Water-repellent aluminum material and method for manufacturing the same

Abstract

The present invention provides a water-repellent aluminum material comprising: an aluminum substrate; an anodic oxide film formed on the aluminum substrate; and a water-repellent layer formed along the surface of the anodic oxide film opposite the aluminum substrate. The anodic oxide film has a plurality of pores, each of which has an opening on the flat upper surface of the anodic oxide film opposite the aluminum substrate. A longitudinal cross-section along the depth direction of the pores has a shape that narrows from the opening to the bottom of the pores. The water-repellent layer contains a low-surface-energy substance. According to the present invention, a water-repellent aluminum material is provided that exhibits excellent water sliding properties and water flow resistance, and is also highly practical.

Description

Technical Field

[0001] The present invention relates to a water-repellent aluminum material and a method for manufacturing the same. Background Art

[0002] Heat exchangers are used in air conditioners, refrigerators, freezers, electric vehicles, and other applications. To meet requirements for weight reduction, improved thermal efficiency, and further miniaturization, heat exchangers such as refrigerator and air conditioner evaporators have traditionally used various aluminum materials for their fins, with designs that minimize fin spacing. These heat exchangers present a problem: water droplets condense on the fin surfaces, and in outdoor units operating during heating, condensed water freezes on the fin surfaces due to low ambient temperatures, increasing ventilation resistance and significantly reducing heat exchange efficiency.

[0003] In order to solve this problem, Patent Document 1 proposes forming a hydrophilic coating film on the fin surface to allow water droplets adhering to the fin surface to flow down or to reduce water droplets remaining during defrosting.

[0004] However, the technique described in Patent Document 1 has a problem in that water residue is inevitably generated due to the hydrophilic nature of the coating film, and thus re-frosting occurs within a short period of time.

[0005] Regarding hydrophilicity, methods have been studied to impart water repellency to aluminum fins to repel water droplets (e.g., Patent Document 2). While water-repellent surfaces have been shown to delay the onset of frost, temporary water droplets are difficult to remove. In other words, water repellency is not necessarily correlated with the ease of droplet conversion and droplet removal. Consequently, existing water-repellent coatings suffer from insufficient water-slip properties.

[0006] In order to improve water sliding properties, methods of imparting unevenness to the aluminum surface by etching or by using water-repellent microparticles to impart unevenness have been studied (e.g., Patent Documents 3 and 4). However, the former method has insufficient water sliding properties, while the latter method has problems with particle dispersion and poor water flow durability.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 6-300482

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-147573

[0011] Patent Document 3: Japanese Patent Application Laid-Open No. 2013-36733

[0012] Patent Document 4: Japanese Patent Application Laid-Open No. 2013-103414 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] An object of the present invention is to provide a water-repellent aluminum material having excellent water sliding properties and water flow durability and excellent practicality.

[0015] Another object of the present invention is to provide a method for producing a water-repellent aluminum material that is excellent in process applicability, has excellent water sliding properties and water flow durability, and is excellent in practicality.

[0016] Solutions for solving problems

[0017] The present inventors conducted intensive research to address the aforementioned issues. As a result, they discovered that a water-repellent aluminum material having an anodized film and a water-repellent layer with a specific structure and a method for producing the same exhibit excellent process suitability, excellent water sliding properties, and excellent water resistance, resulting in excellent practicality. This led to the completion of the present invention.

[0018] The present invention is a water-repellent aluminum material comprising: an aluminum substrate; an anodized film formed on the aluminum substrate; and a water-repellent layer formed along the surface of the anodized film on the opposite side of the aluminum substrate, wherein the anodized film has a plurality of pores, and the pores have openings on the flat upper surface of the anodized film on the opposite side of the aluminum substrate, and a longitudinal cross-section along the depth direction of the pores has a shape that narrows from the openings of the pores toward the bottoms of the pores, and the water-repellent layer contains a low-surface-energy substance.

[0019] In addition, the present invention is a method for manufacturing a water-repellent aluminum material, which comprises the following steps: an anodized film forming step, in which anodizing treatment is performed more than twice in sequence to form an anodized film and pores by anodizing the surface of an aluminum substrate, and a pore enlargement treatment is performed to enlarge the pore diameters of the pores formed by the aforementioned anodization; and a water-repellent layer forming step, in which a water-repellent layer containing a low surface energy substance is formed along the surface of the aforementioned anodized film on the opposite side to the aforementioned aluminum substrate, the aforementioned anodized film having a plurality of pores, and the aforementioned pores having an opening portion on the flat upper surface of the aforementioned anodized film on the opposite side to the aforementioned aluminum substrate, and a longitudinal section along the depth direction of the aforementioned pores has a shape that narrows from the aforementioned opening portion of the aforementioned pores to the bottom of the aforementioned pores.

[0020] Effects of the Invention

[0021] According to the present invention, a water-repellent aluminum material having excellent water sliding properties and water flow durability and excellent practicality can be provided.

[0022] Furthermore, according to the present invention, a method for producing a water-repellent aluminum material having excellent process applicability, excellent water sliding properties and water flow durability, and excellent practicality can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram showing an example of a cross section of the water-repellent aluminum material of the present invention

[0024] Figure 2 A schematic diagram showing the processing state in each step of manufacturing the water-repellent aluminum material of the present invention

[0025] Figure 3 A schematic diagram showing the processing state in each step of manufacturing the water-repellent aluminum material of the present invention

[0026] Figure 4 A schematic diagram showing the processing state in each step of manufacturing the water-repellent aluminum material of the present invention

[0027] Figure 5 A schematic diagram showing the processing state in each step of manufacturing the water-repellent aluminum material of the present invention

[0028] Figure 6 SEM photograph of the anodic oxide film of the manufacturing example of the present invention

[0029] Figure 7 This is a SEM photograph of a cross section of an anodic oxide film of a manufacturing example of the present invention.

[0030] Figure 8 SEM photograph of the anodic oxide film of the comparative example of the present invention

[0031] Figure 9 This is a SEM photograph of a cross section of an anodic oxide film of a comparative manufacturing example of the present invention.

[0032] Figure 10 SEM photograph of the anodic oxide film of the comparative example of the present invention

[0033] Figure 11 This is a SEM photograph of a cross section of an anodic oxide film of a comparative manufacturing example of the present invention.

[0034] Figure 12 SEM photograph of the anodic oxide film of the comparative example of the present invention

[0035] Figure 13 This is a SEM photograph of a cross section of an anodic oxide film of a comparative manufacturing example of the present invention.

[0036] Figure 14 SEM photograph of the anodic oxide film of the comparative example of the present invention

[0037] Figure 15 This is a SEM photograph of a cross section of an anodic oxide film of a comparative manufacturing example of the present invention.

[0038] Figure 16 SEM photograph of the anodic oxide film of the comparative example of the present invention

[0039] Figure 17 This is a SEM photograph of a cross section of an anodic oxide film of a comparative manufacturing example of the present invention. DETAILED DESCRIPTION

[0040] Reference Figure 1 At the same time, a water-repellent aluminum material according to one embodiment of the present invention will be described. Figure 1 This is a schematic diagram of a cross section in the depth direction of the water-repellent aluminum material 1 according to the present embodiment.

[0041] The water-repellent aluminum material 1 comprises: an aluminum substrate 11; an anodized film 12 formed on the aluminum substrate 11; and a water-repellent layer 13 formed along the surface of the anodized film 12 opposite the aluminum substrate 11. The anodized film 12 has a plurality of pores 121. The pores 121 have openings 123 on a flat upper surface 122 of the anodized film 12 opposite the aluminum substrate 11. A longitudinal cross-section along the depth direction of the pores 121 has a shape that narrows from the openings 123 of the pores 121 toward the bottoms 124 of the pores 121. In this embodiment, the "surface opposite the aluminum substrate 11" on which the water-repellent layer 13 is formed includes the flat upper surface 122 having the openings 123 and the inner surfaces of the pores 121. Therefore, the water-repellent layer 13 is formed along the flat upper surface 122 and the inner surfaces of the pores 121. The water-repellent layer 13 comprises a low-surface-energy substance. The water-repellent aluminum material 1 has excellent water sliding properties and water flow durability, and is excellent in practicality.

[0042] There are no particular limitations on the aluminum constituting the aluminum substrate 11. From the perspective of the influence of impurities present in aluminum, the aluminum substrate preferably has an aluminum purity of 99.00 mass % or higher, more preferably 99.50 mass % or higher, and even more preferably 99.90 mass % or higher.

