JPH05302042A - Hydrophilic surface treating agent for aluminum heat exchanger and treatment therewith - Google Patents

Abstract

(57) [Summary] [Structure] (a) Polyvinyl alcohol having a specific degree of saponification and a specific degree of polymerization, (b) a mixture of polyvinylpyrrolidone having a low degree of polymerization and polyvinylpyrrolidone having a high degree of polymerization, and (c) ) A water-soluble nylon, (d) a water-soluble phenolic resin, (e) a nonionic surfactant, and (f) a hydrophilizing agent containing a specific antibacterial agent as essential components. [Effect] It becomes possible to impart corrosion resistance and good hydrophilicity to an aluminum material such as an aluminum fin of a heat exchanger, and at the same time, to form a film that suppresses generation of unpleasant odor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrophilic surface-treating agent used for aluminum heat exchanger materials and a surface treatment method using the same, and more particularly to aluminum fins of aluminum heat exchangers. The present invention relates to a hydrophilic surface treating agent which has corrosion resistance and hydrophilicity and can form a film in which odor generated from a heat exchanger is suppressed, and a surface treating method using the same.

[0002]

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

During the cooling operation of the air conditioner, water in the air tends to adhere to the fin surface as condensed water. In order to prevent this, it is possible to make the fin surface water repellent, but then the condensed water will adhere to the fins in a hemispherical shape or will exist in a bridge shape between the fins, and the smooth flow of air will occur. To prevent ventilation and increase ventilation resistance. In this way, making the fin surface water-repellent decreases the heat exchange efficiency.

By the way, aluminum and its alloys are originally excellent in corrosion resistance, but when condensed water stays on the fin surface for a long period of time, an oxygen concentration cell is formed or pollutants in the atmosphere are gradually attached and concentrated to cause a hydration reaction. And the corrosion reaction is accelerated. This corrosion product is, of course, deposited on the surface of the fin and impairs the heat exchange characteristics, but during heating operation in winter, it becomes white fine powder and is discharged together with warm air by the blower.

Therefore, in order to improve these problems,
Various attempts have been made to form a film having both of the above-mentioned two properties on the fin surface for the purpose of improving the corrosion resistance of the fin as well as increasing the hydrophilicity of the surface.

For example, JP-A-55-12375 and JP-A-56-12
-56572 discloses an evaporator having a fin coated with a synthetic resin film having a hydrophilic amide group. Soluble nylon, for example, is used as the film of the synthetic resin having a hydrophilic amide group. Further, Japanese Patent Laid-Open No. 61-250495 discloses an aluminum fin in which a resin film made of an organic polymer material such as a water-soluble polyamide resin which exhibits a cation property in an aqueous solution is formed on the chemical conversion film. Further, JP-A-63-57674 discloses a hydrophilic film forming treatment agent containing a water-soluble resin such as water-soluble nylon, an alkali metal silicate, and an amino alcohol. Furthermore, JP-A-62-132970 discloses (a) an addition reaction product of at least one member selected from the group consisting of urea, thiourea, and guanidine and (b) formalin, or a condensation product of this addition reaction product. In addition, a surface treating agent for heat exchanger fins containing water-soluble nylon is disclosed, and JP-A-62-176578 discloses a treating method using the treating agent. Further, JP-A-2-102277 discloses a metal surface containing (a) a block copolymer comprising a hydrophilic monomer and a vinyl-type monomer having a cross-linking functional group, and (b) a surfactant. A coating composition is disclosed and vinylpyrrolidone is mentioned as one of the hydrophilic monomers.

