Ink-repellent member, method for manufacturing ink-repellent member, inkjet head, and method for manufacturing article

Abstract

The invention provides an ink-repellent member, a method for manufacturing the ink-repellent member, an inkjet head, and a method for manufacturing an article. The ink-repellent member includes a base portion containing tantalum oxide and having a fluorine compound bonded to a surface of the base portion via a Ta-O-Si bond, in which, after the ink-repellent member is subjected to immersion treatments (1) and (2), in measurement of the surface by X-ray photoelectron spectroscopy, the fluorine compound is bonded to the surface of the base portion via a Ta-O-Si bond, and the Ta-O-Si bond is bonded to the surface of the base portion via a Ta-O-Si bond. When the ratio of the amount of fluorine atoms to the sum of the amount of carbon atoms, the amount of oxygen atoms, the amount of fluorine atoms, the amount of silicon atoms, and the amount of tantalum atoms is represented by F, F is 50 atm% or more.

Description

Technical Field

[0001] The present invention relates to an ink-repellent member and an inkjet head. Background Art

[0002] As a device for ejecting ink (hereinafter referred to as "inkjet head"), there are known a bubble jet (trademark) head that instantaneously evaporates ink by using a heater to fly droplets, a piezoelectric head that pushes droplets by using a piezoelectric element, and the like. In order to record high-quality images by using an inkjet head, it is necessary to eject ink droplets from ink ejection holes while maintaining their straightness in a predetermined direction. However, when droplet residues adhere to the surface of the orifice plate around the ejection holes, the ink droplets are dragged by the residues during the ejection of the ink droplets, resulting in deflection of the ejection direction. As a result, the ink droplets may fly out of the predetermined direction. In order to suppress the adhesion of droplet residues around the inkjet holes, an ink-repellent film is formed around the inkjet holes to provide an ink-repellent member.

[0003] For example, in Japanese Patent Application Laid-Open No. 2014-124879, it is disclosed that a base portion formed of an inorganic oxide is formed on the surface of the orifice plate, and a fluorine-containing silane coupling agent (hereinafter sometimes referred to as "fluorine compound") is chemically bonded thereto to form an ink-repellent member.

[0004] In addition, in an inkjet head, in order to remove droplet residues, paper powder, etc., the surface of the orifice plate is usually cleaned with a wiper or the like. Therefore, the ink-repellent member needs to have ink resistance and sliding resistance. Summary of the Invention

[0005] According to one aspect of the present invention, there is provided an ink-repellent member including a base portion containing tantalum oxide and having a fluorine compound bonded to the surface of the base portion via a Ta-O-Si bond, wherein after the ink-repellent member is subjected to the following impregnation treatments (1) and (2), when the ratio of the amount of fluorine atoms to the sum of the amounts of carbon atoms, oxygen atoms, fluorine atoms, silicon atoms, and tantalum atoms is represented by F in the measurement of the surface by X-ray photoelectron spectroscopy, F is 50 atm% or more: (Impregnation Treatment) (1) A specimen including the surface is cut out from the ink-repellent member, the specimen is placed in a sealable container containing a fluorine solvent containing a hydrofluoroether having a boiling point of 60°C or higher, and the specimen is immersed in the fluorine solvent so that the specimen is completely immersed therein; and (2) After the impregnation in (1), the specimen is held at 60°C for 4 hours in a sealed state.

[0006] In addition, according to one aspect of the present invention, there is provided a ink repellent member including a base portion containing tantalum oxide and having a fluorine compound bonded to the surface of the base portion via a Ta-O-Si bond, wherein the surface has a root mean square slope (Rdq) of 0.08 or less.

[0007] In addition, according to one aspect of the present invention, there is provided a method for manufacturing an ink repellent member including a base portion containing tantalum oxide and having a fluorine compound bonded to its surface via a Ta-O-Si bond, the method including the following steps (1) and (2): (1) performing plasma treatment on the surface of the base portion in an atmosphere having an oxygen concentration of 50 vol% or more; and (2) applying a fluorine compound having a reactive silyl group represented by the following formula (1) to the surface of the base portion that has undergone the plasma treatment in step (1), and then performing dehydration condensation: s*-Si(Y 1 ) n (OR) m (1) In formula (1), "n" and "m" each represent an integer from 0 to 3 and satisfy n + m = 3, and Y 1 each independently represents an alkyl group, a chloro group, or a bromo group, R each independently represents a hydrogen atom or an alkyl group, and "*" represents the bonding position in the fluorine compound.

[0008] In addition, according to one aspect of the present invention, there is provided an inkjet head including the above-described ink repellent member. In addition, according to another aspect of the present invention, there is provided a method for manufacturing an article including ejecting a liquid by using the above-described inkjet head, wherein the liquid is an ink containing a functional material for forming a functional thin film or a functional element.

[0009] Other features of the present invention will become clear from the following description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A is a top view of an inkjet head 100 according to an embodiment of the present invention.

[0011] Figure 1B is a bottom view of the inkjet head 100 according to an embodiment of the present invention.

[0012] Figure 1C is for explaining Figure 1A and Figure 1B a partial perspective view of a part of a cross-section taken along line A - A' shown in.

[0013] Figure 2AIt is a schematic diagram for explaining the state of the ink repellent member according to an embodiment of the present invention.

[0014] Figure 2B It is a schematic diagram for explaining the state of the ink repellent member in the prior art.

[0015] Figure 3 It is a coordinate graph showing the relationship between the treatment time and the ratio of the amount of fluorine atoms when the ink repellent member according to an embodiment of the present invention and the ink repellent member in the prior art are subjected to an impregnation treatment.

[0016] Figure 4A It is an image obtained by measuring the surface of the base portion without bonded fluorine in Example 1 with an atomic force microscope (AFM).

[0017] Figure 4B It is an image obtained by measuring the surface of the base portion of the ink repellent member in Example 1 with an AFM.

[0018] Figure 4C It is an image obtained by measuring the surface of the base portion without bonded fluorine in Comparative Example 2 with an AFM.

