Coating fluid for forming porous film, and porous film

Abstract

The purpose of the present invention is to provide: a coating fluid for forming a porous film having excellent film strength; and a member including the porous film. The coating fluid is characterized by comprising inorganic oxide particles, an inorganic-binder composition, and a sulfonyl compound, wherein the sulfonyl compound is represented by formula 1 or formula 2. (R1 and R2 are organic groups and R1 and / or R2 is a group including a conjugated structure, the conjugated structure being directly bonded to the S atom.) (In formula 2, R3 to R6 are each a hydrogen atom or any group.)

Description

Coating liquid for forming porous film and porous film

[0001] The present disclosure relates to a coating liquid, a porous film, a member, an optical instrument, an imaging device, and a method for manufacturing a member.

[0002] Porous membranes contain many voids and have a large surface area, and therefore may exhibit properties such as adsorption, moisture absorption, antifouling, hydrophilicity / oleophilicity, water / oil repellency, and antifogging. For this reason, porous membranes are used in a wide range of fields, including ion exchange filters, gas sensors, optical components, and building materials.

[0003] However, while porous films have various properties as described above, their structure often results in insufficient strength and poor durability. In particular, strength is required for porous films to be used in applications requiring wear resistance and scratch resistance, such as outdoor optical components and building materials. Therefore, it is necessary to provide porous films with excellent strength. To solve this problem, Patent Document 1 discloses that the number of acidic functional groups in the acid added to the porous film coating solution is increased, thereby increasing the number of bonding points between particles in the porous film and improving the strength of the porous film.

[0004] Japanese Patent Application Laid-Open No. 2022-54404

[0005] In the coating solution of Patent Document 1, the acid has high reactivity, which causes particle aggregation and reduces particle dispersibility, potentially resulting in poor coatability of the porous film. This problem can sometimes be resolved by using a fluorine-containing acid to improve particle dispersibility. However, from an environmental perspective, the use of fluorine-containing acid may be restricted by law in the future. Therefore, it is an issue to provide a coating solution that reduces the amount of fluorine acid used while suppressing particle aggregation and reduced dispersibility.

[0006] The present disclosure has been made in view of the above-mentioned problems, and provides a coating liquid that uses a material with low environmental impact and forms a porous film with excellent film strength.

[0007] That is, the present disclosure provides a coating fluid comprising inorganic oxide particles, an inorganic binder composition, and a sulfonyl compound, wherein the sulfonyl compound is represented by Formula 1 or Formula 2. (In formula 1, n is an integer of 0 or more, and when n=0, R １ , R ２ is an organic group, and R １ , R ２ At least one of R is a group containing a conjugated structure, and the conjugated structure is directly bonded to the S atom, and when n≧1, R １ , R ２ is an organic group, and R ｘ are each independently １ , all R ｘ , and R ２ At least one of the groups is a group containing a conjugated structure, and the conjugated structure is directly bonded to any of the S atoms. (In formula 2, R ３ ~R ６ is a hydrogen atom or any group.

[0008] The present disclosure also provides a porous film having excellent film strength, which is coated using a material with low environmental impact. That is, the present disclosure provides a porous film comprising inorganic oxide particles, an inorganic binder, and a sulfonyl compound, wherein the inorganic oxide particles are bound to each other by the inorganic binder, and the sulfonyl compound is represented by Formula 1 or Formula 2.

[0009] According to the present disclosure, it is possible to provide a coating liquid that suppresses particle aggregation and a decrease in dispersibility, forms a porous film with excellent strength, and reduces the amount of fluorine acid used, thereby reducing the burden on the environment. Furthermore, according to the present disclosure, it is possible to provide a porous film with low environmental impact and excellent film strength, as well as a component, optical equipment, and imaging device. Furthermore, according to the present disclosure, it is possible to provide a method for manufacturing a component with reduced environmental impact, thereby reducing the amount of fluorine acid used.

[0010] FIG. 1 is a schematic diagram showing an embodiment of a coating liquid according to the present disclosure. FIG. 2 is a schematic diagram showing an embodiment of a porous membrane according to the present disclosure. FIG. 3 is a schematic diagram showing an embodiment of a member having a porous membrane on a flat-surface substrate. FIG. 4 is a schematic diagram showing an embodiment of a member having a porous membrane on a textured surface substrate. FIG. 5 is a schematic diagram showing an embodiment of a member having an adhesive intermediate layer between a substrate and a porous membrane. FIG. 6 is a schematic diagram showing an embodiment of a member having a mixed intermediate layer between a substrate and a porous membrane. FIG. 7 is a schematic diagram showing an embodiment of a member having an uneven intermediate layer between a substrate and a porous membrane. FIG. 8 is a diagram illustrating a method for manufacturing a member according to the present disclosure. FIG. 9 is a schematic diagram showing an example configuration of an imaging device equipped with a lens barrel (interchangeable lens) as an optical device using a member according to the present disclosure.

[0011] [Coating Liquid] A coating liquid refers to a liquid to be applied to a member or the like, and coating a film refers to applying a coating liquid and, if necessary, forming a film through an appropriate process.

[0012] One embodiment of a coating fluid according to the present disclosure is shown in Figure 1. The coating fluid 10 contains inorganic oxide particles 11, an inorganic binder composition 120, and a sulfonyl compound 14 represented by Formula 1 or Formula 2, and the inorganic oxide particles 11 are dispersed in a solvent 130.

[0013] Many of the inorganic oxide particles 11 in the coating liquid 10 have their surfaces modified with the sulfonyl compound 14 and are uniformly dispersed in the coating liquid. The coating liquid of the present disclosure may contain components other than the inorganic oxide particles 11, the inorganic binder composition 120, and the sulfonyl compound 14. Furthermore, in addition to the sulfonyl compound 14, the coating liquid may contain a component that modifies the surface of the inorganic oxide 11.

[0014] The film strength of the porous film formed by applying the coating liquid 10 is affected by the dispersion state of the inorganic oxide particles 11 in the coating liquid 10 .

[0015] For example, when a coating liquid in which the inorganic oxide particles 11 are uniformly dispersed is applied, the inorganic oxide particles 11 are stacked with high alignment to form a dense film. The densely formed film is bound by an inorganic binder, resulting in a porous film with high strength. On the other hand, when a coating liquid 10 in which the inorganic oxide particles 11 are unevenly dispersed is applied, the inorganic oxide particles are stacked in an aggregated state to form a film with many gaps. As a result, the strength of the coated porous film is reduced.

[0016] Therefore, in order to obtain a porous film having excellent film strength, it is desirable that the inorganic oxide particles 11 in the coating liquid 10 be in a state where they are highly dispersible.

[0017] (Sulfonyl Compound) In the present disclosure, a sulfonyl compound is a compound represented by SO ２ The sulfonyl compound contained in the coating liquid of the present disclosure is represented by the above formula 1 or 2.

[0018] The coating liquid may contain at least one sulfonyl compound represented by Formula 1 or Formula 2, and the sulfonyl compound contained in the coating liquid may be one type of sulfonyl compound or a combination of multiple sulfonyl compounds. The coating liquid may also contain a sulfonyl compound other than the sulfonyl compound represented by Formula 1 or Formula 2, or another organic acid, and may also contain a fluorine acid.

[0019] The sulfonyl compound contained in the coating liquid of the present disclosure is represented by the following formula 1 or 2. (In formula 1, n is an integer of 0 or more, and when n=0, R １ , R ２ is an organic group, and R １ , R ２ At least one of R is a group containing a conjugated structure, and the conjugated structure is directly bonded to the S atom, and when n≧1, R １ , R ２ is an organic group, and R ｘ are each independently １ , all R ｘ , and R ２At least one of the groups is a group containing a conjugated structure, and the conjugated structure is directly bonded to any of the S atoms. (In formula 2, R ３ ~R ６ is a hydrogen atom or any group.) A sulfonyl compound satisfying Formula 1 is a compound containing a sulfonyl group, S(=O) ２ modifies the surface of the inorganic oxide particles, and R １ , R Ｘ , R ２ The solvent affinity of the organic group can enhance the dispersibility of inorganic oxide particles in a solvent. In this case, if a conjugated system is bonded to the sulfonyl group, the acidity of the sulfonyl compound is significantly increased due to the resonance effect of the conjugated system, and the sulfonyl compound's surface modification ability for inorganic oxide particles is enhanced. As a result, the sulfonyl compound can impart strong dispersibility to inorganic oxides.