[0043] From the perspective of imparting durability in addition to super-hydroplaning properties, the shape of the pores that narrows from the opening 123 to the bottom 124 of the pores is preferably a shape that narrows in stages from the opening 123 to the bottom 124 of the pores. This shape can reduce the area of the portion that comes into contact with water droplets and also enhance shape maintenance, i.e., durability. Figure 1In the embodiment, the shape that narrows from the opening 123 of the pore to the bottom 124 of the pore narrows in one step, but may be in two or more steps. Furthermore, the shape that narrows in steps from the opening 123 of the pore to the bottom 124 of the pore may be a smooth shape. Furthermore, the shape that narrows from the opening 123 of the pore 121 to the bottom 124 of the pore 121 may be a bell-shaped shape that narrows in a curved manner from the opening 123 of the pore 121 to the bottom 124 of the pore 121.

[0044] The shape of the pores 121 is formed by subjecting the surface of the aluminum substrate to two or more anodizing and pore-enlarging treatments. The more anodizing and pore-enlarging treatments are applied, the smoother the shape of the pores 121, which tapers from the opening 123 toward the bottom 124. Therefore, by adjusting the number of anodizing and pore-enlarging treatments, the shape of the pores 121, which tapers from the opening 123 toward the bottom 124, can be adjusted.

[0045] Regarding the pore period P of the pores 121, the lower limit is preferably 100 nm or greater to ensure a sufficient distance from the point of contact with the water droplet and to facilitate the development of super-hydroplaning properties. Furthermore, the upper limit is preferably 1000 nm or less, and more preferably 200 nm or less for productivity. It should be noted that the pore period P refers to the distance from the center of a pore 121 to the center of its adjacent pore 121. This pore period P is measured according to the method described in the Examples.

[0046] From the viewpoint of ensuring water flow durability, the pore depth D of the pores 121 is preferably in the range of 100 nm to 1000 nm. Note that the pore depth D refers to the depth from the flat upper surface 122 to the bottom 124 .

[0047] The low-surface-energy substance included in the water-repellent layer 13 is a substance having a surface free energy lower than that of water, and is, for example, a compound having one or more water-repellent groups selected from the group consisting of fluorine-containing groups, silicone-containing groups, and hydrocarbon groups, and one or more alumina-reactive groups selected from the group consisting of sulfide groups, mercapto groups, amino groups, sulfonyl groups, hydroxyl groups, carboxyl groups, phosphoric acid-containing groups, and alkoxysilyl groups. More specific examples of such low-surface-energy substances include fluorine-containing compounds such as polytetrafluoroethylene and polytetrafluoroethylene-hexafluoropropylene copolymers, and silicone compounds such as polydimethylsiloxane and polymethylphenylsiloxane.

[0048] From the perspective of achieving more excellent super-slippery properties, the low surface energy substance is preferably a fluorine-containing compound having a perfluoroalkyl group and / or a perfluoropolyether group, and more preferably a fluorine-containing compound selected from the group consisting of C n F2n+1 Perfluoroalkyl (n is an integer greater than or equal to 1), F (C n F 2n O) m The perfluoropolyether group shown (n is an integer greater than 1, and m is an integer indicating the number of repetitions), and CF3O (C n F2 n O) m A fluorine-containing compound comprising one or more of the group consisting of the perfluoropolyether group shown (n is an integer greater than 1, and m is an integer representing the number of repetitions), and a silyl group shown by Si(A)3 (the three As are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three As is a hydrolyzable group).

[0049] The aforementioned C n F 2n+1 In the perfluoroalkyl group shown, n is preferably in the range of 1 to 6.

[0050] The aforementioned F(C n F 2n O) m In the perfluoropolyether group shown, n is preferably in the range of 1 to 6, more preferably in the range of 1 to 3, and m is, for example, in the range of 5 to 100 on average, preferably in the range of 8 to 80 on average, more preferably in the range of 10 to 60 on average.

[0051] The aforementioned CF3O(C n F 2n O) m In the perfluoropolyether group shown, n is preferably in the range of 1 to 6, more preferably in the range of 1 to 3, and m is, for example, in the range of 5 to 100 on average, preferably in the range of 8 to 80 on average, more preferably in the range of 10 to 60 on average.

[0052] The fluorine-containing compound may include (C n F 2n O) m The perfluoropolyether chain shown is (n is an integer greater than or equal to 1, and m is an integer indicating the number of repetitions).

[0053] Examples of the hydrolyzable group include alkoxy groups such as methoxy, ethoxy, and propoxy; alkoxy-substituted alkoxy groups such as methoxyethoxy; acyloxy groups such as acetoxy, propionyloxy, and benzoyloxy; alkenyloxy groups such as isopropenyloxy and isobutenyloxy; iminooxy groups such as dimethylketoxime, methylethylketoxime, diethylketoxime, and cyclohexaneoxime; substituted amino groups such as methylamino, ethylamino, dimethylamino, and diethylamino; amide groups such as N-methylacetamide and N-ethylamide; substituted aminooxy groups such as dimethylaminooxy and diethylaminooxy; and halogens such as chlorine. Among these hydrolyzable groups, alkoxy groups are preferred, more preferably alkoxy groups having 1 to 6 carbon atoms, even more preferably alkoxy groups having 1 to 3 carbon atoms, particularly preferably methoxy and ethoxy groups, and most preferably methoxy groups.

[0054] Examples of the non-hydrolyzable group include alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms. Among these non-hydrolyzable groups, alkyl groups having 1 to 3 carbon atoms are preferred, and methyl groups are more preferred, from the perspectives of avoiding steric hindrance, accelerating the hydrolysis rate, and, as a result, rapidly forming a film with excellent durability.

[0055] The number of hydrolyzable groups in the silyl group shown in Si(A)3 is at least 1. From the perspective of being able to form a film with better durability, it is preferably 2 or more, and more preferably all 3 are hydrolyzable groups. It should be noted that when the hydrolyzable groups in the silyl group shown in Si(A)3 have 2 or more, the 2 or more hydrolyzable groups are optionally the same as or different from each other. In addition, when the silyl group shown in Si(A)3 has 2 or more, as long as at least 1 silyl group shown in Si(A)3 has a hydrolyzable group. Similarly, when the non-hydrolyzable groups in the silyl group shown in Si(A)3 have 2 or more, the 2 or more non-hydrolyzable groups are optionally the same as or different from each other.

[0056] The fluorine-containing compound is preferably a compound represented by the following formula (1-1) or (1-2).

[0057] Rf-X-Si(A)3 (1-1)

[0058]

[0059] (In the above formulas (1-1) and (1-2),

[0060] R f Each independently is C n F 2n+1The perfluoroalkyl group represented by (n is an integer greater than or equal to 1).

[0061] The three As of the silyl group represented by Si(A) 3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three As is a hydrolyzable group.

[0062] X is any of the linking groups represented by the following formulae (X-1) to (X-11).

[0063]

[0064] (In the aforementioned formulas (X-1) to (X-11),

[0065] R f C n F 2n+1 The perfluoroalkyl group represented by (n is an integer greater than or equal to 1).

[0066] R 11 It is a direct bond or an alkylene group having 1 to 6 carbon atoms.

[0067] R 11 There are multiple cases, multiple R 11 They are optionally the same as or different from each other.

[0068] R 12 is an alkyl group having 1 to 6 carbon atoms.)

[0069] In formulas (1-1) and (1-2), for C n F 2n+1 Preferred embodiments of the perfluoroalkyl group represented by and the silyl group represented by Si(A)3 are as described above, respectively.

[0070] Specific examples of the compound represented by formula (1-1) or (1-2) include the following.

[0071]

[0072] The method for producing the compound represented by formula (1-1) or (1-2) is not particularly limited and can be produced by a known method, for example, by the method disclosed in International Publication No. WO2015 / 152265.

[0073] The fluorine-containing compound is preferably a compound represented by the following formula (2-1), (2-2), (2-3) or (2-4).

[0074]

[0075] (In the aforementioned formulas (2-1), (2-2), (2-3) and (2-4),

[0076] r is an integer indicating the number of repetitions.

[0077] R 21 It is an alkylene group having 1 to 6 carbon atoms.

[0078] R 23 It is a divalent linking group.

[0079] Z is a trivalent linking group.

[0080] Each Q is independently an organic group or a silyl group represented by -Si(A)3, and at least one of the two Qs is a silyl group represented by Si(A)3.

[0081] The three A's of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three A's is a hydrolyzable group.

[0082] In formulae (2-1), (2-2), (2-3) and (2-4), the number of repetitions of r is preferably in the range of 5 to 100 on average, more preferably in the range of 8 to 80 on average, and even more preferably in the range of 10 to 60 on average.

[0083] In formulas (2-1), (2-2), (2-3) and (2-4), R 21 The alkylene group has 1 to 6 carbon atoms, and preferably has 3 carbon atoms.

[0084] In the formulae (2-1), (2-2), (2-3) and (2-4), preferred embodiments of the silyl group represented by Si(A) 3 are as described above.

[0085] In the formulae (2-1) and (2-2), when Q is an organic group, examples of the organic group include substituted or unsubstituted alkyl groups, alkenyl groups, and phenyl groups.

