JP5607849B1 - Liquid coating method and liquid coating apparatus - Google Patents

Abstract

The present invention provides a liquid coating method and a liquid coating apparatus capable of efficiently forming a liquid film on the inner surface of a recess.
A liquid coating method includes a jet part S1 extending linearly from a nozzle 1 toward a counter electrode 20, and a spread part S2 formed at the tip of the jet part S1 and having an outer diameter that increases as the distance from the nozzle 1 increases. The liquid L is electrostatically sprayed so as to be formed, and the liquid L is applied to the surface of the substrate SB having the trench Tr. In this step, the boundary Sb between the jet part S1 and the expanded part S2 is arranged in the trench Tr of the substrate SB.
[Selection] Figure 1

Description

  The present invention relates to a liquid coating method and a liquid coating apparatus.

  Conventionally, a liquid coating method using a so-called electrostatic spraying technique is known in which charged liquid is discharged from a cylinder, and a large number of fine droplets are formed by a repulsive force due to electrostatic force and supplied to an object. .

JP 2006-58628 A JP 2004-136655 A

  However, in the conventional technique, when the object has a recess, it is difficult to efficiently form a liquid film on the inner surface of the recess.

  The present invention has been made in view of the above problems, and an object thereof is to provide a liquid coating method and a liquid coating apparatus capable of efficiently forming a liquid film on the inner surface of a recess.

  As a result of intensive studies by the present inventors, it has been found that a liquid film can be efficiently formed on the inner surface of the recess when the boundary between the jet portion and the spread portion formed by electrostatic spraying is disposed in the recess.

The liquid coating method according to the present invention forms a jet portion extending linearly from the nozzle toward the counter electrode, and a spread portion formed at the tip of the jet portion and having an outer diameter that increases as the distance from the nozzle increases. A step of electrostatically spraying a liquid and applying the liquid onto the surface of an application object having a recess;
In the step, a boundary between the jet portion and the spread portion is disposed in the concave portion of the application target.

The liquid coating apparatus according to the present invention forms a jet portion that extends linearly from the nozzle toward the counter electrode, and a spread portion that is formed at the tip of the jet portion and that increases in outer diameter as the distance from the nozzle increases. An electrostatic spraying part for electrostatically spraying the liquid;
A control unit that controls the electrostatic spraying unit so that a boundary between the jet unit and the spreading unit is located in a recess of the application target.

  According to the present invention, since the boundary between the jet portion and the expanding portion is located in the recess, the liquid film can be efficiently applied in the recess.

  Here, in the above method, the position of the boundary between the jet part and the spreading part is determined based on the flow rate of the liquid ejected from the nozzle, the magnitude of the voltage applied between the nozzle and the counter electrode, and It can be controlled by changing at least one of the distance between the nozzle and the counter electrode.

  Further, in the above apparatus, the control unit sets a boundary position between the jet unit and the spreading unit, a flow rate of the liquid discharged from the nozzle, and a magnitude of a voltage applied between the nozzle and the counter electrode. And at least one change in the distance between the nozzle and the counter electrode.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid coating method and liquid coating apparatus which can form a liquid film efficiently in the inner surface of a recessed part are provided.

FIG. 1 is a schematic configuration diagram of a liquid coating apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view of the vicinity of the tip of the nozzle of FIG.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a partially broken schematic view of a liquid coating apparatus 100 according to an embodiment of the present invention. The liquid coating apparatus 100 of this embodiment mainly includes an electrostatic spray unit 50, a relative movement unit 60, and a control unit 70. The electrostatic spray unit 50 includes a nozzle unit 10, a counter electrode 20, a power supply 30, and a liquid supply unit 40.

  The electrostatic spray unit 50 includes a nozzle (tubular electrode) 1 and a cover 3.

  The nozzle 1 is connected to an external power source 30, and the liquid sent from the liquid supply unit 40 is charged by the nozzle 1. The nozzle 1 is connected to the line L10 from the liquid supply unit 40 using the joint 4 at the upper end. For example, all or part of the nozzle 1 is made of a conductive material such as stainless steel, and all or part of the inner surface is formed of a conductive wall.

  The cover 3 has a shape that covers the side surface of the nozzle 1 and is made of an electrically insulating material such as resin (PTFE or the like). Although the internal diameter of the nozzle 1 is not specifically limited, For example, it can be 10-1000 micrometers.

