JPH1191118A - Ink-jet recording head and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of air bubbles in a cavity, by carrying out a hydrophilic treatment to inner faces of an ink inlet for supplying ink to the cavity to be formed laminating a plurality of members and an ink feed chamber. SOLUTION: A hydrophilic film is formed at inner faces of a cavity 40 and an ink feed chamber 42 to prevent generation of air bubbles at the cavity 40 and ink feed chamber 42. While the cavity 40, etc., is wet with a coat liquid, an ink-jet recording head is subjected to a heat treatment in an electric furnace. Because of this application of thermal energy, a hydrophilic film 55 is formed to the inner faces of cavity 40, ink feed chamber 42, an ink inlet 44 and a nozzle 46, and an adhesive facing the cavity 40, ink feed chamber 42, ink inlet 44 and nozzle 46.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head for recording an image by ejecting ink droplets from a plurality of nozzles in accordance with an image signal and attaching the ink droplets to a recording medium such as paper. About the method.

[0002]

2. Description of the Related Art Conventionally, an ink jet recording head has been used in which an ink contained in a cavity is pressurized by driving a pressurizing means composed of a piezoelectric element and ejected from a nozzle to form an image on a recording medium. . The inkjet recording head includes a top plate on which a nozzle or the like for discharging ink is formed, a cavity connected to the top plate by being bonded to the top plate, and a cavity communicating with the nozzle, and an ink inlet communicating with the cavity. And a partition wall forming an ink supply chamber for supplying ink to the ink inlet, and a diaphragm serving as a pressurizing unit are bonded together with an adhesive. Further, the adhesive used is one having water repellency that is not affected by ink.
Accordingly, when the top plate and the partition wall are bonded to each other, the adhesive facing the cavity and the ink supply chamber (the adhesive that has protruded to the inner surface of the cavity and the inner surface of the ink supply chamber) is not affected by the ink. In addition, a decrease in the adhesive strength between the top plate and the partition is prevented.

[0003]

However, when the ink comes into contact with the adhesive having water repellency, the ink may embrace air and generate bubbles. Specifically, in the ink jet recording head, when the ink comes into contact with the adhesive facing the cavity or the ink supply chamber, the ink generates bubbles in the cavity or the ink supply chamber. On the other hand, in the above-described ink jet recording head, the color tone of an image formed by adjusting the pressure of the ink by adjusting the amplitude of the vibrating plate, which is a pressing means, and changing the amount of ink droplets to be ejected is adjusted. However, the air bubbles generated inside the cavity as described above function as a damper (buffer) that reduces the pressure applied to the ink inside the cavity. Then, when bubbles are generated inside the cavity in the ink jet recording head, the correlation between the amplitude of the vibration plate and the ejection amount of the ink droplets is broken, so that an ink droplet of a desired size cannot be ejected, In addition, there is a problem that a good image cannot be formed because the bubble may block the nozzle and cause ejection failure of the ink droplet.

Further, since air bubbles have a property of firmly adhering to a water-repellent adhesive, a method of sucking air bubbles in a cavity from a nozzle by a suction means to eliminate the air bubbles can eliminate the air bubbles efficiently. Can not.

Furthermore, a hydrophilic film is formed on the inner surface of the cavity and the inner surface of the ink supply chamber by subjecting the top plate, partition walls, and the like to hydrophilic treatment, thereby preventing the ink from engulfing air and suppressing the generation of bubbles. However, in the ink jet recording head formed by bonding the top plate and the like with an adhesive after the top plate and the like are hydrophilically treated, the adhesive facing the ink supply chamber and the cavity is not subjected to the hydrophilic treatment. Therefore, there is a problem that generation of bubbles cannot be prevented.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to prevent the generation of air bubbles in a cavity, and in the method of manufacturing an ink jet recording head according to claim 1, a plurality of members are formed. In a method of manufacturing an ink jet recording head that is integrally assembled by bonding with an adhesive, after bonding the plurality of members,
A hydrophilic film is formed by performing hydrophilic treatment on a cavity formed by laminating the plurality of members and an inner surface of each of an ink inlet for supplying ink to the cavity and an ink supply chamber.

The ink jet recording head according to the present invention is an ink jet recording head comprising a plurality of members, wherein a cavity is formed on a surface of the pair of members bonded by an adhesive, and a cavity is formed on the cavity. An ink supply chamber for supplying ink is formed, and an inner surface of the cavity, an inner surface of the ink supply chamber, the adhesive facing the cavity, and a hydrophilic film formed on the adhesive facing the ink supply chamber. It is characterized by having.

