CN114516228A - Ink jet head, ink jet printer, and method of manufacturing ink jet head - Google Patents

Abstract

The invention provides an ink jet head with excellent liquid repellency, an ink jet printer and a manufacturing method of the ink jet head. The inkjet head includes a nozzle plate provided with nozzles for ejecting ink onto a recording medium. The nozzle plate includes a nozzle plate substrate, an undercoat layer formed of a monomolecular film of an undercoat agent containing a silicon atom and a carbon atom, provided on a surface of the nozzle plate substrate facing the recording medium, and a lyophobic layer provided on the undercoat layer and formed of a monomolecular film of a linear fluorine compound having a perfluoroalkyl group as one terminal group on a surface side thereof and a terminal group on the other side thereof bonded to the undercoat layer.

Description

Ink jet head, ink jet printer, and method of manufacturing ink jet head

Technical Field

Embodiments of the present invention relate to an inkjet head and an inkjet printer.

Background

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

The present invention addresses the problem of providing an ink jet head having excellent liquid repellency, and an ink jet printer including such an ink jet head.

Disclosure of Invention

An inkjet head according to an embodiment includes a nozzle plate provided with nozzles for ejecting ink onto a recording medium. The nozzle plate includes a nozzle plate substrate, an undercoat layer formed of a monomolecular film of an undercoat (primer) agent containing silicon atoms and carbon atoms, and a lyophobic layer formed of a monomolecular film of a linear fluorine compound having a perfluoroalkyl group as one terminal group on a surface side thereof and having the other terminal group bonded to the undercoat layer, the undercoat layer being provided on the undercoat layer.

Drawings

Fig. 1 is a perspective view illustrating an inkjet head according to an embodiment.

Fig. 2 is an exploded perspective view showing an actuator substrate, a frame, and a nozzle plate constituting an inkjet head according to an embodiment.

Fig. 3 is a schematic diagram illustrating an inkjet printer according to an embodiment.

Fig. 4 is a perspective view showing a main part of an inkjet printer according to an embodiment.

Fig. 5 is a sectional view schematically showing the structure of the nozzle plate according to the embodiment.

Fig. 6 is a graph showing an XPS spectrum obtained for the nozzle plate according to the example.

Fig. 7 is a graph showing XPS spectra obtained for the nozzle plate according to the comparative example.

[ notation ] to show

1. An ink jet head; 10. an ink manifold; 11. an ink supply tube; 12. an ink return tube; 20. an actuator substrate; 21. an ink supply port; 22. an ink discharge port; 30. an actuator; 31. a wiring pattern; 40. a frame; 50. a nozzle plate; n, a nozzle; 51. a nozzle plate substrate; 52. a primer layer; 53. draining the liquid layer; 60. a flexible printed substrate; 61. a drive circuit; 100. an ink jet printer; 1011. a cartridge; 1012. a cartridge; 102. a paper feed roller; 103. a paper feed roller; 104. a pair of conveying rollers; 105. a pair of conveying rollers; 106. a pair of registration rollers; 107. a conveyor belt; 108. a drive roller; 109. a driven roller; 111. a negative pressure chamber; 112, a first electrode; a pair of conveying rollers; 113. a pair of conveying rollers; 114. a pair of conveying rollers; 1151. an ink jet head; 1152. an ink jet head; 1153. an ink jet head; 1154. an ink jet head; 1161. an ink cartridge; 1162. an ink cartridge; 1163. an ink cartridge; 1164. an ink cartridge; 1171. a tube; 1172. a tube; 1173. a tube; 1174. a tube; 118. a paper discharge tray; 119. a fan; p, a recording medium; 110. a medium holding mechanism; 120. a head moving mechanism; 130. a scraper moving mechanism; 140. wiping the scraper.

Detailed Description

Hereinafter, embodiments will be described with reference to the drawings.

Fig. 1 is a perspective view showing an on-demand (on demand) type ink jet head 1 mounted on a head carriage of an ink jet printer according to an embodiment. In the following description, a rectangular coordinate system formed by an X axis, a Y axis, and a Z axis is used. For convenience, the direction indicated by an arrow in the figure is taken as the positive direction. The X-axis direction corresponds to the printing width direction. The Y-axis direction corresponds to a direction in which the recording medium is conveyed. The positive Z-axis direction is a direction opposite to the recording medium.

