JP2007210115A - Nozzle plate manufacturing method and nozzle plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nozzle plate manufacturing method whereby a nozzle plate equipped with a configuration suitable for a liquid discharge head that utilizes the electric field assisting method is manufactured easily, and to provide a nozzle plate. <P>SOLUTION: In the nozzle plate manufacturing method molding nozzles by pressing a substrate set between a first mold with projections that form an inverted shape of the nozzles and a second mold disposed oppositely to this first mold, the following is included. A film is formed on a molding surface of the first mold, and the substrate is held in the second mold. The held substrate is heated, and the first mold with the film formed is heated. While the substrate and the first mold are heated, the molding surface where the film of the first mold is formed is pressed against the substrate held in the second mold, thereby molding the nozzles in the substrate and also transferring the film to the substrate. The substrate is cooled while pressed. The second mold is released from the substrate. Liquid repellency processing is carried out to the surface of the substrate where the second mold is released. The substrate is released from the first mold. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nozzle plate manufacturing method and a nozzle plate.

  In recent years, with the progress of high-definition image quality in inkjet recording methods and the expansion of the application range in industrial applications, there is an increasing demand for fine pattern formation and high-viscosity ink ejection.

  In order to solve these demands with the conventional ink jet recording method, it is necessary to improve the liquid discharge force by reducing the size of the nozzles and discharging high viscosity ink, and accordingly, the drive voltage for discharging the ink is increased. As a result, the cost of the head and device becomes very expensive, and a device suitable for practical use has not been realized.

  Therefore, in response to the above requirements, as a technique for discharging not only low-viscosity but also high-viscosity droplets from a miniaturized nozzle, the liquid in the nozzle is charged, and the nozzle and droplets are subjected to landing. There is known a so-called electrostatic suction type droplet discharge technique in which discharge is performed by an electrostatic suction force received from an electric field formed between various base materials (see Patent Document 1).

  However, when using a liquid discharge head with a flat droplet discharge surface in the electrostatic suction type droplet discharge technology, the degree of electric field concentration on the liquid in the nozzle and the meniscus of the discharge hole is small, and the required electrostatic suction In order to obtain force, it was necessary to apply a very high voltage as a voltage applied between the liquid discharge head and the substrate.

  Therefore, using a flat liquid discharge head, this electrostatic attraction type droplet discharge technology is combined with a technology that discharges droplets using pressure generated by deformation of the piezo element or generation of bubbles inside the liquid. By generating the pressure described above, the liquid meniscus is raised at the nozzle discharge hole, and the electric field is selectively concentrated on the raised meniscus to increase the electrostatic attraction force. Development of a droplet discharge device that uses a so-called electric field assist method for forming and discharging the liquid is progressing (see, for example, Patent Documents 2 to 5).

  In order to discharge droplets using this electric field assist method, it is essential to charge the liquid in the nozzle. Therefore, a highly reliable electrode that contacts the liquid on the inner peripheral surface of the nozzle is efficient. It is important to provide it well. As a technology to form a uniform conductive film on the inner peripheral surface of a minute hole like this nozzle to make an electrode, in the dry process, a method mainly using a wraparound effect when forming a metal material by sputtering or ion plating Further, there is known a vacuum deposition method in which a substrate to be processed is disposed obliquely with respect to an evaporation source and further rotated. In the wet process, plating is known.

  In addition, when the liquid repellency of the surface of the nozzle where the liquid is discharged is insufficient, the liquid droplets are likely to adhere to the surface of the nozzle. In particular, in the electric field assist method, the liquid meniscus formed in the discharge hole portion of the nozzle spreads on the discharge surface around the discharge hole, so that the electric field concentration on the tip of the meniscus is not effectively performed. This results in recording failure. Therefore, in order to effectively eject droplets using the electric field assist method, it is more strongly demanded that the nozzle surface has sufficient liquid repellency.

As a method of providing a liquid repellent layer on the ejection surface, in addition to vacuum deposition, spin coating, spray coating, brush coating, etc., for example, ink with a conductive film formed on a conductive material or non-conductive material is ejected. There is a method of providing a liquid repellent layer made of a fluorine-based resin on the nozzle to be formed by electrolytic polymerization (see, for example, Patent Document 6).
WO03 / 070381 pamphlet JP-A-5-104725 JP-A-5-278212 JP-A-6-134992 JP 2003-53977 A JP-A-5-330060

  However, regarding the provision of a conductive film on the inner peripheral surface of the nozzle, the metal material is mainly formed by a sputtering method or ion plating method due to the wraparound effect and the substrate to be processed is disposed obliquely with respect to the evaporation source. Furthermore, in the dry process such as rotating vacuum deposition method and the wet process technique such as plating, the smaller the opening diameter of the nozzle discharge hole, the more difficult it is to obtain a conductive film on the inner peripheral surface of the nozzle. In particular, the nozzle tip could not be provided with a sufficiently conductive film. There was also a problem with the adhesion of the conductive film.

  In recent years, since a great advantage that direct patterning is possible on a substrate or the like occurs, industrial patterning applications using an ink jet recording method are widely considered. For example, in the case of conducting conductive patterning on a substrate, it is desired to increase the definition so that the landing diameter is 30 μm or less, and in order to meet this demand, the diameter of the ink droplets ejected from the recording head is approximately It is supposed to be 15 μm or less. Accordingly, it is sufficiently predicted that the demand for smaller nozzle apertures will become stronger in the future, and it is predicted that it will be more difficult to obtain a sufficiently conductive film on the inner peripheral surface of the nozzle.

  In addition, regarding the provision of the liquid repellent layer on the surface of the nozzle discharge hole, when the liquid repellent layer is provided by vacuum deposition, spin coating, spray coating, or brushing, the liquid repellent layer is formed up to the inside of the nozzle. In addition to changing the shape, the liquid repellent effect makes it difficult for the liquid to enter the nozzle, and as a result, there is a problem that the liquid cannot be sufficiently discharged.

