JPWO2020022213A1 - Pre-coated aluminum material - Google Patents

Abstract

The precoated aluminum material (1) has an aluminum plate (2), a chemical conversion film (3), and a hydrophilic film (4), which are sequentially laminated and formed. The hydrophilic film (4) contains at least an acrylic resin (A), a polyalkylene ether resin (B), a resin (C), and polyvinyl alcohol (D). The acrylic resin (A) does not substantially have a repeating unit derived from a monomer having a sulfo group and a monomer having an amide group. The resin (C) has a repeating unit derived from a monomer having an amide group. The hydrophilic film (4) has two peaks in the wave number range of 1600 to 1800 cm-1 in the infrared absorption spectrum. The ratio of the absorbances of each peak satisfies a predetermined relationship.

Description

The present invention relates to a precoated aluminum material having a hydrophilic film.

Conventionally, as a heat exchanger mounted on an air conditioner, a refrigerator, or the like, a so-called plate fin tube type heat exchanger having a large number of fins and a tube intersecting these fins is often used. The plate fin tube type heat exchanger may exchange heat between the low temperature refrigerant and the outside air, for example, like an indoor unit during cooling operation in an air conditioner.

In this case, when the temperature of the fin becomes lower than the dew point of the outside air, dew condensation water adheres to the surface of the fin. When the amount of this condensed water is large, the gap between the fins is narrowed or blocked in some cases, which may lead to an increase in ventilation resistance, that is, resistance when the airflow passes between the fins. As a result, the heat exchange efficiency may decrease.

In order to solve such a problem, a precoated aluminum material having a hydrophilic film on the surface has been proposed. By press-processing or the like on this pre-coated aluminum material, fins for a heat exchanger having a hydrophilic film on the surface can be produced. On the surface of such fins, the presence of the hydrophilic film makes it easier for water to get wet and spread. Therefore, various techniques have been proposed in which the condensed water is made into a film having a uniform thickness and a thin film to avoid blockage of the gap between the fins and to promote the discharge of the condensed water from the fins.

As a precoated aluminum material of this type, for example, Patent Document 1 discloses an aluminum fin material in which a chemical conversion film is formed on the surface and a hydrophilic film is formed on the chemical conversion film. The hydrophilic film contains a (meth) acrylic resin, polyvinyl alcohol, at least one resin selected from polyethylene oxide and polyethylene glycol, and crosslinkable fine particles.

Japanese Patent No. 5995546

However, the conventional pre-coated aluminum material tends to cause blocking in the hydrophilic film. Therefore, in a high temperature environment such as summer, in order to prevent the occurrence of blocking, measures have been taken to keep the temperature of the precoated aluminum material before winding low by using a powerful cooling device. Such measures will increase the manufacturing cost of the precoated aluminum material.

In recent years, in order to provide heat exchangers at a lower cost, further cost reduction of fins is strongly required. Increasing the blending ratio of the (meth) acrylic resin or polyvinyl alcohol, which is the skeleton component of the hydrophilic film of the precoated aluminum material, makes it possible to suppress the occurrence of blocking, but the moisture resistance of the hydrophilic film is inferior and it corrodes after being exposed to water. Since odor and acid odor are generated and the wet adhesion is lowered, improvement is desired.

As described above, the precoated aluminum material in recent years is required to have various performances in addition to hydrophilicity and its durability. The present invention has been made in view of this background, and will provide a precoated aluminum material having excellent blocking resistance, odor resistance, acid odor, hydrophilicity, hydrophilic durability, wet adhesion, and press moldability. Is to be.

One aspect of the present invention is a precoated aluminum material in which an aluminum plate, a chemical conversion film, and a hydrophilic film are sequentially laminated and formed.
The hydrophilic film is an acrylic resin (A) of 15 to 20% by mass, a polyalkylene ether resin (B) of 30 to 40% by mass, and a resin (C) of 20 to 20 to 40% having a repeating unit derived from a monomer having an amide group. It contains at least 25% by mass and 22 to 28% by mass of polyvinyl alcohol (D).
The acrylic resin (A) does not substantially have a repeating unit derived from a monomer having a sulfo group and a repeating unit derived from a monomer having an amide group.
The acrylic resin (A) has a weight average molecular weight of 20000 to 20000 and an acid value of 100 to 800 mgKOH / g.
The polyalkylene ether resin (B) has a weight average molecular weight of 5000 to 500000.
^{The hydrophilic film has two peaks in the range of 1600 to 1800 cm-1} in the infrared absorption spectrum, and the absorbance a at the peak top of the peak A on the low wave number side of the two peaks and the absorbance a on the high wave number side. The absorbance b at the peak top of the peak B is in the precoated aluminum material that satisfies the relationship of absorbance a / absorbance b = 0.6 to 1.3.

