Aluminum fin material

Abstract

Provided is an aluminum fin material having an ice and frost inhibiting film layer that is excellent in ice and frost inhibiting effect. An aluminum fin material having an aluminum plate (1) and a film layer (2) formed on the surface of the aluminum plate (1), the film layer (2) having an ice and frost inhibiting film layer (2a) containing an amphoteric polyacrylamide-based resin and polyethylene glycol.

Description

Aluminum fin material Technical Field

[0001] This invention relates to aluminum fin materials, and more particularly to aluminum fin materials suitable for heat exchangers such as air conditioners. Background Technology

[0002] Heat exchangers are used in various fields such as indoor air conditioning, modular air conditioning, refrigerated display cases, refrigerators, oil coolers, and radiators. The fins of heat exchangers are typically made of aluminum or aluminum alloys, which offer excellent thermal conductivity, processability, and corrosion resistance. Plate-fin and plate-tube heat exchangers feature a structure where the fins are arranged in parallel with narrow intervals.

[0003] When the surface temperature of a heat exchanger fin is below the dew point, condensation will form. If the surface of the fin has low hydrophilicity, the contact angle of the condensation will increase, causing water to splash into the environment. Furthermore, if this condensation accumulates and becomes large, it will form bridges between adjacent fins, blocking the ventilation path and increasing ventilation resistance.

[0004] For the purpose of preventing water splashing and reducing ventilation resistance, for example, patent document 1 proposes a technique of coating the surface of the fin material to form a hydrophilic film.

[0005] On the other hand, when the air conditioner is operating in heating mode, the surface temperature of the heat exchanger is below freezing. Condensation adhering to the fin surface forms frost or ice, resulting in a frosting or icing condition. If the hydrophilicity is too high, this frosting or icing is more likely to occur. If the fins become blocked due to frosting or icing, the heat exchanger's heat exchange efficiency is significantly reduced, thus requiring defrosting operations.

[0006] Therefore, various technologies for suppressing icing and frost formation on finned materials have been studied. For example, Patent Document 2 discloses a method in which a fluoroalkoxysilane with a critical surface tension of less than 20 dyn / cm is chemically adsorbed onto the surface of the air-side heat transfer surface, forming a film with a CF3-oriented structure on the outermost surface, thereby providing high water repellency and making frost formation difficult. Furthermore, Patent Document 3 discloses a method of forming a water-repellent film on the surface and making the average surface roughness Ra of the surface greater than 20 μm, thereby reducing the area of ​​water droplets (snow, ice) and decreasing their adhesion.

[0007] However, under the above conditions, the water repellency deteriorates over time, or when the average surface roughness Ra is increased, the reduced strength of the water-repellent film may lead to a decrease in durability.

[0008] Therefore, Patent Document 4 discloses a heat exchanger that serves as a heat transfer section, having a first layer and a second layer located on the air side relative to the first layer. The second layer is composed of a polymer layer having multiple polymer chains, with the roots of the main chains of adjacent polymer chains on the first layer side having a network structure of metal oxides and being bonded to each other. Accordingly, the polymer chains of the second layer can be bonded at a high density in the direction perpendicular to the first layer, thus it is believed that the hydrophilicity of the surface of the heat transfer section can be reliably improved, and even when condensation occurs on the surface of the heat transfer section, the growth of frost can be sufficiently delayed.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent No. 2520308

[0012] Patent Document 2: Japanese Patent Application Publication No. 10-281690

[0013] Patent Document 3: Japanese Patent Application Publication No. 9-228073

[0014] Patent Document 4: Japanese Patent Application Publication No. 2019-158247 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] However, no specific research was conducted on suppressing icing and frost formation in the heat exchanger of Patent Document 4. Furthermore, increased hydrophilicity does not necessarily improve the suppression of icing and frost formation; further experiments are needed to investigate this issue.

[0017] In response, the inventors conducted intensive research on the anti-icing and anti-frost coating layer and discovered that the anti-icing and anti-frost effect was excellent when using an amphoteric polyacrylamide resin. Further research indicated that, from an industrial perspective, it is difficult to simultaneously achieve both the lubricity and anti-icing and anti-frost properties, which are considered important for the processability of fins.

[0018] Therefore, the purpose of this invention is to provide an aluminum fin material that has excellent anti-icing and anti-frost properties, and also has excellent lubricity, forming an anti-icing and anti-frost film layer.

[0019] Problem-solving methods

[0020] This invention relates to the following [1] to [3].

[0021] [1] An aluminum fin material having an aluminum plate and a film layer formed on the surface of the aluminum plate, the film layer having an ice-freezing and frost-inhibiting film layer containing an amphoteric polyacrylamide resin and polyethylene glycol.

[0022] [2] According to the aluminum fin material described in [1], a substrate treatment layer is further provided between the aluminum plate and the film layer.

[0023] [3] According to the aluminum fin material described in [1] or [2], wherein the film layer is formed on both surfaces of the aluminum plate.

[0024] Invention Effects

[0025] According to the present invention, by utilizing the interaction between condensation and frost-freezing inhibition film layers adhering to the surface of the fin material, ice nucleation can be suppressed. As a result, the freezing of condensation is delayed, and surface frost-freezing is appropriately suppressed. This frost-freezing inhibition and good lubricity allow their effects to coexist without hindering each other. Therefore, it is possible to provide aluminum fin materials that are also conducive to industrialization and can suppress frost-freezing. Attached Figure Description

[0026] Figure 1 is a schematic cross-sectional view showing one method of aluminum fin structure.

