JP2008055832A - Liquid ejection head, image forming apparatus, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejection head with excellent clogging resistance, which provides constantly proper intermittent ejection stability even in a low-humidity environment, and which is easily restored to a normal jetting state even under such an abnormal condition that a nozzle surface is left uncapped. <P>SOLUTION: In this liquid ejection head, a water-repellently treated film is formed on the liquid droplet ejection-side surface of a nozzle substrate 1 in which a nozzle hole 11 for ejecting a pigment-based ink is formed, and an approximately circular recess 12, inside which the water-repellently treated film is not formed, is formed on the periphery of each nozzle hole 11. The recess 12 is formed in such a shape as to satisfy a relational expression: d≥D(1-sinθ)/2cosθ. In the relational expression, D represents the diameter of the recess 12; d represents the depth of the recess 12; and θ represents an angle of contact between the recess 12 and a liquid to be ejected. The nozzle substrate 1, which forms the bottom of the recess 12, is formed in such a shape that its thickness is greater in dimension than the depth of the recess 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, or a multifunction machine of these, for example, a liquid (e.g., a liquid ejecting apparatus) including a recording head composed of a liquid ejecting head that ejects liquid droplets of recording liquid (liquid) is used. Hereinafter, although it is also referred to as “paper”, the material is not limited, and a recording medium as a liquid (hereinafter, referred to as “recording medium”, “recording medium”, “transfer material”, “recording paper” and the like is also used synonymously). Some of them perform image formation (recording, printing, printing, and printing are also used synonymously) by attaching the ink to the paper.

  The image forming apparatus means an apparatus for forming an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. The term “not only” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium. Further, the liquid is not limited to the recording liquid and ink, and is not particularly limited as long as it is a liquid capable of forming an image. Further, the liquid ejection apparatus means an apparatus that ejects liquid from a liquid ejection head, and is not limited to an apparatus that forms an image.

  By the way, since a liquid discharge head performs recording by discharging droplets from nozzles (also referred to as discharge ports and openings), the shape and accuracy of the nozzles have a great influence on the droplet ejection characteristics. Various proposals have been made regarding the nozzle shape and surface treatment.

For example, Patent Document 1 discloses that a nozzle substrate has a water-repellent film on the ink ejection side surface, a nozzle forming member that forms the nozzle, and an ink liquid chamber that is bonded to the surface opposite to the ink ejection side of the nozzle substrate. And a liquid chamber constituent member wafer in which the nozzle forming member and the plurality of liquid chamber constituent members are integrally arranged when the nozzle forming member and the liquid chamber constituent member are joined. After joining, the nozzle is processed into a nozzle forming member and cut into a predetermined size to form a chip.
JP 2004-181893 A

Patent Document 2 discloses a liquid flow channel, a discharge port forming member that forms a part of the wall of the liquid flow channel and has a discharge port for discharging liquid as droplets, and a discharge port on the wall of the liquid flow channel And a heating element that generates bubbles in the liquid by applying heat to the liquid, and the discharge port is concave with respect to the surface on which the discharge port of the discharge port forming member is opened. A restrictor is provided at the position, and the liquid is held in a discharge port so as to form a meniscus so that the restrictor is located in the liquid, and the area of the opening area of the restrictor is So, and the surface area of the heating element is Sh , A liquid discharge head that satisfies the relationship So ≦ Sh is described.
JP 2003-154655 A

In Patent Document 3, a parent ink liquid region is formed around a nozzle opening, an ink repellent liquid region is formed around the parent ink liquid region, and the parent ink liquid region is recessed from the ink repellent liquid region. An inkjet head is described.
JP 05-193141 A

Patent Document 4 describes an inkjet head in which a counterbore (recess) is formed around an orifice on the outer surface of a nozzle plate, and a water-repellent portion is formed outward from the inner peripheral edge of the counterbore.
Japanese Patent Laid-Open No. 11-334069

In Patent Document 5, the nozzle opening includes a first protrusion provided around the nozzle outlet that discharges ink, a stepped portion provided at a position lower than the first protrusion on the outside, and a step. An ink jet head is described which is composed of a second protrusion provided at a position higher than the first protrusion on the outside of the first protrusion, and the second protrusion is subjected to ink repellent treatment.
JP 2004-268359 A

In Patent Document 6, a recess corresponding to the orifice is formed as a non-through hole in the flow path forming member that forms the orifice, and the recess is formed by performing stepping processing on the region including the position of the orifice from the back surface side of the recess. A method of manufacturing an ink jet recording head that penetrates and reveals an orifice is described.
Japanese Patent Laid-Open No. 10-109423

In Patent Document 7, a recording liquid introduction unit, a liquid holding unit that holds the recording liquid introduced by the recording liquid introduction unit, and a bubble that is disposed in the held recording liquid are generated in the recording liquid. And an opening forming member having an opening for allowing a part of the recording liquid to fly, which is formed in a round opening area larger than the working area of the energy acting portion corresponding to each energy acting portion. A liquid flight recording apparatus is described in which a protrusion having a height of 0.3 μm or more is formed around the opening on the surface of the recording member side of the opening forming member so as to form a region that forms an area larger than the opening. ing.
Japanese Patent No. 317934

  By the way, as the ink used for image recording by the ink jet recording method, water-based ink using water as a main solvent is generally used. As a colorant for water-based ink, it is common to use a water-soluble dye. Since water-soluble dyes are completely dissolved in the ink medium, if the impurities in the water-soluble dye are controlled to a certain level or less, they will not clog at the tip of the head or in the ink flow path, and will have a clear color tone. It is possible to obtain a recorded matter of concentration.