Referring to fig. 1, the inkjet head 1 includes an ink manifold 10, an actuator substrate 20, a frame 40, and a nozzle plate 50.

The actuator substrate 20 is rectangular with the X-axis direction as the longitudinal direction. Examples thereof include aluminum oxide (Al)₂O₃) Silicon nitride (Si)₃N₄) Silicon carbide (SiC), aluminum nitride (AlN), and lead zirconate titanate (PZT: pb (Zr, Ti) O₃) Etc. as the material of the actuator substrate 20.

To close the open end of the ink manifold 10, the actuator substrate 20 is overlapped over the ink manifold 10. The ink manifold 10 is connected to the ink cartridge via an ink supply tube 11 and an ink return tube 12.

A frame 40 is mounted on the actuator substrate 20. A nozzle plate 50 is attached to the frame 40. In the nozzle plate 50, a plurality of nozzles N are provided at predetermined intervals in the X-axis direction so as to be formed in 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. This ink jet head 1 is of a so-called side shooter type with a shear mode shared wall (share wall).

The plurality of ink supply ports 21 are provided on the actuator substrate 20 at intervals along the X-axis direction so as to form a row at the center portion in the Y-axis direction. The plurality of ink discharge ports 22 are provided on the actuator substrate 20 at intervals in the X-axis direction so as to form rows in the positive Y-axis direction and the negative Y-axis direction with respect to the rows of the ink supply ports 21.

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

Each of the columns formed by the plurality of actuators 30 is composed of a first piezoelectric body and a second piezoelectric body laminated on the actuator substrate 20. Examples thereof include lead zirconate titanate (PZT) and lithium niobate (LiNbO)₃) Lithium tantalate (LiTaO)₃) Etc. as the first and second piezoelectric materials. The first and second piezoelectric bodies are polarized in opposite directions in a thickness direction.

A plurality of grooves extending in the Y-axis direction and arranged in the X-axis direction are provided in a laminated body formed of the first and second piezoelectric bodies. The grooves are open on the second piezoelectric body side and have a depth greater than the thickness of the second piezoelectric body. The portion of the stacked body sandwiched between adjacent grooves is hereinafter referred to as a channel wall. These channel walls extend in the Y-axis direction and are aligned in the X-axis direction. The groove between two adjacent groove walls is an ink channel through which ink flows.

Electrodes are formed on the side walls and bottom of the ink channels. These electrodes are connected to a wiring pattern 31 extending in 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 with a flexible printed circuit board, which will be described later. The protective film includes, for example, a plurality of layers of inorganic insulating films and organic insulating films.

The frame 40 has an opening. The opening portion is smaller than the actuator substrate 20 and larger than the area of the actuator substrate 20 where the ink supply port 21, the actuator 30, and the ink discharge port 22 are provided. The frame 40 is formed of, for example, ceramic. The frame 40 is bonded to the actuator substrate 20, for example, by an adhesive.

The nozzle plate 50 includes a nozzle plate substrate, a primer layer provided on a medium-opposing surface thereof (an ejection surface from which ink is ejected from the nozzles N), and a lyophobic layer provided above the primer layer. The nozzle plate substrate is formed of a resin film such as a polyimide film. Details regarding the undercoat layer and the lyophobic layer will be described 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, by an adhesive.

A plurality of nozzles N are provided in the nozzle plate 50. The nozzles N are formed in two rows corresponding to the ink channels. The larger the diameter of the nozzle N as it goes from the recording medium side toward the ink channel side. The size of the nozzle N is set to a predetermined value according to the ink ejection amount. The nozzle N may 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 flow chamber. The ink was cycled as follows: the ink is supplied from the ink manifold 10 to the ink flow chamber through the ink supply port 21, and the excess ink is returned from the ink discharge port 22 to the ink manifold 10 through the ink channel. A part of the ink is ejected from the nozzle N while flowing through the ink channel and used for printing.

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

The operation of the actuator 30 will be described below. Here, the operation will be described focusing on the central ink channel among the adjacent three ink channels. The electrodes corresponding to the adjacent three ink channels are identified as A, B and C. When no electric field is applied in a direction perpendicular 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 electrodes A and C on both sides is applied to the central electrode B, and an electric field is generated in a direction perpendicular to the channel wall. In this way, the channel walls are driven in the shear mode, and the pair of channel walls sandwiching the center ink channel expands and deforms the volume of the center ink channel.