[0086] When the organic group of Q is a substituted alkyl group, examples of the substituted alkyl group include a partially fluorinated alkyl group having 1 to 6 carbon atoms and a perfluoroalkyl group having 1 to 6 carbon atoms.

[0087] In formulas (2-1), (2-2), (2-3) and (2-4), R 23 The divalent linking group is preferably a linking group represented by the following formula (R-1) or a linking group represented by the following formula (R-2).

[0088] -R 24 -OR 25 - (R-1)

[0089] -R 26 - (R-2)

[0090] (In the aforementioned formulas (R-1) and (R-2),

[0091] R 24 It is an alkylene group having 1 to 3 carbon atoms.

[0092] R 25 It is a direct bond or an alkylene group having 1 to 6 carbon atoms.

[0093] R 26 is an alkylene group having 1 to 5 carbon atoms)

[0094] Specific examples of the linking group represented by formula (R-1) include the following.

[0095] -CH2-O- (R-1-1)

[0096] -CH2-O-CH2- (R-1-2)

[0097] -CH2-O-CH2CH2- (R-1-3)

[0098] -CH2-O-CH2CH2CH2- (R-1-4)

[0099] Specific examples of the linking group represented by formula (R-2) include the following.

[0100] -CH2- (R-2-5)

[0101] -CH2CH2- (R-2-6)

[0102] -CH2CH2CH2- (R-2-7)

[0103] -CH2CH2CH2CH2- (R-2-8)

[0104] -CH2CH2CH2CH2CH2CH2- (R-2-9)

[0105] As the linking groups represented by formulas (R-1) and (R-2), preferred are linking groups represented by formulas (R-1-1), (R-1-3), (R-1-4), (R-2-5), (R-2-6), and (R-2-8), and more preferred are linking groups represented by formulas (R-1-3) and (R-1-4).

[0106] The trivalent linking group of Z in formulae (2-2) and (2-4) is preferably a trivalent cyclic aliphatic group having 4 to 8 carbon atoms, and more preferably a trivalent cyclohexyl group.

[0107] Specific examples of the compound represented by formula (2-1), (2-2), (2-3) or (2-4) include the following.

[0108]

[0109]

[0110]

[0111] (In the above formulas (2-1-11) and (2-1-12), a is an integer of 1 to 6.)

[0112]

[0113]

[0114]

[0115] The method for producing the compound represented by formula (2-1), (2-2), (2-3) or (2-4) is not particularly limited, and the compound can be produced according to a known method.

[0116] Hereinafter, one embodiment of a method for producing a compound represented by formula (2-1), (2-2), (2-3) or (2-4) will be described.

[0117] The method for producing the compounds represented by formulas (2-1) and (2-2) includes, for example, the following steps: a first step of reacting a carboxylic acid represented by the following formula (β-1) with an epoxysilane compound represented by the following formula (β-2) or the following formula (β-3) to prepare a reactant having a secondary hydroxyl group derived from an epoxy group; and a second step of reacting the reactant obtained in the aforementioned first step with an isocyanate compound represented by the following formula (β-4).

[0118]

[0119] (In the above formula (β-1), r is the number of repetitions.)

[0120]

[0121] (In the aforementioned formula (β-2) and formula (β-3),

[0122] R 23 It is a divalent linking group.

[0123] The three A's of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three A's is a hydrolyzable group.

[0124] OCN-R 21-Si(A)3 (β-4)

[0125] (In the aforementioned formula (β-4),

[0126] R 21 It is an alkylene group having 1 to 6 carbon atoms.

[0127] The three A's of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three A's is a hydrolyzable group.

[0128] A compound represented by the following formula (β-5) may be used instead of the compound represented by the formula (β-2).

[0129]

[0130] (In the aforementioned formula (β-5),

[0131] R 23 It is a divalent linking group.

[0132] G is an organic group.)

[0133] When producing the compounds represented by formula (2-3) and (2-4), the above-mentioned first step may be included, and the above-mentioned second step may be omitted.

[0134] Specific examples of the compound represented by formula (β-2) include the following.

[0135]

[0136] Specific examples of the compound represented by formula (β-3) include the following.

[0137]

[0138] Specific examples of the compound represented by formula (β-4) include the following.

[0139] OCN-R 21 -SiCH3(OCH3)2 OCN-R 21 -Si(OCH3)3

[0140] OCN-R 21 -SiCH3(OC2H5)2 OCN-R 21 -Si(OC2H5)3

[0141] OCN-R 21 -SiCH3(OC3H7)2 OCN-R 21 -Si(OC3H7)3

[0142] OCN-R 21 -SiCH3(OC4H9)2 OCN-R 21 -Si(OC4H9)3

[0143] OCN-R 21 -Si(CH3)2(OCH3)

[0144] OCN-R 21 -Si(CH3)2(OC2H5)

[0145] OCN-R 21 -Si(CH3)2(OC3H7)

[0146] OCN-R 21 -Si(CH3)2(OC4H9)

[0147] (Where R 21 is an alkylene group having 1 to 6 carbon atoms, preferably an alkylene group having 1 to 3 carbon atoms, and more preferably an n-propylene group)

[0148] Specific examples of the compound represented by formula (β-5) include the following.

[0149]

[0150] (a is an integer in the range of 1 to 6.)

[0151] The method for producing the compound represented by formula (2-1), (2-2), (2-3) or (2-4) can be carried out in the presence of an organic solvent as necessary.

[0152] The organic solvent is not particularly limited as long as it can dissolve the compound group as the raw materials. For example, solvents such as acetone, methyl ethyl ketone, toluene, and xylene that are not reactive with isocyanate groups, and fluorinated organic solvents can be used.

[0153] As the aforementioned fluorine-based solvents, preferred examples include fluorinated aromatic hydrocarbon solvents such as 1,3-bis(trifluoromethyl)benzene and trifluorotoluene; perfluorocarbon solvents having 3 to 12 carbon atoms such as perfluorohexane and perfluoromethylcyclohexane; hydrofluorocarbon solvents such as 1,1,2,2,3,3,4-heptafluorocyclopentane and 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorooctane; hydrofluoroether solvents such as C3F7OCH3, C4F9OCH3, C4F9OC2H5, and C2F5CF(OCH3)C3F7; and perfluoropolyether compounds such as Fomblin, Galden (manufactured by Solvay), Demnum (manufactured by DAIKIN INDUSTRIES, LTD.), and Krytox (manufactured by Chemours).

[0154] In the aforementioned first step, the reaction ratio of compound (β-1) and compound (β-2) or compound (β-3) is preferably a ratio in the range of 0.5 to 1.5 in terms of the equivalent ratio (carboxyl group / epoxy group) of the carboxyl group possessed by compound (β-1) and the epoxy group possessed by compound (β-2) or compound (β-3), more preferably a ratio in the range of 0.9 to 1.1, and further preferably a ratio in the range of 0.98 to 1.02.

[0155] The reaction temperature in the first step is not particularly limited, but is usually in the range of 50 to 150° C. The reaction time is also not particularly limited, but is usually in the range of 1 to 10 hours.

[0156] In the aforementioned second step, the reaction ratio of the reactant having a secondary hydroxyl group derived from an epoxy group obtained in the aforementioned first step and the compound (β-4) is preferably a ratio in the range of 0.5 to 1.5 in terms of the equivalent ratio (hydroxyl group / isocyanate group) of the hydroxyl group possessed by the aforementioned reactant to the isocyanate group possessed by the compound (β-4), more preferably a ratio in the range of 0.9 to 1.1, and further preferably a ratio in the range of 0.98 to 1.02.

[0157] The reaction temperature in the second step is not particularly limited, but is usually in the range of 30 to 120° C. The reaction time is also not particularly limited, but is usually in the range of 1 to 10 hours.

[0158] The fluorine-containing compound is preferably a compound represented by the following formula (3).

[0159]

[0160] (In the above formula (3),

[0161] PFPE is a poly(perfluoroalkylene ether) chain.

[0162] Y 1 and Y 2 Each independently represents a direct bond or a divalent linking group.

[0163] Z 1 and Z 2 Each is independently a divalent linking group.

[0164] The three A's of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three A's is a hydrolyzable group. The two silyl groups represented by Si(A)3 may be the same or different.

[0165] The compound represented by formula (3) has a carbamate bond in its skeleton. The presence of the carbamate bond can improve the polarity near the hydrolyzable groups located at both ends.

[0166] In formula (3), preferred embodiments of the silyl group represented by Si(A) 3 are as described above.

