JP2007106024A - Nozzle plate, inkjet head and inkjet device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a wiping performance and thereby, to ensure the fault-free operation of a discharging system for a long time, by making easily movable an ink which flows around to the back of a wiping blade in its proceeding direction during wiping, while keeping a contact angle and adherence, that is, making the ink follow the movement of the wiping blade through enhancing fall characteristics (a fall angle). <P>SOLUTION: This nozzle plate is constituted of: a nozzle plate base material 11A with nozzle holes 12 for discharging an ink liquid droplet 25 to the outside from a discharging surface; and a liquid repelling layer 11B formed of a fluorine-based silane coupling agent, formed on the discharging surface. The thickness dispersion of the liquid repelling layer 11B is 5 nm or below. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nozzle plate having a liquid repellent layer on the ejection surface side from which ink droplets are ejected, an ink jet head having the nozzle plate, and an ink jet apparatus having the ink jet head.

  In general, an ink jet apparatus is provided with an ink jet head provided with a planar nozzle plate having a plurality of nozzle holes (ejection holes) arranged in a straight line. The inkjet head includes means for supplying ink to the nozzle holes and generating pressure pulses in the ink liquid so that ink droplets are ejected from the nozzle holes, and a small amount of ink liquid of about several pL to several tens of pL. It is possible to eject drops.

  In such an ink jet apparatus, in order to perform high-precision printing, it is necessary to land the ink droplets ejected from the nozzle holes on the printing medium with high accuracy. For this purpose, it is necessary to accurately control the relative position between the nozzle hole and the printing medium. Furthermore, it is necessary to control the amount of ejected ink droplets to make them minute and to accurately control the ejection direction of the ink droplets. Among them, in order to accurately control the ink droplet ejection direction, it is necessary to eject ink droplets in a direction perpendicular to the nozzle plate, but this may cause interference with ink remaining in the vicinity of the nozzle holes. It is difficult to stably eject ink droplets in the vertical direction.

  For example, when ejection is performed in a state where ink droplets are accumulated near the nozzle holes on the ejection surface of the nozzle plate, the newly ejected ink droplets may come into contact with the ink reservoir. In such a case, the ejection direction of the newly ejected ink droplet changes due to interference with the ink accumulated in the vicinity of the nozzle hole. In addition, when the ink reservoir is dried, the discharge direction of the ink droplets changes in the same manner, and the nozzle holes themselves are clogged, resulting in a problem that the ink droplets are not discharged. End up.

  Therefore, the conventional nozzle plate is subjected to a liquid repellent treatment on the discharge surface of the nozzle plate base material constituting the nozzle plate in order to prevent such ink adhesion and adsorption.

  In recent years, as the development of ink jet technology has progressed, the fields of application have been widely developed, and various ejection materials have been used for ejection. Among them, since ink containing pigments and resin components easily adheres to the nozzle plate, it is necessary to provide a liquid repellent layer having particularly high liquid repellency when using such a discharge material.

  However, even with a nozzle plate having a liquid repellent layer, a small amount of ink droplets scattered during ink ejection may adhere to the ejection surface of the nozzle plate. As described above, the ink droplets adhering to the ink droplets and the deposits from which the ink droplets are dried can cause deterioration in ejection accuracy. Therefore, in general, wiping with an wiping blade is performed to remove these ink jet devices. A nozzle hole cleaning mechanism is provided.

  At this time, if a liquid repellent layer is previously formed on the ejection surface of the nozzle plate, ink droplets adhering to the ejection surface can be easily removed by a wiping operation. In other words, the purpose of forming the liquid repellent layer on the nozzle plate is to suppress ink pooling in the vicinity of the nozzle holes and to prevent ink droplets or dried ink droplets from sticking. The nozzle plate can be easily cleaned. As a result, high discharge accuracy can be maintained for a long time.

  In the case of using a fine particle dispersed ink, for example, an ink containing a pigment or silver nanoparticles, the adhering matter that the ink has dried on the ejection surface of the nozzle plate is brought into contact with the ejected ink or solvent again. Since it is difficult to dissolve again, it is necessary to physically remove it by wiping with a wiping blade. At this time, in order to reduce the damage received by the liquid repellent layer due to the contact of the wiping blade, it is generally performed in a state where the wiping blade is wetted by wetting the ejection surface of the nozzle plate with ink.

  Silicone and fluorine-based materials are mainly used as the liquid repellent material. However, when comparing fluorine-based and silicon-based materials, in order to form a low-energy surface, fluorine-based materials are better. Various fluorinated liquid repellent materials have been studied because of their high liquid repellency.

  In addition to high liquid repellency, it is important that the liquid repellent material for forming the liquid repellent layer also has adhesion to the nozzle plate substrate. This is because there may be physical damage during nozzle cleaning or chemical damage such as immersion depending on the type of ink, resulting in peeling from the nozzle plate substrate.

  In view of this, conventional inkjet heads are chemically strong with the nozzle plate substrate through an oxide bonding layer (adhesion layer) having a reactive group such as a hydroxyl group on the surface among various fluorine-based liquid repellent materials. Therefore, there is a configuration in which a fluorine-based silane coupling agent having excellent adhesion and wear resistance is used as the liquid repellent layer (see, for example, Patent Document 1). In the configuration of Patent Document 1, the fluorine-based silane coupling agent is chemically bonded to the nozzle plate base material to prevent peeling from the nozzle plate even after ink immersion and to maintain the initial contact angle. ing.

Moreover, a film forming method of a fluorine-based silane coupling agent is disclosed in which a fluorine-based silane coupling agent that has not adhered to the base material in an unreacted manner is removed in order to further increase the contact angle of the liquid repellent layer ( For example, see Patent Document 2.)
Japanese Patent Laid-Open No. 6-171094 Japanese Patent Laid-Open No. 6-210857

  However, in the configurations of Patent Documents 1 and 2 described above, when the ejection surface of the nozzle plate is wiped, the remaining ink liquid pool can be removed, but the ink that has wetted the ejection surface for wiping is newly added. In such a case, it remains on the discharge surface in a minute amount that cannot be visually observed. The newly remaining trace amount of ink as an adhering substance adversely affects the ink droplet ejection accuracy. Furthermore, since ink deposits are likely to occur with these deposits as nuclei, the discharge accuracy is deteriorated and the generation of deposits is promoted.

  This is because the ink supplied to wet the wiping blade at the time of wiping wraps around from the side of the wiping blade in the moving direction of the wiping blade to the rear surface of the wiping blade in the moving direction from the side of the wiping blade. Because. That is, wiping is performed while dragging the ink that the wiping blade has turned around.

  A part of the ink that has entered the rear surface of the wiping blade in the traveling direction cannot follow the movement of the wiping blade and is separated in the middle. In particular, when a step is formed on the ejection surface of the nozzle plate with which the wiping blade comes into contact, the ink wraps around the rear surface of the wiping blade due to the step, so that ink tends to accumulate near the step portion, and ink residue is noticeable. appear.

  The object of the present invention is to improve the ease of movement of the ink that wraps around the back surface of the wiping blade during wiping, that is, the tumbling characteristics (falling angle) while maintaining the contact angle and adhesion, and wiping the ink. An object of the present invention is to provide a nozzle plate, an ink jet head, and an ink jet apparatus that can follow the movement of the blade and improve the wiping performance to maintain a long-term discharge system.

  In order to solve the above problems, the present invention has the following configuration.

