JP2015003491A - Maintenance method of liquid discharge head and liquid discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a maintenance method of a liquid discharge head which keeps a clean surface of a water repellent film that inhibits a liquid from penetrating into a space between head modules, is durable even if the liquid penetrates into the space, achieves the manufacturing suitability, and is formed at the space, and to provide the liquid discharge head.SOLUTION: A side surface 202 of a head module which faces an adjacent head module through a space 160 has a water repellent film to which a water repellent material including fluorine is applied. In a maintenance method of a liquid discharge head, a cleaning fluid is placed into the space 160 and the cleaning fluid in the space 160 is suctioned.

Description

  The present invention relates to a liquid discharge head maintenance method and a liquid discharge head, and more particularly to a liquid discharge head maintenance method and a liquid discharge head formed by connecting a plurality of head modules.

  In order to realize high-speed printing with a liquid discharge head, it is necessary to adopt a one-pass scanning method using a line head in which a plurality of head modules are connected. In order to put this line head into practical use at a low cost, it is necessary to make it possible to replace individual head modules. Thereby, for example, when one module is defective, a low maintenance cost can be realized by replacing only the target module without replacing the entire line head.

  If each head module is configured to be replaceable, a gap is naturally generated between the head modules. When a gap is generated between the head modules, ink mist discharged from the nozzles enters the gap during printing, or ink on the nozzle surface is pushed into the gap by wiping the nozzle surface during maintenance. The ink that has entered the gap causes ink dripping when in the liquid state, and causes the recording medium to become dirty during printing.

  Therefore, Patent Document 1 discloses a technique for filling the gap with a gap filler such as wax. In this technique, by using a wax that melts at a low temperature of about 40 ° C., the wax can be melted and removed when the head is replaced. However, when solvent-based ink is used for wax, the wax dissolves and may clog the nozzle surface, or the melted wax may clog the nozzle when replacing the head. .

  Patent Document 2 discloses a technique for preventing ink from adhering to the periphery of the head by attaching a water-repellent sheet to the gap between the head and the spacer. However, in general, such a water-repellent sheet has a thickness of several hundred μm, and when used for a line head for replacement, the water-repellent sheet cannot be pasted unless a gap of about 1 mm is provided. It cannot be used in the case of a nozzle head. And, the ink to be ejected often has a lower surface tension than water, but if the contact angle in the gap is less than 90 °, the ink will theoretically intrude even if the water repellent coating is applied to the side surface. . The water repellent sheet is affixed to the side of the head with an adhesive, but once the ink has infiltrated, once the ink has infiltrated the side, it easily peels off and the water repellency on the side is lost. End up.

Therefore, in order to overcome the problems of Patent Document 2, the technique disclosed in Patent Document 3 can be used. In Patent Document 3, a strong and stable water-repellent film can be formed by forming a siloxane film on a reinforced molded body containing a filler and then forming a water-repellent film with a chlorosilane-based chemical adsorbent. It is disclosed. In Patent Document 3, since the water-repellent film is in close contact by chemical bonding, the adhesive does not elute and peel off unlike the water-repellent sheet. Moreover, since the thickness is very thin, the design of the head gap is not restricted. In Patent Document 3, SiCl ₄ is used as an inner film layer (primer layer), and a chlorosilane-based chemical adsorbent CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ SiCl ₃ is used as a surface layer film. Since the chlorosilane-based water repellent material as in Patent Document 3 easily reacts with moisture in the air and the adsorbents themselves are polymerized, generally in a vacuum chamber or in a dry nitrogen atmosphere The reaction is carried out in an environment where there is no moisture, such as a glove box, and then it is reacted with moisture in the air for hydrolysis.

JP 2008-80762 A JP 2005-103781 A JP-A-6-93121

  However, since the technique of Patent Document 3 uses a highly reactive reagent, the manufacturing facilities are complicated, and it is difficult to stably obtain a good quality water-repellent film.

Therefore, as the inner film layer (primer layer), a SiO ₂ type coating agent that does not hydrolyze immediately like tetraethoxysilane (TEOS: (Si (OC ₂ H ₅ ) ₄ )) is used, and a water repellent material is formed thereon. Such a primer layer is generally wiped well after being applied once, and then a water-repellent material is applied onto the primer layer. In this case, there is a problem that the primer layer which is not sufficiently hydrolyzed enters between the layers, and the adhesion of the water-repellent film is decreased. There is also the problem of variation.

  Therefore, it is preferable not to use a primer layer. However, when a water-repellent material is used for a plastic material such as an epoxy, there is no hydrophilic group for obtaining adhesion. Can't get. Therefore, when a silane coupling agent is directly applied, a water repellent film with good adhesion is required.

  Note that ink may enter the gap between the head modules, but it is not mechanically rubbed. Therefore, the water repellent film is required to have good adhesion to the chemical attack of the ink and be suitable for production.

  By the way, even if water repellency is imparted to the gaps between the head modules, the probability of ink penetration can be reduced in a liquid having a contact angle of 90 ° or less, but ink penetration cannot be completely prevented. Therefore, when ink enters the gap and the ink dries, the water-repellent film in the gap does not function, and there is a problem that further ink penetration is allowed.

  The same applies not only to ink but also to a liquid that chemically attacks the water-repellent film enters the gap between the head modules of the liquid ejection head.

  The present invention has been made in view of such circumstances, and is a water repellent film that is suitable for manufacturing and has durability even when liquid enters the gap between the head modules and has durability even if liquid enters the gap. An object of the present invention is to provide a maintenance method for a liquid discharge head and a liquid discharge head that can keep the surface of the water-repellent film in the gap clean.

