JP7365652B2 - Water-repellent aluminum material and its manufacturing method - Google Patents

Description

The present invention relates to a water-repellent aluminum material and a method for manufacturing the same.

Heat exchangers are used in air conditioners, refrigerators, freezers, electric vehicles, etc., and conventional heat exchangers such as evaporators for refrigerators and air conditioners have been designed to be lightweight and thermally efficient. In order to meet the demands for improved performance and further compactness, various aluminum materials are used as fin materials, and designs are being adopted to make the fin spacing as narrow as possible. In such a heat exchanger, water droplets adhere to the fin surface due to condensation, and when the outdoor unit is in heating mode, the air temperature is low, so the condensed water on the fin surface becomes frost and freezes, causing ventilation resistance. There is a problem in that heat exchange efficiency decreases significantly.

In order to solve this problem, in Patent Document 1, a hydrophilic coating film is formed on the fin surface to allow water droplets adhering to the fin surface to flow off and to reduce the amount of water droplets remaining during defrosting.

However, in the technique described in Patent Document 1, since the coating film is hydrophilic, water inevitably remains, and there is a problem that frosting occurs again in a short period of time.

In contrast to hydrophilic properties, a method of imparting water repellency to aluminum fins to repel water droplets has also been studied (for example, Patent Document 2). Although water-repellent surfaces have been confirmed to be effective in delaying the formation of frost, it is difficult to remove water droplets once they have formed. That is, water repellency, ease of rolling of droplets, and ability to remove water droplets are not necessarily correlated, and therefore, there is a problem that existing water-repellent coatings do not have sufficient water sliding properties.

In order to improve water sliding properties, methods of adding unevenness to the aluminum surface by etching or using water-repellent fine particles are also being considered (for example, Patent Documents 3 and 4), but the former method does not have sufficient water sliding properties. However, the latter has problems with particle dispersion and has poor running water durability.

Japanese Patent Application Publication No. 6-300482 Japanese Patent Application Publication No. 2013-147573 JP2013-36733A Japanese Patent Application Publication No. 2013-103414

An object of the present invention is to provide a water-repellent aluminum material that has excellent water sliding properties and durability under running water and is highly practical.

Another object of the present invention is to provide a method for producing a water-repellent aluminum material that has excellent process suitability, excellent water sliding properties and running water durability, and is highly practical.

The present inventors conducted extensive studies in order to solve the above problems. As a result, it was discovered that a water-repellent aluminum material having a specific structure of an anodized film and a water-repellent layer, and a method for producing the same, have excellent process suitability, excellent water sliding properties and durability under running water, and are excellent in practicality. , we have completed the present invention.

The present invention includes an aluminum base material, an anodic oxide film formed on the aluminum base material, and a water-repellent layer formed along a surface of the anodic oxide film on a side opposite to the aluminum base material. A water-repellent aluminum material, wherein the anodic oxide coating has a plurality of pores, and the pores have openings on a flat upper surface of the anodic oxide coating on the opposite side from the aluminum base material. and the water repellent layer has a shape in which a vertical cross section along the depth direction of the pore narrows from the opening of the pore toward the bottom of the pore, and the water repellent layer contains a low surface energy substance. It is made of aluminum material.

Further, the present invention includes an anodizing treatment in which the surface of an aluminum substrate is anodized to form an anodized film and pores, and a pore diameter enlarging treatment in which the diameter of the pores formed by the anodic oxidation is expanded. an anodic oxide film forming step, which is applied twice or more in each order, and a water-repellent layer forming step, which forms a water-repellent layer containing a low surface energy substance along the surface of the anodic oxide film opposite to the aluminum base material. The anodic oxide film has a plurality of pores, and the pores have openings on a flat upper surface of the anodic oxide film opposite to the aluminum base material, and The present invention is a method for manufacturing a water-repellent aluminum material, in which a longitudinal section along the depth direction narrows from the opening of the pore toward the bottom of the pore.

According to the present invention, it is possible to provide a water-repellent aluminum material that has excellent water sliding properties and running water durability, and is highly practical.

Further, according to the present invention, it is possible to provide a method for manufacturing a water-repellent aluminum material that has excellent process suitability, excellent water sliding properties and running water durability, and is excellent in practicality.

A schematic diagram showing an example of a cross section of the water-repellent aluminum material of the present invention Schematic diagram showing processing conditions in each step of manufacturing the water-repellent aluminum material of the present invention Schematic diagram showing processing conditions in each step of manufacturing the water-repellent aluminum material of the present invention Schematic diagram showing processing conditions in each step of manufacturing the water-repellent aluminum material of the present invention Schematic diagram showing processing conditions in each step of manufacturing the water-repellent aluminum material of the present invention SEM photograph of an anodized film according to a production example of the present invention SEM photograph of the cross section of the anodic oxide film according to the production example of the present invention SEM photograph of anodized film according to comparative production example of the present invention SEM photograph of a cross section of an anodized film according to a comparative production example of the present invention SEM photograph of anodized film according to comparative production example of the present invention SEM photograph of a cross section of an anodized film according to a comparative production example of the present invention SEM photograph of anodized film according to comparative production example of the present invention SEM photograph of a cross section of an anodized film according to a comparative production example of the present invention SEM photograph of anodized film according to comparative production example of the present invention SEM photograph of a cross section of an anodized film according to a comparative production example of the present invention SEM photograph of anodized film according to comparative production example of the present invention SEM photograph of a cross section of an anodized film according to a comparative production example of the present invention

A water-repellent aluminum material according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram of a cross section in the depth direction of the water-repellent aluminum material 1 of this embodiment.

The water-repellent aluminum material 1 includes an aluminum base material 11, an anodic oxide film 12 formed on the aluminum base material 11, and a surface of the anodic oxide film 12 on the side opposite to the aluminum base material 11. It has a water repellent layer 13 formed thereon. The anodic oxide film 12 has a plurality of pores 121, each of the pores 121 has an opening 123 on a flat upper surface 122 of the anodic oxide film 12 on the side opposite to the aluminum base material 11, and The longitudinal section of the pore 121 along the depth direction has a shape that narrows from the opening 123 of the pore 121 toward the bottom 124 of the pore 121 . In this embodiment, "the surface opposite to the aluminum base material 11" on which the water-repellent layer 13 is formed includes a flat upper surface 122 having an opening 123 and an inner surface of the pore 121. Therefore, the water-repellent layer 13 is formed along the flat upper surface 122 and the inner surface of the pore 121. The water repellent layer 13 contains a low surface energy substance. The water-repellent aluminum material 1 has excellent water sliding properties and running water durability, and is excellent in practicality.

The aluminum constituting the aluminum base material 11 is not particularly limited as long as it is aluminum. From the viewpoint of the influence of impurities present in aluminum, the aluminum purity of the aluminum base material is preferably 99.00% by mass or more, more preferably 99.50% by mass or more, and even more preferably 99.90% by mass or more.

The shape narrowing from the opening 123 of the pore toward the bottom 124 of the pore has a gradual shape from the opening 123 toward the bottom 124 of the pore, since it can provide durability in addition to super-smoothness. It is preferable to have a narrow shape. By adopting this shape, the area of the portion that comes into contact with water droplets can be reduced, and the shape can also be maintained, that is, durability can be imparted. In FIG. 1, the shape narrowing from the opening 123 of the pore toward the bottom 124 of the pore is one step narrower, but it may be narrower by two steps or more. Further, the shape that gradually narrows from the opening 123 of the pore toward the bottom 124 of the pore may be a smooth shape. Further, the shape narrowing from the opening 123 of the pore 121 toward the bottom 124 of the pore 121 is a bell shape that narrows in a curve from the opening 123 of the pore 121 toward the bottom 124 of the pore 121. It may be a shape.

