JP2008105231A - Liquid repellent film forming method, ink jet head manufacturing method, ink jet head and electronic apparatus - Google Patents

Abstract

A method for obtaining a liquid repellent film having high adhesion to the undercoat layer and excellent in abrasion resistance, an ink jet head provided with a liquid repellent film excellent in abrasion resistance, a method for producing the same, and the ink jet head Providing electronic equipment.
A method for forming a liquid repellent film is a method for forming a liquid repellent film 19 having a liquid repellency on a surface of a substrate, and the plasma polymerized film 17 is formed on one surface side of the substrate. And a second step of introducing a hydroxyl group and / or adsorbed water by oxidizing the surface of the underlayer in a gas atmosphere having a dew point of −40 to 20 ° C. And a third step of forming the liquid repellent film 19 on the base layer that has been subjected to the oxidation treatment.
[Selection] Figure 6

Description

  The present invention relates to a liquid repellent film forming method, an inkjet head manufacturing method, an inkjet head, and an electronic apparatus.

Inks used in ink jet printers are roughly classified into dye systems and pigment systems. In general, when dye-based ink is used, the surface of a component (nozzle plate) that ejects ink is required to be alkali resistant. On the other hand, when pigment-based ink is used, the surface of the nozzle plate is required to be abrasion resistant.
Conventionally, in order to prevent ink from adhering to the surface of the nozzle plate, the nozzle plate has been subjected to a liquid repellent treatment (see, for example, Patent Document 1). In this liquid repellent treatment method, a silicone plasma polymer film used as a base film is modified with UV in a dry oxygen gas atmosphere or a dry inert gas atmosphere to form a liquid repellent film.

However, although the formed liquid repellent film is excellent in alkali resistance, there is a problem that when the pigment-based ink is used, the liquid repellent film is damaged by the pigment particles.
As described above, the surface modification of the base film under the conventional dry oxygen gas or inert gas atmosphere is compatible with pigment-based inks that have been in increasing demand in recent years (withstands wiping in pigment-based inks). A liquid repellent film having excellent abrasion resistance cannot be obtained.

JP 2004-351923 A

  An object of the present invention is to provide a method for obtaining a liquid repellent film having high adhesion of the liquid repellent film to the underlying layer and excellent in abrasion resistance, a method for producing an ink jet head equipped with a liquid repellent film excellent in abrasion resistance, and abrasion resistance Another object of the present invention is to provide an ink jet head provided with a liquid-repellent film that is superior to the above and an electronic device provided with the ink jet head.

Such an object is achieved by the present invention described below.
The liquid repellent film forming method of the present invention is a liquid repellent film forming method for forming a liquid repellent film having liquid repellency on the surface of a substrate,
A first step of forming an underlayer composed of a plasma polymerized film on one surface side of the substrate;
A second step of introducing a hydroxyl group and / or adsorbed water by subjecting the surface of the base layer to an oxidation treatment under a gas atmosphere having a dew point of −40 to 20 ° C .;
And a third step of forming the liquid repellent film on the base layer subjected to the oxidation treatment.
Thereby, since many hydroxyl groups are introduced into the surface of the underlayer, the adhesion between the liquid repellent film and the underlayer is improved, and a liquid repellent film having excellent abrasion resistance can be obtained.

In the liquid repellent film forming method of the present invention, it is preferable that the oxidation treatment is performed so that condensation does not occur on the surface of the base layer.
Thereby, since the energy rays irradiated on the surface of the underlayer are not hindered by condensation, a hydroxyl group can be reliably introduced into the underlayer.
In the liquid repellent film forming method of the present invention, the second step is preferably performed in a gas atmosphere having a dew point of −40 to −20 ° C.
Thereby, since the hydroxyl group is introduced into the underlayer without excess or deficiency, a liquid repellent film excellent in abrasion resistance and alkali resistance can be obtained.

In the liquid repellent film forming method of the present invention, it is preferable that the oxidation treatment is irradiated with energy rays.
Thereby, since it is possible to easily irradiate a desired position of the underlayer, the oxidation treatment can be efficiently performed.
In the liquid repellent film forming method of the present invention, it is preferable that the energy rays are ultraviolet rays or plasma.
Thereby, since the more optimal oxidation process can be performed with respect to the surface of a base layer, an oxidation process can be performed more efficiently.

In the liquid repellent film forming method of the present invention, it is preferable that the oxidation treatment is performed a plurality of times, and at least one of them is performed in the gas atmosphere containing the moisture.
As a result, since the oxidation treatment is performed a plurality of times, more hydroxyl groups can be introduced to the surface of the underlayer, and a liquid repellent film excellent in abrasion resistance can be obtained.

In the liquid repellent film forming method of the present invention, it is preferable that the plasma polymerization film constituting the base layer is made of a silicone material.
Thereby, since a foundation layer is comprised with the silicone material which made the siloxane bond frame | skeleton, the adhesiveness of a foundation layer and a base material improves.
In the liquid repellent film forming method of the present invention, the silicone material is preferably composed of organopolysiloxane.
Thereby, since the underlayer is composed of organopolysiloxane having a siloxane bond as a skeleton, the adhesion between the underlayer and the substrate is further improved.
In the liquid repellent film forming method of the present invention, the liquid repellent film is preferably composed of a metal alkoxide.
As a result, the alkoxyl group of the metal alkoxide and the surface of the underlayer react reliably, so that a liquid-repellent film having high liquid repellency can be easily formed.

An inkjet head manufacturing method of the present invention is an inkjet head manufacturing method for manufacturing an inkjet head in which a liquid repellent film having liquid repellency is formed on the surface of a nozzle plate having nozzle holes,
A first step of forming a plasma polymerization film on the surface of the nozzle plate on the droplet discharge side;
A second step of introducing a hydroxyl group and / or adsorbed water by subjecting the surface of the plasma polymerized film to an oxidation treatment under a gas atmosphere having a dew point of −40 to 20 ° C .;
And a third step of forming the liquid repellent film on the plasma-polymerized film subjected to the oxidation treatment.
Thereby, since many hydroxyl groups are introduced into the surface of the undercoat layer, the adhesion between the liquid repellent film and the undercoat layer is improved, and an ink jet head excellent in abrasion resistance can be obtained.

In the method for manufacturing an inkjet head of the present invention, it is preferable that the oxidation treatment is performed a plurality of times, and at least one of them is performed in the gas atmosphere containing the moisture.
As a result, since the oxidation treatment is performed a plurality of times, more hydroxyl groups can be introduced into the surface of the underlayer, and an ink jet head excellent in abrasion resistance can be obtained.
In the ink jet head manufacturing method of the present invention, the oxidation treatment is performed a plurality of times, one of which is selectively performed using a mask at a portion corresponding to the outer peripheral portion of the nozzle hole of the plasma polymerization film. Preferably, the thickness of the plasma polymerized film is reduced to form a step that increases the hole diameter in the outer periphery of the nozzle hole.
As a result, a step is formed in the plasma polymerization film, so that the liquid repellent film around the nozzle hole can be protected.

The inkjet head of the present invention is manufactured by the method for manufacturing an inkjet head of the present invention.
Thereby, a highly reliable inkjet head can be obtained.
An electronic apparatus according to the present invention includes the inkjet head according to the present invention.
Thereby, an electronic device with high reliability can be obtained.

<First Embodiment>
Hereinafter, a method for forming a liquid repellent film, a method for manufacturing an ink jet head, an ink jet head, and an electronic apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
First, embodiments of an inkjet head and an electronic device manufactured according to the present invention will be described.

FIG. 1 is an exploded perspective view showing an ink jet head manufactured by the method of manufacturing an ink jet head of the present invention, FIG. 2 is a sectional front view showing the configuration of the main part of the ink jet head shown in FIG. 1, and FIG. FIG. 2 is a schematic view showing an embodiment of an ink jet printer including the ink jet head shown in FIG. 1.
In addition, FIG. 1 is shown upside down from the state normally used. In the following description, the upper side in FIG. 2 is referred to as “upper” and the lower side is referred to as “lower”.

(1) Inkjet Printer An inkjet head 1 shown in FIG. 1 (hereinafter simply referred to as “head 1”) is mounted on an inkjet printer (electronic device of the present invention) 9 as shown in FIG.
The ink jet printer 9 shown in FIG. 3 includes an apparatus main body 92, a tray 921 in which the recording paper P is placed at the upper rear, a paper discharge port 922 for discharging the recording paper P in the lower front, and an operation panel on the upper surface. 97.

The operation panel 97 includes, for example, a liquid crystal display, an organic EL display, an LED lamp, and the like, and a display unit (not shown) for displaying an error message and the like, and an operation unit (not shown) configured with various switches. And.
Further, inside the apparatus main body 92, mainly a printing apparatus (printing means) 94 provided with a reciprocating head unit 93 and a paper feeding apparatus (paper feeding means) for feeding recording paper P to the printing apparatus 94 one by one. 95 and a control unit (control means) 96 for controlling the printing device 94 and the paper feeding device 95.

  Under the control of the control unit 96, the paper feeding device 95 intermittently feeds the recording paper P one by one. The recording paper P passes near the lower part of the head unit 93. At this time, the head unit 93 reciprocates in a direction substantially orthogonal to the feeding direction of the recording paper P, and printing on the recording paper P is performed. That is, the reciprocating motion of the head unit 93 and the intermittent feeding of the recording paper P are the main scanning and sub-scanning in printing, and ink jet printing is performed.

The printing apparatus 94 includes a head unit 93, a carriage motor 941 that is a drive source of the head unit 93, and a reciprocating mechanism 942 that reciprocates the head unit 93 in response to the rotation of the carriage motor 941.
The head unit 93 includes a head 1 having a large number of nozzle holes 111, an ink cartridge 931 that supplies ink to the head 1, and a carriage 932 on which the head 1 and the ink cartridge 931 are mounted.
Ink cartridge 931 is filled with four color inks of yellow, cyan, magenta, and black (black), thereby enabling full color printing.