  In order to achieve the above object, the present invention provides a maintenance method for a liquid discharge head in which a plurality of head modules each having a nozzle surface on which a plurality of nozzles for discharging a liquid are arranged, wherein a gap is formed between adjacent head modules. A liquid discharge head having a water-repellent film coated with a fluorine-containing water-repellent material on the side surface of the head module facing each other, and a step of allowing the cleaning liquid to enter the gap and a step of sucking the cleaning liquid in the gap Provide maintenance methods.

  According to this embodiment, the side surface of the head module facing the adjacent head module through the gap has the water-repellent film coated with the fluorine-containing water-repellent material. The liquid can be prevented from entering the liquid, and even when liquid enters the gap, it has durability, and since it is coated with a water-repellent material containing fluorine, the manufacturing suitability is also good.

  Then, a water repellent film coated with a fluorine-containing water repellent material is provided on the side surface of the head module, and a liquid intrudes into the gap by having a step of injecting the cleaning liquid into the gap and a step of sucking out the cleaning liquid in the gap. Even if this is done, the surface of the water-repellent film in the gap can be kept clean.

  Therefore, according to the present invention, it is a water repellent film that is suitable for manufacturing and has durability even if liquid enters the gap between the head modules and has durability even if liquid enters the gap. Can be kept clean.

  In this embodiment, the side surface of the head module is made of a plastic material containing glass filler, and the water-repellent film is coated with a fluorine-based silane coupling agent terminated with a methoxy group on the plastic material containing glass filler. And it is preferable that it is humidified.

  Compared with chlorosilane-based water-repellent materials, fluorine-based silane coupling agents terminated with a methoxy group can be handled in the air, so manufacturing facilities are not complicated and stable, high-quality water-repellent films Can be obtained. Moreover, since the side surface is made of a plastic material containing glass filler, a water repellent material can be directly applied without the need for a primer layer, so that it is easy to provide a water repellent film. There is no variation in membrane performance.

  In this embodiment, the step of injecting the cleaning liquid into the gap preferably includes injecting the cleaning liquid into the gap by ejecting the cleaning liquid with an injection nozzle, and the step of sucking out the cleaning liquid in the gap preferably sucks out the cleaning liquid with the sucking member.

  By spraying the cleaning liquid with the spray nozzle, the cleaning liquid is allowed to enter the gap, and the cleaning liquid is sucked with the sucking member, so that the surface of the water-repellent film in the gap can be easily kept clean.

  In this embodiment, the blotting member is preferably a fiber cloth.

  If it is a fiber cloth, a washing | cleaning liquid can be blotted off suitably.

  In this embodiment, the fiber cloth is preferably a fiber cloth made of polyethylene terephthalate resin.

  Since the fiber cloth made of polyethylene terephthalate resin is less likely to generate fiber waste, it is possible to prevent clogging of the nozzle of the liquid discharge head due to dust generation. In addition to fibers made of polyethylene terephthalate resin, mixed fibers made of polyethylene terephthalate resin and nylon resin are also preferable. More preferred is a fiber cloth made of polyethylene terephthalate resin.

  In the present embodiment, the step of sucking the cleaning liquid in the gap can further suck the cleaning liquid with a suction nozzle.

  In addition to sucking the cleaning liquid with the fiber cloth, the surface of the water-repellent film in the gap can be further cleaned by sucking the cleaning liquid with the suction nozzle. Note that the step of sucking the cleaning liquid in the gap can be performed only by sucking the cleaning liquid with the suction nozzle, and it is also possible to use both the suction with the fiber cloth and the suction of the cleaning liquid with the suction nozzle.

  In this embodiment, it is preferable that the step of allowing the cleaning liquid to enter the gap and the step of sucking the cleaning liquid in the gap are performed at regular intervals.

  The surface of the water-repellent film in the gap can be suitably kept clean by performing the step of allowing the cleaning liquid to enter the gap and the step of sucking the cleaning liquid in the gap at regular intervals.

  In this embodiment, the application of the water repellent material is preferably performed twice or more.

  By applying a water repellent material twice or more to form a water repellent film, it is possible to have a water repellent film that does not come off due to air bubbles or the like. The water repellent material according to this embodiment preferably uses a device for applying a liquid such as a dispenser, for example, in order to make a part of the water repellent. The water-repellent material according to this embodiment is preferably a coating method, but for example, a gas phase method such as a vapor deposition method or a CVD method may be used by masking a portion where water repellency is unnecessary with a tape or the like in advance. it can.

  In this embodiment, the water repellent film is preferably formed on the entire side surface.

  In general, when a part of the head module side surface near the nozzle surface is subjected to water repellency, the liquid that has entered the gap is sucked up by capillary force, and the liquid accumulates in the hydrophilic part of the side of the head module that has not been subjected to water repellency. End up. If there is a hydrophilic surface in the vicinity of the water repellent surface, the liquid that has entered the water repellent portion generally tends to move to the hydrophilic portion. Therefore, in order to further suppress the liquid suction due to the capillary force, it is preferable to perform water repellent treatment on the entire side surface.

  Here, the entire side surface of the head module means the entire side surface forming the gap. The side surfaces in the longitudinal direction that do not form gaps need not be water repellent. If the water repellent treatment is performed also in the longitudinal direction, the ink moving to the hydrophilic portion is reduced, and the durability is further improved. Further, if the water repellent treatment is not performed in the longitudinal direction, the area where the water repellent material is provided is reduced, which leads to cost reduction.