The shape of the pores 121 is formed by subjecting the surface of the aluminum base material to anodizing treatment and pore diameter enlarging treatment two or more times each. The more times the anodizing treatment and the pore diameter enlargement treatment are performed, the smoother the shape that narrows from the opening 123 of the pore 121 toward the bottom 124 of the pore 121 tends to become. Therefore, by adjusting the number of times of anodization treatment and pore diameter enlargement treatment, the shape of the pore 121 narrowing from the opening 123 toward the bottom 124 of the pore 121 can be adjusted.

The lower limit of the pore period P of the pores 121 is preferably 100 nm or more, since it is advantageous to exhibit superhydrophobicity if the distance between the points in contact with water droplets is ensured. Further, the upper limit of the pore period P is preferably 1000 nm or less, and more preferably 200 nm or less from the viewpoint of productivity. Note that the pore period P means the distance between the center of a pore 121 and the center of the adjacent pore 121. The pore period P is measured by the method described in Examples.

The pore depth D of the pores 121 is preferably in the range of 100 nm or more and 1000 nm or less from the viewpoint of ensuring durability under running water. Note that the pore depth D means the depth from the flat top surface 122 to the bottom 124.

The low surface energy substance contained in the water-repellent layer 13 is a substance whose surface free energy is lower than that of water, and includes, for example, one or more types selected from the group consisting of fluorine-containing groups, silicone-containing groups, and hydrocarbon groups. A compound having a water-repellent group and one or more aluminum oxide reactive groups selected from the group consisting of sulfide, thiol group, amino group, sulfonyl group, hydroxyl group, carboxyl group, phosphoric acid-containing group, and alkoxysilyl group. be. 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. can be mentioned.

The low surface energy substance is preferably a fluorine-containing compound having a perfluoroalkyl group and/or a perfluoropolyether group from the viewpoint of exhibiting superior superhydrophobicity, and is preferably a fluorine-containing _compound having a perfluoroalkyl group and _{/or a perfluoropolyether} group. Alkyl group (n is an integer of 1 or more), perfluoropolyether group represented by F(C _n F _2n O) _m (n is an integer of 1 or more, m is an integer indicating the number of repeats) ), and a perfluoropolyether group represented by CF ₃ O (C _n F _2n O) _m (n is an integer of 1 or more, m is an integer indicating the number of repeats) one or more types, and a silyl group represented by Si(A) ₃ (the three A's are each independently a hydrolyzable group or a non-hydrolyzable group, and at least one of the three A's is a hydrolyzable group) A fluorine-containing compound having a group) is more preferable.

In the perfluoroalkyl group represented by C _n F _2n+1 , n is preferably in the range of 1 to 6.

In the perfluoropolyether group represented by F(C _n F _2n O) _m , n is preferably in the range of 1 to 6, more preferably in the range of 1 to 3, and m is, for example, on average 5 -100, preferably 8-80 on average, more preferably 10-60 on average.

In the perfluoropolyether group represented by CF ₃ O(C _n F _2n O) _m , n is preferably in the range of 1 to 6, more preferably in the range of 1 to 3, and m is, for example, The average value is in the range of 5 to 100, preferably the average value is in the range of 8 to 80, and more preferably the average value is in the range of 10 to 60.

The fluorine-containing compound may include a perfluoropolyether chain represented by (C _n F _2n O) _m (n is an integer of 1 or more, and m is an integer indicating the number of repeats).

Examples of the hydrolyzable group include alkoxy groups such as methoxy, ethoxy, and propoxy groups; alkoxy-substituted alkoxy groups such as methoxyethoxy; acyloxy groups such as acetoxy, propionyloxy, and benzoyloxy; Alkenyloxy groups such as propenyloxy group and isobutenyloxy group; imineoxy groups such as dimethylketoxime group, methylethylketoxime group, diethylketoxime group, and cyclohexaneoxime group; methylamino group, ethylamino group, dimethylamino group, diethylamino group Substituted amino groups such as groups; amide groups such as N-methylacetamide groups and N-ethylamide groups; substituted aminooxy groups such as dimethylaminooxy groups and diethylaminooxy groups; halogens such as chlorine; and the like. Among these hydrolyzable groups, alkoxy groups are preferred because they have a high rate of hydrolysis and can quickly form a coating with excellent durability, and alkoxy groups having 1 to 6 carbon atoms are more preferred; 1 to 3 alkoxy groups are more preferred, methoxy groups and ethoxy groups are particularly preferred, and methoxy groups are most preferred.

Examples of the non-hydrolyzable group include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. Examples include aralkyl groups ranging from 7 to 20. Among these non-hydrolyzable groups, alkyl groups having 1 to 3 carbon atoms are preferred because they can avoid steric hindrance and increase the rate of hydrolysis, resulting in rapid formation of a highly durable coating. A methyl group is more preferred.

The number of hydrolyzable groups in the silyl group represented by Si(A) ₃ is at least one, preferably two or more because a more durable coating can be formed, and all three are hydrolyzable groups. It is more preferable. In addition, when there are two or more hydrolyzable groups in the silyl group represented by Si(A) ₃ , the two or more hydrolyzable groups may be the same or different from each other. Furthermore, when there are two or more silyl groups represented by Si(A) ₃ , it is sufficient that at least one silyl group represented by Si(A) ₃ has a hydrolyzable group. Similarly, when there are two or more non-hydrolyzable groups in the silyl group represented by Si(A) ₃ , the two or more non-hydrolyzable groups may be the same or different.

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

(In the above formulas (1-1) and (1-2),
Rf is each independently a perfluoroalkyl group represented by C _n F _2n+1 (n is an integer of 1 or more).
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. .
X is any of the linking groups represented by the following formulas (X-1) to (X-11). )

(In the above formulas (X-1) to (X-11),
Rf is a perfluoroalkyl group represented by C _n F _2n+1 (n is an integer of 1 or more).
R ¹¹ is a direct bond or an alkylene group having 1 to 6 carbon atoms.
When there is a plurality of R ^11s , the plurality of R ^11s may be the same or different from each other.
R ¹² is an alkyl group having 1 to 6 carbon atoms. )

In formulas (1-1) and (1-2), the preferred forms of the perfluoroalkyl group represented by C _n F _2n+1 and the silyl group represented by Si(A) ₃ are as described above, respectively. .

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

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

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

(In the above formulas (2-1), (2-2), (2-3) and (2-4),
r is an integer indicating the number of repetitions.
R ²¹ is an alkylene group having from 1 to 6 carbon atoms.
R ²³ is a divalent linking group.
Z is a trivalent linking group.
Q is each independently an organic group or a silyl group represented by -Si(A) ₃ , and at least one of the two B's is a silyl group represented by Si(A) ₃ .
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. . )

In formulas (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, and 8 to 80 on average. A range of 10 to 60 on average is even more preferred.

In formulas (2-1), (2-2), (2-3) and (2-4), the alkylene group having 1 to 6 carbon atoms for R ²¹ is preferably an alkylene group having 3 carbon atoms. .

In formulas (2-1), (2-2), (2-3) and (2-4), the preferred form of the silyl group represented by Si(A) ₃ is as described above.

In formulas (2-1) and (2-2), when Q is an organic group, examples of the organic group include substituted or unsubstituted alkyl groups, alkenyl groups, phenyl groups, and the like.
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, a perfluoroalkyl group having 1 to 6 carbon atoms, and the like.

In formulas (2-1), (2-2), (2-3) and (2-4), the divalent linking group for R ²³ is a linking group represented by the following formula (R-1). , or a linking group represented by the following formula (R-2) is preferable.

