JP2015227027A - Liquid discharge head, method for manufacturing the same, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge head capable of preventing degradation of water repellency in the vicinity of a peripheral edge of nozzle holes resulting from reduction of a water repellent film in the vicinity of the peripheral edge of the nozzle holes due to wiping, and comprising a nozzle plate having excellent wiping-durability in the vicinity of the peripheral edge of the nozzle holes.SOLUTION: The liquid discharge head includes at least a nozzle plate comprising: a nozzle substrate which has a plurality of recesses on one surface thereof and is provided with nozzle holes in the recesses; and a water repellent film which is arranged on the surface having the plurality of recesses in the nozzle substrate and contains a perfluoropolyether compound. The difference of a maximum thickness and a minimum thickness of the water repellent film is not less than 1.0 μm, and a thickness of the water repellent film in the vicinity where the nozzle holes are positioned is larger than a thickness of the water repellent film in a part where the recesses are not positioned.

Description

  The present invention relates to a liquid discharge head, a manufacturing method thereof, and an image forming apparatus including the liquid discharge head.

  2. Description of the Related Art Conventionally, as an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, a plotter, or a composite machine thereof, for example, a liquid discharge recording type image forming apparatus having a liquid discharge head is known.

Since the liquid discharge head discharges ink as droplets from a plurality of nozzle holes formed in the nozzle plate, the surface characteristics of the liquid discharge surface on which the ink droplets of the nozzle plate are discharged are determined as ink droplet discharge. Greatly affects stability. In view of this, the ink droplet ejection stability is improved by forming a water-repellent film on the liquid ejection surface of the nozzle plate to prevent ink from adhering to the vicinity of the periphery of the nozzle hole. .
On the other hand, the liquid discharge recording type image forming apparatus includes a cleaning unit that wipes and removes ink adhering to the liquid discharge surface of the nozzle plate with a blade.

In order to improve the water repellency of the liquid ejection surface of the nozzle plate, for example, a nozzle plate using a perfluoropolyether compound as a water-repellent film material has been proposed (see Patent Document 1).
However, the nozzle plate of Patent Document 1 cannot obtain sufficient water repellency for oil-based inks and solvent-based inks, and the water-repellent film does not have sufficient durability against repeated wiping.
Therefore, in order to improve the adhesion between the water repellent film and the nozzle substrate, for example, a SiO ₂ film is provided on the surface of the nozzle substrate on the liquid discharge side, and the end of the perfluoropolyether chain is formed on the SiO ₂ film. A liquid discharge head including a nozzle plate having a water repellent film to which a compound having an alkoxysilane residue is bonded has been proposed (see Patent Document 2). According to this proposal, sufficient water repellency can be obtained for both the oil-based ink and the solvent-based ink, and the adhesion between the nozzle substrate and the water-repellent film can be improved.

  However, as shown in FIG. 1A, the nozzle plate described in Patent Document 2 has a surface 13 on the liquid discharge side of the nozzle substrate 8 before wiping the liquid discharge surface 3 of the nozzle plate 2 with a blade 9. The entire nozzle plate 2 including the vicinity of the periphery of the nozzle hole 1 is flat (the thickness of the water repellent film 4 is uniform). Therefore, when the liquid discharge surface 3 of the nozzle plate 2 is repeatedly wiped with the blade 9, the water repellent film 4 near the periphery of the nozzle hole 1 is partially peeled off or worn as shown in FIG. 1B. Further, since the perfluoropolyether compound constituting the water repellent film 4 is oily, if the blade 9 is wiped even after the water repellent film 4 is formed, another position from the vicinity of the periphery of the nozzle hole 1 is obtained. In some cases, the water repellent film 4 may move. As a result, the water-repellent film 4 near the periphery of the nozzle hole 1 is reduced, the nozzle substrate 8 is exposed, and the water repellency near the periphery of the nozzle hole 1 is reduced, so that Discharge stability will fall. That is, the nozzle plate described in Patent Document 2 does not have sufficient wiping durability near the periphery of the nozzle hole 1.

The liquid discharge head of the present invention has a plurality of recesses on one surface, and a nozzle substrate provided with nozzle holes in the recesses;
A water repellent film containing a perfluoropolyether compound disposed on a surface of the nozzle substrate having the plurality of recesses;
A nozzle plate having at least
The difference between the maximum thickness and the minimum thickness in the water repellent film is 1.0 μm or more,
The thickness of the water repellent film in the vicinity where the nozzle hole is located is thicker than the thickness of the water repellent film in a portion where the concave portion is not located.

  According to the present invention, it is possible to prevent a decrease in water repellency in the vicinity of the periphery of the nozzle hole due to a decrease in the water repellent film in the vicinity of the periphery of the nozzle hole due to wiping, and the nozzle plate having high wiping durability in the vicinity of the periphery of the nozzle hole is provided. A liquid discharge head can be provided.

FIG. 1A is a schematic cross-sectional view illustrating an example of a state before cleaning a liquid discharge surface of a nozzle plate in a conventional liquid discharge head. FIG. 1B is a schematic cross-sectional view illustrating an example of a state in which the liquid ejection surface of the nozzle plate in the conventional liquid ejection head is being cleaned. FIG. 2A is a schematic plan view showing an example of a nozzle plate used in the liquid discharge head of the present invention. FIG. 2B is a partially enlarged view of the nozzle plate in the X part of FIG. 2A. FIG. 2C is a schematic cross-sectional view of the nozzle plate of FIG. 2B. 2D is a schematic cross-sectional view of a nozzle substrate obtained by removing a water repellent film from the nozzle plate of FIG. 2C. FIG. 2E is a schematic enlarged view of a Y portion in FIG. 2C. FIG. 3 is a process chart showing a procedure of an example of a method for manufacturing a liquid discharge head according to the present invention. FIG. 4 is a schematic view showing an example of a nozzle substrate polishing step in the method of manufacturing a liquid discharge head according to the present invention. FIG. 5 is a partially enlarged sectional view showing an example of the nozzle substrate before polishing. FIG. 6 is a partial enlarged cross-sectional view illustrating an example of a state in which the nozzle substrate is pressed from the liquid chamber bonding surface side of the nozzle substrate via an elastic body. FIG. 7 is a partial enlarged cross-sectional view showing an example of a state in which the surface on the liquid discharge side of the nozzle substrate pressed by an elastic body is polished. FIG. 8 is a partially enlarged cross-sectional view illustrating an example of a state in which the pressure applied by the elastic body is released after polishing the surface of the nozzle substrate on the liquid discharge side. FIG. 9A is a partially enlarged cross-sectional view showing an example of a nozzle substrate after polishing in the nozzle substrate polishing step. FIG. 9B is a partially enlarged cross-sectional view showing an example of a state in which the nozzle substrate after polishing is immersed in a liquid containing a perfluoropolyether compound. FIG. 9C is a partially enlarged cross-sectional view showing an example of a state in which the nozzle substrate after immersion is naturally dried at room temperature. FIG. 9D is a partially enlarged cross section showing an example of a state in which the water repellent film is removed from the liquid chamber bonding surface side after a protective film is attached to the liquid discharge side surface of the nozzle substrate on which the water repellent film is formed. FIG. FIG. 9E is a partially enlarged cross-sectional view showing an example of a nozzle plate in which a water repellent film is formed on the surface of the nozzle substrate on the liquid ejection side. FIG. 10 is a schematic view showing an example of the liquid discharge head of the present invention. FIG. 11 is a schematic perspective view showing an example of the image forming apparatus of the present invention on which the liquid discharge head of the present invention is mounted. FIG. 12 is a schematic side view of the image forming apparatus of FIG. FIG. 13A is a schematic cross-sectional view illustrating an example of a state before the liquid ejection surface of the nozzle plate in the liquid ejection head of Example 1 is wiped with a blade. FIG. 13B is a schematic cross-sectional view illustrating an example of a state in which the liquid ejection surface of the nozzle plate in the liquid ejection head of FIG. 13A is wiped with a blade. FIG. 14 is a plan view showing a state in which the vicinity of the periphery of the nozzle hole of the nozzle plate is filled with oil-based magic ink. FIG. 15A is a diagram illustrating a state of the oil-based magic ink in the vicinity of the periphery of the nozzle hole before wiping the liquid ejection surface of the nozzle plate of Example 1 with a blade. FIG. 15B is a diagram illustrating a state of the oil-based magic ink in the vicinity of the peripheral edge of the nozzle hole after wiping the liquid discharge surface of the nozzle plate of Example 1 with a blade. FIG. 16A is a diagram illustrating a state of the oil-based magic ink in the vicinity of the peripheral edge of the nozzle hole before wiping the liquid discharge surface of the nozzle plate of Comparative Example 6 with a blade. FIG. 16B is a diagram illustrating a state of the oil-based magic ink in the vicinity of the peripheral edge of the nozzle hole after wiping the liquid ejection surface of the nozzle plate of Comparative Example 6 with a blade.

(Liquid discharge head)
The liquid discharge head according to the present invention includes at least a nozzle plate, and further includes other members as necessary.

The present invention can prevent a decrease in water repellency near the periphery of the nozzle hole due to a decrease in the water-repellent film near the periphery of the nozzle hole due to wiping, and a liquid having a nozzle plate with high wiping durability near the periphery of the nozzle hole. An ejection head is provided.
The liquid discharge head of the present invention has a plurality of recesses on one surface, and a nozzle substrate provided with nozzle holes in the recesses;
A water repellent film containing a perfluoropolyether compound disposed on a surface of the nozzle substrate having the plurality of recesses;
A nozzle plate having at least
The difference between the maximum thickness and the minimum thickness in the water repellent film is 1.0 μm or more,
The water repellent film in the vicinity where the nozzle hole is located is formed thicker than the water repellent film in the portion where the recess is not located.

Here, the nozzle plate used in the liquid discharge head of the present invention will be described with reference to the drawings.
2A is a schematic plan view showing an example of the nozzle plate 2 used in the liquid discharge head of the present invention, FIG. 2B is a partially enlarged view of a portion X in FIG. 2A, and FIG. It is a schematic sectional drawing of the said nozzle plate 2. 2D is a schematic cross-sectional view of the nozzle substrate 8 obtained by removing the water repellent film 4 from the nozzle plate 2 of FIG. 2C. FIG. 2E is an enlarged view of a Y portion in FIG. 2C.

As shown in FIGS. 2A to 2C, the nozzle plate 2 has a plurality of nozzle holes 1 on a liquid discharge surface 3 that is a surface on the liquid discharge side.
As shown in FIG. 2D, the nozzle substrate 8 has a plurality of recesses 5 on the surface 13 on the liquid discharge side, and the nozzle holes 1 are provided at the bottom of the recesses 5. The bottom of the recess 5 is a part including the deepest position of the recess 5.
The water repellent film 4 containing a perfluoropolyether compound is formed on the liquid discharge side surface 13 including the plurality of recesses 5 in the nozzle substrate 8.