(1) a nozzle plate substrate having ejection holes for ejecting ink droplets from the ejection surface to the outside;
A liquid repellent layer formed of a fluorine-based silane coupling agent on the ejection surface, the liquid repellent layer having a thickness variation of 5 nm or less.

  In this configuration, a liquid repellent layer is formed on the discharge surface of the nozzle plate base material with a fluorine-based silane coupling agent having a high contact angle. Further, the variation in the thickness of the liquid repellent layer is 5 nm or less. Therefore, the falling angle of the liquid repellent layer is less than 90 °. Further, when the thickness is 1.5 nm or less, the falling angle is 40 ° or less.

  Therefore, the fall characteristics are improved without lowering the contact angle and adhesion, so that the ink can easily follow the movement of the wiping blade, and the ink that follows in the middle of the movement of the wiping blade is reduced and separated. Generation of kimono is suppressed.

  (2) The liquid repellent layer has an average thickness of 1 nm or more and 4 nm or less.

In this configuration, the average thickness is 1 nm or more and 4 nm or less, and the liquid repellent layer is formed on the discharge surface of the nozzle plate substrate. The fluorine carbon group exhibiting liquid repellency of the fluorine-based silane coupling agent has a smaller surface energy as the number of fluorine atoms increases. When compared with the contact angle of the solid surface, CF ₃ > CF ₂ <CF. Therefore, when the average thickness is larger than 4 nm, the fluorine-based silane coupling agents are entangled with each other, and the ratio of the CF _{3 at the} end portion having the smallest sea surface energy covering the surface is decreased, and the liquid repellency may be deteriorated. There is.

  On the other hand, if the average thickness is too thin, less than 1 nm, thickness variations are likely to occur, and there is a possibility that a part of the liquid repellent layer does not react with the nozzle plate substrate. Affects sex.

  Therefore, since the average thickness of the liquid repellent layer is 1 nm or more and 4 nm or less, adhesion and liquid repellency are not lowered.

  (3) The nozzle plate base material has an adhesion layer between the ejection surface and the liquid repellent layer.

  In this configuration, an adhesion layer is formed on the discharge surface of the nozzle plate substrate, and a liquid repellent layer is further formed on the adhesion layer. Therefore, even if there is no sufficient hydroxyl group on the ejection surface due to the material of the nozzle plate base material, the adhesion does not deteriorate.

  (4) The adhesion layer is an inorganic oxide.

  In this configuration, an adhesion layer formed of an inorganic oxide is provided between the discharge surface of the nozzle plate substrate and the liquid repellent layer. Since the inorganic oxide has a sufficient number of hydroxyl groups for bonding on the surface, it easily bonds to the fluorine-based silane coupling agent.

(5) The nozzle plate base material is a polymer material that absorbs ultraviolet energy,
The ejection holes are formed using an excimer laser.

  In this configuration, the nozzle plate base material is irradiated with an excimer laser with high processing accuracy to form discharge holes. In addition, since the nozzle plate base material is formed of a polymer material that absorbs ultraviolet energy, the processing accuracy of the excimer laser does not decrease.

  (6) The adhesion layer has an average thickness of 5 nm or more and 30 nm or less.

  In this configuration, an adhesion layer formed with an average thickness of 5 nm or more and 30 nm or less is provided between the discharge surface of the nozzle plate substrate and the liquid repellent layer. When forming the discharge holes after forming the adhesion layer and the liquid repellent layer on the nozzle plate base material, the processing accuracy is affected by the thickness of the adhesion layer. Therefore, if the average thickness of the adhesion layer is greater than 30 nm, the processing is performed. There may be unevenness. This is because the inorganic oxide formed in the adhesion layer has a high bond energy between inorganic and oxygen atoms and is a chemically stable material, and therefore it is difficult to process with an excimer laser with high accuracy. . Further, if the average thickness of the adhesion layer is greater than 30 nm, film unevenness is likely to occur. This film unevenness may cause film unevenness in the liquid repellent layer.

  On the other hand, if the average thickness of the adhesion layer is 5 nm or less, the adhesion layer may not be evenly and reproducibly coated on the nozzle plate base material, ensuring the adhesion, liquid repellency, and falling characteristics of the liquid repellent layer. There is a possibility that it cannot be done.

  Therefore, since the average thickness of the adhesion layer is 5 nm or more and 30 nm or less, the liquid repellent layer can be formed uniformly and with good reproducibility, and processing unevenness in the discharge holes can be prevented.

(7) a head portion having an ink chamber;
The nozzle plate according to claim 1, wherein the nozzle hole is bonded to the head portion in a state where the nozzle hole communicates with the ink chamber.

  In this configuration, ink droplets stored in the ink chamber are discharged from the discharge holes formed in the nozzle plate according to any one of (1) to (6). Further, a liquid repellent layer is formed with a fluorine-based silane coupling agent having a high contact angle on the discharge surface of the nozzle plate base material constituting the nozzle plate. Further, the variation in the thickness of the liquid repellent layer is 5 nm or less. Therefore, the falling angle of the liquid repellent layer is less than 90 °. Further, when the thickness is 1.5 nm or less, the falling angle is 40 ° or less.

  Therefore, the fall characteristics are improved without lowering the contact angle and adhesion, so that the ink can easily follow the movement of the wiping blade, and the ink that follows in the middle of the movement of the wiping blade is reduced and separated. Generation of kimono is suppressed.

(8) In an inkjet apparatus that ejects ink droplets to a desired position,
The inkjet head according to claim 7 is provided.

  In this configuration, ink droplets are ejected from the inkjet head described in (7) to a desired position. A liquid repellent layer is formed with a fluorine-based silane coupling agent having a high contact angle on the ejection surface of the nozzle plate base material constituting the nozzle plate constituting the ink jet head. Further, the variation in the thickness of the liquid repellent layer is 5 nm or less. Therefore, the falling angle of the liquid repellent layer is less than 90 °. Further, when the thickness is 1.5 nm or less, the falling angle is 40 ° or less.

  Therefore, the fall characteristics are improved without lowering the contact angle and adhesion, so that the ink can easily follow the movement of the wiping blade, and the ink that follows in the middle of the movement of the wiping blade is reduced and separated. Generation of kimono is suppressed.

  According to the present invention, the following effects can be obtained.

  (1) By providing a liquid-repellent layer with a thickness variation of 5 nm or less using a fluorine-based silane coupling agent on the discharge surface of the nozzle plate, the fall characteristics can be improved and the occurrence of deposits due to wiping can be suppressed. Therefore, wiping performance can be improved, and high discharge accuracy can be maintained in the long term while maintaining the contact angle and adhesion. Moreover, if the thickness variation is 1.5 nm or less, the generation of deposits can be further suppressed.

  Furthermore, since the fall characteristics can be improved, it is possible to reduce the pressing pressure required for the wiping blade at the time of wiping, and it is possible to solve problems such as wear and scratches, so that the durability of the nozzle plate against wiping can be improved. .

  (2) By forming a liquid repellent layer having an average thickness of 1 nm or more and 4 nm or less on the discharge surface of the nozzle plate base material, it is possible to prevent the liquid repellency and adhesion from deteriorating.

  (3) By forming an adhesion layer between the discharge surface of the nozzle plate base material and the liquid repellent layer, even if there is not enough hydroxyl group on the discharge surface depending on the material of the nozzle plate, adhesion is ensured. be able to.