[0027] Figure 2 is a schematic cross-sectional view showing one method of aluminum fin structure.

[0028] Symbol Explanation

[0029] 1 Aluminum plate

[0030] 2. Skin layer

[0031] 2a. Freezing and frosting inhibit the skin film layer.

[0032] 2b Corrosion-resistant coating layer

[0033] 2c Hydrophilic membrane layer

[0034] 10 Aluminum fin material Detailed Implementation

[0035] The following describes in detail the method of using aluminum fins for implementing the present invention. Also, the term "~" indicating a numerical range is used to mean a lower limit and an upper limit, including the values ​​before and after it.

[0036] <Aluminum Fin Material>

[0037] The aluminum fin material 10 of this embodiment (hereinafter, it may be simply referred to as "fin material"), as shown in FIG1, has an aluminum plate 1 and a film layer 2 formed on the surface of the aluminum plate 1. In addition, the film layer 2 has an ice-freezing and frost-inhibiting film layer 2a containing an amphoteric polyacrylamide resin and polyethylene glycol.

[0038] The coating layer 2 may also include at least one of a corrosion-resistant coating layer and a hydrophilic coating layer. The position of the frost-inhibiting coating layer 2a is not particularly limited, but from the viewpoint of better reflecting the obtained frost-inhibiting and lubricating properties, it is preferable that the frost-inhibiting coating layer 2a is the outermost layer, as shown in FIG2. More preferably, it is provided in the order of corrosion-resistant coating layer 2b, hydrophilic coating layer 2c, and frost-inhibiting coating layer 2a, starting from the aluminum plate 1 side.

[0039] Additionally, the lubricating film layer is not shown in Figure 2 because the icing and frosting inhibition film layer can also achieve good lubrication, thus eliminating the need for a separate lubricating film layer.

[0040] Furthermore, the freezing and frost-inhibiting film layer 2a can also possess the effects of the hydrophilic film layer 2c. Details will be described later, but for example, by adjusting the content of polyethylene glycol in the freezing and frost-inhibiting film layer 2a, or by further adding other ingredients, a more suitable hydrophilic effect can be obtained, thus creating a freezing and frost-inhibiting film layer that combines the functions of a hydrophilic film layer and the freezing and frost-inhibiting function.

[0041] A substrate treatment layer may also be provided between the aluminum plate 1 and the film layer 2.

[0042] Alternatively, the aforementioned film layer can be formed on at least one surface of the aluminum plate 1, but in practice, it is preferable to form the aforementioned film layer on both surfaces of the aluminum plate 1. Furthermore, when forming the aforementioned film layer on both surfaces of the aluminum plate 1, these film layers can be formed in the same manner or in different manners.

[0043] (Ice and frost inhibit the skin film layer)

[0044] The frost-inhibiting film layer 2a contains amphoteric polyacrylamide resin and polyethylene glycol. Amphoteric polyacrylamide resin is an amphoteric polymer with both cationic and anionic groups. Only one type of amphoteric polyacrylamide resin can be used, or two or more types can be used.

[0045] Amphoteric polyacrylamide resins are composed of positively charged cationic groups and negatively charged anionic groups in their molecules.

[0046] The polar group portion of the cationic group in amphoteric polyacrylamide resins is -NR3. + The expression indicates that structures of primary amino, secondary amino, tertiary amino, or quaternary ammonium salts can be listed. Additionally, R can include hydrogen atoms, straight-chain or branched alkyl groups having 1 to 5 carbon atoms, salts, etc.

[0047] The polar part of the anionic group of amphoteric polyacrylamide resins can be listed as unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, unsaturated tricarboxylic acids, unsaturated tetracarboxylic acids, unsaturated sulfonic acids, unsaturated phosphonic acids, and their salts.

[0048] There are no particular limitations on the preparation method of amphoteric polyacrylamide resins; conventionally known methods can be used. For example, they can be obtained by polymerization of acrylamide with cationic monomers having cationic groups and anionic monomers having anionic groups. Additionally, other monomers can be added as needed.

[0049] These polymerization reactions can be initiated, for example, by adding an initiator, or by adding a chain transfer agent as needed. Furthermore, commercially available resins can be used for amphoteric polyacrylamide resins.

[0050] The freezing and frost-inhibiting film layer, in addition to amphoteric polyacrylamide resins, also contains polyethylene glycol (PEG), thus contributing to good lubricity during processing. Furthermore, the polyethylene glycol in this specification also includes modified polyethylene glycol as a modifying compound. Modified polyethylene glycol, for example, is a polyethylene glycol with one or more functional groups in its structure, obtained by introducing urethane bonds or by terminal group substitution with glycidyl ethers, etc. Among polyethylene glycols, those without functional groups are preferred from the perspective of improving hydrophilicity.

[0051] Polyethylene glycol can be used in one or more forms.

