JPH06122204A - Ink jet recording head and water repellent treatment thereof - Google Patents

Abstract

PURPOSE:To endow the device with the property that ink droplets spout straight in the constant direction for a long time by a method wherein irregularities having specified averaged differences in level and pitches are provided on a nozzle opening face and the face with the differences in level is coated with a polymer including fluorine at a specified thickness. CONSTITUTION:While liquid jet flows 11 including grinding stone particles are ejected from an ejection outlet 10 in a wet type honing machine 8, a stage 9 containing a nozzle plate 7 is transported to a direction of arrow 12 so that irregularities having 0.01-0.5mum of averaged differences in level and 15mum or less of pitches are formed on a nozzle opening face 13 to be a nozzle opening section after the assembling of a head. An adhering tape is adhered the opposite face of the nozzle opening face 13 with the irregularities and the nozzle plate 7 is dropped into a polymer solution, e.g. dissolving a polymer including fluorine, whereby the lifting speed of nozzle plate 7 is adjusted in such a manner that thin film having 50-1500 angstrom of thickness is formed. A vibration membrane 15 and a head forming member 16 are bonded each other. A piezoelectric element 17 and the nozzle plate 7 are bonded each other.

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 and a method for treating water repellency on a nozzle opening surface of the ink jet recording head.

[0002]

2. Description of the Related Art An ink jet recording head discharges ink as ink droplets from a nozzle to form a printed image on a recording medium. However, when a water-based ink is used, if the water repellency of the nozzle opening surface is insufficient, the liquid of the ink will be discharged. Drops tend to adhere,
As a result, the straightness of the ejected ink droplets may be impaired, and recording may not be possible due to trouble such as disturbance of the printed image.

Regarding the water repellency of the nozzle opening surface required for an ink jet recording head, it can be said that if the contact angle is 90 degrees or more, the straightness of the ink droplet is not impaired and the water repellency is sufficient. However, many ink jet recording heads use materials such as metal, glass, plastic, and ceramics, and most of them have a contact angle of about 30 to 80 degrees and have sufficient water repellency. It can not be said. Therefore, conventionally, in order to eliminate ink adhesion, the nozzle opening surface is coated with a water repellent treatment agent. As a coating method, for example, electrostatic powder coating (JP-A-57-167765), Various methods such as vacuum vapor deposition (Japanese Patent Laid-Open No. 60-183161) and other methods such as spray coating and spin coating are known.

On the other hand, the ink jet recording head uses a wiper made of rubber or cloth to prevent the dust generated from the recording medium from adhering to the nozzle opening surface during recording and impairing the straightness of the ink droplets. Wiping is performed to wipe the opening surface. At this time, since the wiper rubs the coating layer, the coating layer wears with the number of times of wiping. Therefore, if the layer thickness is not sufficient, the coating layer will be lost by wiping several times and it will be difficult to maintain water repellency, and there is a problem that it cannot be used for a long time.However, wiping more than several thousand times will not eliminate it. When trying to obtain a coating layer having a sufficient layer thickness of, the water repellent treatment agent penetrates into the nozzle and causes clogging in the conventionally known coating method. There was a problem of being lost.

As a method for solving these problems, Japanese Patent Laid-Open No. 2-48953 discloses that a nozzle opening surface is provided with irregularities having an average height difference of 0.5 to 10 μm, and then a porous body or a solvent is used. A method is disclosed in which a water repellent treatment agent is applied to a transfer medium made of a swelling substance, and the agent is transferred onto the uneven surface to obtain a coating layer having good water repellency even after wiping is performed.

[0006]

In this method, however, the layer thickness becomes very large when an attempt is made to form a coating layer that sufficiently fills the recesses, and as a result, as shown in FIG.
a and a coating layer 2 are formed on the nozzle 1 as shown in FIG. 1b, or a web-shaped coating layer 2b is stretched at the end of the nozzle, resulting in defective ejection of ink droplets and straightness. Cause damage. When the thickness of the coating layer is reduced, the nozzle diameter of the ink jet recording head is usually about 10 to 100 μm, whereas the average height difference of the nozzle opening surface is very large, and the shape of the nozzle opening 3 becomes distorted. As a result, the meniscus 4 of the ink is deformed to cause the ink droplets to fly in a direction different from the predetermined direction (FIG. 2), which is not preferable because a good recorded image cannot be obtained. Therefore, the object of the present invention is to maintain the water repellency even by the wiping operation of several thousand times or more, and to cause the ink droplets to fly in a predetermined direction without defective ejection or loss of straightness, thereby providing a long-term good printed image. An object of the present invention is to provide an ink jet recording head that enables to obtain the above.

A further object of the present invention is to provide a water repellent treatment method which is excellent in wiping resistance without causing nozzle clogging in order to provide the ink jet recording head described above. is there.

[0008]

Therefore, according to the present invention, the average height difference is 0.01 μm or more and less than 0.5 μm and the pitch is 15 μm on the nozzle opening surface of the ink jet recording head.
The water repellent treatment is characterized by a first step of providing irregularities of m or less, and a second step of coating the irregular surface with a fluoropolymer in a layer thickness of 50 to 1500 angstroms.

