the signals detected by those position sensors.

A post-drying unit26is arranged on a subsequent stage side of the laminating unit24. The post-drying unit26may perform natural drying or forced drying in the same manner as the pre-drying unit22. From the point of view of reduction in processing time, air blowing, heating, and a combination of these are preferable.

The drying process by the post-drying unit26prevents the liquid inside the recessed portion12A of the printing plate12from being completely dried and further reduces the fluidity of the liquid.

In the case of using aqueous liquid (metal liquid, metal (nano) ink) containing metal particles forming electrical wiring patterns and in the case of using semiconductor liquid (semiconductor ink) prepared by dissolving polymer semiconductors in the solvent, the solvent component (mainly water) is evaporated by blowing dry air or warm (hot) air.

In the case of using a liquid (actinic ray curable ink) cured by irradiation with actinic rays such as ultraviolet rays, an actinic ray emitting means (ultraviolet light source) is provided in the post-drying unit26.

Note that the drying process by the post-drying unit26will be described in detail later.

A peeling unit28is arranged on a subsequent stage side of the post-drying unit26. The peeling unit28peels off the substrate14from the printing plate12following the drying process by the post-drying unit26. Specific examples of the peeling process by the peeling unit28include a peeling process using a peeling claw (not illustrated), a peeling process using an absorption sheet (not illustrated), and other peeling processes.

As another embodiment, the peeling unit28may include a fixing means for fixing the substrate14so as to peel off the substrate14from the printing plate12by moving the printing plate12in a state in which the substrate14is fixed.

Following the peeling process by the peeling unit28, the substrate14is transported on a transport cylinder17. Meanwhile, the printing plate12has a certain releasing property from the liquid, which eliminates the need to be subjected to a cleaning process for each printing, and thus enables continuous printing.

[Description of Control System]

FIG. 4is a block diagram illustrating a schematic configuration of a control system of the printing apparatus10.

As illustrated in the figure, the printing apparatus10includes a system controller100, a communication unit102, a memory104, a transport control unit110, a pattern data processing unit112, an ejection control unit114, a drying control unit116, a laminating control unit118, a peeling control unit120, an operation unit130, a display unit132, a sensor140, a position detection unit144(encoder), and the like.

The system controller100functions as control means for performing overall control on each unit of the printing apparatus10, and functions as calculation means for performing various calculation processes. The system controller100includes a central processing unit (CPU)100A, a read only memory (ROM)100B, and a random access memory (RAM)100C therein.

The system controller100also functions as a memory controller for controlling writing data to the ROM100B, RAM100C, and a memory which is not illustrated, and reading data from those memories.

FIG. 4illustrates an embodiment in which the memories such as the ROM100B and the RAM100C are stored in the system controller100, but the memories such as the ROM100B and the RAM100C may be provided outside the system controller100.

The communication unit102includes a required communication interface to transmit and receive data to and from a host computer103connected to the communication interface.

The memory104functions as a temporary memory for storing various data including pattern data. The data is read from and written to the memory104through the system controller100. The pattern data received from the host computer through the communication unit102is temporarily stored in the memory104.

The transport control unit110controls the operation of a substrate transport unit11and a plate cylinder drive unit13for rotating the plate cylinder16(seeFIG. 1) in the printing apparatus10.

The substrate transport unit11includes a transport mechanism for transporting the substrate14from the substrate supply unit (not illustrated) to the substrate discharge unit (not illustrated), a drive unit for driving the transport mechanism, and a support unit (not illustrated) for supporting the substrate14during transport. In addition, the plate cylinder drive unit13includes a drive source such as a motor of the plate cylinder16and a drive mechanism such as gears.

The pattern data processing unit112generates ejection data (dot data) of the inkjet head30based on the pattern data (data including position information, width information, and other information about the recessed portion12A formed in the printing plate12) transmitted from the host computer103.

In other words, the pattern data processing unit112is a processing unit for performing a process similar to that of an image processing unit (processing unit for generating dot data from raster data) in an inkjet recording device.

The ejection data generated by the pattern data processing unit112is sent to the ejection control unit (head driver)114. The ejection data sent to the ejection control unit114is converted to a drive voltage to be supplied to the inkjet head30and applied to a pressure generating element of the inkjet head30.

More specifically, based on the ejection data generated by the pattern data processing unit112, a liquid ejection rate and a liquid ejection timing of the inkjet head30are controlled. According to the liquid ejection rate and the liquid ejection timing of the inkjet head30, the transport control unit110controls the relative movement speed (start and stop moving the printing plate12) between the inkjet head30and the printing plate12.

As used herein, the term “pressure generating element” refers to a piezoelectric element (piezoelectric actuator) in a piezoelectric system, a heater in a thermal system, and means for applying an ejection pressure to the liquid of the inkjet head30.