[0052] The frost-inhibiting film layer, due to the presence of polyethylene glycol, also exhibits improved hydrophilicity. Specifically, considering good frost-inhibiting properties, lubricity, and hydrophilicity, the content of polyethylene glycol relative to 100 parts by weight of the amphoteric polyacrylamide resin is preferably 1 part by weight or more, more preferably 5 parts by weight or more, and even more preferably 10 parts by weight or more. Furthermore, the upper limit of the polyethylene glycol content is preferably 100 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 25 parts by weight or less.

[0053] When the freezing and frost-inhibiting film layer has sufficient hydrophilicity, it can also serve as a hydrophilic film layer. Therefore, it is not necessarily necessary to set up a separate hydrophilic film layer.

[0054] The freezing and frost-inhibiting film layer may also contain any other components without compromising the effectiveness of the invention. Examples of such other components include cross-linking agents. Further inclusion of a cross-linking agent can further enhance hydrophilicity.

[0055] The crosslinking agent can be any known crosslinking agent, such as those containing oxazoline group, ethylene oxide 20 group (1,2-epoxy structure) , oxetanyl group (1,3-epoxy structure) , isocyanate group , or blocked isocyanate group . Crosslinking agents containing oxazoline group or ethylene oxide group are more preferred.

[0056] The freezing and frost-inhibiting film layer, along with other optional components, such as surfactants, is also preferred from the viewpoint of further improving hydrophilicity. By including surfactants, a better balance between processability and hydrophilicity can be achieved. This is believed to be due to the performance effect of surfactants.

[0057] Surfactants can be anionic, cationic, or nonionic, but from the perspective of their ease of dispersion in the film layer during freezing and frost formation, nonionic surfactants are preferred.

[0058] Examples of anionic surfactants include, for example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl sulfosuccinates, and polyoxyethylene-polyoxypropylene block copolymers.

[0059] Examples of nonionic surfactants include ethylenediamine polyoxypropylene-polyoxyethylene condensates, polyoxyethylene sorbitan monolaurates, polyoxyethylene polyoxypropylene block polymers, and polyoxyethylene sorbitan monostearates.

[0060] The freezing and frost-inhibiting film layer, along with other arbitrary components, such as inorganic materials, is also preferred from the perspective of further improving hydrophilicity. Inorganic materials include silicon-containing compounds and titanium-containing compounds, such as colloidal silica, sodium silicate, silicon oligomers, silane coupling agents, alkoxy titanium, titanium oxide, etc.

[0061] The frost-inhibiting coating layer is formed by coating an aluminum plate or layer containing an amphoteric polyacrylamide resin and polyethylene glycol coating, followed by drying, baking, and curing.

[0062] The content of amphoteric polyacrylamide resin in the frost-inhibiting film layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the solid component composition ratio. Furthermore, the content of amphoteric polyacrylamide resin is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0063] The content of polyethylene glycol in the frost-free film layer is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the solid component composition ratio. Furthermore, the content of polyethylene glycol is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0064] When the frost-inhibiting film layer contains a crosslinking agent, the content of the crosslinking agent relative to 100 parts by weight of the amphoteric polyacrylamide resin, based on the solid component composition ratio, is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and preferably 20 parts by weight or less, more preferably 10 parts by weight or less.

[0065] When the frost-inhibiting film layer contains a surfactant, the content of the surfactant relative to 100 parts by weight of the amphoteric polyacrylamide resin, based on the solid component composition ratio, is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, and preferably 2 parts by weight or less, more preferably 1.5 parts by weight or less.

[0066] When the frost-inhibiting film layer contains inorganic materials, the content of the inorganic materials relative to 100 parts by weight of the amphoteric polyacrylamide resin, based on the solid component composition ratio, is preferably 1 part by weight or more, more preferably 5 parts by weight or more, and preferably 35 parts by weight or less, more preferably 30 parts by weight or less.

[0067] From the viewpoint of achieving sufficient anti-icing and anti-frost effects and good lubrication, the preferred amount of frost-free film is 0.1 mg / dm³. 2 The above, more preferably 0.5 mg / dm 2 The above is further preferred to be 1 mg / dm 2 That's all. Additionally, there is no specific upper limit, but the amount of film inhibited by freezing and frost is preferably 50 mg / dm³. 2 The following is more preferably 30 mg / dm 2 the following.

[0068] The freezing and frost-inhibiting film layer may contain any other ingredients without compromising the effectiveness of the invention. Examples of such other ingredients include various aqueous solvents and paint additives used to improve coatability, workability, and the physical properties of the film layer.

[0069] Examples of coating additives include, for example, water-soluble organic solvents, surface modifiers, wetting and dispersing agents, anti-settling agents, antioxidants, defoamers, rust inhibitors, antibacterial agents, and mildew inhibitors. These coating additives may be one or more.

[0070] There is no specific limit to the thickness of the frost-inhibiting film layer, but it can be assumed that the density of the frost-inhibiting film layer is 1 g / cm³. 3 From the viewpoint of obtaining good frost suppression and lubrication properties, the thickness is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more. Furthermore, there is no particular upper limit, but the thickness of the frost suppression film layer is preferably 5 μm or less, more preferably 3 μm or less.

[0071] The thickness of the coating layer can be inhibited by freezing and frosting. The concentration of the coating components used to inhibit the formation of the coating layer and the selection of the doctor blade coater No. can be adjusted.

[0072] (Aluminum sheet)

[0073] Aluminum sheet is a concept that includes sheets made of aluminum and sheets made of aluminum alloys, and aluminum sheets that can use aluminum fins have traditionally been used.

