Patent Description:
Generally, a liquid jetting head represented by an ink jet head mounted on an ink jet recording device has a nozzle for jetting a liquid. The liquid is supplied from a liquid supply chamber to a liquid flow passage and is jetted from a nozzle hole formed in the nozzle connected to the liquid flow passage.

For example, <CIT> discloses a liquid droplet jetting head comprising a nozzle substrate comprising a plurality of nozzle holes comprising at least a nozzle portion that jets liquid droplets and an introduction portion having a larger cross-sectional area than the nozzle portion and provided coaxially with the nozzle portion, in which the nozzle substrate has a plurality of layers of jetting liquid-resistant protective films formed at least on an inner wall of the nozzle holes. In addition, <CIT> discloses a liquid droplet ejection head comprising a nozzle plate in which a plurality of nozzle openings are provided on a silicon substrate, a hafnium oxide film or a zirconium oxide film formed by atomic layer deposition is provided on both surfaces of the silicon substrate and a nozzle opening inner surface, and a plasma polymerization film of a silicone material is provided on the hafnium oxide film or the zirconium oxide film on a jetting surface. In addition, <CIT> discloses a liquid jetting head that includes a nozzle plate formed with nozzle holes for jetting liquid droplets and jets a liquid from the nozzle holes by pressurizing the liquid in a liquid chamber communicating with the nozzle holes, in which titanium or a titanium oxide film is formed on a jetting side on a surface of the nozzle plate, a silicon oxide film is formed on the titanium or titanium oxide film, a water-repellent layer is formed on the silicon oxide film, a silicon oxide film is formed on a liquid chamber side and an inner wall of the nozzle hole on the surface of the nozzle plate, the titanium or titanium oxide film is covered with a silicon oxide film, an interface between the silicon oxide film and the titanium or titanium oxide film is not exposed on a liquid contact surface.

A component contained in a liquid adhere to a jetting surface of a liquid jetting head as foreign matter because of drying after the liquid is jetted. In a case where foreign matter adheres to a nozzle surface, jetting failure is likely to occur. Therefore, in a liquid jetting device, foreign matter can be removed by periodically wiping the jetting surface of the liquid jetting head. However, durability of the jetting surface of the liquid jetting head may decrease by wiping, and durability against wiping (hereinafter, also referred to as "wipe resistance") is required.

In a case where an alkaline liquid is used, durability of the jetting surface of the liquid jetting head and a liquid flow passage may decrease, and durability against alkali (hereinafter, also referred to as "alkali resistance") is required.

On the other hand, in <CIT>, a silicon oxide film, a metal oxide film, and a water-repellent film are provided in this order on the jetting surface. Since adhesiveness between the water-repellent film and the metal oxide film is insufficient, the jetting surface is considered to be inferior in wipe resistance.

In <CIT>, a hafnium oxide film or a zirconium oxide film, a plasma polymerization film of a silicone material, and a liquid-repellent film are provided in this order on the jetting surface. The plasma polymerization film has few bonding points and many pinholes. Therefore, adhesiveness between the liquid-repellent film and the plasma polymerization film is insufficient, and the jetting surface is considered to be inferior in wipe resistance.

In <CIT>, titanium or a titanium oxide film and a silicon oxide film are provided in this order on a part of the inner wall of the nozzle hole. However, only the silicon oxide film is provided on the liquid chamber side on the surface of the nozzle plate, and it is considered to be inferior in alkali resistance.

The present disclosure has been made in view of such circumstances, and an object to be achieved by an embodiment of the present invention is to provide a liquid jetting structure, a liquid jetting head, and a liquid jetting device, in which a jetting surface is excellent in wipe resistance and the jetting surface and a liquid flow passage are excellent in alkali resistance.

<CIT> is also relevant to the invention. The invention is directed to a liquid jetting structure according to claim <NUM>.

According to the present disclosure, there are provided a liquid jetting structure, a liquid jetting head, and a liquid jetting device, in which a jetting surface is excellent in wipe resistance and the jetting surface and an internal flow passage are excellent in alkali resistance.

Hereinafter, a liquid jetting structure, a liquid jetting head, and a liquid jetting device of the present disclosure will be described in detail.

In the present disclosure, a numerical range shown using "to" indicates a range including the numerical values described before and after "to" as a lower limit value and an upper limit value.

In the present disclosure, in a case where a plurality of substances corresponding to respective components in a composition are present, the amount of the respective components in the composition indicates the total amount of the plurality of substances present in the composition unless otherwise specified.

In a numerical range described in a stepwise manner in the present disclosure, an upper limit value or a lower limit value described in a certain numerical range may be replaced with an upper limit value or a lower limit value in another numerical range described in a stepwise manner or a value described in an example.

In the present disclosure, the term "step" denotes not only an individual step but also a step which is not clearly distinguishable from another step as long as an effect expected from the step can be achieved.

In the present disclosure, a combination of preferred aspects is a more preferred embodiment.

Each element in each of the drawings shown in the present disclosure is not necessarily to an exact scale, with a focus on clearly showing the principles of the present disclosure and some emphasis.

In the present disclosure, the term "liquid-repellent layer" refers to a layer having a contact angle with water of <NUM>° or more. The contact angle with water is a value measured under the condition of <NUM> by using a contact angle meter, for example, a fully automatic contact angle meter (product name "DM-<NUM>", manufactured by Kyowa Interface Science Co.

In the present disclosure, the term "internal flow passage" means a path through which a liquid passes, which is formed inside the liquid jetting structure. That is, the term "internal flow passage" is a concept including a nozzle formed on a nozzle substrate and a liquid flow passage formed on a flow passage substrate.

In the present disclosure, the term "jetting surface" means a surface of the nozzle substrate on a side where the liquid is jetted in the liquid jetting structure.

In the present disclosure, the term "inner wall of the liquid flow passage" means a surface of the flow passage substrate on a side where the liquid flow passage is formed. In addition, the "inner wall of the nozzle" means a surface of the nozzle substrate on a side where the nozzle is formed.

A liquid jetting structure of the present disclosure comprises a nozzle substrate on which a nozzle for jetting a liquid is formed; and a flow passage substrate on which a liquid flow passage communicating with the nozzle is formed. A first layer, a second layer, and a liquid-repellent layer are provided in this order on a jetting surface of the nozzle substrate, and the first layer and the second layer are provided in this order on an inner wall of the liquid flow passage. The first layer is a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide. The second layer is a layer containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON.

Providing the first layer, the second layer, and the liquid-repellent layer in this order on the jetting surface of the nozzle substrate means that the liquid-repellent layer is located on an outermost surface of the nozzle substrate. That is, the liquid-repellent layer is the outermost layer among a plurality of layers provided on the nozzle substrate. Since the liquid jetting structure of the present disclosure has the liquid-repellent layer on the outermost surface of the nozzle substrate, the liquid jetting structure is excellent in antifouling property on the jetting surface.

The liquid jetting structure of the present disclosure has a second layer which is a layer containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON under the liquid-repellent layer which is the outermost layer in the nozzle substrate. A layer containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON has high adhesiveness to the liquid-repellent layer and excellent wipe resistance of the jetting surface.

The liquid jetting structure of the present disclosure has a first layer which is a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide under the second layer in the nozzle substrate, the nozzle, and the liquid flow passage. At least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide is excellent in alkali resistance. Therefore, in a case where an alkaline liquid permeates into the second layer due to a long period of use, the presence of the first layer makes it possible to maintain the alkali resistance of the jetting surface and the internal flow passage.

