JP2016135584A - Liquid discharging head, liquid discharging unit, and device to discharge liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent liquid repellency from being degraded with abrasion of a liquid repellent film caused by repetition of wiping operations.SOLUTION: A liquid discharge head includes a nozzle plate 1 including a nozzle substrate 40 on which a plurality of nozzle holes 41 are formed serving as a nozzle 4 through which the liquid is discharged, and a liquid repellency film 42 is formed on the side of a discharging surface of the nozzle substrate 40. A plurality of dimples 43 are formed on the surface of the nozzle substrate 40. A liquid repellent material, which is a compound having a perfluoropolyether (PFPE) skeleton in its molecule forming the liquid repellent film 42, is held inside the dimple 43 in a flowable manner.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a liquid discharge head, a liquid discharge unit, and an apparatus for discharging liquid.

  A nozzle plate of a liquid discharge head (also referred to as a droplet discharge head) that discharges a liquid has a liquid repellent film formed on the discharge surface side in order to perform stable discharge.

  For example, a liquid repellent material for forming a liquid repellent film is known which uses a compound having a perfluoropolyether (PFPE) skeleton in the molecule (Patent Document 1).

  In addition, a water repellent film is formed by forming irregularities on the discharge surface side of the nozzle base material (Patent Document 2), and the surface roughness of the area near the nozzle holes on the discharge surface of the nozzle base material What is made smaller than surface roughness (patent document 3) etc. is known.

JP 2013-237259 A International Publication No. 99/15337 JP 2011-194668 A

  By the way, in an apparatus for ejecting liquid using a liquid ejection head, a wiping operation for wiping the ejection surface with a blade is performed in order to maintain and recover the ejection performance of the liquid ejection head.

  Therefore, there is a problem that the liquid repellency film is worn by the repetition of the wiping operation and the liquid repellency is lowered.

  The present invention has been made in view of the above problems, and an object thereof is to suppress a decrease in liquid repellency over time.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
Including a nozzle base material in which a plurality of nozzle holes serving as nozzles for discharging liquid are formed;
A nozzle plate having a liquid repellent film formed on the discharge surface side of the nozzle substrate;
A plurality of depressions are formed on the surface of the nozzle substrate,
The liquid repellent material forming the liquid repellent film is held in a fluid state inside the recess.

  According to the present invention, it is possible to suppress a decrease in liquid repellency over time.

FIG. 3 is an external perspective view illustrating an example of a liquid discharge head according to the present invention. FIG. 2 is a cross-sectional explanatory diagram in a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction along the line AA in FIG. 1. It is a cross-sectional explanatory drawing of the nozzle arrangement direction (liquid chamber short direction) along the BB line of FIG. It is plane explanatory drawing of the nozzle plate in 1st Embodiment of this invention. It is an expanded sectional explanatory view which follows the CC line of FIG. It is a plane explanatory view of the nozzle base material of the nozzle plate. It is an expanded sectional explanatory view which follows the DD line | wire of FIG. It is a plane explanatory drawing used for description of the hollow formation area of the nozzle base material. It is sectional explanatory drawing with which it uses for description of an effect | action of the embodiment. It is explanatory drawing of the surface on the opposite side to the discharge surface of a nozzle plate with which it uses for description of an example of the determination method of whether the liquid repellent material which forms a liquid repellent film is hold | maintained in the state which has fluidity | liquidity. It is sectional explanatory drawing which follows the EE line | wire of FIG. It is sectional explanatory drawing in alignment with the FF line of FIG. It is explanatory drawing of an example of the manufacturing method of a nozzle plate. It is explanatory drawing with which it uses for description of the dimple rank in an Example and a comparative example. It is explanatory drawing with which it uses for description of an Example and a comparative example. It is explanatory drawing with which it uses for description of the wiper member used for measurement of wiping tolerance. It is explanatory drawing of an example of the measuring method of the ink drawing time of the nozzle plate after wiping. It is a section explanatory view of a nozzle plate in a 2nd embodiment of the present invention. It is plane explanatory drawing of the nozzle plate in 3rd Embodiment of this invention. It is principal part plane explanatory drawing of an example of the apparatus which discharges the liquid which concerns on this invention. It is principal part side explanatory drawing of the apparatus. It is principal part plane explanatory drawing of the other example of the liquid discharge unit which concerns on this invention. It is front explanatory drawing of the further another example of the liquid discharge unit which concerns on this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of a liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 1 is a perspective explanatory view of the head, FIG. 2 is a cross-sectional explanatory view in a direction (longitudinal direction of the liquid chamber) orthogonal to the nozzle arrangement direction along the line AA in FIG. 1, and FIG. It is sectional explanatory drawing of the nozzle arrangement direction (liquid chamber short direction) in alignment with a line.

  In this liquid discharge head, a nozzle plate 1, a flow path plate 2, and a vibration plate member 3 as a wall surface member are laminated and joined. And the piezoelectric actuator 11 which displaces the diaphragm member 3 and the frame member 20 as a common liquid chamber member are provided.

