CN115461498A - Water-repellent aluminum material and method for producing same - Google Patents

Abstract

The present invention is a water repellent aluminum material having: an aluminum substrate; 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 substrate, wherein the anodic oxide film has a plurality of pores, the pores have openings on a flat upper surface of the anodic oxide film opposite to the aluminum substrate, a longitudinal cross section along a depth direction of the pores has a shape narrowing from the openings of the pores toward bottoms of the pores, and the water repellent layer contains a low surface energy substance. According to the present invention, there is provided a method of: a water-repellent aluminum material having excellent water-sliding properties, excellent water-running durability and excellent practical properties.

Description

Water-repellent aluminum material and method for producing same

Technical Field

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

Background

Heat exchangers are used in air conditioners, refrigerators, freezers, electric vehicles, and the like, and conventionally, in heat exchangers of evaporators for refrigerators, air conditioners, and the like, various aluminum materials are used as fin members in order to satisfy requirements for weight reduction, improvement in thermal efficiency, further miniaturization, and the like, and a design for reducing fin intervals as much as possible is adopted. Such a heat exchanger has the following problems: in the outdoor unit in which water droplets are condensed and attached to the surfaces of the fins or in a heating operation, the condensed water on the surfaces of the fins is frozen as frost due to a low atmospheric temperature, thereby increasing ventilation resistance and significantly reducing heat exchange efficiency.

In order to solve this problem, patent document 1 discloses forming a hydrophilic coating film on the surface of a fin, thereby allowing water droplets adhering to the surface of the fin to flow down or reducing the amount of water droplets remaining during defrosting.

However, the technique described in patent document 1 has a problem that water inevitably remains in the coating film due to hydrophilicity, and hence re-frosting occurs in a short time.

In regard to hydrophilicity, a method of providing water repellency to an aluminum fin to cause water droplets to fall has also been studied (for example, patent document 2). The water-repellent surface confirmed the effect of delaying the occurrence of frost, but it was difficult to remove the water droplets temporarily generated. That is, the water repellency does not necessarily have a correlation with the ease of droplet inversion and the water droplet removability, and therefore, the conventional water repellent coating has a problem of insufficient water repellency.

In order to improve the water-sliding property, a method of imparting unevenness to an aluminum surface by etching or a method of imparting unevenness to an aluminum surface by using water-repellent fine particles has been studied (for example, patent documents 3 and 4), but the former has insufficient water-sliding property, and the latter has a problem in dispersion of particles and also has poor durability against running water.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 6-300482

Patent document 2: japanese patent laid-open publication No. 2013-147573

Patent document 3: japanese patent laid-open publication No. 2013-36733

Patent document 4: japanese patent laid-open publication No. 2013-103414

Disclosure of Invention

Problems to be solved by the invention

The present invention addresses the problem of providing: a water-repellent aluminum material having excellent water-sliding properties, excellent water-running durability and excellent practical properties.

Another object of the present invention is to provide: a method for producing a water-repellent aluminum material having excellent process applicability, excellent water-sliding properties and running water durability, and excellent practicability.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems. As a result, they found that: the water-repellent aluminum material having an anodic oxide coating and a water-repellent layer of a specific structure and the method for producing the same are excellent in process applicability, excellent in water-sliding property and running water durability, and excellent in practicality, and thus the present invention has been completed.

The present invention is a water-repellent aluminum material having: an aluminum substrate; 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 substrate, wherein the anodic oxide film has a plurality of pores, the pores have openings on a flat upper surface of the anodic oxide film opposite to the aluminum substrate, a longitudinal cross section along a depth direction of the pores has a shape narrowing from the openings of the pores toward bottoms of the pores, and the water-repellent layer contains a low surface energy substance.

The present invention is also a method for producing a water repellent aluminum material, comprising the steps of: an anodic oxide film forming step of sequentially performing an anodic oxidation treatment for anodizing the surface of the aluminum substrate to form an anodic oxide film and pores and a pore diameter enlarging treatment for enlarging the pore diameter of the pores formed by the anodic oxidation, for 2 or more times; and a water-repellent layer forming step of forming a water-repellent layer containing a low-surface-energy substance along a surface of the anodic oxide film on the side opposite to the aluminum substrate, wherein the anodic oxide film has a plurality of pores, the pores have openings on a flat upper surface of the anodic oxide film on the side opposite to the aluminum substrate, and a longitudinal cross section along a depth direction of the pores has a shape that is narrowed from the openings of the pores toward bottoms of the pores.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided: a water-repellent aluminum material having excellent water-sliding properties, excellent water-running durability and excellent practical properties.

Further, according to the present invention, there can be provided: a method for producing a water-repellent aluminum material having excellent process applicability, excellent water-sliding properties and running water durability, and excellent practicability.

Drawings

FIG. 1 is a schematic view showing an example of a cross section of a water repellent aluminum material of the present invention

FIG. 2 is a schematic view showing a working state in each step of producing the water repellent aluminum material of the present invention

FIG. 3 is a schematic view showing the processing state in each step of producing the water repellent aluminum material of the present invention

FIG. 4 is a schematic view showing a working state in each step of producing the water repellent aluminum material of the present invention

FIG. 5 is a schematic view showing a working state in each step of producing the water repellent aluminum material of the present invention

FIG. 6 is an SEM photograph of an anodized coating film according to a production example of the present invention

FIG. 7 is an SEM photograph showing a cross section of an anodic oxide film in a production example of the present invention

FIG. 8 is an SEM photograph of an anodized coating film of a comparative manufacturing example of the present invention

FIG. 9 is an SEM photograph showing a cross section of an anodic oxide film of a comparative production example of the present invention

FIG. 10 is an SEM photograph of an anodized coating film of a comparative manufacturing example of the present invention

FIG. 11 is an SEM photograph showing a cross section of an anodic oxide film of a comparative production example of the present invention

FIG. 12 is an SEM photograph of an anodized coating film according to a comparative production example of the present invention

FIG. 13 is an SEM photograph of a cross section of an anodic oxide film of a comparative production example of the present invention

FIG. 14 is an SEM photograph of an anodized coating film of a comparative production example of the present invention

FIG. 15 is an SEM photograph showing a cross section of an anodic oxide film of a comparative production example of the present invention

FIG. 16 is an SEM photograph of an anodized coating film of a comparative production example of the present invention

FIG. 17 is an SEM photograph showing a cross section of an anodic oxide film of a comparative production example of the present invention

Detailed Description

The water repellent aluminum material according to an embodiment of the present invention will be described with reference to fig. 1. Fig. 1 is a schematic view of a cross section in the depth direction of a water repellent aluminum material 1 of the present embodiment.

The water repellent aluminum material 1 has: an aluminum base material 11; an anodic oxide film 12 formed on the aluminum base material 11; and a water-repellent layer 13 formed along the surface of the anodic oxide film 12 opposite to the aluminum substrate 11. The anodic oxide film 12 has a plurality of pores 121, the pores 121 have openings 123 on a flat upper surface 122 of the anodic oxide film 12 on the opposite side of the aluminum substrate 11, and 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 bottoms 124 of the pores 121. In the present embodiment, the "surface on the opposite side of the aluminum substrate 11" forming the water repellent layer 13 includes the flat upper surface 122 having the openings 123 and the inner surface 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 contains a low surface energy substance. The water repellent aluminum material 1 has excellent water-sliding property and running water durability, and is excellent in practical use.