In the water repellent treatment method for an ink jet recording head according to the present invention, the average height difference (hereinafter referred to as Ra) 0.
It is preferable to provide unevenness having a distance (called a pitch) between 01 μm and less than 0.5 μm and a distance (called a pitch) between adjacent peaks of any convex portion in any cross section of the uneven surface of 15 μm or less. If unevenness is provided, the coating layer remains in the recesses even after the coating layer is abraded by wiping, so that the water repellency is maintained and the water repellency is maintained for a long time. However, when Ra is less than 0.01 μm, the recesses are formed during wiping. The coating layer also wears and cannot maintain the water repellency for a long time, and if Ra is 0.5 μm or more, the shape of the nozzle opening is distorted and, as a result, the meniscus of the ink is deformed and the ink droplets of the nozzle may be deformed. It flies in a direction different from the opening direction and a good recorded image cannot be obtained. Further, if the pitch is larger than 15 μm, the coating layer is not retained in the recesses and is worn during wiping, and it is also difficult to maintain water repellency for a long period of time, which is not preferable.

In the water repellent treatment method for an ink jet recording head of the present invention, as a method for forming irregularities, the surface roughness at the time of cutting the surface is set to the extent that irregularities having the above-mentioned surface roughness can be formed. It is possible to use many commonly known methods such as adjusting method, lapping method, sand blasting, wet honing, and buffing.

In the ink jet recording head of the present invention, the head forming member forming the nozzle opening surface can be arbitrarily selected from materials such as metal, glass, plastic and ceramic which are used in many ink jet recording heads. I can. The nozzle opening surface may be formed of only one kind of material or may be formed of two or more kinds of different materials. After performing, the unevenness of the surface of each of the two types of materials is Ra in each
0.01 μm or more and less than 0.5 μm and pitch is 15 μm
It must satisfy m or less.

In the water repellent treatment method for an ink jet recording head of the present invention, when the thickness of the coating layer to be formed is greater than 1500 Å, the water repellent treatment agent penetrates into the nozzle to form a film (see FIG. 3a) or a coating layer is formed on the nozzle (Fig. 3b), and a layer is formed on the resist 5 (Fig. 3c) even if the water repellent treatment is prevented from entering the nozzle by resist treatment or the like, and the nozzle is blocked. As a result, defective ejection of ink droplets is caused, which is not preferable. Further, if the layer thickness is less than 50 angstroms, pinholes due to coating defects are likely to occur and a sufficient water repellent effect cannot be obtained, which is also not preferable. Therefore, it is preferable to form the coating layer with a layer thickness in the range of 50 to 1500 angstroms. .

In the water repellent treatment method for an ink jet recording head of the present invention, the fluorine-containing polymer used as the water repellent treatment agent is preferably an amorphous fluorine-containing polymer. Specifically, a fluorine-containing polymer such as polydiperfluoroalkyl fumarate, Teflon AF (trademark of DuPont), Cytop (trademark of Asahi Glass Co., Ltd.), or an alternate copolymer of diperfluoroalkyl fumarate and styrene. Alternate copolymer of fluorine-containing ethylene and hydrocarbon ethylene such as polymer, alternating copolymer of trifluoroethylene chloride and vinyl ether, alternating copolymer of tetrafluoroethylene chloride and vinyl ester or the like The body or derivative, Fumalite (trademark of NOF CORPORATION) can be preferably used. Since these amorphous fluorine-containing polymers are selectively dissolved in a fluorine-based organic solvent, by dissolving them in a solvent at an arbitrary concentration and coating them, a polytetrafluoride that can be applied only in the form of powder or dispersion medium is used. As compared with fluoroethylene or polychlorotrifluoroethylene, the coating layer formed has higher adhesion to the nozzle opening surface, and uniform coating is possible.

A first preferred form of the coating method in the water repellent treatment method for an ink jet recording head of the present invention is a head forming member having a nozzle opening surface in a polymer solution obtained by dissolving a fluorine-containing polymer. A coating layer is formed by a dipping method in which the material is dipped and pulled at a constant speed. According to the dipping method, the layer thickness of the coating layer is mainly determined by the pulling rate and the viscosity of the polymer solution, but it is very easy to control the layer thickness by adjusting the pulling rate, and a desired thickness can be easily obtained. A coating layer can be obtained with a layer thickness, and coating can be performed very uniformly and stably.

In a preferred second embodiment as a coating method in the water repellent treatment method for an ink jet recording head of the present invention, a polymer solution obtained by dissolving a fluorine-containing polymer is dropped on the water surface by one to several drops. Then, the coating layer is formed by the water surface spreading method in which the obtained spreading film is transferred to the nozzle opening surface after the solvent is volatilized by spreading. According to the water surface development method, the layer thickness of the coating layer is determined by the concentration of the fluorine-containing polymer in the polymer solution and the dropping amount per unit area, but the layer thickness can be easily controlled by adjusting the dropping amount. It is possible to easily obtain a coating layer with a desired layer thickness, and since it is previously formed as a spreading film on the water surface, it is possible to obtain a coating layer with a uniform layer thickness on the entire nozzle opening surface.

Further, as another embodiment of the second preferred embodiment as a coating method in the water repellent treatment method for an ink jet recording head of the present invention, a polymer solution in which a fluorine-containing polymer is dissolved is provided on the water surface in an amount of 1 to several. After dripping down and spreading to evaporate the solvent, the barrier is moved to form the Langmuir film as the spreading film, and the obtained Langmuir film is brought into contact with the nozzle opening surface to form an LB containing a fluorine-containing polymer. The film is formed as a coating layer. L like this
Since the B film can be laminated when it is brought into contact with the same surface more than once, a coating layer having a desired layer thickness can be easily obtained by adjusting the number of contacts.

