JP2012250440A - Inkjet head and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet head that can be assembled with high accuracy while suppressing the damage of an inkjet head member, and to provide a method for manufacturing the same.SOLUTION: In a step for bonding a nozzle plate 12 and an ink flow path plate 13, a non-curing adhesive 21 is applied to an outer periphery of a nozzle hole 11 to keep sealing performance. Furthermore, only the non-curing adhesive 21 in the vicinity of the nozzle hole is locally half-cured. Subsequently, the adhesive is totally-cured by heat while the whole is uniformly pressured after the nozzle plate 12 and the ink flow path plate 13 are disposed parallel at aligned positions. An ultraviolet-curable adhesive is used as the adhesive in order to locally half-cure the adhesive.

Description

  The present invention relates to an inkjet head and a manufacturing method thereof.

  An ink-jet head is known as a head that can apply a necessary amount of ink when necessary according to an input signal. In particular, piezoelectric (piezo) ink jet heads are being actively developed because they can apply a wide variety of inks while controlling them with high precision.

  FIG. 4 shows the configuration of a general inkjet head. The piezoelectric inkjet head includes an ink supply channel, a plurality of ink chambers that communicate with the ink supply channel and have nozzle holes 11, and a piezoelectric element 19 that applies pressure to the ink filled in the ink chamber. The ink droplets are ejected from the nozzle hole 11 by applying pressure to the ink in the ink chamber due to mechanical distortion of the piezoelectric element caused by applying a driving voltage to the piezoelectric element. It is formed by adhering the nozzle plate 12 and the ink flow path plate 13, the ink flow path plate 13 and the membrane 18, and the membrane 18 and the piezoelectric element 19. In particular, in the bonding between the nozzle plate 12 and the ink flow path plate 13, it is necessary to bond so that the adhesive does not flow into the nozzle holes 11 and the ink flow paths.

  In order to solve the above-mentioned problem, as a conventional method, there is one in which a weir is provided by applying an adhesive around the nozzle hole in advance and curing to prevent the adhesive from flowing in (see, for example, Patent Document 1). . FIG. 5 is a diagram showing a conventional configuration described in Patent Document 1. In FIG. An adhesive (uncured adhesive 21) is applied around the nozzle holes 11 formed in the nozzle plate 12, and a weir of the cured adhesive (fully cured adhesive 23) is provided. The adhesive (uncured adhesive 21) is applied again between the adhesive weirs and adhered to the ink flow path plate 13.

  As another conventional method, there is a method of forming a groove around the nozzle hole (see, for example, Patent Document 2). FIG. 6 is a diagram showing a conventional configuration described in Patent Document 2. As shown in FIG. A groove 14 is provided around the nozzle hole 11 formed in the nozzle plate 12, and an adhesive (uncured adhesive 21) is applied thereon to adhere to the ink flow path plate 13. Furthermore, as another conventional method, there is a method in which only the periphery of the nozzle hole is completely cured to form a bank (for example, see Patent Document 3). FIG. 7 is a diagram showing a conventional configuration described in Patent Document 3. As shown in FIG.

  An adhesive (uncured adhesive 21) is applied to the periphery of the nozzle hole 11 opened in the nozzle plate 12, and the adhesive (uncured adhesive 21) is completely cured only in the vicinity of the nozzle hole 11 (fully cured). The adhesive 23) is adhered to the ink flow path plate 13.

JP-A-7-285223 Japanese Patent Laid-Open No. 2002307687 JP 2008-188869 A

  However, the conventional configuration cannot cope with a high-definition inkjet head. In addition, since a completely hardened adhesive has to apply a large load during bonding, the nozzle plate and the ink flow path plate are distorted or the water repellent film on the surface of the nozzle plate is damaged. In addition, there is a problem that the adhesion around the nozzle hole becomes insufficient and the discharge speed cannot be sufficiently obtained.