As shown in FIG. 2D, the thickness of the nozzle substrate 8 in the vicinity where the nozzle hole 1 is located is thinner than the thickness of the nozzle substrate 8 where the recess 5 is not located. Thereby, the thickness of the water-repellent film 4 formed on the concave portion 5 can be formed thicker than the thickness of the water-repellent film 4 where the concave portion 5 is not located. It can suppress that the said water-repellent film 4 of the vicinity reduces, and wiping durability improves.
As shown in FIG. 2D, the recess 5 in the nozzle substrate 8 has a shape in which the thickness of the nozzle substrate 8 gradually decreases from the outer edge 7 of the recess 5 toward the vicinity where the nozzle hole 1 is located. preferable.
As shown in FIG. 2E, the vicinity of the nozzle hole 1 in the nozzle substrate 8 is the nozzle hole on the water repellent film 4 (the liquid discharge side surface 13 of the nozzle substrate 8) side of the nozzle substrate 8. One open end 100 is meant.

As shown in FIG. 2E, the thickness of the nozzle substrate 8 in the vicinity where the nozzle hole 1 is located passes through the opening end 100 of the nozzle hole 1 of the nozzle substrate 8 and is perpendicular to the thickness direction of the nozzle plate 2. The distance between the point 101 where H intersects the surface opposite to the water repellent film 4 on the liquid chamber joint surface 6 of the nozzle plate 2 (imaginary) and the open end 100 of the nozzle hole 1. Yes, the minimum value when this distance is arbitrarily measured at 10 locations of the nozzle hole 1 is the minimum thickness of the nozzle substrate 8.
The maximum thickness of the nozzle substrate 8 is measured at 10 positions (including the opening end 100 of the nozzle hole 1) of the thickness of the nozzle substrate 8 where the recess 5 is not located in the nozzle substrate 8. And it means the maximum value among these measured thickness values.

The difference between the maximum thickness and the minimum thickness in the nozzle substrate 8 is 1.0 μm or more, preferably 1.0 μm to 4.0 μm.
The difference (maximum thickness−minimum thickness) between the maximum thickness and the minimum thickness in the nozzle substrate 8 is preferably 1.0 μm or more, and more preferably 1.0 μm to 4.0 μm. When the difference is 1.0 μm or more, even if wiping is repeatedly performed on the liquid discharge surface 3 of the nozzle plate 2, the difference formed in the concave portion 5 (near the periphery of the nozzle hole 1) of the nozzle substrate 8. There is an advantage that the reduction of the water repellent film 4 can be suppressed and the wiping durability is improved.
The maximum thickness and the minimum thickness in the nozzle substrate 8 are, for example, cutting of a sample cut by a diameter portion passing through the opening center of the nozzle hole 1 of the nozzle substrate 8 by embedding the nozzle substrate 8 with an epoxy resin or the like. The surface is recorded as a digital image at a magnification of 5000 using an electron microscope (JEM-2100 (manufactured by JEOL Ltd.)). The obtained digital image is subjected to image processing using image processing software (Photoshop (manufactured by Adobe)). With respect to the obtained processed image, the thickness of the nozzle substrate 8 at any 10 locations (including the opening end 100 of the nozzle hole 1) is measured by a “measurement” command, and the maximum and minimum values of these measured values are measured. From the value, the maximum thickness and the minimum thickness in the nozzle substrate 8 can be obtained.

As shown in FIGS. 2C and 2E, the water-repellent film 4 in the vicinity where the nozzle hole 1 is located is thicker than the water-repellent film 4 where the recess 5 is not located. ing. That is, the water repellent film 4 is formed so that the surface of the nozzle plate 2 on which the concave portion 5 is formed is flat so that the liquid discharge surface 3 of the nozzle plate 2 is flat.
As shown in FIG. 2E, the vicinity of the nozzle hole 1 of the nozzle substrate 8 is the nozzle on the water-repellent film 4 side of the nozzle substrate 8 (the liquid discharge side surface 13 of the nozzle substrate 8). The open end 100 of the hole 1 is meant.
As shown in FIG. 2E, the thickness of the water-repellent film 4 in the vicinity where the nozzle hole 1 is located is drawn in the thickness direction of the nozzle plate 2 through the opening end 100 of the nozzle hole 1 of the nozzle substrate 8. The distance between the point H where the perpendicular H intersects the surface of the liquid ejection surface 3 of the nozzle plate 2 opposite to the nozzle substrate 8 (horizontal and virtual) and the open end 100 of the nozzle hole 1. The maximum value when this distance is arbitrarily measured at 10 locations of the nozzle hole 1 is the maximum thickness of the water-repellent film 4.
The minimum thickness of the water-repellent film 4 is determined by arbitrarily measuring the thickness of the portion of the water-repellent film 4 where the concave portion 5 is not located (including the opening end 100 of the nozzle hole 1). This means the smallest value among the measured thickness values.

The difference (maximum thickness−minimum thickness) between the maximum thickness and the minimum thickness of the water repellent film 4 is 1.0 μm or more, and more preferably 1.0 μm to 4.0 μm. When the difference is 1.0 μm or more, the thickness of the water repellent film 4 in the vicinity of the periphery of the nozzle hole 1 is sufficiently increased, so that the wiping durability of the liquid discharge surface 3 of the nozzle plate 1 is improved. be able to.
The thickness of the water repellent film was determined by observation with an electron microscope using the above-described observation method using an electron microscope, and the contrast between the water repellent film applied on the nozzle substrate and the epoxy resin. As shown in FIG. 2C, the nozzle substrate is inclined so that the thickness decreases toward the nozzle hole, whereas the water-repellent film is substantially linear in the vicinity of the nozzle hole and the part away from the nozzle hole. Therefore, it was confirmed that the difference between the maximum thickness and the minimum thickness of the water-repellent film 4 (maximum thickness-minimum thickness) was equal to the difference between the maximum thickness and the minimum thickness in the nozzle substrate 8. .

As shown in FIG. 2D, it is preferable that the hole diameter in the nozzle hole 1 of the nozzle substrate 8 has a tapered shape that gradually increases from the water repellent film 4 side. Thereby, the discharge characteristic of the liquid from the liquid discharge surface 3 of the nozzle plate 2 is improved.
The hole diameter of the liquid chamber bonding surface 6 of the nozzle substrate 8 is preferably 10 μm to 50 μm. On the other hand, the hole diameter of the surface 13 on the liquid discharge side of the nozzle substrate 8 is preferably 15 μm to 30 μm. In addition, when the hole shape of the nozzle hole 1 is not circular, a circumscribed circle corresponding to the hole shape of the nozzle hole 1 is drawn, and the hole diameter of the nozzle hole 1 can be obtained from the diameter of the circumscribed circle.

<Nozzle plate>
The nozzle plate 2 includes the nozzle substrate 8 and the water-repellent film 4 on the nozzle substrate 8.

―Nozzle substrate―
The nozzle substrate 8 has a plurality of the concave portions 5 on one surface, and the nozzle holes 1 are provided in the concave portions 5, and there are no particular restrictions on the shape, size, material, structure, and the like. Can be appropriately selected according to the purpose.
The nozzle substrate 8 has a liquid discharge side surface 13 through which liquid is discharged from the nozzle hole 1, which is a surface on the side having the recess 5, and a liquid chamber located on the opposite side of the liquid discharge side surface 13. And a joining surface 6.
The water-repellent film 4 is formed on the surface 13 on the liquid ejection side having the concave portion 5 of the nozzle substrate 8.

There is no restriction | limiting in particular as a planar shape of the said nozzle substrate 8, According to the objective, it can select suitably, For example, a rectangle, a square, a rhombus, a circle, an ellipse etc. are mentioned. Examples of the cross-sectional shape of the nozzle substrate 8 include a flat plate shape and a plate shape.
There is no restriction | limiting in particular as a magnitude | size of the said nozzle substrate 8, According to the magnitude | size of the said nozzle plate 2, it can select suitably.

The material of the nozzle substrate 8 is not particularly limited and may be appropriately selected depending on the purpose, for example, stainless steel, Al, Bi, Cr, InSn , ITO, Nb, Nb 2 O 5, NiCr, Si , SiO ₂ , Sn, Ta ₂ O ₅ , Ti, W, ZAO (ZnO + Al ₂ O ₃ ), Zn, and the like. These may be used alone or in combination of two or more. Among these, stainless steel is preferable from the viewpoint of rust prevention.

There is no restriction | limiting in particular as said stainless steel, According to the objective, it can select suitably, For example, austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, precipitation hardening stainless steel, etc. are mentioned. These may be used alone or in combination of two or more.
Examples of the austenitic stainless steel include SUS201, SUS202, SUS301, SUS302, SUS303, SUS303Se, SUS304, SUS304L, SUS304N1, SUS304N2, SUS304LN, SUS305, SUS309S, SUS310S, SUS316L, SUS316L, SUS316L, SUS316L, SUS316L, SUS316L, SUS316L, SUS316L Examples include SUS317, SUS317L, SUS317J1, SUS321, SUS347, SUSXM7, SUSXM15J1, and SUS329J1.
Examples of the ferritic stainless steel include SUS405, SUS410L, SUS430, SUS430F, SUS434, SUS447J1, and SUSXM27.
Examples of the martensitic stainless steel include SUS403, SUS410, SUS410J1, SUS416, SUS420J1, SUS420F, SUS431, SUS440A, SUS440B, SUS440C, and SUS440F.
Examples of the precipitation hardening stainless steel include SUS630 and SUS631.

  The surface 13 on the liquid ejection side of the nozzle substrate 8 may be subjected to oxygen plasma treatment to introduce hydroxyl groups from the viewpoint of improving the adhesion between the water repellent film 4 and the nozzle substrate 8.

―Recesses―
If the concave portion 5 is provided on the liquid ejection side surface 13 which is one flat surface of the nozzle substrate 8 and has the nozzle hole 1 therein, the shape, size, number, arrangement, and interval thereof are provided. There is no restriction | limiting in particular about etc., According to the objective, it can select suitably.
The shape of the recess 5 is not particularly limited as long as it is a shape that is recessed from the flat surface that is the reference surface when the liquid discharge side surface 13 that is one flat surface of the nozzle substrate 8 is used as a reference surface. It can be appropriately selected depending on the purpose. For example, the thickness of the water repellent film 4 formed on the recess 5 is such that the thickness of the nozzle substrate 8 gradually decreases from the outer edge 7 of the recess 5 toward the vicinity where the nozzle hole 1 is located. Can be formed thick, and this is preferable from the viewpoint of improving wiping durability.
There are no particular restrictions on the number, arrangement, spacing, etc. of the recesses 5, which can be appropriately selected according to the number, arrangement, spacing, etc. of the nozzle holes 1 described later.
The recess 5 preferably has the nozzle hole 1 at the bottom including the deepest position of the recess 5.
Here, as shown in FIGS. 2D and 2E, a plurality of the recesses 5 are formed on the surface 13 of the nozzle substrate 8 on the liquid discharge side. The nozzle hole 1 is provided at the bottom of the recess 5 (the deepest position of the recess 5). The recess 5 is formed in a shape in which the thickness of the nozzle substrate 8 gradually decreases from the outer edge 7 of the recess 5 toward the vicinity where the nozzle hole 1 is located. The nozzle substrate 8 has a minimum thickness D at the open end 100.
The shape of the recess 5 is preferably substantially circular in plan view. In this case, the length corresponding to the substantially diameter of the substantially circular recess 5 (the maximum length between the outer edge 7 and the outer edge 7 of the recess 5) is preferably 10 μm to 50 μm.
The method for forming the recess 5 will be described in detail in the method for manufacturing the liquid discharge head described later.