A third preferred embodiment as a coating method in the water repellent treatment method for an ink jet recording head of the present invention comprises dissolving a fluorine-containing polymer on the mirror plane of a transfer medium having a mirror plane. A polymer layer composed of a polymer solution is formed, and then a coating layer is formed by a transfer method in which the mirror-planar polymer layer is transferred to the nozzle opening surface. According to the transfer method, the layer thickness of the coating layer is determined by the layer thickness of the polymer layer on the mirror plane, and by controlling this, the coating layer with the desired layer thickness can be easily formed on the nozzle opening surface. . The control of the layer thickness of the polymer layer depends on the method for forming the polymer layer on the transfer medium, but the simplest method is a dipping method, and it is also possible to use a spin coating method or a spray coating method. is there. The transfer medium can be made of any material, but the surface shape of the transfer medium is related to the ease of transfer when transferring the polymer layer, and when the surface is a mirror plane. Can be satisfactorily transferred, but an uneven structure is not preferable because it causes a part that is easily transferred and a part that is difficult to be transferred, which causes pinholes.

In the water repellent treatment method for an ink jet recording head of the present invention, it is possible to form unevenness on the nozzle opening surface, and to expose this to an ozone atmosphere before coating. By performing such a surface cleaning treatment using ozone, it is possible to remove stains on the surface to be coated and improve the adhesion of the coating layer, and the ozone atmosphere can be obtained by oxygen plasma or ultraviolet irradiation. . In addition, various surface cleaning treatments such as electrolytic degreasing can be used, and the same effect can be obtained.

[0019]

The present invention will be described in detail below with reference to the drawings.

(Embodiment 1) FIG. 4 is an explanatory diagram showing step by step the ink jet recording head 6 produced by the water repellent treatment method for an ink jet recording head described in the first embodiment of the present invention. First, austenite type C
A r18% Ni8% stainless steel plate (200 μm thick, hereinafter abbreviated as stainless plate) is rolled and die-cut to form a nozzle plate 7. Next, after mounting the nozzle plate 7 on the stage 9 of the wet honing machine 8, the nozzle plate 7 is moved from the jet port 10 to # 3.
20 kg of liquid jet 11 containing 20 fine particles of abrasive powder
The stage 9 was moved in the direction of arrow 12 at a rate of 40 cm / minute while ejecting at a rate of / cm ² , and the surface on the nozzle opening side after head assembly was made uneven (FIG. 4a) to obtain a nozzle opening surface 13.
When the surface step of the unevenness was measured, Ra was 0.05 μ
m, and the pitch was 13 μm. A polyimide tape having an adhesive layer was attached to the surface of the nozzle plate 7 opposite to the surface of the nozzle opening 13 having the irregularities, and a polymer solution having the composition shown in Table 1 was used, and the nozzle plate was pulled up at a speed of 35 mm / min. After dipping No. 7 and peeling off the polyimide tape, put it in an oven at 150 ° C for 1 hour to remove the solvent and coat the coating layer 14 on the nozzle opening surface 13.
Got After that, the vibrating plate 1 made of polysulfone for transmitting the pressure for ejecting the ink droplet to the ink
5 and a head forming member 16 having an ink flow path and a supply port for supplying ink into the head are adhered, and a thick electric element 1 for generating a pressure for ejecting ink droplets
7 and the nozzle plate 7 were adhered to each other to obtain an ink jet recording head 6 (FIG. 4B).

[0021]

[Table 1]

The coating layer 14 of the head 6 has a contact angle with water of about 98 degrees, and the nozzle may be clogged with a film due to infiltration of the polymer solution into the nozzle 18, or the coating layer may be formed on the nozzle 18 to be clogged. Not,
In addition, the nozzle opening surface 13 was formed without coating defects such as pinholes. The coating layer 1
In order to measure the layer thickness of No. 4, after dipping a stainless steel plate having at least one surface polished to a mirror surface by the same method as above, the coating layer on the mirror surface was measured by an optical film thickness meter, and it was about 200 angstroms. Met.

When the ink jet ink 19 shown in Table 2 is ejected from the nozzle 18 using the head 6, the ink droplet 20 is ejected and flies straight without bending (0.5 ° or less) in the opening direction of the nozzle 18. (Fig. 4b),
A high-quality recorded image with high printing accuracy could be formed on the recording medium 21. Further, in order to remove dust when fibrous dust is generated from the recording medium 21 and adheres to the coating layer 14 during ink ejection, a test in which wiping is repeated up to 10,000 times using a dust removing wiper 22 made of silicon rubber. As a result (FIG. 4c), it was possible to form a high-quality recorded image with high printing accuracy even after wiping 10,000 times without impairing the straightness of the ink droplet 20.

[0024]

[Table 2]

(Comparative Example 1) An ink jet recording head 23 was obtained by the same operation as in Example 1 except for the step of performing the wet honing treatment (Fig. 5a). In addition, when the surface roughness of the nozzle opening surface 25 of the nozzle plate 24 was measured before forming the coating layer, Ra was 0.04 μm.
m and the pitch was 20 μm.

The coating layer 26 of the head 23 has a contact angle with water of about 98 °, and the nozzle is clogged with a film due to the infiltration of the polymer solution into the nozzle 27, or the coating layer is formed on the nozzle 27 and clogged. In addition, no defective coating such as pinholes was formed on the nozzle opening surface 25. Further, when the layer thickness of the coating layer 26 was measured by the same method as in Example 1, it was about 200 Å.

