JP2000129202A - Coating composition and hydrophilic aluminum steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating composition which, when applied to the surface of an aluminum material, can form a coating film kept hydrophilic for a relatively long term by incorporating a polyalkylene glycol resin with a hydrophilic resin having hydroxyl, carboxyl, sulfo, or phospho groups. SOLUTION: A composition is obtained by mixing 20-80 wt.%, especially, 30-70 wt.% polyalkylene glycol resin having a molecular weight of at least 5,000, especially, at least 10,000 with a hydrophilic resin having at least one type of functional groups selected from among hydroxyl groups, carboxyl groups, sulfo groups, phospho groups, and salts thereof. The objective coating composition is obtained by mixing 100 pts.wt. (in terms of the solid matter) aqueous dispersion obtained by dispersing the above obtained composition in water and having a mean particle diameter of at most 500 nm and a concentration of 20-60 wt.% with 5-70 pts.wt. resin for curing, and, optionally, at most 30 wt.% additives such as colloidal silica, a water-soluble organic solvent, a leveling agent, a defoamant, a surfactant, a preservative, an antibacterial agent, and an antimold agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous hydrophilicity-imparting agent suitable for imparting hydrophilicity to the surface of an aluminum material and a precoated fin material for a heat exchanger using the agent.

[0002]

2. Description of the Related Art Generally, in a heat exchanger such as an air conditioner used for a building or an automobile, an aluminum material (hereinafter referred to as aluminum or aluminum alloy) is formed into a predetermined fin shape. Fin material is used. In such a fin material, since the interval between the fins is narrowed due to the purpose of increasing the heat exchange efficiency and the effect of miniaturization of the air conditioning equipment, water condensed on the fin surface during cooling or the like becomes spherical. A phenomenon occurs in which a bridge is formed between the fins, and as a result, there is a problem that the ventilation resistance increases and the heat exchange capacity decreases.

[0003] For this reason, conventionally, a surface treatment for imparting hydrophilicity to the fin surface by applying a hydrophilicity imparting agent to the fin base material before fin processing is conventionally performed. This is to increase the hydrophilicity of the fin surface so that the water adhering to the fin surface spreads over the entire surface of the fin surface without agglomeration, thereby avoiding the above-mentioned bridging phenomenon. Note that a fin material in which such a hydrophilicity-imparting agent or the like is applied before use before forming is usually also referred to as a pre-coated fin material.

As such a hydrophilicity-imparting agent, for example, those containing silica and an organic polymer as main components are known (JP-A-53-92846, JP-A-5-92846).
JP-A-5-99976 and JP-A-6-221786.

[0005]

However, conventional hydrophilicity-imparting agents containing silica and an organic polymer as main components are:
Although the hydrophilicity is well exhibited in the initial stage, the hydrophilicity tends to gradually deteriorate over time due to repeated dry / wet conditions and adhesion of hydrocarbons in the air, etc. There is a demand for improvement.

[0006] Further, the hydrophilicity-imparting materials proposed in the above publications are all alkaline in view of the composition and the like, and the surface after being applied to the fin base material is relatively low as described later. It tends to be smooth. Then, not only the hydrophilicity persistence is insufficient on such a fin-coated surface, but another phenomenon that water is repelled is observed. In JP-A-6-221786, a mixed solution (alkali) of a silicate (sodium silicate), a water-soluble resin (sodium polyacrylate) and water is applied to an aluminum plate in Example 1. , Average particle size 0.5 μm
Although a pre-coated fin material that forms a hydrophilic film with silica particles is shown, the film itself to be formed becomes alkaline, which causes foaming and deterioration of the volatile press oil during fin processing and reduces the corrosion resistance of the fin material. And there is a problem that the film structure deteriorates with time due to elution of alkali.

[0007] Further, the pre-coated fin material is usually stored in a roll before storage, and when the fin material is coated with a conventional hydrophilicity imparting agent, the fins adhere to each other. So-called blocking may occur.

[0008] The object of the present invention is to provide, for example, when applied to the surface of an aluminum material, not only excellent hydrophilicity can be obtained in the initial stage, but also aqueous hydrophilicity imparted continuously over a relatively long period of time. To provide an agent. Another object of the present invention is to provide a method for producing a precoated fin material for a heat exchanger, which can produce a high quality precoated fin material that does not cause blocking even when rolled, in addition to obtaining such excellent hydrophilicity. Is to provide.