[0167] In formula (3), as Y 1 、Y 2 , Z 1 and Z 2 Examples of the divalent linking group include an alkylene group having 1 to 22 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a n-propylene group, an isopropylene group, a butylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, a 2,2-dimethylpropylene group, a 2-methylbutylene group, a 2-methyl-2-butylene group, a 3-methylbutylene group, a 3-methyl-2-butylene group, a pentylene group, a 2-pentylene group, a 3-pentylene group, a 3-dimethyl-2-butylene group, a 3,3-dimethylbutylene group, a 3,3-dimethyl-2-butylene group, a 2-ethylbutylene group, a hexylene group, a 2-hexylene group, a 3-hexylene group, a 2-methylpentylene group, a 2-methyl-2-pentylene group, a 2-methyl-3-pentylene group, a 3-methylpentylene group, a 3-methyl-2-pentylene group, a 3- Alkylene groups such as methyl-3-pentylene, 4-methylpentylene, 4-methyl-2-pentylene, 2,2-dimethyl-3-pentylene, 2,3-dimethyl-3-pentylene, 2,4-dimethyl-3-pentylene, 4,4-dimethyl-2-pentylene, 3-ethyl-3-pentylene, heptylene, 2-heptylene, 3-heptylene, 2-methyl-2-hexylene, 2-methyl-3-hexylene, 5-methylhexylene, 5-methyl-2-hexylene, 2-ethylhexylene, 6-methyl-2-heptylene, 4-methyl-3-heptylene, octylene, 2-octylene, 3-octylene, 2-propylpentylene, 2,4,4-trimethylpentylene, and decaprylene can be included.

[0168] Z in formula (3) 1 and Z 2 The divalent linking groups are each independently preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, further preferably an alkylene group having 1 to 3 carbon atoms, and particularly preferably an n-propylene group.

[0169] Y in formula (3) 1 and Y 2 The divalent linking groups are each independently preferably an alkylene group having 1 to 6 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms, and further preferably a methylene group.

[0170] Examples of the PFPE (poly(perfluoroalkylene ether) chain) of formula (3) include linking groups having a structure in which perfluoroalkylene groups having 1 to 3 carbon atoms and oxygen atoms are alternately linked.

[0171] Examples of the linking group having a structure in which perfluoroalkylene groups having 1 to 3 carbon atoms and oxygen atoms are alternately linked include a linking group represented by the following formula (P-1).

[0172]

[0173] (In the aforementioned formula (P-1),

[0174] * is an atomic bond.

[0175] X is a perfluoroalkylene group having 1 to 3 carbon atoms.

[0176] The perfluoroalkylene groups of the plurality of Xs may be the same as or different from each other. Among the plurality of Xs, two or more perfluoroalkylene groups may be present randomly or in blocks.

[0177] n is the number of repetitions. n is, for example, in the range of 6 to 300, preferably in the range of 12 to 200, more preferably in the range of 20 to 150, further preferably in the range of 30 to 100, and most preferably in the range of 35 to 70.

[0178] As the perfluoroalkylene group represented by X, the following structures can be exemplified.

[0179]

[0180] Among these, X is preferably a perfluoromethylene group (a) and a perfluoroethylene group (b), and more preferably a perfluoromethylene group (a) and a perfluoroethylene group (b) coexist in view of industrial availability.

[0181] When the perfluoromethylene group (a) and the perfluoroethylene group (b) coexist, the abundance ratio (a / b) (number ratio) thereof is preferably in the range of 1 / 10 to 10 / 1, more preferably in the range of 3 / 10 to 10 / 3.

[0182] Specific examples of the compound represented by formula (3) include the following.

[0183]

[0184] In the compound represented by formula (3), the total number of fluorine atoms contained in one poly(perfluoroalkylene ether) chain is preferably in the range of 30 to 600, more preferably in the range of 60 to 450, further preferably in the range of 90 to 300, and most preferably in the range of 100 to 200.

[0185] The method for producing the compound represented by formula (3) is not particularly limited, and the compound can be produced according to a known method. One embodiment of the method for producing the compound represented by formula (3) is described below.

[0186] The compound represented by formula (3) can be produced by reacting a diol represented by the following formula (α-1) with an isocyanate represented by the following formula (α-2).

[0187] HO-Y 1 -PFPE-Y 2 -OH (α-1)

[0188] OCN-Z-Si(A)3 (α-2)

[0189] (In the above formulas (α-1) and (α-2),

[0190] PFPE is a poly(perfluoroalkylene ether) chain.

[0191] Y 1 and Y 2 Each independently represents a direct bond or a divalent linking group.

[0192] Z is a divalent linking group.

[0193] The three A's of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three A's is a hydrolyzable group.

[0194] PFPE and Y in formula (α-1) and (α-2) 1 、Y 2 , Z and Si(A)3 correspond to PFPE, Y 1 、Y 2 , Z 1 , Z 2 and Si(A)3.

[0195] Examples of the diol represented by the formula (α-1) include a diol represented by the following formula (α-1-1) and a diol represented by the following formula (α-1-2).

[0196] HO-CH2-PFPE-CH2-OH (α-1-1)

[0197] HO-CH2CH2-PFPE-CH2CH2-OH (α-1-2)

[0198] Examples of the isocyanate represented by the formula (α-2) include isocyanates represented by the following formulas (α-2-1) to (α-2-12).

[0199]

[0200] Z in the isocyanate compounds represented by formulae (α-2-1) to (α-2-12) is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, further preferably an alkylene group having 1 to 3 carbon atoms, and particularly preferably an n-propylene group.

[0201] When the diol represented by formula (α-1) and the isocyanate represented by formula (α-2) are reacted (urethanization), the isocyanate represented by formula (α-2) is preferably added in an amount within the range of 0.5 to 1.5 mol, more preferably within the range of 0.9 to 1.1 mol, and most preferably within the range of 0.98 to 1.02 mol, per 1 mol of OH groups contained in the diol represented by formula (α-1).

[0202] In order to promote the urethanization reaction, when reacting the diol represented by formula (α-1) with the isocyanate represented by formula (α-2), tertiary amines such as triethylamine and benzyldimethylamine, or tin compounds such as dibutyltin dilaurate, dioctyltin dilaurate, and tin 2-ethylhexanoate may be added as catalysts.

[0203] The amount of the catalyst added is preferably 0.001 to 5.0% by mass, more preferably 0.01 to 1.0% by mass, and even more preferably 0.02 to 0.2% by mass relative to the total reaction mixture. The reaction time is preferably 1 to 10 hours.

[0204] In the reaction of the diol represented by formula (α-1) and the isocyanate represented by formula (α-2), the reaction system may be a solvent-free system or an organic solvent such as acetone, methyl ethyl ketone, toluene, xylene, etc. which is not reactive with isocyanate groups; C4F9C2H5, (CF3)2CFCHFCHFCF3, C6F 13 H, C6F 13 A solvent system in which fluorine-based solvents such as C2H5, C4F9OCH3, C4F9OC2H5, C2F5CF(OCH3)C3F7, HCF2CF2OCH2CF3 are used as reaction solvents.

[0205] The reaction temperature is preferably in the range of 30 to 120°C, more preferably in the range of 40 to 90°C.

[0206] The fluorine-containing compound is preferably a compound represented by the following formula (4-1), (4-2) or (4-3).

[0207]

[0208] (In the above formulas (4-1), (4-2) and (4-3),

[0209] r is an integer indicating the number of repetitions.

[0210] R 41 It is an alkylene group having 1 to 6 carbon atoms.

[0211] R 42 is an alkyleneaminoalkylene group or an alkylenethioalkylene group.

[0212] The three A's of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three A's is a hydrolyzable group.

[0213] In the formulae (4-1), (4-2) and (4-3), the number of repetitions of r and preferred embodiments of the silyl group represented by Si(A) 3 are as described above, respectively.

[0214] In formulas (4-1), (4-2) and (4-3), R 41 The alkylene group has 1 to 6 carbon atoms, and preferably has 3 carbon atoms.

[0215] In formulas (4-1), (4-2) and (4-3), R 42 The alkyleneaminoalkylene group is a group in which two alkylene groups are linked by an amino bond (-NH-), and the alkylenethioalkylene group is a group in which two alkylene groups are linked by a sulfide bond (-S-). Here, the alkylene groups in the alkyleneaminoalkylene group and the alkylenethioalkylene group are preferably each independently an alkylene group having 1 to 6 carbon atoms.

[0216] Specific examples of the compound represented by formula (4-1), (4-2) or (4-3) include the following.

[0217]

[0218] The method for producing the compound represented by formula (4-1), (4-2) or (4-3) can be the same as the method for producing the compound represented by formula (2-1), (2-2), (2-3) or (2-4). For example, the compound represented by formula (4-1), (4-2) or (4-3) can be produced by reacting an alcohol represented by the following formula (γ-1) with an isocyanate compound represented by the above formula (β-4). The reaction conditions and other raw materials can be the same as those used in the method for producing the compound represented by formula (2-1), (2-2), (2-3) or (2-4).

