JP2022032624A - Precoated fin material - Google Patents

Abstract

To provide a precoated fin material that can keep excellent hydrophilicity for a long time and allows easy removal of oily contaminants deposited on the surface.SOLUTION: A precoated fin material 1 has a substrate 2 and a resin coating film 3 formed on the substrate 2. The resin coating film 3 contains a modified polyvinyl alcohol (A) having the molecular structure represented by the general formula (1) below and an acrylamide polymer (B). The content of the modified polyvinyl alcohol (A) is 0.5 times or more and 2.0 times or less the content of the acrylamide polymer (B) in the mass ratio.SELECTED DRAWING: Figure 1

Description

The present invention relates to a precoated fin material.

As a heat exchanger mounted on an air conditioner, a refrigerator, or the like, a so-called cross-fin tube type heat exchanger having a large number of fins and a tube intersecting these fins is often used. The fins are manufactured by pressing a precoated fin material having a substrate made of aluminum (including pure aluminum and an aluminum alloy; the same applies hereinafter) and a resin film provided on the substrate.

If the surface temperature of the fins falls below the dew point of air during the operation of an air conditioner or the like, the surface of the fins may condense and the gaps between the fins may be blocked by the dew water. If the gap between the fins is closed, the heat exchange efficiency of the heat exchanger may decrease.

To solve this problem, there is known a technique of suppressing the blockage of gaps between fins due to dew condensation water by increasing the hydrophilicity of the surface of the fins. For example, Patent Document 1 describes (A) at least one polymer selected from polyglycerin and polyvinyl alcohol, (B) a high acid value acrylic resin having a resin acid value of 300 mgKOH / g or more, and (C) the above polymer (C). A hydrophilized composition containing a water-soluble resin other than A) and the high acid value acrylic resin (B), wherein the hydrophilized composition has a resin acid value of 200 mgKOH / g or more. Further, a hydrophilization treatment composition for a heat exchanger fin material, which has a hydroxyl value of 100 mgKOH / g or more, is described.

JP-A-2002-38134

However, if dew condensation water adheres to the surface of the fin during use of the heat exchanger, the hydrophilic substance in the resin film is washed away by the dew condensation water, so that the hydrophilicity of the surface of the fin gradually decreases. Further, oily contaminants present in the environment such as higher fatty acids and higher alcohols adhere to the surface of the fins with the use of the heat exchanger. These contaminants can lead to a decrease in the hydrophilicity of the fin surface.

As described above, the conventional fin has a problem that the hydrophilicity gradually decreases during the use of the heat exchanger due to the decrease of the hydrophilic substance due to the condensed water and the adhesion of the oily pollutant.

The present invention has been made in view of this background, and is a precoated fin material capable of maintaining excellent hydrophilicity for a long period of time and easily removing oily contaminants adhering to the surface. Is intended to provide.

One aspect of the present invention is a substrate made of aluminum and a substrate.
It has a resin coating film formed on the substrate and exposed on the surface thereof.
The resin coating film is
Modified polyvinyl alcohol (A) having a molecular structure represented by the following general formula (1) and
Containing with an acrylamide polymer (B),
The content of the modified polyvinyl alcohol (A) is 0.5 times or more and 2.0 times or less the content of the acrylamide-based polymer (B) in terms of mass ratio.
It is in the pre-coated fin material.

However, R ¹ in the general formula (1) is an organic group having a linear structure and having 5 or more and 10 or less carbon atoms, and m and n satisfy the relationship of 0.005 ≦ n / m ≦ 0.025. It is a positive integer.

A resin coating film containing the specific modified polyvinyl alcohol (A) and an acrylamide-based polymer (B) is provided on the surface of the precoated fin material. The resin coating film is made of the precoated fin material by using the specific modified polyvinyl alcohol (A) and setting the mass ratio of the polyvinyl alcohol (A) to the acrylamide polymer (B) within the specific range. It is possible to increase the hydrophilicity of the surface and maintain excellent hydrophilicity for a long period of time.

