JP4627422B2 - Method for manufacturing droplet discharge head - Google Patents

Description

The present invention relates to the manufacture how the droplet discharge head.

  For example, as an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, a plotter, etc., a nozzle that discharges a recording liquid droplet and a liquid chamber (discharge chamber, pressure chamber, pressurizing chamber, ink flow path) communicating with the nozzle are used. And a droplet discharge head equipped with an actuator means for generating energy for pressurizing the liquid in the liquid chamber as a recording head.

  In such a droplet discharge head, in order to discharge droplets from the nozzle, the shape and accuracy of the nozzle greatly affect the droplet discharge characteristics such as the droplet volume and droplet velocity. By forming a water film (ink repellent film), the uniformity of the discharge side surface of the nozzle is improved, so that the droplet discharge characteristics are stabilized.

As a conventional droplet discharge head having such a water-repellent layer, for example, as described in Patent Document 1, a fluororesin polymer film is formed on a nozzle forming member made of stainless steel, silicon, or the like, followed by heat treatment. In this case, the fluororesin polymer film is cured.
JP 2003-72086 A

Further, as described in Patent Document 2, in order to improve the adhesion between the water repellent layer and the resin layer using a nozzle forming member made of a resin material, the nozzle forming member and the fluorine-based water repellent are used. Some have an SiO ₂ film formed between them.
JP 2003-341070 A

Further, as described in Patent Document 3, the peripheral portion of the nozzle has an organic resin layer containing a copolymer containing tetrafluoroethylene as one component on one side of the support base, and an adhesive layer on the opposite side. There are those coated with an ink repellent layer constituted by
Japanese Patent Laid-Open No. 10-305582

Further, as described in Patent Document 4, there is one in which an ink repellent layer is formed by plasma polymerization of silicone oil.
JP 2003-72085 A

On the other hand, as a method of processing the nozzle hole in the nozzle forming member, an excimer laser is used for the nozzle forming member after a resin member serving as the nozzle forming member is bonded in advance to a liquid chamber constituting member in which a liquid chamber communicating with the nozzle is formed. There are known methods for processing nozzle holes.
JP-A-2-121842 JP-A-1-108056

  As described above, in the conventional droplet discharge head, attempts have been made to improve the adhesion between the nozzle forming member and the water-repellent layer, but the nozzle forming member is formed of a metal member. The adhesiveness with the fluororesin water repellent layer is not sufficiently improved, and there is a problem that the water repellent layer peels off from the interface when the surface of the water repellent layer is rubbed by wiping or the like.

  In addition, when an ink repellent layer (water repellent layer) is formed of a fluorine-based resin layer, it was possible to have good ink repellency with dye ink and pigment ink having a surface tension of about 30 mN / m or more. Ink with low surface tension of 15 to 30 mN / m and ink added with a fluorosurfactant have a problem that sufficient ink repellency cannot be obtained.

  In this case, as described above, a water-repellent layer having good ink mobility can be formed by forming a silicone resin film as described in Patent Document 4, but conventionally, a liquid silicone has been used. A silicone resin film is formed by vacuum deposition of a resin material or plasma polymerization of silicone oil.

  For this reason, it is necessary to perform a vacuum treatment when forming the silicone resin coating, which requires large equipment and high cost. In addition, when a silicone resin film is formed by a method such as vacuum deposition or plasma polymerization, there is a problem that defects such as pinholes are likely to occur because the film formed for a long time is very thin. Further, it is difficult to thicken the film by a method such as vacuum deposition or plasma polymerization, and there is a problem that it is difficult to ensure sufficient durability against wiping or ink.

  Furthermore, the conventional droplet discharge head has a problem that the water-repellent layer protrudes from the nozzle. That is, in particular, when a thick water-repellent layer coating is formed on the nozzle forming member with the tip hole processed, the water-repellent layer inevitably protrudes into the nozzle, which adversely affects the direction in which droplets are ejected from the nozzle. In this case, a method of applying air from a nozzle with a dispenser is considered, but a sufficient effect is not obtained.

The present invention has been made in view of the above problems, and an object thereof is to obtain a highly accurate nozzle having a highly durable and highly water repellent film .

In order to solve the above problems, a method for manufacturing a droplet discharge head according to the present invention includes:
In a manufacturing method of a droplet discharge head, which has a nozzle forming member made of a metal member that forms a nozzle for discharging a droplet, pressurizes a liquid in a liquid chamber to which the nozzle communicates, and discharges the droplet from the nozzle.
Processing the front hole in the portion corresponding to the nozzle hole of the metal member,
Wherein a liquid polyimide resin or a polyamide resin on both surfaces of the metallic member was coated so as to close Nde write enters first hole formed by said destination drilling, only to form a water-repellent layer on the discharge side,
A laser is irradiated from the flow path forming side to the peripheral portion of the tip hole processing to remove the polyimide resin or polyamide resin in the vicinity of the nozzle on the flow path side, the polyimide resin or polyamide resin on the nozzle edge, and the water repellent layer.

Here, the water-repellent layer was formed by sequentially laminating an organic silicon compound layer and a fluorine-based water-repellent layer.

The water repellent layer can be formed by applying a silicone resin.

In this case, the water-repellent layer can be formed by sequentially laminating a silicon oxide film layer and a silicone resin.

According to the method for manufacturing a liquid droplet ejection head according to the present invention, the front hole is processed in a portion corresponding to the nozzle hole of the metal member, and liquid polyimide resin or polyamide resin is formed on both surfaces of the metal member by lowering the front hole. Nde write enters above the hole was coated so as to close, only to form a water-repellent layer on the discharge side, by irradiating a laser Sakiana processing periphery than the flow path forming side, polyimide resin near the nozzle portion of the flow path side Alternatively, since the polyamide resin and the polyimide resin at the nozzle edge or the polyamide resin and the water repellent layer are removed, a highly accurate nozzle having a highly durable and highly water repellent film can be obtained.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a first embodiment of a droplet discharge head according to the present invention will be described with reference to FIGS. 1 is an exploded perspective view of the head, FIG. 2 is a cross-sectional view of the head along the longitudinal direction of the liquid chamber, and FIG. 3 is a cross-sectional view of the head in the lateral direction of the liquid chamber (nozzle arrangement direction). It is.

  This droplet discharge head joins the flow path unit 1 and the actuator unit 2, fixes the flow path unit 1 on the frame member 3, houses the actuator unit 2 inside the frame member 3, and further flows the flow path unit. Nozzle cover 4 covering 1 is mounted.

  The channel unit 1 includes, for example, a channel plate 11 formed by anisotropic etching of a single crystal silicon substrate, a diaphragm 12 formed by, for example, nickel electroforming bonded to the lower surface of the channel plate 11, a channel The nozzle plate 13 joined to the upper surface of the plate 11 is joined and laminated, and the nozzle communication path 15, the liquid chamber 16, and the liquid chamber 16, which are channels through which the nozzles 14 that discharge liquid droplets (ink droplets) communicate with each other. An ink supply port 19 that communicates with a common liquid chamber 18 for supplying ink to the liquid is formed.

  The actuator unit 2 deforms the vibration plate 12 of the flow path unit 1 to pressurize the ink in the liquid chamber 16 and is a two-row stacked piezoelectric element as an electromechanical conversion element that is a pressure generating means (actuator means). 21 and a substrate 22 to which the piezoelectric element 21 is bonded and fixed. A strut portion 23 is provided between the piezoelectric elements 21. The column portion 23 is a portion formed simultaneously with the piezoelectric element 21 by dividing the piezoelectric element member. However, since the drive voltage is not applied, the column portion 23 is a simple column.

  In the actuator unit 2, the piezoelectric element 21 is connected to an electrical board 24 such as an FPC for connection to a drive circuit (drive IC) (not shown) to constitute a unit. By using the electric circuit board 24 as a unit component, the handling becomes easy.

  The frame member 3 is formed with a penetrating portion 31 for accommodating the actuator unit 2, a recess serving as the common liquid chamber 18, and an ink supply hole 32 for supplying ink to the common liquid chamber 18 from the outside. The frame member 3 is formed by injection molding with, for example, a thermosetting resin such as an epoxy resin or polyphenylene sulfite.

  Then, the flow path unit 1 and the actuator unit 2 are bonded with an adhesive, and the actuator unit 2 is bonded to the frame member 3 with an adhesive to fix the flow path unit 1 and the actuator unit 2 integrally. Yes.

  By attaching the nozzle cover 4 to this, the peripheral portion (head outer peripheral portion) of the nozzle plate 15 is covered so that the ink adhering to the surface of the nozzle plate 13 does not enter the inside.

  Here, the flow path plate 11 is formed by, for example, subjecting a single crystal silicon substrate having a crystal plane orientation (110) to anisotropic etching using an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), so that the nozzle communication path 15a, Although the recessed part and the hole part used as the pressurized liquid chamber 16 are formed, it is not restricted to a single crystal silicon substrate, Other stainless steel substrates, photosensitive resin, etc. can also be used.