―Nozzle hole―
As long as the nozzle hole 1 is provided in the recess 5, the number, arrangement, interval, opening shape, opening size, opening cross-sectional shape, and the like are not particularly limited, depending on the purpose. It can be selected appropriately.
There is no restriction | limiting in particular as an arrangement | sequence of the said nozzle hole 1, According to the objective, it can select suitably, For example, the said several nozzle hole 1 is located in a line at equal intervals along the length direction of the said nozzle board | substrate 8. And the like are arranged.
The arrangement of the nozzle holes 1 can be appropriately selected according to the type of liquid (ink) to be ejected, but is preferably 1 to 4 rows, more preferably 1 to 4 rows.
There is no restriction | limiting in particular as the number of the said nozzle holes 1 per said row | line | column, Although it selects suitably according to the objective, 10-10,000 are preferable and 50-500 are more preferable.
There is no restriction | limiting in particular as the space | interval (pitch) P which is the shortest distance between the centers of the said adjacent nozzle hole 1, Although it can select suitably according to the objective, For example, 21 micrometers-169 micrometers are preferable.
In other words, the number of nozzle holes and the interval (pitch) P are preferably in the range of 150 dpi (pitch is 169 μm) to 1,200 dpi (pitch is 21 μm). For example, in the case of 300 dpi, the pitch is 84 μm.
There is no restriction | limiting in particular as an opening shape of the said nozzle hole 1, According to the objective, it can select suitably, For example, circular, an ellipse, a square etc. are mentioned. Among these, a circular shape is preferable from the viewpoint of discharging ink droplets.

-Water repellent film-
The water repellent film 4 is formed on the liquid discharge side surface 13 having the plurality of recesses 5 in the nozzle substrate 8, and the shape, structure, material, thickness and the like are not particularly limited, It can be selected as appropriate according to the conditions.
The meaning of the repelling property means that the surface on the liquid ejection side does not get wet with ink after wiping with a wiper. For that purpose, the one with a relatively high contact angle (for example, 30 degrees or more) expresses the property. It matches. The contact angle can be measured according to JIS R-3257 by replacing pure water with ink.

  As the material of the water repellent film 4, a perfluoropolyether compound is used because it is excellent in water repellency with respect to water-based ink, oil-based ink, solvent ink, and the like. Suitable examples of the perfluoropolyether compound include perfluoropolyether compounds having a polar group at the terminal.

Examples of the terminal polar group include an alkoxysilane residue, —OH, C═O, —COOH, —NH ₂ , —NO ₂ , —NH ₃ , —CN, and the like. Among these, an alkoxysilane residue is preferable from the viewpoint of adhesion to the nozzle substrate.

Examples of the perfluoropolyether compound having an alkoxysilane residue at the terminal include compounds represented by the following general formulas (1) to (8).
However, in said general formula (1)-(8), X and Y represent the coupling | bond part of a perfluoropolyether chain | strand and an alkoxysilane residue, and R represents an alkyl group. n represents an integer of 0 or more.

The binding sites X and Y are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include substituents represented by the following structural formulas.

As the alkyl group, for example, an alkyl group having 1 to 25 carbon atoms is preferable, and specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group. , neopentyl group, a hexyl group, a cyclohexyl group, an octyl group, nonyl group, decyl _{group, C 12 H 25, C 14} H 29, C 16 H 33, C 18 H 37, C 24 , etc. _{H 49} and the like.
Said n represents an integer greater than or equal to 0, and 0-10 are preferable.

As the perfluoropolyether compound, an appropriately synthesized product or a commercially available product may be used.
Examples of the commercially available products include krytoxFSL, krytoxFSH (all manufactured by DuPont), FomblinZ, FLUOROLINKS10, FLUOROLLINKC10 (all manufactured by Solvay Solexis), Morescophospharol A20H Morescophospharol ADOH, Scophosphorol DDOH (all manufactured by Matsumura Oil Research Institute), Fluorosurf FG5010, Fluorosurf FG5020, Fluorosurf FG5060, Fluorosurf FG5070 (all manufactured by FluoroTechnology) These may be used alone or in combination of two or more.

  The method for forming the water repellent film will be described in detail in the method for manufacturing a liquid discharge head described later.

<Liquid>
The liquid is not particularly limited as long as it is a liquid that can be discharged by the liquid discharge head, and can be appropriately selected according to the purpose. For example, ink, inkjet ink, photopolymerizable ink, pretreatment liquid, Fixing treatment liquid, resist, pattern forming material and the like can be mentioned. Among these, inkjet ink is particularly preferable.

<Other members>
There is no restriction | limiting in particular as said other member, According to the objective, it can select suitably, For example, a pressurization chamber, a stimulus generation means, etc. are mentioned.

―Pressurizing chamber―
The pressurizing chamber is a plurality of individual flow paths that are individually arranged corresponding to the plurality of nozzle holes 1 provided in the nozzle plate 2 and communicate with the nozzle holes 1. It may be called a liquid chamber, a pressure chamber, a discharge chamber, a liquid chamber, etc.

―Stimulus generation means―
The stimulus generating means is means for generating a stimulus to be applied to the liquid (ink).
There is no restriction | limiting in particular as a stimulus in the said stimulus generation means, According to the objective, it can select suitably, For example, heat | fever (temperature), a pressure, a vibration, light etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, heat and pressure are preferable.
Examples of the stimulus generating means include a heating device, a pressurizing device, a piezoelectric element, a vibration generating device, an ultrasonic oscillator, and a light. Specific examples of the stimulus generating means include a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. Shape memory alloy actuators using electrostatic force, electrostatic actuators using electrostatic force, and the like.

When the stimulus is “heat”, thermal energy corresponding to the recording signal is applied to the liquid (ink) in the liquid ejection head using, for example, a thermal head. Examples include a method in which bubbles are generated in the ink by the thermal energy, and the ink is ejected as droplets from the nozzle holes 1 of the nozzle plate 2 by the pressure of the bubbles.
When the stimulus is “pressure”, for example, by applying a voltage to the piezoelectric element bonded to the position called the pressure chamber in the ink flow path in the liquid ejection head, the piezoelectric element bends. . As a result, the volume of the pressure chamber shrinks, and the liquid (ink) is ejected as droplets from the nozzle holes 1 of the liquid ejection head.
Among these, a piezo method in which a voltage (applied to a piezo element and a liquid (ink) is allowed to fly is preferable.

Here, an example of the liquid discharge head of the present invention will be described with reference to FIG.
The liquid discharge head is configured by integrally fixing a flow path unit 31 and an actuator unit 32 via a frame 33.
The flow path unit 31 is formed by laminating the nozzle plate 2, the chamber plate 35, and the vibration plate 36, and the pressure chamber 38 is contracted by expansion and contraction of individual piezoelectric vibrators 37 that are pressure generating means of the actuator unit 32. The ink droplets are discharged after being expanded.

The nozzle plate 2 is formed with a plurality of nozzle holes 1 communicating with the pressure chamber 38.
The chamber plate 35 is formed by the pressure chamber 38 and a fluid resistance 34.
The diaphragm 36 is provided so as to face the convex portion 42 that contacts the tip of the piezoelectric vibrator 37, the elastically deformable diaphragm portion 43, and the pressure chambers 38.
A liquid supply port 45 from a common liquid chamber 41 provided in the frame 33 is formed.
A diaphragm portion 44 similar to the diaphragm portion 43 is also formed in the region facing the common liquid chamber 41.

  The flow path unit 31 is formed by joining a stainless steel chamber plate 35, the nozzle plate 2, and the vibration plate 36.

The vibration plate 36 can be elastically deformed by the displacement of the piezoelectric vibrator 37 on the rolled metal plate 48 and has corrosion resistance to the ink, for example, polyimide (PI), polyphenylene sulfide (PPS) resin, or the like. The polymer film 49 is laminated.
The diaphragm 36 is provided with positioning holes including through-holes at important points, and the convex portions 42 are formed by a rolled metal plate 48 by etching a region where the diaphragm portions 43 and 44 are formed. Yes.

  A water repellent film containing the perfluoropolyether compound is formed on the liquid ejection surface 3 of the nozzle plate 2 in order to ensure water repellency with the liquid.

The piezoelectric vibrator 37 serving as a pressure generating unit is joined to the outer side of the diaphragm 36 (on the side opposite to the pressure chamber 38) corresponding to the pressure chamber 38.
The diaphragm 36 and the piezoelectric vibrator 37 constitute a piezoelectric actuator that deforms the diaphragm portion 43 that is a movable part of the diaphragm 36.

  In the liquid discharge head, the piezoelectric vibrator 37 is formed without being divided by groove processing (slit processing). An FPC cable 50 for giving a driving waveform to each piezoelectric vibrator 37 is connected to one end face of the piezoelectric vibrator 37.

A configuration in which the liquid in the pressure chamber 38 is pressurized using a displacement in the d33 direction as the piezoelectric direction of the piezoelectric vibrator 37 may be employed.
The piezoelectric vibrator 37 may be configured to pressurize the liquid in the pressure chamber using a displacement in the d31 direction as the piezoelectric direction.
In the present embodiment, a configuration using displacement in the d33 direction is adopted.

The base member 51 is preferably formed of a metal material. If the material (material) of the base member 51 is a metal, heat storage due to self-heating of the piezoelectric vibrator 37 can be prevented.
The piezoelectric vibrator 37 and the base member 51 are bonded and bonded by an adhesive. However, when the number of channels increases, the temperature rises to near 100 ° C. due to self-heating of the piezoelectric vibrator 37, and the bonding strength decreases significantly. Will do.

  Further, due to self-heating, the temperature inside the head increases, and the liquid temperature rises. However, when the liquid temperature rises, the liquid viscosity decreases and the jetting characteristics are greatly affected. Therefore, by forming the base member 51 from a metal material and preventing heat storage due to self-heating of the piezoelectric vibrator 37, it is possible to prevent deterioration in jetting characteristics due to a decrease in bonding strength and a decrease in liquid viscosity. it can.