Then, a voltage pulse having a potential higher than that of the central electrode B is applied to the electrodes a and C on both sides, and an electric field is generated in a direction perpendicular to the channel wall. In this way, the channel walls are driven in the shear mode, and the pair of channel walls sandwiching the center ink channel is deformed by reducing the volume of the center ink channel. By this operation, pressure is applied to the ink in the center ink channel, and the ink is discharged from the nozzle N corresponding to the ink channel and landed on the recording medium.

For example, all the nozzles are divided into three groups, and the above-described driving operation is time-division controlled to perform three cycles, thereby performing printing on the 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 discharge tray 118. The casing is provided with cassettes 1011 and 1012, sheet feed rollers 102 and 103, conveying roller pairs 104 and 105, registration roller pair 106, conveying belt 107, fan 119, negative pressure chamber 111, conveying roller pairs 112, 113 and 114, inkjet heads 1151, 1152, 1153 and 1154, ink cassettes 1161, 1162, 1163 and 1164, and tubes 1171, 1172, 1173 and 1174.

The cartridges 1011 and 1012 house recording media P of 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 conveying roller pairs 104 and 105 and the registration roller pair 106.

The conveying belt 107 is given tension by a driving roller 108 and two driven rollers 109. Holes are provided at predetermined intervals on the surface of the conveying belt 107. A negative pressure chamber 111 connected to a fan 119 is provided inside the transport belt 107 to suck the recording medium P to the transport belt 107. A pair of conveying rollers 112, 113, and 114 are provided downstream in the conveying direction of the conveying belt 107. In the transport path from the transport belt 107 to the paper discharge tray 118, a heater for heating the printed layer formed on the recording medium P may be provided.

Four inkjet heads that eject ink onto the recording medium P in accordance with image data are arranged above the conveyor belt 107. 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 an inkjet head 1154 that ejects black (Bk) ink are arranged in this order from the upstream side. The inkjet heads 1151, 1152, 1153 and 1154 are the inkjet heads 1 described with reference to fig. 1 and 2.

Above the inkjet heads 1151, 1152, 1153, and 1154, there are provided a cyan (C) ink cartridge 1161, a magenta (M) ink cartridge 1162, a yellow (Y) ink cartridge 1163, and a black (Bk) ink cartridge 1164 that respectively store inks corresponding thereto. These ink cartridges 1161, 1162, 1163, and 1164 are connected to inkjet heads 1151, 1152, 1153, and 1154 through pipes 1171, 1172, 1173, and 1174, respectively.

Next, an image forming operation of the inkjet printer 100 will be described.

First, an image processing apparatus (not shown) starts image processing for recording, generates an image signal corresponding to image data, and generates a control signal for controlling operations of various rollers, the negative pressure chamber 111, and the like.

The paper feed roller 102 or 103 takes out the recording medium P of a selected size one by one from the cassette 1011 or 1012 under the control of the image processing apparatus, and conveys it to the conveying roller pair 104 and 105 and the registration roller pair 106. The registration 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 holes of the conveyor belt 107. Therefore, the recording medium P is conveyed to a position below the inkjet heads 1151, 1152, 1153, and 1154 in sequence as the conveying belt 107 moves while being attracted to the conveying 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 apparatus. Thereby, a color image can be formed at a desired position of the recording medium P.

After that, the conveying roller pairs 112, 113, and 114 discharge the recording medium P on which the image is formed to the discharge tray 118. When a heater is provided in the transport path from the transport belt 107 to the paper discharge tray 118, the print layer formed on the recording medium P may be heated by the heater. When the recording medium P is heated by the heater, the adhesion of the printing layer to the recording medium P can be improved particularly when the recording medium P is non-permeable.

Fig. 4 shows a perspective view of a main part of the inkjet printer 100. 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 are drawn in fig. 4.

The medium holding mechanism 110 holds the recording medium P, for example, a recording sheet, facing the inkjet head 1. The medium holding mechanism 110 functions as a recording sheet moving mechanism for moving the recording medium. The medium holding mechanism 110 includes the conveying belt 107, the driving roller 108, the driven roller 109, the negative pressure chamber 111, and the fan 119 of fig. 3. The medium holding mechanism 110 moves the recording medium P in a direction parallel to the printing surface of the recording medium P in a state where the recording medium P faces the inkjet head 1 during printing. During this time, 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. In addition, the head moving mechanism 120 moves the inkjet head 1 to the cleaning position at the time of cleaning.