The reciprocating mechanism 942 includes a carriage guide shaft 943 whose both ends are supported by a frame (not shown), and a timing belt 944 extending in parallel with the carriage guide shaft 943.
The carriage 932 is supported by the carriage guide shaft 943 so as to be able to reciprocate and is fixed to a part of the timing belt 944.
When the timing belt 944 travels forward and backward via a pulley by the operation of the carriage motor 941, the head unit 93 reciprocates as guided by the carriage guide shaft 943. During this reciprocation, ink is appropriately discharged from the head 1 and printing on the recording paper P is performed.

The sheet feeding device 95 includes a sheet feeding motor 951 serving as a driving source thereof, and a sheet feeding roller 952 that is rotated by the operation of the sheet feeding motor 951.
The paper feed roller 952 includes a driven roller 952a and a drive roller 952b that are vertically opposed to each other with a recording paper P feeding path (recording paper P) interposed therebetween. The drive roller 952b is connected to the paper feed motor 951. As a result, the paper feed roller 952 can feed a large number of recording sheets P set on the tray 921 one by one toward the printing apparatus 94. Instead of the tray 921, a configuration in which a paper feed cassette that stores the recording paper P can be detachably mounted may be employed.

The control unit 96 performs printing by controlling the printing device 94, the paper feeding device 95, and the like based on print data input from a host computer such as a personal computer or a digital camera.
Although not shown, the control unit 96 mainly includes a memory that stores a control program for controlling each unit, a piezoelectric element driving circuit that drives the piezoelectric element (vibration source) 14 to control the ink ejection timing, A driving circuit for driving the printing device 94 (carriage motor 941), a driving circuit for driving the paper feeding device 95 (paper feeding motor 951), a communication circuit for obtaining print data from the host computer, and these electrically And a CPU that is connected and performs various controls in each unit.
Further, for example, various sensors that can detect the remaining ink amount of the ink cartridge 931, the position of the head unit 93, and the like are electrically connected to the CPU.
The control unit 96 obtains print data via the communication circuit and stores it in the memory. The CPU processes the print data and outputs a drive signal to each drive circuit based on the process data and input data from various sensors. The piezoelectric element 14, the printing device 94, and the paper feeding device 95 are each activated by this drive signal. As a result, printing is performed on the recording paper P.

(2) Inkjet Head Next, the head 1 will be described in detail with reference to FIGS. 1 and 2.
The head 1 includes a nozzle plate 11, an ink chamber substrate 12, a vibration plate 13, and a piezoelectric element (vibration source) 14 bonded to the vibration plate 13, and these are housed in a base 16. The head 1 constitutes an on-demand piezo jet head.

The nozzle plate 11 is made of, for example, a silicon-based material such as SiO ₂ , SiN, or quartz glass, a metal-based material such as Al, Fe, Ni, Cu, or an alloy containing these, or an oxide-based material such as alumina or iron oxide. The material is composed of carbon-based materials such as carbon black and graphite.
A number of nozzle holes 111 for discharging ink droplets are formed in the nozzle plate 11. The pitch between these nozzle holes 111 is appropriately set according to the printing accuracy.

An ink chamber substrate 12 is fixed (fixed) to the nozzle plate 11.
The ink chamber substrate 12 temporarily stores a plurality of ink chambers (cavities, pressure chambers) 121 and ink supplied from the ink cartridge 931 by the nozzle plate 11, the side wall (partition wall) 122 and the vibration plate 13 described later. The reservoir chamber 123 is formed, and a supply port 124 for supplying ink from the reservoir chamber 123 to each ink chamber 121 is partitioned.

Each ink chamber 121 is formed in a strip shape (a rectangular parallelepiped shape) and is disposed corresponding to each nozzle hole 111. Each ink chamber 121 has a variable volume due to vibration of a diaphragm 13 described later, and is configured to eject ink by this volume change.
As a material (base material 20) for obtaining the ink chamber substrate 12, for example, a silicon single crystal substrate, various glass substrates, various plastic substrates and the like can be used. Since these substrates are general-purpose substrates, the manufacturing cost of the head 1 can be reduced by using these substrates.

The average thickness of the ink chamber substrate 12 is not particularly limited, but is preferably about 10 to 1000 μm, and more preferably about 100 to 500 μm.
The volume of the ink chamber 121 is not particularly limited, but is preferably about 0.1 to 100 nL, more preferably about 0.1 to 10 nL.
On the other hand, a vibration plate 13 is bonded to the ink chamber substrate 12 on the side opposite to the nozzle plate 11, and a plurality of piezoelectric elements 14 are provided on the vibration plate 13 on the side opposite to the ink chamber substrate 12.
A communication hole 131 is formed at a predetermined position of the diaphragm 13 so as to penetrate in the thickness direction of the diaphragm 13. Ink can be supplied from the ink cartridge 931 to the reservoir chamber 123 through the communication hole 131.

Each piezoelectric element 14 has a piezoelectric layer 143 interposed between the lower electrode 142 and the upper electrode 141, and is disposed corresponding to the substantially central portion of each ink chamber 121. Each piezoelectric element 14 is electrically connected to a piezoelectric element drive circuit and is configured to operate (vibrate, deform) based on a signal from the piezoelectric element drive circuit.
Each piezoelectric element 14 functions as a vibration source, and the diaphragm 13 vibrates due to vibration of the piezoelectric element 14 and functions to instantaneously increase the internal pressure of the ink chamber 121.
The substrate 16 is made of, for example, various resin materials, various metal materials, and the like, and the ink chamber substrate 12 is fixed and supported on the substrate 16.

  Such a head 1 is in a state where a predetermined ejection signal is not input via the piezoelectric element driving circuit, that is, in a state where no voltage is applied between the lower electrode 142 and the upper electrode 141 of the piezoelectric element 14. The piezoelectric layer 143 is not deformed. For this reason, the vibration plate 13 is not deformed, and the volume of the ink chamber 121 is not changed. Therefore, no ink droplet is ejected from the nozzle hole 111.

  On the other hand, in a state where a predetermined ejection signal is input via the piezoelectric element driving circuit, that is, in a state where a constant voltage is applied between the lower electrode 142 and the upper electrode 141 of the piezoelectric element 14, the piezoelectric layer 143 is applied. Deformation occurs. As a result, the diaphragm 13 is greatly deflected, and the volume of the ink chamber 121 is changed. At this time, the pressure in the ink chamber 121 increases instantaneously, and ink droplets are ejected from the nozzle holes 111.

  When the ejection of one ink is completed, the piezoelectric element driving circuit stops applying the voltage between the lower electrode 142 and the upper electrode 141. As a result, the piezoelectric element 14 returns almost to its original shape, and the volume of the ink chamber 121 increases. At this time, a pressure (pressure in the positive direction) from the ink cartridge 931 described later to the nozzle hole 111 is applied to the ink. Therefore, air is prevented from entering the ink chamber 121 from the nozzle hole 111, and an amount of ink corresponding to the amount of ink discharged is supplied from the ink cartridge 931 (reservoir chamber 123) to the ink chamber 121.

In this way, any desired (desired) character or figure can be printed by sequentially inputting the ejection signal to the piezoelectric element 14 at the position to be printed in the head 1 via the piezoelectric element driving circuit. it can.
Such a head 1 can be manufactured as follows, for example. Hereinafter, an example of a method for manufacturing the head 1 will be described.

(3) Inkjet Head Manufacturing Method FIGS. 4 and 5 are views (longitudinal sectional views) for explaining the steps of the ink jet head manufacturing method shown in FIGS. 1 and 2, respectively.
In the following description, the upper side in FIGS. 4 and 5 is referred to as “upper” and the lower side is referred to as “lower”.
[1] First, as shown in FIG. 4A, the base material 20 to be the ink chamber substrate 12 and the vibration plate 13 are bonded (bonded) to integrate them.
For this joining, for example, a method of performing a heat treatment in a state where the base material 20 and the diaphragm 13 are pressure-bonded is suitably used. According to this method, the base material 20 and the diaphragm 13 can be integrated easily and reliably.
The heat treatment conditions are not particularly limited, but are preferably about 100 to 600 ° C. × 1 to 24 hours, and more preferably about 300 to 600 ° C. × 6 to 12 hours.
For bonding, various other bonding methods, various fusion methods, and the like may be used.

[2] Next, as shown in FIG. 4B, a plurality of piezoelectric elements 14 are formed on the diaphragm 13.
The piezoelectric element 14 is formed by sequentially laminating a conductive material layer for forming the lower electrode 142, a piezoelectric material layer for forming the piezoelectric layer 143, and a conductive material layer for forming the upper electrode 141. Then, it can be formed by etching so as to have the shape of the piezoelectric element 14.

Each material layer is formed by, for example, chemical vapor deposition (CVD) such as plasma CVD, thermal CVD, or laser CVD, vacuum deposition, sputtering (low temperature sputtering), dry plating methods such as ion plating, electrolytic plating, It can be formed by wet plating methods such as electrolytic plating, thermal spraying methods, sol-gel methods, MOD methods, and the like.
For the etching of the material layer, for example, one or two of a physical etching method such as plasma etching, reactive ion etching, beam etching, and light assisted etching, and a chemical etching method such as wet etching are used. A combination of the above can be used.

