JPH04366182A - Hydrophilic surface-treating agent, hydrophilic surface treatment bath and hydrophilic surface treatment - Google Patents

Abstract

PURPOSE:To provide a hydrophilic surface-treating agent which can form a film which can give corrosion resistance and hydrophilicity to an aluminum material such as an aluminum fin of a heat exchanger and can prevent the formation of an unpleasant odor. CONSTITUTION:A hydrophilic surface-treating agent containing polyvinylpyrrolidone of a degree of polymerization of 50-1000 and polyvinyl alcohol of a degree of hydrolysis of 80% or above and a degree of polymerization of 100-1000 in a specified ratio.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a hydrophilic surface treatment agent for aluminum materials such as heat exchanger fins, a hydrophilic surface treatment bath, and a surface treatment method using the same. A hydrophilic surface treatment agent that forms a film on aluminum materials such as fins that has corrosion resistance and hydrophilicity and suppresses odors generated from heat exchangers.
The present invention relates to a hydrophilic surface treatment bath and a surface treatment method using the same.

0002

2. Description of the Related Art Aluminum and its alloys are lightweight and have excellent workability and thermal conductivity, and are widely used in heat exchangers. BACKGROUND ART With the spread of air conditioning systems, the number of air conditioners that can be used for cooling, dehumidification, and heating and cooling has increased, and aluminum alloy fins are generally used in the heat exchange parts of these air conditioners.

During cooling operation of an air conditioner, moisture in the air tends to adhere to the surface of the fins as condensed water. To prevent this, it is possible to make the surface of the fins water-repellent, but if this is done, the condensed water will adhere to the fins in a hemispherical shape or exist in the form of bridges between the fins, which will prevent the smooth flow of air. , which increases ventilation resistance. Making the fin surface water repellent in this way will conversely reduce the heat exchange efficiency.

On the other hand, aluminum and its alloys inherently have excellent corrosion resistance, but if condensed water remains on the fin surface for a long period of time, it may form an oxygen concentration cell or pollutants in the atmosphere may gradually adhere and concentrate, causing a hydration reaction. and corrosion reactions are accelerated. Of course, these corrosion products accumulate on the fin surface and impair the heat exchange characteristics, but during heating operation in winter,
It becomes a fine white powder and is discharged along with warm air by a blower.

[0005] Therefore, in order to improve these problems,
In order to improve the corrosion resistance of the fin and at the same time increase the hydrophilicity of its surface, various attempts have been made to form a film on the surface of the fin that has both of the above properties.

For example, JP-A-55-12375 and JP-A-56-56,572 disclose an evaporator in which a synthetic resin film having a hydrophilic amide group is provided on the surface of the fin. For example, soluble nylon is used as the synthetic resin film having a hydrophilic amide group. Further, JP-A-61-250495 discloses an aluminum fin in which a resin film made of an organic polymer material such as a water-soluble polyamide resin that exhibits cationic properties in an aqueous solution is formed on a chemical conversion film. Further, JP-A-63-57674 discloses a treatment agent for forming a hydrophilic film containing a water-soluble resin such as water-soluble nylon, an alkali metal silicate, and an amino alcohol. Furthermore, JP-A-62-
No. 132970 contains (a) at least one member selected from the group of urea, thiourea, and guanidine; and (b)
A surface treatment agent for heat exchanger fins containing an addition reaction product with formalin or a condensation product of this addition reaction product and water-soluble nylon is disclosed, and JP-A-62-176578 discloses a treatment using the treatment agent. The method is disclosed. Further, JP-A-2-102277 discloses a metal surface containing (a) a block copolymer consisting of a hydrophilic monomer and a vinyl monomer having a crosslinking functional group, and (b) a surfactant. Discloses a composition for coating and cites vinylpyrrolidone as one type of hydrophilic monomer.