Hereinafter, an embodiment of the liquid jetting structure of the present disclosure will be described with reference to the drawings.

<FIG> is a cross-sectional view showing an embodiment of the liquid jetting structure of the present disclosure.

As shown in <FIG>, a liquid jetting structure <NUM> comprises a nozzle substrate <NUM> on which a nozzle <NUM> for jetting a liquid is formed, and a flow passage substrate <NUM> on which a liquid flow passage <NUM> communicating with the nozzle <NUM> is formed. It is preferable that the nozzle substrate <NUM> and the flow passage substrate <NUM> are bonded by adhesion or the like.

A type of the liquid supplied to the liquid jetting structure <NUM> is not particularly limited. The liquid jetting structure <NUM> is used for a liquid jetting head described below, and by incorporating the liquid jetting head into a liquid jetting device described below, fine liquid droplets can be jetted from the nozzle <NUM>. It is preferable to use ink as a liquid, and an image can be recorded by jetting fine ink droplets onto the substrate.

The ink for recording an image is, for example, a liquid containing a coloring material, a solvent, and a surfactant. In addition, a pretreatment liquid may be jetted onto the substrate in advance before the ink is jetted onto the substrate, or a posttreatment liquid may be jetted after the ink is jetted. Therefore, examples of the liquid supplied to the liquid jetting structure <NUM> include a pretreatment liquid and a posttreatment liquid in addition to the ink. The pretreatment liquid and the posttreatment liquid are usually colorless liquids containing no coloring material.

In addition, the liquid supplied to the liquid jetting structure <NUM> may be an acidic liquid or an alkaline liquid. The liquid jetting structure <NUM> is suitable for an alkaline liquid because the jetting surface and the inside of the flow passage are excellent in alkali resistance. In particular, the liquid jetting structure <NUM> is suitable for a liquid having a pH of <NUM> to <NUM>. The pH is a value measured at <NUM> using a pH meter, for example, a value measured using a product name "handy pH meter" manufactured by Sato Keiryoki Mfg.

The nozzle substrate <NUM> is, for example, a substrate made of silicon, and may be a single crystal silicon substrate or a polycrystal silicon substrate. The nozzle <NUM> for jetting a liquid is formed on the nozzle substrate <NUM>.

The nozzle <NUM> is a hole penetrating the nozzle substrate <NUM>, and is formed by, for example, dry etching. It is preferable that a plurality of the nozzles <NUM> are formed on the nozzle substrate <NUM>. A shape of the nozzle <NUM> is not particularly limited, but from the viewpoint of controlling a jetting direction of the liquid, it is preferable that the nozzle <NUM> has a tapered shape whose diameter decreases toward the jetting direction of the liquid. A hole diameter on a side where the liquid of the nozzle <NUM> is jetted, that is, a hole diameter of a nozzle opening <NUM> can be appropriately adjusted. In a case where the liquid jetting structure <NUM> is used for the inkjet head, the hole diameter of the nozzle opening <NUM> is, for example, <NUM> to <NUM>.

A thickness of the nozzle substrate <NUM> corresponds to a length of the nozzle <NUM>, and is preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>.

<FIG> is an enlarged view of a broken line frame A in <FIG>.

As shown in <FIG>, a first layer <NUM>, a second layer <NUM>, and a liquid-repellent layer <NUM> are provided in this order on a jetting surface <NUM> of the nozzle substrate <NUM>.

The first layer <NUM> is a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, and is preferably a layer of tantalum oxide, zirconium oxide, or hafnium oxide.

At least one (preferably tantalum oxide, zirconium oxide, or hafnium oxide) selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide is excellent in alkali resistance. Therefore, in a case where an alkaline liquid permeates into the liquid-repellent layer and the second layer provided on the jetting surface of the nozzle substrate due to a long period of use, the presence of the first layer makes it possible to maintain the alkali resistance of the jetting surface.

A thickness of the first layer <NUM> is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, and still more preferably <NUM> to <NUM>. In a case where the thickness of the first layer <NUM> is <NUM> or more, the alkaline liquid is less likely to permeate into the first layer <NUM>, and the wipe resistance and the alkali resistance of the jetting surface are excellent. On the other hand, in a case where the thickness of the first layer <NUM> is <NUM> or less, defects are less likely to occur in the layer, and the wipe resistance and the alkali resistance of the jetting surface are excellent. From the viewpoint of productivity, the thickness of the first layer <NUM> is preferably <NUM> or less.

The second layer <NUM> is a layer containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON, and is preferably a SiO<NUM> layer. A layer (preferably SiO<NUM> layer) containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON has high adhesiveness to the liquid-repellent layer <NUM>. Therefore, the alkaline liquid is less likely to permeate into the liquid-repellent layer <NUM> and the second layer <NUM>, and the wipe resistance and the alkali resistance of the jetting surface are excellent.

A thickness of the second layer <NUM> is <NUM> to <NUM> or <NUM> to <NUM>, still more preferably <NUM> to <NUM>, and still more preferably <NUM> to <NUM>. In particular, in a case where the thickness of the second layer <NUM> is <NUM> to <NUM> or <NUM> to <NUM>, the adhesiveness between the second layer <NUM> and the liquid-repellent layer <NUM> is enhanced, and the wipe resistance and the alkali resistance of the jetting surface are excellent.

A ratio of the thickness of the second layer <NUM> to the thickness of the first layer <NUM> is preferably <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, still more preferably <NUM> or more and <NUM> or less, and still more preferably <NUM> or more and <NUM> or less. In particular, in a case where the ratio of the thickness of the second layer <NUM> to the thickness of the first layer <NUM> is <NUM> or more and <NUM> or less, the alkaline liquid is less likely to permeate into the first layer <NUM>, and the wipe resistance and the alkali resistance of the jetting surface are excellent. In addition, in a case where the ratio of the thickness of the second layer <NUM> to the thickness of the first layer <NUM> is <NUM> or more and <NUM> or less, the adhesiveness between the first layer <NUM> and the second layer <NUM> is high, and the wipe resistance and the alkali resistance of the jetting surface are excellent.

The liquid-repellent layer <NUM> is a layer having a contact angle with water of <NUM>° or more. The contact angle of the liquid-repellent layer <NUM> with water is preferably <NUM>° or more, and more preferably <NUM>° or more. Since the liquid-repellent layer <NUM> is provided on the outermost surface of the nozzle substrate <NUM>, the wipe resistance of the jetting surface is excellent.

From the viewpoint of exhibiting liquid repellency, the liquid-repellent layer <NUM> preferably contains a fluorine-containing compound, and more preferably contains a compound having a perfluoropolyether structure. A compound having a perfluoropolyether structure has a highly flexible and dense molecular structure. Therefore, it is possible to suppress the permeation of the alkaline liquid into the inside of the liquid-repellent layer <NUM>, and the alkali resistance is excellent. Since the perfluoropolyether structure has a high fluorine content, fluorine atoms are likely to remain on a surface of the liquid-repellent layer <NUM> even after wiping, and the contact angle is less likely to decrease. That is, the wipe resistance of the jetting surface is excellent.

From the viewpoint of adhesiveness to the second layer <NUM> which is a layer containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON, the liquid-repellent layer <NUM> is preferably formed using silicon coupling agent, and more preferably formed using a silicon coupling agent having a perfluoropolyether structure. That is, the liquid-repellent layer <NUM> is still more preferably a silicon compound having a perfluoropolyether structure.

