JP2012250517A - Liquid droplet discharge head, method for manufacturing the same and liquid droplet discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid droplet discharge head that achieves both vibration property on a vibration plate and resistance to organic solvent, and to provide a method for efficiently manufacturing the same, and a liquid droplet discharge device with the same.SOLUTION: An ink jet recording head 1 includes a substrate 20, a nozzle plate 10, a vibration plate composed of a vibration film 30 and a support plate 40, and a piezoelectric element 50. The substrate 20 and the nozzle plate 10, the substrate 20 and the vibration film 30, and the vibration film 30 and the support plate 40 are bonded to each other through resin layers 15, 25, 35, respectively. The resin layers are composed of a polyolefin-based resin covering both surfaces of the vibration film 30. The polyolefin-based resin contains polyethylene in the molecule structure thereof, and also, preferably contains unsaturated carboxylic acid and the derivative thereof.

Description

  The present invention relates to a droplet discharge head, a method for manufacturing a droplet discharge head, and a droplet discharge apparatus.

For example, a droplet discharge device such as an ink jet printer is provided with a droplet discharge head for discharging droplets. As such a droplet discharge head, for example, an ink chamber (cavity) that communicates with a nozzle that discharges ink as droplets and stores ink, and a piezoelectric element for driving that deforms the wall surface of the ink chamber, What is provided with is known.
In such a droplet discharge head, a part of the ink chamber (vibrating plate) is displaced by expanding and contracting the driving piezoelectric element. Thereby, the volume of the ink chamber is changed and ink droplets are ejected from the nozzles.

By the way, this droplet discharge head has a nozzle plate on which nozzles are formed, a substrate on which ink chambers are formed, a vibration plate that changes the volume of the ink chambers, and a piezoelectric element that vibrates the vibration plate due to strain. They are assembled by joining them together.
Further, the diaphragm has a vibration film that vibrates due to distortion of the piezoelectric element and a support plate that propagates the distortion of the piezoelectric element to the vibration film, and is assembled by joining them together (for example, , See Patent Document 1).
For the assembly (adhesion) of such various members, epoxy adhesives such as bisphenol or novolac, and various adhesives such as urethane adhesives are used.

  Here, for example, in the bonding between the ink chamber and the vibration plate or the bonding between the ink chamber and the nozzle plate, the adhesive is in contact with the ink stored in the ink chamber for a long time. It is required to have resistance (solvent resistance). Therefore, a urethane-based adhesive generally has low solvent resistance and has a property of being easily swollen by contact with a solvent, and thus is not suitable for joining such members.

In addition, for example, in joining the vibration film and the support plate, it is necessary to propagate the distortion of the piezoelectric element to the vibration film, so that excellent flexibility is required. However, epoxy adhesives such as bisphenol and novolak are generally highly rigid adhesives and are not suitable for joining such members.
In view of the above, there is a demand for a droplet discharge head that has a diaphragm with excellent vibration characteristics and has excellent resistance to solvents.

JP-A-4-21448

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid droplet ejection head that is highly compatible with vibration characteristics in a diaphragm and resistance to an organic solvent, a method for producing a liquid droplet ejection head capable of efficiently producing such a liquid droplet ejection head, and the liquid droplets. It is an object of the present invention to provide a droplet discharge device provided with a discharge head.

The above object is achieved by the present invention described below.
The droplet discharge head of the present invention includes a substrate on which a discharge liquid storage chamber for storing discharge liquid is formed,
A nozzle plate that is provided on one surface of the substrate so as to cover the discharge liquid storage chamber and includes nozzle holes for discharging the discharge liquid as droplets;
A diaphragm provided on the other surface of the substrate so as to cover the discharge liquid storage chamber,
The vibration plate includes a vibration film, a resin layer made of a polyolefin resin covering both surfaces of the vibration film, and a support plate provided on a surface opposite to the substrate of the vibration film,
The substrate and the vibration film, and the vibration film and the support plate are bonded via the resin layer.
As a result, a liquid droplet ejection head that achieves both high vibration characteristics in the diaphragm and resistance to organic solvents can be obtained.

In the liquid droplet ejection head of the present invention, it is preferable that the polyolefin-based resin includes polyethylene in a molecular structure.
As a result, a droplet discharge head having particularly excellent vibration characteristics and particularly excellent solvent resistance against an organic solvent can be obtained.
In the droplet discharge head of the present invention, it is preferable that the polyolefin-based resin further contains an unsaturated carboxylic acid or a derivative thereof in the molecular structure.
Thereby, a resin layer expresses more excellent adhesiveness irrespective of the material of the member used for adhesion.

In the droplet discharge head of the present invention, the unsaturated carboxylic acid is preferably maleic acid.
Maleic acid is highly compatible with polyolefin and has a particularly high adhesion enhancing action, and thus is useful as an additive in a resin layer composed of a polyolefin resin.
In the droplet discharge head of the present invention, it is preferable that the polyolefin resin covering one surface of the vibration film and the polyolefin resin covering the other surface have the same composition.
As a result, the vibration characteristics of the diaphragm are improved, and the discharge characteristics of the droplet discharge head can be improved.

In the droplet discharge head of the present invention, the average thickness of the resin layer is preferably 0.5 μm or more and 25 μm or less.
Thereby, sufficient adhesiveness can be ensured without reducing the dimensional accuracy of the droplet discharge head. As a result, a droplet discharge head with high printing accuracy and high solvent resistance can be obtained.

In the liquid droplet ejection head according to the aspect of the invention, it is preferable that the resin layer is bonded by fusion bonding.
Thereby, since the time for the curing reaction is not required, the adhesion can be completed in a short time, and the manufacturing efficiency of the droplet discharge head can be improved.
In the liquid droplet ejection head according to the aspect of the invention, it is preferable that the liquid droplet ejection head further includes a vibration unit that is provided in contact with the vibration plate and vibrates the vibration plate by strain.
Thereby, the volume of the discharge liquid storage chamber can be changed reliably, and accurate printing is enabled.

The method for manufacturing a droplet discharge head according to the present invention includes a substrate on which a discharge liquid storage chamber for storing discharge liquid is formed,
A nozzle plate that is provided on one surface of the substrate so as to cover the discharge liquid storage chamber and includes nozzle holes for discharging the discharge liquid as droplets;
It is provided on the other surface of the substrate so as to cover the discharge liquid storage chamber, and is opposite to the vibration film, a resin layer composed of a polyolefin resin covering both surfaces of the vibration film, and the substrate of the vibration film. A support plate provided on a surface, and a vibration plate comprising: a droplet discharge head manufacturing method comprising:
Forming a resin layer composed of a polyolefin-based resin so as to cover both surfaces of the vibration film;
Bonding the vibration film and the support plate by fusing the resin layer to obtain the vibration plate;
Laminating and adhering the diaphragm and the substrate through the resin layer;
Adhering the nozzle plate to the substrate.
As a result, it is possible to efficiently produce a liquid droplet ejection head having a diaphragm having excellent vibration characteristics and having excellent resistance to an organic solvent.