[0019] Figure 4D It is an image obtained by measuring the surface of the base portion of the ink repellent member in Comparative Example 2 with an AFM. Detailed Description

[0020] When a fluorine-containing silane coupling agent is bonded, silica is usually used for the base portion, but tantalum oxide is used to exhibit liquid resistance, as shown in Japanese Patent Application Laid-Open No. 2014-124879.

[0021] However, it is known that the Ta-O bond formed when the silane coupling agent is bonded to tantalum oxide has a smaller covalent bond nature (larger ionic bond nature) compared to the Si-O bond formed when silica is used for the base portion ("Journal of The Surface Finishing Society of Japan", The Surface Finishing Society of Japan, 1998, Vol. 49, No. 2, pp. 191-194). In view of the above, the inventors of the present invention have found that there are problems: the reactivity between the base portion and the silane coupling agent is reduced, and the ability of the ink repellent member is reduced due to long-term ink contact and sliding.

[0022] Therefore, even when tantalum oxide is used for the underlying portion, an ink repellent member having excellent sliding resistance and ink resistance is required.

[0023] The ink-repellent member, inkjet head, etc. according to the embodiments of the present invention will be described below with reference to the accompanying drawings. For example, in the following, the terms "ink repellency" and "ink-repellent member" are described, but in the case of aqueous ink, they can be understood as "water repellency" and "water-repellent member". In addition, when implementing the present invention, it is not necessarily required to limit the type and application of the liquid. Therefore, in the following description, the terms "ink repellency" and "ink-repellent member" can be understood as "liquid repellency" or "liquid-repellent member". The embodiments described below are examples. For example, those skilled in the art can appropriately change and implement the detailed configuration without departing from the spirit of the present invention.

[0024] In the drawings referred to in the following description of the embodiments and examples, elements having the same reference numerals have the same functions unless otherwise specified. In addition, the description of the numerical range "XX or more and YY or less" or "XX to YY" means a numerical range including XX (lower limit) and YY (upper limit) as endpoints unless otherwise specified. When the numerical range is described in segments, the upper and lower limits of each numerical range can be arbitrarily combined.

[0025] In this document, the liquid to be operated may be described as "ink", but the ink is not limited to the liquid for forming characters or images. For example, the ink may be a liquid containing a functional material for forming a functional thin film (such as an electrode or a filter) or a functional element (such as an organic EL element).

[0026] The ink-repellent member according to the present invention is an ink-repellent member including a base portion containing tantalum oxide and having a fluorine compound bonded to the surface of the base portion via a Ta-O-Si bond. After the ink-repellent member undergoes the following impregnation treatments (1) and (2), when the ratio of the amount of fluorine atoms to the sum of the amounts of carbon atoms, oxygen atoms, fluorine atoms, silicon atoms, and tantalum atoms in the surface of the base portion (the surface of the ink-repellent member) measured by X-ray photoelectron spectroscopy is represented by F, F is 50 atm% or more.

[0027] (Impregnation treatment) (1) Cut out a specimen including the surface of the base portion (the surface of the ink-repellent member) from the ink-repellent member, place the specimen in a sealable container containing a fluorine solvent containing a hydrofluoroether having a boiling point of 60 °C or higher, and immerse the specimen in the fluorine solvent so that the specimen is completely immersed therein. (2) After the impregnation in (1), keep the specimen at 60 °C for 4 hours in a sealed state.

[0028] As used herein, the term "ink-repellent member" refers to a member including a base portion having a surface to which a fluorine compound is chemically bonded (including a base portion having a fluorine compound chemically bonded to its surface).

[0029] The inventors of the present invention have repeatedly conducted research to obtain an ink-repellent member that can maintain excellent ink resistance and sliding resistance for a long period of time even when tantalum oxide is used for the base portion. As a result, the inventors of the present invention have found that the above object can be achieved by subjecting tantalum oxide to plasma treatment in an oxygen atmosphere and then bonding a fluorine compound to the tantalum oxide.

[0030] Tantalum oxide has high surface activity, so hydrocarbons in the air are easily adsorbed onto the surface of tantalum oxide. Therefore, in order to form hydroxyl groups (hydroxyl groups) as reactive groups on the surface of the base portion, it seems preferable to treat the surface in an argon atmosphere having a large atomic radius and high collision energy. However, as a result of extensive research conducted by the inventors, it has been found that a larger amount of hydroxyl groups are formed by plasma treatment in an oxygen atmosphere. In addition, it has been found that after plasma treatment in an oxygen atmosphere, the surface slope of the base portion surface is gentle. Since the amount of hydroxyl groups is large, the bonding amount of the fluorine compound in the base portion increases. In addition, since the slope is gentle, the fluorine compound is effectively arranged in terms of wiping without being buried in the recesses of the surface. It is considered that with this configuration, an ink-repellent member having excellent ink resistance and sliding resistance can be achieved.

[0031] (Inkjet head) First, an inkjet head according to an embodiment of the present invention may be an inkjet head including the ink-repellent member according to the present invention. The configuration of the inkjet head according to this embodiment will be described below. Figure 1A is a top view of the inkjet head 100 according to this embodiment. Figure 1B is a bottom view of the inkjet head 100. In addition, Figure 1C is for showing along Figure 1A and Figure 1B a partial perspective view of a part of a cross section taken along the line A-A' shown in.

[0032] The inkjet head 100 may include: a first flow path substrate 1 serving as a first member, a second flow path substrate 2 serving as a second member, an adhesive layer 3, ejection holes 4, ejection energy generating elements 5, an orifice plate 6 (ink-repellent member), electrodes 7, and an ink tank chamber. Figures 1A to 1C The ink tank chamber is not shown in. In addition, among the constituent elements of the inkjet head, elements not directly related to the description of the present invention (for example, circuits and wirings) are not shown.