Examples of the perfluoropolyether structure include structures represented by Formulas <NUM> to <NUM>. Among these, the perfluoropolyether structure is preferably a structure represented by Formula <NUM>.

CF<NUM>O-(CF<NUM>O)n-(CF<NUM>CF<NUM>O)m-*.

In Formula <NUM>, m represents an integer of <NUM> to <NUM>, n represents an integer of <NUM> to <NUM>, and m + n is <NUM> or more. * indicates a bonding position to other structures in the compound.

In Formula <NUM>, m represents preferably an integer of <NUM> to <NUM> and more preferably an integer of <NUM> to <NUM>. n represents preferably an integer of <NUM> to <NUM> and more preferably an integer of <NUM> to <NUM>.

CF<NUM>-(CF<NUM>OCF<NUM>O)n-*.

In Formula <NUM>, n represents an integer of <NUM> to <NUM>. * indicates a bonding position to other structures in the compound.

A thickness of the liquid-repellent layer <NUM> is preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>. In a case where the thickness of the liquid-repellent layer <NUM> is <NUM> or more, the wipe resistance is improved. On the other hand, in a case where the thickness of the liquid-repellent layer <NUM> is <NUM> or less, aggregates derived from components constituting the liquid-repellent layer <NUM> are less likely to adhere to the surface of the liquid-repellent layer <NUM>, and insertion of the aggregates into the nozzle <NUM> can be suppressed. As a result, the deterioration of the liquid jettability is suppressed.

<FIG> is an enlarged view of a broken line frame B in <FIG>.

As shown in <FIG>, the liquid jetting structure <NUM> has a first layer <NUM> and a second layer <NUM> on an inner wall <NUM> of the nozzle <NUM> in this order. The first layer <NUM> and the second layer <NUM> provided on the inner wall <NUM> of the nozzle <NUM> are the same as the first layer <NUM> and the second layer <NUM> provided on the jetting surface <NUM> of the nozzle substrate <NUM>.

Since the liquid jetting structure <NUM> has the first layer <NUM> and the second layer <NUM> on the inner wall <NUM> of the nozzle <NUM> in this order, the inner wall <NUM> of the nozzle <NUM> has excellent alkali resistance.

The flow passage substrate <NUM> is, for example, a substrate made of silicon, and may be a single crystal silicon substrate or a polycrystal silicon substrate. As shown in <FIG>, the flow passage substrate <NUM> is composed of a wall member <NUM> and a lid member <NUM>, and the wall member <NUM> and the lid member <NUM> are preferably bonded by adhesion or the like. The liquid flow passage <NUM> communicating with the nozzle <NUM> is formed in the flow passage substrate <NUM>. The liquid flow passage <NUM> includes a nozzle communication path <NUM>, a pressure chamber <NUM>, and a liquid supply path <NUM>.

The nozzle communication path <NUM> is a flow passage connecting the pressure chamber <NUM> and the nozzle <NUM>. The nozzle communication path <NUM> is preferably linear in a cross section.

The pressure chamber <NUM> is a flow passage whose volume changes by application of a driving voltage in a case where the liquid jetting structure <NUM> is used for a liquid jetting head described below. A planar shape of the pressure chamber <NUM> is, for example, a substantially square shape in a case where the liquid jetting structure <NUM> is viewed in a plan view, and has an outlet of the liquid to the nozzle communication path <NUM> at one of both corner portions on the diagonal line and the liquid supply path <NUM> as an inlet of the liquid at the other. The planar shape of the pressure chamber <NUM> is not limited to a substantially square shape, and may be a rectangle, a trapezoid, or the like.

The liquid supply path <NUM> is a flow passage that is connected to a liquid tank (not shown) in a case where the liquid jetting structure <NUM> is incorporated into a liquid jetting device described below. A liquid is supplied from the liquid tank to the pressure chamber <NUM> via the liquid supply path <NUM>. The arrows in the figure indicate a direction in which the liquid flows.

The liquid jetting structure <NUM> has a first layer <NUM> and a second layer <NUM> on an inner wall <NUM> of the liquid flow passage <NUM> in this order, as on the inner wall <NUM> of the nozzle <NUM> shown in <FIG>. The first layer <NUM> and the second layer <NUM> provided on the inner wall <NUM> of the liquid flow passage <NUM> are the same as the first layer <NUM> and the second layer <NUM> provided on the jetting surface <NUM> of the nozzle substrate <NUM>. Specifically, the inner wall <NUM> of the liquid flow passage <NUM> has a surface of the wall member <NUM> on a side where the liquid flow passage <NUM> is formed, a surface of the lid member <NUM> on a side where the liquid flow passage <NUM> is formed, and a surface of the nozzle substrate <NUM> on a side where the liquid flow passage <NUM> is formed.

Since the liquid jetting structure <NUM> has the first layer <NUM> and the second layer <NUM> on the inner wall <NUM> of the liquid flow passage <NUM> in this order, the inner wall <NUM> of the liquid flow passage <NUM> has excellent alkali resistance.

In addition to the structure shown in <FIG>, the structure of the flow passage substrate <NUM> may be, for example, the structure shown in <FIG>.

<FIG> is a schematic cross-sectional view showing a modification example of the liquid jetting structure of the present disclosure.

As shown in <FIG>, a liquid jetting structure 100A comprises a nozzle substrate <NUM>, and a flow passage substrate 20A on which a liquid flow passage <NUM> communicating with the nozzle <NUM> is formed. The configuration of the nozzle substrate <NUM> is as described above. The liquid flow passage <NUM> includes a nozzle communication path <NUM>, a pressure chamber <NUM>, a liquid supply path <NUM>, and a circulation flow passage <NUM>.

The nozzle communication path <NUM> is the same as the nozzle communication path <NUM> described above, and is a flow passage connecting the pressure chamber <NUM> and the nozzle <NUM>.

The pressure chamber <NUM> is the same as the pressure chamber <NUM> described above, and is a flow passage whose volume changes by application of a driving voltage in a case where the liquid jetting structure 100A is used for a liquid jetting head described below.

The liquid supply path <NUM> is the same as the liquid supply path <NUM> described above, and is a flow passage that is connected to a liquid tank (not shown) in a case where the liquid jetting structure 100A is incorporated into a liquid jetting device described below. A liquid is supplied from the liquid tank to the pressure chamber <NUM> via the liquid supply path <NUM>.

The circulation flow passage <NUM> is a flow passage that is connected to a liquid tank (not shown) in a case where the liquid jetting structure 100A is incorporated into a liquid jetting device described below. Although the liquid is sent to the nozzle <NUM> through the liquid supply path <NUM>, the pressure chamber <NUM>, and the nozzle communication path <NUM>, the liquid not jetted from the nozzle opening <NUM> of the nozzle <NUM> is collected in the liquid tank through the circulation flow passage <NUM>.

The liquid jetting structure 100A has a first layer <NUM> and a second layer <NUM> on an inner wall 201A of the liquid flow passage <NUM> in this order, as on the inner wall <NUM> of the liquid flow passage <NUM>. The first layer <NUM> and the second layer <NUM> provided on the inner wall 201A of the liquid flow passage <NUM> are the same as the first layer <NUM> and the second layer <NUM> provided on the inner wall <NUM> of the liquid flow passage <NUM>.