  Further, in the method of providing a liquid repellent layer made of a fluororesin described in Patent Document 6 on the surface of a nozzle plate from which ink is ejected by an electrolytic polymerization method, a masking tape is attached to the back surface of the nozzle plate. However, there is no description about suppressing the formation of the liquid repellent layer inside the nozzle. The effect of suppressing the formation of the liquid repellent layer by the masking tape is expected to be sufficient on the back surface of the nozzle plate, but on the inner side of the nozzle, the smaller the nozzle opening diameter, the more difficult the suppression effect becomes Fully predicted. Therefore, when the nozzle opening diameter is fine, a liquid repellent layer is formed up to the inside of the nozzle, not only changing the shape of the nozzle, but also the liquid repellent effect makes it difficult for the liquid to enter the nozzle, so that the liquid can be discharged sufficiently. It is fully anticipated that problems will become impossible.

  The present invention has been made in view of the above problems, and an object of the present invention is to easily manufacture a nozzle plate having a configuration suitable for use in a liquid discharge head using an electric field assist method. And a nozzle plate manufactured by the manufacturing method.

  Said subject is solved by the following structures.

1. A substrate provided between a first mold having a projection having a reversal shape of a nozzle for discharging liquid as droplets from the discharge hole and a second mold provided to face the first mold. In a nozzle plate manufacturing method for manufacturing a nozzle plate by pressing and forming the nozzle in the thickness direction of the substrate,
A film forming step for providing a film on the molding surface of the first mold;
A holding step for holding the substrate in the second mold;
A first heating step for heating the held substrate;
A second heating step for heating the first mold provided with the film;
In a state where the substrate and the first mold are heated, the molding surface on which the film of the first mold is provided is pressed on the substrate held by the second mold. A pressing step for forming the nozzle on the substrate and transferring the film,
A cooling step for cooling the substrate while being held by the second mold and being pressed by the first mold;
A first release step for releasing the second mold from the substrate;
A liquid repellent treatment step for performing a liquid repellent treatment on the surface of the substrate from which the second mold has been released;
And a mold release step for releasing the substrate from the first mold.

  2. The nozzle plate manufacturing method according to 1, wherein the temperature of the first mold in the film forming step is lower than the temperature of the first mold in the pressing step.

  3. 3. The nozzle plate manufacturing method according to 1 or 2, wherein the film is a metal film.

  4). 3. The nozzle plate manufacturing method according to 1 or 2, wherein the film is a hydrophilic film.

  5. A nozzle plate manufactured by the nozzle plate manufacturing method according to any one of 1 to 4.

6). A substrate provided between a first mold having a projection having a reversal shape of a nozzle for discharging liquid as droplets from the discharge hole and a second mold provided to face the first mold. In a nozzle plate manufacturing method for manufacturing a nozzle plate by pressing and forming the nozzle in the thickness direction of the substrate,
A film forming step for providing a film on the molding surface of the first mold;
A holding step for holding the substrate in the second mold;
A first heating step for heating the held substrate;
A second heating step for heating the first mold provided with the film;
In a state where the substrate and the first mold are heated, the molding surface on which the film of the first mold is provided is pressed on the substrate held by the second mold. A pressing step for forming the nozzle on the substrate and transferring the film,
A cooling step for cooling the substrate while being held by the second mold and being pressed by the first mold;
And a mold release step for releasing the substrate from the first mold.

  7). The nozzle plate manufacturing method according to 6, wherein the temperature of the first mold in the film forming step is lower than the temperature of the first mold in the pressing step.

  8). The nozzle plate manufacturing method according to 6 or 7, wherein the film is a metal film.

  9. 8. The nozzle plate manufacturing method according to 6 or 7, wherein the film is a hydrophilic film.

10. A substrate provided between a first mold having a projection having a reversal shape of a nozzle for discharging liquid as droplets from the discharge hole and a second mold provided to face the first mold. In a nozzle plate manufacturing method for manufacturing a nozzle plate by pressing and forming the nozzle in the thickness direction of the substrate,
A holding step for holding the substrate in the second mold;
A first heating step for heating the held substrate;
A second heating step for heating the first mold;
A pressing step for pressing the first mold onto the substrate held by the second mold while the substrate and the first mold are heated;
A cooling step for cooling the substrate while being held by the second mold and being pressed by the first mold;
A first release step for releasing the second mold from the substrate;
A liquid repellent treatment step for performing a liquid repellent treatment on the surface of the substrate from which the second mold has been released;
And a second release step for releasing the substrate from the first mold. A method for manufacturing a nozzle plate, comprising:

  11. A nozzle plate manufactured by the nozzle plate manufacturing method according to any one of 6 to 10.

  According to invention of Claim 1, there exist the following effects. By pressing a first mold that forms a nozzle having a film on the molding surface onto a substrate that becomes a nozzle plate held by the second mold, the nozzle is molded on the substrate and the first is simultaneously formed. The film provided on the molding surface of the mold is transferred to the substrate.

  In addition, the first mold is in a state where the nozzle is formed on the substrate, and the second mold is in a state where the projection of the first mold for forming the nozzle without gap is present in the nozzle. Since the liquid repellent process is performed on the discharge surface which is the surface of the separated substrate, the liquid repellent process is performed on the discharge surface without being performed inside the nozzle.

  Therefore, when the first mold is released from the substrate, the film is transferred to the inner peripheral surface of the nozzle as well as the release surface of the substrate, and the shape of the nozzle is the discharge surface. The projection shape of the first mold including the ejection holes existing in the nozzle is transferred as it is, and a nozzle plate having a water repellent treatment on the ejection surface is obtained.

  Accordingly, since the liquid to be ejected does not easily adhere to the ejection surface and does not spread on the ejection surface, the liquid droplet can be ejected stably, and the electric field concentration at the meniscus tip is effective. Therefore, it is possible to provide a nozzle plate manufacturing method in which a nozzle plate that can be used for the electric field assist method can be easily manufactured.

  Also, it is possible to provide a nozzle plate manufacturing method in which a nozzle plate that is easy to introduce a liquid discharged to the nozzle can be easily manufactured if the film sufficiently provided on the inner peripheral surface of the nozzle and the subsequent surface is a hydrophilic film. Can do. In addition, if this film is a metal film, a nozzle plate that can be easily provided with an electrode for charging a discharged liquid suitable for use in a liquid discharge head using an electric field assist method can be easily manufactured. A manufacturing method can be provided.

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 1, the film provided on the molding surface of the first mold is more strongly transferred to the substrate. The nozzle plate manufactured by the nozzle plate manufacturing method which can be provided can be provided.