  However, since water-soluble dyes are inherently poor in light fastness and image fastness is not sufficient, water-based pigment inks using pigments such as carbon black are used to give recorded images light resistance and water resistance. There is also something like that.

  In any case, the inkjet water-based ink does not cause clogging in the head end of the image forming apparatus or in the ink flow path, and can be stably ejected, and has a sufficiently high density recording with a clear color tone. Performance such as obtaining images is required.

  Here, the ejection stability of ink indicates the following two phenomena. That is, a recording apparatus using water-based ink is generally provided with a maintenance and recovery mechanism that covers the ejection nozzle holes of the recording head in a sealed state with a cap member when the ejection is not performed. This is to prevent nozzle clogging and jet bending due to drying and thickening of ink components at the nozzle tip of the recording head (hereinafter referred to as “clogging resistance”), and is effective to some extent under normal use conditions. However, if the nozzle cap is not used for a very long time or the airtightness of the nozzle cap is lowered for some reason, nozzle clogging occurs.

  Even under such abnormal use conditions, in normal printing, there are few cases where ink is ejected from all the nozzles of the head, and based on image signals from nozzles that have not ejected ink for a relatively long time. Even when ink is ejected, nozzle clogging, ejection bending, or ejection speed reduction may occur (hereinafter referred to as “intermittent ejection stability”). In particular, it is a serious problem in printing in a low humidity environment.

  In particular, in the above-described pigment ink, problems with respect to nozzle clogging and jet bending due to drying and thickening of ink components as described above become more important. For example, if the head nozzle is left uncapped for a long time, ink thickening, precipitation, and nozzle clogging due to drying will occur, making it almost impossible to recover to a normal ejection state. Further, the positional deviation of the image dots due to a decrease in intermittent ejection stability also becomes a problem. In particular, since the nozzle diameter and dot size are being miniaturized recently in order to achieve further higher image density, there is a further problem of ejection stability (clogging resistance and intermittent ejection stability) due to nozzle drying. There is a growing need for countermeasures. Furthermore, in the electrostatic type head that is expected in the future with downsizing and low power consumption, the ink ejection force is not so large compared with other methods (for example, piezoelectric type head and thermal type head). In some cases, it is necessary to take measures against the ejection stability due to the nozzle drying described above.

  Although Patent Documents 3 and 4 described above describe forming a recess around the nozzle hole, the depth and shape of the recess are appropriately determined without any basis, or the depth of the recess is set. The meniscus is in contact with the inner periphery of the nozzle hole during non-printing (Patent Document 4). However, according to experiments by the present inventors, in the nozzle forming member having such a configuration, when the nozzle surface (surface on the droplet discharge side) is left as it is for one day without being attached with the cap by the cap member, the nozzle It was confirmed that clogging occurred and discharge became unstable.

  Further, as described in Patent Document 2, the discharge port is provided with a throttle portion at a position that is concave with respect to the surface where the discharge port is opened, and the liquid is discharged so that the throttle portion is located in the liquid. The present inventor has a head that is configured to satisfy the relationship of So ≦ Sh when the meniscus is formed and held in the mouth, and the area So of the aperture region of the diaphragm and the surface area of the heating element are Sh. According to these experiments, when a large amount of energy was generated to break the liquid reservoir in the recess and eject the liquid droplets, the strength of the recess in the nozzle forming member was lower than that of a normal dye-based ink. It has been found that when high-viscosity pigment-based ink is ejected, the ejection energy is used for vibration of the nozzle forming member and the ejection efficiency is greatly reduced.

  Further, in Patent Document 5, as a specific configuration, a step portion is provided around the nozzle, the contact angle with water on the nozzle surface is 100 ° or more, the contact angle with water on the step portion is 55 ° or less, and a depth of 20 Although it is described that the diameter is about 50 μm and the diameter is 200 to 500 μm, the value of the contact angle with water and the contact angle with the ink used here are completely different, and the actual contact angle with water depends on the contact angle with water. The shape of the meniscus formed on the nozzle with this ink cannot be defined, and therefore the nozzle shape cannot be defined.

  In addition, as described in Patent Document 6, when the recess is formed and then the process of penetrating the nozzle hole from the opposite side to the recess is performed, the laser is shielded by the flow path member having a complicated shape. In addition, when penetrating the nozzle hole, there is a problem that the nozzle edge may not be sharpened due to reattachment of the nozzle substrate component ablated near the nozzle edge or burnt adhesion.