The drying control unit116controls the operation of the pre-drying unit22and the post-drying unit26according to a command from the system controller100. More specifically, the drying control unit116controls the drying temperature, the flow rate of dry gas, the injection timing of dry gas, and the like, for the drying process of the pre-drying unit22and the post-drying unit26.

The laminating control unit118controls the operation of the laminating unit24. More specifically, based on position information about the substrate14obtained from the sensor140(position detection sensor for detecting the position of the substrate14) and position information about the printing plate12obtained from the position detection unit (encoder)144, the laminating control unit118transmits a command signal to the transport control unit110through the system controller100.

In response to the command signal, the transport control unit110controls the operation of the substrate transport unit11and controls the operation of the plate cylinder drive unit13for rotating the plate cylinder16.

In addition, the laminating control unit118controls the operation of an adjustment mechanism (not illustrated) for adjusting the distance interval between the printing plate12and the substrate14so as to cause the substrate14and the printing plate12to be in close contact with each other.

The peeling control unit120controls the operation of the peeling unit28according to a command from the system controller100. In an embodiment in which a peeling claw is applied to the peeling unit28, when the printing plate12and the substrate14reach a predetermined peeling position, the peeling control unit120operates the peeling claw to peel off the substrate14from the printing plate12.

The operation unit130includes operation members (operation means) such as operation buttons, a keyboard, a touch panel, and the like. The operation unit130transmits operation information inputted from the operation members to the system controller100. The system controller100performs various processes according to the operation information transmitted from the operation unit130.

The display unit132includes a display device such as an LCD panel. The display unit132causes the display device to display various device settings information, error information, and other information thereon according to a command from the system controller100.

FIG. 4illustrates a sensor140on behalf of various sensors. The sensor140inFIG. 4includes a temperature sensor provided in the pre-drying unit22for detecting a temperature of the printing plate12, a temperature sensor provided in the post-drying unit26for detecting a temperature of the printing plate12or the substrate14, a scum detection sensor for detecting a scam of the printing plate12following the peeling of the substrate14(prior to the inking process), an image sensor for detecting a pattern formed (transferred) in the substrate14, and other sensors.

[Description of Printing Method]

The description will now focus on the printing method (micropattern forming method) using the printing apparatus10.FIGS. 5A and 5Bare an explanatory drawing schematically illustrating the inking step. Note that in the following description, the same or similar components as or to the previously described components are designated by the same reference numerals or characters, and the description thereof is omitted.

The inking step illustrated inFIGS. 5A and 5Bcauses the inking unit20(seeFIG. 1) to eject the liquid31A from the inkjet head30so as to be landed inside the recessed portion12A formed in the printing plate12. The liquid landed inside the recessed portion12A is designated by reference alphanumeric code31B.

As illustrated inFIGS. 5A and 5B, the inking step performs, a plurality of times, a relative movement (relative movement process) between the full-line type inkjet head30and the printing plate12so as to place a predetermined volume of the liquid31B in a predetermined position.

FIGS. 5A and 5Bschematically illustrate an embodiment of the inking step of placing the liquid31B into the recessed portion12A by performing twice the relative movement between the inkjet head30and the printing plate12.

FIG. 5Aschematically illustrates a first round of liquid deposition. In the first round of liquid deposition, the liquid31B is placed in every other position in a predetermined deposition position of the liquid31B.

FIG. 5Bschematically illustrates a second round of liquid deposition. In the second round of liquid deposition, the liquid31B is placed in an intermediate position of the liquid31B placed in the first round of liquid deposition.

As described above, in the second round of relative movement between the inkjet head30and the printing plate12, the liquid31B landed inside the recessed portion12A is coalesced with an adjacent liquid31B to form a coalesced body of liquid31B inside the recessed portion12A (seeFIG. 5C). The interior of the recessed portion12A has liquid repellency (the detail will be described later), which prevents the liquid (coalesced liquid)31B from spreading wet in the entire recessed portion12A, resulting in a gap between the liquid31B and an inner wall of the recessed portion12A.

Note that the device configuration in which the liquid31B is placed in all liquid deposition positions by performing, a plurality of times, the relative movement between the inkjet head30and the printing plate12will be described in detail later.

Examples of liquid droplet deposition method in the inking step may include a system in which the liquid31B is placed in all liquid deposition positions by performing only once the relative movement between the inkjet head30and the printing plate12.

In the embodiment illustrated inFIGS. 5A and 5B, the liquid31B inside the recessed portion12A is arranged in discrete (isolated) droplets. As used herein, the term “discrete (isolated) arrangement” of the liquid31B refers to an arrangement in which when a liquid is landed, the liquid does not contact an adjacent liquid, and in the embodiment illustrated inFIGS. 5A and 5B, the diameter of the liquid31B when landed is less than the arrangement pitch of the liquid31B.

The liquid31B immediately after landed, does not contact the adjacent liquid31B, but when a certain period of time has elapsed since the liquid31B was landed, the liquid31B spreads, resulting in that the adjacent liquid droplets contact with each other to form a coalesced droplet.

