JP4936738B2 - Liquid ejection head and image forming apparatus - Google Patents

Description

  The present invention relates to a liquid discharge head, a manufacturing method thereof, and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile, a copying apparatus, and a multifunction machine of these, for example, an ink jet recording apparatus is known. An ink jet recording apparatus uses a liquid discharge head as a recording head, and is a recording medium such as recording paper (hereinafter referred to as “paper”, but the material is not limited to paper, and the recording medium, transfer paper, transfer material, etc. In other words, recording is performed by ejecting ink droplets as a recording liquid onto the recording material) (image formation, printing, printing, printing, etc. are also synonymous).

  By the way, since the liquid ejection head performs recording by ejecting droplets from the nozzles, the shape and accuracy of the nozzles greatly affect the ejection characteristics of the ink droplets. Further, it is known that the characteristics of the surface of the nozzle forming member forming the nozzle holes also affect the ink droplet ejection characteristics. For example, if ink adheres to the periphery of the nozzle hole on the surface of the nozzle forming member and a non-uniform ink pool occurs, the ink droplet ejection direction is bent, the ink droplet size varies, or the ink droplet It is known that inconveniences such as unstable flight speed occur.

  Therefore, in general, in a liquid discharge head, an ink repellent layer (film), a water repellent layer, and the like are formed on the surface of the droplet discharge side.

For example, in Patent Document 1, a fluorine-based water repellent film is formed, in Patent Document 2, a water-repellent film such as hexamethyldisiloxane is formed by plasma polymerization, and in Patent Document 3, a fluororesin polymer film is formed. Alternatively, it is described that a water-repellent film of a silicone resin polymer film is formed.
JP 2001-232799 A JP 2003-72085 A JP 2003-72086 A

As a method for forming a water-repellent film, Patent Document 4 describes that the nozzle surface is immersed in a solution in which a water- and oil-repellent material is dissolved while maintaining a state in which gas is released from the back side of the nozzle toward the surface. A method is described in which the nozzle surface is separated from the solution while gas is released, and the water and oil repellent film is applied by leaving it.
Japanese Patent No. 3379119

  As described above, in a head using a fluororesin as the water repellent layer, specifically, a PTFE thin film is formed by subjecting a metal nozzle plate surface to eutectoid plating of Ni-PTFE and heat treatment. A forming method, a method of coating a surface of a nozzle plate (base material) made of metal or resin with a fluorine-based water repellent, and the like are employed.

  In the case of such a nozzle forming member using a fluororesin as a water-repellent layer, it is possible to provide a good water repellency (ink repellency) with a dye ink or pigment ink having a conventionally known surface tension exceeding 30 mN / m. .

  However, according to experiments by the present inventors, there is a problem that sufficient water repellency (ink repellency) does not manifest when using an ink with a low surface tension of 30 mN / m or less or an ink added with a fluorine compound. It was confirmed that there was.

  On the other hand, as described above, in a head using a silicone resin film as a water-repellent film, specifically, a method of vacuum-depositing a liquid silicone resin material, a method of forming a silicone oil by plasma polymerization, etc. Has been done.

  However, when these methods for forming a silicone resin film are used, it is necessary to perform a vacuum treatment at the time of film formation, resulting in large equipment and high cost. In vacuum deposition or plasma polymerization, the film formation time is long and the formed film is very thin, so that defects such as pinholes are likely to occur. In addition, it is difficult to increase the thickness of the silicone resin film by methods such as vacuum deposition and plasma polymerization, and the nozzle surface (droplet discharge side surface of the nozzle forming member) performed as a head recovery operation is sufficient for ink and ink. There is a problem that it is difficult to ensure the durability.

  Further, as described in Patent Document 4 described above, an ink repellent layer is formed on the surface of the nozzle plate by immersing the nozzle plate in a solution in which an ink repellent agent is dissolved in a state where gas is injected from the nozzle hole. In this method, bubbles are generated in the solution because it is immersed in the solution while the gas is jetted. If the solution is a type that cures at room temperature, the solution must be left in the atmosphere. Therefore, it is difficult to keep the liquid state, and there is a problem that the film thickness control of the ink repellent layer becomes impossible due to the viscosity change of the solution.

  Therefore, the inventor separately invented a method of forming a water-repellent layer by uniformly applying a liquid silicone resin only to a desired portion of the surface of the nozzle forming member using a dispenser. However, when the silicone resin layer formed by this method is filled with ink, the silicone resin layer is peeled off from the portion that touched the ink with the passage of time, the ink adhered to the surface of the nozzle forming member, and the meniscus formation. For this reason, it was confirmed that the silicone resin layer was easily peeled even by wiping.

  Therefore, the present invention has clarified the cause of the peeling of the silicone resin layer, and has completed the present invention.

The present invention has been made based on the above issues, and an object thereof is to improve the adhesion between the silicone resin and the nozzle substrate.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
In a liquid discharge head comprising a nozzle forming member in which a water repellent layer is formed on the surface of a droplet discharge side of a nozzle base material in which nozzle holes for discharging recording liquid droplets are formed,
A natural oxide film is formed on the droplet discharge side surface of the nozzle substrate,
A water repellent layer made of silicone resin is formed on the surface of the natural oxide film,
An oxide film thicker than the natural oxide film is formed on the inner wall surface of the nozzle hole of the nozzle base material .

An image forming apparatus according to the present invention includes the liquid ejection head according to the present invention.

According to the liquid discharge head of the present invention, a natural oxide film is formed on the surface of the nozzle substrate on the droplet discharge side, a water repellent layer made of a silicone resin is formed on the surface of the natural oxide film, and the nozzle base Since the inner wall surface of the nozzle hole has a thicker oxide film than the natural oxide film , the adhesion between the silicone resin and the nozzle substrate can be improved, and stable droplet ejection characteristics Is obtained.

According to the image forming apparatus of the present invention, since the liquid ejection head according to the present invention is provided, high water repellency is achieved and excellent droplet ejection characteristics can be obtained, so that a high quality image can be stably formed. Can do .

  Embodiments of the present invention will be described below with reference to the accompanying drawings. A first embodiment of a liquid discharge head according to the present invention will be described with reference to FIGS. 1 is an exploded perspective view of the head, FIG. 2 is a cross-sectional view of the head along the longitudinal direction of the liquid chamber, FIG. 3 is an enlarged view of the main part of FIG. 2, and FIGS. It is a section explanatory view showing a different example along a room transverse direction.

  The liquid discharge head includes, for example, a flow channel plate 1 formed of a single crystal silicon substrate, a vibration plate 2 bonded to the lower surface of the flow channel plate 1, and a nozzle that is a nozzle forming member bonded to the upper surface of the flow channel plate 1. The plate 3 and the nozzle 4 for ejecting ink droplets thereby communicate with the liquid chamber 6 via the pressurized liquid chamber 6, the fluid resistance portion 8, and the fluid resistance portion 7. The recording liquid (for example, ink) is supplied from the common liquid chamber 8 formed in the frame member 17 to be described later through the supply port 10 formed in the diaphragm 2.

  Then, on the outer side of the diaphragm 2 that forms the wall surface of the liquid chamber 6 (on the side opposite to the liquid chamber 6), corresponding to each pressurized liquid chamber 6, via a connecting portion 11 formed on the diaphragm 2. The upper end portion of the multilayer piezoelectric element 12 as pressure generating means is joined, and the lower end portion of the multilayer piezoelectric element 12 is joined and fixed to the support substrate 13. Note that the support substrate 13 may be divided for each row of the piezoelectric elements 12.

  The piezoelectric element 12 is formed by alternately stacking piezoelectric material layers 14 and internal electrodes 15a and 15b. In this case, the ink in the liquid chamber 6 may be pressurized using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 12, or the pressurized liquid chamber 6 using the displacement in the d31 direction as the piezoelectric direction of the piezoelectric element 12. It can also be configured to pressurize the inner ink.

  Further, the periphery of the flow path plate 1 and the vibration plate 2 is bonded and bonded to a frame member 17 formed by injection molding with, for example, epoxy resin or polyphenylene sulfite, and the frame member 17 and the support substrate 13 are bonded to a portion (not shown). They are fixed to each other with agents. The frame member 17 is formed with the above-described common liquid chamber 8 and a supply path (communication pipe) (not shown) for supplying recording liquid from the outside to the common liquid chamber 8. Further, it is connected to a recording liquid supply source such as a recording liquid cartridge (not shown).

  Further, an FPC cable 18 is connected to the piezoelectric element 12 by solder bonding, ACF (anisotropic conductive film) bonding or wire bonding in order to give a drive signal. The FPC cable 18 is selectively connected to each piezoelectric element 12. A drive circuit (driver IC) 19 for applying a drive waveform is mounted.

  Here, the flow path plate 1 is formed by anisotropically etching a single crystal silicon substrate having a crystal plane orientation (110), for example, with an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), so Groove portions constituting the through hole, the fluid resistance portion 7, the communication portion 9 and the like serving as the pressurized fluid chamber 6 are formed.

  The diaphragm 2 is formed from a nickel (Ni) metal plate, and is manufactured by an electroforming method (electroforming). In the diaphragm 2, a portion corresponding to the pressurized liquid chamber 6 is a thin portion for facilitating deformation, and a connecting portion 11 for joining to the piezoelectric element 12 is provided in the central portion.

  In the lateral direction of the liquid chamber (the direction in which the nozzles 4 are arranged), as shown in FIG. 4, a bi-pitch structure in which the piezoelectric elements 12 and the column portions 22 are alternately arranged can be used, or as shown in FIG. Thus, it can also be set as the normal pitch structure which does not provide the support | pillar part 22. FIG.

  The nozzle plate 3 is formed from a nickel (Ni) metal plate, and is manufactured by an electroforming method (electroforming). In this nozzle plate 3, nozzles 4 having a diameter of 10 to 35 μm are formed corresponding to the respective pressure chambers 6, and bonded to the flow path plate 1 with an adhesive. A water repellent layer formed of a silicone resin is provided on the droplet discharge side surface (surface in the discharge direction: discharge surface or surface opposite to the liquid chamber 6 side) of the nozzle plate 3 as will be described later.

  In the liquid ejection head configured as described above, for example, when driven by a punching method, a drive pulse voltage of 20 to 50 V is selectively applied to the plurality of piezoelectric elements 2 according to an image recorded from a control unit (not shown). By applying the voltage, the piezoelectric element 12 to which the pulse voltage is applied is displaced to deform the vibration plate 2 in the direction of the nozzle plate 3, and pressurize the liquid in the liquid chamber 6 by changing the volume (volume) of the liquid chamber 6. Thus, droplets are ejected from the nozzles 4 of the nozzle plate 3. As the liquid droplets are discharged, the pressure in the liquid chamber 6 decreases, and a slight negative pressure is generated in the liquid chamber 6 due to the inertia of the liquid flow at this time. Under this state, the application of voltage to the piezoelectric element 12 is turned off, so that the diaphragm 2 returns to the original position and the liquid chamber 6 has the original shape, so that further negative pressure is generated. At this time, the liquid that has entered from the liquid supply pipe that leads to a liquid tank (not shown) is filled in the liquid chamber 6, and droplets are ejected from the nozzle 4 in response to the next drive pulse application.