[3] Next, the base material 20 having the piezoelectric element 14 shown in FIG. 4B is turned upside down, and the ink chambers are respectively positioned at positions corresponding to the piezoelectric elements 14 of the base material 20 to be the ink chamber substrate 12. A recess 22 to be 121 is formed. In addition, a recess (not shown) that forms the reservoir chamber 123 and the supply port 124 is formed at a predetermined position of the base material 20.
First, as illustrated in FIG. 4C, a resist layer (mask) 21 having openings corresponding to regions where the ink chamber 121, the reservoir chamber 123, and the supply port 124 are formed is formed on the base material 20.

The resist layer 21 can be obtained (patterned) by, for example, a photolithography method.
Specifically, after a resist material is applied (supplied) onto the base material 20, the resist material is transferred to the i-line, the photomask corresponding to the shapes of the ink chamber 121, the reservoir chamber 123, and the supply port 124, i-line, It can be obtained by exposure and development with ultraviolet rays and electron beams.

Here, examples of the resist material include screw type and positive type resist materials.
Examples of the method for applying the resist material include an inkjet method, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method, and a spray. Various coating methods such as a coating method, a screen printing method, a flexographic printing method, an offset printing method, and a microcontact printing method can be used, and one or more of these can be used in combination.

In the present embodiment, the case where the resist layer 21 is composed of a resist material as the main material has been described. However, the present invention is not limited to such a case. For example, the resist layer 21 is a metal layer as a lower layer of the resist layer 21. The laminated body provided with a layer may be sufficient.
Accordingly, when the ink chamber 121, the reservoir chamber 123, and the supply port 124 are formed by the dry etching method using the resist layer 21 as a mask, the resist layer is etched as the base material 20 is etched (processed). In addition, the ink chamber 121, the reservoir chamber 123, and the supply port 124 with higher dimensional accuracy can be formed by more suitably preventing or suppressing the etching.
Examples of such a metal layer include a layer mainly composed of at least one of Al, Cu, Fe, Ni, and Cr.

The metal layer is formed by forming an oxide film on the base material 20, forming a metal film on almost the entire surface of the oxide film, and further forming the resist layer 21 on the metal film by the method described above, It can be obtained by etching this metal film into the same shape as the resist layer 21 by wet etching using the resist layer 21 as a mask.
Examples of the etchant used in the wet etching method include an aqueous solution of an alkali metal hydroxide such as NaOH and KOH, an aqueous solution of an alkaline earth metal hydroxide such as Mg (OH) ₂ , and tetramethylammonium hydro Examples include aqueous solutions of oxides, amide-based organic solvents such as N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA), and the like. These can be used alone or in combination.

Next, from the upper side of the base material 20, that is, the surface side where the piezoelectric element 14 is not formed, the recess 22 constituting the ink chamber 121, the reservoir chamber 123, and the supply port 124 is formed using an etching method.
For the etching, either a dry etching method or a wet etching method may be used, but a dry etching method is preferable. Thereby, since it can etch with plasma, without using a chemical substance, the base material 20 can be etched easily and reliably.

  The dry etching method includes a chamber, a first introduction valve for introducing a plasma generating gas into the chamber, a second introduction valve for introducing a cooling medium gas for cooling the base material 20, A pair of electrodes provided so as to face each other, a cooling plate for cooling the base material 20 provided on one electrode side through a communication hole through which a cooling medium gas can pass, and an installation for fixing the base material 20 It can be performed using a dry etching apparatus provided with a table.

That is, in the dry etching method, the base material 20 is set on an installation base provided on the electrode side so that one electrode and the piezoelectric element 14 face each other, and the inside of the chamber is decompressed. Then, the cooling medium gas introduced from the second introduction valve is sprayed to the lower side of the base material 20 to transmit the cooling plate and the temperature of the cooling medium gas to cool, and the plasma generated from the first introduction valve is generated. A high frequency voltage is applied between the electrodes in a state where the working gas is supplied between the pair of electrodes. As a result, plasma is generated between the electrodes, and ions and electrons generated thereby collide with the upper surface of the base material 20 including the resist layer 21, thereby forming the ink chamber 121, the reservoir chamber 123, and the supply port 124. A recess 22 is formed.
Such dry etching is preferably vertical anisotropic dry etching. As a result, plasma ions, which are active gases in the plasma, enter perpendicularly, so that anisotropic etching is performed efficiently.

Examples of the plasma generating gas include a fluorine-based gas, a halogen-based gas containing at least one of chlorine and bromine, and the like. As in the present embodiment, the base material 20 is composed of a silicon single crystal. SF ₆ , C ₄ F ₈ , CBrF ₃ , CF ₄ / O ₂ , Cl ₂ , SF ₆ / N ₂ / Ar, and BCl ₂ / Cl ₂ / Ar gas are preferably used. _It is preferable to use any one of ₆ and C ₄ F ₈ gas alone or a mixed gas thereof. Thereby, the base material 20 can be etched efficiently.

The cooling medium gas is not particularly limited as long as it has excellent cooling efficiency and does not affect the generation of plasma. For example, an inert gas such as helium, argon, nitrogen, etc. Among these, it is preferable to use helium as a main component. Helium is preferably used as a cooling medium gas because it has a particularly excellent cooling effect.
The temperature of the cooling plate, that is, the temperature of the cooling medium gas is preferably about -20 to 60 ° C, more preferably about -10 to 10 ° C. Thereby, the base material 20 can be cooled and an appropriate temperature can be maintained.
By etching the base material 20 using the resist layer 21 as a mask as described above, as shown in FIG. 4D, the recess 22 is formed adjacent to the side wall 122 such as the ink chamber 121, the reservoir chamber 123, and the supply port 124. It is formed.

[4] Next, as shown in FIG. 5E, the resist layer 21 formed on the base material 20 corresponding to the side wall 122 is removed.
As the removal method, for example, the resist is exposed to oxygen plasma or ozone vapor under atmospheric pressure or reduced pressure, or immersed in a resist stripping solution such as acetone or alkylbenzene sulfonic acid which can dissolve these. All or part of the layer 21 can be liquefied.

[5] Next, as shown in FIG. 5 (f), the nozzle plate 11 in which the plurality of nozzle holes 111 are formed and subjected to the liquid repellent treatment corresponds to the recesses 22 in which each nozzle hole 111 becomes each ink chamber 121. Align and join.
Thereby, a plurality of ink chambers 121, a reservoir chamber 123, and a plurality of supply ports 124 are defined. For this joining, for example, various adhesion methods such as adhesion with an adhesive, various fusion methods, and the like can be used.
In addition, it is preferable that the internal diameter of the nozzle hole 111 is 5-50 micrometers. In the present embodiment, a 20 μm nozzle hole 111 is used.
[6] Finally, as shown in FIG. 1, the ink chamber substrate 12 is attached (fixed) to the base 16 by, for example, bonding with an adhesive.
The head 1 is manufactured through the steps as described above.

Now, the nozzle plate 11 of the head 1 manufactured by the above processes can be manufactured by the following processes, for example. Hereinafter, an example of the manufacturing method of the nozzle plate 11 will be described.
The method for manufacturing the nozzle plate 11 can also be regarded as a method for forming the liquid repellent film 19.

(4) Method for Producing Nozzle Plate FIG. 6 is a diagram (cross-sectional front view) for explaining an example of the process of the method for producing the nozzle plate of the ink jet head shown in FIGS. 1 and 2.
In the following description, the upper side in FIG. 6 is referred to as “upper” and the lower side is referred to as “lower”.
The manufacturing method of the nozzle plate 11 used in the head 1 of the present invention includes a first step [1] of forming a plasma polymerization film (underlayer) 17 on the surface 112 on the droplet discharge side of the nozzle plate 11, and a desired process. In a gas atmosphere containing moisture, the surface of the plasma polymerization film 17 is subjected to an oxidation treatment to introduce a hydroxyl group and / or adsorbed water [2], and the plasma polymerization film 17 subjected to the oxidation treatment is repelled. And a third step [3] of forming the liquid film 19.

Hereinafter, each process of the manufacturing method of the nozzle plate 11 is demonstrated.
[1] First Step As shown in FIG. 6A, the plasma polymerization film 17 is formed on the surface 112 on the droplet discharge side of the nozzle plate 11.
Examples of the constituent material of the plasma polymerization film 17 include silicone materials such as organopolysiloxane and silane compounds such as alkoxysilane.
Of these, silicone materials are preferred, and organopolysiloxanes are particularly preferred. By using organopolysiloxane for the plasma polymerized film 17, it has a structure with a siloxane bond (Si—O) as a skeleton, so that it can be easily bonded to the constituent material (silicon-based material) of the nozzle plate 11 and easily plasma polymerized. A film 17 can be formed.

Examples of the organopolysiloxane include alkylpolysiloxanes such as dimethylpolysiloxane, diethylpolysiloxane, and cycloalkylpolysiloxane, and arylpolysiloxanes such as phenylpolysiloxane.
Examples of the alkoxysilane include methoxysilane, ethoxysilane, butoxysilane, and the like.
These compounds can be used alone or in combination of two or more.

Of these compounds, alkylpolysiloxane is preferably used. Since alkylpolysiloxane is a polymer compound, a polymer film can be formed on the nozzle plate 11. In addition, since the polymer has an alkyl group, the polymer structure has little steric hindrance, and a film in which molecules are regularly arranged can be formed.
Of the alkylpolysiloxanes, dimethylpolysiloxane is particularly preferable. Since dimethylpolysiloxane is easy to produce, it can be easily obtained. Moreover, since the reactivity is high, the methyl group can be easily cleaved when the plasma polymerization film 17 is subjected to an oxidation treatment as will be described later.