Note that the total volume (total volume of the liquid placed inside the recessed portion12A) of the liquid31B (31A) is greater than the total volume of the recessed portion12A. In other words, the liquid31B having a volume greater than the total volume (total capacity) of the recessed portion12A to the extent that the liquid31B does not overflow from the recessed portion12A is placed inside the recessed portion12A (seeFIG. 5C).

The total ejection volume of the liquid31B (31A) may be appropriately determined according to the physical properties (viscosity and the like) of the liquid. The amount of ejection in one ejection is obtained by dividing the total ejection volume by the number of landed positions.

The inking step is followed by a pre-drying step to be performed by the pre-drying unit22.FIG. 5Cis an explanatory drawing schematically illustrating the pre-drying step.

The pre-drying step performs a drying process (pre-drying process) on the liquid31B placed inside the recessed portion12A of the printing plate12to remove part of the solvent component. InFIG. 5C, the arrow lines directed from the pre-drying unit22toward the liquid31B (printing plate12) represents air and heat imparted to the liquid31B.

The liquid31B inside the recessed portion12A prior to the pre-drying process has a viscosity to the extent that the liquid31B can be ejected from the inkjet head, and hence the liquid31B flows inside the recessed portion12A.

In light of this, the pre-drying process removes part of the solvent of the liquid31B inside the recessed portion12A thereby to increase the viscosity of the liquid31B to be higher than the viscosity when landed (ejected) and to have a fluid state to the extent that the viscosity does not inhibit planarization of the liquid31B.

In addition, the volume of the liquid31B inside the recessed portion12A is adjusted to be suitable for leveling in a later described laminating step.

The processing conditions (air volume, air pressure, heating temperature, processing time, etc.) for the pre-drying process are appropriately determined according to the physical properties of the liquid to be used. For example, in the case of using a liquid having a relatively higher viscosity when landed, the processing time is relatively shorter, and the air volume and the air pressure are relatively smaller. In addition, the heating temperature is relatively lower.

Meanwhile, in the case of using a liquid having a relatively lower viscosity when landed, the processing time is relatively longer, and the air volume and the air pressure are relatively larger. In addition, the heating temperature is relatively higher.

The pre-drying step is followed by a laminating step to be performed by the laminating unit24(seeFIG. 1).FIG. 5Dis an explanatory drawing schematically illustrating the laminating step.

As illustrated in the figure, the printing plate12is aligned with the substrate14and the substrate14is laminated on the printing plate12. When the substrate14is laminated on the printing plate12, the substrate14is pressed against the printing plate12, whereby the liquid31B inside the recessed portion12A of the printing plate12is planarized (leveled).

The arrow lines illustrated inFIG. 5Drepresent a pressing force directed from the substrate14toward the printing plate12. Laminating the substrate14on the printing plate12causes the liquid31B inside the recessed portion12A of the printing plate12to flows, resulting in that the liquid31B spreads out inside the recessed portion12A.

In the case of using a film substrate (substrate having bendable flexibility) as illustrated inFIG. 1, the substrate14can be laminated on the printing plate12by winding the substrate14around the plate cylinder16around whose outer peripheral surface the printing plate12is wound.

At this time, the printing plate12can be pressed against the plate cylinder16by winding the substrate14around the plate cylinder16while pulling the substrate14in a direction opposite to the plate cylinder16.

Meanwhile, in the case of using a rigid substrate (substrate using a hard material) such as a glass substrate and a glass epoxy substrate, the printing plate12is made in planar contact with the substrate14by overlapping the substrate14on the planarly supported printing plate12.

The laminating step is followed by a post-drying step to be performed by the post-drying unit26.FIG. 6Ais an explanatory drawing schematically illustrating the post-drying step.

The liquid31B inside the recessed portion12A (following the pre-drying process) in the aforementioned laminating step has a fluidity to the extent that the liquid31B can move inside the recessed portion12A. Thus, if the substrate14is peeled off from the printing plate12as is, the liquid31A will flow, which cannot maintain the shape of the recessed portion12A of the printing plate12.

In light of this, the post-drying process illustrated in the figure performs a drying process on the liquid31B placed inside the recessed portion12A of the printing plate12thereby to further reduce the fluidity of the liquid31B.

Note that the post-drying process assumes that when the substrate14is peeled off from the printing plate12in the peeling step (seeFIG. 6B) without completely drying the liquid31B inside the recessed portion12A, a pattern31C (the liquid31B following the post-drying process, seeFIG. 6B) has a fluidity to the extent that the pattern31C does not remain inside the recessed portion12A.

The liquid31B following the post-drying process has a fluidity to the extent that the liquid31B does not move inside the recessed portion12A, has less fluidity than when the substrate14is laminated on the printing plate12, and is cured to the extent that the liquid31B does not remain inside the recessed portion12A.