[0009]

That is, the present invention provides: (1) a coating composition comprising a hydrophilic resin containing the following components: A) a polyalkylene glycol resin; Resin having at least one kind of functional group or a functional group of a salt thereof a) group: hydroxyl group, carboxyl group, sulfonic acid group, phosphoric acid group

(2) A coating composition, wherein the hydrophilic resin described in 1 above is at least one of a copolymer polyester and a polyurethane resin of a copolymer polyester polyol.

(3) A coating composition according to any one of the above (1) and (2), comprising a curing agent.

(4) A hydrophilic aluminum steel sheet, wherein the coating composition described in any one of the above items 1, 2, and 3 is provided on at least one surface of the aluminum steel sheet.

(5) A precoated fin material for a heat exchanger, wherein the coating composition described in any one of (1), (2) and (3) is provided on at least one surface of an aluminum steel plate. It is about.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrophilic resin used in the present invention contains a polyalkylene glycol and a hydrophilic resin. As the hydrophilic resin, a polyester resin, an epoxy resin, an acrylic resin, or the like can be used, but the polyester resin is most preferable from the viewpoint of practical characteristics such as substrate adhesion.

The polyester resin is preferably a copolymerized polyester containing an aromatic dicarboxylic acid and an alicyclic dicarboxylic acid as a main skeleton, and a polyester polyurethane having the copolymerized polyester as a main component is also preferable. Hereinafter, when it is described as a polyester resin, such a polyester polyurethane is also included.

In the polyester resin suitable for the hydrophilic resin of the present invention, a hydrophilic functional group (hydroxyl group,
It is preferable to include a carboxyl group, a sulfonic acid group, a phosphoric acid group) in the polyester resin from the viewpoint of the balance between the adhesion of the coated film to the substrate after coating and the function of imparting hydrophilicity. The functional group having a hydrophilicity-imparting function contained in such a polyester is preferably a sulfonic acid group or a salt thereof, and more preferably an ammonium salt or an alkylamine salt of a sulfonic acid group.

The hydrophilic resin preferably contains a polyester containing 60 mol% or more of aromatic and alicyclic dicarboxylic acids in all carboxylic acid components, or a polyester polyurethane containing the polyester as a main component.
Conventional acrylic and olefinic cationic polymers are generally brittle, and because they contain polar functional groups, the polarity of the polymer increases and the adhesion to various substrates may be insufficient. The hydrophilicity-imparting layer of the present invention shows that the polyester or polyester urethane in the resin layer exhibits improved adhesion and adhesion to a substrate such as an aluminum steel plate and compatibility when various resins are added.

Since the polymer containing a hydrophilic group has a sufficient hydrophilic group, it can be dispersed in water and can be made completely water-based without any solvent. From the viewpoint of the influence of the organic solvent on the environment, which has recently been described, the polymer containing a hydrophilic group is preferably an aqueous dispersion.

Further, as the curing agent, a melamine-based curing agent,
Epoxy-based curing agents and isocyanate-based curing agents are exemplified. Among them, nonionic or cationic methylol-based melamine can be used as the melamine-based curing agent. Hereinafter, each item will be described.

(Polyester Resin) (Copolymer Polyester) A preferable polymerization composition of the copolymer polyester used in the present invention is such that the dicarboxylic acid component is 60 to 99 mol% of aromatic dicarboxylic acid, aliphatic and / or alicyclic dicarboxylic acid. 0 to 40 mol%, dicarboxylic acid containing a hydrophilic group, 0.5 to 10 mol%.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid and the like. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecandionic acid, and dimer acid.Examples of the alicyclic dicarboxylic acid include 1,4-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. 3
-Cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and acid anhydrides thereof.

Examples of the dicarboxylic acid containing a hydrophilic group include 5-sodium sulfoisophthalic acid.

Further, p- (2-hydroxyethoxy) benzoic acid or a hydroxycarboxylic acid such as hydroxypivalic acid, γ-butyrolactone or ε-caprolactone can be used if necessary.