The wiping blade 140 wipes the surface of the ink jet head 1 where the nozzle plate opposes the recording medium, that is, the recording medium-opposing surface, and removes the attached matter from the recording medium-opposing surface. Here, the attached matter refers to, for example, ink, dust, and other waste.

The blade moving mechanism 130 moves the wiping blade 140. Specifically, after the head moving mechanism 120 moves the inkjet head 1 to the cleaning position, the blade moving mechanism 130 presses and moves the wiping blade 140 to and on the recording medium-facing surface of the nozzle plate 50. This removes the adhering matter such as ink adhering to the recording medium-facing surface of the nozzle plate 50.

The wiping blade 140 and the blade moving mechanism 130 may be omitted.

In the above-described ink jet head 1, liquid repellency is imparted to the medium-facing surface of the nozzle plate 50. In order to impart liquid repellency, an undercoat layer and a liquid repellent layer are provided on the medium-facing surface of the nozzle plate substrate. This is explained with reference to fig. 5.

Fig. 5 is a sectional view schematically showing the structure of the nozzle plate 50 of fig. 1 and 2. The nozzle plate 50 includes the nozzle plate substrate 51, the undercoat layer 52, and the lyophobic layer 53, as described above.

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

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

The first reactive functional group causes the primer to bond to the nozzle plate substrate 51 by reacting with a functional group present on the surface of the nozzle plate substrate 51. The first reactive functional group is an unsaturated hydrocarbon group such as a hydroxyl group, an epoxy group, an amino group, a methacrylic group, 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 reacts with the linear fluorine compound used for forming the lyophobic layer 53, thereby bonding the linear fluorine compound to the primer. The straight chain fluorine compound will be described later. The second reactive functional group is an alkoxy group such as a hydroxyl group, or a methoxy group, or an ethoxy group.

The carbon backbone links the first reactive functional group to the second reactive functional group. The carbon skeleton contains more than one carbon atom. The number of carbon atoms of the carbon skeleton is more preferably in the range of 4 to 30, and still 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 fluorine atoms, the liquid repellency is excellent.

The alkoxysilyl group is linked to the carbon backbone. The alkoxysilyl group is hydrolyzed to form a silanol group. Intermolecular bonds can be formed in the primer by dehydration condensation of silanol groups between molecules of the primers adjacent to each other on the nozzle plate substrate 51. Thus, it is more preferable that the molecules of the primer are bonded to each other. According to one example, adjacent primer molecules on the nozzle plate substrate 51 are bonded to each other by siloxane bonds (Si-O-Si). Thus, the primer forms a bond substantially parallel to the medium-facing surface of the nozzle plate substrate 51.

Among the silanol groups formed by hydrolysis, the silanol groups that are not used for intermolecular bonds of the primer can be used for bonding the primer to the linear fluorine compound.

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

[ chemical formula 1 ]

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 first and second reactive functional groups, a carbon skeleton, and an alkoxysilyl group.

In the general formula (1), the alkoxysilyl group may be a functional group such as a trimethoxysilyl group or a triethoxysilyl group. In the general formula (1), CF is contained in the carbon skeleton₂The number of radicals being 2, but CF₂The number of the groups may be 1 or 3 or more. The number of carbon atoms included in the repeating unit in the carbon skeleton may be 2, 1, or 3 or more.

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

The lyophobic layer 53 is provided on the undercoat layer 52. The lyophobic layer 53 is formed 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 undercoat layer 52.

The lyophobic layer 53 can be formed using, for example, 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 may be selected within a range of 4 or less (C1 to C4). The perfluoroalkyl group is preferably vertical to the surface of the nozzle plate substrate 51. When the number of carbon atoms of the perfluoroalkyl group is increased, the perfluoroalkyl group tends to stand upright, but the carbon atoms have an adverse effect on the human body such as carcinogenicity.

The third reactive functional group reacts with the second reactive functional group to bond the linear fluorine compound to the primer. The third reactive functional group is an alkoxy group such as a hydroxyl group, or a methoxy group, or an ethoxy group.

The linear fluorine compound may be bonded to the primer by reacting a silanol group, which is not used for an intermolecular bond, among silanol groups generated by hydrolysis of the alkoxysilyl group with the third reactive functional group.

