Aluminum fin material

Abstract

To provide an aluminum fin material having excellent icing frost suppression effect, and having excellent temporal stability of surface hydrophilicity.SOLUTION: An aluminum fin material includes an aluminum plate, and an icing frost suppression film layer and a hydrophilic film layer in this order on at least one surface of the aluminum plate. The icing frost suppression film layer contains an amphoteric (meth)acrylamide resin. The hydrophilic film layer contains hydrophilic inorganic particles.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an aluminum fin material, and particularly to an aluminum fin material suitably used for heat exchangers such as air conditioners.

Background Art

[0002] Heat exchangers are used in products in various fields such as room air conditioners, package air conditioners, refrigerated showcases, refrigerators, oil coolers, and radiators. As materials for the fins of heat exchangers, aluminum and aluminum alloys, which are excellent in thermal conductivity, workability, corrosion resistance, etc., are generally used. Plate fin type and plate and tube type heat exchangers have a structure in which fin materials are arranged in parallel at narrow intervals.

[0003] When the surface temperature of the fin material of a heat exchanger becomes below the dew point, condensed water adheres to the surface in a state. When the hydrophilicity of the surface of the fin material is low, the contact angle of the adhered condensed water becomes large, so scattering in the living environment called water splashing occurs. Further, when such condensed water combines and becomes large, it forms a bridge between adjacent fin materials, closes the ventilation path between the fin materials, and increases the ventilation resistance. For the purpose of preventing such water splashing and reducing the ventilation resistance, for example, Patent Document 1 proposes a technique of applying a hydrophilic surface treatment agent to the surface of the fin material to form a hydrophilic film.

[0004] On the other hand, when the air conditioner is operated for heating, etc., the surface temperature of the heat exchanger becomes below the freezing point, and the condensed water adhering to the surface of the fin material becomes frost or ice, resulting in an icing state. If the hydrophilicity of the fin material surface is increased too much, the above-mentioned icing is more likely to occur. When the fins are blocked due to icing, the heat exchange efficiency of the heat exchanger is significantly reduced, so defrosting operation or the like is required.

[0005] Therefore, various techniques for suppressing frost formation on fin materials have been studied. For example, in Patent Document 2, a fluorinated alkoxysilane having a critical surface tension of 20 dyn / cm or less is chemically adsorbed on the surface of the air-side heat transfer surface to form a water-repellent film having a structure in which CF3 groups are oriented on the outermost surface, thereby preventing frosting. Patent Document 3 discloses that, while forming a water-repellent film on the surface, the average surface roughness Ra is set to 20 μm or more to reduce the area of water droplets, snow, and ice that come into contact with the surface of the member and reduce the adhesion force thereof.

[0006] However, in the above, there are concerns about the deterioration of water repellency over time and the reduction in durability due to the decrease in the strength of the water-repellent film when the average surface roughness Ra is increased. Therefore, Patent Document 4 discloses a heat exchanger including a specific heat transfer section. This heat transfer section has a first layer and a second layer located on the air side relative to the first layer, and the second layer is composed of a polymer layer having a plurality of polymer chains. The roots of the main chains of the adjacent polymer chains on the first layer side have a metal oxide network structure and are bonded to each other. Thereby, the polymer chains of the second layer can be bonded to the first layer in a high density in the vertical direction, so that the hydrophilicity of the surface of the heat transfer section can be surely improved. Therefore, even when condensed water is generated on the surface of the heat transfer section, it is said that the growth of frost can be sufficiently delayed.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in Patent Document 4, no specific consideration regarding ice frost formation suppression of the heat exchanger has been made. Also, it cannot always be said that the suppression of ice frost formation improves as the hydrophilicity improves, and it is necessary to conduct a separate test regarding the suppression of ice frost formation.

[0009] In contrast, the present invention person has found that by providing an ice frost formation suppression film layer having an amphoteric polymer having both a cationic group having a positive charge and an anionic group having a negative charge, the ice frost formation on the aluminum fin material is effectively suppressed. However, through further investigation, it has been found that although the hydrophilicity on the surface of the aluminum fin material is good initially, it decreases over time. Due to the decrease in hydrophilicity, the generated condensed water forms a bridge between adjacent fin materials, and the heat exchange performance deteriorates. Also, when the above-mentioned condensed water remains on the surface, it causes freezing.

[0010] Therefore, an object of the present invention is to provide an aluminum fin material that has an excellent ice frost formation suppression effect and good temporal stability of surface hydrophilicity.

Means for Solving the Problems

[0011] The present invention relates to the following [1] to [7]. [1] An aluminum fin material comprising an ice frost formation suppression film layer and a hydrophilic film layer in this order on at least one surface of an aluminum plate, wherein the ice frost formation suppression film layer contains an amphoteric (meth)acrylamide-based resin, and the hydrophilic film layer contains hydrophilic inorganic particles. [2] The aluminum fin material according to [1], wherein the hydrophilic film layer further contains at least one of polyethylene glycol and a polyethylene glycol-modified product. [3] The aluminum fin material according to [1] or [2], wherein the amphoteric (meth)acrylamide-based resin is an amphoteric acrylamide-based resin. [4] The hydrophilic coating layer has a coating amount of 0.01 to 1.0 g / m 2 The aluminum fin material according to [1] or [2] above. [5] The aluminum fin material according to [1] or [2], wherein the hydrophilic inorganic particles are hydrophilic silica particles. [6] The aluminum fin material described in [1] or [2] above, further comprising a corrosion-resistant coating layer between the aluminum plate and the anti-frost coating layer. [7] The aluminum fin material described in [1] or [2] above, further comprising a base treatment layer between the aluminum plate and the anti-frost coating layer. [Effects of the Invention]

[0012] According to the present invention, ice nucleation can be suppressed by the interaction between the condensed water adhering to the fin material surface and the frost-suppressing coating layer. As a result, it is possible to provide an aluminum fin material in which the freezing of the condensed water is delayed and frost formation on the surface is suitably suppressed. In addition, the good hydrophilicity of the fin material surface can be maintained for a long period of time. Therefore, the formation of bridges due to the condensed water can be prevented, and a deterioration in heat exchange performance and freezing can be prevented. [Brief explanation of the drawings]

[0013]

Figure 1

Figure 2

[0014] Hereinafter, embodiments of the aluminum fin material and the anti-frost agent according to the present invention will be described in detail. Note that the symbol "to" indicating a numerical range is used to mean that the numerical values before and after it are included as the lower limit and upper limit.