The aromatic dicarboxylic acid of the dicarboxylic acid component is more preferably 70 to 99 mol%, and the aliphatic dicarboxylic acid and / or alicyclic dicarboxylic acid is more preferably 0 to 30 mol%. 60 aromatic dicarboxylic acids
When it is less than mol%, the mechanical properties of the coating film are inferior. In addition, when the aliphatic dicarboxylic acid and / or the alicyclic dicarboxylic acid are 40
If the amount exceeds mol%, not only the hardness and stain resistance are reduced, but also the aliphatic ester bond has a lower hydrolysis resistance than the aromatic ester bond. In some cases, the degree of polymerization of the polyester may be reduced during the storage period.

The content of the dicarboxylic acid containing a hydrophilic group is preferably from 0.5 to 10 mol%, more preferably from 1 to 7 mol%, and still more preferably from 1 to 5 mol%, based on the total acid components. . When the amount of the dicarboxylic acid containing a hydrophilic group is 0.5 mol% or less, the dispersibility of the polyester resin in water may not be sufficiently provided, and the dispersed particle diameter in an aqueous medium tends to increase. Stability tends to decrease. When the amount of the dicarboxylic acid containing a hydrophilic group exceeds 20 mol%, the hydrophilicity of the coating film is remarkably increased, the resin becomes water-soluble, peeling may be observed, and the water resistance performance is reduced, and stable hydrophilicity performance is exhibited. It is not desirable because it hinders

On the other hand, the glycol component comprises an aliphatic glycol having 2 to 10 carbon atoms and / or an alicyclic glycol having 6 to 12 carbon atoms and / or an ether bond-containing glycol. Examples of the aliphatic glycol having 2 to 10 carbon atoms include ethylene glycol and 1,2-propylene glycol.
1,3-propanediol, 1,4-butanediol
1,1,5-pentanediole, neopentyl glyco-
1,6-hexanediol, 3-methyl-1,5-
Pentandiol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol, neopentyl glycol hydroxypivalionate, dimethylol heptane, etc., and an alicyclic group having 6 to 12 carbon atoms. Examples of the glycol include 1,4-cyclohexanedimethanol, tricyclodecanedimethylol, and the like.

As the glycol containing an ether bond, diethylene glycol, triethylene glycol, dipropylene glycol, and ethylene oxide or propylene oxide may be added to two phenolic hydroxyl groups of bisphenols. Glycols obtained by adding one to several moles each, for example, 2,2-bis (4-hydroxyethoxyphenyl) propane and the like can be mentioned.

In the copolymerized polyester used in the present invention, 0 to 5 mol% of a tri- or more functional polycarboxylic acid and / or
Or, a polyol can be copolymerized, but as a tricarboxylic or more polycarboxylic acid, trimellitic acid (anhydride),
(Anhydride) pyromellitic acid, (anhydride) benzophenonetetracarboxylic acid, trimesic acid, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimellitate) and the like are used. 3
Glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like are used as the functional or higher polyol. The trifunctional or higher polycarboxylic acid and / or polyol is used in an amount of 0 to 5 mol%, preferably 0 to 3 mol%, based on the total acid component or total glycol component.
However, if it exceeds 5 mol%, it becomes difficult to impart sufficient processability.

The terminal of the copolyester of the present invention may be a carboxylic acid, and the chain may be extended with an epoxy compound.

(Polyurethane resin) The polyurethane resin in the present invention is a polyester polyol (a) comprising the above-mentioned copolymerized polyester, an organic diisocyanate compound
(b) and, if necessary, a chain extender having an active hydrogen group
(c) having a molecular weight of 5,000 to 100,000,
Urethane bond content is 500 to 4000 equivalent / 10 ⁶
g, hydrophilic group content is 1.5 to 30 on average per molecule.