In the precoated aluminum material, the hydrophilic film includes the above-mentioned predetermined acrylic resin (A), the above-mentioned predetermined polyalkylene ether resin (B), and a resin (C) having a repeating unit derived from a monomer having an amide group. , Polyvinyl alcohol (D) is contained in a predetermined content ratio. The infrared absorption spectrum of the hydrophilic coating has two peaks in the wave number range of 1600cm ^-1 ~1800cm ^-1, and the absorbance a of the peak top in the peak A, and the absorbance b of the peak top in the peak B Satisfy the above-mentioned predetermined relationship.

Since it has the above structure, the precoated aluminum material has improved cohesive force of the hydrophilic film and high toughness. Therefore, the precoated aluminum material has excellent blocking resistance. Therefore, blocking is unlikely to occur after winding without using a powerful cooling device. As a result, the manufacturing cost can be reduced.

Further, since the hydrophilic film has high cohesive force and high toughness, the barrier property of the hydrophilic film is high and the moisture resistance is excellent. Therefore, it is unlikely that a corrosive odor will be generated even after being exposed to water. That is, it is excellent in odor resistance after the moisture resistance test.

Further, the hydrophilic film exhibits excellent hydrophilicity and also has excellent hydrophilicity sustainability. Furthermore, the pre-coated aluminum material is also excellent in press moldability, wet adhesion, and acid odor. Therefore, the precoated aluminum material is suitable for, for example, the fins of a heat exchanger.

As described above, according to the present invention, it is possible to provide a precoated aluminum material having excellent blocking resistance, odor resistance, acid odor, hydrophilicity, hydrophilicity persistence, wet adhesion, and press moldability.

FIG. 3 is a cross-sectional view of a main part of a precoated aluminum material in an embodiment. The figure which shows the infrared absorption spectrum of the hydrophilic film in Example 5. The figure which shows the infrared absorption spectrum of the hydrophilic film in the comparative example 2. FIG.

[Aluminum plate]
In the precoated aluminum material, the material of the aluminum plate can be appropriately selected from pure aluminum and aluminum alloy according to desired mechanical properties, corrosion resistance and the like. The aluminum plate is preferably composed of JIS A1200 or JIS A1050. In this case, since the precoated aluminum material has excellent thermal conductivity, it is more suitable for the fins of the heat exchanger.

[Chemical film]
A chemical conversion film is provided on the surface of the aluminum plate. The chemical conversion film improves the adhesion between the aluminum plate and the hydrophilic film or the corrosion-resistant film described later, and improves the corrosion resistance.

The chemical conversion coating is formed by a chemical coating treatment (that is, a chemical conversion treatment). Specifically, the chemical conversion film is formed by a phosphoric acid chromate treatment. The chemical conversion film is also formed by non-chromate treatment of titanium phosphate, zirconium phosphate, molybdenum phosphate, zinc phosphate, zirconium oxide and the like. There are two types of chemical conversion treatment methods, reaction type and coating type, but any method may be used.

The adhesion amount of the chemical conversion film can be appropriately selected from, for example, a range in which the metal content is 5 to 50 mg / m ^2. The amount of the chemical conversion film adhered can be measured by a fluorescent X-ray analyzer.

[Hydrophilic film]
The hydrophilic film is formed on the surface of the chemical conversion film or the surface of the corrosion resistant film described later. The hydrophilic film contains at least an acrylic resin (A), a polyalkylene ether resin (B), a resin (C) having a repeating unit derived from a monomer having an amide group, and polyvinyl alcohol (D). The "repeating unit" means a unit of a structure that is repeated in a resin, and is sometimes called a repeating structural unit. The repeating unit generally has a structure derived from the monomer used in the production of the resin.

<Acrylic resin (A)>
The acrylic resin (A) satisfies the following (1) to (3).
(1) It has substantially no repeating unit derived from a monomer having a sulfo group and a repeating unit derived from a monomer having an amide group. This means that the repeating unit constituting the acrylic resin (A) has substantially no sulfo group and amide group.
(2) The weight average molecular weight is 20000 to 20000.
(3) The acid value is 100 to 800 mgKOH / g.

The acrylic resin (A) enhances the adhesion between the hydrophilic film and the chemical conversion film, and enhances the hydrophilicity of the hydrophilic film. In the present specification, the acrylic resin (A) is a concept including not only an acrylic resin but also a methacrylic resin. That is, the acrylic resin (A) is a (meth) acrylic resin. The (meth) acrylic resin means at least one of an acrylic resin and a methacrylic resin.