[0020] In formula 1, n is preferably an integer of 0 or more and 3 or less. If the molecular weight of the sulfonyl compound is too large, the repulsive action due to steric hindrance between inorganic oxide particles becomes too large during coating of the porous film, which reduces the number of bonding points of the inorganic binder, and the film strength of the porous film may be reduced.

[0021] Sulfonyl compounds satisfying Formula 2 are those containing a sulfonyl group, S(=O) ２ modifies the surface of inorganic oxide particles, and the solvent affinity of the hydroxyl group can enhance the dispersibility of inorganic oxide particles in solvents. In this case, if at least one of the ortho positions relative to the S atom of the benzene ring directly bonded to the sulfonyl group is an amino group, the acidity of the sulfonyl compound is significantly increased due to the resonance effect of the base, and the sulfonyl compound's surface modifying ability on inorganic oxide particles is enhanced. As a result, the sulfonyl compound can impart strong dispersibility to inorganic oxides.

[0022] The acid dissociation constant pKa of the sulfonyl compound represented by Formula 1 or Formula 2 is preferably −1.2 or more and 2.0 or less. If the acid dissociation constant is smaller than −1.2, the alignment of the inorganic oxide particles may be deteriorated during coating of the porous film, and if it is larger than 2.0, the dispersibility of the inorganic oxide particles in the coating liquid may be deteriorated, resulting in a decrease in the film strength of the coated porous film.

[0023] (Regarding the sulfonyl compound represented by formula 1) The sulfonyl compound represented by formula 1 will be further explained. Formula 1 is represented as follows. (In formula 1, n is an integer of 0 or more, and when n=0, R １ , R ２ is an organic group, and R １ , R ２ At least one of R is a group containing a conjugated structure, and the conjugated structure is directly bonded to the S atom, and when n≧1, R １ , R ２ is an organic group, and R ｘ are each independently １ , all R ｘ , and R ２ At least one of the above is a group containing a conjugated structure, and the conjugated structure is directly bonded to one of the S atoms.) The organic group is a group containing carbon atoms and hydrogen atoms, and examples of the organic group in Formula 1 include the following: (i) a substituted or unsubstituted chain hydrocarbon group having from 1 to 20 carbon atoms, which may contain a multiple bond; (ii) a substituted or unsubstituted aromatic hydrocarbon group (including monocyclic, polycyclic, and fused polycyclic) having from 6 to 30 carbon atoms, which may contain a multiple bond; and (iii) a substituted or unsubstituted heterocyclic group (including monocyclic, polycyclic, and fused polycyclic) having from 5 to 30 carbon atoms, which may contain a multiple bond, and which contains any atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.

[0024] When substituted, the substituent is not particularly limited, but preferred examples include an alkyl group, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, and a halogen atom.

[0025] The conjugated structure refers to a structure in which single bonds and multiple bonds are alternately located, and may contain a heteroatom. In the sulfonyl compound represented by Formula 1, the conjugated structure preferably contains 2 to 8 multiple bonds.

[0026] When the number of multiple bonds contained in the conjugated structure is 8 or less, there is no risk that the conjugated structure will absorb light in the visible wavelength range and cause coloring of the porous film. However, if the appearance of the member or light absorption is not an issue, this does not apply, and the number of multiple bonds may exceed 8. The multiple bonds are preferably carbon-carbon double bonds.

[0027] Examples of groups containing a conjugated structure in Formula 1 include the following: (i) a substituted or unsubstituted chain hydrocarbon group containing two or more multiple bonds and having from 1 to 20 carbon atoms; (ii) a substituted or unsubstituted aromatic hydrocarbon group (including monocyclic, polycyclic, and fused polycyclic) containing from 6 to 30 carbon atoms; and (iii) a substituted or unsubstituted heterocyclic group (including monocyclic, polycyclic, and fused polycyclic) containing two or more multiple bonds and having from 5 to 30 carbon atoms and containing any atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.

[0028] When substituted, the substituent is not particularly limited, but preferred examples include an alkyl group, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, and a halogen atom.

[0029] Examples of the group containing a conjugated structure include groups represented by the following formulas 101 to 105. (In formula 101, R １０１ ~R １０５ are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. * indicates the bonding position to the S atom. When formula 101 represents a divalent group, any atom in the formula can be replaced with a second bonding position.

[0030] (R in formula 102 ２０１ ~R ２０４ are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. * indicates the bonding position to the S atom. When formula 102 represents a divalent group, any atom in the formula can be replaced with a second bonding position.

[0031] (R in formula 103 ３０１ ~R ３０４ are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. * indicates the bonding position to the S atom. When formula 103 represents a divalent group, any atom in the formula can be replaced with a second bonding position.

[0032] (R in formula 104 ４００ is NH, an oxygen atom, or a sulfur atom, and R ４０１ ~R ４０４ are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. * indicates the bonding position to the S atom. When formula 104 represents a divalent group, any atom in the formula can be replaced with a second bonding position.

[0033] (R in formula 105 ５００ is NH, an oxygen atom, or a sulfur atom, and R５０１ ~R ５０５ are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. * indicates the bonding position to the S atom. When formula 105 represents a divalent group, any atom in the formula can be replaced with a second bonding position.

[0034] Among these, the group containing a conjugated structure is preferably a group represented by formula 101 or a group represented by formula 103, and more preferably a group represented by formula 101. This is because when the conjugated structure contains an aromatic ring, the resonance structure of the conjugated system is stabilized, and the acidity of the sulfonyl group in the sulfonyl compound is increased.

[0035] The sulfonyl compound represented by Formula 1 is not limited as long as it satisfies the above requirements. Examples of the sulfonyl compound include 4-(methylsulfonyl)aniline, 2-(isopropylsulfonyl)aniline, and 2-aminophenyl phenyl sulfone. Sulfone), 1,4-diamino-2,5-bis(methylsulfonyl)benzene, 1-(phenylsulfonyl)pyrrole, dibenzenesulfonimide, and 4-methyl-N-tosylbenzenesulfonamide. All of the above are commercially available.

[0036] 4-(methylsulfonyl)aniline is represented by formula 1001. That is, in formula 1, n=0 and R １ is a methyl group which is an organic group, and R ２is an organic group and a group containing a conjugated structure, and is represented by formula 101, and R １０３ is an amino group, R １０１ , R １０２ , R １０４ , R １０５ are groups each containing a hydrogen atom.

[0037] 2-(Isopropylsulfonyl)aniline is represented by formula 1002. That is, in formula 1, n=0 and R １ is an organic group, 1-methylethyl group, and R ２ is an organic group and a group containing a conjugated structure, and is represented by formula 101, and R １０１ is an amino group, R １０２ , R １０３ , R １０４ , R １０５ are groups each containing a hydrogen atom.

[0038] 2-aminophenyl phenyl sulfone is represented by formula 1003. That is, in formula 1, n=0 and R １ is an organic group and a group containing a conjugated structure, and is represented by formula 101, and R １０１ ~R １０５ are both hydrogen atoms, and R ２ is an organic group and a group containing a conjugated structure, and is represented by formula 101, and R １０１ is an amino group, R １０２ , R １０３ , R １０４ , R １０５ are groups each containing a hydrogen atom.

[0039] 1,4-Diamino-2,5-bis(methylsulfonyl)benzene is represented by formula 1004. That is, it is represented by formula 1, n=1, and R １ is a methyl group which is an organic group, Rx is an organic group and a group containing a conjugated structure, and is represented by formula 101, and R １０１ and R １０４ Amino group, R １０３ is a bond group, and R ２ is a methyl group, which is an organic group.

[0040] 1-(phenylsulfonyl)pyrrole is represented by formula 1005. That is, it is represented by formula 1, n=0, and R １ is an organic group and a group containing a conjugated structure, and is represented by formula 103, and R ３０１ ~R ３０４ is a hydrogen group, and R ２ is an organic group and a group containing a conjugated structure, and is represented by formula 101, and R １０１ ~R １０５ are groups in which all are hydrogen atoms.