  In order to achieve the above object, the present invention is a liquid discharge head in which a plurality of head modules each having a nozzle surface on which a plurality of nozzles for discharging a liquid are arranged, and is opposed to adjacent head modules via a gap. The side surface of the head module is made of a plastic material containing a glass filler, and has a humidified water-repellent film by applying a fluorine-based silane coupling agent terminated with a methoxy group on the plastic material containing a glass filler. A liquid discharge head is provided.

  According to this embodiment, it is a water repellent film having manufacturability and having durability even when liquid enters the gap between the head modules, and the surface of the water repellent film in the gap is cleaned. Can be kept in. According to the present embodiment, when the water repellency is lowered after use, it is possible to re-apply the fluorine-based silane coupling agent after wiping and washing the module side member with a solvent or the like.

  According to the liquid discharge head maintenance method and the liquid discharge head of the present invention, a liquid repellent film that is manufacturable and has durability even if liquid enters the gap between the head modules. Thus, it is possible to provide a liquid discharge head maintenance method and a liquid discharge head that can keep the surface of the water-repellent film in the gap clean.

1 is an overall configuration diagram of an ink jet recording apparatus. It is a perspective view of an inkjet head. It is a top view which shows the structural example of the inkjet head shown in FIG. FIG. 4 is a partially enlarged view of FIG. 3. FIG. 4 is a plan perspective view of the head module shown in FIG. 3. It is sectional drawing which shows the maintenance of the liquid discharge head which concerns on this invention. 6 is a table showing Experiment 1. FIG. It is a table | surface figure which shows experiment 2A. It is a table | surface figure which shows experiment 2B. It is a table | surface figure which shows experiment 2D.

  Hereinafter, preferred embodiments of a liquid discharge head and a method of manufacturing a liquid discharge head according to the present invention will be described with reference to the accompanying drawings. Hereinafter, an ink jet head will be described as an example of the liquid discharge head. An ink jet recording apparatus having this ink jet head will be described.

<< Overall configuration of inkjet recording apparatus >>
First, the overall configuration of the ink jet recording apparatus will be described. FIG. 1 is a configuration diagram showing the overall configuration of the ink jet recording apparatus.

  The inkjet recording apparatus 10 includes a plurality of colors from inkjet heads 72M, 72K, 72C, and 72Y on a recording medium 24 (sometimes referred to as “paper” for convenience) held on an impression cylinder (drawing drum 70) of the drawing unit 16. Is an impression cylinder direct drawing type ink jet recording apparatus that forms a desired color image by applying ink droplets of the ink. This is an on-demand type image forming apparatus to which a two-liquid reaction (aggregation) method for forming an image on a recording medium 24 by reacting a treatment liquid and an ink liquid is applied.

  As shown in the figure, the ink jet recording apparatus 10 mainly includes a paper feed unit 12, a treatment liquid application unit 14, a drawing unit 16, a drying unit 18, a fixing unit 20, and a discharge unit 22.

(Paper Feeder)
The paper supply unit 12 is a mechanism that supplies the recording medium 24 to the treatment liquid application unit 14, and a recording medium 24 that is a sheet is stacked on the paper supply unit 12. The paper feed unit 12 is provided with a paper feed tray 50, and the recording medium 24 is fed from the paper feed tray 50 to the processing liquid application unit 14 one by one.

  In the inkjet recording apparatus 10 of this example, a plurality of types of recording media 24 having different paper types and sizes (paper sizes) can be used as the recording medium 24. A mode is also possible in which a plurality of paper trays (not shown) are provided in the paper feed unit 12 to separately collect various recording media and the paper to be sent to the paper feed tray 50 is automatically switched from among the plurality of paper trays. In addition, a mode is also possible in which the operator selects or replaces the paper tray as necessary. In this example, a sheet (cut paper) is used as the recording medium 24, but a configuration in which continuous paper (roll paper) is cut to a required size and fed is also possible.

(Processing liquid application part)
The processing liquid application unit 14 is a mechanism that applies the processing liquid to the recording surface of the recording medium 24. The treatment liquid includes a color material aggregating agent that agglomerates the color material (pigment in this example) provided in the drawing unit 16. And the solvent are promoted.

  As shown in FIG. 1, the treatment liquid application unit 14 includes a paper feed drum 52, a treatment liquid drum 54, and a treatment liquid application device 56. The treatment liquid drum 54 is a drum that holds and rotates and conveys the recording medium 24. The processing liquid drum 54 is provided with a claw-shaped holding means (gripper) 55 on the outer peripheral surface thereof, and the recording medium 24 is sandwiched between the claw of the holding means 55 and the peripheral surface of the processing liquid drum 54 to thereby remove the recording medium 24. The tip can be held. The treatment liquid drum 54 may be provided with suction holes on the outer peripheral surface thereof and connected to suction means for suction from the suction holes. As a result, the recording medium 24 can be held in close contact with the peripheral surface of the treatment liquid drum 54.

  A processing liquid coating device 56 is provided outside the processing liquid drum 54 so as to face the peripheral surface thereof. The processing liquid coating device 56 includes a processing liquid container in which the processing liquid is stored, an anix roller partially immersed in the processing liquid in the processing liquid container, and the recording medium 24 on the anix roller and the processing liquid drum 54. And a rubber roller that transfers the measured processing liquid to the recording medium 24. According to the processing liquid application device 56, the processing liquid can be applied to the recording medium 24 while being measured.