  The nozzle plate 1, the flow channel plate 2, and the vibration plate member 3 form an individual flow channel 5 through which a plurality of nozzles 4 that discharge liquid communicate. When the nozzle 4 side is the downstream side, the individual flow path 5 communicates with the individual liquid chamber 6 through which the nozzle 4 communicates from the downstream side, the fluid resistance portion 7 that supplies liquid to the individual liquid chamber 6, and the fluid resistance portion 7. It is comprised with the liquid introduction part 8. FIG.

  Then, the liquid is introduced into the individual flow path 5 from the common liquid chamber 10 as the common flow path of the frame member 20 through the introduction port portion (supply port) 9 formed in the diaphragm member 3, and the liquid introduction portion 8, the fluid resistance The liquid is supplied to the individual liquid chamber 6 through the section 7. Note that a filter may be provided at the inlet 9.

  Here, the nozzle plate 1 is formed by forming a nozzle hole that becomes the nozzle 4 by press working on a SUS substrate that becomes a nozzle base material, and a liquid-repellent film is provided on the discharge side surface as described later.

  The flow path plate 2 forms a penetrating part (or a groove part) that forms the individual flow path 5 such as the individual liquid chamber 6, the fluid resistance part 7, and the liquid introduction part 8 by etching the SUS substrate. .

  The diaphragm member 3 is a wall surface member that forms the wall surface of the individual liquid chamber 6 of the flow path plate 2. The diaphragm member 3 has a three-layer structure (may be one layer, two layers, four layers or more). When the flow path plate 2 side is the first layer, a deformable vibration region (vibration plate) 30 is formed in a portion corresponding to the individual liquid chamber 6 in the first layer.

  The diaphragm member 3 is formed from a nickel (Ni) metal plate and is manufactured by an electroforming method (electroforming). Not limited to this, other metal members, resin members, laminated members of resin layers and metal layers, and the like can be used.

  A piezoelectric actuator 11 including an electromechanical conversion element as a driving means (actuator means, pressure generating means) for deforming the vibration region 30 of the diaphragm member 3 on the opposite side of the diaphragm member 3 from the individual liquid chamber 6. Is arranged.

  The piezoelectric actuator 11 has a plurality of laminated piezoelectric members 12 bonded with adhesive on a base member 13, and the piezoelectric member 12 is grooved by half-cut dicing to have a required number of piezoelectric members 12. Columnar piezoelectric elements (piezoelectric columns) 12A and 12B are formed in a comb shape at predetermined intervals.

  The piezoelectric elements 12A and 12B of the piezoelectric member 12 are the same, but are a piezoelectric element 12A that is driven by giving a drive waveform and a piezoelectric element 12B that is used as a mere support without giving a drive waveform.

  The piezoelectric element 12 </ b> A is joined to a convex portion 30 a that is an island-shaped thick portion formed in the vibration region 30 of the diaphragm member 3. Further, the piezoelectric element 12 </ b> B is joined to the convex portion 30 b which is a thick portion of the diaphragm member 3.

  This piezoelectric member 12 is formed by alternately laminating piezoelectric layers and internal electrodes, and each internal electrode is pulled out to the end face to be provided with an external electrode, and can be used to supply a drive signal to the external electrode of the drive column 12A. An FPC 15 as a flexible wiring member having flexibility is connected.

  The frame member 20 is formed by injection molding using, for example, epoxy resin or polyphenylene sulfite, which is a thermoplastic resin, and a common liquid chamber 10 to which liquid is supplied from a head tank or a liquid cartridge is formed.

  In the liquid discharge head configured as described above, for example, by lowering the voltage applied to the piezoelectric element 12A from the reference potential, the piezoelectric element 12A contracts, and the vibration region 30 of the vibration plate member 3 descends, so that the individual liquid chamber 6 As the volume expands, the liquid flows into the individual liquid chamber 6.

  Thereafter, the voltage applied to the piezoelectric element 12A is increased to extend the piezoelectric element 12A in the stacking direction, and the vibration region 30 of the diaphragm member 3 is deformed in the nozzle 4 direction to contract the volume of the individual liquid chamber 6. Thereby, the liquid in the individual liquid chamber 6 is pressurized, and the liquid is ejected (injected) from the nozzle 4.

  Then, by returning the voltage applied to the piezoelectric element 12A to the reference potential, the vibration region 30 of the diaphragm member 3 is restored to the initial position, and the individual liquid chamber 6 expands to generate a negative pressure. The liquid is filled into the individual liquid chamber 6 from the liquid chamber 10. Therefore, after the vibration of the meniscus surface of the nozzle 4 is attenuated and stabilized, the operation proceeds to the next droplet discharge.

  Note that the driving method of the head is not limited to the above example (pulling-pushing), and it is also possible to perform striking or pushing depending on the direction to which the driving waveform is given.