  According to the invention described in claim 6, by pressing the first mold that forms the nozzle provided with the film on the molding surface onto the substrate that becomes the nozzle plate held by the second mold, As soon as the nozzle is formed on the substrate, the film provided on the molding surface of the first mold is transferred to the substrate. Next, the first mold is released from the substrate with the film remaining on the substrate, so that the film is transferred to the inner peripheral surface of the nozzle as well as the release surface of the substrate. As for the nozzle shape, a nozzle plate is obtained in which the projection shape of the first mold including the discharge holes is transferred as it is.

  Therefore, it is possible to provide a nozzle plate manufacturing method in which a nozzle plate having a film sufficiently provided on the inner peripheral surface of the nozzle and the subsequent surface can be easily manufactured.

  If the above-described film is a hydrophilic film, a nozzle plate manufacturing method can be provided in which a nozzle plate in which liquid discharged to the nozzle is easily introduced can be easily manufactured. Further, if the film is a metal film, a nozzle plate manufacturing method for easily manufacturing a nozzle plate that can include an electrode for charging a discharge liquid suitable for use in a liquid discharge head using an electric field assist method. Can be provided.

  According to the tenth aspect of the present invention, there is a protrusion of the first mold for forming the nozzle without a gap in the nozzle, in which the first mold is in a state where the nozzle is formed on the substrate. In this state, the liquid repellent treatment is not performed on the inside of the nozzle because the liquid repellent treatment is performed on the ejection surface, which is the surface of the substrate away from the second mold. Further, by releasing the first mold, a nozzle plate in which the projection shape of the first mold is transferred as it is without deformation of the discharge holes present on the discharge surface by the liquid repellent layer is obtained. It will be.

  Accordingly, since the liquid to be ejected does not easily adhere to the ejection surface and does not spread on the ejection surface, the liquid droplet can be ejected stably, and the electric field concentration at the meniscus tip is effective. Therefore, it is possible to provide a nozzle plate manufacturing method in which a nozzle plate that can be used for the electric field assist method can be easily manufactured.

  According to the eleventh aspect of the present invention, in addition to the effects of the above-described sixth and tenth aspects, the film provided on the molding surface of the first mold is more firmly transferred to the substrate. The nozzle plate manufactured by the nozzle plate manufacturing method which can be provided can be provided.

  Hereinafter, a liquid discharge head having a nozzle plate according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating an overall configuration of a liquid ejection apparatus 1 that uses a liquid ejection head 2 (cross-sectional view) having a nozzle plate 11 as an example of the present embodiment and uses an electric field assist method. The liquid discharge head 2 can be applied to various liquid discharge devices such as a so-called serial method or line method.

  The liquid ejecting apparatus 1 includes a liquid ejecting head 2 on which a nozzle 10 for ejecting a droplet D of a chargeable liquid L such as ink is formed, an operation control unit 4, and an opposing surface facing the nozzle 10 of the liquid ejecting head 2. And a counter electrode 3 that has a surface and supports a substrate K that receives the landing of the droplet D on the opposite surface.

  A nozzle plate 11 having a plurality of nozzles 10 is provided on the side of the liquid ejection head 2 facing the counter electrode 3. The liquid discharge head 2 is configured as a head having a flat discharge surface in which the nozzle 10 does not protrude from the discharge surface 12 facing the counter electrode 3 of the nozzle plate 11 or the nozzle 10 protrudes only about 30 μm.

  Each nozzle 10 is formed by being drilled in a nozzle plate 11, and is a through-hole having a discharge hole 13 on a discharge surface 12 of the nozzle plate 11. The nozzle 10 may have a polygonal shape, a star shape, or the like instead of being formed into a circle in cross-sectional shape. The nozzle diameter indicates the diameter of the discharge hole 13 of the nozzle 10. When the opening shape of the discharge hole is not a circle, the opening area of the target opening surface is replaced with a circle having the same area as described above. The diameter in case

  The nozzle plate 11 is preferably formed from glass (hereinafter referred to as high resistance glass) or resin (hereinafter referred to as high resistance resin) having a high volume resistivity described later. A detailed description of the nozzle plate 11 will be described later together with the charging electrode 16 and the liquid repellent layer 28 described later.

  The inner peripheral surface 17 of the nozzle 10 of the nozzle plate 11 is made of, for example, a conductive material such as nickel (Ni), and is charged by applying a voltage to the liquid L in the nozzle 10 to generate an electrostatic attraction force described later. A charging electrode 16 serving as an electrostatic voltage applying means is provided. The charging electrode 16 is in contact with the liquid L in the nozzle.

  The charging electrode 16 is connected to an electrostatic voltage power source 18, and when an electrostatic voltage is applied from the electrostatic voltage power source 18 to the charging electrode 16, the liquid L in all the nozzles 10 is simultaneously charged, An electrostatic attraction force is generated between the liquid discharge head 2 and the counter electrode 3, particularly between the liquid L and the substrate K.

  A substantially cylindrical space having an inner diameter larger than the opening of the nozzle 10 is formed in a portion of the body plate 19 facing the opening end of each nozzle 10 on the opposite side of the surface in which the nozzle plate 11 is provided with the discharge holes. Each space is a cavity 20 for temporarily storing the liquid L to be discharged.

  The body plate 19 is provided with a flow path (not shown) for supplying the liquid L to the cavity 20. For example, a cavity 20, a common channel, and a channel connecting the common channel and the cavity 20 are provided by using a known photolithography process (resist application, exposure, development) and an etching method using a Si substrate as a base material. In addition, a supply pipe (not shown) for supplying the liquid L from an external liquid tank (not shown) is connected to the common flow path, and a differential pressure due to a supply pump (not shown) provided in the supply pipe or due to the arrangement position of the liquid tank Thus, a predetermined supply pressure is applied to the liquid L such as the flow path, the cavity 20 and the nozzle 10. Further, the bottom of the cavity 20 is formed as thin as about 20 μm and can be deformed so as to generate pressure on the liquid L.

  Piezo elements 22 that are piezoelectric element actuators as pressure generating means are provided on the back surface of the bottom of each cavity 20, and the piezoelectric elements 22 are used for applying a driving voltage to the elements to deform the elements. A drive voltage power supply 23 is connected. The piezo element 22 is deformed by the application of a drive voltage from the drive voltage power source 23 to generate a pressure on the liquid L in the nozzle, thereby forming a meniscus of the liquid L in the discharge hole 13 of the nozzle 10. . In addition to the piezoelectric element actuator as in the present embodiment, for example, an electrostatic actuator, a thermal method, or the like can be adopted as the pressure generating means.