[0033] The group of the first flow path substrate 1 and the second flow path substrate 2, the group of the first flow path substrate 1 and the orifice plate 6, and the group of the second flow path substrate 2 and the ink tank chamber are all joined by the adhesive layer 3 to be integrated with each other to form a flow path structure. In this flow path structure, a first through flow path 8 and a second through flow path 9 are formed and made to communicate with each other to form an ink supply path. In Figure 1C for the sake of easy explanation, only a part of the adhesive layer 3 is shown.

[0034] The ink is supplied from the ink tank chamber to the liquid flow path 10 through the second through-flow path 9 formed in each of the second flow path substrate 2 and the first flow path substrate 1, and is ejected from the ejection hole 4 after the ejection energy generating element 5 gives ejection energy. The ink that is not ejected from the ejection hole 4 flows back to the ink tank chamber through the first through-flow path 8 formed in the first flow path substrate 1 and the third through-flow path 19 (circulation return path) formed in the second flow path substrate 2.

[0035] Although a plurality of ejection holes 4 are arranged in the orifice plate 6, the arrangement method (number and position) of the ejection holes 4 is not limited to the illustrated example. On the outer surface of the orifice plate 6, that is, on the orifice surface 6a which is the surface on the side opposite to the liquid flow path 10, a fluorine compound is bonded to the surface of the base portion described later. On the first flow path substrate 1, the ejection energy generating element 5 for ejecting the liquid is arranged at positions corresponding to the respective ejection holes 4, and the ejection energy generating element 5 is driven in response to an electric signal transmitted from the outside via the electrode 7. For example, a heat-electric conversion element or a piezoelectric element is suitable as the ejection energy generating element 5. Silicon is suitable as the material to be used for the substrate of the orifice plate 6, but in addition to silicon, silicon carbide, silicon nitride, various glasses (such as quartz glass and borosilicate glass), various ceramics (such as alumina and gallium arsenide), and resins (such as polyimide) can also be used as the material. In the present embodiment, the orifice plate is formed of a liquid-repellent member, but the inkjet head itself can be formed of a liquid-repellent member.

[0036] (Base portion) For example, to be arranged on Figures 1A to 1C The base portion on the outer surface (orifice surface 6a) of the illustrated orifice plate 6 can be formed to contain an inorganic oxide. The base portion has hydroxyl groups formed on its surface, and thus can form a chemical bond with a fluorine compound (fluorine-containing silane coupling agent) having a reactive silyl group. By forming a chemical bond, the adhesion between the base portion and the fluorine compound can be improved. The base portion can be formed as a base film or a base layer on the substrate. However, when the substrate itself (bulk material) is formed to contain an inorganic oxide, the substrate itself can be used as the base portion.

[0037] In the present invention, the base portion contains tantalum oxide as the inorganic oxide. Tantalum oxide forms compounds each having an oxidation number of +2 to +5. Among them, tantalum pentoxide is preferred from the viewpoint of being able to form a large amount of hydroxyl groups as reaction sites. In addition to tantalum oxide, the base portion may also contain oxide materials such as silicon oxide, zirconium oxide, alumina, titanium oxide, hafnium oxide, cerium oxide, tungsten oxide, niobium oxide, and yttrium oxide.

[0038] As the base portion containing tantalum oxide, for example, a base film can be formed on a substrate (e.g., silicon) by sputtering, ion-assisted vapor deposition, atomic layer deposition (ALD), or the like. Among these, from the perspective of being able to form a high-density film, the ALD method is preferably used. When the density is high, the ink tolerance for alkaline ink is further improved.

[0039] When forming a base film on a substrate as the base portion, silicon is usually used as the substrate for the lower layer of the base film. In this case, from the perspective of protecting silicon from the influence of ink, the thickness of the base film is preferably 10 nm or more, more preferably 50 nm or more. In addition, from the perspective of suppressing cohesive failure during sliding, the thickness is preferably 300 nm or less, more preferably 200 nm or less.

[0040] (Surface treatment of the base portion) A method for manufacturing a ink-repellent member according to an embodiment of the present invention can be a method for manufacturing an ink-repellent member including a base portion containing tantalum oxide and having a fluorine compound bonded to the surface of the base portion via a Ta-O-Si bond, the method including the following steps (1) and (2): (1) Plasma-treating the surface of the base portion without the bonded fluorine compound in an atmosphere with an oxygen concentration of 50 vol% or more; and (2) Applying a fluorine compound having a reactive silyl group represented by the following formula (1) to the surface of the base portion that has undergone the plasma treatment in step (1), and then performing dehydration condensation: *-Si(Y 1 ) n (OR) m (1) In formula (1), "n" and "m" each represent an integer from 0 to 3 and satisfy n + m = 3, Y 1 each independently represents an alkyl group, a chloro group, or a bromo group, R each independently represents a hydrogen atom or an alkyl group, and "*" represents the bonding position in the fluorine compound.

[0041] In the present invention, the surface treatment of the base portion is preferably performed by plasma treatment in an oxygen atmosphere. As a result of research conducted by the inventors of the present invention, it has been found that even when the surface of the base portion is treated in an atmosphere of either oxygen or argon, the contact angle after treatment becomes low (e.g., a static contact angle of <5°), however, compared with the treatment in an argon atmosphere, a larger amount of hydroxyl groups can be formed by the treatment in an oxygen atmosphere.

[0042] To study this mechanism, the surface after plasma treatment was measured by X-ray photoelectron spectroscopy (XPS), and the ratio of +1 to +5 valences was calculated from the analysis of Ta 4f. As a result, it was recognized that the ratio of the +5 valence decreased in the case of treatment in an argon atmosphere (95% before treatment and 85% after treatment). At the same time, in the case of treatment in an oxygen atmosphere, no decrease in the ratio of the +5 valence was found. Therefore, it is inferred that when tantalum oxide is subjected to plasma treatment, a large amount of hydroxyl groups can be formed by treatment in an oxygen atmosphere.