The FPC cable 50 is equipped with a plurality of driver ICs 52 for applying drive waveforms (electric signals) for driving each channel (corresponding to each pressure chamber 38).
The frame 33 is joined around the diaphragm 36 with an adhesive. The common liquid chamber 41 for supplying a liquid from the outside to the pressure chamber 38 is formed in the frame 33 so as to be disposed on the opposite side of the driver IC 52 and at least the base member 51. .
The common liquid chamber 41 communicates with the fluid resistance portion 34 and the pressure chamber 38 via a liquid supply port 45 of the vibration plate 36.
A damper chamber 53 is formed in the common liquid chamber 41 by the diaphragm portion 44, and a pressure wave generated in the common liquid chamber 41 by liquid discharge is attenuated to stabilize liquid discharge.

  In the piezoelectric vibrator 37, piezoelectric layers (piezoelectric material layers) 54, internal electrodes 55A and internal electrodes 55B are alternately stacked, and common-side external electrodes 56 and individual-side external electrodes 57 are provided on both end faces. Thus, a plurality of the piezoelectric vibrators 37 are formed by slitting (grooving) to form grooves.

  In the liquid discharge head configured as described above, a drive pulse voltage of 20 V to 50 V is selectively applied to the drive unit of the piezoelectric vibrator 37. As a result, the drive unit to which the drive pulse voltage is applied extends in the stacking direction to deform the diaphragm unit 44 in the liquid discharge direction, and the liquid in the pressure chamber 38 is added by the volume or volume change of the pressure chamber 38. The liquid droplets are discharged from the nozzle hole 1.

(Liquid discharge head manufacturing method)
The method for producing a liquid discharge head of the present invention includes at least a nozzle substrate polishing step, and preferably includes a water-repellent film forming step. Further, if necessary, a cleaning step, a protective film attaching step, a water-repellent film removing step, It includes other processes such as a bonding process.

<Nozzle substrate polishing process>
In the nozzle substrate polishing step, one surface of the nozzle substrate 8 in which the plurality of nozzle holes 1 are formed is pressed through an elastic body 10, and the other surface of the nozzle substrate 8 is brought into contact with the polishing member 11. And polishing.
The one surface of the nozzle substrate 8 is the surface 13 on the liquid discharge side, and the other surface of the nozzle substrate 8 is the liquid chamber bonding surface 6.

By performing the nozzle substrate polishing step, the vicinity of the periphery of the nozzle hole 1 on the surface 13 of the nozzle substrate 8 on the liquid discharge side is selectively polished to form the recess 5. Here, the formation mechanism of the recess 5 will be described with reference to the drawings.
As shown in FIG. 5, the vicinity of the peripheral edge of the nozzle hole 1 of the nozzle substrate 8 is weak in rigidity, and the hole diameter of the nozzle hole 1 extends from the liquid discharge side surface 13 of the nozzle substrate 8 toward the liquid chamber bonding surface 6. If the taper is gradually increased, the rigidity of the nozzle substrate 8 in the vicinity of the periphery of the nozzle hole 1 is considered to be further weakened.
As shown in FIG. 6, such a nozzle substrate 8 is connected to the liquid discharge side from the liquid chamber bonding surface 6 of the nozzle substrate 8 through an elastic body 10 by a pressurizing means (not shown) in a polishing apparatus. When pressed toward the surface 13, the elastic body 10 enters the nozzle hole 1 from the liquid chamber joint surface 6 (10a in FIG. 6), and the rigidity of the peripheral edge 8a of the nozzle hole 1 is weakened. Protrudes substantially in the shape of a truncated cone on the surface 13 on the liquid discharge side. In the state where the peripheral edge 8a of the nozzle hole 1 protrudes in a substantially truncated cone shape, the surface 13 on the liquid discharge side of the nozzle substrate 8 is brought into contact with the polishing surface 15 of the polishing member 11 as shown in FIG. And polish. Then, the entire surface 13 on the liquid discharge side of the nozzle substrate 8 including the peripheral edge 8a of the nozzle hole 1 protruding in a substantially truncated cone shape is polished and flattened.
Then, when the pressure applied to the nozzle substrate 8 by the elastic body 10 is released, as shown in FIG. 8, the surface 13 on the liquid discharge side of the nozzle substrate 8 is substantially circular (in the thickness direction of the nozzle substrate 8). The concave portion 5 having a substantially tapered cross section is formed. The nozzle hole 1 is located at the bottom of the recess 5 (the deepest position of the recess 5).
As shown in FIG. 8, the recess 5 is formed so that the thickness of the nozzle substrate 8 gradually decreases from the outer edge 7 of the recess 5 toward the vicinity where the nozzle hole 1 is located.
The vicinity where the nozzle hole 1 is located means the opening end 100 of the nozzle hole 1 on the water-repellent film 4 side (surface 13 on the liquid discharge side) of the nozzle substrate 8.

The nozzle substrate 8 may be the same as that described for the liquid discharge head, but is preferably stainless steel.
There is no restriction | limiting in particular in the average thickness of the said nozzle substrate 8, Although it can select suitably according to the objective, 20 micrometers-75 micrometers are preferable. When the average thickness is in the range of 20 μm to 75 μm, the nozzle substrate 8 is appropriately deformed by the pressing of the elastic body 10, and the concave portion 5 is efficiently formed on the liquid discharge side surface 13 of the nozzle substrate 8. can do.

The elastic body 10 is not particularly limited as long as it has an elastic force when the nozzle substrate 8 is pressed, and the shape, material, hardness, thickness, structure, and the like are not particularly limited and may be appropriately selected according to the purpose. Can do.
Examples of the shape of the elastic body 10 include a sheet shape, a film shape, and a plate shape.
Examples of the material of the elastic body 10 include rubber and elastomer. Examples of the rubber include urethane rubber. Examples of the elastomer include thermoplastic elastomers.
The hardness of the elastic body 10 is preferably 40 degrees to 60 degrees for Shore A. When the hardness shore A is in the range of 40 degrees to 60 degrees, the concave portion 5 can be efficiently formed on the liquid discharge side surface 13 of the nozzle substrate 8, and the nozzle plate 2 having high wiping durability can be efficiently formed. Can be manufactured.
There is no restriction | limiting in particular as average thickness of the said elastic body 10, Although it can select suitably according to the objective, 0.5 mm-10 mm are preferable.

Examples of the polishing apparatus having the polishing member 11 and the pressurizing means 16 include an ultraprecision swing type single-side polishing machine (manufactured by Ebara Corporation).
There is no restriction | limiting in particular as the said polishing member 11, According to the objective, it can select suitably, For example, a polyurethane pad etc. are mentioned.
There is no restriction | limiting in particular as said abrasive | polishing agent, According to the objective, it can select suitably, For example, POLIPLA103 by FUJIMI company is diluted 4 times with a pure water (POLIPLA103: pure water = 1: 3 (volume ratio)). And the like.
Examples of the elastic member 10 include a urethane rubber sheet having a hardness Shore A of 40 degrees to 60 degrees.
The pressing force when pressing the nozzle substrate 8 through the elastic body 10 with the polyurethane pad as the polishing member 11, the rotation speed (rpm) when rotating the polyurethane pad, the amount of the polishing agent, the polishing time Adjust as appropriate. Thereby, the surface 13 on the liquid ejection side of the nozzle substrate 8 including the vicinity of the peripheral edge of the nozzle hole 1 can be flattened, and the surface roughness Ra of the nozzle substrate 8 can be 1 μm or less.
The pressing by the elastic body 10 is not particularly limited and can be appropriately selected according to the purpose. However, the protruding amount in the vicinity of the peripheral edge of the nozzle hole 1 of the nozzle substrate 8 is 1.0 μm to 4.0 μm. The degree is preferred.

When the surface roughness Ra of the surface 13 on the liquid discharge side of the nozzle substrate 8 is 0.1 μm or less, the water repellent film 4 is efficiently formed on the surface 13 on the liquid discharge side of the nozzle substrate 8. It is possible to prevent the water-repellent film 4 from peeling off due to repeated wiping.
The surface roughness (Ra) of the surface 13 on the liquid ejection side of the nozzle substrate 8 can be measured according to JIS 0601. For example, the surface roughness is measured using a stylus type surface shape measuring device (Dektak 150, manufactured by ULVAC). be able to.

<Washing process>
The cleaning step is a step of ultrasonically cleaning the nozzle substrate 8 polished in the nozzle substrate polishing step.
The nozzle substrate 8 after being polished in the nozzle substrate polishing step is preferably subjected to ultrasonic cleaning using a solvent in a wet environment so that the surface of the polished nozzle substrate 8 is not dried. The wet environment is preferably a humidity of 50% RH or more from the viewpoint of drying prevention.
Examples of the solvent include pure water, alcohols such as acetone, ethanol, and isopropanol; hydrofluoroethers such as Novec (manufactured by Sumitomo 3M Co., Ltd.), Bertrell (manufactured by DuPont), Galden (manufactured by Solvay Solexis), and the like. Can be mentioned.
As cleaning methods other than the ultrasonic cleaning, for example, scrub cleaning, shower cleaning (for example, high pressure spray cleaning, ultrasonic shower cleaning, etc.), immersion cleaning (for example, running water cleaning, jet cleaning, bubbling cleaning, etc.), steam cleaning Etc.
The nozzle substrate 8 after the cleaning is preferably subjected to oxygen plasma treatment. By performing the oxygen plasma treatment, a hydroxyl group can be introduced into the surface of the nozzle substrate 8 and the adhesion between the water repellent film 4 and the nozzle substrate 8 is improved.

<Water repellent film forming process>
The water repellent film forming step is a step of forming a water repellent film containing a perfluoropolyether compound on the other surface of the nozzle substrate polished by the nozzle substrate polishing step.
The other surface of the nozzle substrate 8 is the surface 13 on the liquid ejection side of the nozzle substrate 8.

As the perfluoropolyether compound, the same compounds as those described for the liquid discharge head can be used.
The liquid containing the perfluoropolyether compound is prepared using a solvent so that the content of the perfluoropolyether compound is 0.1% by mass to 1% by mass.
There is no restriction | limiting in particular as said solvent, According to the objective, it can select suitably, For example, a fluorine-type solvent etc. are mentioned.
As the fluorine-based solvent, commercially available products can be used. -5080 (both manufactured by Sumitomo 3M Co., Ltd.), Bertrell (manufactured by DuPont), Galden (manufactured by Solvay Solexis), and the like. These may be used alone or in combination of two or more.