[0007]

[Problems to be Solved by the Invention] However, the surface treatment methods using the above-mentioned films or treatment agents have not been able to sufficiently satisfy both hydrophilicity and odor suppression (prevention) effects. In addition, an aluminum heat exchanger (Japanese Patent Application Laid-open No. 60-5-5) was designed to suppress the generation of microorganisms in the condensed water on the surface of the heat exchanger and remove odor caused by microorganisms.
No. 0397), but it is not sufficient in terms of hydrophilicity and odor suppressing effect. As described above, with the conventional surface treatment techniques for heat exchanger fins, it is not possible to obtain a film that has sufficient hydrophilicity and corrosion resistance, has good film strength, and is odor-free. Therefore, the object of the present invention is to provide a surface treatment agent, a surface treatment bath, and the like for forming a hydrophilic film for use in heat exchanger fins, etc., which has good hydrophilicity, corrosion resistance, water solubility, etc., and does not generate unpleasant odors. It is also an object of the present invention to provide a surface treatment method using the same.

[0008]

[Means for Solving the Problems] As a result of extensive studies to achieve the above object, the present inventors have developed polyvinylpyrrolidone having a specific degree of polymerization, and polyvinyl alcohol having a specific degree of saponification and polymerization. The present invention was completed based on the discovery that by blending these in a specific ratio, it is possible to form a hydrophilic film that has good hydrophilicity, corrosion resistance, etc., and does not generate unpleasant odors.

That is, the hydrophilic surface treatment agent of the present invention is
In terms of solid content, (a) 0.5 to 6 parts by weight of polyvinylpyrrolidone with a degree of polymerization of 50 to 1000, and (b) 1 to 10 parts of polyvinyl alcohol with a degree of saponification of 80% or more and a degree of polymerization of 100 to 1000. parts by weight, and the component (a
) and component (a) relative to the total amount of component (b).
The weight ratio (a) / [(a) + (b)] is 0.1
It is characterized by being in the range of ~0.9.

The hydrophilic surface treatment bath of the present invention also contains (a) 0.5 to 6 parts by weight of polyvinylpyrrolidone with a degree of polymerization of 50 to 1000, and (b) a degree of saponification of 8 in terms of solid content.
0% or more, and 1 to 10 parts by weight of polyvinyl alcohol having a degree of polymerization of 100 to 1000, and the component (a)
and the weight ratio (a)/[(a) + (b)] of the component (a) to the total amount of the component (b) is 0.1 to
Hydrophilic surface treatment agent in the range of 0.9 to 10 to 20
It is characterized in that it is contained at a concentration of 0 g/liter.

Furthermore, the hydrophilic surface treatment method of the present invention includes:
(1) Apply chemical conversion treatment to the object to be coated, (2) Next,
In terms of solid content, (a) 0.5 to 6 parts by weight of polyvinylpyrrolidone with a degree of polymerization of 50 to 1000, and (b) 1 to 10 parts of polyvinyl alcohol with a degree of saponification of 80% or more and a degree of polymerization of 100 to 1000. parts by weight, and the components (
said component (a) relative to the total amount of component (a) and component (b).
) weight ratio (a) / [(a) + (b) ] is 0.
It is characterized in that the treatment is carried out using a hydrophilic surface treatment bath containing a hydrophilic surface treatment agent in the range of 1 to 0.9.

The present invention will be explained in detail below. Hydrophilic Surface Treatment Agent The hydrophilic surface treatment agent of the present invention contains (a) polyvinylpyrrolidone and (b) polyvinyl alcohol. First, polyvinylpyrrolidone used in the present invention has the following general formula:

It is represented by the following formula (where n represents the degree of polymerization) and is obtained by polymerizing N-vinyl-2-pyrrolidone.

In the present invention, the degree of polymerization n of polyvinylpyrrolidone is from 50 to 1,000. If polyvinylpyrrolidone having a degree of polymerization of less than 50 is used, the film forming property will be poor, the odor suppressing effect will be poor, and the hydrophilicity over time will also decrease. Furthermore, even if the degree of polymerization of polyvinylpyrrolidone exceeds 1000, good hydrophilicity is not maintained and the odor suppressing effect of the hydrophilic film is reduced. Preferably, the degree of polymerization n of polyvinylpyrrolidone is 80 to
600, more preferably 100-360.