  The drive voltage power supply 23 and the electrostatic voltage power supply 18 that applies an electrostatic voltage to the charging electrode 16 are connected to the operation control means 4, respectively, and are controlled by the operation control means 4.

  A liquid repellent layer 28 is provided on the ejection surface 12 of the nozzle plate 11. By providing the liquid repellent layer 28, the liquid L is prevented from seeping out from the discharge hole 13, and the liquid meniscus formed in the discharge hole 13 portion of the nozzle 10 is difficult to spread on the discharge surface around the discharge hole 13. As a result, it is possible to effectively prevent a reduction in electric field concentration at the meniscus tip.

  Next, the operation control means 4 is composed of a computer in which a CPU 25, a ROM 26, a RAM 27, etc. are connected by a BUS (not shown). The CPU 25 is based on a power control program stored in the ROM 26. 18 and each drive voltage power supply 23 are driven to discharge the liquid L from the discharge hole 13 of the nozzle 10.

  In the liquid discharge direction of the liquid L of the liquid discharge head 2, a flat counter electrode 3 that supports the substrate K is disposed in parallel to the discharge surface 12 of the liquid discharge head 2 at a predetermined distance. The predetermined distance between the counter electrode 3 and the liquid ejection head 2 is appropriately set within a range of about 0.1 to 3 mm.

  In the liquid ejection device 1, the counter electrode 3 is grounded and is always maintained at the ground potential. Therefore, when an electrostatic voltage is applied from the electrostatic voltage power source 18 to the charging electrode 16, an electric field is generated between the liquid L in the ejection hole 13 of the nozzle 10 and the opposing surface of the counter electrode 3 facing the liquid ejection head 2. Has come to occur. When the charged droplet D lands on the substrate K, the counter electrode 3 releases the electric charge by grounding.

  The counter electrode 3 or the liquid ejection head 2 is provided with positioning means (not shown) for positioning the liquid ejection head 2 and the substrate K by relatively moving them. The droplets D discharged from each nozzle 10 can be landed on the surface of the substrate K at an arbitrary position.

  As the liquid L to be discharged by the liquid discharge apparatus 1, for example, an inorganic liquid, an organic liquid, or a conductive paste containing a large amount of a substance having high electrical conductivity (such as silver powder) can be used. When the paste is discharged as the liquid L, the above-described substances such as silver powder dissolved or dispersed in the liquid L are not particularly limited, except for coarse particles that cause clogging at the nozzle 10.

  Here, the nozzle plate 11 described above will be described in detail below. The nozzle plate 11 is manufactured by punching a thin plate by press molding. FIG. 2 shows an upper mold 201 as a first mold and a lower mold 207 as a second mold. The process of manufacturing the nozzle plate 11 (FIG. 2 (g) 205b) by press-molding the thin plate 205, which is a substrate, is schematically shown, and will be described below.

  FIG. 2A shows an upper mold 201 for punching a thin plate. The upper mold 201 is provided with a plurality of projections 201a for forming nozzles in a planar shape. The material of the mold is not particularly limited as long as it can be used without reacting with the thin plate material at the above-mentioned heating temperature because it is necessary to heat and soften the resin or glass which is a thin plate material to be described later. For example, stainless steel, silicon carbide, carbon, nickel, cemented carbide, tungsten carbide and the like are not limited.

  Next, as shown in FIG. 2B, a metal film 203 is provided on the molding surface of the upper mold 201. The metal film 203 becomes the charging electrode 203a in the nozzle plate 205b, and the metal film 203 is made of an electrode such as aluminum, nickel, silver, gold, platinum, palladium, titanium, or carbon. Examples include conductive materials. These conductive materials are not particularly limited as long as materials that do not cause corrosion or the like due to the discharged liquid are appropriately selected.

  The film forming method on the molding surface of the upper mold 201 is most preferably a sputtering method that excels in forming a dense film, but is not limited thereto, and may be, for example, a vacuum evaporation method. The film thickness to be formed may be about 0.1 μm to 1 μm. Here, the metal film 203 formed on the upper mold 201 is required to be easily peeled off from the upper mold 201 when the upper mold 201 described later and a thin plate serving as a nozzle plate are released. In general, the cleaning process (also referred to as a surface activation process) by reverse sputtering or the like, which is generally performed so that the film is not easily peeled off from the film forming material, is not performed on the surface of the upper mold 201 that is the film forming surface. Is preferred. Further, the temperature of the upper mold 201 when the metal film 203 is provided is preferably lower than the molding temperature of a thin plate at the time of press molding, which will be described later. For example, film formation without heating is preferable. It will be described later.

  Next, as shown in FIG. 2C, a thin plate 205 to be the nozzle plate 205b is provided on the lower mold 207. The material of the lower mold 207 may be the same as that shown as the material of the upper mold 201 described above, as long as it can be used at a temperature higher than the molding temperature of the resin or glass that is the material of the thin plate 205 described later, It is not particularly limited, and examples thereof include stainless steel, silicon carbide, carbon, nickel, cemented carbide and tungsten carbide. The thin plate 205 has a thickness of about 30 μm to 300 μm, and as a preferable material, high resistance glass having a high volume resistivity may be appropriately selected from, for example, quartz, synthetic quartz, lanthanum silica flint glass, borosilicate glass, etc. Examples of the high-resistance resin having a high volume resistivity include PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PI (polyimide), and the like.

  The thin plate 205 is placed on the lower mold 207 described above, and the thin plate 205 is soft and the shape is maintained to such an extent that the projection 201a forming the nozzle of the upper mold 201 can easily enter the thin plate 205. To a temperature (hereinafter referred to as a molding temperature). The molding temperature may be determined by a molding experiment or the like with reference to the temperature of the softening point of the material to be the thin plate 205. For example, polyethylene terephthalate (PET) is about 80 ° C., and borosilicate glass is 400 ° C. depending on the components. It is about 700 ° C. The heating method is not particularly limited. For example, a method of circulating water, oil, or steam inside the lower mold 207, a resistance heating method, a light heating method, a high frequency induction heating method, or the like can be used. What is necessary is just to select suitably by required shaping | molding temperature etc.