Performing the drying process on the liquid31B inside the recessed portion12A in this manner causes the liquid31B in the same shape as that of the recessed portion12A to be formed in the substrate14, and further prevents the liquid31B (pattern31C) from remaining inside the recessed portion12A.

In the state in which the printing plate12is in close contact with the substrate14in the post-drying step, the solvent component of the liquid31B passes through the interface between the printing plate12and the substrate14, and the solvent component of the liquid31B passes through the substrate14, whereby the solvent component of the liquid31B is escaped from inside the recessed portion12A to the outside.

FIG. 6Bis an explanatory drawing schematically illustrating the peeling step to be performed by the peeling unit28. As illustrated in the figure, following the post-drying step, the substrate14is peeled off from the printing plate12, and then the liquid (pattern)31C that has been placed inside the recessed portion12A of the printing plate12, subjected to the pre-drying process, the leveling, and the post-drying process, and then cured is transferred to the substrate14.

The arrow line illustrated inFIG. 6Brepresents a pressure imparted to the substrate14in the peeling step.

The pattern31C transferred to the substrate14has a shape such that the shape of the recessed portion12A of the printing plate12is faithfully reproduced. In addition, the liquid31B (seeFIG. 6A) does not remain inside the recessed portion12A of the printing plate12.

[Detailed Description of Printing Plate]

The printing plate12will now be described in detail. From the point of view of ensuring releasability from liquid31B, the recessed portion12A of the printing plate12has liquid repellency to the liquid to be used. The portion (a) ofFIG. 7is an explanatory drawing illustrating a relationship between the film thickness (micrometer) of the liquid31B inside the recessed portion12A of the printing plate12and the contact angle (degree) inside the recessed portion12A of the printing plate12to the liquid31B to be used. The portion (b) ofFIG. 7is an enlarged portion (a) with the horizontal line representing real numbers.

As used herein, the film thicknesses of the liquid31B were measured following the post-drying process using a Confocal Microscope OPTELICS (registered trademark) series H1200 (product name, manufactured by Laser Tech Co., Ltd.).

The group1(represented by white circles) in the figure represents cases in each of which a good pattern31C (seeFIG. 6B) was formed with no liquid31B remaining inside the recessed portion12A. In other words, when the film thickness of the liquid31B is relatively thin and the contact angle is relatively high, a good pattern having the reproduced shape of the recessed portion12A is formed (transferred).

The good pattern was formed under the conditions where when the film thicknesses of the liquid31B are 0.1 micrometers and 0.26 micrometers, the contact angle inside the recessed portion12A is 70° (degrees); when the film thicknesses of the liquid31B are 0.29 micrometers and 0.41 micrometers, the contact angle inside the recessed portion12A is 75°; and when the film thicknesses of the liquid31B is 0.5 micrometers, 0.64 micrometers, 0.78 micrometers, 1.9 micrometers, and 2.2 micrometers, the contact angle inside the recessed portion12A is 102°.

In other words, under the conditions where when the film thicknesses of the liquid31B placed inside the recessed portion12A of the printing plate12following the post-drying step is equal to or greater than 0.5 micrometers and equal to or less than 3.0 micrometers, the contact angle inside the recessed portion12A of the printing plate12is equal to or greater than 100°, a good pattern31C is formed in the substrate14with no liquid31B remaining inside the recessed portion12A.

Note that a more preferable upper limit of the film thickness is 2.2 micrometers according to the experimental measurement data, but considering that the contact angle is constant (102°) when the film thickness is in the range from 0.5 micrometers to 2.2 micrometers, the contact angle can be assumed to be constant when the film thickness is in the range of 2.2 micrometers plus several micrometers. Therefore, the preferable upper limit of the film thickness is set to 3.0 micrometers.

Likewise, a more preferable lower limit of the film thickness is 0.5 micrometers according to the experimental measurement data. Considering the trend of data from 0.5 micrometers to 0.41 micrometers and considering that it is difficult to accurately adjust the film thickness up to two decimal places, the more preferable lower limit of the film thickness is set to 0.5 micrometers.

Note also that a more preferable minimum value of the contact angle is 102° according to the experimental measurement data, but considering that it is difficult to accurately adjust the contact angle up to two decimal places, and considering measurement errors and the like, the preferable minimum value of the contact angle is set to 100°.

In addition, when the film thickness of the liquid31B is less than 0.5 micrometers, the contact angle inside the recessed portion12A is made equal to or greater than 70°. Under this condition, a good pattern31C with no liquid31B remaining inside the recessed portion12A is formed in the substrate14(seeFIG. 6B).

Note that a preferable lower limit of the film thickness is 0.1 micrometer according to the experimental measurement data, which is not different from data with a film thickness of 0.26 micrometers. In consideration of this trend, the similar data is assumed to be obtained with a film thickness of 0.1 micrometer or less.

