JP2022080462A - Inkjet head and inkjet printer - Google Patents

Abstract

To provide an inkjet head having excellent repellency.SOLUTION: An inkjet head comprises a nozzle plate provided with a nozzle that discharges ink toward a recording medium. The nozzle plate includes a nozzle plate substrate, a primer layer, provided on a surface opposing to the recording medium, of the nozzle plate substrate, which is formed of a monomolecular film of a primer agent including a silicone atom and a carbon atom, and a repellent layer, provided on the primer layer, which is formed of a monomolecular film of a linear fluorine compound which has a perfluoroalkyl group as one terminal group at a surface side thereof and has the other terminal group coupled to the primer layer.SELECTED DRAWING: Figure 5

Description

Embodiments of the present invention relate to inkjet heads and inkjet printers.

For example, in an inkjet head that pressurizes ink with a piezoelectric element and ejects ink droplets from a nozzle provided on the nozzle plate, liquid repellency is imparted so that the ink does not adhere to the surface of the nozzle plate. In order to impart liquid repellency to the surface of the nozzle plate, a fluorine-based compound is formed on the surface of the nozzle plate substrate by a coating method or a vapor phase growth method to form a liquid repellent film.

JP-A-2007-106024

An object to be solved by the present invention is to provide an inkjet head having excellent liquid repellency and an inkjet printer provided with such an inkjet head.

The inkjet head of the embodiment includes a nozzle plate provided with a nozzle for ejecting ink toward a recording medium. The nozzle plate is provided on the nozzle plate substrate and the surface of the nozzle plate substrate facing the recording medium, and is formed on a primer layer made of a monomolecular film of a primer agent containing silicon atoms and carbon atoms, and on the primer layer. Includes a liquid repellent layer made of a monomolecular film of a linear fluorine compound bonded to the primer layer, which has a perfluoroalkyl group on the surface side as one terminal group. ..

The perspective view which shows the inkjet head which concerns on embodiment. An exploded perspective view showing an actuator substrate, a frame, and a nozzle plate constituting the inkjet head according to the embodiment. The schematic diagram which shows the inkjet printer which concerns on embodiment. The perspective view which shows the main part of the inkjet printer which concerns on embodiment. FIG. 3 is a cross-sectional view schematically showing the structure of the nozzle plate according to the embodiment. The graph which shows the XPS spectrum obtained about the nozzle plate which concerns on an Example. The graph which shows the XPS spectrum obtained about the nozzle plate which concerns on a comparative example.

Hereinafter, embodiments will be described with reference to the drawings.
FIG. 1 is a perspective view showing an on-demand type inkjet head 1 mounted on a head carriage of an inkjet printer according to an embodiment. In the following description, a Cartesian coordinate system including an X-axis, a Y-axis, and a Z-axis is used. The direction indicated by the arrow in the figure is the positive direction for convenience. The X-axis direction corresponds to the print width direction. The Y-axis direction corresponds to the direction in which the recording medium is conveyed. The Z-axis plus direction is the direction facing the recording medium.

Briefly with reference to FIG. 1, the inkjet head 1 includes an ink manifold 10, an actuator board 20, a frame 40, and a nozzle plate 50.

The actuator board 20 has a rectangular shape with the X-axis direction as the longitudinal direction. Examples of the material of the actuator substrate 20 include alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), aluminum nitride (Al N), and lead zirconate titanate (PZT: Pb (Zr,). Ti) O ₃ ) and the like can be mentioned.

The actuator substrate 20 is superposed on the ink manifold 10 so as to close the open end of the ink manifold 10. The ink manifold 10 is connected to the ink cartridge via the ink supply tube 11 and the ink return tube 12.

A frame 40 is mounted on the actuator board 20. A nozzle plate 50 is mounted on the frame 40. The nozzle plate 50 is provided with a plurality of nozzles N at predetermined intervals along the X-axis direction so as to form two rows along the Y-axis.

FIG. 2 is an exploded perspective view of the actuator substrate 20, the frame 40, and the nozzle plate 50 constituting the inkjet head 1 according to the embodiment. The inkjet head 1 is a side shooter type of a so-called shear mode shared wall.

