JP2012135746A - Droplet discharge device and method for cleaning droplet discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet discharge device capable of cleaning a droplet discharge head more efficiently, and to provide a cleaning method thereof.SOLUTION: The droplet discharge device 100 is composed to supply a cleaning liquid 2 fed from a cleaning liquid reservoir to the droplet discharge head 110 through a first opening 216 and a nozzle 118 covered with the first opening 216 while relatively moving a cleaning head 210 with respect to the droplet discharge head 110 by a moving means 290 with the cleaning head 210 in contact with the droplet discharge head 110, and to suction the cleaning liquid 2 in the droplet discharge head 110 through a second opening 214 and the nozzle 118 covered with the second opening 214.

Description

  The present invention relates to a droplet discharge device and a cleaning method for the droplet discharge device.

For example, as a method of applying a liquid material for wiring (conductor pattern), a liquid material for a color filter, or a liquid material for printing on a substrate, the liquid material is dropped from a droplet discharge head of a droplet discharge device. An ink jet method for discharging in a shape is widely known (see, for example, Patent Document 1).
A liquid discharge head provided in the droplet discharge device includes a nozzle plate in which nozzles are formed, a cavity that is in communication with the nozzle and is filled with a liquid material, and a piezoelectric element that changes the pressure in the cavity. Then, the liquid material is ejected as droplets from the nozzle by increasing the pressure in the cavity by the piezoelectric element.

  Since the liquid material discharged from the droplet discharge head generally has a high viscosity and a high solid content, the solid content tends to remain on the nozzle and the discharge surface of the droplet discharge head. Therefore, for example, when the liquid material is continuously discharged from the droplet discharge head, the components contained in the liquid material adhere to the nozzle or discharge surface of the droplet discharge head, and the liquid material is discharged from the droplet discharge head. It becomes unstable.

In order to solve such a problem, conventionally, for example, a droplet discharge head is ejected from the substrate while the droplet discharge head is withdrawn from the substrate. Agglomerates, deposits, etc. present in the ejection head are removed, and contamination and clogging due to liquid materials are eliminated. However, such a method involves a process time and consumption of liquid material, and this method alone cannot sufficiently remove aggregates and deposits. Further, when the liquid droplets are discharged again, there is a problem that the discharge amount of the liquid droplets becomes unstable in a relatively short period of time or the nozzles are clogged again.
As a method for cleaning a droplet discharge head, a method is also known in which cleaning is performed by replacing all liquid materials in the droplet discharge apparatus with a cleaning liquid. However, in such a method, there is a problem that the liquid material in the droplet discharge device is wasted due to the replacement with the cleaning liquid, and in-cross occurs.

JP 2007-84387 A

  An object of the present invention is to provide a droplet discharge apparatus and a cleaning method thereof that can more efficiently clean a droplet discharge head.

Such an object is achieved by the present invention described below.
The droplet discharge device of the present invention includes a storage tank for storing a liquid material,
A droplet discharge head comprising a plurality of nozzles for discharging the liquid material sent from the storage tank;
A cleaning liquid storage tank for storing a cleaning liquid used for cleaning the droplet discharge head;
A cleaning head provided so as to be relatively close to and away from the droplet discharge head;
Moving means for relatively moving the cleaning head and the droplet discharge head while bringing the cleaning head into contact with the droplet discharge head;
The cleaning head is in contact with the droplet discharge head, the first opening covering a part of the plurality of nozzles, and the nozzle not covered by the first opening And a second opening that covers all or some of the nozzles,
While the cleaning head is in contact with the droplet discharge head, the moving head relatively moves the cleaning head and the droplet discharge head while the first opening opens. The cleaning liquid fed from the cleaning liquid storage tank is supplied into the droplet discharge head through the nozzle covered by the opening, and the second opening covers the second opening. The cleaning liquid in the droplet discharge head is sucked through a nozzle.
As a result, a droplet discharge device that can more efficiently clean the droplet discharge head is obtained.

In the droplet discharge device of the present invention, the droplet is discharged from the first opening through the nozzle covered by the first opening in a state where the cleaning head is in contact with the droplet discharge head. A first state in which the cleaning liquid is supplied into the discharge head and the cleaning liquid in the droplet discharge head is sucked from the second opening through the nozzle covered by the second opening; The cleaning liquid is supplied from the second opening to the droplet discharge head through the nozzle covered by the second opening, and the nozzle covered by the first opening from the first opening. It is preferable that the second state of sucking the cleaning liquid in the droplet discharge head is alternately performed via the liquid crystal.
Thereby, a load can be applied to the dirt from both directions in small increments, and the probability of removing (peeling) the dirt can be particularly increased.

In the droplet discharge device of the present invention, the cleaning head includes an outer tube and an inner tube provided inside the outer tube, and includes one end of a flow path formed inside the inner tube and the outer tube. One end of a flow path formed between the tube and the inner tube preferably constitutes the first opening, and the other constitutes the second opening.
This further simplifies the configuration of the cleaning head.
In the droplet discharge device according to the aspect of the invention, it is preferable that the first opening is located on the front side in the relative movement direction of the cleaning head with the droplet discharge head with respect to the second opening.
This further simplifies the configuration of the cleaning head.

In the droplet discharge device of the present invention, in a state where the cleaning head is in contact with the droplet discharge head, the number of the nozzles covered by the first opening is X, and the second opening When the number of covered nozzles is Y, X / Y is preferably 0.8 or more and 1.2 or less.
Thereby, it is possible to balance the supply amount of the cleaning liquid into the droplet discharge head and the suction amount of the cleaning liquid from the droplet discharge head.

In the droplet discharge device of the present invention, the liquid droplet ejection apparatus includes a filter that removes the liquid material contained in the cleaning liquid sucked from the second opening, and the cleaning liquid from which the liquid material has been removed by the filter is supplied from the cleaning head. It is preferable to send it out into the droplet discharge head.
Thereby, since a washing | cleaning liquid can be used repeatedly, a washing | cleaning liquid can be used effectively. In addition, the cleaning ability of the cleaning liquid can be maintained in a high state.

In the liquid droplet ejection apparatus of the present invention, the liquid droplet ejection apparatus has a valve that prevents the liquid material from being fed from the storage tank to the liquid droplet ejection head in a state where the cleaning liquid is supplied into the liquid droplet ejection head. It is preferable.
Thereby, the liquid material removed at the time of washing | cleaning of a droplet discharge head can be kept to the minimum.

In the droplet discharge device according to the aspect of the invention, it is preferable that the cleaning liquid is a liquid that can dissolve or disperse a solid content included in the liquid material and is compatible with a main solvent included in the liquid material. .
Thereby, even if the solid content of the ink is precipitated, the solid content can be taken into the cleaning liquid by re-dissolution or re-dispersion and washed away.

In the droplet discharge device of the present invention, it is preferable that the cleaning liquid contains the main solvent of the liquid material as a main component.
As a result, the cleaning liquid is particularly excellent in replaceability with ink, and can be quickly mixed and replaced with the remaining ink.
In the droplet discharge device of the present invention, it is preferable that the liquid material is obtained by dispersing metal particles in a dispersion medium.
Thereby, it becomes a liquid material suitable for forming a conductor pattern.

A cleaning method for a droplet discharge device of the present invention includes a storage tank for storing a liquid material,
A droplet discharge head comprising a plurality of nozzles for discharging the liquid material sent from the storage tank;
A cleaning liquid storage tank for storing a cleaning liquid used for cleaning the droplet discharge head;
A cleaning head provided so as to be relatively close to and away from the droplet discharge head;
Moving means for relatively moving the cleaning head and the droplet discharge head while bringing the cleaning head into contact with the droplet discharge head;
The cleaning head is in contact with the droplet discharge head, the first opening covering a part of the plurality of nozzles, and the nozzle not covered by the first opening And a second opening that covers all or some of the nozzles,
While the cleaning head is in contact with the droplet discharge head, the moving head relatively moves the cleaning head and the droplet discharge head while the first opening opens. The cleaning liquid fed from the cleaning liquid storage tank is supplied into the droplet discharge head through the nozzle covered by the opening, and the second opening covers the second opening. The cleaning liquid in the droplet discharge head is sucked through a nozzle.
Thereby, the droplet discharge head can be cleaned more efficiently.