In the method for manufacturing a droplet discharge head of the present invention, the resin layer is preferably formed by applying a liquid containing the resin layer raw material on both surfaces of the vibration film and then drying the liquid.
Thereby, since the resin layer can be formed efficiently and inexpensively, the manufacturing efficiency of the droplet discharge head can be improved and the cost can be reduced.

In the method for manufacturing a droplet discharge head according to the present invention, a patterning process for removing unnecessary portions of the plate-shaped raw material after bonding a plate-shaped raw material serving as a raw material for the support plate to the vibration film by fusing the resin layer. It is preferable that the support plate is formed by applying the step to obtain the diaphragm.
As a result, the positional accuracy of the pattern formed on the diaphragm is increased, and as a result, the vibration characteristics of the diaphragm can be enhanced.
The liquid droplet ejection apparatus of the present invention has the liquid droplet ejection head of the present invention.
As a result, a droplet discharge device having high printing accuracy and excellent durability can be obtained.

1 is a longitudinal sectional view showing an embodiment in which a droplet discharge head of the present invention is applied to an ink jet recording head. It is the schematic which shows embodiment of an inkjet printer provided with the inkjet recording head shown in FIG. It is a figure (longitudinal sectional drawing) for demonstrating the manufacturing method of an inkjet recording head. It is a figure (longitudinal sectional drawing) for demonstrating the manufacturing method of an inkjet recording head. It is a figure (longitudinal sectional drawing) for demonstrating the manufacturing method of an inkjet recording head. It is a schematic diagram which shows an example of the adhesion state of a resin layer and a to-be-adhered member.

Hereinafter, a droplet discharge head, a method of manufacturing a droplet discharge head, and a droplet discharge apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<Inkjet recording head>
First, the droplet discharge head of the present invention will be described. Hereinafter, a case where the droplet discharge head of the present invention is applied to an ink jet recording head will be described as an example.

FIG. 1 is a longitudinal sectional view showing an embodiment in which the droplet discharge head of the present invention is applied to an ink jet recording head. FIG. 2 is a schematic view showing an embodiment of an ink jet printer including the ink jet recording head shown in FIG. It is. In the following description, the upper side in FIG. 1 is referred to as “upper” and the lower side is referred to as “lower”.
An ink jet recording head 1 shown in FIG. 1 (hereinafter sometimes simply referred to as “head 1”) is mounted on an ink jet printer (droplet discharge device of the present invention) 9 as shown in FIG.

The ink jet printer 9 shown in FIG. 2 includes an apparatus main body 92, a tray 921 in which the recording paper P is placed at the upper rear, a paper discharge port 922 for discharging the recording paper P in the lower front, and an operation panel on the upper surface. 97.
The operation panel 97 is composed of, for example, a liquid crystal display, an organic EL display, an LED lamp, and the like. And.

Further, inside the apparatus main body 92, mainly a printing apparatus (printing means) 94 provided with a reciprocating head unit 93 and a paper feeding apparatus (paper feeding means) for feeding recording paper P to the printing apparatus 94 one by one. 95 and a control unit (control means) 96 for controlling the printing device 94 and the paper feeding device 95.
Under the control of the control unit 96, the paper feeding device 95 intermittently feeds the recording paper P one by one. The recording paper P passes near the lower part of the head unit 93. At this time, the head unit 93 reciprocates in a direction substantially orthogonal to the feeding direction of the recording paper P, and printing on the recording paper P is performed. That is, the reciprocating motion of the head unit 93 and the intermittent feeding of the recording paper P are the main scanning and sub-scanning in printing, and ink jet printing is performed.

The printing apparatus 94 includes a head unit 93, a carriage motor 941 that is a drive source of the head unit 93, and a reciprocating mechanism 942 that reciprocates the head unit 93 in response to the rotation of the carriage motor 941.
The head unit 93 includes a head 1 having a large number of nozzle holes 11, an ink cartridge 931 that supplies ink to the head 1, and a carriage 932 on which the head 1 and the ink cartridge 931 are mounted at the lower part thereof.

Ink cartridge 931 is filled with four color inks of yellow, cyan, magenta, and black (black), thereby enabling full color printing.
The reciprocating mechanism 942 includes a carriage guide shaft 943 whose both ends are supported by a frame (not shown), and a timing belt 944 extending in parallel with the carriage guide shaft 943.

The carriage 932 is supported by the carriage guide shaft 943 so as to be able to reciprocate and is fixed to a part of the timing belt 944.
When the timing belt 944 travels forward and backward through the pulley by the operation of the carriage motor 941, the head unit 93 reciprocates as guided by the carriage guide shaft 943. During this reciprocation, ink is appropriately discharged from the head 1 and printing on the recording paper P is performed.

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

The control unit 96 performs printing by controlling the printing device 94, the paper feeding device 95, and the like based on print data input from a host computer such as a personal computer or a digital camera.
Although not shown, the control unit 96 mainly includes a memory that stores a control program for controlling each unit, a drive circuit that drives the printing device 94 (carriage motor 941), and a paper feeding device 95 (paper feeding motor 951). Drive circuit, a communication circuit for obtaining print data from a host computer, and a CPU that is electrically connected to these and performs various controls in each unit.

In addition, for example, various sensors that can detect the remaining amount of ink in the ink cartridge 931, the position of the head unit 93, and the like are electrically connected to the CPU.
The control unit 96 obtains the print data via the communication circuit and stores it in the memory. The CPU processes the print data and outputs a drive signal to each drive circuit based on the process data and input data from various sensors. The printing device 94 and the paper feeding device 95 are operated by this drive signal. As a result, printing is performed on the recording paper P.

Hereinafter, the head 1 will be described in detail with reference to FIG.
As shown in FIG. 1, the head 1 includes a nozzle plate 10, a discharge liquid storage chamber forming substrate (substrate) 20 provided on the nozzle plate 10, and a vibration film provided on the discharge liquid storage chamber forming substrate 20. 30, a support plate 40 provided on the vibration film 30, and a piezoelectric element (vibration means) 50 and a case head 60 provided on the support plate 40. In the present embodiment, the head 1 constitutes a piezo jet head.

A plurality of discharge liquid storage chambers (pressure chambers) 21 for storing ink are formed on the discharge liquid storage chamber forming substrate 20 (hereinafter referred to as “substrate 20” for short). A common discharge liquid supply chamber 22 that supplies ink to each discharge liquid storage chamber 21 is formed.
As shown in FIG. 1, each of the discharge liquid storage chambers 21 and the discharge liquid supply chambers 22 has a substantially rectangular shape in plan view, and the width (short side) of each of the discharge liquid storage chambers 21 is the discharge liquid supply chamber. It is narrower than the width (short side) of 22.
Further, each discharge liquid storage chamber 21 is arranged so as to be substantially perpendicular to the discharge liquid supply chamber 22, and each discharge liquid storage chamber 21 and the discharge liquid supply chamber 22 are comb-like in plan view. It has a shape.

The material constituting the substrate 20 is not particularly limited. For example, silicon materials such as single crystal silicon, polycrystalline silicon, and amorphous silicon, metal materials such as stainless steel, glass materials such as quartz glass, alumina Ceramic materials such as graphite, carbon materials such as graphite, polyolefins, polyvinyl chloride, acrylonitrile-styrene copolymers (AS resins), resin materials such as silicone resins, etc., one or more of these Can be used in combination.
Moreover, the material which gave each process, such as an oxidation process (oxide film formation), a plating process, a passivation process, a nitriding process, to the above materials may be used.