The actuator substrate 20 is provided with a plurality of ink supply ports 21 at intervals along the X-axis direction so as to form a row at the central portion in the Y-axis direction. Further, on the actuator board 20, a plurality of ink ejection ports 22 are spaced along the X-axis direction so as to form rows in the Y-axis plus direction and the Y-axis minus direction with respect to the rows of the ink supply ports 21. It is provided open.

A plurality of actuators 30 are provided between the row of ink supply ports 21 in the center and the row of ink discharge ports 22 on one side. These actuators 30 form a row extending in the X-axis direction. Further, a plurality of actuators 30 are also provided between the row of the ink supply ports 21 in the center and the row of the other ink discharge ports 22. These actuators 30 also form a row extending in the X-axis direction.

Each of the rows of the plurality of actuators 30 is composed of a first piezoelectric body and a second piezoelectric body laminated on the actuator substrate 20. Examples of the material of the first and second piezoelectric bodies include lead zirconate titanate (PZT), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ) and the like. The first and second piezoelectric bodies are polarized in opposite directions along the thickness direction.

The laminated body made of the first and second piezoelectric bodies is provided with a plurality of grooves each extending in the Y-axis direction and arranged in the X-axis direction. These grooves are open on the side of the second piezoelectric body and have a depth larger than the thickness of the second piezoelectric body. Hereinafter, the portion of the laminated body sandwiched between the adjacent grooves is referred to as a channel wall. Each of these channel walls extends in the Y-axis direction and is arranged in the X-axis direction. The groove between the two adjacent channel walls is the ink channel through which the ink flows.

Electrodes are formed on the side walls and the bottom of the ink channel. These electrodes are connected to a wiring pattern 31 extending along the Y-axis direction.

A protective film (not shown) is formed on the surface of the actuator substrate 20 including the electrodes and the wiring pattern 31, except for the connection portion with the flexible printed circuit board described later. The protective film includes, for example, a plurality of layers of an inorganic insulating film and an organic insulating film.

The frame 40 has an opening. This opening is smaller than the actuator board 20 and larger than the area of the actuator board 20 where the ink supply port 21, the actuator 30, and the ink discharge port 22 are provided. The frame 40 is made of, for example, ceramics. The frame 40 is joined to the actuator substrate 20 by, for example, an adhesive.

The nozzle plate 50 includes a nozzle plate substrate, a primer layer provided on a surface facing the medium (a discharge surface for ejecting ink from the nozzle N), and a liquid repellent layer provided on the primer layer. The nozzle plate substrate is made of, for example, a resin film such as a polyimide film. The primer layer and the liquid-repellent layer will be described in detail later.

The nozzle plate 50 is larger than the opening of the frame 40. The nozzle plate 50 is joined to the frame 40, for example, with an adhesive.

The nozzle plate 50 is provided with a plurality of nozzles N. These nozzles N form two rows corresponding to the ink channels. The diameter of the nozzle N increases as it advances from the surface facing the recording medium toward the ink channel. The dimension of the nozzle N is set to a predetermined value according to the amount of ink ejected. The nozzle N can be formed, for example, by performing laser processing using an excimer laser.

The actuator substrate 20, the frame 40, and the nozzle plate 50 are integrated as shown in FIG. 1 to form a hollow structure. The area surrounded by the actuator substrate 20, the frame 40, and the nozzle plate 50 is an ink distribution chamber. The ink is supplied from the ink manifold 10 to the ink distribution chamber through the ink supply port 21, passes through the ink channel, and the excess ink circulates so as to return from the ink discharge port 22 to the ink manifold 10. A part of the ink is ejected from the nozzle N while flowing through the ink channel and used for printing.

A flexible printed circuit board 60 is connected to the wiring pattern 31 at a position on the actuator board 20 and outside the frame 40. A drive circuit 61 for driving the actuator 30 is mounted on the flexible printed circuit board 60.

Hereinafter, the operation of the actuator 30 will be described. Here, the operation will be described by focusing on the central ink channel among the three adjacent ink channels. Let A, B and C be the electrodes corresponding to the three adjacent ink channels. When no electric field is applied in the direction orthogonal to the channel wall, the channel wall is in an upright state.

For example, a voltage pulse having a potential higher than the potentials of the adjacent electrodes A and C is applied to the central electrode B to generate an electric field in a direction orthogonal to the channel wall. In this way, the channel wall is driven in shear mode, and the pair of channel walls sandwiching the central ink channel is deformed so as to expand the volume of the central ink channel.