[0014] When polyvinylpyrrolidone with a degree of polymerization of 50 to 1000 is used, appropriate film-forming properties can be obtained, and good hydrophilicity is maintained (hereinafter, the property of maintaining hydrophilicity is referred to as sustained hydrophilicity). . In order to achieve this, it is necessary to adjust the amount of polyvinylpyrrolidone in the hydrophilic surface treatment agent to 0.5 to 6 parts by weight in terms of solid content. If the amount is less than 0.5 parts by weight, the hydrophilicity will be deteriorated, and if the amount of polyvinylpyrrolidone is more than 6 parts by weight, the film forming property will be poor and odor problems will occur. The preferred content of polyvinylpyrrolidone is 0.6 to 4 parts by weight.

Next, the polyvinyl alcohol used in the present invention has the following general formula:

[Chemical formula 2] (In the above formula, m represents the number of saponified structural units, and n represents the number of unsaponified structural units.) It is at least partially saponified.

The degree of saponification of the polyvinyl alcohol represented by the above formula 2 must be 80% or more, and the degree of polymerization (m+n) must be 100 to 1000. Saponification degree is 80%
If the degree of polymerization is less than 1,000, or if the degree of polymerization exceeds 1000, the hydrophilicity will deteriorate and it is unsuitable. Also, the degree of polymerization is 1
If it is less than 00, film-forming properties and odor suppressing effects will deteriorate, which is not preferable. Preferably, the saponification degree is 90 or more and the polymerization degree is 200-600.

Saponification degree of 80% or more and polymerization degree of 100-1
000 polyvinyl alcohol has the effect of preventing odor and imparting hydrophilicity. In order to effectively exhibit this effect, the amount of polyvinyl alcohol in the hydrophilic surface treatment agent needs to be 1 to 10 parts by weight. If it is less than 1 part by weight, film forming properties will be reduced and the odor suppressing effect will be poor. On the other hand, if the amount exceeds 10 parts by weight, the hydrophilicity (represented by the contact angle of water) after immersion in running water decreases. The preferred content is 2
~5 parts by weight. In the present invention, the degree of saponification and degree of polymerization are in accordance with JIS K 6725, 5.2 and 5.4.
shall be measured in accordance with.

The hydrophilic surface treatment agent of the present invention contains the above-mentioned components (a) and (b) in the above-mentioned amounts, but the contents of the two components are not independent of each other and satisfy the relationship shown below. There is a need. As a result, the hydrophilic surface treatment agent of the present invention provides a film that is excellent in hydrophilicity and prevents odor. That is, the ratio (a)/[(a) + (b)] of the weight of component (a) to the total weight of components (a) and (b) is 0.1 to 0.9 in terms of solid content. within range. The above ratio is 0.1
If it is less than that, there will be no problem with odor or film-forming properties, but hydrophilicity will deteriorate. On the other hand, if this ratio exceeds 0.9, the hydrophilicity will be good, but problems will arise in terms of odor and film-forming properties. A more preferable range is 0.2 to 0.8.

The hydrophilic surface treatment agent of the present invention, in addition to the above-mentioned essential components (a) and (b), optionally contains a water-soluble polyamide resin, a water-soluble resin that can act as a crosslinking agent with a resin other than the water-soluble polyamide resin. , a surfactant, a fungicide, an antibacterial agent, water glass and/or colloidal silica to an extent that does not cause odor, a small amount of a solvent, etc. may be contained.

The water-soluble polyamide resin is water-soluble nylon, such as nylon-6, made soluble in water and/or alcohol, and has an average degree of polymerization of 50 to 30.
0, commercially available resins such as AQ-nylon, A-90
, A-70, P-70, etc. (all manufactured by Toray Industries, Inc.) can be suitably used.

Water-soluble nylon has the effect of imparting hydrophilicity. In order to effectively exhibit this effect, the content of water-soluble nylon in the hydrophilic surface treatment agent must be 0.
It is preferably 3 to 5 parts by weight. If it is less than 0.3 parts by weight, film-forming properties will be poor and hydrophilic sustainability will decrease. If it exceeds 5 parts by weight, odor problems will occur. A more preferable content is 0.5 to 3.0 parts by weight.