The linear fluorine compound has, for example, a spacer linking group linking the perfluoroalkyl group and the third reactive functional group. If the spacer linking group is present, the perfluoroalkyl group advantageously stands in the perpendicular direction with respect to the surface of the nozzle plate substrate 51. The spacer linkage 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.

[ chemical formula 2 ]

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

When a monomolecular film is formed using the linear fluorine compound, the lyophobic layer 53 having a thickness of usually 9nm to 10nm can be obtained.

The nozzle plate 50 shown in fig. 5 can be obtained, for example, as follows. Here, the nozzle plate substrate 51 is made of polyimide, and the primer contains an alkoxysilyl group.

First, a nozzle plate substrate 51 made of polyimide is prepared. The surface of the nozzle plate substrate 51 facing the recording medium P may have almost no functional group, such as a hydroxyl group, necessary for bonding to the primer. In that case, the nozzle plate substrate 51 is preferably subjected to the following pretreatment before the formation of the undercoat layer 52.

For example, ion plasma treatment is applied to the surface of the nozzle plate substrate 51 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 placed in a vacuum chamber, and the air in the chamber is evacuated. Then, the atmosphere around 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 oxygen-containing atmosphere, a ring-opening reaction of polyimide on the surface of the nozzle plate substrate 51 occurs, and the surface is modified with hydroxyl groups. In addition, by performing ion plasma treatment in an argon-containing atmosphere, dust adhering to the nozzle plate substrate 51 is removed.

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 in an argon-oxygen mixed gas having an oxygen concentration in the range of 20 to 50% by volume. When the oxygen concentration is too high, the surface of the nozzle plate substrate 51 may be damaged and roughened. In the case where the surface of the nozzle plate substrate 51 is roughened, the bonding with the primer may be insufficient.

The ion plasma treatment is preferably performed for 100 seconds or more, and more preferably performed for 200 seconds or more. 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 an undercoat 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 with an organic solvent can be used. The solution can be applied by a common method such as a spray coating method, a spin coating method, or a blade coating method.

Next, the laminate including the nozzle plate substrate 51 and the coating film containing the primer is heated. In so doing, the primer binds to the polyimide and the coating film is dried. The heating is carried out, for example, at 200 ℃ for 15 minutes.

Next, the alkoxysilyl group of the primer is hydrolyzed. If the alkoxysilyl group of the primer is hydrolyzed, a silanol group is formed. Then, dehydration condensation of silanol groups occurs between molecules of the primers adjacent to each other on the nozzle plate substrate 51. Thereby, intermolecular bonds of the primer are formed.

In this manner, 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 undercoat layer 52 to form a lyophobic layer 53. For example, a solution in which a linear fluorine compound is dissolved in an organic solvent can be used as the solution containing the linear fluorine compound. In addition, the solution can be applied using the above-described method with respect to the solution containing the primer.

Next, a laminate including a coating film containing a linear fluorine compound, the undercoat layer 52, and the nozzle plate substrate 51 is heated. In this way, the linear fluorine compound is reacted with the primer, and the linear fluorine compound is bonded to the surface of the primer layer 52. Thereby, a monomolecular film formed of a linear fluorine compound was formed as the lyophobic layer 53. The heating is carried out, for example, at 200 ℃ for 15 minutes.

Operating in the above manner, the nozzle plate 50 shown in fig. 5 can be obtained.

The nozzle plate 50 is excellent in liquid repellency. Therefore, the ink jet head 1 including the nozzle plate 50 is excellent in liquid repellency.

For example, a nozzle plate having a structure similar to the nozzle plate 50 can be obtained by omitting the undercoat layer and forming a lyophobic layer on the nozzle plate substrate using a material having the structure described above with respect to the undercoat layer and the structure described above with respect to the linear fluorine compound in one molecule.

However, the molecules used for the formation of such a lyophobic layer are long because they have the above structure with respect to the primer and the above structure with respect to the linear fluorine compound in one molecule. Therefore, it is difficult to arrange these molecules on the nozzle plate substrate densely and orderly.