  (4) By forming the adhesion layer with an inorganic oxide, the ejection surface of the nozzle plate substrate and the liquid repellent layer can be firmly bonded, and adhesion can be ensured.

  (5) By using the excimer laser to form the discharge holes in the nozzle plate base material made of a polymer material that absorbs ultraviolet energy, it is possible to stably form the discharge holes with high processing accuracy and ensure the discharge accuracy. can do.

  (6) By forming an adhesion layer having an average thickness of 5 nm or more and 30 nm or less on the discharge surface of the nozzle plate substrate, the liquid repellent layer can be formed uniformly and with good reproducibility, and the discharge hole Since processing unevenness can be prevented, stable ejection accuracy can be ensured.

  (7) By adhering the nozzle plate described in (1) to (6) to the head part, the fall characteristics can be improved, and the occurrence of deposits due to wiping can be suppressed, so that the wiping performance can be improved, and the contact angle and adhesion High discharge accuracy can be maintained in the long term while maintaining the properties. Furthermore, since the fall characteristics can be improved, it is possible to reduce the pressing pressure required for the wiping blade at the time of wiping, and it is possible to solve problems such as wear and scratches, so that the durability of the nozzle plate against wiping can be improved. .

  (8) By providing the ink jet head described in (7), the fall characteristics can be improved, and the generation of deposits due to wiping can be suppressed, so that the wiping performance can be improved, and the contact angle and adhesion are maintained for a long time. High discharge accuracy can be maintained.

  Furthermore, since the fall characteristics can be improved, it is possible to reduce the pressing pressure required for the wiping blade at the time of wiping, and it is possible to solve problems such as wear and scratches, so that the durability of the nozzle plate against wiping can be improved. .

  Hereinafter, an ink jet apparatus according to the best embodiment of the present invention will be described in detail with reference to the drawings. In addition, this embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and includes all modifications within the scope and meaning equivalent to the terms of the claims.

  FIG. 1 is an explanatory diagram showing a simple configuration of an ink jet apparatus according to an embodiment of the present invention. The inkjet apparatus 20 includes a droplet discharge unit 21, a maintenance unit 22, a droplet curing unit 23, and the like. The droplet discharge unit 21 has the inkjet head 10 mounted thereon. The maintenance unit 22 cleans a discharge surface of a nozzle plate described later by wiping. The droplet curing unit 23 cures the ink droplet 25 that has landed on the substrate 24 as necessary.

  The droplet discharge unit 21 includes an XY stage 26, an inkjet head 10, a CCD camera 27, a control device 28, an XY stage driver unit 29, an inkjet head driver unit 30, a support member 31, and the like.

  The XY stage 26 is mounted with a printing medium 24 and supported so as to be movable in two axial directions of an X axis and a Y axis representing two-dimensional plane coordinates that are horizontal plane coordinates. The inkjet head 10 ejects ink droplets 25 from a plurality of nozzle holes of the nozzle plate. The CCD camera 27 has a charge coupled device (abbreviated as CCD), images the ink droplets 25 landed on the printing medium 24 from a direction substantially perpendicular to the surface of the printing medium 24, and the captured image. Data is transmitted to the control device 28.

  The control device 28 controls the overall operation of the inkjet device 20. The XY stage driver unit 29 and the inkjet head driver unit 30 are connected to the control device 28. The support member 31 supports the inkjet head driver 30 and the CCD camera 27.

  The XY stage 26 has a flat one surface portion, and the one surface portion serves as a placement surface on which the printing medium 24 is placed. The XY stage 26 positions the printing medium 24 by a projection-shaped positioning pin (not shown), and vacuum-sucks the printing medium 24 by a vacuum suction means (not shown) to fix it on the mounting surface.

  The XY stage 26 is driven by the control device 28 via the XY stage driver unit 29. The control device 28 adjusts the position of the XY stage 26 so that the position where the ink droplet 25 should land on the printing medium 24 placed on the XY stage 26 is a position where the CCD camera 27 can capture an image. Further, the control device 28 determines that the position where the ink droplet 25 confirmed by the captured image data of the printing medium 24 placed on the XY stage 26 should land is a position where the liquid material can be ejected from the inkjet head 10. Thus, the position of the XY stage 26 is adjusted.

  The inkjet head 10 is driven by the control device 28 via the inkjet head driver unit 30. The control device 28 drives the inkjet head 10 so that the ejection material is ejected to the position where the ink droplet 25 confirmed by the imaged image data of the printing medium 24 placed on the XY stage 26 should land. To do. As a result, the ejection material is ejected from the inkjet head 10 to the position where the ink droplet 25 should land.

  The maintenance unit 22 includes a suction cap 32, a rubber blade (wiping blade) 33, and the like, and cleans the discharge surface of the nozzle plate 11 by wiping. The suction cap 32 covers the nozzle holes and sucks ink from the covered nozzle holes. The rubber blade 33 wipes ink droplets remaining on the ejection surface of the nozzle plate 11.

  A plurality of suction caps 32 and rubber blades 33 may be provided. For example, when a plurality of ink jet heads 10 are mounted, ink suction and wiping of the plurality of ink jet heads 10 are performed at a time. It can be carried out.

  The suction cap 32 is provided with a lip portion having elasticity to cover the periphery of the ejection surface of the nozzle plate 11 of the inkjet head 10 and to maintain hermeticity. Further, the suction cap 32 is connected to the back surface of a suction pump (not shown) and an air communication valve that sucks the inside of the space formed by the nozzle plate 11. This suction pump sucks the discharge surface of the nozzle plate 11 covered and sealed by the suction cap 32 through the suction cap 32.

  Further, the maintenance unit 22 includes a blade movable portion (not shown) that supports the rubber blade 33 and rotates the contact surface of the rubber blade 33 in parallel with the discharge surface of the nozzle plate 11. The rubber blade 33 is formed of an elastic body, and although it depends on the discharge material used, perfluorofluororubber having excellent chemical resistance is desirable.

  The droplet curing unit 23 dries the ink droplet 25 that has landed on the printing medium 24 as necessary when the discharge material is a curable resin or the like. Accordingly, the ink droplets 25 can be ejected and dried on the same apparatus, and printing can be completed more easily.

  For example, when a photocurable resin composition such as an ultraviolet curable resin composition is used as the discharge material, the droplet curing unit 23 may be equipped with a light irradiation mechanism 34 such as an ultraviolet ray. As shown in FIG. 1, the light irradiation mechanism 34 adjusts the amount of light emitted from the lamp 34, a substrate table 341 on which the printed material 24 is placed, a lamp 342 that irradiates the printed material 24 with light. And an irradiation amount adjusting device 343. In the case where it is not necessary to cure the discharged material, a configuration without the droplet curing unit 23 may be employed.

  Moreover, when using a thermosetting resin composition, it may replace with the light irradiation mechanism 34, and should just provide the heating means which is not shown in figure which heats a solidification component. Examples of the heating means include an infrared lamp and a hot plate, but the user may select as appropriate.

  FIG. 2 is an explanatory diagram showing the configuration of the inkjet head 10 provided in the inkjet apparatus 20 according to the embodiment of the present invention. FIG. 2 shows a state before the nozzle plate 11 is bonded to the inkjet head 10. The inkjet head 10 is shown in a cross-sectional view so that the internal structure can be seen.