The acrylic resin (A) contains a repeating unit derived from at least one of an acrylic acid monomer and a methacrylic acid monomer. The total content of the repeating unit derived from the acrylic acid monomer and the repeating unit derived from the methacrylic acid monomer is not particularly limited, but is preferably 50 to 100% by mass.

The acrylic resin (A) may contain a repeating unit other than the repeating unit derived from the acrylic acid monomer and the repeating unit derived from the methacrylic acid monomer. For example, it is a repeating unit derived from an acrylic acid monomer or a derivative of a methacrylic acid monomer.

Specifically, there is a monomer having one polymerizable unsaturated bond in the molecule. Examples of such monomers include alkyl methacrylates such as methyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, n-octyl methacrylate, lauryl methacrylate, and stearyl methacrylate; methyl acrylate and n-butyl. Alkyl acrylates such as acrylates, i-butyl acrylates, 2-ethylhexyl acrylates, isononyl acrylates and n-octyl acrylates; aralkyl methacrylates such as benzyl methacrylate; alkoxyalkyl methacrylates such as butoxyethyl methacrylate; alkoxyalkyl acrylates such as butoxyethyl acrylates and the like. Can be mentioned. These may be used alone or in combination of two or more.

Further, the (meth) acrylic resin (A) may contain a component other than the above-mentioned monomer, but a repeating unit derived from a monomer having a sulfo group and a repeating unit derived from a monomer having an amide group may be used. Substantially not included. If these are included, it is difficult to suppress the generation of odor when adsorbing an acid component in the atmosphere, and the acid odor is inferior.

(Content of acrylic resin (A))
The content of the acrylic resin (A) in the hydrophilic film is 15 to 20% by mass. In this case, the absorbance a / absorbance b can be easily adjusted to a desired range of 0.6 to 1.3 while increasing the hydrophilicity of the precoated aluminum material. If it is less than 15% by mass, the wet adhesion is inferior, and if it exceeds 20% by mass, the acid odor is inferior. The content of the acrylic resin (A) means the content of the acrylic resin (A), the polyalkylene ether resin (B), the resin (C), and the polyvinyl alcohol (D) with respect to the total resin component. The same applies to the contents of the polyalkylene ether resin (B), the resin (C), and the polyvinyl alcohol (D).

(Acid value of acrylic resin (A))
The acid value of the acrylic resin (A) is 100 to 800 mgKOH / g. When the acid value of the acrylic resin (A) is less than 100 mgKOH / g, the adhesion between the hydrophilic film and the metal surface is lowered, and the wet adhesion is inferior. When the acid value of the acrylic resin (A) exceeds 800 mgKOH / g, the hydrophilic film adsorbs the acid component in the atmosphere and the acid odor is reduced. From the viewpoint of further enhancing the adhesion of the hydrophilic film, the acid value of the acrylic resin (A) is preferably 500 mgKOH / g or more. From the viewpoint of further enhancing the odor resistance, the acid value of the acrylic resin (A) is preferably 800 mgKOH / g or less as described above.

(Weight average molecular weight of acrylic resin (A))
The weight average molecular weight of the acrylic resin (A) is 20000 to 2000000. When the weight average molecular weight of the acrylic resin (A) is less than 20000, the hydrophilicity persistence is lowered. When the weight average molecular weight of the acrylic resin (A) exceeds 2000000, the viscosity of the hydrophilic treatment agent used for forming the hydrophilic film, which will be described later, becomes high and the workability is deteriorated. When the weight average molecular weight of the acrylic resin (A) is small, when the water comes into contact with the hydrophilic film, the acrylic resin (A) existing near the boundary on the surface side of the aluminum plate moves to the surface side of the hydrophilic film. It will move. As a result, the adhesion between the hydrophilic film and the metal surface is reduced. Further, if the weight average molecular weight is too small, the adhesion between the hydrophilic film and the metal surface is lowered because the acrylic resin is easily eluted in water. When the weight average molecular weight of the acrylic resin is within the above range, the problem of deterioration of the adhesion between the hydrophilic film and the metal surface does not occur even if water continues to adhere to the surface of the hydrophilic film. The preferable range of the weight average molecular weight of the acrylic resin (A) is 20000 to 100,000.

As the value of the weight average molecular weight, the value measured by the gel permeation chromatography (GPC) method is adopted. Specifically, a solution prepared by dissolving 0.4 parts by mass of a resin sample in 100 parts by mass of tetrahydrofuran was used as a sample solution, and this was used by LC-08 (A-5432) type GPC manufactured by Analytical Industry Co., Ltd. Measure and calculate by polystyrene conversion.

<Polyalkylene ether resin (B)>
The polyalkylene ether resin (B) can impart lubricity to the hydrophilic film and enhance moldability when the surface of the precoated aluminum material is press-processed.