  When the molding temperature is high, the mold may be deteriorated due to oxidation or the like. For example, when a thin plate 205 made of borosilicate glass is formed using a die made of silicon carbide, the forming temperature needs to be about 700 ° C. If this heating is performed in air, the die Deterioration may progress. In order to prevent this deterioration, it is preferable to perform heating and shaping in a heated state in an atmosphere of an inert gas such as argon gas or nitrogen gas.

  When the thin plate 205 is heated to the above-described molding temperature, as shown in FIG. 2D, a plurality of projections 201a forming nozzles provided on the upper mold 201 can be easily formed. Can invade. Here, it is preferable that the heating temperature of the upper mold 201 when the metal film 203 described above is provided be lower than the molding temperature of the thin plate 205a at the time of press molding. By doing so, it is possible to easily transfer the metal film 203 firmly by the thin plate 205a during press molding.

  In addition, when the temperature of the upper mold 201 is lowered to press the thin plate 205 and touches the thin plate 205, the tip of the projection forming the nozzle having a small heat capacity is cooled, which makes molding difficult. It is preferable to set the temperature so that the mold 201 is not fused to the thin plate 205. When the thin plate 205 has a melting temperature, the temperature at which the thin plate 205 has a melting temperature is preferably about 50 to 100 ° C. lower than the melting temperature, and when the thin plate 205 does not have a clear melting temperature, it may be determined by experiment. good. Also, the heating method is not particularly limited, and the same as described above, for example, a method of circulating water, oil or steam inside the upper mold 201, a resistance heating method, a light heating method, high frequency induction heating A method or the like may be appropriately selected depending on the material of the thin plate 205, a necessary molding temperature, and the like.

  Next, the thin plate 205 is press-molded by the upper mold 201 and the lower mold 207 to form a thin plate 205a with a nozzle perforated. In this state, the thin plate 205a is cooled to a temperature convenient for performing the liquid repellent treatment described later. The cooling temperature is preferably about room temperature to about 80 ° C. when the liquid repellent treatment uses a vapor deposition method, and about room temperature to about 40 ° C. when coating with an organic solvent. Moreover, when removing the thin plate 205a from a metal mold | die, it is preferable to set it as room temperature to about 40 degreeC from a viewpoint of handling.

  Next, as shown in FIG. 2 (e), the lower mold 207 is released and retracted, and then, as shown in FIG. 2 (f), the lower mold 207 of the thin plate 205a is removed from the surface. A liquid repellent treatment for providing the liquid repellent layer 209 is performed.

  For the liquid repellent layer 209, for example, a material having water repellency is used when the liquid L is aqueous, and a material having oil repellency is used when the liquid L is oily. For example, FEP (ethylene tetrafluoride · 6 fluorine) is used. Propylene fluoride), PTFE (polytetrafluoroethylene), fluorosiloxane, fluoroalkylsilane, amorphous perfluororesin, and the like. The formation method of the liquid repellent layer 209 is not particularly limited, and may be appropriately selected from coating, vapor deposition, and the like according to the material of the liquid repellent layer 209. The liquid repellent layer 209 may be formed directly on the surface from which the lower mold 207 is released, or may be formed via an intermediate layer in order to improve the adhesion of the liquid repellent layer 209. .

  As shown in FIG. 2 (f), the state after the liquid repellent treatment is that the projection 201a that forms the nozzle of the upper mold 201 is still present in the molded nozzle portion without any gaps. Regardless of the method of providing the layer 209, the liquid repellent material does not enter the nozzle provided in the thin plate 205a. Therefore, the nozzle shape is not changed, and there is no problem that it becomes difficult for the ejected liquid to enter the nozzle due to the formation of the liquid repellent layer in the nozzle.

  Next, the nozzle plate 205b is obtained by releasing the thin plate 205a from the upper mold 201 by holding the thin plate 205a by vacuum suction, for example. At this time, the metal film 203 can be easily separated from the upper mold 201 and transferred to the thin plate 205b. Therefore, the metal plate 203a is provided on the inner peripheral surface of the nozzle 210 from which the upper mold 201 is separated and the subsequent surface of the thin plate 205b serving as the nozzle plate. Further, the metal film at the tip of the protrusion 201a forming the nozzle of the upper mold 201 remains on the upper mold 201 as there is no member to be transferred, and the repellent formed on the metal film is left as it is. Since the liquid layer is fixed to the metal film, it remains on the metal film as it is.

  Therefore, as shown in FIG. 2G, the metal film 203a is provided on the surface of the nozzle plate 205b on the upper mold 201 side and the inner peripheral surface of the nozzle 210, and the liquid repellent layer is provided on the opposite surface. Thus, the nozzle 210 can obtain the desired nozzle plate 205b in which the shape of the protrusion 201a is transferred and the opening shape of the nozzle 210 is not affected by the liquid repellent layer 209a.

The inventors configured the electric field strength of the electric field between the electrodes to be a practical value of 1.5 kV / mm using the liquid discharge experimental apparatus S ′ shown in FIG. In experiments conducted by forming the nozzle plate 11 ′ and based on the following experimental conditions, there were cases where the droplet D ′ was ejected from the nozzle 10 ′ and was not ejected.
[Experimental conditions]
Distance between discharge surface 12 'of nozzle plate 11' and facing surface of counter electrode 3 ': 1.0 mm
Nozzle plate 11 'thickness: 125 μm
Nozzle diameter: 10 μm
Electrostatic voltage: 1.5 kV
Drive voltage: 20V
The nozzle 10 ′ of the experimental liquid discharge head A ′ used in the liquid discharge experiment has a taper angle of 4 °. The taper angle indicates an angle that spreads in a direction away from the discharge surface 12 ′ from a perpendicular to the discharge surface 12 ′ in the cross section of the nozzle 10 ′. The taper angle has a small influence on the ejection, and it is obtained from simulations described later that the dependence on the conditions for ejecting the droplets stably is not large.

