JP5573174B2 - Inkjet head, inkjet head manufacturing method, and inkjet recording method - Google Patents

Description

  The present invention relates to an inkjet head that can be used for the electronics industry, a method for manufacturing the inkjet head, and an inkjet recording method.

  Liquid ejecting heads that can eject liquid in the form of minute droplets have become widespread, for example, as ink jet heads used in ink jet printers that record images by ejecting ink droplets onto recording paper.

  As a typical ink ejection method for an ink jet head, a method is used in which water in an ink is vaporized and expanded by applying heat to an electric resistor disposed in a pressurizing chamber, and pressure is applied to the ink for ejection. Each of the piezoelectric bodies can be formed by using part of the flow path member constituting the pressurizing chamber as a piezoelectric body or by installing a piezoelectric body in the flow path member and selectively driving the piezoelectric bodies corresponding to the plurality of nozzles. There is a method in which a liquid is discharged from a nozzle by deforming a pressurizing chamber based on the dynamic pressure of the nozzle.

  In recent years, attempts have been made to eject various inks by an inkjet method for industrial use. For example, solvent-based inks and ultraviolet curable inks are used for outdoor exhibitions, and acid inks and alkaline inks are used in addition to solvent-based inks and ultraviolet curables for the production of electronic industry parts. ing.

  In particular, alkaline inks used for the production of electronic industry parts have a very high pH and are much more corrosive than general alkaline water-based inkjet inks. While the pH of general alkaline water-based ink-jet ink is 10 to 11 at the highest, the alkaline ink used for the production of electronic industry parts is alkaline of pH 13 or higher.

  On the other hand, for the purpose of sucking ink in the inkjet head, a rubber suction cap is pressed against the head and brought into close contact with the head to reduce pressure by sucking ink from the nozzle and recovering nozzle clogging. . For maintenance, the surface of the nozzle plate facing the recording medium is wiped with an elastic blade such as rubber to remove ink remaining on the nozzle formation surface.

  On the head side, a member (hereinafter referred to as a cap receiving member) is provided so as to be in close contact with the suction cap so as to surround the periphery of the nozzle plate. The cap receiving member increases the contact area with the cap to reduce air leakage, so that suction is performed efficiently and the blade pressure is distributed to both the nozzle plate and the cap receiving member during wiping. This is used to reduce the pressure applied to the nozzle plate and protect the water repellent layer of the nozzle plate.

  After the suction of the cap receiving member, it is difficult for the ink to remain when the suction cap is removed. Further, when the nozzle plate is wiped for maintenance, the cap receiving member is wiped at the same time so that no ink remains. If a large amount of ink remains, ink adheres to the nozzle plate, which adversely affects the emission stability.

  For this purpose, the cap receiving surface of the cap receiving member is provided with an ink repellent layer to facilitate ink repelling.

  However, highly alkaline inks used for the manufacture of electronic industry parts have the property of deteriorating the adhesion between the water-repellent layer of the cap receiving member used in the inkjet head and the cap receiving member. If it is used for a long time, the water repellent layer of the cap receiving member is peeled off, and even if it is wiped for maintenance, the ink remains without being wiped off, so that the ink ejection becomes unstable.

  In particular, corrosion tends to start from the boundary between the area where the ink repellent layer is applied and the area where the ink repellent layer is not applied on the side surface of the cap receiving member, and the ink repellent layer tends to peel off from that portion.

  In Patent Document 1, a thin plate-like nozzle cover that covers a part of the nozzle forming surface of the nozzle plate and the periphery thereof is subjected to ink repellent treatment. The nozzle cover is bent to cover the side surface of the inkjet head. The ink repellent layer of the nozzle cover is provided by vapor deposition or coating with a spin coater or a wire bar.

  However, this ink repellent layer has a boundary at the end of the side surface, and ink droplets generated by the maintenance operation and ink mist generated by the printing operation adhere to the boundary. When highly alkaline ink adheres to the boundary, peeling proceeds from there.