  Next, a first embodiment of the present invention will be described with reference to FIGS. 4 is an explanatory plan view of the nozzle plate in the same embodiment, FIG. 5 is an enlarged sectional explanatory view taken along the line CC of FIG. 4, FIG. 6 is an explanatory plan view of the nozzle substrate of the nozzle plate, and FIG. 6 is an enlarged cross-sectional explanatory view taken along line DD, and FIG. 8 is an explanatory plan view for explaining a recess formation region of the nozzle base material.

  The nozzle plate 1 has a nozzle base material 40 in which a plurality of nozzle holes 41 serving as nozzles 4 for discharging liquid are formed, and a liquid repellent film 42 is formed on the discharge surface 40 a side of the nozzle base material 40. .

  The nozzle base material 40 uses a metal plate such as a SUS substrate, forms a nozzle hole 41 by pressing, and is flattened by polishing. The cross-sectional shape of the nozzle hole 41 is not particularly limited.

For example, the nozzle substrate 40 may be made of Al, Bi, Cr, InSn, ITO, Nb, Nb ₂ O ₅ , NiCr, Si, SiO ₂ , Sn, Ta ₂ O ₅ , Ti, W, ZAO (other than the SUS substrate). ZnO + Al ₂ O ₃ ), Zn, or a film formed of these on a substrate can be used.

  The liquid repellent film 42 is formed on the discharge surface 40 a of the nozzle substrate 40 using a liquid repellent material that is a compound having a perfluoropolyether (PFPE) skeleton in the molecule.

  Here, a plurality of depressions (hereinafter referred to as “dimples”) 43 are formed in the discharge surface 40 a of the nozzle base material 40. In each figure, the arrangement of the dimples 43 is shown in a simplified manner for the sake of simplicity, but a large number of dimples 43 are formed and arranged around the nozzle row in which the plurality of nozzles 4 are arranged.

  The dimple 43 is larger than the hole diameter of the nozzle hole 41. The wall surface of the dimple 43 is preferably curved. Further, as shown in FIG. 8, the dimple 43 is formed in a region 40 c excluding the region 40 b around the nozzle hole 41. Specifically, the dimple 43 is formed at a position at least 150 μm away from the center of the nozzle hole 41. Further, the surface roughness Ra of the nozzle base material 40 due to the formation of the dimples 43 is set to 0.1 μm or less.

  A liquid repellent material such as a liquid repellent material, which is a compound having a perfluoropolyether (PFPE) skeleton in its molecule, is applied to the discharge surface 40a of the nozzle substrate 40 to form a liquid repellent film 42. .

  At this time, the liquid repellent material forming the liquid repellent film 42 is held in the dimple 43 in a fluid state.

  That is, in the dimple 43, the molecules of the liquid repellent film 42 are bonded to the nozzle base 40 on the interface side with the nozzle base 40, but are located outside the interface with the nozzle base 40 (liquid repellent). The molecules are in a free state (on the surface side of the film 42, between the surface of the liquid repellent film 42 and the interface between the nozzle substrate 40). The “interface with the nozzle base material 40” means the interface with the base layer when the nozzle base material 40 includes a base layer, as will be described in the following embodiments.

  Next, the operation of this embodiment will be described with reference to FIG. FIG. 9 is a cross-sectional explanatory view for explaining the same.

  In this apparatus for ejecting liquid using the liquid ejection head, in order to maintain and recover the performance of the liquid ejection head, a wiper member 483, which is a wiping member made of an elastic member, is used for the nozzle surface (here, the surface of the liquid repellent film 42). A wiping operation for wiping off is performed.

  At this time, as shown in FIG. 9, the wiper member 483 enters the dimple 43, so that the liquid repellent material of the liquid repellent film 42 held with fluidity inside the dimple 43 is scraped out.

  Therefore, even when the liquid repellent film 42 around the nozzle 4 is thinned or peeled off by the wiping operation, the liquid repellent material scraped out from the dimple 43 moves around the nozzle 4 to recover the liquid repellent film 42. .

  As a result, it is possible to suppress a decrease in the liquid repellency of the liquid repellent film over time associated with the wiping operation and maintain the liquid repellency over a long period of time.

  Here, a method of determining (discriminating) whether or not the liquid repellent material that forms the liquid repellent film 42 on the surface of the nozzle plate 1 is held in a fluid state will be described with reference to FIGS. . 10 is an explanatory view of the surface opposite to the discharge surface of the nozzle plate used for the same description, FIG. 11 is a cross-sectional explanatory view taken along line EE in FIG. 10, and FIG. 12 is a cross-sectional view taken along line FF in FIG. It is explanatory drawing.

  First, in a state where the nozzle plate 1 is not heated, a line 500 is drawn across the nozzle hole 41 with a felt pen on the surface 40b opposite to the discharge surface 40a of the nozzle plate 1. At this time, the liquid-repellent film 42 is formed on the ejection surface 40a side, but at this point, the liquid-repellent film 40 does not move and adhere to the surface 40b opposite to the ejection surface 40a. As shown in FIG. 11, the line 500 can also be drawn around the nozzle hole 41.