Examples of the polyalkylene ether resin (B) include polyoxyethylene such as polyethylene oxide and polyethylene glycol; and polyoxypropylene such as polypropylene oxide and polypropylene glycol.

The weight average molecular weight of the polyalkylene ether resin (B) is 5000 to 500000. By setting the weight average molecular weight to 5000 or more, it is possible to prevent unwinding after winding the precoated aluminum material. Further, by setting the content to 500,000 or less, it is possible to prevent the viscosity of the coating material for forming the hydrophilic film from becoming too high, and the coatability is improved.

(Content of polyalkylene ether resin (B))
The content of the polyalkylene ether resin (B) is 30 to 40% by mass. If it is less than 30% by mass, the press moldability is lowered. If it exceeds 40% by mass, the film component may elute into water, and as a result, the hydrophilicity persistence is inferior. From the viewpoint of further enhancing press moldability and hydrophilicity persistence, the content of the polyalkylene ether resin (B) is more preferably 31 to 39% by mass.

<Resin (C)>
The resin (C) is a resin having a repeating unit derived from a monomer having an amide group. That is, the resin (C) has a repeating unit derived from a monomer having an amide group in at least one of the repeating structural units of the polymer constituting the resin. The resin (C) can enhance the hydrophilicity persistence.

As the monomer having an amide group, at least one selected from the group consisting of N-methylolacrylamide, N-methylolmethacrylamide, N-hydroxyethylacrylamide, and N-hydroxyethylmethacrylamide can be used. Preferably, the resin (C) is a repeating unit derived from at least one monomer selected from the group consisting of N-methylolacrylamide, N-methylolmethacrylamide, N-hydroxyethylacrylamide, and N-hydroxyethylmethacrylamide. , It may be contained in at least one of the repeating structural units constituting the resin. That is, in the resin (C), it is preferable that at least one of these monomers is a repeating unit constituting the polymer. In this case, it is possible to obtain the effect of increasing the cohesive force of the coating film and enhancing the hydrophilicity persistence.

The resin (C) is more preferably a copolymer of the above-mentioned (meth) acrylamide monomer and the following monomer copolymerizable. (Meta) acrylamide means at least one of acrylamide and methacrylamide. Examples of the copolymerizable monomer include a polyoxyalkylene chain such as methoxypolyethylene glycol monomethacrylate, methoxypolyethylene glycol monoacrylate, and octoxypolyethylene glycol-polypropylene glycol monoacrylate, and a monomer having a polymerizable double bond; acrylic acid and methacrylic acid. , Itaconic acid, maleic acid, vinyl monomer such as vinyl acetate group; 2-hydroxyethyl acrylate, hydroxypropyl acrylate and the like.

(Content of resin (C))
The content of the resin (C) is 20 to 25% by mass. In this case, the absorbance a / absorbance b can be easily adjusted to the desired range while increasing the hydrophilicity persistence of the precoated aluminum material. From the viewpoint of further enhancing this effect, the content of the resin (C) is preferably 21 to 24% by mass. When the content of the resin (C) is less than 20% by mass, the hydrophilicity is inferior. On the other hand, if it exceeds 25% by mass, the wet adhesion is inferior.

<Polyvinyl alcohol (D)>
The hydrophilic film contains polyvinyl alcohol (D). Polyvinyl alcohol (D) can be obtained, for example, by saponifying a polymer obtained by polymerizing polyvinyl acetate.

(Content of polyvinyl alcohol (D))
The content of polyvinyl alcohol (D) is 22 to 28% by mass. When the content of polyvinyl alcohol (D) is less than 22% by mass, the wet adhesion is inferior. On the other hand, when it exceeds 28% by mass, the hydrophilicity and the hydrophilicity persistence are inferior.

<Other additives>
If necessary, a defoaming agent, a leveling agent, an anti-repellent agent, a dispersant, a surfactant, a coloring agent, an antioxidant, an anti-aging agent and the like can be added to the hydrophilic film.

<Infrared absorption spectrum of hydrophilic film>
Hydrophilic coating has two peaks in the wave number range of 1600cm ^-1 ~1800cm ^-1 in the infrared absorption spectrum. The peak on the low wavenumber side is peak A, and the peak on the high wavenumber side is peak B.

The absorbance a at the peak top of the peak A and the absorbance b at the peak top of the peak B satisfy the relationship of absorbance a / absorbance b = 0.6 to 1.3. That is, the ratio of the absorbance a to the absorbance b (that is, the absorbance a / absorbance b) is 0.6 to 1.3. When the absorbance a / absorbance b is less than 0.6, the number of components having an amide group is too small, the cohesive force of the coating film is insufficient, and the toughness of the coating film is insufficient. As a result, the odor resistance of the hydrophilic film deteriorates. On the other hand, if it exceeds 1.3, the number of components having an ester group or a carboxyl group is too small, and the blocking resistance is deteriorated. From the viewpoint of improving the odor resistance and the blocking resistance in a more balanced manner, the absorbance a / absorbance b is preferably 0.7 to 1.2.