  Accordingly, the present invention solves the above-described conventional problems, and provides a manufacturing method capable of suppressing damage to an inkjet head member and assembling with high accuracy, an inkjet head capable of stably obtaining a discharge speed, and a manufacturing method thereof. For the purpose.

  In order to achieve the above object, a first invention of the present application is an inkjet head that sends ink by a piezoelectric element to a pressure chamber having a nozzle plate, an ink flow path plate, and a membrane. The nozzle plate and the ink The step of adhering the chamber plates includes a step of temporarily curing the adhesive and a step of fully curing the adhesive.

  With this configuration, the adhesive can be prevented from flowing into the nozzle hole.

  The second invention of the present application is characterized in that, in the step of temporarily curing the adhesive, the degree of cure of the adhesive is less than 100%.

  With this configuration, it is possible to reduce the load required for bonding while maintaining the bonding force.

  3rd invention of this application has the characteristics hardened | cured because an adhesive agent absorbs an ultraviolet-ray in the process of pre-hardening an adhesive agent.

  With this configuration, the degree of curing of the adhesive can be easily controlled.

  With this configuration, the load required for bonding can be further reduced.

  A fourth invention of the present application is an ink jet head having a structure in which a nozzle plate having nozzle holes and an ink flow path plate for applying pressure to ejected ink are bonded to each other. It is characterized by having air bubbles on the path plate side and no air bubbles on the ink flow path plate side of the other part of the adhesive layer.

  This configuration has the advantage that it is difficult to damage the water-repellent film around the nozzle hole because the bonding portion sinks due to having a minute space during wiping. The wiping is a maintenance operation of the ink jet head in which excess droplets that have a bad influence on the flight bending remaining around the nozzle hole are wiped off with a cloth.

  As described above, according to the present invention, it is possible to suppress the flow of the adhesive into the nozzle hole and simultaneously reduce the load necessary for bonding. Thereby, damage of a member can be suppressed and it can assemble with sufficient accuracy. Further, it is possible to provide an ink jet head that maintains the sealing performance around the nozzle hole and has stable ejection characteristics.

The figure which shows the adhesion process of the nozzle plate and ink flow path plate in Embodiment 1 of this invention. The figure which shows the adhesion process of the nozzle plate and ink flow path plate in Embodiment 2 of this invention. The figure which shows the characteristic of the inkjet head manufactured by Embodiment 1 and 2 of this invention Diagram showing the configuration of a general inkjet head The figure which shows the adhesion process of the conventional nozzle plate and ink flow path plate described in patent document 1 The figure which shows the adhesion process of the conventional nozzle plate described in patent document 2, and an ink flow path plate The figure which shows the adhesion process of the conventional nozzle plate and ink flow path plate which were described in patent document 3

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a manufacturing process of an ink jet head according to Embodiment 1 of the present invention.

  In FIG. 1 (a), an adhesive (uncured adhesive 21) is applied to the nozzle plate 12. The surface of the nozzle plate 12 and the ink flow path plate 13 is cleaned using ultraviolet rays or plasma. The nozzle plate and the ink flow path plate are made of, for example, stainless steel. The nozzle plate is a plate in which holes of the same size are spaced at equal intervals on a stainless steel plate. The nozzle hole can be processed with, for example, a laser.

  The ink flow path plate is a plate in which holes and slits are spaced at equal intervals on a stainless steel plate. It can be processed by laser or etching. Further, when a complicated flow path shape is formed in the plate, it is possible to manufacture by laminating a plurality of processed plates.

  By sufficiently washing the surfaces of the nozzle plate and the ink flow path plate manufactured as described above, the adhesive strength between the nozzle plate 12 and the ink flow path plate 13 is increased through the adhesive. However, since the surface state deteriorates with time, it is desirable to wash immediately before applying or bonding the adhesive. As will be described later, since the contact angle of the plate decreases as the plate is washed well, the pattern spreads and spreads when the adhesive is applied, and transferability deteriorates.