According to a third aspect of the present invention, the set of members is made of a porous ceramic material.

According to a fourth aspect of the present invention, there is provided an ink jet recording head comprising a plurality of members, wherein a cavity is formed on a surface of the plurality of members which is in contact with a pair of members made of a piezoelectric ceramic material. And an ink supply chamber for supplying ink to the cavity is formed, the set of members is integrated by sintering, and a hydrophilic film is formed on the inner surface of the cavity and the inner surface of the ink supply chamber. It is characterized by:

[0010]

According to the method of manufacturing an ink jet recording head according to the first aspect, after a plurality of members are bonded with an adhesive, the inner surface of the cavity, the inner surface of the ink inlet, and the inner surface of the ink supply chamber are subjected to a hydrophilic treatment. Since the hydrophilic film is formed, not only the inner surface of the cavity, the inner surface of the ink inlet, and the inner surface of the ink supply chamber, but also the adhesive facing the cavity by protruding into the inner surface of the cavity,
A hydrophilic film is also formed on the surface of the adhesive facing the ink inlet by protruding into the inner surface of the ink inlet and the surface of the adhesive facing the ink supply chamber by protruding from the inner surface of the ink supply chamber. Thus, in the inkjet recording head manufactured by the manufacturing method, since the inner surface of the cavity, the inner surface of the ink inlet and the inner surface of the ink supply chamber are all formed with the hydrophilic film, the inner surface of the cavity,
On the inner surface of the ink inlet and the inner surface of the ink supply chamber, the ink does not trap air and generate bubbles. Therefore, in the ink jet recording head, when the ink in the cavity is ejected by pressurizing the ink, the correlation between the pressing force and the ejection amount of the ink droplet is maintained, so that the desired ink droplet can be ejected, Also,
A good image can be formed because the nozzles are not blocked by bubbles. Further, when air bubbles mixed into the ink supply chamber enter the cavity, the air bubbles do not firmly adhere to the ink supply chamber, the ink inlet and the cavity, and can be sucked from the nozzle by the suction means.

In the ink jet recording head according to the present invention, the adhesive which faces the cavity by protruding into the inner surface of the cavity, the inner surface of the ink supply chamber, the inner surface of the cavity, and the like, and the ink is supplied by protruding into the inner surface of the ink supply chamber. Since the hydrophilic film is formed on the surface of the adhesive facing the chamber, the ink does not trap air and generate bubbles on the inner surface of the cavity and the inner surface of the ink supply chamber. Therefore, in the ink jet recording head, when the ink in the cavity is ejected by pressurizing the ink, the correlation between the pressing force and the ejection amount of the ink droplet is maintained, so that the desired ink droplet can be ejected,
Further, a good image can be formed since the nozzle is not blocked by the bubble. Further, when air bubbles mixed into the ink supply chamber enter the cavity, the air bubbles do not firmly adhere to the ink supply chamber and the cavity, and can be sucked from the nozzle by the suction means.

In the ink jet recording head according to a third aspect of the present invention, since a pair of members constituting the ink supply chamber and the cavity are formed of a porous ceramic material, the inner surface of the cavity and the inner surface of the ink supply chamber are formed. The hydrophilicity of the hydrophilic film formed on the surface of the adhesive facing the cavity and the surface of the adhesive facing the ink supply chamber is improved.

In the ink jet recording head according to the fourth aspect, a set of members constituting the cavity and the ink supply chamber is made of a piezoelectric ceramic material, and these are integrally assembled by sintering. Since the adhesive having water repellency is not used, the hydrophilicity of the hydrophilic film formed on the inner surface of the cavity and the inner surface of the ink supply chamber is improved.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a part of an inkjet printer 1 which is an embodiment of an apparatus having an inkjet recording head 10 according to the present invention. The ink jet printer 1 converts the paper 5 as a recording medium into y
And a carriage 11 to which the ink jet recording head 10 is attached.
And a moving mechanism 9 for moving in the direction.

FIGS. 2 and 3 show a front view of the ink jet recording head 10 and a cross section taken along line III-III of FIG. 2, respectively.
As shown in these figures, the ink jet recording head 1
0 comprises a first head section 26 and a second head section 28,
Top plate 30, partition wall 32, diaphragm 34, and base plate 3
6 are integrally combined. In the present embodiment, the first head section 26 and the second head section 28 are arranged in the direction of movement of the recording head 10 and have a symmetrical configuration with respect to a central one-dot chain line 38. Note that the first head section 26 and the second head section 28
Are arranged in a staggered manner, the density of the ink jet recording head 10 can be increased.