[0007]

However, both the hydrophilicity and the odor suppressing (preventing) effect cannot be sufficiently satisfied by the surface treating method using each of the above coatings or treating agents. Further, an aluminum heat exchanger designed to suppress the generation of microorganisms in the condensed water on the surface of the heat exchanger and remove the offensive odor caused by the microorganisms (JP-A-60-50397).
No.), but it is not sufficient in terms of hydrophilicity and odor control effect. As described above, the conventional surface treatment technology cannot form a odorless coating on an aluminum heat exchanger material while having sufficient hydrophilicity and corrosion resistance, good membrane strength. Therefore, the object of the present invention, on the surface of the fin material or the like of the heat exchanger, hydrophilicity, corrosion resistance, good water solubility and the like, and a surface treatment agent for forming a hydrophilic film that does not generate an unpleasant odor, and It is to provide a surface treatment method using this.

[0008]

As a result of intensive studies to achieve the above object, the present inventors have found that polyvinyl alcohol having a specific degree of saponification and degree of polymerization, polyvinyl pyrrolidone having a low degree of polymerization and high A mixture of polyvinylpyrrolidone having a degree of polymerization in a specific ratio, water-soluble nylon, a water-soluble phenolic resin, a nonionic surfactant, and a specific antibacterial agent are blended in specific amounts, respectively, to make them hydrophilic. The present invention has been completed by discovering that it is possible to form a hydrophilic film that has good corrosion resistance and at the same time does not generate an unpleasant odor.

That is, the hydrophilic surface treating agent of the present invention for an aluminum heat exchanger is (a) polyvinyl alcohol 40 to 60 having a saponification degree of 98% or more and a polymerization degree of 150 to 350 in terms of solid content. Parts by weight, and (b) the degree of polymerization is 15 to
Polyvinylpyrrolidone of 40 and a degree of polymerization of 100 to 30
0 with polyvinylpyrrolidone of 0: 1.5-
1: 3.0, and a total of 20 to 40 parts by weight, (c) 10 to 20 parts by weight of water-soluble nylon, and (d) 2 to 12 parts by weight of water-soluble phenolic resin. And (e) 1 to 10 parts by weight of the nonionic surfactant with respect to 100 parts by weight of the water-soluble resin, and (f) bis (2-
Pyridylthio) -zinc-1,1-dioxide is contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the water-soluble resin.

In the hydrophilic surface treatment method of the present invention, the aluminum heat exchanger substrate is subjected to (1) chemical conversion treatment, and (2) in terms of solid content, (a) saponification degree. Is 98% or more and the degree of polymerization is 150 to 350. Polyvinyl alcohol 4
0 to 60 parts by weight, (b) a polyvinylpyrrolidone having a polymerization degree of 15 to 40, and a polyvinylpyrrolidone having a polymerization degree of 100 to 300 are used in a weight ratio of 1: 1.5 to 1: 3.0. A total of 20 to 40 parts by weight, (c) 10 to 20 parts by weight of water-soluble nylon, (d) 2 to 12 parts by weight of water-soluble phenolic resin, and (e) a nonionic resin 1 to 10 parts by weight of a surfactant based on 100 parts by weight of the water-soluble resin, and (f) bis (2-pyridylthio) -zinc-1,1-dioxide based on 100 parts by weight of the water-soluble resin. The surface treatment is performed using a hydrophilizing surface treatment bath containing 5 to 20 parts by weight.

The present invention will be described in detail below. Hydrophilic surface treatment agent The hydrophilic surface treatment agent of the present invention comprises (a) polyvinyl alcohol, (b) two types of polyvinylpyrrolidone having different polymerization degrees, (c) water-soluble nylon, and (d) water-soluble phenol. It contains a resin, (e) a nonionic surfactant, and (f) a specific antibacterial agent.

First, the polyvinyl alcohol used as the component (a) in the present invention has the following general formula:

[Chemical 1] (In the above formula, m represents the number of constitutional units that have been saponified, and n represents the number of constitutional units that have not been saponified.) It is saponified.