When the ink jet ink 19 is ejected from the nozzle 27 by using the head 23, the ink droplet 20b is not bent in the initial direction of the nozzle (0.
5 ° or less) Direct ejection / flying (FIG. 5a) Recording medium 21
On the other hand, a high-quality recorded image with high printing accuracy could be formed. However, when wiping was performed in the same manner as in Example 1, the coating layer was not worn away after 500 times of wiping, and the ink pool 28 was generated. The droplet 20b bends 2 to 8 ° with respect to the opening direction of the nozzle 23 (angle a)
(FIG. 5B) Recording was performed on the recording medium 21, but a high-quality recorded image could not be formed.

(Embodiment 2) The nozzle opening surface 30 of the nozzle plate 29 made of a stainless steel plate was operated in the same manner as in Embodiment 1 except that the abrasive grains were # 600 fine powder and the ejection pressure was 3.0 kg / cm ^2. Roughened. When the surface step of the unevenness was measured, Ra was 0.1 μm and the pitch was 1
It was 4 μm. Next, water 32 is put into the water tank 31, and
1 to 2 drops of the polymer solution having the composition shown in FIG. 1 are dropped on the water surface to volatilize the solvent, and then the floating layer on the water surface is gathered by the glass barrier 33 to form the Langmuir membrane 34, and the nozzle plate 29 The uneven nozzle opening surface 30 is gently brought into contact with the Langmuir film 34 (FIG. 6a).
It is preferable that the nozzle opening surface 30 is parallel to the water surface, but the contact can be made without any trouble even if the nozzle opening surface 30 is inclined by several degrees. After leaving for a while after the contact, the nozzle plate 29 is gently pulled up to remove the attached water droplets by air blow. After the process from the contact with the Langmuir film 34 to the air blowing of water drops was performed 15 times in total, the nozzle plate 29 was placed in an oven at 130 ° C. for 1 hour to completely remove the residual water, and a coating layer 35 was obtained. . After that, the diaphragm 15b made of polysulfone and the head 1 forming member 16b are bonded together,
Further, the thick electric element 17b and the nozzle plate 29 were adhered to each other to obtain an ink jet recording head 36 (FIG. 6b).

[0029]

[Table 3]

The coating layer 35 of the head 36 has a contact angle with water of about 103 degrees, so that the coating layer 35 will not be clogged by the invasion of the polymer into the nozzle 37 or the coating layer will not be formed on the nozzle 37 and clogged. Face 30
On the other hand, it was formed without coating defects such as pinholes. Further, when the layer thickness of the coating layer 35 was measured by the same method as in Example 1, it was about 180 Å.

When the ink jet ink 19 is ejected from the nozzle 37 using this head 36, an ink drop 20
c does not bend with respect to the opening direction of the nozzle 37 (0.5 °
(Below) The ink was ejected and flew straight (FIG. 6B), and a high-quality recorded image with high printing accuracy could be formed on the recording medium 21. Wiping was performed in the same manner as in Example 1,
The straightness of the ink droplet 20c is not impaired at all (FIG. 6).
c) It was possible to form a high-quality recorded image with high printing accuracy even after wiping 10,000 times.

[0032] (Comparative Example 2) abrasive grains # 400 fines, to obtain an ink jet recording head 38 by the same operation as in Example 2 except that the jet pressure and 2.5 kg / cm ² (Fig. 7a). The nozzle opening surface 40 of the nozzle plate 39
When the surface roughness of was measured before forming the coating layer,
Ra was 0.1 μm and the pitch was 17 μm.

The coating layer 41 of the head 38 has a contact angle with water of about 103 degrees, so that the coating layer 41 is not clogged due to the intrusion of the polymer into the nozzle 42 or the coating layer is not formed on the nozzle 42 and is not clogged. Face 40
On the other hand, it was formed without coating defects such as pinholes. Furthermore, when the layer thickness of the coating layer 41 was measured by the same method as in Example 1, it was about 180 Å.

When the ink jet ink 19 is ejected from the nozzle 42 using this head 38, the ink droplet 20d is ejected and flies straight (0.5 ° or less) straight in the opening direction of the nozzle 42 in the initial stage (see FIG. 7a), a high-quality recorded image with high printing accuracy could be formed on the recording medium 21, but when wiping was performed by the same method as in Example 1, the coating layer disappeared due to abrasion after 1000 times of wiping 43 occurs, the ink droplet 20d bends 2 to 9 ° with respect to the opening direction of the nozzle 42 (angle b) (FIG. 7b), and recording is performed on the recording medium 21, but a high-quality recording image cannot be formed. .

(Embodiment 3) The nozzle opening surface 45 of the nozzle plate 44 made of a stainless steel plate was made uneven by the same operation as in Embodiment 1 except that the abrasive grains were # 600 fine powder. When Ra was 0.
The pitch was 02 μm and the pitch was 7 μm. Next, a mirror plane 47 (Ra 0.002 μm, of a transfer medium 46 made of glass,
1 to 2 drops of a polymer solution having the composition shown in Table 4 on a pitch of 40 μm) and the transfer medium 46 was rotated at 2000 rpm / min for 1 minute by using a motor 48, and a polymer layer 49 was formed on a mirror plane 47. Was obtained (Fig. 8a). After allowing this to stand for a while to evaporate the solvent, the uneven nozzle opening surface 45 is pressed against the polymer layer 49 for a few minutes to transfer a part of the polymer layer 49 onto the nozzle opening surface 45, Nozzle plate 4
4 was put in an oven at 200 degrees for 1 hour to obtain a coating layer 50. Then, the vibrating plate 15c made of polysulfone and the head forming member 16c were adhered to each other, and the thick electric element 17c and the nozzle plate 44 were adhered to each other to obtain an ink jet recording head 51 (FIG. 8b).