  In Patent Document 1, when the ink repellent layer is applied by a spin coater or a wire bar, the base material of the nozzle cover must be flat, and it is necessary to bend it after application to form the shape of the nozzle cover. This method has the drawback that the ink repellent layer is easily damaged when bent, the ink repellency is lowered, and the highly alkaline ink is easily corroded from the scratched portion.

  In the case of vapor deposition, the ink-repellent layer can be provided after the cap receiving member is bent to form the vapor-deposited layer. However, vapor deposition has poor work efficiency, and the ink-repellent layer provided by vapor deposition has a drawback of low durability.

Japanese Patent Laid-Open No. 2006-256013

  An object of the present invention is to provide an ink jet head capable of emitting light stably even when used for a long period of time, even when a highly corrosive ink is used.

  The object of the present invention has been achieved by the following means.

1. There is a cap receiving member around the nozzle plate, and the cap receiving member is provided with an ink repellent layer on a base material, and the ink repellent layer is the entire surface of the cap receiving surface of the base material of the cap receiving member. An inkjet head covering the entire side surface and part of the back surface ,
The inkjet head further has a housing, and the housing and the back surface of the cap receiving member are bonded and sealed, and the region covered with the ink repellent layer on the back surface of the cap receiving member and the region An ink-jet head, wherein the cap receiving member and the housing are bonded to each other by an epoxy adhesive across the back surface beyond the surface.

2 . 2. The ink jet head according to 1 , wherein the side surface of the base material of the cap receiving member has a surface roughness larger than that of the cap receiving surface of the base material.

3 . 3. The ink jet head according to 1 or 2 , wherein the ink repellent layer contains a heat-meltable fluororesin.

4 . 4. The ink jet head according to any one of 1 to 3 , wherein an ink repellent film is applied to a cap receiving surface and a side surface of the cap receiving member, and then the cap receiving surface of the cap receiving member is faced up to form an ink repellent layer. A method for producing an ink jet head, wherein the heat treatment is performed at a melting point or higher.

5 . An alkaline ink that is a solution of 0.1N to 10N NaOH or KOH is obtained by the inkjet head according to any one of 1 to 3 or the inkjet head manufactured by the method for manufacturing the inkjet head according to 4 above. An inkjet recording method characterized by emitting light.

  According to the present invention, it is possible to provide an ink jet head capable of emitting light stably even when used for a long period of time because the water-repellent film does not peel off even when highly corrosive ink is used.

Recording operation by inkjet head Inkjet head Cross section of chip Cross section of inkjet head Enlarged view of the upper right part of FIG. Method for applying cap receiving surface and side surface of cap receiving member Method for applying a cap receiving surface of a cap receiving member

(Inkjet head)
The ink jet head will be described with reference to the drawings.

  FIG. 1 is a schematic perspective view showing an operation when recording on the recording medium B by the ink jet head A. FIG. X is the moving direction of the inkjet head when printing while ejecting ink from the inkjet head, and is parallel to the width direction of the recording medium B.

  Y is the moving direction of the recording medium. When the ink-jet head moves to the end in the width direction of the recording medium while printing, the ink-jet head stops printing, moves in the direction opposite to X, and moves to the end of the recording medium. Return to.

  While the ink jet head returns to the end, the recording medium moves in the Y direction. When the recording medium stops, the ink jet head moves again in the X direction and prints on the recording medium. In this way, the entire surface of the recording medium can be printed.

Z is the upward direction. The ink is ejected downward from the nozzle 11a (the direction opposite to Z) and landed on the recording medium B. The cap receiving member 3 and the nozzle plate 11 of the inkjet head A are configured so that one surface thereof faces the recording medium and is parallel to the recording medium. (Hereafter, the surface facing the recording medium of the inkjet head is called the front surface)
The ink is supplied to the inkjet head A from an ink tank (not shown) through an ink supply tube (not shown).

  In order to eject ink like an image, a drive signal is sent from a drive progress generation circuit to an inkjet head through a cable (not shown), and is applied to an actuator in a pressure chamber, thereby applying pressure to the ink.

  FIG. 2 is an example of the configuration of the inkjet head, and is a schematic perspective view of the inkjet head. In the figure, 1 is an actuator, 2 is a housing, 3 is a cap receiving member, and 4 and 5 are adhesive layers.