  The recording medium 24 to which the processing liquid is applied by the processing liquid applying unit 14 is transferred from the processing liquid drum 54 to the drawing drum 70 of the drawing unit 16 via the intermediate transport unit 26.

(Drawing part)
The drawing unit 16 includes a drawing drum (second transport body) 70, a sheet pressing roller 74, and inkjet heads 72M, 72K, 72C, and 72Y. The drawing drum 70 includes a claw-shaped holding means (gripper) 71 on the outer peripheral surface thereof, like the processing liquid drum 54. The recording medium 24 fixed to the drawing drum 70 is conveyed with the recording surface facing outward, and ink is applied to the recording surface from the inkjet heads 72M, 72K, 72C, 72Y.

  Each of the inkjet heads 72M, 72K, 72C, and 72Y is preferably a full-line inkjet recording head (inkjet head) having a length corresponding to the maximum width of the image forming area in the recording medium 24. On the ink ejection surface, a nozzle row in which a plurality of nozzles for ink ejection are arranged over the entire width of the image forming area is formed. Each inkjet head 72M, 72K, 72C, 72Y is installed so as to extend in a direction orthogonal to the conveyance direction of the recording medium 24 (the rotation direction of the drawing drum 70).

  The droplets of the corresponding color ink are ejected from the respective ink jet heads 72M, 72K, 72C, 72Y toward the recording surface of the recording medium 24 held tightly on the drawing drum 70. The ink comes into contact with the treatment liquid previously applied to the recording surface, and the color material (pigment) dispersed in the ink is aggregated to form a color material aggregate. Thereby, the color material flow on the recording medium 24 is prevented, and an image is formed on the recording surface of the recording medium 24.

  In this example, the configuration of CMYK standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, and special colors are used as necessary. Ink may be added. For example, it is possible to add an inkjet head that discharges light-colored ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

  The recording medium 24 on which an image is formed by the drawing unit 16 is transferred from the drawing drum 70 to the drying drum 76 of the drying unit 18 via the intermediate conveyance unit 28.

(Drying part)
The drying unit 18 is a mechanism for drying moisture contained in the solvent separated by the color material aggregation action, and includes a drying drum 76 and a solvent drying device 78 as shown in FIG.

  Similar to the treatment liquid drum 54, the drying drum 76 includes a claw-shaped holding unit (gripper) 77 on the outer peripheral surface thereof, and the holding unit 77 can hold the leading end of the recording medium 24.

  The solvent drying device 78 is disposed at a position facing the outer peripheral surface of the drying drum 76, and includes a plurality of IR heaters 82 and hot air ejection nozzles 80 disposed between the IR heaters 82.

  Various drying conditions can be realized by appropriately adjusting the temperature and air volume of the hot air blown toward the recording medium 24 from each hot air jet nozzle 80 and the temperature of each IR heater 82.

  The surface temperature of the drying drum 76 is set to 50 ° C. or higher. Drying is accelerated by heating from the back surface of the recording medium 24, and image destruction during fixing can be prevented. The upper limit of the surface temperature of the drying drum 76 is not particularly limited, but from the viewpoint of safety of maintenance work such as cleaning ink adhering to the surface of the drying drum 76 (preventing burns due to high temperature). It is preferably set to 75 ° C. or lower (more preferably 60 ° C. or lower).

  The recording drum 24 is held on the outer peripheral surface of the drying drum 76 so that the recording surface of the recording medium 24 faces outward (that is, in a state where the recording surface of the recording medium 24 is convex), and is dried while being rotated and conveyed. By doing so, it is possible to prevent the recording medium 24 from being wrinkled or lifted, and to reliably prevent uneven drying due to these.

  The recording medium 24 that has been dried by the drying unit 18 is transferred from the drying drum 76 to the fixing drum 84 of the fixing unit 20 via the intermediate conveyance unit 30.

(Fixing part)
The fixing unit 20 includes a fixing drum 84, a halogen heater 86, a fixing roller 88, and an inline sensor 90. Like the processing liquid drum 54, the fixing drum 84 includes a claw-shaped holding unit (gripper) 85 on its outer peripheral surface, and the holding unit 85 can hold the leading end of the recording medium 24.

  With the rotation of the fixing drum 84, the recording medium 24 is conveyed with the recording surface facing outward. The recording surface is preheated by the halogen heater 86, fixed by the fixing roller 88, and by the inline sensor 90. Inspection is performed.

  The halogen heater 86 is controlled to a predetermined temperature (for example, 180 ° C.). Thereby, the recording medium 24 is preheated.

  The fixing roller 88 is a roller member for heating and pressurizing the dried ink to weld the self-dispersing thermoplastic resin fine particles in the ink to form a film of the ink. The fixing roller 88 is configured to heat and press the recording medium 24. Composed. Specifically, the fixing roller 88 is disposed so as to be in pressure contact with the fixing drum 84, and constitutes a nip roller with the fixing drum 84. As a result, the recording medium 24 is sandwiched between the fixing roller 88 and the fixing drum 84 and nipped at a predetermined nip pressure (for example, 0.15 MPa), and a fixing process is performed.