[0043] For example, when plasma treatment is performed in a mixed atmosphere of oxygen and another gas (e.g., argon), the oxygen concentration is preferably 50 vol% or more, more preferably 75 vol% or more, and even more preferably 80 vol% or more. This treatment can be performed in an atmosphere containing only oxygen (oxygen concentration is 100 vol%). When the oxygen concentration is 50 vol% or more, hydroxyl groups are sufficiently formed.

[0044] In addition, a bias voltage can be applied to perform the treatment by accelerating the plasma generated during the treatment. As a result, the surface treatment is accelerated, and hydroxyl groups can be further formed.

[0045] By treating the surface of the base with a fluorine-containing low-molecular-weight silane coupling agent and measuring the amount of fluorine atoms by X-ray photoelectron spectroscopy, the amount of hydroxyl groups on the surface of the base after plasma treatment can be quantified. In this case, the ratio of the amount of fluorine atoms is calculated, and the amount of hydroxyl groups can be evaluated in the same manner as in the evaluation of the bonding amount of the fluorine compound described later based on the calculated value.

[0046] In addition, the surface profile of the base after plasma treatment was analyzed. As a result, it was found that the arithmetic mean roughness (Ra) did not change with the atmosphere, but the surface slope (root mean square slope Rdq) became gentle when plasma treatment was performed in an oxygen atmosphere compared to the case of treatment in an argon atmosphere. The detailed reason for this is not clear, but it is speculated that when the active substances generated in an oxygen atmosphere react with tantalum oxide, the tantalum oxide undergoes surface treatment in a uniform and gentle manner so that the surface is not roughened.

[0047] Figure 2A is a schematic diagram for explaining the state of the ink-repellent member according to an embodiment of the present invention. Figure 2BIt is a schematic diagram for explaining the state of the ink-repellent member in the prior art. In the ink-repellent member 21 according to the present embodiment, a fluorine compound is chemically bonded to the surface 23 of the base portion 22. It is considered that in the case where the surface slope is gentle, when the fluorine compound is chemically bonded to the base portion, the fluorine compound can be bonded at a position and an angle where the fluorine compound does not bury into the recesses on the surface. As a result, a state that effectively exhibits sliding resistance for wiping can be achieved. Meanwhile, in the prior art, the fluorine compound is chemically bonded to the surface 33 of the base portion 32 in the ink-repellent member 31, but the slope is steeper than that of the ink-repellent member 21. As a result, the fluorine compound is likely to bury into the recesses on the surface, and the bonding amount of the fluorine compound is also small.

[0048] Rdq is a value obtained by evaluating the magnitude of the local inclination angle and quantifying the steepness of the surface unevenness. For example, Rdq can be calculated by measuring the surface with an atomic force microscope (AFM).

[0049] The ink-repellent member according to an embodiment of the present invention may be an ink-repellent member including a base portion containing tantalum oxide and having a fluorine compound bonded to the surface of the base portion via a Ta-O-Si bond, wherein the root mean square slope (Rdq) of the surface of the base portion (ink-repellent member surface) is 0.08 or less.

[0050] The Rdq of the surface of the base portion to which the fluorine compound is bonded is preferably 0.08 or less, more preferably 0.07 or less. Since the sliding resistance is improved, the Rdq is preferably 0.08 or less.

[0051] In the case of using tantalum oxide as the base portion, when plasma treatment is performed in an oxygen atmosphere, the amount of hydroxyl groups as reactive groups can be increased, and a state in which the effect can be easily exhibited can be achieved without burying the fluorine compound into the recesses. Therefore, an ink-repellent member excellent in ink resistance and sliding resistance can be achieved.

[0052] (fluorine compound) The fluorine compound for the ink-repellent member has a linear main chain structure, and one end on both sides of the main chain forms a chemical bond (Ta-O-Si) with the hydroxyl group on the surface of tantalum oxide of the base portion. The fluorine compound for manufacturing the ink-repellent member to form a Ta-O-Si bond has at least one reactive silyl group represented by the following formula (1). When the fluorine compound has a reactive silyl group at one of its ends, the reaction between fluorine compound molecules can be inhibited. *-Si(Y 1 ) n (OR) m (1)

[0053] In formula (1), "n" and "m" each represent an integer from 0 to 3, and satisfy n + m = 3. For example, "m" can represent 3 and "n" can represent 0. Y 1 each independently represents an alkyl group, a chlorine group or a bromine group. Each R independently represents a hydrogen atom or an alkyl group. Preferably, Y 1 each represents a methyl group. When Y 1 has a small number of carbon atoms, it is easy to suppress the reduction in reactivity caused by steric hindrance. Preferably, each R represents a methyl group because the hydrolysis of the fluorine compound becomes faster, and thus the reaction becomes faster.

[0054] In addition, the fluorine compound preferably has a perfluoromethyl structure (perfluoromethyl group) at the other end. The perfluoromethyl structure has a small surface free energy and thus can exhibit high ink repellency.

[0055] From the viewpoint of ensuring ink repellency and sliding resistance, the main chain structure of the fluorine compound preferably has a perfluoropolyether (hereinafter sometimes referred to as "PFPE") structure.

[0056] That is, the preferred structure of the fluorine compound to be used for manufacturing the ink repellent member can be represented by the following formula (10). F3C-R 2 -R 1 (10)

[0057] In formula (10), R 1 represents a reactive silyl group represented by formula (1), and R 2 represents a structure having a perfluoropolyether structure.

[0058] The fluorine compound preferably has at least one of the following structures as the PFPE structure: a repeating structure represented by the following formula (2), a repeating structure represented by the following formula (3), a repeating structure represented by the following formula (4), and a repeating structure represented by the following formula (5).

[0059] In formulas (2), (3), (4) and (5), n1, n2, n3 and n4 each independently represent an integer of 1 or more.