  Here, the principle of liquid ejection in the liquid ejection head will be described with reference to FIG. In the experimental liquid ejection head A ′, an electrostatic voltage is applied from the electrostatic voltage power source 63 ′ to the charging electrode 16 ′ as electrostatic voltage application means, and is opposed to the liquid L ′ in the ejection hole 13 ′ of the nozzle 10 ′. An electric field is generated between the facing surface of the electrode 3 ′ facing the experimental liquid ejection head A ′. Further, a driving voltage is applied from the driving voltage power supply 61 ′ to the piezoelectric element 22 ′ as pressure generating means to deform the piezoelectric element 22 ′, and thereby the discharge hole 13 ′ of the nozzle 10 ′ is generated by the pressure generated in the liquid L ′. To form a meniscus of liquid L ′.

  When the insulating property of the nozzle 10 'increases, as shown by the equipotential lines by simulation in FIG. 4, equipotential lines are arranged in the nozzle 10' in a direction substantially perpendicular to the ejection surface 12 ', and the liquid L A strong electric field is generated toward the meniscus portion.

  In particular, as can be seen from the fact that the equipotential lines are dense at the tip of the meniscus in FIG. 4, a very strong electric field concentration occurs at the tip of the meniscus. For this reason, the meniscus is torn off by the electrostatic force of the electric field and separated from the liquid L ′ in the nozzle to form a droplet D ′. Further, the droplet D ′ is accelerated by the electrostatic force, and is attracted and landed on the base material K ′ supported by the counter electrode 3 ′. At that time, since the droplet D 'attempts to land closer by the action of electrostatic force, the angle at the time of landing on the substrate K' is stabilized and accurately performed.

  As described above, if the discharge principle of the liquid L ′ in the experimental liquid discharge head A ′ is used, the experimental liquid discharge head A ′ having a flat discharge surface also uses the nozzle 10 ′ portion having high insulation. By generating a potential difference in the vertical direction with respect to the discharge surface 12 ′, strong electric field concentration can be generated, and an accurate and stable discharge state of the liquid L ′ can be formed.

In the experiment using the liquid discharge experimental device S ′, the electric field strength at the tip of the meniscus was obtained for all cases where the droplet D ′ was stably discharged from the nozzle. Actually, since it is difficult to directly measure the electric field strength at the tip of the meniscus, the electric field simulation software “PHOTO-VOLT” (trade name, manufactured by Photon Co., Ltd.) was used for calculation. The electric field strength here refers to the electric field strength 300 seconds after voltage application in the current distribution analysis mode. As a result, in all cases, the electric field strength at the meniscus tip was 1.5 × 10 ⁷ V / m or more. In this experiment, even when the droplet D ′ was not stably ejected from the nozzle, the electric field strength at the meniscus tip was calculated by the same simulation as described above. As a result, it was less than 1.5 × 10 ⁷ V / m.

  Further, as a result of calculating the electric field strength at the meniscus tip by inputting the same parameters as the above experimental conditions into the software, the electric field strength is the volume resistance of the insulator used for the nozzle plate 11 ′ as shown in FIG. It turned out to be strongly dependent on the rate.

  Theoretically, if the electrostatic voltage is increased, the droplet D 'may be ejected from the nozzle 10'. When the electrostatic voltage is increased, it is not preferable to increase the electrostatic voltage because the base material K ′ may be damaged due to the occurrence of sparks between the electrodes.

Therefore, in the liquid discharge head 2 shown in FIG. 1, the nozzle plate 11 is made of a resin or glass having a high volume resistivity that makes it easy for the electric field strength at the meniscus tip to be 1.5 × 10 ⁷ V / m or more. It is more preferable that the volume resistivity be 10 ¹⁵ Ω · m or more so that the electric field strength at the meniscus tip is 1.5 × 10 ⁷ V / m or more.

In the nozzle plate 11 using such resin or glass having a high volume resistivity, an electric field at the tip of the meniscus of the droplet formed in the discharge hole 13 is applied by applying an electrostatic voltage within a practical range. The strength can be easily increased to 1.5 × 10 ⁷ V / m or more, and the liquid can be discharged stably.

  In addition, when the resin of the nozzle plate 11 absorbs a conductive liquid, the electrical conductivity of the nozzle plate 11 increases, and as a result, the volume resistivity may decrease. In such a case, a liquid absorption preventing layer may be provided on the surface of the nozzle plate 11 that contacts the liquid to be discharged.

  Further, when the nozzle plate 11 is thin, it is necessary to compensate for the insufficient strength due to the thinness. For example, as shown in FIG. 6 showing a part of the liquid discharge head, a hole having a diameter larger than the nozzle diameter is provided. The auxiliary plate 25 may be bonded to the nozzle plate 11 to form a laminated structure. The material of the auxiliary plate 25 is preferably a material having the same volume resistivity as that of the nozzle plate 11. The method for manufacturing the auxiliary plate 25 is not particularly limited. For example, a known molding method may be used for resin, and a known photolithography process (resist application, exposure, development) and dry etching are used for glass. Examples include technology.

In a liquid discharge head that does not use the electric field assist method, the metal film 203 described above can be a hydrophilic film. By using the hydrophilic film, it is possible to easily introduce the liquid to be discharged into the nozzle, and it is possible to easily ensure stable discharge by uniform wetting of the liquid to be discharged from the opening of the nozzle. The hydrophilic film formed on the upper mold 201 is not particularly limited, and examples thereof include an oxide film such as SiO ₂ . The method for forming the hydrophilic film is not particularly limited. For example, a known sputtering method or vacuum deposition method can be used, and the film thickness is 0.05 μm or more from the island structure. The upper limit is not particularly limited, but is preferably about 5 μm practically, and more preferably from 0.1 μm to 2 μm from the viewpoint of ease of production.

  The following embodiment will be described with reference to FIG.

Example 1
An upper mold 201 made of stainless steel 304 (a shape in which 128 protrusions having a diameter of 10 μm and a height of 0.1 mm are arranged on a plane and arranged at a pitch of 50 μm. The thickness of the surface of FIG. A nickel film 203 having a thickness of 3 μm was formed (FIG. 2B). At this time, the surface activation treatment of the surface of the upper mold 201 was not performed. In addition, the temperature of the upper mold 201 at the time of film formation was set to about the same as room temperature by performing film formation without heating.

  Next, a thin plate 205 made of polyethylene terephthalate (PET) having a thickness of 0.1 mm is placed on a lower mold 207 made of stainless steel 304, and a thin plate is formed with a heater provided inside the lower mold 207. 205 was heated to about 80 ° C. to be softened (FIG. 2C). This molding temperature was determined by experiment with reference to the softening point of PET which is a material of the thin plate 205. The temperature of the upper mold 201 was set to about 100 ° C. by the same method as that for the lower mold 207.