[0074] For aluminum sheets, considering excellent thermal conductivity and processability, 1000 series aluminum as specified in JIS H 4000:2014 is preferred. More specifically, aluminum alloys with alloy numbers 1050, 1070, and 1200 are more preferred. However, the above description does not exclude the use of 2000 to 9000 series aluminum alloys and other aluminum sheets.

[0075] The aluminum plate is made to the required thickness depending on the application and specifications of the fin material. Regarding fin materials used in heat exchangers, considering factors such as fin strength, a thickness of 0.08 mm or more is preferred, and 0.1 mm or more is more preferable. On the other hand, considering factors such as processability in fin manufacturing and heat exchange efficiency, a thickness of 0.3 mm or less is preferred, and 0.2 mm or less is more preferable.

[0076] (Corrosion-resistant coating layer)

[0077] A corrosion-resistant coating layer, mainly to improve the corrosion resistance of aluminum plates, can also be formed on aluminum plates, preferably containing hydrophobic resin.

[0078] When a substrate treatment layer is formed on the surface of an aluminum plate, a corrosion-resistant film layer is formed on top of the substrate treatment layer. Furthermore, if an anti-icing and anti-frost film layer is preferred as the outermost layer, then a corrosion-resistant film layer is preferably formed on top of the aluminum plate or the substrate treatment layer.

[0079] A corrosion-resistant coating layer, for example, can be formed by applying a coating composition containing a hydrophobic resin onto an aluminum plate or layer, followed by drying, baking, etc.

[0080] Under the action of the corrosion-resistant film layer, moisture such as condensation, oxygen, and ions such as chloride ions are difficult to penetrate into the aluminum plate, which can inhibit the corrosion of the aluminum plate and the formation of aluminum oxides that produce odors.

[0081] The hydrophobic resin in the corrosion-resistant coating layer can be any known material. For example, various resins such as polyester, polyolefin, melamine, epoxy, urethane, and acrylic resins can be used, and one or more of these resins can be mixed.

[0082] In addition to the above-mentioned components, the corrosion-resistant coating layer may also contain any other components without impairing the effects of the present invention. Examples of such components include various aqueous solvents and coating additives used to improve coatability, workability, and the physical properties of the coating.

[0083] Examples of coating additives include, for example, water-soluble organic solvents, crosslinking agents, surfactants, surface modifiers, wetting and dispersing agents, anti-settling agents, antioxidants, defoamers, rust inhibitors, antibacterial agents, and mildew inhibitors. These coating additives may be one or more.

[0084] There is no particular limitation on the amount of corrosion-resistant coating, but from the viewpoint of imparting sufficient corrosion resistance to the aluminum plate, 0.5 mg / dm³ is preferred. 2 The above, more preferably 2 mg / dm 2 That's all. On the other hand, from the viewpoint of suppressing the decrease in heat exchange efficiency of the fins, the preferred coating amount of the corrosion-resistant coating layer is 150 mg / dm³. 2 The following is more preferably 50 mg / dm 2 the following.

[0085] From the viewpoint of achieving good corrosion resistance, the thickness of the corrosion-resistant film layer is preferably 0.05 μm or more. Furthermore, from the viewpoint of achieving good film formation, reducing defects such as cracks, and suppressing the thermal resistance of the corrosion-resistant film layer to obtain good fin heat exchange efficiency, it is preferably 15 μm or less.

[0086] Furthermore, the thickness and amount of the corrosion-resistant coating can be adjusted by factors such as the concentration of the coating components used to form the corrosion-resistant coating and the selection of the doctor blade coater No.

[0087] (Hydrophilic membrane layer)

[0088] The hydrophilic coating layer is a coating layer that imparts hydrophilicity to the surface of the finned material and contains a known hydrophilic resin.

[0089] Hydrophilic resins only need to have hydrophilic groups; they can contain one type of resin or two or more types. Examples of hydrophilic groups include hydroxyl (hydroxyl), carboxyl, sulfonic acid, and polyether groups. However, if the freezing and frost-inhibiting film layer has sufficient hydrophilicity and also functions as a hydrophilic film layer, then a hydrophilic film layer may not be necessary. Furthermore, even if the freezing and frost-inhibiting film layer has sufficient hydrophilicity, a hydrophilic film layer may be provided to further improve hydrophilicity or the durability of hydrophilicity.

[0090] Examples of resins containing hydroxyl groups include polyethylene glycol (PEG) and polyvinyl alcohol (PVA). Examples of resins containing carboxyl groups include polyacrylic acid (PAA). Examples of resins containing both hydroxyl and carboxyl groups include carboxymethyl cellulose (CMC). Examples of resins containing sulfonic acid groups include ethyl sulfonate. Examples of resins containing polyether groups include polyethylene glycol (PEG) and its modified compounds.

[0091] From the perspective that even if the hydrophilic film layer forms an ice-freezing and frost-inhibiting film layer on its surface, the desired hydrophilicity can still be better reflected, the hydrophilic resin is preferably a resin containing sulfonic acid groups, a resin containing polyether groups (i.e., a resin containing ether bonds), more preferably a resin containing both sulfonic acid groups and ether bonds, and particularly preferably an acrylic resin containing both sulfonic acid groups and ether bonds.