The polyester polyol used in the present invention
(a) has a hydroxyl group at both terminal groups and a molecular weight of 500 to 10
000 is desirable. The polyester polyol used in the present invention has a dicarboxylic acid component of at least 6
It is necessary that at least 0 mol%, desirably at least 70 mol% be composed of aromatic dicarboxylic acid. An aliphatic polyester polyol widely used for general polyurethane resins, for example, a polyurethane resin using adipate of ethylene glycol or neopentyl glycol has extremely low water resistance. As an example, the reduced viscosity retention of this aliphatic polyester polyurethane after immersion in hot water at 70 ° C. for 20 days is as low as 20 to 30%, while the resin having the same glycol terephthalate and isophthalate as the polyester polyol has the same conditions. The reduced viscosity retention rate is 8
It is as high as 0 to 90%. Therefore, it is necessary to use a polyester polyol mainly composed of an aromatic dicarboxylic acid for high water resistance of the coating film. Further, a polyolefin polyol or the like can be used together with these polyester polyols, if necessary.

The organic diisocyanate compound (b) used in the present invention includes hexamethylene diisocyanate, tetramethylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, p-xylylene diisocyanate, and m-xylylene diisocyanate. 1,3-diisocyanatomethylcyclohexane, 4,4′-diisocyanatodicyclohexane,
4,4′-diisocyanatodicyclohexylmethane,
Isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-
Phenylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, 2,4
-Naphthalenediisocyanate, 3,3'-dimethyl-
4,4'-biphenylenediisocyanate, 4,4'-
Examples include diisocyanate diphenyl ether, 1,5-naphthalenediisocyanate, and the like.

In the present invention, examples of the chain extender (c) having an active hydrogen group used as required include ethylene glycol, propylene glycol, neopentyl glycol, 2,2-diethyl-1,3-propane. Examples thereof include glycols such as diol, diethylene glycol, spiro glycol, and polyethylene glycol, and amines such as hexamethylene diamine, propylene diamine, and hexamethylene diamine.

The polyurethane resin used in the present invention comprises a polyester polyol (a), an organic diisocyanate (b),
And, if necessary, a chain extender (c) having an active hydrogen group with an active hydrogen group / isocyanate ratio of (a) + (c).
It must be a polyurethane resin obtained by reacting at a compounding ratio of 0.8 to 1.3 (equivalent ratio). When the ratio of active hydrogen groups / isocyanate groups of (a) + (c) is out of this range, the urethane resin cannot have a sufficiently high molecular weight,
The desired coating film properties cannot be obtained.

The polyurethane resin used in the present invention is produced in a known manner at a reaction temperature of 20 to 150 ° C. in a solvent in the presence or absence of a catalyst. As the solvent used at this time, for example, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, and esters such as ethyl acetate and butyl acetate can be used. As a catalyst for accelerating the reaction, amines, organotin compounds and the like are used. It can also be produced by kneading a polyester polyol and an organic diisocyanate in a molten state.

(Polyalkylene glycol) The polyalkylene glycol used in the present invention includes polyethylene glycol, polypropylene glycol and polytetramethylene glycol. Among them, polyethylene glycol is desirable. The molecular weight is preferably 5,000 or more, more preferably 10,000 or more, and most preferably 150
00 or more. When the molecular weight is lower than 5,000, unfavorable points such as occurrence of blocking are observed.

(Hydrophilic polyester resin) The hydrophilic resin of the present invention can be obtained by blending the above-mentioned polyester resin with polyalkylene glycol.

The ratio of the polyalkylene glycol moiety in the resin of the present invention is preferably 20 to 80%, more preferably 30 to 70%, and most preferably 40 to 60%. When the ratio of the polyalkylene glycol moiety in the resin is 2
When it is 0% or less, it is difficult to impart hydrophilicity. The ratio is 80
%, The hydrophilicity becomes high, the water resistance becomes poor, and in addition, there are many unfavorable points such as an increase in solution viscosity and a decrease in coating suitability.

(Water dispersion) The hydrophilic resin according to the present invention can be easily dispersed in water into fine particles having an average particle diameter of 500 nm or less. When carrying out water dispersion, a melt state,
Alternatively, a solid (pellet, powder, etc.) hydrophilic resin can be poured into water and stirred under heating to form an aqueous dispersion, but most preferably, the hydrophilic resin is blended and dissolved in a solvent. Thereafter, a method of adding water and further heating and stirring to obtain an aqueous dispersion (one-pot method) is desirable. Further, when the boiling point of the solvent is 100 ° C. or lower, part or all of the solvent used in the complexing reaction can be easily removed by distillation.

The aqueous dispersion produced according to the present invention has a solid content of 20 to 60% by weight, and may be used by adding water and diluting it as necessary.