The degree of saponification of the polyvinyl alcohol represented by the above chemical formula 1 must be 98% or more, and the degree of polymerization (m + n) must be 150 to 350. If the degree of saponification is less than 98% or the degree of polymerization exceeds 350, the hydrophilicity is deteriorated, which is not suitable. The degree of polymerization is 150
If it is less than the above, the film-forming property and the odor suppressing effect are deteriorated. The preferred degree of polymerization is 200 to 300.

A saponification degree of 98% or more and a polymerization degree of 150 to 3
Polyvinyl alcohol of 50 has the function of imparting odor prevention and hydrophilicity. In order to effectively exhibit this effect, the amount of polyvinyl alcohol in the hydrophilic surface treating agent needs to be 40 to 60 parts by weight. If it is less than 40 parts by weight, the film-forming property is deteriorated and the odor control effect is poor. On the other hand, 60
If the amount is more than parts by weight, the hydrophilic durability (represented by the contact angle of water) after immersion in running water is reduced. In the present invention, the saponification degree and the polymerization degree are measured according to JIS K 6725, 5.2 and 5.4.

Next, the polyvinylpyrrolidone of the component (b) used in the present invention has the following general formula:

[Chemical 2] (Wherein n represents the degree of polymerization), and is obtained by polymerizing N-vinyl-2-pyrrolidone.

In the present invention, two types of polyvinylpyrrolidone are used in combination, that is, polyvinylpyrrolidone having a low degree of polymerization and polyvinylpyrrolidone having a high degree of polymerization. The degree of polymerization n of polyvinylpyrrolidone having a low degree of polymerization is 15 to 40, and the degree of polymerization n of polyvinylpyrrolidone having a high degree of polymerization is 100 to 300.

When polyvinylpyrrolidone having a low degree of polymerization and polyvinylpyrrolidone having a high degree of polymerization are used in combination, the film-forming property and the hydrophilicity with time become better than those obtained by using one kind of polyvinylpyrrolidone. The mechanism of this action is not always clear, but by using two types of polyvinylpyrrolidone having different degrees of polymerization in combination, during the reaction curing, the polyvinylpyrrolidone having a low degree of polymerization is preferentially crosslinked to improve the film-forming property. Therefore, it is considered that the contribution of the high degree of polymerization polyvinylpyrrolidone to the cross-linking is alleviated, and as a result, the hydrophilicity is improved. If the degree of polymerization of the two types of polyvinylpyrrolidone does not fall within the ranges described above, either the film-forming property or the hydrophilic property over time will be poor.

The total amount of polyvinylpyrrolidone having a low degree of polymerization and a high degree of polymerization is calculated in terms of solid content in the hydrophilic surface treating agent.
It should be 20-40 parts by weight. When the amount is less than 20 parts by weight, the hydrophilicity is lowered, and when the amount exceeds 40 parts by weight, polyvinylpyrrolidone is inferior in film forming property, and an odor problem occurs. The preferred content is 25 to 35 parts by weight.

The blending ratio of low polymerization degree polyvinylpyrrolidone and high polymerization degree polyvinylpyrrolidone must be 1: 1.5 to 1: 3.0 by weight. When the ratio of polyvinylpyrrolidone having a high degree of polymerization (to polyvinylpyrrolidone having a low degree of polymerization) is less than 1.5, the hydrophilicity with time decreases. On the other hand, if this ratio exceeds 3.0, the film-forming property deteriorates. It is preferably 1: 2 to 1: 2.5.

The water-soluble nylon as the component (c) is, for example, nylon-6 made soluble in water and / or alcohol.

Water-soluble nylon has an average degree of polymerization of
It is preferable to use one of 50 to 300. Specifically, AQ
-Nylon A-90, A-70, P-70 (all manufactured by Toray Industries, Inc.) and the like can be preferably used.

The water-soluble nylon has a function of imparting hydrophilicity. In order to effectively exhibit this effect, the content of water-soluble nylon in the hydrophilized surface treatment agent should be 10
Must be ~ 20 parts by weight. If it is less than 10 parts by weight, the film-forming property is poor and the hydrophilicity retention is deteriorated. If it exceeds 20 parts by weight, an odor problem occurs. The preferred content is 12 to 18 parts by weight.