[0036]

[Table 4]

The coating layer 50 of the head 51 has a contact angle with water of about 106 degrees, so that the coating layer 50 is not clogged by the intrusion of the polymer into the nozzle 52 or the coating layer is not formed on the nozzle 52 and is not clogged. Face 45
On the other hand, it was formed without coating defects such as pinholes. When the layer thickness of the coating layer 50 was measured by the same method as in Example 1, it was about 170 Å.

When the ink jet ink 19 is ejected from the nozzle 52 using this head 51, the ink droplet 20
e is not bent with respect to the opening direction of the nozzle 52 (0.5 °
(Below) The ink was ejected and flew straight (FIG. 8b), and a high-quality recorded image with high printing accuracy could be formed on the recording medium 21. Wiping was performed in the same manner as in Example 1,
The straightness of the ink droplet 20e is not impaired at all (FIG. 8).
c) It was possible to form a high-quality recorded image with high printing accuracy even after wiping 10,000 times.

(Comparative Example 3) The injection pressure was 1.5 kg / cm ^2.
Inkjet recording head 53 was obtained in the same manner as in Example 3 except for the above (FIG. 9A). When the surface roughness of the nozzle opening surface 55 of the nozzle plate 54 was measured before forming the coating layer, Ra was 0.007 μm.
m and the pitch was 5 μm.

The coating layer 56 of the head 53 has a contact angle with water of about 106 degrees, so that the coating layer 56 is not clogged due to the intrusion of the polymer into the nozzle 57 or the coating layer is not formed on the nozzle 57 and is not clogged. Face 55
On the other hand, it was formed without coating defects such as pinholes. When the layer thickness of the coating layer 56 was measured by the same method as in Example 1, it was about 170 Å.

When the ink-jet ink 19 is ejected from the nozzle 57 using the head 53, the ink droplet 20f is initially ejected straight (0.5 ° or less).
After flying (FIG. 9A), a high-quality recorded image with high printing accuracy could be formed on the recording medium 21, but when wiping was performed by the same method as in Example 1, the wiping was 100%.
After 0 times, the coating layer almost disappeared and an ink pool 58 was generated, and the ink droplet 20f was bent 2 to 6 ° with respect to the opening direction of the nozzle 57 (angle a) (FIG. 9b), and recording was performed on the recording medium 21. High-quality recorded images could not be formed.

(Embodiment 4) FIG. 10 is an explanatory diagram showing step by step the ink jet recording head 59 formed by the water repellent treatment method for an ink jet recording head described in the fourth embodiment of the present invention. First, the head forming member 60 made of polyether sulfone is applied to the directions 61 and 6
Hole 6 to be a nozzle after assembled by excimer laser from 2
3. Perforate the ink supply port 64 (FIG. 10a). After adhering the diaphragm 65 made of polyether sulfone to the perforated head forming member 60, a slashing machine 67 equipped with a cutting grindstone 66 made of # 2000 fine particles.
Then, the head forming member 60 is cut along the line A-A in FIG.
0b), a nozzle opening surface 68 having irregularities was obtained. When the surface step difference of the nozzle opening surface 68 was measured, Ra was 0.4 μm.
m and the pitch was 6 μm. Then, a coating layer 69 is formed on the nozzle opening surface 68 using the same method as in the second embodiment.
Got Then, the thick electric element 17d was adhered to the vibration plate 65 to obtain an ink jet recording head 59 (FIG. 10).
c).

The coating angle of the coating layer 69 of the head 59 with respect to water is about 103 degrees, and there is no clogging due to the intrusion of the polymer into the nozzle 70 or the coating layer is not formed on the nozzle 70 and clogged. Face 68
On the other hand, it was formed without coating defects such as pinholes. In order to measure the layer thickness of the coating layer 69, a coating layer was obtained on the mirror surface plate of polyether sulfone by the same operation as the method of obtaining the coating layer 69, and a part of the coating layer was cut into small pieces of polyether sulfone. The thickness of the coating layer was calculated by a method of measuring the step difference between the mirror surface of the polyether sulfone and the surface of the coating layer, which was revealed as a result, and found to be about 19
It was 0 angstrom.

When the ink jet ink 19 is ejected from the nozzle 70 using this head 59, the ink droplet 20
g does not bend with respect to the opening direction of the nozzle 70 (0.5 °
(Below) A high-quality recorded image with high printing accuracy could be formed on the recording medium 21 by ejecting and flying straight. Wiping was performed in the same manner as in Example 1, but ink droplets 20
It was possible to form a high-quality recorded image with high printing accuracy even after wiping 10,000 times without impairing the straightness of g.

(Comparative Example 4) The cutting grindstone used is # 150.
An inkjet recording head 71 was obtained in the same manner as in Example 4 except that the number of fine particles was 0 (FIG. 11).
a). When the surface roughness of the nozzle opening surface 72 was measured before forming the coating layer, Ra was 0.5 μm and the pitch was 7 μm.

The coating layer 73 of the head 71 has a contact angle with water of about 103 degrees, so that the coating layer 73 is not clogged by the intrusion of the polymer into the nozzle 74 or the coating layer is not formed on the nozzle 74 and is not clogged. Face 72
On the other hand, it was formed without coating defects such as pinholes. When the layer thickness of the coating layer 73 was determined in the same manner as in Example 4, it was about 190 Å.