The top plate 30 made of a nickel material is water-repellent by applying a fluorine-based water-repellent agent on the surface side, which is the surface facing the paper 5. A plurality of concave portions are formed by fine processing by a method such as electroforming or photolithography, and the first head portion 2 is formed.
6, a plurality of cavities 40 for accommodating ink, an ink supply chamber 42 for accommodating ink for replenishment, and an ink supply chamber 4 for each of the second head portions 28.
2 are formed.
Cavities 40 of first head section 26 and second head section 28
Are formed in a long groove shape extending in the direction in which the head portions 26 and 28 face each other and in parallel.

On the top plate 30, a nozzle 46 communicating with the cavity 40 is orthogonal to the longitudinal direction of the cavity 40 at a position opposite to the position where the ink inlet 44 is formed with respect to the longitudinal direction of the cavity 40. Are formed at predetermined intervals on one straight line. Nozzle 4
Numeral 6 has a tapered shape tapering outward, and has an inner diameter of 25 μm on the ejection side.

The partition 32 is made of a thin film made of SUS304 material, and is fixed between the top plate 30 and the diaphragm 34. The partition 32 does not hinder the deformation of the piezoelectric member 48 described later, but deforms according to the deformation of the piezoelectric member 48.

The vibration plate 34 is formed by depositing a metal on the upper and lower surfaces of a single plate made of a piezoelectric ceramic material to form a conductive layer. After being adhered and fixed to the base plate 36, it is cut vertically and horizontally by dicing. Then, the piezoelectric member 48 is separated into a piezoelectric member 48 facing the cavity 40 and a wall 50 surrounding each piezoelectric member 48, and a polarization process is performed by applying a high voltage to each piezoelectric member 48 at a high temperature.

The base plate 36 has a plurality of conductive leads (not shown) on the surface facing the vibration plate 34, and each conductive lead faces the piezoelectric member 48.

The top plate 30 and the partition 32 having the above configuration are adhered with an adhesive having water repellency, for example, an epoxy adhesive E30H manufactured by Konishi Co., Ltd.
The vibration plate 34 and the base plate 36 are bonded to each other with a conductive wire adhesive, and the top plate 30, the partition 32, the vibration plate 34, and the base plate 36 are integrated to constitute the ink jet recording head 10.

In the ink jet recording head 10 having the above configuration, the ink supply chambers 42 of the respective head portions 26 and 28 are provided.
In contrast, when ink is supplied from an ink tank (not shown), the ink in the ink supply chamber 42 is distributed to each cavity 40 via the ink inlet 44. Also,
As shown in FIG. 1, the recording head 10 reciprocates in the direction of the arrow x based on the driving of the motor 20. When a predetermined voltage (print signal) is applied to the piezoelectric member 48, the piezoelectric member 48 is deformed toward the cavity 40, and the deformation is transmitted to the partition 32. As a result, the ink in the cavity 40 is pressurized, the ink droplets fly from the nozzles 46, and adhere to the sheet 5 fed in the direction of the arrow y in the opposite portion of the recording head 10 to record an image.

Next, the cavity 40 and the ink supply chamber 4
In FIG. 2, the cavity 4 is used to prevent the generation of air bubbles.
The step of forming a hydrophilic film on the inner surface of the ink supply chamber 42 and the inner surface of the ink supply chamber 42 will be described. The above steps are performed based on the steps (i to v) shown in FIG. Hereinafter, description will be made in accordance with the process order.

(I) Injection of hydrophilic treatment agent: The vacuum displacement device 60 shown in FIG. 5 is a device for forming a film made of a desired material on the surface of the member to be treated inserted inside the vacuum bell jar 62. In the process, it is used to inject a hydrophilic treatment material into the cavity 40, the ink supply chamber 42, and the ink inlet 44 of the inkjet recording head 10. The vacuum displacement device 60 includes a tank 66 filled with a coating liquid 64 (silane coupling agent: vinyltriethoxysilane), which is a hydrophilic treatment material, on the ceiling of the vacuum bell jar 62. An introduction pipe 68 for introducing the coating liquid 64 into the vacuum bell jar 62 is attached to the bottom surface of the tank 66 via a cock 70. An atmosphere communication pipe 74 having an atmosphere leak valve 72 is attached to the ceiling of the vacuum bell jar 62 so that the pressure inside the vacuum bell jar 62 can be returned to normal pressure.