The water-soluble phenolic resin as the component (d) has a phenolic-OH group such as phenol, cresol, xylenol, p-alkylphenol, p-phenylphenol, chlorophenol, bisphenol A, phenolsulfonic acid and resorcin. To something
Add aldehydes such as formalin and furfural,
It is possible to use a water-soluble product of a condensed polymer. These are generally classified as phenol / formalin, cresol / formalin, phenol / furfural, resorcin resin and the like.

The water-soluble phenol resin forms cross-links between the resins and acts to improve the film forming property. In order to exert this effect effectively, the content of the water-soluble phenol resin should be 2
Must be ~ 12 parts by weight. When it is less than 2 parts by weight,
Problems arise in terms of film-forming property and odor. on the other hand,
If it exceeds 12 parts by weight, the hydrophilicity will decrease. The preferred range is 4 to 10 parts by weight.

As the surface active agent of the component (e), a nonionic type is used in consideration of workability such as stability of the processing liquid, foaming property and coating property. Typical nonionic surfactants include polyoxyethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxypropylene glycol, polyoxyethylene alkylphenyl ether, glycerin fatty acid partial ester, sorbitan fatty acid partial ester, pentaerythritol fatty acid. There are partial esters, polyoxyethylene sorbitan acid fatty partial esters, and polyoxyethylene alkyl ethers.

The amount of the surfactant added is 1 part with respect to 100 parts by weight of the solid content of the water-soluble resin (the total of the above components (a) to (d)).
~ 10 parts by weight. If it is less than 1 part by weight, the hydrophilicity will decrease,
If it exceeds 10 parts by weight, the water solubility of the formed film is lowered. A preferred range is 3 to 7 parts by weight.

Further, in the present invention, an antibacterial agent is added as the component (f). As an antibacterial agent, bis (2-pyridylthio)-
Zinc-1,1-dioxide is used. Bis (2-pyridylthio) -zinc-1,1-dioxide has good heat resistance, and has good antifungal and antibacterial properties. In addition to bis (2-pyridylthio) -zinc-1,1-dioxide, quaternary ammonium salts, nitrogen-containing sulfur compounds, halogen-containing nitrogen-sulfur compounds, organic iodine compounds, benzimidazole compounds, etc. are used in combination. can do.

The antibacterial agent is added in an amount of 5 parts by weight based on 100 parts by weight of the solid content of the water-soluble resin (total of the above components (a) to (d)).
~ 20 parts by weight. If it is less than 5 parts by weight, the antifungal effect is not sufficient, and if it exceeds 20 parts by weight, the performance of the hydrophilic coating may deteriorate. Even if the antibacterial agent is added in an amount of more than 20 parts by weight, the antibacterial property is not improved corresponding to the added amount, which is not economical. The preferred addition amount is 7-
15 parts by weight.

Further, in the present invention, an alcohol solvent and / or a cellosolve solvent can be added in order to further improve the wettability of the film surface. The amount of such a solvent added is less than 7 parts by weight.

Hydrophilic surface treatment bath The surface treatment bath for forming a hydrophilic film on an aluminum material is
The hydrophilic surface treating agent is appropriately diluted before use. The concentration is such that a hydrophilic film of 0.5 to 2.5 g / m ² can be formed on the surface of the aluminum material by a dipping method, a spray method, a brush coating method or the like. When the dipping method is used, the concentration of solid components in the surface treatment bath should be 10 in consideration of the distance between the fins and the film burrs caused by the resin.
It is preferable to adjust it to be ~ 200 g / liter.
More preferably, it is 30 to 100 g / liter. If the composition of the solution changes during the painting operation, the composition of the composition is appropriately added to maintain the initial composition.