[0022] Water-soluble nylon is water-soluble itself, and its hydrophilic groups do not react during baking and drying after film formation, or even if they do, the extent of the reaction is small and the hydrophilicity is lost. It is a compound that never occurs. Such a compound has at least one of a hydroxyl group, an amino group, a secondary amine, a tertiary amine, and an alkanolamine. Here, the secondary amines include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine (cadaperine), hexamethylenediamine, 1,7-diaminoheptane, 1,8-
Diaminooctane, 1,9-diaminononane, 1,10
- Aliphatic amines such as diaminodecane, and aromatic amines such as o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine. Examples of tertiary amines include triethylamine, tripropylamine, tributylamine, and dimethylbenzylamine. Further, as the alkanolamine, ethanolamine, diethanolamine, triethanolamine, aminoethylethanolamine, morpholine, etc. are used.

As the water-soluble resin that can serve as a crosslinking agent, water-soluble amino resins, water-soluble phenol resins, and the like can be suitably used.

Examples of the water-soluble amino resin include water-soluble melamine resins such as n-butylated melamine resin and isobutylated melamine resin, benzoguanamine resin, and urea resin. These resins are usually melamine,
A compound obtained by subjecting an amino compound such as benzoguanamine to an addition reaction or an addition condensation reaction with an aldehyde such as formaldehyde or paraformaldehyde has 1 to 4 carbon atoms.
It is obtained by etherification with a monohydric alcohol. Specific examples of melamine resins include alkoxymethylmelamine resins in which the alkoxy group is a methoxy group, an ethoxy group, an n-butoxy group, an i-butoxy group, or the like. Preferably, methylated melamine resin can be used.

[0025] The water-soluble amino resin causes crosslinking between the resins, thereby improving film-forming properties. In order to effectively exhibit this effect, the content of water-soluble amino resin must be 0.1 to 5.
Parts by weight are preferred. If the amount is less than 0.1 part by weight, problems will arise in terms of film-forming properties and odor. On the other hand, if it exceeds 5 parts by weight, hydrophilicity decreases. A more preferable range is 0.5 to 2 parts by weight.

The water-soluble amino resin is also a compound that is itself water-soluble and does not lose its hydrophilicity because its hydrophilic groups do not substantially react during baking and drying after film formation. This water-soluble amino resin contains at least one of the secondary amines, tertiary amines, and alkanolamines described in the above-mentioned water-soluble nylon section, and may further contain a hydroxyl group.

Examples of water-soluble phenolic resins include those having a phenolic -OH group such as phenol, cresol, xylenol, p-alkylphenol, p-phenylphenol, chlorophenol, bisphenol A, phenolsulfonic acid, and resorcinol, formalin,
A water-soluble polymer obtained by adding and condensing aldehydes such as furfural can be used. These are generally classified as phenol/formalin, cresol/formalin, phenol/furfural, resorcinol resin, etc.

[0028] The water-soluble phenol resin forms crosslinks between resins and acts to improve film-forming properties. In order to effectively exhibit this effect, the content of water-soluble phenol resin must be reduced to 0.1
The amount is preferably 5 parts by weight. If the amount is less than 0.1 part by weight, problems will arise in terms of film-forming properties and odor. On the other hand, if it exceeds 5 parts by weight, hydrophilicity decreases. A more preferable range is 0.5 to 2 parts by weight.

Examples of surfactants include nonionic surfactants,
Any surfactant such as anionic, cationic, or amphoteric surfactants may be selected and used in consideration of workability such as stability, foaming properties, and coating properties of the processing liquid. Typical nonionic surfactants include polyoxyethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxypropylene glycol, polyoxyethylene alkyl phenyl ether, glycerin fatty acid partial ester, sorbitan fatty acid partial ester, Pentaerythritol fatty acid partial ester, polyoxyethylene sorbitan acid fatty acid partial ester, polyoxyethylene alkyl ether, and anionic active agents include dialkyl sulfosuccinate, alkanesulfonate, alkylbenzene sulfonate, and alkylnaphthalene sulfonate. Salt, polyoxyethylene alkyl sulfophenyl ether salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, fatty acid alkyl ester sulfate ester salt, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, fatty acid There are monoglyceride sulfate ester salts, cationic active agents include alkylamine salts and dialkylamine salts, and amphoteric active agents include N,N,N-trialkyl-N-sulfoalkylene ammonium betaine.