It is a perspective view which shows an example of suitable embodiment of a droplet discharge apparatus (inkjet apparatus). It is the schematic diagram which showed an example of the whole structure of a droplet discharge apparatus. FIG. 2 is a schematic diagram for explaining a schematic configuration of a droplet discharge head (inkjet head) included in the droplet discharge device of FIG. 1. FIG. 2 is a schematic diagram for explaining a schematic configuration of a droplet discharge head (inkjet head) included in the droplet discharge device of FIG. 1. FIG. 3 is a cross-sectional view of the cleaning head shown in FIG. 2. It is a figure for demonstrating the washing | cleaning method of the droplet discharge apparatus of this invention. It is the schematic diagram which showed another example of the whole structure of the droplet discharge apparatus. It is the schematic diagram which showed another example of the whole structure of the droplet discharge apparatus.

Hereinafter, preferred embodiments of the present invention will be described in detail.
<< Droplet Discharge Device and Cleaning Method for Droplet Discharge Device >>
First, a preferred embodiment of the droplet discharge device of the present invention will be described.
FIG. 1 is a perspective view showing an example of a preferred embodiment of a droplet discharge device (inkjet device), FIG. 2 is a schematic view showing an example of the overall configuration of the droplet discharge device, and FIGS. FIG. 5 is a schematic diagram for explaining a schematic configuration of a droplet discharge head (inkjet head) provided in the droplet discharge device of FIG. 1, FIG. 5 is a sectional view of the cleaning head shown in FIG. 2, and FIG. It is a figure for demonstrating the washing | cleaning method of a droplet discharge apparatus.
The droplet discharge device (inkjet device) 100 discharges, for example, a conductive pattern forming ink (liquid material; hereinafter simply referred to as “ink”) 1 onto a substrate 11 made of, for example, a ceramic molded body. An apparatus used to form a predetermined conductor pattern.

As shown in FIGS. 1 and 2, the droplet discharge device 100 includes a droplet discharge head (inkjet head; hereinafter simply referred to as “head”) 110, a base 130, a table 140, and an ink storage tank 150. Table positioning means 170, head positioning means 180, and control device 190 are provided.
The base 130 is a table that supports each component of the droplet discharge device 100 such as the table 140, the table positioning unit 170, and the head positioning unit 180.

The table 140 is installed on the base 130 via the table positioning means 170. The table 140 is used to place a substrate (acceptor) 11 on which droplets are landed.
The table positioning unit 170 includes a first moving unit 171 and a motor 172. The table positioning means 170 determines the position of the table 140 on the base 130, and thereby determines the position of the substrate 11 on the base 130.

The first moving means 171 has two rails provided substantially parallel to the Y direction and a support base that moves on the rails. The support base of the first moving means 171 supports the table 140 via the motor 172. Then, as the support base moves on the rail, the table 140 on which the substrate 11 is placed is moved and positioned in the Y direction.
The motor 172 supports the table 140 and swings and positions the table 140 in the θz direction.
The head positioning unit 180 includes a second moving unit 181, a linear motor 182, and motors 183, 184 and 185. The head positioning unit 180 determines the position of the head 110.

  The second moving means 181 is provided with two support pillars standing from the base 130, a support base provided between the support pillars, the rail support having two rails, and the rails. And a support member (not shown) for supporting the head 110. Then, as the support member moves along the rail, the head 110 is moved and positioned in the X direction.

The linear motor 182 is provided in the vicinity of the support member, and can move and position the head 110 in the Z direction.
Motors 183, 184, and 185 swing and position the head 110 in the α, β, and γ directions, respectively.
By the table positioning means 170 and the head positioning means 180 as described above, the ink jet apparatus 100 can accurately control the relative position and posture of the ink ejection surface 115P of the head 110 and the substrate 11 on the table 140. It has become.

  As shown in FIG. 3, the head 110 ejects the ink 1 from the nozzle 118 by an ink jet method (droplet ejection method). In the present embodiment, the head 110 uses a piezo method in which ink is ejected using a piezo element 113 as a piezoelectric element. The piezo method has the advantage that the composition of the material is not affected because heat is not applied to the ink 1.

The head 110 has a head body 111, a diaphragm 112, and a piezo element 113.
The head main body 111 has a main body 114 and a nozzle plate 115 on the lower end surface thereof. Then, the main body 114 is sandwiched between the plate-like nozzle plate 115 and the vibration plate 112 to form a reservoir 116 as a space and a plurality of ink chambers 117 branched from the reservoir 116.

Ink 1 is supplied to the reservoir 116 from an ink storage tank 150 described later. Further, the reservoir 116 forms a flow path for supplying the ink 1 to each ink chamber 117.
The nozzle plate 115 is attached to the lower end surface of the main body 114 and constitutes an ink ejection surface 115P. In the nozzle plate 115, a plurality of nozzles 118 that discharge ink 1 are opened corresponding to the ink chambers 117. An ink flow path is formed from each ink chamber 117 toward the corresponding nozzle (ejection unit) 118.

The diaphragm 112 is attached to the upper end surface of the head body 111 and constitutes the wall surface of each ink chamber 117. The diaphragm 112 can vibrate according to the vibration of the piezo element 113.
The piezo element 113 is provided corresponding to each ink chamber 117 on the opposite side of the vibration plate 112 from the head body 111. The piezoelectric element 113 is obtained by sandwiching a piezoelectric material such as quartz with a pair of electrodes. The pair of electrodes is connected to the drive circuit 191.

  When an electric signal is input from the drive circuit 191 to the piezo element 113, the piezo element 113 is expanded or contracted. When the piezo element 113 contracts and deforms, the pressure in the ink chamber 117 decreases, and the ink 1 flows from the reservoir 116 into the ink chamber 117. Further, when the piezo element 113 expands and deforms, the pressure in the ink chamber 117 increases and the ink 1 is ejected from the nozzle 118. Note that the amount of deformation of the piezo element 113 can be controlled by changing the applied voltage. Further, the deformation speed of the piezo element 113 can be controlled by changing the frequency of the applied voltage. That is, by controlling the voltage applied to the piezo element 113, the ejection conditions of the ink 1 can be controlled.

  As shown in FIG. 4, a plurality of nozzles 118 are formed in the head 110 so as to be arranged in series corresponding to the respective ink chambers 117. Among the plurality of nozzles 118, at least one nozzle 118 at each end portion at both ends in the arrangement direction of the nozzles 118 is a non-ejection nozzle (dummy nozzle) 118a that does not eject ink 1. For example, in the general head 110, about 200 nozzles 118 are formed in series, but in this case, about 20 nozzles 118 from both ends, that is, about 40 nozzles 118 are not provided. The discharge nozzle 118a is preferable.

Generally, the ink supply flow rate to the nozzles 118 located at both ends of the head 110 is affected by the shape of the ink path in the head 110. As a result, variations occur in the ejection speed and ejection amount of the ink 1 ejected from the nozzles 118 located at both ends of the head 110. Variations in the ejection speed and ejection amount of the ink 1 can be corrected to some extent by various controls. However, the variations cannot be corrected in a scene where high accuracy is required (for example, conductor pattern formation). Therefore, by providing the non-ejection nozzles 118a at both ends, the ejection speed and ejection amount of the ink 1 from each nozzle 118 can be easily made substantially equal.
The control device 190 controls each part of the inkjet device 100. For example, the discharge condition of the ink 1 is controlled by adjusting the waveform of the applied voltage generated by the drive circuit 191, and the discharge of the ink 1 onto the substrate 11 is controlled by controlling the table positioning unit 170 and the head positioning unit 180. Control the position.

The ink storage tank 150 stores the ink 1.
As shown in FIG. 2, the ink storage tank 150 is connected to the head 110 (reservoir 116) via an ink conveyance path 151.
The ink transport path 151 is provided with a self-sealing valve 153 for preventing the backflow of the ink 1 between the ink storage tank 150 side and the head 110. Further, an open / close valve 152 for opening and closing the ink transport path 151 is separately provided between the ink storage tank 150 and the self-sealing valve 153.
The ink 1 stored in the ink storage tank 150 is sent to the ink transporting path 151 as needed during droplet discharge or the like, and is supplied to the reservoir 116 via the open / close valve 152 and the self-sealing valve 153. .