(In the formulas (R-1) and (R-2),
R ²⁴ is an alkylene group having 1 to 3 carbon atoms.
R ²⁵ is a direct bond or an alkylene group having 1 to 6 carbon atoms.
^R26 is an alkylene group having 1 to 5 carbon atoms)

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

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

The linking groups represented by formulas (R-1) and (R-2) include formulas (R-1-1), (R-1-3), (R-1-4), (R-2- 5), (R-2-6), and (R-2-8) are preferable, and the linking groups represented by formulas (R-1-3) and (R-1-4) are preferable. More preferred.

The trivalent linking group for Z in formulas (2-2) and (2-4) is preferably a trivalent cycloaliphatic group having 4 to 8 carbon atoms, more preferably a trivalent cyclohexyl group. It is.

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

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

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

The method for producing compounds represented by formulas (2-1) and (2-2) includes, for example, a method for producing compounds represented by formulas (β-1) and (β-2) or (β-2) below. A first step of preparing a reactant having a secondary hydroxyl group derived from an epoxy group by reacting the epoxysilane compound represented by -3) with the reactant obtained in the first step and the following formula (β -4) includes a second step of reacting with the isocyanate compound represented by.

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

(In the formula (β-2) and formula (β-3),
R ²³ is a divalent linking group.
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. )

(In the above formula (β-4),
R ²¹ is an alkylene group having from 1 to 6 carbon atoms.
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. )

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

(In the above formula (β-5),
R ²³ is a divalent linking group.
G is an organic group. )

When producing the compounds represented by formulas (2-3) and (2-4), the first step may be included, and the second step may be omitted.

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

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

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

(In the formula, 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)

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

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

The method for producing a compound represented by formula (2-1), (2-2), (2-3) or (2-4) may be carried out in the presence of an organic solvent if necessary.

The organic solvent is not particularly limited as long as it can dissolve the above-mentioned compounds as raw materials, and examples include solvents such as acetone, methyl ethyl ketone, toluene, and xylene that do not have reactivity with isocyanate groups, and fluorine-based solvents. Organic solvents can be used.

Examples of the fluorine-based solvent include fluorine-containing aromatic hydrocarbon solvents such as 1,3-bis(trifluoromethyl)benzene and trifluorotoluene; and those having 3 to 3 carbon atoms such as perfluorohexane and perfluoromethylcyclohexane. 12 perfluorocarbon solvent; 1,1,2,2,3,3,4-heptafluorocyclopentane, 1,1,1,2,2,3,3,4,4,5,5,6, Hydrofluorocarbon solvents such as 6-tridecafluorooctane; C ₃ F ₇ OCH ₃ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , C ₂ F ₅ CF(OCH ₃ )C ₃ F ₇ , etc. Preferred examples include perfluoropolyether compounds such as Fomblin, Galden (manufactured by Solvay), Demnum (manufactured by Daikin Industries), and Krytox (manufactured by Chemours).

In the first step, the reaction ratio between compound (β-1) and compound (β-2) or compound (β-3) is determined by the reaction ratio between the carboxyl group of compound (β-1) and compound (β-2) or compound (β-3). The equivalent ratio (carboxyl group/epoxy group) to the epoxy group possessed by the compound (β-3) is preferably in the range of 0.5 to 1.5, and preferably in the range of 0.9 to 1.1. is more preferable, and a ratio in the range of 0.98 to 1.02 is even more preferable.

The reaction temperature in the first step is not particularly limited and is usually in the range of 50 to 150°C. Further, the reaction time is not particularly limited, and is usually in the range of 1 to 10 hours.

In the second step, the reaction ratio between the reactant having a secondary hydroxyl group derived from an epoxy group obtained in the first step and the compound (β-4) is the same as the hydroxyl group of the reactant and the compound (β-4). The equivalent ratio (hydroxyl group/isocyanate group) with the isocyanate group possessed by is preferably in the range of 0.5 to 1.5, more preferably in the range of 0.9 to 1.1, and more preferably 0.9 to 1.1. More preferably, the ratio is in the range of 98 to 1.02.

The reaction temperature in the second step is not particularly limited and is usually in the range of 30 to 120°C. Further, the reaction time is not particularly limited, and is usually in the range of 1 to 10 hours.

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

(In the above 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 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. )

The compound represented by formula (3) has a urethane bond in its skeleton. By having this urethane bond, the polarity near the hydrolyzable groups at both ends can be improved.

In formula (3), the preferred form of the silyl group represented by Si(A) ₃ is as described above.

In formula (3), examples of the divalent linking groups Y ¹ , Y ² , Z ¹ and Z ² include alkylene groups having 1 to 22 carbon atoms. Examples of the alkylene group include methylene group, ethylene group, n-propylene group, isopropylene group, butylene group, isobutylene group, sec-butylene group, tert-butylene group, 2,2-dimethylpropylene group, 2-methyl Butylene group, 2-methyl-2-butylene group, 3-methylbutylene group, 3-methyl-2-butylene group, pentylene group, 2-pentylene group, 3-pentylene group, 3-dimethyl-2-butylene group, 3 , 3-dimethylbutylene group, 3,3-dimethyl-2-butylene group, 2-ethylbutylene group, hexylene group, 2-hexylene group, 3-hexylene group, 2-methylpentylene group, 2-methyl-2- Pentylene group, 2-methyl-3-pentylene group, 3-methylpentylene group, 3-methyl-2-pentylene group, 3-methyl-3-pentylene group, 4-methylpentylene group, 4-methyl-2- Pentylene group, 2,2-dimethyl-3-pentylene group, 2,3-dimethyl-3-pentylene group, 2,4-dimethyl-3-pentylene group, 4,4-dimethyl-2-pentylene group, 3-ethyl -3-pentylene group, heptylene group, 2-heptylene group, 3-heptylene group, 2-methyl-2-hexylene group, 2-methyl-3-hexylene group, 5-methylhexylene group, 5-methyl-2- hexylene group, 2-ethylhexylene group, 6-methyl-2-heptylene group, 4-methyl-3-heptylene group, octylene group, 2-octylene group, 3-octylene group, 2-propylpentylene group, 2, Examples include alkylene groups such as 4,4-trimethylpentylene group and decaoctylene group.

The divalent linking groups Z ¹ and Z ² in formula (3) are each independently preferably an alkylene group having 1 to 10 carbon atoms, and preferably an alkylene group having 1 to 6 carbon atoms. More preferred are alkylene groups in the range of 1 to 3, even more preferred are n-propylene groups.

The divalent linking groups Y ¹ and Y ² in formula (3) 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 methylene More preferred are groups.

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

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

(In the above formula (P-1),
* is a bond.
X is a perfluoroalkylene group having 1 to 3 carbon atoms.
The plurality of perfluoroalkylene groups of X may be the same or different. In the plurality of X's, two or more types of perfluoroalkylene groups may be present randomly or in a block form.
n is the number of repetitions. For example, n ranges from 6 to 300, preferably from 12 to 200, more preferably from 20 to 150, even more preferably from 30 to 100, and most preferably from 35 to 70. )

As the perfluoroalkylene group for X, the following structures can be exemplified.

Among these, X is preferably a perfluoromethylene group (a) or a perfluoroethylene group (b). ) is more preferable.

When the perfluoromethylene group (a) and the perfluoroethylene group (b) coexist, their abundance ratio (a/b) (ratio of numbers) is preferably in the range of 1/10 to 10/1, and 3/ The range of 10 to 10/3 is more preferable.

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

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, and preferably in the range of 60 to 450. is more preferable, the range of 90 to 300 is even more preferable, and the range of 100 to 200 is most preferable.

The method for producing the compound represented by formula (3) is not particularly limited, and it can be produced by any known method. Hereinafter, one embodiment of the method for producing the compound represented by formula (3) will be described.

The compound represented by formula (3) can be produced by reacting a diol represented by formula (α-1) below with an isocyanate represented by formula (α-2) below.