  Next, the nozzle plate 1 is heated at 120 ° C. for 1 hour. At this time, if the liquid repellent material of the liquid repellent film 42 is in a fluid state, the liquid repellent material on the discharge surface 40a moves into the nozzle hole 41 by heating as shown in FIG. As a result, part of the liquid repellent material also adheres to the opposite surface 40b side.

  Therefore, when the line 501 is drawn across the nozzle hole 41 with a felt pen on the surface 40b opposite to the discharge surface 40a with respect to the heated nozzle plate 1, as shown in FIG. 10 and FIG. 501 is not pulled near the nozzle hole 41. That is, the liquid repellent material flows and adheres to the vicinity of the nozzle hole 41 on the opposite surface 40b to the discharge surface 40a, whereby the ink is repelled and the line 501 is interrupted in this region 502.

  With the above method, it is possible to determine whether the liquid repellent material has fluidity.

  Next, an example of a nozzle plate manufacturing method will be described with reference to FIG. FIG. 13 is an explanatory diagram for explaining an example of the method.

  Here, an upstream process, a pretreatment process, a liquid repellent film forming process, a post-treatment process, and a downstream process are performed. In the following, a stainless steel plate will be described as an example of the nozzle base material 40, but the present invention is not limited to this.

-Upstream process-
The upstream process is a process of polishing the surface of the nozzle base material 40, that is, a discharge surface that is a surface for discharging a liquid.

  As a polishing method of the surface (surface on the discharge surface 40a side) of the nozzle base material 40 in which the nozzle holes 41 are formed, for example, a polyurethane pad is used in an ultra-precise swing type single-side polishing machine (CMP polishing apparatus). There is a method of polishing the surface of the nozzle substrate 40. Polishing is preferably performed by rotating the polyurethane pad at 1 to 20 rpm until the surface roughness Ra of the surface of the nozzle substrate 40 becomes 0.1 μm or less.

  The surface roughness Ra of the discharge surface of the nozzle substrate 40 can be measured according to JIS 0601. For example, the surface roughness Ra can be measured using a stylus type surface shape measuring device Dektak 150 (manufactured by ULVAC).

  In order to adjust the surface roughness Ra, for example, pressure when pressing the surface of the nozzle substrate 40 with a polyurethane pad, rotation speed when rotating the polyurethane pad (rpm: number of rotations per minute), polishing liquid It is possible to adjust by changing the flow rate, polishing time and the like.

  The dimple 43 is formed when a polishing process for polishing the discharge surface of the nozzle substrate 40 is performed.

-Pretreatment process-
A pre-processing process is a process of the nozzle base material 40 which grind | polished the surface, and is a process of ultrasonically cleaning. In addition to ultrasonic cleaning, wet cleaning such as scrub cleaning, shower cleaning (high pressure spray cleaning, ultrasonic shower cleaning), immersion cleaning (running water cleaning, jet cleaning, bubbling cleaning), and steam cleaning can also be performed.

-Film formation process of liquid repellent film-
The film forming process of the liquid repellent film 42 is as follows.

  First, a dip solution having PFPE for forming the liquid repellent film 42 is adjusted.

  Plasma treatment is performed on the surface of the nozzle substrate 40 after the pre-treatment, that is, the droplet ejection surface. In addition to the plasma treatment, it is also possible to perform dry cleaning such as vacuum cleaning (ion beam cleaning) and normal pressure cleaning (UV ozone cleaning, ice scrubber cleaning, laser cleaning).

  Thereafter, the adjusted dipping liquid is applied to the nozzle substrate 40 by a dipping method. After being left at room temperature (about 25 degrees), it is heated and subjected to ultrasonic cleaning for removing excess perfluoropolyether. By performing ultrasonic cleaning, excess PFPE is removed, and the thickness of the liquid repellent film 42 is preferably adjusted to a monomolecular layer level.

As the dip liquid for the liquid repellent film 42, a solution obtained by diluting a perfluoropolyether derivative to 1 wt% or less in a fluorine-based solvent can be used. The perfluoropolyether derivative preferably has a polar group at the terminal. Examples of the polar group herein include —OH, C═O, —COOH, —NH ₂ , —NO ₂ , —NH ₃ ⁺ , —CN, and the like.

  This polar group is bonded to the nozzle substrate or the base layer on the nozzle substrate.

  Examples of the fluorine-based solvent include hydrofluoroethers such as Novec (manufactured by Sumitomo 3M), Bertrell (manufactured by Dupont), and Galden (manufactured by Solvay Solexis).

  Further, the discharge surface of the nozzle substrate 40 is subjected to oxygen plasma treatment.

  For example, the liquid repellent film 42 may be formed by immersing the nozzle substrate 40 in a solution, pulling it up, and then naturally drying it in a room temperature environment, followed by heat treatment and fixing. The heating temperature and the heating time can be changed according to the purpose.

