AQUEOUS RESIN DISPERSION, PRODUCTION METHOD FOR AQUEOUS RESIN DISPERSION, HYDROPHILIZATION AGENT, HYDROPHILIZATION METHOD, METAL MATERIAL, AND HEAT EXCHANGER

Abstract

Provided are an aqueous resin dispersion of an ethylene-vinyl alcohol copolymer exhibiting excellent dispersion stability, a production method for the aqueous resin dispersion, a hydrophilization agent including the aqueous resin dispersion, a hydrophilization method using the hydrophilization agent, a metal material on which a hydrophilic coating has been formed, and a heat exchanger on which a hydrophilic coating has been formed. Specifically provided are: an aqueous resin dispersion comprising an ethylene-vinyl alcohol copolymer (A) and a radical polymer (B) having a structural unit derived from a radical-polymerizable carboxylic acid monomer (B1-1), wherein the content of the radical polymer (B) is 10-80 mass % relative to the total content of the ethylene-vinyl alcohol copolymer (A) and the radical polymer (B); a production method for the aqueous resin dispersion; a hydrophilization agent including the aqueous resin dispersion; a hydrophilization method using the hydrophilization agent; a metal material on which a hydrophilic coating has been formed; and a heat exchanger on which a hydrophilic coating has been formed.

Claims

1. An aqueous resin dispersion, comprising ethylene-vinylalcohol copolymer (A), and a radical polymer (B) having a structural unit derived from a radically polymerizable carboxylic acid monomer (B1-1), the content of an ethylene structural unit in the ethylene-vinylalcohol copolymer (A) being 24 to 44 mol %, the content of the radical polymer (B) being 10 to 80 mass % relative to the total amount of the ethylene-vinylalcohol copolymer (A) and the radical polymer (B).

2. The aqueous resin dispersion according to claim 1, wherein the radical polymer (B) further has a structural unit derived from a radically polymerizable sulfonic acid monomer (B1-2).

3. The aqueous resin dispersion according to claim 1 or 2, wherein the radical polymer (B) further has a structural unit derived from at least one radically polymerizable monomer (B2-1) selected form the group consisting of a radically polymerizable monomer represented by the following formula (a), (meth)acrylamide, N-vinylformamide, N-vinylacetamide, and N-vinylpyrrolidone:
[Chem. 1]
CH.sub.2C(R.sup.1)CO(OCH.sub.2CH.sub.2).sub.mOR.sup.2 Formula (a), wherein in the formula (a), R.sup.1 represents H or CH.sub.3, and R.sup.2 represents H or CH.sub.3, and m represents an integer of 1 to 200.

4. The aqueous resin dispersion according to claim 3, wherein the radical polymer (B) further has a structural unit derived from at least one radically polymerizable monomer (B2-2) selected from the group consisting of a radically polymerizable hydroxy group-containing monomer, a radically polymerizable amide group-containing monomer, a radically polymerizable silyl group-containing monomer, a radically polymerizable epoxy group-containing monomer, a radically polymerizable ester group-containing monomer, and a vinyl group-containing monomer.

5. The aqueous resin dispersion according to claim 4, wherein the radical polymer (B) is a copolymer of a first monomer group and a second monomer group, or a mixture of a copolymer of the first monomer group and a copolymer of the second monomer group, the first monomer group having the radically polymerizable carboxylic acid monomer (B1-1) as an essential ingredient and having the radically polymerizable sulfonic acid monomer (B1-2) as an optional ingredient, and the second monomer group having the radically polymerizable monomer (B2-1) as an essential ingredient and having the radically polymerizable monomer (B2-2) as an optional ingredient.

6. The aqueous resin dispersion according to claims 1, further comprising at least one hydrophilic compound (C) selected from the group consisting of a compound having a structure represented by the following formula (b), a compound having a structure of polyvinylpyrrolidone, and a compound having a structure of poly-N-vinylformamide, the total content of the radical polymer (B) and the hydrophilic compound (C) being 10 to 80 mass % relative to the total amount of the ethylene-vinylalcohol copolymer (A), the radical polymer (B), and the hydrophilic compound (C):
[Chem. 2]
R.sup.3O(CH.sub.2CH.sub.2O).sub.nFormula (b), wherein in the formula (b), R.sup.3 represents H or CH.sub.3, and n represents an integer of 2 to 100,000.