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

From the viewpoint of imparting durability in addition to the super-lubricity, the shape narrowing from the opening 123 of the fine pore to the bottom 124 of the fine pore is preferably a shape gradually narrowing from the opening 123 to the bottom 124 of the fine pore. By forming this shape, the area of the portion in contact with the water droplets can be reduced, and durability, which is the maintenance of the shape, can be provided. In fig. 1, the shape narrowing from the opening 123 of the fine hole toward the bottom 124 of the fine hole may be 1 step or more, but may be 2 steps or more. The shape gradually narrowing from the opening 123 of the fine pore toward the bottom 124 of the fine pore may be a smooth shape. The shape narrowing from the opening 123 of the fine pore 121 to the bottom 124 of the fine pore 121 may be a bell shape curvilinearly narrowing from the opening 123 of the fine pore 121 to the bottom 124 of the fine pore 121.

The shape of the pores 121 is formed by subjecting the surface of the aluminum substrate to the anodization treatment and the pore diameter enlargement treatment 2 or more times. As the number of anodization and pore diameter enlargement increases, the shape of the pores 121 tends to become narrower from the openings 123 toward the bottoms 124 of the pores 121. Therefore, by adjusting the number of times of the anodization and the pore diameter enlargement, the shape of the pore 121 can be adjusted to be narrowed from the opening 123 toward the bottom 124.

The pore period P of the pores 121 is preferably 100nm or more in the lower limit, from the viewpoint of ensuring the distance between the points of contact with water droplets and contributing to super-lubricity. The upper limit of the pore period P is preferably 1000nm or less, and more preferably 200nm or less from the viewpoint of productivity. The pore period P is a distance from the center of a pore 121 to the center of an adjacent pore 121. The pore period P was measured by the method described in examples.

The pore depth D of the pores 121 is preferably in the range of 100nm to 1000nm from the viewpoint of ensuring the durability against flowing water. The pore depth D is a depth from the flat upper surface 122 to the bottom 124.

The low surface energy substance contained 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 1 or more water repellent groups selected from the group consisting of a fluorine-containing group, a silicone-containing group, and a hydrocarbon group, and 1 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 group, and an alkoxysilyl group. More specific examples of the low surface energy material include fluorine-containing compounds such as polytetrafluoroethylene and polytetrafluoroethylene-hexafluoropropylene copolymer, and silicone compounds such as polydimethylsiloxane and polymethylphenylsiloxane.

From the viewpoint of exhibiting more excellent super-lubricity, 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 having a functional group selected from the group consisting of C _n F _2n+1 A perfluoroalkyl group (n is an integer of 1 or more), F (C) _n F _2n O) _m The perfluoropolyether group (n is an integer of 1 or more, m is an integer representing the number of repetitions), and CF ₃ O(C _n F2 _n O) _m 1 or more kinds selected from the group consisting of the perfluoropolyether groups (n is an integer of 1 or more, and m is an integer representing the number of repetitions) and Si (A) ₃ A fluorine-containing compound having a silyl group (3A's are each independently a hydrolyzable group or a non-hydrolyzable group, and at least 1 of the 3A's is a hydrolyzable group).

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

The aforementioned F (C) _n F _2n O) _m In the perfluoropolyether group, 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.

CF as described above ₃ O(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.

The fluorine-containing compound may comprise (C) _n F _2n O) _m The perfluoropolyether chain (n is an integer of 1 or more, and m is an integer representing the number of repetitions).

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, benzoyloxy and the like; alkenyloxy such as isopropenyloxy and isobutenyloxy; iminoxy groups such as dimethyl ketoximino, methyl ethyl ketoximino, diethyl ketoximino and cyclohexane oximino; substituted amino groups such as methylamino, ethylamino, dimethylamino, and diethylamino; amide groups such as N-methylacetamide group and N-ethylamide group; substituted aminooxy groups such as dimethylaminoxy group and diethylaminooxy group; halogen such as chlorine, etc. Among these hydrolyzable groups, alkoxy groups are preferable, alkoxy groups having 1 to 6 carbon atoms are more preferable, alkoxy groups having 1 to 3 carbon atoms are even more preferable, methoxy groups and ethoxy groups are particularly preferable, and methoxy groups are most preferable, because hydrolysis speed is high and a film having excellent durability can be formed quickly.

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 aralkyl group having 7 to 20 carbon atoms. Among these non-hydrolyzable groups, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is more preferable, because steric hindrance is avoided, hydrolysis speed can be increased, and as a result, a film having excellent durability can be formed quickly.

Si(A) ₃ The number of the hydrolyzable groups in the silyl group is at least 1, and from the viewpoint of forming a coating film having more excellent durability, the number of the hydrolyzable groups is preferably 2 or more, and more preferably 3. In addition, si (A) ₃ When the number of the hydrolyzable groups in the silyl group is 2 or more, the number of the hydrolyzable groups is 2 or more, and the hydrolyzable groups may be the same or different from each other. In addition, si (A) ₃ When there are 2 or more silyl groups, at least 1 Si (A) is required ₃ The silyl group may have a hydrolyzable group. Likewise, si (A) ₃ When the number of the non-hydrolyzable groups in the silyl group is 2 or more, the 2 or more non-hydrolyzable groups are optionally the same as or different from each other.

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

Rf-X-Si(A) ₃ (1-1)

(in the aforementioned formulae (1-1) and (1-2),

R ^f each independently is C _n F _2n+1 A perfluoroalkyl group (n is an integer of 1 or more).

The aforementioned Si (A) ₃ Each of 3A's of the silyl group is independently a hydrolyzable group or a non-hydrolyzable group, and at least one of 3A' sLess than 1 is a hydrolyzable group.

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

(in the above formulae (X-1) to (X-11),

R ^f is C _n F _2n+1 A perfluoroalkyl group (n is an integer of 1 or more).

R ¹¹ Is a direct bond or an alkylene group having 1 to 6 carbon atoms.

R ¹¹ In a plurality of cases, a plurality of R ¹¹ Optionally identical to or different from each other.

R ¹² Is an alkyl group having 1 to 6 carbon atoms. )

In the formulae (1-1) and (1-2), for C _n F _2n+1 Perfluoroalkyl groups and Si (A) shown ₃ Preferred modes of the silyl groups shown are as described above, respectively.

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

The method for producing the compound represented by the formula (1-1) or (1-2) is not particularly limited, and the compound can be produced by a known method, for example, a method disclosed in international publication No. WO 2015/152265.

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

(in the aforementioned formulae (2-1), (2-2), (2-3) and (2-4),

r is an integer representing the number of repeats.

R ²¹ Is an alkylene group having 1 to 6 carbon atoms.

R ²³ Is a linking group having a valence of 2.