[0041] Dibenzenesulfonimide is represented by formula 1006. That is, it is represented by formula 1, n=1, Rx is a divalent amino group, and R １ , R ２ are both organic groups and groups containing a conjugated structure, and are represented by formula 101, and R １０１ ~R １０５ is a group that is a hydrogen atom.

[0042] 4-methyl-N-tosylbenzenesulfonamide is represented by formula 1007. That is, it is represented by formula 1, n=1, Rx is a divalent amino group, and R １ , R ２ are both organic groups and groups containing a conjugated structure, and are represented by formula 101, and R １０３ is a methyl group, and R １０１ , R １０２ , R １０４ , and R １０５ is a group that is a hydrogen atom.

[0043] (Regarding the sulfonyl compound represented by formula 2) The sulfonyl compound represented by formula 2 will be further explained. Formula 2 is represented as follows. (In formula 2, R ３ ~R ６ is a hydrogen atom or any group.

[0044] More preferably, R ３ ~R ６are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom.

[0045] The sulfonyl compound represented by formula 2 is not limited as long as it satisfies the above conditions, but examples include p-anisidine-2-sulfonic acid and 2-amino-3,5-dimethylbenzenesulfonic acid, all of which are commercially available.

[0046] p-Anisidine-2-sulfonic acid is represented by formula 201. That is, in formula 2, R ３ , R ５ and R ６ is a hydrogen atom, R ４ corresponds to a compound which is an alkoxy group having one carbon atom.

[0047] 2-Amino-3,5-dimethylbenzenesulfonic acid is represented by formula 202. That is, in formula 2, R ３ and R ５ is a hydrogen atom, R ４ and R ６ All of these correspond to compounds in which the alkyl group has one carbon atom.

[0048] The coating liquid may contain at least one sulfonyl compound represented by Formula 1 or Formula 2, and the coating liquid may contain one type of sulfonyl compound or a combination of multiple sulfonyl compounds.

[0049] The sulfonyl compound contained in the coating liquid can be identified directly by spectroscopic analysis such as Fourier transform infrared spectroscopy or microscopic Raman spectroscopy, or by gas chromatography mass spectrometry, or by fragment analysis.

[0050] As explained above, the sulfonyl compound represented by formula 1 has a sulfonyl group that modifies the surface of inorganic oxide particles, and R １ , R ２ The solvent affinity of the organic group in Formula 2 can enhance the dispersibility of inorganic oxide particles in a solvent. In addition, the sulfonyl compound represented by Formula 2 can modify the surface of inorganic oxide particles with the sulfonyl group, and can enhance the dispersibility of inorganic oxide particles in a solvent with the solvent affinity of the hydroxyl group. When the acidity of the sulfonyl compound is sufficiently high, the sulfonyl compound has a high surface modification ability for inorganic oxide particles, and the sulfonyl compound further improves the dispersibility of inorganic oxide.

[0051] Therefore, the acid dissociation constant pKa of the sulfonyl compound represented by Formula 1 or Formula 2 is preferably -1.2 or more and 2.0 or less. When the acid dissociation constant is 2.0 or less, the inorganic oxide particles have sufficiently good dispersibility in the coating liquid. Furthermore, when the acid dissociation constant is -1.2 or more, the inorganic oxide particles have good alignment when the coating liquid is applied.

[0052] The content of the sulfonyl compound is preferably 0.05 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of inorganic oxide particles in the coating liquid. When it is 0.05 parts by mass or more, the dispersibility of the inorganic oxide particles is sufficient, and the film strength of the porous film is sufficiently high. When it is 10 parts by mass or less, the concentration of the sulfonyl compound in the coating liquid is sufficiently low, and there is no risk of interfering with the bonding of the inorganic oxide particles by the inorganic binder in the coated porous film.

[0053] (Inorganic Oxide Particles) Inorganic oxide particles are particles formed of an inorganic oxide. The inorganic oxide is not particularly limited, but examples thereof include metal oxides such as silicon oxide, alumina, titania, zirconia, antimony oxide, tin oxide, tantalum oxide, zinc oxide, cerium oxide, lead oxide, and indium oxide; metal nitrides such as silicon nitride, titanium nitride, and aluminum nitride; metal carbides such as silicon carbide and titanium carbide; metal sulfides such as zinc sulfide; metal carbonates such as calcium carbonate and magnesium carbonate; metal sulfates such as calcium sulfate and magnesium sulfate; metal silicates such as calcium silicate and magnesium silicate; metal phosphates such as calcium phosphate; metal borates such as aluminum borate and magnesium borate, and composites thereof. The inorganic oxide particles may form a salt. The inorganic oxide particles may be composed of a single composition or multiple compositions. Furthermore, the inorganic oxide particles may be used alone or in combination of two or more types.

[0054] The inorganic oxide particles contained in the coating liquid are preferably those having hydroxyl groups on their surfaces, since the hydroxyl groups can be bonded with a sulfonyl compound or an inorganic binder composition. Examples of inorganic oxide particles having hydroxyl groups include silicon oxide particles, titanium oxide particles, alumina particles, and zirconia particles. All of these are commercially available. In particular, silicon oxide particles are widely available and are a preferred example of inorganic oxide particles.

[0055] The composition of the inorganic oxide particles can be analyzed and identified using energy dispersive X-ray fluorescence analysis (EDX).

[0056] Examples of the shape of the inorganic oxide particles include spherical, cocoon-shaped, bale-shaped, disk-shaped, rod-shaped, needle-shaped, angular, and chain-shaped. In order to increase the film strength while maintaining porosity, it is preferable to include inorganic oxide particles with a shape that increases the packing rate of the inorganic oxide particles, for example, spherical. Furthermore, it is preferable to include chain-shaped inorganic oxide particles, as this can prevent film cracking during firing.

[0057] The inorganic oxide particles contained in the coating liquid may have one or more different shapes, and may have shapes other than spherical, cocoon-shaped, bale-shaped, disk-shaped, rod-shaped, needle-shaped, angular, and chain-shaped.

[0058] The inorganic oxide particles may be either solid or hollow inorganic oxide particles. Solid inorganic oxide particles are preferred because they can further increase the film strength of the porous film. Hollow inorganic oxide particles refer to inorganic oxide particles that are hollow inside, while solid inorganic oxide particles refer to inorganic oxide particles that are not hollow. The inorganic oxide particles contained in the coating liquid may be either solid inorganic oxide particles or hollow inorganic oxide particles, or may contain both. Hollow inorganic oxide particles can lower the refractive index of a porous film containing the particles by the air (refractive index 1.0) contained in the pores.

[0059] Chain inorganic oxide particles are secondary particles formed by connecting a plurality of primary particles in a straight or curved manner. The size of the chain inorganic oxide particles can be expressed by the minor axis and the major axis.

[0060] The minor axis of the chain inorganic oxide particles corresponds to the thickness of the chain inorganic oxide particles, in other words, the average particle diameter of one primary particle. The minor axis of the chain inorganic oxide particles can be calculated from the specific surface area obtained by nitrogen adsorption method for the chain inorganic oxide particles extracted from the coating liquid.

[0061] The average minor axis of the chain-like inorganic oxide particles is preferably 8 nm or more and 20 nm or less. When the minor axis is 8 nm or more, the surface area of ​​the inorganic oxide particles is not too large, and when coated, the porous film does not absorb excessive moisture or chemicals from the atmosphere, which may reduce the porosity of the film. Furthermore, when the average minor axis is 20 nm or less, dispersion in the solvent is stable, and there is no risk of deterioration in coatability.

[0062] The major axis of the chain inorganic oxide particles corresponds to the thickness of the chain inorganic oxide particles, in other words, the length of the secondary particles, and can be determined by dynamic light scattering.

[0063] The major axis of the chain inorganic oxide particles is preferably 4 to 8 times the minor axis. When the major axis is 4 or more times the minor axis, the film does not become too dense and the porosity can be sufficiently exhibited, and when it is 8 or less, there is no risk of deterioration in coating properties and leveling properties, or of the coated porous film scattering light.