In the liquid jetting structure of the present disclosure, as shown in <FIG> and <FIG>, it is preferable that the first layer <NUM> and the second layer <NUM> are provided on the inner wall <NUM> of the nozzle <NUM>. That is, it is preferable that the liquid jetting structure of the present disclosure comprises: a nozzle substrate on which a nozzle for jetting a liquid is formed; and a flow passage substrate on which a liquid flow passage communicating with the nozzle is formed, in which a first layer, a second layer, and a liquid-repellent layer are provided in this order on a jetting surface of the nozzle substrate, the first layer and the second layer are provided in this order on an inner wall of the nozzle and an inner wall of the liquid flow passage, the first layer is a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, and the second layer is a layer containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON.

In both the liquid jetting structure <NUM> and the liquid jetting structure 100A, the first layer <NUM> and the second layer <NUM> are provided on the inner wall <NUM> of the nozzle <NUM>. However, the first layer <NUM> and the second layer <NUM> may not be provided on the inner wall <NUM> of the nozzle <NUM>. Usually, an area of the inner wall <NUM> of the nozzle <NUM> is very small with respect to an area of the inner wall <NUM> of the liquid flow passage <NUM> (inner wall 201A of the liquid flow passage <NUM>). Therefore, even though the first layer <NUM> and the second layer <NUM> are not provided on the inner wall <NUM> of the nozzle <NUM>, the internal flow passage is excellent in alkali resistance.

Next, a method of forming the first layer <NUM>, the second layer <NUM>, and the liquid-repellent layer <NUM> on the nozzle substrate <NUM>, the nozzle <NUM>, and the flow passage substrate <NUM> will be described. The first layer <NUM>, the second layer <NUM>, and the liquid-repellent layer <NUM> are preferably formed after the nozzle substrate <NUM> and the flow passage substrate <NUM> are bonded to obtain a bonded body.

First, it is preferable to perform surface treatment on a surface of the bonded body in advance before forming the first layer <NUM> on the surface of the bonded body of the nozzle substrate <NUM> and the flow passage substrate <NUM>. Examples of the surface treatment include UV ozone treatment and oxygen plasma treatment. Among these, the surface treatment is preferably oxygen plasma treatment from the viewpoint of enhancing the adhesiveness between the bonded body and the first layer. The irradiation conditions of the oxygen plasma can be appropriately adjusted, for example, the irradiation is performed under the conditions of an output of <NUM> W to <NUM> W, a flow rate of <NUM>/min to <NUM>/min, and an irradiation time of <NUM> minute to <NUM> minutes.

Next, the first layer <NUM> is formed on a surface of the surface-treated bonded body. Specifically, the first layer <NUM> is formed on the jetting surface <NUM> of the nozzle substrate <NUM>, and on the inner wall <NUM> of the nozzle <NUM> and the inner wall <NUM> of the liquid flow passage <NUM>.

The first layer <NUM> is preferably formed by an atomic layer deposition (ALD) method. As the ALD method, a generally known method can be adopted. In a case where the ALD method is used, a dense layer is formed, so that the effect of suppressing the permeation of the alkaline liquid is high.

The first layer <NUM> can be formed, for example, by repeating four steps of a step of disposing the surface-treated bonded body in an atomic layer deposition (ALD) chamber, introducing H<NUM>O gas, and then introducing precursor gas, a step of discharging surplus gas, a step of introducing H<NUM>O gas, and a step of discharging surplus gas.

First, by introducing H<NUM>O gas, a hydroxyl group is formed on the surface of the bonded body. Next, by introducing precursor gas, the hydroxyl group formed on the surface of the bonded body reacts with a precursor. Further, by introducing H<NUM>O gas, the precursor that has reacted with the hydroxyl group reacts with H<NUM>O.

Examples of the precursor used in a case of forming a tantalum oxide layer as the first layer <NUM> include tert-butylimino tri(diethylamino)tantalum (TBTDET), tert-butylimino tri(dimethylamino)tantalum (TBTDMT), tert-butylimino tri(ethylmethylamino)tantalum (TBTEMT), ethylimino tri(diethylamino)tantalum (EITDET), ethylimino tri(dimethylamino)tantalum (EITDMT), ethylimino tri(ethylmethylamino)tantalum (EITEMT), tert-amylimino tri(dimethylamino)tantalum (TAIMAT), tert-amylimino tri(diethylamino)tantalum, pentakis(dimethylamino)tantalum, and tert-amylimino tri(ethylmethylamino)tantalum.

Examples of the precursor used in a case of forming a zirconium oxide layer as the first layer <NUM> include tetrakis(N-ethylmethylamino)zirconium (TEMAZ) and tris(dimethylamino)cyclopentadienyl zirconium (ZAC).

Examples of the precursor used in a case of forming a titanium oxide layer as the first layer <NUM> include tetrakis(dimethylamino)titanium (TDMAT), tetrakis(diethylamino)titanium (TDEAT), and tetrakis(ethylmethylamino)titanium (TEMAT).

Examples of the precursor used in a case of forming a hafnium oxide layer as the first layer <NUM> include tetrakis(dimethylamino)hafnium (TDMAHf), tetrakis(diethylamino)hafnium (TDEAHf), and tetrakis(ethylmethylamino)hafnium (TEMAHf).

In a case of forming the first layer <NUM>, ozone gas may be used instead of H<NUM>O gas.

Next, the second layer <NUM> is formed on the first layer <NUM>.

A method of forming the second layer <NUM> is not particularly limited, and examples thereof include a chemical vapor deposition (CVD) method. As the CVD method, a generally known method can be adopted. It is more preferable that the second layer <NUM> is formed by an atomic layer deposition (ALD) method. As the ALD method, a generally known method can be adopted. In a case where the ALD method is used, a dense layer is formed, so that the effect of suppressing the permeation of the alkaline liquid is high.

Next, the liquid-repellent layer <NUM> is formed on the second layer <NUM>.

Although a method of forming the liquid-repellent layer <NUM> is not particularly limited, a method of performing hydrophilization treatment on the surface of the second layer <NUM> and then forming a film by a vapor deposition method using a silane coupling agent is preferable. Since the silane coupling agent is bonded to a hydrophilic group formed on the surface of the second layer after hydrolysis, the adhesiveness between the liquid-repellent layer <NUM> and the second layer <NUM> is high, and the permeation of the alkaline liquid is suppressed.

Examples of the hydrophilization treatment include UV ozone treatment and oxygen plasma treatment. Among these, the hydrophilization treatment is preferably oxygen plasma treatment. The irradiation conditions can be appropriately adjusted, for example, the irradiation is performed under the conditions of an output of <NUM> W to <NUM> W, a flow rate of <NUM>/min to <NUM>/min, and an irradiation time of <NUM> minute to <NUM> minutes.

The film formation method by the vapor deposition method can be performed, for example, by disposing a bonded body in which the first layer <NUM> and the second layer <NUM> are laminated in a vacuum chamber and putting a silane coupling agent in a vapor deposition boat. A vapor deposition temperature is preferably <NUM> to <NUM>.

The silane coupling agent is preferably a fluorine-containing silane coupling agent, more preferably a silane coupling agent having a perfluoropolyether structure, and still more preferably an alkoxysilane having a perfluoropolyether structure. Examples of the perfluoropolyether structure include structures represented by Formulas <NUM> to <NUM>. The preferred embodiment is as described above.