Z is a linking group having a valence of 3.

Q is each independently an organic group or-Si (A) ₃ At least 1 of 2 of the silyl groups is Si (A) ₃ Silyl groups as shown.

The aforementioned Si (A) ₃ Each of 3A's of the silyl group is independently a hydrolyzable group or a non-hydrolyzable group, and at least 1 of 3A's is a hydrolyzable group. )

In the 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 still more preferably in the range of 10 to 60 on average.

In the formulae (2-1), (2-2), (2-3) and (2-4), as R ²¹ The alkylene group having 1 to 6 carbon atoms in (b) is preferably an alkylene group having 3 carbon atoms.

In the formulae (2-1), (2-2), (2-3) and (2-4), for Si (A) ₃ Preferred modes of the silyl group are as described above.

When Q is an organic group in the formulae (2-1) and (2-2), examples of the organic group include a substituted or unsubstituted alkyl group, an alkenyl group, a phenyl group, 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 the formulae (2-1), (2-2), (2-3) and (2-4), as R ²³ The linking group having a valence of 2 in (1) is preferably a linking group represented by the following formula (R-1) or a linking group represented by the following formula (R-2).

-R ²⁴ -O-R ²⁵ - (R-1)

-R ²⁶ - (R-2)

(in the aforementioned formulae (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.

R ²⁶ An alkylene group having 1 to 5 carbon atoms)

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

-CH ₂ -O- (R-1-1)

-CH ₂ -O-CH ₂ - (R-1-2)

-CH ₂ -O-CH ₂ CH ₂ - (R-1-3)

-CH ₂ -O-CH ₂ CH ₂ CH ₂ - (R-1-4)

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

-CH ₂ - (R-2-5)

-CH ₂ CH ₂ - (R-2-6)

-CH ₂ CH ₂ CH ₂ - (R-2-7)

-CH ₂ CH ₂ CH ₂ CH ₂ - (R-2-8)

-CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ - (R-2-9)

As the linking group represented by the formulae (R-1) and (R-2), preferred are linking groups represented by the formulae (R-1-1), (R-1-3), (R-1-4), (R-2-5), (R-2-6), (R-2-8), and more preferred are linking groups represented by the formulae (R-1-3) and (R-1-4).

The linking group having a valence of 3 of Z in the formulae (2-2) and (2-4) is preferably a cyclic aliphatic group having a valence of 3 and having 4 to 8 carbon atoms, and more preferably a cyclohexyl group having a valence of 3.

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

(in the formulae (2-1-11) and (2-1-12), a is an integer of 1 to 6.)

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

One embodiment of the method for producing the compound represented by formula (2-1), (2-2), (2-3), or (2-4) will be described below.

The method for producing the compounds represented by the formulae (2-1) and (2-2) includes, for example, the following steps: a step 1 of reacting a carboxylic acid represented by the following formula (. Beta. -1) with an epoxysilane compound represented by the following formula (. Beta. -2) or (. Beta. -3) to prepare a reactant having a secondary hydroxyl group derived from an epoxy group; and a 2 nd step of reacting the reaction product obtained in the 1 st step with an isocyanate compound represented by the following formula (. Beta. -4).

(in the formula (. Beta. -1), r is a repetition number.)

(in the above-mentioned formulas (. Beta. -2) and (. Beta. -3),

R ²³ is a linking group having a valence of 2.

Si(A) ₃ Each of 3A's of the silyl group is independently a hydrolyzable group or a non-hydrolyzable group, and at least 1 of 3A's is a hydrolyzable group. )

OCN-R ²¹ -Si(A) ₃ (β-4)

(in the above formula (. Beta. -4),

R ²¹ is an alkylene group having 1 to 6 carbon atoms.

Si(A) ₃ Each of 3A's of the silyl group is independently a hydrolyzable group or a non-hydrolyzable group, and at least 1 of 3A's is a hydrolyzable group. )

Instead of the compound represented by the formula (. Beta. -2), a compound represented by the following formula (. Beta. -5) may be used.

(in the above formula (. Beta. -5),

R ²³ is a linking group having a valence of 2.

G is an organic group. )

When the compounds represented by the formulae (2-3) and (2-4) are produced, the step 2 may be omitted as long as the step 1 is included.

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

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

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

OCN-R ²¹ -SiCH ₃ (OCH ₃ ) ₂ OCN-R ²¹ -Si(OCH ₃ ) ₃

OCN-R ²¹ -SiCH ₃ (OC ₂ H ₅ ) ₂ OCN-R ²¹ -Si(OC ₂ H ₅ ) ₃

OCN-R ²¹ -SiCH ₃ (OC ₃ H ₇ ) ₂ OCN-R ²¹ -Si(OC ₃ H ₇ ) ₃

OCN-R ²¹ -SiCH ₃ (OC ₄ H ₉ ) ₂ OCN-R ²¹ -Si(OC ₄ H ₉ ) ₃

OCN-R ²¹ -Si(CH ₃ ) ₂ (OCH ₃ )

OCN-R ²¹ -Si(CH ₃ ) ₂ (OC ₂ H ₅ )

OCN-R ²¹ -Si(CH ₃ ) ₂ (OC ₃ H ₇ )

OCN-R ²¹ -Si(CH ₃ ) ₂ (OC ₄ H ₉ )

(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, more preferably n-propylene group)

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

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

The process for producing the compound represented by the 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 the compound group as a raw material can be dissolved, and for example, a solvent such as acetone, methyl ethyl ketone, toluene, xylene, or a fluorine-based organic solvent which does not have reactivity with an isocyanate group can be used.

Examples of the fluorine-containing solvent include fluorine-containing aromatic hydrocarbon-based solvents such as 1, 3-bis (trifluoromethyl) benzene and trifluorotoluene; perfluorocarbon solvents having 3 to 12 carbon atoms such as perfluorohexane and perfluoromethylcyclohexane; <xnotran> 1,1,2,2,3,3,4- ,1,1,1,2,2,3,3,4,4,5,5,6,6- ; </xnotran> 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 Hydrofluoroether solvents, etc.; perfluoropolyether compounds such as Fomblin, galden (manufactured by Solvay), demnum (manufactured by DAIKIN INDUSTRIES, LTD.), krytox (manufactured by Chemours), and the like.

In the step 1, the reaction ratio of the compound (. Beta. -1) and the compound (. Beta. -2) or the compound (. Beta. -3) is preferably a ratio in which the equivalent ratio of the carboxyl group of the compound (. Beta. -1) to the epoxy group of the compound (. Beta. -2) or the compound (. Beta. -3) (carboxyl group/epoxy group) is in the range of 0.5 to 1.5, more preferably in the range of 0.9 to 1.1, and still more preferably in the range of 0.98 to 1.02.

The reaction temperature in the step 1 is not particularly limited, but is usually in the range of 50 to 150 ℃. The reaction time is also not particularly limited, and is usually in the range of 1 to 10 hours.