As shown in FIG. 2, the droplet discharge device 100 includes a cleaning mechanism 200 for cleaning the head 110.
The cleaning mechanism 200 includes a cleaning head 210, a sending unit that sends the cleaning liquid (cleaning ink) 2 from the cleaning head 210, a suction unit that sucks the cleaning liquid 2 from the cleaning head 210, and a moving unit 290 that moves the cleaning head 210. have. The delivery means includes a cleaning liquid storage tank 240 that stores the cleaning liquid 2, a cleaning liquid transport path 202 that supplies the cleaning liquid 2 from the cleaning liquid storage tank 240 to the inside of the cleaning head 210, and a pressure pump provided in the middle of the cleaning liquid transport path 202. 250. The suction means includes a recovery tank 230 that recovers the cleaning liquid 2 supplied into the head 110, a suction medium transport path 201 that transports the cleaning liquid 2 from the cleaning head 210 to the recovery tank 230, and a suction medium transport path 201. And a suction pump 220 provided in the middle of the above.

  As shown in FIG. 5, the cleaning head 210 has a double tube structure having an outer tube 211 and an inner tube 212 provided inside the outer tube 211. A flow path 213 is formed inside the inner tube 212, and the flow path 213 is connected to the suction medium transport path 201. Further, one end of the flow path 213 (one end on the side facing the head 110) constitutes a suction port (second opening) 214 for sucking the cleaning liquid 2. A flow path 215 is formed between the outer pipe 211 and the inner pipe 212, and the flow path 215 is connected to the cleaning liquid transport path 202. In addition, one end of the flow path 215 (one end on the side facing the head 110) constitutes a delivery port (first opening) 216 that delivers the cleaning liquid 2.

Thus, the structure of the cleaning head 210 becomes simpler by making the cleaning head 110 into a double tube structure.
Such a cleaning head 210 is arranged to face the ink ejection surface 115P of the head 110. The cleaning head 210 is configured such that the delivery port 216 and the suction port 214 are open on the surface facing the ink ejection surface 115P and cover the nozzle 118 in a state of being in contact with the head 110.

  In addition, the cleaning head 210 is provided so as to be relatively close to and away from the ink discharge surface 115P. When the cleaning head 210 is in contact with the ink discharge surface 115P, the outer tube 211 and the inner tube 212 are provided. Respectively define an airtight space together with the ink ejection surface 115P. The cleaning head 210 only needs to be in contact with or separated from the ink ejection surface 115P. Therefore, either the configuration in which only the cleaning head 210 moves, the configuration in which only the head 110 moves, or the configuration in which both move. There may be. In the following description, a case where only the cleaning head 210 moves will be described.

  The contact portion of the cleaning head 210 with respect to the ink discharge surface 115P, that is, the upper end portions of the outer tube 211 and the inner tube 212 are made of a highly adhesive material, and the airtightness of the flow paths 213 and 215 is ensured. . Examples of the material having high adhesion include various elastomers and various rubbers. The shapes of the outer tube 211 and the inner tube 212 are not limited as long as the cleaning liquid 2 can flow.

  The moving unit 290 has a function of moving the cleaning head 210 in the arrangement direction of the nozzles 118 with respect to the head 110 while keeping the state in contact with the head 110. The configuration of the moving unit 290 is not particularly limited as long as the above function can be achieved. For example, a rail that guides the movement of the cleaning head 210, and a motor that moves the cleaning head 210 along the rail; It can be set as the structure which has. The driving of the motor can be controlled by the control device 190.

The pressurizing pump 250 supplies the cleaning liquid 2 stored in the cleaning liquid storage tank 240 to the cleaning head 210 via the cleaning liquid conveyance path 202 while pressurizing the cleaning liquid 2. As such a pressure pump 250, for example, a pressure pump such as a diaphragm type or a piston type is used.
On the other hand, the suction pump 220 forcibly sucks the medium from the suction port 214 of the cleaning head 210 via the suction medium transport path 201 and sends the liquid to the recovery tank 230. Examples of the medium include a liquid such as ink 1 and cleaning liquid 2, or a mixture containing two or more of these. As such a suction pump 220, for example, a diaphragm pump, a piston pump, or the like is used.
The on-off valve 152, the suction pump 220, and the pressurization pump 250 are electrically connected to the control device 190 described above. The control device 190 opens and closes the on-off valve 152, and the suction pump 220 is suctioned and pressurized. The start and end of pressurization of the pump 250, or the operation conditions such as the suction amount and the pressurization amount can be controlled.

Next, the operation of the cleaning mechanism 200 will be described.
FIG. 6 is a view (longitudinal sectional view) for explaining the cleaning method of the droplet discharge device of the present invention. In the following description, the upper side in FIG. 6 is referred to as “upper” and the lower side is referred to as “lower”.
The droplet discharge device 100 normally performs an operation of discharging the ink 1 from the nozzle 118 of the head 110. As this operation is repeated, solid content (dirt) contained in the ink 1 adheres to the nozzle 118. The operation of the cleaning mechanism 200 is performed before or after the start of the normal operation, between normal operations, or the like, and is performed to remove the solid content attached to the head 110.
Specifically, first, the head 110 is lowered to bring the ink ejection surface 115P into contact with the upper surface of the cleaning head 210 as shown in FIG. In this state, the flow paths 213 and 215 are hermetically sealed, respectively. In this state, the nozzle 118 located at one end of the plurality of nozzles 118 is covered with the delivery port 216 or the suction port 214.

  Next, after the on-off valve 152 is closed, the cleaning liquid 2 is sent out from the delivery port 216 by the pressurizing pump 250, and the cleaning solution 2 sent out from the delivery port 216 is passed through the nozzle 118 covered by the delivery port 216. The ink is supplied to the inside of 110 (each ink chamber 117 and the reservoir 116). At the same time, the cleaning liquid 2 supplied into the head 110 is sucked through the nozzle 118 covered by the suction port 214 by sucking the inside of the flow path 213 by the suction pump 220. The sucked cleaning liquid 2 is collected in the collection tank 230.

  Further, while supplying and sucking the cleaning liquid into the head 110 as described above, the moving head 290 moves the cleaning head 210 in the arrangement direction of the nozzles 118 with respect to the head 110. As a result, each nozzle 118 is covered in turn with the delivery port 216 and the suction port 214, and when the nozzle 118 is covered with the delivery port 216, the cleaning liquid 2 is supplied into the head 110 via the nozzle 118 and is supplied to the suction port 214. When it is covered, the cleaning liquid 2 in the head 110 is sucked through the nozzle 118.

As described above, while the cleaning head 210 is moved relative to the head 110, the cleaning liquid 2 is supplied into the head 110 through the predetermined nozzle 118, and the supplied cleaning liquid 2 is sucked through the other nozzles 118. As a result, the cleaning liquid 2 flows (forced convection) inside the head 110, thereby removing dirt inside the head 110.
Here, the feeding speed of the cleaning liquid 2 by the pressure pump 250 is not particularly limited, but is preferably 1 mL / min or more and 200 mL / min or less, and more preferably 5 mL / min or more and 100 mL / min or less. Thereby, it can wash | clean more effectively.
The nozzles 118 that are not covered by the cleaning head 210 are open to the atmosphere. However, as described above, since the liquid feeding speed and the suction speed of the cleaning liquid 2 are sufficiently high, the nozzles 118 that are open to the air are used. Even if exists, the inside of the head 110 can be cleaned efficiently.

  Further, at the predetermined time, the number of nozzles 118 covered by the delivery port 216 and the number of nozzles 118 covered by the suction port 214 are not particularly limited, but are preferably substantially equal to each other. Specifically, when the number of nozzles 118 covered by the delivery port 216 is X and the number of nozzles 118 covered by the suction port 214 is Y, X / Y is about 0.8 or more and 1.2 or less. Is preferred. Thereby, the supply of the cleaning liquid 2 to the inside of the head 110 and the suction of the cleaning liquid 2 inside the head 110 can be performed in a balanced manner.