A nozzle plate 11 in which a large number of nozzles 11 a for discharging ink are arranged is bonded to the front surface of the actuator 1. An ink repellent layer 1 a is provided on the surface of the nozzle plate 11. C is a cut surface of the cross-sectional views of FIGS. 3 and 4 .

  FIG. 3 is a cross-sectional view of a chip having an actuator 1, and the actuator 1 is composed of a long piezoelectric ceramic substrate in which a large number of channels corresponding to each nozzle 11a are arranged in parallel, and a member that generates a pressure change applied to ink. It is.

  Each channel 12 is cut into a straight and elongated groove shape by a diamond blade or the like, and the uncut piezoelectric ceramic constitutes a partition wall 13 between adjacent channels 12 and 12. The depth of each channel 12 gradually decreases as it goes to the right in FIG. 2, and finally disappears. A metal electrode (not shown) is formed on a part of the inner surface of the channel 12.

  Further, a cover substrate 14 made of a non-piezoelectric ceramic substrate or the like is bonded from above each channel 12. In the cover substrate 14, openings 14 a extending over all the channels 12 are formed at positions corresponding to the shallow groove portions of the respective channels 12, and a manifold 15 is provided so as to cover the openings 14 a. And a shallow groove portion of each channel 12, a common ink chamber 16 for distributing ink to each channel 12 is formed.

  The non-piezoelectric ceramic substrate is preferably selected from at least one of alumina, aluminum nitride, zirconia, silicon, silicon nitride, silicon carbide, quartz, and non-polarized PZT, and polarized even when the partition wall 13 is shear-deformed. The piezoelectric ceramic can be reliably supported.

  As a piezoelectric ceramic, a ceramic such as PZT, PLZT, etc., mainly a mixed microcrystal of PbOx, ZrOx, TiOx, a trace amount of metal oxide known as a softening agent or a hardening agent, such as Nb, Zn, Mg, Those containing oxides such as Sn, Ni, La, and Cr are preferable.

  PZT is lead zirconate titanate, which is preferable because it has a high packing density, a large piezoelectric constant, and good workability. When the temperature is lowered after firing, the crystal structure suddenly changes, and PZT becomes a collection of fine crystals in the form of dipoles in which atoms are displaced, one side is positive, and the other side is negative. These spontaneous polarizations are random in direction and cancel each other's polarity, so further polarization processing is required.

  In the polarization treatment, a thin plate of PZT is sandwiched between electrodes, immersed in silicon oil, and polarized by applying a high electric field of about 10 to 35 kV / cm. When a voltage is applied to the polarized PZT at a right angle to the polarization direction, the side wall is sheared and deformed in a diagonal shape in a diagonal direction by the piezoelectric sliding effect, and the volume of the ink chamber expands.

  Gold, silver, aluminum, palladium, nickel, tantalum, and titanium can be used as the material of the metal electrode, and gold and aluminum are particularly preferable from the viewpoint of electrical characteristics and workability. It is formed. Each metal electrode is drawn from the inside of each channel 11 to the upper surface on the rear side (right end in FIG. 3) of the actuator 1 through the shallow groove portion, and is electrically connected to the drive circuit by a signal line (not shown).

  The nozzle plate 11 is formed of plastics such as polyalkylene terephthalate such as PET, polyimide, polyetherimide, polyetherketone, polyethersulfone, polycarbonate, and cellulose acetate. The ink repellent layer 1a is provided to keep the emission angle stable.

  In the actuator 1, when a driving voltage applied from a driving circuit is applied to the metal electrode in each channel 12, the partition wall 13 undergoes shear deformation to cause a pressure change in the channel 12, and the stress in the channel 12 is received. Ink is ejected from the nozzle 11a. The ink ejected from the nozzles 11a flies in the longitudinal direction of the channel 12 and lands on a recording material such as paper.