Next, a voltage pulse having a potential higher than the potential of the central electrode B is applied to the electrodes A and C on both sides to generate an electric field in the direction orthogonal to the channel wall. In this way, the channel wall is driven in shear mode, and the pair of channel walls sandwiching the central ink channel is deformed so as to reduce the volume of the central ink channel. By this operation, pressure is applied to the ink in the central ink channel, and the ink is ejected from the nozzle N corresponding to this ink channel and landed on the recording medium.

For example, all the nozzles are divided into three groups, and the drive operation described above is time-division-controlled to perform three cycles to print on a recording medium.

FIG. 3 shows a schematic diagram of the inkjet printer 100. The inkjet printer 100 shown in FIG. 3 includes a housing provided with a paper output tray 118. In the housing, cassettes 1011 and 1012, paper feed rollers 102 and 103, transfer roller pairs 104 and 105, resist roller pairs 106, transfer belt 107, fan 119, negative pressure chamber 111, transfer roller pairs 112, 113 and 114, Ink cartridges 1151, 1152, 1153 and 1154, ink cartridges 1161, 1162, 1163 and 1164, and tubes 1171, 1172, 1173 and 1174 are installed.

The cassettes 1011 and 1012 contain recording media P having different sizes. The paper feed roller 102 or 103 takes out the recording medium P corresponding to the size of the selected recording medium from the cassette 1011 or 1012 and conveys it to the transport roller pairs 104 and 105 and the resist roller pair 106.

The conveyor belt 107 is tensioned by the drive roller 108 and the two driven rollers 109. Holes are provided on the surface of the transport belt 107 at predetermined intervals. Inside the conveyor belt 107, a negative pressure chamber 111 connected to a fan 119 for adsorbing the recording medium P to the conveyor belt 107 is installed. Transfer roller pairs 112, 113, and 114 are installed downstream of the transfer belt 107 in the transfer direction. A heater for heating the print layer formed on the recording medium P can be installed in the transport path from the transport belt 107 to the output tray 118.

Above the transport belt 107, four inkjet heads that eject ink to the recording medium P according to the image data are arranged. Specifically, an inkjet head 1151 that ejects cyan (C) ink, an inkjet head 1152 that ejects magenta (M) ink, an inkjet head 1153 that ejects yellow (Y) ink, and black (Bk) ink are ejected. Inkjet heads 1154 are arranged in this order from the upstream side. Each of the inkjet heads 1151, 1152, 1153 and 1154 is the inkjet head 1 described with reference to FIGS. 1 and 2.

Above the inkjet heads 1151, 1152, 1153 and 1154, there are cyan (C) ink cartridge 1161, magenta (M) ink cartridge 1162, yellow (Y) ink cartridge 1163, and black, respectively, containing the corresponding inks. (Bk) An ink cartridge 1164 is installed. These cartridges 1161, 1162, 1163 and 1164 are connected to the inkjet heads 1151, 1152, 1153 and 1154 by tubes 1171, 1172, 1173 and 1174, respectively.

Next, the image forming operation of the inkjet printer 100 will be described.
First, an image processing means (not shown) starts image processing for recording, generates an image signal corresponding to the image data, and generates a control signal for controlling the operation of various rollers, the negative pressure chamber 111, and the like. do.

Under the control of the image processing means, the paper feed roller 102 or 103 takes out the recording media P of the selected size one by one from the cassette 1011 or 1012 and transfers them to the transfer rollers 104 and 105 and the resist roller pair 106. do. The resist roller pair 106 corrects the skew of the recording medium P and conveys the recording medium P at a predetermined timing.

The negative pressure chamber 111 sucks air through the hole of the transport belt 107. Therefore, the recording medium P is sequentially conveyed to the lower positions of the inkjet heads 1151, 1152, 1153, and 1154 as the transfer belt 107 moves while being attracted to the transfer belt 107.

The inkjet heads 1151, 1152, 1153, and 1154 eject ink in synchronization with the timing at which the recording medium P is conveyed under the control of the image processing means. As a result, a color image is formed at a desired position on the recording medium P.