It is preferable that a liquid containing the perfluoropolyether compound is applied to the nozzle substrate 8 and naturally dried at room temperature. The liquid containing the perfluoropolyether compound is preferably applied to at least one of the liquid discharge side surface 13 and the liquid chamber bonding surface 6 of the nozzle substrate 8.
First, a liquid containing the perfluoropolyether compound is applied to the nozzle substrate 8 polished in the nozzle substrate polishing step and having the recess 5 formed on the surface 13 on the liquid discharge side, and then naturally dried at room temperature. To do. At that time, the water-repellent film 4 formed on the nozzle substrate 8 is stabilized by a force to minimize the surface area by the surface tension of the liquid containing the perfluoropolyether compound. Therefore, the water repellent film 4 is formed on the surface of the nozzle substrate 8 in a flat state.
The normal temperature in the coating is 20 ° C. to 30 ° C., preferably naturally dried at the temperature for 30 minutes to 2 hours, and more preferably naturally dried at 25 ° C. for 1 hour.
There is no restriction | limiting in particular as a method of apply | coating the liquid containing the said perfluoro polyether compound to the said nozzle substrate 8, It can select suitably according to the objective, For example, a dipping method, a roller coating method, a spray coating method, Examples include spin coating. Among these, the dipping method is preferable. According to the dipping method, as shown in FIG. 9C, the water-repellent film 4 in a flat state is efficiently formed on both surfaces (the liquid discharge side surface 13 and the liquid chamber bonding surface 6) of the nozzle substrate 8. be able to.
In the immersion method, when the nozzle substrate 8 is immersed in a liquid containing the perfluoropolyether compound for 30 seconds to 2 minutes and the nozzle substrate 8 is pulled up at a speed of 1 mm / sec to 5 mm / sec, the nozzle substrate The water-repellent film 4 is formed on both surfaces of 8.

Next, the water-repellent film 4 formed on the nozzle substrate 8 is heated at 80 ° C. to 120 ° C. for about 1 hour to 10 hours to fix the water-repellent film 4 to the nozzle substrate 8. Can do.
If the perfluoropolyether compound adheres excessively to the nozzle substrate 8, it can be removed by ultrasonic cleaning in a fluorine-based solvent. There is no restriction | limiting in particular in the time of the said ultrasonic cleaning, Although it can select suitably according to the objective, 3 minutes-10 minutes are preferable.
Examples of the fluorine-based solvent include Novec HFE7100, Novec HFE7200 (both manufactured by Sumitomo 3M Co., Ltd.), Vertrel (manufactured by DuPont), and the like.

  By performing the water repellent film forming step, the nozzle plate 2 having the water repellent film 4 on the nozzle substrate 8 can be produced. When the water repellent film 4 is formed on both surfaces (the liquid discharge side surface 13 and the liquid chamber bonding surface 6) of the nozzle substrate 8 by the dipping method, a protective film attaching step and a repellent property described below are performed. By performing the water film removing step, the nozzle plate 2 can be produced.

<Protective film application process>
Since the water-repellent film 4 is formed on both surfaces of the nozzle substrate 8 when the protective film is applied by the dipping method, the water-repellent film formed on the liquid discharge side surface 13 of the nozzle substrate 8. In order to protect 4, a protective film 18 is attached to the surface of the water repellent film 4 on the surface 13 of the nozzle substrate 8 on the liquid discharge side.
There is no restriction | limiting in particular as the said protective film 18, According to the objective, it can select suitably, For example, the cross tape (made by Mitsui Chemicals) etc. which are the high clean adhesive plus chip tapes for semiconductors are mentioned.

<Water repellent film removal process>
When the water-repellent film removing step is applied by the dipping method, the water-repellent film 4 is formed on both surfaces of the nozzle substrate 8, so that the water-repellent film is positioned on the opposite side to the liquid discharge side surface 13 of the nozzle substrate 8. In this step, the water repellent film 4 is removed from the liquid chamber bonding surface 6 by plasma treatment.
In the protective film attaching step, the liquid chamber bonding surface 6 of the nozzle substrate 8 in a state where the protective film 18 is attached to the surface of the water repellent film 4 formed on the liquid discharge side surface 13 of the nozzle substrate 8. Plasma treatment is performed from the side. Thereby, the water-repellent film 4 attached or formed on the liquid chamber bonding surface 6 of the nozzle substrate 8 and the inner wall of the nozzle hole 1 can be removed.
There is no restriction | limiting in particular as said plasma processing, According to the objective, it can select suitably, For example, oxygen plasma is irradiated using plasma cleaner PDC-510 (made by Yamato Scientific Co., Ltd.), and it reverses for 1 minute at 50 sccm. Examples include a sputtering method.

<Joint process>
The joining step is a step of joining the liquid chamber joining surface 6 of the nozzle plate 2 and the flow path plate forming the liquid chamber via an adhesive.

There is no restriction | limiting in particular as said adhesive agent, According to the objective, it can select suitably, For example, the epoxy adhesive which does not harden | cure at normal temperature, and does not harden | cure at 60 to 100 degreeC. Agents and the like.
Examples of the room temperature curable epoxy adhesive include Scotch Weld two-component epoxy room temperature curable adhesive DP-460EG (manufactured by Sumitomo 3M Co., Ltd.).
Examples of the epoxy adhesive that does not cure at normal temperature and starts curing at 60 ° C. to 100 ° C. include AE901 series (manufactured by Ajinomoto Fine Techno Co., Ltd.).

In the joining step, it is preferable to heat and pressure-bond in order to maintain the adhesion state for a long time.
The heating temperature is preferably 80 ° C. or less, and more preferably 30 ° C. to 80 ° C., from the viewpoint of avoiding fatigue of the members constituting the ink discharge head due to heat. The heating and pressure bonding time is preferably 2 hours to 4 hours from the viewpoint of productivity.

The bonding step is preferably performed within one day from the end of the water repellent film forming step or the end of the water repellent film removing step.
The perfluoropolyether compound is oily at room temperature and has high fluidity, and the mobility of the water repellent film 4 formed on the nozzle substrate 8 is very high. Therefore, the water repellent film 4 may be formed again on the liquid chamber bonding surface 6 of the nozzle substrate 8 depending on the elapsed time from the end of the water repellent film forming step or the end of the water repellent film removing step. In such a state, when the liquid chamber bonding surface 6 of the nozzle plate 2 and the flow path plate forming the liquid chamber are bonded, the adhesiveness between the two is low, so that the durability of the manufactured liquid discharge head is lowered. . Therefore, the durability of the manufactured liquid discharge head can be greatly improved by performing the bonding step within one day after the completion of the water repellent film forming step or the water repellent film removing step.

  Here, based on the procedure of the process chart of the manufacturing method of the liquid ejection head shown in FIG. 3, the manufacturing method of the liquid ejection head of the present invention will be described with reference to the drawings. The manufacturing method of the liquid discharge head includes the water repellent film 4 formed on both surfaces of the nozzle substrate 8 by the dipping method, and includes the protective film attaching step and the water repellent film removing step.

First, as shown in FIG. 2A, FIG. 2B, and FIG. 5, the predetermined number of nozzle holes 1 having a predetermined diameter are formed in four rows in a predetermined length direction at a predetermined interval (pitch) P. The nozzle substrate 8 made of stainless steel having a size is prepared.
Next, using a CMP polishing apparatus having the polishing member 11 and the pressurizing means 16 shown in FIG. 4, the polishing member 11 is formed on the surface 13 on the liquid discharge side of the nozzle substrate 8 as shown in FIGS. The polished surface 15 is brought into contact. In that state, while pressing the pressure member 16 through the elastic body 10 with a pressure of 10 kPa, the polishing member 16 and the polishing member 16 are rotated at 50 rpm together with the polishing agent 17, and the liquid discharge side of the nozzle substrate 8 is rotated. The surface 13 is polished (nozzle substrate polishing step).

As the CMP polishing apparatus, for example, an ultra-precise swing type single-side polishing machine (manufactured by Ebara Corporation) was used.
For example, a polyurethane pad was used as the polishing member 11.
As the elastic body 10, for example, a urethane rubber sheet having a predetermined thickness and a hardness Shore A of 40 degrees was used.
As the abrasive 17, for example, POLIPLA103 manufactured by FUJIMI was diluted 4 times with pure water (POLIPLA103: pure water = 1: 3 (volume ratio)).

By performing the polishing, the nozzle substrate 8 after polishing as shown in FIGS. 2D, 8 and 9A is obtained.
As shown in FIGS. 2D, 8, and 9 </ b> A, a plurality of the recesses 5 are formed on the surface 13 on the liquid discharge side of the nozzle substrate 8 after polishing. The nozzle hole 1 is disposed at the bottom of the recess 5. The thickness of the nozzle substrate 8 gradually decreases from the outer edge 7 of the recess 5 toward the vicinity where the nozzle hole 1 is located, and the opening end 100 of the nozzle hole 1 of the nozzle substrate 8 is formed. Thus, the thickness of the nozzle substrate 8 is minimized.

Next, the polished nozzle substrate 8 is ultrasonically cleaned with pure water to remove foreign substances such as abrasives (cleaning step).
Next, the surface 13 on the liquid discharge side of the nozzle substrate 8 after the cleaning is subjected to oxygen plasma processing at 500 W and 50 sccm for 1 minute using a plasma processing apparatus (PDC-510, manufactured by Yamato Scientific Co., Ltd.). . Thereby, a hydroxyl group can be introduced into the surface 13 on the liquid ejection side of the nozzle substrate 8, and the adhesion between the water repellent film 4 and the nozzle substrate 8 is improved.

Next, for example, the perfluoropolyether compound obtained by diluting the perfluoropolyether compound (FG5020, manufactured by Fluoro Technology Co., Ltd.) to a concentration of 0.2% by mass using HFE7100 (manufactured by Sumitomo 3M Co., Ltd.) as a diluent. A liquid (hereinafter, also referred to as a dipping liquid) containing is prepared.
Next, as shown in FIG. 9A, the nozzle substrate 8 in which a plurality of recesses 5 are formed on the surface 13 on the liquid ejection side is immersed in a dipping solution containing the perfluoropolyether compound for 60 seconds, and 3 mm By pulling up at a speed of / sec, the water-repellent film 4 is formed on both surfaces of the nozzle substrate 8 as shown in FIG. 9B.

Next, the nozzle substrate 8 on which the water repellent film 4 is formed on both sides is left to stand at room temperature (25 ° C.) for 1 hour to be naturally dried. At that time, as shown in FIG. 9C, the surface tension of the dipping liquid containing the perfluoropolyether compound is stabilized by a force that minimizes the surface area. Therefore, the water repellent film 4 is formed in a flat state on the liquid chamber bonding surface 6 which is the surface opposite to the liquid discharge side surface 13 of the nozzle substrate 8.
Next, the nozzle substrate 8 having the water-repellent film 4 formed on both sides is heated at 120 ° C. for 2 hours to fix the water-repellent film 4 to the nozzle substrate 8.