[0064] The ratio of the major axis to the minor axis of the chain inorganic oxide particles can be measured and calculated using a scanning electron microscope.

[0065] The average particle size of the primary particles of the hollow inorganic oxide particles is preferably 15 nm or more and 300 nm or less, more preferably 30 nm or more and 80 nm or less. When the average particle size is 15 nm or more, the particles can be produced stably. When the average particle size is 300 nm or less, large voids are less likely to occur between particles, and the applied porous film is less likely to cause light scattering. The shell thickness of the hollow particles is 10% or more and 50% or less, preferably 20% or more and 35% or less, of the average particle size. When the shell thickness is 10% or more, the strength of the particles themselves is sufficient. When the shell thickness is 50% or less, light scattering is less likely to occur.

[0066] Furthermore, the average particle size of the primary particles of inorganic oxide particles that are not hollow inorganic oxide particles is preferably 5 nm or more and 80 nm or less. When the average particle size is 5 nm or more, the surface area of ​​the inorganic oxide particles is not too large, and when applied, there is no risk that the porous film will absorb excessive moisture or chemicals from the atmosphere, resulting in a decrease in the porosity of the film. Furthermore, when the average particle size is 80 nm or less, there is no risk that the coating property or leveling property will deteriorate, or that the applied porous film will scatter light.

[0067] The average particle size of inorganic oxide particles can be the average Feret diameter. The average Feret diameter can be measured by image processing of a transmission electron microscope image of a plurality of inorganic oxide particles contained in a coating liquid. As an image processing method, a commercially available image processing software such as ImageProPLUS (manufactured by Media Cybernetics) can be used. In a predetermined image area, the contrast is appropriately adjusted as necessary, and the Feret diameter of each particle is measured by particle measurement, and the average value of the plurality of particles is calculated.

[0068] The inorganic oxide particles may be surface-treated. By treating the surfaces of the inorganic oxide particles, desired film properties such as adsorptivity, hygroscopicity, antifouling properties, hydrophilicity / oleophilicity, water / oil repellency, and antifogging properties can be obtained. For example, by making the surfaces of the inorganic oxide particles hydrophilic, the coated porous film exhibits effects such as hydrophilicity, antifogging properties, antifouling properties, and hygroscopicity.

[0069] (Inorganic binder composition) The coating liquid of the present disclosure contains an inorganic binder composition. In this specification, the inorganic binder before binding may be referred to as the inorganic binder composition to distinguish it from the inorganic binder after binding.

[0070] The inorganic binder composition can be used without any particular limitation as long as it can bind inorganic oxide particles together. Preferably, the inorganic binder composition contains an inorganic material of the same nature as the inorganic oxide particles. By containing an inorganic material of the same nature as the inorganic oxide particles, the affinity between the materials is increased, so that the inorganic oxide particles can be strongly bound together when coating a porous film. For example, when silicon oxide particles are used as the inorganic oxide particles, the inorganic binder composition preferably contains a silicon oxide compound.

[0071] Inorganic binder compositions include monomeric silicon oxide compounds, oligomeric silicon oxide compounds, and polymeric silicon oxide compounds.

[0072] The monomeric silicon oxide compound can be represented by formula 300, where R ３００ are each independently an alkyl group or other functional group.

[0073]

[0074] In the monomeric silicon oxide compound, R ３００ Preferred examples of the group include a methyl group, an ethyl group, a propyl group, and a butyl group. These groups bond with other Si groups through hydrolysis and condensation reactions to form a three-dimensional structure, thus forming a siloxane polymer structure.

[0075] The oligomeric silicon oxide compounds and polymeric silicon oxide compounds are oligomers or polymers composed of units represented by the following formulas 301 to 304. In any of formulas 301 to 304, R ３００each independently represents an alkyl group or other functional group, and * represents another unit of Si, another unit of alkyl group, another unit of functional group, or a bond with a hydrogen atom. Oligomeric silicon oxide compounds consist of 3 to 15 of these units. Polymeric silicon oxide compounds have 16 or more of these units.

[0076] In oligomeric silicon oxide compounds and polymeric silicon oxide compounds, most of the * groups bond with other units of Si, other units of alkyl groups, and other units of functional groups through hydrolysis, condensation, dehydration condensation, etc., to form a three-dimensional structure, forming a siloxane polymer structure.

[0077] The inorganic binder composition is preferably an oligomeric silicon oxide compound having 3 to 15 units of the above-mentioned unit, i.e., a trimer to 15-mer. When the inorganic binder composition is a trimer or more, there are sufficient binding points of the inorganic binder when coating a porous film, and the inorganic oxide particles are sufficiently bound together, resulting in a coated porous film with high strength. On the other hand, when the inorganic binder composition is a 15-mer or less, the molecular weight is not too large, and no inorganic binder layer is formed between the inorganic oxide particles when coating a porous film, resulting in a coated porous film with high strength.

[0078] An example of an oligomeric silicon oxide compound is an alkyl silicate represented by formula 305: Si ｎ O ｎ－１ (O-R ３０５ ) ２ｎ＋２ Formula 305 (R ３０５ is an alkyl group having 1 to 5 carbon atoms, and n is an integer of 3 to 15) ３０５ Alternatively, a plurality of different n's may be mixed.

[0079] Examples of such oligomeric silicon oxide compounds include methyl silicate having an average trimer to 15-mer, methyl silicate having an average trimer to 15-mer, and a mixture of ethyl silicate having an average trimer to 15-mer and methyl silicate having an average trimer to 15-mer, all of which are commercially available.

[0080] The composition of the inorganic binder composition or the inorganic binder can be analyzed and identified using energy dispersive X-ray fluorescence analysis (EDX). In addition, the condensation rate of the inorganic binder can be determined using a nuclear magnetic resonance spectrometer.

[0081] The content of the inorganic binder composition in the coating liquid is preferably 0.1 to 40 parts by mass relative to 100 parts by mass of the inorganic oxide particles contained in the coating liquid. When the amount of the inorganic binder composition is 0.1 parts by mass or more, the coated porous film has sufficient film strength. When the amount is 40 parts by mass or less, there is no risk of the coated porous film losing its porosity.

[0082] (Solvent) The solvent for the coating liquid may be any solvent that does not cause the inorganic oxide particles to precipitate or the coating liquid to suddenly increase in viscosity. The coating liquid may preferably contain an organic solvent. Examples of organic solvents that the coating liquid may contain include the following:Methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methylpropanol, 1-pentanol, 2-pentanol, cyclopentanol, 2-methylbutanol, 3-methylbutanol, 1-hexanol, 2-hexanol, 3-hexanol, 4-methyl-2-pentanol, 2-methyl-1-pentanol, 2-ethylbutanol, 2,4-dimethyl-3-pentanol, 3-ethylbutanol, 1-heptanol, 2-heptanol, 1-octanol monohydric alcohols such as ethylene glycol and 2-octanol; dihydric or higher alcohols such as ethylene glycol and triethylene glycol; ether alcohols such as methoxyethanol, ethoxyethanol, propoxyethanol, isopropoxyethanol, butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, and 3-methoxy-1-butanol; dimethoxyethane, diglyme (diethylene glycol dimethyl ether), tetrahydrofuran, ethers such as hexane, dioxane, diisopropyl ether, dibutyl ether, and cyclopentyl methyl ether; esters such as ethyl formate, ethyl acetate, n-butyl acetate, methyl lactate, ethyl lactate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, and propylene glycol monomethyl ether acetate; various aliphatic or alicyclic hydrocarbons such as n-hexane, n-octane, cyclohexane, cyclopentane, and cyclooctane; various aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; various ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; various chlorinated hydrocarbons such as chloroform, methylene chloride, carbon tetrachloride, and tetrachloroethane; and aprotic polar solvents such as N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and ethylene carbonate. The coating liquid may contain only one of these solvents, or may contain a mixture of two or more of these solvents.