  The fixing roller 88 is configured by a heating roller in which a halogen lamp is incorporated in a metal pipe such as aluminum having good thermal conductivity, and is controlled to a predetermined temperature (for example, 60 to 80 ° C.). By heating the recording medium 24 with this heating roller, thermal energy equal to or higher than the Tg temperature (glass transition temperature) of the thermoplastic resin fine particles contained in the ink is applied, and the thermoplastic resin fine particles are melted. As a result, pressing and fixing are performed on the unevenness of the recording medium 24, and the unevenness of the image surface is leveled to obtain glossiness.

  In the embodiment of FIG. 1, only one fixing roller 88 is provided. However, a configuration in which a plurality of fixing rollers 88 are provided may be employed depending on the thickness of the image layer and the Tg characteristics of the thermoplastic resin fine particles.

  On the other hand, the in-line sensor 90 is a measuring means for measuring a check pattern, a moisture content, a surface temperature, a glossiness, and the like for an image fixed on the recording medium 24, and a CCD line sensor or the like is applied.

  According to the fixing unit 20 configured as described above, the thermoplastic resin fine particles in the thin image layer formed by the drying unit 18 are heated and pressurized by the fixing roller 88 and melted. Can be fixed and fixed. Further, by setting the surface temperature of the fixing drum 84 to 50 ° C. or higher, drying is promoted by heating the recording medium 24 held on the outer peripheral surface of the fixing drum 84 from the back surface, thereby preventing image destruction during fixing. In addition, the image intensity can be increased by the effect of increasing the image temperature.

  In addition, when a UV curable monomer is contained in the ink, after the water is sufficiently volatilized in the drying unit, the image is irradiated with UV at the fixing unit equipped with a UV irradiation lamp. The monomer can be cured and polymerized to improve the image strength.

(Discharge part)
As shown in FIG. 1, a discharge unit 22 is provided following the fixing unit 20. The discharge unit 22 includes a discharge tray 92, and a transfer drum 94, a conveyance belt 96, and a tension roller 98 are provided between the discharge tray 92 and the fixing drum 84 of the fixing unit 20 so as to be in contact therewith. It has been. The recording medium 24 is sent to the conveying belt 96 by the transfer drum 94 and discharged to the discharge tray 92.

  Although not shown in the drawing, the ink jet recording apparatus 10 of the present example has an ink storage / loading unit for supplying ink to each of the ink jet heads 72M, 72K, 72C, and 72Y, and a treatment liquid application, in addition to the above-described configuration. A means for supplying a processing liquid to the unit 14, and a head maintenance unit for cleaning each of the inkjet heads 72M, 72K, 72C, 72Y (wiping, purging, nozzle suction, etc. of the nozzle surface), A position detection sensor for detecting the position of the recording medium 24, a temperature sensor for detecting the temperature of each part of the apparatus, and the like are provided.

[Configuration of inkjet head]
FIG. 2 is a perspective view of the inkjet head. FIG. 2 illustrates a state in which the ejection surface is looked up from below the ink jet head 72 (obliquely downward direction). The ink-jet head 72 is a print head installed in a drawing section of an ink-jet recording apparatus, and is a full-line bar head (single-line head) in which a plurality of head modules 72-i are aligned and connected in the paper width direction. Page wide head with pass printing). Here, an example in which 17 head modules 72-i are connected is shown, but the configuration of the modules, the number of modules, and the arrangement form are not limited to the illustrated examples. Reference numeral 104 denotes a housing (housing for constituting a bar-shaped line head) serving as a frame for fixing a plurality of head modules 72-i, and reference numeral 106 denotes a flexible member connected to each head module 72-i. It is a substrate.

  FIG. 3 is a plan view showing a structural example of the head 72, and is a view of the head 72 as seen from the nozzle surface 72A side. FIG. 4 is a partially enlarged view of FIG.

  As shown in FIG. 3, the head 72 has n head modules 72-i (i = 1, 2, 3,..., N) perpendicular to the transport direction of the longitudinal direction (recording medium 24 (see FIG. 1)). ), And a plurality of nozzles (not shown in FIG. 3) are provided over a length corresponding to the entire width of the recording medium.

  Each head module 72-i is supported by a head module support member 72B from both sides of the head 72 in the short direction. Further, both end portions of the head 72 in the longitudinal direction are supported by a head support member 72D.

  As shown in FIG. 4, each head module 72-i (n-th head module 72-n) has a structure in which a plurality of nozzles are arranged in a matrix. In FIG. 4, an oblique solid line denoted by reference numeral 151A represents a nozzle row in which a plurality of nozzles are arranged in a row.

  Fig.5 (a) is a plane perspective view of the head module 72-i, and FIG.5 (b) is the one part enlarged view.

  In order to increase the dot pitch formed on the recording medium 24, it is necessary to increase the nozzle pitch in the head 72. As shown in FIGS. 5A and 5B, the head module 72-i of this example includes a plurality of ink chamber units each including a nozzle 151 that is an ink discharge port, a pressure chamber 152 corresponding to each nozzle 151, and the like. (Droplet discharge elements as recording element units) 153 has a structure in which the zigzag is arranged in a matrix (two-dimensionally), and thereby, the head longitudinal direction (direction orthogonal to the transport direction of the recording medium 24); High density of the substantial nozzle interval (projection nozzle pitch) projected along the main scanning direction is achieved.

  The pressure chamber 152 provided corresponding to each nozzle 151 has a substantially square planar shape, the nozzle 151 is provided at one of the diagonal corners, and the supply port 154 is provided at the other. ing. The shape of the pressure chamber 152 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon, other polygons, a circle, and an ellipse.