Further, since the surface of the precoated fin material is not only excellent in hydrophilicity but also excellent in oil repellency, it is possible to suppress the adhesion of oily contaminants to the surface of the precoated fin material. Further, since the pre-coated fin material is excellent in both hydrophilicity and oil repellency, dew condensation water or the like easily enters between the surface of the pre-coated fin material and the contaminants adhering to the surface. Therefore, even when an oily contaminant adheres to the surface of the precoated fin material, the contaminant can be washed away with water such as dew condensation water and easily removed from the surface of the fin.

As described above, the pre-coated fin material can maintain excellent hydrophilicity for a long period of time, and oily contaminants adhering to the surface can be easily removed.

It is a partially enlarged sectional view which shows the main part of the test material 1 to the test material 3 in an Example. It is a partially enlarged sectional view which shows the main part of the test material 4 and the test material 5 in an Example.

In the precoated fin material, the aluminum constituting the substrate can be appropriately selected from pure aluminum and aluminum alloy according to desired mechanical properties, corrosion resistance and the like. The substrate may be composed of, for example, pure aluminum having a chemical component represented by an alloy number such as 1200 or 1050 in JIS H4000.

A resin coating film containing the modified polyvinyl alcohol (A) and the acrylamide-based polymer (B) is formed on the substrate. The resin coating film may be directly laminated on the substrate, or another film or coating film may be interposed between the substrate and the resin coating film.

For example, the pre-coated fin material may further have an undercoat film laminated on the substrate. Depending on the material of the undercoat film, for example, the adhesion between the substrate and the corrosion-resistant coating film can be improved, and the corrosion resistance of the substrate can be improved.

As the undercoat, for example, chromate treatment such as chromate treatment with phosphoric acid, chemical film treatment such as non-chromate treatment with titanium phosphate, zirconium phosphate, molybdenum phosphate, zinc phosphate, zirconium oxide, etc. other than chromium compounds, so-called chemical conversion. A film obtained by the treatment can be adopted.

The chemical conversion treatment method described above includes a reaction type and a coating type, and any method may be used. The amount of the undercoat adhered can be appropriately selected from the range of 100 mg / m ² or less as the metal content, for example. Further, the amount of adhesion of the base film can be measured by a fluorescent X-ray analyzer.

Further, the pre-coated fin material may further have a corrosion-resistant coating film interposed between the substrate and the resin coating film. The corrosion-resistant coating film may contain, for example, one or more resins selected from the group consisting of acrylic resin, epoxy resin, urethane resin and ester resin. The corrosion-resistant coating film containing these resins can further improve the corrosion resistance of the fins.

The film thickness of the corrosion-resistant coating film can be appropriately set from, for example, within the range of 0.3 μm or more and 5.0 μm or less. By setting the film thickness of the corrosion-resistant coating film within the above-mentioned specific range, it is possible to sufficiently obtain the effect of improving the corrosion resistance of the fins while avoiding the deterioration of the heat dissipation performance due to the corrosion-resistant coating film.

The resin coating film provided on the surface of the precoated fin material contains a modified polyvinyl alcohol (A) and an acrylamide polymer (B). The resin coating film may contain a modified polyvinyl alcohol (A) and an acrylamide-based polymer (B) and may have a hydrophilic layer interposed between the lubricating layer and the substrate. By forming such a hydrophilic layer in the resin coating film, the hydrophilicity and oil repellency of the surface of the precoated fin material can be enhanced, and these characteristics can be maintained for a long period of time.

The film thickness of the resin coating film can be appropriately set from, for example, in the range of 0.3 μm or more and 2.0 μm or less. By setting the film thickness of the resin coating film to 0.3 μm or more, the hydrophilicity of the surface of the precoated fin material can be enhanced, and contaminants adhering to the surface of the fin can be more easily removed from the surface of the fin. Further, by setting the film thickness of the resin coating film to 2.0 μm or less, it is possible to improve the coatability of the paint when forming the resin coating film.