[0060] Preferred specific examples of the fluorine compound include a compound represented by the following formula (6), a compound represented by the following formula (7), a compound represented by the following formula (8), and a compound represented by the following formula (9): In formula (6), s1, t1, and u1 each independently represent an integer of 1 or more; In formula (7), s2 and t2 each independently represent an integer of 1 or more; In formula (8), s3 represents an integer of 1 or more; and In formula (9), s4, t4, and u4 each independently represent an integer of 1 or more. The fluorine compound in the ink repellent member is preferably a fluorine compound having a main chain with a perfluoropolyether structure and having a perfluoromethyl group at its end. That is, in a state where the fluorine compound is chemically bonded to the surface of the base portion via a Ta-O-Si bond, the preferred structure of the fluorine compound can be represented by the following formula (11): F3C-R 2 -R 3 -* (11) In formula (11), R 2 represents a structure having a perfluoropolyether structure, R 3 represents an Si-O bond, the fluorine compound is chemically bonded to the surface of the base portion via a Ta-O-Si bond containing an Si-O bond, and "*" represents the bonding position to the tantalum atom.

[0062] The number average molecular weight of the fluorine compound is preferably 4000 or more. For example, the number average molecular weight of the fluorine compound can be calculated by 19 19F-NMR measurement based on the integration ratio relative to the perfluoromethyl group (CF3 group) at the end.

[0063] (Method for manufacturing the ink repellent member) Subsequently, a method for bonding a fluorine compound to the surface of a base portion containing tantalum oxide will be described. The fluorine compound can be bonded by a silane coupling treatment. Examples thereof will be described below.

[0064] First, for example, a base portion, which is a base film containing tantalum oxide, is formed on a substrate such as a well plate. An example of a method for forming tantalum oxide as the base film is a method for forming tantalum oxide by atomic layer deposition (ALD).

[0065] Next, hydroxyl groups are formed on the surface of the base portion by the above plasma treatment.

[0066] Next, the fluorine compound is applied to the surface of the base portion on which the hydroxyl groups are formed. There is no particular limitation on the application method, and examples thereof may include a vacuum vapor deposition method, a hot vapor deposition method, a spraying method, a spin coating method, and a dip coating method.

[0067] Subsequently, the alkoxysilyl or halosilyl group at the terminal of the fluorine compound is hydrolyzed to be converted into a silanol group (Si-OH group). Then, a dehydration condensation reaction is carried out between the silanol group of the fluorine compound and the hydroxyl group formed on the base portion to form a Ta-O-Si bond.

[0068] Hydrolysis is caused by exposure to moisture and also by adsorbed water present on the surface of the base portion. The dehydration condensation reaction can also occur at room temperature, but can be accelerated by increasing the temperature (e.g., from 100 °C to 120 °C). In particular, when the base portion is formed of tantalum oxide, the covalent bond nature of the Ta-O bond in the Ta-O-Si bond is small, and the reaction is less likely to occur. Therefore, in the reaction at room temperature, the reaction energy required for bonding is insufficient, and the reaction between fluorine compound molecules (Si-O-Si bond) can easily occur. In order to sufficiently increase the amount of bonding on the base portion of the fluorine compound, it is preferable to react the applied fluorine compound by heating at a high temperature to accelerate the bonding between the fluorine compound and the base portion. Specifically, for example, it is preferable to heat the applied fluorine compound to 100 °C or higher to cause dehydration condensation.

[0069] The reaction time can be appropriately selected according to the temperature. For example, it is about 10 hours at room temperature and about 1 hour under the condition of 120 °C.

[0070] Subsequently, the base portion is washed to remove the remaining unbonded fluorine compound. There is no particular limitation on the washing method. For example, it is only necessary to immerse the ink-repellent member in a fluorine solvent compatible with the fluorine compound. The base portion is washed to the extent that it can be visually recognized that no fluorine compound remains on the base portion.

[0071] The thickness of the fluorine compound is preferably 5 nm or more, more preferably 10 nm or more.

[0072] After drying the fluorine solvent, the bonding amount, ink resistance, and sliding resistance of the fluorine compound can be evaluated.

[0073] (Bonding amount of the fluorine compound) In the ink-repellent member according to an embodiment of the present invention, the ratio F of the amount of fluorine atoms measured as described below is 50 atm% (atomic percentage) or more. The ratio F of the amount of fluorine atoms corresponds to the bonding amount of the fluorine compound on the surface of the ink-repellent member. The surface (the surface of the base portion) of the ink-repellent member to which the fluorine compound is bonded is measured by X-ray photoelectron spectroscopy after the following impregnation treatments (1) and (2), and the ratio F of the amount of fluorine atoms to the sum of the amounts of carbon atoms, oxygen atoms, fluorine atoms, silicon atoms, and tantalum atoms is calculated.

[0074] (Impregnation treatment) (1) Cut out a test piece including the base surface from the ink-repellent member, place the test piece in a sealable container containing a fluorine solvent that contains a hydrofluoroether having a boiling point of 60 °C or higher, and immerse the test piece in the fluorine solvent so that the test piece is completely immersed therein. (2) After the immersion in (1), keep the test piece at 60 °C for 4 hours in a sealed state.

[0075] The XPS measurement conditions can be set as described below. Measurement device: Quantera II (product name), manufactured by ULVAC-PHI, Inc. X-ray source: AlKα Analysis area: φ200 μm Pass energy: 140 eV Number of scans: 10 Detection angle: 45° Elements to be detected: C, O, F, Si, Ta XPS peaks: C1s, O1s, F1s, Si2p, Ta4f

[0076] The hydrofluoroether is a compound formed by carbon atoms, fluorine atoms, hydrogen atoms, and an ether bond (-O-). The hydrofluoroether dissolves only fluorine compounds and has no corrosiveness. Therefore, by the above treatment, fluorine compounds that were not completely removed in the washing step can be removed, even though the fluorine compounds are not chemically bonded to the base surface. That is, by performing the above immersion treatment, only the fluorine compounds actually chemically bonded to the base surface can be quantified.

[0077] As an example, Figure 3 Shows the change in the ratio of the amount of fluorine atoms when the ink-repellent member according to an embodiment of the present invention used in Example 1 below and the prior art ink-repellent member used in Comparative Example 3 are each subjected to the above immersion treatment. The ratio of the amount of fluorine atoms is the ratio of the amount of fluorine atoms to the sum of the amounts of carbon atoms, oxygen atoms, fluorine atoms, silicon atoms, and tantalum atoms.