The silane coupling agent may be a commercially available product, and examples of the preferred silane coupling agent include the following commercially available products. Examples of the silane coupling agent having a structure represented by Formula <NUM>, in which m represents an integer of <NUM> to <NUM> and n represents an integer of <NUM> to <NUM> in Formula <NUM>, include KY1901, KY1903, and KY1903-<NUM> manufactured by Shin-Etsu Chemical Co. Examples of the silane coupling agent having a structure represented by Formula <NUM>, in which n represents an integer of <NUM> to <NUM> in Formula <NUM>, include X-<NUM>-<NUM> manufactured by Shin-Etsu Chemical Co. Examples of the silane coupling agent having a structure represented by Formula <NUM>, in which n represents an integer of <NUM> to <NUM> in Formula <NUM>, include OPTOOL DSX manufactured by Daikin Industries, Ltd.

In order to further improve the adhesiveness between the second layer <NUM> and the liquid-repellent layer <NUM>, it is preferable that the bonded body in which the first layer <NUM>, the second layer <NUM>, and the liquid-repellent layer <NUM> are laminated is held in a high-temperature and high-humidity environment after film formation. For example, the bonded body in which the first layer <NUM>, the second layer <NUM>, and the liquid-repellent layer <NUM> are laminated is held at a temperature of <NUM> to <NUM> and a humidity of <NUM>% to <NUM>% for <NUM> hours to <NUM> hours.

Next, the liquid-repellent layer <NUM> provided on the inner wall <NUM> of the nozzle <NUM> and the inner wall <NUM> of the liquid flow passage <NUM> is removed.

For example, a tape is attached to the surface of the liquid-repellent layer <NUM> provided on the jetting surface of the nozzle substrate <NUM>, and oxygen plasma treatment is performed on the nozzle <NUM> and the liquid flow passage <NUM>, whereby the liquid-repellent layer <NUM> provided on the inner wall <NUM> of the nozzle <NUM> and the inner wall <NUM> of the liquid flow passage <NUM> can be removed.

The liquid jetting head of the present disclosure comprises a liquid jetting structure. The liquid jetting head of the present disclosure will be described with reference to <FIG>.

<FIG> is a cross-sectional view showing an embodiment of the liquid jetting head of the present disclosure.

As shown in <FIG>, a liquid jetting head <NUM> comprises a liquid jetting structure 100A and a piezoelectric element <NUM>.

The configuration of the liquid jetting structure 100A is as described above. The lid member <NUM> in the liquid jetting structure 100A functions as a diaphragm in the liquid jetting head <NUM>.

On the lid member (diaphragm) <NUM>, the piezoelectric element <NUM> having a laminated structure of a lower electrode <NUM>, a piezoelectric layer <NUM>, and an upper electrode <NUM> is arranged. The piezoelectric element <NUM> is provided above the pressure chamber <NUM>.

The upper electrode <NUM> is an individual electrode patterned corresponding to a shape of the pressure chamber <NUM>. In a case where a driving voltage is applied to the upper electrode <NUM> of the piezoelectric element <NUM> provided above the pressure chamber <NUM> according to input data, the piezoelectric element <NUM> and the lid member (diaphragm) <NUM> are deformed and the volume of the pressure chamber <NUM> is changed. Because of the pressure change in the pressure chamber <NUM>, a liquid is jetted from the nozzle opening <NUM> of the nozzle <NUM> via the nozzle communication path <NUM>.

A heater may be provided inside the pressure chamber <NUM> as a pressure generating element instead of the piezoelectric element, a driving voltage may be supplied to the heater to generate heat, and the liquid in the pressure chamber <NUM> may be jetted from the nozzle opening <NUM> by utilizing the film boiling phenomenon.

The liquid jetting device of the present disclosure comprises a liquid jetting head. Hereinafter, an ink jet recording device, which is an example of the liquid jetting device, will be described.

The ink jet recording device comprises, for example, a plurality of ink jet heads (an example of a liquid jetting head) provided for each ink color, an ink storage unit that stores ink to be supplied to each ink jet head, a paper feed unit that supplies recording paper, a decurling unit that removes curl of the recording paper, a transport unit that is disposed facing a jetting surface of each ink jet head and transports the recording paper, an image detection unit that reads an image recording result, and a paper discharge unit that discharges an image-recorded object to the outside.

Each configuration of the ink jet recording device other than the ink jet head is the same as that of the known configuration in the related art, and for example, <CIT> can be referred to.

The liquid jetting device of the present disclosure preferably has a liquid circulation mechanism that circulates a liquid between the liquid jetting head and the liquid tank. For example, by using the liquid jetting head comprising the liquid jetting structure 100A shown in <FIG>, a liquid can be circulated between the liquid jetting head and the liquid tank.

Hereinafter, examples of the present disclosure will be described, but the present disclosure is not limited to the following examples.

A nozzle substrate on which a nozzle was formed and a flow passage substrate on which a liquid flow passage was formed were bonded to prepare a bonded body having the same structure as in <FIG> and having a size of <NUM> × <NUM>.

The bonded body was disposed in a vacuum chamber. After evacuating the inside of the vacuum chamber, it was replaced with oxygen to generate oxygen plasma. The irradiation conditions of the oxygen plasma were an output of <NUM> W, a flow rate of <NUM>/min, and an irradiation time of <NUM> minute.

Next, the bonded body after the step (a1) was disposed in an atomic layer deposition (ALD) chamber, and H<NUM>O gas was introduced to form a hydroxyl group on a surface of the bonded body. Next, tert-butylimino tri(ethylmethylamino)tantalum (TBTEMT) gas was introduced, and the hydroxyl group formed on the surface of the bonded body was reacted with TBTEMT. After that, surplus gas was discharged. Next, H<NUM>O gas was introduced to react TBTEMT bonded to the hydroxyl group in the previous reaction with H<NUM>O. After that, surplus gas was discharged. Then, the introduction and discharge of TBTEMT gas and the introduction and discharge of H<NUM>O gas were repeated as one cycle until a predetermined thickness (<NUM>) was reached, thereby forming a tantalum oxide layer.

Next, a SiO<NUM> layer was formed on the bonded body after the step (b1) by chemical vapor deposition (CVD). A film was formed at a substrate temperature of <NUM> by using SiCl<NUM> as a raw material. A thickness of the SiO<NUM> layer was <NUM>.

Next, the bonded body after the step (c1) was disposed in a vacuum chamber. After evacuating the inside of the vacuum chamber, it was replaced with oxygen to generate oxygen plasma. The irradiation conditions of the oxygen plasma were an output of <NUM> W, a flow rate of <NUM>/min, and an irradiation time of <NUM> minute.

Next, the bonded body after the step (d1) was disposed in a vapor deposition machine chamber. A silane coupling agent was added to a tungsten boat. As the silane coupling agent, KY1901 (a silane coupling agent having a perfluoropolyether structure represented by Formula <NUM>, manufactured by Shin-Etsu Chemical Co. ) was used.

In Formula <NUM>, m represents an integer of <NUM> to <NUM>, n represents an integer of <NUM> to <NUM>. * indicates a bonding position to other structures in the compound.

A shutter was opened in a case where a temperature of the tungsten boat reached <NUM>, and, while monitoring a film thickness with a crystal oscillator, the shutter was closed in a case where the film thickness reached <NUM>, and the silane coupling agent was vapor-deposited.

Next, in order to promote the hydrolysis reaction of the silane coupling agent and the condensation reaction between the bonded body and the silane coupling agent after the step (e1), the mixture was left for <NUM> hours in an environment of a temperature of <NUM> and a humidity of <NUM>%. A contact angle of the formed liquid-repellent layer with water was <NUM>° or more. The contact angle with water was measured under the condition of <NUM> by using a fully automatic contact angle meter (product name "DM-<NUM>", manufactured by Kyowa Interface Science Co.