Next, the surface treatment method of the present invention will be described. Surface Treatment Method Before forming a film with a hydrophilic surface treating agent, first, a chemical conversion treatment is performed, but a degreasing treatment may be performed as a pretreatment for the chemical conversion treatment. As the degreasing treatment, pickling treatment using sulfuric acid or nitric acid, solvent degreasing with trichloroethylene, perchlorethylene, gasoline, normal hexane, etc., and alkali solution such as sodium hydroxide, sodium carbonate, sodium silicate, sodium phosphate, etc. Either alkaline degreasing may be performed.

After degreasing, a corrosion resistant film is formed by chemical conversion treatment. The corrosion resistant film can be obtained by a chromate treatment. The chromate treatment is performed with a treatment liquid prepared by adding additives to chromic anhydride, sulfuric acid, nitric acid, hydrofluoric acid, phosphoric acid and the like. There are a phosphoric acid chromate system that uses phosphoric acid as an inorganic acid, and a chromium chromate system that uses another acid. The chromate treatment can be carried out by dipping in the treatment liquid, spraying the treatment liquid, or the like, but the dipping method is simple and preferable for fins of a heat exchanger having a complicated shape.
Corrosion resistant coating obtained by chromate treatment has a Cr content of 30-
It is preferably 250 mg / m ² . The aluminum material on which the corrosion resistant film is formed is washed with water. Washing with tap water for 10 seconds ~
It can be performed by soaking for about 10 minutes.

The above-described hydrophilizing surface treating agent of the present invention is appropriately diluted to form a surface treating bath, which is used to hydrophilize the chromate-treated aluminum material described above through a chemical conversion treatment layer. Apply the surface treatment agent. For this, a roll coating method, a bar coating method, a dipping method, a spraying method, a brush coating method and the like can be used, but the dipping method is preferable for a fin having a complicated shape such as a heat exchanger.

[0034]

The present invention will be described in more detail by the following examples. Examples 1-5, Comparative Examples 1-19 After degreasing aluminum plates, Alsurf 407/47 (trade name:
Using Nippon Paint Co., Ltd., a phosphoric acid chromate treatment was performed by a dipping method to form a corrosion resistant film having a Cr content of 80 to 120 mg / m ² . The chromated aluminum plate was washed with running water for 20 seconds.

A treating agent having the composition shown in Table 1 was prepared and appropriately diluted with water so that the solid content concentration was 5% by weight to obtain a treating solution. The chromate-treated aluminum plate was immersed in this treatment solution for 1 minute at room temperature, and then at 180 ° C for 20 minutes.
Each sample was obtained by drying for a minute to form a hydrophilic film.

Table 1 (Part 1) Example 1 Example 2 Example 3 Example 4 Example 5 (a) Component ⁽¹⁾ degree of polymerization 230 230 230 230 230 degree of saponification 98 98 98 98 98 wt% 50 40 60 50 40 (b) Component ⁽²⁾ Degree of polymerization (low / high) ⁽³⁾ 26/108 26/108 26/108 26/108 26/108 Weight% (low / high) ⁽⁴⁾ 10/20 13 / 27 8/17 6/14 13/27 Low / High ratio ⁽⁵⁾ 1/2 1 / 2.1 1 / 2.1 1 / 2.3 1 / 2.1 (c) Component ⁽⁶⁾ wt% 15 15 10 20 15 (d) Component ⁽⁷⁾ wt% 5 5 5 10 5 (e) component ⁽⁸⁾ parts by weight ⁽⁹⁾ 5 5 5 5 5 (f) component ⁽¹⁰⁾ parts by weight ⁽⁹⁾ 10 10 10 10 10