[0092] Acrylic resins containing sulfonic acid groups and ether bonds are acrylic resins containing unsaturated double bonds and sulfonic acid groups. Examples include polyvinyl ether-sulfonic acid-acrylic copolymer and benzyl ether-sulfonic acid-acrylic copolymer. However, acrylic resins containing sulfonic acid groups and ether bonds are not limited to these examples.

[0093] In addition to the above, hydrophilic resins can also be copolymers of two or more monomers having hydrophilic groups. Examples include copolymers of acrylic acid and ethyl acrylate. The arrangement of monomers in the copolymer is not particularly limited; it can be an alternating copolymer, block copolymer, graft copolymer, random copolymer, etc.

[0094] In addition to the hydrophilic resin, the hydrophilic film layer preferably also contains a surfactant. Therefore, even if an anti-freezing / frost-reducing film layer forms on the hydrophilic film layer, the effects from these film layers and improved hydrophilicity can coexist. This is considered to be the effect of the surfactant.

[0095] Surfactants can be anionic, cationic, or nonionic, but from the viewpoint of easy dispersion in hydrophilic film layers, nonionic surfactants are preferred. Examples of nonionic surfactants include ethylenediaminepolyoxypropylene-polyoxyethylene condensates, polyoxyethylene sorbitan monolaurates, polyoxyethylenepolyoxypropylene block polymers, and polyoxyethylene sorbitan monostearates.

[0096] The hydrophilic film layer can be formed by applying a coating composition containing a hydrophilic resin onto an aluminum plate, a substrate treatment layer, or a corrosion-resistant film layer, and then curing it through drying, baking, or other processes. Furthermore, if the frost-inhibiting film layer is preferably the outermost layer, then it is preferable to form the hydrophilic film layer on top of the aluminum plate, the substrate treatment layer, or the corrosion-resistant film layer.

[0097] From the viewpoint of achieving sufficient hydrophilicity, the amount of hydrophilic film layer is preferably 0.1 mg / dm³. 2 The above, more preferably 0.5 mg / dm 2 The above is further preferred to be 1 mg / dm 2 That's all. Furthermore, when the surface of the fin material is wetted in water, from the viewpoint of preventing the hydrophilic resin from dissolving and inhibiting the effect of the film layer on preventing freezing and frost formation, the film weight of the hydrophilic film layer is preferably 50 mg / dm³. 2 The following is more preferably 30 mg / dm 2 The following is a further preferred value: 10 mg / dm³ 2 the following.

[0098] In addition to hydrophilic resins and surfactants, the hydrophilic film layer may contain any other components without impairing the effects of the present invention. Examples of such components include various aqueous solvents and coating additives used to improve coatability, workability, and the physical properties of the film layer.

[0099] Examples of coating additives include, for example, water-soluble organic solvents, crosslinking agents, surface modifiers, wetting and dispersing agents, anti-settling agents, antioxidants, defoamers, rust inhibitors, antibacterial agents, and mildew inhibitors. These coating additives may be one or more.

[0100] There is no particular limit to the thickness of the hydrophilic film layer, but it is assumed that the density of the hydrophilic film layer is 1 g / cm³. 3 From the viewpoint of obtaining good hydrophilicity, the thickness is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more. Furthermore, although there is no particular upper limit, the thickness of the hydrophilic film layer is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less.

[0101] The thickness of the hydrophilic film layer can be adjusted by factors such as the concentration of the coating composition used to form the hydrophilic film layer and the selection of the doctor blade coater No.

[0102] Furthermore, from the viewpoint of suppressing the reduction of heat exchange efficiency of the fin material, the total film thickness of the fin coating is preferably less than 5 μm. Also, the term "coating" refers to an ice-freezing and frost-resistant coating, or any corrosion-resistant or hydrophilic coating.

[0103] (Substrate treatment layer)

[0104] A substrate treatment layer can be applied to the aluminum plate as needed.

[0105] By having a base treatment layer, the corrosion resistance of the aluminum plate can be improved. In addition, when a corrosion-resistant film layer is also present, the adhesion between the aluminum plate and the corrosion-resistant film layer can be improved.

[0106] The substrate treatment layer, which imparts corrosion resistance to the aluminum sheet, can use conventionally known layers. For example, layers composed of inorganic oxides or inorganic-organic composite compounds can be used.

[0107] As inorganic materials constituting inorganic oxides or inorganic-organic composites, the main components are preferably chromium (Cr), zirconium (Zr), or titanium (Ti).

[0108] The inorganic oxide layer, which serves as the base treatment layer, can be formed, for example, by treating an aluminum plate with chromate phosphate, zirconium phosphate, zirconium oxide, chromate chromate, zinc phosphate, or titanate phosphate. However, the type of inorganic oxide is not limited to those formed by these treatments.

[0109] A layer composed of an inorganic-organic composite compound, serving as a substrate treatment layer, can be formed, for example, by applying a coating-type chromate treatment or a coating-type zirconium treatment to an aluminum plate. Specific examples of such inorganic-organic composite compounds include, for instance, acrylic-zirconium composites.

[0110] The thickness of the substrate treatment layer is not particularly limited and can be set appropriately. However, the preferred method is to make the amount of metal (Cr, Zr, Ti) attached per unit area 1 to 100 mg / m². 2 The preferred film thickness is 1–100 nm.