Next, a tape was attached to a surface of the nozzle substrate in the bonded body after the step (f1), and oxygen plasma treatment was performed on the nozzle and the liquid flow passage from a surface of the flow passage substrate opposite to a surface bonded to the nozzle substrate. As a result, the liquid-repellent layer formed on the inner wall of the nozzle and the inner wall of the liquid flow passage was removed, thereby obtaining a liquid jetting structure.

A liquid jetting structure was obtained in the same manner as in the steps (a1) and (c1) to (g1) of Example <NUM> except that the step (b1) of Example <NUM> was changed to the following step (b2).

A zirconium oxide layer was formed in the same manner as in the step (b1) except that TBTEMT in the step (b1) was changed to tris(dimethylamino)cyclopentadienyl zirconium (ZAC).

A liquid jetting structure was obtained in the same manner as in the steps (a1) and (c1) to (g1) of Example <NUM> except that the step (b1) of Example <NUM> was changed to the following step (b3).

A titanium oxide layer was formed in the same manner as in the step (b1) except that TBTEMT in the step (b1) was changed to tetrakis(dimethylamino)titanium (TDMAT).

A liquid jetting structure was obtained in the same manner as in the steps (a1) and (c1) to (g1) of Example <NUM> except that the step (b1) of Example <NUM> was changed to the following step (b4).

A hafnium oxide layer was formed in the same manner as in the step (b1) except that TBTEMT in the step (b1) was changed to tetrakis(dimethylamino)hafnium (TDMAHf).

A liquid jetting structure was obtained in the same manner as in the steps (a1) to (d1), (f1), and (g1) of Example <NUM> except that the step (e1) of Example <NUM> was changed to the following step (e2).

The silane coupling agent was vapor-deposited in the same manner as in the step (e1) except that the film thickness by the vapor deposition of the silane coupling agent was changed from <NUM> to <NUM> in the step (e1).

A liquid jetting structure was obtained in the same manner as in the steps (a1), (b1), and (d1) to (g1) of Example <NUM> except that the step (c1) of Example <NUM> was changed to the following step (c2).

A SiN layer was formed on the bonded body after the step (b1) by chemical vapor deposition (CVD). Monosilane (SiH<NUM>), ammonia, and nitrogen were used as raw materials, and a film was formed at a substrate temperature of <NUM>. A thickness of the SiN layer was <NUM>.

A liquid jetting structure was obtained in the same manner as in the steps (a1) and (c1) to (g1) of Example <NUM> except that the step (b1) of Example <NUM> was changed to the following step (b5).

A tantalum oxide layer was formed in the same manner as in the step (b1) except that the thickness was changed to <NUM>.

A liquid jetting structure was obtained in the same manner as in the steps (a1) and (c1) to (g1) of Example <NUM> except that the step (b1) of Example <NUM> was changed to the following step (b6).

A liquid jetting structure was obtained in the same manner as in the steps (a1), (b1), and (d1) to (g1) of Example <NUM> except that the step (c1) of Example <NUM> was changed to the following step (c3).

An SiO<NUM> layer was formed in the same manner as in the step (c1) except that the thickness was changed to <NUM>.

A liquid jetting structure was obtained in the same manner as in the steps (a1) and (d1) to (g1) of Example <NUM> except that the step (b1) of Example <NUM> was changed to the following step (b7) and the step (c1) was changed to the following step (c4).

A liquid jetting structure was obtained in the same manner as in the steps (a1) to (d1) and (g1) of Example <NUM> except that the step (e1) of Example <NUM> was changed to the following step (e3) and the step (f1) was changed to the following step (f2).

The silane coupling agent was vapor-deposited in the same manner as in the step (e1) except that KY1901 in the step (e1) was changed to trichloro(<NUM>, <NUM>, <NUM>, <NUM>-heptadecafluorodecyl)silane (FDTS).

In order to promote the hydrolysis reaction of the silane coupling agent and the condensation reaction between the bonded body and the silane coupling agent after the step (e3), the mixture was left for <NUM> hours in an environment of a temperature of <NUM>. A contact angle of the formed liquid-repellent layer with water was <NUM>° or more.

After the step (a1), the step (c1) was carried out, and then the step (b1) was carried out. Further, the steps (d1) to (g1) were carried out in the same manner as in Example <NUM> to obtain a liquid jetting structure.

After the step (a1), the step (b1) was carried out. Next, the following step (j1) was carried out. Further, the steps (d1) to (g1) were carried out in the same manner as in Example <NUM> to obtain a liquid jetting structure.

A silicone polymer was plasma-polymerized on the bonded body after the step (b1) with reference to Examples of <CIT> to form a plasma polymerization film. A thickness of the plasma polymerization film was <NUM>.

After the step (a1) was carried out, the following step (k1) was carried out. Further, the steps (c1) to (g1) were carried out in the same manner as in Example <NUM> to obtain a liquid jetting structure.

A tantalum oxide layer was formed on the bonded body after the step (a1) by a sputtering method. The tantalum oxide layer was formed only on the surface of the nozzle substrate, not on the inner wall of the nozzle and the inner wall of the liquid flow passage. A thickness of the tantalum oxide layer was <NUM>.

After the step (a1) was carried out, the steps (c1) to (g1) were carried out in the same manner as in Example <NUM> to obtain a liquid jetting structure. That is, the step (b1) was not carried out.

After the step (a1) and the step (b1) were carried out, the steps (d1) to (g1) were carried out in the same manner as in Example <NUM> to obtain a liquid jetting structure. That is, the step (c1) was not carried out.

Next, the wipe resistance and the alkali resistance of the surface of the nozzle substrate, the alkali resistance of the internal flow passage, and the jettability were evaluated. The evaluation method is as follows.

The bonded body was disposed in a vacuum chamber. After evacuating the inside of the vacuum chamber, it was replaced with oxygen to generate oxygen plasma. The irradiation conditions of the oxygen plasma were an output of <NUM> W, a flow rate of <NUM>/min, and an irradiation time of <NUM> minutes.

Next, the bonded body after the step (p1) was disposed in an atomic layer deposition (ALD) chamber, and H<NUM>O gas was introduced to form a hydroxyl group on a surface of the bonded body. Next, tetrakis(dimethylamino)hafnium (TDMAHf) gas was introduced, and a hydroxyl group formed on the surface of the bonded body was reacted with TDMAHf. After that, surplus gas was discharged. Next, H<NUM>O gas was introduced to react TDMAHf bonded to the hydroxyl group in the previous reaction with H<NUM>O. After that, surplus gas was discharged. Then, the introduction and discharge of TDMAHf gas and the introduction and discharge of H<NUM>O gas were repeated as one cycle until a predetermined thickness (<NUM>) was reached, thereby forming a hafnium oxide layer.

Next, the bonded body after the step (q1) was disposed in an atomic layer deposition (ALD) chamber, and H<NUM>O gas was introduced to form a hydroxyl group on a surface of the bonded body. Next, tris(dimethylamino)silane (TDMAS) gas was introduced, and a hydroxyl group formed on the surface of the bonded body was reacted with TDMAS. After that, surplus gas was discharged. Next, H<NUM>O gas was introduced to react TDMAS bonded to the hydroxyl group in the previous reaction with H<NUM>O. After that, surplus gas was discharged. Then, the introduction and discharge of TDMAS gas and the introduction and discharge of H<NUM>O gas were repeated as one cycle until a predetermined thickness (<NUM>) was reached, thereby forming a silicon oxide layer.