The modified polyvinyl alcohol (A) in the resin coating film has a molecular structure in which some hydroxyl groups in polyvinyl alcohol are modified by an organic group having a hydroxyl group at the terminal. Specifically, the modified polyvinyl alcohol (A) has a molecular structure represented by the following general formula (1).

However, R ¹ in the general formula (1) is an organic group having a linear structure and having 5 or more and 10 or less carbon atoms, and m and n satisfy the relationship of 0.005 ≦ n / m ≦ 0.025. It is a positive integer.

The modified polyvinyl alcohol (A) modified with the specific organic group is less likely to crystallize than unmodified polyvinyl alcohol because a relatively bulky organic group is introduced into the side chain. Therefore, by blending the modified polyvinyl alcohol (A) in the resin coating film, the formation of hydrogen bonds can be suppressed, and the hydrophilicity and oil repellency of the surface of the precoated fin material can be maintained for a long period of time. ..

From the viewpoint of further enhancing the above-mentioned action and effect, R ¹ in the general formula (1) is preferably an organic group containing a plurality of methylene groups and one or more carbonyl groups, and is preferably a plurality of methylene groups and 2 More preferably, it is an organic group containing more than one carbonyl group.

When R ¹ in the general formula (1) is an organic group containing a carbonyl group, the position of the carbonyl group can take various embodiments. For example, the carbonyl group may form an ester bond (—O—CO—) with an oxygen atom attached to the main chain of polyvinyl alcohol. Further, the carbonyl group may be interposed between the methylene groups (-CH ₂ -CO-CH _2- ). Further, the carbonyl group may form a carboxyl group (—CO—OH) together with the hydroxyl group at the end of the side chain.

The content of polyvinyl alcohol (A) in the resin coating film is 0.5 times or more and 2.0 times or less of that of the acrylamide polymer (B) in terms of mass ratio. By setting the ratio of polyvinyl alcohol (A) to the acrylamide polymer (B) in the above-mentioned specific range, the hydrophilicity and oil repellency of the surface of the precoated fin material can be maintained for a long period of time. When the ratio of polyvinyl alcohol (A) to the acrylamide polymer (B) is out of the above specific range, the resin coating film deteriorates relatively early during the use of the heat exchanger, and is hydrophilic and oil repellent. May lead to a decrease in.

From the viewpoint of maintaining excellent hydrophilicity and oil repellency for a longer period of time, the content of polyvinyl alcohol (A) may be 0.7 times or more and 1.9 times or less that of the acrylamide polymer (B). It is preferably 1.0 times or more and 1.6 times or less, more preferably.

The acrylamide-based polymer (B) in the resin coating film includes, for example, a homopolymer having (meth) acrylamide or a derivative thereof as a monomer, such as polyacrylamide and polymethacrylicamide, and a group consisting of (meth) acrylamide and its derivatives. Copolymers containing two or more selected compounds as monomers, copolymers containing one or more compounds selected from the group consisting of (meth) acrylamide and derivatives thereof, and compounds other than these as monomers can be adopted. .. The resin coating film may contain one of these homopolymers and copolymers as the acrylamide-based polymer (B), or may contain two or more of them.

As the acrylamide-based polymer (B), it is preferable to use a homopolymer of a primary amide or a secondary amide, or a copolymer containing a primary amide or a secondary amide as a monomer. These homopolymers and copolymers contain highly polar primary or secondary amide groups. Therefore, by using these homopolymers and copolymers as the acrylamide-based polymer (B), the hydrophilicity of the resin coating film can be made higher, and contaminants can be removed more easily from the fin surface. From this point of view, it is particularly preferable to use polyacrylamide as the acrylamide-based polymer (B).

The acid value of the acrylamide polymer (B) is preferably 20 mgKOH / g or more and 100 mgKOH / g or less. By using the acrylamide-based polymer (B) having an acid value in the specific range, excellent hydrophilicity and oil repellency can be maintained for a longer period of time. As a result, contaminants adhering to the surface of the fins can be easily removed from the surface of the fins and the ability to remove contaminants can be maintained for a longer period of time.