Next, details of the nozzle plate 3 of the liquid discharge head will be described with reference to FIGS. 6 is an enlarged sectional explanatory view of one nozzle portion of the nozzle plate 3, and FIG. 7 is an enlarged sectional explanatory view of a main portion of the nozzle plate (note that some sectional hatching is omitted for easy understanding). The same shall apply hereinafter.)
The nozzle plate 3 is formed by forming a water-repellent layer 32 made of a silicone resin layer directly on the discharge surface side surface of a nozzle base material 31 made of a Ni metal plate in which nozzle holes 34 to become the nozzles 4 are formed. The nozzle base material 31 is described using a Ni metal plate, but is not limited thereto. However, the present invention is particularly effective when a nozzle substrate made of a metal material is used.

  Here, by setting the film thickness of the silicone resin layer (water repellent layer 32) within the range of, for example, 0.1 μm to 10 μm, wiping resistance and water repellency can be secured, and film formation is facilitated. It was. The surface roughness Ra of the silicone resin layer (water repellent layer 32) is preferably 0.2 or less for obtaining good water repellency. Further, as the silicone resin for forming the water repellent layer 32, application in the air is possible by using a room temperature curable liquid silicone resin. In particular, it is preferable to use a liquid silicone resin having a hydrolysis action.

  In the nozzle plate 3, as shown in FIG. 7, there is no oxide film between the nozzle base material 31 and the silicone resin layer which is the water repellent layer 32, and the silicone resin film is directly formed with the above film thickness. On the other hand, an oxide film 35 is formed on the wall surface 34 a of the nozzle hole 34 of the nozzle substrate 31. This oxide film 35 may be either a natural oxide film or an oxide film as a wet-resistant film formed separately in order to improve the liquid contact property of the nozzle substrate 31.

  In this case, for example, in the case where an oxide film as a liquid contact resistant film is formed on the surface of the nozzle base material 31, an oxidation film (contact liquid resistant film) 35 is formed on the entire surface of the nozzle base material 31 by performing an oxidation treatment. After the formation, a process of removing the oxide film on the discharge surface side surface of the nozzle substrate 31 is performed. At this time, not only simply removing the oxide film, but as described later, the nozzle substrate 31 was subjected to acid treatment, plasma treatment or ultraviolet irradiation treatment to remove the surface oxide film and replace the hydroxyl group. By applying a silicone resin to the nozzle substrate 31 to form a water repellent layer, the adhesion between the silicone resin layer 32 and the nozzle substrate 31 can be reliably improved. Further, when removing the natural oxide film formed on the surface of the nozzle base material 31, it is preferable to similarly perform acid treatment or the like.

  Thus, the absence of an oxide film between the nozzle substrate 31 of the nozzle plate 3 and the silicone resin layer that is the water repellent layer 32 allows the discharge surface side surface of the nozzle substrate 31 and the silicone resin layer to be repellent. Even when the adhesion strength with the water layer 32 is increased and the water-repellent layer 32 is formed by applying a silicone resin in the air, the surface of the nozzle substrate 31 and the water-repellent layer 32 that is a silicone resin layer are formed. Sufficient adhesion strength can be obtained, and stable water repellency can be maintained. In other words, a structure in which an oxide film is not interposed between the nozzle substrate 31 of the nozzle plate 3 and the silicone resin layer that is the water-repellent layer 32 forms a water-repellent layer by applying silicone resin in the air. Therefore, the water repellent layer can be easily formed, and the manufacturing cost of the head can be reduced.

Next, another example of the nozzle plate 3 of the liquid discharge head will be described with reference to FIG. FIG. 8 is an enlarged cross-sectional explanatory view of a main part of a nozzle plate similar to FIG.
This nozzle plate 3 is formed with a water repellent layer 32 made of a silicone resin layer on the discharge surface side surface of a nozzle base material 31 made of a Ni metal plate in which nozzle holes 34 to become the nozzles 4 are formed. This is the same as the seventh example.

  In the nozzle plate 3 of this example, as shown in FIG. 8, a natural oxide film 36 remains between the nozzle base material 31 and the silicone resin layer that is the water repellent layer 32. The thickness t1 of the natural oxide film 36 is the oxide film 35 on the wall surface 34a of the nozzle hole 34 (an oxide film as a wet-resistant film formed separately to improve the wettability of the natural oxide film or the nozzle substrate 31). ) To be thinner than the thickness t2.

  That is, as described above, the nozzle substrate 31 is subjected to acid treatment, plasma treatment, or ultraviolet irradiation treatment to remove the surface oxide film and replace the hydroxyl group, and then apply a silicone resin to the nozzle substrate 31. Even when the water-repellent layer is formed, a natural oxide film 36 may be formed on the surface of the nozzle base material 31 over time. The natural oxide film 36 completely covers the surface of the nozzle base material 31. By applying a silicone resin before forming the water repellent layer, the high adhesion strength between the discharge surface side surface of the nozzle substrate 31 and the water repellent layer 32, which is a silicone resin layer, can be obtained as in the above example. Obtainable.

  In this case, since the silicone resin layer is not formed on the inner wall surface of the nozzle hole 34 of the nozzle base material 31, the nozzle base material 31 and the water repellent layer 32 are further grown even if the oxide film 35 is a natural oxide film. The nozzle of the nozzle base 31 is thicker than the natural oxide film 36 remaining between the silicone resin layer or the natural oxide film 36 per unit area of the surface of the nozzle base 31 on which the silicone resin layer is formed. The oxide film 35 per unit area of the inner wall surface 34a is larger.

  Thus, the thickness of the oxide film 36 between the nozzle substrate 31 of the nozzle plate 3 and the silicone resin layer that is the water repellent layer 32 is the oxide film 35 (natural oxide film or nozzle substrate) of the wall surface 34a of the nozzle hole 34. In order to improve the wettability of 31, the thickness of the oxide film as a wet-resistant film formed separately) is made thinner so that the discharge surface side surface of the nozzle substrate 31 and the silicone resin layer are repellent. Even when the adhesion strength with the water layer 32 is increased and the water-repellent layer 32 is formed by applying a silicone resin in the air, the surface of the nozzle substrate 31 and the water-repellent layer 32 that is a silicone resin layer are formed. Sufficient adhesion strength can be obtained, and stable water repellency can be maintained. In other words, since the water repellent layer can be formed by applying silicone resin in the air, the water repellent layer can be easily formed, and the manufacturing cost of the head can be reduced.

  On the other hand, when the water-repellent layer 32 is formed by applying a silicone resin after forming the oxide film 35 on the discharge surface side surface of the nozzle substrate 31 as shown in FIG. As shown in (b), when the ejection surface is wiped with the wiper blade 40, the peripheral portion 32a of the water repellent layer 32 facing the nozzle hole 34 is easily peeled off, and stable water repellency cannot be maintained. .

  Further, when the liquid discharge head according to the present invention and the liquid discharge head described with reference to FIG. 9 were tested for the adhesion of the water-repellent layer 32 to the ink immersion, as shown in FIG. When the oxide film 35 is also present on the surface side surface, the water-repellent layer 32 was not peeled off at the initial stage, but was peeled off when immersed in the ink, whereas the liquid discharge head according to the present invention. When there is no oxide film 35 on the discharge surface side surface of the nozzle base material 31 (when there is no oxide film and when there is a natural oxide film 36), the water-repellent layer 32 is peeled off even after being immersed in the ink at the initial stage. Did not occur. Thus, it was confirmed that the adhesion strength between the water repellent layer 32 and the nozzle substrate 31 is high in the liquid discharge head according to the present invention.

Next, the relationship with the ink to be used will be described.
An experiment was conducted regarding the relationship between the case where the nozzle substrate 31 is made of Ni and the ink. As a result, as shown in FIG. 11, when the oxide film 35 as a liquid contact resistant film is not formed on the nozzle inner wall surface 34a, if the oxide film 35 is present when the ink pH = 3 (acid side), some Ni Elution was observed, and a large amount of Ni was observed without the oxide film 35. On the other hand, it was confirmed that when the ink pH is 9 (alkali side), if the oxide film 35 is present, Ni is not eluted, and even if the oxide film 35 is not present, Ni is little eluted. Further, when an elution inhibitor for Ni was added to the ink, no elution of Ni was observed even when the oxide film 35 was not present.

  For this reason, the liquid discharge head according to the present invention can reduce the elution of the ink base material by using a recording liquid exhibiting alkalinity in the range of pH = 8 to 11 as the recording liquid (ink). Preferably, the elution of the ink base material can be reliably prevented by adding an elution inhibitor to the recording liquid.

  That is, in the liquid discharge head according to the present invention, as described above, there is no oxide film between the nozzle base material and the water-repellent layer of the silicone resin layer, or there is a relatively thin natural oxide film. Therefore, it is preferable not to form an oxide film as a liquid contact film on the inner wall surface of the nozzle in order to simplify the oxide film removal process. However, by not forming an oxide film as a wetted film on the inner wall surface of the nozzle, when the nozzle base material is Ni or the like, depending on the ink composition, the nozzle base material Ni is likely to elute into the ink, so pH = It is preferable to reduce elution of the ink base material by using a recording liquid exhibiting alkalinity within the range of 8 to 11 or using a recording liquid to which an elution inhibitor is added.

  Furthermore, the liquid discharge head according to the present invention can obtain good water repellency with respect to a recording liquid containing a fluorine compound. That is, it was confirmed that when a recording liquid containing a fluorine compound (for example, a surfactant) is used, sufficient water repellency cannot be obtained even if a water repellent layer of a fluorine resin is formed. On the other hand, by using a water-repellent layer of silicone resin, sufficient water repellency can be obtained even for a recording liquid containing a fluorine compound.

  In this case, the dynamic surface tension can be reduced to 30 mN / m or less by containing a fluorine-based compound in the recording liquid. By using a recording liquid having a low surface tension with a dynamic surface tension of 30 mN / m or less, the ink permeation speed can be increased, and in particular, the drying time can be shortened when pigment-based ink is used.

Next, an example of a method for manufacturing a liquid discharge head according to the present invention will be described with reference to FIG.
First, as shown in FIG. 12A, a natural oxide film or an oxide film 35 as a liquid contact film is formed on the surface of the nozzle base 31 formed by Ni electroforming. As shown in FIG. 12, after acid treatment is performed to remove the oxide film 35 on the surface and hydroxyl substitution is performed on the surface, as shown in FIG. In a state where air 51 is blown from the surface opposite to the discharge surface to the discharge surface, a liquid silicone resin is applied to the nozzle base material 31 by the dispenser 50 to form a silicone resin film 52, and the silicone resin The film 52 is cured to form the water repellent layer 32 as shown in FIG.