When the ink jet ink 19 was ejected from the nozzle 74 using this head 71, the ink droplet 2
0 h was bent by 1 to 3 ° with respect to the opening direction of the nozzle 74 (angle d) (Fig. 11a), and a high-quality recorded image could not be formed on the recording medium 21. When observing the nozzle 74 of the head 71, the nozzle opening 75 has a distorted shape, and the meniscus 76 is deformed by the influence of the shape and the ink droplet 20h
Was discharged while bending in the opening direction of the nozzle 74 (FIG. 11b). Further, when wiping was performed by the same method as in Example 1, the water repellency was maintained, but the ink droplet 20h was bent 1 to 3 ° without changing from that before wiping, which is a high quality with respect to the recording medium 21. It was not possible to form a recorded image.

(Embodiment 5) An ink jet recording head 77 was obtained in the same manner as in Embodiment 1, except that the pulling speed during dipping was 10 mm / min. When the surface roughness of the nozzle opening surface 78 was determined before forming the coating layer, Ra was 0.05 μm and the pitch was 13 μm.

The coating layer 79 of the head 77 has a contact angle with water of about 98 degrees, and the nozzle 80 is clogged with a film due to the polymer solution entering the nozzle 80 or a coating layer is formed on the nozzle 80 to block it. There was no problem, and no defective coating such as pinholes was formed on the nozzle opening surface 78. This is Example 1
When the layer thickness was measured by the same method as described above, it was about 70 Å.

When the ink jet ink 19 is ejected from the nozzle 80 using this head 77, the ink droplet 20
i does not bend with respect to the opening direction of the nozzle 80 (0.5 °
Below) The ink was ejected and flew straight (FIG. 12), and a high-quality recorded image with high printing accuracy could be formed on the recording medium 21. Wiping was performed in the same manner as in Example 1,
The straightness of the ink droplet 20i is 100 without being impaired.
It was possible to form a high-quality recorded image with high printing accuracy even after wiping 00 times.

Example 6 An ink jet recording head 81 was obtained in the same manner as in Example 1 except that the pulling rate during dipping was 100 mm / min. In addition,
When the surface roughness of the nozzle opening surface 82 was determined before forming the coating layer, Ra was 0.05 μm and the pitch was 13 μm.

The coating layer 83 of the head 81 has a contact angle with water of about 98 degrees, and the nozzle is clogged with a film due to the infiltration of the polymer solution into the nozzle 84 or the coating layer is formed on the nozzle 84 to be clogged. In addition, no defective coating such as pinholes was formed on the nozzle opening surface 82. When the layer thickness was measured in the same manner as in Example 1, it was about 500 Å.

When the ink jet ink 19 is ejected from the nozzle 84 using this head 81, the ink droplet 20
j does not bend with respect to the opening direction of the nozzle 84 (0.5 °
(Below) The ink was ejected and flew straight (FIG. 13), and a high-quality recorded image with high printing accuracy could be formed on the recording medium 21. Wiping was performed in the same manner as in Example 1,
The straightness of the ink droplet 20j is 100 without being impaired.
It was possible to form a high-quality recorded image with high printing accuracy even after wiping 00 times.

(Comparative Example 5) An ink jet recording head 85 was obtained in the same manner as in Example 1 except that the pulling speed at dipping was 5 mm / min. When the surface roughness of the nozzle opening surface 86 was determined before forming the coating layer, Ra was 0.05 μm and the pitch was 13 μm.

The coating layer 87 of the head 85 has a contact angle with water of about 90 degrees, and thus the nozzle is clogged due to film clogging due to the polymer layer penetrating into the nozzle 88, or the coating layer is not formed and blocked on the nozzle 88. Although not present, pinholes 89 were confirmed in places of the coating layer 87, and when the inkjet ink 19 was dropped, an ink pool 90 was generated on the pinhole 89. When the layer thickness was measured by the same method as in Example 1, the layer thickness was about 40 Å.

When the ink jet ink 19 was ejected from the nozzle 88 using this head 85, the ink droplet 2
0 k is influenced by the ink pool 90 and is bent by 1 to 5 ° with respect to the opening direction of the nozzle 88 and ejected (angle e) (see FIG. 1).
4) A high-quality recorded image with high printing accuracy could not be formed on the recording medium 21.

(Comparative Example 6) An ink jet recording head 91 was obtained in the same manner as in Example 1 except that the pulling rate at dipping was 200 mm / min. In addition,
When the surface roughness of the nozzle opening surface 92 was determined before forming the coating layer, Ra was 0.05 μm and the pitch was 13 μm.

The coating layer 93 of the head 91 had a contact angle with water of about 98 degrees, but the polymer solution entered the nozzle 94 and the film 95 was stretched and clogged (FIG. 15), and the ink jet ink 19 was applied to the head 91. Ink droplets could not be ejected even when supplied inside. When the layer thickness was measured in the same manner as in Example 1, the layer thickness was about 1700 angstroms.

(Example 7) An ink jet recording head was obtained in the same manner as in Example 4 except that the number of times the uneven nozzle opening surface was brought into contact with the Langmuir film was 9. When the surface roughness of the nozzle opening surface was measured before forming the coating layer, Ra was 0.4 μm and the pitch was 6 μm.

The coating layer formed on the nozzle opening surface has a contact angle with water of about 103 degrees, and the coating layer is not clogged due to the intrusion of the polymer into the nozzle or the coating layer is not clogged on the nozzle. Further, the nozzle opening surface was formed without coating defects such as pinholes. When the layer thickness of this was measured by the same method as in Example 4, it was about 60 Å.