Examples of the method for forming the plasma polymerized film 17 using such a constituent material include a plasma polymerization method, a vapor deposition method, a treatment with a silane coupling agent, a treatment with a liquid material containing polyorganosiloxane, and the like. One or two or more of them can be used in combination. Among these, it is preferable to use a plasma polymerization method.
In the plasma polymerization method, for example, a nozzle plate 11 is installed in a chamber, an electric field is generated in the chamber, organosiloxane is supplied in a gaseous state together with a carrier gas, and the generated plasma is supplied to the droplet discharge side by plasma polymerization. This is a method of forming a film on the surface 112 (plasma polymerization film 17).
By using such a plasma polymerization method, plasma of organopolysiloxane is generated, so that a plasma polymerization film 17 having a uniform and uniform film thickness can be formed.
In addition, as said carrier gas (addition gas), argon, helium, nitrogen, etc. can be used, for example.

Moreover, when forming the plasma polymerization film | membrane 17 by a plasma polymerization method, the formation conditions (film-forming conditions) can be as follows, for example.
The high frequency output is preferably about 100 to 1000 W.
The pressure in the chamber during film formation is preferably about 1 × 10 ^{−4 to} 1 Torr.
The raw material gas flow rate is preferably about 1 to 100 sccm. On the other hand, the carrier gas flow rate is preferably about 10 to 500 sccm.
The treatment time is preferably about 1 to 10 minutes, more preferably about 4 to 7 minutes.

By appropriately setting such conditions, the plasma polymerization film 17 having a desired average thickness can be formed.
The average film thickness _{T 1} of the plasma polymerization film 17 is preferably in the range of about 10 to 1000 nm, more preferably about 50 to 500 nm. With such a thickness, an optimal amount of alkyl groups terminates on the surface of the plasma polymerized film 17, so that the liquid repellent film 19 having liquid repellency is formed by an oxidation treatment described later and reaction with the metal alkoxide 191. Can be formed.

[2] Second Step As shown in FIG. 6B, the plasma polymerization film 17 is subjected to an oxidation treatment in an atmosphere containing moisture (hereinafter referred to as “processing gas”).
The processing gas contains a predetermined amount of water vapor in the main component gas described below.
As the main component gas of the processing gas, for example, inert gas such as hydrogen, helium, argon, air, oxygen gas, or CF ₄ , C ₂ F ₆ , C ₃ F ₆ , C ₄ F ₈ , CClF ₃ , SF Various halogen-based gases such as a fluorine atom-containing compound gas such as _{6 and} a chlorine atom-containing compound gas such as Cl ₂ , BCl ₃ , and CCl ₄ are included. These main component gases may be used in combination of two or more.

When ultraviolet irradiation is used for the oxidation treatment described later, the main component gas is preferably an inert gas such as hydrogen, helium, or argon, air, oxygen gas, or the like. If an inert gas is used, the plasma polymerization film 17 is oxidized in an inert gas atmosphere, so that it is possible to prevent impurities from being bonded to the plasma polymerization film 17 in an active state due to the oxidation process.
In addition, if air or oxygen gas is used, ozone is generated by ultraviolet irradiation, so that the oxidation treatment can be promoted using the ozone.
When plasma irradiation is used for the oxidation treatment described later, the main component gas is preferably various halogen-based gases such as a fluorine atom-containing compound gas and a chlorine atom-containing compound gas. By using such a gas, the plasma polymerization film 17 can be reliably etched, so that the alkyl group can be reliably cut from the Si atoms.

The amount of water (water vapor) contained in the processing gas, in other words, the dew point of the processing gas with the water content as the saturated water content is preferably −40 to 20 ° C.
If the dew point of the processing gas is within such a range, since the desired amount of water that can exist as a gas is contained in the processing gas at each temperature, the plasma polymerization film 17 is oxidized and adsorbed by the oxidation treatment. A lot of water can be introduced. Therefore, when the liquid repellent film 19 is bonded to the hydroxyl group, the bonding force between the liquid repellent film 19 and the base layer 17 is increased, so that the rub resistance of the liquid repellent film 19 is improved.

  Further, the dew point of the processing gas is more preferably −40 to −20 ° C. If the dew point of the processing gas is in such a range, the processing gas contains a sufficient amount of desired water that can exist as a gas, so that the plasma polymerization film 17 can be reliably reacted with the metal alkoxide 191 by the oxidation treatment. Possible hydroxyl groups and / or adsorbed water can be introduced. Therefore, when the liquid repellent film 19 is bonded to the hydroxyl group, the adhesion between the liquid repellent film 19 and the base layer 17 is increased, so that the rub resistance of the liquid repellent film 19 is improved. In addition, since the number of unreacted hydroxyl groups present on the surface of the plasma polymerized film 17 is small, the alkali resistance of the liquid repellent film 19 is also improved. In this way, the liquid repellent film 19 having a balance between the abrasion resistance and the alkali resistance can be obtained.

Examples of the process gas preparation method as described above include a method of bubbling the main component gas into water and a method of contacting the dry main component gas with water vapor. And the moisture content is managed by a dew point meter.
For example, when preparing a treatment gas having a dew point of 10 ° C. (in the case of air, including a saturated water content of 9.4 g / m ³ ), if the dew point of the treatment gas obtained by the above preparation method is 0 ° C., Since the gas is deficient in moisture, bubbling to water or contact with water vapor is performed again, and moisture is contained in the gas to obtain a processing gas (air) having a dew point of 10 ° C.

On the other hand, if the dew point of the processing gas obtained by the above preparation method is 20 ° C., the water is excessively contained in the processing gas, so that the dew point is adjusted by bringing the gas into contact with dry air and adjusting the amount of water. A process gas (air) of 10 ° C. is obtained.
The main component gas used for the preparation of the processing gas is preferably a dry gas. If the dry gas is used, the water content can be easily managed.

Next, an oxidation process performed on the plasma polymerization film 17 will be described. In the following description, for example, a case where alkylpolysiloxane is used for the plasma polymerization film 17 will be described as a representative.
In the present invention, as will be described later, the metal alkoxide 191 is reacted with the plasma polymerization film 17 to form the liquid repellent film 19 on the surface (surface) opposite to the nozzle plate 11 of the plasma polymerization film 17. However, the surface of the plasma polymerized film 17 is terminated with an alkyl group. Therefore, it is difficult to react the plasma polymerization film 17 and the metal alkoxide 191 to form the liquid repellent film 19. Therefore, in order to facilitate the reaction between the plasma polymerized film 17 and the metal alkoxide 191, an oxidation process is performed on a portion of the plasma polymerized film 17 where the liquid repellent treatment is desired. By this oxidation treatment, the alkyl group terminated at the surface of the plasma polymerized film 17 is cut from the Si atoms, and oxygen atoms are introduced into the Si atoms (SiO ₂ conversion treatment).

At this time, since the oxidation treatment is performed in the atmosphere of the processing gas, the hydroxyl group is introduced into the plasma polymerized film 17 due to the influence of moisture contained in the processing gas. The following two mechanisms are presumed for introducing the hydroxyl group into the plasma polymerization film 17.
That is, by performing an oxidation treatment in a treatment gas atmosphere, the water molecule bond is cut by the oxidation treatment, and a hydroxyl group is liberated. And it is estimated that the said hydroxyl group couple | bonds with Si atom from which the alkyl group was cut | disconnected by the oxidation process.

In addition, moisture contained in the processing gas is radicalized by oxidation treatment, and hydroxide radicals are generated. And it is estimated that the said hydroxyl radical couple | bonds with the Si atom from which the alkyl group was cut | disconnected by the oxidation process.
In addition, the surface of the plasma polymerization film 17 may include adsorbed water in which moisture in the process gas is adsorbed.

Such oxidation treatment is performed by, for example, a method of irradiating energy rays. Thereby, since the oxidation treatment can be performed only on the region irradiated with the energy rays, the SiO ₂ conversion can be performed efficiently.
Examples of the energy ray include ultraviolet rays and plasma. Of these, ultraviolet rays are preferred. By using ultraviolet rays, since a large apparatus is not required, a desired oxidation treatment can be easily performed. In addition, unlike plasma irradiation, oxidation treatment can be performed only by irradiating with ultraviolet rays, so that oxidation treatment can be performed with high purity without generation of reaction products due to plasma.

When such oxidation treatment is performed by, for example, ultraviolet irradiation or plasma irradiation, the processing conditions can be set as follows.
A: When ultraviolet irradiation is used as the oxidation treatment The wavelength of the ultraviolet rays is not particularly limited, but may be 400 nm or less, and is preferably about 100 to 350 nm.
UV intensity is preferably in the range of about 1000~3000mJ / cm ^2, more preferably about 1400~2600mJ / cm ^2.

The atmosphere of ultraviolet irradiation may be in the air or in a reduced pressure state, but is preferably in the air. As a result, oxygen atoms are efficiently introduced from oxygen molecules present in the atmosphere almost simultaneously with the cleavage of the alkyl group and Si, so that the polyorganosiloxane can be changed to SiO ₂ more quickly. .
Moreover, it is preferable that the irradiation time of an ultraviolet-ray is about 1 to 10 minutes, and it is more preferable that it is about 3 to 7 minutes.
Moreover, although ultraviolet irradiation may be performed on either sealing conditions or open conditions, it is preferable to set it as sealing conditions. Thereby, since the plasma polymerization film 17 is oxidized in a high moisture concentration state, more hydroxyl groups can be introduced into the plasma polymerization film 17.

B: When plasma irradiation is used as the oxidation treatment Examples of the gas species for generating plasma include oxygen gas, nitrogen gas, inert gas (argon gas, helium gas, etc.), and one of these or Two or more kinds can be used in combination.
The high-frequency output is preferably about 100 to 700 W, and more preferably about 300 to 500 W.
The gas flow rate is preferably about 10 to 500 sccm, and more preferably about 100 to 300 sccm.