[0015] <Aluminum fin material> The aluminum fin material 10 according to this embodiment (hereinafter, may be simply referred to as "fin material") includes, as shown in FIG. 1, an aluminum plate 1, an anti-icing and frost layer 2 and a hydrophilic film layer 3 formed on at least one surface of the aluminum plate 1 in this order. The anti-icing and frost layer 2 contains an amphoteric (meth)acrylamide-based resin, and the hydrophilic film layer 3 contains hydrophilic inorganic particles.

[0016] The aluminum fin material 10 may further include other layers. For example, a base treatment layer 4 and a corrosion-resistant film layer 5 may be mentioned. When all of these layers are provided, it is preferable to provide the base treatment layer 4 and the corrosion-resistant film layer 5 between the aluminum plate 1 and the anti-icing and frost layer 2. In this case, as shown in FIG. 2, it is preferable to provide the layers in the order of the base treatment layer 4, the corrosion-resistant film layer 5, the anti-icing and frost layer 2, and the hydrophilic film layer 3 in this order from the aluminum plate 1 side. However, the outermost layer is preferably the hydrophilic film layer 3. Also, within a range that does not impair the effects of the present invention, other layers having other functions may be further provided.

[0017] In FIGS. 1 and 2, the hydrophilic film layer 3 is directly provided on the surface of the anti-icing and frost layer 2, but other layers may be further provided between these layers. In order to achieve both the anti-icing and frost suppression effect by the partially exposed anti-icing and frost layer 2 and the high hydrophilicity persistence obtained by covering most of the upper layer, it is preferable that the hydrophilic film layer 3 is directly provided on the anti-icing and frost layer 2.

[0018] In FIGS. 1 and 2, the hydrophilic film layer 3 is located on the outermost surface of the aluminum fin material 10, but other layers may be further provided on the surface of the hydrophilic film layer 3. In order to exhibit high hydrophilicity in the initial state, it is preferable that the hydrophilic film layer 3 is located on the outermost surface.

[0019] Note that it is sufficient if at least one surface of the aluminum plate 1 has the above configuration, and both surfaces of the aluminum plate 1 may have the above configuration. Also, when both surfaces of the aluminum plate 1 have the above configuration, the two surfaces do not need to be in the same mode.

[0020] (Anti-frosting film layer) The anti-frosting film layer 2 contains an amphoteric (meth)acrylamide resin. The amphoteric (meth)acrylamide resin means at least one of an amphoteric methacrylamide resin and an amphoteric acrylamide resin. By amphoteric, it is composed of a cationic group in which the amino group of (meth)acrylamide has a positive charge and an anionic group in which an anionic group is introduced into the amino group to have a negative charge. By using an amphoteric (meth)acrylamide resin having an anionic group and a cationic group in one molecule, it is preferable from the viewpoint of solution stability without precipitation compared to a mixture of an anionic compound and a cationic compound.

[0021] By providing the anti-frosting film layer, the water adhering to the surface of the fin material is suppressed in ice nucleation due to the interaction with the anti-frosting film layer, and the freezing of the water is delayed. As a result, the generation of frost can be suppressed.

[0022] The anti-frosting film layer can be formed, for example, by applying a paint composition containing an amphoteric (meth)acrylamide resin onto an aluminum plate, an undercoat layer, or a corrosion-resistant film layer and solidifying it by drying or the like.

[0023] The amphoteric (meth)acrylamide resin contained in the anti-frosting film layer is an amphoteric polymer having a cationic group and an anionic group in the molecule. Only one kind or two or more kinds of the amphoteric (meth)acrylamide resin may be used.

[0024] The polar group part in the cationic group of the amphoteric (meth)acrylamide resin is represented by -NR3 + and examples of the structure include a primary amino group, a secondary amino group, a tertiary amino group, or a quaternary ammonium salt. Here, R includes a hydrogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms, a salt, etc.

[0025] Examples of the polar group moiety in the anionic group of the amphoteric (meth)acrylamide-based resin include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, unsaturated tricarboxylic acids, unsaturated tetracarboxylic acids, unsaturated sulfonic acids, unsaturated phosphonic acids, and their salts.

[0026] From the viewpoint of enhancing hydrophilicity, it is preferable that the anti-icing and frosting film layer further contains a crosslinking agent in addition to the amphoteric (meth)acrylamide-based resin. Conventionally known crosslinking agents can be used. Examples include crosslinking agents containing an oxazoline group, an oxiranyl group (1,2-epoxy structure), an oxetanyl group (1,3-epoxy structure), an isocyanate group, a blocked isocyanate group, etc. Among them, an oxazoline group and an oxiranyl group are more preferable. When sufficient hydrophilicity can be obtained by containing a crosslinking agent, the anti-icing and frosting film layer can also serve as a hydrophilic film layer without separately providing a hydrophilic film layer on the fin material.

[0027] From the viewpoint of enhancing hydrophilicity, it is also preferable that the anti-icing and frosting film layer further contains a surfactant in addition to the amphoteric (meth)acrylamide-based resin. By containing a surfactant, the processability by the hydrophilic film layer and the hydrophilicity can be more preferably compatible. This is considered to be due to the surface-exposing action of the surfactant.

[0028] Any of anionic, cationic, nonionic surfactants can be applied, and amphoteric surfactants can also be applied.