(Cap receiving member)
The surface (front surface) where the cap receiving member 3 opposes the recording medium is also called a cap receiving surface, and has a function of keeping a negative pressure inside the cap by closely contacting the cap for sucking ink during the nozzle recovery operation. Therefore, the cap receiving surface is preferably smooth.

  The cap receiving member 3 is made of, for example, acrylic, polycarbonate, polyetherimide, modified PPE, aluminum, stainless steel, and the like, and an opening having substantially the same shape as the ink repellent layer 1a on the nozzle surface of the actuator 1 is formed at the substantially central portion thereof. The nozzle plate 11 of the actuator 1 is disposed so as to face the opening 31 by fitting the actuator 1 into the opening.

  Accordingly, in the inkjet head A, a wide flat space is formed around the nozzle plate 11 by the cap receiving member 3 and is forced from the nozzle 11a of the actuator 1 using a suction cap (not shown). The ink can be sucked by bringing the suction cap into close contact with the surface of the cap receiving member 3.

  Ink repellent layers 3a and 1a are provided on the front surface of the cap receiving member 3 and the front surface of the nozzle plate 11 so that ink can be easily removed when wiping with a blade. The front surface of the cap receiving member 3 is preferably smooth so that the ink can be easily removed when wiped by the blade.

  Since the ink repellency of the ink repellent layer 1a of the nozzle plate is particularly important for ink emission, the suction cap is not in contact with the ink repellent layer 1a and only with the ink repellent layer 3a in order to prevent scratches and dirt from adhering. Touch and stick.

  FIG. 4 is a cross-sectional view of the ink jet head taken along the cutting plane C in FIG. FIG. 5 is an enlarged view of the upper right portion of FIG. The ink repellent layer 3a provided on the base material 3b of the cap receiving member covers a part of the front surface 3c, the side surface 3d and the back surface 3e of the base material 3b. Here, the side surface of the base material 3b of the cap receiving member is an external surface perpendicular to the front surface 3c, and the back surface is a surface opposite to the front surface 3c.

  The cap receiving member 3 and the actuator 1 are sealed with an adhesive layer 5 so that the cap for sucking ink adheres to the cap receiving member, and air leaks when the inside of the cap is decompressed. It is preventing.

  Between the cap receiving member 3 and the housing 2, an adhesive layer 4 covers the ink repellent layer on the back surface of the cap receiving member and is filled to a region where no ink repellent layer is provided. The body 2 is bonded. Thus, it is presumed that by covering the end portion of the ink repellent layer with the adhesive, it is possible to prevent the ink repellent layer from being eroded by the ink from the end portion and peeling off.

  The side surface of the base material of the cap receiving member 3 is preferably larger in surface roughness than the front surface of the base material. By reducing the surface roughness of the front surface and increasing the surface roughness of the side surface, the ink-repellent layer and the base material of the cap receiving member are in contact with each other while satisfying the adhesion to the cap and the ink removal property by wiping. By increasing the area, peeling can be suppressed.

  The thickness of the cap receiving member 3 is preferably 1 mm or more and 3 mm or less. If it is 1 mm or more, the ink when wiped spreads and hardly reaches the end of the ink repellent layer, and if it is 3 mm or less, the mass of the inkjet head can be kept within a practical range. Cost can be reduced.

  It is preferable that the adhesive layer for bonding the cap receiving member and the housing swells outward from the side surface of the cap receiving member. Thereby, it is possible to further suppress the ink from penetrating to the end of the ink repellent layer on the back surface of the cap receiving member.

(Ink repellent layer)
The ink repellent layer 3a preferably contains a heat-meltable fluororesin. The ink repellent layer containing a fluororesin has excellent ink repellency with respect to a wide range of ink types, and is difficult to permeate alkaline ink and has excellent durability.

  Before applying the ink repellent layer to the base material of the cap receiving member, it is necessary to form the base material of the cap receiving member into a final shape to be incorporated into the ink jet head. It is preferable because there is nothing. The molding means bending, cutting and polishing.

  Application of the ink repellent layer can improve the durability of the ink repellent layer by applying a coating liquid containing a fluororesin, drying, and then heat treating to melt the fluororesin.