  As shown in FIG. 5B, the ink chamber units 153 having such a structure are arranged in a fixed manner along a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. By arranging a large number of patterns in a lattice pattern, the high-density nozzle head of this example is realized.

  That is, with a structure in which a plurality of ink chamber units 153 are arranged at a constant pitch d along the direction of an angle θ with respect to the main scanning direction, the pitch P of the nozzles projected in the main scanning direction is d × cos θ. Thus, in the main scanning direction, each nozzle 151 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which the number of nozzle rows projected so as to be aligned in the main scanning direction is 2400 per inch (2400 nozzles / inch).

<Configuration of head module side>
Next, the configuration of the side surface of the head module will be described. FIG. 6 is a cross-sectional view of a head module of a liquid discharge head in which a plurality of head modules are connected together.

  As shown in FIG. 6, a water repellent film is formed on the side surface 202 facing the adjacent head modules 72-(i-1) and 72-i via the gap 160. In the present invention, the “water repellent film” is a film having a static contact angle of water of 60 ° or more.

  The method for forming the water repellent film is not particularly limited, and the film can be formed by applying and drying a water repellent material.

  As a material for the water repellent film, a water repellent material containing fluorine can be used.

  Preferably, a fluorine-based silane coupling agent terminated with a methoxy group can be used with the side surface 202 of the head module as a plastic material containing glass filler. The side surface 202 of the head module is optimally made of a plastic material containing a glass filler, but may be any plastic material containing an oxide filler.

  The film thickness of the water repellent film is determined by the distance between the head modules 72-i.

  When the distance between the head modules 72-i becomes large, the nozzles must be arranged so as to correct the gap, and therefore the allowable distance between the head modules is 2/3 or less of the distance between the nozzles. For example, in the case of a 1200 dpi high density head, the minimum distance between nozzles is about 300 μm. On the other hand, when the gap is too narrow, the modules may collide with each other and be damaged when the modules are replaced. In addition, since the capillary length is inversely proportional to the size of the gap, it is preferable that the ink enters the gap with a wider interval. From this viewpoint, for example, the gap is preferably 150 μm or more.

  Therefore, since the water repellent film is formed on both sides of the head module, it is necessary that the water repellent film is ½ or less (for example, 150 μm or less) of the inter-module distance. Further, since the capillary length is inversely proportional to the size of the gap, it is preferable that the gap is not narrowed by the applied water-repellent film. For example, it is preferably 1% or less of the gap interval, for example, 1.5 μm or less on one side.

  The application of the water repellent material is preferably performed twice or more. By applying a water repellent material twice or more to form a water repellent film, it is possible to have a water repellent film that does not come off due to air bubbles or the like.

  In addition, when a fluorinated silane coupling agent terminated with a methoxy group is used as a water-repellent material, unlike a chloro-based water-repellent material, it does not hydrolyze even in air. Therefore, in a room temperature and humidity environment of 25 ° C. and 50% humidity, it is necessary to leave it humidified for one day or more, preferably about one week. Note that this time can be shortened in a high-temperature and high-humidity environment.

  The water repellent film 204 is preferably formed on the entire surface of the side surface 202 of the head module. In general, when a part of the head module side surface near the nozzle surface is subjected to water repellency, the liquid that has entered the gap is sucked up by capillary force, and the liquid accumulates in the hydrophilic part of the side of the head module that has not been subjected to water repellency. End up. If there is a hydrophilic surface in the vicinity of the water repellent surface, the liquid that has entered the water repellent portion generally tends to move to the hydrophilic portion. Therefore, in order to further suppress the liquid suction due to the capillary force, it is preferable to perform water repellent treatment on the entire side surface. Here, the entire surface of the side surface of the head module means the entire surface of the side surface 202 that forms the gap 160.

<Maintenance method of liquid discharge head>
A maintenance method for the side surface of the head module configured as described above will be described.

  The maintenance method for the liquid discharge head according to the present embodiment includes a step of allowing the cleaning liquid to enter the gap between the head modules and a step of sucking the cleaning liquid into the gap between the head modules. By including the step of intruding the cleaning liquid into the gap and the step of sucking out the cleaning liquid in the gap, the surface of the water-repellent film in the gap can be kept clean even if the ink enters the gap. In addition, in a line head in which a plurality of head modules are arranged, it is inevitable that ink enters the gap even if the water repellent film as described above is provided on the side of the head module.

  In the present embodiment, the step of injecting the cleaning liquid into the gap of the head module preferably injects the cleaning liquid into the gap by ejecting the cleaning liquid with an injection nozzle, and the step of sucking out the cleaning liquid in the gap preferably sucks out the cleaning liquid with the sucking member. . As the blotting member, paper, cloth, porous material, and the like are conceivable, but cloth is preferable, and fiber cloth is preferable among cloths.

  FIG. 6 shows a gap ink sucking mechanism 300 that is an example for carrying out the maintenance method of the head module side surface.

  The gap ink sucking mechanism 300 in FIG. 6 includes a jet nozzle 302 and a fiber cloth pressing unit 304. 6 and the fabric cloth pressing unit 304 are provided on the same frame 306.

  The gap ink sucking mechanism 300 having the ejection nozzle 302 and the fiber cloth pressing portion 304 is movable in the width direction of the line head by moving the gantry 306. The gantry 306, the injection nozzle 302, and the fiber cloth pressing unit 304 are controlled by a control unit (not shown). Although FIG. 6 shows that the gap ink sucking mechanism 300 is movable in the width direction of the line head, the gap ink sucking mechanism 300 may be fixed and the line head may be movable.