After that, the transport roller pairs 112, 113, and 114 discharge the recording medium P on which the image is formed to the output tray 118. When the heater is installed in the transport path from the transport belt 107 to the output tray 118, the print layer formed on the recording medium P may be heated by the heater. Heating with a heater can enhance the adhesion of the print layer to the recording medium P, especially when the recording medium P is impermeable.

FIG. 4 shows a perspective view of a main part of the inkjet printer 100. FIG. 4 depicts the inkjet head 1, the medium holding mechanism 110, the head moving mechanism 120, the blade moving mechanism 130, and the wiping blade 140 described above.

The medium holding mechanism 110 holds the recording medium P, for example, the recording paper, facing the inkjet head 1. The medium holding mechanism 110 also has a function as a recording paper moving mechanism for moving the recording medium. The medium holding mechanism 110 includes the transport belt 107, the drive roller 108, the driven roller 109, the negative pressure chamber 111, and the fan 119 of FIG. At the time of printing, the medium holding mechanism 110 moves the recording medium P so as to face the inkjet head 1 in a direction parallel to the printing surface of the recording medium P. Meanwhile, the inkjet head 1 ejects ink droplets from the nozzles and prints on the recording medium P.

The head moving mechanism 120 moves the inkjet head 1 to the printing position at the time of printing. Further, the head moving mechanism 120 moves the inkjet head 1 to the cleaning position at the time of cleaning.

The wiping blade 140 rubs the surface of the nozzle plate of the inkjet head 1 facing the recording medium, that is, the surface facing the recording medium, and removes deposits from the surface facing the recording medium. Here, the deposit is dust such as ink, dust, and dust, for example.

The blade moving mechanism 130 moves the wiping blade 140. Specifically, the blade moving mechanism 130 moves on the wiping blade 140 while pressing the wiping blade 140 against the recording medium facing surface of the nozzle plate 50 after the head moving mechanism 120 moves the inkjet head 1 to the cleaning position. Let me. As a result, deposits such as ink adhering to the surface facing the recording medium of the nozzle plate 50 are removed.
The wiping blade 140 and the blade moving mechanism 130 may be omitted.

In the inkjet head 1 described above, liquid repellency is imparted to the surface of the nozzle plate 50 facing the medium. In order to impart liquid repellency, a primer layer and a liquid repellent layer are provided on the surface facing the medium of the nozzle plate substrate. This will be described with reference to FIG.

FIG. 5 is a cross-sectional view schematically showing the structure of the nozzle plate 50 of FIGS. 1 and 2. As described above, the nozzle plate 50 includes a nozzle plate substrate 51, a primer layer 52, and a liquid repellent layer 53.

The primer layer 52 is provided on the surface of the nozzle plate substrate 51 facing the recording medium P. The primer layer 52 is made of a monomolecular film of a primer agent. The primer agent contains a silicon atom and a carbon atom.

The primer agent contains, for example, first and second reactive functional groups, a carbon skeleton and an alkoxysilyl group.

The first reactive functional group binds the primer agent to the nozzle plate substrate 51 by reacting with the functional group existing on the surface of the nozzle plate substrate 51. The first reactive functional group is, for example, an unsaturated hydrocarbon group such as a hydroxyl group, an epoxy group, an amino group, a methacrylic group or a vinyl group, or a mercapto group. The functional group present on the surface of the nozzle plate substrate 51 is, for example, a hydroxyl group, an ester bond, an amino group, or a thiol group.

The second reactive functional group binds the linear fluorine compound to the primer agent by reacting with the linear fluorine compound used for forming the liquid repellent layer 53. The linear fluorine compound will be described later. The second reactive functional group is, for example, a hydroxyl group or an alkoxy group such as a methoxy group and an ethoxy group.

The carbon skeleton connects the first reactive functional group and the second reactive functional group. The carbon skeleton contains one or more carbon atoms. The number of carbon atoms in the carbon skeleton is preferably in the range of 4 to 30, more preferably in the range of 4 to 22. The carbon skeleton preferably further contains one or more fluorine atoms. When the carbon skeleton has a fluorine atom, it has excellent liquid repellency.

The alkoxysilyl group is linked to the carbon skeleton. Hydrolysis of the alkoxysilyl group yields a silanol group. By causing dehydration condensation of silanol groups between adjacent molecules of the primer agent on the nozzle plate substrate 51, an intermolecular bond can be generated in the primer agent. As described above, it is preferable that the molecules of the primer agent are bound to each other. According to one example, the molecules of the primer agent adjacent to each other on the nozzle plate substrate 51 are bonded to each other by a siloxane bond (Si—O—Si). As a result, the primer agent forms a bond substantially parallel to the medium facing surface of the nozzle plate substrate 51.