  The inkjet head 10 includes a nozzle plate 11, a piezo element 13, a cover plate 14, and the like. In general, inkjet heads are roughly classified into a piezo type and a thermal type. The former is a method of ejecting ink by using a piezoelectric element (piezo element) that is deformed by applying a voltage, creating a mechanism like a piston. On the other hand, in the latter, a high temperature is applied to the ink with a heater, the ink is vaporized instantaneously, and the ink is ejected from the nozzle holes by bubbles generated at this time.

  Although the inkjet head 10 according to the present embodiment is a piezo type, it can also be applied to a thermal type or other type of inkjet head.

  The nozzle plate 11 has a plurality of nozzle holes 12, and is bonded to the head portion to which the piezo elements 13 and the cover plate 14 are bonded in a state where the nozzle holes 12 communicate with the ink flow path 15. The piezo element 13 includes upper 13A and lower 13B elements having different polarization directions. By applying a voltage to the piezo elements 13A and 13B, the partition walls of the piezo elements 13A and 13B are driven, and the volume of the portion surrounded by the partition walls (ink flow path 15) is changed. As a result, the pressure in the ink flow path 15 changes, and the ink supplied to the ink chamber 14 is ejected from the nozzle hole 12. The nozzle hole 12 corresponds to the discharge hole of the present invention.

  The cover plate 14 includes an ink chamber 16 that stores ink, and is bonded to the piezo element 13A.

  Moreover, the nozzle plate 11 is comprised from the nozzle plate base material 11A and the liquid repellent layer 11B, as shown to FIG. 3 (A). 11 A of nozzle plate base materials are formed with metal materials, such as iron, aluminum, nickel, stainless steel, glass, etc. which are materials which have many hydroxyl groups in order to couple | bond with the liquid repellent layer 11B.

  In addition, about the material of 11 A of nozzle plate base materials, if it has sufficient hydroxyl group in order to react with a fluorine-type silane coupling agent, not only what was mentioned above but a user can select suitably.

  Therefore, materials other than those described above can be used as long as they can introduce hydroxyl groups into the discharge surface using oxygen plasma or the like. Examples of the material capable of introducing a hydroxyl group include inorganic materials such as silicon wafer and zirconium oxide, and resin materials such as polyimide and polypropylene.

  However, in the portion where the hydroxyl group exists, the nozzle plate substrate 11A and the fluorine-based silane coupling agent can be chemically strongly bonded, but if the hydroxyl group is insufficient, good adhesion and liquid repellency are obtained. In some cases, it is necessary to select a material for the nozzle plate base 11A or perform an appropriate treatment depending on the desired wear resistance and liquid repellency.

The liquid repellent layer 11B is composed of a liquid repellent layer material similar to a fluorine-based silane coupling agent. The fluorine-based silane coupling agent is a silicon compound represented by Y _n SiX _4-n (n = 1, 2, 3), and X is a condensation with a hydroxyl group or adsorbed water on the discharge surface of the nozzle plate substrate 11A. It consists of a group that can be bound by The use varies depending on the number of Y. For example, n = 1 is used as a coupling agent, n = 2 is used as a siloxane polymer raw material, and n = 3 is used as a silylating agent or polymer endcapping agent. .

  In particular, a silane coupling agent containing a fluorocarbon chain in Y is called a fluorine-based silane coupling agent, and has both water repellency and oil repellency properties, such as liquid repellency, antifouling, deodorization, and lubrication. It is widely used as a surface treatment agent for the purpose.

  Fluorocarbon compounds are the most electronegative fluorine combined with carbon and the most oxidized state of carbon, so it has excellent oxidation resistance, nonflammability, and is extremely chemically stable. It has the characteristic of being. Moreover, since the electronegativity is high, the bond energy of carbon-fluorine is large, and furthermore, the fluorine atom is only about 10% larger than the hydrogen atom, so the bond distance between carbon and fluorine is short.

  Moreover, the fluorocarbon chain has a rigid rod-like structure having a twist period of 13 carbon atoms. The carbon skeleton inside the rigid rod is covered with fluorine atoms present on the surface without any gaps, that is, the carbon chain is covered with a fluorine sheath. Therefore, the fluorocarbon compound has the above-described characteristics because carbon and fluorine are extremely strongly bonded in the molecule, but only a very weak interaction is exhibited between the molecules.

  The liquid repellent layer material of the present invention may be a compound represented by YSiX3 used as a coupling agent and may be any fluorine-based silane coupling agent containing a fluorocarbon chain in Y.

For example, as Y, CF ₃ (CF ₂ ) n (CH ₂ ) ₂ (n = 3, 5, 7, 9), (CF ₃ ) ₂ CF (CF ₂ ) _n (CH ₂ ) ₂ (n = 4) , 6, 8), CF ₃ (CF ₂ ) _n (C ₆ H ₄ ) (CH ₂ ) ₂ (n = 0, 3, 5, 7).

In general, it is known that a fluorocarbon chain exhibiting liquid repellency of a fluorine-based silane coupling agent is linear, and the longer the fluorocarbon chain, the better the liquid repellency. Therefore, among Y mentioned above, it is desirable to use a liquid repellent layer material such as CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ or CF ₃ (CF ₂ ) ₉ (CH ₂ ) ₂ .

  Further, X needs to be a hydrolyzable linking group in order to condense and bond with the hydroxyl group and adsorbed water on the discharge surface of the nozzle plate substrate 11A, and examples thereof include Cl, OCH3, and OCH2 CH3. . However, when it is necessary to suppress the reactivity with the nozzle plate base material 11A, it is not necessary that all three Xs are as described above, and even if one or two groups are non-hydrolyzable CH3 or the like. Good.

  As described above, as the liquid repellent layer material comprising the fluorine-based silane coupling agent of the present invention, the desired liquid repellency, reactivity with the nozzle plate 11A base material, etc., among the combinations of X and Y described above, etc. Therefore, the user may select a liquid repellent layer material to be used as appropriate.

  When a fluorine-based silane coupling agent is applied as the liquid repellent layer 11B to the discharge surface of the nozzle plate substrate 11A having a hydroxyl group, one of the bonding groups undergoes a condensation reaction with the hydroxyl group of the nozzle plate 11A substrate. As a result, the siloxane (—Si—O—) bond in which Si and O are chemically bonded strongly bonds the nozzle plate base material 11A and the fluorine-based silane coupling agent, thereby exhibiting high adhesion.

  In addition, the remaining two bonding groups are converted into hydroxyl groups by reaction with water to form silanol (—Si—OH) groups, which are condensed with the silanol (—Si—OH) groups of adjacent fluorine-based silane coupling agents. Therefore, a siloxane (—Si—O—) network is also formed between the fluorine-based silane coupling agents.

Of the fluorine-based silane coupling agents described above, Y = CF ₃ (CF ₂ ) _n (CH ₂ ) ₂
As an example, FIG. 4 schematically shows the surface structure of the discharge surface of the lyophobic nozzle plate substrate 11A. In the fluorine-based silane coupling agent, the bonding group undergoes a condensation reaction with the base material, and is chemically bonded to the nozzle plate base material 11A via the siloxane (—Si—O—) bond 111B.

  Further, the other end of the fluorocarbon chain 112B covers the discharge surface of the nozzle plate substrate 11A, and the liquid repellent layer 11B is formed on the discharge surface of the nozzle plate substrate 11A. As a result, characteristics such as liquid repellency, incombustibility, and chemical inertness of the fluorocarbon chain 112B are imparted to the ejection surface of the nozzle plate base 11A. In addition, the fluorine-based silane coupling agents are also strongly bonded to each other by a siloxane (—Si—O—) bond 111B.