  The diaphragm 12 is formed from a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). In addition, a metal plate or a joining member between a metal and a resin plate may be used. it can. The piezoelectric element 21 and the column portion 23 are bonded to the diaphragm 12 with an adhesive, and the frame member 3 is further bonded with an adhesive.

  The nozzle plate 13 forms a nozzle 14 having a diameter of 10 to 30 μm corresponding to each liquid chamber 16 and is bonded to the flow path plate 1 with an adhesive. As will be described later, the nozzle plate 13 is formed by forming a water repellent layer on the outermost surface of a nozzle forming member made of a metal member via a required layer.

  The piezoelectric element 21 is a stacked piezoelectric element (here, PZT) in which piezoelectric materials 51 and internal electrodes 52 are alternately stacked. An individual electrode 53 and a common electrode 54 are connected to each internal electrode 52 drawn out to the alternately different end faces of the piezoelectric element 21. In this embodiment, the ink in the liquid chamber 16 is pressurized using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 21, but the displacement in the d31 direction is used as the piezoelectric direction of the piezoelectric element 21. A configuration may be adopted in which the ink in the liquid chamber 16 is pressurized. Alternatively, a structure in which one row of piezoelectric elements 21 is provided on one substrate 22 may be employed.

  In the droplet discharge head configured as described above, by selectively applying a drive pulse voltage of 20 to 50 V to the piezoelectric element 21, the piezoelectric element 21 to which the pulse voltage is applied extends in the stacking direction. Then, the diaphragm 12 is deformed in the direction of the nozzle 14, the recording liquid in the pressurizing liquid chamber 16 is pressurized by the volume / volume change of the liquid chamber 16, and droplets of the recording liquid are ejected (jetted) from the nozzle 14.

  As the liquid droplets are ejected, the liquid pressure in the pressurized liquid chamber 16 decreases, and a slight negative pressure is generated in the pressurized liquid chamber 16 due to the inertia of the ink flow at this time. Under this state, when the voltage application to the piezoelectric element 21 is turned off, the diaphragm 12 returns to the original position, and the pressurized liquid chamber 16 becomes the original shape. To do. At this time, the recording liquid is filled into the pressurized liquid chamber 16 from the common liquid chamber 18. Therefore, after the vibration of the meniscus surface of the nozzle 14 is attenuated and stabilized, a pulse voltage is applied to the piezoelectric element 21 to discharge the droplet for the next droplet discharge.

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

Next, the nozzle plate 13 in the droplet discharge head of the first embodiment will be described with reference to FIG. In addition, the figure is an expanded sectional explanatory drawing of the nozzle part of the nozzle plate.
This nozzle plate 13 is made of a metal member, and a polyimide resin or polyamide resin layer (hereinafter referred to as “polyimide / polyamide resin layer”) is formed on the liquid droplet ejection surface 62a side of a nozzle forming member 62 as a base material on which a nozzle tip hole 61 is formed. 63), an organic silicon compound layer 64 is formed on the polyimide / polyamide resin layer 63, and a fluorine-based water repellent layer 65 is sequentially formed on the organic silicon compound layer 64. The opening portions of the polyimide / polyamide resin layer 63, the organosilicon compound layer 64, and the fluorine-based water repellent layer 65 are referred to as a nozzle edge 14a, and the nozzle edge 14a and the nozzle tip hole 51 are collectively referred to as a nozzle 14.

  Although the nozzle forming member 62 is made of a metal member as described above, the nozzle diameter can be accurately formed by forming by Ni electroforming, and also serves as a high-accuracy mask during laser processing. The hole diameter of the water repellent layer can be formed with high accuracy.

  Various materials can be used as the material for forming the polyimide / polyamide resin layer 63, but as described later, it is preferable to apply a liquid resin material. Kosan), Chemite (trade name, manufactured by Toshiba Chemical Co., Ltd.) and the like are commercially available.

  When the film thickness of the polyimide / polyamide resin layer 63 is increased, the accuracy of the diameter of the droplet discharge surface is deteriorated. When the film is too thin, pinholes or the like are generated, and the organic silicon compound layer 64 or the fluorine-based water repellent layer 65 It will cause peeling. For this reason, the film thickness of the resin layer 63 is preferably in the range of 0.1 to 5 μm. By setting this range, it is possible to prevent poor adhesion of the water-repellent layer due to pinholes in the polyimide / polyamide resin layer without impairing the accuracy of the nozzle diameter.

  And as above-mentioned, the polyimide / polyamide resin layer 63 can obtain easily the film thickness of the range of 0.1-5 micrometers by coating the nozzle formation member 62 in a liquid state, and nozzle diameter accuracy. The adhesion failure of the water repellent layer due to the pinhole of the polyimide / polyamide resin layer can be prevented without impairing the resistance.

  For the formation of the organosilicon compound layer 64, vapor deposition or spin coating dissolved in a suitable solvent can be used. It is advantageous from the viewpoint of process time and material cost (cost) that the thickness of the organic silicon compound layer 63 is set to the minimum necessary thickness within a range in which adhesion can be secured. If the film thickness of the organosilicon compound layer 64 is too thick, there may be a problem in the nozzle hole processing with an excimer laser.

  That is, even if the polyimide / polyamide resin layer 63 is cleanly processed into a nozzle hole shape, a part of the organosilicon compound layer 64 may not be processed sufficiently and may remain as a processing residue. Therefore, specifically, the adhesive strength can be ensured, and the range in which the organosilicon compound layer 64 does not remain at the time of excimer laser processing is preferably in the range of 1 to 300 mm, more preferably in the range of 10 to 100 mm.

  According to the experiments by the present inventors, it was confirmed that the adhesion was sufficient even when the thickness of the organosilicon compound layer 64 was 30 mm, and there was no problem with the excimer laser processability. Further, although a slight processing residue was observed when the thickness of the organosilicon compound layer 64 was 300 mm, it was within the usable range, and when it exceeded 300 mm, a considerably large processing residue was generated, resulting in the generation of an unusable nozzle profile. confirmed.

  As the organic silicon compound layer 64, a dimethylsiloxane-based resin has good compatibility with both the polyimide / polyamide resin layer 62 and the fluorine-based water-repellent layer 65, and is preferable for improving the adhesion.

  Various materials are known as the fluorine-based water-repellent material used for the fluorine-based water-repellent layer 65. Here, modified perfluoropolyoxetane (trade name: OPTOOL DSX, manufactured by Daikin Industries, Ltd.) is used. Thus, the necessary water repellency is obtained by vapor deposition so that the film thickness (layer thickness) is in the range of 1 to 30 mm. By using the modified perfluoropolyoxetane as the fluorine-based water repellent, wiping durability is improved and excimer laser processability is improved, so that both durability and processability can be achieved.

  As a result of the experiment, there was no difference in water repellency and wiping durability performance even when the thickness of the modified perfluoropolyoxetane was 10 mm, 20 mm, or 30 mm. Therefore, when cost etc. are considered, More preferably, it exists in the range of 1? -20 ?.

  Thus, according to this droplet discharge head, the polyimide resin or polyamide resin layer, the organosilicon compound layer, and the fluorine-based water repellent layer are sequentially laminated on the droplet discharge surface side of the nozzle forming member made of a metal member. Since it is configured, the fluorine-based water-repellent layer and the organic silicon-based compound layer are in close contact with each other, thereby improving the adhesion with the nozzle forming member and improving the durability of the water-repellent layer against wiping and the like.

  Here, the film thickness of the fluorine-based water repellent layer can be 1 to 300 mm. This is because the organosilicon compound and the fluorine-based water-repellent layer are in close contact with each other by chemical bonding, so that the film thickness of the fluorine-based water-repellent layer can be made extremely thin. The processing time can be reduced and the cost can be reduced.

  Further, by forming the fluorine-based water repellent layer from modified perfluoropolyoxetane, both wiping durability and excimer laser processability can be achieved. This is because the adhesion between the organosilicon compound and the fluorine-based water-repellent layer is high, so the thickness of the organosilicon compound and the fluorine-based water-repellent layer can be reduced, making it easy to process with an excimer laser. It is to become.

  Furthermore, since the organosilicon compound layer is a layer made of a dimethylsiloxane compound, the adhesion can be further improved and the water repellent layer can be made thinner.

Next, as a first embodiment of the method for manufacturing a droplet discharge head according to the present invention, a manufacturing process of the nozzle plate 13 of the droplet discharge head according to the first embodiment will be described with reference to FIG.
In this embodiment, as shown in FIG. 5A, a liquid polyimide resin or polyamide resin is applied to the side of the droplet discharge surface 62a of the metal nozzle forming member 62 in which the nozzle tip hole 61 has been processed and cured. After the polyimide resin / polyamide resin layer 63 is formed, an organosilicon compound layer 64 is formed on the polyimide resin / polyamide resin layer 63 as shown in FIG. 5B, and further as shown in FIG. In addition, a fluorine-based water repellent layer 65 is formed on the organosilicon compound layer 64.