[0083] From the viewpoint of dispersibility of inorganic oxide particles, the solvent contained in the coating liquid preferably contains a polar solvent. Among these, it is particularly preferable to contain at least one solvent selected from ethoxyethanol, propoxyethanol, isopropoxyethanol, butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, ethyl lactate, and 3-methoxy-1-butanol. In addition to the polar solvent, the coating liquid may contain a poor solvent or water.

[0084] The method for storing the coating liquid is not particularly limited as long as it has sufficient resistance to solvents and the like, and may be a resin container, a glass bottle, or, for example, a drum or a spray can.

[0085] [Porous Membrane] The present disclosure provides a porous membrane comprising inorganic oxide particles, an inorganic binder, and a sulfonyl compound, wherein the inorganic oxide particles are bound to each other by the inorganic binder, and the sulfonyl compound is represented by Formula 1 or Formula 2.

[0086] 2 is a schematic diagram showing one embodiment of a porous film 1 according to the present disclosure. The porous film 1 is composed of a skeleton made of inorganic oxide particles 11 and a plurality of voids 13 present between the skeleton and the inorganic oxide particles 11, which are bound to one another by an inorganic binder 12. The inorganic binder 12 is formed by binding an inorganic binder composition 120.

[0087] The strength of the porous film 1 is controlled by the alignment of the inorganic oxide particles 11 and the binding strength of the inorganic binder 12. The porous film 1 also contains a sulfonyl compound 14 represented by Formula 1 or Formula 2.

[0088] The film strength of the porous film 1 is preferably an indentation strength of 0.8 GPa or more and 2.0 GPa or less. If the indentation strength is 0.8 GPa or more, the film strength is sufficient and high durability is obtained, and if it is 2.0 GPa or less, the stress of the porous film is not too high and film cracking does not occur over time.

[0089] The amount of voids 13 in the porous film 1 can be calculated by measuring the refractive index of the porous film 1. When the porous film 1 is in air, the refractive index of the porous film will be a value between the refractive index of air and the refractive index of the material that makes up the porous film, and the more voids 13 there are, the smaller the refractive index. For example, when the inorganic oxide particles 11 and the inorganic binder 12 are both silicon oxide, the refractive index of the porous film 1 is greater than 1.00 and less than 1.46. If the porous film 1 has too many voids 13, the film strength of the porous film 1 will be reduced. If the refractive index of the porous film 1 is 1.20 or more and 1.46 or less, the film strength will be sufficiently high.

[0090] [Member containing porous membrane] The present disclosure provides a member having a substrate and the above-described porous membrane 1 provided on the substrate. Figures 3A and 3B are schematic diagrams showing one example of a member 2 containing the porous membrane 1 according to the present disclosure. In the member 2 containing the porous membrane 1, the porous membrane 1 is disposed on a substrate 20. The material of the substrate 20 can be glass, ceramics, resin, metal, or the like. Furthermore, the shape of the substrate is not limited, and may be a curved shape having a flat, concave, or convex surface, a film, or the like.

[0091] The surface shape of the substrate 20 is not particularly limited, and may be, for example, a flat substrate 20a as shown in Fig. 3A or a rough substrate 20b as shown in Fig. 3B. By using a rough substrate 20b as the substrate, the adhesion between the porous membrane 1 and the substrate 20 can be improved.

[0092] The composition of the glass or ceramic is not particularly limited. Examples include zirconium oxide, titanium oxide, tantalum oxide, niobium oxide, hafnium oxide, lanthanum oxide, gadolinium oxide, silicon oxide, calcium oxide, barium oxide, sodium oxide, potassium oxide, boron oxide, and aluminum oxide. The substrate 20 can be produced by grinding and polishing, molding, float forming, or the like.

[0093] The resin is preferably a thermoplastic resin or a thermosetting resin. Examples of the thermoplastic resin include PET polyethylene terephthalate, PEN (polyethylene naphthalate), PP (polypropylene), PMMA (polymethyl methacrylate, acrylic resin), triacetyl cellulose, PC (polycarbonate), cycloolefin polymer, and polyvinyl alcohol. Examples of the thermosetting resin include polyimide, epoxy resin, and urethane resin. The metal may be a metal composed of one type of metal element or an alloy containing two or more types of elements.

[0094] As shown in FIGS. 4A to 4C, the member 2 may also have an intermediate layer 30 between the porous membrane 1 and the substrate 20. The provision of the intermediate layer 30 can prevent the diffusion of impurities from the substrate and improve adhesion between the porous membrane 1 and the substrate 20. Examples of the intermediate layer 30 include an inorganic oxide layer such as an oxide or nitride, and an organic compound layer such as a polymer. The intermediate layer 30 may be a single layer made of the above-mentioned material, or a laminate of multiple layers. The intermediate layer 30 may be an adhesive intermediate layer 30a that bonds with the porous membrane 1 as shown in FIG. 4A, a mixed intermediate layer 30b that includes the porous membrane 1 as shown in FIG. 4B, or an uneven intermediate layer 30c with an uneven surface as shown in FIG. 4C.

[0095] The member 2 is not limited and may be any type of member, but examples include lenses, parts of optical devices such as security cameras and video cameras, and building materials.

[0096] [Method for manufacturing a member] The present disclosure provides a method for manufacturing a member, which includes a step of applying the above-described coating liquid onto a substrate, and a step of drying and / or baking the substrate coated with the coating liquid.

[0097] That is, the manufacturing method of the member 2 of the present disclosure includes, as shown in FIG. 5, a step S5001 of applying a coating liquid onto a substrate 20, and a step S5002 of drying and / or baking the substrate 20 to which the coating liquid 10 has been applied.

[0098] In step S5001, methods for applying the coating liquid to the substrate 20 include spin coating, blade coating, roll coating, slit coating, printing, gravure coating, and dip coating. When manufacturing a component having a complex three-dimensional shape such as a concave or convex surface, spin coating is preferred, as it is easy to apply the coating with a uniform thickness. When manufacturing a large-area component having a three-dimensional shape such as an uneven surface, spray coating is preferred.

[0099] In step S5002, the solvent in the coating liquid is removed, and the inorganic oxide particles are bound without disturbing their alignment, thereby obtaining the porous film 1. In step S5002, for example, the drying and / or baking temperature can be set taking into account the heat resistance temperature of the substrate 10. For example, if the substrate 10 is an inorganic compound substrate, it is preferably treated at 20°C or higher and 800°C or lower, and more preferably at 20°C or higher and 200°C or lower. If the substrate 10 is an organic compound substrate, it is preferably treated at 20°C or higher and 200°C or lower. The drying and / or curing time may be any time that does not affect the substrate 10 and is long enough to remove the organic solvent from the layer, but is preferably 5 minutes to 200 hours, and more preferably 30 minutes to 24 hours.

[0100] (Optical Apparatus) The present disclosure provides an optical apparatus including a housing and an optical system including a plurality of lenses provided in the housing, at least one of the plurality of lenses being the above-described member.

[0101] An example of the configuration of an imaging device equipped with a lens barrel (interchangeable lens) as an optical device using a member according to the present disclosure is shown in Fig. 6. Fig. 6 shows an example of a single-lens reflex digital camera to which the lens barrel (interchangeable lens) is coupled.

[0102] In this disclosure, optical equipment refers to equipment equipped with an optical system, such as binoculars, microscopes, semiconductor exposure apparatuses, and interchangeable lenses.

[0103] Furthermore, the imaging device in this disclosure refers to an electronic device equipped with an imaging element that receives light that has passed through an optical element, such as a camera system such as a digital still camera or a digital video camera, or a mobile phone. Note that the imaging device may also be in the form of a module mounted on an electronic device, such as a camera module.

[0104] 6, the imaging device 200 includes a camera body 202 and a lens barrel 201, which is an optical device. The dashed-dotted line indicates the optical path. The camera body 202 and the lens barrel 201 are connected, but the lens barrel 201 is a so-called interchangeable lens that can be attached to and detached from the camera body 202. A cap 250 can be attached to the lens barrel 201 when not taking pictures.

[0105] Light from a subject passes through an optical system including multiple lenses 203 and 205 arranged on the optical axis of the imaging optical system within the housing 220 of the lens barrel 201, and is received by the image sensor. The member according to the present disclosure can also be used as a lens that constitutes the optical system.