  Among these, the constituent material of the substrate 20 is preferably a silicon material or stainless steel. Since such a material is excellent in chemical resistance, even if it is exposed to ink for a long time, the substrate 20 can be reliably prevented from being deteriorated or deteriorated. Moreover, since these materials are excellent in workability, the substrate 20 with high dimensional accuracy can be obtained. For this reason, the accuracy of the volume of the discharge liquid storage chamber 21 and the discharge liquid supply chamber 22 is increased, and the head 1 capable of high-quality printing is obtained.

Further, the discharge liquid supply chamber 22 communicates with a discharge liquid supply path 61 provided in a case head 60 described later, and is a part of a reservoir 70 that functions as a common ink chamber that supplies ink to the plurality of discharge liquid storage chambers 21. Parts.
The nozzle plate 10 is bonded to the lower surface of the substrate 20 (the surface opposite to the vibration film 30) so as to cover the discharge liquid storage chamber 21 and the discharge liquid supply chamber 22 via the resin layer 15.

Nozzle holes 11 are formed (perforated) in the nozzle plate 10 so as to correspond to the respective discharge liquid storage chambers 21. By extruding the ink (discharge liquid) stored in the discharge liquid storage chamber 21 from the nozzle hole 11, the ink is discharged as droplets.
Further, the nozzle plate 10 constitutes the lower surface of the inner wall surface of each discharge liquid storage chamber 21 and the discharge liquid supply chamber 22. That is, each of the discharge liquid storage chambers 21 and the discharge liquid supply chamber 22 is defined by the nozzle plate 10, the substrate 20, and the vibration film 30.

Examples of the material constituting the nozzle plate 10 include silicon materials, metal materials, glass materials, ceramic materials, carbon materials, resin materials, or one or more of these materials as described above. The composite material etc. which were combined are mentioned.
Among these, it is preferable that the constituent material of the nozzle plate 10 is a silicon material or stainless steel. Since such a material is excellent in chemical resistance, it is possible to reliably prevent the nozzle plate 10 from being altered or deteriorated even when exposed to ink for a long time. Moreover, since these materials are excellent in workability, the nozzle plate 10 with high dimensional accuracy can be obtained. For this reason, the highly reliable head 1 is obtained.

The constituent material of the nozzle plate 10 is preferably a material having a linear expansion coefficient of about 2.5 × 10 ⁻⁶ / ° C. to 4.5 × 10 ⁻⁶ / ° C. at 300 ° C. or lower.
The thickness of the nozzle plate 10 is not particularly limited, but is preferably about 0.01 mm or more and 1 mm or less.
Moreover, it is preferable to perform a liquid repellent treatment on the lower surface of the nozzle plate 10 as necessary. Thereby, it is possible to prevent ink droplets ejected from the nozzle holes from being ejected in unintended directions.

A vibration film 30 is bonded to the upper surface (the other surface) of the substrate 20 through the resin layer 25 so as to cover the discharge liquid storage chamber 21 and the discharge liquid supply chamber 22.
The vibration film 30 constitutes the upper surface of the inner wall surface of each discharge liquid storage chamber 21 and the discharge liquid supply chamber 22. That is, each of the discharge liquid storage chambers 21 and the discharge liquid supply chamber 22 is defined by the vibration film 30, the substrate 20, and the nozzle plate 10. In addition, since the vibration film 30 is securely bonded to the substrate 20, the liquid tightness of each discharge liquid storage chamber 21 and the discharge liquid supply chamber 22 is ensured.

Furthermore, the vibration film 30 has a function of elastic deformation. Therefore, the volume of the discharge liquid storage chamber 21 can be changed by displacing (vibrating) the vibration film 30 via the support plate 40 due to the distortion generated in the piezoelectric element 50. As a result, ink is discharged. The
Examples of the material constituting the vibration film 30 include a silicon material, a metal material, a glass material, a ceramic material, a carbon material, a resin material, or a combination of one or more of these materials as described above. Materials and the like.

  Among these, the constituent material of the vibration film 30 is preferably a resin material such as polyphenylene sulfide (PPS) or an aramid resin, a silicon material, or stainless steel. Since such a material is excellent in chemical resistance, even if it is exposed to ink for a long time, the vibration film 30 can be reliably prevented from being altered or deteriorated. For this reason, ink can be stored in the discharge liquid storage chamber 21 and the discharge liquid supply chamber 22 for a long period of time. Furthermore, since these are materials that can be elastically deformed at high speed, the volume of the discharge liquid storage chamber 21 can be changed at high speed, and as a result, ink can be discharged with high accuracy.

A support plate 40 is bonded to the upper surface of the vibration film 30 via a resin layer 35 so as to correspond to a part of the vibration film 30.
The support plate 40 has a function of propagating the distortion generated in the piezoelectric element 50 to the vibration film 30 through this. Accordingly, by generating distortion in the piezoelectric element 50, the vibration film 30 is displaced, and as a result, a volume change in each discharge liquid storage chamber 21 can be surely generated.

Examples of the material constituting the support plate 40 include a silicon material, a metal material, a glass material, a ceramic material, a carbon material, a resin material, or a combination of one or more of these materials as described above. Materials and the like.
Among these, it is preferable that the constituent material of the support plate 40 is a silicon material or stainless steel (SUS). Such a material has excellent strength. For this reason, the distortion generated in the piezoelectric element 50 is more reliably transmitted to the vibration film 30, so that the ink is ejected with higher accuracy.

In the present embodiment, the vibration plate (sealing plate) that covers the discharge liquid storage chamber 21 and the discharge liquid supply chamber 22 by the laminate in which the vibration film 30 and the support plate 40 are bonded via the resin layer 35 described above. ) Is configured.
A piezoelectric element (vibrating means) 50 is bonded to a part of the upper surface of the support plate 40 (in FIG. 1, near the center of the upper surface of the support plate 40).

  The piezoelectric element 50 is constituted by a laminate of a piezoelectric layer 51 made of a piezoelectric material and an electrode film 52 that applies a voltage to the piezoelectric layer 51. In such a piezoelectric element 50, when a voltage is applied to the piezoelectric layer 51 through the electrode film 52, a distortion corresponding to the voltage is generated in the piezoelectric layer 51 (reverse piezoelectric effect). This distortion causes the vibration film 30 to bend (vibrate) via the support plate 40 and change the volume of the discharge liquid storage chamber 21. Since the piezoelectric element 50 having such a structure is reliably bonded to the support plate 40, the distortion generated in the piezoelectric element 50 can be reliably converted into the displacement of the vibration film 30 via the support plate 40. As a result, the volume of each discharge liquid storage chamber 21 is reliably changed.

  The lamination direction of the piezoelectric layer 51 and the electrode film 52 is not particularly limited, and may be a direction parallel to the support plate 40 or a direction orthogonal thereto. In addition, when the stacking direction of the piezoelectric layer 51 and the electrode film 52 is a direction orthogonal to the support plate 40 as shown in FIG. Say Layer Piezo). If the piezoelectric element 50 is MLP, the displacement amount of the support plate 40 can be increased, which has the advantage that the adjustment range of the ink ejection amount is large.