[0029] Examples of the anionic surfactant include alkyl sulfate esters such as sodium lauryl sulfate, ethanolamine lauryl sulfate, ammonium lauryl sulfate; sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene alkyl ether sulfuric acidPolyoxyethylene alkyl ether sulfate salts such as sodium; alkylbenzene sulfonates, sodium dodecylbenzene sulfonate, alkylnaphthalene sulfonates, sodium dialkyl sulfosuccinate, sodium alkyl diphenyl ether disulfonate, sodium alkane sulfonate and other alkylbenzene sulfonates and other sulfonates; reactive surfactants such as polyoxyalkylene alkenyl ether ammonium sulfate; fatty acid salts such as sodium stearate soap, potassium oleate soap; other anionic surfactants such as potassium polyoxyethylene alkyl ether phosphate, dipotassium alkenyl succinate, etc.

[0030] Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether; polyoxyalkylene derivatives such as polyoxyethylene alkylene alkyl ethers, reactive surfactants such as polyoxyalkylene alkenyl ethers; sorbitan fatty acid esters such as sorbitan monolaurate; polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene sorbitol fatty acid esters such as polyoxyethylene sorbitol tetraoleate; glycerin fatty acid esters such as glycerol monostearate, polyoxyethylene alkylamine, alkyl alka n-ol amides and the like.

[0031] Examples of cationic surfactants include alkylamine salts such as stearylamine acetate; quaternary ammonium salts such as lauryl trimethyl ammonium chloride.

[0032] Examples of amphoteric surfactants include carboxybetaines, aminocarboxylic acids, sulfobetaines, amino sulfate esters, imi da zolines and the like.

[0033] The content of the amphoteric (meth)acrylamide resin in the anti-frosting film layer is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more in terms of the solid content composition ratio. Further, the upper limit of the above content is not particularly limited, and it may be 100% by mass in terms of the solid content composition ratio, that is, it may consist only of the amphoteric (meth)acrylamide resin.

[0034] When the anti-frosting film layer has a cross-linking agent, the content of the cross-linking agent with respect to 100 parts by mass of the amphoteric (meth)acrylamide resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less in terms of the solid content composition ratio.

[0035] When the anti-frosting film layer has a surfactant, the content of the surfactant with respect to 100 parts by mass of the amphoteric (meth)acrylamide resin is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less in terms of the solid content composition ratio.

[0036] The film thickness of the anti-frosting film layer is preferably 0.01 g / m 2 or more, and more preferably 0.1 g / m 2 or more. Further, although the upper limit is not particularly limited, the film thickness of the anti-frosting film layer is preferably 5 g / m 2 or less, and more preferably 3 g / m 2 or less from the viewpoint of obtaining a sufficient anti-frosting effect.

[0037] The anti-frosting film layer may contain other optional components as long as the effects of the present invention are not impaired. Examples of other optional components include various paint additives for improving the physical properties of the film layer and the like. Further, in the process of forming the anti-frosting film layer, an aqueous solvent, a water-soluble organic solvent, or the like may be used from the viewpoints of paintability, workability, and the like. Examples of the paint additives include a surface conditioner, a wetting dispersant, an anti-settling agent, an antioxidant, an antifoaming agent, a rust preventive agent, an antibacterial agent, a fungicide, and the like. These paint additives may be contained singly or in combination of two or more.

[0038] The thickness of the anti-frosting film layer is not particularly limited. However, assuming the density of the anti-frosting film layer is 1 g / cm 3 From the viewpoint of obtaining good anti-frosting performance, the thickness is preferably 0.01 μm or more, more preferably 0.1 μm or more, and even more preferably 0.3 μm or more. The upper limit is not particularly limited, but is preferably 5 μm or less, and more preferably 3 μm or less. The thickness of the anti-frosting film layer can be adjusted by, for example, the concentration of the coating composition used for forming the anti-frosting film layer, the selection of the bar coater No., etc.

[0039] (Hydrophilic film layer) The hydrophilic film layer contains hydrophilic inorganic particles. Hydrophilic inorganic particles mean inorganic particles whose surface has not been hydrophobized or inorganic particles whose surface has been hydrophilized. Hydrophilic inorganic particles are superior in dispersibility in an aqueous medium compared to hydrophobic inorganic particles.

[0040] When a hydrophilic film layer composed only of hydrophilic inorganic particles is formed so that the film amount is 0.05 g / m 2 or more, the initial contact angle of water is preferably 25° or less. When the hydrophilic film layer contains polyethylene glycol or the like described later, the polyethylene glycol or the like may be washed away with water, and the initial contact angle of water may be measured for the hydrophilic film layer composed only of hydrophilic inorganic particles. Note that the above film amount is not an essential film amount for obtaining the effect of the hydrophilic film layer, but is a film amount that can be used as a reference when determining whether inorganic particles are hydrophilic or not.

[0041] The hydrophilic film layer can be formed, for example, by applying a coating composition containing hydrophilic inorganic particles onto the anti-frosting film layer or the corrosion-resistant film layer and solidifying it by drying or the like.

[0042] Examples of the inorganic material that becomes hydrophilic inorganic particles include silica (SiO2), titanium oxide (TiO2), alumina (Al2O3), etc. Also, an inorganic material containing two or more of these may be used, and examples thereof include zeolite (aluminosilicate), etc. The hydrophilic inorganic particles may be used singly or in combination of two or more.

[0043] The shape of the hydrophilic inorganic particles is not particularly limited, and is not particularly limited such as spherical, flat plate-like, flat-like, needle-like, disk-like, etc. Also, a pearl necklace-like shape in which spherical particles are bonded may be used.

[0044] The size of the hydrophilic inorganic particles is not particularly limited either, but the median diameter (D50) of the primary particles determined by the dynamic light scattering method is preferably 1 μm or less, more preferably 300 nm or less, from the viewpoint of dispersibility. Also, the lower limit of the median diameter (D50) is not particularly limited, but is, for example, 1 nm or more.

[0045] From the viewpoint of high hydrophilicity over time stability, the content of the hydrophilic inorganic particles in the hydrophilic film layer is preferably 50% by mass or more, more preferably 55% by mass or more, and still more preferably 60% by mass or more in terms of the solid content composition ratio. Also, the upper limit is not particularly limited, and it may be a hydrophilic film layer consisting only of hydrophilic inorganic particles, i.e., 100% by mass. When the hydrophilic film layer contains components other than the hydrophilic inorganic particles, the above content of the hydrophilic inorganic particles is preferably 95% by mass or less, for example.