In addition, considering the trend of data from 0.5 micrometers to 0.41 micrometers and considering that it is difficult to accurately adjust the film thickness up to two decimal places, the preferable film thickness range is set to 0.5 micrometers or less.

Meanwhile, group2(represented by white triangles) represents cases with remaining liquid, where the pattern31C maintained the width of the recessed portion12A, but did not maintain the depth of the recessed portion12A (insufficient thickness).

In addition, group3(represented by black triangles) represents cases with remaining liquid, where the pattern31C did not maintain the width of the recessed portion12A (insufficient width) and did not maintain the depth of the recessed portion12A (insufficient thickness).

Finally, group4(represented by X) represents cases in each of which the pattern31C was not formed in the substrate14(part of the liquid31B inside the recessed portion12A was moved into substrate14, but the pattern31C was not formed).

The relationship between the film thickness (micrometer) of the liquid31B inside the recessed portion12A of the printing plate12and the contact angle (degree) inside the recessed portion12A of the printing plate12illustrated inFIG. 7was derived using the following liquid (nano silver ink).

Liquid 1A: Solvent-based silver nanoink (ink prepared by adjusting the silver concentration of L-Ag1TeH (model number) for the purpose of film thickness adjustment)

In addition, the printing plate was made of the following materials.

Printing plate 2: Surface modified by irradiating printing plate 1 with vacuum-ultraviolet light (a wavelength of 172 nm)

Note that the relative relationship of the plate hardness of the printing plates 3 to 5 is such that the plate hardness of the printing plate 5 is greater than the plate hardness of the printing plate 3 which is greater than the plate hardness of the printing plate 4.

The substrate was made of the following materials.

Drying was performed under the conditions where both pre-drying and post-drying were performed, the pre-drying was performed for 1 minute to 20 minutes, the post-drying was performed for 5 seconds to 10 minutes, and both pre-drying and post-drying were performed at room temperature.

The data of groups1to4illustrated inFIG. 7was measured under the conditions listed in Tables 1 to 4 respectively. Table 1 lists data of group1. Table 2 lists data of group2. Table 3 lists data of group3. Table 4 lists data of group4.

FIG. 8is an entire configuration view illustrating another device configuration of the printing apparatus according to the present invention. A printing apparatus200illustrated in the figure transports a printing plate212on a flat surface216A of a printing plate transport unit216(relative movement unit), in the course of which an inking unit220, a pre-drying unit222, a laminating unit224, a post-drying unit226, and a peeling unit228perform the respective processes.

InFIG. 8, a substrate214supplied to the printing plate transport unit216is illustrated by solid lines; and the printing plate212used by the inking unit220, the pre-drying unit222, the laminating unit224, the post-drying unit226, and the peeling unit228are illustrated by broken lines.

The embodiment of planarly transporting a printing plate212illustrated inFIG. 8is effective for the substrate214made of a brittle material (rigid materials, or stiff, inflexible materials weak to bending) such as a glass substrate.

Instead of the printing plate transport unit216illustrated inFIG. 8, another embodiment may be used in which each processing unit has its own individual printing plate transport unit and transfer unit for transferring the printing plate212between the processing units.

The processes of the inking unit220, the pre-drying unit222, the laminating unit224, the post-drying unit226, and the peeling unit228illustrated inFIG. 8are the same as the processes of the inking unit20, the pre-drying unit22, the laminating unit24, the post-drying unit26, and the peeling unit28illustrated inFIG. 1, and hence the description thereof is omitted.

Note that inFIG. 8, reference numeral230designates an inkjet head for ejecting a liquid231A. Note also that the arrow lines illustrated inFIG. 8indicate the direction of transporting the printing plate212.

In the present embodiment, the printing plate12(212) is moved with respect to each unit, but as another embodiment, the printing plate12(212) may be fixed and each unit may be moved. Alternatively, as still another embodiment, the printing plate12(212) may be moved by means (such as an XY table) for two-dimensionally moving the printing plate12(212).

[Description of Inkjet Head Liquid Ejection Method]

FIGS. 9A and 9Bare an entire configuration view schematically illustrating a schematic device configuration preferable for interlaced droplet ejection to be described later.FIG. 9Aillustrates the inking step.FIG. 9Billustrates the laminating step and the following steps. Note that most of the components illustrated inFIGS. 9A and 9Bare the same as the components illustrated inFIG. 1. The reference numerals inFIGS. 9A and 9Bstart with “3” followed by the same two digits as those inFIG. 1. More specifically, a printing apparatus300is configured to include: an inking unit320that places ink into (performs an inking process on) a recessed portion312A of a printing plate312; a pre-drying unit322that performs a drying process on the printing plate312following the inking process; a laminating unit324that laminates a substrate314on the printing plate312following the pre-drying process; a post-drying unit326(drying unit) that performs a drying process on the printing plate312and the substrate314following the laminating process; and a peeling unit328that peels off the substrate314from the printing plate312following the drying process by the post-drying unit326. In addition, inFIGS. 9A and 9B, reference alphanumeric code312B designates a surface of the printing plate312, reference alphanumeric code314A designates a pattern forming surface of the substrate314, and reference numeral317designates a transport cylinder, and reference alphanumeric code331B designates liquid.