  Further, the time during which the predetermined nozzle 118 is covered by the delivery port 216 (the time during which the cleaning head 210 is covered by the region located in front of the suction port 214 and the rear side from the suction port 214) The time covered by the region is not particularly limited, but is preferably about 1 second or more and 10 seconds or less. The same applies to the time during which the predetermined nozzle 118 is covered by the suction port 214. Accordingly, the inside of each nozzle 118 can be sufficiently cleaned, and the time required for cleaning can be relatively shortened. Moreover, the usage-amount of the washing | cleaning liquid 2 can also be suppressed.

  According to such a method, since the ink 1 is not used as in the prior art, the waste of the ink 1 can be eliminated. Further, since the flow path of the ink 1 and the flow path of the cleaning liquid 2 are different, dirt inside the head 110 can be effectively removed. Further, the cleaning liquid 2 supplied from the plurality of nozzles 118 mixes in the reservoir 116 and collides therewith, thereby generating a turbulent flow, thereby more effectively removing dirt inside the head 110. Can do.

  Further, after almost all the nozzles 118 (nozzles 118 other than the nozzles 118 located at both ends) function as supply ports for supplying the cleaning liquid 2 into the head 110, the discharge ports for discharging the cleaning liquid 2 in the head 110. Therefore, the flow of the cleaning liquid 2 toward the inside of the head 110 and the flow of the cleaning liquid 2 toward the outside of the head 110 can be alternately generated in almost all the nozzles 118. Therefore, a load can be applied to the dirt in the nozzle 118 from both directions, and the probability of removing (peeling) the dirt can be particularly increased.

  Further, by using the double pipe structure as described above, the cleaning liquid 2 is supplied into the head 110 from the nozzle 118 located on the front side and the nozzle 118 located on the rear side in the moving direction of the cleaning head 210. In addition, since the cleaning liquid 2 can be sucked from the nozzles 118 located between the nozzles 118 supplied with the cleaning liquid 2, the flow of the cleaning liquid 2 flowing in the head 110 can be made more complicated. Therefore, it is easy to generate turbulent flow in the head 110, and the probability of removing (peeling) dirt can be particularly increased.

  In addition, by setting the nozzles 118 located at both ends in the arrangement direction of the nozzles 118 among the plurality of nozzles 118 as non-ejection nozzles 118a, the following effects can be obtained. That is, according to the cleaning method as described above, the nozzles 118 located at both ends in the arrangement direction of the nozzles 118 function as supply ports for supplying the cleaning liquid 2 into the head 110 and the cleaning liquid 2 in the head 110. In some cases, only one of the functions as a discharge outlet can be exhibited. Therefore, the cleaning efficiency of the nozzles 118 located at both ends in the arrangement direction of the nozzles 118 may be lower than the cleaning efficiency of the nozzles 118 located at the other central part.

Therefore, the nozzles 118 that are located at both ends of the nozzle 118 in the arrangement direction and have a possibility of lowering the cleaning efficiency are non-ejection nozzles 118a that do not eject ink 1, and the other inks 1 that are high in cleaning effect are the inks 1 only. The nozzles 118 used for discharging the ink 1 can be effectively cleaned by discharging the ink.
Further, as described above, since the on-off valve 152 is closed during cleaning, only the ink 1 that is removed during cleaning remains in the head 110. Therefore, the amount of ink 1 removed by cleaning can be kept to a minimum.

  As a cleaning method, for example, first, the ink 1 remaining in the head 110 is sucked through the nozzle 118 covered by the suction port 214 by sucking the inside of the flow path 213 by the suction pump 220. The cleaning liquid 2 may be supplied into the head 110. Further, after supplying the cleaning liquid 2 into the head 110, the process of sucking the cleaning liquid in the head 110 and emptying the head 110 may be performed a plurality of times. As a result, the action of removing dirt can be particularly enhanced.

The preferred embodiment of the droplet discharge device of the present invention has been described above, but the present invention is not limited to this. For example, a droplet discharge device as shown in FIGS. 7 and 8 may be used.
FIG. 7 is a schematic view showing another example of the overall configuration of the droplet discharge device of the present invention.
In the present embodiment, differences from the above-described embodiment will be described, and description of similar configurations will be omitted.

  The droplet discharge device shown in FIG. 7 is provided between the suction pump 220 and the recovery tank 230 of the suction medium transport path 201, and a branching section 203 (flow path selection section) that branches the suction medium transport path 201 into two. And a branching section 204 (flow path selecting section) that is provided between the pressurizing pump 250 and the cleaning liquid storage tank 240 in the cleaning liquid transfer path 202 and branches the cleaning liquid transfer path 202 into two, a branching section 203 and a branching section. 204 is provided with a communication path 205 that communicates with 204.

  The branching unit 203 can freely take a first state in which the medium flowing through the suction medium conveyance path 201 is sent to the recovery tank 230 and a second state in which the medium is sent to the communication path 205. Further, the branching unit 204 sends the cleaning liquid 2 stored in the cleaning liquid storage tank 240 to the cleaning head 210 and the medium sent from the communication path 205 to the cleaning head 210. The second state is selected.

When the first state is selected in each of the branching unit 203 and the branching unit 204, the operation of the cleaning mechanism 200 is the same as the operation described above.
On the other hand, when the second state is selected in each of the branching unit 203 and the branching unit 204, consumption of the cleaning liquid 2 is stopped, and instead the cleaning liquid 2 sucked from the cleaning head 210 is returned to the cleaning head 210 again. The liquid can be sent. As a result, the cleaning liquid 2 is constituted by the cleaning liquid conveyance path 202, the flow path 215, the head 110, the flow path 213, the suction medium conveyance path 201, and the communication path 205 by operating the pressurization pump 250 and the suction pump 220. It will circulate through the circular path | route made. In this way, it is possible to further promote removal of dirt while suppressing consumption of the cleaning liquid 2.

  The branch unit 203 and the branch unit 204 are configured to be electrically connected to the control device 190 and to control the operation thereof. Thereby, each operation of the branching unit 203 and the branching unit 204 can be controlled in cooperation with the suction operation of the pressurizing pump 250 and the suction pump 220, so that the branching unit 203 and the branching unit 204 are operated at an optimal timing. As a result, the consumption of the cleaning liquid 2 can be minimized, and the action of removing dirt can be enhanced to the maximum.

  When the cleaning liquid 2 is circulated in this way, the cleaning liquid 2 containing the ink 1 may be circulated. However, the medium immediately after the start of suction with a high content of the ink 1 is sent to the recovery tank 230 and the ink 1 It is preferable to start the circulation at the timing when the content ratio of the water content decreases. Thereby, the dirt adhering to the inside of the head 110 can be exposed to a cleaner flow of the cleaning liquid 2 without consuming the cleaning liquid 2 wastefully, and the action of removing the dirt can be particularly enhanced.

  Further, a filter 260 is provided between the cleaning head 210 and the suction pump 220 in the suction medium conveyance path 201 (upstream side of the suction pump 220). The filter 260 can filter the medium flowing in the suction medium conveyance path 201 and filter out contained dirt (solid content). Thereby, it is possible to circulate the clean cleaning liquid 2 that does not contain dirt in the annular path, and to prevent the dirt from reattaching.

Examples of the filter 260 include a fabric filter made of nonwoven fabric or woven fabric, a thread wound filter, a membrane filter, a sponge filter, a metal filter, a ceramic filter, and the like.
Here, at this time, the flow of the cleaning liquid 2 may be reversed by reversing the rotation direction of the pressurization pump 250 or the suction pump 220 for a predetermined time. As a result, a load in the opposite direction is also applied to the dirt adhering to the inside of the head 110, and the probability of removing (peeling) the dirt can be increased.