  In this way, by performing the acid treatment to remove the oxide film, the water-repellent layer 32 is formed by applying a silicone resin in the atmosphere without the oxide film on the discharge surface side surface of the nozzle base material 31. Can do. In this case, a natural oxide film 36 may be formed on the surface of the nozzle substrate 31 by being exposed to the atmosphere between the acid treatment and the application of the silicone resin. Thus, the adhesion strength between the silicone resin and the nozzle substrate is obtained.

  The oxide film removal treatment can be performed by plasma treatment, ultraviolet irradiation treatment, or the like, but the acid treatment is the simplest and can be performed at low cost.

  Next, an example of an image forming apparatus according to the present invention including an apparatus for ejecting liquid droplets according to the present invention provided with the liquid ejection head according to the present invention will be described with reference to 13 and FIG. FIG. 13 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG. 14 is an explanatory plan view of the main part of the apparatus.

  In this image forming apparatus, a carriage 103 is slidably held in a main scanning direction by a guide rod 101 and a guide rail 102 that are horizontally mounted on left and right side plates (not shown), and a driving pulley 106A is driven by a main scanning motor 104. 14 is moved and scanned in the direction indicated by the arrow (main scanning direction) in FIG.

  For example, four independent ink jet recording liquid droplets (ink droplets) of black (K), cyan (C), magenta (M), and yellow (Y) are recorded on the carriage 103. The recording head 107 composed of the liquid ejection heads 107k, 107c, 107m, and 107y is arranged in a direction along the main scanning direction, and is mounted with the droplet ejection direction facing downward. In addition, although the independent liquid discharge head is used here, it is also possible to employ a configuration in which one or a plurality of heads having a plurality of nozzle rows for discharging recording liquid droplets of each color are used. Further, the number of colors and the arrangement order are not limited to this.

  The liquid discharge head according to the present invention constituting the recording head 107 includes a diaphragm that forms the wall surface of the ink flow path using an electromechanical conversion element such as a piezoelectric element as pressure generating means for pressurizing ink in the pressurized liquid chamber. A so-called piezo type that changes the volume of the ink flow path to eject ink droplets, a so-called thermal type that utilizes film boiling of the recording liquid using an electrothermal conversion element such as a heating resistor, The diaphragm and the electrode forming the wall surface of the ink flow path are arranged opposite to each other, and the diaphragm is deformed by an electrostatic force generated between the vibration plate and the electrode, thereby changing the volume of the ink flow path to change the ink droplet. An electrostatic type that discharges water, a shape memory alloy actuator that uses a metal phase change due to a temperature change, and the like can be used.

  The carriage 103 is equipped with a sub tank 108 for each color for supplying each color ink to the recording head 107. Ink is supplied to the sub tank 108 from a main tank (ink cartridge) (not shown) via an ink supply tube 109.

  On the other hand, as a sheet feeding unit for feeding a recording medium (sheet) 112 loaded on a sheet stacking unit (pressure plate) 111 such as a sheet feeding cassette 110, the sheets 112 are separated and fed from the sheet stacking unit 111 one by one. Opposite to the half-moon roller (feed roller) 113 and the feed roller 113 to be fed, a separation pad 114 made of a material having a large friction coefficient is provided, and this separation pad 114 is urged toward the feed roller 113 side.

  As a transport unit for transporting the paper 112 fed from the paper feed unit below the recording head 107, a transport belt 121 for electrostatically attracting and transporting the paper 112, and a paper feed unit A counter roller 122 for transporting the paper 112 fed through the guide 115 while sandwiching it between the transport belt 121 and the paper 112 fed substantially vertically upward is changed by about 90 ° and copied on the transport belt 121. A conveying guide 123 for adjusting the pressure and a tip pressure roller 125 urged toward the conveying belt 121 by a pressing member 124. In addition, a charging roller 126 that is a charging unit for charging the surface of the conveyance belt 121 is provided.

  Here, the conveyance belt 121 is an endless belt, and is stretched between the conveyance roller 127 and the tension roller 128, and the conveyance roller 127 rotates from the sub-scanning motor 131 via the timing belt 132 and the timing roller 133. By doing so, it is configured to circulate in the belt conveyance direction (sub-scanning direction) of FIG. A guide member 129 is disposed on the back side of the conveyance belt 121 in correspondence with the image forming area formed by the recording head 107.

  In addition, a slit disk 134 is attached to the shaft of the transport roller 127, and a sensor 135 for detecting the slit of the slit disk 134 is provided, and the encoder 136 is configured by the slit disk 134 and the sensor 135. .

  The charging roller 126 is arranged so as to contact the surface layer of the conveyor belt 121 and rotate following the rotation of the conveyor belt 121, and applies 2.5N to both ends of the shaft as a pressing force.

  Further, an encoder scale 142 having slits is provided on the front side of the carriage 103, and an encoder sensor 143 including a transmission type photosensor for detecting the slits of the encoder scale 142 is provided on the front side of the carriage 103. An encoder 144 for detecting the position of the carriage 103 in the main scanning direction is configured.

  Further, as a paper discharge unit for discharging the paper 112 recorded by the recording head 107, a separation unit for separating the paper 112 from the conveying belt 121, a paper discharge roller 152 and a paper discharge roller 153, and paper discharge A paper discharge tray 154 for stocking the paper 112 to be printed.

  A double-sided paper feeding unit 155 is detachably mounted on the back. The double-sided paper feeding unit 155 takes in the paper 112 returned by the reverse rotation of the transport belt 121, reverses it, and feeds it again between the counter roller 122 and the transport belt 121.

  Further, as shown in FIG. 13, a maintenance / recovery mechanism 156 for maintaining and recovering the nozzle state of the recording head 107 is disposed in the non-printing area on one side of the carriage 103 in the scanning direction.

  The maintenance / recovery machine 156 includes a cap 157 for capping each nozzle surface of the recording head 107, a wiper blade 158 which is a blade member for wiping the nozzle surface, and a discharge unit for discharging the thickened recording liquid. An empty discharge receiver 159 for receiving droplets when performing empty discharge for discharging droplets that do not contribute to recording is provided.

  In the image forming apparatus configured as described above, the sheets 112 are separated and fed one by one from the sheet feeding unit, and the sheet 112 fed substantially vertically upward is guided by the guide 115, and includes the conveyance belt 121 and the counter roller 122. The leading end is guided by the conveying guide 123 and pressed against the conveying belt 121 by the leading end pressure roller 125, and the conveying direction is changed by approximately 90 °.

  At this time, a positive voltage output and a negative output are alternately repeated from the high voltage power source to the charging roller 126 by a control circuit (not shown), that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 121 alternates, In the sub-scanning direction, which is the circumferential direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 112 is fed onto the conveyance belt 121 charged alternately with plus and minus, the paper 112 is attracted to the conveyance belt 121 by electrostatic force, and the paper 112 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 121. Is done.

  Therefore, by driving the recording head 107 according to the image signal while moving the carriage 103 in the forward and backward directions, ink droplets are ejected onto the stopped paper 112 to record one line, and the paper 112 is After transporting a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 112 has reached the recording area, the recording operation is finished, and the paper 112 is discharged onto the paper discharge tray 154.

  In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording belt 112 is fed into the double-sided paper feeding unit 155 by rotating the conveyor belt 121 in the reverse direction. The paper 112 is reversed (with the back surface being the printing surface), and is fed again between the counter roller 122 and the conveyor belt 121. The timing is controlled, and the sheet is conveyed onto the conveyor bell 121 as described above. After recording on the back side, the sheet is discharged to the discharge tray 154.

  Further, during printing (recording) standby, the carriage 103 is moved to the maintenance / recovery mechanism 155 side, and the nozzle surface of the recording head 107 is capped by the cap 157 so that the nozzles are kept in a wet state. To prevent. In addition, the recording liquid is sucked from the nozzle in a state where the recording head 107 is capped by the cap 157 (referred to as “nozzle suction” or “head suction”), and a recovery operation is performed to discharge the thickened recording liquid or bubbles. Wiping is performed by the wiper blade 158 in order to clean and remove ink adhering to the nozzle surface of the recording head 107 by this recovery operation. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the recording head 107 is maintained.

  As described above, since the image forming apparatus includes the liquid discharge head according to the present invention, the water-repellent layer 32 does not peel off even when wiping is performed by the wiper blade 158 of the maintenance / recovery mechanism 155, and the image forming apparatus can be used for a long time. Since stable and sufficient water repellency can be maintained and stable droplet ejection characteristics can be obtained, high-quality images can be stably formed.

  In the above embodiments, the printer configuration has been described as the image forming apparatus according to the present invention. However, the present invention is not limited to this, and can be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. Further, the present invention can also be applied when using a recording liquid that is a liquid other than ink.

  Next, the recording method according to the present invention will be described. In the recording method according to the present invention, an image is recorded on a recording medium (paper) by ejecting liquid droplets from the liquid ejection head according to the present invention as in the image forming apparatus described above.

  Here, first, the relationship between the nozzle plate (nozzle plate), the recording liquid (here, ink), and the recording medium (referred to as media) of the liquid ejection head according to the present invention will be described. As described above, the liquid according to the present invention. The nozzle plate of the ejection head is excellent in water repellency and ink repellency. Therefore, even when ink having a low surface tension is used, ink droplets can be well formed (particulate). This is because the nozzle plate is not too wet and the ink meniscus is formed normally. When the meniscus is formed normally, the ink is not pulled in one direction when the ink is ejected, and as a result, there is little ink ejection bending and an image with high dot position accuracy can be obtained.

  When printing on paper (media) with low absorbency, the quality of the dot position is noticeable in image quality. In other words, since it is difficult for ink to spread on paper with low absorbency, if the dot position accuracy is as low as possible, a portion where the ink cannot be filled in the paper, that is, a white portion is generated. This portion that cannot be filled up leads to uneven image density and reduced image density, and appears in the degradation of image quality.

  However, since the nozzle plate of the liquid ejection head according to the present invention has high dot position accuracy even when using low surface tension ink, the ink can fill the paper even when using paper with low absorbency. Prints with high image quality can be obtained without unevenness or image density reduction.

Hereinafter, a recording medium (recording medium) used in the recording method according to the present invention and ink as a recording liquid will be described.
<Recording media>
The recording medium has a support and a coating layer on at least one surface of the support, and further has other layers as necessary.

As the recording medium, the transfer amount of the ink as the recording liquid to the recording medium at a contact time of 100 ms measured with a dynamic scanning absorption meter is ² to 40 ml / m ² , more preferably 3 to 30 ml / What is m ² is used. Similarly, a transfer amount of pure water to a recording medium at a contact time of 100 ms measured with a dynamic scanning absorption meter is preferably ² to 45 ml / m ² , more preferably 3 to 30 ml / m ² . . As a recording medium, if the transfer amount of ink and pure water at a contact time of 100 ms is too small, beading is likely to occur. If it is too large, the ink dot diameter after recording is smaller than the desired diameter. May be too much.