Note that the atmosphere in which plasma irradiation is performed may be in the air or in a reduced pressure state, but is preferably in the air. As a result, oxygen atoms are efficiently introduced from oxygen molecules existing in the atmosphere almost simultaneously with the bond between the alkyl group and Si being broken, so that polyorganosiloxane can be changed to SiO ₂ more quickly. Can do.
In particular, for plasma irradiation, it is preferable to use oxygen plasma irradiation using a gas containing oxygen gas as a gas species for generating plasma. According to the oxygen plasma irradiation, since the oxygen plasma breaks the bond between the alkyl group and Si and is used for the bond between Si and the oxygen atom, the polyorganosiloxane can be more reliably changed to SiO _2. .
In addition, when plasma irradiation is used, it may be performed under any of sealed conditions (for example, in a chamber) or open conditions, but is preferably sealed conditions. Thereby, since the plasma polymerization film 17 is oxidized in a higher plasma density state, more hydroxyl groups can be introduced into the plasma polymerization film 17.

In the oxidation treatment as described above, when the oxidation treatment is performed in a sealed condition, for example, as shown in FIG. 6B, the nozzle plate 11 in which the plasma polymerized film 17 is formed is accommodated in the oxidation treatment chamber 4. Is called.
The oxidation processing chamber (ultraviolet processing chamber) 4 includes a processing chamber main body 41, a lid 42 that covers the upper portion of the processing chamber main body 41, a gas supply means 43 that supplies a moisture-containing gas into the processing chamber main body 41, and a processing chamber main body. 41 is provided with gas discharge means 44 for discharging the gas in the gas generator 41.

Hereinafter, the structure of each part of the oxidation treatment chamber 4 will be described.
As shown in FIG. 6B, the processing chamber main body 41 accommodates the nozzle plate 11 on which the plasma polymerized film 17 is formed, and an oxidation treatment space 411 is formed that irradiates energy rays, in this embodiment, ultraviolet rays. ing. A nozzle plate 11 is installed at the bottom of the oxidation treatment space 411.
A processing gas supply port 412 for supplying a processing gas is formed on the side wall of the processing chamber body 41. A processing gas discharge port 413 for discharging the processing gas is formed on the side wall opposite to the side wall.
The shape of the processing chamber body 41 is not particularly limited, for example, a square shape, a cylindrical shape, or the like.

The lid 42 is provided with an ultraviolet ray light source 421 for irradiating energy rays, in this embodiment, ultraviolet rays. When the ultraviolet light source 421 is turned on, the ultraviolet light source 421 irradiates the upper surface of the plasma polymerization film 17 with ultraviolet light. Note that the shape of the lid 42 is not particularly limited as is the case with the processing chamber body 41.
The gas supply means 43 supplies the processing gas into the processing chamber main body 41 from the processing gas supply port 412. The gas supply means 43 is a gas bomb (gas supply source) 431 filled with a process gas adjusted to a predetermined water vapor amount (dew point) and supplied, and a mass flow controller for adjusting the flow rate of the process gas supplied from the gas cylinder 431. And a processing gas supply port 412, a valve (flow channel opening / closing means) 433 for opening and closing a flow path in the processing gas supply pipe 434 on the downstream end side from the mass flow controller 432. And a processing gas supply pipe 434.

Such a gas supply means 43 sends out a predetermined processing gas from the gas cylinder 431 and adjusts the flow rate by the mass flow controller 432. The gas supply means 43 introduces (supplies) the processing gas flowing through the processing gas supply pipe 434 to the processing chamber main body 41 from the processing gas supply port 412.
Further, the gas cylinder 431 is filled with the dried main component gas, and the main component gas is flowed in the same manner as described above. Then, before the processing gas supply port 412, the main component gas and water vapor may be mixed to prepare a processing gas having a desired dew point and introduced into the processing chamber main body 41 from the processing gas supply port 412.

Further, a water vapor supply port is separately provided in the vicinity of the processing gas supply port 412, and the water vapor and the main component gas are separately introduced into the processing chamber main body 41. Then, the water vapor and the main component gas may be mixed in the processing chamber body 41 to obtain a processing gas having a desired dew point.
Note that the flow rate of the processing gas is appropriately determined according to the type of the main component gas of the processing gas, the amount of water contained, and the like. Usually, it is preferably about 30 SCCM to 50 SLM.

The gas discharge means 44 discharges the reaction product and the processing gas existing in the oxidation processing space 411 from the processing gas discharge port 413 to the outside of the processing chamber main body 41 and collects them.
The gas discharge means 44 includes a process gas discharge pipe 441 connected to the process gas discharge port 413, a valve (flow path opening / closing means) 442 for opening and closing a flow path in the process gas discharge pipe 441, a pump 443, And a processing gas recovery tank 444 provided on the downstream end side of 443.

  Such a gas discharge means 44 operates the pump 443 to temporarily reduce the oxidation treatment space 411 to a reduced pressure state. The gas discharge means 44 discharges the processing gas or the like to the processing gas discharge pipe 441 through the processing gas discharge port 413 and collects it in the processing gas recovery tank 444. The recovered processing gas can be used again as a processing gas by performing a predetermined processing.

By exposing the plasma polymerized film 17 converted to SiO ₂ to the atmosphere as described above, hydrogen atoms in the atmosphere (in the air) are bonded to oxygen atoms introduced into the Si atoms. Then, as shown in FIG. 6C, the surface of the plasma polymerization film 17 is terminated with a hydroxyl group.
In addition, the hydroxyl group generated from the moisture contained in the processing gas by the oxidation treatment is bonded to the Si atom from which the alkyl group has been cleaved. Then, as shown in FIG. 6C, the surface of the plasma polymerization film 17 is terminated with a hydroxyl group. Further, partially adsorbed water is also introduced into the plasma polymerization film 17.
As described above, the surface of the plasma polymerized film 17 is terminated with many hydroxyl groups by two introduction methods of introducing hydroxyl groups by oxidation treatment and introducing hydroxyl groups by moisture in the processing gas. Therefore, the metal alkoxide 191 described later can be sufficiently bonded to the hydroxyl group.

[3] Third Step In order to prevent ink from adhering to the surface of the nozzle plate 11, as shown in FIG. 6D, a metal alkoxide 191 reacts with the surface of the plasma polymerized film 17 subjected to oxidation treatment. Thus, the liquid repellent film 19 is formed.
The plasma polymerized film 17 and the metal alkoxide 191 react by the following mechanism. That is, as described above, the surface of the plasma polymerized film 17 is converted to SiO ₂ by oxidation treatment and terminated with a hydroxyl group. When the metal alkoxide 191 is brought into contact with the surface (hydroxyl group) of the plasma polymerized film, the hydroxyl group reacts with the alkoxyl group of the metal alkoxide 191, and the silanol group (Si—O—) of the metal alkoxide 191 and the surface of the plasma polymerized film 17. Bond (siloxane bond). Thereby, a liquid repellent film 19 composed of the metal alkoxide 191 is formed.

Here, the metal alkoxide 191 used for forming the liquid repellent film has the following general formula (1).
X _n M (OR) _4-n ...... Formula (1)
(However, X is a functional group exhibiting liquid repellency, M is a metal, R is an alkyl group, and n is an integer of 1 to 3.)
It is a compound represented by these.

X in the general formula (1) includes, for example, a functional group exhibiting liquid repellency such as a fluoroalkyl group, an alkyl group, and a vinyl group. Of these, a fluoroalkyl group is preferred. Thereby, the surface free energy is reduced, so that the liquid repellency of the liquid repellent film 19 can be improved, and characteristics such as chemical resistance, weather resistance, and friction resistance can be improved.
In addition, it is preferable that the weight average molecular weight of X is about 200-4000, and it is more preferable that it is about 1000-2000.

M in the general formula (1) is, for example, a metal such as Ti, Li, Si, Na, K, Mg, Ca, St, Ba, Al, In, Ge, Bi, Fe, Cu, Y, Zr, and Ta. Is mentioned. Among these, Si, Ti, Al, Zr, etc. are more preferable.
R in the general formula (1) includes an alkyl group having 1 to 20 carbon atoms, and examples thereof include a methyl group, a propyl group, and a pentyl group.

In such a metal alkoxide 191 represented by the general formula (1), it is particularly preferable that X is a fluoroalkyl group and M is Si (silane coupling agent). By being such a compound, since X is a fluoroalkyl group, it is excellent in liquid repellency as described above, and since M is Si, it can be obtained at low cost.
The alkyl group of the fluoroalkyl group may be the same as R described above, but is preferably a group having a long carbon number. Thereby, since fat solubility becomes higher, liquid repellency can be maintained and improved.

Specific examples of the metal alkoxide 191 represented by the general formula (1) include, for example, tridecafluoro-1,1,2,2 tetrahydrooctyltriethoxysilane, tridecafluoro-1,1,2, 2 tetrahydrooctyltrimethoxysilane, tridecafluoro-1,1,2,2 tetrahydrooctyltrichlorosilane, trifluoropropyltrimethoxysilane and the like.
In addition, in the metal alkoxide 191 represented by the general formula (1), when n is 1 or 2, a siloxane bond can be formed even between adjacent silanol groups in the compound. Therefore, the adhesion of the formed liquid repellent film 19 can be improved.

  Such a method of forming the liquid repellent film 19 by reacting the metal alkoxide 191 with the surface of the plasma polymerized film 17 can be performed using various processes such as a liquid phase process and a gas phase process. Among these, it is preferable to use a liquid phase process. If the liquid phase process is used, the liquid repellent film 19 can be formed by a relatively simple process of preparing the metal alkoxide 191 solution and supplying the metal alkoxide 191 solution to the surface of the plasma polymerization film 17. .