[0078] It can be understood that the ratio of the amount of fluorine atoms after the washing step (corresponding to Figure 3 the treatment time of 0 hours) is the same, but the ratio F of the prior art ink-repellent member decreases through the immersion treatment. At the same time, it can be understood that the ink-repellent member according to this embodiment manufactured in Example 1 maintains the ratio F for 4 hours during maintenance. The removal is completed through a treatment of 3 hours or more, so the evaluation can be made based on the treatment for 4 hours.

[0079] Unbonded fluorine compounds can also contribute to improving durability. Therefore, generally, unbonded fluorine compounds are actively used and not removed for practical purposes. However, unbonded fluorine compounds diffuse into the ink during contact with the ink, for example, and are removed over time. As a result, the base portion with low liquid repellency is exposed, leading to deterioration of the ink repellency function. Even if the ratio of the amount of fluorine atoms is the same before the above treatment, the amount bonded to the base portion actually changes due to the film-forming process. Therefore, an ink repellent member with excellent ink resistance can be obtained by achieving an ink repellent member with a large ratio of F after the above treatment.

[0080] The ratio F after the above dipping treatment is preferably 50 atm% or more, more preferably 52 atm% or more. When the ratio F is 50 atm% or more, the ink resistance becomes sufficient.

[0081] There is no particular limitation on the fluorine solvent containing hydrofluoroether to be used for the dipping treatment, and examples of commercially available products may include: Novec (trademark) 7200 (boiling point: 76°C, manufactured by 3M Company, structure: C4F9OC2H5), Sumitec Solvent 72 (boiling point: 76°C, manufactured by Sumitomo Mining Lubricants Co., Ltd.), and SOLBLE RN2000 (boiling point: 76°C, manufactured by Solvay Solexis S.p.A.) (each containing a compound having the same structure as Novec 7200 as the main component). The fluorine solvent containing hydrofluoroether may be hydrofluoroether itself (hydrofluoroether content: 100%).

[0082] (Manufacturing method of an article including an ink repellent member) The manufacturing method of an article according to an embodiment of the present invention is a manufacturing method of an article including ejecting a liquid with the above ink repellent member (e.g., an inkjet head), wherein the liquid is an ink containing a functional material for forming a functional thin film or a functional element. [Examples]

[0083] Specific examples and comparative examples are described below.

[0084] (Example 1) Tantalum pentoxide was laminated to 100 nm on a Φ3-inch silicon substrate using an ALD film-forming apparatus.

[0085] Next, the silicon substrate having tantalum pentoxide formed thereon as a base film was placed in the chamber of a plasma processing apparatus, and the surface of the base film was processed. Specifically, after evacuating the inside of the chamber, only oxygen was introduced. Then, plasma was generated, and a bias voltage was applied to accelerate the plasma (output power value: 120 W). This state was maintained for 300 seconds.

[0086] Subsequently, the silicon substrate with the processed basement membrane surface was placed in a vacuum vapor deposition machine, and a fluorine compound was vapor deposited on the surface on which the basement membrane was formed. A compound represented by the formula (6) with a number average molecular weight of 5000 was used as the fluorine compound. The vapor deposition was carried out in such a way that 160 mg of the fluorine compound in a state of being impregnated in steel wool was placed in a Cu container, and the fluorine compound was heated on a resistance boat.

[0087] Subsequently, the silicon substrate with the vapor deposited fluorine compound thereon was placed in an oven and left standing for 45 minutes in an environment of 120 °C.

[0088] Subsequently, the taken-out silicon substrate was washed by impregnating it in a fluorine solvent for 30 seconds so that the fluorine compound attached to the surface was removed. The washing was repeated twice using fresh fluorine solvent, and the solvent was dried. Thus, a ink repellent member with a fluorine compound bonded thereto was obtained.

[0089] (Examples 2 to 5 and Comparative Examples 1 to 3) The ink repellent members according to each example and comparative example were manufactured by the same method as in Example 1, except that the conditions for plasma treatment and dehydration condensation of the basement membrane were changed to the conditions shown in Table 1-1 and Table 1-2.

[0090] The evaluation methods for the base portions and the ink repellent members according to each example and comparative example are described below.

[0091] (Evaluation 1: Amount of hydroxyl groups on the base portion) Specimens (thickness: about 700 μm, size: about 2 cm on each side) including the base portion of tantalum pentoxide that had been subjected to plasma treatment (on which no fluorine compound was bonded) were cut out, and a vial containing (3,3,3-trifluoropropyl)dimethylchlorosilane (manufactured by Gelest) was placed in a PFA container. The specimens were immersed in (3,3,3-trifluoropropyl)dimethylchlorosilane. The container was sealed with a lid and left standing at 30 °C for 20 hours. The amount of hydroxyl groups was evaluated by the following means: the surface of the base portion in the taken-out specimens was measured by X-ray photoelectron spectroscopy (XPS); and the ratio of the amount of fluorine atoms to the sum of the amounts of carbon atoms, oxygen atoms, fluorine atoms, silicon atoms, and tantalum atoms was calculated.

[0092] XPS measurement conditions Measurement device: Quantera II (product name), manufactured by ULVAC-PHI X-ray source: AlKα Analysis area: φ200 μm Pass energy: 140 eV Number of scans: 10 Detection angle: 45° Elements to be detected: C, O, F, Si, Ta XPS peaks: C1s, O1s, F1s, Si2p, Ta4f

[0093] The amount of hydroxyl groups is evaluated based on the following criteria. A: The ratio of the amount of fluorine atoms is 5.0 atm% or more. B: The ratio of the amount of fluorine atoms is 4.0 atm% or more and less than 5.0 atm%. C: The ratio of the amount of fluorine atoms is 3.0 atm% or more and less than 4.0 atm%. D: The ratio of the amount of fluorine atoms is 2.0 atm% or more and less than 3.0 atm%. E: The ratio of the amount of fluorine atoms is less than 2.0 atm%.