Moreover, as a recording medium, the transfer amount of the ink to the recording medium at a contact time of 400 ms measured with a dynamic scanning absorption meter is 3 to 50 ml / m ² , more preferably 4 to 40 ml / m ^2. Is used. Similarly, the amount of transfer of pure water to a recording medium at a contact time of 400 ms measured with a dynamic scanning absorption meter is 3 to 50 ml / m ² , more preferably 4 to 40 ml / m ² . . As a recording medium, if the transfer amount at a contact time of 400 ms is too small, the drying property is insufficient, and thus spur marks are likely to occur. If it is too much, bleeding is likely to occur. In some cases, the gloss of the image portion tends to be low.

  Here, the above-mentioned dynamic scanning absorption meter (DSA, Papa Technical Journal, Vol. 48, May 1994, pp. 88-92, Shigenori Kusaka) It is a device that can measure accurately. This dynamic scanning absorptiometer reads the liquid absorption speed directly from the movement of the meniscus in the capillary, makes the sample disk-shaped, and then scans the liquid absorption head in a spiral pattern according to a preset pattern. Is automatically changed by a method in which the number of necessary points is measured with one sample. A liquid supply head for a paper sample is connected to a capillary via a Teflon (registered trademark) tube, and the position of the meniscus in the capillary is automatically read by an optical sensor. Specifically, the transfer amount of pure water or ink was measured using a dynamic scanning absorption meter (K350 series D type, manufactured by Kyowa Seiko Co., Ltd.). The transfer amount at the contact time of 100 ms and the contact time of 400 ms can be obtained by interpolation from the measured value of the transfer amount at the contact time adjacent to each contact time. The measurement was performed at 23 ° C. and 50% RH.

-Support-
The support is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include paper based on wood fibers, and sheet-like materials such as non-woven fabrics mainly composed of wood fibers and synthetic fibers. .

  Here, there is no restriction | limiting in particular as paper, According to the objective, it can select suitably according to the objective, For example, wood pulp, waste paper pulp, etc. are used. Examples of the wood pulp include hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), NBSP, LBSP, GP, and TMP.

  As the raw material of waste paper pulp, the white paper, ruled white, cream white, card, special white, medium white, imitation, fair white, Kent, white art, as shown in the used paper standard quality standard table of the Waste Paper Recycling Promotion Center , Special upper deadline, separate upper deadline, newspaper, magazine and so on. Specifically, printer paper such as non-coating computer paper, thermal paper, and pressure-sensitive paper as information-related paper; OA waste paper such as PPC paper; coating of art paper, coated paper, finely coated paper, matte paper, etc. Paper: High quality paper, color quality, notebook, notepaper, wrapping paper, fancy paper, medium quality paper, newsprint, reprint paper, super paper, imitation paper, pure white roll paper, uncoated paper such as milk carton, etc. Examples of used paper and paperboard include chemical pulp paper and high-yield pulp-containing paper. These may be used individually by 1 type and may use 2 or more types together.

This waste paper pulp is generally produced from a combination of the following four steps.
(1) For disaggregation, waste paper is treated with mechanical force and chemicals with a pulper to loosen it into a fibrous form, and the printing ink is peeled off from the fiber.
(2) Dust removal is to remove foreign matter (plastic etc.) and dust contained in waste paper with a screen, cleaner or the like.
(3) In the deinking, the printing ink peeled off from the fiber using a surfactant is removed from the system by a flotation method or a cleaning method.
(4) Bleaching increases the whiteness of the fiber using an oxidizing action or a reducing action.
When used paper pulp is mixed, the mixing ratio of the used paper pulp in the total pulp is preferably 40% or less from the viewpoint of curling after recording.

  Moreover, as an internal filler used for a support body, a conventionally well-known pigment is used, for example as a white pigment. Examples of white pigments include light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, and silicic acid. White inorganic pigments such as calcium, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, magnesium hydroxide, styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin, And organic pigments such as melamine resins. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the internal sizing agent used for making the support include neutral rosin sizing agents used for neutral papermaking, alkenyl succinic anhydride (ASA), alkyl ketene dimer (AKD), petroleum Examples thereof include resin-based sizing agents. Among these, a neutral rosin sizing agent or alkenyl succinic anhydride is particularly preferable. The alkyl ketene dimer may be added in a small amount because of its high size effect, but the friction coefficient on the surface of the recording paper (media) is low and slippery, which is not preferable from the viewpoint of transportability during ink jet recording. There is.

-Coating layer-
The coating layer contains a pigment and a binder (binder), and further contains a surfactant and other components as necessary.

Here, as the pigment, an inorganic pigment or a combination of an inorganic pigment and an organic pigment can be used.
Examples of inorganic pigments include kaolin, talc, heavy calcium carbonate, light calcium carbonate, calcium sulfite, amorphous silica, titanium white, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and water. Examples include zinc oxide and chlorite. Among these, kaolin is particularly preferable because it has excellent glossiness and can be made close to a paper for offset printing.

  The kaolin includes delaminated kaolin, calcined kaolin, engineered kaolin by surface modification, etc., but considering the gloss development, the particle size distribution with a particle size of 2 μm or less is 80% by mass or more. It is preferable that the kaolin which has occupies 50 mass% or more of the whole kaolin.

  The amount of kaolin added is preferably 50 parts by mass or more with respect to 100 parts by mass of the total pigment in the coating layer. When the addition amount is less than 50 parts by mass, a sufficient effect on glossiness may not be obtained. The upper limit of the addition amount is not particularly limited, but is preferably 90 parts by mass or less from the viewpoint of coating suitability in consideration of the fluidity of kaolin, particularly the thickening under high shear force.

  Examples of organic pigments include water-soluble dispersions such as styrene-acrylic copolymer particles, styrene-butadiene copolymer particles, polystyrene particles, and polyethylene particles. Two or more of these organic pigments may be mixed.

  The amount of the organic pigment added is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the total pigment in the coating layer. Since the organic pigment is excellent in gloss expression and its specific gravity is smaller than that of an inorganic pigment, it is possible to obtain a coating layer that is bulky, high gloss, and has good surface coverage. When the addition amount is less than 2 parts by mass, the above effect is not obtained. When the addition amount exceeds 20 parts by mass, the fluidity of the coating liquid deteriorates, leading to a decrease in coating operability, and economical from the viewpoint of cost. is not.

  The organic pigment has a solid type, a hollow type, a donut type and the like in its form, but the average particle size is 0.2 to 0.2 in view of the balance of gloss development, surface coverage, and fluidity of the coating liquid. A hollow type having a porosity of 40% or more is more preferable.

As the binder, it is preferable to use an aqueous resin.
Here, as the aqueous resin, at least one of a water-soluble resin and a water-dispersible resin is preferably used. There is no restriction | limiting in particular as water-soluble resin, According to the objective, it can select suitably, For example, modified products of polyvinyl alcohol, such as polyvinyl alcohol, anion modified polyvinyl alcohol, cation modified polyvinyl alcohol, acetal modified polyvinyl alcohol; Polyurethane Polyvinylpyrrolidone and polyvinylpyrrolidone and vinyl acetate copolymer, vinylpyrrolidone and dimethylaminoethyl / methacrylic acid copolymer, quaternized vinylpyrrolidone / dimethylaminoethyl / methacrylic acid copolymer, vinylpyrrolidone and methacrylic acid Modified products of polyvinylpyrrolidone such as a copolymer of amidopropyltrimethylammonium chloride; cellulose such as carboxymethylcellulose, hydroxyethylcellulose, droxypropylcellulose; Modified products of cellulose such as thiolated hydroxyethyl cellulose; synthetic resins such as polyester, polyacrylic acid (ester), melamine resin, or modified products thereof, polyester and polyurethane copolymer; poly (meth) acrylic acid, poly ( Examples thereof include (meth) acrylamide, oxidized starch, phosphate esterified starch, self-modified starch, cationized starch, or various modified starches, polyethylene oxide, sodium polyacrylate, and sodium alginate. These may be used individually by 1 type and may use 2 or more types together.

  Among these, polyvinyl alcohol, cation-modified polyvinyl alcohol, acetal-modified polyvinyl alcohol, polyester, polyurethane, a copolymer of polyester and polyurethane, and the like are particularly preferable from the viewpoint of ink absorbability.

  The water-dispersible resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyvinyl acetate, ethylene-vinyl acetate copolymer, polystyrene, styrene- (meth) acrylate copolymer , (Meth) acrylic acid ester polymer, vinyl acetate- (meth) acrylic acid (ester) copolymer, styrene-butadiene copolymer, ethylene-propylene copolymer, polyvinyl ether, silicone-acrylic copolymer , Etc. Further, it may contain a crosslinking agent such as methylolated melamine, methylolated urea, methylolated hydroxypropylene urea, or isocyanate, or may be a copolymer containing units such as N-methylolacrylamide and having a self-crosslinking property. A plurality of these water-based resins can be used simultaneously.

  2-100 mass parts is preferable with respect to 100 mass parts of said pigments, and, as for the addition amount of aqueous resin, 3-50 mass parts is more preferable. The amount of the aqueous resin added is determined so that the liquid absorption characteristics of the recording medium fall within a desired range.

  When a water-dispersible colorant is used as the colorant, the cationic organic compound is not necessarily added, but is not particularly limited and can be appropriately selected and used depending on the purpose. For example, a primary to tertiary amine, quaternary ammonium salt monomer or oligomer that reacts with a sulfonic acid group, a carboxyl group, an amino group, or the like in a direct dye or acidic dye in water-soluble ink to form an insoluble salt A polymer etc. are mentioned, Among these, an oligomer or a polymer is preferable.

  Examples of the cationic organic compound include dimethylamine / epichlorohydrin polycondensate, dimethylamine / ammonia / epichlorohydrin condensate, poly (trimethylaminoethyl methacrylate / methyl sulfate), diallylamine hydrochloride / acrylamide copolymer. , Poly (diallylamine hydrochloride / sulfur dioxide), polyallylamine hydrochloride, poly (allylamine hydrochloride / diallylamine hydrochloride), acrylamide / diallylamine copolymer, polyvinylamine copolymer, dicyandiamide, dicyandiamide / ammonium chloride / urea / formaldehyde Condensate, polyalkylene polyamine dicyandiamide ammonium salt condensate, dimethyldiallylammonium chloride, polydiallylmethylamine hydrochloride, poly (diallyl) Methylammonium chloride), poly (diallyldimethylammonium chloride / sulfur dioxide), poly (diallyldimethylammonium chloride / diallylamine hydrochloride derivative), acrylamide / diallyldimethylammonium chloride copolymer, acrylate / acrylamide / diallylamine hydrochloride copolymer Products, ethyleneimine derivatives such as polyethyleneimine and acrylicamine polymer, and polyethyleneimine alkylene oxide modified products. These may be used individually by 1 type and may use 2 or more types together.