From the viewpoint of maintaining the ability to remove contaminants for a longer period of time, it is more preferable that the acid value of the acrylamide polymer (B) is 40 mgKOH / g or more. On the other hand, from the viewpoint of further enhancing the ability to remove contaminants, it is more preferable that the acid value of the acrylamide polymer (B) is 90 mgKOH / g or less.

In addition to polyvinyl alcohol (A) and acrylamide-based polymer (B) as essential components, the resin coating film may contain optional components other than these. When the resin coating film contains an arbitrary component, the total content of the modified polyvinyl alcohol (A) and the acrylamide-based polymer (B) is, for example, 85 when the mass of the entire resin coating film is 100 parts by mass. It can be appropriately set from the range of parts by mass or more. In this case, the amounts of the polyvinyl alcohol (A) and the acrylamide-based polymer (B) in the resin coating film can be sufficiently increased. As a result, it is possible to obtain the effect of any component while ensuring excellent hydrophilicity and oil repellency.

Polyethylene glycol may be contained in the resin coating film as an optional component.

Polyethylene glycol can float on the hydrophilic layer in the process of forming the resin coating film to form a lubricating layer. The polyethylene glycol exposed on the surface of the resin coating film functions as a lubricant to reduce the friction between the pre-coated fin material and the press die when the pre-coated fin material is pressed, and improves the workability during press processing. Can be improved.

The content of polyethylene glycol in the resin coating film is preferably 1.5 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the resin coating film. By setting the content of polyethylene glycol to 1.5 parts by mass or more, the friction between the precoated fin material and the die during press working can be further reduced. From the viewpoint of further reducing the friction between the pre-coated fin material and the die during press working, the polyethylene glycol content is preferably 2.0 parts by mass or more, and more preferably 2.5 parts by mass or more. preferable.

Further, by setting the content of polyethylene glycol to 8 parts by mass or less, the surface roughness of the precoated fin material can be made smaller, and contaminants can be made less likely to adhere to the surface of the fin. From the viewpoint of smoothing the surface of the precoated fin material and more effectively suppressing the adhesion of contaminants to the surface of the fin, the content of polyethylene glycol is preferably 7 parts by mass or less, and 5 parts by mass or less. Is more preferable.

The number average molecular weight of polyethylene glycol is preferably in the range of 1000 to 20000. In this case, it is possible to improve the lubricity during press working and more effectively suppress the adhesion of contaminants to the fin surface.

The resin coating film may contain, as an optional component, a cross-linking agent for making the crystal structure of the modified polyvinyl alcohol (A) denser. By adding a cross-linking agent to the resin coating film, the hardness of the resin coating film can be further increased and the adhesion of dust can be suppressed more effectively. As the cross-linking agent, for example, a melamine resin, a blocked isocyanate compound, or the like can be used. These compounds may be used alone or in combination of two or more.

Further, the resin coating film may further contain at least one of an antibacterial agent and an antifungal agent as an optional component, or both may be added. Further, an antibacterial / antifungal agent having both an antibacterial action and an antifungal action can be added to the resin coating film. By adding a compound having at least one of an antibacterial effect and an antifungal effect to the resin coating film, corrosion of the resin coating film can be suppressed and the action and effect of the resin coating film can be maintained for a longer period of time. ..

Examples of compounds having antibacterial and antifungal effects include isothiazolin-based antibacterial / antifungal agents, aldehyde-based antibacterial / antifungal agents, benzimidazole-based antibacterial / antifungal agents, halogen-based antibacterial / antifungal agents, and carboxylic acids. Antibacterial / antifungal agents, sulfamide antibacterial / antifungal agents, thiazole antibacterial / antifungal agents, triazole antibacterial / antifungal agents, phenol antibacterial / antifungal agents, phthalimide antibacterial / antifungal agents, naphthenic acid Organic antibacterial and antifungal agents such as antibacterial and antifungal agents and pyridine antibacterial and antifungal agents, and inorganic antibacterial and antifungal agents such as Ag, Cu and Zn can be used.