[0111] The amount of substrate treatment layer and the film thickness can be adjusted by regulating the concentration of the formation solution used for film formation and the film formation time.

[0112] Before forming the substrate treatment layer, the surface of the aluminum plate can be pre-degreased with an alkaline degreasing solution, which improves the reactivity of the substrate treatment and also improves the adhesion of the formed substrate treatment layer.

[0113] (Characteristics of aluminum fins)

[0114] The aluminum fin material of this embodiment can suppress ice nucleation even when condensation is attached to its surface, due to the interaction between the condensation and the ice-freezing and frost-inhibiting film layer. As a result, the freezing of condensation is delayed, and ice-freezing and frost formation on the fin surface can be appropriately suppressed. Moreover, good lubricity can be achieved without hindering the ice-freezing and frost-inhibiting properties.

[0115] The icing and frost suppression effect of finned materials can be evaluated using the following methods.

[0116] A copper plate with refrigerant channels, a Peltier element, and an air channel is installed on the upper inner side of an acrylic cylinder. The device is placed in an environment with a temperature of 10°C and a relative humidity of 55%. At the position on the copper plate that contacts the air inside the cylinder, a test sample formed by cutting finned material into, for example, 35mm × 57mm pieces is placed. Then, air is blown into the cylinder at a wind speed of 1.5 m / s.

[0117] After the above process, while blowing air into the cylinder at the same wind speed, the copper plate is cooled to a surface temperature of -7.5°C, and condensation is intentionally formed on the surface of the test material.

[0118] A digital microscope was set up on the side of the test material with condensation to observe the condensation and frost on the surface of the test material. The time from the start of cooling to the start of frost formation was measured and used as the "freezing and frost delay time" to evaluate the effect of freezing and frost suppression.

[0119] The freezing and frosting delay time obtained by the above method is preferably 3 minutes or more, more preferably 5 minutes or more. Furthermore, there is no specific upper limit, but longer delays are preferred.

[0120] The lubricity of finned materials can be evaluated using the following methods.

[0121] The coefficient of friction of aluminum fins was measured using a Bowden tester under conditions of 200g load and 25°C to evaluate their lubricity.

[0122] The coefficient of friction obtained by the above method is preferably 0.15 or less, more preferably 0.12 or less. Furthermore, there is no particular limitation on the lower limit, but the coefficient of friction obtained by the above method is generally 0.05 or more.

[0123] When using fins in heat exchangers, hydrophilicity is also an important parameter. Therefore, the hydrophilicity of fins can be evaluated based on the contact angle when pure water is dripped onto the surface of the fin.

[0124] Specifically, at room temperature, approximately 2 μL of pure water is dropped onto the surface of the finned material, and the contact angle of the droplet (pure water) is measured using a contact angle measuring instrument. The contact angle of the droplet (pure water) is preferably 30° or less, more preferably 20° or less. Furthermore, although the lower limit is not particularly limited, the contact angle of the droplet (pure water) is generally 5° or more.

[0125] <Manufacturing Method of Aluminum Fin Material>

[0126] An example of the manufacturing method of the aluminum fin material in this embodiment has been described, but it is not limited to this method. Other manufacturing methods can also be used without affecting the effect of this embodiment.

[0127] The following example illustrates the sequential formation of a substrate treatment layer, a corrosion-resistant film layer, and an ice-freezing / frost-inhibiting film layer on the surface of an aluminum plate; however, the formation of the substrate treatment layer and the corrosion-resistant film layer is arbitrary. Furthermore, a hydrophilic film layer can also be formed. In this case, the hydrophilic film layer can be formed using conventionally known methods. Also, the location of the ice-freezing / frost-inhibiting film layer is arbitrary, but it is preferably formed on the outermost layer.

[0128] A substrate treatment layer is formed on the surface of an aluminum plate using known methods. A corrosion-resistant film layer is then formed on the surface using known methods.

[0129] Next, a coating composition containing amphoteric polyacrylamide resin and polyethylene glycol is applied to the corrosion-resistant film layer, and then dried and baked to form an ice-freezing and frost-inhibiting film layer.

[0130] Coating compositions containing amphoteric polyacrylamide resins and polyethylene glycol may also include other components such as crosslinking agents, surfactants, and inorganic materials.

[0131] The solvent for coating compositions containing amphoteric polyacrylic resins and polyethylene glycol is not particularly limited; examples include water, alcohols, and aliphatic ketones. Among these, water or alcohols are preferred, and as alcohols, butanol and ethanol are preferred.

[0132] One solvent can be used, or two or more solvents can be mixed. For example, when used as a mixed solvent of water and alcohol, the alcohol content is 1 to 20 parts by mass relative to 100 parts by mass of water, which is preferred from the viewpoint of coating properties of the substrate.

[0133] The concentration of solids in the coating composition containing amphoteric polyacrylic resin and polyethylene glycol is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 5.0% by mass or more, from the viewpoint of coatability to the substrate. Furthermore, the concentration of solids is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of coatability to the substrate.