7. A method of manufacturing the aqueous resin dispersion (D) according to claim 1, the method comprising the step of: performing a (co)polymerization reaction in a solution containing the ethylene-vinylalcohol copolymer (A) to obtain the radical polymer (B).

8. The method of manufacturing the aqueous resin dispersion (D) according to claim 6, comprising the step of: performing a (co)polymerization reaction in a solution containing the ethylene-vinylalcohol copolymer (A) and optionally the hydrophilic compound (C) to obtain the radical polymer (B).

9. A hydrophilization agent, comprising the aqueous resin dispersion (D) according to claim 1.

10. The hydrophilization agent according to claim 9, further comprising at least one of a hydrophilic compound (E) and a cross-linking agent (F), the total content of the hydrophilic compound (E) and the cross-linking agent (F) being 70 mass % or less relative to the total amount of the aqueous resin dispersion (D), the hydrophilic compound (E), and the cross-linking agent (F), and the content of the cross-linking agent (F) being 30 mass % or less relative to the total amount of the aqueous resin dispersion (D), the hydrophilic compound (E), and the cross-linking agent (F).

11. The hydrophilization agent according to claim 9, further comprising an anticorrosive material (G) including at least one or more selected from the group of Zr, V, Ti, Cr, Ce, Nb, and P.

12. The hydrophilization agent according to claim 11, wherein the content of the anticorrosive material (G) is 30 mass % or less relative to the total amount of the aqueous resin dispersion (D), the hydrophilic compound (E), and the cross-linking agent (F).

13. A hydrophilization method of obtaining a hydrophilic coating with the hydrophilization agent according to claim 9 via any of the steps of (I) to (V): (I) immersing a base material into a chemical conversion treatment agent, and washing the base material with water, and then applying the hydrophilization agent to the base material, and drying the hydrophilization agent; (II) applying the hydrophilization agent to a base material, and drying the hydrophilization agent, and further applying another hydrophilization agent different from the hydrophilization agent to the base material and drying the another hydrophilization agent; (III) allowing a primer to adhere on a base material, and drying the primer, and then applying the hydrophilization agent to the base material, and drying the hydrophilization agent; (IV) applying the hydrophilization agent to a base material, and drying the hydrophilization agent; or (V) immersing a base material into a chemical conversion treatment agent, and further allowing a primer to adhere, and drying the primer, and then applying the hydrophilization agent to the base material, and drying the hydrophilization agent.

14. A metal material having a hydrophilic coating formed thereon by allowing the hydrophilization agent according to claim 9 to adhere on a surface, and drying the hydrophilization agent.

15. A heat exchanger having a hydrophilic coating formed thereon by allowing the hydrophilization agent according to claim 9 to adhere on a surface, and drying the hydrophilization agent.

Description

EXAMPLES

[0077] Below, the present invention will be described in more detail with reference to Examples. However, the present invention shall not be limited to these Examples.

<Examples of Manufacturing Aqueous Resin Dispersion>

Example 1

[0078] To a flask to which a stirrer, a condenser, a temperature controller, and dripping funnels (2 lines) were attached, 60 parts by mass of a pellet-like EVOH (A) and a mixture of water and methanol 9 times in parts by mass relative to the EVOH (A) (water:methanol=1:1 by mass ratio) were charged, and heated to 75 C., and vigorously stirred for 1 hour or more to obtain an EVOH (A) solution.

[0079] Subsequently, a methanol solution of 40 parts by mass of acrylic acid and an aqueous solution of 0.6 parts by mass of ammonium persulfate were each placed in a separate dripping funnel, and added dropwise to the EVOH (A) solution under a nitrogen atmosphere. At this time, dropwise addition was performed over 30 minutes while maintaining the solution temperature at 75 C., and stirring was continued at the same temperature for 2 hours after completion of dropwise addition.

[0080] Subsequently, acrylic acid-equivalent aqueous ammonia (prepared by dilution with the same amount of methanol as that of water in the aqueous ammonia) was added dropwise over about 20 minutes to achieve neutralization. Then, a condenser tube for solvent removal was attached, and heated while supplying water to distill methanol away, thereby replacing the medium with water. Subsequently, this was cooled and filtered to obtain a stable aqueous resin dispersion.