In the 2 nd step, the reaction ratio of the reactant having a secondary hydroxyl group derived from an epoxy group obtained in the 1 st step and the compound (β -4) is preferably a ratio in which the equivalent ratio (hydroxyl group/isocyanate group) of the hydroxyl group of the reactant and the isocyanate group of the compound (β -4) is in the range of 0.5 to 1.5, more preferably in the range of 0.9 to 1.1, and still more preferably in the range of 0.98 to 1.02.

The reaction temperature in the step 2 is not particularly limited, but is usually in the range of 30 to 120 ℃. The reaction time is also 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-mentioned formula (3),

PFPE is a poly (perfluoroalkylene ether) chain.

Y ¹ And Y ² Each independently is a direct bond or a 2-valent linking group.

Z ¹ And Z ² Each independently is a 2-valent linking group.

The aforementioned Si (A) ₃ Each of 3A's of the silyl group is independently a hydrolyzable group or a non-hydrolyzable group, and at least 1 of 3A's is a hydrolyzable group. 2 pieces of Si (A) mentioned above ₃ The silyl groups shown are optionally the same or different from each other. )

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

In formula (3), for Si (A) ₃ Preferred modes of the silyl group are as described above.

In formula (3), as Y ¹ 、Y ² 、Z ¹ And Z ² Examples of the linking group having a valence of 2 in (2) 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-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-methyl-3-pentylene group, a 4-methylpentylene group, a 4-methyl-2-pentylene group, a 2, 2-dimethyl-3-pentylene group, a 2, a 3-dimethyl-3-pentylene group, a 2, a 4, a 3-dimethylpentylene groupAlkylene groups such as the group-3-pentylene, 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-ethylhexyl, 6-methyl-2-heptylene, 4-methyl-3-heptylene, octylene, 2-octylene, 3-octylene, 2-propylpentylene, 2, 4-trimethylpentylene, and decaoctylene.

Z of formula (3) ¹ And Z ² The linking groups having a valence of 2 in (b) are each independently preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, still more preferably an alkylene group having 1 to 3 carbon atoms, and particularly preferably an n-propylene group.

Y of formula (3) ¹ And Y ² The linking groups having a valence of 2 in (b) 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 still more preferably a methylene group.

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

Examples of the linking group having a structure in which a perfluoroalkylene group having 1 to 3 carbon atoms is alternately linked to an oxygen atom include linking groups represented by the following formula (P-1).

(in the above formula (P-1),

* Is an atomic bond.

X is a C1-3 perfluoroalkylene group.

The perfluoroalkylene groups of the plurality of xs are optionally the same as or different from each other. In the plural X, 2 or more kinds of perfluoroalkylene groups are optionally present in a random or block form.

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, still more preferably in the range of 30 to 100, and most preferably in the range of 35 to 70. )

The perfluoroalkylene group as X may be exemplified by the following structure.

Among them, 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 if the aspect of industrial availability is included.

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

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

In the compound represented by the formula (3), the total number of fluorine atoms contained in 1 poly (perfluoroalkylene ether) chain is preferably in the range of 30 to 600, more preferably 60 to 450, still more preferably 90 to 300, and most preferably 100 to 200.

The method for producing the compound represented by formula (3) is not particularly limited, and the compound can be produced by a known method. An embodiment of the method for producing the compound represented by formula (3) will be described below.

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

HO-Y ¹ -PFPE-Y ² -OH (α-1)

OCN-Z-Si(A) ₃ (α-2)

(in the aforementioned formulae (. Alpha. -1) and (. Alpha. -2),

PFPE is a poly (perfluoroalkylene ether) chain.

Y ¹ And Y ² Each independently is a direct bond or a 2-valent linking group.

Z is a linking group having a valence of 2.

Si(A) ₃ Each of 3A's of the silyl group is independently a hydrolyzable group or a non-hydrolyzable group, and at least 1 of 3A's is a hydrolyzable group. )

PFPE, Y in the formulae (. Alpha. -1) and (. Alpha. -2) ¹ 、Y ² Z and Si (A) ₃ PFPE, Y corresponding to the formula (3) respectively ¹ 、Y ² 、Z ¹ 、Z ² And Si (A) ₃ 。

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

HO-CH ₂ -PFPE-CH ₂ -OH (α-1-1)

HO-CH ₂ CH ₂ -PFPE-CH ₂ CH ₂ -OH (α-1-2)

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

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

In the reaction (carbamation) of the diol represented by the formula (. Alpha. -1) with the isocyanate represented by the formula (. Alpha. -2), the isocyanate represented by the formula (. Alpha. -2) is preferably added so as to be in the range of 0.5 to 1.5 mol, more preferably in the range of 0.9 to 1.1 mol, and most preferably in the range of 0.98 to 1.02 mol, based on 1 mol of OH groups contained in the diol represented by the formula (. Alpha. -1).

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

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

In the reaction of the diol represented by the formula (. Alpha. -1) and the isocyanate represented by the formula (. Alpha. -2), the reaction system may be a solventless system, or an organic solvent such as acetone, methyl ethyl ketone, toluene, xylene, or the like, which does not have reactivity with the isocyanate group; 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(OCH3)C ₃ F ₇ 、HCF ₂ CF ₂ OCH ₂ CF ₃ And a solvent system in which a fluorine-based solvent is used as a reaction solvent.

The reaction temperature is preferably in the range of 30 to 120 ℃ and more preferably in the range of 40 to 90 ℃.

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

(in the aforementioned formulae (4-1), (4-2) and (4-3),

r is an integer representing the number of repeats.

R ⁴¹ Is an alkylene group having 1 to 6 carbon atoms.

R ⁴² Is an alkyleneaminoalkylene or alkylenethioalkylene group.

The aforementioned Si (A) ₃ Each of 3A's of the silyl group is independently a hydrolyzable group or a non-hydrolyzable group, and at least 1 of 3A's is a hydrolyzable group. )

In the formulae (4-1), (4-2) and (4-3),the number of repetitions of r, and Si (A) ₃ Preferred modes of the silyl groups shown are as described above, respectively.

In the formulae (4-1), (4-2) and (4-3), as R ⁴¹ The alkylene group having 1 to 6 carbon atoms in (b) is preferably an alkylene group having 3 carbon atoms.

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

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

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

(in the formula (. Gamma. -1), r is a repetition number.)

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

(in the above formulae (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 alkylenethioalkylene.

The aforementioned Si (A) ₃ Each of 3A's of the silyl group is independently a hydrolyzable group or a non-hydrolyzable group, and at least 1 of 3A's is a hydrolyzable group. )

In the formulas (5-1), (5-2) and (5-3), the repeating unit enclosed by l and the repeating unit enclosed by m may be a random polymerized structure of the repeating unit enclosed by l and the repeating unit enclosed by m, or a block polymerized structure of the repeating unit enclosed by l and the repeating unit enclosed by m.

In the formulae (5-1), (5-2) and (5-3), the number of repetitions of l and m, and Si (A) ₃ Preferred embodiments of the silyl group are as described above.

In the formulae (5-1), (5-2) and (5-3), as R ⁵¹ The alkylene group having 1 to 6 carbon atoms in (b) is preferably an alkylene group having 3 carbon atoms.