[0046] The hydrophilic film layer may contain a resin that enhances lubricity in addition to the hydrophilic inorganic particles. Thereby, the friction coefficient of the fin material surface is reduced to be lubricious, and the press formability etc. when processing the fin material into fins is improved.

[0047] Examples of the resin that enhances lubricity include, for example, a resin having a hydrophilic group. Examples of the hydrophilic group include a hydroxyl group, a carboxyl group, a sulfonic acid group, a polyether group, etc.

[0048] Examples of the resin having a hydroxyl group include polyethylene glycol (PEG) and polyvinyl alcohol (PVA). Examples of those having a carboxyl group include polyacrylic acid (PAA). Examples of those having a hydroxyl group and a carboxyl group include carboxymethyl cellulose (CMC). Examples of those having a sulfonic acid group include sulfoethyl acrylate. Examples of those having a polyether group include polyethylene glycol (PEG) and its modified compounds. In addition to these, copolymers of two or more hydrophilic group-containing monomers can also be applied.

[0049] Among the above, for example, it is preferable to further contain at least one of polyethylene glycol (PEG) and a polyethylene glycol modified body (PEG modified body). The PEG modified body refers to, for example, those having a urethane bond in the molecule, those containing a glycidyl ether group in the molecule, methyl ether in which one or both of the -OH groups at the ends of the molecule are substituted with -CH3 groups, those having an amine in the molecule, and the like.

[0050] From the viewpoint of good lubricity, the total content of PEG and the PEG modified body in the hydrophilic film layer is preferably 5% by mass or more, more preferably 8% by mass or more, and still more preferably 10% by mass or more in terms of the solid content ratio. Also, from the viewpoint of favorably exerting the effect of the hydrophilic inorganic particles, the total content is preferably 50% by mass or less, more preferably 40% by mass or less.

[0051] A water-soluble thickener may be used in the hydrophilic film layer together with the resin that enhances lubricity. The water-soluble thickener contributes to the immobilization of the resin that enhances lubricity. The water-soluble thickener is not particularly limited, and conventionally known ones can be used. For example, carboxymethyl cellulose (CMC) can be mentioned.

[0052] In the hydrophilic film layer, the total content of the water-soluble thickener is preferably 0.5% by mass or more, preferably 1% by mass or more, and preferably 5% by mass or less in terms of the solid content ratio.

[0053] The hydrophilic film layer may contain hydrophilic inorganic particles, a resin such as PEG or a PEG derivative for enhancing lubricity optionally, a water-soluble thickener, and other optional components as long as the effects of the present invention are not impaired. Examples of the other optional components include various paint additives for improving the physical properties of the film layer. Examples of the paint additives include crosslinking agents, surfactants, surface modifiers, wetting dispersants, anti-settling agents, antioxidants, defoamers, antifouling agents, rust preventives, antibacterial agents, antifungal agents, etc. These paint additives may be contained singly or in combination of two or more. In the process of forming the hydrophilic film layer, an aqueous solvent, a water-soluble organic solvent, etc. may be used from the viewpoints of paintability, workability, etc.

[0054] From the viewpoint of obtaining sufficient temporal stability of hydrophilicity, the film amount of the hydrophilic film layer is preferably 0.01 g / m 2 or more, more preferably 0.03 g / m 2 or more, and even more preferably 0.05 g / m 2 or more. The upper limit of the film amount of the hydrophilic film layer is not particularly limited, but is preferably 5 g / m 2 or less, more preferably 3 g / m 2 or less, and even more preferably 1 g / m 2 or less.

[0055] The thickness of the hydrophilic film layer is not particularly limited. Assuming the density of the hydrophilic film layer is 1 g / cm 3 , from the viewpoint of obtaining good temporal stability of hydrophilicity, the thickness is preferably 0.01 μm or more, more preferably 0.1 μm or more, and even more preferably 0.3 μm or more. The upper limit is not particularly limited, but is preferably 5 μm or less, and more preferably 3 μm or less. The thickness of the hydrophilic film layer can be adjusted by the concentration of the paint composition used for forming the hydrophilic film layer, the selection of the bar coater No., etc.

[0056] (Aluminum plate) The aluminum plate is a concept including a plate made of aluminum and a plate made of an aluminum alloy, and an aluminum plate conventionally used for aluminum fin materials can be used. As the aluminum plate, aluminum of the 1000 series defined in JIS H 4000:2014 is preferred because of its excellent thermal conductivity and workability. More specifically, aluminum of alloy numbers 1050, 1070, and 1200 is more preferred as the aluminum plate. However, the above description does not exclude the use of aluminum alloys of the 2000 series to 9000 series or other aluminum plates as the aluminum plate at all.

[0057] The aluminum plate shall have a thickness as desired according to the use and specifications of the fin material, etc. For the fin material for heat exchangers, from the viewpoint of fin strength and the like, the thickness is preferably 0.08 mm or more, and more preferably 0.1 mm or more. On the other hand, from the viewpoints of workability to fins and heat exchange efficiency, etc., the thickness is preferably 0.3 mm or less, and more preferably 0.2 mm or less.

[0058] (Corrosion-resistant coating layer) The corrosion-resistant coating layer is not essential, but is a layer formed on the aluminum plate as desired to enhance the corrosion resistance of the aluminum plate, and preferably contains a hydrophobic resin. When a base treatment layer is formed on the surface of the aluminum plate, the corrosion-resistant coating layer is preferably formed on the base treatment layer. Also, when an anti-icing and frosting coating layer is formed on the aluminum plate or on the base treatment layer, the corrosion-resistant coating layer may be formed thereon.

[0059] The corrosion-resistant coating layer can be formed, for example, by applying a paint composition containing a hydrophobic resin on the aluminum plate, on the base treatment layer, or on the anti-icing and frosting coating layer and solidifying it by drying or the like.

[0060] The corrosion-resistant coating layer makes it difficult for moisture such as condensed water, oxygen, ion species such as chloride ions, etc. to penetrate into the aluminum plate, and suppresses the corrosion of the aluminum plate and the generation of aluminum oxides that generate odors.