  The coating liquid for the ink repellent layer contains a solvent such as water in addition to the fluororesin, and may contain a surfactant or the like.

  Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer. Combined (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), etc. can be used, but FEP has a low critical surface tension, excellent ink repellency, and a heat treatment temperature. It is preferable in that the melt viscosity at 300 ° C. to 400 ° C. is low and a uniform film can be formed.

  When polyoxyethylene alkyl ether is used as the surfactant, it is possible to further improve the durability of the ink repellent layer.

  As an application method for forming the ink repellent layer, spray coating, spin coating, brush coating, dip coating, wire bar coating, and the like can be used. In the present invention, spray coating is performed on the front surface in a single application step. It is preferable because the side surfaces can be coated and efficient coating becomes possible.

  FIG. 6 shows a state where the front surface and the side surface are spray-coated in one application process. On the other hand, when the base material of the cap receiving member is densely arranged as shown in FIG. 7, the application efficiency can be increased, but only the front surface is coated.

  As a method of providing an ink repellent layer on a part of the back surface, after masking the non-coated surface of the back surface, a method of coating the back surface, and heating before the fluidity of the coating liquid applied to the side surface is lost, the side surface is heated. Although the method by which the coating liquid of this wets a part of back surface etc. is mentioned, the latter is preferable from the point of the efficiency of a coating process.

  From the viewpoint of the adhesive force between the housing and the cap receiving member, it is preferable that the width of the ink repellent layer to spread from the end of the back surface is narrower than the width of the adhesive surface between the housing and the cap receiving member.

  After coating and drying, the coating layer is heat treated. The treatment temperature is preferably equal to or higher than the melting point of the ink repellent layer, and particularly preferably from 300 ° C to 400 ° C.

(Epoxy adhesive)
The epoxy adhesive is a combination of an epoxy compound and a curing agent.

  Epoxy compounds include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, aromatic epoxy compounds such as novolac type epoxy resins, and alicyclic epoxies such as 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexylcarboxylate. And aliphatic epoxies such as triglycidyl glycerol, but aromatic epoxies are preferred.

  Examples of the curing agent include polyaddition curing agents, cationic polymerization initiators, and anionic polymerization initiators, and polyaddition curing agents and anionic polymerization initiators are preferred. Examples of the polyaddition type curing agent include diethylenetriamine, triethylenetetramine, cyclohexanediamine, and polyamidoamine. Examples of the anionic polymerization initiator include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2,4,6-tris-dimethylaminomethylphenol.

  Since the cap receiving member and the casing are relatively large in thickness, strain stress due to thermal expansion tends to increase, and therefore the curing temperature is preferably in the range of room temperature to 60 ° C.

(ink)
As the ink, any ink can be applied, and examples thereof include acidic aqueous ink, weak alkaline aqueous ink having a pH of 6 to 11, solvent ink, ultraviolet curable ink, and highly alkaline ink. The present invention is particularly effective in preventing peeling due to corrosion. The ink that exhibits is a highly alkaline ink.

The highly alkaline ink is an ink in which NaOH or KOH is dissolved in a mixed solution of water and a water-soluble organic solvent, and particularly when an ink having a NaOH or KOH concentration of 0.1 N or more is used. The effect is remarkable. (N is the specified concentration and is gram equivalent / L.)
Examples of the water-soluble organic solvent include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, glycerin, triethylene glycol, ethanol, propanol and the like.

(Cap receiving member)
(Preparation of cap receiving member 1)
A base plate of a cap receiving member was produced by punching a stainless steel plate (made of SUS316) having a thickness of 1.1 mm. The surface roughness Ra of the cap receiving surface was 0.81 μm, and the surface roughness Ra of the side surface was 1.45 μm.

  The base materials of the cap receiving member were arranged without gaps as shown in FIG. 1, and the following ink repellent material 1 was applied by spray so that the thickness after the following heat treatment was about 5 μm.

  After application, air is blown at room temperature, the solvent evaporates, and the coating solution does not flow even when the cap receiving member is set up vertically. Then, the coating surface is placed in an oven at 350 ° C. and heat-treated for 5 hours. Thus, an ink repellent layer was provided, and a cap receiving member 1 was produced.