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

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

As the method for producing the compound represented by the formula (5-1), (5-2) or (5-3), the same method as that for producing the compound represented by the formula (4-1), (4-2) or (4-3) can be used.

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

(in the above-mentioned formula (. Delta. -1),

l is the number of repetitions.

m is the number of repetitions. )

The water-repellent layer 13 may contain 1 kind of fluorine-containing compound alone or 2 or more kinds of fluorine-containing compounds in combination.

The low surface energy substance is not limited to the fluorine-containing compound. The low surface energy substance may be used as long as it is a compound having both a reactive group capable of bonding to the anodic oxide film by reaction and a water-repellent group exhibiting water repellency.

Examples of the reactive group capable of bonding by reaction with the anodic oxide film include a thioether group, a mercapto group, an amino group, a sulfonyl group, a hydroxyl group, a carboxyl group, a phosphoric acid group, and an alkoxysilyl group, and more preferably include a 1-or 2-valent phosphoric acid group represented by the following formula (6-1) or (6-2), an alkoxysilyl group represented by the following formula (6-3), and the like.

(in the aforementioned formulae (6-1) and (6-2),

R ⁶¹ each independently is any cation.

R ⁶² Each independently is an alkyl group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. )

As R ⁶¹ Examples of the optional cation include alkali metal ions such as sodium ion, potassium ion and lithium ion, and organic cations such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine and triisopropanolamineQuaternary ammonium ions, and the like. Among them, lithium ion, sodium ion, and organic quaternary ammonium ion are preferable.

Examples of the water-repellent group include C _n H _2n+1 A hydrocarbon group represented by the formula (7-1) (n is an integer of 1 or more), a group represented by the formula (7-1), and the like.

(in the above-mentioned formula (7),

R ⁷¹ each independently is 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 described above within a range not to impair the effects of the present invention.

The lower limit of the thickness of the water-repellent layer 13 is preferably 1nm 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 100nm or less, and more preferably 20nm 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 a water droplet of 5 μ L. The water slip angle on the surface of the water-repellent layer 13 is preferably 10 ° or less, more preferably 5 ° or less, for 5 μ L of water droplets. In the present specification, the sliding angle of water and the contact angle of water are measured by the methods described in examples.

A method for producing a water repellent aluminum material according to an embodiment of the present invention includes the steps of: an anodic oxide film forming step of sequentially performing an anodic oxidation treatment for anodizing the surface of the aluminum substrate to form an anodic oxide film and pores and a pore diameter enlarging treatment for enlarging the pore diameter of the pores formed by the anodic oxidation, for 2 or more times; and a water-repellent layer forming step of forming a water-repellent layer containing a low-surface-energy substance along a surface of the anodic oxide film on the side opposite to the aluminum substrate, wherein the anodic oxide film has a plurality of pores, the pores have openings on a flat upper surface of the anodic oxide film on the side opposite to the aluminum substrate, and a longitudinal cross section along a depth direction of the pores has a shape that is narrowed from the openings of the pores toward bottoms of the pores.

A method for producing a water repellent aluminum material according to an embodiment of the present invention will be described with reference to fig. 2 to 5. The same portions as those described in the present embodiment are denoted by the same reference numerals, and redundant description thereof is omitted.

FIGS. 2 to 5 are schematic views showing the processing states in the respective steps of producing the water repellent aluminum material 1.

The anodic oxide film forming step is a step of forming the anodic oxide film 12 on the surface of the aluminum substrate 11 shown in fig. 2 by respectively performing the anodic oxidation treatment and the pore diameter enlargement treatment 2 or more times on the surface of the aluminum substrate 11. When the anodization is performed as the 1 st treatment, an anodized film 12 having micropores 121' is formed on the surface of the aluminum substrate 11 as shown in fig. 3. The pores 121' have a cylindrical shape at an initial stage. The anodic oxide film 12 in the above state is further subjected to a pore diameter enlarging treatment, whereby the pore diameter of the fine pores 121' is enlarged (fig. 4). The anodic oxide film 12 in the state of fig. 4 can be formed on the aluminum substrate 11 by further repeating the anodic oxidation treatment and the pore diameter enlargement treatment. The anodized film 12 formed in the anodized film forming step has the pores 121, the pores 121 have openings 123 in a flat upper surface 122 of the anodized film 12 on the opposite side of the aluminum substrate 11, and 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 bottoms 124 of the pores 121 (fig. 5).

In the anodic oxidation coating formation step, since the thickness between the fine pores can be precisely controlled by the anodic oxidation treatment and the pore diameter enlargement treatment performed 2 or more times, the final treatment is preferably the pore diameter enlargement treatment.

By adjusting the number of times and conditions of the anodization and the pore diameter enlargement, the number of steps of the shape gradually narrowing from the opening 123 of the pore toward the bottom 124 of the pore, the smoothness of the shape, and the like can be adjusted. More specifically, the time of the hole diameter enlarging process as the last process is set to a process time different from the time of the hole diameter enlarging process in the previous repeating process, so that the vertical cross-sectional shape of the fine hole 121 can be formed into a shape in which the vertical cross-section along the depth direction of the fine hole 121 is narrowed from the opening 123 of the fine hole 121 toward the bottom 124 of the fine hole 121, or a bell shape in which the hole diameter of the fine hole 121 is reduced and the inner surface of the fine hole 121 changes curvilinearly. More specifically, it is preferable that the step of performing the hole diameter enlarging process after the anodic oxidation process is repeated n times, and the process time of the hole diameter enlarging process of the nth time is longer than the process time of the hole diameter enlarging process of the 1 st to (n-1) th times, so that the vertical cross-sectional shape of the fine hole 121 is in a bell shape in which the hole diameter of the fine hole 121 on the bottom portion 124 side is relatively sharply reduced from the hole diameter of the fine hole 121 on the opening portion 123 side of the fine hole 121 in the hole depth direction from the opening portion 123 of the fine hole 121 to the bottom portion 124, and the inner surface of the fine hole 121 changes curvilinearly.

It is preferable to perform the anodization for a long time at a constant voltage to form an oxide film, remove the oxide film once, and perform the anodization again under the same conditions, thereby obtaining the pores 121 having a high regularity in the arrangement of the pores.

The anodic oxidation treatment means the following treatment: an aluminum substrate is immersed in an electrolytic solution, which is an aqueous solution of 1 or more acids selected from the group consisting of chromic acid, citric acid, oxalic acid and sulfuric acid, and a constant current is applied to form a porous oxide film on the surface of the aluminum substrate. The concentration of the electrolyte is not particularly limited, and is, for example, in the range of 0.01 to 1.0M.

The electrolyte solution used for the anodic oxidation treatment is preferably a solution containing citric acid, oxalic acid, or sulfuric acid, for example, because the pores 121 having a high regularity of pore arrangement can be obtained. The chemical conversion voltage of the anodic oxidation treatment is preferably 30V to 60V when an oxalic acid solution is used as the electrolytic solution, or 25V to 30V when a sulfuric acid solution is used as the electrolytic solution, because the pores 121 having a high pore arrangement regularity can be obtained.