The surface of the piezoelectric element 50 adjacent to (in contact with) the support plate 40 differs depending on the arrangement method of the piezoelectric element 50, but the surface on which the piezoelectric layer is exposed, the surface on which the electrode film is exposed, or the piezoelectric layer and the electrode Either side of the membrane is exposed.
As a material constituting the piezoelectric layer 51 in the piezoelectric element 50, for example, barium titanate, lead zirconate, lead zirconate titanate, zinc oxide, aluminum nitride, lithium tantalate, lithium niobate, crystal, and the like are available. Can be mentioned.

On the other hand, as a material constituting the electrode film 52, for example, various metal materials such as Fe, Ni, Co, Zn, Pt, Au, Ag, Cu, Pd, Al, W, Ti, Mo, or an alloy containing them. Is mentioned.
Here, the support plate 40 described above has a recess 53 formed in an annular shape in plan view so as to surround a position corresponding to the piezoelectric element 50. That is, the support plate 40 is provided on a part of the vibration film 30, and at a position corresponding to the piezoelectric element 50, a part of the support plate 40 is isolated in an island shape with the annular recess 53 interposed therebetween. ing. By adopting a configuration in which the piezoelectric element 50 is joined to such an island-shaped portion, distortion generated in the piezoelectric element 50 can be more reliably propagated to the vibration film 30, so that the bending in the vibration film 30 is prevented. It will occur more reliably.

The electrode film 52 of the piezoelectric element 50 is electrically connected to a drive IC (not shown). Thereby, the operation of the drive element 50 can be controlled by the drive IC.
Further, the case head 60 is joined to a part of the upper surface of the support plate 40 (in FIG. 1, a portion surrounding the island-shaped portion with the recess 53 therebetween). In this way, the case head 60 and the support plate 40 are joined to reinforce a so-called cavity portion composed of a laminate of the nozzle plate 10, the substrate 20, the vibration film 30 and the support plate 40. The tee portion can be reliably prevented from being twisted or warped.

Examples of the material constituting the case head 60 include a silicon material, a metal material, a glass material, a ceramic material, a carbon material, a resin material, or a combination of one or more of these materials as described above. Materials and the like.
Among these, the constituent material of the case head 60 is preferably polyphenylene sulfide (PPS), a modified polyphenylene ether resin such as Zylon (“Zylon” is a registered trademark), or stainless steel. Since these materials have sufficient rigidity, they are suitable as constituent materials for the case head 60 that supports the head 1.

  Further, the vibration film 30, the resin layer 35, and the support plate 40 have a through hole 23 at a position corresponding to the discharge liquid supply chamber 22. Through the through hole 23, the discharge liquid supply path 61 provided in the case head 60 and the discharge liquid supply chamber 22 communicate with each other. The discharge liquid supply path 61 and the discharge liquid supply chamber 22 constitute a part of a reservoir 70 that functions as a common ink chamber that supplies ink to the plurality of discharge liquid storage chambers 21.

  In such a head 1, after taking ink from an external discharge liquid supply means (not shown) and filling the interior from the reservoir 70 to the nozzle hole 11 with the ink, each discharge liquid storage chamber 21 is received by a recording signal from the drive IC. Each piezoelectric element 50 corresponding to is operated. Accordingly, the vibration film 30 is bent (vibrated) via the support plate 40 due to the reverse piezoelectric effect of the piezoelectric element 50. As a result, for example, when the volume in each discharge liquid storage chamber 21 contracts, the pressure in each discharge liquid storage chamber 21 increases instantaneously, and ink is pushed out (discharged) from the nozzle hole 11 as a droplet.

In this way, in the head 1, a voltage is applied to the piezoelectric element 50 at a position to be printed via the driving IC, that is, an arbitrary character is printed as a figure or the like by sequentially inputting ejection signals. Can do.
The head 1 is not limited to the configuration described above, and may include, for example, an electrostatic actuator instead of the piezoelectric element 50 serving as a vibration unit.

However, as in the present embodiment, since the vibration means is configured by a piezoelectric element, the degree of bending that occurs in the vibration film 30 can be easily controlled. As a result, the size of the ink droplet can be easily controlled.
Here, among the resin layers 15, 25, and 35 described above, at least the resin layers 25 and 35 are each made of a polyolefin resin.

  Polyolefin resins are low in polarity and chemically stable, and therefore basically have poor adhesion. For this reason, it has hitherto been considered unsuitable for bonding a highly liquid-tight portion, for example, a portion where contact with an organic solvent cannot be avoided, such as an ink jet recording head. Therefore, in the conventional ink jet recording head, an adhesive composed of a thermosetting resin such as an epoxy resin or a urethane resin has been mainly used.

However, some of these adhesives have low solvent resistance, and there are cases where the adhesiveness is lowered when they are in contact with ink for a long time. In addition, these adhesives have poor flexibility after curing, and thus have an adverse effect on the vibration characteristics of the diaphragm.
Therefore, the present inventor, as a structure of the head 1 that can simultaneously solve the above problems, each resin layer 25, 35 is made of polyolefin resin, and the resin layer 25 covers the lower surface of the vibration film 30. The present inventors have found a structure in which the resin layer 35 is provided so as to cover the resin film 35 so as to cover the upper surface of the vibration film 30, and the present invention has been completed.

  According to the present invention as described above, the upper surface and the lower surface of the vibration film 30 are each covered with the polyolefin-based resin. As described above, since the polyolefin resin has low polarity and is chemically stable, when both surfaces of the vibration film 30 are covered with such a resin, the vibration film 30 is isolated from contact with ink. It becomes. As a result, it is possible to prevent the vibration characteristics of the vibration film 30 from changing due to the vibration film 30 being attacked or swollen by the solvent contained in the ink.

  In addition, since the polyolefin-based resin is generally high in flexibility, even if the upper and lower surfaces of the vibration film 30 are covered, the vibration characteristics of the vibration film 30 are hardly adversely affected. For this reason, the vibration film 30 and the vibration plate including the vibration film 30 can vibrate with sufficient amplitude by the piezoelectric element 50, and the droplet discharge performance can be improved. In addition, since a sufficient amplitude can be obtained even with a relatively small driving waveform, the diaphragm can realize various vibration patterns, and the head 1 can perform various printing.

Moreover, it is preferable that each resin layer 25 and 35 is expressing adhesiveness by melt | fusion. Since the fusion does not cure the resin but develops adhesiveness through melting and re-solidification, it does not require time for the curing reaction. For this reason, adhesion can be completed in a very short time by fusing the members in the resin layers 25 and 35, which is preferable from the viewpoint of manufacturing efficiency. Note that the adhesive used in the conventional head needs to secure a long curing time at the time of curing and is difficult to manufacture easily. Can be solved.
For the reasons described above, the head 1 can simultaneously and highly solve various problems in the conventional head.