Table 1 (No. 2) Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 (a) Component ⁽¹⁾ Polymerization degree 500 120 200 230 230 Saponification degree 98 98 60 98 98 wt% 50 50 50 30 68 (b) Component ⁽²⁾ Degree of polymerization (low / high) ⁽³⁾ 26/108 26/108 26/108 26/108 26/108 Weight% (low / high) ⁽⁴⁾ 10/20 10 / 20 10/20 13/27 6/14 Low / High ratio ⁽⁵⁾ 1/2 1/2 1/2 1 / 2.1 1 / 2.3 (c) Component ⁽⁶⁾ wt% 15 15 15 20 10 (d) Component ⁽⁷⁾ Weight% 5 5 5 10 2 (e) Component ⁽⁸⁾ parts by weight ⁽⁹⁾ 5 5 5 5 5 (f) Component ⁽¹⁰⁾ parts by weight ⁽⁹⁾ 10 10 10 10 10

Table 1 (No. 3) Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 (a) Component ⁽¹⁾ Polymerization degree 230 230 230 230 230 Saponification degree 98 98 98 98 98 wt% 50 50 40 60 50 (b) Component ⁽²⁾ Degree of polymerization (low / high) ⁽³⁾ 0/108 26/0 26/108 26/108 26/108 Weight% (low / high) ⁽⁴⁾ 0/30 30 / 0 16/32 3/7 13/27 Low / high ratio ⁽⁵⁾ − − 1/2 1 / 2.3 1 / 2.1 (c) Component ⁽⁶⁾ wt% 15 15 10 20 0 (d) Component ⁽⁷⁾ wt % 5 5 2 10 10 (e) Component ⁽⁸⁾ parts by weight ⁽⁹⁾ 5 5 5 5 5 (f) Component ⁽¹⁰⁾ parts by weight ⁽⁹⁾ 10 10 10 10 10

Table 1 (Part 4) Comparative Example 11 Comparative Example 12 Comparative Example 13 Comparative Example 14 Comparative Example 15 (a) Component ⁽¹⁾ Polymerization degree 230 230 230 230 230 Saponification degree 98 98 98 98 98 wt% 45 55 45 50 50 (b) Component ⁽²⁾ Degree of polymerization (low / high) ⁽³⁾ 26/108 26/108 26/108 26/108 26/108 Weight% (low / high) ⁽⁴⁾ 6/14 10 / 20 10/20 10/20 10/20 Low / High ratio ⁽⁵⁾ 1 / 2.3 1/2 1/2 1/2 1/2 (c) Component ⁽⁶⁾ Weight% 30 15 10 15 15 (d) Component ⁽⁷⁾ Weight% 5 0 15 5 5 (e) Component ⁽⁸⁾ parts by weight ⁽⁹⁾ 5 5 5 5 5 (f) Component ⁽¹⁰⁾ parts by weight ⁽⁹⁾ 10 10 10 0 30

Table 1 (Part 5) Comparative Example 16 Comparative Example 17 Comparative Example 18 Comparative Example 19 (a) Component ⁽¹⁾ Degree of polymerization 230 230 230 230 Saponification degree 98 98 98 98% by weight 50 50 50 50 (b) Ingredient ⁽²⁾ Degree of polymerization (low / high) ⁽³⁾ 26/108 26/108 26/108 26/108 wt% (low / high) ⁽⁴⁾ 10/20 10/20 15/15 6/24 Low / High ratio ⁽⁵⁾ 1/2 1/2 1/1 1/4 (c) Component ⁽⁶⁾ wt% 15 15 15 15 (d) Component ⁽⁷⁾ wt% 5 5 5 5 (e) Component ⁽⁸⁾ Parts by weight ⁽⁹⁾ 0 20 5 5 (f) Component ⁽¹⁰⁾ Parts by weight ⁽⁹⁾ 10 10 10 10