Before the 1 st anodizing treatment, fine depressions may be formed on the surface of the aluminum substrate, and these may be used as fine pore generation points during the anodizing. This is preferable because pores 121 having an arbitrary arrangement can be obtained.

The pore diameter enlarging treatment is a treatment for enlarging the pore diameter of the fine pores formed by the anodic oxidation treatment. The pore diameter enlarging treatment can be performed by, for example, immersing the anodized aluminum substrate in an aqueous solution of 1 or more acids selected from the group consisting of sulfuric acid, phosphoric acid, chromic acid, oxalic acid, and sulfamic acid for a constant time. As conditions for the pore diameter-enlarging treatment, for example, the concentration of the aqueous acid solution may be set to a range of 1.0 to 20 wt%, the temperature of the aqueous acid solution may be set to a range of 20 to 60 ℃, and the immersion time may be set to a range of 30 seconds to 60 minutes.

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

In the water-repellent layer forming step, the method of forming the water-repellent layer 13 along the surface of the anodic oxide film 12 opposite to the aluminum substrate 11 is not particularly limited, and the following method may be exemplified: the low surface energy substance is dissolved in a solvent to prepare a low surface energy substance solution, and the low surface energy substance solution is brought into contact with the anodic oxide film 12.

The method of bringing the low surface energy substance solution into contact with the anodic oxide film 12 is not particularly limited, and the following methods may be exemplified: a method of immersing the anodic oxide film 12 in the low surface energy substance solution; the method of coating the low surface energy substance solution on the anodized film 12 is preferred, but a method of immersing the anodized film 12 in the low surface energy substance solution is preferred.

Examples of the solvent used in the low surface energy substance solution include a fluorine-containing aromatic hydrocarbon solvent such as 1, 3-bis (trifluoromethyl) benzene and benzotrifluoride; perfluorocarbon solvents having 3 to 12 carbon atoms such as perfluorohexane and perfluoromethylcyclohexane; <xnotran> 1,1,2,2,3,3,4- ,1,1,1,2,2,3,3,4,4,5,5,6,6- ; </xnotran> 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 Hydrofluoroether solvents, etc.; perfluoropolyether compounds such as Fomblin, galden (manufactured by Solvay), demnum (manufactured by DAIKIN INDUSTRIES, manufactured by LTD.), krytox (manufactured by Chemours), etc. In addition to the above solvents, water, alcohol solvents, ketone solvents, ester solvents, and the like can be used. The solvent used in the low surface energy substance solution may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

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

The water repellent layer 13 can be obtained by leaving the anodized film 12 in contact with the low surface energy substance solution at room temperature for several minutes, for example, and drying the anodized film at a drying temperature in the range of 40 to 200 ℃, preferably 40 to 150 ℃, for a drying time in the range of 5 to 60 minutes, preferably 30 to 60 minutes.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" or "%" are used, but unless otherwise specified, "parts by mass" or "% by mass" are used.

Preparation of a solution of Low surface energy substance (silane Compound containing Poly (perfluoroalkylene ether) chain) >

[ Synthesis example 1]

60.62g of 1, 3-bis (trifluoromethyl) benzene, 87.6g of Krytox157FS (H) manufactured by Chemours shown in the following formula, 87.6g, and a solvent were placed in a glass flask equipped with a stirrer, a thermometer, a condenser, and a dropping device,

(wherein, in the formula, r represents the number of repeats, and the average is 43.)

3.33g of gamma-glycidoxypropyltrimethoxysilane and 0.273g of triphenylphosphine as a reaction catalyst were stirred under a nitrogen stream, and the mixture was heated to 105 ℃ and reacted for about 5 hours. Then, the temperature is reduced to 50 ℃, and C is added ₄ F ₉ OC ₂ H ₅ 33.33g, 3.02g of 3-isocyanatopropyltrimethoxysilane, and 0.047g of tin octylate as a carbamation catalyst were reacted at 70 ℃ for about 4 hours with stirring under a nitrogen stream to obtain a reaction product. Using C so that the content of the solvent in the obtained reaction mixture became 80% ₄ F ₉ OC ₂ H ₅ The reaction was diluted. The diluted reaction product was purified by filtration using a Polytetrafluoroethylene (PTFE) filter having a pore size of 1 μm to obtain a solution containing a silane compound (1) having a poly (perfluoroalkylene ether) chain represented by the following general formula.

[ Synthesis example 2]

20g of an alcohol having a poly (perfluoroalkylene ether) chain represented by the following general formula, 20g of the alcohol, and a solvent were placed in a glass flask equipped with a stirrer, a thermometer, a condenser and a dropping device,

( In the formula, l is the number of repeats, and is 19 on average. m is the number of repeats, averaging 19. )

Hydrofluoroether (C) as solvent ₄ F ₉ OC ₂ H ₅ ) 20g and 0.006g of tin octylate as a urethane-forming catalyst, 1.31g of 3-isocyanatopropyltrimethoxysilane was added dropwise over 15 minutes while keeping the temperature at 50 ℃ under stirring under a nitrogen stream. After the completion of the dropwise addition, the mixture was stirred at 50 ℃ for 6 hours to react the alcohol with 3-isocyanatopropyltrimethoxysilane, thereby obtaining a reaction product. With respect to the obtained reaction product, IR spectrum measurement was performed, and disappearance of an isocyanate group in the reaction product was confirmed, and it was confirmed that the compound (2) represented by the following general formula was obtained.

Hydrofluoroether (C) was used so that the concentration of the solvent became 80 mass% ₄ F ₉ OC ₂ H ₅ ) The reaction solution was diluted. The diluted reaction solution was filtered and purified using a Polytetrafluoroethylene (PTFE) filter having a pore diameter of 0.2. Mu.m, to obtain a hydrofluoroether solution containing the silane compound (2) having a poly (perfluoroalkylene ether) chain.

< production of aluminum base Material having anodic oxide coating film >

Production example 1

For an aluminum plate having a purity of 99.99%, anodic oxidation was performed at 17 ℃ for 2 minutes using 0.2M citric acid aqueous solution as an electrolyte at a chemical conversion voltage of 350V. Thereafter, the plate was immersed in a 10wt% phosphoric acid aqueous solution at 50 ℃ for 20 minutes to carry out pore size enlargement treatment. This operation was repeated 5 times to obtain an aluminum material (A) having an anodic oxide film with a pore period of 850 nm. Fig. 6 is a Scanning Electron Microscope (SEM) photograph of the upper surface of the obtained aluminum material (a). Fig. 7 is an SEM photograph of a cross section of the aluminum material (a). From fig. 6 and 7, it can be confirmed that: a fine uneven shape is formed on the surface of the anodic oxidation coating film of the aluminum material (A).