-Post-treatment process-
The post-treatment process is as follows. In order to protect the surface of the liquid repellent film 42, the discharge surface is covered with a laminate material (lamination is performed), and the back surface of the nozzle substrate 40, that is, the surface opposite to the discharge surface is subjected to plasma treatment.

-Downstream process-
A downstream process is a process performed as needed, and a downstream process is a process which adhere | attaches the nozzle plate 1 and the member which comprises a liquid chamber, etc., and strengthens the adhesive force by heating.

  The nozzle plate 1 obtained in the post-processing step is bonded using a flow path plate and a low-temperature curable epoxy adhesive or the like in a downstream bonding step. In order to maintain the adhesive state for a long period of time, it is preferable to bond by heating and pressure bonding.

  Next, the detail of the manufacturing method of the nozzle base material which comprises a nozzle plate is demonstrated.

  The discharge surface side surface of the nozzle base material 40 is polished using a polyurethane pad by, for example, an ultraprecision swing type single-side polishing machine (CMP polishing apparatus). When polishing, it is preferable to polish while pressing with a pressure of 5 to 20 kPa. Further, when polishing is performed, it is preferable to perform polishing together with a polishing liquid prepared by adding a small amount of particles such as alumina to a slurry obtained by diluting an abrasive slurry with pure water.

  Polishing is preferably performed by rotating the polyurethane pad at 1 to 20 rpm until the surface roughness Ra of the nozzle substrate 40 becomes 0.1 μm or less. By performing such polishing, innumerable dimples 43 can be formed on the polished surface of the nozzle substrate 40 after polishing.

  Here, the dimple 43 is a recess having a diameter of 80 to 120 μm and a depth of 2 to 4 μm, for example. It is preferable that the dimple 43 has a gentle slope on the inner wall surface. The number of dimples 43 to be formed can be controlled by the amount of particles mixed in the polishing liquid and the polishing time.

  The particles to be added preferably have an average particle size of about 90 to 250 μm. For example, ceramic abrasives such as alumina particles, silicon carbide particles, and zircon particles can be used.

  As described above, the surface roughness Ra can be measured according to JIS0601, and can be measured using, for example, a stylus type surface shape measuring apparatus.

  Next, the wiping resistance in specific examples and comparative examples will be described with reference to FIGS. FIG. 14 is an explanatory diagram for explaining the dimple rank, and FIG. 15 is an explanatory diagram for explaining examples and comparative examples.

  First, the nozzle plates 1 were ranked according to the number of dimples 43 formed on the nozzle substrate 40. Here, the surface of the nozzle substrate 40 is observed in a dark field with a metal microscope, and the number of minute concave portions to be highlighted is counted. At this time, since the size of the dimple 43 is 80 to 120 μm, the difference from the nozzle hole 41 and scratches can be easily determined.

  And as shown in FIG. 14, when the nozzle hole density (a) which is the number of nozzle holes in a specific length and all the dimples 43 in the range of 150 μm to 10 mm from the nozzle row are projected in the nozzle row direction Based on the magnitude relationship of the dimple density (b), which is the number of dimples in a specific length in the nozzle row direction, the following ranks (dimple ranks) 0 to 5 were ranked.

Rank 0: (b) = 0
Rank 1: 0 <b <2a
Rank 2: 2a <b <2.5a
Rank 3: 2.5a <b <3.3a
Rank 4: 3.3a <b <5a
Rank 5: b> 5a

  In the example of FIG. 14, since (a) = 8 and (b) = 14, the rank is 1.

  Here, as shown in FIG. 15, the nozzle base materials of Examples 1 to 3 and Comparative Examples 1 to 3 were changed by changing the content of alumina particles contained in the polishing liquid when polishing the surface of the nozzle base material 40. 40 was obtained. The particle diameter of the alumina particles was 90 to 250 μm.

  At this time, the surface roughness Ra of the flat portion other than the dimple 43, the presence / absence of the dimple 43, and the dimple rank in Examples 1 to 3 and Comparative Examples 1 to 3 were as shown in FIG.

  From Examples 1, 2, and 3 it can be seen that the dimple rank increases and the number of dimples increases as the content of alumina particles in the polishing liquid used for surface polishing increases.

  The contents of alumina particles in Comparative Examples 2 and 3 are the same as in Example 2, but no dimples are formed. In Comparative Examples 2 and 3, since the polishing time is shorter than that in Example 2, the surface of the nozzle base material is not sufficiently flattened, and the surface is simply rough (rough surface). Dimples are not formed.

  Further, although not clearly shown in FIG. 13, when the surface roughness Ra of the polished surface is larger than 0.1, it is confirmed that a hollow dimple having a diameter of 80 to 120 μm and a depth of 2 to 4 μm is not formed. It was done. Therefore, the dimple 43 is formed when the surface roughness Ra of the polished surface is 0 or 1 μm or less.