As the antibacterial / antifungal agent, it is preferable to use at least one of zinc pyrithione, 2,3,5,6-tetrachloro-4- (methylsulfonyl) -pyridine and 2- (4-thiazolyl) benzimidazole. .. These compounds have little effect on the physical properties of the resin coating film, are insoluble in water, and have high heat stability. Therefore, by adding these compounds to the resin coating film, the antibacterial action and the antifungal action can be maintained for a long period of time.

The resin coating film may contain, as an optional component, fluororesin particles having a fluororesin having a perfluoroalkyl group and having a median diameter of 1 μm or more and 4 μm or less on a volume basis. At least a part of the fluororesin particles in the resin coating film is arranged on the surface of the hydrophilic layer described above, and functions as a lubricant during press working together with polyethylene glycol. By setting the median diameter of the fluororesin particles to the above-mentioned specific range, the lubricity during press working can be further reduced. From the viewpoint of more reliably achieving such an action and effect, the content of the fluororesin particles is preferably 2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the resin coating film.

The median diameter of the fluororesin particles on a volume basis is specifically a cumulative 50% diameter in the particle size distribution obtained by the laser diffraction / scattering method.

Examples of the fluororesin constituting the fluororesin particles include a completely fluororesin such as polytetrafluoroethylene (that is, PTFE), polyvinylidene fluoride (that is, PVDF), and partially fluorine such as polyvinyl fluoride (that is, PVF). Fluororesin copolymers such as chemical resins, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymers (that is, PFA), and ethylene-tetrafluoroethylene copolymers (that is, ETFE) can be used. The fluororesin particles may be composed of one kind of particles made of these fluororesins, or two or more kinds may be used in combination.

The fluororesin particles are preferably composed of a fluororesin having a perfluoroalkyl group. In this case, the lubricity at the time of press working can be improved.

As a method for producing the pre-coated fin material, for example, a method of applying a paint containing a modified polyvinyl alcohol (A) and an acrylamide-based polymer (B) on a substrate and then heating and drying the paint can be adopted. .. In the process of drying the paint, the modified polyvinyl alcohol (A) and the acrylamide polymer (B) settle on the substrate side to form a hydrophilic layer. At this time, since the modified polyvinyl alcohol (A) has low compatibility with the acrylamide polymer (B), the hydrophilic layer contains a phase containing the modified polyvinyl alcohol (A) and a phase containing the acrylamide polymer (B). And are formed in a state of being phase-separated from each other. Both of these phases are exposed on the surface of the hydrophilic layer.

The phase containing the modified polyvinyl alcohol (A) can exhibit excellent oil repellency derived from the modified polyvinyl alcohol (A). Further, in the phase containing the modified polyvinyl alcohol (A), the formation of hydrogen bonds between the hydroxyl groups contained in the modified polyvinyl alcohol (A) is suppressed due to the steric hindrance of the organic group introduced into the side chain. Therefore, a relatively large number of hydroxyl groups that do not form hydrogen bonds can be exposed on the surface of the phase containing the modified polyvinyl alcohol (A), and the hydrophilicity of the surface of the hydrophilic layer can be enhanced.

Further, in the phase containing the acrylamide-based polymer (B), excellent hydrophilicity derived from the acrylamide-based polymer (B) can be exhibited. Therefore, the hydrophilic layer containing the modified polyvinyl alcohol (A) and the acrylamide-based polymer (B) can achieve both excellent hydrophilicity and oil repellency.

The pre-coated fin material is used for manufacturing a heat exchanger, for example, as follows. First, fins are produced by cutting the precoated fin material to a desired size. Slit processing, louver molding, and color processing are appropriately combined and performed on the obtained fins using a press processing machine to form slits, louvers, and collars. After that, a plurality of fins are arranged at predetermined intervals from each other, and a metal tube for flowing the refrigerant is attached so as to penetrate the plurality of fins. After that, the expansion plug is inserted into the metal tube to expand the outer diameter of the metal tube, so that the metal tube and the fins are brought into close contact with each other. In this way, the heat exchanger can be obtained. The heat exchanger can be incorporated into, for example, an indoor unit or an outdoor unit of an air conditioner.