Next, as shown in FIG. 9D, the tape 13 (manufactured by Mitsui Chemicals) as the protective film 18 is applied to the surface 13 on the liquid discharge side of the nozzle substrate 8 on which the water repellent film 4 is formed on both sides. Affix (protective film application process).
Next, as shown in FIG. 9D, oxygen plasma is applied from the liquid chamber bonding surface 6 side of the nozzle substrate 8 using a plasma cleaner PDC-510 (manufactured by Yamato Scientific Co., Ltd.) with the protective film 18 attached. And reverse sputtering is performed at 50 sccm for 1 minute. As a result, as shown in FIG. 9E, the water repellent film 4 attached or formed on the liquid chamber bonding surface 6 of the nozzle substrate 8 and the inner wall of the nozzle hole 1 is removed (water repellent film removing step). ). As described above, the nozzle plate 2 can be manufactured.

  Next, the liquid chamber joining surface 6 of the obtained nozzle plate 2 and the flow path plate forming the liquid chamber are, for example, curable epoxy adhesive (cured at 60 ° C. to 100 ° C. without curing at normal temperature. Adhesive of the type to be started, AE901 series, manufactured by Ajinomoto Fine Techno Co., Ltd.), and bonded by heating and pressurizing at 70 ° C. for 5 hours (bonding step). As described above, the liquid discharge head of the present invention can be manufactured.

(Image forming device)
The image forming apparatus of the present invention includes an ink storage unit, a liquid discharge head, and a cleaning unit, and further includes other units as necessary.

<Ink storage means>
The ink containing means is means for containing ink jet ink, and examples thereof include a tank and an ink cartridge.
The ink cartridge contains the ink-jet ink in a container, and further includes other members appropriately selected as necessary.
There is no restriction | limiting in particular as said container, The shape, a structure, a magnitude | size, a material, etc. can be suitably selected according to the objective, For example, it has an ink bag etc. which were formed with the aluminum laminate film, the resin film, etc. A thing etc. are suitable.

<Liquid discharge head>
The liquid discharge head is means for applying a stimulus to the ink-jet ink and causing the ink to fly to record an image on a recording medium.
The liquid discharge head of the present invention is used as the liquid discharge head.

-Inkjet ink-
There is no restriction | limiting in particular as said ink for inkjet, It can select suitably from well-known things, for example, Unexamined-Japanese-Patent No. 2008-260926, Unexamined-Japanese-Patent No. 2008-38156, Unexamined-Japanese-Patent No. 2005-161834, etc. Ink and the like disclosed in the above.

-Recording media-
The recording medium is not particularly limited and may be appropriately selected from known media. For example, plain paper, glossy paper, special paper, thread, fiber, fabric, leather, metal, plastic, glass, wood , Ceramics, OHP sheet, film and the like.

<Cleaning means>
The cleaning means is means for wiping the liquid discharge surface 3 of the nozzle plate 2 of the liquid discharge head with a blade 9.
There is no restriction | limiting in particular about the magnitude | size, material, shape, structure, etc. as said blade 9, According to the objective, it can select suitably.
There is no restriction | limiting in particular as a magnitude | size of the said blade 9, According to the objective, it can select suitably.
Examples of the material of the blade 9 include rubber and elastomer from the viewpoint of wiping the surface of the water repellent film 4 of the nozzle plate 2.
The shape of the blade 9 is not particularly limited as long as a wiping process can be performed, and can be appropriately selected according to the purpose. Examples thereof include a plate shape and a plate shape.

<Other means>
Examples of the other means include control means. The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

  Here, an example of an image forming apparatus equipped with the liquid discharge head of the present invention will be described with reference to FIGS. FIG. 11 is a schematic perspective view showing an example of an image forming apparatus equipped with the liquid discharge head of the present invention, and FIG. 12 is a schematic side view of the image forming apparatus of FIG.

The image forming apparatus includes a carriage 93 that is movable in the main scanning direction inside the apparatus main body 81, the liquid discharge head 94 of the present invention mounted on the carriage 93, and supplies the ink to the liquid discharge head 94. And a printing mechanism 82 composed of an ink cartridge or the like.
A sheet feeding cassette (or a sheet feeding tray) 84 on which a large number of sheets 83 can be stacked from the front side can be attached to the lower portion of the apparatus main body 81 in a detachable manner. Further, the manual feed tray 85 for manually feeding the paper 83 can be turned over.
The paper 83 fed from the paper feed cassette 84 or the manual feed tray 85 is taken in, and after a required image is recorded by the printing mechanism unit 82, the paper is discharged to a paper discharge tray 86 mounted on the rear side.

The printing mechanism 82 holds the carriage 93 slidably in the main scanning direction with a main guide rod 91 and a sub guide rod 92 which are guide members horizontally mounted on left and right side plates (not shown).
The carriage 93 has the liquid discharge head 94 that discharges ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk) in the plurality of nozzle holes 1 in the main scanning direction. They are arranged in the intersecting direction and mounted with the ink droplet ejection direction facing downward. In addition, each of the ink cartridges 95 for supplying ink of each color to the liquid discharge head 94 is replaceably mounted on the carriage 93.

  The ink cartridge 95 has an air port that communicates with the atmosphere above, a supply port that supplies the ink to the liquid ejection head 94 below, and a porous body filled with ink inside. The ink supplied to the liquid ejection head 94 is maintained at a slight negative pressure by the capillary force of the porous body. Further, as the liquid discharge head 94, the liquid discharge head 94 of each color is used here, but one liquid discharge head 94 having the nozzle holes 1 for discharging ink droplets of each color may be used.

  The carriage 93 is slidably fitted to the main guide rod 91 on the rear side (downstream side in the paper conveyance direction), and slidable on the front guide rod 92 on the front side (upstream side in the paper conveyance direction). It is location. In order to move and scan the carriage 93 in the main scanning direction, a timing belt 100 is stretched between a driving pulley 98 and a driven pulley 99 that are rotationally driven by a main scanning motor 97, and the timing belt 100 is moved to the carriage. The carriage 93 is reciprocated by forward and reverse rotation of the main scanning motor 97.

In order to convey the paper 83 set in the paper feed cassette 84 to the lower side of the liquid discharge head 94, a paper feed roller 101 and a friction pad 102 for separating and feeding the paper 83 from the paper feed cassette 84; A guide member 103 that guides the paper 83, a transport roller 104 that reverses and transports the fed paper 83, a transport roller 105 that is pressed against the peripheral surface of the transport roller 104, and the paper from the transport roller 104 And a tip roller 106 for defining 83 feed angles.
The conveying roller 104 is rotationally driven by a sub-scanning motor 107 through a gear train.

There is a printing receiving member 109 which is a paper guide member for guiding the paper 83 sent out from the transport roller 104 corresponding to the movement range of the carriage 93 in the main scanning direction on the lower side of the liquid discharge head 94. ing.
On the downstream side of the printing receiving member 109 in the sheet conveyance direction, there are a conveyance roller 111 and a spur 112 that are rotationally driven to send out the sheet 83 in the sheet discharge direction.
Further, the sheet discharge roller 113 and the spur 114 for sending the sheet 83 to the sheet discharge tray 86, and guide members 115 and 116 for forming a sheet discharge path are provided.
At the time of recording, the liquid discharge head 94 is driven in accordance with an image signal while moving the carriage 93, thereby discharging the ink onto the stopped sheet 83 to record one line, and the sheet 83. After the predetermined amount is conveyed, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 83 has reached the recording area, the recording operation is terminated and the paper 83 is discharged.

Further, a recovery device 117 for recovering the ejection failure of the liquid ejection head 94 is provided at a position outside the recording area on the right end side in the movement direction of the carriage 93.
The recovery device 117 includes a cap unit, a suction unit, and a cleaning unit.
The carriage 93 is moved to the recovery device 117 side during printing standby, and the liquid ejection head 94 is capped by the capping unit, and the nozzle hole 1 is kept in a wet state, thereby preventing ejection failure due to ink drying. To prevent. Further, by ejecting the ink not related to recording during recording or the like, the ink viscosity of all the nozzle holes 1 can be made constant and stable ejection performance can be maintained.

  When a discharge failure occurs, the nozzle hole 1 of the liquid discharge head 94 is sealed by the capping unit, and bubbles and the like are sucked out from the nozzle hole 1 by the suction unit through a tube. Ink, dust, etc. adhering to the surface are removed by wiping and the ejection failure is recovered. The sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the apparatus main body 81 and absorbed and held by an ink absorber inside the waste ink reservoir.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
<Production of liquid discharge head>
Based on the procedure of the process chart of the manufacturing method of the liquid discharge head shown in FIG. 3, the liquid discharge head was manufactured as follows.

-Nozzle substrate polishing process-
First, as shown in FIG. 2A, FIG. 2B, FIG. 2D, and FIG. 5, the nozzle hole diameter on the liquid discharge side surface 13 is 25 μm, and the nozzle hole diameter on the liquid chamber bonding surface 6 is 35 μm. The nozzle holes 1 have a pitch P of 85 μm (300 dpi), which is the shortest distance between the centers of the adjacent nozzle holes 1, and four nozzle hole rows arranged in 320 / row are formed, and the length is 34 mm × The nozzle substrate 8 made of stainless steel having a width of 16 mm and an average thickness of 20 μm was prepared.
Next, using the CMP polishing apparatus having the polishing member 11 and the pressurizing means 16 shown in FIG. 4, as shown in FIGS. 6 to 8, the liquid ejection side of the nozzle substrate 8 having the plurality of nozzle holes 1. The polished surface 15 of the polishing member 11 is brought into contact with the surface 13. In this state, while pressing the pressure member 16 through the elastic body 10 with a pressure of 10 kPa, the polishing member 11 is rotated at 50 rpm together with the polishing agent 17, and the liquid discharge side of the nozzle substrate 8 is changed. Surface 13 was polished.

As the CMP polishing apparatus, an ultra-precise swing type single-side polishing machine (manufactured by Ebara Corporation) equipped with a polyurethane pad as the polishing member 11 was used.
As the elastic body 10, a urethane rubber sheet (prototype (manufactured by NOK Corporation)) having an average thickness of 1 mm and a hardness Shore A adjusted to 40 degrees was used.
As the abrasive 17, POLIPLA103 manufactured by FUJIMI was diluted 4 times with pure water (POLIPLA103: pure water = 1: 3 (volume ratio)).