[0061] As the hydrophobic resin in the corrosion-resistant film layer, conventionally known ones can be used. For example, various resins such as polyester-based, polyolefin-based, melamine-based, epoxy-based, urethane-based, and acrylic-based resins can be mentioned, and a mixture of one or more of these can be applied.

[0062] In addition to the above, the corrosion-resistant film layer may contain other optional components within a range that does not impair the effects of the present invention. Examples of the optional components include various paint additives for improving the physical properties of the film and the like. Examples of the paint additives include water-soluble organic solvents, crosslinking agents, surfactants, surface modifiers, wetting dispersants, anti-settling agents, antioxidants, defoamers, rust preventives, antibacterial agents, antifungal agents, and the like. These paint additives may be included singly or in combination of two or more. Also, in the process of forming the corrosion-resistant film layer, from the viewpoints of paintability, workability, etc., an aqueous solvent, a water-soluble organic solvent, or the like may be used.

[0063] The film amount of the hydrophobic resin in the corrosion-resistant film layer is not particularly limited, but from the viewpoint of imparting sufficient corrosion resistance to the aluminum plate, 0.05 g / m 2 or more is preferable, and 0.2 g / m 2 or more is more preferable. On the other hand, from the viewpoint of suppressing the decrease in the heat exchange efficiency of the fin, the adhesion amount of the hydrophobic resin is preferably 15 g / m 2 or less, and more preferably 3 g / m 2 or less.

[0064] The thickness of the corrosion-resistant film layer is preferably 0.05 μm or more from the viewpoint of obtaining good corrosion resistance. Also, from the viewpoints that the film-forming property is good, defects such as cracks are reduced, the heat transfer resistance of the corrosion-resistant film layer is kept low, and good heat exchange efficiency of the fin is obtained, 15 μm or less is preferable. Note that the thickness of the corrosion-resistant film layer and the adhesion amount of the hydrophobic resin can be adjusted by, for example, the concentration of the paint composition used for forming the corrosion-resistant film layer and the selection of the bar coater No.

[0065] (Substrate treatment layer) The undercoat layer is not essential, but is a layer formed on the aluminum plate if desired. The undercoat layer can enhance the corrosion resistance of the aluminum plate. Also, when the fin material is provided with a corrosion-resistant coating layer, the adhesion between the aluminum plate and the corrosion-resistant coating layer can be enhanced by providing an undercoat layer therebetween.

[0066] The undercoat layer only needs to be able to impart corrosion resistance to the aluminum plate, and conventionally known ones can be used. For example, a layer composed of an inorganic oxide or an inorganic-organic composite compound can be used. As the inorganic materials constituting the inorganic oxides and inorganic-organic composite compounds, chromium (Cr), zirconium (Zr), and titanium (Ti) are preferably used as the main components.

[0067] The layer made of an inorganic oxide serving as the undercoat layer can be formed, for example, by performing chromate phosphate treatment, zirconium phosphate treatment, zirconium oxide treatment, chromate chromate treatment, zinc phosphate treatment, titanate phosphate treatment, etc. on the aluminum plate. However, the types of inorganic oxides are not limited to those formed by these treatments.

[0068] The layer made of an inorganic-organic composite compound serving as the undercoat layer can be formed, for example, by performing a coating-type chromate treatment or a coating-type zirconium treatment on the aluminum plate. Specific examples of such inorganic-organic composite compounds include, for example, an acrylic-zirconium composite.

[0069] The film thickness etc. of the undercoat layer are not particularly limited and can be set as appropriate. However, it is preferably formed such that the deposition amount per unit area is 1 to 100 mg / m in terms of metals such as Cr, Zr, Ti, etc. 2 and the film thickness is preferably 1 to 100 nm. The deposition amount and film thickness of the undercoat layer can be adjusted by adjusting the concentration of the chemical conversion treatment liquid used for forming the undercoat layer and the film formation treatment time.

[0070] Before forming the undercoat layer, the surface of the aluminum plate may be pre-degreased using an alkaline degreasing solution. This improves the reactivity of the undercoat treatment and further enhances the adhesion of the formed undercoat layer.

[0071] (Properties of Aluminum Finned Material) Even when condensed water adheres to the surface of the aluminum finned material according to this embodiment, ice nucleation can be suppressed by the interaction between the condensed water and the anti-icing and frosting film layer. As a result, the freezing of the condensed water is delayed, and icing and frosting on the surface of the finned material can be preferably suppressed. In addition, since good hydrophilicity can be realized not only initially but also with time stability, the formation of bridges by condensed water can be prevented, and a decrease in heat exchange performance and freezing can be prevented.

[0072] The anti-icing and frosting effect of the finned material can be evaluated by the following method. A copper plate equipped with a refrigerant flow path, a Peltier element, and an air flow path is disposed inside the upper part of an acrylic cylinder, and this device is disposed in an environment with a temperature of 10°C and a relative humidity of 55%. A finned material is disposed at a position on the copper plate where it is in contact with the air inside the cylinder. Then, air is blown into the cylinder at a wind speed of 1.5 m / s. After the above steps, while continuing to blow air into the cylinder at the same wind speed, the copper plate is cooled to a surface temperature of -7.5°C to intentionally cause condensed water to adhere to the surface of the finned material. A digital microscope is installed on the side where the condensed water of the finned material adheres, and the state of the condensed water and frost on the surface of the finned material is observed. The time from the start of cooling until frost begins to form is measured as the "anti-icing and frosting delay time" to evaluate the anti-icing and frosting effect. The anti-icing and frosting delay time by the above method is preferably more than 20 minutes, and more preferably more than 30 minutes.

[0073] Hydrophilicity is also an important parameter when using the finned material in a heat exchanger. Therefore, the hydrophilicity can be evaluated by the initial contact angle when pure water is dropped onto the surface of the finned material. Specifically, at room temperature, about 2 μL of pure water is dropped onto the surface of the finned material, and the contact angle of the liquid droplet (pure water) is measured as the initial contact angle using a contact angle measuring device. The initial contact angle of the droplet (pure water) is preferably 30° or less, more preferably 25° or less, still more preferably 20° or less, and particularly preferably 10° or less. The lower limit is not particularly limited, but is usually 2° or more.