(In the above formulas (α-1) and (α-2),
PFPE is a poly(perfluoroalkylene ether) chain.
Y ¹ and Y ² are each independently a direct bond or a divalent linking group.
Z is a divalent linking group.
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. )

PFPE, Y ¹ , Y ² , Z and Si(A) ₃ in formulas (α-1) and (α-2) are PFPE, Y ¹ , Y ² , Z ¹ and Z ² and Each corresponds to Si(A) ₃ .

Examples of the diol represented by the formula (α-1) include a diol represented by the following formula (α-1-1), a diol represented by the following formula (α-1-2), and the like.

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

Z in the isocyanate compounds represented by formulas (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. Preferably, 1 to 3 alkylene groups are more preferable, and n-propylene groups are particularly preferable.

During the reaction (urethanization) between the diol represented by formula (α-1) and the isocyanate represented by formula (α-2), the OH contained in the diol represented by formula (α-1) is The isocyanate represented by formula (α-2) is preferably charged in an amount of 0.5 to 1.5 mol, preferably 0.9 to 1.1 mol, per mol of the group. More preferably, the amount is in the range of 0.98 to 1.02 mol.

In order to accelerate the urethanization reaction, when reacting the diol represented by formula (α-1) with the isocyanate represented by formula (α-2), for example, tertiary amines such as triethylamine, benzyldimethylamine, etc. Amines, tin compounds such as dibutyltin dilaurylate, dioctyltin dilaurate, and tin 2-ethylhexanoate may be added as catalysts.

The amount of the catalyst added is preferably in the range of 0.001 to 5.0% by mass, more preferably in the range of 0.01 to 1.0% by mass, even more preferably in the range of 0.02 to 5.0% by mass, based on the entire reaction mixture. It is in the range of 0.2% by mass. The reaction time is preferably in the range of 1 to 10 hours.

In the reaction between 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 have no reactivity with the isocyanate group. Organic solvents such as acetone, methyl ethyl ketone, toluene, xylene; C ₄ F ₉ C ₂ H ₅ , (CF ₃ ) ₂ CFCHFCHFCF ₃ , C ₆ F ₁₃ H, C ₆ F ₁₃ C ₂ H ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H _{5 ,} C ₂ F ₅ CF(OCH ₃ )C ₃ F ₇ , HCF ₂ CF ₂ OCH ₂ CF _3, or other fluorine-based solvents may be used as the reaction solvent.

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

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

(In the above formulas (4-1), (4-2) and (4-3),
r is an integer indicating the number of repetitions.
R ⁴¹ is an alkylene group having 1 to 6 carbon atoms.
R ⁴² is an alkyleneaminoalkylene group or an alkylenethioalkylene group.
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. . )

In formulas (4-1), (4-2) and (4-3), the repeating number of r and the preferred form of the silyl group represented by Si(A) ₃ are as described above.

In formulas (4-1), (4-2) and (4-3), the alkylene group having 1 to 6 carbon atoms for R ⁴¹ is preferably an alkylene group having 3 carbon atoms.

In formulas (4-1), (4-2), and (4-3), the alkylene aminoalkylene group of R ⁴² is a group in which two alkylene groups are connected by an amino bond (-NH-), and is an alkylene amino group. An alkylene group is a group in which two alkylene groups are connected by a thio bond (-S-). Here, the alkylene groups of the alkyleneaminoalkylene group and the alkylenethioalkylene group are each independently preferably an alkylene group having 1 to 6 carbon atoms.

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

A method for producing a compound represented by formula (4-1), (4-2) or (4-3) is a method for producing a compound represented by formula (2-1), (2-2), (2-3) or (2- A method similar to the method for producing the compound represented by 4) can be adopted. For example, by reacting the alcohol represented by the following formula (γ-1) with the isocyanate compound represented by the above formula (β-4), the formula (4-1), (4-2) or ( A compound represented by 4-3) can be produced. Regarding the reaction conditions and other raw materials, the same reaction conditions and other raw materials as in the manufacturing method of the compound represented by formula (2-1), (2-2), (2-3) or (2-4) are adopted. It's good to do that.

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

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

(In the above formulas (5-1), (5-2) and (5-3),
l is an integer indicating the number of repetitions.
m is an integer indicating the number of repetitions.
R ⁵¹ is an alkylene group having from 1 to 6 carbon atoms.
R ⁵² is an alkyleneaminoalkylene group or an alkylenethioalkylene group.
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. . )

In formulas (5-1), (5-2) and (5-3), the repeating units bracketed by l and the repeating units bracketed by m are the repeating units bracketed by l and the repeating units bracketed by m. It may be a random polymerization structure of repeating units, or a block polymerization structure of repeating units bounded by l and repeating units bounded by m.

In formulas (5-1), (5-2) and (5-3), the repeating numbers of l and m and the preferred form of the silyl group represented by Si(A) ₃ are as described above. be.

In formulas (5-1), (5-2) and (5-3), the alkylene group having 1 to 6 carbon atoms for R ⁵¹ is preferably an alkylene group having 3 carbon atoms.

In formulas (5-1), (5-2), and (5-3), the alkyleneaminoalkylene group of R ⁵² is a group in which two alkylene groups are connected by an amino bond (-NH-), and is an alkylenethione group. An alkylene group is a group in which two alkylene groups are connected by a thio bond (-S-). Here, the alkylene groups of the alkyleneaminoalkylene group and the alkylenethioalkylene group are each independently preferably an alkylene group having 1 to 6 carbon atoms.

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

A method for producing a compound represented by formula (5-1), (5-2) or (5-3) is a method for producing a compound represented by formula (4-1), (4-2) or (4-3). A method similar to the method for producing the compound can be adopted.
For example, by using the alcohol represented by the following formula (δ-1) instead of the alcohol represented by the above formula (γ-1), the formula (5-1), (5-2) or (5-5 A compound represented by -3) can be produced.

(In the above formula (δ-1),
l is the number of repetitions.
m is the number of repetitions. )

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

The low surface energy substance is not limited to the above-mentioned fluorine-containing compound. The low surface energy substance can be any compound that has both a reactive group that can react with and bond to the anodic oxide film and a water-repellent group that exhibits water-repellent properties.

（前記式（６－１）及び（６－２）中、
Ｒ^６１は、それぞれ独立に、任意の陽イオンである。
Ｒ^６２は、それぞれ独立に、アルキル基であり、好ましくは炭素原子数１～６のアルキル基であり、より好ましくは炭素原子数１～３のアルキル基である。）Examples of the reactive group capable of reacting and bonding with the anodic oxide film include sulfide, thiol group, amino group, sulfonyl group, hydroxyl group, carboxyl group, phosphoric acid-containing group, and alkoxysilyl group, and more preferably the following: Examples include a monovalent or divalent phosphoric acid-containing group represented by formula (6-1) or (6-2), an alkoxysilyl group represented by formula (6-3) below, and the like.

(In the above formulas (6-1) and (6-2),
Each R ⁶¹ is independently an arbitrary cation.
Each R ⁶² is independently an alkyl group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. )

The optional cations of ^R61 include alkali metal ions such as sodium ions, potassium ions, and lithium ions; organic quaternary ions such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine; Examples include ammonium ion and ammonium ion. Among these, lithium ions, sodium ions, and organic quaternary ammonium ions are preferred.

（前記式（７）中、
Ｒ^７１は、それぞれ独立に、アルキル基であり、好ましくは炭素原子数１～６のアルキル基であり、より好ましくは炭素原子数１～３のアルキル基である。
ｎは１以上の整数である。）Examples of the water-repellent group include a hydrocarbon group represented by C _n H _2n+1 - (n is an integer of 1 or more), a group represented by the following formula (7-1), and the like.