  Among these, low molecular weight cationic organic compounds such as dimethylamine / epichlorohydrin polycondensate and polyallylamine hydrochloride and other relatively high molecular weight cationic organic compounds such as poly (diallyldimethylammonium chloride) It is preferable to use in combination. By using in combination, the image density can be improved and feathering can be further reduced as compared with the case of single use.

  The cation equivalent of the cationic organic compound by colloid titration method (using polyvinyl potassium sulfate and toluidine blue) is preferably 3 to 8 meq / g. If the cation equivalent is within this range, good results can be obtained within the above dry adhesion range. In the measurement of the cation equivalent by the colloid titration method, the cationic organic compound is diluted with distilled water so that the solid content becomes 0.1% by mass, and the pH is not adjusted.

  The dry adhesion amount of the cationic organic compound is preferably 0.3 to 2.0 g / m2. When the dry adhesion amount of the cationic organic compound is less than 0.3 g / m 2, sufficient image density improvement and feathering reduction effects may not be obtained.

  The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Any of anionic, cationic, amphoteric and nonionic surfactants can be used. . Of these, nonionic active agents are particularly preferred. By adding a surfactant, the water resistance of the image is improved, the image density is increased, and bleeding is improved.

  Here, as the nonionic activator, for example, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide adduct, higher aliphatic amine ethylene oxide adduct, Fatty acid amide ethylene oxide adduct, fat ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, glycerol fatty acid ester, pentaerythritol fatty acid ester, sorbitol and sorbitan fatty acid ester, sucrose fatty acid ester, polyhydric alcohol alkyl Examples include ethers and fatty acid amides of alkanolamines. These may be used individually by 1 type and may use 2 or more types together.

  The polyhydric alcohol is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include glycerol, trimethylolpropane, pentaerythritol, sorbitol, and sucrose. As the ethylene oxide adduct, a product obtained by substituting a part of ethylene oxide with an alkylene oxide such as propylene oxide or butylene oxide is also effective as long as water solubility can be maintained. The substitution rate is preferably 50% or less. 4-15 are preferable and, as for HLB (hydrophilic / lipophilic ratio) of the said nonionic activator, 7-13 are more preferable.

  0-10 mass parts is preferable with respect to 100 mass parts of said cationic organic compounds, and, as for the addition amount of surfactant, 0.1-1.0 mass part is more preferable.

  Other components can be added to the coating layer as needed, as long as the object and effect of the present invention are not impaired. Examples of the other components include additives such as alumina powder, pH adjuster, preservative, and antioxidant.

  There is no restriction | limiting in particular as a formation method of this coating layer, According to the objective, it can select suitably, It can carry out by the method of impregnating or apply | coating a coating layer liquid on the said support body. The impregnation or coating method of the coating layer liquid is not particularly limited and can be appropriately selected according to the purpose. For example, a conventional size press, a gate roll size press, a film transfer size press, a blade coater, a rod coater, It can be applied with various coating machines such as an air knife coater and curtain coater. Among these, from the viewpoint of cost, a method of impregnating or adhering with a conventional size press, a gate roll size press, a film transfer size press or the like installed in a paper machine and finishing on-machine is preferable.

  There is no restriction | limiting in particular in the adhesion amount of this coating layer liquid, Although it can select suitably according to the objective, 0.5-20 g / m2 is preferable at solid content, and 1-15 g / m2 is more preferable. In addition, after impregnation or application | coating, you may make it dry as needed, As temperature of drying in this case, there is no restriction | limiting in particular, Although it can select suitably according to the objective, About 100-250 degreeC is. preferable.

  As the recording medium used in the recording method according to the present invention, a back layer may be formed on the back surface of the support, between the support and the coating layer, and other layers may be formed between the support and the back layer. A protective layer can also be provided on the coating layer. Each of these layers may be a single layer or a plurality of layers.

  The recording medium used in the recording method according to the present invention is a commercially available coated paper for offset printing, coated paper for gravure printing, etc., as long as the liquid absorption property is within the range of the present invention. Also good.

The basis weight of the recording medium used in the recording method according to the present invention is preferably 50 to 250 g / m ² . If it is less than 50 g / m ² , there is no stiffness, and a conveyance failure such as a recording medium being clogged in the middle of the conveyance path tends to occur. If it exceeds 250 g / m 2, the stiffness becomes too large, so that the recording medium cannot be bent at the curved portion in the middle of the conveyance path, and a conveyance failure such as clogging of the recording medium is likely to occur.

Next, ink as a recording liquid used in the recording method according to the present invention will be described.
<Ink>
The ink used in the recording method according to the present invention contains at least water, a colorant, and a wetting agent, and further contains a penetrating agent, a surfactant, and, if necessary, other components.

  Here, the ink has a surface tension at 25 ° C. of 15 to 40 mN / m, and more preferably 20 to 35 mN / m. When the surface tension is less than 15 / m, the liquid ejection head according to the present invention is too wet with the nozzle plate (nozzle plate) to form ink droplets (particle formation), or used in the recording method according to the present invention. Bleeding on the recording medium becomes significant, and stable ink ejection may not be obtained. If it exceeds 40 mN / m, ink penetration into the recording medium does not occur sufficiently and beading or drying occurs. The time may be prolonged.

  The surface tension can be measured at 25 ° C. using a platinum plate using, for example, a surface tension measuring device (CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.).

-Colorant-
As the colorant contained in the ink, it is preferable to use at least one of a pigment, a dye, and colored fine particles.

As the colored fine particles, an aqueous dispersion of polymer fine particles containing at least one colorant of pigment and dye is preferably used.
Here, the term “containing a color material” means either or both of a state in which a color material is enclosed in polymer fine particles and a state in which the color material is adsorbed on the surface of the polymer fine particles. In this case, it is not necessary for all of the color material blended in the ink of the present invention to be encapsulated or adsorbed in the polymer fine particles, and the color material is dispersed in the emulsion as long as the effects of the present invention are not impaired. Also good. The color material is not particularly limited as long as it is water-insoluble or hardly water-soluble and can be adsorbed by the polymer, and can be appropriately selected according to the purpose.

  Further, “water-insoluble or poorly water-soluble” means that 10 parts by mass or more of the coloring material is not dissolved in 100 parts by mass of water at 20 ° C. Further, “dissolve” means that separation or sedimentation of the coloring material is not observed in the surface layer or the lower layer of the aqueous solution visually.

  The volume average particle diameter of the polymer fine particles (colored fine particles) containing a colorant is preferably 0.01 to 0.16 μm in the ink.

  Examples of the colorant include water-soluble dyes, oil-soluble dyes, disperse dyes, and the like, pigments, and the like. Oil-soluble dyes and disperse dyes are preferable from the viewpoint of good adsorptivity and encapsulation, but pigments are preferably used from the light resistance of the obtained image.

  In addition, from the viewpoint of efficiently impregnating the polymer fine particles, each of the dyes is preferably dissolved in an organic solvent, for example, a ketone solvent in an amount of 2 g / liter or more, and more preferably 20 to 600 g / liter.

  The water-soluble dye is a dye classified into an acid dye, a direct dye, a basic dye, a reactive dye, and a food dye in the color index, and preferably has excellent water resistance and light resistance.

  In this case, examples of acid dyes and food dyes include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142; C.I. I. Acid Red 1,8,13,14,18,26,27,35,37,42,52,82,87,89,92,97,106,111,114,115,134,186,249,254 289; I. Acid Blue 9, 29, 45, 92, 249; I. Acid Black 1, 2, 7, 24, 26, 94; I. Food Yellow 3, 4; I. Food red 7, 9, 14; I. Food black 1, 2 etc. are mentioned.

  Examples of direct dyes include C.I. I. Direct yellow 1,12,24,26,33,44,50,86,120,132,142,144; I. Direct red 1,4,9,13,17,20,28,31,39,80,81,83,89,225,227; I. Direct orange 26, 29, 62, 102; I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202; I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171 and the like.

  Examples of basic dyes include C.I. I. Basic yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 64, 65, 67, 70, 73, 77, 87, 91; C.I. I. Basic Red 2,12,13,14,15,18,22,23,24,27,29,35,36,38,39,46,49,51,52,54,59,68,69,70, 73, 78, 82, 102, 104, 109, 112; I. Basic blue 1,3,5,7,9,21,22,26,35,41,45,47,54,62,65,66,67,69,75,77,78,89,92,93, 105, 117, 120, 122, 124, 129, 137, 141, 147, 155; I. Basic black 2, 8 etc. are mentioned.

  Examples of reactive dyes include C.I. I. Reactive Black 3, 4, 7, 11, 12, 17; C.I. I. Reactive Yellow 1,5,11,13,14,20,21,22,25,40,47,51,55,65,67; I. Reactive Red 1,14,17,25,26,32,37,44,46,55,60,66,74,79,96,97; I. Reactive blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95, and the like.

The pigment is not particularly limited and may be appropriately selected depending on the purpose.
Either an inorganic pigment or an organic pigment may be used.

Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black. Among these, carbon black is preferable. In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.

  Examples of organic pigments include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable. Examples of the azo pigment include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of the polycyclic pigment include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinofullerone pigments. Examples of the dye chelates include basic dye chelates and acidic dye chelates.

  There is no restriction | limiting in particular as a color of a pigment, According to the objective, it can select suitably, For example, the thing for black, the thing for color, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.

  Examples of black materials include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, copper, iron (CI pigment black 11), titanium oxide, and the like. And organic pigments such as aniline black (CI Pigment Black 1).

  As for the color, for yellow ink, for example, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 23, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 74, 81, 83 (Disazo Yellow HR), 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 128, 138, 150, 153, and the like.

  For magenta, for example, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (Permanent Red 2B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48 : 3 (Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G Lake), 83, 88, 92, 101 (Bengara), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Dimethylquinacridone), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 19, and the like.

  For cyan, for example, C.I. I. Pigment Blue 1, 2, 15 (copper phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 1, 56, 60, 63 and the like.

  In addition, as the intermediate colors for red, green and blue, C.I. I. Pigment red 177, 194, 224, C.I. I. Pigment orange 43, C.I. I. Pigment violet 3, 19, 23, 37, C.I. I. Pigment green 7, 36, and the like.

  As the pigment, a self-dispersing pigment that can be stably dispersed without using a dispersant in which at least one hydrophilic group is bonded to the surface of the pigment directly or through another atomic group is suitably used. As a result, unlike the conventional ink, a dispersant for dispersing the pigment becomes unnecessary. As the self-dispersing pigment, those having ionicity are preferable, and those having an anionic charge or those having a cationic charge are suitable.

  The volume average particle size of the self-dispersing pigment is preferably 0.01 to 0.16 μm in the ink.

Examples of the anionic hydrophilic group include —COOM, —SO ₃ M, —PO ₃ HM, —PO ₃ M ₂ , —SO ₂ NH ₂ , —SO ₂ NHCOR (where M in the formula represents hydrogen Atom, alkali metal, ammonium or organic ammonium, R represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent) Is mentioned. Among these, it is preferable to use those in which —COOM and —SO ₃ M are bonded to the surface of the color pigment.