  At this stage, a part of the polyimide resin / polyamide resin layer 63 formed by coating protrudes into the nozzle tip hole 61 of the nozzle forming member 62 (including a case where it closes) to become an extended portion 63a. Does not function as a nozzle. Therefore, as shown in FIG. 5D, the laser beam 66 is irradiated from the flow path surface side (liquid chamber surface side) to remove the resin protruding from the nozzle tip hole 61 (the protruding portion 53a).

  At this time, by irradiating the laser beam 66 from the liquid chamber surface side, the nozzle forming member 62 which is a metal member can be used as a mask, and it is not necessary to narrow down to the nozzle diameter, and the nozzle is formed even in the entire surface exposure. And is extremely productive.

  In addition, since the polyimide resin / polyamide resin layer 63 is extremely thin, the droplet discharge surface side is not separated from the mask (nozzle forming member 62) as in the case where the polyimide resin / polyamide resin film is pasted. It can be formed with extremely high accuracy.

  Specifically, as shown in FIG. 5A, a liquid polyimide resin or polyamide resin is applied to a nozzle forming member 62 made of a metal member in which a nozzle tip hole 61 is formed. This application can be performed by spin coating, roll coating, or the like. By curing this, the polyimide resin / polyamide resin layer 63 is formed. At this time, since the resin enters the nozzle tip hole 61, the protruding portion 63a is formed.

  Next, as shown in FIG. 5B, an organosilicon compound layer 64 is formed on the surface of the polyimide resin / polyamide resin layer 63.

  Next, as shown in FIG. 5C, a fluorine-based water repellent layer 65 is formed on the organosilicon compound layer 64. As a method for forming the fluorine-based water repellent layer 65, a fluorine-based water repellent can be applied by a method such as a spin coater, a roll coater, a spray coater, or screen printing. According to the experiments by the present inventors, It was confirmed that the method of forming a film by vacuum deposition leads to improvement in the adhesion of the water repellent layer 65.

  In addition, it was confirmed that a better effect can be obtained by performing the vacuum deposition as it is in the same vacuum chamber after forming the organosilicon compound layer 64. This is presumed that, after the organic silicon compound layer 64 is formed, once the workpiece is taken out from the vacuum chamber, impurities and the like adhere to the surface, and thus the adhesion is impaired.

  Various types of fluorine-based water repellent materials are known. Here, the use of silane-modified perfluoropolyether as the fluorine amorphous compound provides the necessary water repellency particularly for ink. It was confirmed that it can be obtained.

  Therefore, as shown in FIG. 5D, the protrusion 63a of the polyimide resin / polyamide resin layer 63 is formed by irradiating the excimer laser light 66 from the liquid chamber surface side with the nozzle forming member 62 as a mask. The nozzle edge 14a is formed by removing the organic silicon compound layer 64 and the fluorine-based water repellent layer 65 placed on 63a. Thereby, the nozzle 14 including the nozzle tip hole 61 and the nozzle edge 14a is formed.

  Thus, by forming a polyimide resin / polyamide resin layer by coating polyimide resin or polyamide resin on a metal member in a liquid state, the film thickness of the polyimide / polyamide resin layer can be easily in the range of 0.1 to 5 μm. Therefore, a highly durable and highly accurate nozzle can be formed.

  In addition, the metal member is pre-hole processed before the resin is coated on the portion corresponding to the nozzle hole, so that the nozzle can be formed using the tip hole as a mask, and the nozzle diameter accuracy is increased. Can do.

  Furthermore, after laminating each layer on the metal member, the tip-hole processed part is irradiated with laser, and the polyimide resin layer or polyamide resin layer, the organosilicon compound layer, and the fluorine-based water repellent layer are removed using the tip hole as a mask. By forming the edge of the nozzle. There is no need to reduce the diameter of the laser, and a large number of nozzles can be processed simultaneously with wide-area irradiation, thus reducing costs.

Next, a manufacturing process of the nozzle plate 13 of the droplet discharge head of the first embodiment will be described as a second embodiment of the method of manufacturing a droplet discharge head according to the present invention with reference to FIG.
In this embodiment, the polyimide resin or polyamide resin has high adhesion to metals, particularly SUS and Ni, and also has high adhesion to epoxy adhesives, etc., so that it can be applied to a metal surface to improve adhesion. Is obtained. Moreover, it is stable and resistant to solvents, and hardly deteriorates even when it comes into contact with a liquid such as ink. Therefore, in order to take advantage of these characteristics, polyimide resin or polyamide resin is applied to both surfaces of a nozzle forming member made of a metal member, and an adhesion improving layer made of polyimide resin or polyamide resin is formed on the flow path surface side.

  The application method of the polyimide resin or the polyamide resin may be a dipping method or the like, or may be a method of applying one side at a time with a spin coater or a roll coater. At this time, since the inside of the nozzle is blocked with polyimide resin or polyamide resin, the resin inside the nozzle is removed by a laser. In this case, since it is sufficient that the irradiation diameter can be removed from the vicinity of the nozzle, high accuracy is not required as in the case where the nozzle is formed by a laser, and multiple holes can be processed at the same time, thereby increasing productivity.

  More specifically, as shown in FIG. 6A, a liquid polyimide resin or polyamide resin is spin-coated, roll-coated, etc. on both surfaces of the metal nozzle forming member 62 in which the front hole 61 is processed. The polyimide resin / polyamide resin layer 63 is formed by applying and curing. In this case, polyimide resin or polyamide resin also enters the tip hole 61.

  Thereafter, as shown in FIG. 6 (b), an organosilicon compound 64 is formed on the surface of the polyimide resin / polyamide resin layer 63 on the discharge surface side. Further, as shown in FIG. A fluorine-based water repellent layer 65 is formed on the substrate.

  Next, as shown in FIG. 6D, the liquid chamber of the nozzle forming member 62 is irradiated by irradiating a predetermined region including the nozzle tip hole 61 from the liquid chamber surface side using a predetermined mask. The polyimide resin / polyamide resin layer 63 on the side is removed, and the remaining polyimide resin / polyamide resin layer 63 is left as a bonding improvement layer 67, and the excimer laser light 66 is applied from the liquid chamber surface side using the nozzle forming member 62 as a mask. , The polyimide resin / polyamide resin layer 63 in the nozzle tip hole 61, the polyimide resin / polyamide resin layer 63, the organosilicon compound layer 64, and the fluorine-based water repellent layer 65 in the nozzle edge 14 a subsequent thereto are removed. By doing so, the nozzle 14 is formed.

  In this way, a polyimide resin or a polyamide resin is applied to both surfaces of the metal member, an organosilicon compound layer and a fluorine-based water repellent layer are formed only on the discharge surface side, and a laser is applied to the peripheral portion of the tip hole processing from the flow path formation side. By irradiating and removing the polyimide resin or polyamide resin in the vicinity of the nozzle on the flow channel side and the protruding portion of the nozzle edge, the adhesion improving film on the flow channel side and the film that becomes the base of high water repellency on the discharge surface side Both can be formed simultaneously, and a highly water-repellent and highly reliable head can be formed at low cost.

  Here, the fluorine-based water repellent layer will be described. As the water repellent material for forming the fluorine-based water repellent layer, an organic compound having a fluorine atom, particularly an organic substance having a fluoroalkyl group can be used. An organosilicon compound having a dimethylsiloxane skeleton is also a water repellent material.

  As the organic compound having a fluorine atom, fluoroalkylsilane, alkane having a fluoroalkyl group, cambonic acid, alcohol, amine and the like are preferable. Specifically, the fluoroalkylsilane includes heptadecafluoro-1,1,2,2-tetrahydrodecyltrimethoxysilane, heptadecafluoro-1,1,2,2-tetrahydrotrichlorosilane; fluoroalkyl As the alkane having a group, octafluorocyclobutane, perfluoromethylcyclohexane, perfluoro-n-hexane, perfluoro-n-heptane, tetradecafluoro-2-methylpentane, perfluorododecane, perfluoroeucosane; and carboxylic acid having a fluoroalkyl group Perfluorodecanoic acid, perfluorooctanoic acid; alcohols having a fluoroalkyl group include 3, 3, 4, 4, 5, 5, 5-heptafluoro-2-pentanol; The emissions can include heptadecafluoro over 1,1,2,2-tetrahydro-decyl amine.

  Examples of the organosilicon compound having a dimethylsiloxane skeleton include α, w-bis (3-aminopropyl) polydimethylsiloxane, α, w-bis (3-glycidoxypropyl) polydimethylsiloxane, α, w-bis (vinyl). ) Polydimethylsiloxane and the like.