(Preparation of cap receiving member 2)
In the production of the cap receiving member 1, the ink-repellent material 1 was changed to a method in which the ink-repellent material 2 was spray-coated and dried at room temperature, and then the ink-repellent material 3 was spray-coated and dried at room temperature. Similarly, the cap receiving member 2 was produced. In addition, the application amount of the ink repellent material 2 and the ink repellent material 3 was the same, and it applied so that the thickness after heat processing of all the laminated ink repellent layers might be set to 5 micrometers.

(Preparation of cap receiving member 3)
In the production of the cap receiving member 1, the ink receiving material is arranged in the direction perpendicular to the cap receiving surface so that the cap receiving members are arranged at intervals of 3 mm as shown in FIG. A cap receiving member 3 was produced in the same manner except that spray coating was applied from a direction inclined 45 degrees from the same.

(Preparation of cap receiving member 4)
In the production of the cap receiving member 3, the application of the ink repellent material 1 was changed to a method of spraying the ink repellent material 2 and drying at room temperature, and then spraying the ink repellent material 3 and drying at room temperature. Similarly, the cap receiving member 4 was produced. In addition, the application amount of the ink repellent material 2 and the ink repellent material 3 was the same, and it applied so that the thickness after heat processing of all the laminated ink repellent layers might be set to 5 micrometers.

(Preparation of cap receiving member 5)
In the production of the cap receiving member 3, while the coating liquid is fluid so that a part of the ink-repellent layer after the heat treatment wets the back surface and covers the back surface with a width of 0.5 mm from the end, 350 ° C. The cap receiving member 5 was produced in the same manner except that it was put in the oven.

(Preparation of cap receiving member 6)
In the production of the cap receiving member 5, the cap receiving member 6 is formed in the same manner except that the application and drying of the ink repellent material 1 are changed to the following (laminated application of ink repellent material 2 and ink repellent material 3 and drying). Produced. In addition, the application amount of the ink repellent material 2 and the ink repellent material 3 was the same, and it applied so that the thickness after heat processing of all the laminated ink repellent layers might be set to 5 micrometers.

(Laminated coating of ink repellent material 2 and ink repellent material 3 and drying)
After the ink repellent material 2 is spray-coated and dried at room temperature, the ink-repellent material 3 is spray-coated and dried at room temperature. While the coating solution was fluid so as to cover the back surface with a width of 5 mm, it was put into an oven at 350 ° C.

(Preparation of cap receiving member 7)
In the production of the cap receiving member 5, the base material is a stainless steel plate (made of SUS316) having a thickness of 0.9 mm (the surface roughness Ra of the cap receiving surface is 0.92 μm, and the surface roughness Ra of the side surface is 1.46 μm. The cap receiving member 7 was produced in the same manner except that it was changed to.

(Preparation of cap receiving member 8)
In the production of the cap receiving member 6, the base material is a stainless steel plate having a thickness of 0.9 mm (made of SUS316) (the surface roughness Ra of the cap receiving surface is 0.92 μm, and the surface roughness Ra of the side surface is 1.46 μm. The cap receiving member 8 was produced in the same manner except that the above.

(Preparation of cap receiving member 9)
In the production of the cap receiving member 5, the base material was a molded product of aluminum die cast having a thickness of 2.5 mm (the surface roughness Ra of the cap receiving surface was 0.99 μm, and the surface roughness Ra of the side surface was 1.42 μm. The cap receiving member 9 was produced in the same manner except that it was changed to.

(Preparation of cap receiving member 10)
In the production of the cap receiving member 6, the base material was a molded product of aluminum die cast having a thickness of 2.5 mm (the surface roughness Ra of the cap receiving surface was 0.99 μm, and the surface roughness Ra of the side surface was 1.42 μm. The cap receiving member 10 was manufactured in the same manner except that the above.

(Preparation of cap receiving member 11)
In the production of the cap receiving member 5, the base material is a molded product of aluminum die cast having a thickness of 1.5 mm (the surface roughness Ra of the cap receiving surface is 0.87 μm, and the surface roughness Ra of the side surface is 0.87 μm. The cap receiving member 11 was produced in the same manner except that.