(In the above formula (7),
Each R ⁷¹ is independently an alkyl group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms.
n is an integer of 1 or more. )

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.

The lower limit of the thickness of the water-repellent layer 13 is preferably 1 nm or more in order not to impair the thermal conductivity of aluminum. Further, the upper limit of the thickness of the water-repellent layer 13 is preferably 100 nm or less, more preferably 20 nm or less.

The contact angle of water on the surface of the water-repellent layer 13 is preferably 150° or more, more preferably 160° or more with respect to 5 μL of water droplets. Further, the sliding angle of water on the surface of the water-repellent layer 13 is preferably 10° or less, more preferably 5° or less with respect to 5 μL of water droplets. Note that in this specification, the sliding angle of water and the contact angle of water are measured by the methods described in Examples.

A method for manufacturing a water-repellent aluminum material according to an embodiment of the present invention includes an anodizing treatment in which the surface of an aluminum substrate is anodized to form an anodized film and pores, and pores formed by the anodic oxidation are an anodic oxide film forming step in which a pore diameter enlarging treatment is performed twice or more in this order, and a water repellent containing a low surface energy substance along the surface of the anodic oxide film opposite to the aluminum base material; the anodic oxide film has a plurality of pores, and the pores are formed on a flat upper surface of the anodic oxide film on a side opposite to the aluminum base material. The pore has an opening in the pore, and a vertical cross section of the pore along the depth direction narrows from the opening of the pore toward the bottom of the pore.

A method for manufacturing a water-repellent aluminum material according to an embodiment of the present invention will be described with reference to FIGS. 2 to 5. Note that the same parts as those described in the present embodiment described above are given the same reference numerals, and redundant explanation will be omitted.

2 to 5 are schematic diagrams showing processing states in each step of manufacturing the water-repellent aluminum material 1.

The anodic oxide film forming step is a step of forming an anodic oxide film 12 on the surface of the aluminum base material 11 by subjecting the surface of the aluminum base material 11 shown in FIG. It is. When anodic oxidation treatment is performed as the first treatment, an anodic oxide film 12 having pores 121' is formed on the surface of the aluminum base material 11, as shown in FIG. The pore 121' has a cylindrical shape at an initial stage. By further performing a pore diameter enlarging process on the anodic oxide film 12 in such a state, the pore diameters of the pores 121' are enlarged (FIG. 4). The anodic oxide film 12 can be formed on the aluminum base material 11 by further repeating the anodic oxidation treatment and the pore diameter enlarging treatment on the anodic oxide film 12 in the state shown in FIG. The anodic oxide film 12 formed in the anodic oxide film forming step has the pores 121, and the pores 121 are formed on the flat upper surface 122 of the anodic oxide film 12 on the opposite side from the aluminum base material 11. The pore 121 has an opening 123, and a longitudinal section along the depth direction of the pore 121 has a shape that narrows from the opening 123 of the pore 121 toward the bottom 124 of the pore 121 (FIG. 5).

Since the anodizing treatment and the pore diameter enlarging treatment performed twice or more in the anodic oxide film forming step allow precise control of the wall thickness between the pores, it is preferable that the last treatment is the pore diameter enlarging treatment.

By adjusting the number and conditions of the anodizing treatment and the pore diameter enlarging treatment, the number of stages of the shape that gradually narrows from the opening 123 of the pore toward the bottom 124 of the pore, the smoothness of the shape, etc. are adjusted. can. More specifically, the longitudinal cross-sectional shape of the pores 121 is changed by setting the time of the pore diameter enlarging process as the last process to be different from the time of the pore diameter enlarging process in the previous repeated process. , the vertical cross section of the pore 121 along the depth direction narrows from the opening 123 of the pore 121 toward the bottom 124 of the pore 121, or as the diameter of the pore 121 decreases, the pore becomes narrower. The inner surface of 121 can be shaped like a bell with a curved shape. More specifically, after performing the anodic oxidation treatment, the step of performing the pore diameter enlarging treatment is repeated n times, and the nth pore diameter enlarging treatment is performed from the first to the (n-1)th pore diameter enlarging treatment. By lengthening the treatment time, the longitudinal cross-sectional shape of the pore 121 is such that the pore diameter on the bottom 124 side of the pore 121 is smaller than that in the pore depth direction from the opening 123 of the pore 121 to the bottom 124. This is preferable because the diameter of the pore 121 on the opening 123 side of the pore 121 decreases rapidly compared to the diameter of the pore 121, and the inner surface of the pore 121 has a bell shape with a curved shape.

In addition, the pores 121 have high pore arrangement regularity by performing anodization treatment at a constant voltage for a long time to form an oxide film, once removing the oxide film, and performing anodization treatment again under the same conditions. This is preferable because it provides the following.

The anodizing treatment is performed by immersing the aluminum base material in an electrolytic solution, which is an aqueous solution of one or more acids selected from the group consisting of chromic acid, citric acid, oxalic acid, and sulfuric acid, and passing a constant current. , a process of forming a porous oxide film on the surface of the aluminum base material. The concentration of the electrolytic solution is not particularly limited, and is, for example, in the range of 0.01 to 1.0M.
As the electrolytic solution used in the anodizing treatment, a solution containing, for example, citric acid, oxalic acid, or sulfuric acid is preferable because the pores 121 having high pore arrangement regularity can be obtained. The formation voltage of the anodizing treatment is, for example, 30 V to 60 V when an oxalic acid solution is used as the electrolytic solution, and 25 V to 30 V when a sulfuric acid solution is used as the electrolytic solution. This is preferable because it provides the following.

It is also possible to form fine depressions on the surface of the aluminum base material before the first anodic oxidation treatment, and use these as pore generation points during anodization. This is preferable because the pores 121 having an arbitrary arrangement can be obtained.

The pore size enlarging process is a process for enlarging the pore size of the pores formed by the anodic oxidation process. The pore size enlarging treatment involves, for example, immersing an anodized aluminum base material 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 certain period of time. This can be done by The conditions for the pore size enlargement treatment include, for example, the concentration of the acid aqueous solution is in the range of 1.0 to 20% by weight, the temperature of the acid aqueous solution is in the range of 20 to 60°C, and the immersion time is in the range of 30 seconds to 60 minutes. It can be done.

The water-repellent layer forming step is performed on the surface of the anodic oxide film 12 obtained in the anodic oxide film forming step on the side opposite to the aluminum base material 11, that is, the flat upper surface 122 and pores of the anodic oxide film 12. This is a step of forming the water repellent layer 13 along the inner surface of the water repellent layer 121.

In the water-repellent layer forming step, the method for forming the water-repellent layer 13 along the surface of the anodic oxide film 12 on the side opposite to the aluminum base material 11 is not particularly limited. An example of a method is to prepare a low surface energy substance solution by dissolving the low surface energy substance solution, and to bring the low surface energy substance solution into contact with the anodic oxide film 12.

The method of bringing the low surface energy material solution into contact with the anodic oxide film 12 is not particularly limited, and may include a method of immersing the anodic oxide film 12 in the low surface energy material solution, or a method of contacting the anodic oxide film 12 with the low surface energy material solution. An example is a method of applying the material to an energetic material solution, but a method of immersing the anodic oxide film 12 in the low surface energy material solution is preferable.