  “M” in the hydrophilic group includes, for example, lithium, sodium, potassium and the like as an alkali metal. Examples of the organic ammonium include mono to trimethyl ammonium, mono to triethyl ammonium, and mono to trimethanol ammonium. As a method of obtaining the anionically charged color pigment, as a method of introducing —COONa to the color pigment surface, for example, a method of oxidizing the color pigment with sodium hypochlorite, a method of sulfonation, a diazonium salt The method of making it react is mentioned.

  Further, as the cationic hydrophilic group, for example, a quaternary ammonium group is preferable, and the quaternary ammonium groups listed below are more preferable, and any of these bonded to the pigment surface is suitable as a coloring material. .

  The method for producing the cationic self-dispersing carbon black to which the hydrophilic group is bonded is not particularly limited and may be appropriately selected depending on the intended purpose. For example, N— represented by the following structural formula Examples of the method for bonding the ethylpyridyl group include a method of treating carbon black with 3-amino-N-ethylpyridinium bromide.

Here, the hydrophilic group may be bonded to the surface of the carbon black via another atomic group. Examples of other atomic groups include an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. Specific examples of the case where the above-described hydrophilic group is bonded to the surface of carbon black via another atomic group include, for example, —C ₂ H ₄ COOM (where M represents an alkali metal, quaternary ammonium), -PhSO ₃ M (where Ph represents a phenyl group, M represents an alkali metal, quaternary ammonium), -C ₅ H ₁₀ NH ₃ + and the like.

  For the ink used in the recording method according to the present invention, a pigment dispersion using a pigment dispersant can also be used.

  Examples of the pigment dispersant include the above-mentioned hydrophilic polymer compounds, and in the natural system, vegetable polymers such as gum arabic, tragan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, quince seed starch, alginic acid, carrageenan And seaweed polymers such as agar, animal polymers such as gelatin, casein, albumin and collagen, and microorganism polymers such as xanthene gum and dextran. In semi-synthetic systems, fiber polymers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, starch polymers such as sodium starch glycolate and sodium starch phosphate, sodium alginate, propylene glycol alginate And seaweed polymers such as Pure synthetic systems include polyvinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl methyl ether, non-crosslinked polyacrylamide, polyacrylic acid or alkali metal salts thereof, acrylic resins such as water-soluble styrene acrylic resins, and water-soluble styrene malees. Acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic resin, polyvinyl pyrrolidone, polyvinyl alcohol, alkali metal salt of β-naphthalene sulfonic acid formalin condensate, cationic functional group such as quaternary ammonium and amino group Examples thereof include a polymer compound having a salt in the side chain and a natural polymer compound such as shellac. Among these, those having a carboxyl group introduced from a homopolymer of acrylic acid, methacrylic acid or styrene acrylic acid or a copolymer of a monomer having another hydrophilic group are particularly preferred as the polymer dispersant.

  Here, the weight average molecular weight of the copolymer is preferably 3,000 to 50,000, more preferably 5,000 to 30,000, and still more preferably 7,000 to 15,000.

  The mixing mass ratio of the pigment and the dispersant (pigment: dispersant) is preferably 1: 0.06 to 1: 3, and more preferably 1: 0.125 to 1: 3.

  The addition amount of the colorant in the ink is preferably 6 to 15% by mass, and more preferably 8 to 12% by mass. When the addition amount is less than 6% by mass, the image density may be lowered due to a decrease in coloring power, or feathering or bleeding may be deteriorated due to a decrease in viscosity. If the nozzle is left unattended, the nozzles will be easy to dry, non-ejection phenomenon will occur, the viscosity will be too high, the permeability will decrease, and the dots will not spread, so the image density will decrease. Or a blurred image.

-Wetting agent-
There is no restriction | limiting in particular as a wetting agent, According to the objective, it can select suitably, For example, at least 1 sort (s) selected from a polyol compound, a lactam compound, a urea compound, and saccharides is suitable.

  Here, examples of the polyol compound include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, and carbonic acid. Ethylene, and the like. These may be used alone or in combination of two or more.

  Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,3-purpandiol, 1,3-butanediol, 1,4 butanediol, and 3-methyl-1. , 3-butanediol 1,3-propanediol, 1,5-pentanediol, 1,6 hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3- Examples include butanetriol and petriol.

  Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, and the like. .

  Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

  Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam.

  Examples of amides include formamide, N-methylformamide, formamide, N, N-dimethylformamide and the like.

  Examples of amines include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine.

  Examples of sulfur-containing compounds include dimethyl sulfoxide, sulfolane, thiodiethanol, and the like.

  Among these, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1 from the viewpoint of obtaining excellent effects on solubility and prevention of poor jetting characteristics due to water evaporation , 3-butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol 1,3-propanediol, 1,5-pentanediol, tetraethylene glycol, 1, 6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1,2,6-hexanetriol, thiodiglycol, 2-pyrrolidone, N-methyl-2 -Pyrrolidone, N-hydroxyethyl-2-pi Pyrrolidone is preferred.

  Examples of the lactam compound include at least one selected from 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, and ε-caprolactam.

  Examples of the urea compound include at least one selected from urea, thiourea, ethylene urea, and 1,3-dimethyl-2-imidazolidinone. In general, the amount of urea added to the ink is preferably 0.5 to 50% by mass, and more preferably 1 to 20% by mass.

  Examples of the saccharide include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), polysaccharides, and derivatives thereof. Among these, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, and maltotriose are preferable, and maltose, sorbitol, gluconolactone, and maltose are particularly preferable.

  The above-mentioned polysaccharide means a saccharide in a broad sense and can be used to include substances widely existing in nature such as α-cyclodextrin and cellulose.

Derivatives of sugars include reducing sugars of sugars (for example, sugar alcohol (however, represented by the general formula: HOCH ₂ (CHOH) nCH ₂ OH (where n represents an integer of 2 to 5)), oxidized sugar (For example, aldonic acid, uronic acid, etc.), amino acids, thioic acid, etc. Among these, sugar alcohol is particularly preferable, and examples of the alcohol include maltitol, sorbit, and the like.

  Moreover, 10-50 mass% is preferable and, as for content in the ink of a wetting agent, 20-35 mass% is more preferable. If the content is too small, the nozzle is likely to be dried and defective ejection of droplets may occur. If the content is too large, the ink viscosity is increased, and the proper viscosity range may be exceeded.

-Penetration agent-
As the penetrant, a water-soluble organic solvent such as a polyol compound or a glycol ether compound is used. In particular, at least one of a polyol compound having 8 or more carbon atoms and a glycol ether compound is preferably used.

  Here, if the polyol compound has less than 8 carbon atoms, sufficient penetrability cannot be obtained, and the recording medium is soiled during double-sided printing, or the ink spread on the recording medium is insufficient and the pixels are filled. May deteriorate character quality and image density.

  Examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol (solubility: 4.2% (25 ° C.)), 2,2,4-trimethyl-1,3-pentanediol ( Solubility: 2.0% (25 ° C.)) is preferable.

  The glycol ether compound is not particularly limited and may be appropriately selected depending on the intended purpose.For example, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetra Examples include polyhydric alcohol alkyl ethers such as ethylene glycol monomethyl ether and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

  Moreover, there is no restriction | limiting in particular in the addition amount of a penetrant, Although it can select suitably according to the objective, 0.1-20 mass% is preferable and 0.5-10 mass% is more preferable.

-Surfactant-
There is no restriction | limiting in particular as said surfactant, According to the objective, it can select suitably, For example, anionic surfactant, nonionic surfactant, amphoteric surfactant, fluorine type surfactant etc. are mentioned. .

  Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, polyoxyethylene alkyl ether sulfate salt, and the like.

  Examples of nonionic surfactants include acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, and the like.

  Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3, 5-dimethyl-1-hexyn-3-ol and the like. Examples of commercially available acetylene glycol surfactants include Surfynol 104, 82, 465, 485, and TG manufactured by Air Products (USA).

  Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine. Specific examples include lauryl dimethylamine oxide, myristyl dimethylamine oxide, stearyl dimethylamine oxide, dihydroxyethyl lauryl amine oxide, polyoxyethylene coconut oil alkyl dimethyl amine oxide, dimethyl alkyl (coconut) betaine, dimethyl lauryl betaine, and the like. It is done.

  Among these surfactants, surfactants represented by the following general formulas (I), (II), (III), (IV), (V), and (VI) are preferable.

ただし、前記一般式（Ｉ）中、Ｒ１は、アルキル基を表し、炭素数６〜１４の分岐していてもよいアルキル基を表す。ｈは、３〜１２の整数を表す。Ｍは、アルカリ金属イオン、第４級アンモニウム、第４級ホスホニウム、及びアルカノールアミンから選択されるいずれかを表す。

However, in the said general formula (I), R1 represents an alkyl group and represents the C6-C14 alkyl group which may be branched. h represents an integer of 3 to 12. M represents one selected from alkali metal ions, quaternary ammonium, quaternary phosphonium, and alkanolamine.

ただし、前記一般式（ＩＩ）中、Ｒ２は、アルキル基を表し、炭素数５〜１６の分岐していてもよいアルキル基を表す。Ｍは、アルカリ金属イオン、第４級アンモニウム、第４級ホスホニウム、及びアルカノールアミンから選択されるいずれかを表す。

However, in the said general formula (II), R2 represents an alkyl group and represents the C5-C16 alkyl group which may be branched. M represents one selected from alkali metal ions, quaternary ammonium, quaternary phosphonium, and alkanolamine.

ただし、上記一般式（ＩＩＩ）中、Ｒ３は、炭化水素基を表し、例えば、分岐していてもよい炭素数６〜１４のアルキル基を表す。ｋは５〜２０の整数を表す。

However, in said general formula (III), R3 represents a hydrocarbon group, for example, the C6-C14 alkyl group which may be branched. k represents an integer of 5 to 20.

ただし、上記一般式（ＩＶ）中、Ｒ４は、炭化水素基を表し、例えば、炭素数６〜１４のアルキル基を表す。ｊは、５〜２０の整数を表す。

However, in said general formula (IV), R4 represents a hydrocarbon group, for example, a C6-C14 alkyl group. j represents an integer of 5 to 20.

ただし、上記一般式（Ｖ）中、Ｒ^６は、炭化水素基を表し、例えば、炭素数６〜１４の分岐していてもよいアルキル基を表す。Ｌ及びｐは、１〜２０の整数を表す。

However, in the general formula (V), R ⁶ represents a hydrocarbon group, for example, represents an alkyl group which may be branched having 6 to 14 carbon atoms. L and p represent an integer of 1 to 20.

ただし、上記一般式（ＶＩ）中、ｑ及びｒは０〜４０の整数を表す。

However, in said general formula (VI), q and r represent the integer of 0-40.

  Hereinafter, the surfactants of the structural formulas (I) and (II) are specifically shown in the free acid form. First, examples of the surfactant (I) include those represented by the following (I-1) to (I-6).

  Next, examples of the surfactant (II) include those represented by the following (II-1) to (II-4).