(Curing Agent) Examples of the crosslinking agent for the hydrophilic resin described above include phenol formaldehyde resin, amino resin, polyfunctional epoxy compound, polyfunctional isocyanate compound and various blocked isocyanate compounds,
Various curing agents such as a polyfunctional aziridine compound can be used. In particular, a melamine-based curing agent can be used as a curing agent capable of obtaining a coating film excellent in water resistance, solvent resistance, transparency, adhesion, and heat resistance by heating at a low temperature for a short time.

The curing reaction is generally carried out according to the aqueous dispersion 1 of the present invention.
5-70 parts (solid content) of the curing resin is blended with 00 parts (solid content), and heating is performed for about 1 to 60 minutes in a temperature range of 60 to 250 ° C. depending on the type of the curing agent. If necessary, a reaction catalyst or a promoter is also used.

(Additives) This imparting agent may optionally include colloidal silica, a water-soluble organic solvent, a leveling agent, a defoaming agent, a surfactant, a preservative, an antibacterial agent, and an antimicrobial agent. Components can be added, and in that case, the total content is not more than 30% by weight based on the entire imparting agent. The content of each optional component is in the range of 0.1 to 10% by weight based on the entire imparting agent.

The colloidal silica may be either an acid (pH 1 to 4) stable silica sol or an alkali (pH 9 to 10.5) stable silica sol provided as an aqueous dispersion. Of 5 to 100 nm, preferably 10 to 30 nm. When using alkali-stable colloidal silica, the colloidal silica is neutralized by the acid of the carboxylic acid, but in order to minimize aggregation of the silica in a bath having a PH value of 1 to 5, It is important to minimize the time for the alkali-stable colloidal silica to pass (reside) in the neutral range of pH 5 to 7 in the bath. If the dispersed particle diameter is less than 5 nm, the silica is likely to aggregate, and the required roughened surface cannot be obtained, and the hydrophilicity level is low. 10 on the contrary
If it exceeds 0 nm, the silica will coalesce and the stability of the bath will deteriorate.

The water-soluble organic solvent is added to dilute the water-soluble polymer, and specifically, alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol and ethylene glycol are used. . The leveling agent is added to reduce the surface strength of the imparting agent, and specifically, a silicon-based leveling agent such as polysiloxane and silicon oligomer, a fluorine-based leveling agent such as perfluoroalkyl, and a polyacrylate. And other acrylic leveling agents. The antifoaming agent is added to suppress the generation of foam at the time of adjusting or applying the imparting agent, and specifically, glycols such as polypropylene glycol, methanol, ethanol, isopropanol, n-butanol, isobutanol And lower fatty acids such as metal soaps and higher fatty acid metal soaps such as metal soaps. Surfactants are added to lower the surface tension of the imparting agent to improve applicability or to function as an initial hydrophilicity imparting agent in the coating film.Specifically, alkylbenzene sulfonate, alkyl Anionic surfactants such as sulfosuccinates and nonionic surfactants such as polyoxyethylene alkylamines and polyoxyethylene alkyl ethers are used. In addition, a cationic surfactant is not preferable from the bath stability of the imparting agent. Preservative,
Antibacterial agents, antifungal agents, etc. are added to prevent the generation of mold odor due to corrosion odor and mold generation.
Imidazole-based compounds such as (4-thiazolyl) -benzimidazole, methyl 2-benzimidazole carbamate, 2-dicarboximide, and O-phenylphenol are used. These preservatives, antibacterial agents, antifungal agents and the like are preferably added so that the total solid content is 5 to 20% by weight.

(Lamination Method) The imparting agent of the present invention is prepared as an aqueous composition (paint) by blending a polymer, water and, if necessary, optional additives under the above-mentioned conditions. This imparting agent has a surface strength of 4 depending on the application means.
It is prepared so that the viscosity is 0 dyn / cm or less and the viscosity is 5 to 100 CPS (20 ° C.). The imparting agent is used by being applied to aluminum or an alloy thereof, but may be applied to other metal materials for the purpose of, for example, preventing dew condensation.