(Preparation of cap receiving member 12)
A cap receiving member 12 was prepared in the same manner except that the surface roughness Ra of the cap receiving surface of the base material was 0.91 μm and the surface roughness Ra of the side surface was 1.47 μm.

(Preparation of cap receiving member 13)
In the production of the cap receiving member 12, after application, air is blown at room temperature, the solvent evaporates, and the coating liquid does not flow even when the cap receiving member is set up vertically. And heat-treated for 5 hours.

  The surface roughness of the front and side surfaces of the cap receiving members 1 to 13 was adjusted by polishing.

(Measurement of surface roughness)
Ra (center line surface roughness) defined by JIS B 0601 was measured by WYKO.

(Coating solution)
Ink repellent materials 1, 2, and 3, which are coating solutions applied to the base material of the cap receiving member, are described below.

Ink repellent material 1: Polyflon PTFE TC-7109BK (manufactured by Daikin Industries)
Ink repellent material 2: Polyflon PTFE EK-1909S21L (manufactured by Daikin Industries)
Ink repellent material 3: NEOFLON FEP ND-4 (manufactured by Daikin Industries)
The melting point of PTFE excluding the solvent is 327 ° C., and the melting point of the ink repellent layer of the ink repellent material 1 is also 327 ° C. The melting point of FEP is 270 ° C., and the melting point of the ink repellent layer of the ink repellent material 2 is 270 ° C. or less.

(Observation of coated surface)
When the coated surfaces of the cap receiving members 1 to 13 were observed after the heat treatment, the ink repellent layers of the cap receiving members 1 and 2 were almost applied only to the cap receiving surface. The ink repellent layers of the cap receiving members 3, 4, and 13 were coated on the entire cap receiving surface and side surfaces, and the back surface was not coated. The ink repellent layers of the cap receiving members 5 to 12 were applied to the entire cap receiving surface and side surfaces, and the back surface was applied to about 0.5 mm from the end.

(Preparation of inkjet head 1)
A chip having the structure shown in FIG. 3 was produced according to the following method.

  The resist film is adhered to the upper surface of the substrate made of PZT (lead zirconate titanate, thickness 700 μm, Curie temperature 210 ° C.), and the diamond blade is moved parallel to the upper surface, and the same from the end of PZT to the middle of PZT Cutting at a depth formed a plurality of parallel straight grooves. From the cutting end point of the groove on the way to the end of the PZT, the resist was peeled off with the same width as the groove along the extension line from the groove. An aluminum layer was formed by vapor deposition on the upper side surface and the upper surface of the partition wall separating adjacent grooves. By stripping off the resist, the resist on the top of the partition and the aluminum layer deposited thereon were removed together to form electrodes individually provided on the wall surface of each groove and a plurality of extraction electrodes led therefrom. .

  A cover plate (depolarized PZT having a thickness of 700 μm) was bonded to the surface of the partition top portion from which the resist was peeled to form a chip having a plurality of ink flow paths.

  In the chip manufactured in this way, drive walls and flow paths made of piezoelectric elements are alternately arranged in parallel.

  As shown in FIG. 3, the cover plate is shorter than the substrate, and is joined so that the extraction electrode is exposed at a portion not covered by the cover plate.

  The take-out electrode was protected with a masking tape, and a protective film made of polyparaxylylene was formed on the inner surface of the pressure chamber including the drive electrode and on the end of the pressure chamber, thereby producing an actuator.

  A common ink chamber was formed by bonding a manifold to the opening of the cover plate, and a nozzle plate having an ink repellent layer was bonded to the other opening of the actuator to produce a chip.

(Adhesion of cap receiving member and chip)
A chip was inserted from the opening of the cap receiving surface of the cap receiving member 1, the cap receiving surface and the surface of the nozzle plate were aligned, the following epoxy adhesive was injected into the gap, and heat-cured at 60 ° C. for 3 hours.