  Therefore, it is desirable that the contact angle with respect to pure water of the nozzle plate to which the adhesive is applied is 10 ° or more and 80 ° or less. By setting such conditions, the adhesive strength can be increased while relatively maintaining the transferability. More preferably, it is desirable that the angle is 30 ° or more and 50 ° or less. As a result, the transferability of the adhesive pattern is well maintained, and the adhesive strength is not impaired.

  When applying an adhesive, it is desirable to use screen printing. By using screen printing, it is possible to apply the adhesive pattern around the nozzle holes with high accuracy. The thickness of the adhesive to be applied is 5 to 10 μm, and the pattern width is preferably about ¼ to ½ of the distance between the nozzle holes. If the thickness of the adhesive is less than 5 μm, sufficient sealing properties cannot be ensured if there is variation in the printed thickness. On the other hand, when the thickness of the adhesive is larger than 10 μm, the adhesive becomes excessive. Further, when the pattern width is less than 1/4 of the distance between the nozzle holes, the adhesive strength cannot be obtained, and when the pattern width is more than 1/2, it causes the flow into the nozzle holes.

  The screen plate pattern to be used preferably has a function of sealing the periphery of the nozzle hole, a function of maintaining the adhesive strength in the peripheral part, and a function of suppressing peeling of the plate at the outermost periphery of the plate. Use a metal mask for the screen version.

  In order to seal around the nozzle hole, for example, a ladder-like pattern may be used. Since the pattern transfer property of screen printing is improved at a portion where the ladder pattern intersects, the film thickness tends to be larger than that at the peripheral portion. Therefore, in order to suppress the flow of the adhesive after bonding and make the bonded shape more perfect, it is better to design a pattern that actively reduces the volume of the adhesive, for example, by narrowing the pattern at the intersection.

  It is preferable to arrange patterns at regular intervals in the portion that maintains the adhesive strength. A round shape is desirable because transferability is good. A pattern shape having an acute angle such as a square may be used, but the pattern at the acute angle portion is easily blurred. Further, it is preferable that the pattern interval is sufficiently large so that the adjacent adhesive patterns do not hold after being crushed by the load. Since the air existing between the nozzle plate 12 and the ink flow path plate 13 is easily removed, when the plate coated with the adhesive is pressurized and cured by heat, the air confined in the space is thermally expanded by the thermal expansion. It is possible to suppress the breaking of the pattern and secure the sealing property.

  Screen printing has been described as a method for applying the adhesive, but the method for applying the adhesive is not limited. For example, a dispenser, letterpress printing, gravure printing, or the like may be used. Moreover, although the method for applying the adhesive to the nozzle plate has been described, the substrate to which the adhesive is applied is not limited and may be applied to the ink flow path plate side.

  Moreover, there is no restriction | limiting in particular in the adhesive agent to be used, An epoxy adhesive agent, an acrylic adhesive agent, etc. may be used. However, in order to locally semi-cure only the vicinity of the nozzle hole, it is preferable to use an epoxy adhesive having ultraviolet curing properties. In addition, it is desirable that the adhesive also has a thermosetting characteristic so as to be uniformly cured while being uniformly pressurized.

  Furthermore, in order to ensure the film thickness uniformity of the adhesive layer after bonding, it is desirable to include a spacer in the adhesive. For this spacer, for example, silica particles are used. The particle diameter is desirably 0.1 to 10 μm. If it is less than 0.1 μm, the particles tend to aggregate, and if it is 10 μm or more, the adhesive film thickness becomes too large and weak against shear stress. The contained particles may be 0.1 to 10 wt%. If it is less than 0.1 wt%, the role of the spacer is weakened, and if it is 10 wt% or more, the adhesive strength is lowered. In order to disperse the spacers in the adhesive uniformly, for example, a kneader such as a three-roller may be used.