The amount of surfactant added is preferably 1.5 parts by weight or less, and if it exceeds 1.5 parts by weight, the water solubility will decrease.

[0031]Furthermore, as a fungicide and preservative, the fourth
Class ammonium salts, nitrogen-containing sulfur compounds, halogen-containing nitrogen-sulfur compounds, organic iodine compounds, benzimidazole compounds, and the like can be used. Specific examples of fungicides include 2-thiazol-4-ylbenzimidazole, methylbenzimidazol-2-ylcarbamate, and N-dichlorofluoromethylthio-N',N'-
Dimethyl-N-phenylsulfamide, tetramethylthiuram disulfide, N-(trichloromethylthio)-4-cyclohexene-1,2-dicarboximide, 2,4,5,6-tetrachloro-1,3-iso There are phthalonitrile, 2,3,5,6-tetrachloro-4-(methylsulfonyl) pyridine, bis(2-pyridylthio)-zinc-1,1-dioxide, etc., but considering heat resistance, 2 -thiazole-4- ylbenzimidazole, methylbenzimidazole-2-
ylcarbamate and 2,4,5,6-tetrachloro-1,3-isophthalonitrile, bis(2-pyridylthio)-zinc-1,1-dioxide are preferred.

[0032] Specifically, as an antibacterial agent, 1
, 2-benzisothiazolin-3-one (BIT),
2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine and 10,10'-oxybisphenoxyarsine are used.

[0033] The total amount of the antifungal agent and antibacterial agent added is preferably 0.1 to 2.0 parts by weight.

Further, in the present invention, further hydrophilicity can be exhibited by adding water glass and/or colloidal silica to an extent that does not cause odor generation. Water glass includes SiO2 /M2O (M is Li, Na and K), but SiO2 /K2O
is preferred. In addition, as colloidal silica, the particle size is 10~
The thickness is preferably 50 μm, and the amount added is preferably less than 1 part by weight.

Furthermore, in the present invention, a solvent can be added to further improve the wettability of the film surface. Alcohol-based and cellosolve-based solvents can be used as such solvents. The amount added is less than 7 parts by weight.

Hydrophilic Surface Treatment Bath The surface treatment bath of the present invention for forming a hydrophilic film on an aluminum material is produced by appropriately diluting the hydrophilic surface treatment agent described above. The composition of the surface treatment bath is as described above, and its concentration is such that a hydrophilic film of 0.5 to 2.5 g/m2 can be formed on the surface of the aluminum material by dipping, spraying, brushing, etc. The concentration should be as high as possible. The concentration of solid components in the surface treatment bath is adjusted to 10 to 200 g/liter, preferably 50 to 100 g/liter. If the components of the solution change during the painting process, add the appropriate components to maintain the initial composition.

Next, the surface treatment method of the present invention will be explained. Surface Treatment Method Before forming a film using a hydrophilic surface treatment agent, a chemical conversion treatment is first performed, but a degreasing treatment may be performed as a pretreatment for the chemical conversion treatment. Degreasing treatments include pickling using sulfuric acid or nitric acid, solvent degreasing using trichlorethylene, perchloroethylene, gasoline, n-hexane, etc., and alkaline solutions such as sodium hydroxide, sodium carbonate, sodium silicate, and sodium phosphate. Either alkaline degreasing may be performed.