Further, forward rotation and reverse rotation in the rotation direction of the pressure pump 250 and the suction pump 220 may be alternately repeated in a short time. That is, while supplying the cleaning liquid 2 from the delivery port 216 to the inside of the head 110 through the nozzle 118, the first state in which the cleaning liquid 2 in the head 110 is sucked from the suction port 214 through the nozzle 118, and the suction port The second state in which the cleaning liquid 2 is supplied from 214 to the inside of the head 110 via the nozzle 118 and the cleaning liquid 2 is sucked from the outlet 216 via the nozzle 118 may be alternately performed. As a result, a load can be applied in small increments from both directions to the dirt, and the probability of removing (peeling) the dirt due to a synergistic effect with the load from both directions applied by the movement of the cleaning head 210 as described above. It can be further increased.
At this time, the period for changing the rotation direction is preferably about 0.1 seconds to 10 seconds, and more preferably about 0.3 seconds to 5 seconds.

FIG. 8 is a schematic view showing another example of the overall configuration of the droplet discharge device of the present invention.
In the present embodiment, differences from the above-described embodiment will be described, and description of similar configurations will be omitted.
In the droplet discharge device shown in FIG. 8, the cleaning head 210 has two tubular bodies 241 and 242. These tubular bodies 241 and 242 are arranged side by side in the moving direction of the cleaning head 210, and the tubular body 241 is located on the front side in the moving direction and the tubular body 242 is located on the rear side. A flow path 215 is formed inside the tube body 241, and the opening of the tube body 241 constitutes the delivery port 216. Similarly, a flow path 213 is formed inside the tube body 242, and the opening of the tube body 242 constitutes the suction port 214. Thereby, the configuration of the cleaning head 210 is simplified.
Further, according to such a cleaning head 210, since the suction port 214 is on the rear side in the moving direction of the cleaning head 210, the cleaning liquid 2 in the head 110 can be sucked more reliably, and after cleaning, It is possible to effectively prevent the cleaning liquid 2 from remaining on the surface.

Next, the ink 1 and the cleaning liquid 2 that can be suitably applied to the droplet discharge device 100 described above will be described.
<Ink 1>
As the ink 1, for example, a dispersion liquid in which silver particles (metal particles) are dispersed in an aqueous dispersion medium (dispersion medium) can be suitably used. By setting it as such a structure, it becomes a liquid material suitable for forming a conductor pattern.

[Aqueous dispersion medium]
In the present specification, the “aqueous dispersion medium” refers to one composed of water and / or a liquid excellent in compatibility with water (for example, a liquid having a solubility in 100 g of water at 25 ° C. of 30 g or more). As described above, the aqueous dispersion medium is composed of water and / or a liquid having excellent compatibility with water, but is preferably composed mainly of water. It is preferably 70 wt% or more, more preferably 90 wt% or more. Thereby, the effect mentioned above is exhibited more notably.

Specific examples of the aqueous dispersion medium include, for example, water, methanol, ethanol, butanol, propanol, isopropanol and other alcohol solvents, 1,4-dioxane, tetrahydrofuran (THF) and other ether solvents, pyridine, pyrazine, pyrrole and the like. Aromatic heterocyclic compound solvents, amide solvents such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), nitrile solvents such as acetonitrile, and aldehyde solvents such as acetaldehyde. Of these, one or a combination of two or more can be used.
Further, the content of the aqueous dispersion medium in the ink 1 is preferably 20 wt% or more and 80 wt% or less, and more preferably 25 wt% or more and 70 wt% or less. Thereby, while making the viscosity of the ink 1 suitable, the change of the viscosity by volatilization of a dispersion medium can be made small.

[Silver particles]
Next, silver particles (metal particles) will be described.
Silver particles are the main component of the conductor pattern to be formed, and are components that impart conductivity to the conductor pattern. Such silver particles are dispersed in the ink 1.
The average particle size of the silver particles is preferably 1 nm or more and 100 nm or less, and more preferably 10 nm or more and 40 nm or less. Thereby, the ejection stability of the ink 1 can be further increased, and a fine conductor pattern can be easily formed. In the present specification, the “average particle size” means a volume-based average particle size unless otherwise specified.

Further, the content of silver particles (silver particles in which the dispersant is not adsorbed on the surface) contained in the ink 1 is preferably 0.5 wt% or more and 60 wt% or less, and is 10 wt% or more and 45 wt% or less. Is more preferable. Thereby, disconnection of a conductor pattern can be prevented more effectively, and a more reliable conductor pattern can be formed.
Further, the silver particles are preferably dispersed in an aqueous dispersion medium as silver colloid particles having a dispersant attached to the surface thereof. Thereby, the dispersibility of the silver particles in the aqueous dispersion medium is particularly excellent, and the ejection stability of the ink 1 is particularly improved.

  Although it does not specifically limit as a dispersing agent, it has 3 or more of COOH groups and OH groups, and the number of COOH groups is the same as that of OH groups, or contains hydroxy acid or its salt more than it. Is preferred. These dispersants adsorb on the surface of silver particles to form colloidal particles, and the colloidal liquid is stabilized by uniformly dispersing silver colloidal particles in an aqueous solution by the electric repulsive force of COOH groups present in the dispersant. Has the function of

As described above, since the silver colloid particles are stably present in the ink 1, a fine conductor pattern can be more easily formed. Further, silver particles are uniformly distributed in the pattern formed by the ink 1, and cracks, disconnections, and the like are less likely to occur. Examples of such a dispersing agent include citric acid, malic acid, trisodium citrate, tripotassium citrate, trilithium citrate, triammonium citrate, disodium malate, tannic acid, gallotannic acid, and pentaploid tannin. Of these, one or a combination of two or more can be used.
The content of the silver colloid particles in the ink 1 is preferably 1 wt% or more and 60 wt% or less, and more preferably 5 wt% or more and 50 wt% or less.
Further, the heat loss to 500 ° C. in the thermogravimetric analysis of the silver colloid particles is preferably 1 wt% or more and 25 wt% or less.

[Organic binder]
The ink 1 may contain an organic binder. The organic binder prevents aggregation of silver particles in the conductor pattern precursor formed using the ink 1. The organic binder has a function of improving the adhesion of the ink 1 to the substrate 11.

  Although it does not specifically limit as an organic binder, For example, polyethyleneglycol # 200 (weight average molecular weight 200), polyethyleneglycol # 300 (weight average molecular weight 300), polyethyleneglycol # 400 (average molecular weight 400), polyethyleneglycol # 600 ( Weight average molecular weight 600), polyethylene glycol # 1000 (weight average molecular weight 1000), polyethylene glycol # 1500 (weight average molecular weight 1500), polyethylene glycol # 1540 (weight average molecular weight 1540), polyethylene glycol # 2000 (weight average molecular weight 2000), etc. Polyethylene glycol, polyvinyl alcohol # 200 (weight average molecular weight: 200), polyvinyl alcohol # 300 (weight average molecular weight: 300), polyvinyl alcohol # 400 (average molecular weight: 400), polyvinyl alcohol # 600 (weight average molecular weight: 600), polyvinyl alcohol # 1000 (weight average molecular weight: 1000), polyvinyl alcohol # 1500 (weight average molecular weight: 1500), polyvinyl alcohol # Polyglycerin compounds having a polyglycerin skeleton such as polyvinyl alcohol such as 1540 (weight average molecular weight: 1540), polyvinyl alcohol # 2000 (weight average molecular weight: 2000), polyglycerin, polyglycerin ester, etc. Alternatively, two or more kinds can be used in combination. Examples of polyglycerol esters include polyglycerol monostearate, tristearate, tetrastearate, monooleate, pentaoleate, monolaurate, monocaprylate, polycinnolate, sesquistearate, decaoleate, and sesquioleate. Etc.

(Drying inhibitor)
Further, the ink 1 may contain a drying inhibitor. The drying inhibitor prevents unintended volatilization of the aqueous dispersion medium in the ink 1. As a result, the aqueous dispersion medium can be prevented from volatilizing in the vicinity of the nozzle 118 of the ink jet apparatus 100, and the increase in viscosity and drying of the ink 1 can be suppressed. Examples of such a drying inhibitor include compounds represented by the following formula (I), alkanolamines, sugar alcohols, and the like, and one or more of them can be used in combination.

（ただし、Ｒ、Ｒ’は、それぞれ、Ｈまたはアルキル基である。）

(However, R and R ′ are each H or an alkyl group.)