The nozzle substrate 8 subjected to the nozzle substrate polishing step is embedded with an epoxy resin (Epoch 812 (manufactured by Oken Shoji Co., Ltd.)) and cut at a diameter portion passing through the center of the nozzle hole 1 of the nozzle substrate 8. The cut surface of the obtained sample was observed with an electron microscope using the above-described observation method using an electron microscope, and the above-described image processing was performed on the obtained digital image. When the obtained processed image of the nozzle substrate 8 was observed, as shown in FIGS. 2D and 8, a plurality of the recesses 5 were formed on the surface 13 on the liquid ejection side of the nozzle substrate 8 after polishing. It was. The nozzle hole 1 having a diameter of 25 μm was formed at the bottom of the recess 5 (the deepest position of the recess 5). The recess 5 is formed in a shape in which the thickness of the nozzle substrate 8 gradually decreases from the outer edge 7 of the recess 5 toward the vicinity where the nozzle hole 1 is located. At the opening end 100, the thickness of the nozzle substrate 8 was minimized.
The shape of the concave portion 5 was circular in plan view. The length corresponding to the diameter of the circular recess 5 (the maximum length between the outer edge 7 and the outer edge 7 of the recess 5) was 35 μm.
The surface roughness Ra of the surface 13 on the liquid discharge side of the nozzle substrate 8 after polishing was 0.1 μm when measured as follows.
<Measurement of surface roughness Ra>
The surface roughness Ra of the surface 13 on the liquid ejection side of the nozzle substrate 8 was measured according to JIS 0601. Specifically, the surface roughness Ra was measured using a stylus type surface shape measuring device (Dektak 150, ULVAC, Inc.).

-Washing process-
Next, the nozzle substrate 8 after polishing was subjected to ultrasonic cleaning with pure water to remove foreign substances such as an abrasive.
Next, the surface 13 on the liquid ejection side of the nozzle substrate 8 after the cleaning was subjected to oxygen plasma treatment at 500 W and 50 sccm for 1 minute using a plasma processing apparatus (PDC-510, manufactured by Yamato Scientific Co., Ltd.). .

-Water repellent film forming process-
Next, a dipping solution was prepared by diluting a perfluoropolyether compound (FG5020, manufactured by Fluoro Technology Co., Ltd.) to a concentration of 0.2% by mass using HFE7100 (manufactured by Sumitomo 3M Co., Ltd.) as a diluent.
Next, as shown in FIG. 9A, the nozzle substrate 8 having a plurality of recesses 5 formed on the surface 13 on the liquid ejection side is dipped in a dipping solution containing the perfluoropolyether compound for 60 seconds, and 3 mm / The water-repellent film 4 was formed on both surfaces of the nozzle substrate 8 as shown in FIG.
Next, the nozzle substrate 8 on which the water-repellent film 4 was formed on both sides was left to stand at room temperature (25 ° C.) for 1 hour and dried naturally. At that time, as shown in FIG. 9C, the surface of the dipping liquid containing the perfluoropolyether compound is stabilized by a force that tends to minimize the surface area. The liquid chamber bonding surface 6, which is the surface opposite to the liquid discharge side surface 13, was formed in a flat state.
Next, the nozzle substrate 8 having the water-repellent film 4 formed on both surfaces was heated and fixed at 120 ° C. for 2 hours.

-Protective film application process-
Next, as shown in FIG. 9D, on the liquid discharge side surface 13 of the nozzle substrate 8 on which the water-repellent film 4 is formed on both sides, an isopropyl tape as the protective film 18 (manufactured by Mitsui Chemicals, Inc.) Was pasted.

-Water repellent film removal process-
Next, with the protective film 18 attached, as shown in FIG. 9D, a plasma cleaner PDC-510 (Yamato Scientific) is formed from the liquid chamber bonding surface 6 side of the nozzle substrate 8 on which the water repellent film 4 is formed. Oxygen plasma was radiated using a product manufactured by Co., Ltd., and reverse sputtering was performed at 50 sccm for 1 minute. As a result, as shown in FIG. 9E, the water repellent film 4 adhered or formed on the liquid chamber bonding surface 6 of the nozzle substrate 8 and the inner wall of the nozzle hole 1 was removed. After removing the excess water-repellent film 4, the protective film 18 was peeled from the surface 13 on the liquid discharge side of the nozzle substrate 8. Thus, the nozzle plate 2 was produced.

-Joining process-
Next, the liquid chamber joining surface 6 of the obtained nozzle plate 2 and the flow path plate forming the liquid chamber are cured at a low temperature curing type epoxy adhesive (not cured at room temperature but at 60 ° C. to 100 ° C. A type adhesive, AE901 series, manufactured by Ajinomoto Fine-Techno Co., Ltd.) and bonded by heating and pressing at 70 ° C. for 5 hours. Thus, the liquid discharge head of Example 1 was produced.

(Example 2)
-Production of liquid ejection head-
In Example 1, except that a urethane rubber sheet (prototype (manufactured by NOK Corporation)) having a hardness Shore A adjusted to 60 degrees was used as the elastic body 10 in the nozzle substrate polishing step, and Example 1 Similarly, the liquid discharge head of Example 2 was produced.

(Comparative Example 1)
-Production of liquid ejection head-
In Example 1, except that a urethane rubber sheet (prototype (manufactured by NOK Corporation)) having a hardness Shore A adjusted to 80 degrees was used as the elastic body 10 in the nozzle substrate polishing step, Similarly, the liquid discharge head of Comparative Example 1 was produced.

(Example 3)
-Production of liquid ejection head-
In Example 1, the liquid ejection head of Example 3 was produced in the same manner as in Example 1 except that the average thickness of the nozzle substrate 8 used in the nozzle substrate polishing step was 50 μm.

Example 4
-Production of liquid ejection head-
In Example 1, an average thickness of the nozzle substrate 8 used in the nozzle substrate polishing step is 50 μm, and a urethane rubber sheet (prototype (manufactured by NOK Co., Ltd.) having a hardness shore A adjusted to 60 degrees as the elastic body 10 is used. The liquid discharge head of Example 4 was produced in the same manner as in Example 1 except that)) was used.

(Comparative Example 2)
-Production of liquid ejection head-
In Example 1, an average thickness of the nozzle substrate 8 used in the nozzle substrate polishing step was 50 μm, and a urethane rubber sheet having a hardness shore A adjusted to 80 degrees as the elastic body 10 (prototype (manufactured by NOK Corporation) The liquid discharge head of Comparative Example 2 was produced in the same manner as in Example 1 except that the above method was used.

(Example 5)
-Production of liquid ejection head-
In Example 1, the liquid discharge head of Example 5 was produced in the same manner as in Example 1 except that the average thickness of the nozzle substrate 8 used in the nozzle substrate polishing step was set to 75 μm.

(Example 6)
-Production of liquid ejection head-
In Example 1, an average thickness of the nozzle substrate 8 used in the nozzle substrate polishing step was 75 μm, and a urethane rubber sheet (prototype (manufactured by NOK Corporation) with a hardness shore A adjusted to 60 degrees as the elastic body 10 was used. The liquid discharge head of Example 6 was produced in the same manner as in Example 1 except that)) was used.

(Comparative Example 3)
-Production of liquid ejection head-
In Example 1, an average thickness of the nozzle substrate 8 used in the nozzle substrate polishing step was 75 μm, and a urethane rubber sheet (prototype (manufactured by NOK Corporation) having a hardness shore A adjusted to 80 degrees as the elastic body 10 was used. The liquid discharge head of Comparative Example 3 was produced in the same manner as in Example 1 except that the above method was used.

(Comparative Example 4)
-Production of liquid ejection head-
In Example 1, a liquid discharge head of Comparative Example 4 was produced in the same manner as in Example 1 except that the average thickness of the nozzle substrate 8 used in the nozzle substrate polishing step was 100 μm.

(Comparative Example 5)
-Production of liquid ejection head-
In Example 1, an average thickness of the nozzle substrate 8 used in the nozzle substrate polishing step was 100 μm, and a urethane rubber sheet having a hardness shore A adjusted to 60 degrees as the elastic body 10 (prototype (manufactured by NOK Corporation) The liquid discharge head of Comparative Example 5 was produced in the same manner as in Example 1 except that the above method was used.

(Comparative Example 6)
-Production of liquid ejection head-
In Example 1, an average thickness of the nozzle substrate 8 used in the nozzle substrate polishing step was 100 μm, and a urethane rubber sheet (prototype (manufactured by NOK Corporation) having a hardness shore A adjusted to 80 degrees as the elastic body 10 was used. The liquid discharge head of Comparative Example 6 was produced in the same manner as in Example 1 except that the above method was used.

Next, with respect to the nozzle plate 2 and the nozzle substrate 8 produced in the examples and comparative examples, “the difference between the maximum thickness and the minimum thickness of the water-repellent film 4”, “the nozzle substrate 8”, as described below. The difference between the maximum thickness and the minimum thickness of the nozzle plate 2 ”and“ the ratio (A / B) of the maximum thickness A (μm) of the nozzle plate 2 to the minimum thickness B (μm) of the nozzle plate 2 ”were measured. The results are shown in Table 1-1 and Table 1-2.
Further, the ejection stability of the produced liquid ejection head was evaluated as follows. The results are shown in Table 1-2.

<Measurement of difference between maximum thickness and minimum thickness of nozzle substrate>
The above-described image processing was performed on the obtained digital image using the observation method using the electron microscope described above, and the difference between the maximum thickness and the minimum thickness of the nozzle substrate 8 was calculated.
Moreover, as for the said nozzle substrate 8 of Examples 1-6, the said recessed part 5 as shown to FIG. 1D is formed in the surface by the side of a liquid discharge by the said electron microscope observation, The outer edge of the said recessed part 5 It was found that the thickness of the nozzle substrate 8 gradually decreased from 7 toward the vicinity where the nozzle hole 1 is located.

<Measurement of difference between maximum thickness and minimum thickness of water repellent film>
The thickness of the water-repellent film was confirmed to be equal to the difference between the maximum thickness and the minimum thickness of the nozzle substrate 8 by observing with an electron microscope using the above-described observation method using an electron microscope.
Moreover, as for the said water-repellent film 4 of the said nozzle plate 2 of Examples 1-6, as shown in FIG. 1C, the said water-repellent film 4 of the vicinity in which the said nozzle hole 1 is located by the said electron microscope observation. It was found that the thickness of the water repellent film 4 is thicker than the thickness of the water repellent film 4 in the portion where the concave portion 5 is not located.

<Measurement of ratio (A / B) of maximum thickness A (μm) of nozzle plate and minimum thickness B (μm) of nozzle plate>
The prepared nozzle plate 2 is observed with an electron microscope using the above-described observation method using an electron microscope, and the obtained digital image is subjected to the above-described image processing. The maximum thickness A and the minimum thickness B of the nozzle plate 2 are The ratio (A / B) was calculated.

<Discharge stability evaluation method>
Each prepared liquid discharge head is mounted on an ink jet printer (RICOH GX-3000, manufactured by Ricoh Co., Ltd.), and an ink for ink for RICOH GX-3000 manufactured by Ricoh Co., Ltd. is used, based on the following evaluation criteria. Discharge characteristics were performed. Further, a discharge stability test was conducted as follows.
[Evaluation criteria for initial discharge characteristics]
○: normal without discharge failure ×: discharge failure-discharge stability test-
Next, cleaning was performed by the printer, and a discharge stability test was performed in which the liquid discharge surface 3 of the nozzle plate 2 was repeated 1,000 times. Thereafter, the discharge stability test was repeated up to a total of 10,000 wiping cycles by repeating the wiping cycle every 1,000 times. At this time, a nozzle check pattern was printed every 1,000 times, and the discharge state was visually evaluated. The time when abnormal ejection (bending or non-ejection of ink droplets) occurred was described as the number of wipings when ejection failure occurred.