  Then, the wiping durability life was evaluated by the number of wiping rubbed until the ink draw-out time was 50 sec or more. This means that the longer the wiping frequency is, the longer the wiping durability life is. The evaluation results (number of wiping operations) are shown in FIG.

  As can be seen from the evaluation results in FIG. 15, in Comparative Examples 1 to 3, the number of wipings is 2000 times or less, and the ink withdrawal time is 50 seconds or more. On the other hand, in Examples 1 to 3, even if the number of wipings exceeds 2000, the ink draw-out time does not become 50 seconds or more, and the wiping durability life is long.

  Here, a method of measuring the number of times of wiping until the ink closing time reaches 50 sec will be described with reference to FIG. FIG. 16 is an explanatory diagram for explaining the wiper member.

  First, an EPDM (ethylene propylene rubber) rubber blade having a thickness of 1.2 mm and a width of 30 mm is fixed at one end by a fixing jig 602 in a state where it is freely bent by 7 mm out of a length of 20 mm as shown in FIG. Thus, the wiper member 601 was obtained.

  Then, the wiper member 601 was wiped at a speed of 100 mm / sec while being bent in a state where the wiper member 601 interfered with the discharge surface of the nozzle plate 1 by 2 mm (/ 7 mm). In addition, as shown in FIG. 16, the “2 mm (/ 7 mm) interference state” means the length of the portion of the wiper member 601 that touches the discharge surface of the nozzle plate 1 when the length of the flexing portion is 7 mm. Represents a state of 2 mm.

  At this time, the wiper member 601 is lowered to a position in contact with the discharge surface, and after wiping the discharge surface, lifted and separated from the discharge surface, returned to the wiping start position, and lowered again to a position in contact with the discharge surface. Repeated.

  Next, a method for measuring the ink drawing time of the nozzle plate 1 after wiping will be described with reference to FIG.

  As shown in FIGS. 17 (a) and 17 (b), half of the nozzle plate 1 is immersed in the ink 610 and pulled up at a speed of 100 mm / sec as shown in FIG. 17 (c). Immediately after the pulling up (t = 0), the ink 610 is drawn from the ejection surface as shown in FIG. 4D, and the ink 610 covering the ejection surface is at the time t = 0 as shown in FIG. The time required to reach 10% of the area was measured, and this was defined as ink drawing time.

  As described above, the ink removal time is measured using the nozzle plate 1 after wiping. As described above, the number of times of wiping necessary to obtain the nozzle plate 1 with an ink drawing time of 50 seconds was measured.

  Here, the composition of the ink used for the measurement of the ink closing time is as follows.

  The composition having the following formulation was stirred and dissolved at 60 ° C., allowed to cool at room temperature, and then adjusted with a 10% aqueous solution of lithium hydroxide so that the pH would be 9-10. The ink 610 was produced by filtering through a filter.

(Ink 610)
C. I. Direct Black 168 3% by mass
2-pyrrolidone 3% by mass
Diethylene glycol 4% by mass
Glycerin 1% by mass
Alkyl ether carboxylate surfactant ECTD-3NEX 0.1% by mass (surfactant manufactured by Nippon Surfactant Kogyo Kagaku)
Nonipol 400 (Sanyo Kasei surfactant) 0.5% by mass
Sun eye bag P-100 (San-ai Petroleum antiseptic and fungicide) 0.4% by mass
Ion exchange water

  The static surface tension of this ink 610 was 25.1 mN / m 2.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 18 is a cross-sectional explanatory view of the nozzle plate in the same embodiment.

In the present embodiment, the nozzle base material 40 is configured by a base material 51 and a base film (base layer) 52 formed on the surface of the base material 51. The base film 52 is a film that enhances the bonding force between the base material 51 and the liquid repellent film 42, and for example, a SiO ₂ film can be used. The interface of the nozzle substrate described above corresponds to the interface between the base film 52 and the liquid repellent film 42 in this embodiment.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 19 is an explanatory plan view of the nozzle plate in the same embodiment.

  In the present embodiment, the nozzle base 40 is formed with a total of four nozzle rows including nozzle hole rows 41A1 and 41B1 in which a plurality of nozzle holes 41 are arranged, and nozzle hole rows 41A2 and 41B2. In order to simplify the drawing, the nozzle hole rows are shown by lines. In this configuration, four nozzle rows are arranged on the nozzle plate corresponding to the nozzle hole rows.

  Here, the space between the nozzle hole row 41B1 and the nozzle row 41A2 is formed wider than the space between the nozzle hole rows 41A1 and 41B1 and between the nozzle rows 41A2 and 41B2.

  In the present embodiment, the dimples 43 are also formed between the nozzle hole row 41B1 and the nozzle row 41A2.

  Thereby, the liquid repellent material held in the dimple 43 between the nozzle hole row 41B1 and the nozzle hole row 41A2 is supplied to the periphery of the nozzle 4 on the nozzle hole row 41B1 side or the nozzle hole row 41A side (depending on the wiping direction). Is done.