On the other hand, the molecular length of the primer used for the production of the nozzle plate 50 is short. Therefore, these primer molecules are easily arranged densely and orderly on the nozzle plate substrate 51. Further, the molecular length of the linear fluorine compound used for producing the nozzle plate 50 is also short. Therefore, these linear fluorine compound molecules are also easily arranged densely and orderly on the undercoat layer 52. Therefore, the nozzle plate 50 having the two-layer structure of the undercoat layer 52 and the lyophobic layer 53 on the nozzle plate substrate 51 achieves more excellent lyophobicity than the nozzle plate without the undercoat layer.

In addition, since the nozzle plate 50 has a two-layer structure of the undercoat layer 52 and the lyophobic layer 53 on the nozzle plate substrate 51, the number of moles of the undercoat agent does not necessarily match the number of moles of the linear fluorine compound. Therefore, for example, the number of moles of the linear fluorine compound contained in the lyophobic layer 53 can be made larger than the number of moles of the primer contained in the primer layer 52. Specifically, the second reactive functional group and the silanol group not used for intermolecular bond may be bonded to each molecule of another linear fluorine compound, and the number of moles of the linear fluorine compound included in the lyophobic layer 53 may be larger than the number of moles of the primer included in the primer layer 52. As described above, the nozzle plate 50 can easily achieve desired liquid repellency.

The nozzle plate 50 includes an undercoat layer 52 formed of a monomolecular film. Such a nozzle plate 50 is superior in adhesion and scratch resistance between the lyophobic layer and the nozzle plate substrate, compared to a nozzle plate in which the undercoat layer is formed of a laminate of a plurality of monomolecular films. The scratch resistance refers to a property that deterioration of liquid repellency due to scratching with the wiping blade 140 or the like is less likely to occur.

Whether or not primer layer 52 is formed of a monomolecular film can be determined by X-ray photoelectron spectroscopy (XPS). The determination can be performed, for example, by subjecting the nozzle plate 50 including the lyophobic layer 53, the undercoat layer 52, and the nozzle plate substrate 51 to X-ray photoelectron spectroscopy (XPS) spectrum detection of the nozzle plate 50 etched from the surface of the lyophobic layer 53.

[ examples ]

Hereinafter, examples and comparative examples will be described.

(examples)

In this example, a nozzle plate having an undercoat layer and a lyophobic layer was manufactured. The undercoat layer and the lyophobic layer are formed by the following method.

A polyimide film was prepared as a nozzle plate substrate. Plasma treatment is applied to the nozzle plate substrate in a reduced-pressure atmosphere containing an argon-oxygen mixed gas. This causes a ring-opening reaction of the polyimide on the substrate surface, thereby imparting a hydroxyl group to the surface.

A solution of the primer is applied to the above-mentioned surface of the nozzle plate substrate by a blade coating method. A compound represented by the above general formula (1), wherein R1 is a hydroxyl group, R2 is a hydroxyl group, and n is 10, is used as a primer.

The coating film was heated at 200 ℃ for 15 minutes. In this way, the primer is combined with the polyimide and the coating film is dried. Further, the alkoxysilyl group of the primer is hydrolyzed, and dehydration condensation of silanol groups occurs between adjacent primer molecules. Thus, a monomolecular film formed of the primer was formed as the primer layer.

Then, a solution of a linear fluorine compound was applied to the undercoat layer by a doctor blade method. The linear fluorine compound represented by the general formula (2) is a compound wherein R3 represents a hydroxyl group and p represents 1.

The coating film was heated at 200 ℃ for 15 minutes. In this way, the third reactive functional group of the linear fluorine compound reacts with the second reactive functional group of the undercoat layer. Thereby, a monomolecular film formed of a fluorine compound is formed as a lyophobic layer.

Comparative example

A nozzle plate was produced in the same manner as in the above example, except that the formation of the undercoat layer was performed twice.

(lyophobicity test)

The nozzle plates according to examples and comparative examples were each cut to a width of 15 mm. These samples were immersed in the inkjet ink for several seconds with their main surfaces parallel to the direction of gravity. Then, each sample was pulled out from the ink only by a length of 45mm, and the time required until the ink of the pulled-out portion disappeared was measured. As a result, the ink disappeared from the pulled-out portion immediately after any sample was pulled out from the ink. From this, it is understood that the nozzle plates according to the examples and comparative examples are excellent in liquid repellency.