In producing a precoated fin material for a heat exchanger using the imparting agent of the present invention, the imparting agent is applied directly to the surface of an aluminum fin substrate or on a corrosion-resistant undercoat formed on the surface. And then dried by heating. When the application material is directly applied, the surface of the fin base material is subjected to a degreasing treatment or the like. In addition, as a corrosion-resistant undercoat, chromate chromate treatment, phosphoric acid chromate treatment,
An inorganic film formed by a coating type chromate treatment or a corrosion-resistant resin film such as an acrylic resin or an epoxy resin is formed. In this case, the thickness of the inorganic film is preferably 0.01 to 0.2 μm, and the thickness of the corrosion-resistant resin film is preferably 0.5 to 3 μm.

The application of the imparting agent to the fin base material is performed by using a coating method such as a roll coating method, a bar coating method, a spraying method, a immersion method or the like so that the solid content becomes 0.3 to 1.5 g / m ² . Do so. When the amount of adhesion is less than 0.3 g / m ² , the level of hydrophilicity in the coating film is low, and in the case where coating unevenness occurs, a partially required hydrophilicity cannot be obtained. Conversely, 1.
If it exceeds 5 g / m ² , there will be no further improvement in the hydrophilicity level, and problems such as peeling of the coating film during fin molding will occur.

The heating and drying after the coating is performed at a heating temperature of 200 to
It is preferable to perform the heating at 280 ° C. and a heating time of 5 to 60 seconds. If the heating temperature is lower than 200 ° C., the polymer component becomes uncured, and the coating film dissolves or wets when it comes into contact with water. It becomes brittle. On the other hand, when the heating time exceeds 60 seconds, not only the improvement of the coating film performance is not observed, but also the production cost is increased. Therefore, the heating time is preferably 10 to 30 seconds.

The precoated fin material thus obtained is wound into a roll as necessary, stored, and then applied with a volatile press oil, and then subjected to a forming process such as a slitting process or a corrugating process. A fin material for a heat exchanger having a desired shape is used. Then, the hydrophilic coating is exposed by heating the fin material to volatilize the volatile press oil from the surface.

[0051]

Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited by these. In the examples, “parts” means “parts by weight”, and “%” means “% by weight”.

[Production Example of Polyester Resin] Stirrer,
Dimethyl terephthalate 60 in a stainless steel autoclave equipped with a thermometer and a partial reflux condenser
g, 60 g of dimethyl isophthalate, 41 g of ethylene glycol, 50 g of 3-methylpentanediol, and 0.52 g of tetra-n-butyl titanate.
The transesterification reaction was performed for 4 hours from 0 to 220 ° C. Next, 29 g of 5-sodium sulfoisophthalic acid was added, and an esterification reaction was carried out at 200 ° C. for 30 minutes. Thereafter, the temperature was raised to 250 ° C., and the pressure of the reaction system was gradually reduced. Obtained polyester resin A
Was pale yellow and transparent.

[Production Example of Coating Liquid] In a glass flask equipped with a stirrer, a thermometer and a reflux condenser, 60 g of the polyester resin A obtained by the method shown in the production example of the hydrophilic resin and polyethylene glycol (# 20,000) ) 4
To 0 g, 30 g of methyl ethyl ketone and 30 g of toluene were charged and heated and stirred to dissolve the resin. Water 10 in dissolved resin
g was further added and stirred for 1 hour to obtain a coating liquid.

Example 1 The polyester resin obtained above was applied to a degreased aluminum fin substrate with a coater so that the solid content was 0.8 g / m ^2, and then the coating was performed at 240 ° C. for 30 seconds. Heat drying was performed to produce a precoated fin material. In order to know the coating properties of the obtained fin material, the initial hydrophilicity, hydrophilicity persistence, and wet adhesion of the coating were examined. Regarding the initial hydrophilicity, 1
The spreading diameter (mmφ) of the water droplet when 0 μL (microliter) of deionized water was removed was measured. Regarding the hydrophilicity persistence, fresh tap water is always spread over a 10 cm square fin material so as to spread over the entire surface (flow rate on the fin material is about 10%).
cm / s) for 7 hours, and then allowed to stand at a temperature of 20 ° C. for 17 hours, followed by drying. The test was repeated 10 times.
φ) was measured. Regarding the wet adhesion, after the fin material was immersed in running water for 100 hours and dried at room temperature, the number of adhered pieces when the cross-cut cellophane tape (Nichiban cellophane tape) was peeled off was measured. The result is that the initial hydrophilicity is 10mmφ or more,
Hydrophilicity lasting more than 10mmφ, wet adhesion 100/10
It was 0. In addition, the life of the bath was examined.
The state was stable even after 0 days had passed. Regarding the life of this bath, the same results were obtained in Examples 2 and 3 described later.