[Surface tension modifier]
The ink 1 may contain a surface tension adjusting agent. The surface tension adjusting agent has a function of adjusting the contact angle between the ink 1 and the substrate 11 to a predetermined angle. As the surface tension adjusting agent, various surfactants can be used, and one or a combination of two or more types can be used. The contact angle between the ink 1 and the substrate 11 can be set within a predetermined range with a small addition amount. It is preferable that an acetylene glycol type compound is included from a viewpoint which can be adjusted to.

  Examples of acetylene glycol compounds include Surfynol 104 series (104E, 104H, 104PG-50, 104PA, etc.), Surfynol 400 series (420, 465, 485, etc.), Olphine series (EXP4036, EXP4001, E1010, etc.). ("Surfinol" and "Orphine" are trade names of Nissin Chemical Industry Co., Ltd.) and the like, and one or more of these can be used in combination.

[Other ingredients]
In addition, the structural component of the ink 1 is not limited to the said component, You may contain components other than the above. Examples of such components include thiourea.
The viscosity of the ink 1 is not particularly limited, but is preferably 1.0 mPa · s or more and 15.0 mPa · s or less, and more preferably 4.0 mPa · s or more and 11.0 mPa · s or less. Thereby, the ejection stability of the droplets can be improved, and the unintentional wetting and spreading of the ink 1 supplied to the substrate 11 can be prevented more reliably.
The example of the ink 1 has been described above.

<Cleaning liquid>
The cleaning liquid (cleaning ink) applied to the present invention is for cleaning the head 110 used for forming the conductor pattern. Particularly, the head 110 is preferably stained and clogged with the ink 1 as described above. It will be solved.
The cleaning liquid 2 is a liquid that can dissolve or disperse the solid content contained in the ink 1 and is compatible with the main solvent contained in the ink 1. Thereby, the inside of the head 110 can be cleaned more efficiently.
The cleaning liquid 2 is not particularly limited, but it is preferable to use a liquid containing ceramic particles and a dispersion medium for dispersing the ceramic particles.

  These ceramic particles have relatively high hardness and function as an abrasive for the flow path of the ink 1. As a result, even when metal particles are deposited in the vicinity of the nozzle 118 of the head 110, the metal particles on which the ceramic particles are deposited are quickly scraped off, and accumulation of the metal particles in the vicinity of the nozzle 118 outlet of the head 110 is prevented. The For this reason, when the flow path of the ink 1 is cleaned using the cleaning liquid 2, the flying curve of the ink 1 and the unstable discharge amount of the droplet are prevented, and the droplet discharge stability is excellent. . When the flow path of the ink 1 is cleaned using the cleaning liquid 2, a fine pattern can be accurately drawn with the ink 1, and the formed conductor pattern has high reliability in which defects such as disconnection and short circuit are prevented. It will be a thing.

[Ceramic particles]
As described above, the cleaning liquid 2 contains ceramic particles.
The ceramic particles are dispersed in an aqueous dispersion medium to be described later.
The ceramic material that can be used as the ceramic particles is not particularly limited, and examples thereof include aluminum oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, lanthanum oxide, zinc oxide, gallium oxide, indium oxide, titanium oxide, and oxide. Metal oxides such as germanium, tin oxide, titanium oxide and zirconium oxide, glass materials such as borosilicate glass, silicate and silicon dioxide, carbides such as silicon carbide, nitrides such as silicon nitride, halides such as fluorite , Antimony oxide, bismuth oxide and the like, or a mixture thereof, and the like can be used, and one or more of them can be used in combination.
Moreover, it is preferable that a ceramic particle contains a metal oxide among the above-mentioned. Such a compound is chemically stable and stably dispersed in the cleaning liquid. In addition, since the hardness is relatively high, dirt on the discharge port is preferably removed, and as a result, the discharge stability of the conductive pattern forming ink droplets can be made particularly excellent.

  In particular, when the ceramic particles contain aluminum oxide or titanium oxide as the metal oxide, the following effects can be obtained. These compounds have high hardness and have relatively high detergency. In addition, since these compounds have a relatively high melting point, even when the cleaning liquid 2 remains in the flow path of the ink 1, the conductor pattern precursor is sintered in the conductor pattern formed by the ink 1. When it sets, it does not melt and exists as particles. As a result, when the silver particles of the conductor pattern are melted, these ceramic particles are pushed out by the surface tension of the liquid silver, and the ceramic particles are excluded from the formed conductor pattern. As a result, the formed conductor pattern can exhibit the intended performance more reliably and has high reliability. In particular, aluminum oxide and titanium oxide are generally used as a constituent material of a ceramic molded body to be a substrate, and have little influence on a ceramic substrate formed from the ceramic molded body.

  Moreover, among the above-mentioned ceramic particles, it is preferable to include a glass material, and it is more preferable to include silicon dioxide or silicate. The glass material has a function of adsorbing dirt adhering to the ink flow path, and can adsorb the dirt once scraped off to suitably clean the ink 1 flow path. Even when the cleaning liquid 2 remains in the flow path of the ink 1, in the conductor pattern formed by the ink 1, such a compound is melted at least partially during the sintering, so that the conductor This can contribute to improvement in the adhesion between the pattern and the substrate, and can further increase the reliability of the conductor pattern. In particular, silicon dioxide and silicate are generally used as a constituent material of a ceramic molded body serving as a substrate. When the ceramic molded body contains silicon dioxide or silicate, ceramics formed from the ceramic molded body At the same time, the influence on the substrate is reduced, and at the same time, the adhesion between the conductor pattern and the ceramic substrate is further improved, and the reliability of the conductor pattern is further improved.

The average particle diameter of the ceramic particles is preferably 10 nm or more and 300 nm or less, and more preferably 20 nm or more and 2000 nm or less. Thereby, the metal particles adhering to the ink flow path can be removed. That is, the cleaning effect of the ceramic particles can be made particularly excellent. As a result, a fine conductor pattern precursor can be easily and accurately formed using the cleaned droplet discharge device.
In the present specification, the “average particle size” means a volume-based average particle size unless otherwise specified.

  Further, the content of ceramic particles (ceramic colloid particles when ceramic particles are present as a colloid) in the cleaning liquid 2 is preferably 1 wt% or more and 30 wt% or less, and preferably 3 wt% or more and 25 wt% or less. Is more preferable. Thereby, it is possible to prevent the metal particles from adhering to the flow path of the ink 1 and to prevent the ceramic particles from remaining in the flow path of the ink after cleaning.

The ceramic particles are preferably dispersed in an aqueous dispersion medium as ceramic colloidal particles having a dispersant attached to the surface thereof. As a result, the dispersibility of the ceramic colloid particles in the aqueous dispersion medium is particularly excellent, and the cleaning performance of the ceramic particles is suitably exhibited, and the ceramic particles hardly remain in the ink flow path.
Moreover, the heating loss to 500 ° C. in the thermogravimetric analysis of the ceramic colloidal particles is preferably 1 wt% or more and 25 wt% or less. Thereby, the dispersion stability stability of the ceramic colloid particles can be made particularly excellent, and the cleaning effect by the ceramic particles can be made more remarkable.

[Dispersant]
The cleaning liquid 2 preferably contains a dispersant.
The dispersant adheres to the free silver particles to form silver colloidal particles when the ceramic particles scrape off the silver particles adhering to the ink flow path. For this reason, once dispersed silver particles can be prevented from adhering again to the ink flow path, and the cleaning effect of the cleaning liquid can be enhanced.
Moreover, a dispersing agent adheres to a ceramic particle and each forms a ceramic colloid particle. Since such ceramic colloidal particles are excellent in dispersion stability, the cleaning performance is suitably exhibited, and the ceramic colloid particles hardly remain in the ink flow path after cleaning.