When the ink-jet ink 19 was ejected from the nozzle using the above-described head, the ink droplets were ejected and flew straight without bending (0.5 ° or less), and the recording medium 2 was recorded.
As compared with No. 1, a high-quality recorded image with high printing accuracy could be formed. Wiping was performed in the same manner as in Example 1, but the straightness of the ink droplet was not impaired at all.
It was possible to form a high-quality recorded image with high printing accuracy even after wiping 00 times.

(Embodiment 8) An ink jet recording head was obtained in the same manner as in Embodiment 4, except that the number of times that the uneven nozzle opening surface was brought into contact with the Langmuir film was 60 times. When the surface roughness of the nozzle opening surface was measured before forming the coating layer, Ra was 0.4 μm and the pitch was 6 μm.

The coating layer formed on the opening surface of the nozzle has a contact angle with water of about 103 degrees, and the coating layer is not clogged due to the intrusion of the polymer into the nozzle or the coating layer is not clogged on the nozzle. Further, the nozzle opening surface was formed without coating defects such as pinholes. When the layer thickness was measured by the same method as in Example 4, it was about 1000 angstroms.

When the ink jet ink 19 was ejected from the nozzle using the above-mentioned head, the ink droplets were ejected and flew straight without bending (0.5 ° or less), and the recording medium 2 was recorded.
As compared with No. 1, a high-quality recorded image with high printing accuracy could be formed. Wiping was performed in the same manner as in Example 1, but the straightness of the ink droplet was not impaired at all.
It was possible to form a high-quality recorded image with high printing accuracy even after wiping 00 times.

(Comparative Example 7) An ink jet recording head was obtained in the same manner as in Example 4 except that the number of times of contacting the Langmuir film with the uneven nozzle opening surface was set to 7. When the surface roughness of the nozzle opening surface was measured before forming the coating layer, Ra was 0.4 μm and the pitch was 6 μm.

The coating layer formed on the opening surface of the nozzle had a contact angle with water of about 103 degrees, and the polymer was not clogged due to the intrusion of the polymer into the nozzle or the coating layer was not formed and blocked on the nozzle. However, pinholes were generated in places on the coating layer, and when the inkjet ink 19 was dropped, an ink pool was formed on the pinholes. When the layer thickness was measured in the same manner as in Example 4, the layer thickness was about 40 Å.

When the ink-jet ink 19 is ejected from the nozzle using the above-mentioned head, the ink droplets are affected by the ink pool and the number of ink drops is 1 to 1 in the opening direction of the nozzle.
The ink was discharged with a 6 ° bend, and a high-quality recorded image with high printing accuracy could not be formed on the recording medium 21.

(Comparative Example 8) An ink jet recording head was obtained in the same manner as in Example 4 except that the number of times the nozzle opening surface having irregularities was brought into contact with the Langmuir film was 100 times. When the surface roughness of the nozzle opening surface was measured before forming the coating layer, Ra was 0.4 μm,
The pitch was 6 μm.

Although the coating layer formed on the nozzle opening surface had a contact angle with water of about 103 degrees, the coating layer was formed on the nozzle to block the nozzle, and the inkjet ink 19 was supplied into the head. However, ink droplets could not be ejected. When the layer thickness was measured in the same manner as in Example 4, the layer thickness was about 1800 Å.

Table 5 is obtained by summarizing the above results.

[0071]

[Table 5]

From Table 5, as shown in Examples 1 to 8, the nozzle opening surface was provided with irregularities of Ra 0.01 μm or more and less than 0.5 μm and a pitch of 15 μm or less to form a coating layer with a layer thickness of 50 to 1500 angstroms. In this case, a coating layer can be obtained on the nozzle opening surface without causing coating defects such as pinholes and without blocking or blocking the nozzle. Also early ~
The flight trajectory of the ink droplet does not bend until after 10,000 times of wiping, so that a good recorded image can be formed on the recording medium for a long time. However, if the pitch exceeds 15 μm as in Comparative Examples 1 and 2, or Ra is less than 0.01 μm as in Comparative Example 3, the coating layer is easily peeled off by wiping even though the ink droplets have good straightness in the initial stage. Occurs, an ink pool is formed, the straightness is gradually deteriorated, and a high-quality recorded image cannot be obtained. When Ra is 0.5 μm or more as in Comparative Example 4, the shape of the nozzle opening becomes distorted and the ink droplets fly in a direction different from the nozzle opening direction, which is not preferable for an inkjet recording head. Further, when the thickness of the coating layer is smaller than 50 angstroms as in Comparative Examples 5 and 7, pinholes are generated in the coating layer and ink pools are generated, and straightness of ink droplets cannot be obtained. Like 1500
When the layer thickness exceeds angstrom, the nozzles are blocked, resulting in defective ejection of ink droplets, so that a recorded image cannot be formed.

[0073]

As described above, according to the water repellent treatment method for an ink jet recording head of the present invention, Ra of 0.01 μm or more and less than 0.5 μm and a pitch of 15 are formed on the nozzle opening surface.
By forming the coating layer after making unevenness of less than μm, the coating layer remains in the recess even after wiping the head for long-term use, and the water repellency is maintained. However, the nozzle has a distorted shape. Since it does not become a mouth, the ink drop does not fly in a direction different from the nozzle opening direction due to the deformation of the meniscus and accordingly, it is possible to obtain an ink jet recording head having straightness and directionality of the ink drop for a long period of time. I can. Further, by setting the layer thickness of the coating layer in the range of 50 to 1500 angstroms, it is possible to form a coating layer on the nozzle opening surface of the ink jet recording head without water repellency or nozzle clogging due to coating defects such as pinholes. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view for explaining a problem caused by a conventional water repellent treatment method.