  Next, in FIG. 1B, the adhesive (uncured adhesive 21) is irradiated with ultraviolet rays 15 to be temporarily cured (semi-cured adhesive 22). By temporarily curing, it is possible to suppress the flow of the adhesive into the nozzle hole. In order to selectively irradiate the adhesive (uncured adhesive 21) with ultraviolet rays, for example, a mask 17 may be used. As for the intensity | strength of an ultraviolet-ray, 0.1-10 mW / cm <2> is desirable. When it is less than 0.1 mW / cm 2, the curing of the adhesive does not proceed sufficiently, and when it is 10 mW / cm 2 or more, only the surface of the adhesive is easily cured. The degree of cure of the adhesive in the temporary curing step is less than 100%, preferably 20 to 80%, and more preferably 40 to 60%.

  When the degree of cure is less than 100%, the load required for adhesion can be reduced. Further, the adhesive strength can be ensured by setting it to 20 to 80%, and the flow of the adhesive into the nozzle hole 11 can be suppressed by setting it to 40 to 60%. When arranging the mask, it is better to make the distance from the adhesive as close as possible because the controllability of the semi-cured range is improved.

  Finally, in FIG. 1C, the ink flow path plate 13 is disposed on the opposite side of the nozzle plate 12, and is fully cured in a thermosetting furnace while the whole is pressurized. By this step, the adhesive (uncured adhesive 21) and the adhesive (semi-cured adhesive 22) are cured to become a fully cured adhesive 23. Although it depends on the type of adhesive, it is cured at a temperature of approximately 50 to 200 ° C. Further, the load necessary for bonding is about 1 to 50 kgf.

  According to such a method for manufacturing an ink jet head, it is possible to both prevent the adhesive from flowing into the nozzle hole and ensure the sealing performance by temporarily curing only the portion that requires the sealing performance, rather than temporarily curing the whole. However, since the load required for adhesion can be reduced, damage to the members can be prevented and assembly can be performed with high accuracy.

  The inkjet head according to this manufacturing method has the following characteristics. The adhesive layer near the nozzle hole has a lot of minute space (bubbles) on the ink flow path plate side, and the minute space (bubble) on the ink flow path plate side of the other part of the adhesive layer is near the nozzle hole The adhesive layer is less than the adhesive layer.

  FIG. 3 shows the shape of the adhesive when the adhesive is temporarily cured. FIG. 3A shows the state of the adhesive when the vicinity of the nozzle hole is temporarily cured, and FIG. 3B shows the nozzle hole. It is a figure which shows the mode of the adhesive agent at the time of main-curing the vicinity.

  In the figure, 24 is an adhesive layer near the nozzle hole 11, and a bubble 16 is a minute space on the ink flow path plate 13 side of the adhesive layer near the nozzle hole 11. Reference numeral 25 denotes an adhesive layer other than the adhesive layer near the nozzle hole 11. The adhesive disposed outside the vicinity of the nozzle holes has a small space 16 on the ink flow path plate 13 side.

  The ink jet head having such a structure has an advantage that the water repellent film around the nozzle hole is hardly damaged during wiping. Wiping is a maintenance operation of the inkjet head that wipes off excess droplets that have a bad influence on the flight bend remaining around the nozzle hole with a cloth. In the ink jet head of the present application, when wiping, the adhesive 24 disposed in the vicinity of the nozzle hole sinks due to the minute space with respect to the adhesive 25 disposed in the vicinity of the nozzle hole. It is hard to damage the water repellent film around the hole.

  The plate unit bonded with the nozzle plate and the ink flow path plate manufactured as described above is bonded to the membrane. The adhesive is applied to the ink flow path plate or the membrane side. The application method, the adhesive, the pressurizing method, and the curing method can be manufactured by the same method as that for adhering the nozzle plate and the ink flow path plate as described above.

  The nozzle unit, the ink flow path plate, and the plate unit bonded with the membrane manufactured as described above are bonded to the piezoelectric element. The adhesive is applied to the membrane or piezoelectric element side. About an application method, an adhesive agent, a pressurization method, and a hardening method, it is possible to manufacture by the method similar to the above.

  In this way, an ink jet head can be manufactured.

(Embodiment 2)
FIG. 2 is a diagram showing a manufacturing process of the ink jet head in the second embodiment of the present invention.