Examples of the solvent used in the low surface energy substance solution include fluorine-containing aromatic hydrocarbon solvents such as 1,3-bis(trifluoromethyl)benzene and trifluorotoluene; perfluorohexane, perfluoromethylcyclohexane, etc. perfluorocarbon solvent having a carbon number of 3 to 12; 1,1,2,2,3,3,4-heptafluorocyclopentane, 1,1,1,2,2,3,3,4,4 _{, 5,5,6,6 - tridecafluorooctane and other hydrofluorocarbon solvents ; _ _ _ 3} ) Hydrofluoroether solvents such as _C3F7 ; perfluoropolyether compounds such _as Fomblin, Galden (manufactured by Solvay), Demnum (manufactured by Daikin Industries), and Krytox (manufactured by Chemours); In addition to the above solvents, water, alcohol solvents, ketone solvents, ester solvents, etc. can also be used. The solvents used in the low surface energy substance solution may be used alone or in combination of two or more.

The lower limit of the concentration of the low surface energy substance in the low surface energy substance solution is, for example, 0.01% by mass or more, preferably 0.1% by mass or more. The upper limit of the concentration of the low surface energy substance in the low surface energy substance solution is, for example, 10% by mass or less, preferably 5% by mass or less.

After the anodic oxide film 12 and the low surface energy substance solution come into contact, for example, the solution is left at room temperature for several minutes, the drying temperature is set to, for example, a range of 40 to 200°C, preferably a range of 40 to 150°C, and a drying time is set. For example, the water-repellent layer 13 can be obtained by drying for 5 to 60 minutes, preferably 30 to 60 minutes.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. In the examples, "parts" or "%" are used, but unless otherwise specified, "parts by mass" or "% by mass" are expressed.

（ただし、式中、ｒは繰り返し数を表し、平均４３である。）
で表されるケマーズ製Ｋｒｙｔｏｘ１５７ＦＳ（Ｈ）８７．６ｇと、γ－グリシドキシプロピルトリメトキシシラン３．３３ｇと、反応触媒としてトリフェニルフォスフィン０．２７３ｇを加え、窒素気流下で攪拌を開始し、１０５℃に加温後、約５時間反応させた。その後、５０℃まで降温し、Ｃ_４Ｆ_９ＯＣ_２Ｈ_５ ３３．３３ｇと、３－イソシアナトプロピルトリメトキシシラン３．０２ｇと、ウレタン化触媒としてオクチル酸スズ０．０４７ｇを加え、窒素気流下で攪拌を開始し、７０℃で約４時間反応させ、反応物を得た。得られた反応物における溶剤の含有率が８０％となるようにＣ_４Ｆ_９ＯＣ_２Ｈ_５で反応物を希釈した。この希釈した反応物を孔径１μｍのポリテトラフルオロエチレン（ＰＴＦＥ）製フィルターを使用してろ過精製し、下記一般式で示されるポリ（パーフルオロアルキレンエーテル）鎖含有シラン化合物（１）を含む溶液を得た。

<Preparation of low surface energy substance (silane compound containing poly(perfluoroalkylene ether) chain) solution>
[Synthesis example 1]
In a glass flask equipped with a stirring device, a thermometer, a cooling tube, and a dropping device, 60.62 g of 1,3-bis(trifluoromethyl)benzene and the following general formula

(However, in the formula, r represents the number of repetitions, which is 43 on average.)
87.6 g of Krytox 157FS (H) manufactured by Chemours, represented by After heating to 105° C., the mixture was allowed to react for about 5 hours. Thereafter, the temperature was lowered to 50°C, and 33.33 g of C ₄ F ₉ OC ₂ H ₅ , 3.02 g of 3-isocyanatopropyltrimethoxysilane, and 0.047 g of tin octylate as a urethanization catalyst were added, and the mixture was heated under a nitrogen stream. Stirring was started at 70° C. for about 4 hours to obtain a reaction product. The reaction product was diluted with C ₄ F ₉ OC ₂ H ₅ so that the solvent content in the obtained reaction product was 80%. This diluted reaction product 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. Obtained.

（式中、ｌは繰り返し数であり、平均で１９である。ｍは繰り返し数であり、平均で１９である。）
で表されるポリ（パーフルオロアルキレンエーテル）鎖を有するアルコール２０ｇと溶剤としてハイドロフルオロエーテル（Ｃ_４Ｆ_９ＯＣ_２Ｈ_５）２０ｇとウレタン化触媒としてオクチル酸スズ０．００６ｇを仕込み、窒素気流下で攪拌を開始し、５０℃を保ちながら３－イソシアナトプロピルトリメトキシシラン１．３１ｇを１５分間かけて滴下した。滴下終了後、５０℃で６時間攪拌することにより前記アルコールと３－イソシアナトプロピルトリメトキシシランとを反応させ、反応物を得た。得られた反応物について、ＩＲスペクトル測定を行い、反応物中にイソシアネート基の消失していることを確認し、下記一般式で示される化合物（２）が得られたことを確認した。

溶剤の濃度が８０質量％となるようにハイドロフルオロエーテル（Ｃ_４Ｆ_９ＯＣ_２Ｈ_５）で反応液を希釈した。希釈した反応液を孔径０．２μｍのポリテトラフルオロエチレン（ＰＴＦＥ）製フィルターを使用してろ過精製し、前記ポリ（パーフルオロアルキレンエーテル）鎖含有シラン化合物（２）を含むハイドロフルオロエーテル溶液を得た。[Synthesis example 2]
In a glass flask equipped with a stirrer, thermometer, cooling tube, and dropping device, add the following general formula.

(In the formula, l is the number of repetitions, which is 19 on average. m is the number of repetitions, which is 19 on average.)
20 g of alcohol having a poly(perfluoroalkylene ether) chain represented by , 20 g of hydrofluoroether (C ₄ F ₉ OC ₂ H ₅ ) as a solvent, and 0.006 g of tin octylate as a urethanization catalyst were charged, and the mixture was heated under a nitrogen stream. Stirring was started, and 1.31 g of 3-isocyanatopropyltrimethoxysilane was added dropwise over 15 minutes while maintaining the temperature at 50°C. After the addition was completed, the alcohol and 3-isocyanatopropyltrimethoxysilane were reacted by stirring at 50° C. for 6 hours to obtain a reaction product. The obtained reaction product was subjected to IR spectrum measurement, and it was confirmed that the isocyanate group had disappeared in the reaction product, and it was confirmed that the compound (2) represented by the following general formula was obtained.

The reaction solution was diluted with hydrofluoroether (C ₄ F ₉ OC ₂ H ₅ ) so that the concentration of the solvent was 80% by mass. The diluted reaction solution was purified by filtration 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). Ta.

<Preparation of aluminum base material with anodized film>
Manufacturing example 1
An aluminum plate with a purity of 99.99% was anodized at 17° C. for 2 minutes at a formation voltage of 350 V using 0.2 M citric acid aqueous solution as an electrolyte. Thereafter, it was immersed in a 10 wt % phosphoric acid aqueous solution at 50° C. for 20 minutes to perform a pore diameter enlargement treatment. By repeating this operation five times, an aluminum material (A) having an anodic oxide film with a pore period of 850 nm was obtained. FIG. 6 is a scanning electron microscope (SEM) photograph of the top surface of the obtained aluminum material (A). Moreover, FIG. 7 is a SEM photograph of the cross section of the aluminum material (A). It can be confirmed from FIGS. 6 and 7 that fine irregularities are formed on the surface of the anodic oxide film of the aluminum material (A).

Manufacturing example 2
An aluminum plate with a purity of 99.50% was anodized for 30 seconds at a formation voltage of 40 V using a 0.3 M oxalic acid aqueous solution as an electrolyte. Thereafter, it was immersed in a 5 wt % phosphoric acid aqueous solution at 30° C. for 12 minutes to perform a pore diameter enlargement treatment. By repeating this operation five times, an aluminum material (B) having an anodic oxide film with a pore period of 100 nm was obtained. When the surface of the obtained aluminum material (B) was observed with a scanning electron microscope, it was confirmed that fine irregularities were formed on the surface of the anodic oxide film of the aluminum material (B).