  The present invention has been made in view of the above problems, and is a liquid discharge head that has excellent discharge efficiency and excellent clogging resistance when discharging pigment-based ink, a method of manufacturing the liquid discharge head, and the liquid An object of the present invention is to provide an image forming apparatus including an ejection head and an image forming method using the liquid ejection head, and to eject a nozzle hole having a sharp edge and a recess in a nozzle forming member with a simple process. An object is to provide a method for manufacturing a head.

  In order to solve the above problems, the liquid ejection head according to the present invention is a head that ejects pigment-based ink, and the nozzle forming member has a water-repellent portion formed on the surface on the droplet ejection side, When a substantially circular recess having no water-repellent portion formed inside is formed around the nozzle hole, the diameter of the recess is D, the depth of the recess is d, and the contact angle between the recess and the liquid is θ. In addition, the concave portion satisfies the relational expression d ≧ D (1-sinθ) / 2cosθ, and the nozzle forming member in the portion forming the bottom of the concave portion is thicker than the depth of the concave portion.

  A method for manufacturing a liquid discharge head according to the present invention is a method for manufacturing a liquid discharge head according to the present invention, wherein a water-repellent film is formed in advance on one side of a resin film to be a nozzle forming member, and then an excimer laser is used. It was set as the structure which nozzle hole processing and recessed part formation are performed to the resin film.

  A method of manufacturing a liquid discharge head according to the present invention includes a nozzle forming member having a plurality of nozzle holes for discharging droplets and a recess around each nozzle hole, a plurality of liquid chambers communicating with each nozzle, and a liquid chamber Forming a liquid chamber and a first member to be a plurality of nozzle forming members having a water-repellent film formed on a surface on the droplet discharge side After joining the second member to be a plurality of flow path members, nozzle holes are processed from the surface side of the droplet discharge side with respect to the first member, and further, recesses are processed around each nozzle hole. The bonded first member and second member are cut into a predetermined head size.

  Here, it can be set as the structure which performs the process which forms a nozzle hole and a recessed part sequentially, without moving the joined 1st member and 2nd member.

  The image forming apparatus according to the present invention includes the liquid ejection head according to the present invention. Here, a wiping member that cleans the nozzle surface of the liquid discharge head may be provided, and the wiping member may contact the ink composition in the recess of the liquid discharge head during the wiping operation.

  The image forming method according to the present invention is configured to form an image by ejecting pigment-based ink from the liquid ejection head according to the present invention.

  Here, the ink is an ink-jet water-based ink containing water, a pigment, and a water-soluble organic solvent as essential components, and has a viscosity at 25 ° C. of 5 mPa · sec to 20 mPa · sec and a surface tension of 40 mN / m or less. Can be configured. Further, the ink can be configured to contain 3% or more of a resin component.

  According to the liquid discharge head according to the present invention, the nozzle forming member has a water-repellent portion formed on the surface on the droplet discharge side, and the water-repellent portion is not formed inside each nozzle hole. A circular concave portion is formed, where the concave portion has a relationship of D ≧ D (1-sinθ) / 2 cos θ, where D is the diameter of the concave portion, d is the depth of the concave portion, and θ is the contact angle between the concave portion and the liquid. Since the configuration satisfies the equation, it is possible to always obtain good intermittent discharge stability even in a low humidity environment, and normal even under abnormal conditions such as when the nozzle surface is left uncapped. A liquid discharge head excellent in clogging resistance that can be easily recovered to the ejection state is obtained.

  According to the method of manufacturing a liquid discharge head according to the present invention, the method of manufacturing the liquid discharge head according to the present invention is the method of manufacturing the liquid discharge head according to the present invention. Since the nozzle hole is processed and the recess is formed in the resin film by the laser, the liquid discharge head according to the present invention can be manufactured by a simple process.

  According to the method of manufacturing a liquid discharge head according to the present invention, a plurality of flow path members that form a liquid chamber and a first member that is a plurality of nozzle forming members in which a water repellent film is formed on the surface on the droplet discharge side After joining the second member to be the first member, nozzle holes are processed from the surface side of the droplet discharge side with respect to the first member, and further, recesses are processed around each nozzle hole, and the joined first members Since the member and the second member are cut to a predetermined head size, it is possible to form nozzle holes and concave portions having sharp edges in the nozzle forming member by a simple process.

  According to the image forming apparatus of the present invention, since the liquid discharge head according to the present invention is provided, good intermittent discharge stability can be always obtained even in a low humidity environment, and the nozzle surface is left uncapped. It becomes easy to recover to a normal injection state even under abnormal conditions such as

  According to the image forming method of the present invention, since the image is formed by discharging the pigment-based ink from the liquid discharge head according to the present invention, the intermittent discharge stability is always good even in a low humidity environment. As a result, a high-quality image can be formed.

  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 sectional view of the head along the longitudinal direction of the liquid chamber, and FIG. 3 is an enlarged view of the nozzle portion of FIG.

  This liquid discharge head is configured by laminating a nozzle substrate 1, which is a nozzle forming member, a flow path member 2, a diaphragm member 3, and an actuator substrate 4.