FIG. 2 is a schematic cross-sectional view for explaining a problem caused by a conventional water repellent treatment method.

FIG. 3 is a schematic cross-sectional view for explaining a problem caused by exceeding a preferable coating layer thickness shown in the water repellent treatment method of the present invention.

FIG. 4 is a partial explanatory view of a process of performing Example 1 of the present invention and a cross-sectional view of the obtained inkjet recording head.

FIG. 5 is a sectional view of an ink jet recording head obtained according to Comparative Example 1 of the present invention.

6A and 6B are a partial explanatory view of a process of performing Example 2 of the present invention and a cross-sectional view of the obtained ink jet recording head.

FIG. 7 is a cross-sectional view of an inkjet recording head obtained according to Comparative Example 2 of the present invention.

FIG. 8 is a partial explanatory view of a process of performing Example 3 of the present invention and a cross-sectional view of the obtained ink jet recording head.

FIG. 9 is a cross-sectional view of an inkjet recording head obtained according to Comparative Example 3 of the present invention.

FIG. 10 is a partial explanatory view of a process of performing Example 4 of the present invention and a cross-sectional view of the obtained ink jet recording head.

FIG. 11 is a cross-sectional view of an inkjet recording head obtained in Comparative Example 4 of the present invention.

FIG. 12 is a cross-sectional view of an inkjet recording head obtained according to Example 5 of the present invention.

FIG. 13 is a cross-sectional view of an inkjet recording head obtained according to Example 6 of the present invention.

FIG. 14 is a cross-sectional view of an inkjet recording head obtained in Comparative Example 5 of the present invention.

FIG. 15 is a cross-sectional view of an inkjet recording head obtained in Comparative Example 6 of the present invention.

[Explanation of symbols]

1, 18, 27, 37, 42, 52, 57, 70, 7
4, 80, 84, 88, 94 ... Nozzle 2, 2b, 14, 26, 35, 41, 50, 56, 6
9, 73, 79, 83, 87, 93 ... Coating layer 3, 75 ... Nozzle port 4, 76 ... Meniscus 5 ... Resist 6, 23, 36, 38, 51, 53, 59, 71, 7
7, 81, 85, 91 ... Inkjet recording head 7, 24, 29, 39, 44, 54 ... Nozzle plate 8 ... Wet honing machine 9 ... Stage 10 ... Jet 11 ... Liquid jet 13, 25 , 30, 40, 45, 55, 68, 72, 7
8, 82, 86, 92 ... Nozzle opening surface 15, 15b, 15c, 65 ... Vibrating plate 16, 16b, 16c, 60 ... Head forming member 17, 17b, 17c, 17d ... Thick electric element 19 ... Inkjet ink 20, 20b, 20c, 20d, 20e, 20f, 20
g, 20h, 20i, 20j, 20k ... Ink droplet 21 ... Recorded material 22 ... Dust removal wiper 28, 43, 58 ... Ink pool 31 ... Water tank 32 ... Water 33 ... Barrier 34 ... Rung Muir film 46. Transfer medium 47 .. Mirror plane 48 .. Motor 49 .. Polymer layer 63 .. Hole 64 .. Ink supply port 66 .. Cutting grindstone 67 .. Slashing machine 89 .. Pinhole 95 ... Membrane a, b, c, d, e ... Angle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B41J 2/055

Claims (8)

[Claims] 1. A nozzle opening surface of an ink jet recording head, comprising: 1. Providing unevenness having an average height difference of 0.01 μm or more and less than 0.5 μm and a pitch of 15 μm or less, A water repellent treatment method for an ink jet recording head, characterized in that the uneven surface is coated with a fluorine-containing polymer in a layer thickness of 50 to 1500 Å. 2. The water repellent treatment method for an inkjet recording head according to claim 1, wherein the fluorine-containing polymer is an amorphous fluorine-containing polymer. 3. The water repellent treatment method for an inkjet recording head according to claim 1, wherein the coating method is a dipping method. 4. The method of coating comprises developing a polymer solution in which a fluorine-containing polymer is dissolved on a water surface to volatilize a solvent, and then transferring the developed film to the uneven surface. The water repellent treatment method for an inkjet recording head according to claim 1, wherein the method is a method of forming a coating layer. 5. The coating method is such that a polymer solution in which a fluorine-containing polymer is dissolved is spread on a water surface to volatilize a solvent, and then a barrier is moved to form a Langmuir film as a spreading film. 2. The water repellent treatment method for an ink jet recording head according to claim 1, wherein the Langmuir film obtained is brought into contact with the uneven surface at least once to form a coating layer. 6. The method of coating comprises forming a polymer layer made of a polymer solution obtained by dissolving a fluorine-containing polymer on the mirror plane of a transfer medium having a mirror plane, and then forming the surface of the transfer medium. 2. The water repellent treatment method for an inkjet recording head according to claim 1, which is a method of transferring the upper polymer layer onto the uneven surface. 7. The nozzle opening surface of the ink jet recording head is 1. 1. It has unevenness with an average height difference of 0.01 μm or more and less than 0.5 μm and a pitch of 15 μm or less, A coating layer made of a fluorine-containing polymer having a layer thickness of 50 to 1500 angstroms is formed on the unevenness.
Inkjet recording head characterized by that. 8. The ink jet recording head according to claim 7, wherein the fluorine-containing polymer is an amorphous fluorine-containing polymer.