[0094] When evaluating the amount of hydroxyl groups on the surface of the base portion where no fluorine compound is bonded in Example 1, the ratio of the amount of fluorine atoms is 5.2 atm%, and it is evaluated as A.

[0095] (Evaluation 2: Surface profiles (arithmetic mean roughness Ra and root mean square slope Rdq) of the base portion where no fluorine compound is bonded and the base portion of the ink repellent member The surface profiles of the base portion (where no fluorine compound is bonded) after plasma treatment and the surface of the base portion of the ink repellent member where a fluorine compound is bonded are measured using an atomic force microscope (L-Trace II, manufactured by Hitachi High-Technologies Corporation). SI-DF40 (manufactured by Hitachi High-Technologies Corporation) is used as the cantilever, and the measurement is performed in tapping mode. As Figure 4A 、 Figure 4B 、 Figure 4C and Figure 4D shown, a measurement area of 500 nm × 500 nm is divided into 256 blocks on the substrate surface in the x-direction and y-direction, respectively, and the height value Z(x, y) at each position is measured.

[0096] Ra and Rdq are calculated based on the method specified in JIS B0601.

[0097] The calculation method of Rdq is specifically described below. In Z(x, y), the local slope dZx,y / dx in the x-direction at a specific coordinate (x, y) can be expressed as follows using the seven-point formula.

[0098] In this case, when the number of data points in the x-direction and y-direction are represented by X and Y, respectively, it should be noted that since the seven-point formula is used, the values at x = 1, 2, 3, X - 2, X - 1, and X cannot be calculated.

[0099] Based on the above, the root mean square slope Rdq in the measurement region can be determined by the following equation.

[0100] The Rdq of the surface of the base of tantalum pentoxide (on which no fluorine compound is bonded) after the plasma treatment in Example 1 was measured to be Rdq = 0.055. In addition, in Example 1, the Rdq of the surface of the base of the ink-repellent member to which a fluorine compound is bonded is 0.055, which is not different from the Rdq of the base surface before bonding the fluorine compound. Figure 4A is an image showing the state when measuring the surface of the base (on which no fluorine compound is bonded) after the plasma treatment in Example 1 using AFM. Figure 4B is an image showing the state when measuring the surface of the base of the ink-repellent member to which a fluorine compound is bonded in Example 1 using AFM. Figure 4C is an image showing the state when measuring the surface of the base (on which no fluorine compound is bonded) after the plasma treatment in Comparative Example 2 using AFM. Figure 4D is an image showing the state when measuring the surface of the base of the ink-repellent member to which a fluorine compound is bonded in Comparative Example 2 using AFM.

[0101] (Evaluation 3: Ratio of the amount of fluorine atoms before the impregnation treatment to the amount of bonded fluorine compound after the impregnation treatment) For the surface of the base of the ink-repellent member to which a fluorine compound is bonded before the following impregnation treatment, the ratio of the amount of fluorine atoms (the ratio of the amount of fluorine atoms to the total amount of carbon atoms, oxygen atoms, fluorine atoms, silicon atoms, and tantalum atoms) is measured by X-ray photoelectron spectroscopy. In addition, for the surface of the base of the ink-repellent member after the following impregnation treatment, the ratio F (the ratio of the amount of fluorine atoms to the total amount of carbon atoms, oxygen atoms, fluorine atoms, silicon atoms, and tantalum atoms) is measured, and the amount of bonded fluorine compound is evaluated. In Example 1, the ratio of the amount of fluorine atoms on the surface side of the ink-repellent member before the impregnation treatment is 53.5 atm%. In addition, in Example 1, after the following impregnation treatment, the ratio F of the amount of fluorine atoms on the surface side of the ink-repellent member is 53.5 atm%.

[0102] (Impregnation treatment) (1) A specimen (thickness: about 700 μm, area: about 2 cm on each side) including the surface of the base of the ink-repellent member to which a fluorine compound is bonded is placed in a sealable container containing a hydrofluoroether (Novec 7200, boiling point: 76 °C, manufactured by 3M Company) with a boiling point of 60 °C or higher, and it is immersed in the hydrofluoroether so that the specimen is completely immersed therein. (2) Keep the test piece at 60 °C for 4 hours under a sealed condition.

[0103] XPS measurement conditions Measuring device: Quantera II (product name), manufactured by ULVAC-PHI, Inc. X-ray source: AlKα Analysis area: φ200 μm Pass energy: 140 eV Number of scans: 10 Detection angle: 45° Detected elements: C, O, F, Si, Ta XPS peaks: C1s, O1s, F1s, Si2p, Ta4f

[0104] (Evaluation 4: Evaluation of ink resistance) Evaluate the ink resistance of the ink-repellent member bonded with a fluorine compound thereon through the following procedure. Use an alkaline dye ink (BCI-7C, manufactured by Canon Inc.) as the ink. Put the ink into a PFA container. Immerse the ink-repellent member in the ink so that its entire surface is in contact with the ink, and seal the container with a lid. Put the container into an oven in this state and keep the temperature at 60 °C for 30 weeks. Take out the ink-repellent member and wash it thoroughly with water to remove the ink. Then, measure and evaluate the receding contact angle through the following method.

[0105] Use a contact angle meter (product name: DM-701, manufactured by Kyowa Interface Science Co., Ltd., analysis software: FAMAS (version 3.5.5)). The measurement conditions are as described below. · Droplet: 2 μL (pure water) · Receding contact angle: Calculate this angle by the sessile drop method.

[0106] Specifically measure the receding contact angle through the following method. Measure the contact angle at 80 points at intervals of 15 seconds after the droplet lands. By using the values of the contact angle and the contact radius (unit: μm) at a specific time calculated from the above software, perform the following calculations in the order starting from the 0-second time, and execute the following processes (A) and (B). (A) When the value of the contact radius at time "t" is represented by R t and the value of the contact radius 90 seconds after t is represented by R t+90 calculate the value "x" of (R t -R t+90 ) 2 . (B) When the value of "x" is 200 or less, process (A) is executed again, and the contact angle at the time "t" when the value of "x" first exceeds 200 is defined as the receding contact angle.