[0074] As the stability over time of the hydrophilicity of the fin material, it can be evaluated by the contact angle when pure water is dropped onto the surface of the fin material after undergoing a wet-dry cycle. Specifically, for the wet-dry cycle, processing oil is applied to the surface of the fin material and heated at 200°C for 10 minutes, then returned to room temperature. Next, (i) the fin material is exposed to ion-exchanged water with a flow rate of 0.1 mL / min for 8 hours, and (ii) then dried at 80°C for 16 hours. One cycle consists of such steps, and such steps are performed 14 times. Then, after returning to room temperature, about 2 μL of pure water is dropped onto the surface of the fin material, and the contact angle of the droplet (pure water) is measured as the contact angle over time using a contact angle measuring device.

[0075] The contact angle over time of the droplet (pure water) is preferably 30° or less, more preferably 25° or less, still more preferably 20° or less, and particularly preferably 10° or less. The lower limit is not particularly limited, but is usually 2° or more.

[0076] Drainage of the fin material is also important. Drainage can be evaluated by dropping a water droplet (pure water) onto the surface of the fin material and measuring the angle (sliding angle) formed between the fin material and the horizontal plane when the above water droplet begins to fall when one end of the fin material is lifted and inclined. Similar to the contact angle, it can be evaluated by the initial sliding angle and the sliding angle over time after undergoing a wet-dry cycle. However, for both the initial sliding angle and the sliding angle over time, it is preferable to slide regardless of the angle, and the sliding angle is more preferably 50° or less, still more preferably 30° or less, even more preferably 20° or less, and particularly preferably 10° or less.

[0077] As an index of the workability of the fin material, the coefficient of friction is cited. If the coefficient of friction is high, it causes wear of the mold when pressing the aluminum fin material with a mold during the manufacture of the heat exchanger. Regarding the fin material, using a Boudouard tester, the average value of the values obtained by performing 3 reciprocating slides while changing the position under a load of 200 g is defined as the coefficient of friction. The coefficient of friction is preferably 0.25 or less, more preferably 0.2 or less, still more preferably 0.15 or less, and particularly preferably 0.1 or less. The above coefficient of friction can be decreased, for example, by adding a component that enhances lubricity such as PEG or a PEG-modified product to the hydrophilic film layer.

[0078] <Manufacturing method of aluminum fin material> An example of the manufacturing method of the aluminum fin material according to the present embodiment will be described, but it is not limited to such a mode, and it can also be manufactured by other manufacturing methods as long as the effects of the present embodiment are not impaired. Further, the following example is an explanation of the case where a base treatment layer, a corrosion-resistant film layer, an anti-icing and frosting film layer, and a hydrophilic film layer are formed in this order on the surface of an aluminum plate, but the formation of the base treatment layer and the corrosion-resistant film layer is optional. Also, the order of each layer can be changed as appropriate.

[0079] A base treatment layer is formed on the surface of the aluminum plate by a known method. A corrosion-resistant film layer is formed on the surface thereof by a known method.

[0080] Next, a paint composition containing an amphoteric (meth)acrylamide-based resin is applied, dried, and baked on the corrosion-resistant film layer to form an anti-icing and frosting film layer. The baking temperature is not particularly limited as long as the corrosion-resistant film layer does not peel off. For example, 100°C or higher is preferable, and 200°C or higher is more preferable. Also, from the viewpoint of preventing oxidation of the resin of the corrosion-resistant film layer, the baking temperature is preferably 400°C or lower, and more preferably 300°C or lower. Note that the above baking temperature is the temperature of the furnace for baking.

[0081] The baking time is not particularly limited as long as the corrosion-resistant coating layer does not peel off. For example, 3 seconds or more is preferable, and 10 seconds or more is more preferable. Also, from the viewpoint of preventing oxidation of the resin of the corrosion-resistant coating layer, the baking time is preferably 2 hours or less, and more preferably 1 hour or less.

[0082] The coating composition containing the amphoteric (meth)acrylamide-based resin may contain other components such as a surfactant. By containing a surfactant, the surface tension can be arbitrarily adjusted, and the coatability can be improved.

[0083] The solvent of the coating composition containing the amphoteric (meth)acrylamide-based resin is not particularly limited, and examples thereof include water, alcohol, aliphatic ketones, etc. Among them, water and alcohol are preferable, and as the alcohol, butanol, ethanol, etc. are preferable. One kind of solvent may be used, or two or more kinds may be mixed and used. For example, when using a mixed solvent of water and alcohol, from the viewpoint of coatability on the substrate, the alcohol is preferably 1 to 20 parts by mass with respect to 100 parts by mass of water.

[0084] The solid content concentration in the coating composition containing the amphoteric (meth)acrylamide-based resin is preferably 1% by mass or more, and more preferably 3% by mass or more, from the viewpoint of coating stability. Also, the solid content concentration is preferably 40% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of coatability on the substrate.

[0085] The film thickness when the coating composition containing the amphoteric (meth)acrylamide-based resin is applied is preferably 1 μm or more, and more preferably 5 μm or more, from the viewpoint of coatability. Also, the film thickness is preferably 40 μm or less, and more preferably 20 μm or less, from the viewpoint of the volatility of the solvent. Here, the film thickness is the film thickness before drying, and can be adjusted, for example, by selecting the bar coater No. when applying the coating composition using a bar coater.

[0086] Next, a coating composition containing hydrophilic inorganic particles is applied, dried, and baked on the surface of the anti-icing frost film layer to form a hydrophilic film layer. The baking temperature is not particularly limited as long as the anti-icing frost film layer does not peel off. For example, 100°C or higher is preferable, and 200°C or higher is more preferable. Also, from the viewpoint of preventing oxidation of the anti-icing frost film layer, the baking temperature is preferably 400°C or lower, and more preferably 300°C or lower. Note that the above baking temperature is the temperature of the furnace for baking.