(FPC and ink tube connection, housing adhesion)
The FPC connected to the external drive signal generating circuit was connected to the take-out electrode of the chip to which the cap receiving member 1 was bonded as described above by ACF.

  An ink tube connected to an external ink tank was connected to the manifold.

  After connecting the FPC and the ink tube as described above, the following epoxy adhesive is applied to the back surface of the cap receiving member, an aluminum die-cast casing having a thickness of 1.5 mm is adhered, and heat-cured at 60 ° C. for 6 hours. Inkjet head 1 was produced. In addition, the application amount of the adhesive was set to a thickness rising from the side surface of the cap receiving member after bonding.

(Epoxy adhesive)
Epicoat 807 (Bisphenol F type epoxy resin; made by Japan Epoxy Resin)
10 parts by mass 2-ethyl-4-methylimidazole 1 part by mass (production of inkjet heads 2 to 13)
Ink jet heads 2 to 13 were produced in the same manner except that the cap receiving member 1 was changed to the cap receiving members 2 to 13 in the production of the ink jet head 1.

(Evaluation of ink durability)
Using the inkjet heads 1 to 13, the operation of ejecting the following highly alkaline ink for 8 hours per day was continued for 1 month. Every day, before the ejection, the cap was brought into close contact with the cap receiving surface and ink was sucked. After the ejection, the ink-repellent layer was observed, and the cap was kept in close contact with the cap receiving surface and stored until the next ejection.

(Composition of highly alkaline ink)
Water 100 parts by mass Glycerin 100 parts by mass NaOH 8 parts by mass (Evaluation criteria)
○: No peeling even after one month has elapsed Δ: Although peeling does not occur until the lapse of 20 days, peeling occurs in less than one month ×: Peeling occurs after 8 days The results are shown in Table 1.

  From Table 1, it can be seen that an ink jet head using a cap receiving member in which a part of the front surface, side surface and back surface is covered with an ink repellent layer has high ink resistance. It can also be seen that the ink durability is further improved when the thickness of the base material of the cap receiving member is 1 to 3 mm or when the side surface roughness is larger than the front surface roughness.

DESCRIPTION OF SYMBOLS 1 Actuator 1a Ink repellent layer 2 Case 3 Cap receiving member 3a Ink repellent layer 3b Base material of cap receiving member 3c Cap receiving surface of base material of cap receiving member 3d Side surface of base material of cap receiving member 3e Base of cap receiving member Back surface of material 4 Adhesive layer 5 Adhesive layer 11 Nozzle plate 11a Nozzle 12 Channel 13 Partition wall 14 Cover plate 15 Manifold 16 Common ink chamber A Inkjet head B Recording medium C Cut surface X Inkjet head moving direction Y Recording medium moving direction Y Z upward

Claims (5)

There is a cap receiving member around the nozzle plate, and the cap receiving member is provided with an ink repellent layer on a base material, and the ink repellent layer is the entire surface of the cap receiving surface of the base material of the cap receiving member. An inkjet head covering the entire side surface and part of the back surface ,
The inkjet head further has a housing, and the housing and the back surface of the cap receiving member are bonded and sealed, and the region covered with the ink repellent layer on the back surface of the cap receiving member and the region An ink-jet head, wherein the cap receiving member and the housing are bonded to each other by an epoxy adhesive across the back surface beyond the surface. 2. The ink jet head according to claim 1 , wherein the side surface of the base material of the cap receiving member has a surface roughness larger than that of the cap receiving surface of the base material. The inkjet head according to claim 1 or 2, wherein the ink-repellent layer contains a heat-fusible fluororesin. In the inkjet head according to any one of claim 1 to 3 after coating the ink-repellent film on the cap receiving surface and the side surface of the cap receiving member, and the top cap receiving surface of the cap receiving member, the ink repellent layer A method for producing an ink jet head, wherein the heat treatment is carried out at a melting point or higher. An alkaline solution which is a solution of 0.1N to 10N NaOH or KOH by the inkjet head according to any one of claims 1 to 3 or the inkjet head manufactured by the method for manufacturing an inkjet head according to claim 4 . An ink jet recording method comprising ejecting ink.

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