  Specific examples of the liquid phase process include, for example, an inkjet method, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method, and a spray coating method. Various coating methods such as a screen printing method, a flexographic printing method, an offset printing method, and a micro contact printing method can be used, and one or more of these can be used in combination.

When the liquid repellent film 19 is formed using a liquid phase process (coating method), for example, the liquid repellent film 19 can be formed as follows.
First, a metal alkoxide 191 solution is prepared.
Various solvents can be used as the solvent for dissolving the metal alkoxide 191. For example, aromatic hydrocarbon solvents such as toluene, xylene, trimethylbenzene, tetramethylbenzene, and cyclohexylbenzene can be used.
Further, the concentration of the metal alkoxide 191 is preferably about 0.01 to 0.5 wt%, and more preferably about 0.1 to 0.3 wt%.

Next, the metal alkoxide 191 solution is supplied to the surface of the plasma polymerization film 17 by the coating method described above.
In this case, heating may be performed to increase the reactivity between the surface of the plasma polymerized film 17 and the metal alkoxide 191. In the case of heating, the temperature is preferably about 50 to 200 ° C, more preferably about 80 to 150 ° C.
The heating time is preferably about 1 to 50 minutes, more preferably about 5 to 20 minutes.
By the above method, as shown in FIG. 6D, the metal alkoxide 191 is bonded to almost the entire upper surface of the plasma polymerized film 17, and the metal alkoxide 191 is disposed on the droplet discharge side of the nozzle plate 11. An exposed liquid repellent film 19 is formed.

<Second Embodiment>
FIG. 7 is a cross-sectional front view showing a second embodiment of the main part of the inkjet head of the present invention, and FIGS. 8 and 9 are examples of the steps of the method for manufacturing the nozzle plate of the ink jet head shown in FIGS. 1 and 2, respectively. FIG. 10 is a plan view of the nozzle plate.
In the following description, the upper side in FIGS. 7 to 9 is referred to as “upper” and the lower side is referred to as “lower”.

Hereinafter, the manufacturing method (liquid repellent film forming method) of the ink jet head according to the second embodiment will be described with a focus on differences from the first embodiment described above, and description of similar matters will be omitted.
The manufacturing method of the nozzle plate 11 used in the inkjet head 1 of the present embodiment includes the first step [1] of forming the plasma polymerization film 17 (underlayer) on the surface 112 on the droplet discharge side of the nozzle plate 11; Corresponding to the second step [2] in which the surface of the plasma polymerized film 17 is subjected to an oxidation treatment and introduces hydroxyl groups and / or adsorbed water under a processing gas atmosphere, and the outer periphery of the nozzle hole 111 of the plasma polymerized film 17 A third step [3] of forming the step 23 in the outer peripheral portion 171 and a fourth step [4] of forming the liquid repellent film 19 so as to cover at least a portion of the plasma polymerization film 17 having the step 23. Have.

Hereinafter, each process of the manufacturing method of the nozzle plate 11 is demonstrated.
[1] First Step As shown in FIG. 8A, the plasma polymerization film 17 is formed on the surface 112 on the droplet discharge side of the nozzle plate 11.
The constituent material of the plasma polymerized film 17, the forming method of the plasma polymerized film 17, the average film thickness of the plasma polymerized film 17, and the like are the same as those in the first embodiment.

[2] Second Step Next, as shown in FIG. 8A, the plasma polymerization film 17 is subjected to an oxidation treatment in a processing gas atmosphere.
The main component gas of the processing gas, the dew point of the processing gas, the preparation method of the processing gas, the principle of the oxidation treatment, the method of the oxidation treatment, and the like are the same as in the first embodiment.

The plasma polymerized film 17 is oxidized on the principle as described above. However, when the present inventors analyzed the film thickness of the plasma polymerized film 17 after the oxidation process, the film thickness surprisingly decreases. And found a new property (FIG. 8B). This phenomenon is presumed to be due to the following reason. That is, by applying the above-described oxidation treatment to the plasma polymerized film 17, the alkyl group terminating on the surface of the plasma polymerized film 17 is cut from the Si atoms. By cutting the alkyl group, the alkyl group extending from the surface of the plasma polymerization film 17 disappears. Therefore, it is estimated that the thickness of the plasma polymerization film 17 is reduced by the amount of the lost alkyl group.
The degree of decrease in the thickness of the plasma polymerized film 17 due to such oxidation treatment can be adjusted by the strength of the oxidation treatment, that is, the intensity of energy rays, the irradiation time, and the like.

When after the film thickness of the plasma polymerization film 17 is reduced to an average film thickness of the plasma polymerization film 17 (after oxidation treatment) was T _2, the average thickness T ₂ are the average of oxidative pretreatment of the plasma polymerization film 17 respect to the film thickness _{T 1,} is preferably T ₂ / T 1 = 0.2~0.9, more preferably 0.35 to 0.75. By being in such a range, the film thickness of the plasma polymerized film 17 is sufficiently reduced (without excess or deficiency), so that the surface of the plasma polymerized film 17 is sufficiently converted to SiO ₂ , and the liquid repellent film 19 Can be reliably formed.

[3] Third Step As described above, when the plasma polymerized film 17 is oxidized, the thickness of the plasma polymerized film 17 in the part subjected to the oxidation process decreases. Therefore, if this property is used, the liquid repellent treatment of the nozzle plate 11 and the formation of the step 23 of the outer peripheral portion 171 corresponding to the outer peripheral portion of the nozzle hole 111 of the plasma polymerization film 17 can be efficiently performed at once. Can do.

Hereinafter, a method of forming the step 23 will be described in detail using the property that the film thickness of the plasma polymerization film 17 is reduced.
[3-1] Mask Forming Process As shown in FIGS. 8C and 10A, the mask 18 is formed on the plasma polymerized film 17 that has been oxidized in the second process and whose film thickness has decreased. Form.
An opening (window) 181 having a predetermined shape is formed in the mask 18 so as to include an outer peripheral portion 171 corresponding to the outer peripheral portion of the nozzle hole 111 of the plasma polymerization film 17. The mask 18 is resistant to the oxidation treatment performed in the next step, that is, has a function of blocking energy rays irradiated in the next step.
If it has such a function, the material of the mask 18 will not be specifically limited, For example, materials, such as metals, such as aluminum, glass (glass which has a function which interrupts | blocks an ultraviolet-ray), various ceramics, silicon, etc. are mentioned. Can do.

When glass is used for the mask 18, a film may be attached to a portion other than the irradiated portion so as to block the energy rays.
A method for forming the mask 18 is not particularly limited, and for example, the mask 18 can be formed by mounting a plate-shaped mask 18 having an opening 181 on the plasma polymerization film 17. Specifically, the outer peripheral portion 171 and the opening 181 of the mask 18 can be positioned and bonded onto the plasma polymerization film 17 so that the outer peripheral portion 171 forms an opening. Further, as another method for forming the mask 18, for example, a vapor deposition method or a photolithography method can be used.
The shape of the opening 181 of the mask 18 is not particularly limited as long as it includes the outer peripheral portion 171 corresponding to the outer peripheral portion of each nozzle hole 111 of the plasma polymerization film 17, but in the present embodiment, it is formed in a band shape. ing. The shape of the opening 181 may be a circular shape larger than the inner diameter of the nozzle hole 111 with respect to one nozzle hole 111.
As described above, the outer peripheral portion 171 and the opening 181 are positioned, and the mask 18 is disposed on the plasma polymerization film 17, whereby the outer peripheral portion 171 opening from the opening 181 is selectively oxidized. Can do.

[3-2] Oxidation Process for Forming Steps Next, as shown in FIG. 8C, the plasma polymerized film 17 is oxidized using a mask 18.
At this time, due to the function of the mask 18 described above, only the portion immediately below the opening 181 of the mask 18 of the plasma polymerization film 17, that is, only the outer peripheral portion 171 is selectively oxidized. As a result, the alkyl group terminating at the surface of the portion 171 is cleaved from the Si atom and converted to SiO ₂ . Then, as shown in FIG. 8D, the film thickness of the plasma polymerization film 17 in the opening 181, that is, the plasma polymerization film 17 in the outer peripheral portion 171 decreases. As a result, a step 23 is formed between the portion of the plasma polymerization film 17 covered with the mask 18 and the outer peripheral portion 171.
When the plasma polymerization film 17 is exposed to the atmosphere (air), hydrogen atoms are introduced into oxygen atoms, and the surface of the outer peripheral portion 171 is terminated with a hydroxyl group.

The principle, type and method of the oxidation treatment are the same as those described in the above [1] first step.
Further, when the thickness of the plasma polymerization film 17 at the outer peripheral portion 171 has a T ₃ the average film thickness of the plasma polymerization film 17 after reduction (after the oxidation treatment of the step formation), the average thickness T _3, the film It is preferable that T ₃ / T ₂ = 0.2 to 0.9, and 0.35 to 0.75 with respect to the average film thickness T ₂ of the plasma polymerization film 17 after the thickness is reduced. More preferred. Due to such a range, a difference in film thickness, that is, a step 23 occurs between the outer peripheral portion 171 and other portions of the plasma polymerized film 17, so that even when a paper jam occurs in the printing apparatus 94, the surface of the outer peripheral portion 171 is appropriately Can be protected.

  The gap length c of the step 23 formed by the oxidation treatment for forming such a step is preferably 0.01 to 0.5 times the inner diameter a of the nozzle hole 111, and 0.05 to 0 .35 times is more preferable. By setting it as such a range, the gap length of the step of the plasma polymerization film becomes an optimum length, and even when a paper jam occurs in the printing apparatus 94, the surface of the outer peripheral portion 171 can be appropriately protected.