[0087] The baking time is not particularly limited as long as the anti-icing frost film layer does not peel off. For example, 3 seconds or longer is preferable, and 10 seconds or longer is more preferable. Also, from the viewpoint of preventing oxidation of the resin of the anti-icing frost film layer, the baking time is preferably 2 hours or shorter, and more preferably 1 hour or shorter.

[0088] The application of the corrosion-resistant film layer, the anti-icing frost film layer, and the hydrophilic film layer is performed by a bar coater, a roll coating method, or the like. In particular, if the aluminum plate is in a coil shape, it is preferably to apply a roll coating device or the like to continuously perform degreasing, painting, heating, winding, etc. from the viewpoint of productivity. Also, the baking temperatures of the corrosion-resistant film layer, the anti-icing frost film layer, and the hydrophilic film layer may be set according to the components such as the resin used, and for example, it is preferably in the range of 120 to 270°C.

Examples

[0089] Hereinafter, the present invention will be described more specifically by giving examples and comparative examples. However, the present invention is not limited to these examples, and it is also possible to make modifications within the range that can conform to the gist thereof and implement them, and all of them are included in the technical scope of the present invention.

[0090] (Example 1) As the aluminum plate, the standard of alloy number 1070 defined in JIS H 4000:2014 with a thickness of 0.1 mm was used. A base treatment layer was formed on one surface of the aluminum plate by chromate phosphate treatment. Next, a coating composition in which an amphoteric polyacrylamide resin was dissolved in water was prepared. The solid content concentration of the amphoteric polyacrylamide resin in this coating composition was 5% by mass, and the compound solid content weight ratio of the amphoteric polyacrylamide resin, that is, the ratio of the amphoteric polyacrylamide resin in the solid content, was 100% by mass. The above coating composition was applied onto the surface of the base treatment layer using a bar coater. Then it was dried and baked at 225 °C to form an anti-frosting film layer. The film thickness of the anti-frosting film layer was 0.2 - 0.3 g / m 2 was obtained. Next, a coating composition in which hydrophilic silica particles were dispersed in water was prepared. The solid content concentration of the hydrophilic silica particles in this coating composition was 2% by mass, and the compound solid content weight ratio of the hydrophilic silica particles, that is, the ratio of the hydrophilic silica particles in the solid content, was 100% by mass. The above coating composition was applied onto the surface of the formed anti-frosting film layer using a bar coater. Then it was dried and baked at 225 °C to form a hydrophilic film layer, and an aluminum fin material was obtained. The film thickness of the hydrophilic film layer was 0.08 g / m 2 was obtained.

[0091] (Example 2) As the aluminum plate, the standard of alloy number 1070 defined in JIS H 4000:2014 with a thickness of 0.1 mm was used. A base treatment layer was formed on one surface of the aluminum plate by phosphoric acid chromate treatment. Next, a corrosion-resistant film layer 1 containing ammonium polyacrylate was formed on the surface of the base treatment layer. Next, an anti-frosting film layer and a hydrophilic film layer were formed on the surface of the corrosion-resistant film layer 1 in the same manner as in Example 1 to obtain an aluminum fin material. However, the solid content concentration of the hydrophilic silica particles in the coating composition for forming the hydrophilic film layer was 1% by mass, and the film thickness of the hydrophilic film layer was 0.04 g / m 2 was set.

[0092] (Examples 3 - 5) The solid content concentration of the hydrophilic silica particles in the paint composition for forming the hydrophilic film layer was changed to the concentration described in Table 1, and an aluminum fin material was obtained in the same manner as in Example 2, except that the film thickness of the hydrophilic film layer was the same as that described in Table 1.

[0093] (Examples 6 to 15) Up to the formation of the anti-icing frost film layer, the procedure was the same as in Example 2. Next, a paint composition was prepared by dispersing hydrophilic silica particles, polyethylene glycol (PEG), and carboxymethyl cellulose (CMC) in water so that the weight ratio of the compound solids was as described in Table 1. The solid content concentration in this paint composition is as shown in Table 1. The above paint composition was applied onto the surface of the formed anti-icing frost film layer using a bar coater. Then it was dried and baked at 160 °C to form a hydrophilic film layer, and an aluminum fin material was obtained. The film thickness of the hydrophilic film layer is as shown in Table 1.

[0094] (Example 16) An aluminum fin material was obtained in the same manner as in Example 7, except that the corrosion-resistant film layer 1 was changed to a corrosion-resistant film layer 2 containing sodium silicate.

[0095] (Example 17) The corrosion-resistant film layer 2 was changed to a corrosion-resistant film layer 3 containing an epoxy resin, and an aluminum fin material was obtained in the same manner as in Example 16, except that the paint composition for forming the anti-icing frost film layer was adjusted so that the weight ratio of the amphoteric polyacrylamide resin and sodium dialkylsulfosuccinate as a surfactant was 100 / 0.3 in terms of solid content.

[0096] (Comparative Example 1) An aluminum fin material was obtained in the same manner as in Example 1, except that a hydrophilic film layer was not formed.

[0097] (Comparative Example 2) A paint composition for forming an anti-icing frost film layer was prepared by dissolving and dispersing an amphoteric polyacrylamide resin and hydrophilic silica particles in water so that the solid content weight ratio was 80 / 20. An aluminum fin material was obtained in the same manner as in Example 1, except that a hydrophilic film layer was not formed.

[0098] The structures of the corrosion-resistant film layer, anti-icing frost film layer, and hydrophilic film layer of the aluminum fin material obtained above are summarized in Table 1. In Table 1, "-" means that the film layer is not formed.