Although it does not specifically limit as a dispersing agent, it has 3 or more of COOH groups and OH groups, and the number of COOH groups is the same as that of OH groups, or contains hydroxy acid or its salt more than it. Is preferred. These dispersants adsorb on the surface of silver particles and ceramic particles to form colloidal particles, and silver colloid particles and ceramic colloid particles are uniformly dispersed in an aqueous solution by the electric repulsive force of COOH groups present in the dispersant. Disperses and stabilizes the colloidal liquid. As a result, the cleaning effect of the ceramic particles is sufficiently exhibited, and dirt such as silver once released is hardly reattached to the ink flow path. On the other hand, if the number of COOH groups and OH groups in the dispersant is less than 3 or the number of COOH groups is less than the number of OH groups, the dispersibility of the silver colloid particles and ceramic colloid particles is reduced. You may not get enough.
Examples of such a dispersing agent include citric acid, malic acid, trisodium citrate, tripotassium citrate, trilithium citrate, triammonium citrate, disodium malate, tannic acid, gallotannic acid, and pentaploid tannin. Of these, one or a combination of two or more can be used.

  Further, the dispersant may contain mercapto acid or a salt thereof having two or more COOH groups and SH groups. In these dispersants, mercapto groups are adsorbed on the surfaces of silver particles and ceramic particles to form colloidal particles, and the colloidal particles are uniformly dispersed in an aqueous solution by the electric repulsive force of COOH groups present in the dispersant. Has the function of stabilizing the colloidal liquid. Thereby, the same effect as the hydroxy acid or the salt thereof as described above can be obtained. On the other hand, when the number of COOH groups and SH groups in the dispersant is less than 2, that is, only one, the dispersibility of the silver colloid particles and ceramic colloid particles may not be sufficiently obtained.

  Examples of such dispersants include mercaptoacetic acid, mercaptopropionic acid, thiodipropionic acid, mercaptosuccinic acid, thioacetic acid, sodium mercaptoacetate, sodium mercaptopropionate, sodium thiodipropionate, disodium mercaptosuccinate, Examples include potassium mercaptoacetate, potassium mercaptopropionate, potassium thiodipropionate, dipotassium mercaptosuccinate, and the like, and one or more of these can be used in combination.

  The dispersant contained in the cleaning liquid 2 preferably includes at least a part of the components constituting the dispersant contained in the ink 1, and more preferably has the same composition as the dispersant contained in the ink 1. preferable. Since the deposited deposit is considered to be attached to the original dispersant of the ink 1, the deposit in the same cleaning liquid as the dispersant contained in the ink 1 is further added to the deposit released by the ceramic particles. As a result of adhering, adhering substances that have been liberated easily can be dispersed as colloidal particles in the cleaning liquid. For this reason, the cleaning liquid is more excellent in cleaning properties. Further, after cleaning, the cleaning liquid 2 in the flow path of the ink 1 and the ink 1 can be quickly replaced.

  The content of the dispersant in the cleaning liquid 2 is not particularly limited, but is preferably 0.1 wt% or more and 20 wt% or less, and more preferably 0.3 wt% or more and 10 wt% or less. Thereby, the dispersion effect of the ceramic particles and silver particles as described above can be remarkably exhibited, and there are too many dispersants, so that the dispersant remains after cleaning, and it takes time to replace the cleaning liquid 2 with the ink 1. This can be prevented.

[Aqueous dispersion medium]
Next, the aqueous dispersion medium will be described.
In the present invention, the “aqueous dispersion medium” refers to a liquid composed of water and / or a liquid having excellent compatibility with water (for example, a liquid having a solubility in 100 g of water at 25 ° C. of 30 g or more). As described above, the aqueous dispersion medium is composed of water and / or a liquid having excellent compatibility with water, but is preferably composed mainly of water. It is preferably 70 wt% or more, more preferably 90 wt% or more.
Further, the aqueous dispersion medium contained in the cleaning liquid 2 preferably has substantially the same composition as the aqueous dispersion medium constituting the ink 1. As a result, the replaceability with the ink 1 is particularly excellent, and the remaining ink 1 can be quickly mixed and replaced.

Specific examples of the aqueous dispersion medium include, for example, water, methanol, ethanol, butanol, propanol, isopropanol, ethylene glycol, an alcohol solvent such as propanediol, an ether solvent such as 1,4-dioxane, tetrahydrofuran (THF), Aromatic heterocyclic compound solvents such as pyridine, pyrazine and pyrrole, amide solvents such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), nitrile solvents such as acetonitrile, acetaldehyde and the like Examples of the solvent include aldehyde solvents, and one or more of these can be used in combination.
In addition, the content of the aqueous dispersion medium in the cleaning liquid 2 is preferably 95 to 65 wt%, and more preferably 85 to 75 wt%. Thereby, the viscosity of the cleaning liquid 2 can be made suitable, and the characteristics as the cleaning liquid can be made higher.

[Drying inhibitor]
Moreover, it is preferable that the washing | cleaning liquid 2 contains a drying inhibitor. The drying inhibitor has a function of preventing the ink flow path from being dried after washing. Thereby, when the ink 1 is refilled after the cleaning, mixing of bubbles can be prevented, and the ink 1 can be easily refilled.

  Examples of such a drying inhibitor include compounds represented by the following formula (II), sugar alcohols, alkanolamines, and the like, and one or more of them can be used in combination. These compounds have a function of preventing volatilization of the aqueous dispersion medium as described above, and also have a large number of polar groups such as hydroxyl groups and carbonyl groups. Disperses stably in. For this reason, when the ink 1 contains a metal oxide as ceramic particles and contains the above compound, the dispersion stability of the ceramic particles in the cleaning liquid 2 is particularly excellent, and the cleaning properties of the cleaning liquid 2 are particularly excellent. It will be a thing.

（ただし、Ｒ、Ｒ’は、それぞれ、Ｈまたはアルキル基である。）

(However, R and R ′ are each H or an alkyl group.)

The compound represented by the above formula (II) is a component having a high hydrogen bonding property. For this reason, it has a high affinity with water, can retain an appropriate amount of water, and can prevent unintentional volatilization of the aqueous dispersion medium in the ink flow path.
As described above, in the compound represented by the above formula (II) used in the present invention, R and R ′ are each hydrogen or an alkyl group, but R and R ′ are both hydrogen. preferable. That is, urea is preferable. Thereby, the moisture retention as described above can be made particularly high. Further, when the ceramic particles are present as colloidal particles as described above, the dispersion stability is particularly excellent, and the cleaning property of the cleaning liquid 2 is particularly excellent.

Alkanolamine is a highly moisturizing component, and when the metal particles and ceramic particles are colloidal particles as described above, the functional group of the dispersant on the surface of the colloidal particles can be activated. Dispersion stability can be made higher.
Examples of the alkanolamine include monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, and tripropanolamine.

The alkanolamine is preferably a tertiary amine. Tertiary amines have particularly high moisture retention among alkanolamines, and can make the above effects more remarkable.
Among tertiary amines, it is particularly preferable to use triethanolamine from the viewpoints of ease of handling, high moisture retention, and the like.

Sugar alcohol is obtained by reducing aldehyde groups and ketone groups of sugars.
Sugar alcohol is a compound having high moisture retention.
Examples of sugar alcohols include threitol, erythritol, pentaerythritol, dipentaerythritol, tripentaerythritol, arabitol, ribitol, xylitol, sorbitol, mannitol, threitol, glycol, tallitol, galactitol, allitol, altritol, dolitol, iditol. Glycerin (glycerol), inositol, maltitol, isomaltitol, lactitol, tranitol and the like, and one or more of these can be used in combination.

In addition, when the drying inhibitor is contained in the ink 1, the drying inhibitor contained in the cleaning liquid 2 preferably includes at least a part of the components constituting the dispersant contained in the ink 1. Thereby, the cleaning liquid 2 and the ink 1 in the ink flow path can be quickly replaced after the cleaning.
The content of the drying inhibitor as described above in the cleaning liquid is preferably 3 wt% or more and 20 wt% or less, and more preferably 5 wt% or more and 15 wt% or less. Thereby, the unintentional volatilization of the aqueous dispersion medium in the ink flow path can be more effectively prevented.

[Other ingredients]
The cleaning liquid may contain other components.
Examples of such components include those used in ink 1, and specifically include surface tension adjusting agents, organic binders, ethylene glycol, 1,3-propanediol, 1,3-butylene glycol, propylene glycol. And polyhydric alcohols such as thiourea.
The cleaning liquid 2 as described above preferably has a lower surface tension at 25 ° C. than the ink 1. Thereby, at the time of washing | cleaning, the washing | cleaning liquid 2 can spread suitably in the washing | cleaning site | part of the droplet discharge apparatus 100. For this reason, the amount of dirt remaining on the cleaned portion after cleaning is particularly small.