  In this embodiment, the liquid repellent layer 11B is formed on the discharge surface of the nozzle plate substrate 11A. However, as shown in FIG. 3B, an adhesion layer is provided between the discharge surface and the liquid repellent layer 11B. 11C may be provided. This is because, even when oxygen plasma treatment or the like is used, when a sufficient hydroxyl group cannot be expressed on the discharge surface of the nozzle plate substrate 11A, a hydroxyl group can be provided on the discharge surface of the nozzle plate 11A, and adhesion can be secured. Effective in terms.

  As an adhesive layer material for forming the adhesive layer 11C, for example, an inorganic oxide such as alumina, titania, or silicon oxide is desirable. Since many hydroxyl groups exist on the surface of this inorganic oxide, it is suitable as an adhesive layer for a fluorine-based silane coupling agent. Therefore, the fluorine-based silane coupling agent is bonded to many hydroxyl groups of the adhesion layer 11C, and a high-density liquid repellent layer can be formed, so that high liquid repellency can be obtained. Furthermore, the adhesion to the nozzle plate substrate 11A is also improved, and the physical and chemical durability of the liquid repellent layer is imparted.

  Inorganic oxides generally have large free energy and are chemically stable, which leads to chemical resistance of the adhesion layer itself.

  The method for forming the adhesion layer 11C is not particularly specified. For example, a sputtering method in which an inorganic oxide is formed by sputtering on the discharge surface of the nozzle plate base 11A, aluminum, titanium, silicon, or the like. There is a reactive sputtering method in which sputter film formation is performed while introducing oxygen using a non-oxidized material.

  It is also possible to form an inorganic oxide adhesion layer by forming a simple substance such as aluminum, titanium, or silicon by sputtering and then performing an oxidation treatment using oxygen plasma or the like.

  An example of a manufacturing process of the nozzle plate 11 having the liquid repellent layer 11B and the adhesion layer 11C will be described.

  The liquid repellent layer material, the nozzle plate base material 11A, and the adhesion layer material may be appropriately selected and used by the user from the above-described materials, and the following is an example.

The case where a polyimide film (Upilex S50 manufactured by Ube Industries, Ltd.) is used as the nozzle plate substrate 11A will be described as an example. The polyimide film is suitable for the nozzle plate substrate 11A because it has the characteristics of excellent mechanical strength, heat resistance, and chemical resistance and also has good laser processability. However, as described above, the nozzle plate base material 11A is not limited to this.

In addition, it is preferable to wash | clean the nozzle plate base material 11A as needed for the purpose of removing the oil-and-fat dirt on the surface before formation of the contact | adherence layer 11C. For example, when using a polyimide film, wash with a neutral detergent, remove the oil and grease stains on the surface, and then wash with pure water so that the detergent components do not remain. Just do it.

Further, as described above, it is desirable to use an inorganic oxide having many hydroxyl groups on the surface as the adhesion layer material.

  First, silicon oxide is formed with a film thickness of 10 nm on the discharge surface of the nozzle plate substrate 11A by RF sputtering to form the adhesion layer 11C. The method for forming the adhesion layer 11C is not particularly limited as described above, and the user may appropriately select a known method.

  As the liquid repellent layer material, a fluorine-based silane coupling agent is used. In general, the longer the fluorocarbon chain of the fluorinated silane coupling agent is, and the longer the fluorocarbon chain, the better the liquid repellency. Therefore, when high liquid repellency is required, a fluorine-based silane coupling agent may be used, but the type is not particularly limited. The user may appropriately select the desired liquid repellency, reactivity with the nozzle plate substrate 11A, and the like.

In addition, the fluorine-carbon group exhibiting liquid repellency of the fluorine-based silane coupling agent has a smaller surface energy as the number of fluorines increases. Compared with the contact angle of the solid surface, CF ₃ > CF ₂ > CF. The contact angle increases in order. Therefore, the fluorine-based silane coupling agent is used in the nozzle plate so that the terminal CF ₃ appears cleanly on the surface as shown in FIG. 4 rather than the fluorine-based silane coupling agent is entangled to coat the surface of the substrate thickly. The liquid-repellent layer 11B arranged in a monomolecular state can be obtained with better liquid repellency without excessive or insufficient on the discharge surface of the base material 11A.

  If the concentration of the fluorinated silane coupling agent is too high, the siloxane (—Si—O—) bond between the fluorinated silane coupling agents tends to advance and become entangled. Therefore, it is desirable to dilute to an appropriate concentration.

  Here, examples of the solvent that can be used include fluorinated solvents such as chlorofluorocarbon and perfluorohexane, methanol, ethanol, ethyl acetate, benzene, and the like, and it is preferable to dilute to a low concentration of 1% or less.

  The thus prepared fluorinated silane coupling agent solution is applied onto the discharge surface of the nozzle plate base 11A on which the adhesion layer 11C is formed, thereby forming the liquid repellent layer 11B.

The application method of the fluorine-based silane coupling agent solution is not particularly limited, and brush coating, spray coating, dip coating, spin coating, vapor deposition, or the like may be used. However, it is important to apply so as not to cause uneven coating.

  Moreover, you may heat-process after fluorine-type silane coupling agent application | coating. This is because heat treatment after application of the fluorine-based silane coupling agent generally has an effect of promoting the formation of a siloxane (—Si—O—) network.

  In general, when a liquid repellent layer 11B is formed by applying a fluorine-based silane coupling agent, solvent cleaning is performed for the purpose of removing excess fluorine-based silane coupling agent. Here, the solvent to be used may be the same as that used when diluting the fluorine-based silane coupling agent, or other solvents exemplified above may be used. The solvent washing | cleaning method should just immerse for about several minutes in the solvent used for the diluent, for example.

Next, nozzle holes 12 are formed on the nozzle plate base material 11A on which the liquid repellent layer 11B is formed using an excimer laser processing apparatus. The nozzle hole 12 is processed from the surface side of the nozzle plate substrate 11A where the liquid repellent layer 11B is not formed. The nozzle hole diameter to be processed is defined by the mask size, and can be appropriately set according to the desired ink discharge amount. The nozzle hole 12 for the inkjet head 10 is generally a circular one having a diameter of 10 μm to 100 μm.

  In order to further improve the processing accuracy in processing using an excimer laser, a polymer material such as a polyimide film or polypropylene that absorbs ultraviolet rays is preferably used for the nozzle plate base 11A.

Example 1
With respect to the nozzle plate 11 of the present invention, nozzle plates with different variations in the thickness of the liquid repellent layer 11B are generated and the performance is compared, and the results of observing the surface state of the generated liquid repellent layer 11B are shown. In Example 1, performance evaluation and the like were performed with a configuration in which the adhesion layer 11C was not provided.

  In the first embodiment, a thermally oxidized silicon substrate (manufactured by Electronics End Materials Corporation) is used as the nozzle plate substrate 11A. Since a dense silicon oxide layer is formed on the surface of a thermally oxidized silicon substrate, it has a sufficient hydroxyl group, so that a fluorine-based silane coupling agent can be formed at a high density, and the substrate surface Is extremely flat, the thickness variation of the formed liquid repellent layer 11B can be estimated.