Production example 2

For an aluminum plate having a purity of 99.50%, anodic oxidation was performed for 30 seconds at a chemical conversion voltage of 40V using a 0.3M oxalic acid aqueous solution as an electrolyte. Thereafter, the plate was immersed in a 5wt% phosphoric acid aqueous solution at 30 ℃ for 12 minutes to carry out pore diameter enlargement treatment. This operation was repeated 5 times to obtain an aluminum material (B) having an anodic oxide film with a pore cycle of 100 nm. The surface of the obtained aluminum material (B) was observed with a scanning electron microscope, and it was confirmed that a fine uneven shape was formed on the surface of the anodized film of the aluminum material (B).

Production example 3

For an aluminum plate having a purity of 99.50%, anodic oxidation was performed for 50 seconds at a chemical conversion voltage of 80V using 0.05M oxalic acid aqueous solution as an electrolyte. Thereafter, the plate was immersed in a 5wt% phosphoric acid aqueous solution at 30 ℃ for 30 minutes to carry out pore diameter enlargement treatment. This operation was repeated 5 times to obtain an aluminum material (C) having an anodic oxide film with a pore cycle of 200 nm. The surface of the obtained aluminum material (C) was observed with a scanning electron microscope, and it was confirmed that a fine uneven shape was formed on the surface of the anodized film of the aluminum material (C).

Production example 4

For an aluminum plate having a purity of 99.50%, 0.1M phosphoric acid aqueous solution was used as an electrolyte, and anodization was performed for 5 minutes at a chemical conversion voltage of 200V. Thereafter, the plate was immersed in a 10wt% phosphoric acid aqueous solution at 30 ℃ for 60 minutes to carry out pore diameter enlargement treatment. This operation was repeated 4 times, and further anodic oxidation was carried out under the same conditions for 5 minutes, thereby obtaining an aluminum material (D) having an anodic oxide film with a pore cycle of 500 nm. The surface of the obtained aluminum material (D) was observed with a scanning electron microscope, and it was confirmed that a fine uneven shape was formed on the surface of the anodized film of the aluminum material (D).

Production example 5

For an aluminum plate having a purity of 99.50%, 0.2M citric acid aqueous solution was used as an electrolyte, and anodization was performed for 10 minutes at a chemical conversion voltage of 350V. Thereafter, the plate was immersed in a 10wt% phosphoric acid aqueous solution at 50 ℃ for 20 minutes to carry out pore size enlargement treatment. This operation was repeated 5 times to obtain an aluminum material (E) having an anodic oxide film with a pore period of 850 nm. As a result of observing the surface of the obtained aluminum material (E) with a scanning electron microscope, it was confirmed that a fine uneven shape was formed on the surface of the anodized film of the aluminum material (E).

Production example 6

For an aluminum plate having a purity of 99.50%, 0.2M citric acid aqueous solution was used as an electrolyte, and anodization was performed for 10 minutes at a chemical conversion voltage of 400V. Thereafter, the plate was immersed in a 10wt% phosphoric acid aqueous solution at 50 ℃ for 20 minutes to carry out pore size enlargement treatment. This operation was repeated 5 times to obtain an aluminum material (F) having an anodic oxide film with a pore cycle of 1000 nm.

Production example 7

For an aluminum plate having a purity of 99.50%, 0.3M oxalic acid aqueous solution was used as an electrolytic solution, and anodic oxidation was performed at a chemical conversion voltage of 40V for 75 seconds. Thereafter, the plate was immersed in a 5wt% phosphoric acid aqueous solution at 30 ℃ for 30 minutes to carry out a pore diameter enlarging treatment. This operation was repeated 2 times to obtain an aluminum material (G) having an anodic oxide film with a pore cycle of 100 nm. As a result of observing the surface of the obtained aluminum material (G) with a scanning electron microscope, it was confirmed that a fine uneven shape was formed on the surface of the anodized film of the aluminum material (G).

Production example 8

For an aluminum plate having a purity of 99.50%, 0.3M oxalic acid aqueous solution was used as an electrolytic solution, and anodic oxidation was performed for 250 seconds at a chemical conversion voltage of 80V. Thereafter, the plate was immersed in a 5wt% phosphoric acid aqueous solution at 30 ℃ for 75 minutes to carry out pore diameter enlargement treatment. This operation was repeated 2 times to obtain an aluminum material (H) having an anodic oxide film with a pore cycle of 200 nm.

Comparative production example 1

An aluminum plate having 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. Then, the obtained aluminum plate was immersed in the solution of silane compound (2) of synthesis example 2, and left to stand for 1 hour. Then, the aluminum plate was taken out and dried at 150 ℃ for 30 minutes to obtain an aluminum material (I).

Comparative production example 2

An aluminum plate having a purity of 99.50% was immersed in a 5% triethanolamine aqueous solution at 90 ℃ for 10 minutes, and then washed with water and methanol. The obtained aluminum plate was immersed in the solution of 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 ℃ for 30 minutes to obtain an aluminum material (J).

Comparative production example 3

For an aluminum plate having a purity of 99.99%, anodic oxidation was performed at 17 ℃ for 10 minutes using 0.2M citric acid aqueous solution as an electrolyte at a chemical conversion voltage of 350V. Thereafter, the resultant was immersed in a 10 mass% phosphoric acid aqueous solution at 50 ℃ for 40 minutes to carry out pore diameter enlargement treatment, thereby obtaining an aluminum material (K). Fig. 8 is an SEM photograph of the upper surface of the obtained aluminum material (K). Fig. 9 is an SEM photograph of a cross section of the aluminum material (K). From fig. 8, it can be confirmed that: the surface of the anodized coating of the aluminum material (K) was formed with fine irregularities, but it was confirmed from fig. 9 that: the longitudinal section along the depth direction of the fine pores does not have a shape narrowing from the opening portions of the fine pores to the bottom portions of the fine pores.

Comparative production example 4

An aluminum plate having a purity of 99.99% was anodized at 17 ℃ for 10 minutes at a chemical conversion voltage of 350V using a 0.2M oxalic acid aqueous solution as an electrolyte to obtain an aluminum material (L). Fig. 10 is an SEM photograph of the upper surface of the obtained aluminum material (L). Fig. 11 is an SEM photograph of a cross section of the aluminum material (L). From fig. 10 and 11, it can be confirmed that: the surface of the anodized film of the aluminum material (L) had fine irregularities, but the flat upper surface was damaged.

Comparative production example 5

For an aluminum plate having a purity of 99.50%, anodic oxidation was performed for 15 seconds at a chemical conversion voltage of 40V using a 0.3M oxalic acid aqueous solution as an electrolyte. Thereafter, the resultant was immersed in a 5 mass% phosphoric acid aqueous solution at 30 ℃ for 3 minutes to carry out a pore diameter enlarging treatment, thereby obtaining an aluminum material (M). Fig. 12 is an SEM photograph of the upper surface of the obtained aluminum material (M). Fig. 13 is an SEM photograph of a cross section of the aluminum material (M). From fig. 12 and 13, it can be confirmed that: the surface of the anodized coating of the aluminum material (M) has fine irregularities, but the flat upper surface is damaged, and the longitudinal section along the depth direction of the pores does not have a shape narrowing from the opening of the pores to the bottom of the pores.