Example 2 to Example 37

[0081] In Examples 2 to 37, using a similar procedure as in Example 1, the EVOH (A) and optionally the hydrophilic compound (C) were mixed and dissolved according to compositions shown in Table 1, and the radically polymerizable monomers (B1-1) and (B1-2) and optionally the radically polymerizable monomers (B2-1) and (B2-2) were mixed. This and an aqueous solution of ammonium persulfate were simultaneously but separately added dropwise to effect polymerization. The acid was neutralized with equivalent aqueous ammonia, and methanol was then replaced with water, and then cooled and filtered to obtain an aqueous resin dispersion. It is noted that in each of Comparative Examples 1 to 6, manufacture of a dispersion was tried by a similar procedure. However, only in Comparative Example 2, manufacture was performed without blending the radically polymerizable carboxylic acid monomer (B1-1).

<Dispersion Stability>

[0082] Dispersion stability was evaluated for the aqueous resin dispersions from Examples 1 to 37 and the dispersions from Comparative Examples 1 to 6 manufactured according to the aforementioned procedure. Results are shown in Table 1.

(Evaluation Criteria)

[0083] 3: no sedimentation separation was observed after one month has passed.

[0084] 2: precipitates were developed after one month had passed.

[0085] 1: significant aggregation and sedimentation separation were developed.

TABLE-US-00001 TABLE 1 Example Ingredients 1 2 3 4 5 6 7 8 9 10 11 12 (A) EVOH Ethylene ratio 25 mol % 60 80 42 36 53 37 37 Ethylene ratio 32 mol % 90 38 36 63 Ethylene ratio 44 mol % 75 (B) (B1-1) Radically Acrylic acid 40 18 10 25 31 31 21 19 14 25 21 21 polymerizable Methacrylic acid carboxylic acid monomer (B1-2) Radically HAPS 2 polymerizable AMPS sulfonic acid monomer (B2-1) Radically m = 1 R1, R2: H polymerizable m = 23 R1, R2: Me 31 monomer of m = 45 R1, R2: Me 31 27 35 11 Formula (a) m = 113 R1, R2: Me 21 21 Radically NVF polymerizable AAm monomer (B2-2) Radically DMAA 10 polymerizable GMA monomer (C) Hydrophilic PEG 14 11 21 16 compound PEO 5 PVP 18 EO-PVA PNVF Dispersion stability 3 3 3 3 3 3 3 3 3 3 3 3 Example Ingredients 13 14 15 16 17 18 19 20 21 22 (A) EVOH Ethylene ratio 25 mol % 32 36 36 38 28 40 40 40 Ethylene ratio 32 mol % 35 Ethylene ratio 44 mol % 35 (B) (B1-1) Radically Acrylic acid 32 29 29 23 21 21 32 23 polymerizable Methacrylic acid 28 14 32 carboxylic acid monomer (B1-2) Radically HAPS 2 polymerizable AMPS sulfonic acid monomer (B2-1) Radically m = 1 R1, R2: H polymerizable m = 23 R1, R2: Me monomer of m = 45 R1, R2: Me 26 21 Formula (a) m = 113 R1, R2: Me 18 14 20 8 16 16 16 Radically NVF 15 polymerizable AAm 2 monomer (B2-2) Radically DMAA polymerizable GMA 1 monomer (C) Hydrophilic PEG 24 8 21 21 12 12 21 compound PEO PVP 18 EO-PVA 21 PNVF 15 8 Dispersion stability 3 3 3 3 3 3 3 3 3 3 Example Ingredients 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 (A) EVOH Ethylene ratio 25 mol % 35 35 33 25 25 Ethylene ratio 32 mol % 40 40 60 40 40 40 49 50 50 Ethylene ratio 44 mol % 40 (B) (B1-1) Radically Acrylic acid 21 21 33 45 45 32 32 32 30 30 30 32 24 40 40 polymerizable Methacrylic acid carboxylic acid monomer (B1-2) Radically HAPS polymerizable AMPS 2 sulfonic acid monomer (B2-1) Radically m = 1 R1, R2: H 10 polymerizable m = 23 R1, R2: Me 13 10 monomer of m = 45 R1, R2: Me 10 Formula (a) m = 113 R1, R2: Me 15 15 16 16 16 10 16 16 16 11 Radically NVF 7 polymerizable AAm 7 monomer (B2-2) Radically DMAA polymerizable GMA 10 monomer (C) Hydrophilic PEG 22 22 20 20 20 12 12 12 12 17 compound PEO 12 PVP 14 EO-PVA PNVF Dispersion stability 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Comparative Example Ingredients 1 2 3 4 5 6 (A) EVOH Ethylene ratio 25 mol % 95 92 8 Ethylene ratio 32 mol % 75 15 17 Ethylene ratio 44 mol % (B) (B1-1) Radically Acrylic acid 5 85 3 4 46 polymerizable Methacrylic acid carboxylic acid monomer (B1-2) Radically HAPS polymerizable AMPS 25 sulfonic acid monomer (B2-1) Radically m = 1 R1, R2: H polymerizable m = 23 R1, R2: Me monomer of m = 45 R1, R2: Me Formula (a) m = 113 R1, R2: Me 80 Radically NVF polymerizable AAm monomer (B2-2) Radically DMAA polymerizable GMA monomer (C) Hydrophilic PEG 46 compound PEO 4 PVP EO-PVA PNVF Dispersion stability 1(Aggre- 1(Aggre- 1(Sepa- 1(Aggre- 1(Aggre- 1(Aggre- gation) gation) ration) gation) gation) gation)