Of the silanol groups generated by hydrolysis, the silanol groups that were not used for the intermolecular bond of the primer agent can be used for the bond between the primer agent and the linear fluorine compound.

As the primer agent, for example, a compound represented by the following general formula (1) can be used.

In the general formula (1), n is a natural number of 1 to 10. In the general formula (1), R1 and R2 are the above-mentioned first and second reactive functional groups, respectively. The compound represented by the general formula (1) contains a first and second reactive functional group, a carbon skeleton and an alkoxysilyl group.

In the general formula (1), the alkoxysilyl group is a trimethoxysilyl group, but the alkoxysilyl group may be a functional group such as a triethoxysilyl group. Further, in the general formula (1), the number of CF ₂ groups contained in the carbon skeleton is 2, but the number of CF ₂ groups may be 1 or 3 or more. Further, although the number of carbon atoms contained in the repeating unit of the carbon skeleton is 2, the number of carbon atoms may be 1 or 3 or more.

When a monomolecular film is formed using the above-mentioned primer agent, a primer layer 52 having a thickness of 0.7 nm to 1 nm is usually obtained.

The liquid repellent layer 53 is provided on the primer layer 52. The liquid repellent layer 53 is made of a monomolecular film of a linear fluorine compound. The linear fluorine compound is a linear molecule having a perfluoroalkyl group as one terminal group on the surface side and the other terminal group bonded to the primer layer 52.

The liquid repellent layer 53 can be formed, for example, by using a linear fluorine compound in which one terminal group is a perfluoroalkyl group and the other terminal group is a third reactive functional group.

The perfluoroalkyl group is linear. The number of carbon atoms of the perfluoroalkyl group can be selected within the range of 4 or less (C1 to C4). The perfluoroalkyl group is preferably upright along the perpendicular direction to the surface of the nozzle plate substrate 51. Increasing the number of carbon atoms of the perfluoroalkyl group makes it easier to erect the perfluoroalkyl group, but it has an adverse effect on the human body such as carcinogenicity.

The third reactive functional group binds the linear fluorine compound to the primer agent by reacting with the second reactive functional group. The third reactive functional group is, for example, a hydroxyl group or an alkoxy group such as a methoxy group and an ethoxy group.
The third reactive functional group binds a linear fluorine compound to a primer agent by reacting with a silanol group that was not used for the intermolecular bond among the silanol groups generated by hydrolysis of the alkoxysilyl group. It is also possible.

The linear fluorine compound has, for example, a spacer linking group that links the perfluoroalkyl group and the third reactive functional group. The presence of the spacer linking group is advantageous for the perfluoroalkyl group to have an upright structure along the perpendicular direction to the surface of the nozzle plate substrate 51. The spacer linking group is, for example, a perfluoropolyether group.

As the linear fluorine compound, for example, a compound represented by the following general formula (2) can be used.

In the general formula (2), p is a natural number from 1 to 50, and R3 is a third reactive functional group.

When a monomolecular film is formed using the above-mentioned linear fluorine compound, a liquid-repellent layer 53 having a thickness of 9 nm to 10 nm is usually obtained.

The nozzle plate 50 shown in FIG. 5 is obtained, for example, as follows. Here, as an example, it is assumed that the nozzle plate substrate 51 is made of polyimide and the primer agent contains an alkoxysilyl group.

First, a nozzle plate substrate 51 made of polyimide is prepared. The surface of the surface of the nozzle plate substrate 51 facing the recording medium P may have almost no functional group, for example, a hydroxyl group necessary for bonding with the primer agent. In such a case, it is preferable to perform the following pretreatment on the nozzle plate substrate 51 prior to the formation of the primer layer 52.

For example, the surface of the nozzle plate substrate 51 is subjected to ion plasma treatment in an argon-oxygen mixed gas to modify the surface. The ion plasma treatment is performed, for example, as follows. That is, the nozzle plate substrate 51 is installed in the vacuum chamber, and the air in the chamber is evacuated. Then, the atmosphere surrounding the nozzle plate substrate 51 is switched to an argon-oxygen mixed gas, and then plasma is generated.