[0106] The lens 205 is supported by an inner barrel 204 and is supported movably relative to the outer barrel of the lens barrel 201 for focusing and zooming.

[0107] During the observation period before shooting, light from the subject is reflected by a main mirror 207 inside the camera body housing 221, passes through a prism 211, and then is projected to the photographer through a viewfinder lens 212 as a captured image. The main mirror 207 is, for example, a half mirror, and light transmitted through the main mirror 207 is reflected by a sub-mirror 208 toward an AF (autofocus) unit 213. This reflected light is used, for example, for distance measurement. The main mirror 207 is attached and supported by a main mirror holder 240, for example, by adhesive. During shooting, a drive mechanism (not shown) moves the main mirror 207 and sub-mirror 208 out of the optical path, opens a shutter 209, and focuses a captured light image incident from the lens barrel 201 onto an image sensor 210. The aperture 206 is configured so that the brightness and depth of focus during shooting can be changed by changing the aperture area.

[0108] By using a member according to the present disclosure as a lens that constitutes an optical system, reflection and scattering in the optical system are suppressed, and an excellent image can be obtained.

[0109] The components disclosed herein can be used not only for optical components such as prisms, lenses, and mirrors, but also for hydrophilic coatings on windshields and side mirrors of vehicles such as cars and trains, and anti-fouling coatings on solar panels.

[0110] In the examples, a porous film-forming coating solution was prepared by the following method, and a porous film was formed on a substrate to produce a member having a porous film. The obtained porous film was evaluated as follows.

[0111] <Evaluation of porous film strength> A porous film was formed on the polished surface of a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side) with a film thickness of approximately 400 nm to 500 nm. Wax was applied to a sample stage prepared in advance, and the glass substrate was attached on top with the porous film-coated surface facing up. After confirming that the wax had sufficiently dried, the indentation strength of the porous film was measured using a nanoindenter (NanoIndenter G-200, manufactured by Agilent Technologies). A DCM head was used to measure the indentation strength, and measurements were taken at multiple locations per sample, with the average value being the measured value. The evaluation depth was set to 150 nm to 300 nm because if it was too shallow, it would be affected by the surface roughness of the porous film, and if it was too deep, it could be affected by the strength of the substrate itself.

[0112] <Evaluation of refractive index and porosity of porous film> A porous film was formed on the polished surface of a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side). Using a spectroscopic ellipsometer (VASE manufactured by J.A. Woollam Japan), light was incident on the porous film, and the reflected light was measured at wavelengths from 380 nm to 800 nm to calculate the refractive index. The refractive index at a wavelength of 550 nm was evaluated, and the porosity of the porous film was calculated.

[0113] <Contact angle of porous film> Pure water was dropped onto the surface of the porous film, and the contact angle of the pure water was measured at room temperature of 22° C. and humidity of 40 to 45% RH. The contact angle was measured by taking an image 1000 ms after the pure water was dropped.

[0114] Example 1 18.67 g of 2-propanol, 0.04 g of dibenzenesulfonimide, and 6.00 g of pure water were added to 7.84 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solid content concentration 51% by mass), and the mixture was stirred at 37.5° C. for 6 hours to prepare a silica sol solution.

[0115] Next, 133.33 g of a 2-propanol dispersion of spherical silicon oxide particles (IPA-ST manufactured by Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 30 mass%) and 334.12 g of 2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0116] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm.The film was then dried at 22°C for 10 hours to obtain a member having a porous film.

[0117] Evaluation of the porous film revealed that the film strength was 1.65 GPa, the refractive index was 1.351, the porosity was 24%, and the contact angle was 8.6°.

[0118] Example 2 18.67 g of 2-propanol, 0.04 g of dibenzenesulfonimide, and 6.00 g of pure water were added to 7.84 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solid content concentration 51% by mass), and the mixture was stirred at 37.5° C. for 6 hours to prepare a silica sol solution.

[0119] Next, 66.67 g of a 2-propanol dispersion of spherical silicon oxide particles (IPA-ST manufactured by Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 30 mass%), 128.21 g of a 2-propanol dispersion of chain silicon oxide particles (IPA-ST-UP manufactured by Nissan Chemical Industries, Ltd., average minor axis 12 nm, solid content concentration 15.6 mass%), and 272.58 g of 2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0120] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm.The film was then dried at 22°C for 10 hours to obtain a member having a porous film.

[0121] Evaluation of the porous film revealed that the film strength was 1.26 GPa, the refractive index was 1.330, the porosity was 28%, and the contact angle was 8.4°.

[0122] Example 3 15.69 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solid content concentration 51% by mass) was mixed with 37.33 g of 1-ethoxy-2-propanol, 0.08 g of dibenzenesulfonimide, and 12.00 g of pure water, and the mixture was stirred at 37.5° C. for 6 hours to prepare a silica sol solution.

[0123] Next, 100.00 g of a propylene glycol monomethyl ether dispersion of spherical silicon oxide particles (PGM-ST manufactured by Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 30 mass%), 64.10 g of a propylene glycol monomethyl ether dispersion of chain silicon oxide particles (PGM-ST-UP manufactured by Nissan Chemical Industries, Ltd., average minor axis 12 nm, solid content concentration 15.6 mass%), and 272.58 g of 1-ethoxy-2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0124] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm.The film was then dried at 22°C for 10 hours to obtain a member having a porous film.

[0125] Evaluation of the porous film revealed that the film strength was 1.42 GPa, the refractive index was 1.376, the porosity was 18%, and the contact angle was 10.6°.

[0126] Example 4 37.33 g of 2-propanol, 0.08 g of dibenzenesulfonimide, and 12.00 g of pure water were added to 15.69 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solid content concentration 51% by mass), and the mixture was stirred at 37.5° C. for 6 hours to prepare a silica sol solution.

[0127] Next, 100.00 g of a propylene glycol monomethyl ether dispersion of spherical silicon oxide particles (PGM-ST manufactured by Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 30 mass%), 64.10 g of a 2-propanol dispersion of chain silicon oxide particles (IPA-ST-UP manufactured by Nissan Chemical Industries, Ltd., average minor axis 12 nm, solid content concentration 15.6 mass%), and 272.58 g of 1-ethoxy-2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0128] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm.The film was then dried at 22°C for 10 hours to obtain a member having a porous film.

[0129] As a result of evaluating the porous film, the film strength was 1.40 GPa, the refractive index was 1.391, the porosity was 15%, and the contact angle was 9.0°.

[0130] Example 5 166.67 g of cellosolve acetate was added to the coating liquid obtained in Example 3, and the mixture was stirred at room temperature for 2 hours to obtain a coating liquid.

[0131] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm.The film was then dried at 22°C for 10 hours to obtain a member having a porous film.

[0132] Evaluation of the porous film revealed that the film strength was 1.39 GPa, the refractive index was 1.392, the porosity was 15%, and the contact angle was 7.9°.

[0133] Example 6 37.25 g of 2-propanol, 0.16 g of dibenzenesulfonimide, and 12.00 g of pure water were added to 15.69 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solid content concentration 51% by mass), and the mixture was stirred at 37.5° C. for 6 hours to prepare a silica sol solution.

[0134] Next, 100.00 g of a 2-propanol dispersion of spherical silicon oxide particles (IPA-ST manufactured by Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 30 mass%), 64.10 g of a 2-propanol dispersion of chain silicon oxide particles (IPA-ST-UP manufactured by Nissan Chemical Industries, Ltd., average minor axis 12 nm, solid content concentration 15.6 mass%), and 272.58 g of 2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0135] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm.The film was then dried at 22°C for 10 hours to obtain a member having a porous film.

[0136] Evaluation of the porous film revealed that the film strength was 1.35 GPa, the refractive index was 1.382, the porosity was 17%, and the contact angle was 10.4°.

[0137] Example 7 37.33 g of 2-propanol, 0.08 g of dibenzenesulfonimide, and 12.00 g of pure water were added to 15.69 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solid content concentration 51% by mass), and the mixture was stirred at 37.5° C. for 6 hours to prepare a silica sol solution.