  Furthermore, as another water-repellent material, an organic compound having a silicon atom, particularly an organic compound having an alkylsiloxane group can be used. Examples of the organic compound having an alkylsiloxane group include the alkylsiloxane group having two or more alkylsiloxane groups and cyclic aliphatic epoxy groups in the molecule constituting the alkylsiloxane epoxy resin composition. The polymer compound (A) containing the structural unit represented by general formula (a) and (b) is mentioned.

  The compound having the above structure also functions as a binder when used in combination with other water-repellent compounds. That is, it improves the workability of the ink-repellent composition and improves the workability as a dry coating film that improves the drying property after evaporation of the solvent.

  The film thickness of the water repellent layer is preferably 5 μm or less, more preferably 2 μm or less. When the film thickness exceeds 5 μm, drying of the coating film may be delayed, productivity may be deteriorated, and mechanical durability may be impaired, and peeling may occur when wiping is performed.

  Further, as described above, the water-repellent layer may be formed by vapor deposition under vacuum, or may be applied after being dissolved in an appropriate solvent.

  Speaking of the former, for example, after evacuating the inside of the vacuum chamber to a predetermined degree of vacuum with a vacuum exhaust pump, the water repellent material is vaporized at 400 ° C. and introduced into the vacuum chamber, the vacuum atmosphere is adjusted, and the high frequency power supply Then, power is supplied to the discharge electrode to cause RF glow discharge, and the nozzle surface of the droplet discharge head is surface-treated in a plasma atmosphere to form a water repellent film on the nozzle surface. Depending on the material and the degree of vacuum in the vacuum chamber, a water-repellent film at a low temperature of about room temperature to about 200 ° C. can be formed.

  As for the latter, for example, a water-repellent material can be dissolved in an organic solvent and coated with a jig such as a wire bar or a doctor blade, or can be applied by spin coating with a spin coater or by spraying. It can also be dip coated (dipped) in a container filled with a coating solution.

Next, a second embodiment of the droplet discharge head according to the present invention will be described with reference to FIG. This figure is an enlarged explanatory view of the nozzle portion of the nozzle plate 13 in the droplet discharge head of the same embodiment.
The nozzle plate 13 is made of a metal member, and a polyimide / polyamide resin layer 73 is formed on the polyimide / polyamide resin layer 73 on a droplet discharge surface 72a of a nozzle forming member 72 as a base material on which a nozzle tip hole 71 is formed. In addition, a silicone resin layer 75 serving as a water repellent layer is sequentially laminated. The opening portions of the polyimide / polyamide resin layer 73 and the silicone resin layer 75 are referred to as a nozzle edge 14a, and the nozzle edge 14a and the nozzle tip hole 71 are collectively referred to as a nozzle 74.

  Although the nozzle forming member 72 is made of a metal member as described above, the nozzle diameter can be accurately formed by forming by Ni electroforming, and also serves as a high-accuracy mask during laser processing. The hole diameter of the water repellent layer can be formed with high accuracy.

  Again, various materials can be used as the material for forming the polyimide / polyamide resin layer 73, but it is preferable to apply a liquid resin material as in the above-described embodiment. (Trade name, manufactured by Ube Industries), chemitite (trade name, manufactured by Toshiba Chemical) and the like are commercially available.

  When the polyimide / polyamide resin layer 73 is thick, it causes deterioration of the diameter accuracy on the droplet discharge surface side. When the polyimide / polyamide resin layer 73 is too thin, the silicone resin layer 75 is peeled off due to generation of pinholes or the like. For this reason, the thickness of the resin layer 73 is preferably in the range of 0.1 to 5 μm. By setting it as this range, the adhesion failure of the silicone resin layer 75 by the pinhole of a polyimide / polyamide resin layer can also be prevented, without impairing the precision of a nozzle diameter.

  The polyimide / polyamide resin layer 73 can be easily coated with the nozzle forming member 72 in the state as described above to easily obtain a film thickness in the range of 0.1 to 5 μm, and has high durability and high water repellency. The nozzle plate can be easily obtained.

  Examples of the silicone resin for forming the silicone resin layer 75 include room temperature curable and heat curable liquid silicone resins or elastomers, but all have relatively low hardness, so the film thickness is from the point of wear resistance. Thick ones are preferred. However, when the thickness of the silicone resin layer 75 which is a water repellent layer is increased, it is difficult to maintain the nozzle diameter accuracy, and it is preferably in the range of about 1 μm to 20 μm from the balance between the two, more preferably 5 It is in the range of -10 μm. By setting the film thickness of the silicone resin layer 75 within the range of 1 μm to 20 μm, both wear resistance and nozzle diameter accuracy can be achieved.

  As described above, the polyimide resin or polyamide resin layer and the silicone resin are sequentially laminated on the droplet discharge surface side of the nozzle forming member made of a metal member, so that the adhesion between the silicone resin and the nozzle forming member is high. Thus, the durability of the water repellent layer is improved.

Next, a third embodiment of the droplet discharge head according to the present invention will be described with reference to FIG. FIG. 8 is an enlarged explanatory view of the nozzle portion of the nozzle plate of the droplet discharge head according to the embodiment.
In this nozzle plate 13, a Si oxide film layer 74 is formed between the polyimide resin / polyamide resin layer 73 and the silicone resin layer 75 formed on the nozzle plate 13 of the droplet discharge head according to the second embodiment. Is.

  As a means for improving the adhesion of the silicone resin layer 75, it is effective to form a Si oxide film layer 74 between the polyimide / polyamide resin layer 73 and the silicone resin layer 75. Sputtering, ion beam vapor deposition, ion plating, CVD (chemical vapor deposition), P-CVD (plasma vapor deposition), etc. are suitable for forming this Si oxide film layer 74, but a liquid phase Si-based primer is used. The method of apply | coating and baking may be used.

  Here, it is advantageous from the viewpoint of process time and material cost that the Si oxide film layer 74 has a necessary minimum thickness as long as the adhesion of the silicone resin layer 75 can be secured. . If the film thickness of the Si oxide film layer 74 becomes too thick, there is a possibility that trouble may occur when nozzle holes are processed with an excimer laser. That is, even if the polyimide / polyamide resin layer 73 is neatly processed into a nozzle hole shape, a part of the Si oxide film layer 74 may not be sufficiently processed and may remain as a processing residue.

  Therefore, specifically, as the range in which the adhesion can be secured and the Si oxide film layer 74 does not remain at the time of excimer laser processing, the thickness of the Si oxide film layer 74 is preferably in the range of 1 to 300 mm, More preferably, it is in the range of 10 to 100 inches. As a result of experiments by the present inventors, it was confirmed that even if the thickness of the Si oxide film layer 74 is 30 mm, the adhesion is sufficient, and there is no problem with the workability by the excimer laser. In addition, although a slight processing residue was observed when the thickness of the Si oxide film layer 74 was 300 mm, it was within the usable range, and when it exceeded 300 mm, a considerably large processing residue was generated, so that an unusable nozzle profile could be seen. It was confirmed that

  As described above, the polyimide resin or polyamide resin layer, the Si oxide film layer, and the silicone resin are sequentially laminated on the droplet discharge surface side of the nozzle forming member made of a metal member, so that the silicone resin and the nozzle forming member are formed. The adhesion of the water repellent layer is further improved, and the durability (abrasion resistance and peel resistance) of the water repellent layer is improved.

Next, a third embodiment of the method for manufacturing a droplet discharge head according to the present invention will be described with reference to FIG. 9 taking the nozzle plate 13 of the droplet discharge head according to the third embodiment as an example.
In this embodiment, as shown in FIG. 9A, a liquid polyimide resin or polyamide resin is applied to the droplet discharge surface 72a side of the metal nozzle forming member 72 in which the nozzle tip hole 71 has been processed and cured. After the polyimide resin / polyamide resin layer 73 is formed, an Si oxide film layer 74 is formed on the polyimide resin / polyamide resin layer 73 as shown in FIG. 9B, and further as shown in FIG. 9C. Then, a silicone resin layer 75 is formed on the Si oxide film layer 74.

  At this stage, a part of the polyimide resin / polyamide resin layer 73 formed by coating protrudes into the nozzle tip hole 71 of the nozzle forming member 72 (including the case where it closes), so that the protruding portion 73a remains. Does not function as a nozzle. Therefore, as shown in FIG. 9D, the laser beam 76 is irradiated from the flow path surface side (liquid chamber surface side), and the resin protruding from the nozzle tip hole 71 (the protruding portion 63a) is removed.

  At this time, by irradiating the laser beam 76 from the liquid chamber surface side, the nozzle forming member 72, which is a metal member, can be used as a mask. And is extremely productive.

  Further, since the polyimide resin / polyamide resin layer 73 is extremely thin, the droplet discharge surface side is not separated from the mask (nozzle forming member 62) as in the case where the polyimide resin / polyamide resin film is pasted. It can be formed with extremely high accuracy.