  The nozzle substrate 1 is made of a resin material, nozzle holes 11 for discharging droplets are formed at a pitch of 150 dpi, for example, and a substantially circular recess 12 around the nozzle holes 11 on the surface on the droplet discharge side. (The nozzle hole 11 and the recess 12 are collectively referred to as a nozzle). A polyimide resin is used as a resin material for forming the nozzle substrate 1. A fluorine-based water repellent film 13 is formed on the surface of the nozzle substrate 1 on the droplet discharge side, and the water repellent film 13 is not formed on the inner side (inner surface) of the recess 12.

  In the flow path member 2, a communication hole 21 and a liquid chamber 22 communicating with the nozzle hole 11 are formed. The channel member 2 is formed of, for example, a silicon substrate. A diaphragm-shaped diaphragm 31 corresponding to the liquid chamber 22 and forming one surface of the liquid chamber 22 is formed on the diaphragm member 3. Here, a Ni material is used as the diaphragm member 3. Piezoelectric elements 41 are arranged on the actuator substrate 4 along the nozzle holes 11 corresponding to the liquid chambers 22, and the upper end surfaces of the piezoelectric elements 41 are joined to the convex portions 32 of the diaphragm 31 of the diaphragm member 3. .

  Further, a frame member 5 in which a common liquid chamber 51 for supplying ink to each liquid chamber 22 is formed is joined to the outer peripheral side of the diaphragm member 3. Ink is supplied from the common liquid chamber 51 to the liquid chamber 22 through the through hole 33 formed in the diaphragm member 3, and ink is supplied to the common liquid chamber 51 from the outside through the ink supply path 52.

  In the liquid ejection head configured as described above, for example, by lowering the voltage applied to the piezoelectric element 41 from the reference potential, the piezoelectric element 41 contracts, and the diaphragm 31 descends to expand the volume of the liquid chamber 22. Then, ink flows into the liquid chamber 22, and then the voltage applied to the piezoelectric element 41 is increased to extend the piezoelectric element 41, and the diaphragm 31 is deformed in the direction of the nozzle hole 11 to contract the volume / volume of the liquid chamber 6. By doing so, the ink in the liquid chamber 6 is pressurized, and ink droplets are ejected (jetted) from the nozzle holes 11.

  Then, by returning the voltage applied to the piezoelectric element 41 to the reference potential, the diaphragm 31 is restored to the initial position, and the liquid chamber 22 expands to generate a negative pressure. 22 is filled with ink. Therefore, after the vibration of the meniscus surface of the nozzle hole 11 is attenuated and stabilized, the operation proceeds to the next droplet discharge.

  Note that the driving method of the head is not limited to the above example (drawing-pushing), and striking or pushing can be performed depending on the direction of the drive waveform.

Details of the nozzle holes 11 and the recesses 12 formed in the nozzle substrate 1 of the liquid discharge head will be described with reference to FIG.
A water-repellent treatment film 13 (water-repellent portion) is formed on the surface of the nozzle substrate 1 on the droplet discharge side, and a water-repellent treatment film 13 (water-repellent portion) is formed around the nozzle hole 11 inside. A substantially circular recess 12 is formed. Here, when the diameter of the recess 12 is D, the depth of the recess 12 is d, and the contact angle between the recess 12 and the liquid ink is θ, the recess 12 has d ≧ D (1−sin θ ) / 2 cos θ, the diameter D and the depth d satisfy the relational expression.

  Specifically, for example, the nozzle hole 11 has a diameter of 15 μm, and a recess 12 is formed around the outlet side (surface on the droplet discharge side). The contact angle of the liquid (ink) discharged using this head with the water repellent film 13 is 80 degrees, and the contact angle with the recess 12 where the water repellent film 13 is not formed is 20 degrees. . Therefore, the recess 12 is circular with a depth d of 18 μm and a diameter D of about 50 μm, and is formed concentrically with the nozzle hole 11.

  In other words, an ink meniscus is formed at the nozzle outlet, but the shape is such that, as shown in FIG. 4, the nozzle inner wall and the ink contact with the nozzle outlet edge formed on the discharge side surface of the nozzle substrate 1. This corresponds to a part of the peripheral surface of the sphere P having a radius r that is in contact with the angle θ. Here, when the diameter of the concave portion 12 serving as the nozzle edge portion forming the meniscus is D, the depth from the surface on the droplet discharge side of the nozzle substrate 1 to the bottom of the ink meniscus center is D (1-sinθ). / 2 cos θ.

  Therefore, by setting the depth d of the concave portion 12 to be equal to or greater than the depth from the surface on the droplet discharge side of the nozzle substrate 1 to the bottom of the center of the ink meniscus (= D (1-sinθ) / 2 cos θ), The formed meniscus causes the central nozzle edge (nozzle hole 11) to be buried with the ink.

  That is, as shown in FIG. 5A, when the depth d (= d1) of the recess 12 is equal to or greater than “D (1-sinθ) / 2cosθ”, the nozzle hole 11 is formed by the liquid 10 accumulated in the recess 12. The opening is closed and can be prevented from drying by being blocked from the outside air. That is, the ink meniscus in the recess 12 is formed along an arc that forms a contact angle θ from the periphery of the recess 12, and the opening of the nozzle hole 11 exists outside the arc, that is, inside the liquid meniscus.