  Here, FIG. 13A is a schematic cross-sectional view showing an example of a state before the liquid ejection surface 3 of the nozzle plate 2 of Example 1 is wiped with a blade. FIG. 13B is a schematic cross-sectional view showing an example of a state where the liquid ejection surface 3 of the nozzle plate 2 of the liquid ejection head in FIG. 13A is wiped with a blade.

As shown in FIG. 13A, the liquid discharge head of Example 1 has the recess 5 having the nozzle hole 1 formed in the surface 13 on the liquid discharge side of the nozzle substrate 8. The formed water-repellent film 4 can be formed thicker than the water-repellent film 4 where the recess 5 is not located. Therefore, even when wiping is repeatedly performed with the blade 9, the water-repellent film 4 having a sufficient thickness is maintained as shown in FIG. 13B. That is, when wiping is repeatedly performed with the blade 9, the water-repellent film 4 near the periphery of the nozzle hole 1 is partially peeled off or worn. Further, since the perfluoropolyether compound constituting the water repellent film 4 is oily, if the blade 9 is wiped even after the water repellent film 4 is formed, another position from the vicinity of the periphery of the nozzle hole 1 is obtained. In some cases, the water repellent film 4 may move. However, as a result of these, even if the water repellent film 4 near the periphery of the nozzle hole 1 is reduced, the thickness of the water repellent film 4 near the periphery of the nozzle hole 1 is sufficiently thick. Even when wiping is repeated with the blade 9, the water-repellent film 4 having a sufficient thickness is maintained as shown in FIG. 13B.
Therefore, the liquid discharge head according to the first embodiment can prevent a decrease in water repellency due to a decrease in the water repellent film 4 in the vicinity of the peripheral edge of the nozzle hole 1 due to repeated wiping with the blade 9, and the length of the liquid discharge head Life expectancy can be improved. This is apparent from the results in Table 1-2 because the liquid discharge head of Example 1 has a wiping durability of 10,000 times or more.

  As shown in FIG. 1A, the liquid discharge head of Comparative Example 6 has the water-repellent film 4 formed on the surface 13 on the liquid discharge side of the nozzle substrate 8. Since the concave portion 5 having the nozzle hole 1 is not formed on the substrate 8, the water repellent film 4 in the vicinity of the periphery of the nozzle hole 1 cannot be formed thick. Therefore, when the blade 9 repeatedly wipes the liquid discharge surface 3 of the nozzle plate 2, the water-repellent film 4 near the periphery of the nozzle hole 1 is reduced as shown in FIG. 1B, and the nozzle substrate 8 is exposed. As a result, the water repellency is lowered. This is apparent from the results shown in Table 1-2 because the liquid discharge head of Comparative Example 6 generates abnormal image quality after 4,000 times of wiping.

As shown in FIG. 14, the liquid discharge surface 3 of the nozzle plate 1 in Example 1 and Comparative Example 6 is painted with oil-based magic ink M (Mackey (manufactured by Zebra)) around the periphery of the nozzle hole 1, The Z part in FIG. 14 was recorded with a metal microscope at a magnification of 200 times.
15A is a photograph showing the state of the oily magic ink M in the vicinity of the peripheral edge of the nozzle hole 1 before wiping the liquid ejection surface 3 of the nozzle plate 2 of Example 1 with the blade 9, and FIG. 15B is an example. 2 is a photograph showing the state of the oil-based magic ink M in the vicinity of the peripheral edge of the nozzle hole 1 after wiping the liquid discharge surface 3 of the nozzle plate 2 with the blade 9.
16A is a photograph showing the state of the oily magic ink M in the vicinity of the peripheral edge of the nozzle hole 1 before wiping the liquid discharge surface 3 of the nozzle plate 2 of Comparative Example 6 with the blade 9, and FIG. 16B is a comparative example. 6 is a photograph showing the state of oil-based magic ink M in the vicinity of the periphery of the nozzle hole 1 after wiping the liquid ejection surface 3 of the nozzle plate 2 with the blade 9.
From the results of FIGS. 15A to 16B, compared with the nozzle plate 2 of Example 1, the nozzle plate 2 of Comparative Example 6 has oil-based magic ink M attached to the vicinity of the peripheral edge of the nozzle hole 1 (FIG. 16B). It has been found that the water-repellent film 4 in the vicinity of the periphery of the nozzle hole 1 is lost.

From the results of Table 1-1 and Table 1-2, in the liquid discharge heads of Examples 1 to 6, the difference between the maximum thickness and the minimum thickness of the water-repellent film 4 is 1.0 μm or more. It has been found that it has excellent wiping durability of 000 times or more. In this case, as the polishing conditions for the nozzle substrate 8, the average thickness of the nozzle substrate 8 is preferably 20 μm to 75 μm, and the hardness shore A of the elastic body 11 is preferably 40 degrees to 60 degrees. .
On the other hand, it has been found that the liquid ejection heads of Comparative Examples 1 to 6 cause ink ejection failure with the number of wiping operations less than 8,000.

As an aspect of this invention, it is as follows, for example.
<1> A nozzle substrate having a plurality of recesses on one surface and provided with nozzle holes in the recesses;
A water repellent film containing a perfluoropolyether compound disposed on a surface of the nozzle substrate having the plurality of recesses;
A nozzle plate having at least
The difference between the maximum thickness and the minimum thickness in the water repellent film is 1.0 μm or more,
In the liquid discharge head, the thickness of the water-repellent film in the vicinity of the nozzle hole is thicker than the thickness of the water-repellent film in a portion where the concave portion is not positioned.
<2> The liquid ejection head according to <1>, wherein the thickness of the nozzle substrate gradually decreases from the outer edge of the recess toward the vicinity where the nozzle hole is located.
<3> The liquid ejection head according to any one of <1> to <2>, wherein a hole diameter in the nozzle hole is a tapered shape that gradually increases from the water-repellent film side.
<4> A ratio (A / B) between the maximum thickness A (μm) of the nozzle plate and the minimum thickness B (μm) of the nozzle plate is 1.01 to 1.10. 3>. The liquid discharge head according to any one of 3).
<5> At least a nozzle substrate polishing step in which one surface of the nozzle substrate in which a plurality of nozzle holes are formed is pressed through an elastic body and the other surface of the nozzle substrate is brought into contact with a polishing member for polishing. This is a method for manufacturing a liquid discharge head.
<6> The method for producing a liquid ejection head according to <5>, wherein the elastic body has a hardness of 40 degrees to 60 degrees on Shore A.
<7> The method according to any one of <5> to <6>, wherein the nozzle substrate has an average thickness of 20 μm to 75 μm.
<8> From the above <5> to <7> including a water repellent film forming step of forming a water repellent film containing a perfluoropolyether compound on the other surface of the nozzle substrate polished by the nozzle substrate polishing step. A method for manufacturing a liquid discharge head according to any one of the above.
<9> The liquid ejection head according to <8>, wherein in the water repellent film forming step, a liquid containing a perfluoropolyether compound is applied to the nozzle substrate and is naturally dried at room temperature to form a water repellent film. It is a manufacturing method.
<10> storage means for storing inkjet ink;
A liquid ejection head that applies a stimulus to the inkjet ink and causes the ink to fly to record an image on a recording medium;
Cleaning means for wiping the liquid discharge surface of the nozzle plate of the liquid discharge head with a blade;
An image forming apparatus having
An image forming apparatus, wherein the liquid discharge head is the liquid discharge head according to any one of <1> to <4>.

DESCRIPTION OF SYMBOLS 1 Nozzle hole 2 Nozzle plate 3 Liquid discharge surface 4 Water repellent film 5 Recessed part 6 Liquid chamber joint surface 7 Outer edge of recessed part 8 Nozzle substrate 9 Blade 10 Elastic body 11 Polishing member 13 Surface on the liquid discharge side of nozzle substrate 15 Polishing surface 16 Pressure means 17 Abrasive 18 Protective film 100 Open end of nozzle hole of nozzle substrate

Japanese Patent Laid-Open No. 2003-19803 JP 2006-44226 A

Claims (10)

A nozzle substrate having a plurality of recesses on one surface, and nozzle holes provided in the recesses;
A water repellent film containing a perfluoropolyether compound disposed on a surface of the nozzle substrate having the plurality of recesses;
A nozzle plate having at least
The difference between the maximum thickness and the minimum thickness in the water repellent film is 1.0 μm or more,
The liquid discharge head according to claim 1, wherein a thickness of the water repellent film in the vicinity where the nozzle hole is located is thicker than a thickness of the water repellent film in a portion where the concave portion is not located. The thickness of the nozzle substrate in the vicinity where the nozzle hole is located is thinner than the thickness of the nozzle substrate where the recess is not located,
The liquid discharge head according to claim 1, wherein the thickness of the nozzle substrate gradually decreases from the outer edge of the recess toward the vicinity where the nozzle hole is located.   3. The liquid ejection head according to claim 1, wherein a hole diameter in the nozzle hole is a tapered shape that gradually increases from the water-repellent film side. 4.   4. The ratio (A / B) between the maximum thickness A (μm) of the nozzle plate and the minimum thickness B (μm) of the nozzle plate is 1.01 to 1.10. The liquid discharge head described.   It includes at least a nozzle substrate polishing step in which one surface of a nozzle substrate in which a plurality of nozzle holes are formed is pressed through an elastic body, and the other surface of the nozzle substrate is in contact with a polishing member for polishing. A method for manufacturing a liquid discharge head.   6. The method of manufacturing a liquid discharge head according to claim 5, wherein the hardness of the elastic body is 40 degrees to 60 degrees on Shore A.   The method for manufacturing a liquid ejection head according to claim 5, wherein an average thickness of the nozzle substrate is 20 μm to 75 μm.   8. The water repellent film forming step of forming a water repellent film containing a perfluoropolyether compound on the other surface of the nozzle substrate polished by the nozzle substrate polishing step. Manufacturing method of liquid discharge head.   The method of manufacturing a liquid discharge head according to claim 8, wherein in the water repellent film forming step, a liquid containing a perfluoropolyether compound is applied to the nozzle substrate and naturally dried at room temperature to form a water repellent film. Storage means for storing ink-jet ink;
A liquid ejection head that applies a stimulus to the inkjet ink and causes the ink to fly to record an image on a recording medium;
Cleaning means for wiping the liquid discharge surface of the nozzle plate of the liquid discharge head with a blade;
An image forming apparatus having
The image forming apparatus according to claim 1, wherein the liquid discharge head is the liquid discharge head according to claim 1.