[0219]

[0220] (In the above formula (γ-1), r is the number of repetitions.)

[0221] The fluorine-containing compound is preferably a compound represented by the following formula (5-1), (5-2) or (5-3).

[0222]

[0223] (In the above formulas (5-1), (5-2) and (5-3),

[0224] l is an integer representing the number of repetitions.

[0225] m is an integer indicating the number of repetitions.

[0226] R 51 It is an alkylene group having 1 to 6 carbon atoms.

[0227] R 52 is an alkyleneaminoalkylene group or an alkylenethioalkylene group.

[0228] The three A's of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three A's is a hydrolyzable group.

[0229] In formulas (5-1), (5-2) and (5-3), the repeating units enclosed by l and the repeating units enclosed by m can be a random polymerization structure of the repeating units enclosed by l and the repeating units enclosed by m, or a block polymerization structure of the repeating units enclosed by l and the repeating units enclosed by m.

[0230] In formulae (5-1), (5-2) and (5-3), the repeating numbers of l and m, and preferred embodiments of the silyl group represented by Si(A) 3 are as described above, respectively.

[0231] In formulas (5-1), (5-2) and (5-3), R 51 The alkylene group has 1 to 6 carbon atoms, and preferably has 3 carbon atoms.

[0232] In formulas (5-1), (5-2) and (5-3), R 52 The alkyleneaminoalkylene group is a group in which two alkylene groups are linked by an amino bond (-NH-), and the alkylenethioalkylene group is a group in which two alkylene groups are linked by a sulfide bond (-S-). Here, the alkylene groups in the alkyleneaminoalkylene group and the alkylenethioalkylene group are preferably each independently an alkylene group having 1 to 6 carbon atoms.

[0233] Specific examples of the compound represented by formula (5-1), (5-2) or (5-3) include the following.

[0234]

[0235] The method for producing the compound represented by formula (5-1), (5-2) or (5-3) can be the same method as the method for producing the compound represented by formula (4-1), (4-2) or (4-3).

[0236] For example, by using an alcohol represented by the following formula (δ-1) instead of the alcohol represented by the above formula (γ-1), a compound represented by the formula (5-1), (5-2) or (5-3) can be produced.

[0237]

[0238] (In the aforementioned formula (δ-1),

[0239] l is the number of repetitions.

[0240] m is the number of repetitions.)

[0241] The fluorine-containing compound in the water-repellent layer 13 may be used alone or in combination of two or more.

[0242] The low surface energy substance is not limited to the fluorine-containing compound. Any compound having both a reactive group capable of reacting and bonding with the anodic oxide film and a water-repellent group exhibiting water repellency can be used.

[0243] As the aforementioned reactive groups capable of reacting and bonding with the anodized coating, there can be mentioned sulfide groups, mercapto groups, amino groups, sulfonyl groups, hydroxyl groups, carboxyl groups, phosphoric acid groups, and alkoxysilyl groups. More preferred examples include monovalent or divalent phosphoric acid groups represented by the following formula (6-1) or (6-2), and alkoxysilyl groups represented by the following formula (6-3).

[0244]

[0245] (In the above formulas (6-1) and (6-2),

[0246] R 61 Each independently represents any cation.

[0247] R 62 Each independently represents an alkyl group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms.)

[0248] As R 61 The arbitrary cations include alkali metal ions such as sodium ion, potassium ion, lithium ion, organic quaternary ammonium ions such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, ammonium ions, etc. Among them, lithium ion, sodium ion, and organic quaternary ammonium ion are preferred.

[0249] Examples of the water-repellent group include Cn H 2n+1 - (n is an integer greater than or equal to 1), a group represented by the following formula (7-1), etc.

[0250]

[0251] (In the above formula (7),

[0252] R 71 Each independently represents an alkyl group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms.

[0253] n is an integer greater than or equal to 1.)

[0254] The water-repellent layer 13 may contain components other than the low-surface-energy substance as long as the effects of the present invention are not impaired.

[0255] The lower limit of the thickness of the water-repellent layer 13 is preferably 1 nm or more so as not to impair the thermal conductivity of aluminum. The upper limit of the thickness of the water-repellent layer 13 is preferably 100 nm or less, more preferably 20 nm or less.

[0256] The contact angle of water on the surface of the water-repellent layer 13 is preferably 150° or greater, more preferably 160° or greater, for a 5 μL water droplet. Furthermore, the roll-off angle of water on the surface of the water-repellent layer 13 is preferably 10° or less, more preferably 5° or less, for a 5 μL water droplet. It should be noted that in this specification, the roll-off angle of water and the contact angle of water are measured using the methods described in the Examples.

[0257] A method for manufacturing a water-repellent aluminum material according to one embodiment of the present invention comprises the following steps: an anodized film forming step, in which anodizing treatment is performed more than twice in sequence to form an anodized film and pores by anodizing the surface of an aluminum substrate, and a pore enlargement treatment is performed to enlarge the pore diameters of the pores formed by the anodizing; and a water-repellent layer forming step, in which a water-repellent layer comprising a low-surface-energy substance is formed along the surface of the anodized film on the opposite side to the aluminum substrate, wherein the anodized film has a plurality of pores, and the pores have an opening on the flat upper surface of the anodized film on the opposite side to the aluminum substrate, and a longitudinal section along the depth direction of the pores has a shape that narrows from the opening of the pores to the bottom of the pores.

[0258] Reference Figures 2 to 5 At the same time, a method for producing a water-repellent aluminum material according to an embodiment of the present invention will be described. It should be noted that the same reference numerals are given to the same parts as those described in the present embodiment, and repeated descriptions are omitted.

[0259] Figures 2 to 5It is a schematic diagram showing the processing state in each step of manufacturing the water-repellent aluminum material 1.

[0260] The above-mentioned anodic oxide film forming process is to Figure 2 The surface of the aluminum substrate 11 is subjected to anodizing treatment and pore enlargement treatment for two or more times to form an anodized film 12 on the surface of the aluminum substrate 11. If anodizing treatment is performed as the first treatment, then Figure 3 As shown, an anodic oxide film 12 having pores 121' is formed on the surface of the aforementioned aluminum substrate 11. The pores 121' are cylindrical in the initial stage. The anodic oxide film 12 in the above state is further subjected to a pore enlargement treatment, thereby enlarging the pores 121' ( Figure 4 ).right Figure 4 The anodized film 12 in the state of further repeating the anodizing treatment and the pore enlargement treatment can form the anodized film 12 on the aluminum substrate 11. The anodized film 12 formed in the anodized film forming step has the pores 121. The pores 121 have an opening 123 on the flat upper surface 122 of the anodized film 12 on the opposite side to the aluminum substrate 11. The longitudinal section along the depth direction of the pores 121 has a shape that narrows from the opening 123 of the pores 121 to the bottom 124 of the pores 121 ( Figure 5 ).

[0261] The two or more anodizing treatments and pore enlargement treatments in the anodized film forming step can precisely control the wall thickness between pores. Therefore, the last treatment is preferably the pore enlargement treatment.

[0262] By adjusting the number and conditions of the anodizing treatment and the pore enlarging treatment, the number of stages of the shape that gradually narrows from the opening 123 of the pore to the bottom 124 of the pore, the smoothness of the shape, etc. can be adjusted. More specifically, by setting the duration of the pore enlarging treatment, which is the final treatment, to a different duration from the duration of the pore enlarging treatment in the preceding repeated treatments, the longitudinal cross-sectional shape of the pore 121 can be formed into a bell-shaped shape in which the longitudinal cross-section along the depth direction of the pore 121 gradually narrows from the opening 123 of the pore 121 to the bottom 124 of the pore 121, and the pore diameter of the pore 121 decreases, and the inner surface of the pore 121 changes in a curved line. More specifically, the process of performing anodizing treatment and then pore enlargement treatment is repeated n times, and by making the treatment time of the nth pore enlargement treatment longer than the treatment time of the pore enlargement treatment from the 1st to the (n-1)th times, the longitudinal cross-sectional shape of the pore 121 is preferably such that the pore diameter on the bottom 124 side of the pore 121 decreases relatively sharply compared with the pore diameter on the opening 123 side of the pore 121 in the pore depth direction from the opening 123 of the pore 121. The pore diameter becomes a bell shape in which the inner surface of the pore 121 changes curvedly, which is preferred.

[0263] Furthermore, it is preferable to perform anodizing treatment at a constant voltage for a long time to form an oxide film, temporarily remove the oxide film, and perform anodizing treatment again under the same conditions to obtain the aforementioned pores 121 having a high pore arrangement regularity.

[0264] The anodizing treatment is a treatment in which an aluminum substrate is immersed in an aqueous solution of one or more acids selected from the group consisting of chromic acid, citric acid, oxalic acid, and sulfuric acid, i.e., an electrolyte, and a constant current is passed through the solution to form a porous oxide film on the surface of the aluminum substrate. The concentration of the electrolyte is not particularly limited, but is, for example, in the range of 0.01 to 1.0 M.