  In this way, by forming dimples between a plurality of nozzle rows (nozzle hole rows), liquid repellent material can be replenished around the nozzles from a location closer to the nozzles, and the liquid repellency can be maintained over a longer period of time. Can be maintained.

  Next, an example of an apparatus for ejecting liquid according to the present invention will be described with reference to FIGS. 20 is an explanatory plan view of the main part of the apparatus, and FIG. 21 is an explanatory side view of the main part of the apparatus.

  This apparatus is a serial type apparatus, and the carriage 403 reciprocates in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 spans the left and right side plates 491A and 491B and holds the carriage 403 so as to be movable. The carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 spanned between the driving pulley 406 and the driven pulley 407.

  The carriage 403 is equipped with a liquid discharge unit 440 in which a liquid discharge head 404 and a head tank 441 according to the present invention including a nozzle plate according to the present invention are integrated.

  The liquid discharge head 404 of the liquid discharge unit 440 discharges, for example, yellow (Y), cyan (C), magenta (M), and black (K) liquids. The liquid ejection head 404 is mounted with a nozzle row composed of a plurality of nozzles arranged in the sub-scanning direction orthogonal to the main scanning direction, and the ejection direction facing downward.

  The liquid stored in the liquid cartridge 450 is supplied to the head tank 441 by the supply mechanism 494 for supplying the liquid stored outside the liquid discharge head 404 to the liquid discharge head 404.

  The supply mechanism 494 includes a cartridge holder 451 that is a filling unit for mounting the liquid cartridge 450, a tube 456, a liquid feeding unit 452 including a liquid feeding pump, and the like. The liquid cartridge 450 is detachably attached to the cartridge holder 451. Liquid is fed from the liquid cartridge 450 to the head tank 441 by the liquid feeding unit 452 via the tube 456.

  This apparatus includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412 serving as transport means, and a sub-scanning motor 416 for driving the transport belt 412.

  The conveyance belt 412 adsorbs the paper 410 and conveys it at a position facing the liquid ejection head 404. The transport belt 412 is an endless belt and is stretched between the transport roller 413 and the tension roller 414. The adsorption can be performed by electrostatic adsorption or air suction.

  The transport belt 412 rotates in the sub-scanning direction when the transport roller 413 is rotationally driven by the sub-scanning motor 416 via the timing belt 417 and the timing pulley 418.

  Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 that performs maintenance / recovery of the liquid ejection head 404 is disposed on the side of the transport belt 412.

  The maintenance / recovery mechanism 420 includes, for example, a cap member 421 for capping the nozzle surface (surface on which the nozzle is formed) of the liquid ejection head 404, a wiper member 422 for wiping the nozzle surface, and the like.

  The main scanning movement mechanism 493, the supply mechanism 494, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including the side plates 491A and 491B and the back plate 491C.

  In this apparatus configured as described above, the paper 410 is fed and sucked onto the transport belt 412, and the paper 410 is transported in the sub-scanning direction by the circular movement of the transport belt 412.

  Therefore, the liquid ejection head 404 is driven in accordance with the image signal while moving the carriage 403 in the main scanning direction, thereby ejecting liquid onto the stopped paper 410 to form an image.

  Thus, since this apparatus includes the liquid ejection head according to the present invention, a high-quality image can be stably formed.

  Next, another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 22 is an explanatory plan view of the main part of the unit.

  This liquid discharge unit includes a housing part composed of side plates 491A and 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid among the members constituting the liquid discharge device. The discharge head 404 is configured.

  Note that a liquid discharge unit in which at least one of the above-described maintenance and recovery mechanism 420 and the supply mechanism 494 is further attached to, for example, the side plate 491B of the liquid discharge unit may be configured.

  Next, still another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 23 is an explanatory front view of the unit.

  This liquid discharge unit includes a liquid discharge head 404 to which a flow path component 444 is attached, and a tube 456 connected to the flow path component 444.

  The flow path component 444 is disposed inside the cover 442. A head tank 441 may be included instead of the flow path component 444. In addition, a connector 443 that is electrically connected to the liquid ejection head 404 is provided above the flow path component 444.

  In the present application, the “apparatus for discharging liquid” is an apparatus that includes a liquid discharge head or a liquid discharge unit and drives the liquid discharge head to discharge liquid. The apparatus for ejecting liquid includes not only an apparatus capable of ejecting liquid to an object to which liquid can adhere, but also an apparatus for ejecting liquid toward the air or liquid.

  This “apparatus for discharging liquid” may include means for feeding, transporting, and discharging a liquid to which liquid can adhere, as well as a pre-processing apparatus and a post-processing apparatus.

  For example, as a “liquid ejecting device”, an image forming device that forms an image on paper by ejecting ink, a powder is formed in layers to form a three-dimensional model (three-dimensional model) There is a three-dimensional modeling apparatus (three-dimensional modeling apparatus) that discharges a modeling liquid onto the powder layer.