In the present embodiment, it is sufficient that at least the resin layers 25 and 35 have the above-described matters, but in the present embodiment, the resin layer 15 will be described as having the above-mentioned matters.
The polyolefin resin constituting each of the resin layers 15, 25, and 35 may be any resin as long as it contains a polyolefin in its molecular structure. Specific examples of the polyolefin include a random copolymer of propylene and one or both of ethylene and 1-butene in addition to a homopolymer such as polyethylene, polypropylene, poly-1-butene, polyisobutylene and polymethylpentene. Or a block copolymer, an ethylene-propylene-diene terpolymer containing ethylene, propylene and a diene component, a copolymer of cyclopentadiene and one or both of ethylene and propylene, ethylene or propylene and a vinyl compound A random copolymer, a block copolymer, etc. are mentioned.

  Among these, polyethylene is preferably used. A resin containing polyethylene has particularly high flexibility (particularly low Young's modulus), has relatively high solvent resistance, and high adhesion by fusion. For this reason, each of the resin layers 15, 25, and 35 made of such a resin has particularly high vibration characteristics (such as high followability to vibration) of the diaphragm, and excellent solvent resistance with respect to the vibration film 30. It is possible to impart properties and easily bond.

  Such a polyolefin resin may further include an arbitrary structure (functional group-containing structure) for firmly bonding the polyolefin to the adherend in the molecular structure. Examples of such structures include unsaturated carboxylic acids or derivatives thereof, glycidyl group-containing unsaturated compounds, vinyl group-containing compounds, etc. Among them, those containing unsaturated carboxylic acids or derivatives thereof are preferably used. Such a polyolefin-based resin exhibits better adhesiveness regardless of the material of the member used for adhesion.

Unsaturated carboxylic acid or a derivative thereof generates a hydrogen bond to a member to be bonded, so that the adhesion of the polyolefin resin can be further improved.
Examples of the unsaturated carboxylic acid include maleic acid, maleic anhydride, fumaric acid, citraconic acid, citraconic anhydride, itaconic acid, itaconic anhydride, crotonic acid, isocrotonic acid, acrylic acid, and the like. One of them or two or more of them are used in combination. Moreover, as a derivative | guide_body of unsaturated carboxylic acid, the metal salt, amide, imide, ester, etc. of the said unsaturated carboxylic acid are mentioned.
Among these, maleic acid is preferably used. Maleic acid is highly compatible with polyolefin and has particularly excellent adhesion enhancing action. For this reason, the polyolefin resin containing maleic acid is particularly useful as a constituent material of the resin layers 15, 25, and 35 that can simultaneously solve the above-described problems.

  In addition, unsaturated carboxylic acid or its derivative forms a copolymer with the polyolefin mentioned above. This copolymer may be any of various copolymers such as random copolymers, block copolymers, alternating copolymers, and graft copolymers having a polyolefin as the main chain, but preferably unsaturated. The copolymer is formed by addition polymerization so that the unsaturated bond in the carboxylic acid or derivative thereof constitutes a part of the main chain of the polyolefin. Since such a copolymer has a structure in which a functional group that generates a hydrogen bond is firmly bonded to the main chain of the polyolefin, the polyolefin resin is particularly excellent in adhesion to an adherend. Will be shown.

FIG. 6 is a schematic diagram illustrating an example of a bonding state between each resin layer 15, 25, 35 and the member to be bonded. FIG. 6 shows a state in which a copolymer formed by addition polymerization of an unsaturated bond of maleic acid to a polyethylene main chain is adhered to an adherend.
In general, hydroxyl groups are often exposed on the surface of the adherend. Moreover, even when it is not exposed, a hydroxyl group is introduced by a general ground treatment. When a hydrogen bond is generated between the hydroxyl group and a hydroxyl group derived from maleic acid, a strong adhesive force is generated between each of the resin layers 15, 25, and 35 and the member to be bonded.

Specific examples of the copolymer include maleic acid-modified polyethylene, maleic anhydride-modified polyethylene, maleic acid-modified polypropylene, maleic anhydride-modified polypropylene, and the like.
Although the content rate of the arbitrary structure mentioned above is not specifically limited, It is preferable that it is 0.001 mass part or more and 20 mass parts or less with respect to 100 mass parts of polyolefin, and is 0.01 mass part or more and 15 mass parts or less. Is more preferably 0.05 parts by mass or more and 10 parts by mass or less. If the content of the structure is within the above range, stronger adhesiveness can be imparted to the polyolefin-based resin without impairing the physical properties inherent in the polyolefin.

The weight average molecular weight of the polyolefin resin is not particularly limited, but is preferably 10,000 or more and 100,000 or less, more preferably 20,000 or more and 80,000 or less. In addition, a weight average molecular weight can be calculated | required by measuring with gel permeation chromatography (GPC) and converting with standard polystyrene.
The average thickness of each resin layer 15, 25, 35 is preferably 0.5 μm or more and 25 μm or less, and more preferably 2 μm or more and 10 μm or less. By setting the average thickness of each resin layer 15, 25, 35 within the above range, sufficient adhesion can be ensured without reducing the dimensional accuracy of the head 1. As a result, the head 1 with high printing accuracy and high solvent resistance can be obtained.

  The polyolefin resin constituting the resin layer 25 provided on the lower surface of the vibration film 30 and the polyolefin resin constituting the resin layer 35 provided on the upper surface may have different compositions from each other, The same composition is preferred. Thereby, the vibration characteristics of the diaphragm are further improved, and the ejection characteristics of the head 1 are improved. Further, since the structure of the diaphragm is simplified and the manufacture becomes easy, it is effective from the viewpoint of the manufacturing efficiency of the head 1.

In addition, the polyolefin resin constituting the resin layer 15 provided on the lower surface of the substrate 20 preferably has the same composition as the polyolefin resin constituting the two resin layers 25 and 35. This simplifies the structure of the head 1 and facilitates manufacturing, which is useful from the viewpoint of manufacturing efficiency of the head 1.
In addition to the essential components such as polyolefin described above, each resin layer 15, 25, 35 is a component such as an antioxidant, an ultraviolet absorber, a crosslinking agent, a lubricant, a plasticizer, an antistatic agent, an emulsifier, or a reaction thereof. It may contain products and the like.

The resin layer 15 may be composed of other adhesives. Examples of other adhesives include epoxy adhesives, silicone adhesives, urethane adhesives, and the like.
Further, in bonding the piezoelectric element 50 and the case head 60, an adhesive made of the above-described polyolefin resin can be used, and other adhesives can also be used.

<Method for producing ink jet recording head>
Next, a method for manufacturing the droplet discharge head of the present invention will be described. Hereinafter, a case where the method for manufacturing a droplet discharge head according to the present invention is applied to a method for manufacturing an ink jet recording head will be described as an example.
3 to 5 are views (longitudinal sectional views) for explaining a method of manufacturing the ink jet recording head. In the following description, the upper side in FIGS. 3 to 5 is referred to as “upper” and the lower side is referred to as “lower”.
The method for manufacturing the head 1 according to the present embodiment includes: [1] a step of forming a resin layer on both surfaces of the vibration film 30; and [2] a step of bonding the vibration film 30 and the support plate 40 to obtain a vibration plate. And [3] a step of bonding the diaphragm and the substrate 20 and [4] a step of bonding the nozzle plate 10 to the substrate 20.