[0265] As the electrolyte used in the anodizing treatment, a solution containing citric acid, oxalic acid, or sulfuric acid is preferred because it can produce the pores 121 having a high pore arrangement regularity. The chemical conversion voltage of the anodizing treatment is preferably 30 V to 60 V when an oxalic acid solution is used as the electrolyte, or 25 V to 30 V when a sulfuric acid solution is used as the electrolyte, because it can produce the pores 121 having a high pore arrangement regularity.

[0266] Before the first anodizing treatment, fine depressions are formed on the surface of the aluminum substrate, which can also serve as pore generation points during anodizing. This is preferred because it allows the formation of pores 121 with random arrangements.

[0267] The pore enlargement treatment is a treatment that enlarges the pores formed by the anodizing treatment. This pore enlargement treatment can be performed, for example, by immersing the anodized aluminum substrate in an aqueous solution of one or more acids selected from the group consisting of sulfuric acid, phosphoric acid, chromic acid, oxalic acid, and sulfamic acid for a predetermined period of time. Conditions for this pore enlargement treatment include, for example, a concentration of the aqueous acid solution in the range of 1.0 to 20% by weight, a temperature of 20 to 60°C, and an immersion time in the range of 30 seconds to 60 minutes.

[0268] The water-repellent layer forming step is a step of forming the water-repellent layer 13 along the surface of the anodic oxide film 12 obtained in the anodic oxide film forming step that is opposite to the aluminum substrate 11 , that is, along the flat upper surface 122 of the anodic oxide film 12 and the inner surface of the pores 121 .

[0269] In the aforementioned water-repellent layer forming step, the method for forming the aforementioned water-repellent layer 13 along the surface of the aforementioned anodized film 12 on the opposite side to the aforementioned aluminum substrate 11 is not particularly limited, and the following method can be used as an example: dissolving the aforementioned low surface energy substance in a solvent to prepare a low surface energy substance solution, and bringing the low surface energy substance solution into contact with the aforementioned anodized film 12.

[0270] The method for bringing the low surface energy substance solution into contact with the aforementioned anodized coating 12 is not particularly limited, and the following methods can be exemplified: a method of immersing the aforementioned anodized coating 12 in the aforementioned low surface energy substance solution; a method of coating the aforementioned low surface energy substance solution on the aforementioned anodized coating 12, but a method of immersing the aforementioned anodized coating 12 in the aforementioned low surface energy substance solution is preferred.

[0271] Examples of solvents used in the low surface energy material solution include fluorinated aromatic hydrocarbon solvents such as 1,3-bis(trifluoromethyl)benzene and trifluorotoluene; perfluorocarbon solvents with 3 to 12 carbon atoms such as perfluorohexane and perfluoromethylcyclohexane; hydrofluorocarbon solvents such as 1,1,2,2,3,3,4-heptafluorocyclopentane and 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorooctane; hydrofluoroether solvents such as C3F7OCH3, C4F9OCH3, C4F9OC2H5, and C2F5CF(OCH3)C3F7; and perfluoropolyether compounds such as Fomblin, Galden (manufactured by Solvay), Demnum (manufactured by Daikin Industries, Ltd.), and Krytox (manufactured by Chemours). In addition to the above solvents, water, alcoholic solvents, ketone solvents, and ester solvents can also be used. The solvent used in the low surface energy substance solution may be used alone or in combination of two or more.

[0272] As the lower limit of the concentration of the aforementioned low-surface energy substance in the aforementioned low-surface energy substance solution, for example, be more than 0.01 mass %, preferably more than 0.1 mass %.As the upper limit of the concentration of the aforementioned low-surface energy substance in the aforementioned low-surface energy substance solution, for example, be below 10 mass %, preferably below 5 mass %.

[0273] After the above-mentioned anodized coating 12 is contacted with the above-mentioned low surface energy substance solution, it is placed at room temperature for a few minutes, for example, and the drying temperature is set to a range of, for example, 40 to 200° C., preferably a range of 40 to 150° C., and the drying time is set to a range of, for example, 5 to 60 minutes, preferably a range of 30 to 60 minutes, so that the above-mentioned water-repellent layer 13 can be obtained.

[0274] Example

[0275] The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereto. It should be noted that "parts" or "%" are used in the Examples, but unless otherwise specified, they represent "parts by mass" or "mass %".

[0276] <Preparation of Low Surface Energy Material (Silane Compound Containing Poly(perfluoroalkylene ether) Chain) Solution>

[0277] [Synthesis example 1]

[0278] In a glass flask equipped with a stirrer, a thermometer, a condenser, and a dropping device, 60.62 g of 1,3-bis(trifluoromethyl)benzene, 87.6 g of Krytox157FS(H) manufactured by Chemours, represented by the following general formula,

[0279]

[0280] (In the formula, r represents the number of repetitions, the average is 43.)

[0281] 3.33 g of γ-glycidoxypropyltrimethoxysilane and 0.273 g of triphenylphosphine as a reaction catalyst were stirred under a nitrogen stream, heated to 105°C, and reacted for about 5 hours. The mixture was then cooled to 50°C, and 33.33 g of C4F9OC2H5, 3.02 g of 3-isocyanatepropyltrimethoxysilane, and 0.047 g of tin octoate as a urethanization catalyst were added. Stirring was then started under a nitrogen stream, and the mixture was reacted at 70°C for about 4 hours to obtain a reactant. The reactant was diluted with C4F9OC2H5 so that the solvent content in the obtained reactant was 80%. The diluted reactant was filtered and purified using a polytetrafluoroethylene (PTFE) filter with a pore size of 1 μm to obtain a solution containing a poly(perfluoroalkylene ether) chain-containing silane compound (1) represented by the following general formula.

[0282]

[0283] [Synthesis example 2]

[0284] In a glass flask equipped with a stirring device, a thermometer, a condenser, and a dropping device, 20 g of an alcohol having a poly(perfluoroalkylene ether) chain represented by the following general formula was added.

[0285]

[0286] (Where, l is the number of repetitions, the average is 19. m is the number of repetitions, the average is 19.)

[0287] 20 g of hydrofluoroether (C4F9OC2H5) as a solvent and 0.006 g of tin octoate as a urethanization catalyst were stirred under a nitrogen stream, and 1.31 g of 3-isocyanatepropyltrimethoxysilane was added dropwise over 15 minutes while maintaining the temperature at 50°C. After the addition was completed, the mixture was stirred at 50°C for 6 hours to allow the alcohol and 3-isocyanatepropyltrimethoxysilane to react, thereby obtaining a reactant. IR spectroscopy was performed on the obtained reactant to confirm the disappearance of the isocyanate group in the reactant, confirming that compound (2) represented by the following general formula was obtained.

[0288]

[0289] The reaction solution was diluted with hydrofluoroether (C4F9OC2H5) to a solvent concentration of 80% by mass. The diluted reaction solution was filtered and purified using a polytetrafluoroethylene (PTFE) filter with a pore size of 0.2 μm to obtain a hydrofluoroether solution containing the poly(perfluoroalkylene ether) chain-containing silane compound (2).

[0290] <Preparation of an Anodic Oxide-Coated Aluminum Substrate>

[0291] Production Example 1

[0292] An aluminum plate with a purity of 99.99% was anodized using a 0.2M aqueous citric acid solution as the electrolyte at a chemical conversion voltage of 350V at 17°C for 2 minutes. The plate was then immersed in a 10wt% aqueous phosphoric acid solution at 50°C for 20 minutes to increase its pore size. This process was repeated five times, resulting in an aluminum material (A) having an anodized film with a pore period of 850nm. Figure 6 The scanning electron microscope (SEM) photograph of the upper surface of the obtained aluminum material (A) is shown in FIG. Figure 7 This is a SEM photo of the cross section of the aluminum material (A). Figure 6 and Figure 7 It was confirmed that fine concavo-convex shapes were formed on the surface of the anodic oxide film of the aluminum material (A).

[0293] Production Example 2

[0294] For an aluminum plate with a purity of 99.50%, a 0.3M oxalic acid aqueous solution was used as an electrolyte and anodized for 30 seconds at a chemical conversion voltage of 40V. Afterwards, it was immersed in a 5wt% phosphoric acid aqueous solution at 30°C for 12 minutes to implement a pore enlargement treatment. This operation was repeated 5 times to obtain an aluminum material (B) having an anodized film with a pore period of 100nm. The surface of the obtained aluminum material (B) was observed with a scanning electron microscope, and the results confirmed that fine concave and convex shapes were formed on the surface of the anodized film of the aluminum material (B).