  Specifically, as shown in FIG. 9A, a liquid polyimide resin or polyamide resin is applied to a nozzle forming member 72 made of a metal member in which a nozzle tip hole 71 is formed. This application can be performed by spin coating, roll coating, or the like. By curing this, the polyimide resin / polyamide resin layer 73 is formed. At this time, since the resin enters the nozzle tip hole 71, the protruding portion 73a is formed.

  Next, as shown in FIG. 9B, a Si oxide film layer 74 is formed on the surface of the polyimide resin / polyamide resin layer 73.

  Next, as shown in FIG. 9C, a silicone resin layer 75 is formed on the Si oxide film layer 74. As a method of forming the silicone resin layer 75, a silicone resin water repellent can be applied by a method such as a spin coater, a roll coater, a spray coater, or screen printing.

  Therefore, as shown in FIG. 9 (d), by using the nozzle forming member 72 as a mask and irradiating the excimer laser beam 76 from the liquid chamber surface side, the protruding portion 73a of the polyimide resin / polyamide resin layer 73 is formed. The nozzle edge 14a is formed by removing the Si oxide film layer 74 and the silicone resin layer 75 placed on the layer 73a. Thereby, the nozzle 14 including the nozzle tip hole 71 and the nozzle edge 14a is formed.

  Thus, by forming a polyimide resin / polyamide resin layer by coating polyimide resin or polyamide resin on a metal member in a liquid state, the film thickness of the polyimide / polyamide resin layer can be easily in the range of 0.1 to 5 μm. Therefore, a highly durable and highly accurate nozzle can be formed.

  In addition, the metal member is pre-hole processed before the resin is coated on the portion corresponding to the nozzle hole, so that the nozzle can be formed using the tip hole as a mask, and the nozzle diameter accuracy is increased. Can do.

  Furthermore, after laminating each layer on the metal member, the tip hole processed portion is irradiated with laser, and using the tip hole as a mask, the protrusion of the polyimide resin layer or polyamide resin layer, Si oxide film layer and silicone resin layer is removed, By forming the edge of the nozzle. There is no need to reduce the diameter of the laser, and a large number of nozzles can be processed simultaneously with wide-area irradiation, thus reducing costs.

Next, as a fourth embodiment of the method for manufacturing a droplet discharge head according to the present invention, a manufacturing process of the nozzle plate 13 of the droplet discharge head of the third embodiment will be described as an example with reference to FIG.
In this embodiment, the polyimide resin or polyamide resin has high adhesion to metals, particularly SUS and Ni, and also has high adhesion to epoxy adhesives, etc., so that it can be applied to a metal surface to improve adhesion. Is obtained. Moreover, it is stable and resistant to solvents, and hardly deteriorates even when it comes into contact with a liquid such as ink. Therefore, in order to take advantage of these characteristics, polyimide resin or polyamide resin is applied to both surfaces of a nozzle forming member made of a metal member, and an adhesion improving layer made of polyimide resin or polyamide resin is formed on the flow path surface side.

  The application method of the polyimide resin or the polyamide resin may be a dipping method or the like, or may be a method of applying one side at a time with a spin coater or a roll coater. At this time, since the inside of the nozzle is blocked with polyimide resin or polyamide resin, the resin inside the nozzle is removed by a laser. In this case, since it is sufficient that the irradiation diameter can be removed from the vicinity of the nozzle, high accuracy is not required as in the case where the nozzle is formed by a laser, and multiple holes can be processed at the same time, thereby increasing productivity.

  Specifically, as shown in FIG. 10A, a liquid polyimide resin or polyamide resin is spin-coated, roll-coated, etc. on both surfaces of the metal nozzle forming member 72 in which the leading hole 71 is processed. The polyimide resin / polyamide resin layer 73 is formed by applying and curing. In this case, polyimide resin or polyamide resin also enters the tip hole 71.

  Thereafter, as shown in FIG. 10B, a Si oxide film layer 74 is formed on the surface of the polyimide resin / polyamide resin layer 73 on the discharge surface side, and further, as shown in FIG. A silicone resin layer 75 is formed on 74.

  Next, as shown in FIG. 10D, the liquid chamber of the nozzle forming member 72 is irradiated by irradiating a predetermined region including the nozzle tip hole 71 from the liquid chamber surface side using a predetermined mask. The polyimide resin / polyamide resin layer 73 on the side is removed, and the remaining polyimide resin / polyamide resin layer 73 is left as the bonding improvement layer 77. Also, the excimer laser light 76 is applied from the liquid chamber surface side using the nozzle forming member 72 as a mask. The polyimide resin / polyamide resin layer 73 in the nozzle tip hole 71 and the polyimide resin / polyamide resin layer 73, the Si oxide film layer 74, and the silicone resin layer 75 at the nozzle edge 14 a subsequent thereto are removed. Thus, the nozzle 14 is formed.

  In this way, a polyimide resin or a polyamide resin is applied to both surfaces of the metal member, a Si oxide film layer and a silicone resin layer are formed only on the discharge surface side, and a laser is irradiated from the flow path formation side to the front hole processing peripheral part. By removing the polyimide resin or polyamide resin in the vicinity of the nozzle on the flow path side and the protruding part of the nozzle edge, both the adhesion improving film on the flow path side and the film that becomes the base of high water repellency on the discharge surface side A head that can be formed simultaneously and has high water repellency and high reliability can be formed at low cost.

  An image forming apparatus (inkjet recording apparatus) equipped with a droplet discharge head using a nozzle plate as described above is an apparatus with extremely excellent print quality because the nozzle surface has sufficient ink repellency. In particular, a large effect is exhibited in an ink having a low surface tension that is difficult to produce ink repellency, specifically, an ink of about 15 to 30 N / m. In addition, a large effect is exhibited also with respect to an ink containing a fluorine-based surfactant that easily wets a fluorine-based water repellent.

  A nozzle plate formed with an ink-repellent film (water-repellent layer) of a silicone resin according to the present invention, and a nozzle plate subjected to heat treatment at 350 ° C. for 60 minutes after performing a conventional eutectoid plating of Ni-PTFE. Table 1 shows the ink repellency for each ink. The ink conditions were as follows: surface tension: 20 mN / m, 35 mN / m, fluorine surfactant: contained or not contained.

  As can be seen from Table 1, with the nozzle plate according to the conventional method, ink repellency (water repellency) could not be obtained with respect to ink having a surface tension of 20 mN / m and ink containing a fluorosurfactant. In contrast, according to the nozzle plate of the present invention, it was possible to obtain good ink repellency with respect to the ink of all the above conditions.

Next, an example of an image forming apparatus according to the present invention equipped with the droplet discharge head according to the present invention will be described with reference to FIGS. FIG. 10 is an explanatory side view for explaining the overall configuration of the image forming apparatus according to the present invention, and FIG. 11 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 which are horizontally mounted on left and right side plates (not shown), and a timing belt 105 is slid by a main scanning motor 104. 11 to move and scan in the arrow direction (main scanning direction) in FIG.

  On this carriage 103, for example, four recording heads 107 each comprising a droplet discharge head according to the present invention for discharging yellow (Y), cyan (C), magenta (M), and black (Bk) ink droplets, respectively. Are arranged in a direction crossing the main scanning direction and the ink droplet discharge direction is directed downward.

  As the droplet discharge head constituting the recording head 107, recording is performed using an electrothermal conversion element such as a heating resistor in addition to a head that discharges droplets using a piezoelectric actuator such as a piezoelectric element as described above. Thermal actuators that use liquid film boiling, shape memory alloy actuators that use metal phase changes due to temperature changes, electrostatic actuators that use electrostatic force, etc., as energy generating means for ejecting ink (liquid) Can be used. Note that the recording head can also be configured by one or a plurality of liquid droplet ejection heads provided with a plurality of nozzle rows that eject different colors.

  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 paper feeding unit for feeding paper 112 stacked on a paper stacking unit (pressure plate) 111 such as a paper feeding cassette 110, a half-moon roller (separately feeding paper 112 one by one from the paper stacking unit 111) A separation pad 114 made of a material having a large friction coefficient is provided opposite to the sheet feeding roller 113 and the sheet feeding roller 113, and the separation pad 114 is urged toward the sheet feeding roller 113 side.

  As a transport unit for transporting the paper 112 fed from the paper feed unit below the recording head 107, a transport belt 121 for electrostatically attracting and transporting the paper 112, and a paper feed unit A counter roller 122 for transporting the paper 112 fed through the guide 115 while sandwiching it between the transport belt 121 and the paper 112 fed substantially vertically upward is changed by about 90 ° and copied on the transport belt 121. A conveying guide 123 for adjusting the pressure and a tip pressure roller 125 urged toward the conveying belt 121 by a pressing member 124. Further, a charging roller 126 which 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 circulate in the belt conveyance direction (sub-scanning direction) of FIG. A guide member 129 is disposed on the back side of the conveyance belt 121 in correspondence with the image forming area formed by the recording head 107.