Examples of the pre-coated fin material will be described with reference to FIG. As shown in FIG. 1, the precoated fin material 1 of this example has a substrate 2 made of aluminum and a resin coating film 3 formed on the substrate 2 and exposed on the surface. The resin coating film 3 contains a modified polyvinyl alcohol (A) having a molecular structure represented by the general formula (1) and an acrylamide-based polymer (B). The content of the modified polyvinyl alcohol (A) is 0.5 times or more and 2.0 times or less the content of the acrylamide-based polymer (B) in terms of mass ratio. Hereinafter, a more specific example of the pre-coated fin material of this example will be described together with the manufacturing method thereof.

・ Test material 1 to test material 3
The test materials 1 to 3 shown in Table 1 can be produced by the following methods. First, the substrate 2 is prepared. As the substrate 2, a plate material made of aluminum may be used as it is, or a plate material on which a base film has been formed in advance by chemical conversion treatment may be used. Specifically, the substrate 2 used for the test material 1 to the test material 3 is made of aluminum having a chemical component represented by the alloy number 1050 in JIS H4000, and is represented by the quality code H26 in JIS H0001. It is a quality aluminum plate with a plate thickness of 0.1 mm. The substrate 2 is previously subjected to chemical conversion treatment using a phosphoric acid chromate solution, and a base film 21 made of phosphoric acid chromate is provided on both sides of the substrate 2.

Next, a coating material containing the modified polyvinyl alcohol (A) and the acrylamide-based polymer (B) in the mass ratios shown in Table 1 is prepared. In Table 1, "polyvinyl alcohol" is abbreviated as "PVA" and "acrylamide-based polymer" is abbreviated as "PAM".

The modified polyvinyl alcohol (A) used in the test materials 1 to 3 has a molecular structure represented by the following structural formula (2).

However, R ² in the structural formula (2) has 7 carbon atoms and is an organic group having a linear structure containing both a methylene group and a carbonyl group, and m and n are 0.005 ≦ n /. It is a positive integer satisfying the relationship of m ≦ 0.025.

The acid value of the acrylamide-based polymer (B) used in the test materials 1 to 3 is 50 mgKOH / g, and the polystyrene-equivalent weight average molecular weight is 300,000.

After applying the above-mentioned paint on the substrate 2 using a bar coater, the paint is heated at a temperature of 225 ° C. for 10 seconds to dry. As a result, the resin coating film 3 can be formed on the substrate 2 to obtain the test materials 1 to 3. The thickness of the resin coating film 3 is 1 μm.

As shown in FIG. 1, the resin coating film 3 of the test materials 1 to 3 is a hydrophilic layer including a phase 311 containing a modified polyvinyl alcohol (A) and a phase 312 containing an acrylamide polymer (B). Has 31.

・ Test material 4 and test material 5
The test material 4 and the test material 5 have the same configuration as the test material 1 to the test material 3 except that polyethylene glycol is contained in the resin coating film 3. The manufacturing method of the test material 4 and the test material 5 is the same as the manufacturing method of Examples 1 to 3 except that the amount of polyethylene glycol shown in Table 1 is added to the paint. The number average molecular weight of the polyethylene glycol used in the test material 4 and the test material 5 is 6000. Further, in Table 1, "polyethylene glycol" is abbreviated as "PEG".

When polyethylene glycol is contained in the paint as in the test material 4 and the test material 5, the modified polyvinyl alcohol (A) and the acrylamide-based polymer (B) in the paint are in the process of heating and drying the paint on the substrate. Settles to the substrate 2 side. As a result, as shown in FIG. 2, the base film 21 of the test material 4 and the test material 5 has a phase 311 containing the modified polyvinyl alcohol (A) and a phase 312 containing the acrylamide polymer (B). The hydrophilic layer 31 is formed.