  The counter electrode 20 is disposed on an extension line of the axis of the nozzle 1 and is separated from the nozzle 1. The counter electrode 20 is preferably grounded. The distance between the nozzle 1 and the substrate SB is not particularly limited, but can be, for example, about 10 to 60 mm.

  In this embodiment, the counter electrode 20 has a plate shape, and the substrate SB to be coated is placed on the counter electrode. The shape of the counter electrode 20 is not limited to a plate shape.

  The power source 30 applies a voltage between the nozzle 1 and the counter electrode 20. Usually, the voltage is a direct current and can also be supplied in pulses. Although a voltage is not specifically limited, In this embodiment, it can be set to 5-20 kV. The voltage is preferably applied to the counter electrode 20 so that the nozzle 1 side is positive.

  When the voltage from the power supply 30 is supplied, an electrostatic spray phenomenon occurs from the tip 1n of the nozzle 1 as shown in FIG. Specifically, the Taylor cone T of the liquid L is formed at the tip 1n of the nozzle 1, and from the tip, the jet portion S1 that extends linearly, and the tip of the jet portion S1, formed away from the tip 1n of the nozzle 1. As a result, a liquid spray structure S having an expanded portion S2 (sometimes referred to as flare) whose outer diameter increases is formed. When the boundary Sb is unclear, the boundary can be a place where the diameter becomes twice the minimum diameter portion in the jet portion S1.

  Returning to FIG. 1, the liquid supply part 40 is an apparatus which supplies a liquid with respect to the nozzle 1 via the line L10.

The liquid supply unit 40 includes a tank 41 that stores the liquid, and a pump 42 that supplies the liquid from the tank 41 to the nozzle 1 via the line L10. In the present embodiment, the liquid is supplied to the nozzle 1 through the line L10 by supplying air to the tank 41 in which the pump 42 is in a sealed state. The liquid supply unit 40 does not necessarily have to supply the liquid by the pump 42. For example, the liquid supply unit 40 can be configured by an air pulse dispenser. An air pulse dispenser is a device that pushes out a liquid material by opening and closing a solenoid valve for a certain period of time to introduce a gas such as N _{2 having} a reduced pressure through a regulator to a container such as a syringe enclosing the liquid material.

  The relative moving unit 60 moves the nozzle unit 10 relative to the counter electrode 20 or the substrate SB on the counter electrode. Specifically, for example, when the object is the substrate SB, the nozzle unit 10 can independently move in two axes within a horizontal plane parallel to the surface of the substrate SB. Thereby, the liquid can be applied to a desired portion on the substrate SB. Moreover, it is preferable that the relative movement part 60 can move the nozzle unit 10 with respect to the counter electrode 20 also in a direction perpendicular to the substrate SB. Thereby, it is easy to adjust the distance between the tip of the nozzle 1 and the substrate SB.

  The control unit 70 controls the power supply 30, the pump 42 of the liquid supply unit 40, and the relative movement unit 60. Specifically, as illustrated in FIG. 2, the control unit 70 causes the tip 1 n of the nozzle 1 to be relatively positioned on the trench (concave portion) Tr of the substrate (application target) SB to be applied. The relative moving unit 60 is controlled. Further, the control unit 70 controls the magnitude of the voltage applied from the power supply 30 and the discharge flow rate of the liquid controlled by the pump 42, and the boundary Sb between the jet part S1 and the spreading part S2 is inside the trench Tr. The spray structure S is controlled so as to be positioned.

  An example of a specific control method is as follows. First, a matrix of the position of the boundary Sb (for example, the height from the counter electrode 20 and the distance from the tip 1n of the nozzle 1) for the combination of the flow rate and the voltage value is prepared in advance according to the type of liquid. This is stored in the control unit 70. If the flow rate and / or voltage is changed so that the desired boundary Sb is obtained, the position of the boundary Sb can be freely controlled. Further, if a plurality of such matrixes of the position of the boundary Sb are obtained in advance according to the distance between the tip 1n of the nozzle 1 and the substrate SB and stored in the control unit 70, the control is performed even when this distance varies. Is possible.

  Further, the position of the boundary Sb is photographed by the camera, the photographed image is image-processed to obtain the current position of the boundary Sb, and based on the relationship (for example, difference) between the current position of the boundary Sb and the set position of the boundary Sb. The position of the boundary Sb can also be controlled by so-called feedback control that changes the voltage and / or flow rate so that the boundary Sb approaches the set position.