  The ejection nozzle 302 ejects the cleaning liquid into the gap 160 of the head module. The fiber cloth pressing unit 304 sucks the cleaning liquid sprayed into the gap 160 of the head module by the fiber cloth 304 a provided in the fiber cloth pressing unit 304.

  As described above, the cleaning liquid is injected into the gap by jetting the cleaning liquid with the jet nozzle 302, and the water repellent film surface of the gap 160 can be easily kept clean by sucking the cleaning liquid with the fiber cloth 304a. Therefore, even when the ink enters the gap 160 and the side surface 202 becomes dirty, the water repellency can be maintained by the gap ink sucking mechanism 300.

  In the present embodiment, in the step of sucking the cleaning liquid in the gap, the cleaning liquid can be further sucked by a suction nozzle (not shown). Not only the cleaning liquid is sucked by the fiber cloth, but also the cleaning liquid is sucked by the suction nozzle, so that the surface of the water-repellent film in the gap can be kept clean.

  However, only a suction nozzle is conceivable for sucking the cleaning liquid in the gap. However, in many cases, the gap 160 of the line head is less than 1 mm, and it is difficult to suck out the cleaning liquid with the suction nozzle alone. In addition, any cloth or paper may be used for sucking the cleaning liquid. However, there is a problem that fiber scraps are generated from the cloth due to wiping, and the nozzle is clogged. A fiber cloth made of polyethylene terephthalate resin with low dust generation such as a trademark is preferred. In addition to fibers made of polyethylene terephthalate resin, mixed fibers made of polyethylene terephthalate resin and nylon resin are also preferable. Moreover, non-woven fabrics, such as Asahi Kasei Benlyse (registered trademark), which are less likely to generate fiber debris, can be used. The fiber cloth preferably has a diameter of 2 μm or more and 10 μm or less.

  In this embodiment, it is preferable that the step of allowing the cleaning liquid to enter the gap and the step of sucking the cleaning liquid in the gap are performed at regular intervals. The surface of the water-repellent film in the gap can be suitably kept clean by performing the step of allowing the cleaning liquid to enter the gap and the step of sucking the cleaning liquid in the gap at regular intervals.

  The technical scope of the present invention is not limited to the scope described in the above embodiment. The configuration and the like in each embodiment can be changed without departing from the spirit of the present invention. For example, the arrangement form of the modules is not limited to the examples in FIGS. 2 to 4, and even if the part where the side surfaces of the adjacent head modules are opposed is a part, a gap is formed by a part. For example, the present invention holds.

(Experiment 1)
A simple line head with a head module connected was made as a prototype, and an evaluation test was conducted by immersing water-based pigment ink.

  The ink was immersed in the nozzle surface of the connection module and left to stand. The ink temperature was 60 ° C. The ink was replenished at regular intervals, and the ink was always immersed in the nozzle surface.

(Samples 1-9)
Samples 1 to 9 shown in Table 1 of FIG. 7 were prepared. As shown in Table 1, an epoxy material mixed with glass fiber was used for the side surface of the head module of the inkjet head. For comparison, Sample 1 used a normal epoxy material.

  As the side material, Harves DS-5210TH (0.1 wt%) was used. As a primer, 0.5 wt% of Harves PC-3B TEOS (tetraethoxysilane) was prepared. Sample 5 was a Harves DS-3320 made up of only a fluororesin dispersion. For sample 6, a water-repellent sheet ASF116TFR made by Daikin was attached and ink immersion was performed. In addition, application | coating of the material of a side surface was performed using the tubing dispenser MT-410 by Musashi engineering, and the desktop robot Shot Master.

  After exposing the gap on the side surface of the head module to the ink, the contact angle on the side surface of the head module was measured with water at 100C every 100 hours. Then, the time when the contact angle was less than 90 ° was measured.

[Measurement result]
Sample 1 was simply a water-repellent film coated on epoxy, but deteriorated easily because there was no group that could be bonded to the side of the head. In addition, the samples coated with a primer as in Samples 2 to 4 can obtain a long-life product after wiping, but if the time until wiping is extended, the primer dries and the wiping effect Is not obtained at all. For this reason, when the primer is sandwiched between them, there is a problem in terms of manufacturing robustness.

  On the other hand, as in Samples 7 to 9, when the primer was applied directly to the epoxy containing glass filler, excellent alkaline ink immersion durability was obtained. In addition, the water repellent film to be applied has the same performance regardless of the amount applied, has no performance difference due to the application method dependency, and is excellent in manufacturing robustness.

  And when the coating liquid which is not a silane coupling agent like the sample 5 was used, water-repellent property disappeared easily by ink immersion. In Sample 6, the water-repellent sheet peeled off in 100 hours. Therefore, it turns out that it is effective to use a silane coupling agent.

(Experiment 2A)
A continuous drive test was conducted with a head (hereinafter referred to as sample 10) in which four modules without a water repellent film were connected (hereinafter referred to as sample 10) and the head prepared in experiment 1 above (sample 8). evaluated. Note that four modules were connected and the gap between the modules was adjusted to 300 μm.

  In the continuous drive test, (1) all nozzles are printed with a length of 150 mm, (2) the nozzle surface is wiped with a polyester terephthalate (PET) microfiber cloth moistened with a cleaning solution (olphine 1 wt%, water 99 wt%), As one cycle, 800 cycles were performed per day, and the progress was observed. The results observed up to 9 days are shown in Table 2 of FIG.