  As shown in FIG. 11, a slit disk 134 is attached to the shaft of the transport roller 127, and a sensor 135 for detecting the slit of the slit disk 134 is provided. An encoder 136 is configured.

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

  Further, as shown in FIG. 10, an encoder scale 142 having slits is provided on the front side of the carriage 103, and an encoder sensor comprising a transmissive photosensor that detects the slits of the encoder scale 142 on the front side of the carriage 103. The encoder 144 for detecting the position of the carriage 103 in the main scanning direction is configured by these.

  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 161 is detachably attached to the back. The double-sided paper feeding unit 161 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. 12, a maintenance / recovery mechanism 191 for maintaining and recovering the state of the nozzles of the recording head 107 is disposed in a non-printing area on one side of the carriage 103 in the scanning direction.

  The maintenance and recovery mechanism 191 caps each nozzle surface of the recording head 107 (here, “nozzle surface” refers to the outermost surface of the nozzle plate 13, that is, the surface of the fluorine-based water repellent layer 65 or the surface of the silicone resin 75). Caps 192a to 192d (referred to as “cap 192” when not distinguished), a wiper blade 193 that is a blade member for wiping the nozzle surface, and recording to discharge the thickened recording liquid An empty discharge receptacle 194 for receiving droplets when performing empty discharge for discharging droplets that do not contribute 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 output and a negative output are alternately repeated from the high voltage power source to the charging roller 126 by a control circuit (not shown), that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 21 is alternating, that is, In the sub-scanning direction, which is the circumferential direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 112 is fed onto the conveyance belt 121 charged alternately with plus and minus, the paper 112 is attracted to the conveyance belt 121 by electrostatic force, and the paper 112 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 121. Is done.

  Therefore, by driving the recording head 107 according to the image signal while moving the carriage 103, ink droplets are ejected onto the stopped paper 112 to record one line, and after the paper 112 is conveyed by a predetermined amount, Record the next line. 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 161 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 191 side, and the nozzle surface of the recording head 107 is capped by the cap 192. To prevent. In addition, the recording liquid is sucked from the nozzle in a state where the recording head 107 is capped with the cap 192 (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 193 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, the image forming apparatus according to the present invention includes the liquid droplet ejection head according to the present invention that is excellent in durability of the water-repellent layer against wiping and the like, and thus can stably provide a high-quality image over a long period of time. Can be formed.

Next, a recording liquid (ink) used in the image forming apparatus will be described.
The recording liquid used in the image forming apparatus according to the present invention can be used as a color material, either a pigment or a dye, or can be used as a mixture.

[Pigment]
Although there is no limitation in particular as a pigment used for a recording liquid, For example, the pigments listed below are used suitably. Moreover, you may use these pigments in mixture of multiple types.
Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. It is done.

  Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

  The particle diameter of these pigments is preferably 0.01 to 0.30 [mu] m. If the particle diameter is 0.01 [mu] m or less, the light resistance and feathering are deteriorated because the particle diameter approaches that of the dye. On the other hand, if it is 0.30 μm or more, clogging of the discharge port or clogging with a filter in the image forming apparatus occurs, and discharge stability cannot be obtained.

  The carbon black used in the black pigment ink is carbon black produced by the furnace method and the channel method, the primary particle size is 15 to 40 millimicrons, the specific surface area by the BET method is 50 to 300 square meters / g, The DBP oil absorption is preferably 40 to 150 ml / 100 g, the volatile content is 0.5 to 10%, and the pH value is 2 to 9.

  As such a thing, for example, no. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (Mitsubishi Chemical), Raven700, 5750, 5250, 5000, 3500, 1500 (Columbia), Regal 400R, 330R, 660R, MoguL, Monarch 700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (manufactured by Cabot), color black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, the same V, the same 140U, the same 140V, the special black 6, the same 5, the same 4A, the same 4 (manufactured by Degussa) and the like can be used, but are not limited thereto.

Specific examples of color pigments are listed below.
Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.
Specific examples according to color are as follows.

  Examples of pigments that can be used for yellow ink include C.I. I. Pigment Yellow 1, 2, 2, 3, 12, 14, 16, 17, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 128, 129, 151, 154, etc., but are not limited thereto.

    Examples of pigments that can be used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 123, 168, 184, 202, etc. However, it is not limited to these.

  Examples of pigments that can be used for cyan ink include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15:34, 16, 22, 22, 60, C.I. I. Examples thereof include, but are not limited to, Bat Blue 4 and 60.

  Further, the pigment contained in each ink used in the image forming apparatus according to the present invention can be used even if it is newly manufactured for the droplet discharge head according to the present invention.

  The pigments listed above can be made into an inkjet recording liquid by dispersing them in an aqueous medium using a polymer dispersant or a surfactant. As a dispersant for dispersing such organic pigment powder, a normal water-soluble resin or a water-soluble surfactant can be used.

  Specific examples of water-soluble resins include styrene, styrene derivatives, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itacon. Examples thereof include block copolymers consisting of at least two monomers selected from acids, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, etc., random copolymers, or salts thereof. These water-soluble resins are alkali-soluble resins that are soluble in an aqueous solution in which a base is dissolved. Among them, a resin having a weight average molecular weight of 3000 to 20000 is used as a dispersion when used in an inkjet recording liquid. It is particularly preferred because of the advantages that it can be reduced in viscosity and can be easily dispersed.

  The simultaneous use of the polymer dispersant and the self-dispersing pigment is a preferable combination because an appropriate dot diameter can be obtained. The reason is not clear, but it is thought as follows.

  By containing the polymer dispersant, the penetration into the recording paper is suppressed. On the other hand, since the aggregation of the self-dispersing pigment is suppressed by containing the polymer dispersant, the self-dispersing pigment can smoothly spread in the lateral direction. Therefore, it is considered that the dots spread widely and thinly and ideal dots can be formed.

  Moreover, the following are mentioned as a specific example of the water-soluble surfactant which can be used as a dispersing agent by this invention. For example, anionic surfactants include higher fatty acid salts, alkyl sulfates, alkyl ether sulfates, alkyl ester sulfates, alkyl aryl ether sulfates, alkyl sulfonates, sulfosuccinates, alkyl allyls and alkyl naphthalene sulfonic acids. Examples thereof include salts, alkyl phosphates, polyoxyethylene alkyl ether phosphate esters, and alkyl allyl ether phosphates. Examples of the cationic surfactant include alkylamine salts, dialkylamine salts, tetraalkylammonium salts, benzalkonium salts, alkylpyridinium salts, imidazolinium salts, and the like. Furthermore, examples of the amphoteric surfactant include dimethylalkyl lauryl betaine, alkyl glycine, alkyl di (aminoethyl) glycine, imidazolinium betaine and the like. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, sucrose ester, glycerin ester polyoxyethylene ether, sorbitan Examples thereof include polyoxyethylene ethers of esters, polyoxyethylene ethers of sorbitol esters, fatty acid alkanolamides, polyoxyethylene fatty acid amides, amine oxides, and polyoxyethylene alkylamines.

  Further, the pigment can be provided with dispersibility by coating with a resin having a hydrophilic group and encapsulating the pigment.

  As a method for coating a water-insoluble pigment with an organic polymer and microencapsulating, all conventionally known methods can be used. Conventionally known methods include chemical production methods, physical production methods, physicochemical methods, mechanical production methods, and the like. Specifically, the following (1) to (10) can be mentioned.

  (1) Interfacial polymerization method: A method in which two types of monomers or two types of reactants are separately dissolved in a dispersed phase and a continuous phase, and both substances are reacted at the interface between them to form a wall film. .

(2) In-situ polymerization method: a method in which a liquid or gas monomer and catalyst, or two reactive substances are supplied from either one of the continuous phase core particles to cause a reaction to form a wall film) is there.

  (3) In-liquid cured coating method: A method in which a wall film is formed by insolubilizing droplets of a polymer solution containing core material particles in a liquid with a curing agent or the like.

  (4) Coacervation (phase separation) method: a method in which a polymer dispersion in which core material particles are dispersed is separated into a coacervate (concentrated phase) and a dilute phase having a high polymer concentration to form a wall membrane. is there.

  (5) In-liquid drying method: A liquid in which a core material is dispersed in a solution of a wall membrane material is prepared, and the dispersion is put into a liquid in which the continuous phase of this dispersion is not mixed to form a composite emulsion. In this method, the wall film is formed by gradually removing the dissolved medium.

  (6) Melt dispersion cooling method: Utilizing a wall film material that melts into a liquid state upon heating and solidifies at room temperature, this material is heated and liquefied, core material particles are dispersed therein, and then cooled to fine particles. This is a method for forming a wall film.

  (7) Air suspension coating method: Powder core material particles are suspended in the air by a fluidized bed, and the wall membrane material coating solution is sprayed and mixed while suspended in the air stream to form a wall membrane. Is the method.