  The thermally oxidized silicon substrate has a diameter of 150 mm, a thickness of 625 μm, and the thickness of the silicon oxide layer formed on the surface layer is 500 nm. A 50 mm square cut out was used as the nozzle plate substrate 11A.

  The liquid repellent layer material for forming the liquid repellent layer 11B is Optool DSX (manufactured by Daikin Industries, Ltd.) and 200-fold diluted with demnum solvent SOL-1 (manufactured by Daikin Industries, Ltd.) as a diluent. It was used. Optool DSX itself is obtained by diluting a fluorine-carbon compound by 20% with a solvent, and the resulting liquid-repellent layer solution has a fluorine-carbon compound concentration of 0.1%.

  As a coating method of the liquid repellent layer solution (fluorine silane coupling agent solution), spin coating was used. For spin coating, 1 mL of the liquid repellent layer solution was weighed out using a syringe, dropped onto the discharge surface of the nozzle plate substrate 11A, and performed at a rotation speed of 500 rpm for 30 seconds. Thereafter, solvent washing and heat treatment were performed.

  The heat treatment was performed in an oven at 100 ° C. for 2 hours. For solvent washing, demnam solvent SOL-1 used as a diluent was used. This solvent washing was completed by weighing about 100 mL of demnum solvent SOL-1 in a petri dish, immersing the nozzle plate base material 11A for 2 minutes, and then pulling up as it was.

  As a result of the above procedure, samples A to E of the nozzle plate 11 having the liquid repellent layer 11B were formed. The samples A to E use the same nozzle plate base material 11A and the same liquid repellent layer material, and have the same application amount of the liquid repellent material, but have different falling angles as will be described later.

  Moreover, the sample F which formed the liquid repellent layer 11B into a film by vacuum deposition using the same liquid repellent layer material and the nozzle plate base material 11A was formed. The average thickness of the liquid repellent layer 11B for the materials A to F is substantially the same.

  For samples A to F, the contact angle and the falling angle were measured, and the performance of the liquid repellent layer 11B was compared.

  A contact angle meter (Drop Master 700) manufactured by Kyowa Interface Science Co., Ltd. was used for measurement of the contact angle and the sliding angle. The contact angle is a value obtained by dropping 1.3 μl of pure water on the sample and calculating the angle formed by the water droplet with the sample surface by the θ / 2 method. In the measurement of the falling angle, 1.8 μl of pure water is dropped on the sample, and the sample stage is continuously inclined from 0 ° to 90 ° in about 40 seconds. At this time, the dropped pure water was observed with a CCD camera, and the tilt angle of the sample stage when the water droplet started to move was defined as the falling angle.

  FIG. 5 is a diagram showing the measurement results of the contact angle and the sliding angle in samples A to F. Although the contact angle was a high value of 113 ° or more in all the samples A to F, a result that the falling angle varied greatly was obtained. This value exceeds the contact angle of about 109 ° of Teflon (PTFE), which is known as an excellent water repellent material.

  Here, since the samples A to E applied by the same spin coating vary, the variation in the falling angle is not caused by the difference in the application method between spin coating and vapor deposition.

  In the case where such a liquid repellent layer 11B is formed on an inkjet nozzle plate 11 and used, particularly in an ink that has a large effect on the adhesion of a liquid, such as an ink containing a resin and a pigment. It is inappropriate to simply evaluate the wiping performance based on the static contact angle between the nozzle plate 11 and the ink, and it is necessary to consider the fall characteristics (fall angle).

  Then, the confirmation experiment of the wiping performance by the difference of the falling angle was conducted. By immersing Sample A (with a falling angle of 13 °) with good falling characteristics and Sample B (with a falling angle> 90 °) with poor falling characteristics in ink, the discharge surface of the nozzle plate 11 gets wet with ink during wiping. Reproduced. The ink used is an ink obtained by dispersing about 10% of a pigment and a synthetic resin using an organic solvent as a solvent, has a surface tension of about 30 mN / m at room temperature, and a viscosity of about 10 cP.

  After dipping for about 1 hour, the ink was pulled up from the ink at a speed of about 20 mm / second and observed with a microscope, and a deposit 40 of about 1 μm as shown in FIG. 6 was confirmed. Although FIG. 6 is a photograph in the case of sample A with good falling characteristics, the same amount of deposit 40 was confirmed in sample B with poor falling characteristics, so the photograph is omitted. At this time, the ink droplets at the visual level did not remain in both samples A and B. This is considered to be because both samples have high liquid repellency of 113 ° or more.

  About both samples A and B which have the deposit 40, the same ink as what was used for immersion was dripped, and the manual wiping was performed using the rubber blade. The rubber blade has a width of 16.1 mm, a thickness of 0.5 mm, and a rubber hardness of 70 degrees.

  The result of microscopic observation again after wiping is shown in FIG. 7 for sample A with good fall characteristics and in FIG. 8 for sample B with bad fall characteristics. As shown in FIG. 7, the deposit 40 was able to be removed in the sample A having a good fall characteristic, but in the sample B having a bad fall characteristic, as shown in FIG. It could not be removed.

  In both samples, it was confirmed that the deposit 40 was removed when wiping was performed without dropping ink. Therefore, it is considered that the deposit 40 that has already occurred when the nozzle plate 11 is lifted from the ink can be physically removed by wiping.

  The result of this experiment will be considered as follows using the schematic diagram of the wiping operation shown in FIG. From the above confirmation experiment, the deposit 40 generated at the time of lifting from the ink is removed from the surface of the liquid repellent layer 11B by physical contact of the edge portion of the rubber blade 33 when wiping is performed by the rubber blade 33. Should have been.

  However, as shown in FIG. 9, the wiping is not performed in a state where the ink 41 supplied to wet the rubber blade is held on the front surface of the rubber blade 33 in the wiping direction indicated by the arrow in FIG. The rubber blade 33 is transmitted to the side of the rubber blade 33 and the like, and also wraps around the rear surface of the rubber blade 33 in the wiping direction.

  In the sample B having poor fall characteristics, the ink 42 dragged by the rubber blade 33 cannot follow the movement of the rubber blade 33 and is separated and remains on the liquid repellent layer 11B in a minute amount that cannot be visually observed. End up. As a result of drying of this small amount of ink, it is considered that a new deposit 43 is generated on the liquid repellent layer 11B after the wiping operation.

  In order to support this, in FIG. 8, the deposit 40 is confirmed in a streak shape along the wiping direction of the rubber blade indicated by the arrow. That is, the stripe-shaped deposit 40 shown in FIG. 8 is considered to correspond to the new deposit 43. On the other hand, in the sample A having good fall characteristics, the ink 41 that wraps around the rear surface in the wiping direction of the rubber blade 33 follows the movement of the rubber blade 33 and easily moves on the liquid repellent layer 11B. Therefore, it can be considered that the deposit 40 can be removed without generating a new deposit 43 after wiping.

  From the above, it has been shown that the deposit 40 can be removed by wiping on the liquid repellent layer 11B having good fall characteristics, and the fall characteristics of the nozzle plate 11 used in the inkjet head 10 which is the subject of the present invention. The importance was also confirmed.

  In the above confirmation experiment, the result of using a thermally oxidized silicon substrate as the nozzle plate base material 11A was described. However, the same fall characteristics are also obtained in the configuration of the nozzle plate 11 using a resin material such as polyimide or polypropylene for the nozzle plate base material 11A. The effect of was confirmed. Moreover, the effect of the same fall characteristic was confirmed also about the structure which provided 11 C of contact | adherence layers between the discharge surface of 11 A of nozzle plate base materials, and the liquid repellent layer 11B.