  On the other hand, as shown in FIG. 5B, when the depth d (= d2) of the recess 12 is less than “D (1-sinθ) / 2cosθ”, the meniscus is formed in the opening of the nozzle hole 11. Is formed, and non-ejection tends to occur due to slight surface drying.

  Further, as shown in FIG. 5C, when the depth d (= d3) of the recess 12 is equal to or greater than “D (1-sinθ) / 2cosθ” and the depth d3 is deep, the recess 12 accumulates. The amount of liquid increases and the resistance to drying of the meniscus is much better. However, if the depth d of the concave portion 12 is too deep, it may cause a droplet discharge resistance, and the discharge may become unstable. This is determined in consideration of the magnitude of generated energy, and an appropriate depth condition is determined.

  Here, as described above, if the depth d of the concave portion 12 is too deep, the droplet discharge becomes unstable. Therefore, as a specific numerical value, 1 ≦ d−D (1−sin θ) / 2 cos θ ≦ 30 (μm) It is preferable that 1 ≦ d−D (1-sin θ) / 2 cos θ ≦ 20 (μm). Also, the specific value of the diameter of the nozzle hole 11 is preferably 1 to 100 [mu] m, and 2 to 30 [mu] m in order to improve gradation and graininess by miniaturizing the droplets. It is preferable that it is 5-20 micrometers.

  As described above, the nozzle forming member has a water-repellent portion formed on the surface on the droplet discharge side, and a substantially circular recess having no water-repellent portion formed on the inside around each nozzle hole. The diameter of the recess is D, the depth of the recess is d, and the contact angle between the recess and the liquid is θ, and the recess satisfies the relational expression d ≧ D (1-sinθ) / 2 cos θ. By doing so, the nozzle hole opening is located in the meniscus, and it is possible to always obtain good intermittent discharge stability even in a low humidity environment, and abnormal conditions such as when the nozzle surface is left uncapped. In this case, it becomes easy to recover the normal injection state.

Next, an example of the shape of the nozzle hole formed in the nozzle substrate will be described with reference to FIGS.
The nozzle hole 11 is formed perpendicular to the nozzle substrate 1, but its cross-sectional shape is not limited to a straight shape as shown in FIG. 6 (a), but in the ejection direction as shown in FIG. 6 (b). A taper shape that narrows, or a taper shape that spreads in the ejection direction as shown in FIG.

  Further, as shown in FIG. 7A, a recess 15 can be formed around the inlet side of the nozzle hole 11 on the liquid chamber 22 side of the nozzle substrate 1. Furthermore, as shown in FIG. 8B, the thickness c of the portion 16 forming the bottom of the recess 12 of the nozzle substrate 1 may not be uniform.

Next, the thickness c of the part which forms the bottom part of the recessed part of a nozzle substrate is demonstrated with reference to FIG.8 and FIG.9.
The thickness of the portion (the thinnest portion of the nozzle substrate 1: also referred to as the thinnest portion) 16 forming the bottom of the recess 12 of the nozzle substrate 1 (the thickness of the portion of the nozzle substrate 1) c is: It is formed thicker than the depth d of the recess 12. That is, when the thickness of the portion 16 forming the bottom of the concave portion 12 is made thicker than the depth of the concave portion 12, even when the discharge energy is applied, the portion 16 does not flex as shown in FIG. The droplet 20 can be discharged, and the discharge efficiency is improved.

  On the other hand, when the thickness of the portion 16 forming the bottom of the concave portion 12 is less than the depth of the concave portion 12, as shown in FIG. Simultaneously with the discharge, the thinnest portion 16 of the nozzle substrate 1 is bent as indicated by an arrow, and the droplet discharge becomes unstable and the discharge efficiency decreases.

  According to an experiment, the thinnest portion 16 does not cause excessive deflection that impedes ejection due to droplet ejection energy, and therefore needs to be 20 μm or more. When the thickness c of the thinnest portion 16 is less than 20 μm, the deflection is not caused. It was confirmed that the droplet ejection was unstable.

As described above, in the head that discharges pigment-based ink, the nozzle forming member has a water-repellent portion formed on the surface on the droplet discharge side, and a water-repellent portion is formed inside each nozzle hole. A substantially circular concave portion is formed, and when the diameter of the concave portion is D, the depth of the concave portion is d, and the contact angle between the concave portion and the liquid is θ, the concave portion is d ≧ D (1-sinθ) / 2 cos θ. The nozzle forming member at the portion where the bottom of the recess is formed is thicker than the depth of the recess, so that the discharge efficiency can be improved. Clogging is improved.

Next, the diameter D of the recess 12 of the nozzle substrate 1 will be described with reference to FIGS.
According to experiments, the diameter D of the recess 12 formed in the nozzle substrate 1 is preferably 30 μm or more. In order to prevent the liquid from drying in the recess 12, the recess 12 is preferably large. When the meniscus surface is dried and the viscosity of the liquid is increased, the liquid in the recess 12 is stirred by a wiping means such as a rubber blade. The effect that the viscosity of the surface is reduced is also obtained.