The peak A is a peak derived from the expansion / contraction vibration of C = O in the amide group. Peak A is located, for example, in the range of ^{1650 to 1660 cm -1.} The peak B is a peak derived from the C = O expansion / contraction vibration of the ester group or the carboxyl group. Peak B is located, for example, within the range of ^{1710 to 1730 cm -1.}

Absorbance a / absorbance b is the monomer component and its ratio constituting the acrylic resin (A), the monomer component and its ratio constituting the resin (C), the blending ratio of the acrylic resin (A) and the resin (C), and the like. It is adjusted appropriately according to the seizure conditions and the like. The infrared absorption spectrum of the hydrophilic film is measured by a total reflection measurement method (that is, ATR method) of a Fourier transform infrared spectrophotometer (that is, FT-IR), a high sensitivity reflection measurement method (IRRAS), or the like. In the measurement result of at least one of these measurement methods, the absorbance a / absorbance b is preferably within the above range, and at least the absorbance a / absorbance b by FT-IR is more preferably within the above range.

<Amount of hydrophilic film adhered>
The amount of the hydrophilic film adhered is preferably ^{0.3 to 2.0 g / m 2.} When the amount of adhesion is within this range, the press formability of the precoated aluminum material is further improved while suppressing the increase in cost due to the increase in the amount of adhesion. From the viewpoint of further enhancing this effect, the amount of the hydrophilic film adhered is more preferably ^{0.5 to 1.4 g / m 2.}

[Corrosion resistant film]
The precoated aluminum material may have a corrosion resistant film between the chemical conversion film and the hydrophilic film. The corrosion resistant film improves the corrosion resistance of the precoated aluminum material. The corrosion-resistant film contains at least one resin selected from the group consisting of urethane-based resins, epoxy-based resins, acrylic-based resins, and polyolefin-based resins.

The amount of the corrosion-resistant film adhered is preferably ^{0.3 to 2.0 g / m 2.} If it is less than 0.3 g / m ² , it becomes difficult to sufficiently obtain the effect of improving corrosion resistance. If it exceeds 2.0 g / m ² , the material cost increases, and it becomes difficult to obtain the effect of improving the corrosion resistance commensurate with the cost increase.

<Method of forming hydrophilic film>
First, an acrylic resin (A), a polyalkylene ether resin (B), a resin (C), and polyvinyl alcohol (D) are used as essential components and dispersed in a liquid such as ion-exchanged water to prepare a coating material. Such paints are sometimes referred to as hydrophilizing agents. Next, the paint is applied to the aluminum plate on which the chemical conversion film, the corrosion resistant film and the like are formed, using a roll coater or a bar coater. After that, the paint is baked and dried in a hot air drying furnace, a far infrared ray furnace, a near infrared ray furnace, or the like. At this time, it is preferable to dry at a temperature of 150 to 300 ° C. for 3 to 20 seconds. In this way, a hydrophilic film can be formed.

Each of the resins (A) to (D) exists as a solid content in the paint. Therefore, from the viewpoint of obtaining a hydrophilic film having the above composition, in the paint, for example, the solid content of the acrylic resin (A) is 15 to 20% by mass, and the solid content of the polyalkylene ether resin (B) is 15 to 20% by mass. The content of the solid content of the resin (C) can be set to 30 to 40% by mass, the content of the solid content of the resin (C) can be set to 20 to 25% by mass, and the content of the solid content of the polyvinyl alcohol (D) can be set to 22 to 28% by mass. can.

[Use of pre-coated aluminum material]
The precoated aluminum material is preferably used for the fins of the plate fin tube type heat exchanger. In this case, the fins made of pre-coated aluminum material exhibit excellent hydrophilicity. Therefore, it is possible to suppress the accumulation of condensed water on the fins. In addition, the fins show excellent odor resistance, and corrosive odors are less likely to be generated after being exposed to water.

In addition, the pre-coated aluminum material has excellent blocking resistance. Therefore, in a high temperature environment such as summer, it is easy to prevent the occurrence of blocking when the precoated aluminum material is wound up. Specifically, the cooling strength at the time of winding is relaxed, and in some cases, the need for cooling is eliminated. Therefore, the manufacturing cost of the pre-coated aluminum material can be reduced. Further, the pre-coated aluminum material is excellent in press moldability. Therefore, the fin tube type heat exchanger can be easily manufactured.