  (8) Spray drying method: A method in which an encapsulated stock solution is sprayed and brought into contact with hot air to evaporate and dry the volatile matter to form a wall film.

  (9) Acid precipitation method: At least a part of the anionic group of the organic polymer compound containing an anionic group is neutralized with a basic compound to provide water solubility and in an aqueous medium together with the coloring material. After kneading, it is neutralized or acidified with an acidic compound, organic compounds are precipitated and fixed on a colorant, and then neutralized and dispersed.

  (10) Phase inversion emulsification method: A mixture containing an anionic organic polymer having dispersibility in water and a coloring material is used as an organic solvent phase, and water is added to the organic solvent phase or water In which the organic solvent phase is charged.

  Examples of organic polymers (resins) used as the material constituting the microcapsule wall membrane material include polyamide, polyurethane, polyester, polyurea, epoxy resin, polycarbonate, urea resin, melamine resin, phenol resin, and polysaccharide. , Gelatin, gum arabic, dextran, casein, protein, natural rubber, carboxypolymethylene, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, cellulose, ethyl cellulose, methyl cellulose, nitrocellulose, hydroxyethyl cellulose, acetic acid Cellulose, polyethylene, polystyrene, (meth) acrylic acid polymer or copolymer, (meth) acrylic acid ester polymer or copolymer, (meth) acrylic acid (Meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, styrene-maleic acid copolymer, sodium alginate, fatty acid, paraffin, beeswax, water wax, hardened beef tallow, carnauba wax, albumin, etc. .

  Among these, organic polymers having an anionic group such as a carboxylic acid group or a sulfonic acid group can be used. Nonionic organic polymers include, for example, polyvinyl alcohol, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate or their (co) polymers, and 2-oxazoline cationic ring-opening polymers. Is mentioned. In particular, a complete saponified product of polyvinyl alcohol is particularly preferable because it has low water solubility and is easily dissolved in hot water but difficult to dissolve in cold water.

  Further, the amount of the organic polymer constituting the wall membrane material of the microcapsule is 1% by weight or more and 20% by weight or less based on the water-insoluble colorant such as an organic pigment or carbon black. By setting the amount of the organic polymer within the above range, the content of the organic polymer in the capsule is relatively low so that the pigment develops due to the organic polymer covering the pigment surface. Can be suppressed. If the amount of the organic polymer is less than 1% by weight, it is difficult to exert the effect of encapsulation. Conversely, if the amount exceeds 20% by weight, the color developability of the pigment is significantly reduced. In consideration of other characteristics, the amount of the organic polymer is preferably in the range of 5 to 10% by weight based on the water-insoluble colorant.

That is, since a part of the color material is exposed without being substantially covered, it is possible to suppress a decrease in color developability, and conversely, a part of the color material is not substantially exposed without being exposed. Since it is coated, it is possible to simultaneously exhibit the effect that the pigment is coated. The number average molecular weight of the organic polymers used in the present invention is preferably 2000 or more from the viewpoint of capsule production. Here, “substantially exposed” means not the partial exposure associated with defects such as pinholes and cracks, but a state where it is intentionally exposed.
Furthermore, if an organic pigment or self-dispersing carbon black, which is a self-dispersing pigment, is used as a colorant, the dispersibility of the pigment is improved even if the content of the organic polymer in the capsule is relatively low. In addition, since sufficient storage stability of the ink can be secured, it is more preferable for the present invention.

  It is preferable to select an organic polymer suitable for the microencapsulation method. For example, in the case of interfacial polymerization, polyester, polyamide, polyurethane, polyvinyl pyrrolidone, epoxy resin and the like are suitable. In the case of using the in-situ polymerization method, a polymer or copolymer of (meth) acrylic acid ester, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, Polyvinyl chloride, polyvinylidene chloride, polyamide and the like are suitable. In the case of the liquid curing method, sodium alginate, polyvinyl alcohol, gelatin, albumin, epoxy resin and the like are suitable. In the case of the coacervation method, gelatin, celluloses, casein and the like are suitable. In addition, in order to obtain a fine and uniform microencapsulated pigment, it is possible to use all conventionally known encapsulation methods other than those described above.

  When the phase inversion method or the acid precipitation method is selected as the microencapsulation method, anionic organic polymers are used as the organic polymers constituting the wall membrane material of the microcapsules. The phase inversion method is a composite or composite of an anionic organic polymer having self-dispersibility or solubility in water and a colorant such as a self-dispersion organic pigment or self-dispersion carbon black, or a self-dispersion method. A mixture of a colorant such as a dispersible organic pigment or self-dispersing carbon black, a curing agent, and an anionic organic polymer is used as an organic solvent phase, and water is added to the organic solvent phase, or the organic solvent is submerged in water. In this method, a solvent phase is introduced and microencapsulation is performed while self-dispersion (phase inversion emulsification) is performed. In the above phase inversion method, there is no problem even if the organic solvent phase is mixed with a recording liquid vehicle or additives. In particular, it is more preferable to mix a liquid medium of a recording liquid because a dispersion liquid for recording liquid can be directly produced.

  On the other hand, in the acid precipitation method, a part or all of the anionic group of the anionic group-containing organic polymer is neutralized with a basic compound, and a colorant such as a self-dispersing organic pigment or self-dispersing carbon black, A water-containing cake obtained by a production method comprising a step of kneading in an aqueous medium and a step of neutralizing and acidifying an acidic compound to precipitate an anionic group-containing organic polymer and fixing it to a pigment, This is a method of microencapsulation by neutralizing a part or all of an anionic group using a compound. By doing in this way, the aqueous dispersion containing the anionic microencapsulated pigment which is fine and contains many pigments can be manufactured.

  Examples of the solvent used for microencapsulation as described above include alkyl alcohols such as methanol, ethanol, propanol and butanol; aromatic hydrocarbons such as benzol, toluol and xylol; methyl acetate Esters such as ethyl acetate and butyl acetate; Chlorinated hydrocarbons such as chloroform and ethylene dichloride; Ketones such as acetone and methyl isobutyl ketone; Ethers such as tetrahydrofuran and dioxane; Cellosolves such as methyl cellosolve and butyl cellosolve Etc. The microcapsules prepared by the above method are once separated from these solvents by centrifugation or filtration, and then stirred and redispersed with water and the necessary solvent, and used for the intended present invention. A recording liquid that can be used is obtained. The average particle diameter of the encapsulated pigment obtained by the above method is preferably 50 nm to 180 nm.

  By coating the resin in this way, the pigment adheres firmly to the printed material, whereby the scratching property of the printed material can be improved.

〔dye〕
As the dye used in the recording liquid, dyes classified into acid dyes, direct dyes, basic dyes, reactive dyes, and food dyes in the color index and having excellent water resistance and light resistance are used. These dyes may be used as a mixture of a plurality of types, or may be used as a mixture with other color materials such as pigments as necessary. These colorants are added within a range that does not impair the effects of the present invention.

(A) As an acid dye and a food dye,
C. I. Acid Yellow 17, 23, 42, 44, 79, 142
C. 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
C. I. Acid Blue 9, 29, 45, 92, 249
C. I. Acid Black 1, 2, 7, 24, 26, 94
C. I. Food Yellow 3, 4
C. I. Food Red 7, 9, 14
C. I. Food Black 1, 2

(B) As a direct dye,
C. I. Direct yellow 1,12,24,26,33,44,50,86,120,132,142,144
C. I. Direct Red 1,4,9,13,17,20,28,31,39,80,81,83,89,225,227
C. I. Direct orange 26, 29, 62, 102
C. I. Direct blue 1,2,6,15,22,25,71,76,79,86,87,90,98,163,165,199,202
C. I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171

(C) As a basic dye,
C. 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. 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
C. 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
C. I. Basic Black 2,8

(D) As a reactive dye,
C. I. Reactive Black 3, 4, 7, 11, 12, 17
C. I. Reactive Yellow 1,5,11,13,14,20,21,22,25,40,47,51,55,65,67
C. I. Reactive Red 1,14,17,25,26,32,37,44,46,55,60,66,74,79,96,97
C. I. Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95, etc. can be used.

[Additives and physical properties common to dyes and pigments]
In order to make the recording liquid used in the image forming apparatus according to the present invention have the desired physical properties or to prevent clogging of the nozzles of the recording head due to drying, a water-soluble organic solvent is used in addition to the colorant. It is preferable to do. The water-soluble organic solvent includes a wetting agent and a penetrating agent. The wetting agent is added for the purpose of preventing clogging of the nozzles of the recording head due to drying.

  Specific examples of the wetting agent include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, 1,3-butanediol, 1,3-propanediol, and 2-methyl-1,3-propane. Diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 1,2 Polyhydric alcohols such as 1,4-butanetriol, 1,2,3-butanetriol, and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene Polyhydric alcohol alkyl ethers such as glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether and propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether Forehead: Nitrogen-containing heterocyclic compounds such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam; formamide, N-methylformamide, Amides such as formamide and N, N-dimethylformamide; monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethyl And amines such as ruamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol, propylene carbonate, ethylene carbonate, and γ-butyrolactone. These solvents are used alone or in combination with water.