[0295] Production Example 3

[0296] For an aluminum plate with a purity of 99.50%, a 0.05M oxalic acid aqueous solution was used as an electrolyte and anodized for 50 seconds at a chemical conversion voltage of 80V. Afterwards, it was immersed in a 5wt% phosphoric acid aqueous solution at 30°C for 30 minutes to implement a pore enlargement treatment. This operation was repeated 5 times to obtain an aluminum material (C) having an anodized film with a pore period of 200nm. The surface of the obtained aluminum material (C) was observed with a scanning electron microscope, and the results confirmed that fine concave and convex shapes were formed on the surface of the anodized film of the aluminum material (C).

[0297] Production Example 4

[0298] For an aluminum plate with a purity of 99.50%, a 0.1M phosphoric acid aqueous solution was used as an electrolyte and anodized for 5 minutes at a chemical conversion voltage of 200V. After that, it was immersed in a 10wt% phosphoric acid aqueous solution at 30°C for 60 minutes to implement pore enlargement treatment. This operation was repeated 4 times, and anodized for 5 minutes under the same conditions to obtain an aluminum material (D) having an anodized film with a pore period of 500nm. The surface of the obtained aluminum material (D) was observed with a scanning electron microscope, and the results confirmed that fine concave and convex shapes were formed on the surface of the anodized film of the aluminum material (D).

[0299] Production Example 5

[0300] For an aluminum plate with a purity of 99.50%, a 0.2M citric acid aqueous solution was used as an electrolyte and anodized for 10 minutes at a chemical conversion voltage of 350V. After that, it was immersed in a 10wt% phosphoric acid aqueous solution at 50°C for 20 minutes to implement a pore enlargement treatment. This operation was repeated 5 times to obtain an aluminum material (E) having an anodized film with a pore period of 850nm. The surface of the obtained aluminum material (E) was observed with a scanning electron microscope, and the results confirmed that fine concave and convex shapes were formed on the surface of the anodized film of the aluminum material (E).

[0301] Production Example 6

[0302] An aluminum plate with a purity of 99.50% was anodized for 10 minutes at a chemical conversion voltage of 400 V using a 0.2 M aqueous citric acid solution as the electrolyte. The plate was then immersed in a 10 wt % aqueous phosphoric acid solution at 50°C for 20 minutes to increase its pore size. This process was repeated five times, resulting in an aluminum material (F) having an anodized film with a pore period of 1000 nm.

[0303] Production Example 7

[0304] For an aluminum plate with a purity of 99.50%, a 0.3M oxalic acid aqueous solution was used as an electrolyte and anodized for 75 seconds at a chemical conversion voltage of 40V. Afterwards, it was immersed in a 5wt% phosphoric acid aqueous solution at 30°C for 30 minutes to implement a pore enlargement treatment. This operation was repeated twice to obtain an aluminum material (G) having an anodized film with a pore period of 100nm. The surface of the obtained aluminum material (G) was observed with a scanning electron microscope, and the results confirmed that fine concave and convex shapes were formed on the surface of the anodized film of the aluminum material (G).

[0305] Production Example 8

[0306] An aluminum plate with a purity of 99.50% was anodized for 250 seconds using a 0.3M oxalic acid aqueous solution as the electrolyte at a chemical conversion voltage of 80V. The plate was then immersed in a 5wt% phosphoric acid aqueous solution at 30°C for 75 minutes to increase its pore size. This process was repeated twice, resulting in an aluminum material (H) having an anodized film with a pore period of 200nm.

[0307] Comparative Manufacturing Example 1

[0308] An aluminum plate with a purity of 99.50% was immersed in a 0.5% aqueous sodium hydroxide solution for 10 minutes, and then washed with water and methanol. The obtained aluminum plate was then immersed in a solution of the silane compound (2) of Synthesis Example 2 and allowed to stand for 1 hour. The aluminum plate was then removed and dried at 150° C. for 30 minutes to obtain aluminum material (I).

[0309] Comparative Manufacturing Example 2

[0310] An aluminum plate with a purity of 99.50% was immersed in a 5% triethanolamine aqueous solution at 90°C for 10 minutes, and then washed with water and methanol. The obtained aluminum plate was immersed in a solution of the silane compound (2) of Synthesis Example 2 and allowed to stand for 1 hour. The aluminum plate was then removed and dried at 150°C for 30 minutes to obtain an aluminum material (J).

[0311] Comparative Manufacturing Example 3

[0312] An aluminum plate with a purity of 99.99% was anodized at 17°C for 10 minutes using a 0.2M citric acid aqueous solution as an electrolyte at a chemical conversion voltage of 350 V. The plate was then immersed in a 10% by mass phosphoric acid aqueous solution at 50°C for 40 minutes to perform a pore enlargement treatment, thereby obtaining an aluminum material (K). Figure 8 This is a SEM photograph of the upper surface of the obtained aluminum material (K). Figure 9 This is a SEM photo of the cross section of the aluminum material (K). Figure 8 It was confirmed that fine concavo-convex shapes were formed on the surface of the anodic oxide film of the aluminum material (K), but Figure 9 It was confirmed that the longitudinal cross section along the depth direction of the pore did not have a shape that narrowed from the opening of the pore toward the bottom of the pore.

[0313] Comparative Manufacturing Example 4

[0314] An aluminum plate with a purity of 99.99% was anodized using a 0.2 M oxalic acid aqueous solution as an electrolyte at a chemical conversion voltage of 350 V at 17° C. for 10 minutes to obtain an aluminum material (L). Figure 10 This is a SEM photograph of the upper surface of the obtained aluminum material (L). Figure 11 This is a SEM photo of the cross section of the aluminum material (L). Figure 10 and Figure 11 It was confirmed that fine concavo-convex shapes were formed on the surface of the anodic oxide film of the aluminum material (L), but the flat upper surface was damaged.

[0315] Comparative Manufacturing Example 5

[0316] An aluminum plate with a purity of 99.50% was anodized for 15 seconds using a 0.3 M oxalic acid aqueous solution as an electrolyte at a chemical conversion voltage of 40 V. The plate was then immersed in a 5 mass % phosphoric acid aqueous solution at 30° C. for 3 minutes to perform pore enlargement treatment, thereby obtaining an aluminum material (M). Figure 12 This is a SEM photograph of the upper surface of the obtained aluminum material (M). Figure 13 This is a SEM photo of the cross section of the aluminum material (M). Figure 12 and Figure 13 It was confirmed that fine irregularities were formed on the surface of the anodic oxide film of the aluminum material (M), but the flat upper surface was damaged, and the longitudinal cross section along the depth direction of the pores did not have a shape that narrowed from the pore opening to the pore bottom.

[0317] Comparative Production Example 6

[0318] An aluminum plate with a purity of 99.50% was anodized for 15 seconds using a 0.3 M oxalic acid aqueous solution as an electrolyte at a chemical conversion voltage of 40 V to obtain an aluminum material (N). Figure 14 This is a SEM photograph of the upper surface of the obtained aluminum material (N). Figure 15 This is a SEM photo of the cross section of the aluminum material (N). Figure 14 and Figure 15 It was confirmed that fine concavo-convex shapes were formed on the surface of the anodic oxide coating of the aluminum material (N), but the cut surface did not have a shape that narrowed from the opening of the pore toward the bottom of the pore.

[0319] Comparative Production Example 7

[0320] For an aluminum plate with a purity of 99.50%, the 2 Next, the aluminum plate was immersed in a 5% phosphoric acid aqueous solution at 50° C. to perform a dissolution treatment, thereby obtaining an aluminum material (O). Figure 16 This is a SEM photograph of the upper surface of the obtained aluminum material (O). Figure 17 This is a SEM photo of the cross section of the aluminum material (O). Figure 16 and Figure 17 It was confirmed that in the aluminum material (O), a layer having fine pores was formed by anodic oxidation, but the surface of the anodic oxide film did not have a flat upper surface, and the partition walls that further partitioned the fine pores collapsed and overlapped.

[0321] Each of the aluminum materials produced above was subjected to the following treatment to form a water-repellent layer.

[0322] [Formation of water-repellent layer 1]

[0323] C4F9OC2H5 was added to the solution of the silane compound (1) in Synthesis Example 1 to prepare a 0.1% by mass solution of the silane compound (1). The aluminum materials (A) to (H) were immersed in the 0.1% by mass solution of the silane compound (1) and allowed to stand for 1 hour. Each plate was then removed and dried at 150°C for 30 minutes to obtain water-repellent aluminum materials (A)' to (H)' having a water-repellent layer.

[0324] [Formation of water-repellent layer 2]

[0325] C4F9OC2H5 was added to the solution of the silane compound (2) in Synthesis Example 2 to prepare a 0.1% by mass solution of the silane compound (2). The aluminum materials (A) to (F) were immersed in the 0.1% by mass solution of the silane compound (2) and allowed to stand for 1 hour. Each plate was then removed and dried at 150°C for 30 minutes to obtain water-repellent aluminum materials (A)" to (F)" having a water-repellent layer.