  When the voltage of the power supply 30 is increased, the position of the boundary Sb tends to move away from the tip 1n of the nozzle 1, and when the voltage of the power supply 30 is decreased, the position of the boundary Sb tends to approach the tip 1n of the nozzle 1. Further, when the liquid supply flow rate by the pump 42 is increased, the position of the boundary Sb tends to move away from the tip 1n of the nozzle 1, and when the liquid supply flow rate is decreased, the position of the boundary Sb tends to approach the tip 1n of the nozzle 1. .

  Further, the position of the boundary Sb can also be controlled by changing the distance between the nozzle 1 and the counter electrode 20 instead of or in addition to the control based on the flow rate and / or voltage. Even if the distance between the nozzle 1 and the counter electrode 20 is changed, the distance between the boundary Sb and the tip 1n of the nozzle 1 is usually not changed in many cases. However, since the distance between the boundary Sb and the counter electrode 20 changes, the relative positional relationship between the substrate SB and the boundary Sb can be controlled.

  The distance from the tip 1n of the nozzle 1 at the boundary Sb can be set to 5 to 100 mm, for example.

(Liquid for electrostatic spraying)
The liquid to be electrostatically sprayed in this embodiment is not particularly limited, but may include a film forming material and a liquid component that dissolves or disperses the film forming material.

  The film-forming material is a component that forms a film by evaporating a liquid component from the electrostatic spraying liquid and then remaining without evaporation. Examples of the film forming material are a resin and / or inorganic particles.

  Examples of the resin are epoxy resin (for example, bisphenol A type epoxy resin, novolac type epoxy resin), polyhydroxystyrene resin, acrylic resin, urethane resin, silicone resin, polyamideimide resin, and polyimide resin.

  The resin may be thermoplastic or curable. The curable resin can contain a monomer and / or a prepolymer and a curing agent. The curing agent can be arbitrarily selected depending on the monomer, prepolymer, curing conditions after electrostatic coating (photocuring, thermal curing, reaction curing, etc.) and the like.

  The curable resin can also include a polymerizable monomer and / or a polymerizable prepolymer. For example, examples of the polymerizable monomer for the acrylic resin are esters of acrylic acid or methacrylic acid such as 1,9-nonanediol acrylate and 1,1,1-trimethylolpropane triacrylate.

The resin can include a photosensitizer such as naphthoquinonediazide, in which case the resin can be a photosensitive resist.
The resin can contain various additives such as a surfactant and a leveling material.

  Specifically, the resin as described above can be a photosensitive resist, an adhesive, a coating agent, or the like.

  Examples of inorganic particles are metal particles and oxide particles. Examples of metal particles are silver particles, gold particles, copper particles, and the like. Examples of the oxide particles include ceramic particles such as titania, silica, and alumina, and glass particles.

  The example of the particle size of a metal particle or an oxide particle is 0.001-100 micrometers.

  The liquid component can dissolve or disperse the film-forming component. Examples of liquid components are γ-butyrolactone, ethyl lactate, acetone, diglyme, cyclopentanone, and water. The relative dielectric constant of each liquid component is 39, 13, 20, 8, 14, 80. The liquid component can be a mixture of these compounds.

  The liquid component is preferably liquid at 25 ° C. Further, the boiling point of the liquid component can be 80 ° C. or higher, and can be lower than 260 ° C. When the boiling point is 80 ° C. or higher, a liquid film is easily formed on the object. Further, when the boiling point is less than 260 ° C., the drying time can be shortened and the productivity is easily improved.

  The electrostatic spray liquid may have a relative dielectric constant of 14 to 100. The relative dielectric constant is [dielectric constant / dielectric constant of vacuum]. The relative dielectric constant of the liquid can be measured by MODEL 871 manufactured by Nippon Luft. The maximum value of the relative dielectric constant can be 90 or less and 80 or less. The minimum value of the dielectric constant can be 16 or more, 20 or more, or 30 or more.

  The preferable viscosity range of the liquid for electrostatic spraying is 5 to 100,000 mPa · s, but is not limited thereto.

  The electrostatic spray liquid may contain further additives. Examples of additives are surfactants, leveling agents and the like. The concentration of the additive can be 10% by mass or less.

  The method for preparing the electrostatic spray liquid is not particularly limited, and the above-described film forming component and liquid component may be mixed.