Next, the bonded body after the step (r1) was disposed in a vacuum chamber. After evacuating the inside of the vacuum chamber, it was replaced with oxygen to generate oxygen plasma. The irradiation conditions of the oxygen plasma were an output of <NUM> W, a flow rate of <NUM>/min, and an irradiation time of <NUM> minutes.

Next, the bonded body after the step (s1) was disposed in a vapor deposition machine chamber. A silane coupling agent was added to a tungsten boat. As the silane coupling agent, KY1901 (a silane coupling agent having a perfluoropolyether structure represented by Formula <NUM>, manufactured by Shin-Etsu Chemical Co. ) was used.

Next, in order to promote the hydrolysis reaction of the silane coupling agent and the condensation reaction between the bonded body and the silane coupling agent after the step (t1), the mixture was left for <NUM> hours in an environment of a temperature of <NUM> and a humidity of <NUM>%. A contact angle of the formed liquid-repellent layer with water was <NUM>° or more. The contact angle with water was measured under the condition of <NUM> by using a fully automatic contact angle meter (product name "DM-<NUM>", manufactured by Kyowa Interface Science Co.

Next, a tape was attached to a surface of the nozzle substrate in the bonded body after the step (u1), and oxygen plasma treatment was performed on the nozzle and the liquid flow passage from a surface of the flow passage substrate opposite to a surface bonded to the nozzle substrate. As a result, the liquid-repellent layer formed on the inner wall of the nozzle and the inner wall of the liquid flow passage was removed, thereby obtaining a liquid jetting structure.

A liquid jetting structure was obtained in the same manner as in the steps (p1) and (r1) to (v1) of Example 1A except that the step (q1) of Example 1A was changed to the following step (q2).

A liquid jetting structure was obtained in the same manner as in the steps (p1) and (r1) to (v1) of Example 1A except that the step (q1) of Example 1A was changed to the following step (q3).

A zirconium oxide layer was formed in the same manner as in the step (q1) except that TDMAHf in the step (q1) was changed to tris(dimethylamino)cyclopentadienyl zirconium (ZAC).

A liquid jetting structure was obtained in the same manner as in the steps (p1) and (r1) to (v1) of Example 1A except that the step (q1) of Example 1A was changed to the following step (q4).

A tantalum oxide layer was formed in the same manner as in the step (q1) except that TDMAHf in the step (q1) was changed to tert-butylimino tri(ethylmethylamino)tantalum (TBTEMT).

A liquid jetting structure was obtained in the same manner as in the steps (p1) and (r1) to (v1) of Example 1A except that the step (q1) of Example 1A was changed to the following step (q5).

A titanium oxide layer was formed in the same manner as in the step (q1) except that TDMAHf in the step (q1) was changed to tetrakis(dimethylamino)titanium (TDMAT).

A liquid jetting structure was obtained in the same manner as in the steps (p1), (q1), and (s1) to (v1) of Example 1A except that the step (r1) of Example 1A was changed to the following step (r2).

The bonded body after the step (q1) was disposed in an atomic layer deposition (ALD) chamber, and H<NUM>O gas was introduced to form a hydroxyl group on a surface of the bonded body. Next, tris(dimethylamino)silane (TDMAS) gas was introduced, and a hydroxyl group formed on the surface of the bonded body was reacted with TDMAS. After that, surplus gas was discharged. Next, H<NUM>O gas was introduced to react TDMAS bonded to the hydroxyl group in the previous reaction with H<NUM>O. After that, surplus gas was discharged. Then, the introduction and discharge of TDMAS gas and the introduction and discharge of H<NUM>O gas were repeated as one cycle until a predetermined thickness (<NUM>) was reached, thereby forming a silicon oxide layer.

A liquid jetting structure was obtained in the same manner as in the steps (p1), (q1), and (s1) to (v1) of Example 1A except that the step (r1) of Example 1A was changed to the following step (r3).

A liquid jetting structure was obtained in the same manner as in the steps (p1), (q1), and (s1) to (v1) of Example 1A except that the step (r1) of Example 1A was changed to the following step (r4).

A liquid jetting structure was obtained in the same manner as in the steps (p1), (q1), and (s1) to (v1) of Example 1A except that the step (r1) of Example 1A was changed to the following step (r5).

Black ink disclosed in [<NUM>] of <CIT> was prepared. Ink whose pH was adjusted to <NUM> by adding sodium hydroxide to the prepared black ink was used as evaluation ink. The prepared liquid jetting structure was immersed in the evaluation ink and allowed to stand in a constant-temperature tank set at <NUM>. After <NUM> hours had passed, a static contact angle on the surface of the nozzle substrate was measured using the newly prepared evaluation ink. The contact angle with the ink was measured under the condition of <NUM> by using a fully automatic contact angle meter (product name "DM-<NUM>", manufactured by Kyowa Interface Science Co. The alkali resistance was evaluated based on the contact angle. The evaluation standard is as follows. It can be said that the larger the contact angle, the better the alkali resistance.

<NUM>: The contact angle is <NUM>° or more and less than <NUM>°.

<NUM>: The contact angle is less than <NUM>°.

Since the contact angle of the internal flow passage cannot be measured directly, the evaluation was performed using the following method instead.

First, in the examples and the comparative examples, the first step to the step (f1) in the manufacture of the liquid jetting structure were carried out, and the bonded body after the step (f1) was prepared. Then, by performing oxygen plasma treatment on the surface of the nozzle substrate, the liquid-repellent layer on the surface of the nozzle substrate was removed, and an evaluation structure was obtained. The surface condition of the nozzle substrate from which the liquid-repellent layer has been removed is the same as the surface condition of the internal flow passage in the liquid jetting structure.

The prepared liquid evaluation structure was immersed in the evaluation ink and allowed to stand in a constant-temperature tank set at <NUM>. A surface roughness Ra of the nozzle substrate in the evaluation structure was measured before the immersion and after <NUM> hours had passed since the immersion. The surface roughness Ra was measured using an atomic force microscope (product name "Dimension icon with ScanAsyst", manufactured by BRUKER), and an average value measured at five points was adopted. The alkali resistance was evaluated based on a degree of change in the surface roughness Ra. The degree of change is expressed by a ratio (times) of the surface roughness Ra after the immersion to the surface roughness Ra before the immersion. The evaluation standard is as follows. It can be said that the smaller the degree of change in the surface roughness Ra, the better the alkali resistance.

<NUM>: The degree of change is less than <NUM> times.

<NUM>: The degree of change is <NUM> times or more and less than <NUM> times.

<NUM> : The degree of change is <NUM> times or more.

The evaluation ink was added dropwise to a wiping member (product name "TORAYSEE", manufactured by Toray Industries, Inc. The surface of the nozzle substrate in the prepared liquid jetting structure was pressed against the surface to which the ink was added dropwise at a constant pressure of <NUM> kPa and slid reciprocatively. After <NUM>,<NUM> times of reciprocating sliding, a static contact angle on the surface of the nozzle substrate was measured using the newly prepared evaluation ink. The contact angle with the ink was measured under the condition of <NUM> by using a fully automatic contact angle meter (product name "DM-<NUM>", manufactured by Kyowa Interface Science Co. The wipe resistance was evaluated based on the contact angle. The evaluation standard is as follows. It can be said that the larger the contact angle, the better the wipe resistance.