Table 1 Note (1): All are Shin-Etsu Chemical Co., Ltd.
The polyvinyl alcohol manufactured was the following. (Degree of Saponification) (Degree of Polymerization) 98 120: SMR-5HH 98 230: SMR-10HH 98 500: SMR-30HH 60 200: SMR-10M (2): Polyvinylpyrrolidone manufactured by BASF Co., Ltd. I used one. Degree of polymerization 26: Rubiscol K-12 Degree of polymerization 108: Rubiscol K-17 (3): Degree of polymerization of polyvinylpyrrolidone of low degree of polymerization and polyvinylpyrrolidone of high degree of polymerization (low degree of polymerization / high degree of polymerization) Stuff). (4): The blending amounts (% by weight) of low polymerization degree polyvinylpyrrolidone and high polymerization degree polyvinylpyrrolidone are shown in the order of (low polymerization degree / high polymerization degree). (5): A compounding ratio (weight ratio) of polyvinylpyrrolidone having a low degree of polymerization and polyvinylpyrrolidone having a high degree of polymerization. (6): AQ nylon A-90 manufactured by Toray Industries, Inc., average degree of polymerization of about 100. (7): It is a water-soluble phenolic resin and is Hitachin 4500 manufactured by Hitachi Chemical Co., Ltd. (8): Polyoxyethylene glycol. (9): Total 100 parts by weight of components (a) to (d) (solid content conversion)
Is the compounding amount. (10): Bis (2-pyridylthio) -zinc-1,1-dioxide.

Each of the obtained hydrophilic coatings was subjected to an odor test, a hydrophilicity test (hydrophilic persistence test by a water contact angle test), a water solubility test, an adhesion test and a mildew proof test as follows. ..

(1) Odor Test An odor test was conducted by directly sniffing 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 △: Clearly odor ×: Strong odor

(2) Hydrophilic persistence test (water contact angle test) In the hydrophilic continuity test, the hydrophilicity over time was evaluated by measuring the contact angle of a water drop according to the following procedure.

Each sample was tap water (flow rate 5 liters /
Min) was immersed in running water for 480 hours, and then the water contact angle was measured for the hydrophilic film dried at 80 ° C. for 10 minutes. The water contact angle was measured by leveling the sample, dropping 5 microliters of pure water on it, and measuring with an automatic contact angle meter (CA-Z: manufactured by Kyowa Interface Science Co., Ltd.). The evaluation standard of the contact angle is 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 Resistance Each sample was immersed in tap water for 24 hours, and the water dissolution rate was calculated from the amount of the film before and after immersion by the following formula.

Water dissolution rate = [(initial amount of film−amount of film after immersion for 24 hours) / initial amount of film] × 100 The evaluation criteria for water solubility are as follows. Water dissolution rate ◎: Less than 10% ○: 10% or more and less than 30% △: 30% or more and less than 50% ×: 50% or more

(4) Adhesion Test A goggle eye test (100 pieces (10 pieces × 10 pieces) / 1 mm-thickness) was performed, and the number of remaining frames was evaluated in the following five grades. ◎: 100 ○: 90 to 99 △: 80 to 89 ×: 70 to 79 × ×: less than 70

(5) Antifungal test A sample cut into a size of 3 cm x 3 cm was immersed in running water for 250 hours, and each test piece was sprayed with a mixed spore suspension of the following four bacterial species as a test bacterium, at 27 ° C. Tested by the exposure method that observes the degree of reproduction of mold after culturing for 7 days (according to JIS-Z-2911)
Then, the following criteria were evaluated.

Test bacterium Aspergillus niger IFO 4414 Penicillium funiclosum IFO 6345 Cladosporium cladosporioides IFO 6348 Aureobasidium pullulans IFO 6353 ⊚: No reproduction of mold on the sample surface with the naked eye. ○: The reproduction of mold is slightly recognized on the sample surface with the naked eye. △: Reproduction of mold on the surface of the sample is about 1/3 with the naked eye. ×: About 2/3 of mold reproduction was observed on the sample surface with the naked eye. XX: Reproduction of mold on the entire surface of the sample with the naked eye. The results of tests (1) to (5) are shown in Table 2.