An exhaust pipe 76 connected to a vacuum pump (not shown) for reducing the pressure inside the vacuum bell jar 62 is attached to a side wall of the vacuum bell jar 62 via a valve 78. Between the valve 78 and the vacuum pump, an atmosphere communication pipe 80 for communicating the exhaust pipe 76 with the atmosphere.
Are connected via a leak valve 82, and a cold trap for monomer recovery is connected (not shown).

In the vacuum displacement device 60 having the above configuration,
With the inkjet recording head 10 placed in the beaker 84, the inkjet recording head 10 is inserted into the vacuum bell jar 62,
With the vacuum pump, vacuum bell jar 6 with 2 and 82 closed
After the pressure in the chamber 2 is reduced to a predetermined pressure, the coating liquid 64 is poured into the beaker 84 from the tank 66, and the ink jet recording head 10 is immersed in the coating liquid. As described above, since the inkjet recording head 10 is immersed in the coating liquid under a reduced-pressure atmosphere, the coating liquid is injected into the cavity 40, the ink supply chamber 42, and the ink inlet 44. In addition,
When the coating liquid is a liquid having a high degree of polymerization, the surface of the top plate 30 on which the water repellent treatment has been performed is masked with an adhesive tape to prevent contact with the coating liquid.

(Ii): Pretreatment heating ink-jet recording head 10 into which coating liquid has been injected
Is removed from the vacuum displacement device 60, and then
In the state of being immersed in the coating liquid in 4, it is heated to about 75 ° C. Thus, the coating liquid favorably forms the hydrophilic film 55 during the main heat treatment performed in a later step (see FIG. 6). When the coating liquid is a liquid having a high degree of polymerization, the pretreatment heating may be omitted.

(Iii) Discharging of the hydrophilic treatment agent When the pretreatment heating is completed, the ink jet recording head 10 is taken out from the beaker 84 and the coating liquid injected into the cavity 40 and the like is discharged.
Discharged from

(Iv): Main heat treatment The ink jet recording head 10 is heat-treated in an electric furnace (150 ° C., 30 minutes) while the coating liquid is discharged and the cavity 40 and the like are wet with the coating liquid. In this manner, by applying heat energy, the inner surface of the cavity 40, the inner surface of the ink supply chamber 42, and the ink inlet 44
Inner surface of the nozzle, the inner surface of the nozzle 46, and these cavities 4
A hydrophilic film 55 is formed on the adhesive 56 facing the ink supply chamber 42, the ink inlet 44, and the nozzle 46 (see FIG. 6).

(V): Cleaning treatment The coating liquid not formed as the hydrophilic film 55 is removed by washing the ink jet recording head 10 with water. Note that alcohol cleaning may be performed according to the type of the coating liquid.

In the ink jet recording head 10 subjected to the hydrophilic treatment as described above, the inner surface of the ink supply chamber 42, the inner surface of the cavity 40, the inner surface of the ink inlet 44, the inner surface of the nozzle 46, and the ink supply chamber 42, the cavity Since the hydrophilic film 55 is formed on the adhesive 56 facing the ink inlet 44, the ink inlet 44, and the nozzle 46, the ink supply chamber 42, the cavity 40,
In the ink inlet 44, it is prevented that the ink embraces air and generates bubbles. This allows
In the ink jet recording head 10, pressurization due to deformation of the piezoelectric member 48 is directly transmitted to the ink in the cavity 40. That is, the correlation between the pressure and the ejection amount of the ink droplets is maintained without change, so that a desired ink droplet can be ejected. Further, since the nozzle 46 is not blocked by bubbles, a favorable An image can be formed.

The top plate 30 and the partition walls 3 are formed by the above hydrophilic treatment.
2. Table 1 below shows how the contact angle of the adhesive 56 with water changed. The present inventors found that the contact angle was 60
It has been found that when the temperature is below the degree, the generation of bubbles is prevented and the bubbles do not adhere firmly. As shown in Table 1, since the contact angle of the top plate 30, the partition wall 32, and the adhesive is 60 degrees or less, generation of bubbles is prevented in the ink supply chamber 40 formed by these components.
It was also confirmed that bubbles did not adhere firmly in the ink supply chamber 42 and the like. Therefore, for example, when bubbles are mixed in the ink supplied from the ink tank and the bubbles move to the ink supply chamber 42, the bubbles can be easily sucked from the nozzle 46 by the suction means.

[0033]

[Table 1]

The top plate 30 of the ink jet recording head 10 is not limited to nickel or SUS304, but may be made of porous ceramics, oxide ceramics, piezoelectric ceramics or other highly hydrophilic ceramics, or excellent in workability. A semiconductor material such as silicon may be used. Note that silicon may be used as an anisotropic material whose surface is doped with phosphorus to increase hydrophilicity. Further, the partition wall may be an aramid film having excellent durability in addition to the above materials.