The printing apparatus300illustrated inFIGS. 9A and 9Bis configured such that a plate cylinder316can be moved in a direction indicated by both arrow lines by a moving mechanism which is not illustrated. Specifically, when the substrate314is laminated on the printing plate312in the laminating step, the plate cylinder316is moved obliquely downward from the position in the inking step.FIG. 9Billustrates a state after the plate cylinder316has been moved in the laminating step.

In the inking step illustrated inFIG. 9A, an inkjet head330and the printing plate312are moved a plurality of times (the plate cylinder316is rotated a plurality of times immediately under the inkjet head330), whereby a droplet is placed in all deposition positions of the liquid331B determined according to the printing data.

While the plate cylinder316is being rotated a plurality of times, a predetermined distance (clearance) between the surface312B of the plate cylinder316and the substrate314is maintained in order to prevent the printing plate312from contacting the substrate314.

The interlace system is applied to droplet ejection (liquid deposition) in the inking step. More specifically, for a first round of droplet ejection from the inkjet head330, the liquid331B is placed in discrete (isolated) droplets on the printing plate312, and for multiple rounds of droplet ejections, the liquid331B is ejected (deposited) into a different position, whereby the droplets are placed in all deposition positions of the liquid331B determined according to the printing data.

When the inking step ends, as illustrated inFIG. 9B, the position of the substrate314is aligned with the position of the printing plate312having the liquid deposited therein and the plate cylinder316is moved obliquely downward.

When the plate cylinder316is moved to the position where the printing plate312is pressed against the substrate314, the liquid331B on the printing plate312is transferred to the substrate314.

FIGS. 10A to 10Dare an explanatory drawing of an interlaced droplet ejection control (method) for the inking unit20(reference numeral220inFIG. 8). Note that inFIGS. 10A to 10D, liquid droplets placed adjacent to each other are in contact with each other, but the liquid deposition position and placement distance may be determined such that the liquid droplets placed adjacent to each other are partially overlapped.

In the interlaced droplet ejection control to be described later, a liquid (dot) is skippingly placed by one relative movement between the inkjet head30(reference numeral230inFIG. 8and reference numeral330inFIGS. 9A and 9B) and the printing plate12, whereby the liquid is placed in all deposition positions by multiple relative movements between the inkjet head and the printing plate12.

Therefore, a landing time difference between the liquid droplets placed in adjacent deposition positions occurs, which suppresses landing position deviation due to landing interference (coalescence), prevents the liquid from leaking from inside the recessed portion12A (reference alphanumeric code312A inFIGS. 9A and 9B) of the printing plate12(reference numeral212inFIG. 8and reference numeral312inFIGS. 9A and 9B), and prevents a space from occurring due to insufficient liquid.

FIGS. 10A to 10Dillustrate cases in which a liquid (reference alphanumeric code31B inFIG. 1and reference alphanumeric code331B inFIGS. 9A and 9B) is placed inside the recessed portion12A of the printing plate12by four relative movements between the inkjet head30and the printing plate12.

FIG. 10Aschematically illustrates a liquid411(reference alphanumeric code31B inFIGS. 5A to 5Dand reference alphanumeric code331B inFIGS. 9A and 9B) placed inside the recessed portion12A by a first round of relative movement (first round of liquid deposition). The liquid411is placed in every other position in a staggered manner in the X direction (width direction of the printing plate12) and in the Y direction (moving direction of the printing plate12).

FIG. 10Bschematically illustrates the liquid411(illustrated by dot hatching) placed by the first round of liquid deposition and a liquid412placed inside the recessed portion12A by a second round of relative movement (second round of liquid deposition).

The second round of liquid deposition causes the liquid412to be placed in an adjacent position (one of the adjacent positions in the X direction) in the X direction on the right hand side of the liquid411placed by the first round of liquid deposition inFIGS. 10A to 10D. Then, fixation of the liquid411placed by the first round of liquid deposition progresses, and hence coalescence occurs between the liquid411placed by the first round of liquid deposition and the liquid412placed by the second round of liquid deposition, but landing position deviation due to landing interference does not occur.

FIG. 10Cillustrates the liquid411(illustrated by dot hatching) placed by the first round of liquid deposition, the liquid412(illustrated by dot hatching) placed by the second round of liquid deposition, and a liquid413placed by a third relative movement (third round of liquid deposition).

The third round of liquid deposition causes the liquid413to be placed between the liquids411placed by the first round of liquid deposition in the Y direction. Then, fixation of the liquid411placed by the first deposition progresses, and hence coalescence occurs between the liquid411placed by the first round of liquid deposition and the liquid413placed by the third round of liquid deposition, but landing position deviation due to landing interference does not occur.