  Further, the penetrant is added for the purpose of improving the wettability between the recording liquid and the recording material and adjusting the penetration speed. As the penetrant, those represented by the following formulas (I) to (IV) are preferable. That is, a polyoxyethylene alkylphenyl ether surfactant of formula (I) below, an acetylene glycol surfactant of formula (II), a polyoxyethylene alkyl ether surfactant of formula (III) below and formula (IV) The polyoxyethylene polyoxypropylene alkyl ether-based surfactant (1) can reduce the surface tension of the liquid, so that the wettability can be improved and the penetration rate can be increased.

（Ｒは分岐していても良い炭素数６〜１４の炭化水素鎖、ｋは５〜２０）

(R is an optionally branched hydrocarbon chain having 6 to 14 carbon atoms, k is 5 to 20)

（ｍ、ｎは０〜４０）

(M and n are 0 to 40)

（Ｒは分岐していても良い炭素数６〜１４の炭化水素鎖、ｎは５〜２０）

(R is an optionally branched hydrocarbon chain having 6 to 14 carbon atoms, n is 5 to 20)

（Ｒは炭素数６〜１４の炭化水素鎖、ｍ、ｎは２０以下の数）

(R is a hydrocarbon chain having 6 to 14 carbon atoms, m and n are numbers of 20 or less)

  Other than the compounds of the above formulas (I) to (IV), for example, diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, tetraethylene glycol chlorophenyl Use alkyl and aryl ethers of polyhydric alcohols such as ethers, nonionic surfactants such as polyoxyethylene polyoxypropylene block copolymers, fluorine-based surfactants, lower alcohols such as ethanol and 2-propanol However, diethylene glycol monobutyl ether is particularly preferable.

  The surface tension of the recording liquid used in the image forming apparatus according to the present invention is preferably 10 to 60 N / m, and 15 to 30 N from the viewpoint of achieving both wettability with the recording medium and droplet formation. More preferably, it is / m.

  Similarly, the viscosity of the recording liquid is preferably in the range of 1.0 to 20 mPa · s, and from the viewpoint of ejection stability, it is preferably in the range of 5.0 to 10 mPa · s.

  The pH of the recording liquid is preferably in the range of 3 to 11, and more preferably in the range of 6 to 10 from the viewpoint of preventing corrosion of the metal member in contact with the liquid.

  Further, the recording liquid can contain an antiseptic / antifungal agent. By containing the antiseptic / antifungal agent, the growth of bacteria can be suppressed, and the storage stability and the image quality stability can be improved. As antiseptic / antifungal agents, benzotriazole, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, isothiazoline compounds, sodium benzoate, sodium pentachlorophenol, and the like can be used.

  Further, the recording liquid can contain a rust inhibitor. By containing a rust preventive agent, a coating can be formed on the metal surface in contact with the liquid, such as a head, and corrosion can be prevented. As the rust inhibitor, for example, acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like can be used.

  Further, the recording liquid can contain an antioxidant. By containing an antioxidant, even when radical species that cause corrosion are generated, the antioxidant can be prevented by eliminating the radical species.

  Typical examples of the antioxidant include phenolic compounds and amine compounds. Examples of the phenolic compounds include hydroquinone and gallate compounds, 2,6-di-tert-butyl-p-cresol, and 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′-thiobis (3-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-4-hydroxybenzyl) benzene, Hindered materials such as lith (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, tetrakis [methylene-3 (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate] methane Phenol compounds are exemplified, and amine compounds include N, N′-diphenyl-p-phenylenediamine, phenyl-β-naphthylamine, phenyl-α-naphthylamine, N, N′-β-naphthyl-p-phenylene. Examples include diamine, N, N′-diphenylethylenediamine, phenothiazine, N, N′-di-sec-butyl-p-phenylenediamine, 4,4′-tetramethyl-diaminodiphenylmethane, and the like. As the latter, sulfur compounds and phosphorus compounds are representative, but as sulfur compounds, dilauryl thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, Examples include myristyl thiodipropionate, distearyl β, β′-thiodibutyrate, 2-mercaptobenzimidazole, dilauryl sulfide and the like, and phosphorus compounds include triphenyl phosphite, trioctadecyl phosphite, tridecyl. Examples include phosphite, trilauryl trithiophosphite, diphenylisodecyl phosphite, trinonylphenyl phosphite, distearyl pentaerythritol phosphite.

  The recording liquid can contain a pH adjusting agent. Examples of the pH adjuster include hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, lithium carbonate, Examples include alkali metal carbonates such as sodium carbonate and potassium carbonate, amines such as diethanolamine and triethanolamine, boric acid, hydrochloric acid, nitric acid, sulfuric acid, and acetic acid.

  Here, the recording liquid used in the image forming apparatus according to the present invention preferably has a surface tension in the range of 15 to 30 N / m. As described above, since the recording liquid having a low surface tension can be used, the fixability of the recording liquid on the recording medium is improved. In addition, it is preferable that the recording liquid to be used contains a fluorosurfactant, which makes it possible to form an image with good color developability. Furthermore, it is preferable to use a pigment-based recording liquid, which enables high-quality image formation with excellent weather resistance and water resistance even when the recording medium is plain paper. In this case, a self-dispersing pigment-based recording liquid or a polymer-dispersed pigment-based recording liquid is used as the pigment-based recording liquid, so that it is particularly excellent in weather resistance, water resistance, and scratch resistance even on plain paper. Image quality can be formed. In addition, by using a resin-coated pigment-based recording liquid, it is possible to form a high-quality image having excellent weather resistance, water resistance, and scratch resistance even on plain paper.

1 is an exploded perspective view illustrating an example of a first embodiment of a droplet discharge head according to the present invention. It is sectional explanatory drawing of the direction along the liquid chamber longitudinal direction of the head. It is a cross-sectional explanatory drawing along a liquid chamber short direction similarly. It is an expanded sectional explanatory view of the nozzle part of the nozzle plate of the same droplet discharge head. It is explanatory drawing with which it uses for description of 1st Embodiment of the manufacturing method of the droplet discharge head which concerns on this invention. It is explanatory drawing with which it uses for description of 2nd Embodiment of the manufacturing method of the droplet discharge head which concerns on this invention. FIG. 6 is an enlarged cross-sectional explanatory diagram of a nozzle portion of a nozzle plate in a second embodiment of a droplet discharge head according to the present invention. It is an expanded sectional explanatory view of the nozzle part of the nozzle plate in a 3rd embodiment of the droplet discharge head concerning the present invention. It is explanatory drawing with which it uses for description of 3rd Embodiment of the manufacturing method of the droplet discharge head which concerns on this invention. It is explanatory drawing with which it uses for description of 4th Embodiment of the manufacturing method of the droplet discharge head which concerns on this invention. 1 is an overall configuration explanatory view showing an example of an image forming apparatus according to the present invention. FIG. 2 is an explanatory plan view of a main part of the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Channel unit 2 ... Actuator unit 11 ... Channel plate 12 ... Vibration plate 13 ... Nozzle plate 14 ... Nozzle 16 ... Liquid chamber 61 ... Nozzle tip hole 62 ... Nozzle formation member 63 ... Polyimide / polyamide resin layer 64 ... Organosilicon Compound layer 65 ... Fluorine-based water repellent layer 71 ... Nozzle tip hole 72 ... Nozzle forming member 73 ... Polyimide / polyamide resin layer 74 ... Si oxide film layer 75 ... Silicone resin layer

Claims (4)

In a manufacturing method of a droplet discharge head, which has a nozzle forming member made of a metal member that forms a nozzle for discharging a droplet, pressurizes a liquid in a liquid chamber to which the nozzle communicates, and discharges the droplet from the nozzle.
Processing the front hole in the portion corresponding to the nozzle hole of the metal member,
Wherein a liquid polyimide resin or a polyamide resin on both surfaces of the metallic member was coated so as to close Nde write enters first hole formed by said destination drilling, only to form a water-repellent layer on the discharge side,
A laser is irradiated from the flow path forming side to the peripheral portion of the front hole processing, and the polyimide resin or polyamide resin in the vicinity of the nozzle on the flow path side and the polyimide resin or polyamide resin on the nozzle edge and the water repellent layer are removed. A method for manufacturing a droplet discharge head.   The method of manufacturing a droplet discharge head according to claim 1, wherein the water repellent layer is formed by sequentially laminating an organic silicon compound layer and a fluorine-based water repellent layer.   The method of manufacturing a droplet discharge head according to claim 1, wherein the water repellent layer is formed by applying a silicone resin.   4. The method of manufacturing a droplet discharge head according to claim 3, wherein the water repellent layer is formed by sequentially laminating a silicon oxide film layer and a silicone resin.

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