  Next, the results of observing the surface state (maximum height difference) of the liquid repellent layer 11B for each of the samples A to F are shown in FIG. The surface state is observed using an atomic force microscope (SPA400) manufactured by Seiko Instruments Inc., and the measurement range is 20 μm square. FIG. 10 is a diagram showing the relationship between the maximum height difference of samples A to F and the falling angle.

  Here, the maximum height difference is a value calculated as PV among the measurement parameters provided in the atomic force microscope, and is a difference in height between the highest point and the lowest point on the measurement range plane. In addition, the maximum height difference of the discharge surface of only the thermally oxidized silicon substrate used as the nozzle plate base material 11A in this embodiment is 0.5 nm.

  As shown in FIG. 10, there is a clear correlation between the falling angle and the maximum height difference in the liquid repellent layer 11B, and it is clear that the falling angle tends to decrease as the maximum height difference decreases.

  Therefore, the relationship between the maximum height difference in the liquid repellent layer 11B and the falling angle will be considered as follows. The maximum height difference is a difference between the maximum thickness (height) and the minimum thickness (height) with respect to the average thickness, and indicates a variation in thickness.

  First, the surface state of the liquid repellent layer 11B, which means the value of the maximum height difference, will be described. As described above, the maximum height difference of only the nozzle plate substrate 11A is 0.5 nm. For example, a case is considered where the maximum height difference of the measured nozzle plate 11 of the sample is X nm. Since the maximum height difference of only the nozzle plate base material 11A is also added to the measured value X, the variation in the thickness of the liquid repellent layer 11B itself formed on the ejection surface of the nozzle plate base material 11A is: X-0.5 to X + 0.5 nm can be estimated.

  That is, if the maximum height difference of only the nozzle plate base material 11A is known, the maximum height difference of only the nozzle plate base material 11A is measured by measuring the maximum height difference of the discharge surface of the nozzle plate 11 on which the liquid repellent layer 11B is formed. Although the thickness variation of the difference is included, it is possible to know the thickness variation of the liquid repellent layer 11B itself.

  Next, the variation in the thickness of the liquid repellent layer 11B necessary for forming the liquid repellent layer 11B having a desired drop angle is determined from the relationship between the maximum height difference of the samples A to F and the drop angle shown in FIG. Explain that an estimate can be made.

  For example, it is assumed that the value obtained by reading the value of the maximum height difference of the nozzle plate 11 when the drop angle of the ejection surface is Y ° from the graph of FIG. 10 is Xnm. The thickness variation of the liquid repellent layer 11B itself at this time can be considered to be X−0.5 to X + 0.5 nm. Therefore, in order to form the liquid repellent layer 11B having a drop angle of Y °, the drop angle Y ° can be realized if the variation in the thickness of the liquid repellent layer 11B is at least X−0.5 nm. it is conceivable that.

The plotted points shown in FIG. 10 are measured values of the maximum height difference of the nozzle plate 11, and are values including the maximum height difference of only the nozzle plate substrate 11A. FIG. 10 illustrates the maximum height difference (± 0.5 nm) of only the plate base material 11A with respect to the plot points as error bars T _{A to} T _F , so that the liquid repellent for realizing the above-described sliding angle Y °. The value of the thickness variation (X−0.5 nm) of the layer 11B corresponds to the lowest point of the error bar.

  Therefore, as shown in FIG. 10, when the thickness variation of the liquid repellent layer 11B itself is 5 nm or less, it is possible to form the liquid repellent layer 11B having a fall characteristic (fall angle <90 °). More preferably, by setting the thickness variation to 1.5 nm or less, the falling angle can be reduced to 40 ° or less, and the liquid repellent layer 11B having better falling characteristics can be formed.

  The smaller the drop angle, the greater the influence of the slight thickness variation. On the other hand, when the thickness variation is 5 nm or more, the fall characteristics are completely lost regardless of the thickness variation, and the discharge surface. Ink droplets 25 adhering to the ink no longer fall down.

  In Samples B and D that did not fall down, protrusions of 5 nm or more were observed. When such protrusions exist, it is considered that the variation in the thickness of the liquid repellent layer 11B becomes large, the surface uniformity is lost, and the fall characteristics are deteriorated.

  Therefore, after forming the nozzle plate 11 by applying the liquid repellent layer 11B or the like using a known method, the thickness variation of the liquid repellent layer 11B is measured using an atomic force microscope or the like, and the thickness variation is measured. The inkjet head 10 may be manufactured by selecting only the nozzle plate 11 having a thickness of 5 nm or 1.5 nm or less.

  In Example 1, in order to measure the maximum height difference, measurement was performed with an atomic force microscope, but measurement is also possible by cross-sectional observation using a transmission electron microscope. When a transmission electron microscope is used, it is necessary to generate a flaky observation sample. For example, a flaky shape is formed after embedding the nozzle plate substrate 11A on which the liquid repellent layer 11B is formed in an epoxy resin or the like. It can be generated by cutting out. As the cutting method, there are a focused ion beam (FIB) method, an ultramicrotome method using a diamond knife, and the like, and the user may select appropriately according to the type of the nozzle plate substrate 11A and the liquid repellent layer material.

  In Example 1, a thermally oxidized silicon substrate was used as the nozzle plate base material 11A in order to facilitate measurement of the maximum height difference of the sample. However, the present invention is not limited to this, and the thickness is 5 nm or less. If the liquid repellent layer 11B having the above variation is formed, it is possible to form the nozzle plate 11 having the same level of fall characteristics.

  As described above, by forming the thickness variation of the liquid repellent layer 11B to be 5 nm or less, it is possible to improve the fall characteristics, and to suppress the generation of new deposits 43 due to wiping, so that the wiping performance can be improved and the contact angle In addition, it is possible to maintain high discharge accuracy in the long term while maintaining adhesion. Moreover, if the thickness variation is 1.5 nm or less, the generation of deposits can be further suppressed.

  Further, the pressing pressure required for the rubber blade 33 during wiping can be reduced, and problems such as wear and scratches can be solved, so that the durability of the nozzle plate 11 against wiping can be improved.

  In this embodiment, the liquid repellent layer material is formed on the discharge surface of the nozzle plate base material, but the surface is not limited to the nozzle plate, for example, a window glass for a car, a liquid crystal display, an optical lens surface, It can also be applied to processing applications.

(Example 2)
Next, five samples of the nozzle plate 11 are formed, and the results of tests on the relationship between the average film thickness (thickness) of the liquid repellent layer 11B, liquid repellency, and falling characteristics are shown in FIG.

  Five samples of the nozzle plate 11 formed in the second embodiment use the same nozzle plate base material 11A and the liquid repellent layer material used in the first embodiment, and the same as the sample F of the first embodiment, by the vacuum evaporation method. Formed. The average thickness of the liquid repellent layer 11B in the five samples is 0.5, 1, 2, 4, 6 nm. As the five samples, those having the same variation in the thickness of the liquid repellent layer 11B were used.

When the average thickness of the liquid repellent layer 11B was 1 nm or more, the contact angle was as high as 113 ° or more, but at 0.5 nm, the contact angle was deteriorated. This is because if the thickness of the liquid repellent layer 11B is too thin, thickness variations are likely to occur, and there is a possibility that a part of the liquid repellent layer 11B does not react with the nozzle plate substrate 11A. Because.