By performing ion plasma treatment in an atmosphere containing oxygen, a ring-opening reaction is caused by the polyimide on the surface of the nozzle plate substrate 51, and this surface is modified with hydroxyl groups. In addition to this, dust adhering to the nozzle plate substrate 51 is removed by performing ion plasma treatment in an atmosphere containing argon.

The ion plasma treatment is preferably performed in an argon-oxygen mixed gas having an oxygen concentration of 50% by volume or less, and more preferably performed in an argon-oxygen mixed gas having an oxygen concentration in the range of 20 to 50% by volume. .. If the oxygen concentration is too high, the surface of the nozzle plate substrate 51 may be damaged and the surface may be roughened. If the surface of the nozzle plate substrate 51 is roughened, the bonding with the primer agent may be insufficient.

The ion plasma treatment is preferably performed for 100 seconds or longer, and more preferably 200 seconds or longer. If the plasma irradiation time is too short, the surface modification of the nozzle plate substrate 51 may not be sufficiently performed.

Next, a solution containing a primer is applied to the surface of the nozzle plate substrate 51. As the solution containing the primer, for example, a solution in which the primer is dissolved in an organic solvent can be used. Further, the solution can be applied by a usual method such as a spray method, a spin coating method, or a blade coating method.

Next, the laminate provided with the coating film containing the primer agent and the nozzle plate substrate 51 is heated. In this way, the primer agent is bonded to the polyimide and the coating film is dried. Heating is performed, for example, at 200 ° C. for 15 minutes.

The alkoxysilyl group of the primer is then hydrolyzed. Hydrolysis of the alkoxysilyl group of the primer produces a silanol group. Then, dehydration condensation of silanol groups occurs between the molecules of the primer agents adjacent to each other on the nozzle plate substrate 51. This forms an intermolecular bond of the primer agent.

In this way, the primer layer 52 is formed on the nozzle plate substrate 51.

Next, a solution containing a linear fluorine compound is applied to the surface of the primer layer 52 to form a liquid repellent layer 53. As the solution containing the linear fluorine compound, for example, a solution obtained by dissolving the linear fluorine compound in an organic solvent can be used. Further, for the application of the solution, the method described above for the solution containing the primer can be used.

Next, the laminate including the coating film containing the linear fluorine compound, the primer layer 52, and the nozzle plate substrate 51 is heated. In this way, a reaction is caused between the linear fluorine compound and the primer agent to bond the linear fluorine compound to the surface of the primer layer 52. As a result, a monomolecular film made of a linear fluorine compound is formed as the liquid repellent layer 53. Heating is performed, for example, at 200 ° C. for 15 minutes.

As described above, the nozzle plate 50 shown in FIG. 5 is obtained.

The nozzle plate 50 described above has excellent liquid repellency. Therefore, the inkjet head 1 provided with the nozzle plate 50 described above is also excellent in liquid repellency.

For the nozzle plate having a structure similar to the nozzle plate 50 described above, for example, a material having the above-mentioned structure for the primer agent and the above-mentioned structure for the linear fluorine compound in one molecule is used by omitting the primer layer. It can be obtained by forming a liquid-repellent layer on the nozzle plate substrate.

However, the molecule used for forming such a liquid-repellent layer is long because it has the above-mentioned structure for the primer agent and the above-mentioned structure for the linear fluorine compound in one molecule. Therefore, it is difficult to arrange these molecules precisely and orderly on the nozzle plate substrate.

On the other hand, the primer agent used for manufacturing the nozzle plate 50 described above has a relatively short molecular length. Therefore, the molecules of these primer agents can be easily arranged on the nozzle plate substrate 51 in a precise and orderly manner. Further, the linear fluorine compound used for manufacturing the nozzle plate 50 described above also has a relatively short molecular length. Therefore, it is easy to arrange the molecules of these linear fluorine compounds on the primer layer 52 in a precise and orderly manner. Therefore, the nozzle plate 50 having the above-mentioned two-layer structure of the primer layer 52 and the liquid-repellent layer 53 on the nozzle plate substrate 51 can achieve better liquid repellency than the above-mentioned nozzle plate without the primer layer. ..