Examples of the present invention will be described below, but specific embodiments of the precoated aluminum material according to the present invention are not limited to the embodiments of the examples, and are appropriately configured as long as the gist of the present invention is not impaired. Can be changed.

[Examples 1 to 9]
As illustrated in FIG. 1, the precoated aluminum material 1 of the example has an aluminum plate 2, a chemical conversion film 3, and a hydrophilic film 4. In the precoated aluminum material 1, the aluminum plate 2, the chemical conversion film 3, and the hydrophilic film 4 are sequentially laminated.

Specifically, the chemical conversion film 3 is formed on the surface of the aluminum plate 2, and the hydrophilic film 4 is formed on the surface of the chemical conversion film 3. The chemical conversion film 3 and the hydrophilic film 4 may be formed on one side of the aluminum plate 2 or on both sides.

The chemical conversion film 3 is a phosphoric acid chromate-treated film. The hydrophilic film 4 contains an acrylic resin (A), a polyalkylene ether resin (B), a resin (C), and a polyvinyl alcohol (D) as essential components.

The acrylic resin (A) is a resin having no repeating unit derived from a monomer having a sulfo group and a monomer having an amide group. Further, the resin (C) is a resin having a repeating unit derived from a monomer having an amide group.

Specifically, in this example, the following (1) to (9) are used as the acrylic resin (A). The following a to c are used as the polyalkylene ether resin (B). The following α to γ are used as the resin (C). The following polyvinyl alcohol (D) is used.

"Acrylic resin (A)"
(1) Polyacrylic acid (weight average molecular weight: 20000, acid value: 780 mgKOH / g)
(2) Polyacrylic acid (weight average molecular weight: 2000000, acid value: 800 mgKOH / g)
(3) Copolymer of polyacrylic acid and hydroxyethyl methacrylate (weight average molecular weight: 400,000, acid value: 400 mgKOH / g)
(4) Polyacrylic acid (weight average molecular weight: 20000, acid value: 100 mgKOH / g)
(5) Polyacrylic acid (weight average molecular weight: 6000, acid value: 780 mgKOH / g)
(6) Polyacrylic acid (weight average molecular weight: 20000, acid value: 40 mgKOH / g)
(7) Polyacrylic acid (weight average molecular weight: 20000, acid value: 820 mgKOH / g)
(8) Polyacrylic sulfonic acid (weight average molecular weight: 20000, acid value: 200 mgKOH / g)
(9) Polyacrylamide (weight average molecular weight: 20000, acid value: 200 mgKOH / g)

"Polyalkylene ether resin (B)"
a: Polyethylene glycol, weight average molecular weight: 5000
b: Polyethylene oxide, weight average molecular weight: 500000
c: Polyethylene glycol, weight average molecular weight: 1000

"Resin (C)"
α: Copolymer of N-methylolacrylamide and acrylic acid β: Copolymer of N-methylolmethacrylamide and methacrylic acid γ: Copolymer of N-hydroxyethylacrylamide and methacrylic acid

"Polyvinyl alcohol (D)"
Degree of polymerization: 500, degree of saponification: 98.0 mol%

In the production of the pre-coated aluminum materials of Examples 1 to 9, first, a JIS A1200P aluminum plate having a plate thickness of 0.10 mm was prepared. After alkaline degreasing, the aluminum plate was subjected to phosphoric acid chromate treatment. As a result, a phosphoric acid chromate-treated film was formed as a chemical conversion film on the surface of the aluminum plate.

Next, the acrylic resin (A), the polyalkylene ether resin (B), the resin (C), and the polyvinyl alcohol (D) were dispersed in pure water at the ratios shown in Table 1 described later. As a result, a paint for forming a hydrophilic film was produced. Then, using a roll coater, the coating material of each example adjusted with the formulation shown in Table 1 was applied onto the chemical conversion film. Then, the paint was baked by heating. As a result, a hydrophilic film was formed. In this way, the pre-coated aluminum material of each example was produced.