  Next, perforation was performed by press-molding the thin plate 205 using the upper mold 201 (FIG. 2D). In this state, after cooling the thin plate 205 to about 30 ° C., the lower mold 207 was released (FIG. 2E).

  Next, a Teflon (registered trademark) water-repellent organic solvent “Fluorosurf” is spray-applied to the surface on which the lower mold 207 of the thin plate 205 is released, and dried at 120 ° C. for 30 minutes. 209 is provided (FIG. 2 (f)). After that, the nozzle plate 205b was released from the upper mold 201 by vacuum suction so that the nozzle plate 205b was held and no force in the direction perpendicular to the protrusion 201a of the upper mold 201 was applied (FIG. 2 (g)).

  As a result, the nickel film 203 formed on the upper mold 201 can be transferred to the thin plate 205 and used as a charging electrode. Further, a liquid repellent layer made of “fluorosurf” is formed on the opposite surface of the nozzle plate 205b without entering the inside of the nozzle.

  Next, a body plate was manufactured. Using a silicon substrate, by using a known photolithography process (resist coating, exposure, development) and anisotropic dry etching technology, a plurality of concave portions that respectively communicate with the nozzle, and a plurality of recesses that respectively communicate with the cavity. An ink supply groove serving as an ink supply path, a common ink chamber groove serving as a common ink chamber communicating with the ink supply, and an ink supply port were formed.

  Next, as shown in FIG. 1, the nozzle plate 205b and the body plate prepared so far are bonded together using an adhesive, and a piezoelectric element as a pressure generating means is attached to the back of each cavity of the body plate. A droplet discharge head was obtained. This droplet discharge head is installed at a position facing the counter electrode 3 as in the liquid discharge apparatus 1 shown in FIG. 1, and each piezoelectric element and each drive voltage power source 23, electrostatic voltage power source 18 and charging electrode 16, Each drive voltage power supply 23 and electrostatic voltage power supply 18 and the operation control means 4 are connected to form the liquid ejection apparatus 1. The counter electrode 3 and the negative terminal of the electrostatic voltage power source 18 were grounded.

  The electrostatic voltage Vc applied from the electrostatic voltage power supply 18 is 1.5 kV, the drive voltage Vd from each drive voltage power supply 23 supplied to each piezo element is 20 V, and 3 masses of dye (CI Acid Red 1) are added to ethanol. When the droplet discharge head 2 was operated as a liquid for discharging a conductive liquid containing%, it was confirmed that stable discharge was possible.

(Example 2)
In this example, the upper mold 201, the lower mold 207, the press mechanism for moving the upper mold 201, and the high-frequency heating coil were provided in a chamber that can be separated from the ambient air.

  A top mold 201 made of silicon carbide (a shape in which 64 protrusions having a diameter of 5 μm and a height of 0.05 mm are arranged in a plane and arranged at a pitch of 30 μm. FIG. 2A) has a thickness of 0. A 1 μm gold film 203 was formed (FIG. 2B). At this time, the surface activation treatment of the surface of the upper mold 201 was not performed. In addition, the temperature of the upper mold 201 during film formation was set to about 200 ° C.

  Next, a thin plate 205 made of borosilicate glass having a thickness of 0.05 mm is placed on a lower mold 207 made of silicon carbide, and the chamber is placed in a chamber in order to create a nitrogen gas atmosphere at normal pressure. The introduction of nitrogen gas was started, and when about 3 minutes had passed after the start, the lower mold 207 was heated by a high frequency induction heating method to soften the thin plate 205 to about 680 ° C. (FIG. 2C). This molding temperature was determined by experiment with reference to the softening point of the borosilicate glass that is the material of the thin plate 205.

  Next, when lowering the upper mold 201 for press molding, the upper mold 201 is stopped immediately before touching the thin plate 205 and heated to the same temperature as the lower mold 207 by a high frequency induction heating method. Was lowered, and the thin plate 205 was press-molded to perform perforation (FIG. 2D). After the drilling, the thin plate 205 was cooled to about 30 ° C. as it was, and then the lower mold 207 was released (FIG. 2E).

  Next, a Teflon (registered trademark) water-repellent organic solvent “Fluorosurf” is spray-applied to the surface on which the lower mold 207 of the thin plate 205 is released, and dried at 120 ° C. for 30 minutes. 209 is provided (FIG. 2 (f)). Thereafter, the nozzle plate 205b is released from the upper mold 201 in a direction parallel to the protrusion so that the nozzle plate 205b is held by vacuum suction and a force in a direction perpendicular to the protrusion of the upper mold 201 is not applied (FIG. 2). (G)).

  As a result, the metal film 203 formed on the upper mold 201 can be transferred to the thin plate 205 and used as a charging electrode. A liquid repellent layer 209 a made of “fluorosurf” is formed on the opposite surface of the nozzle plate 205 b without entering the inside of the discharge hole 211.

  Thereafter, the liquid droplet ejection head 2 using the nozzle plate described above was operated as in Example 1 except that the electrostatic voltage Vc applied from the electrostatic voltage power supply 18 was set higher than 1.5 kV. It was confirmed that stable discharge was possible.

(Example 3)
In this example, the upper mold 201, the lower mold 207, the press mechanism for moving the upper mold 201, and the light-emitting unit for light heating were provided in a chamber that can be separated from the ambient air.

  Upper mold 201 made of carbon (shape having 32 projections with a diameter of 10 μm and a height of 0.05 mm arranged in a plane at a pitch of 50 μm. The thickness of the surface of FIG. 2A is 0.1 μm by sputtering. A platinum film 203 was formed (FIG. 2B). At this time, the surface activation treatment of the surface of the upper mold 201 was not performed. In addition, the temperature of the upper mold 201 during film formation was set to about 200 ° C.

  Next, a thin plate 205 made of quartz having a thickness of 0.05 mm is placed on a lower mold 207 made of carbon, and a nitrogen gas atmosphere is placed in the chamber in order to create a nitrogen gas atmosphere at normal pressure. The introduction was started, and when about 3 minutes passed, the lower mold 207 was heated by a light heating method using a halogen lamp to soften the thin plate 205 to about 1580 ° C. (FIG. 2C). . This molding temperature was determined by experiment with reference to the softening point of quartz, which is the material of the thin plate 205.