Further, since the nozzle plate 50 described above has a two-layer structure of the primer layer 52 and the liquid-repellent layer 53 on the nozzle plate substrate 51, the number of moles of the primer agent and the number of moles of the linear fluorine compound are different. Do not have to match. Therefore, for example, the number of moles of the linear fluorine compound contained in the liquid repellent layer 53 can be increased as compared with the number of moles of the primer agent contained in the primer layer 52. Specifically, the second reactive functional group and the silanol group that was not used for the intermolecular bond are bonded to the molecules of different linear fluorine compounds, whereby the linear chain contained in the liquid repellent layer 53 is contained. The number of moles of the fluorine compound can be made larger than the number of moles of the primer agent contained in the primer layer 52. As described above, the nozzle plate 50 described above can easily achieve the desired liquid repellency.

The nozzle plate 50 described above includes a primer layer 52 made of a monomolecular film. Such a nozzle plate 50 is superior in adhesion and scratch resistance between the liquid-repellent layer and the nozzle plate substrate as compared with a nozzle plate in which the primer layer is a laminate of a plurality of monomolecular films. The scratch resistance is a property that deterioration of the liquid repellency due to scratching using a wiping blade 140 or the like is unlikely to occur.

The X-ray photoelectron spectroscopy (XPS) method can be used to determine whether or not the primer layer 52 is made of a monomolecular film. For example, the X-ray photoelectron spectroscopy (XPS) spectrum of the nozzle plate 50 obtained by etching the nozzle plate 50 including the liquid repellent layer 53, the primer layer 52, and the nozzle plate substrate 51 from the surface of the liquid repellent layer 53 is examined. This makes the above judgment possible.

Hereinafter, examples and comparative examples will be described.
(Example)
In this example, a nozzle plate having a primer layer and a liquid-repellent layer was manufactured. The primer layer and the liquid-repellent layer were formed by the following method.

A polyimide film was prepared as a nozzle plate substrate. The nozzle plate substrate was subjected to plasma treatment in a reduced pressure atmosphere containing an argon-oxygen mixed gas. As a result, a ring-opening reaction was caused by the polyimide on the surface of the substrate, and a hydroxyl group was imparted to this surface.

The primer solution was applied to the surface of the nozzle plate substrate by the blade coating method. As the primer agent, which is represented by the above general formula (1), R1 is a hydroxyl group, R2 is a hydroxyl group, and n is 10.
The coating was heated at 200 ° C. for 15 minutes. In this way, the primer agent was bonded to the polyimide and the coating film was dried. Further, the alkoxysilyl group of the primer agent was hydrolyzed to cause dehydration condensation of the silanol group between adjacent primer agent molecules. As a result, a monomolecular film made of a primer agent was formed as a primer layer.

Then, a solution of the linear fluorine compound was applied on the primer layer by the blade coating method. As the linear fluorine compound, a compound represented by the above general formula (2), in which R3 is a hydroxyl group and p is 1, was used.
The coating was heated at 200 ° C. for 15 minutes. In this way, the third reactive functional group of the linear fluorine compound was reacted with the second reactive functional group of the primer layer. As a result, a monomolecular film made of a fluorine compound was formed as a liquid-repellent layer.

(Comparative example)
A nozzle plate was manufactured by the same method as in the above example except that the primer layer was formed twice.

(Liquid repellent test)
Each of the nozzle plates according to Examples and Comparative Examples was cut to a width of 15 mm. Each of these samples was immersed in inkjet ink for a few seconds so that its main surface was parallel to the direction of gravity. Then, each sample was pulled up from the ink by a length of 45 mm, and the time required for the ink to run out from the pulled up portion was measured. As a result, in each sample, the ink disappeared from the pulled-up portion immediately after being pulled up from the ink. From this, both the nozzle plates according to the examples and the comparative examples were excellent in liquid repellency.

(Adhesion and scratch resistance test)
The nozzle plate according to the embodiment was rubbed 6000 times with a wiping blade. As a result, in the nozzle plate according to the example, the liquid-repellent layer did not peel off from the nozzle plate substrate even after being rubbed 6000 times. In addition, the nozzle plate after rubbing was excellent in liquid repellency. As described above, the nozzle plate according to the embodiment was excellent in adhesion between the liquid repellent layer and the nozzle plate substrate and scratch resistance.