  As the fluorosurfactant, those represented by the following general formula (A) are suitable.

ただし、前記一般式（Ａ）中、ｍは、０〜１０の整数を表す。ｎは、１〜４０の整数を表す。

However, in said general formula (A), m represents the integer of 0-10. n represents an integer of 1 to 40.

  Examples of the fluorine-based surfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic compound, a perfluoroalkyl phosphate compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. And polyoxyalkylene ether polymer compounds. Among these, the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain has a low foaming property, and the bioaccumulation property of a fluorine compound that has been regarded as a problem in recent years is low and highly safe. Particularly preferred.

  Here, examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like.

  Moreover, as a perfluoroalkyl carboxylic compound, perfluoroalkyl carboxylic acid, perfluoroalkyl carboxylate, etc. are mentioned, for example.

Examples of the perfluoroalkyl phosphate compound include perfluoroalkyl phosphate esters, perfluoroalkyl phosphate salts, and the like.
The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, and a polyoxyalkylene having a perfluoroalkyl ether group in the side chain. Examples thereof include sulfuric acid ester salts of ether polymers and salts of polyoxyalkylene ether polymers having a perfluoroalkyl ether group in the side chain.

Counter ions of salts in these fluorinated _{surfactants, Li, Na, K, NH4} , NH 3 CH 2 CH 2 OH, NH 2 (CH 2 CH 2 OH) 2, NH (CH 2 CH 2 OH) 3 Etc.

As a fluorine-type surfactant, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.), Fullrad FC- 93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M), MegaFuck F-470, F1405, F-474 ( All manufactured by Dainippon Ink and Chemicals), Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont), FT-110, FT-250 FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), PF-151N (manufactured by Omninova), and the like. It is done. Among these, Zonyl FS-300, FSN, FSN-100, and FSO (manufactured by DuPont) are particularly preferable from the viewpoints of reliability and color development improvement.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected as necessary. For example, resin emulsion, pH adjuster, antiseptic / antifungal agent, rust inhibitor, antioxidant, ultraviolet absorber, oxygen absorber Agents, light stabilizers, and the like.

-Resin emulsion-
The resin emulsion is obtained by dispersing resin fine particles in water as a continuous phase, and may contain a dispersant such as a surfactant as necessary.

  The content of resin fine particles as a dispersed phase component (content of resin fine particles in the resin emulsion) is generally preferably 10 to 70% by mass. Further, the particle diameter of the resin fine particles is preferably 10 to 1000 nm, more preferably 20 to 300 nm, particularly considering use in an ink jet recording apparatus.

  The resin fine particle component of the dispersed phase is not particularly limited and can be appropriately selected depending on the purpose. For example, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, Examples include vinyl chloride resins, acrylic styrene resins, acrylic silicone resins, and among these, acrylic silicone resins are particularly preferable.

As a resin emulsion, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of commercially available resin emulsions include microgel E-1002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.). Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion, Seiden) Chemical Co., Ltd.), Primal AC-22, AC-61 (acrylic resin emulsion, manufactured by Rohm and Haas), Nanoacryl SBCX-2821, 3689 (acrylic silicone resin emulsion, Toyo Ink Manufacturing Co., Ltd.) Company Ltd.), # 3070 (methyl methacrylate polymer resin emulsion, manufactured by Mikuni Color Ltd.).

  The addition amount of the resin fine particle component in the resin emulsion in the ink is preferably 0.1 to 50% by mass, more preferably 0.5 to 20% by mass, and still more preferably 1 to 10% by mass. If the addition amount is less than 0.1% by mass, the effect of improving clogging resistance and ejection stability may not be sufficient, and if it exceeds 50% by mass, the storage stability of the ink may be reduced. There is.

  Examples of antiseptic / antifungal agents include 1,2-benzisothiazolin-3-one, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, etc. Is mentioned.

  The pH adjuster is not particularly limited as long as the pH can be adjusted to 7 or more without adversely affecting the ink, and any substance can be used according to the purpose.

  Examples of the pH adjusting agent include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonium hydroxide, quaternary ammonium hydroxide, Examples thereof include quaternary phosphonium hydroxide, alkali metal carbonates such as lithium carbonate, sodium carbonate, and potassium carbonate.

  Examples of the rust preventive agent include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Examples of the antioxidant include phenolic antioxidants (including hindered phenolic antioxidants), amine-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants.

  Examples of phenolic antioxidants (including hindered phenolic antioxidants) include butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionate, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4 , 4′-Butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) Propionyloxy] ethyl] 2,4,8,10-tetrixaspiro [5,5] undecane, 1,1,3-tris (2-methyl-4- Hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, and the like.

  Examples of amine-based antioxidants include phenyl-β-naphthylamine, α-naphthylamine, N, N′-di-sec-butyl-p-phenylenediamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol, butylhydroxyanisole, 2,2′-methylenebis (4 -Methyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), tetrakis [methylene- 3 (3,5-di-tert-butyl-4-dihydroxyphenyl) propionate] methane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, and the like.

  Examples of the sulfur-based antioxidant include dilauryl 3,3′-thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl β, β′-thiodipropionate, 2-mercaptobenzimidazole, dilauryl sulfide and the like can be mentioned.

  Examples of phosphorus antioxidants include triphenyl phosphite, octadecyl phosphite, triisodecyl phosphite, trilauryl trithiophosphite, and trinonylphenyl phosphite.

  Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, salicylate UV absorbers, cyanoacrylate UV absorbers, nickel complex salt UV absorbers, and the like.

  Examples of the benzophenone-based ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, and the like.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- ( 2'-hydroxy-4'-octoxyphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, and the like.

  Examples of salicylate-based ultraviolet absorbers include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and the like.

  Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3′-diphenyl acrylate, methyl-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate, and butyl-2-cyano. -3-methyl-3- (p-methoxyphenyl) acrylate, and the like.

  Examples of the nickel complex ultraviolet absorber include nickel bis (octylphenyl) sulfide, 2,2′-thiobis (4-tert-octylferrate) -n-butylamine nickel (II), 2,2′-thiobis ( 4-tert-octylferrate) -2-ethylhexylamine nickel (II), 2,2′-thiobis (4-tert-octylferrate) triethanolamine nickel (II), and the like.

  The ink in the ink media set of the present invention comprises at least water, a colorant, and a wetting agent, and if necessary, a penetrating agent, a surfactant, and, if necessary, other components dispersed or dissolved in an aqueous medium, Produced by stirring and mixing as necessary. The dispersion can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, etc., and stirring and mixing are performed by a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like. be able to.

  The viscosity of the ink is preferably 1 cps or more and 30 cps or less at 25 ° C., more preferably 2 to 20 cps. If the viscosity exceeds 20 cps, it may be difficult to ensure ejection stability.

  The pH of the ink is preferably 7 to 10, for example.

  There is no restriction | limiting in particular as coloring of an ink, According to the objective, it can select suitably, Yellow, magenta, cyan, black etc. are mentioned. When recording is performed using an ink set in which two or more of these colorings are used in combination, a multicolor image can be formed. When recording is performed using an ink set in which all colors are combined, a full color image is formed. be able to.

  Next, specific examples will be described. Note that the present invention is not limited to these examples.

(Preparation Example 1)
-Preparation of copper phthalocyanine pigment-containing polymer fine particle dispersion-
After sufficiently replacing the inside of the 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas introduction tube, reflux tube, and dropping funnel with nitrogen gas, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate Then, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer (manufactured by Toa Gosei Co., Ltd., trade name: AS-6) and 0.4 g of mercaptoethanol were charged and heated to 65 ° C. Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxyethyl methacrylate, styrene macromer (trade name: AS-6, manufactured by Toagosei Co., Ltd.) A mixed solution of 36.0 g, mercaptoethanol 3.6 g, azobisdimethylvaleronitrile 2.4 g, and methyl ethyl ketone 18 g was dropped into the flask over 2.5 hours.

  After completion of dropping, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobisdimethylvaleronitrile was added and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a concentration of 50% by mass. Next, a part of the polymer solution was dried and measured by gel permeation chromatography (standard: polystyrene, solvent: tetrahydrofuran). The weight average molecular weight (Mw) was 15,000.

Next, 28 g of the obtained polymer solution, 26 g of copper phthalocyanine pigment, 13.6 g of 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 30 g of ion-exchanged water were sufficiently stirred. Thereafter, the mixture was kneaded 20 times using a three-roll mill (manufactured by Noritake Company, trade name: NR-84A). The obtained paste was put into 200 g of ion-exchanged water, and after sufficiently stirring, methyl ethyl ketone and water were distilled off using an evaporator to obtain 160 g of a blue polymer fine particle dispersion having a solid content of 20.0% by mass. .
About the obtained polymer microparticles | fine-particles, the average particle diameter (D50%) measured with the particle size distribution analyzer (Microtrac UPA, Nikkiso Co., Ltd.) was 93 nm.

(Preparation Example 2)
-Preparation of dimethylquinacridone pigment-containing polymer fine particle dispersion-
In Preparation Example 1, the copper phthalocyanine pigment was changed to C.I. I. A red-purple polymer fine particle dispersion was prepared in the same manner as in Preparation Example 1, except that the pigment red 122 was used.
About the obtained polymer microparticles | fine-particles, the average particle diameter (D50%) measured with the particle size distribution analyzer (Microtrac UPA, Nikkiso Co., Ltd.) was 127 nm.

(Preparation Example 3)
-Preparation of monoazo yellow pigment-containing polymer fine particle dispersion-
In Preparation Example 1, the copper phthalocyanine pigment was changed to C.I. I. A yellow polymer fine particle dispersion was prepared in the same manner as in Preparation Example 1, except that the pigment yellow 74 was changed.
About the obtained polymer microparticles | fine-particles, the average particle diameter (D50%) measured with the particle size distribution analyzer (Microtrac UPA, Nikkiso Co., Ltd.) was 76 nm.

(Preparation Example 4)
-Preparation of carbon black dispersion treated with sulfonating agent-
150 g of commercially available carbon black pigment (manufactured by Degussa, “Printex # 85”) was mixed well into 400 ml of sulfolane, finely dispersed with a bead mill, 15 g of amidosulfuric acid was added, and the mixture was stirred at 140 to 150 ° C. for 10 hours. The obtained slurry was put into 1000 ml of ion-exchanged water, and a surface-treated carbon black wet cake was obtained with a centrifuge at 12,000 rpm. The obtained carbon black wet cake is redispersed in 2,000 ml of ion exchange water, adjusted to pH with lithium hydroxide, desalted and concentrated with an ultrafiltration membrane, and a carbon black dispersion having a pigment concentration of 10% by mass. And filtering with a nylon filter having an average pore diameter of 1 μm to obtain a carbon black dispersion.
About the obtained carbon black dispersion, the average particle diameter (D50%) measured with the particle size distribution analyzer (Microtrac UPA, Nikkiso Co., Ltd.) was 80 nm.