Subsequently, a liquid coating method using the liquid coating apparatus 100 of the present embodiment will be described.
First, the substrate SB to be applied is placed on the counter electrode 20. The material of the substrate SB is not particularly limited. However, when the substrate SB is conductive, an insulating material can be interposed so as not to conduct with the counter electrode 20. Subsequently, a voltage is applied between the nozzle 1 and the counter electrode 20 by the power source 30. Further, the pump 42 is driven to supply the liquid in the tank 41 into the nozzle 1 via the line L10. The liquid is charged by being charged by the nozzle 1, and the liquid protruding from the tip 1 n of the nozzle 1 forms a Taylor cone T. At the tip of the Taylor cone T, a jet part S1 and a spreading part S2 are formed (electrostatic spraying step). In the spreading portion S2, the droplet is split (Rayleigh split) by electrostatic force, and the droplet spreads in a direction perpendicular to the axis of the nozzle 1.

  In the present embodiment, the boundary Sb between the jet portion S1 and the expanding portion S2 is positioned inside (inside) the trench Tr by adjusting the supply flow rate and / or voltage of the liquid. According to this embodiment, a liquid or a solid film derived from the liquid can be efficiently formed on the inner surface of the trench Tr. When the trench Tr is deep to some extent, the liquid can be applied while moving the position of the boundary Sb in the depth direction of the trench Tr.

  According to the present embodiment, it is possible to eliminate waste of liquid when applying the liquid in the recess. In addition, the liquid can be efficiently applied in a narrow and deep hole.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, the method of electrostatic spraying is not limited to the above-described embodiment, and is not particularly limited as long as the liquid is charged and the charged liquid is discharged from the flow path of the cylinder toward the counter electric training.

  In the above embodiment, since the liquid application target is the substrate SB, the counter electrode 20 is also plate-shaped, but the shape of the counter electrode 20 can be changed to a desired form according to the shape of the application target. . Further, the object to be applied is not particularly limited, and for example, the liquid can be applied to various objects such as a substrate having an uneven surface.

  Moreover, in the said embodiment, although the trench Tr is mentioned as a recessed part, it cannot be overemphasized that other recessed parts, such as a hole, may be sufficient. The inner diameter of the trench Tr and the inner diameter of the hole can be set to 0.5 to 100 mm, for example. Moreover, the depth of a trench or a hole can be 5-50 mm, for example.

  DESCRIPTION OF SYMBOLS 1 ... Nozzle, Tr ... Trench (concave part), SB ... Substrate (application object), S1 ... Jet part, S2 ... Spreading part, Sb ... Boundary, 50 ... Electrostatic spray part, 70 ... Control part, 100 ... Liquid application apparatus.

Claims (6)

The liquid is electrostatically sprayed so as to form a jet part extending linearly from the nozzle toward the counter electrode, and a spreading part formed at the tip of the jet part and having an outer diameter that increases as the distance from the nozzle increases. A step of applying the liquid to the surface of the application object having
In the step, a liquid coating method is provided in which a boundary between the jet portion and the spread portion is disposed in the concave portion of the application target.   The position of the boundary between the jet part and the spreading part is defined as the flow rate of the liquid discharged from the nozzle, the magnitude of the voltage applied between the nozzle and the counter electrode, and the nozzle and the counter electrode. The liquid coating method according to claim 1, wherein the liquid coating method is controlled by changing at least one of the distances. Electrostatic spray that electrostatically sprays the liquid so as to form a jet portion extending linearly from the nozzle toward the counter electrode and a spreading portion formed at the tip of the jet portion and having an outer diameter that increases as the distance from the nozzle increases. And
A liquid coating apparatus comprising: a control unit that controls the electrostatic spraying unit so that a boundary between the jet unit and the spreading unit is positioned in a concave portion of the coating target.   The control unit is configured to determine a boundary position between the jet unit and the spreading unit, a flow rate of the liquid ejected from the nozzle, a magnitude of a voltage applied between the nozzle and the counter electrode, and the nozzle. The liquid coating apparatus according to claim 3, wherein the liquid coating apparatus is controlled by changing at least one of a distance from the counter electrode. A storage unit for storing a matrix relating to the position of the boundary with respect to a combination of a flow rate of the liquid and a magnitude of a voltage applied between the nozzle and the counter electrode;
The control unit includes an adjustment unit that adjusts a flow rate of the liquid and / or a voltage applied between the nozzle and the counter electrode so that the boundary is located in the recess based on the matrix. The liquid coating apparatus according to claim 3. An acquisition unit that acquires a relationship between a current position of the boundary and a setting position in the recess of the boundary;
6. The liquid application apparatus according to claim 3, wherein the control unit controls the electrostatic spray unit so that the boundary is located in the concave portion based on the relationship.

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