Manufacturing example 3
An aluminum plate with a purity of 99.50% was anodized for 50 seconds at a formation voltage of 80 V using a 0.05 M oxalic acid aqueous solution as an electrolyte. Thereafter, it was immersed in a 5 wt % phosphoric acid aqueous solution at 30° C. for 30 minutes to perform a pore diameter enlargement treatment. By repeating this operation five times, an aluminum material (C) having an anodic oxide film with a pore period of 200 nm was obtained. When the surface of the obtained aluminum material (C) was observed with a scanning electron microscope, it was confirmed that fine irregularities were formed on the surface of the anodic oxide film of the aluminum material (C).

Production example 4
An aluminum plate with a purity of 99.50% was anodized for 5 minutes at a formation voltage of 200 V using 0.1 M phosphoric acid aqueous solution as an electrolyte. Thereafter, it was immersed in a 10 wt % phosphoric acid aqueous solution at 30° C. for 60 minutes to perform a pore diameter enlargement treatment. This operation was repeated four times and further anodized for 5 minutes under the same conditions to obtain an aluminum material (D) having an anodic oxide film with a pore period of 500 nm. When the surface of the obtained aluminum material (D) was observed with a scanning electron microscope, it was confirmed that fine irregularities were formed on the surface of the anodic oxide film of the aluminum material (D).

Manufacturing example 5
An aluminum plate with a purity of 99.50% was anodized for 10 minutes at a formation voltage of 350 V using 0.2 M citric acid aqueous solution as an electrolyte. Thereafter, it was immersed in a 10 wt % phosphoric acid aqueous solution at 50° C. for 20 minutes to perform a pore diameter enlargement treatment. By repeating this operation five times, an aluminum material (E) having an anodic oxide film with a pore period of 850 nm was obtained. When the surface of the obtained aluminum material (E) was observed with a scanning electron microscope, it was confirmed that fine irregularities were formed on the surface of the anodic oxide film of the aluminum material (E).

Manufacturing example 6
An aluminum plate with a purity of 99.50% was anodized for 10 minutes at a formation voltage of 400 V using 0.2 M citric acid aqueous solution as an electrolyte. Thereafter, it was immersed in a 10 wt % phosphoric acid aqueous solution at 50° C. for 20 minutes to perform a pore diameter enlargement treatment. By repeating this operation five times, an aluminum material (F) having an anodic oxide film with a pore period of 1000 nm was obtained.

Manufacturing example 7
An aluminum plate with a purity of 99.50% was anodized for 75 seconds at a formation voltage of 40 V using a 0.3 M oxalic acid aqueous solution as an electrolyte. Thereafter, it was immersed in a 5 wt % phosphoric acid aqueous solution at 30° C. for 30 minutes to perform a pore diameter enlargement treatment. By repeating this operation twice, an aluminum material (G) having an anodic oxide film with a pore period of 100 nm was obtained. When the surface of the obtained aluminum material (G) was observed with a scanning electron microscope, it was confirmed that fine irregularities were formed on the surface of the anodic oxide film of the aluminum material (G).

Production example 8
An aluminum plate having a purity of 99.50% was anodized for 250 seconds at a formation voltage of 80 V using a 0.3 M oxalic acid aqueous solution as an electrolyte. Thereafter, it was immersed in a 5 wt % phosphoric acid aqueous solution at 30° C. for 75 minutes to perform a pore diameter enlargement treatment. By repeating this operation twice, an aluminum material (H) having an anodic oxide film with a pore period of 200 nm was obtained.

Comparative manufacturing example 1
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. Subsequently, 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. Then, the aluminum plate was taken out and dried at 150° C. for 30 minutes to obtain an aluminum material (I).

Comparative manufacturing example 2
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. Then, the aluminum plate was taken out and dried at 150° C. for 30 minutes to obtain an aluminum material (J).

Comparative manufacturing example 3
An aluminum plate with a purity of 99.99% was anodized at 17° C. for 10 minutes at a formation voltage of 350 V using 0.2 M citric acid aqueous solution as an electrolyte. Thereafter, the aluminum material (K) was obtained by immersing it in a 10% by mass phosphoric acid aqueous solution at 50° C. for 40 minutes and performing a pore diameter enlargement treatment. FIG. 8 is a SEM photograph of the top surface of the obtained aluminum material (K). Moreover, FIG. 9 is a SEM photograph of the cross section of the aluminum material (K). From Fig. 8, it can be confirmed that fine irregularities are formed on the surface of the anodic oxide film of the aluminum material (K), and from Fig. 9, the longitudinal section along the depth direction of the pores is shown from the opening of the pores. It can be confirmed that the pores do not have a shape that narrows toward the bottom.

Comparative production example 4
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 formation voltage of 350 V at 17° C. for 10 minutes to obtain an aluminum material (L). FIG. 10 is a SEM photograph of the top surface of the obtained aluminum material (L). Moreover, FIG. 11 is a SEM photograph of the cross section of the aluminum material (L). From FIGS. 10 and 11, it can be confirmed that fine irregularities are formed on the surface of the anodic oxide film of the aluminum material (L), but the flat top surface is impaired.

Comparative production example 5
An aluminum plate with a purity of 99.50% was anodized for 15 seconds at a formation voltage of 40 V using a 0.3 M oxalic acid aqueous solution as an electrolyte. Thereafter, the aluminum material (M) was obtained by immersing it in a 5% by mass phosphoric acid aqueous solution at 30° C. for 3 minutes and performing a pore diameter enlargement treatment. FIG. 12 is a SEM photograph of the top surface of the obtained aluminum material (M). Moreover, FIG. 13 is a SEM photograph of the cross section of the aluminum material (M). As shown in FIGS. 12 and 13, fine irregularities are formed on the surface of the anodic oxide film of the aluminum material (M), but the flat top surface is damaged and the longitudinal section along the depth direction of the pores is It can be confirmed that the shape does not narrow from the opening toward the bottom of the pore.

Comparative manufacturing example 6
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 formation voltage of 40 V to obtain an aluminum material (N). FIG. 14 is a SEM photograph of the top surface of the obtained aluminum material (N). Moreover, FIG. 15 is a SEM photograph of the cross section of the aluminum material (N). As shown in FIGS. 14 and 15, fine irregularities are formed on the surface of the anodic oxide film of the aluminum material (N), but the cut surface has a shape that narrows from the opening of the pore toward the bottom of the pore. I can confirm that there is no.

Comparative production example 7
An aluminum plate with a purity of 99.50% was anodized in a 10% aqueous sulfuric acid solution at 20° C. for 1 hour at a current density of 1 A/dm ² . Next, the aluminum plate was immersed in a 5% phosphoric acid aqueous solution at 50°C and subjected to a dissolution treatment to obtain an aluminum material (O). FIG. 16 is a SEM photograph of the top surface of the obtained aluminum material (O). Moreover, FIG. 17 is a SEM photograph of the cross section of the aluminum material (O). From FIGS. 16 and 17, it can be seen that although a layer with pores was formed by anodization in the aluminum material (O), the surface of the anodic oxide film did not have a flat top surface, and furthermore, there were no partition walls that partitioned the pores. You can see that they have fallen down and are folded on top of each other.

Each of the aluminum materials produced above was subjected to the following treatment to form a water-repellent layer.
[Formation of water repellent layer 1]
C ₄ F ₉ OC ₂ H ₅ was added to the solution of silane compound (1) of Synthesis Example 1 to prepare a 0.1% by mass solution of silane compound (1). The aluminum materials (A) to (H) were immersed in a 0.1% by mass solution of the silane compound (1) and allowed to stand for 1 hour. Then, each plate was taken out and dried at 150° C. for 30 minutes to obtain water-repellent aluminum materials (A)' to (H)' having water-repellent layers.