[0134] When coating a paint composition containing amphoteric polyacrylic resin and polyethylene glycol, the film thickness is preferably 1 μm or more, more preferably 5 μm or more, from the viewpoint of coatability to the substrate. Furthermore, from the viewpoint of solvent volatility, the film thickness is preferably 40 μm or less, more preferably 20 μm or less. Also, the film thickness mentioned here is the film thickness before drying; for example, when coating the paint composition using a doctor blade coater, it can be adjusted by selecting the doctor blade coater No., etc.

[0135] The application of the corrosion-resistant coating, the hydrophilic coating, and the frost-inhibiting coating can be performed by methods such as doctor blade coating or roller coating. Especially if the aluminum sheet is in roll form, a roller coating device can be used to continuously perform degreasing, coating, heating, and winding, which is preferable in terms of productivity. Furthermore, the baking temperatures for the corrosion-resistant coating, the hydrophilic coating, and the frost-inhibiting coating can be set according to the composition of the resin used, etc., and are preferably in the range of 120–270°C.

[0136] Example

[0137] The present invention will be described in more detail below with examples and comparative examples, but the present invention is not limited to these examples and may be modified and implemented within the scope that can meet its spirit, and these modifications are all included within the technical scope of the present invention.

[0138] (Example 1)

[0139] As an aluminum sheet, alloy number 1070 as specified in JIS H 4000:2014 with a thickness of 0.095 mm is used, and chromate phosphate treatment is performed on the aluminum sheet as a base treatment layer.

[0140] Next, using water as a solvent, a coating composition containing amphoteric polyacrylamide resin (manufactured by Starlight PMC Co., Ltd., T-MP183) and polyethylene glycol (manufactured by Sanyo Chemical Co., Ltd., PEG20000) was prepared and applied to the surface of a substrate-treated aluminum plate using a doctor blade coater. After drying and baking, an ice-freezing and frost-inhibiting film layer was formed, resulting in aluminum fins. The solid composition of the amphoteric polyacrylamide resin and polyethylene glycol is shown in Table 1. Furthermore, the film weight of the ice-freezing and frost-inhibiting film layer was 3.7 mg / dm³. 2 .

[0141] (Example 2)

[0142] Similar to Example 1, after forming a substrate treatment layer on the aluminum plate, a coating composition containing modified urethane resin is applied using a doctor blade coater, dried, and baked to form a corrosion-resistant film layer. The film weight of the corrosion-resistant film layer is 10 mg / dm³. 2 .

[0143] Next, on the surface of the corrosion-resistant film layer, a film amount of 3.7 mg / dm³ was formed, similar to Example 1. 2 The icing and frost-inhibiting film layer is used to obtain aluminum fins.

[0144] (Comparative Example 1)

[0145] The coating composition used for the frost-inhibiting film layer was formulated to contain only the same amphoteric polyacrylamide resin as in Example 1, without polyethylene glycol. Otherwise, it was identical to Example 1, resulting in aluminum fins. The film weight of the frost-inhibiting film layer was 3.1 mg / dm³. 2 .

[0146] (Comparative Example 2)

[0147] On the surface of the frost-inhibiting film layer obtained in Comparative Example 1, a coating composition containing polyethylene glycol was applied, and the mixture was baked to form a functional layer, resulting in an aluminum fin material. The amount of the polyethylene glycol-formed functional layer was 0.6 mg / dm³. 2 .

[0148] (Comparative Example 3)

[0149] Similar to Example 1, after forming a substrate treatment layer on an aluminum plate, a coating composition containing silica is applied, and then baked to form a functional layer, resulting in aluminum fin material. The film weight of the silica-formed functional layer is 200 mg / dm³. 2 .

[0150] (Comparative Example 4)

[0151] The coating composition used for the frost-inhibiting film layer is a coating composition containing an amphoteric polyacrylamide resin and an oxazoline crosslinking agent (Epocros WS700, manufactured by Nippon Shokubai Co., Ltd., a registered trademark). Their solid composition is as described in Table 1. Aluminum fins were obtained in the same manner as in Example 1. The film weight of the frost-inhibiting film layer was 3.2 mg / dm³. 2 .

[0152] (Comparative Example 5)

[0153] The coating composition used for the frost-inhibiting film layer is a coating composition containing amphoteric polyacrylamide resin and zirconium carbonate. Their solid composition is as shown in Table 1. Except for this, aluminum fins were obtained in the same manner as in Example 1. The film weight of the frost-inhibiting film layer was 3.2 mg / dm³. 2 .

[0154] (Comparative Example 6)

[0155] The coating composition used for the frost-inhibiting film layer is a coating composition containing an amphoteric polyacrylamide resin and surfactant A. Their solid composition is as described in Table 1. Except for this, aluminum fins were obtained in the same manner as in Example 1. The film weight of the frost-inhibiting film layer was 3.2 mg / dm³. 2 .

[0156] (Comparative Example 7)

[0157] The coating composition used for the frost-inhibiting film layer is a coating composition containing an amphoteric polyacrylamide resin and surfactant B. Their solid composition is as shown in Table 1. Except for this, aluminum fins were obtained in the same manner as in Example 1. The film weight of the frost-inhibiting film layer was 3.2 mg / dm³. 2 .

[0158] (Comparative Example 8)

[0159] The coating composition used for the frost-inhibiting film layer is a coating composition containing amphoteric polyacrylamide resin and carboxymethyl cellulose (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., SORGEN PR). Their solid composition is as shown in Table 1. Aluminum fins were obtained in the same manner as in Example 1. The film weight of the frost-inhibiting film layer was 3.2 mg / dm³. 2 .