As shown in Table 2 below, a top plate 3 made of steatite ceramics (pore ratio: about 12%) and unpolarized PZT (piezoelectric ceramics: pore ratio: about 3.8%)
0, all of the partition walls 32 made of aramid film were able to reduce the contact angle by the hydrophilic treatment.
Particularly, in the top plate 30 made of steatite ceramics,
A contact angle of 35 degrees was obtained. If the contact angle is 45 degrees or less, generation of bubbles can be completely prevented. If the ceramic material constituting the top plate 30 has a pore ratio (volume ratio of holes) of 3% or more, the contact angle can be suppressed to 60 degrees or less. When the ceramic material is an oxide, the ceramic material is preferably an oxide because it contributes to suppressing the contact angle. When the top plate 30 is made of a ceramic material, the nozzles 46 and the like are formed by excimer laser processing.

[0036]

[Table 2]

Further, the ink jet recording head 10
The top plate 30, the partition wall 32, the diaphragm 34, and the base plate 36 may all be made of unpolarized PZT, and may be integrated by sintering. In the ink jet recording head 10, since the adhesive is not used when the top plate 30 and the partition wall 32 are integrated, the cavity 42 is not used.
Etc. do not face the adhesive. Therefore, the contact angle with the ink in the cavity 42 and the like subjected to the hydrophilic treatment becomes 39 degrees as described above, and the generation of bubbles is prevented, so that a good image can be formed with the ink jet recording head 10. In addition, the above effect is obtained by using the cavity 4
Since the ink jet recording head 10 can be obtained if the adhesive does not face 2 etc., the inkjet recording head 10 may have a configuration in which the top plate 30 and the partition 32 are formed of non-polarized PZT, and these are integrated by sintering.

In the above hydrophilic treatment, a silane coupling agent made of vinyltriethoxysilanesilane was used in the coating solution. However, the silane coupling agent is not limited to the above vinyltriethoxysilanesilane, but may be vinyltris (2- (Methoxyethoxyquin) silane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3.4-epoxycyclohexyl) ethyltrimethoxysilane, N-2
-(Aminoethyl) 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3- Mercaptopropyltrimethoxysilane and 3-chloropropyltrimethoxysilane may be used.

The coating solution is Na ₂ O.nSiO ₂ ,
Or K ₂ O.nSiO ₂ (n = 2 to 3, preferably 2.
Water glass represented by formulas (1) to (3.5) or polysiloxane ((-O-Si-O-Si-) n) may be used.

[Brief description of the drawings]

FIG. 1 is a partial perspective view of an inkjet printer including an inkjet recording head according to the present invention.

FIG. 2 is a plan view of the ink jet recording head.

FIG. 3 is a perspective view of the inkjet recording head shown in FIG.
FIG. 3 is a sectional view taken along line III.

FIG. 4 is an explanatory view showing a hydrophilic treatment step.

FIG. 5 is a schematic view of a vacuum replacement device.

FIG. 6 is a partially enlarged view of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Ink-jet head, 30 ... Top plate, 32 ... Partition, 40 ... Cavity, 42 ... Ink supply chamber, 46 ... Nozzle, 55 ... Hydrophilic film, 56 ... Adhesive.

Claims (4)

[Claims] 1. A method for manufacturing an ink jet recording head in which a plurality of members are bonded together with an adhesive to assemble them integrally, wherein after bonding the plurality of members, a cavity formed by bonding the plurality of members; And a hydrophilic film is formed by performing hydrophilic treatment on each inner surface of the ink supply chamber and the ink inlet for supplying ink to the cavity. 2. An ink jet recording head comprising a plurality of members, wherein a cavity and an ink supply chamber for supplying ink to the cavity are formed on the bonded surface of a set of members bonded by an adhesive. An ink jet recording head, wherein a hydrophilic film is formed on the inner surface of the cavity, the inner surface of the ink supply chamber, the adhesive facing the cavity, and the adhesive facing the ink supply chamber. . 3. The ink jet recording head according to claim 2, wherein said one set of members is a porous ceramic material. 4. An ink jet recording head comprising a plurality of members, wherein a cavity is provided on a surface of the plurality of members which is in contact with a pair of members made of a piezoelectric ceramic material, and ink for supplying ink to the cavity is provided. A supply chamber is formed, and the set of members are integrated by sintering,
An ink jet recording head, wherein a hydrophilic film is formed on the inner surface of the cavity and the inner surface of the ink supply chamber.