[0138] Next, 100.00 g of a 2-propanol dispersion of spherical silicon oxide particles (IPA-ST manufactured by Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 30 mass%), 64.10 g of a 2-propanol dispersion of chain silicon oxide particles (IPA-ST-UP manufactured by Nissan Chemical Industries, Ltd., average minor axis 12 nm, solid content concentration 15.6 mass%), and 272.58 g of 2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0139] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating to a thickness of approximately 420 nm. The film was then cured at 700°C for 2 hours to obtain a member having a porous film.

[0140] Evaluation of the porous film revealed that the film strength was 1.40 GPa, the refractive index was 1.396, the porosity was 14%, and the contact angle was 10.9°.

[0141] Example 8 9.00 g of 2-propanol, 0.02 g of p-anisidine-2-sulfonic acid, and 3.60 g of pure water were added to 4.71 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solid content concentration 51% by mass), and the mixture was stirred at 37.5° C. for 6 hours to prepare a silica sol solution.

[0142] Next, 60.00 g of a 2-propanol dispersion of spherical silicon oxide particles (IPA-ST manufactured by Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 30 mass%), 38.50 g of a 2-propanol dispersion of chain silicon oxide particles (IPA-ST-UP manufactured by Nissan Chemical Industries, Ltd., average minor axis 12 nm, solid content concentration 15.6 mass%), 0.10 g of p-anisidine-2-sulfonic acid, and 180.00 g of 2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0143] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm.The film was then dried at 22°C for 10 hours to obtain a member having a porous film.

[0144] As a result of evaluating the porous film, the film strength was 1.42 GPa, the refractive index was 1.342, the porosity was 26%, and the contact angle was 8.5°.

[0145] Example 9 To 9.42 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solid content concentration 51% by mass), 18.00 g of 2-propanol, 0.05 g of p-anisidine-2-sulfonic acid, and 7.2 g of pure water were added, and the mixture was stirred at 37.5°C for 6 hours to prepare a silica sol solution.

[0146] Next, 117.0 g of a 2-propanol dispersion of hollow silicon oxide particles (Sururia 1110, manufactured by JGC Catalysts and Chemicals Co., Ltd., average particle size 50 nm, solid content concentration 20.5 mass%), 0.10 g of p-anisidine-2-sulfonic acid, and 148.00 g of 2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0147] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm.The film was then dried at 22°C for 10 hours to obtain a member 2 having a porous film.

[0148] Evaluation of the porous film revealed that the film strength was 0.92 GPa, the refractive index was 1.213, the porosity was 54%, and the contact angle was 8.2°.

[0149] Example 10 36.00 g of 2-propanol, 0.11 g of p-anisidine-2-sulfonic acid, and 14.40 g of pure water were added to 18.84 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solid content concentration 51% by mass), and the mixture was stirred at 37.5°C for 6 hours to prepare a silica sol solution.

[0150] Next, 117.0 g of a 2-propanol dispersion of hollow silicon oxide particles (Sururia 1110 manufactured by JGC Catalysts and Chemicals Co., Ltd., average particle size 50 nm, solid content concentration 20.5 mass%), 0.10 g of p-anisidine-2-sulfonic acid, and 44.34 g of 2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0151] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm.The film was then dried at 22°C for 10 hours to obtain a member having a porous film.

[0152] As a result of evaluating the porous film, the film strength was 1.13 GPa, the refractive index was 1.274, the porosity was 40%, and the contact angle was 8.8°.

[0153] Comparative Example 1 37.33 g of 2-propanol, 0.16 g of a phosphinic acid solution (50% by mass), and 11.92 g of pure water were added to 15.69 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solids concentration 51% by mass), and the mixture was stirred at 37.5°C for 6 hours to prepare a silica sol solution. The phosphinic acid was used as a substitute for the sulfonyl compound represented by Formula 1. Next, 100.00 g of a 2-propanol dispersion of spherical silicon oxide particles (IPA-ST, manufactured by Nissan Chemical Industries, Ltd., average particle size 12 nm, solids concentration 30% by mass), 64.10 g of a 2-propanol dispersion of chain silicon oxide particles (IPA-ST-UP, manufactured by Nissan Chemical Industries, Ltd., average minor axis 12 nm, solids concentration 15.6% by mass), and 272.58 g of 2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating solution.

[0154] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm. The film was then cured at 22°C for 10 hours to obtain a member having a porous film.

[0155] Evaluation of the porous film revealed that the film strength was 1.30 GPa, the refractive index was 1.375, the porosity was 18%, and the contact angle was 8.8°.

[0156] Comparative Example 2 37.33 g of 2-propanol, 0.16 g of nitrilotris(methylene)triphosphonic acid (50% by mass aqueous solution), and 12.00 g of pure water were added to 15.69 g of methyl silicate (Methyl Silicate 51, manufactured by Colcoat Co., Ltd., solids concentration 51% by mass), and the mixture was stirred at 37.5° C. for 6 hours to prepare a silica sol solution. Nitrilotris(methylene)triphosphonic acid was used as a substitute for the sulfonyl compound represented by Formula 1. Next, 100.00 g of a 2-propanol dispersion of spherical silicon oxide particles (IPA-ST manufactured by Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 30 mass%), 64.10 g of a 2-propanol dispersion of chain silicon oxide particles (IPA-ST-UP manufactured by Nissan Chemical Industries, Ltd., average minor axis 12 nm, solid content concentration 15.6 mass%), and 272.58 g of 2-propanol were added to the silica sol solution, and the mixture was stirred for 2 hours to obtain a coating liquid.

[0157] The obtained coating liquid was dropped onto a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 2 mm, polished on one side), and a porous film was formed by spin coating so that the thickness of the formed porous film was approximately 420 nm. The film was then cured at 22°C for 10 hours to obtain a member having a porous film.

[0158] As a result of evaluating the porous film, the film strength was 1.24 GPa, the refractive index was 1.377, the porosity was 18%, and the contact angle was 8.8°.

[0159] For Examples 1 to 7 and Comparative Examples 1 and 2, the shape and mixing ratio of inorganic oxide particles, the amount of inorganic binder added, the amount of sulfonyl compound added, and the evaluation results of the physical properties of the porous films are shown in Tables 1-1 and 1-2.

[0160]

[0161]

[0162] For Examples 8 to 12, the shape and mixing ratio of inorganic oxide particles, the amount of inorganic binder added, the amount of sulfonyl compound added, and the evaluation results of the physical properties of the porous film are shown in Tables 2-1 and 2-2.

[0163]

[0164]

[0165] The results in Tables 1-1, 1-2, 2-1 and 2-2 show that the porous membranes of Examples 1 to 12 achieved high membrane strength while maintaining porosity.

[0166] On the other hand, in Comparative Examples 1 and 2, although porosity is maintained, the film strength is reduced. This is thought to be because the organic acid used is not the sulfonyl compound of Formula 1 or Formula 2, and the acidity of the adsorption group is low, making it difficult to modify the surface of the inorganic oxide particles, resulting in a decrease in the dispersibility of the coating liquid.

[0167] As described above, according to the present disclosure, it is possible to provide a coating liquid that can suppress particle aggregation and a decrease in dispersibility, form a porous film with excellent strength, reduce the amount of fluorine acid used, and reduce the burden on the environment. Although fluorine acid was not used in the above-mentioned examples, the coating liquid of the present disclosure may be mixed with a coating liquid containing fluorine acid. By doing so, it is possible to reduce the amount of fluorine acid used compared to conventional methods.

[0168] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present disclosure. Therefore, the following claims are appended to apprise the public of the scope of the present disclosure.

[0169] This application claims priority based on Japanese Patent Application No. 2024-089719 filed on June 3, 2024 and Japanese Patent Application No. 2024-166617 filed on September 25, 2024, the entire contents of which are incorporated herein by reference.