[0160] (Comparative Example 9)

[0161] The coating composition used for the frost-inhibiting film layer is a coating composition containing an amphoteric polyacrylamide resin and a hydrophilic resin. Their solid composition is as shown in Table 1. Except for this, aluminum fins were obtained in the same manner as in Example 1. The film weight of the frost-inhibiting film layer was 3.7 mg / dm³. 2 .

[0162] (Comparative Example 10)

[0163] Similar to Example 2, a substrate treatment layer was formed on an aluminum plate, and then a coating composition containing modified urethane resin was applied using a doctor blade coater. After baking, a corrosion-resistant film layer was formed. The film weight of the corrosion-resistant film layer was 10 mg / dm³.2 .

[0164] Next, on the surface of the corrosion-resistant film layer, similar to Comparative Example 1, a coating composition containing an amphoteric polyacrylamide resin but without polyethylene glycol was used to form a film with a film weight of 3.1 mg / dm³. 2 The icing and frost-inhibiting film layer is used to obtain aluminum fins.

[0165] (Evaluation: Inhibition of freezing and frost formation)

[0166] A copper plate containing refrigerant channels, a Peltier element, and an air channel is placed on the upper inner side of an acrylic cylinder. This device is placed in an environment with a temperature of 10°C and a relative humidity of 55%. At the point on the copper plate that contacts the air inside the cylinder, a test sample formed by cutting aluminum fins into 35mm × 57mm pieces is placed. Then, air is blown into the cylinder at a speed of 1.5 m / s.

[0167] After the above process, while blowing air into the cylinder at the same wind speed, the copper plate is cooled to a surface temperature of -7.5°C, and condensation is intentionally formed on the surface of the fin material.

[0168] A digital microscope was set up on the side of the test material with condensation to observe the condensation and frost on the surface of the test material. The time from the start of cooling to the start of frost formation was measured and used as the "freezing and frost delay time" to evaluate the effect of freezing and frost suppression.

[0169] The evaluation criteria are as follows, and the results are shown in Table 2, "Icing and Frosting Inhibition". Also, in Table 2, "-" indicates that no measurement was taken.

[0170] A. Good (Acceptable): Freezing / frost delay time is more than 3 minutes.

[0171] B. Defective (Unacceptable): Freezing / frost delay time is less than 3 minutes.

[0172] (Evaluation: Lubricity)

[0173] For the surface of aluminum fins, the coefficient of friction was measured using a Bowden testing machine (Kyowa Interface Science Co., Ltd., TS502) under conditions of 200g load and 25°C to evaluate lubricity. The evaluation criteria are as follows, and the results are shown in Table 2, "Lubricity". Also, "-" in Table 2 means not measured.

[0174] A. Good (Pass): Coefficient of friction is below 0.15

[0175] B. Defective (Unacceptable): Coefficient of friction higher than 0.15

[0176] (Evaluation: Hydrophilicity)

[0177] At room temperature, approximately 2 μL of pure water was dropped onto the surface of an aluminum fin, and the contact angle of the droplet (pure water) was measured using a contact angle meter (Kyowa Interface Science Co., Ltd., CA-05 type). The evaluation criteria are as follows, and the results are shown in "Hydrophilicity" in Table 2. Also, in Table 2, "-" indicates that no measurement was taken.

[0178] A. Good (Pass): Contact angle below 30°

[0179] B. Defect (Non-conforming): Contact angle higher than 30°

[0180] Table 1

[0181]

[0182] Table 2

[0183]

[0184] The results above show that aluminum fins, by incorporating an ice-freezing and frost-inhibiting film layer containing amphoteric polyacrylamide resin and polyethylene glycol, achieve excellent ice-freezing and frost-inhibiting properties as well as lubrication. Furthermore, they also exhibit excellent hydrophilicity.

[0185] On the other hand, when a frost-inhibiting film layer without polyethylene glycol is used, as in Comparative Example 1, good frost-inhibiting properties are achieved, but lubricity is poor. Furthermore, as in Comparative Example 2, when an frost-inhibiting film layer formed of amphoteric polyacrylamide resin and a film layer formed of polyethylene glycol are respectively provided, good lubricity is achieved, but frost-inhibiting properties are poor. Therefore, it is evident that providing an frost-inhibiting film layer containing both amphoteric polyacrylamide resin and polyethylene glycol is necessary to achieve both frost-inhibiting effect and good lubricity.

Claims

1. An aluminum fin material having an aluminum plate and a film layer formed on the surface of the aluminum plate, the film layer comprising an ice-freezing and frost-inhibiting film layer containing an amphoteric polyacrylamide resin and polyethylene glycol, wherein the content of the amphoteric polyacrylamide resin in the ice-freezing and frost-inhibiting film layer is 50% by mass or more and 99% by mass or less in terms of solid components, and the content of the polyethylene glycol in the ice-freezing and frost-inhibiting film layer is 1% by mass or more and 50% by mass or less in terms of solid components.

2. The aluminum fin material according to claim 1, wherein, A substrate treatment layer is also provided between the aluminum plate and the film layer.

3. The aluminum fin material according to claim 1 or 2, wherein, The film layer is formed on both surfaces of the aluminum plate.

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