  That is, as shown in FIG. 10A, when the ink meniscus 61 is dried and the viscosity is increased in the nozzle hole 11 of the head having no recess, the energy generating means can apply energy in this state. Since the droplets are not ejected normally, the recovery operation is performed by the maintenance mechanism (maintenance / recovery mechanism), but when the viscosity rises excessively, it does not readily recover. FIG. 10B shows a state of wiping by the rubber blade 62, which is one of the maintenance operations. Usually, the nozzle diameter is 30 μm or less, and even if the discharge side surface of the nozzle substrate 1 is wiped, it does not contact the meniscus and has no change.

  On the other hand, in the head having the recess 12 according to the present invention as shown in FIG. 11A, when the meniscus is dried in the recess 12, the diameter of the recess 12 is 30 μm or more, and the ink reservoir Since the volume is relatively large, even if the meniscus surface is dried and the viscosity is increased (indicated by the viscosity increasing region 63), the inside of the ink reservoir is slowly dried and the low viscosity state is maintained for a long time. . By wiping with the rubber blade 62 in this state, as shown in FIG. 11B, the tip of the elastic rubber blade 62 enters the recess 12, and contacts the ink in the recess 12 to stir the ink reservoir. Can do. As a result, the high-viscosity ink film formed on the meniscus surface is broken, and the viscosity can be lowered to a dischargeable viscosity.

Next, a method for manufacturing a liquid discharge head according to the present invention will be described.
First, a member to be processed before nozzle hole processing will be described with reference to FIGS. FIG. 12 is an explanatory view of the member to be processed as viewed from the liquid discharge surface side and the liquid chamber (flow channel surface) side, and FIG. 13 is a cross-sectional explanatory view for one bit of one chip of the member to be processed. One chip CH means a part constituting one head, and one bit means a part constituted by one nozzle hole, a liquid chamber, and energy generating means.

  Here, as shown in FIGS. 11 and 12, a thickness of 50 μm, which is a first member that becomes a plurality of nozzle substrates 1, on a silicon substrate 202 that is a second member that forms a plurality of flow path members 2. The polyimide resin film 201 is joined to form a workpiece (a member to which the first and second members are joined) 200. The polyimide resin film 201 is provided with a water repellent film 213 on the discharge side opposite to the silicon substrate 202, and a 100 μm-thick PVC film 210 is bonded thereon. This PVC film 210 functions as a protection film for the water-repellent treatment film 213 formed on the discharge surface of the nozzle substrate 1 and a protection film during excimer laser processing, which will be described later, and is peeled off after the nozzle holes 11 are formed. .

  As shown in FIG. 14, the nozzle hole 11 and the recess 12 are processed with respect to such a bonded member 200 using an excimer laser processing apparatus. In this excimer laser processing apparatus, the excimer laser beam 252 emitted from the laser oscillator 251 is reflected by the mirrors 253 to 257, guided to the processing table 261, and irradiated to the member 200 to be joined. In the optical path of the laser beam 252, lenses 258 and 259 and a mask 260 are provided at predetermined positions.

  Therefore, as shown in FIG. 15A, from the side of the silicon substrate 202 that becomes the flow path member 2 until the polyimide resin film 201 that becomes the nozzle substrate 1 penetrates the pulse laser beam 252 by the excimer laser using the mask 260a. Irradiation is performed to form the nozzle hole 11. Thereafter, as shown in FIG. 15B, the protective film 210 is peeled off, and the surface of the water-repellent treatment film 213 on the opposite side is changed to a mask 260b for forming a recess, and similarly, a pulse laser using an excimer laser is used. The concave portion 12 is formed by irradiating the beam 252 under the condition that a desired depth d that does not penetrate the polyimide resin film 201 to be the nozzle substrate 1 is formed. The nozzle holes 11 and the recesses 12 are formed with a desired pattern by switching the mask 260 mounted on the excimer laser processing apparatus. Thereafter, the workpiece 200 is divided into chips.

  Alternatively, as shown in FIG. 16A, the protective film 210 is peeled off, and the nozzle hole 11 is formed in the polyimide resin film 201 by irradiating the laser beam 252 from the water repellent film 213 side using a mask 260a. Form. Thereafter, the mask 260a is replaced with the mask 260b, and the laser beam 252 is irradiated again, so that the recess 12 is formed following the formation of the nozzle hole 11. The shape of the nozzle hole 11 may be slightly tapered by irradiation with the laser beam 252. Thereafter, the workpiece 200 is divided into chips.

  In this way, the first member that is a plurality of nozzle forming members having a water repellent film formed on the surface on the droplet discharge side and the second member that is a plurality of flow path members that form liquid chambers are joined together. Thereafter, nozzle holes are processed from the surface on the droplet discharge side with respect to the first member, and further, recesses are processed around each nozzle hole, and the bonded first member and second member are fixed to each other. By manufacturing the liquid discharge head by cutting into a head size, nozzles with sharp edges can be formed.

  That is, as in the present invention, the nozzle hole is first penetrated from the direction opposite to the flow path member (nozzle surface), and then the concave portion is formed from the same direction. There is no shading. Further, when penetrating the nozzle hole, the nozzle edge may not be sharpened due to reattachment of the nozzle substrate component ablated near the nozzle edge or burnt adhesion in some cases. Therefore, by first penetrating the nozzle hole and then forming the recess, the deposit can be removed by laser irradiation, and a nozzle with a sharp edge can be formed. Moreover, since laser irradiation is performed from the same direction, only one laser light source is required, and the nozzle and the recess can be formed without adjusting the laser light path, thereby greatly simplifying the process.