[0099]

Table 1

[0100] (Evaluation: Anti-icing frost inhibition) A copper plate equipped with a refrigerant flow path, a Peltier element, and an air flow path was disposed inside the upper part of an acrylic cylinder. This device was disposed in an environment with a temperature of 10 °C and a relative humidity of 55%. A fin material was disposed at a position on the copper plate that was in contact with the air inside the cylinder. Then, air was blown into the cylinder at a wind speed of 1.5 m / s. After the above process, while continuing to blow air into the cylinder at the same wind speed, the copper plate was cooled to a surface temperature of -7.5 °C, and dew water was intentionally adhered to the surface of the fin material. A digital microscope was installed on the side where the dew water of the fin material adhered, and the state of the dew water and frost on the surface of the fin material was observed. The time from the start of cooling until frost began to form was measured as the "anti-icing frost delay time", and the anti-icing frost inhibition effect was evaluated. The evaluation criteria are as follows, and the results are shown in "Anti-icing frost inhibition" in Table 1. In the table, "-" means unmeasured. ◎ Very good (qualified): The anti-icing frost delay time exceeds 30 minutes ○ Good (qualified): The anti-icing frost delay time exceeds 20 minutes and is 30 minutes or less △ Poor (unqualified): The anti-icing frost delay time is 20 minutes or less

[0101] (Evaluation: Hydrophilicity) At room temperature, approximately 2 μL of pure water was dropped onto the surface of the aluminum fin material, and the contact angle of the liquid droplet (pure water) was measured using a contact angle measuring instrument (CA-05 type, manufactured by Kyowa Interface Science Co., Ltd.). The results are shown in "Hydrophilicity, Contact Angle, Initial" in Table 1. If it is 30° or less, it is considered good and can be said to pass. If it is 25° or less, it is very good, and if it is 20° or less, it is extremely good.

[0102] Also, for the evaluation of the temporal stability of hydrophilicity, processing oil was applied to the surface of the fin material, heated at 200 °C for 10 minutes, and then returned to room temperature. Next, a process of (i) exposing the fin material to ion-exchanged water with a flow rate of 0.1 mL / min for 8 hours and (ii) then drying it at 80 °C for 16 hours was defined as one cycle, and such a process was performed 14 cycles. After that, it was returned to room temperature, approximately 2 μL of pure water was dropped onto the surface of the fin material, and the contact angle of the liquid droplet (pure water) was measured as the contact angle over time using a contact angle measuring instrument. The results are shown in "Hydrophilicity, Contact Angle, Over Time" in Table 1. If it is 30° or less, it is considered good and can be said to pass. If it is 25° or less, it is very good, and if it is 20° or less, it is extremely good. In addition, in "Hydrophilicity, Evaluation" of Table 1, those with a contact angle of 10° or less in "Hydrophilicity, Contact Angle, Over Time" are particularly good and indicated by "◎", those with a contact angle greater than 10° and 30° or less are indicated by "○", and those that do not pass with a contact angle greater than 30° are indicated by "△".

[0103] (Evaluation: Water Sliding Property) At room temperature, water droplets (pure water) were dropped onto the surface of the fin material, and when one end of the fin material was lifted and inclined, the angle formed between the fin material and the horizontal plane when the above water droplets began to fall was measured as the sliding angle. The results are shown in "Water Sliding Property, Sliding Angle, Initial" in Table 1. It can be said to pass if it slides regardless of the angle, and the smaller the sliding angle, the more preferable.

[0104] Also, for the evaluation of the temporal stability of water sliding property, the same process as when measuring the contact angle over time in the above (Evaluation: Hydrophilicity) was performed 14 cycles. After that, it was returned to room temperature, pure water was dropped onto the surface of the fin material, and the sliding of the liquid droplet (pure water) was measured as the contact angle over time. The results are shown in "Water slipperiness, sliding angle, over time" in Table 1. Those with a sliding angle exceeding 10° are indicated by "○" as qualified, and those with a sliding angle of 10° or less are indicated by "◎". Also, not only over time, but those that did not slide on the initial dictionary are indicated by "×" as unqualified, and "-" means unmeasured.

[0105] (Evaluation: Processability) For the fin material, using a Boudin tester, while changing the position with a load of 200 g, 3 reciprocating slides were performed to obtain the friction coefficient, and the average value was taken as the friction coefficient of the fin material. The results are shown in "Processability, friction coefficient" in Table 1. If the friction coefficient is more than 0.1 and 0.25 or less, it is considered good and indicated by "○" as qualified. If it is 0.1 or less, it is considered particularly good and indicated by "◎". Also, for those with a friction coefficient of more than 0.25 are indicated by "△" as unqualified, and "-" means unmeasured.

[0106] From the above results, by using the aluminum fin material according to this embodiment provided with an anti-icing frost suppression film layer containing an amphoteric (meth)acrylamide-based resin and a hydrophilic film layer containing hydrophilic inorganic particles, while effectively suppressing the formation of icing frost, good temporal stability of the hydrophilicity of the surface was also achieved. In addition, for the aluminum fin material according to this embodiment, by adding a component that enhances lubricity such as PEG to the hydrophilic film layer, the friction coefficient can be reduced without impairing good anti-icing frost suppression properties and hydrophilicity. As a result, wear of the mold used for pressing the fin material during the manufacture of the heat exchanger can be prevented.

Explanation of Signs

[0107] 1 Aluminum plate 2 Anti-icing frost suppression film layer 3 Hydrophilic film layer 4 Substrate treatment layer 5 Corrosion-resistant film layer 10 Aluminum fin material

Claims

1. An aluminum fin material comprising an anti-icing frost film layer and a hydrophilic film layer in this order on at least one surface of an aluminum plate and the aluminum plate, wherein the anti-icing frost film layer contains an amphoteric (meth)acrylamide-based resin, and the hydrophilic film layer contains hydrophilic inorganic particles.

2. The aluminum fin material according to claim 1, wherein the hydrophilic film layer further contains at least one of polyethylene glycol and a polyethylene glycol modified product.

3. The aluminum fin material according to claim 1 or 2, wherein the amphoteric (meth)acrylamide-based resin is an amphoteric acrylamide-based resin.

4. The hydrophilic film layer has a film amount of 0.01 to 1.0 g / m ２ The aluminum fin material according to claim 1 or 2, which is such.

5. The aluminum fin material according to claim 1 or 2, wherein the hydrophilic inorganic particles are hydrophilic silica particles.

6. The aluminum fin material according to claim 1 or 2, further comprising a corrosion-resistant film layer between the aluminum plate and the anti-icing frost film layer.

7. The aluminum fin material according to claim 1 or 2, further comprising a primer layer between the aluminum plate and the anti-icing frost film layer.

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