If the gap length c is too smaller than the lower limit value of the range, the step 23 becomes small. Therefore, when a paper jam occurs in the printing apparatus 94, the outer peripheral portion 171 contacts the paper, and the surface of the outer peripheral portion 171 is damaged. easy.
On the other hand, if the gap length c is too larger than the upper limit of the range, the difference between the outer peripheral portion 171 of the plasma polymerization film 17 and the other portion (the upper surface of the plasma polymerization film 17) increases. It is difficult to perform a uniform oxidation treatment and it is difficult to form a uniform liquid repellent film 19.

  Further, the diameter of the space formed inside the step 23, that is, the width b of the opening 181 of the mask 18 is preferably 2 to 10 times, and 3 to 6 times the inner diameter a of the nozzle hole 111. Is more preferable. By setting it as such a range, the width | variety of the opening part 181 becomes optimal length, and even when a paper jam generate | occur | produces in the printing apparatus 94, the surface of a nozzle vicinity can be protected appropriately.

If the width b of the opening 181 of the mask 18 is too smaller than the lower limit value of the range, the area of the outer peripheral portion 171 becomes small, so that it is difficult to form the liquid repellent film 19.
On the other hand, if the width b of the opening 181 of the mask 18 is too larger than the upper limit value of the range, the area of the outer peripheral portion 171 increases, so that when the paper jam occurs in the printing apparatus 94, the portion 171 and the paper are The outer peripheral portion 171 is easily damaged.
As described above, by performing the oxidation treatment using the mask 18 for forming the step 23 of the plasma polymerized film 17, the step 23 can be easily and efficiently formed in the outer peripheral portion 171.

[3-3] Mask Removal Step After the step 23 is formed, the mask 18 is removed from the plasma polymerized film 17 as shown in FIGS. 9 (e) and 10 (b).
The method for removing the mask 18 differs depending on the type (formation method) of the mask 18. When the plate-shaped mask 18 is used, for example, the mask 18 can be removed by separating from the plasma polymerization film 17. Further, when the mask 18 is formed by vapor deposition or photolithography, for example, it is performed by a method of exposing to oxygen plasma or ozone vapor under atmospheric pressure or reduced pressure, or a method of immersing in a solution or stripping solution of the mask 18. Can do.

[4] Fourth Step In order to prevent ink from adhering to the surface of the nozzle plate 11, as shown in FIG. 9 (f), a metal alkoxide 191 is applied to the surface of the plasma polymerized film 17 on which the step 23 is formed. A liquid repellent film 19 is formed by reaction.
The mechanism for forming the liquid repellent film 19, the metal alkoxide 191, the method for forming the liquid repellent film 19 and the like are the same as those in the first embodiment.
Since the plasma polymerization film 17 is subjected to the oxidation treatment in the processing gas atmosphere and the oxidation treatment using the mask by the method as described above, the liquid repellent film 19 having excellent abrasion resistance is provided, and the step 23 is provided. The inkjet head 1 having the above can be obtained simply, efficiently and at low cost.

In the manufacturing method of the nozzle plate 11 of the present embodiment described above, in the above-mentioned [3] oxidation process for forming a step in [3] third step, the processing gas atmosphere described in the first embodiment is used. Thus, oxidation treatment for forming a step may be performed. In such two oxidation treatments, by performing each oxidation treatment in a processing gas atmosphere, more hydroxyl groups can be introduced into the plasma polymerized film 17, so that the plasma polymerized film 17 and the repellent material can be more strongly repelled. The liquid film 19 can be combined.
In addition, since the step 23 is formed in the plasma polymerization film 17, the outer peripheral portion 171 corresponding to the nozzle hole 111 of the plasma polymerization film 17 is protected even when a paper jam occurs in the printing apparatus 94. Can do.

  Moreover, in the manufacturing method of the nozzle plate 11 of the present embodiment, the oxidation process is not performed in the processing gas atmosphere in the above-described [2] second step, and [3-2] in the above-mentioned [3] third step. Only in the oxidation treatment for forming the step, the oxidation treatment for forming the step may be performed in the processing gas atmosphere described in the first embodiment. As described above, since a large number of hydroxyl groups are introduced into the outer peripheral portion 171 by performing the oxidizing treatment in the processing gas atmosphere only during the oxidation processing for forming the step of [3-2], plasma in the outer peripheral portion 171 is obtained. The adhesion between the polymer film 17 and the liquid repellent film 19 is strengthened, and the rub resistance of the liquid repellent film 19 at the outer peripheral portion 171 is improved.

As mentioned above, although the manufacturing method of the inkjet head of this invention, the inkjet head, and the electronic device were demonstrated based on embodiment of illustration, this invention is not limited to these.
In addition, the inkjet head manufacturing method of the present invention may be a combination of any two or more configurations (features) of the above embodiments.
The oxidation treatment may be performed using a combination of ultraviolet irradiation and plasma irradiation.

Further, the liquid repellent film may be formed on at least a portion having a step even if it is not formed on the entire surface of the plasma polymerization film.
Note that the plasma polymerized film may also be formed on the inner wall surface of the nozzle hole. Therefore, the oxidation treatment may be performed on the surface and the surface continuous with the inner wall surface of the nozzle hole of the plasma polymerization film. As a result, a liquid repellent film may be formed also on those surfaces.

In each of the above embodiments, the method of forming a liquid repellent film using a nozzle plate as a base material has been described as an example. However, the base material is not limited to a nozzle plate, and for example, an inkjet head cap or an inkjet head cleaning Any substrate such as a wiper, gear, platen, carriage, or the like on which a liquid repellent film needs to be formed may be used.
According to the manufacturing method of the ink jet head described above, the balance between the rub resistance and the alkali resistance of the liquid repellent film can be adjusted according to the purpose and necessity by using a gas whose water content is arbitrarily adjusted.

Next, specific examples of the present invention will be described.
1. Production of inkjet head (Example 1)
<1> First, a silicon single crystal substrate having a plane orientation (110) and a diaphragm were pressure-bonded and heat-treated at 400 ° C. for 8 hours. Thereby, the silicon single crystal substrate and the diaphragm were integrated.

Next, after sequentially laminating a conductive material layer, a piezoelectric material layer, and a conductive material layer on the vibration plate, an ink chamber substrate including a piezoelectric element was formed by etching using a dry etching method.
Next, a resist layer having openings corresponding to regions for forming an ink chamber, a reservoir chamber, and a supply port is formed on the substrate by a photolithography method, and then the substrate is etched by a dry etching method to thereby obtain an ink chamber. A recess corresponding to the reservoir chamber and the supply port was formed.
Then, the resist layer was removed by exposing the substrate in which the recesses were formed to oxygen plasma under atmospheric pressure.

<2> A stainless steel (SUS201) substrate was prepared, and the substrate was etched by a beam etching method to form a nozzle plate having a plurality of nozzle holes.
<3> Next, the nozzle plate was installed in the chamber of the film forming apparatus. Then, the inside of the chamber was decompressed to 5.25 × 10 ⁻² Torr, argon gas was supplied into the chamber at a flow rate of 250 sccm, and 100 W of power was applied from a high frequency power source to generate argon plasma.
On the other hand, dimethylpolysiloxane was heated and vaporized by a heater and supplied into the chamber at a flow rate of 50 sccm.
Dimethylpolysiloxane supplied into the chamber and argon plasma were allowed to react for about 5 minutes, and a plasma polymerization film having a film thickness (T ₁ ) of 500 nm was formed on the surface of the nozzle plate on the droplet discharge side.
A plasma polymerization film was also formed on the inner wall of the nozzle hole.

<4> A nozzle plate on which a plasma polymerized film was formed was installed at the bottom of an ultraviolet treatment chamber in which the oxidation treatment space was set to 20 ° C. Then, after replacing the ultraviolet treatment chamber with dry air at 20 ° C., air with a dew point of 10 ° C. (water content: 9.4 g / m ³ ) is supplied into the ultraviolet treatment chamber at a flow rate of 40 sccm, and 300 nm ultraviolet rays are 2000 mJ / Irradiated with an intensity of cm ² for 5 minutes.
As a result, the film thickness (T ₂ ) of the plasma polymerized film after ultraviolet irradiation was 400 nm.

<5> Next, the outer peripheral portion and the opening of the mask are positioned so that the outer peripheral portion corresponding to the nozzle hole of the plasma-polymerized film subjected to the ultraviolet treatment forms an opening, and the plate-like shape is formed on the plasma-polymerized film. Wearing a mask.
Then, the plasma polymerization film was irradiated with 300 nm ultraviolet rays at an intensity of 2000 mJ / cm ² for 5 minutes. As a result, the film thickness (T ₃ ) of the plasma polymerization film at the outer peripheral portion after the ultraviolet irradiation was 200 nm, and the gap length of the step was 200 nm.
Thereafter, the mask was removed away from the plasma polymerization film 17.

  <6> A silane coupling agent (“KY-130” manufactured by Shin-Etsu Silicone Co., Ltd.) having a functional group containing a fluoroalkyl group was dissolved in FR thinner (manufactured by Shin-Etsu Silicone Co., Ltd.) so as to be 0.1 wt%. . This solution was supplied to the surface of the plasma polymerized film obtained in the step <4> by a spin coating method to obtain a liquid repellent film. The liquid repellent film was heated and dried at 100 ° C. for 15 minutes to impart liquid repellency to the liquid repellent film.

<7> The ink chamber substrate provided with the vibration plate and the piezoelectric element and the nozzle plate were joined with an adhesive so that each nozzle hole corresponded to the recess.
<8> The edge of the nozzle plate was supported by a step formed on the outer periphery of the recess in a state where the nozzle plate, the ink chamber substrate, the vibration plate, and the piezoelectric element were housed in the recess provided in the base.
<9> Covering both the nozzle plate and the edge of the substrate with a cover member through an epoxy adhesive (Three Bond 2000 series, “manufactured by Three Bond Co., Ltd.”), the cover member covers the nozzle plate and the substrate. Fixed.
Through the above steps, the ink jet head shown in FIG. 1 was produced.