FIG. 10Dillustrates the liquid411(illustrated by dot hatching) placed by the first round of liquid deposition, the liquid412(illustrated by dot hatching) placed by the second round of liquid deposition, the liquid413(illustrated by dot hatching) placed by the third round of liquid deposition, and a liquid414placed by a fourth relative movement (fourth round of liquid deposition).

The fourth round of liquid deposition causes the liquid414is placed between the liquids412placed by the second round of liquid deposition in the Y direction. Then, fixation of the liquid412placed by the second round of liquid deposition progresses, and hence coalescence occurs between the liquid412placed by the second round of liquid deposition and the liquid414placed by the fourth round of liquid deposition, but landing position deviation due to landing interference does not occur.

Note that the interlace system described usingFIGS. 10A to 10Dis just an example, and hence the liquid deposition and the number of relative movements (number of liquid depositions) between the inkjet head30and the printing plate12may be appropriately determined as long as the liquids411to414are skippingly placed by one movement of the inkjet head30.

Any modifications, additions, or deletions may be appropriately made to the above-described printing apparatus and printing method without departing from the spirit and scope of the present invention.

For example, the printing apparatus (printing method) may include a curing unit (hardening step) that performs a curing process on the substrate14(pattern31C) following the peeling process, a detection unit (detection step) that detects the presence or absence of the liquid31B remaining in the printing plate12(recessed portion12A) following the peeling process, and a cleaning unit (cleaning step) that performs a cleaning process on the printing plate12(recessed portion12A) following the detection process if the presence of the liquid31B remaining in the printing plate12(recessed portion12A) is detected.

Alternatively, the presence or absence of the liquid31B remaining in the printing plate12(recessed portion12A) may be determined based on the shape of the pattern31C formed in the substrate14.

[Invention to be Disclosed Herein]

As has become evident from the above detailed description of the embodiments of the invention, the present specification includes disclosure of various technical ideas including the invention as described in at least the following.

(First aspect) A printing apparatus including: a printing plate having a recessed portion formed therein shaped corresponding to a pattern to be formed on a substrate; an inking unit including an inkjet head that performs an inking process of ejecting a liquid into the recessed portion of the printing plate, the liquid having particles as a material of the pattern dispersed therein; a laminating unit that performs a laminating process of laminating the substrate on a surface having the recessed portion of the printing plate formed therein in a state in which the liquid is placed inside the recessed portion of the printing plate; a drying unit that performs a drying process on the liquid inside the recessed portion in a state in which the substrate is laminated on the surface having the recessed portion of the printing plate formed therein, thereby to reduce fluidity of the liquid; and a peeling unit that peels off the substrate from the printing plate following the drying process by the drying unit.

According to the first aspect, the liquid is placed inside the recessed portion of the printing plate by the inking unit, the substrate is laminated on the printing plate, the drying process is performed in the state in which the substrate is laminated on the printing plate, and the fluidity of the liquid inside the recessed portion of the printing plate is reduced to the extent that the shape of the liquid is maintained. Thus, after the substrate is peeled off from the printing plate, the fluidity of the liquid on the substrate is suppressed, and the shape of the liquid on the substrate corresponding to the shape of the recessed portion of the printing plate is maintained.

Therefore, it is possible to achieve a balance between preventing scumming (ink remaining on a planar portion) of the printing plate and ensuring reproducibility of the micropattern formed on the substrate.

(Second aspect) The printing apparatus according to the first aspect includes a pre-drying unit that performs a drying process on the liquid placed inside the recessed portion of the printing plate following the process by the inking unit prior to the process by the laminating unit, wherein the drying process reduces the volume of the liquid inside the recessed portion and reduces the fluidity of the liquid inside the recessed portion.

According to the second aspect, the liquid placed inside the recessed portion of the printing plate is dried before the substrate is laminated on the printing plate, and thereby the liquid volume is adjusted to the extent that the liquid does not overflow from inside the recessed portion due to liquid flow when the substrate is laminated on the printing plate and the liquid viscosity is also adjusted.

In addition, the pre-drying unit performs the pre-drying process, and thereby the time required for the subsequent drying step can also be shortened.

(Third aspect) In the printing apparatus according to the second aspect, the drying unit further reduces the fluidity of the liquid following the drying process by the pre-drying unit.

According to the third aspect, the liquid inside the recessed portion of the printing plate is dried in two steps, and thereby a preferable drying state of the liquid can be obtained at the laminating process by the laminating unit and at the peeling process by the peeling unit.

(Fourth aspect) In the printing apparatus according to any one of the first to third aspects, when the thickness of the liquid placed inside the recessed portion of the printing plate following the drying process is equal to or greater than 0.5 micrometers and equal to or less than 3.0 micrometers, the contact angle to the liquid to be used inside the recessed portion of the printing plate is equal to or greater than 100 degrees.