Hereinafter, each process will be described sequentially.
[1] First, the resin layer 25 is formed on the lower surface of the vibration film 30 and the resin layer 35 is formed on the upper surface.
The resin layers 25 and 35 are formed by a method of laminating a thin film containing the raw material, a method of applying a liquid containing the raw material (liquid raw material), and then drying.

Of these, the latter method is preferably used. According to the latter method, the resin layers 25 and 35 can be formed efficiently and inexpensively, which contributes to an improvement in manufacturing efficiency and cost reduction of the head 1.
As the liquid raw material, an aqueous dispersion medium or an aqueous solution of the raw material for the resin layers 25 and 35 is used. Such a liquid raw material is prepared, for example, by stirring the raw material, the above-described components added as necessary, and an aqueous medium. The stirring method, stirring conditions, and the like are not particularly limited, but stirring under heating is preferable.

Further, the solid content concentration in the liquid raw material is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.
Examples of the aqueous medium include water and alcohols.
The liquid raw material may be applied to the upper and lower surfaces of the vibration film 30 by any method. Examples of the method include screen printing, gravure printing, microgravure, dip coat printing, bar coater coating, and roll coater coating. And various methods such as lip coater coating and spray coater coating.

In addition, the application surface of the vibration film 30 may be subjected to a surface treatment as necessary. Examples of the surface treatment include corona discharge treatment, plasma discharge treatment, ultraviolet irradiation treatment, ozone treatment, and ultrasonic cleaning.
In addition, drying is performed after the liquid material is applied. The drying temperature is preferably 40 ° C. or higher and 200 ° C. or lower, and more preferably 50 ° C. or higher and 170 ° C. or lower. Further, the drying time is preferably 10 seconds or more and 600 seconds or less, and more preferably 20 seconds or more and 180 seconds or less.

[2] Next, the vibration film 30 and the support plate 40 are laminated to obtain a vibration plate.
When the support plate 40 is patterned in accordance with the shape of the piezoelectric element 50, a previously patterned one may be laminated, or a non-patterned one may be laminated and then patterned. . In the latter case, it is not necessary to perform the bonding operation while aligning, so that the positional accuracy of the pattern is improved, and this is useful in that the vibration characteristics of the diaphragm are improved. On the other hand, the former case is useful in that it does not contaminate the resin layer during patterning although the difficulty of the bonding operation is high. Here, the latter case will be described.

First, the support plate forming substrate 41 is laminated on the resin layer 35 formed on the upper surface of the vibration film 30. The support plate forming substrate 41 has a shape that covers the upper surface of the vibration film 30.
Next, the vibration film 30 and the support plate forming substrate 41 are laminated via the resin layer 35, and the obtained laminate is pressed in the thickness direction. Thereby, the vibration film 30 and the support plate forming substrate 41 are bonded via the resin layer 35.

The pressure at the time of pressurization is not particularly limited and is appropriately set according to the material of the adherend member, but is preferably 0.01 MPa or more and 10 MPa or less, more preferably 0.05 MPa or more and 5 MPa or less. preferable. Thereby, necessary and sufficient adhesive force is obtained in each resin layer 15, 25, 35.
Further, the pressure treatment is performed under heating as necessary. The heating temperature at that time is preferably 80 ° C. or higher and 300 ° C. or lower, and more preferably 100 ° C. or higher and 250 ° C. or lower. Thereby, the polyolefin-based resin is melted, and the adherend member is firmly bonded by the subsequent re-solidification. In addition, when the polyolefin resin has a polar group, adhesion by hydrogen bonding is enhanced. As a result, a diaphragm having excellent vibration characteristics can be obtained.

The pressurization time is preferably 0.1 second or more and 20 seconds or less, more preferably 0.5 second or more and 10 seconds or less. Thereby, it is possible to efficiently and firmly bond without altering the member to be bonded.
Thereafter, the support plate forming substrate 41 is subjected to patterning to remove unnecessary portions, thereby forming the support plate 40. Thereby, a diaphragm is obtained.

For this patterning process, a method using one or a combination of two or more of physical etching methods such as dry etching, reactive ion etching, beam etching, and light-assisted etching, and chemical etching methods such as wet etching is used. It is done.
In addition, since what laminated | stacked 4 layers, the resin layer 25, the vibration film 30, the resin layer 35, and the support plate formation board | substrate 41 can be manufactured and stored in large quantities beforehand, it is useful from a viewpoint of manufacturing efficiency. is there. In that case, by using a base material for a vibration film having a long band shape, it can be wound and stored in a roll shape, which is useful from the viewpoint of storage efficiency and ease of conveyance in the subsequent process. is there.
Moreover, it is preferable that the adhesive surface of the support plate 40 is subjected to the surface treatment as described above. Thereby, the bond strength of the hydrogen bond is further increased.

[3] Next, the diaphragm and the substrate 20 are bonded.
[3-1] As the substrate 20, a flat base material 20 'as shown in FIG. 3B is prepared, and processed to give each discharge liquid storage chamber as shown in FIG. 3C. 21 and the discharge liquid supply chamber 22 are formed.
The formation of the discharge liquid storage chamber 21 and the discharge liquid supply chamber 22 is one of physical etching methods such as dry etching, reactive ion etching, beam etching, and light-assisted etching, and chemical etching methods such as wet etching. Or it can carry out using combining 2 or more types.

Next, the diaphragm and the substrate 20 are laminated via the resin layer 25, and the obtained laminate is pressed in the thickness direction. As a result, as shown in FIG. 3D, the diaphragm (vibrating film 30) and the substrate 20 are bonded via the resin layer 25.
The pressurizing conditions and the like are the same as in the above process.
In the present embodiment, the vibration film 30 and the support plate 40 are bonded to obtain the vibration plate, and then the obtained vibration plate and the substrate 20 are bonded. And the vibration film 30 and the substrate 20 may be bonded at the same time. Thereby, the further improvement of manufacturing efficiency is achieved.

On the other hand, when bonding the two locations individually, when bonding the vibration film 30 and the support plate 40, the surface of the resin layer 25 is not contaminated or unintentionally bonded to other members. What is necessary is just to make it cover with the protective film etc. which have peelability.
In addition, it is preferable to perform the surface treatment as described above on the bonding surface of the substrate 20 in advance. Thereby, the bond strength of the hydrogen bond is further increased.

[3-2] Subsequently, as shown in FIG. 4A, a position corresponding to the discharge liquid supply chamber 22 of the substrate 20 among the vibration film 30, the resin layer 35, and the support plate 40, that is, the discharge liquid. A through hole 23 is formed so as to communicate with the supply chamber 22. Furthermore, the recessed part 53 is formed in the cyclic | annular area | region surrounding the position where the piezoelectric element 50 is assembled among the support plates 40. FIG.
The through holes 23 and the recesses 53 are formed by using various etching methods similar to those described in the above-described formation of the discharge liquid storage chamber 21 and the discharge liquid supply chamber 22.