Next, the infrared absorption spectrum of the hydrophilic film of each precoated aluminum material was measured by the ATR method of FT-IR. The measuring device and measuring conditions are as follows.
Measuring device: FT-IR Microscope (Fourier transform infrared spectrometer) manufactured by Bruker Optics
Measurement conditions: 15 scans, 4 resolution

The results of Example 5 are shown in FIG. 2 as a representative example of the infrared absorption spectrum of the hydrophilic film in the examples. As shown in FIG. 2, in the infrared absorption spectrum of Example 5, two peaks are confirmed in the range of ^{wave number 1600 to 1800 cm -1.} In FIG. 2, the horizontal axis shows the wave number, the right side in the horizontal axis direction shows the small wave number, and the left side shows the large wave number. Of the two peaks, the peak on the right side in the horizontal axis direction (that is, the low wave number side) is "peak A", and the peak on the left side in the horizontal axis direction (that is, the high wave number side) is "peak B". The absorbance at the peak top of the peak A is "absorbance a", and the absorbance at the peak top of the peak B is "absorbance b". The same applies to "peak A", "peak B", "absorbance a", and "absorbance b" in the infrared absorption spectrum of FIG. 3, which will be described later. From the infrared absorption spectrum of the hydrophilic film of each example, the absorbance a of peak A and the absorbance b of peak B were measured, and the ratio (specifically, absorbance a / absorbance b) was calculated. The results are shown in Table 1.

Next, the precoated aluminum materials of each example were evaluated for blocking resistance, odor resistance, acid odor, hydrophilicity, hydrophilic persistence, wet adhesion, and press moldability by the following methods. A and B pass, and C fails. The results are shown in Table 1.

<Blocking resistance>
The coated surfaces of the pre-coated aluminum materials were overlapped and heated by hot pressing at 50 ° C. and 10 MPa for 15 minutes. After that, the pre-coated aluminum materials were peeled off, and the sticking state was evaluated according to the following criteria.
A: The pre-coated aluminum materials could be peeled off after heating.
C: The pre-coated aluminum materials could not be peeled off after heating.

<Odor resistance>
For each pre-coated aluminum material, a moisture resistance test was carried out for 144 hours in accordance with JIS K5600-7-2: 1999. Then, the odor on the surface of the hydrophilic film was evaluated by sensory evaluation according to the following criteria. There were 10 panelists, and the average value was adopted.
A: Almost no odor was observed.
B: A slight odor was observed.
C: Significant odor was observed.

<Acid odor>
After each precoated aluminum material was immersed in pure water for 1 hour, 0.5 g of acetic acid was placed in a container and contaminated at room temperature for 72 hours. It was taken out and left in the air, and after 5 hours, the odor was evaluated according to the following evaluation criteria. The value obtained by averaging the evaluations of 10 evaluators was used as the evaluation result.
A: Odorless.
B: I feel a slight odor.
C: I feel a strong odor.

<Hydrophilic>
The hydrophilicity was evaluated by measuring the contact angle of water using an automatic contact angle meter. As the automatic contact angle meter, a FACE automatic contact angle meter "CA-Z" manufactured by Kyowa Surface Chemistry Co., Ltd. was used. Specifically, in an environment where the room temperature was controlled within the range of 20 ± 5 ° C., water droplets were dropped onto the hydrophilic film of each precoated aluminum material. Then, the contact angle of the water droplet 30 seconds after the dropping was measured by an automatic contact angle meter, and evaluated according to the following criteria.
A: When the contact angle is 20 ° or less C: When the contact angle exceeds 20 ° In the evaluation of hydrophilicity, when the evaluation result is "A", the hydrophilicity is high and the ventilation resistance due to condensed water increases. Since it can be suppressed, it was judged to be acceptable, and when the evaluation result was "C", it was judged to be unacceptable because the hydrophilicity was low and it was difficult to suppress the increase in ventilation resistance due to condensed water.

<Hydrophilic persistence>
After immersing each precoated aluminum material in pure water for 240 hours, the contact angle with water droplets was evaluated. The method for measuring the contact angle is the same as the above-mentioned evaluation of hydrophilicity. The evaluation was performed according to the following criteria.
A: When the contact angle is 30 ° or less C: When the contact angle exceeds 30 °

<Wet adhesion>
Pure water was sprayed on each pre-coated aluminum material and lightly rubbed with a finger. One round trip was set as one time, and the number of times until the hydrophilic film was peeled off was evaluated.
A: 5 times or more.
C: 4 times or less.

<Press moldability>
Processing oil was applied to the surface of each precoated aluminum material. Next, a single press was carried out so that the drawing ratio was 48%, and a collar portion was formed on the precoated aluminum material. Then, the degree of peeling of the hydrophilic film in the collar portion was observed, and the press moldability was evaluated according to the following criteria.
A: No change was seen.
B: Slight peeling was observed.
C: Vertical streaks were observed.

[Comparative Examples 1 to 16]
Except for using a paint in which acrylic resin (A), polyalkylene ether resin (B), resin (C), and polyvinyl alcohol (D) are dispersed in pure water at the ratio shown in Table 1 below. The operation was performed as in Examples 1 to 9. The results of Comparative Examples 1 to 16 are shown in Table 2. The results of Comparative Example 2 are shown in FIG. 3 as a representative example of the infrared absorption spectrum of the hydrophilic film in Comparative Example.