After degreasing, a corrosion-resistant film is formed by chemical conversion treatment. Corrosion-resistant coatings can be obtained by chromate treatment. Chromate treatment is performed using a treatment solution prepared by adding additives to chromic anhydride, sulfuric acid, nitric acid, hydrofluoric acid, phosphoric acid, etc. There are phosphoric acid chromate systems that use phosphoric acid as the inorganic acid, and chromium chromate systems that use other acids. The chromate treatment can be carried out by dipping into a treatment liquid, spraying the treatment liquid, etc., but the dipping method is simple and preferable for complex-shaped heat exchanger fins. The corrosion-resistant film obtained by chromate treatment has a Cr content of 3
It is 0 to 250 mg/m2. The aluminum material on which the corrosion-resistant film has been formed is washed with water. Wash with tap water, etc.
This can be done by immersing for about 10 seconds to 10 minutes.

The hydrophilic surface treatment agent of the present invention is suitably diluted to form a surface treatment bath, and this is used to perform hydrophilic surface treatment on the above-described chromate-treated aluminum material via a chemical conversion treatment layer. Apply the agent. For this purpose, a roll coating method, a bar coating method, a dipping method, a spraying method, a brush coating method, etc. are possible, and the dipping method is preferable for products with complicated shapes such as the fins of a heat exchanger.

[0040] The present invention is applicable not only to a method of treating an aluminum material pre-formed into a fin shape or the like using the surface treatment bath of the present invention, but also to pre-coating.

[0041]

EXAMPLES The present invention will be explained in more detail with reference to the following examples. Examples 1 to 9, Comparative Examples 1 to 10 After degreasing the aluminum plate, Alsurf 407/47 (
Product name: Nippon Paint Co., Ltd.) was subjected to phosphoric acid chromate treatment by the dipping method, and the Cr content was 80 to 120.
A corrosion-resistant film of mg/m2 was formed. This chromate-treated aluminum plate was washed with running water for 20 seconds.

The plate subjected to the above treatment was immersed in a treatment solution having the composition shown in Table 1 for 1 minute at room temperature, and then immersed at 180°C for 2 minutes.
Each sample was obtained by drying for 0 minutes to form a hydrophilic film.

[0043]
Table 1 (Part 1)
Example 1 Example 2
Example 3 Example 4 (a) Component (1) Degree of polymerization 360
360 360 360
Weight% 3
3 3
3(b) Component (2) Saponification degree 90
90 90
90 Degree of polymerization 500
500 500 50
0 weight% 5
5 5
5 Water-soluble nylon (3) (wt%) −
1.5-
-Water-soluble resin (4) type-
- melamine
Urea weight%
- - 1
．． 0 1.0 Antifungal agent (5) (wt%) -
− −
- Antibacterial agent (6) (wt%) -
− −
−(a)/[(a) +(b)]
0.38 0.38
0.38 0.38

[0044]
Table 1 (Part 2)
Example 5 Example 6 Example 7
Example 8 Example 9 (a) Component (1) Degree of polymerization 360
360 108 360 360
Weight% 3
1 3
3 3(b) Component (2) Saponification degree 90
90 90 90
90 Degree of polymerization 50
0 500 500 500
500% by weight
5 10 5
5 5 Water-soluble nylon (3)


(weight%) −
- - 1.5
1.5 Water-soluble resin (4)

Type Ph resin Melamine - Ph resin Ph
Resin weight%
1.0 1.0 -
1.0 1.0 Antifungal agent (5)
(weight%) −
− − −
0.3 Antibacterial agent (6)


(weight%) −
− − −
0.1(a)/[(a) +(b)]
0.38 0.1
0.38 0.38 0.3
8

[0045]
Table 1 (Part 3)
Comparative example 1 Comparative example 2 Comparative example 3
Comparative Example 4 Comparative Example 5 (a) Component (1) Degree of polymerization 360
- 360 360 3
60% by weight
3-7.1
0.05 6.5(b) Component (2) Saponification degree -
90 90 90
90 Degree of polymerization
- 500 500 500
500% by weight
-10 0.6
11 1.2 Water-soluble nylon (
3)

(weight%) −
− −
- - Water-soluble resin (4)


Type −
− − −
Melamine weight%
− −
− − 1.0 Antifungal agent (5) (wt%) −
− − −
- Antibacterial agent (6)