  The surface tension of the cleaning liquid 2 at 25 ° C. is not particularly limited, but is preferably, for example, 15 to 45 dyn / cm, and more preferably 20 to 40 dyn / cm. Thereby, at the time of washing | cleaning, the washing | cleaning liquid 2 can spread suitably in the washing | cleaning site | part of the droplet discharge apparatus 100, and it can make the washing | cleaning property of the washing | cleaning liquid 2 excellent. Even if the cleaning liquid 2 remains in a very small amount, the influence on the surface tension of the ink 1 can be made extremely small. In addition, in this specification, the value measured based on JISK3362 can be employ | adopted for surface tension.

  The cleaning liquid 2 preferably has a lower viscosity at 25 ° C. than the ink 1. Thereby, at the time of washing | cleaning, the washing | cleaning liquid 2 can spread suitably in the washing | cleaning site | part of the droplet discharge apparatus 100. Further, at the time of cleaning, the cleaning liquid 2 can increase the flow velocity in the ink flow path. For this reason, the amount of dirt remaining on the cleaned portion after cleaning is particularly small.

  The viscosity of the cleaning liquid 2 at 25 ° C. is not particularly limited. For example, it is preferably 20 mPa · s or less, and more preferably 10 mPa · s or less. Thereby, at the time of washing | cleaning, a washing | cleaning liquid can spread suitably on the washing | cleaning site | part of the droplet discharge apparatus 100, and it can make the washing | cleaning property of the washing | cleaning liquid 2 excellent. Further, even if the cleaning liquid 2 remains in a very small amount, the influence on the viscosity of the ink 1 described later can be made extremely small. In the present specification, as the value of the viscosity, a value obtained by measurement at 25 ° C. using a vibration viscometer can be adopted, and in particular, the viscosity is measured at 25 ° C. in accordance with JIS Z8809. The required value can be adopted.

As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to these.
For example, each part constituting the droplet discharge device can be replaced with any one that exhibits the same function, or other configurations can be added. In the above-described embodiment, the liquid material (ink) discharged from the droplet discharge device is described as the conductive pattern forming ink. However, the liquid material is not limited to this, and for example, a color filter It may be a color filter forming ink for forming an image or a printing ink for forming an image.

DESCRIPTION OF SYMBOLS 1 ... Ink 2 ... Cleaning liquid 11 ... Board | substrate 100 ... Inkjet apparatus (droplet discharge apparatus) 110 ... Inkjet head (droplet discharge head, head) 111 ... Head main body 112 ... Vibration plate 113 ... Piezo element 114 ... Main body 115 ... Nozzle plate 115P ... Ink Ejecting Surface 116 ... Reservoir 117 ... Ink Chamber 118 ... Nozzle 118a ... Non-Ejecting Nozzle 130 ... Base 140 ... Table 150 ... Ink Reservoir 151 ... Ink Transport Path 152 ... Open / Close Valve 153 ... Self-Sealing Valve 170 ... Table Positioning means 171 ... first moving means 172 ... motor 180 ... head positioning means 181 ... second moving means 182 ... linear motors 183, 184, 185 ... motor 190 ... control device 191 ... drive circuit 200 ... cleaning mechanism 201 Suction medium transport path 202 ... Cleaning liquid transport path 203, 204 ... Branch 205 ... Communication path 210 ... Cleaning head 211 ... Outer pipe 212 ... Inner pipe 213, 215 ... Flow path 214 ... Suction port 216 ... Outlet 220 ... Suction pump 230 ... Recovery tank 240 ... Cleaning liquid storage tank 241,242 ... Tube 250 ... Pressure pump 260 ... Filter 290 ... Moving means

Claims (11)

A storage tank for storing a liquid material;
A droplet discharge head comprising a plurality of nozzles for discharging the liquid material sent from the storage tank;
A cleaning liquid storage tank for storing a cleaning liquid used for cleaning the droplet discharge head;
A cleaning head provided so as to be relatively close to and away from the droplet discharge head;
Moving means for relatively moving the cleaning head and the droplet discharge head while bringing the cleaning head into contact with the droplet discharge head;
The cleaning head is in contact with the droplet discharge head, the first opening covering a part of the plurality of nozzles, and the nozzle not covered by the first opening And a second opening that covers all or some of the nozzles,
While the cleaning head is in contact with the droplet discharge head, the moving head relatively moves the cleaning head and the droplet discharge head while the first opening opens. The cleaning liquid fed from the cleaning liquid storage tank is supplied into the droplet discharge head through the nozzle covered by the opening, and the second opening covers the second opening. A droplet discharge device configured to suck the cleaning liquid in the droplet discharge head through a nozzle.   With the cleaning head in contact with the droplet discharge head, the cleaning liquid is supplied from the first opening into the droplet discharge head through the nozzle covered by the first opening. And a first state in which the cleaning liquid in the droplet discharge head is sucked from the second opening via the nozzle covered by the second opening, and the second state from the second opening. The cleaning liquid is supplied into the droplet discharge head through the nozzle covered by the opening, and the droplet discharge head is supplied from the first opening through the nozzle covered by the first opening. The droplet discharge device according to claim 1, wherein the second state of sucking the cleaning liquid is alternately performed.   The cleaning head has an outer tube and an inner tube provided inside the outer tube, and is formed between one end of a flow path formed inside the inner tube and between the outer tube and the inner tube. 3. The droplet discharge device according to claim 1, wherein one end of the flow path configured as the first opening constitutes the first opening and the other constitutes the second opening.   3. The droplet discharge device according to claim 1, wherein the first opening is located on the front side in the relative movement direction of the cleaning head with respect to the droplet discharge head relative to the second opening.   In a state where the cleaning head is in contact with the droplet discharge head, the number of the nozzles covered by the first opening is X, and the number of the nozzles covered by the second opening is Y. 5. The droplet discharge device according to claim 1, wherein X / Y is 0.8 or more and 1.2 or less.   A filter for removing the liquid material contained in the cleaning liquid sucked from the second opening, and the cleaning liquid from which the liquid material has been removed by the filter is sent from the cleaning head into the droplet discharge head. Item 6. A droplet discharge device according to any one of Items 1 to 5.   7. The valve according to claim 1, further comprising a valve that prevents the liquid material from being fed from the storage tank to the droplet discharge head in a state where the cleaning liquid is supplied into the droplet discharge head. A droplet discharge device according to claim 1.   The liquid according to any one of claims 1 to 7, wherein the cleaning liquid is a liquid that can dissolve or disperse a solid content contained in the liquid material and is compatible with a main solvent contained in the liquid material. Drop ejection device.   The droplet discharge apparatus according to claim 8, wherein the cleaning liquid contains the main solvent of the liquid material as a main component.   The liquid droplet ejection apparatus according to claim 1, wherein the liquid material is obtained by dispersing metal particles in a dispersion medium. A storage tank for storing a liquid material;
A droplet discharge head comprising a plurality of nozzles for discharging the liquid material sent from the storage tank;
A cleaning liquid storage tank for storing a cleaning liquid used for cleaning the droplet discharge head;
A cleaning head provided so as to be relatively close to and away from the droplet discharge head;
Moving means for relatively moving the cleaning head and the droplet discharge head while bringing the cleaning head into contact with the droplet discharge head;
The cleaning head is in contact with the droplet discharge head, the first opening covering a part of the plurality of nozzles, and the nozzle not covered by the first opening And a second opening that covers all or some of the nozzles,
While the cleaning head is in contact with the droplet discharge head, the moving head relatively moves the cleaning head and the droplet discharge head while the first opening opens. The cleaning liquid fed from the cleaning liquid storage tank is supplied into the droplet discharge head through the nozzle covered by the opening, and the second opening covers the second opening. A cleaning method for a droplet discharge device, wherein the cleaning liquid in the droplet discharge head is sucked through a nozzle.

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