On the other hand, since polyethylene glycol has a lower viscosity than the modified polyvinyl alcohol (A) and the acrylamide-based polymer (B), it floats to the surface side as the drying of the paint progresses. As a result, the lubricating layer 32 containing polyethylene glycol is formed on the hydrophilic layer 31. As described above, the resin film 302 of the test material 4 and the test material 5 has a lubricating layer 32 exposed on the surface and a hydrophilic layer 31 interposed between the lubricating layer 32 and the substrate 2.
-Test material 6 and test material 7
The test material 6 and the test material 7 have the same configurations as those of the test material 1 to the test material 3 except that the ratio of the modified polyvinyl alcohol (A) to the acrylamide-based polymer (B) is outside the above-mentioned specific range. There is.
・ Test material 8
The test material 8 has the same configuration as the test material 4 and the test material 5 except that the content of polyethylene glycol is higher than the above-mentioned specific range.

・ Test material 9
The test material 9 is produced by the same production method as that of the test materials 1 to 3 except that unmodified polyvinyl alcohol (number average molecular weight 6000) is used instead of the modified polyvinyl alcohol (A). ..

Various characteristics of the test material 1 to the test material 9 can be evaluated by the following methods.

-Hydrophilicity The hydrophilicity of the test material can be evaluated based on the contact angle of water. In this example, the contact angle of water in each test material immediately after production and the contact angle of water in the test material after the deterioration test are measured. The contact angles of water in each test material immediately after production are as shown in Table 1.

After measuring the contact angle of water immediately after production, a deterioration test is performed. In the deterioration test, after immersing the test material in ion-exchanged water for 2 minutes, air is blown to each test material for 6 minutes to dry the resin coating film 3, and this cycle is repeated for 300 cycles. Then, water is dropped on the test material after the deterioration test is completed, and the contact angle of the water is measured. The contact angle of water in the test material after the deterioration test is as shown in Table 1.

-Oil repellency The oil repellency of the test material can be evaluated based on the results of the cleaning test shown below. First, a square having a side of 15 mm is drawn on the resin coating film 3 of the test material using an oil-based dye marker, and the inside of the square is filled with the oil-based dye marker to adhere the ink layer on the resin coating film 3. As the oil-based dye marker, for example, "Twin Marker MFN-15FB-B" manufactured by Pilot Corporation can be used.

Next, the test material is erected vertically, and water is sprayed 150 times on the portion of the test material located above the ink layer using a mist. At this time, make sure that the water sprayed from the mist does not hit the square directly. After spraying is complete, the area of the ink layer removed by spraying is measured. Then, a value expressed as a percentage of the ratio of the area of the ink layer removed by spraying to the area of the ink layer before spraying is defined as the ink layer removal rate (unit:%).

The results of the above cleaning tests performed on the test material immediately after production and the test material after the deterioration test described above are shown in the "oil repellency" column of Table 1. In the "oil repellent" column of Table 1, the symbol "A" is used when the removal rate of the ink layer is higher than 80%, and the symbol "B" is used when the removal rate is more than 60% and 80% or less. When it is 60% or less, the symbol "C" is described, when it is more than 20% and 40% or less, the symbol "D" is described, and when it is 20% or less, the symbol "E" is described.

-Adhesion The adhesion between the substrate 2 and the resin coating film 3 can be evaluated by a method according to the cross-cut method specified in JIS K5600-5-6: 1999. Specifically, first, the resin coating film 3 is cut in a grid pattern using a cutter knife, and 100 square pieces having a side of 2 mm are formed on the resin coating film 3. Attach cellophane tape as an adhesive tape to these square pieces. Then, the cellophane tape is peeled off at an angle of 45 ° with respect to the substrate 2, and the number of square pieces remaining on the substrate 2 is counted. In the "adhesion" column of Table 1, "Good" is described when all the square pieces remain on the substrate 2, and "Good" is described when one or more square pieces are peeled off from the substrate 2. Bad ".