  In this case, the nozzle hole and the concave portion are formed on the concentric circle with high accuracy by performing the process of sequentially forming the nozzle hole and the concave portion without moving the joined first member and the second member. It can be formed without performing an alignment operation at the time of forming, and the processing becomes simple.

Next, a second embodiment of the liquid ejection head according to the present invention will be described with reference to FIG.
This head is a thermal head in which the energy generating means (driving element) for discharging droplets is an electrothermal converter, and the side wall of the flow path 513 is formed on the substrate 512 having the discharge energy generating body 511. A flow path forming member 514 is stacked, and a nozzle substrate 517 having a nozzle hole 515 and a recess 516 formed thereon is stacked on the flow path forming member 514, and the surface of the nozzle substrate 517 other than the recess 516 is repelled on the surface on the liquid droplet ejection side. A water treatment film 518 is formed.

  Even when the present invention is applied to such a thermal head, the same effects as described above can be obtained.

  Next, an example of an image forming apparatus provided with the liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 18 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG. 19 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. And the driven pulley 106B are moved and scanned in the direction indicated by the arrow (main scanning direction) via the timing belt 105.

  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 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. And a pressure roller 125 </ b> A and a tip pressure roller 125 </ b> B urged toward the conveyance belt 121 by the 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, is stretched between the conveyance roller 127 and the tension roller 128, and the conveyance roller 127 is rotated from the sub-scanning motor 131 via the timing belt 132 and the timing roller 133. By doing so, it is configured to go around in the belt conveyance direction (sub-scanning direction). 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. The charging roller 126 is disposed so as to come into contact with the surface layer of the transport belt 121 and to rotate following the rotation of the transport belt 121.

  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. 19, a maintenance / recovery mechanism 156 for maintaining and recovering the state of the nozzles of the recording head 107 is arranged 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 AC bias supply unit to the charging roller 126 by a control circuit (not shown), that is, a charging voltage pattern in which an alternating voltage is applied and the conveying belt 121 alternates. That is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction which is the circumferential direction. 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, by providing the liquid discharge head according to the present invention, it is possible to always obtain good intermittent discharge stability even in a low humidity environment, and abnormal conditions such as when the nozzle surface is left uncapped. Even underneath, it becomes easy to recover to the normal injection state by the maintenance recovery operation.

Next, an example of a recording liquid (ink) as a liquid used when an image is formed by being ejected by the liquid ejection head according to the present invention will be described.
The ink ejected by the liquid ejection head or the like 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. Is preferred.

  Here, the ink preferably has a surface tension at 25 ° C. of 40 mN / m or less, more preferably 15 to 30 mN / m. If the surface tension is less than 15 mN / m, ink droplets may not be formed (particles) well due to being too wet with the nozzle plate (nozzle plate), and stable ink ejection may not be obtained. On the other hand, if it exceeds 30 mN / m, ink permeation into the recording medium does not occur sufficiently, which may cause beading and a longer drying time.

  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, at least any of pigments, dyes, and colored fine particles can be used. However, although pigment-based ink is used here, dye-based ink will be described below.

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.

  As the pigment dispersant, as the hydrophilic polymer compound, 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.
Commercially available resin emulsions include, for example, 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, and the like. be able to.

  The viscosity of the ink is preferably 1 mPa · s or more and 20 mPa · s or less, and more preferably 2 to 20 mPa · s at 25 ° C. When the viscosity exceeds 20 Pa · s, it may be difficult to ensure ejection stability. Furthermore, in order to reduce the blur of the image, it is preferably 5 mPa · s or more at 25 ° C.

  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. The liquid (recording liquid) discharged by the liquid discharge head according to 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 2.

<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.).

  Among the above-described water-based inks, in particular, an ink-jet water-based ink containing water, a pigment, and a water-soluble organic solvent as essential components, having a viscosity at 25 ° C. of 5 mPa · sec to 20 mPa · sec and a surface tension of 40 dyne. When an image is formed by ejecting liquid droplets from a liquid ejection head using ink of / cm 2 or less, the problem of ejection failure due to meniscus drying becomes significant. Therefore, by performing image formation using the above-described liquid discharge head according to the present invention, it is possible to always obtain good intermittent discharge stability even in a low humidity environment, and the case where the nozzle surface is left uncapped. Even under such abnormal conditions, it is easy to recover to the normal injection state by the maintenance recovery operation, so that stable high-quality images can be formed without causing defective discharge due to meniscus drying. become able to.

  In this case, as described above, when the resin component is included in the ink, particularly when the resin component is contained in an amount of 3% or more, the problem of ejection failure due to meniscus drying becomes more significant. By performing image formation using the liquid ejection head, even if the ink contains a resin component, a high-quality image can be stably formed without causing ejection failure due to meniscus drying.