On the other hand, the falling angle increased rapidly when the average thickness of the liquid repellent layer 11B was 4 nm or more, and the falling characteristics deteriorated. When the average thickness was 6 nm, the falling characteristics disappeared. This is because when the average thickness of the liquid repellent layer 11B is increased, the fluorinated silane coupling agents are entangled with each other, and the ratio of the CF ₃ group at the end portion with the smallest coastal surface energy covering the surface decreases. It is thought that. Further, it is considered that the siloxane (—Si—O—) network is irregularly formed and the variation in the thickness of the liquid repellent layer 11B becomes large.

On the other hand, when the average thickness of the liquid repellent layer 11B is 1 nm or less, the falling angle tends to increase. This is considered to be because the thickness of the liquid repellent layer 11B varies and there are places where the liquid repellent layer 11B does not cover a part of the nozzle plate substrate 11A.

  Even if the average thickness is 5 nm, the contact angle and the falling angle are considered to be included in an appropriate range as shown in FIG. 11, but the falling angle may exceed 90 °. 4 nm or less is considered appropriate.

  From the above results, by setting the average thickness of the liquid repellent layer 11B to 1 nm or more and 4 nm or less, the nozzle plate 11 having good liquid repellency, falling characteristics and adhesion to the nozzle plate substrate 11A is formed. be able to.

(Example 3)
Next, FIG. 12 shows the test results of the relationship between the average film thickness (thickness) of the adhesion layer 11C and the processing accuracy of the nozzle holes 12 for the nozzle plate 11 of the present invention.

Nozzle plate base material 11A uses Upilex S50 manufactured by Ube Industries, Ltd., and after washing with neutral detergent before forming the adhesion layer 11C to remove oily and dirt on the surface, no detergent components remain. What was sufficiently washed with pure water was used. Using silicon oxide (SiO ₂ ) as the adhesion layer material, four samples of the nozzle plate 11 having an average thickness of the adhesion layer 11C of 3, 5, 30, and 100 nm were formed by RF sputtering.

In addition, the liquid repellent layer 11B of each sample is formed using a vacuum evaporation method, and average thickness is 2 nm. In addition, in order to avoid variations in the thickness of the liquid repellent layer 11B of each sample in the forming step, the liquid repellent layer 11B was formed in the same batch. Therefore, the four samples have almost the same thickness variation.

After forming the liquid repellent layer 11B, a time was allowed to stand for 1 day or more in an air atmosphere, and then the nozzle hole 12 was processed using an excimer laser. The nozzle hole 12 was processed into a circular shape having a wavelength of 248 nm, an irradiation power of about 0.6 J / cm ² and a diameter of about 20 μm from the back side of the surface on which the liquid repellent layer 11B of the nozzle plate substrate 11A was formed.

  FIG. 12 shows an observation photograph around the nozzle hole 12 on the ejection surface side where the liquid repellent layer 11B of the nozzle plate 11 is formed. The observation photograph was imaged using a scanning electron microscope (SEM). 12A to 12D are observation photographs of samples with an average thickness of the adhesion layer 11C of 3, 5, 30, and 100 nm.

  As shown in FIGS. 12A to 12C, when the average thickness of the adhesion layer 11C is 3 nm to 30 nm, there is no processing unevenness in the shape of the nozzle hole 12, but FIG. As shown in the graph, when the average thickness of the adhesion layer 11C is 100 nm, it is understood that processing irregularities such as burrs are observed at the edge portion of the nozzle hole 12 and the roundness is remarkably reduced.

  This is because if the average thickness of the adhesion layer 11C made of silicon oxide is large, it is difficult to process with an excimer laser (wavelength 248 nm). Therefore, the average thickness of the adhesion layer 11C should be as thin as possible, and the nozzle hole 12 can be formed with high accuracy by setting it to 30 nm or less.

  On the other hand, when the average thickness of the adhesion layer 11C is 3 nm, there is no processing unevenness, but the adhesion layer 11C made of silicon oxide cannot completely cover the nozzle plate substrate 11A made of a polyimide film. The conditions for forming the continuous film of the adhesion layer 11C are related to the surface roughness of the nozzle plate substrate 11A. Since the surface roughness of a commercially available polyimide film is generally 3 nm or less, it is considered that a continuous film can be formed if the film thickness is 5 nm or more.

  Therefore, it can be seen that the average thickness of the adhesion layer 11C should be 5 nm or more in order to improve the falling characteristics of the ejection surface of the nozzle plate 11. By setting the average thickness of the adhesion layer 11C to 5 nm or more, the nozzle plate substrate 11A can be evenly covered with the adhesion layer 11C, so that the liquid repellent layer 11B can be evenly formed with good reproducibility.

  From the above test results, the average thickness of the adhesion layer 11C can be set to 5 nm or more and 30 nm or less in order to satisfy both the maintenance of the processing accuracy of the nozzle hole 12 and the good fall characteristics of the nozzle plate 11. desirable.

It is explanatory drawing which shows the simple structure of the inkjet apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the structure of an inkjet head. It is sectional drawing which shows the structure of a nozzle plate. It is a schematic diagram which shows the surface structure of the nozzle plate base material made liquid-repellent with the fluorine-type silane coupling agent. It is a figure which shows the measurement result of the contact angle and sliding angle in samples AF. It is a figure which shows the result of the confirmation experiment of the wiping performance by the difference in a fall angle. It is a figure which shows the result of the confirmation experiment of the wiping performance by the difference in a fall angle. It is a figure which shows the result of the confirmation experiment of the wiping performance by the difference in a fall angle. It is explanatory drawing which shows the state of the ink at the time of wiping, and a deposit | attachment. It is a figure which shows the relationship between the maximum height difference of samples AF and a fall angle. It is a figure which shows the relationship between the average thickness of a liquid repellent layer, liquid repellency (contact angle), and a fall characteristic (fall angle). It is a figure which shows the relationship between the average thickness of an adhesion layer, and the processing precision of a nozzle hole.

Explanation of symbols

10- Inkjet head 11- Nozzle plate 11A- Nozzle plate base material 11B- Liquid repellent layer 11C- Adhesion layer 12- Nozzle hole 20- Inkjet device

Claims (8)

A nozzle plate substrate having ejection holes for ejecting ink droplets from the ejection surface to the outside;
A nozzle plate comprising: a liquid repellent layer formed of a fluorine-based silane coupling agent on the discharge surface, wherein the thickness variation is 5 nm or less.   2. The nozzle plate according to claim 1, wherein the liquid repellent layer has an average thickness of 1 nm or more and 4 nm or less.   The nozzle plate according to claim 1, wherein the nozzle plate base material has an adhesion layer between the ejection surface and the liquid repellent layer.   The nozzle plate according to claim 3, wherein the adhesion layer is an inorganic oxide. The nozzle plate base material is a polymer material that absorbs ultraviolet energy,
The nozzle plate according to claim 1, wherein the discharge hole is formed using an excimer laser.   The nozzle plate according to claim 4, wherein the adhesion layer has an average thickness of 5 nm or more and 30 nm or less. A head portion having an ink chamber;
An ink jet head comprising: the nozzle plate according to claim 1, wherein the nozzle hole is bonded to the head portion in a state where the nozzle hole communicates with the ink chamber. In an inkjet apparatus that ejects ink droplets to a desired position,
An inkjet apparatus comprising the inkjet head according to claim 7.

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