(test of adhesion and scratch resistance)

The example relates to a nozzle plate that was wiped 6000 times by a wiping blade. As a result, the lyophobic layer was not peeled off from the nozzle plate substrate even after the nozzle plate according to the example was wiped 6000 times. Further, the nozzle plate after wiping is excellent in liquid repellency. As described above, the lyophobic layer of the nozzle plate according to the example is excellent in adhesion to the nozzle plate substrate and scratch resistance.

When the nozzle plate according to the comparative example was wiped with the wiping blade, the lyophobic layer was immediately peeled off from the nozzle plate substrate. As described above, the nozzle plate according to the comparative example was not excellent in adhesion between the lyophobic layer and the nozzle plate substrate, and also was not excellent in scratch resistance.

(XPS analysis)

XPS spectra were measured for each of the nozzle plates according to examples and comparative examples. In addition to the measurement of the XPS spectrum described above, the XPS spectrum was measured for each nozzle plate according to the etching examples and comparative examples, and 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 at an etching rate of 1.7 pm/sec.

Fig. 6 and 7 are graphs showing XPS spectra obtained for nozzle plates according to examples and comparative examples, respectively. As shown in fig. 6 and 7, for example, in the case of 6000 seconds of etching, the nozzle plate according to the example has a smaller peak of energy intensity in the binding energy range of 680 to 690eV than the nozzle plate according to the comparative example.

As such, the difference between the structure of the nozzle plate according to the example and the structure of the nozzle plate according to the comparative example can be expressed in the XPS spectrum.

The present invention is not limited to the above embodiment, and various modifications can be made in the implementation stage without departing from the scope of the present invention. In addition, the embodiments can be combined and implemented as appropriate, and in this case, a combined effect can be obtained. Further, the above-described embodiments include a plurality of inventions, and a plurality of inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some of all the constituent elements described in the embodiments are deleted, if the problem can be solved and the effect can be obtained, the configuration in which the constituent elements are deleted can be extracted as an invention.

Claims (10)

1. An ink jet head is characterized in that,

comprises a nozzle plate provided with nozzles for ejecting ink onto a recording medium,

the nozzle plate comprises a nozzle plate substrate, a bottom coating and a lyophobic layer,

the undercoat layer is provided on a surface of the nozzle plate substrate facing the recording medium, the undercoat layer is formed of a monomolecular film of an undercoat agent containing silicon atoms and carbon atoms,

the lyophobic layer is provided on the undercoat layer, and is formed from a monomolecular film of a linear fluorine compound having a perfluoroalkyl group on the surface side as one terminal group, and the other terminal group bonded to the undercoat layer.

2. An ink jet head according to claim 1,

the molecules of the primer bind to each other.

3. An ink jet head according to claim 1 or 2,

the nozzle plate substrate is formed of polyimide.

4. An ink jet head according to claim 1 or 2,

the lyophobic layer contains the linear fluorine compound in a larger number of moles than the primer in a larger number of moles.

5. An inkjet printer, comprising:

an ink jet head according to any one of claims 1 to 4; and

a medium holding mechanism that holds the recording medium opposite to the inkjet head.

6. The inkjet printer of claim 5,

the inkjet recording apparatus further includes a wiping blade that wipes a surface of the nozzle plate facing the recording medium to remove an attached matter from the surface of the nozzle plate facing the recording medium.

7. A method of manufacturing an ink jet head,

the inkjet head includes a nozzle plate provided with nozzles for ejecting ink onto a recording medium, and the method of manufacturing the inkjet head includes:

preparing a base plate of the nozzle plate,

applying a primer to a surface of the nozzle plate substrate facing the recording medium so as to form a monomolecular film of the primer, thereby forming an undercoat layer formed of the primer containing silicon atoms and carbon atoms,

the method for producing a liquid repellent layer includes applying a solution of a linear fluorine compound on the undercoat layer so as to form a monomolecular film of the linear fluorine compound, and forming a liquid repellent layer of the linear fluorine compound having a perfluoroalkyl group on a surface side thereof as one terminal group and having the other terminal group bonded to the undercoat layer.

8. A method of manufacturing an ink jet head according to claim 7,

the molecules of the primer bind to each other.

9. A method of manufacturing an ink jet head according to claim 7 or 8,

the nozzle plate substrate is formed of polyimide.

10. A method of manufacturing an ink jet head according to claim 7 or 8,

the lyophobic layer contains the linear fluorine compound in a larger number of moles than the primer in a larger number of moles.

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