(Example 2)
An inkjet head was manufactured in the same manner as in Example 1 except that air having a dew point of −10 ° C. was used instead of air having a dew point of 10 ° C. in Step <4> of Example 1.
(Example 3)
An inkjet head was manufactured in the same manner as in Example 1 except that air having a dew point of −20 ° C. was used instead of air having a dew point of 10 ° C. in Step <4> of Example 1.

Example 4
An inkjet head was manufactured in the same manner as in Example 1 except that air having a dew point of −30 ° C. was used instead of air having a dew point of 10 ° C. in Step <4> of Example 1.
(Example 5)
An inkjet head was manufactured in the same manner as in Example 1 except that air having a dew point of −40 ° C. was used instead of air having a dew point of 10 ° C. in Step <4> of Example 1.
(Example 6)
An ink jet head was manufactured in the same manner as in Example 1 except that air having a dew point of 20 ° C. was used instead of air having a dew point of 10 ° C. in Step <4> of Example 1.

(Comparative Example 1)
An ink jet head was manufactured in the same manner as in Example 1 except that air having a dew point of −50 ° C. was used instead of air having a dew point of 10 ° C. in Step <4> of Example 1.
(Comparative Example 2)
An ink jet head was manufactured in the same manner as in Example 1 except that air having a dew point of 30 ° C. was used instead of air having a dew point of 10 ° C. in Step <4> of Example 1.
(Comparative Example 3)
An ink jet head was manufactured in the same manner as in Example 1 except that dry air (RH 0%) was used instead of air having a dew point of 10 ° C. in the step <4> of Example 1.

2. Evaluation The following immersion test, wiping test, and head durability test were carried out on the inkjet head provided with the nozzle plate obtained in each example.
2-1. Immersion test In the immersion test, the inkjet head is immersed in an alkaline solution and then taken out from the alkaline solution. At this time, the alkaline solution adhering to the film shape is repelled on the nozzle plate, and the contact angle is 90 ° or more. The time until a droplet was formed was measured.
In addition, each condition at the time of immersing a board | substrate in an alkaline solution is as showing below.
-Alkaline solution: NaOH aqueous solution (pH: 11)
・ Alkaline solution temperature: 45 ° C
・ Immersion time: 60 minutes

And the time measured as mentioned above was evaluated according to the following four steps for each immersion time.
A: A droplet was formed within 5 seconds.
A: A droplet was formed in 6 to 20 seconds.
(Triangle | delta): The droplet was formed in 21-60 seconds.
X: Droplets having a contact angle of 90 ° C. or more are not formed.

2-2. Wiping test In the wiping test, the wiping operation of extending the alkaline solution with a rubber nozzle cleaning wiper was repeated 2000 times with the alkaline solution adhered on the nozzle plate, and then adhered to the film. The time from when the alkaline solution was repelled until a droplet with a contact angle of 90 ° or more was formed was measured.
Each condition in the wiping operation is as follows.
-Alkaline solution: NaOH aqueous solution (pH: 11)
・ Atmospheric temperature at wiping: 45 ℃

Then, the time measured as described above was evaluated according to the following four criteria.
A: A droplet was formed within 5 seconds.
A: A droplet was formed in 6 to 20 seconds.
(Triangle | delta): The droplet was formed in 21-60 seconds.
X: Droplets having a contact angle of 90 ° C. or more are not formed.
The results of these immersion tests and wiping tests are shown in Table 1 below.

2-3. Head endurance test In the head endurance test, an ink jet head is mounted on an ink jet printer ("PMA-890" manufactured by Seiko Epson Corporation), a predetermined image is printed on 5000 recording papers, and then mounted on the ink jet printer. The inkjet head thus taken out was taken out, and the presence or absence of peeling of the cover member from the nozzle plate and the substrate was visually confirmed.

As shown in Table 1, in any of the examples, it was confirmed that the repellency was maintained even when wiping was repeated 2000 times, and the nozzle plate was excellent in abrasion resistance.
In particular, it was found that when air having a dew point of −20 to 10 ° C. in Examples 1 to 3 was used, a nozzle plate superior in abrasion resistance was obtained.
It was also found that when air having a dew point of −40 to −20 ° C. in Examples 3 to 5 was used, a nozzle plate excellent in alkali resistance and abrasion resistance was obtained.
In any of the examples, peeling of the cover member from the nozzle plate and the substrate could not be observed.
On the other hand, in the comparative example, it was found that when wiping was repeated 2000 times, the liquid repellent film was damaged and the abrasion resistance was poor.

It is a disassembled perspective view which shows embodiment of an inkjet head. It is a sectional front view showing the composition of the principal part of an ink jet head. It is a schematic perspective view which shows embodiment of an inkjet printer. It is a figure for demonstrating an example of the process of the manufacturing method of an inkjet head. It is a figure for demonstrating an example of the process of the manufacturing method of an inkjet head. It is a figure for demonstrating an example of the process of the manufacturing method of a nozzle plate. It is a section front view showing the composition of a 2nd embodiment of the principal part of an ink-jet head. It is a figure for demonstrating an example of the process of the manufacturing method of 2nd Embodiment of a nozzle plate. It is a figure for demonstrating an example of the process of the manufacturing method of 2nd Embodiment of a nozzle plate. It is a top view which shows 2nd Embodiment of a nozzle plate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inkjet head 11 ... Nozzle plate 111 ... Nozzle hole 112 ... Droplet discharge side surface 12 ... Ink chamber substrate 121 ... Ink chamber 122 ... Side wall 123 ... Reservoir chamber 124 ... Supply port 13 ... Diaphragm 131 …… Communication hole 14 …… Piezoelectric element 141 …… Upper electrode 142 …… Lower electrode 143 …… Piezoelectric layer 16 …… Substrate 17 …… Plasma polymerized film 171 …… Outer peripheral part 18 …… Mask 181 …… Opening 19 ... Liquid repellent film 191 ... Metal alkoxide 20 ... Base material 21 ... Resist layer 22 ... Recess 23 ... Step 4 ... Oxidation treatment chamber 41 ... Treatment chamber body 411 ... Oxidation treatment space 412 …… Process gas supply port 413 …… Process gas discharge port 42 …… Cover body 421 …… Ultraviolet light source 43 …… Gas supply means 431 …… Ga Cylinder 432 ... Mass flow controller 433 ... Valve 434 ... Process gas supply pipe 44 ... Gas discharge means 441 ... Process gas discharge pipe 442 ... Valve 443 ... Pump 444 ... Process gas recovery tank 9 ... Inkjet printer 92 …… Device main body 921 …… Tray 922 …… Discharge port 93 …… Head unit 931 …… Ink cartridge 932 …… Carriage 94 …… Printing device 941 …… Carriage motor 942 …… Reciprocating mechanism 943 …… Carriage guide Shaft 944... Timing belt 95... Feeding device 951... Feeding motor 952... Feeding roller 952 a .. Driven roller 952 b.

Claims (14)

A liquid repellent film forming method for forming a liquid repellent film having liquid repellency on a surface of a substrate,
A first step of forming an underlayer composed of a plasma polymerized film on one surface side of the substrate;
Under a gas atmosphere having a dew point of −40 to 20 ° C., a second step of oxidizing the surface of the underlayer and introducing hydroxyl groups and / or adsorbed water;
And a third step of forming the liquid repellent film on the base layer subjected to the oxidation treatment.   The method of forming a liquid repellent film according to claim 1, wherein the oxidation treatment is performed so that the surface of the base layer does not cause dew condensation.   The liquid repellent film forming method according to claim 1 or 2, wherein the second step is performed in a gas atmosphere having a dew point of -40 to -20 ° C.   4. The liquid repellent film forming method according to claim 1, wherein the oxidation treatment is performed by irradiating energy rays.   The method of forming a liquid repellent film according to claim 4, wherein the energy beam is ultraviolet light or plasma.   6. The liquid repellent film forming method according to claim 1, wherein the oxidation treatment is performed a plurality of times, and at least one of them is performed in the gas atmosphere containing the moisture.   The method for forming a liquid repellent film according to claim 1, wherein the plasma polymerization film constituting the underlayer is made of a silicone material.   The liquid-repellent film forming method according to claim 7, wherein the silicone material is composed of organopolysiloxane.   The method for forming a liquid repellent film according to claim 1, wherein the liquid repellent film is composed of a metal alkoxide. An inkjet head manufacturing method for manufacturing an inkjet head in which a liquid repellent film having liquid repellency is formed on a surface of a nozzle plate having nozzle holes,
A first step of forming a plasma polymerization film on the surface of the nozzle plate on the droplet discharge side;
A second step of introducing a hydroxyl group and / or adsorbed water by subjecting the surface of the plasma polymerized film to an oxidation treatment under a gas atmosphere having a dew point of −40 to 20 ° C .;
And a third step of forming the liquid repellent film on the plasma polymerized film subjected to the oxidation treatment.   The inkjet head manufacturing method according to claim 10, wherein the oxidation treatment is performed a plurality of times, and at least one of them is performed in the gas atmosphere containing the moisture.   The oxidation treatment is performed a plurality of times, one of which is selectively performed using a mask at a portion corresponding to the outer peripheral portion of the nozzle hole of the plasma polymerization film, and the film thickness of the plasma polymerization film is reduced. The method of manufacturing an ink jet head according to claim 10, wherein a step is formed by increasing the outer diameter of the nozzle hole to increase the hole diameter.   An ink jet head manufactured by the method of manufacturing an ink jet head according to claim 10.   An electronic apparatus comprising the inkjet head according to claim 13.

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