Comparative production example 6

For an aluminum plate having a purity of 99.50%, 0.3M oxalic acid aqueous solution was used as an electrolyte, and anodic oxidation was performed at a chemical conversion voltage of 40V for 15 seconds to obtain an aluminum material (N). Fig. 14 is an SEM photograph of the upper surface of the obtained aluminum material (N). Fig. 15 is an SEM photograph of a cross section of the aluminum material (N). From fig. 14 and 15, it can be confirmed that: the surface of the anodized coating of the aluminum material (N) had a fine uneven shape, but the cut surface did not have a shape narrowing from the opening of the pores to the bottom of the pores.

Comparative production example 7

For an aluminum plate having a purity of 99.50%, the aluminum plate was heated at 1A/dm in a 10% sulfuric acid aqueous solution at 20 deg.C ² The current density of (2) was subjected to anodic oxidation treatment for 1 hour. Next, the aluminum plate was immersed in a 5% phosphoric acid aqueous solution at 50 ℃ to carry out a dissolving treatment, thereby obtaining an aluminum material (O). Fig. 16 is an SEM photograph of the upper surface of the obtained aluminum material (O). Fig. 17 is an SEM photograph of a cross section of the aluminum material (O). From fig. 16 and 17, it can be confirmed that: in this aluminum material (O), although a layer having fine pores is formed by anodic oxidation, the surface of the anodic oxidation coating does not have a flat upper surface, and partition walls that further define the fine pores collapse and overlap.

The following treatments were performed on each of the aluminum materials produced above to form a water repellent layer.

[ formation of Water repellent layer 1]

To a solution of silane compound (1) of Synthesis example 1 was added C ₄ F ₉ OC ₂ H ₅ A0.1 mass% solution of the silane compound (1) was prepared. The aluminum materials (a) to (H) were immersed in a 0.1 mass% solution of the silane compound (1), and allowed to stand for 1 hour. Then, the plates were taken out and dried at 150 ℃ for 30 minutes to obtain water-repellent aluminum materials (A) 'to (H)' having a water-repellent layer.

[ formation of Water-repellent layer 2]

To a solution of the silane compound (2) of Synthesis example 2 was added C ₄ F ₉ OC ₂ H ₅ A 0.1 mass% solution of the silane compound (2) was prepared. The aluminum materials (a) to (F) were immersed in a 0.1 mass% solution of the silane compound (2), and allowed to stand for 1 hour. Then, each plate was taken out and dried at 150 ℃ for 30 minutes to obtain water-repellent aluminum materials (A) "to (F)" having a water-repellent layer.

[ formation of Water-repellent layer 3]

Butyl acetate was added to dodecyl methoxysilane to prepare a 0.1 mass% butyl acetate solution of dodecyl methoxysilane. The aluminum material (B) was immersed in a 0.1 mass% butyl acetate solution of dodecylmethoxysilane and allowed to stand for 1 hour. Then, the plate was taken out and dried at 150 ℃ 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) of synthesis example 1, and allowed to stand for 1 hour. Then, the plate was taken out and dried at 150 ℃ for 30 minutes to obtain aluminum materials (K) '- (O)'.

[ formation of Water-repellent layer 5 ]

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. Then, the plate was taken out and dried at 150 ℃ for 30 minutes to obtain aluminum materials (K) "to (N)".

Examples 1 to 8 and comparative examples 1 to 8

The following evaluations were made for each of the obtained aluminum materials. The evaluation results are shown in tables 1 to 3. In the water falling angle measurement, water does not fall off in the aluminum material G, and most of the water remains on the aluminum material G. In the running water durability test, the aluminum materials G, M 'and N' were all in a state in which water did not slip when the water was allowed to flow for 1 hour. Further, the aluminum material O' was in a state where water did not slip off when the water was allowed to flow for 66 hours.

< evaluation method >

[ Water contact Angle measurement ]

The water repellency was evaluated by measuring the contact angle of water. For the evaluation of the contact angle, DM-500, manufactured by Kyowa Kagaku K.K., was used. The angle was set as a value by dropping 5. Mu.L of water droplets onto the substrate. The measurement was performed 3 times, and the average value was defined as a value.

[ measurement of Water slip Angle ]

The water sliding property was evaluated by measuring the water falling angle. Incidentally, DM-500, a product of Kyowa Kagaku K.K., was used for evaluation of the slip angle. 5 μ L of water droplets were dropped on the substrate, the stage was tilted at a rate of 2 degrees/sec, and the angle at which the water droplets started to move was taken as the value of the slip angle. The measurement was performed 3 times, and the average value was defined as a value.

[ running water durability ]

After measuring the water falling angle of each aluminum material, water was allowed to flow down from a tube having an inner diameter of 1mm in an amount of 9.9 mL/min at the portion where the water falling angle was measured, and the change in the water falling angle was measured at predetermined time intervals.

[ Table 1]

[ Table 2]

[ Table 3]

As is clear from the results in tables 1 to 3, the water repellent aluminum materials of the examples are excellent in water repellency, water sliding property and water flow durability. On the other hand, it is determined that: the aluminum materials of the comparative examples are inferior in water repellency, water-sliding property and water flow durability, and therefore the problems of the present invention cannot be solved.

Claims (7)

1. A water repellent aluminum material having: 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 on the opposite side to the aluminum substrate,

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 to the aluminum substrate,

a longitudinal cross section along a depth direction of the fine hole has a shape narrowing from the opening portion of the fine hole to a bottom portion of the fine hole,

the water repellent layer comprises a low surface energy material.

2. The water repellent aluminum material according to claim 1, wherein the shape narrowing from the openings of the pores to the bottoms of the pores is a shape gradually narrowing from the openings of the pores to the bottoms of the pores.

3. The water repellent aluminum material according to claim 1 or 2, wherein the pores are formed by subjecting the surface of the aluminum substrate to the anodizing treatment and the pore diameter enlarging treatment 2 or more times in this order.

4. The water repellent aluminum material according to any one of claims 1 to 3, wherein the pore period of the fine pores is in a range of 100nm or more and 1000nm or less.

5. The water-repellent aluminum material according to any one of claims 1 to 4, wherein the water-repellent layer has a thickness in the range of 1nm or more and 100nm or less.

6. The water repellent aluminum material according to any one of claims 1 to 5, wherein the low surface energy substance is a compound having 1 or more water repellent groups selected from the group consisting of a fluorine-containing group, a silicone-containing group and a hydrocarbon group, and 1 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 group and an alkoxysilyl group.

7. A method for producing a water repellent aluminum material, comprising the steps of:

an anodic oxide film forming step of sequentially performing an anodic oxidation treatment for anodizing the surface of the aluminum substrate to form an anodic oxide film and pores and a pore diameter enlarging treatment for enlarging the pore diameter of the pores formed by the anodic oxidation, for 2 or more times; and (c) and (d),

a water-repellent layer forming step of forming a water-repellent layer containing a low-surface-energy substance along a surface of the anodic oxide film on the side opposite to the aluminum substrate,

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 to the aluminum substrate,

a longitudinal cross section along a depth direction of the fine hole has a shape that is narrowed from the opening portion of the fine hole toward a bottom portion of the fine hole.

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