[0170] REFERENCE SIGNS LIST 10 Coating liquid 120 Inorganic binder composition 14 Sulfonyl compound 11 Inorganic oxide particles 1 Porous film 12 Inorganic binder 2 Member 20 Substrate

Claims

1. A coating liquid comprising inorganic oxide particles, an inorganic binder composition, and a sulfonyl compound, wherein the sulfonyl compound is represented by Formula 1 or Formula 2. (In formula 1, n is an integer of 0 or more, and when n=0, R １ , R ２ is an organic group, and R １ , R ２ at least one of R is a group containing a conjugated structure, and the conjugated structure is directly bonded to the S atom; when n≧1, １ , R ２ is an organic group, and R ｘ are each independently, and R １ , all R ｘ , and R ２ At least one of the groups is a group containing a conjugated structure, and the conjugated structure is directly bonded to any of the S atoms. (In formula 2, R ３ ~R ６ is a hydrogen atom or any group.

2. The coating liquid according to claim 1, wherein the sulfonyl compound is represented by formula 1, and n in formula 1 is an integer of 0 or more and 3 or less.

3. The coating liquid according to claim 1 or 2, wherein the sulfonyl compound is represented by formula 1 and the conjugated structure contains 2 to 8 multiple bonds.

4. A coating fluid according to any one of claims 1 to 3, wherein the sulfonyl compound is represented by formula 1 and the conjugated structure contains an aromatic hydrocarbon.

5. The coating fluid according to any one of claims 1 to 4, wherein the sulfonyl compound is represented by formula 1, and the conjugated structure is a group selected from the group consisting of: (i) a substituted or unsubstituted chain hydrocarbon group containing two or more multiple bonds and having 1 to 20 carbon atoms, (ii) a substituted or unsubstituted aromatic hydrocarbon group containing 6 to 30 carbon atoms, and (iii) a substituted or unsubstituted heterocyclic group containing two or more multiple bonds and having 5 to 30 carbon atoms and containing any atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.

6. The coating fluid according to any one of claims 1 to 5, wherein the sulfonyl compound is represented by formula 1 and the group containing a conjugated structure is represented by formula 101. (In formula 101, R １０１ ~R １０５ are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. * indicates the bonding position to the S atom. When formula 101 represents a divalent group, any atom in the formula can be replaced with a second bonding position.

7. The sulfonyl compound is represented by formula 2, and R ３ ~R ６ are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom.

8. The coating fluid according to any one of claims 1 to 7, wherein the acid dissociation constant pKa of the sulfonyl compound is -1.2 or more and 2.0 or less.

9. A coating liquid according to any one of claims 1 to 8, wherein the content of the sulfonyl compound is 0.05 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the inorganic oxide particles.

10. A coating liquid according to any one of claims 1 to 9, wherein the inorganic oxide particles include silicon oxide particles.

11. The coating liquid according to any one of claims 1 to 10, wherein the inorganic oxide particles include at least one of solid inorganic oxide particles, chain inorganic oxide particles, and hollow inorganic oxide particles.

12. The coating liquid according to claim 11, wherein the solid inorganic oxide particles have an average particle size of 5 nm or more and 80 nm or less.

13. The coating liquid according to claim 11, wherein the average minor axis diameter of the chain-like inorganic oxide particles is 8 nm or more and 20 nm or less, and the average major axis diameter is 4 times or more and 8 times or less the average minor axis diameter.

14. The coating liquid according to claim 11, wherein the hollow inorganic oxide particles have an average particle size of 15 nm or more and 300 nm or less.

15. The coating fluid according to any one of claims 1 to 14, wherein the inorganic binder composition contains an oligomeric silicon oxide compound.

16. A coating liquid according to any one of claims 1 to 15, wherein the content of the inorganic binder composition is 0.1 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the inorganic oxide particles.

17. The coating fluid according to any one of claims 1 to 16, wherein the coating fluid contains a polar solvent.

18. The coating fluid according to claim 17, wherein the polar solvent contains at least one solvent selected from the group consisting of ethoxyethanol, propoxyethanol, isopropoxyethanol, butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, ethyl lactate, and 3-methoxy-1-butanol.

19. A coating liquid according to any one of claims 1 to 18 for forming a porous film.

20. A porous membrane comprising inorganic oxide particles, an inorganic binder, and a sulfonyl compound, wherein the inorganic oxide particles are bound to each other by the inorganic binder, and the sulfonyl compound is represented by Formula 1 or Formula 2. (In formula 1, n is an integer of 0 or more, and when n=0, R １ , R ２ is an organic group, and R １ , and R ２ at least one of R is a group containing a conjugated structure, and the conjugated structure is directly bonded to the S atom; when n≧1, １ , R ２ is an organic group, and R ｘ are each independently, and R １ , all R ｘ , and R ２ At least one of the groups is a group containing a conjugated structure, and the conjugated structure is directly bonded to any of the S atoms. (In formula 2, R ３ ~R ６ is a hydrogen atom or any group.

21. The porous membrane according to claim 20, wherein the sulfonyl compound is represented by Formula 1, and the conjugated structure contains 2 to 8 multiple bonds.

22. The porous membrane according to claim 20 or 21, wherein the sulfonyl compound is represented by Formula 1 and the conjugated structure is an aromatic hydrocarbon.

23. The porous membrane according to any one of claims 20 to 22, wherein the sulfonyl compound is represented by formula 1, and the group containing a conjugated structure is a group selected from the group consisting of: (i) a substituted or unsubstituted chain hydrocarbon group containing two or more multiple bonds and having 1 to 20 carbon atoms, (ii) a substituted or unsubstituted aromatic hydrocarbon group containing 6 to 30 carbon atoms, and (iii) a substituted or unsubstituted heterocyclic group containing two or more multiple bonds and having 5 to 30 carbon atoms and containing any atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.

24. The porous membrane according to any one of claims 20 to 23, wherein the sulfonyl compound is represented by formula 1 and the group containing a conjugated structure is a group represented by formula 101. (In formula 101, R １０１ ~R １０５ are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. * indicates the bonding position to the S atom. When formula 101 represents a divalent group, any atom in the formula can be replaced with a second bonding position.

25. The sulfonyl compound is represented by formula 2, and R ３ ~R ６ are each independently a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, an amino group, a hydroxy group, a carboxy group, a sulfo group, an alkylsulfonyl group, an acyl group, an alkoxy group, or a halogen atom, or adjacent groups are bonded to each other to form a ring structure, and the ring structure contains at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom.

26. The porous membrane of any one of claims 20 to 25, wherein the inorganic oxide particles comprise silicon oxide particles.

27. The porous membrane according to any one of claims 20 to 26, wherein the inorganic oxide particles comprise at least one of solid inorganic oxide particles, chain-like inorganic oxide particles, and hollow inorganic oxide particles.

28. The porous membrane according to claim 27, wherein the solid inorganic oxide particles have an average particle size of 5 nm or more and 80 nm or less.

29. The porous film according to claim 27, wherein the average minor axis diameter of the chain-like inorganic oxide particles is 8 nm to 20 nm, and the average major axis diameter is 4 to 8 times the average minor axis diameter.

30. The porous membrane according to claim 27, wherein the hollow inorganic oxide particles have an average particle size of 15 nm or more and 300 nm or less.

31. The porous membrane of any one of claims 20 to 30, wherein the inorganic binder comprises a silicon oxide compound.

32. The porous film according to any one of claims 20 to 31, characterized in that the indentation strength of the porous film is 0.8 GPa or more and 2.0 GPa or less.

33. The porous film according to any one of claims 20 to 32, characterized in that the refractive index of the porous film is 1.20 or more and 1.46 or less.

34. A member comprising a substrate and a porous membrane according to any one of claims 20 to 33 provided on the substrate.

35. The element of claim 34, further comprising an intermediate layer between the substrate and the porous membrane.

36. An optical device comprising a housing and an optical system including a plurality of lenses provided within the housing, at least one of the plurality of lenses being a member as defined in claim 34.

37. An imaging device comprising a housing, an optical system including a plurality of lenses provided within the housing, and an imaging element that receives light that has passed through the optical system, wherein at least one of the plurality of lenses is a member as defined in claim 34.

38. A method for manufacturing a member, comprising the steps of: applying the coating liquid according to claim 1 onto a substrate; and drying and / or baking the substrate onto which the coating liquid has been applied.

39. The method for manufacturing a member according to claim 38, wherein in the step of applying the coating liquid onto the substrate, the coating liquid is applied by spin coating or spray coating.

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