  Next, when lowering the upper mold 201 for press molding, the upper mold 201 is stopped immediately before touching the thin plate 205 and heated to the same temperature as the lower mold 207 by a light heating method. Drilling was performed by lowering and press-molding the thin plate 205 (FIG. 2 (d)). After the drilling, the thin plate 205 was cooled to about 60 ° C. as it was, and then the lower mold 207 was released (FIG. 2 (e)).

  Next, a water repellent vapor deposition material “Evaporation maintenance WR1: perfluoroalkylsilane” (Merck) is formed on the surface on which the lower mold 207 of the thin plate 205 is released to a thickness of 10 nm by vacuum deposition. A liquid repellent layer 209 was formed (FIG. 2F). Thereafter, the nozzle plate 205b was released from the upper mold 201 by vacuum suction so that a force in a direction perpendicular to the protrusion of the upper mold 201 was not applied (FIG. 2 (g)).

  As a result, the platinum film 203 formed on the upper mold 201 can be transferred to the thin plate 205 and used as a charging electrode. Further, a liquid repellent layer 209 a made of “perfluoroalkylsilane” is formed on the opposite surface of the nozzle plate 205 b without entering the inside of the discharge hole 211.

  Thereafter, as in Example 1, when the droplet discharge head 2 using the above-described nozzle plate was operated, it was confirmed that stable discharge was possible.

1 is a diagram illustrating a cross section of a liquid discharge head according to an embodiment and an overall configuration of a liquid discharge apparatus. It is a figure explaining an example of the manufacturing process of a nozzle plate with a sectional view. It is a figure which shows the whole structure to the liquid discharge apparatus which performed the discharge experiment by the actual machine. It is a figure which shows typically the electric potential distribution of the discharge hole vicinity of the nozzle by simulation. It is a figure which shows the relationship between the volume resistivity of a nozzle plate, and the electric field strength of a meniscus front-end | tip part. It is a figure which shows the example which provided the auxiliary | assistant board in the nozzle plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid discharge apparatus 2 Liquid discharge head 3 Counter electrode 4 Operation control means 10, 210 Nozzle 11, 205b Nozzle plate 12 Discharge surface 13, 211 Discharge hole 16 Charging electrode 17 Nozzle inner peripheral surface 18 Electrostatic voltage power source 19 Body plate 20 Cavity 22 Piezo element 23 Drive voltage power supply L Liquid D Droplet K Substrate receiving landing of droplet D 201 Upper mold 201a Nozzle formation protrusion 203 Metal film 203a Transferred metal film (charging electrode)
205 Thin plate 205a Perforated thin plate 207 Lower mold 209 Liquid repellent layer 209a Liquid repellent layer on nozzle plate

Claims (11)

A substrate provided between a first mold having a projection having a reversal shape of a nozzle for discharging liquid as droplets from the discharge hole and a second mold provided to face the first mold. In a nozzle plate manufacturing method for manufacturing a nozzle plate by pressing and forming the nozzle in the thickness direction of the substrate,
A film forming step for providing a film on the molding surface of the first mold;
A holding step for holding the substrate in the second mold;
A first heating step for heating the held substrate;
A second heating step for heating the first mold provided with the film;
In a state where the substrate and the first mold are heated, the molding surface on which the film of the first mold is provided is pressed on the substrate held by the second mold. A pressing step for forming the nozzle on the substrate and transferring the film,
A cooling step for cooling the substrate while being held by the second mold and being pressed by the first mold;
A first release step for releasing the second mold from the substrate;
A liquid repellent treatment step for performing a liquid repellent treatment on the surface of the substrate from which the second mold has been released;
And a mold release step for releasing the substrate from the first mold. 2. The nozzle plate manufacturing method according to claim 1, wherein the temperature of the first mold in the film forming step is lower than the temperature of the first mold in the pressing step. The nozzle plate manufacturing method according to claim 1, wherein the film is a metal film. The nozzle plate manufacturing method according to claim 1, wherein the film is a hydrophilic film. A nozzle plate manufactured by the nozzle plate manufacturing method according to claim 1. A substrate provided between a first mold having a projection having a reversal shape of a nozzle for discharging liquid as droplets from the discharge hole and a second mold provided to face the first mold. In a nozzle plate manufacturing method for manufacturing a nozzle plate by pressing and forming the nozzle in the thickness direction of the substrate,
A film forming step for providing a film on the molding surface of the first mold;
A holding step for holding the substrate in the second mold;
A first heating step for heating the held substrate;
A second heating step for heating the first mold provided with the film;
In a state where the substrate and the first mold are heated, the molding surface on which the film of the first mold is provided is pressed on the substrate held by the second mold. A pressing step for forming the nozzle on the substrate and transferring the film,
A cooling step for cooling the substrate while being held by the second mold and being pressed by the first mold;
And a mold release step for releasing the substrate from the first mold. The temperature of the said 1st metal mold | die in the said film formation process is lower than the said 1st metal mold | die temperature in the said press process, The nozzle plate manufacturing method of Claim 6 characterized by the above-mentioned. The nozzle plate manufacturing method according to claim 6, wherein the film is a metal film. The nozzle plate manufacturing method according to claim 6, wherein the film is a hydrophilic film. A substrate provided between a first mold having a projection having a reversal shape of a nozzle for discharging liquid as droplets from the discharge hole and a second mold provided to face the first mold. In a nozzle plate manufacturing method for manufacturing a nozzle plate by pressing and forming the nozzle in the thickness direction of the substrate,
A holding step for holding the substrate in the second mold;
A first heating step for heating the held substrate;
A second heating step for heating the first mold;
A pressing step for pressing the first mold onto the substrate held by the second mold while the substrate and the first mold are heated;
A cooling step for cooling the substrate while being held by the second mold and being pressed by the first mold;
A first release step for releasing the second mold from the substrate;
A liquid repellent treatment step for performing a liquid repellent treatment on the surface of the substrate from which the second mold has been released;
And a second release step for releasing the substrate from the first mold. A method for manufacturing a nozzle plate, comprising: A nozzle plate manufactured by the nozzle plate manufacturing method according to claim 6.

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