A wiping member (product name "TORAYSEE", manufactured by Toray Industries, Inc. ) was pressed against the surface of the nozzle substrate in the prepared liquid jetting structure at a constant pressure of <NUM> kPa and slid reciprocatively <NUM> times.

Next, a liquid jetting head was prepared by bonding a diaphragm to the liquid jetting structure and arranging a piezoelectric element. The prepared liquid jetting head was incorporated into an ink jet recording experimental device.

Before operating the inkjet recording experimental device, liquid circulation with ink was performed for <NUM> minutes to remove ink remaining in the ink contact portion in the device. After that, the device was operated continuously for <NUM> hour to jet ink. After <NUM> hour, a wiping member (product name "TORAYSEE", manufactured by Toray Industries, Inc. ) was pressed against the surface of the nozzle substrate at a constant pressure of <NUM> kPa and slid reciprocatively <NUM> times. After repeating the continuous jetting and the sliding operation <NUM> times, the number of nozzles that have caused a jetting failure was counted. The jetting failure includes a state in which ink is not jetted at all (non-jetting) and a state in which ink is jetted or not jetted (intermittent non-jetting). The jettability was evaluated based on the number of nozzles that have caused the jetting failure. The evaluation standard is as follows. It can be said that the smaller the number of nozzles that have caused the jetting failure, the better the jettability. In the liquid jetting structure, <NUM> pieces of nozzles are formed.

<NUM>: The number of nozzles that have caused the jetting failure is <NUM>.

<NUM>: The number of nozzles that have caused the jetting failure is <NUM> or <NUM>.

<NUM>: The number of nozzles that have caused the jetting failure is <NUM> to <NUM>.

<NUM>: The number of nozzles that have caused the jetting failure is <NUM> or more.

<NUM>: The degree of change is <NUM> times or more.

The evaluation results are shown in Table <NUM> and Table <NUM>. In Tables <NUM> and <NUM>, the first layer means the lowest layer provided in the nozzle substrate and the internal flow passage. The second layer means a layer provided on the first layer. The liquid-repellent layer is a layer provided on the second layer on the jetting surface of the nozzle substrate. For the liquid-repellent layer, whether or not it has a perfluoropolyether structure (PFPE structure) is described. For the first layer and the second layer, the types and thicknesses of components constituting the layers are described. In Tables <NUM> and <NUM>, the term "second layer/first layer" means a ratio of the thickness of the second layer to the thickness of the first layer.

As shown in Table <NUM>, in Examples <NUM> to <NUM>, it was found that since the liquid jetting structure of the present disclosure comprises: a nozzle substrate on which a nozzle for jetting a liquid is formed; and a flow passage substrate on which a liquid flow passage communicating with the nozzle is formed, in which a first layer, a second layer, and a liquid-repellent layer are provided in this order on a jetting surface of the nozzle substrate, the first layer and the second layer are provided in this order on an inner wall of the liquid flow passage, the first layer is a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, and the second layer is a layer containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON, the jetting surface is excellent in wipe resistance and the jetting surface and the internal flow passage are excellent in alkali resistance.

On the other hand, in Comparative Example <NUM>, it was found that since the first layer is an SiO<NUM> layer and the second layer is a tantalum oxide layer on both the surface of the nozzle substrate and the inner wall of the internal flow passage, the jetting surface is inferior in wipe resistance.

In Comparative Example <NUM>, it was found that since the second layer is a plasma polymerization film made of a silicone material on both the surface of the nozzle substrate and the inner wall of the internal flow passage, the jetting surface is inferior in wipe resistance.

In Comparative Example <NUM>, it was found that since only an SiO<NUM> layer is provided on the inner wall of the internal flow passage, the internal flow passage is inferior in alkali resistance.

In Comparative Example <NUM>, it was found that since only an SiO<NUM> layer is provided on the surface of the nozzle substrate and the inner wall of the internal flow passage, the internal flow passage is inferior in alkali resistance.

In Comparative Example <NUM>, it was found that since only a tantalum oxide layer is provided on the surface of the nozzle substrate and the inner wall of the internal flow passage, the jetting surface is inferior in wipe resistance.

In Examples <NUM> and <NUM>, it was found that since the first layer is a layer of tantalum oxide or zirconium oxide, the internal flow passage is excellent in alkali resistance as compared with Examples <NUM> and <NUM>.

In Example <NUM>, it was found that since the second layer is an SiO<NUM> layer, the jetting surface is excellent in wipe resistance as compared with Example <NUM>.

In Example <NUM>, it was found that since the thickness of the first layer is <NUM> to <NUM>, the jetting surface and the internal flow passage are excellent in alkali resistance as compared with Example <NUM>, the jetting surface is excellent in wipe resistance as compared with Example <NUM>, and the jetting surface and the internal flow passage are excellent in alkali resistance as compared with Example <NUM>.

In Example <NUM>, it was found that since the thickness of the second layer is <NUM> or more, the jetting surface is excellent in wipe resistance as compared with Example <NUM>.

In Example <NUM>, it was found that since the ratio of the thickness of the second layer to the thickness of the first layer is <NUM> or more, the jetting surface is excellent in wipe resistance as compared with Example <NUM>.

In Example <NUM>, it was found that since the liquid-repellent layer contains a silicon compound having a perfluoropolyether structure, the jetting surface is excellent in wipe resistance as compared with Example <NUM>.

In Example <NUM>, it was found that since the thickness of the liquid-repellent layer is <NUM> to <NUM>, the jettability is excellent in wipe resistance as compared with Example <NUM>.

As shown in Table <NUM>, in Examples 1A to 9A, it was found that since the liquid jetting structure of the present disclosure comprises: a nozzle substrate on which a nozzle for jetting a liquid is formed; and a flow passage substrate on which a liquid flow passage communicating with the nozzle is formed, in which a first layer, a second layer, and a liquid-repellent layer are provided in this order on a jetting surface of the nozzle substrate, the first layer and the second layer are provided in this order on an inner wall of the liquid flow passage, the first layer is a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, and the second layer is a layer containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON, the jetting surface is excellent in wipe resistance and the jetting surface and the internal flow passage are excellent in alkali resistance.

In Examples 1A, 3A, and 4A, it was found that since the first layer is a layer of tantalum oxide, zirconium oxide, or hafnium oxide, the internal flow passage is excellent in alkali resistance as compared with Example 5A.

In Example 7A, it was found that since the thickness of the second layer is <NUM> to <NUM>, the jetting surface is excellent in wipe resistance and alkali resistance as compared with Example 8A.

Claim 1:
A liquid jetting structure (<NUM>) comprising:
a nozzle substrate (<NUM>) on which a nozzle (<NUM>) for jetting a liquid is formed; and
a flow passage substrate (<NUM>) on which a liquid flow passage (<NUM>) communicating with the nozzle (<NUM>) is formed,
wherein a first layer (<NUM>), a second layer (<NUM>), and a liquid-repellent layer (<NUM>) are provided in this order on a jetting surface (<NUM>) of the nozzle substrate (<NUM>),
the first layer (<NUM>) and the second layer (<NUM>) are provided in this order on an inner wall of the liquid flow passage (<NUM>),
the first layer (<NUM>) is a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, and
the second layer (<NUM>) is a layer containing at least one selected from the group consisting of SiO<NUM>, SiC, SiN, SiCN, and SiON, wherein a thickness of the second layer (<NUM>) is <NUM> to <NUM> or <NUM> to <NUM>.