− (weight%) − −
− −
0.1(a)/[(a) +(b)]
1.0 0 0.92
0.01 0.84

[0046]
Table 1 (Part 4)
Comparative example 6 Comparative example 7 Comparative example 8 Comparative example 9 Comparative example 10 (a) Component (1) Degree of polymerization 26
6000 360 360
360% by weight
3 3 3
3 7.1(b) Component (2) Saponification degree 90
90 30 60
90 Degree of polymerization 50
0 500 500 200
500% by weight
5 5 5
5 0.6 Water-soluble nylon (
3)

(weight%) −
− −
- 1.5 Water-soluble resin (4)


Type −
− − −
Ph resin weight%
− −
− − 1.0 Antifungal agent (5) (wt%) −
− − −
- Antibacterial agent (6)


(weight%) −
− − −
−(a)/[(a) +(b)]
0.38 0.38 0.3
8 0.38 0.92

004
7] Table 1 Note (1): All were polyvinylpyrrolidone manufactured by BASF, and the following were used. Degree of polymerization 26: Rubiscoll K-12 Degree of polymerization 1
08: Rubiscoll K-17 Degree of polymerization 360: Rubiscoll K-30 Degree of polymerization 6000: Rubiscoll
K-90 (2): All are polyvinyl alcohols manufactured by Shin-Etsu Chemical Co., Ltd., and the following were used. (Saponification degree) (Polymerization degree) 90 500: SMR-30H
H60 200: SMR-10
M30 500: SMR-20
L (3): Manufactured by Toray Industries, Inc., AQ nylon P-70
, average degree of polymerization about 100 (4): "Melamine" in the table is water-soluble methylated melamine, manufactured by Sanwa Chemical Co., Ltd., Nikalac MX-0
It is 54. "Urea" in the table is a water-soluble urea resin,
Abond UL-3201S manufactured by Gunei Chemical Industry Co., Ltd. "Ph resin" in the table is a water-soluble phenol resin, and is Hytanol 4500 manufactured by Hitachi Chemical Co., Ltd. (5) : Manufactured by Takeda Pharmaceutical Co., Ltd., Courtside 55D
. (6) : Manufactured by Takeda Pharmaceutical Co., Ltd., Suraoff 72N
. (7): Weight ratio of (a) polyvinylpyrrolidone to the total amount of (a) polyvinylpyrrolidone and (b) polyvinyl alcohol.

[0048] Each of the obtained hydrophilic films was subjected to an odor test, a hydrophilicity test (hydrophilicity sustainability test using a water contact angle test), a water solubility test, an adhesion test, and a mold resistance test as described below. .

(1) Odor test An odor test was conducted by directly smelling each hydrophilic film-formed aluminum plate (hereinafter simply referred to as a sample). The evaluation criteria are as follows. ◎: No odor at all ○: Almost no odor △: Obvious odor ×: Strong odor

(2) Hydrophilicity sustainability test (water contact angle test)
As a hydrophilicity durability test, hydrophilicity over time was evaluated by measuring the contact angle of water droplets in the manner described below. Each sample was immersed in running tap water (water flow rate: 5 liters/min) for 480 hours, and then the water contact angle was measured for the hydrophilic film that was dried at 80° C. for 10 minutes. To measure the water contact angle, hold the sample horizontally and drop 5 microliters of pure water onto it.
Measurement was performed using an automatic contact angle meter (CA-Z: manufactured by Kyowa Interface Science Co., Ltd.). The evaluation criteria for contact angle are as follows. Contact angle ◎: Less than 20° ○: 20° or more and less than 30° △: 30° or more and less than 40° ×: 40° or more

(3) Water Solubility Each sample was immersed in tap water for 24 hours, and the water solubility rate was determined from the amount of film before and after immersion using the following formula. Water dissolution rate = [(Initial film amount - Film amount after 24 hours immersion)
÷Initial film amount]×100 The evaluation criteria for water-resistant solubility are as follows. Water solubility ◎: Less than 10% ○: 10% or more and less than 30% △: 30% or more and less than 50% ×: 50% or more

(4) Adhesion test Vertical test (100 pieces (10 pieces x 10 pieces)/1m
m-th) and was evaluated in the following 5 stages based on the number of remaining frames. ◎: 100 ○: 90-99 △: 80-89 ×: 70-79 XX: Less than 70

(5) Mildew resistance test After immersing samples cut into 3 cm x 3 cm pieces in running water for 250 hours, each test piece was sprayed with a mixed spore suspension of the following 4 bacterial species as test bacteria, and heated to 27°C. Tested using an exposure method (JIS
-Z-2911) and evaluated based on the following criteria.