[0326] [Formation of water-repellent layer 3]

[0327] Butyl acetate was added to dodecylmethoxysilane to prepare a 0.1% by mass dodecylmethoxysilane-butyl acetate solution. The aluminum material (B) was immersed in the 0.1% by mass dodecylmethoxysilane-butyl acetate solution and allowed to stand for 1 hour. The plate was then removed and dried at 150°C for 30 minutes to obtain aluminum material (B).

[0328] [Formation of water-repellent layer 4]

[0329] The aluminum materials (K) to (O) were immersed in a hydrofluoroether solution containing the poly(perfluoroalkylene ether) chain-containing silane compound (1) of Synthesis Example 1 and allowed to stand for 1 hour. The plates were then removed and dried at 150° C. for 30 minutes to obtain aluminum materials (K)′ to (O)′.

[0330] [Formation of water-repellent layer 5]

[0331] The aluminum materials (K) to (N) were immersed in a 0.1 mass % solution of the silane compound (2) and allowed to stand for 1 hour. The plates were then removed and dried at 150°C for 30 minutes to obtain aluminum materials (K)" to (N)".

[0332] Examples 1 to 8 and Comparative Examples 1 to 8

[0333] The following evaluations were performed on each of the obtained aluminum materials. The evaluation results are shown in Tables 1 to 3. It should be noted that in the water fall angle measurement, in the case of aluminum material G, water did not fall, and most of the water remained on the aluminum material. Furthermore, in the running water durability test, for aluminum materials G, M', and N', the water did not fall after running water for 1 hour. Furthermore, for aluminum material O', the water did not fall after running water for 66 hours.

[0334] Evaluation Method

[0335] 〔Water contact angle measurement〕

[0336] The water repellency was evaluated by measuring the contact angle of water. It should be noted that the contact angle was evaluated using a DM-500 manufactured by Kyowa Interface Science Co., Ltd. A 5 μL drop of water was dripped onto the substrate, and the angle was taken as the value. The measurement was performed three times, and the average value was taken as the value.

[0337] 〔Measurement of water fall angle〕

[0338] Water sliding properties were evaluated by measuring the water's sliding angle. The sliding angle was evaluated using the DM-500 manufactured by Kyowa Interface Science Co., Ltd. A 5 μL drop of water was placed on the substrate, and the stage was tilted at a rate of 2 degrees / second. The angle at which the water droplet began to move was taken as the sliding angle. The measurement was performed three times, and the average value was used as the value.

[0339] 〔Running water durability〕

[0340] After measuring the water fall angle of each aluminum material, water was flowed from a tube with an inner diameter of 1 mm at a rate of 9.9 mL / min onto the portion where the water fall angle was measured, and changes in the water fall angle were measured at predetermined time intervals.

[0341] [Table 1]

[0342]

[0343] [Table 2]

[0344]

[0345] [Table 3]

[0346]

[0347] The results in Tables 1 to 3 clearly show that the water-repellent aluminum materials of Examples are excellent in water repellency, water sliding properties, and water running durability. On the other hand, the aluminum materials of Comparative Examples are found to be inferior in water repellency, water sliding properties, and water running durability, and therefore cannot solve the problems of the present invention.

Claims

1. A water-repellent aluminum material comprising: an aluminum substrate; an anodic oxide film formed on the aluminum substrate; and a water-repellent layer formed along a surface of the anodic oxide film opposite to the aluminum substrate. The anodized film has a plurality of pores, and the pores have openings on the flat upper surface of the anodized film opposite to the aluminum substrate. A longitudinal cross section along the depth direction of the pore has a shape that narrows from the opening of the pore toward the bottom of the pore, The water-repellent layer comprises a low surface energy substance, The low surface energy substance is one or more selected from the group consisting of compounds represented by the following formulas (2-1) to (2-4), compounds represented by the following formula (3), compounds represented by the following formulas (4-1) to (4-3), and compounds represented by the following formulas (5-1) to (5-3). In the formulas (2-1), (2-2), (2-3) and (2-4), r is an integer representing the number of repetitions, R 21 is an alkylene group having 1 to 6 carbon atoms, R 23 is a divalent linking group, Z is a trivalent linking group, Q is independently an organic group or a silyl group represented by -Si(A)3, and at least one of the two Qs is a silyl group represented by Si(A)3, The three As of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three As is a hydrolyzable group. In the formula (3), PFPE is a poly(perfluoroalkylene ether) chain. Y 1 and Y 2 are each independently a direct bond or a divalent linking group, Z 1 and Z 2 are each independently a divalent linking group, The three As of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, at least one of the three As is a hydrolyzable group, and the two silyl groups represented by Si(A)3 may be the same or different. In the formulas (4-1), (4-2) and (4-3), r is an integer representing the number of repetitions, R 41 is an alkylene group having 1 to 6 carbon atoms, R 42 is an alkyleneaminoalkylene or an alkylenethioalkylene, The three As of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three As is a hydrolyzable group. In the formulas (5-1), (5-2) and (5-3), l is an integer representing the number of repetitions, m is an integer representing the number of repetitions, R 51 is an alkylene group having 1 to 6 carbon atoms, R 52 is an alkyleneaminoalkylene or an alkylenethioalkylene, The three As of the silyl group represented by Si(A) 3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three As is a hydrolyzable group.

2. The water-repellent aluminum material according to claim 1, wherein The shape that narrows from the opening of the pore toward the bottom of the pore is a shape that narrows in steps from the opening of the pore toward the bottom of the pore.

3. The water-repellent aluminum material according to claim 1 or 2, wherein The pores are formed by sequentially performing anodizing treatment and pore enlarging treatment on the surface of the aluminum substrate two or more times.

4. The water-repellent aluminum material according to claim 1 or 2, wherein The pore period of the pores is in the range of 100 nm to 1000 nm.

5. The water-repellent aluminum material according to claim 1 or 2, wherein The thickness of the water-repellent layer is in the range of 1 nm to 100 nm.

6. The water-repellent aluminum material according to claim 1 or 2, wherein The low surface energy substance is a compound having one or more water-repellent groups selected from the group consisting of a fluorine-containing group, a silicone-containing group, and a hydrocarbon group, and one or more alumina-reactive groups selected from the group consisting of a thioether group, a mercapto group, an amino group, a sulfonyl group, a hydroxyl group, a carboxyl group, a phosphoric acid-containing group, and an alkoxysilyl group.

7. A method for manufacturing a water-repellent aluminum material, comprising the following steps: an anodic oxide film forming step, sequentially performing two or more anodizing treatments to form an anodic oxide film and pores by anodizing the surface of the aluminum substrate, and a pore enlarging treatment to enlarge the pores formed by the anodizing treatment; and a water-repellent layer forming step of forming a water-repellent layer containing a low surface energy substance along the surface of the anodic oxide film opposite to the aluminum substrate; The anodized film has a plurality of pores, and the pores have openings on the flat upper surface of the anodized film opposite to the aluminum substrate. A longitudinal cross section along the depth direction of the pore has a shape that narrows from the opening of the pore toward the bottom of the pore, The low surface energy substance is one or more selected from the group consisting of compounds represented by the following formulas (2-1) to (2-4), compounds represented by the following formula (3), compounds represented by the following formulas (4-1) to (4-3), and compounds represented by the following formulas (5-1) to (5-3). In the formulas (2-1), (2-2), (2-3) and (2-4), r is an integer representing the number of repetitions, R 21 is an alkylene group having 1 to 6 carbon atoms, R 23 is a divalent linking group, Z is a trivalent linking group, Q is independently an organic group or a silyl group represented by -Si(A)3, and at least one of the two Qs is a silyl group represented by Si(A)3, The three As of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three As is a hydrolyzable group. In the formula (3), PFPE is a poly(perfluoroalkylene ether) chain. Y 1 and Y 2 are each independently a direct bond or a divalent linking group, Z 1 and Z 2 are each independently a divalent linking group, The three As of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, at least one of the three As is a hydrolyzable group, and the two silyl groups represented by Si(A)3 may be the same or different. In the formulas (4-1), (4-2) and (4-3), r is an integer representing the number of repetitions, R 41 is an alkylene group having 1 to 6 carbon atoms, R 42 is an alkyleneaminoalkylene or an alkylenethioalkylene, The three As of the silyl group represented by Si(A)3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three As is a hydrolyzable group. In the formulas (5-1), (5-2) and (5-3), l is an integer representing the number of repetitions, m is an integer representing the number of repetitions, R 51 is an alkylene group having 1 to 6 carbon atoms, R 52 is an alkyleneaminoalkylene or an alkylenethioalkylene, The three As of the silyl group represented by Si(A) 3 are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three As is a hydrolyzable group.

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