Example 2 A hydrophilicity-imparting agent was prepared under the same conditions as in Example 1 except that 0.3 g of glycerin was added to adjust the total weight to 100 g. Then, this imparting agent was applied to the degreased aluminum fin base material in Example 1.
The precoated fin material was prepared by applying under the same conditions as above and drying by heating. In the case of this example, the coating properties are such that the initial hydrophilicity is 10 mmφ or more, and the hydrophilicity lasting 10 mmφ.
As described above, the wet adhesion was 100/100.

Example 3 The hydrophilicity imparting agent of Example 1 was
The coating was performed under the same conditions as in Example 1 except that the coating was performed so that the solid content was 0.6 g / m ^2, and the coating was heated and dried to prepare a precoated fin material. In the case of this example, the properties of the coating film were such that the initial hydrophilicity was 10 mmφ or more, the hydrophilicity persistence was 10 mmφ or more, and the wet adhesion was 100/100.

Example 4 The amount of 2 corresponding to 7% by weight
A hydrophilicity-imparting agent was prepared under the same conditions as in Example 1 except that (4 thiazolyl) -benzimidazole was added to adjust the total weight to 100 g. Then, this imparting agent was applied to a degreased aluminum fin substrate under the same conditions as in Example 1, and dried by heating to prepare a precoated fin material. The antimicrobial and antifungal properties of this fin material were measured at 28 ° C. and 37 ° C. in a thermostat using a bacterial agar medium and a mold agar medium.
When stored at 48 ° C. for 48 hours and examined for growth status, neither bacteria nor mold was detected.

Example 5 The same procedure as in Example 1 was repeated except that 8 g of an aqueous polyester resin solution was used, and a water-soluble epoxy resin (trade name: Denacol EX313, manufactured by Nagase Kasei Co., Ltd., solid content 100)
% And an epoxy equivalent of 141) were mixed under the same conditions as in Example 1 except that 2 g of an epoxy equivalent was blended. Then, this imparting agent was applied to the degreased aluminum fin base material in Example 1.
The precoated fin material was prepared by applying under the same conditions as above and drying by heating. In the case of this example, the properties of the coating film were such that the initial hydrophilicity was 10 mmφ, the hydrophilicity persistence was 10 mmφ, and the wet adhesion was 100/100.

[0059]

As described above, according to the hydrophilicity imparting agent of the present invention, when the imparting agent is applied to, for example, the surface of an aluminum material, the adhesion of the coating film is good.
A high level of hydrophilicity can be obtained, and excellent hydrophilicity can be obtained not only in the initial stage but also for a long period of time. Further, according to the production method of the present invention, in addition to obtaining the above-mentioned good hydrophilicity, a high-quality precoated fin material that does not cause blocking even when wound into a roll can be obtained. The precoated fin material has good press workability during molding.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J038 DD051 DF011 DG111 DG231 GA03 GA06 GA13 GA14 JA19 JA20 KA03 NA06 NA11 PB06 PC02

Claims (5)

[Claims] 1. A coating composition comprising a hydrophilic resin containing the following components. A) Polyalkylene glycol resin B) Hydrophilic resin having at least one kind of a functional group selected from the following a) group or a salt thereof, a) group: hydroxyl group, carboxyl group, sulfonic acid group, phosphoric acid Base 2. A coating composition, wherein the hydrophilic resin according to claim 1 is at least one of a copolymerized polyester and a polyurethane resin of a copolymerized polyester polyol. 3. The coating composition according to claim 1, further comprising a curing agent. 4. A hydrophilic aluminum steel sheet comprising the coating composition according to claim 1, provided on at least one surface of the aluminum steel sheet. 5. A precoated fin material for a heat exchanger, wherein the coating composition according to claim 1 is provided on at least one surface of an aluminum steel sheet.