  In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this. For example, the present invention may be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. it can. Further, the present invention can be applied to an image forming apparatus using a recording liquid or a fixing processing liquid that is a liquid other than ink.

1 is an exploded perspective view showing an embodiment of a liquid discharge head according to the present invention. It is sectional explanatory drawing along the liquid chamber longitudinal direction of the head. It is an expansion explanatory view of the nozzle part of the head. It is explanatory drawing with which it uses for description of the relationship between the diameter D and the depth d of the recessed part of the head. It is explanatory drawing with which it uses for description of the relationship between the diameter D of the recessed part, the depth d, and the meniscus similarly. It is explanatory drawing with which it uses for description of the other different example of the shape of the nozzle hole of a nozzle board | substrate. It is explanatory drawing with which it uses for description of the other different example of a nozzle board | substrate similarly. It is explanatory drawing with which it uses for description of the thickness of the thinnest part of a nozzle substrate. It is explanatory drawing with which it uses for description when the thickness of the thinnest part of a nozzle substrate is thin. It is explanatory drawing with which it uses for description of the wiping operation | movement in case a nozzle substrate does not have a recessed part. It is explanatory drawing with which it uses for description of the wiping operation | movement in case a nozzle substrate has a recessed part. It is explanatory drawing with which it uses for description of the to-be-processed member used for description of the manufacturing method of the liquid discharge head which concerns on this invention. It is sectional explanatory drawing with which it uses for description of the part corresponding to 1 bit of 1 chip | tip in the to-be-processed member. It is typical explanatory drawing with which it uses for description of a laser processing apparatus. It is explanatory drawing with which it uses for description of the process of the nozzle hole and recessed part formation with respect to the to-be-processed member. It is explanatory drawing with which it uses for description of the other process of nozzle hole and recessed part formation with respect to the to-be-processed member. FIG. 6 is a cross-sectional explanatory diagram for explaining another embodiment of the liquid ejection head according to the present 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 ... Nozzle substrate 2 ... Channel member 3 ... Diaphragm member 4 ... Actuator substrate 5 ... Frame member 10 ... Liquid (ink)
DESCRIPTION OF SYMBOLS 11 ... Nozzle hole 12 ... Recessed part 21 ... Communication hole 22 ... Liquid chamber 31 ... Diaphragm 41 ... Piezoelectric element 51 ... Common liquid chamber 103 ... Carriage 107 ... Recording head 200 ... Processed member (1st, 2nd member joined) )

Claims (9)

In a liquid discharge head having a nozzle forming member having a plurality of nozzle holes for discharging droplets of liquid, a plurality of liquid chambers communicating with each of the nozzles, and energy generating means for giving energy to the liquid in the liquid chambers,
The liquid to be ejected is pigment-based ink;
The nozzle forming member has a water-repellent portion formed on the surface on the droplet discharge side, and a substantially circular recess having no water-repellent portion formed on the inside around each nozzle hole. When the diameter of the recess is D, the depth of the recess is d, and the contact angle between the recess and the liquid is θ, the recess satisfies the relational expression d ≧ D (1-sinθ) / 2 cos θ,
A liquid discharge head, wherein a thickness of a nozzle forming member in a portion forming a bottom of the recess is thicker than a depth of the recess.   A manufacturing method for manufacturing the liquid discharge head according to claim 1, wherein a water repellent film is formed in advance on one surface of a resin film to be a nozzle forming member, and then nozzle hole processing and recess formation are formed in the resin film by an excimer laser. A method of manufacturing a liquid discharge head, characterized in that: A nozzle forming member having a plurality of nozzle holes for discharging droplets and a recess around each nozzle hole; a plurality of liquid chambers communicating with each of the nozzles; and energy generating means for providing energy to the liquid in the liquid chamber; In a method of manufacturing a liquid discharge head having
After joining the first member to be a plurality of nozzle forming members having a water repellent film formed on the surface on the droplet discharge side and the second member to be a plurality of flow path members forming the liquid chamber, Nozzle holes are machined from the surface on the droplet discharge side with respect to the first member, and a recess is further machined around each nozzle hole, and the bonded first member and second member are connected to a predetermined head. A method of manufacturing a liquid discharge head, characterized by cutting into a size.   4. The method of manufacturing a liquid discharge head according to claim 3, wherein the nozzle hole and the recess are sequentially formed without moving the joined first member and second member. Manufacturing method of liquid discharge head.   An image forming apparatus comprising the liquid discharge head according to claim 1.   6. The image forming apparatus according to claim 5, further comprising a wiping member that cleans a nozzle surface of the liquid discharge head, wherein the wiping member contacts an ink composition in a recess of the liquid discharge head during a wiping operation. An image forming apparatus.   An image forming method comprising: ejecting pigment-based ink from the liquid ejection head according to claim 1 to form an image.   The image forming method according to claim 7, wherein the ink is a water-based inkjet ink containing water, a pigment, and a water-soluble organic solvent as essential components, and has a viscosity at 25 ° C. of 5 mPa · sec to 20 mPa · sec. An image forming method, wherein the surface tension is 40 mN / n or less. 9. The image forming method according to claim 7, wherein the ink contains 3% or more of a resin component.

Images