[0107] A: The receding contact angle is 100° or more. B: The receding contact angle is 95° or more and less than 100°. C: The receding contact angle is 90° or more and less than 95°. D: The receding contact angle is 85° or more and less than 90°. E: The receding contact angle is less than 85°.

[0108] (Evaluation 5: Evaluation of sliding resistance) The sliding resistance of the ink-repellent member having a fluorine compound bonded thereto is evaluated by the following procedure. A high-density felt material (CS-7, manufactured by Taber Industries) is attached to a friction and wear tester (FPR-2100, manufactured by Rhesca Co., Ltd.) as a sliding material, and a reciprocating sliding test is performed on the surface of the ink-repellent member. The reciprocating sliding test is performed under the following conditions: a sliding load of 650 g, a sliding width of 10 mm, a linear velocity of 50.8 mm / sec, and a sliding cycle number of 15,000. The receding contact angle of the surface of the ink-repellent member after sliding is measured and evaluated by the method described in Evaluation 4.

[0109] The technical parameters of the base films and ink-repellent members of Examples 1 to 5 and Comparative Examples 1 to 3 and the evaluation results of Evaluations 1, 2, and 3 are summarized in Table 1 below. Using the same equipment as that used in Evaluation 4 under the same conditions (droplet), the static contact angle of the base surface without fluorine bonded thereto after plasma treatment is measured, and the contact angle 1 second after the droplet lands is defined as the static contact angle.

[0110] Table 1-1

[0111] Table 1-2

[0112] The results of Evaluations 4 and 5 of the ink-repellent films of Examples 1 to 5 and Comparative Examples 1 to 3 are summarized in Table 2 below.

[0113] Table 2 Ink resistance Sliding resistance Example 1 A A Example 2 A A Example 3 B A Example 4 B B Example 5 C C Comparative Example 1 D D Comparative Example 2 D E Comparative Example 3 E E

[0114] In order to satisfy the practicality as a ink-repellent member, a contact angle of 90° or more is required. Therefore, it can be said that the ink-repellent members according to Embodiments 1 to 5 (whose ink resistance and sliding resistance are both evaluated as A to C) have more excellent practical characteristics than the ink-repellent members according to Comparative Examples 1 to 3.

[0115] According to the present invention, an ink-repellent member and an inkjet head excellent in both sliding resistance and ink resistance can be provided.

[0116] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the following claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. An ink repellent member comprising a base portion, the base portion comprising tantalum oxide, and having a fluorine compound bonded to a surface of the base portion via a Ta-O-Si bond, in, After the ink repellent member is subjected to the following immersion treatments (1) and (2), in measurement of the surface by X-ray photoelectron spectroscopy, when the ratio of the amount of fluorine atoms to the sum of the amount of carbon atoms, the amount of oxygen atoms, the amount of fluorine atoms, the amount of silicon atoms and the amount of tantalum atoms is represented by F, F is 50 atm% or more: (Immersion treatment) (1) cutting out a test piece including the surface from the ink repellent member, placing the test piece in a sealable container containing a fluorine solvent, the fluorine solvent containing a hydrofluoroether having a boiling point of 60° C. or higher, and immersing the test piece in the fluorine solvent so that the test piece is completely immersed therein; and (2) After the immersion in (1), the test piece was kept at 60° C. for 4 hours in a sealed state.

2. An ink repellent member comprising a base portion, the base portion comprising tantalum oxide, and having a fluorine compound bonded to a surface of the base portion via a Ta-O-Si bond, wherein the surface has a root mean square slope (Rdq) of less than 0.

08. The ink repellent member according to claim 1 , wherein the surface has a root mean square slope (Rdq) of 0.08 or less. 4 . The ink repellent member according to claim 1 , wherein the fluorine compound has a main chain having a perfluoropolyether structure and has a perfluoromethyl group at a terminal thereof.

5. The ink repellent member according to claim 1 or 2, wherein the fluorine compound has at least one structure represented by the following formula (2), the following formula (3), the following formula (4), and the following formula (5): In formulae (2), (3), (4) and (5), n1, n2, n3 and n4 each independently represent an integer of 1 or more. The ink repellent member according to claim 1 or 2, wherein the number average molecular weight of the fluorine compound is 4,000 or more. 7 . The ink repellent member according to claim 1 , further comprising a substrate, wherein the base portion is disposed on the substrate.

8. A method for manufacturing an ink repellent member, the ink repellent member comprising a base portion, the base portion comprising tantalum oxide and having a fluorine compound bonded to a surface of the base portion via a Ta-O-Si bond, the method comprising the following steps (1) and (2): (1) subjecting the surface of the base portion to plasma treatment in an atmosphere having an oxygen concentration of 50% by volume or more; and (2) applying a fluorine compound having a reactive silyl group represented by the following formula (1) to the surface of the base portion subjected to the plasma treatment in step (1), followed by dehydration condensation: *-Si(Y 1 ) n (OR) m (1) In formula (1), "n" and "m" each represent an integer from 0 to 3, and satisfy n+m=3, Y 1 Each independently represents an alkyl group, a chloro group or a bromo group, each R independently represents a hydrogen atom or an alkyl group, and "*" represents a bonding position in the fluorine compound.

9. The method for manufacturing an ink repellent member according to claim 8, wherein: In the step (2), the applied fluorine compound is heated to 100° C. or higher to perform dehydration condensation.

10. The method for producing an ink repellent member according to claim 8 or 9, wherein: In the step (1), the oxygen concentration is 75% by volume or more. 11 . An inkjet head comprising the ink repellent member according to claim 1 .

12. A method for manufacturing an article, comprising ejecting liquid by using the inkjet head according to claim 11, The liquid is an ink containing a functional material for forming a functional film or a functional element.

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