[result]
The head subjected to the side gap water repellency lasts for a long time without ink stains, which is presumed to have water repellency. However, the contact angle of ink is about 80 ° and the cleaning liquid is about 70 °, and even if there is a gap, the ink or the cleaning liquid theoretically enters. For this reason, it is estimated that every time the wet ultrafine fiber cloth passes through the gap, the liquid gradually enters and the dirt accumulates. Even with a head having water repellency, once dirt is deposited, a large amount of ink dirt immediately fills the gap. For this reason, it can be determined that it is not sufficient to maintain the head in this manner in a situation where the usage frequency is high.

(Experiment 2B)
Next, a cleaning liquid (olphine 1 wt% / water 99 wt%) was sprayed into the head every 6 days when dirt was generated to fill the gap, and then the gap was cleaned by sucking the gap with a dry PET microfiber cloth. . The results observed up to 18 days are shown in Table 3 in FIG.

[result]
In the sample 8, the dirt in the gap that entered could be sucked out and kept clean at all times. On the other hand, in sample 10, the first gap cleaning was effective, but the second gap cleaning was hardly effective.

(Experiment 2C)
In the sample 8 of Experiment 2B, dirt is likely to accumulate, and clearance cleaning is to be performed in a state where dirt is likely to accumulate. Therefore, it was considered that if the sample 10 was cleaned every other day, the cleanliness of the gap could be maintained as in the case of the sample 8, and the gap cleaning cleaning described in Experiment 2B was performed every other day.

[result]
Even though the frequency of gap cleaning was increased in sample 10, the ink adhesion stains accumulated on the 12th day. In the sample 8 of Experiment 2B, when the washed liquid is absorbed, the surface is completely absorbed because of water repellency. This is probably because the rest occurs.

(Experiment 2D)
Next, an experiment similar to Experiment 2B was performed using the head of Sample 5. The results observed for up to 30 days are shown in Table 4 in FIG.

[result]
It can be seen that if a water repellent film is provided in the gap as in Sample 5, good gap cleanliness can be maintained as compared to Sample 1 of Experiment 2B. In a line head that is used infrequently, it is considered that a good dirt removal function can be maintained even if the sample 5 is used if clearance cleaning is performed.

  On the other hand, when the gap cleaning operation is repeatedly performed, the clean maintenance mechanism of sample 5 has deteriorated. When the head was removed, the presence or absence of the water-repellent film could not be visually confirmed with the film using the silane coupling agent of Sample 8, but when the water repellency was confirmed by dripping water, the water repellency was maintained. . On the other hand, since the film of Sample 5 has a thick water-repellent film, the presence or absence of the water-repellent film can be visually confirmed, but it was confirmed that the water-repellent film was locally peeled off.

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 12 ... Paper feed part, 14 ... Processing liquid provision part, 16 ... Drawing part, 18 ... Drying part, 20 ... Fixing part, 22 ... Discharge part, 24 ... Recording medium, 70 ... Drawing drum, 72 ... Inkjet head, 72A ... Nozzle surface, 72-i ... Head module, 160 ... Gap, 202 ... Side (side of head module), 300 ... Gap ink suction mechanism, 302 ... Jet nozzle, 304 ... Fiber cloth pressing part, 304a ... Textile cloth, 306 ... Stand

Claims (10)

A maintenance method for a liquid discharge head in which a plurality of head modules each having a nozzle surface on which a plurality of nozzles for discharging liquid are arranged are connected,
On the side surface of the head module facing the adjacent head module with a gap, it has a water repellent film coated with a water repellent material containing fluorine,
A maintenance method for a liquid ejection head, comprising: a step of injecting a cleaning liquid into the gap; and a step of sucking out the cleaning liquid in the gap. The side surface of the head module is made of a plastic material containing glass filler,
2. The maintenance method for a liquid discharge head according to claim 1, wherein the water-repellent film is obtained by applying a humidified fluorine-based silane coupling agent terminated with a methoxy group on the plastic material containing the glass filler. . The step of causing the cleaning liquid to enter the gap causes the cleaning liquid to enter the gap by spraying the cleaning liquid with an injection nozzle,
3. The maintenance method for a liquid discharge head according to claim 1, wherein the step of sucking the cleaning liquid in the gap includes sucking the cleaning liquid with a sucking member.   The method of maintaining a liquid discharge head according to claim 3, wherein the suction member is a fiber cloth.   5. The maintenance method for a liquid discharge head according to claim 3, wherein the fiber cloth is a fiber cloth made of polyethylene terephthalate resin.   6. The maintenance method for a liquid discharge head according to claim 3, wherein the step of sucking out the cleaning liquid in the gap further sucks the cleaning liquid with a suction nozzle.   7. The maintenance method for a liquid discharge head according to claim 1, wherein the step of causing the cleaning liquid to enter the gap and the step of sucking the cleaning liquid in the gap are performed at regular intervals.   The liquid discharge head maintenance method according to claim 1, wherein the application of the water repellent material is performed twice or more.   9. The maintenance method for a liquid discharge head according to claim 1, wherein the water repellent film is formed on an entire surface of the side surface. 10. A liquid discharge head in which a plurality of head modules each having a nozzle surface on which a plurality of nozzles for discharging liquid are arranged are connected,
The side surface of the head module facing the adjacent head module through a gap is made of a plastic material containing glass filler, and the fluorine-based silane coupling agent terminated with a methoxy group on the plastic material containing glass filler. A liquid discharge head having a water-repellent film coated and moistened.

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