As shown in Table 1, the test materials 1 to 5 have a resin coating film having a composition in the specific range on the substrate. Therefore, these test materials have a water contact angle of 20 ° or less immediately after production, and exhibit excellent hydrophilicity immediately after production. Further, these test materials have a water contact angle of 30 ° or less after the deterioration test, and can maintain high hydrophilicity for a long period of time. Further, these test materials are also excellent in oil repellency immediately after production and oil repellency after deterioration test.

On the other hand, the mass ratio of the modified polyvinyl alcohol (A) to the acrylamide-based polymer (B) in the test material 6 is smaller than the above-mentioned specific range. Therefore, the hydrophilicity and oil repellency of the test material 6 after the deterioration test are lower than those of the test materials 1 to 5.

The mass ratio of the modified polyvinyl alcohol (A) to the acrylamide-based polymer (B) in the test material 7 is larger than the specific range as shown in Table 1. Therefore, the oil repellency of the test material 7 after the deterioration test is lower than that of the test materials 1 to 5.

The content of polyethylene glycol in the test material 8 is higher than the above-mentioned specific range. Therefore, the adhesion of the resin coating film 3 of the test material 8 and the oil repellency after the deterioration test are lower than those of the test materials 1 to 5.

Since the test material 9 contains unmodified polyvinyl alcohol instead of the modified polyvinyl alcohol (A), the structure of the hydrophilic layer of the test material 9 is different from that of the test materials 1 to 5. .. The hydrophilicity of the test material 9 after the deterioration test is lower than that of the test materials 1 to 5.

The specific embodiment of the precoated fin material according to the present invention is not limited to the embodiment described above, and can be appropriately changed as long as the gist of the present invention is not impaired. For example, in the above-mentioned Examples and Experimental Examples, an example of the pre-coated fin material 1 in which the undercoat film 21 is formed on the substrate 2 is shown, but the chemical conversion treatment for forming the undercoat film 21 is omitted and the substrate 2 is covered. It is also possible to directly form the resin coating film 3 on the surface. Further, the chemical conversion treatment for forming the undercoat film 21 may be omitted, and the corrosion-resistant coating film and the resin coating film 3 may be sequentially formed on the substrate 2.

1 Pre-coated fin material 2 Substrate 3 Resin coating film

Claims (7)

A board made of aluminum and
It has a resin coating film formed on the substrate and exposed on the surface thereof.
The resin coating film is
Modified polyvinyl alcohol (A) having a molecular structure represented by the following general formula (1) and
Containing with an acrylamide polymer (B),
The content of the modified polyvinyl alcohol (A) is 0.5 times or more and 2.0 times or less the content of the acrylamide-based polymer (B) in terms of mass ratio.
Pre-coated fin material.

(However, R ¹ in the general formula (1) is an organic group having a linear structure and having 5 or more and 10 or less carbon atoms, and m and n have a relationship of 0.005 ≦ n / m ≦ 0.025. It is a positive integer that satisfies.) The precoated fin material according to claim 1, wherein R ¹ in the general formula (1) is an organic group containing a plurality of methylene groups and one or more carbonyl groups. The precoated fin material according to claim 1 or 2, wherein polyethylene glycol is further contained in the resin coating film. The precoat according to any one of claims 1 to 3, wherein the resin coating film further contains one kind or two or more kinds of compounds selected from the group consisting of a blocked isocyanate compound and a melamine resin. Fin material. The precoated fin material according to any one of claims 1 to 4, wherein at least one of an antibacterial agent and an antifungal agent is further contained in the resin coating film. Any one of claims 1 to 5, wherein the resin coating film contains fluororesin particles made of a fluororesin having a perfluoroalkyl group and having a median diameter of 1 μm or more and 4 μm or less on a volume basis. The pre-coated fin material described in the section. It has a corrosion-resistant coating film interposed between the substrate and the resin coating film, and the corrosion-resistant coating film is one or two selected from the group consisting of acrylic resin, epoxy resin, urethane resin and ester resin. The precoated fin material according to any one of claims 1 to 6, which contains the above resin.

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