  In FIG. 2 (a), an adhesive (uncured adhesive 21) is applied to the nozzle plate 12. Since the kind of adhesive, the coating method, and the like may be the same as those in Embodiment 1, the details are omitted.

  Next, in FIG. 2B, the ink flow path plate 13 is arranged in parallel to the opposite side of the nozzle plate 12, and alignment is performed so that the position is reached. The distance between the adhesive and the ink flow path plate is arbitrary, but if it is as close as possible, only the range substantially equivalent to the hole shape opened in the ink flow path plate can be selectively semi-cured.

  Further, when the distance between the adhesive and the ink flow path plate is set to be large, the ultraviolet rays can circulate from the hole opened in the ink flow path plate, and can be semi-cured to a range larger than the hole shape. That is, the adhesive (uncured adhesive 21) in the ink flow path is irradiated with ultraviolet rays 15 to be temporarily cured (semi-cured adhesive 22). In order to selectively irradiate the adhesive (uncured adhesive 21) with ultraviolet rays, ultraviolet rays 15 are irradiated from above. The ultraviolet irradiation intensity and the curing degree of the adhesive are the same as those in the first embodiment.

  By such a method, only the adhesive near the nozzle hole can be selectively temporarily cured. This is shown in FIG. Thereafter, the nozzle plate and the ink flow path plate are bonded without any gap by performing main curing in a thermosetting furnace while uniformly pressurizing the whole. At this time, the adhesive (uncured adhesive 21) and the adhesive (semi-cured adhesive 22) are cured to become a fully cured adhesive 23 having the same composition of the adhesive (FIG. 2D). )). The curing temperature and the adhesive load may be the same as in the first embodiment.

  According to such an ink jet head manufacturing method, the vicinity of the nozzle holes can be selectively temporarily cured as compared with the first embodiment. Therefore, the sealing performance can be further improved and the load necessary for adhesion can be reduced. Further, since the ink flow path plate aligned with the nozzle plate can be used as it is instead of the mask, it is not necessary to prepare a separate mask.

  The inkjet head of the present invention has stable ejection characteristics and can be applied to display manufacturing and other industrial uses.

11 Nozzle hole 12 Nozzle plate 13 Ink flow path plate 14 Groove 15 Ultraviolet ray 16 Minute space (bubble)
17 Mask 18 Membrane 19 Piezoelectric Element 21 Uncured Adhesive 22 Semi-cured Adhesive 23 Fully Cured Adhesive 24 Adhesive Arranged Near Nozzle Hole 25 Adhesive Arranged Other Than Near Nozzle Hole

Claims (4)

A method of manufacturing an inkjet head manufactured by a step of bonding a nozzle plate and an ink flow path plate, a step of bonding a membrane, and a step of bonding a piezoelectric element,
The step of bonding the nozzle plate and the ink flow path plate includes:
After applying adhesive to the nozzle plate or ink flow path plate at multiple locations and pre-curing the adhesive applied in the vicinity of the nozzle among the adhesives, the nozzle plate and the ink flow path plate are placed facing each other. And then pressing from at least one of the nozzle plate and the ink flow path plate and fully curing the adhesive,
A method of manufacturing an ink-jet head.   The method for producing an ink jet head according to claim 1, wherein when the adhesive is temporarily cured, the degree of cure of the adhesive is less than 100%.   The inkjet head according to claim 1, wherein when the adhesive is temporarily cured, the adhesive is a material that is cured by absorbing ultraviolet rays, and the adhesive is temporarily cured by irradiating ultraviolet rays. Manufacturing method. An ink jet head having a structure in which a nozzle plate having a nozzle hole and an ink flow path plate having a pressure chamber communicating with the nozzle are bonded via an adhesive,
The volume of bubbles on the ink flow path plate side of the adhesive applied in the vicinity of the nozzle hole is larger than the volume of bubbles on the ink flow path plate side of the other part of the adhesive,
An inkjet head characterized by the above.

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