Test fungus Aspergillus niger I
FO 4414 Penicillium funicl
osum IFO 6345 Cladosporiu
m cladosporioides IFO 634
8Aureobasidium pullulans
IFO 6353◎: No mold growth is observed on the sample surface with the naked eye. ○: Slight growth of mold is observed on the sample surface with the naked eye. △: Approximately 1/3 of mold growth is observed on the sample surface with the naked eye. ×: Approximately 2/3 of mold growth was observed on the sample surface with the naked eye. XX: Mold growth is observed all over the sample surface with the naked eye. The results of tests (1) to (5) are shown in Table 2.

[0055]
Table 2 Example No. odor
Hydrophilicity Sustainability Water Solubility Resistance Adhesion
Mildew resistance Example 1 ◎
◎ ○
◎ -Example 2 ◎
○ ○
◎ -Example 3
○ ◎
◎ ◎
-Example 4 ○ ◎
◎ ◎
-Example 5 ◎
◎ ◎
◎ -Example 6
○ ○ ○
◎ −Example 7 ◎ ◎
○ ◎
-Example 8 ◎
◎ ◎ ◎
-Example 9 ◎
◎ ◎
◎ ◎Comparative example 1
○ △
△ × −
Comparative example 2 ○ ×
× ×
-Comparative example 3 ○
△ △
× - Comparative example 4 ○
× ×
× - Comparative example 5
○ △
◎ ◎
△Comparative example 6 ○ ◎
△ ○
-Comparative example 7 △
○ ○
○ - Comparative example 8
◎ ○
△ ○ - Comparative Example 9 ◎ ○
× ○
-Comparative example 10 △
◎ ◎
◎ −

[0056]

Effects of the Invention As described above, the hydrophilic film formed using the hydrophilic surface treatment agent of the present invention not only has good hydrophilicity and water solubility resistance, but also has significantly suppressed odor, and has excellent adhesion and water resistance. It has good mold resistance and is suitable for hydrophilic treatment of aluminum fin materials for heat exchangers, etc.

Claims (3)

[Claims] [Claim 1] In terms of solid content, (a) degree of polymerization is 50
0.5 to 6 parts by weight of polyvinylpyrrolidone of ~1000, and (b) a degree of saponification of 80% or more and a degree of polymerization of 100 to
1000 polyvinyl alcohol, and the weight ratio of component (a) to the total amount of component (a) and component (b) is (a)/[(a) +
(b) ] is in the range of 0.1 to 0.9. [Claim 2] In terms of solid content, (a) degree of polymerization is 50
0.5 to 6 parts by weight of polyvinylpyrrolidone of ~1000, and (b) a degree of saponification of 80% or more and a degree of polymerization of 100 to
1000 polyvinyl alcohol, and the weight ratio of component (a) to the total amount of component (a) and component (b) is (a)/[(a) +
(b) A hydrophilic surface treatment bath characterized by containing a hydrophilic surface treatment agent having a value of 0.1 to 0.9 in a concentration of 10 to 200 g/liter. [Claim 3] The object to be coated is (1) subjected to a chemical conversion treatment, and (2) then, in terms of solid content, (a) the degree of polymerization is 5.
0 to 1000 polyvinylpyrrolidone (0.5 to 6 parts by weight), and (b) a degree of saponification of 80% or more and a degree of polymerization of 100%.
~1000 polyvinyl alcohol, and the weight ratio of component (a) to the total amount of component (a) and component (b) is (a)/[(a) + (b).
)] is in the range of 0.1 to 0.9.