(Production Example 1)
-Production of cyan ink-
Copper phthalocyanine pigment-containing polymer fine particle dispersion 20.0% by mass of Preparation Example 1, 3-methyl-1,3-butanediol 23.0% by mass, glycerin 8.0% by mass, 2-ethyl-1,3-hexane 2.0% by mass of diol, 2.5% by mass of FS-300 (manufactured by DuPont) as a fluorosurfactant, 0.2% by mass of Proxel LV (manufactured by Avecia) as an antiseptic / antifungal agent, 2-amino Appropriate amounts of 2-ethyl-1,3-propanediol 0.5% by mass and ion-exchanged water were added to obtain 100% by mass, followed by filtration through a membrane filter having an average pore size of 0.8 μm. A cyan ink was prepared as described above.

(Production Example 2)
-Magenta ink production-
Dimethylquinacridone pigment-containing polymer fine particle dispersion 20.0% by mass of Preparation Example 2, 3-methyl-1,3-butanediol 22.5% by mass, glycerin 9.0% by mass, 2-ethyl-1,3-hexane 2.0% by mass of diol, 2.5% by mass of FS-300 (manufactured by DuPont) as a fluorosurfactant, 0.2% by mass of Proxel LV (manufactured by Avecia) as an antiseptic / antifungal agent, 2-amino Appropriate amounts of 2-ethyl-1,3-propanediol 0.5% by mass and ion-exchanged water were added to obtain 100% by mass, followed by filtration through a membrane filter having an average pore size of 0.8 μm. A magenta ink was prepared as described above.

(Production Example 3)
-Preparation of yellow ink-
Monoazo yellow pigment-containing polymer fine particle dispersion of Preparation Example 2 20.0% by mass, 3-methyl-1,3-butanediol 24.5% by mass, glycerin 8.0% by mass, 2-ethyl-1,3-hexane 2.0% by mass of diol, 2.5% by mass of FS-300 (manufactured by DuPont) as a fluorosurfactant, 0.2% by mass of Proxel LV (manufactured by Avecia) as an antiseptic / antifungal agent, 2-amino Appropriate amounts of 2-ethyl-1,3-propanediol 0.5% by mass and ion-exchanged water were added to obtain 100% by mass, followed by filtration through a membrane filter having an average pore size of 0.8 μm. Thus, a yellow ink was prepared.

(Production Example 4)
-Preparation of black ink-
Carbon black dispersion of Preparation Example 4 20.0% by mass, 2-methyl-1,3-butanediol 22.5% by mass, glycerin 7.5% by mass, 2-pyrrolidone 2.0% by mass, 2-ethyl- 2.0 mass% of 1,3-hexanediol, 2.5 mass% of FS-300 (manufactured by DuPont) as a fluorosurfactant, 0.2 mass of Proxel LV (manufactured by Avecia) as an antiseptic and fungicidal agent %, 2-amino-2-ethyl-1,3-propanediol 0.5% by mass and ion exchanged water are added in an appropriate amount to 100% by mass, and then filtered through a membrane filter having an average pore size of 0.8 μm. It was. A black ink was prepared as described above.

  Next, the surface tension and viscosity of each of the inks of Production Examples 1 to 4 obtained were measured as follows. The results are shown in Table 1.

<Measurement of viscosity>
The viscosity was measured at 25 ° C. using a R-500 viscometer (manufactured by Toki Sangyo Co., Ltd.) under conditions of cone 1 ° 34 ′ × R24, 60 rpm, 3 minutes later.

<Measurement of surface tension>
The surface tension is a static surface tension measured at 25 ° C. using a platinum plate using a surface tension measuring device (CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.).

-Production of support-
A 0.3 mass% slurry having the following composition was made with a long paper machine to prepare a support having a basis weight of 79 g / m2. In addition, in the size press process of the papermaking process, the oxidized starch aqueous solution was applied so that the solid content was 1.0 g / m ² per side.
-Hardwood bleached kraft pulp (LBKP) ... 80 parts by mass-Softwood bleached kraft pulp (NBKP) ... 20 parts by weight-Light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.) ... 10 parts by weight-Aluminum sulfate 1.0 part by mass-Amphoteric starch (trade name: Cato3210, manufactured by Nippon NSC Co., Ltd.) ... 1.0 part by mass-Neutral rosin sizing agent (trade name: NeuSize M-10, manufactured by Harima Kasei Co., Ltd.) ... 0. 3 parts by mass-Yield improver (trade name: NR-11LS, manufactured by Hymo Co., Ltd.) ... 0.02 parts by mass

(Production Example 1)
-Production of recording medium 1-
70 parts by mass of clay having a particle diameter of 2 μm or less as a pigment of 97% by mass, 30 parts by mass of heavy calcium carbonate having an average particle diameter of 1.1 μm, and styrene having a glass transition temperature (Tg) of −5 ° C. as an adhesive -Add 8 parts by weight of butadiene copolymer emulsion, 1 part by weight of phosphate esterified starch, and 0.5 parts by weight of calcium stearate as an auxiliary agent, and then add water to obtain a coating solution having a solid content concentration of 60% by weight. Prepared.

  The obtained coating solution is applied to both sides using a blade coater so that the solid content per side is 8 g / m 2 on the prepared support, dried with hot air, and then subjected to a step super calendar process. “Recording medium 1” was produced.

(Production Example 2)
-Production of recording medium 2-
70 parts by mass of clay having a particle diameter of 2 μm or less as a pigment of 97% by mass, 30 parts by mass of heavy calcium carbonate having an average particle diameter of 1.1 μm, and styrene having a glass transition temperature (Tg) of −5 ° C. as an adhesive -Addition of 7 parts by mass of butadiene copolymer emulsion, 0.7 parts by mass of phosphoric acid esterified starch, 0.5 parts by mass of calcium stearate as an auxiliary agent, and further water to add a coating solution having a solid content concentration of 60% by mass Was prepared.

  The obtained coating solution was coated on both sides using a blade coater so that the solid content per side was 8 g / m 2 on the prepared support, dried with hot air, and then subjected to a step super calendar treatment. “Recording medium 2” was produced.

Example 1
-Ink set, recording media, and image recording-
“Ink set 1” consisting of black ink of Production Example 4, yellow ink of Production Example 3, magenta ink of Production Example 2 and cyan ink of Production Example 1 was prepared by a conventional method.
Using the obtained ink set 1 and the recording medium 1 described above, printing is performed at an image resolution of 600 dpi and a maximum ink droplet of 18 pl using a drop-on-demand printer prototype having 300 dpi, nozzle resolution 384, and nozzles. It was. The amount of secondary color was regulated to 140% and the amount of adhesion was regulated, and solid images and characters were printed to obtain an image print.

(Example 2)
-Ink set, recording media, and image recording-
In Example 1, except that the recording medium 2 was used as a recording medium, printing was performed in the same manner as in Example 1 to obtain an image print.

(Example 3)
-Ink set, recording media, and image recording-
In Example 1, a coated paper for gravure printing (trade name; space DX, basis weight = 56 g / m ² , manufactured by Nippon Paper Industries Co., Ltd.) (hereinafter referred to as “recording medium 3”) was used as the recording medium. Except for the above, printing was performed in the same manner as in Example 1 to obtain an image print.

  Next, with respect to the recording media used in the recording medium 1, the recording medium 2, and the recording medium 3, transfer of pure water by the dynamic scanning absorption meter and cyan ink of Production Example 1 were performed as follows. The amount was measured. The results are shown in Table 2.

<Measurement of transfer amount of pure water and cyan ink by dynamic scanning absorption meter>
For each recording medium, the transfer amount of pure water or cyan ink was measured at 25 ° C. and 50% RH using a dynamic scanning absorption meter (K350 series D type, manufactured by Kyowa Seiko Co., Ltd.). The transfer amount at the contact time of 100 ms and the contact time of 400 ms was determined by interpolation from the measured value of the transfer amount at the contact time adjacent to each contact time.

  Next, for each of the obtained image prints of Examples 1 to 3, beading, bleeding, spur marks, and gloss were evaluated as follows. The results are shown in Table 3.

<Beading>
The degree of beading of the green solid image portion of each image print was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: Uniform printing without beading.
○: Slight beading is observed.
(Triangle | delta): Generation | occurrence | production of beading is recognized clearly.
×: Significant beading is observed.

<Evaluation of bleed>
The degree of bleed of black letters in the yellow of each image print was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: Clear printing without bleeding.
○: Slight bleeding is observed.
X: The blur has occurred so that the outline of the character is not clear.

<Evaluation of spur marks>
The degree of spurs on each image print was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: Not recognized at all.
○: Slightly recognized.
X: Spur marks are clearly recognized.

<Evaluation of glossiness>
The degree of glossiness of the image portion of each image print was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: High gloss.
○: Glossy.
X: A glossiness is not recognized.

It is an exploded perspective view showing an example of a liquid discharge head concerning the present invention. It is sectional explanatory drawing along the liquid chamber longitudinal direction of the head. FIG. 3 is an enlarged view of a main part of FIG. 2. It is sectional explanatory drawing of the bipitch structure along the liquid chamber transversal direction of the head. It is sectional explanatory drawing of the normal pitch structure along the liquid chamber transversal direction of the head. It is principal part expanded sectional explanatory drawing of the nozzle plate of the head. It is a principal part expanded sectional enlarged view of FIG. It is principal part expanded sectional explanatory drawing which shows the other example of the head. It is an expanded sectional explanatory view used for description of the nozzle plate of a comparative example. It is explanatory drawing which shows an example of the experimental result of the relationship between the presence or absence of an oxide film, and peeling of a water repellent layer. It is explanatory drawing which shows an example of the experimental result of the relationship between the presence or absence of a liquid-resistant film (oxide film) and the elution of the nozzle substrate with respect to the characteristics of the ink. It is sectional explanatory drawing with which it uses for description of an example of the manufacturing method of the liquid discharge head which concerns on this invention. 1 is an overall configuration diagram illustrating an example of an image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Channel formation member 2 ... Diaphragm 3 ... Nozzle plate (nozzle formation member)
DESCRIPTION OF SYMBOLS 4 ... Nozzle 6 ... Liquid chamber 12 ... Piezoelectric element 31 ... Nozzle base material 32 ... Water-repellent layer (silicone resin layer)
34 ... Nozzle hole 35 ... Oxide film 36 ... Natural oxide film 50 ... Dispenser 103 ... Carriage 107 ... Recording head 158 ... Wiper blade

Claims (2)

In a liquid discharge head comprising a nozzle forming member in which a water repellent layer is formed on the surface of a droplet discharge side of a nozzle base material in which nozzle holes for discharging recording liquid droplets are formed,
A natural oxide film is formed on the droplet discharge side surface of the nozzle substrate,
A water repellent layer made of silicone resin is formed on the surface of the natural oxide film,
A liquid discharge head, wherein an oxide film thicker than the natural oxide film is formed on an inner wall surface of a nozzle hole of the nozzle base material. An image forming apparatus comprising the liquid discharge head according to claim 1 .

Images