[Formation of water repellent layer 2]
C ₄ F ₉ OC ₂ H ₅ was added to the solution of silane compound (2) of Synthesis Example 2 to prepare a 0.1% by mass solution of silane compound (2). The aluminum materials (A) to (F) were immersed in a 0.1% by mass solution of the silane compound (2) and allowed to stand for 1 hour. Then, each plate was taken out and dried at 150° C. for 30 minutes to obtain water-repellent aluminum materials (A)'' to (F)'' having water-repellent layers.

[Formation of water repellent layer 3]
Butyl acetate was added to dodecylmethoxysilane to prepare a 0.1% by mass solution of dodecylmethoxysilane in butyl acetate. The aluminum material (B) was immersed in a 0.1% by mass solution of dodecylmethoxysilane in butyl acetate and allowed to stand for 1 hour. Then, the plate was taken out and dried at 150°C for 30 minutes to obtain an aluminum material (B)'''.

[Formation of water repellent layer 4]
The aluminum materials (K) to (O) were immersed in a hydrofluoroether solution containing the poly(perfluoroalkylene ether) chain-containing silane compound (1) according to Synthesis Example 1, and allowed to stand for 1 hour. Then, the plate was taken out and dried at 150° C. for 30 minutes to obtain aluminum materials (K)' to (O)'.

[Formation of water repellent layer 5]
The aluminum materials (K) to (N) were immersed in a 0.1% by mass solution of the silane compound (2) and allowed to stand for 1 hour. Then, the plates were taken out and dried at 150° C. for 30 minutes to obtain aluminum materials (K)'' to (N)''.

Examples 1 to 8 and Comparative Examples 1 to 8
The following evaluations were performed for each of the obtained aluminum materials. The results of each evaluation are shown in Tables 1 to 3. In addition, in the water sliding angle measurement, water did not slide down on the aluminum material G, and only a small amount of water remained on the aluminum material. In addition, in the running water durability test, aluminum materials G, M', and N' were all in a state where water did not slide off when water was poured on them for 1 hour. Furthermore, water did not slide off the aluminum material O' after 66 hours of water flowing onto it.

<Evaluation method>
[Water contact angle measurement]
Water repellency was evaluated by measuring the contact angle of water. Note that DM-500 manufactured by Kyowa Interface Science Co., Ltd. was used to evaluate the contact angle. A 5 μL water droplet was dropped onto the base material, and the angle thereof was taken as a value. The measurement was performed three times, and the average value was taken as the value.
[Water fall angle measurement]
The water sliding property was evaluated by measuring the sliding angle of water. Note that DM-500 manufactured by Kyowa Interface Science Co., Ltd. was used to evaluate the sliding angle. A 5 μL water droplet was dropped onto the base material, the stage was tilted at a speed of 2 degrees/second, and the angle at which the water droplet began to move was defined as the falling angle. The measurement was performed three times, and the average value was taken as the value.
[Running water durability]
After measuring the sliding angle of each aluminum material, water was poured into the area where the sliding angle was measured at a rate of 9.9 mL/min from a tube with an inner diameter of 1 mm, and changes in the sliding angle were measured at predetermined intervals. was measured.

As is clear from the results in Tables 1 to 3, it can be seen that the water-repellent aluminum materials according to Examples have excellent water repellency, water sliding properties, and durability against running water. On the other hand, it can be seen that the aluminum material according to the comparative example is inferior in water repellency, water sliding properties, and running water durability, and therefore cannot solve the problems of the present invention.

Claims (7)

A water-repellent aluminum comprising: an aluminum base material; an anodic oxide film formed on the aluminum base material; and a water-repellent layer formed along a surface of the anodic oxide film opposite to the aluminum base material. It is a material,
the anodic oxide film has a plurality of pores, and the pores have openings on a flat upper surface of the anodic oxide film on the opposite side from the aluminum base material,
The pore has a shape in which a longitudinal section along the depth direction narrows from the opening of the pore toward the bottom of the pore,
The water-repellent layer comprises a compound represented by the following formulas (2-1) to (2-4), a compound represented by the following formula (3), a compound represented by the following formula (4-1), and the following: A water-repellent aluminum material containing one or more low surface energy substances selected from the group consisting of compounds represented by formula (5-1) .
(In the above formulas (2-1), (2-2), (2-3) and (2-4),
r is an integer indicating the number of repetitions.
R ²¹ is an alkylene group having from 1 to 6 carbon atoms.
R ²³ is a divalent linking group.
Z is a trivalent linking group.
Q is each independently an organic group or a silyl group represented by -Si(A) ₃ , and at least one of the two B's is a silyl group represented by Si(A) ₃ .
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. .
(In the above 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 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. )
(In the above formula (4-1),
r is an integer indicating the number of repetitions.
R ⁴¹ is an alkylene group having 1 to 6 carbon atoms.
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. . )
(In the above formula (5-1),
l is an integer indicating the number of repetitions.
m is an integer indicating the number of repetitions.
R ⁵¹ is an alkylene group having from 1 to 6 carbon atoms.
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 repellent according to claim 1, wherein the shape narrowing from the opening of the pore toward the bottom of the pore is a shape gradually narrowing from the opening of the pore toward the bottom of the pore. Water-based aluminum material. The water-repellent aluminum material according to claim 1 or 2, wherein the pores are pores formed by subjecting the surface of the aluminum base material to anodizing treatment and pore diameter enlarging treatment two or more times in this order. The water-repellent aluminum material according to any one of claims 1 to 3, wherein the pore period of the pores is in the range of 100 nm or more to 1000 nm or less. The water-repellent aluminum material according to any one of claims 1 to 4, wherein the water-repellent layer has a thickness ranging from 1 nm or more to 100 nm or less. The low surface energy substance includes one or more water-repellent groups selected from the group consisting of fluorine-containing groups, silicone-containing groups, and hydrocarbon groups, and sulfide, thiol groups, amino groups, sulfonyl groups, hydroxyl groups, carboxyl groups, The water-repellent aluminum material according to any one of claims 1 to 5, which is a compound having one or more aluminum oxide-reactive groups selected from the group consisting of a phosphoric acid-containing group and an alkoxysilyl group. Anodizing treatment in which the surface of the aluminum base material is anodized to form an anodic oxide film and pores, and pore diameter enlarging treatment in which the pore diameters of the pores formed by the anodic oxidation are expanded twice or more each in this order. 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 base material,
the anodic oxide film has a plurality of pores, and the pores have openings on a flat upper surface of the anodic oxide film on the opposite side from the aluminum base material,
A method for producing a water-repellent aluminum material, wherein a vertical cross section of the pore along the depth direction narrows from the opening of the pore toward the bottom of the pore,
The low surface energy substance is a compound represented by the following formulas (2-1) to (2-4), a compound represented by the following formula (3), a compound represented by the following formula (4-1), and A method for producing a water-repellent aluminum material, which is one or more selected from the group consisting of compounds represented by the following formula (5-1) .
(In the above formulas (2-1), (2-2), (2-3) and (2-4),
r is an integer indicating the number of repetitions.
R ²¹ is an alkylene group having from 1 to 6 carbon atoms.
R ²³ is a divalent linking group.
Z is a trivalent linking group.
Q is each independently an organic group or a silyl group represented by -Si(A) ₃ , and at least one of the two B's is a silyl group represented by Si(A) ₃ .
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. .
(In the above 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 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. )
(In the above formula (4-1),
r is an integer indicating the number of repetitions.
R ⁴¹ is an alkylene group having 1 to 6 carbon atoms.
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. . )
(In the above formula (5-1),
l is an integer indicating the number of repetitions.
m is an integer indicating the number of repetitions.
R ⁵¹ is an alkylene group having from 1 to 6 carbon atoms.
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. . )

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