When the nozzle plate according to the comparative example was rubbed with a wiping blade, the liquid-repellent layer was immediately peeled off from the nozzle plate substrate. As described above, the nozzle plate according to the comparative example did not have excellent adhesion between the liquid-repellent layer and the nozzle plate substrate, and therefore did not have excellent scratch resistance.

(XPS analysis)
XPS spectra were measured for each of the nozzle plates according to Examples and Comparative Examples. In addition to the above-mentioned measurement of the XPS spectrum, each of the nozzle plates according to Examples and Comparative Examples was etched, and the XPS spectrum was also measured for the nozzle plate obtained by etching. The XPS spectrum was also measured for the nozzle plate obtained by changing the etching time. The etching was performed so that the etching rate was 1.7 pm / sec.

6 and 7 are graphs showing XPS spectra obtained for the nozzle plates according to Examples and Comparative Examples, respectively. As shown in FIGS. 6 and 7, for example, when etched for 6000 seconds, the nozzle plate according to the embodiment has an energy within the range of binding energy of 680 to 690 eV as compared with the nozzle plate according to the comparative example. The peak value of intensity is smaller.
As described above, the difference between the structure of the nozzle plate according to the embodiment and the structure of the nozzle plate according to the comparative example appears in the XPS spectrum.

The present invention is not limited to the above embodiment, and can be variously modified at the implementation stage without departing from the gist thereof. Further, the embodiments may be carried out in combination as appropriate, and in that case, the combined effect can be obtained. Further, the above-described embodiment includes various inventions, and various inventions can be extracted by a combination selected from a plurality of disclosed constituent requirements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, if the problem can be solved and the effect is obtained, the configuration in which the constituent elements are deleted can be extracted as an invention.

1 ... inkjet head, 10 ... ink manifold, 11 ... ink supply tube, 12 ... ink return tube, 20 ... actuator board, 21 ... ink supply port, 22 ... ink discharge port, 30 ... actuator, 31 ... wiring pattern, 40 ... Frame, 50 ... Nozzle plate, N ... Nozzle, 51 ... Nozzle plate substrate, 52 ... Primer layer, 53 ... Liquid repellent layer, 60 ... Flexible printed substrate, 61 ... Drive circuit, 100 ... Inkjet printer, 1011 ... Cassette, 1012 ... Cassette, 102 ... Ink roller, 103 ... Ink roller, 104 ... Ink roller pair, 105 ... Ink roller pair, 106 ... Ink roller pair, 107 ... Ink belt, 108 ... Drive roller, 109 ... Driven roller, 111 ... Negative Pressure chamber, 112, transfer roller pair, 113 ... transfer roller pair, 114 ... transfer roller pair, 1151 ... inkjet head, 1152 ... inkjet head, 1153 ... inkjet head, 1154 ... inkjet head, 1161 ... ink cartridge, 1162 ... ink cartridge , 1163 ... ink cartridge, 1164 ... ink cartridge, 1171 ... tube, 1172 ... tube, 1173 ... tube, 1174 ... tube, 118 ... paper ejection tray, 119 ... fan, P ... recording medium, 110 ... medium holding mechanism, 120 ... Head movement mechanism, 130 ... blade movement mechanism, 140 ... wiping blade.

Claims (5)

It is equipped with a nozzle plate provided with a nozzle that ejects ink toward the recording medium.
The nozzle plate is
Nozzle plate board and
A primer layer provided on the surface of the nozzle plate substrate facing the recording medium and made of a monomolecular film of a primer agent containing silicon atoms and carbon atoms.
A liquid-repellent layer provided on the primer layer, having a perfluoroalkyl group as one terminal group on the surface side, and having the other terminal group bonded to the primer layer, which is a monomolecular film of a linear fluorine compound. Including inkjet head. The inkjet head according to claim 1, wherein the molecules of the primer agent are bound to each other. The inkjet head according to claim 1 or 2, wherein the nozzle plate substrate is made of polyimide. The inkjet head according to any one of claims 1 to 3 and the inkjet head.
An inkjet printer provided with a medium holding mechanism for holding the recording medium facing the inkjet head. The inkjet printer according to claim 4, further comprising a wiping blade that rubs the surface of the nozzle plate facing the recording medium to remove deposits from the surface of the nozzle plate facing the recording medium.

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