Table 2 Example No. Odor Hydrophilic Persistence Water Solubility Adhesion Adhesion Antifungal Example 1 ◎ ◎ ◎ ◎ ◎ ◎ Example 2 ◎ ◎ ◎ ◎ ◎ ◎ Example 3 ◎ ◎ ◎ ◎ ◎ ◎ Example 4 ◎ ◎ ◎ ◎ ◎ ◎ Example 5 ◎ ◎ ◎ ◎ ◎ ◎ 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 ○ △ ○ ◎ ◎ ◎ Comparative Example 11 ○ △ ○ ◎ ○ Comparative Example 12 △ △ △ △ △ Comparative Example 13 ○ × ◎ ◎ ○ Comparative Example 14 ◎ ◎ ◎ ◎ ◎ × Comparative Example 15 ◎ △ ○ ○ ◎ Comparative Example 16 ◎ △ ◎ ◎ ◎ ◎ Comparative Example 17 ○ △ △ ○ △ Comparative Example 18 ○ ○ ○ ◎ ○ Comparative example 19 ◎ ○ ○ ◎ ○

[0052]

As described in detail above, in the hydrophilic surface treating agent of the present invention, polyvinylpyrrolidone having a low degree of polymerization and polyvinylpyrrolidone having a high degree of polymerization are used in combination. Better hydrophilicity than hydrophilic coating with treatment material containing polyvinylpyrrolidone,
Has water solubility resistance. In addition, the odor is remarkably suppressed, and the adhesion and antifungal properties are good, and it is suitable for hydrophilic treatment of aluminum fin materials for heat exchangers.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location (C09D 129/04 177: 00 9286-4J 161: 06) 8215-4J (72) Inventor Mikami Fujio 4-1-1, Minami-Shinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. Tokyo office (72) Inventor Kiyotada Yasuhara 4-1-1, Minami-Shinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. Tokyo office

Claims (2)

[Claims] 1. A hydrophilic surface-treating agent for an aluminum heat exchanger, which comprises, in terms of solid content, (a) 40-60 parts by weight of polyvinyl alcohol having a saponification degree of 98% or more and a polymerization degree of 150-350. And (b) the polyvinylpyrrolidone having a degree of polymerization of 15 to 40 and the polyvinylpyrrolidone having a degree of polymerization of 100 to 300 are in a weight ratio of 1: 1.5 to 1: 3.0, and a total of 20 to A water-soluble resin containing 40 parts by weight, (c) 10 to 20 parts by weight of water-soluble nylon, and (d) 2 to 12 parts by weight of water-soluble phenolic resin;
1 to 10 parts by weight of a nonionic surfactant based on 100 parts by weight of the water-soluble resin, and (f) bis (2-pyridylthio)-
A hydrophilic surface treating agent comprising zinc-1,1-dioxide in an amount of 5 to 20 parts by weight based on 100 parts by weight of the water-soluble resin. 2. A heat exchanger substrate made of aluminum is subjected to (1) chemical conversion treatment, and (2) next, in terms of solid content, (a) saponification degree is 98% or more, and polymerization degree is 150-350 polyvinyl alcohol 4
0 to 60 parts by weight, (b) a polyvinylpyrrolidone having a polymerization degree of 15 to 40, and a polyvinylpyrrolidone having a polymerization degree of 100 to 300 are used in a weight ratio of 1: 1.5 to 1: 3.0. A total of 20 to 40 parts by weight, (c) 10 to 20 parts by weight of water-soluble nylon, (d) 2 to 12 parts by weight of water-soluble phenolic resin, and (e) a nonionic resin 1 to 10 parts by weight of a surfactant based on 100 parts by weight of the water-soluble resin, and (f) bis (2-pyridylthio) -zinc-1,1-dioxide based on 100 parts by weight of the water-soluble resin. A hydrophilizing surface treatment method comprising performing a surface treatment using a hydrophilizing surface treatment bath containing 5 to 20 parts by weight.