As shown in Table 1, the hydrophilic films of Examples 1 to 9 do not have repeating units derived from the monomer having a sulfo group and the monomer having an amide group, and the weight average molecular weight and the acid value are in a predetermined range. Acrylic resin (A), polyalkylene ether resin (B) having a weight average molecular weight in a predetermined range, a resin (C) having a repeating unit derived from a monomer having an amide group, and polyvinyl alcohol (D). Is contained in a predetermined ratio. In the hydrophilic film of Examples 1 to 9, the absorbance a / absorbance b in the infrared absorption spectrum is in the range of 0.6 to 1.3. Examples 1 to 9 having such a hydrophilic film showed good results in all of blocking resistance, odor resistance, acid odor, hydrophilicity, hydrophilic persistence, wet adhesion, and press moldability.

On the other hand, in Comparative Examples 1 and 3, the absorbance a / absorbance b in the infrared absorption spectrum of the hydrophilic film is less than 0.6. Such a hydrophilic film was inferior in odor resistance. Further, since the acrylic resin (A) exceeds 20% by mass, the acid odor is inferior. Next, in Comparative Examples 2 and 4, the absorbance a / absorbance b in the infrared absorption spectrum of the hydrophilic film exceeds 1.3 for A / B. Such a hydrophilic film was inferior in blocking resistance. Further, since the resin (C) exceeds 25% by mass, the wet adhesion is inferior.

In Comparative Example 5, the absorbance a / absorbance b in the infrared absorption spectrum of the hydrophilic film exceeded 1.3, so that the blocking resistance was inferior. Further, since the acrylic resin (A) was less than 15% by mass, the wet adhesion was inferior.

In Comparative Example 6, since the content of the polyalkylene ether resin (B) was less than 30% by mass, the press moldability was inferior. In Comparative Example 7, since the content of the polyalkylene ether resin (B) exceeded 40% by mass, the hydrophilicity persistence was inferior. In Comparative Example 8, since the content of polyvinyl alcohol (D) was less than 22% by mass, the wet adhesion was inferior.

In Comparative Example 9, since the content of polyvinyl alcohol (D) exceeded 28% by mass, the hydrophilicity and the hydrophilicity persistence were inferior. In Comparative Example 10, since the absorbance a / absorbance b in the infrared absorption spectrum of the hydrophilic film was less than 0.6, the odor resistance was inferior. Further, since the content of the resin (C) was less than 20% by mass, the hydrophilicity persistence was inferior.

In Comparative Example 11, since the weight average molecular weight of the acrylic resin (A) was less than 20000, the hydrophilicity persistence was inferior. In Comparative Example 12, since the acid value of the acrylic resin (A) was less than 100 mgKOH / g, the wet adhesion was inferior. In Comparative Example 13, the acid value of the acrylic resin (A) exceeded 800 mgKOH / g, so that the acid odor was inferior.

In Comparative Example 14, since the weight average molecular weight of the polyalkylene ether resin (B) was less than 5000, winding misalignment occurred during winding. This means that pre-coated aluminum materials cannot be manufactured. In Comparative Example 15, since the acrylic resin (A) had a repeating unit derived from a monomer having a sulfo group, the acid odor was inferior. In Comparative Example 16, since the acrylic resin (A) had a repeating unit derived from a monomer having an amide group, the acid odor was inferior.

Claims (2)

A pre-coated aluminum material in which an aluminum plate, a chemical conversion film, and a hydrophilic film are sequentially laminated and formed.
The hydrophilic film is an acrylic resin (A) of 15 to 20% by mass, a polyalkylene ether resin (B) of 30 to 40% by mass, and a resin (C) of 20 to 20 to 40% having a repeating unit derived from a monomer having an amide group. It contains at least 25% by mass and 22 to 28% by mass of polyvinyl alcohol (D).
The acrylic resin (A) does not substantially have a repeating unit derived from a monomer having a sulfo group and a repeating unit derived from a monomer having an amide group.
The acrylic resin (A) has a weight average molecular weight of 20000 to 20000 and an acid value of 100 to 800 mgKOH / g.
The polyalkylene ether resin (B) has a weight average molecular weight of 5000 to 500000.
^{The hydrophilic film has two peaks in the range of 1600 to 1800 cm-1} in the infrared absorption spectrum, and the absorbance a at the peak top of the peak A on the low wave number side of the two peaks and the absorbance a on the high wave number side. A precoated aluminum material in which the absorbance b at the peak top at the peak B of the above satisfies the relationship of absorbance a / absorbance b = 0.6 to 1.3. The precoated aluminum material according to claim 1, wherein the precoated aluminum material is used for fins of a heat exchanger.

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