According to the fourth aspect, a good peeling between the recessed portion of the printing plate and the liquid is achieved, and a pattern faithfully reproducing the shape of the recessed portion of the printing plate is formed on the substrate.

(Fifth aspect) In the printing apparatus according to any one of the first to third aspects, when the thickness of the liquid placed inside the recessed portion of the printing plate following the drying process is less than 0.5 micrometers, the contact angle to the liquid to be used inside the recessed portion of the printing plate is equal to or greater than 70 degrees.

According to the fifth aspect, when the thickness of the liquid inside the recessed portion of the printing plate is relatively thin, the liquid repellency to the liquid to be used inside the recessed portion of the printing plate may be reduced.

(Sixth aspect) In the printing apparatus according to any one of the first to fifth aspects, the printing plate is made of silicone rubber or fluororubber.

According to the sixth aspect, the printing plate is made of a material having liquid repellency, and thereby the condition according to the fourth aspect or the fifth aspect can be satisfied.

(Seventh aspect) The printing apparatus according to any one of the first to sixth aspects includes: a relative movement unit that performs relative movement between the printing plate and the inkjet head; and an ejection control unit that controls liquid ejection of the inkjet head, wherein the ejection control unit discretely places the liquid into the recessed portion by one relative movement between the printing plate and the inkjet head by the relative movement unit, and places the liquid in all predetermined liquid deposition positions inside the recessed portion by multiple relative movements between the printing plate and the inkjet head by the relative movement unit.

According to the seventh aspect, the interlace system is applied to the inkjet head ejection control, and thereby liquid position deviation is prevented so as not to move the liquid placed in an adjacent position of the liquid inside the recessed portion.

(Eighth aspect) In the printing apparatus according to the seventh aspect, the inkjet head is a full-line type head having a length corresponding to an entire length in a direction perpendicular to the moving direction of the relative movement unit of the printing plate in a direction perpendicular to the moving direction of the relative movement unit.

In the eighth aspect, a preferable embodiment may be such that the liquid is discretely placed inside the recessed portion by ejecting the liquid for every several nozzles in a direction perpendicular to the moving direction of the relative movement unit.

(Ninth aspect) A printing method including: an inking step of performing an inking process of ejecting a liquid into a recessed portion of a printing plate using an inkjet head, the liquid having particles as a material of a pattern dispersed therein, the pattern to be formed on a substrate, the printing plate having the recessed portion shaped corresponding to the pattern formed on the substrate; a laminating step of performing a laminating process of laminating the substrate on a surface having the recessed portion of the printing plate formed therein in a state in which the liquid is placed inside the recessed portion of the printing plate following the inking step; a drying step of performing a drying process on the liquid inside the recessed portion following the laminating step in a state in which the substrate is laminated on the surface having the recessed portion of the printing plate formed therein, thereby to reduce fluidity of the liquid; and a peeling step of peeling off the substrate from the printing plate following the drying process by the drying step.

(Tenth aspect) It is included that a pre-drying step of performing a drying process on the liquid placed inside the recessed portion of the printing plate following the inking step and prior to the laminating step, wherein the drying process reduces the volume of the liquid inside the recessed portion and reduces the fluidity of the liquid inside the recessed portion.

(Eleventh aspect) In the printing method according to the tenth aspect, the drying step further reduces the fluidity of the liquid following the drying process by the pre-drying step.

(Twelfth aspect) In the printing method according to any one of the ninth to eleventh aspects, when the thickness of the liquid placed inside the recessed portion of the printing plate following the drying process is equal to or greater than 0.5 micrometers and equal to or less than 3.0 micrometers, the contact angle to the liquid to be used inside the recessed portion of the printing plate is equal to or greater than 100 degrees.

(Thirteenth aspect) In the printing method according to any one of the ninth to eleventh aspects, when the thickness of the liquid placed inside the recessed portion of the printing plate following the drying process is less than 0.5 micrometers, the contact angle to the liquid to be used inside the recessed portion of the printing plate is equal to or greater than 70 degrees.

(Fourteenth aspect) In the printing method according to any one of the ninth to thirteenth aspects, the printing plate is made of silicone rubber or fluororubber.

(Fifteenth aspect) The printing method according to any one of the ninth to fourteenth aspects, including a relative movement step of performing relative movement between the printing plate and the inkjet head, wherein the inking step discretely places the liquid into the recessed portion by one relative movement between the printing plate and the inkjet head, and places the liquid in all predetermined liquid deposition positions inside the recessed portion by multiple relative movements between the printing plate and the inkjet head.

In the above aspect, a preferable embodiment may use a full-line type inkjet head having a length corresponding to the entire length in a direction perpendicular to the moving direction of the relative movement unit of the printing plate in a direction perpendicular to the moving direction of the relative movement unit.