  Further, the “apparatus for ejecting liquid” is not limited to an apparatus in which significant images such as characters and figures are visualized by the ejected liquid. For example, what forms a pattern etc. which does not have a meaning in itself, and what forms a three-dimensional image are also included.

  The above-mentioned “thing to which liquid can adhere” means that liquid can adhere even temporarily. The material to which “the liquid adheres” may be any material as long as the liquid can temporarily adhere, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics.

  “Liquid” also includes ink, treatment liquid, DNA sample, resist, pattern material, binder, modeling liquid, and the like.

  Further, the “device for ejecting liquid” includes both a serial type device that moves the liquid ejection head and a line type device that does not move the liquid ejection head, unless otherwise specified.

  In addition to the “device for discharging liquid”, a processing liquid coating apparatus for discharging a processing liquid onto a sheet for applying a processing liquid to the surface of the sheet for the purpose of modifying the surface of the sheet, or a raw material There is an injection granulator for granulating raw material fine particles by spraying a composition liquid dispersed in a solution through a nozzle.

  A “liquid ejection unit” is a unit in which functional parts and mechanisms are integrated with a liquid ejection head, and is an assembly of parts related to liquid ejection. For example, the “liquid discharge unit” includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, and a main scanning movement mechanism with a liquid discharge head.

  Here, the term “integrated” refers to, for example, a liquid discharge head, a functional component, and a mechanism that are fixed to each other by fastening, adhesion, engagement, etc., and one that is held movably with respect to the other. Including. Further, the liquid discharge head, the functional component, and the mechanism may be configured to be detachable from each other.

  For example, there is a liquid discharge unit in which a liquid discharge head and a head tank are integrated as in the liquid discharge unit 440 shown in FIG. Also, there are some in which the liquid discharge head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter may be added between the head tank and the liquid discharge head of these liquid discharge units.

  In addition, there is a liquid discharge unit in which a liquid discharge head and a carriage are integrated.

  In addition, there is a liquid discharge unit in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably on a guide member that forms a part of the scanning movement mechanism. Further, as shown in FIG. 22, there is a liquid discharge unit in which a liquid discharge head, a carriage, and a main scanning movement mechanism are integrated.

  Also, there is a liquid discharge unit in which a cap member that is a part of the maintenance / recovery mechanism is fixed to a carriage to which the liquid discharge head is attached, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. .

  Further, as shown in FIG. 23, as a liquid discharge unit, there is a unit in which a tube is connected to a liquid discharge head to which a head tank or a flow path component is attached, and the liquid discharge head and the supply mechanism are integrated. .

  The main scanning movement mechanism includes a guide member alone. The supply mechanism includes a single tube and a single loading unit.

  The “liquid discharge head” is not limited to the pressure generating means to be used. For example, in addition to the piezoelectric actuator as described in the above embodiment (a multilayer piezoelectric element may be used), a thermal actuator using an electrothermal conversion element such as a heating resistor, a diaphragm and a counter electrode are included. An electrostatic actuator or the like may be used.

  In addition, the terms “image formation”, “recording”, “printing”, “printing”, “printing”, “modeling” and the like in the terms of the present application are all synonymous.

DESCRIPTION OF SYMBOLS 1 Nozzle plate 2 Flow path plate 3 Vibration plate member 4 Nozzle 6 Individual liquid chamber 8 Liquid introduction part 10 Common liquid chamber 12 Piezoelectric member 20 Frame member 40 Nozzle base material 41 Nozzle hole 42 Liquid repellent film 43 Dimple (dent)
403 Carriage 404 Liquid discharge head 440 Liquid discharge unit

Claims (7)

Including a nozzle base material in which a plurality of nozzle holes serving as nozzles for discharging liquid are formed;
A nozzle plate having a liquid repellent film formed on the discharge surface side of the nozzle substrate;
A plurality of depressions are formed on the surface of the nozzle substrate,
A liquid ejection head, wherein the liquid repellent material forming the liquid repellent film is held in a fluid state inside the recess. The liquid discharge head according to claim 1, wherein the liquid repellent material forming the liquid repellent film is a compound having a perfluoropolyether (PFPE) skeleton in a molecule. The liquid ejection head according to claim 1, wherein the plurality of depressions of the nozzle base material are formed in a region excluding the periphery of the nozzle hole. 4. The liquid discharge head according to claim 1, wherein a surface of the nozzle base material has a base film serving as a base of the liquid repellent film. 5.   A liquid discharge unit comprising the liquid discharge head according to claim 1. A head tank for storing liquid to be supplied to the liquid discharge head, a carriage on which the liquid discharge head is mounted, a supply mechanism for supplying liquid to the liquid discharge head, a maintenance / recovery mechanism for maintaining and recovering the liquid discharge head, and the liquid 6. The liquid discharge unit according to claim 5, wherein the liquid discharge head is integrated with at least one of a main scanning movement mechanism that moves the discharge head in the main scanning direction.   An apparatus for ejecting liquid, comprising the liquid ejection head according to claim 1 or the liquid ejection unit according to claim 5 or 6.

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