[3-3] Next, the piezoelectric element 50 is prepared, and the piezoelectric element 50 is joined to the island-shaped portion of the support plate 40, so that the diaphragm and the piezoelectric element as shown in FIG. 50.
[3-4] Next, the case head 60 is prepared, and the case head 60 is joined to the upper surface of the diaphragm, thereby joining the diaphragm and the case head 60 as shown in FIG.
At this time, the discharge liquid supply chamber 22 communicates with the vibration film 30, the through hole 23 formed in the resin layer 35 and the support plate 40, and the discharge liquid supply path 61 provided in the case head 60. A reservoir 70 is formed.

  In the above description, the vibration film 30, the support plate 40, the piezoelectric element 50, and the substrate 20 on which the base material 20 ′ is previously processed to form the respective discharge liquid storage chambers 21 and the discharge liquid supply chambers 22 are provided. Although the case where the case head 60 is bonded has been described, the method for manufacturing the head 1 is not limited to this, and after the vibration film 30, the support plate 40, the piezoelectric element 50, and the case head 60 are bonded to the base material 20 ′. Alternatively, the base material 20 ′ may be processed to form the discharge liquid storage chamber 21 and the discharge liquid supply chamber 22 to obtain the substrate 20.

[4] Next, the nozzle plate 10 is prepared, and the substrate 20 and the nozzle plate 10 are bonded via the resin layer 15 as shown in FIG. Thereby, the head 1 is obtained.
The resin layer 15 can be formed in the same manner as the resin layers 25 and 35 described above.
Moreover, not only the adhesion via the resin layer 25 and the resin layer 35 but also the adhesion via the resin layer 15 can be performed simultaneously. That is, adhesion through the three resin layers 15, 25, and 35 can be performed simultaneously. Thereby, the further improvement of manufacturing efficiency is achieved.

Although the droplet discharge head, the method for manufacturing the droplet discharge head, and the droplet discharge apparatus have been described based on the illustrated embodiments, the present invention is not limited to these.
For example, in the method of manufacturing the droplet discharge head of the present invention, the order of the steps may be changed without being limited to the configuration of the above embodiment. In addition, one or two or more processes for an arbitrary purpose may be added, and unnecessary processes may be added.

Next, specific examples of the present invention will be described.
1. Production of inkjet recording head (Example 1)
<1> First, a vibration film made of polyphenylene sulfide (PPS) was prepared, and a liquid raw material for a resin layer was applied to the entire both surfaces by a microgravure method. The application surface of the vibration film was previously subjected to corona discharge treatment. As the liquid raw material, one containing maleic acid-modified polyethylene and an aqueous medium (water, isopropyl alcohol) was used.

  Subsequently, the coating film was dried by heating at 150 ° C. for 3 minutes. As a result, a resin layer having an average thickness of 5 μm composed of maleic acid-modified polyethylene (polyolefin resin) was formed. The maleic acid-modified polyethylene contains a maleic acid-derived site at a ratio of 0.5 parts by mass with respect to 100 parts by mass of polyethylene. The weight average molecular weight of the maleic acid-modified polyethylene was about 50,000. Furthermore, the maleic acid-modified polyethylene used is obtained by copolymerization such that unsaturated bonds in maleic acid are addition-polymerized to polyethylene and constitute a part of the main chain.

<2> Next, a stainless steel foil was prepared as a support plate forming substrate. And stainless steel foil was laminated | stacked through the resin layer formed into a film on one surface of the vibration film. Then, the vibration film and the stainless steel foil were bonded by pressurizing in the thickness direction at a pressure of 0.15 MPa and a temperature of 200 ° C. for 2 seconds.
Next, after a resist film was formed on the stainless steel foil, the resist film was patterned by a photolithography technique and an etching technique. Then, the stainless steel foil was etched using the patterned resist film as a mask, and patterned into a predetermined shape. In addition, a through hole for the reservoir was formed by etching. Thereafter, the resist film was removed to obtain a diaphragm.

<3> Next, a base material made of single crystal silicon was prepared, and the base material was processed by photolithography technique and etching technique to form each discharge liquid storage chamber and discharge liquid supply chamber. Thereby, a discharge liquid storage chamber forming substrate was obtained.
Next, a discharge liquid storage chamber forming substrate was laminated via a resin layer formed on the other surface of the vibration film. And the vibration film and the discharge liquid storage chamber formation board | substrate were adhere | attached by pressurizing for 2 second at the pressure of 0.15 MPa and the temperature of 200 degreeC in the thickness direction.
In addition, a piezoelectric element and a case head were prepared, and these were also bonded using a resin layer similar to the resin layer.

<4> Next, a stainless steel nozzle plate was prepared, and a resin layer having an average thickness of 5 μm composed of the same polyolefin-based resin as described above was formed on one surface thereof. And the nozzle plate and the discharge liquid storage chamber formation board | substrate were laminated | stacked through the formed resin layer. Then, the discharge liquid storage chamber forming substrate and the nozzle plate were bonded by pressurizing for 2 seconds at a pressure of 0.15 MPa and a temperature of 200 ° C. in the thickness direction.
An ink jet recording head was obtained as described above.

(Examples 2 to 15)
An ink jet recording head was obtained in the same manner as in Example 1 except that the composition of the polyolefin resin used was changed as shown in Table 1.
(Example 16)
An ink jet recording head was obtained in the same manner as in Example 1 except that a polyethylene film (average thickness: 5 μm) was used as the resin layer, and the film was laminated and fused via the polyethylene film.
(Example 17)
An ink jet recording head was obtained in the same manner as in Example 1 except that the composition of the polyolefin resin to be formed on the both surfaces of the vibration film was different from each other.

(Comparative Example 1)
An ink jet recording head was obtained in the same manner as in Example 1 except that an epoxy adhesive was used instead of each resin layer composed of a polyolefin resin.
At the time of adhesion, after applying the adhesive, the adherend member was bonded before curing, and kept in that state for 1 day.

(Comparative Example 2)
An ink jet recording head was obtained in the same manner as in Example 1 except that a urethane adhesive was used instead of each resin layer composed of a polyolefin resin.
At the time of adhesion, after applying the adhesive, the adherend member was bonded before curing, and kept in that state for 1 day.

(Comparative Example 3)
Of the two resin layers formed on both surfaces of the vibration film, ink jet recording is performed in the same manner as in Example 1 except that an epoxy adhesive is used for the resin layer that bonds the support plate and the vibration film. Got the head.
At the time of adhesion, after applying the adhesive, the adherend member was bonded before curing, and kept in that state for 1 day.

(Comparative Example 4)
When adhering the vibration film and the discharge liquid storage chamber forming substrate, the resin layer is not formed on the vibration film side, but is formed on the upper surface of the discharge liquid storage chamber forming substrate, and is adhered through this. Except for the above, an ink jet recording head was obtained in the same manner as in Example 1. In this way, in the obtained ink jet recording head, the vibration film is exposed in the discharge liquid storage chamber.
Table 1 shows the manufacturing conditions of the ink jet recording head.

2. Evaluation of Inkjet Recording Head Using the inkjet recording head obtained in each Example and each Comparative Example, a long-term ejection operation was performed in which inks a to c composed of the following three types of solvents were continuously ejected on the substrate for 1000 hours.
<Three types of ink>
Ink a: N-methyl-2-pyrrolidone Ink b: γ-butyrolactone Ink c: Butyl cellosolve Then, the following evaluations were performed on the behavior of the head and ink when ejection was temporarily stopped and ejected again.

2-1. Evaluation of Variation in Ink Ejection Speed First, variation in the average value of the speed of ink ejected from the ink jet recording head was measured. And the measurement result was evaluated according to the evaluation criteria shown below.
<Evaluation criteria for fluctuations in discharge speed>
A: Speed variation is less than ± 2% B: Speed variation is ± 2% or more and less than 5% C: Speed variation is ± 5% or more and less than 10% D: Speed variation is ± 10% or more and less than 20% E : Speed variation is ± 20% or more, or an ejection port that does not eject ink occurs

2-2. Evaluation of Inflection of Ink Flight Next, the amount of deviation of the landing position of the ink ejected from the ink jet recording head was measured. And the measurement result was evaluated according to the evaluation criteria shown below.
<Evaluation criteria for flight curve>
A: Flight curve is less than 5 μm B: Flight curve is from 5 μm to less than 10 μm C: Flight curve is from 10 μm to less than 20 μm D: Flight curve is from 20 μm to less than 30 μm E: Flight curve is from 30 μm to less than 40 μm

2-3. Evaluation of frequency correction Next, regarding the voltage applied to the piezoelectric element that vibrates the vibration plate of the ink jet recording head, correction of the voltage necessary to stabilize the ink ejection operation (to stabilize vibration of the vibration plate) The amount was measured. And the measurement result was evaluated according to the evaluation criteria shown below.

<Evaluation criteria for frequency correction>
A: Frequency correction by voltage is less than 2 V B: Frequency correction by voltage is 2 V or more and less than 5 V C: Frequency correction by voltage is 5 V or more, or stable operation is difficult even when the voltage waveform is corrected. 4). Evaluation results Table 2 shows the evaluation results obtained from 2-1 to 2-3.

  As can be seen from Table 2, the ink jet recording heads obtained in each example had little variation in ink ejection speed and ink flight bending even after continuous driving over a long period of time, and required voltage correction amount. The result that there was little was obtained. This is because, in each head, the vibration film in the vibration plate is covered with a layer of polyolefin resin having high solvent resistance, so that it is difficult to be attacked by the organic solvent in the ink. It is inferred that the result is due to the high durability against the ink containing the organic solvent.

On the other hand, in the ink jet recording heads obtained in the respective comparative examples, as a result of continuous driving over a long period of time, variations in ink ejection speed and flying curves of ink increased. Further, in order to stabilize the ink ejection operation, a larger voltage correction is required.
In addition, in the ink jet recording heads obtained in the respective examples, compared to the ink jet recording heads obtained in Comparative Examples 1 to 3, a large amount of ink was ejected even with the same driving voltage. This is considered due to a difference in vibration characteristics such as the amplitude of the diaphragm. Since the difference of the diaphragm in each head is the structure of the resin layer, it has been clarified that the vibration characteristics of the diaphragm can be improved by using the resin layer composed of polyolefin resin.

DESCRIPTION OF SYMBOLS 1 ... Inkjet recording head 10 ... Nozzle plate 11 ... Nozzle hole 15, 25, 35 ... Resin layer 20 ... Discharge liquid storage chamber forming substrate 20 '... Base material 21 ... Discharge liquid storage chamber 22 ... ... Discharged liquid supply chamber 23 ... through hole 30 ... vibrating film 31 ... liquid material 32 ... liquid coating 40 ... support plate 41 ... support plate forming substrate 50 ... piezoelectric element 51 ... piezoelectric layer 52 ... Electrode film 53 ... Recess 60 ... Case head 61 ... Discharge liquid supply path 70 ... Reservoir 9 ... Inkjet printer 92 ... Device main body 921 ... Tray 922 ... Paper discharge port 93 ... Head unit 931 …… Ink cartridge 932 …… Carriage 94 …… Printing device 941 …… Carriage motor 942 …… Reciprocating mechanism 943 …… Carriage Jjigaido shaft 944 ...... timing belt 95 ...... feeder 951 ...... feeding motor 952 ...... feed rollers 952a ...... driven roller 952b ...... drive roller 96 ...... controller 97 ...... operation panel P ...... recording paper

Claims (12)

A substrate on which a discharge liquid storage chamber for storing the discharge liquid is formed;
A nozzle plate that is provided on one surface of the substrate so as to cover the discharge liquid storage chamber and includes nozzle holes for discharging the discharge liquid as droplets;
A diaphragm provided on the other surface of the substrate so as to cover the discharge liquid storage chamber,
The vibration plate includes a vibration film, a resin layer made of a polyolefin resin covering both surfaces of the vibration film, and a support plate provided on a surface opposite to the substrate of the vibration film,
The droplet discharge head, wherein the substrate and the vibration film, and the vibration film and the support plate are bonded via the resin layer.   The droplet discharge head according to claim 1, wherein the polyolefin resin contains polyethylene in a molecular structure.   The droplet discharge head according to claim 2, wherein the polyolefin-based resin further includes an unsaturated carboxylic acid or a derivative thereof in a molecular structure.   The droplet discharge head according to claim 3, wherein the unsaturated carboxylic acid is maleic acid.   5. The droplet discharge head according to claim 1, wherein the polyolefin resin covering one surface of the vibration film and the polyolefin resin covering the other surface have the same composition.   6. The droplet discharge head according to claim 1, wherein an average thickness of the resin layer is not less than 0.5 μm and not more than 25 μm.   The droplet discharge head according to claim 1, wherein the resin layer is bonded by fusion bonding.   The liquid droplet ejection head according to claim 1, further comprising a vibration unit that is provided in contact with the vibration plate and vibrates the vibration plate due to strain. A substrate on which a discharge liquid storage chamber for storing the discharge liquid is formed;
A nozzle plate that is provided on one surface of the substrate so as to cover the discharge liquid storage chamber and includes nozzle holes for discharging the discharge liquid as droplets;
It is provided on the other surface of the substrate so as to cover the discharge liquid storage chamber, and is opposite to the vibration film, a resin layer composed of a polyolefin resin covering both surfaces of the vibration film, and the substrate of the vibration film. A support plate provided on a surface, and a vibration plate comprising: a droplet discharge head manufacturing method comprising:
Forming a resin layer composed of a polyolefin-based resin so as to cover both surfaces of the vibration film;
Bonding the vibration film and the support plate by fusing the resin layer to obtain the vibration plate;
Laminating and adhering the diaphragm and the substrate through the resin layer;
And a step of bonding the nozzle plate to the substrate.   The method of manufacturing a droplet discharge head according to claim 9, wherein the resin layer is formed by applying a liquid containing a raw material of the resin layer to both surfaces of the vibration film and then drying the liquid.   After the plate-like raw material that is the raw material of the support plate is bonded to the vibration film by fusing the resin layer, the support plate is formed by performing a patterning process to remove unnecessary portions of the plate-like raw material, The method of manufacturing a droplet discharge head according to claim 9 or 10, wherein a diaphragm is obtained.   A droplet discharge apparatus comprising the droplet discharge head according to claim 1.

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