[0086] In Table 1, the numerical values recited in a column of each of Examples and Comparative Examples represent the content (mass %) of each component in the solid content of an aqueous resin dispersion. Further, the abbreviations of materials shown in Table 1 represent the followings. HAPS: a sodium salt of 3-allyloxy-2-hydroxy-1-propanesulfonic acid

AMPS: 2-acrylamido-2-methylpropanesulfonic acid

NVF: N-vinylformamide

[0087] AAm: acrylamide

DMAA: N,N-dimethylacrylamide

[0088] GNA: glycidyl methacrylate
PEG: polyethylene glycol (weight average molecular weight: 20000)
PEO: polyethylene oxide (weight average molecular weight: 500000)
PVP: polyvinylpyrrolidone (weight average molecular weight: 20000)
EO-PVA: polyoxyethylene-modified polyvinyl alcohol (weight average molecular weight: 20000)
PNVF: poly-N-vinylformamide (weight average molecular weight: 100000)

[0089] Comparison of Examples 1 to 37 with Comparative Example 2 revealed that the aqueous resin dispersions from Examples 1 to 37 showed superior dispersion stability. These results demonstrate that according to the aqueous resin dispersion of the present invention including the radical polymer (B) having a structural unit derived from the radically polymerizable carboxylic acid monomer (B1-1), a dispersion with excellent dispersion stability can be obtained.

[0090] Further, comparison of Examples 1 to 37 with Comparative Examples 1 and 5 revealed that the aqueous resin dispersions from Examples 1 to 37 showed superior dispersion stability. These results demonstrate that according to the aqueous resin dispersion of the present invention in which the content of the radical polymer (B) relative to the total amount of the EVOH (A) and the radical polymer (B) was 10 mass % or more, a dispersion with excellent dispersion stability can be obtained.

[0091] Moreover, comparison of Examples 1 to 37 with Comparative Examples 3, 4, and 6 revealed that the aqueous resin dispersions from Examples 1 to 37 showed superior dispersion stability. These results demonstrate that according to the aqueous resin dispersion of the present invention in which the content of the radical polymer (B) relative to the total amount of the EVOH (A) and the radical polymer (B) was 80 mass % or less, a dispersion with excellent dispersion stability can be be obtained.

Example 38 to Example 56

<Preparation of Hydrophilization Agent>

[0092] The aqueous resin dispersion (D) manufactured in Examples 1, 6, 11, and 15, the hydrophilic compound (E), and the cross-linking agent (F) were mixed according to blended amounts (contents) shown in Table 2 to prepare the hydrophilization agents for Examples 38 to 56 and Comparative Examples 7 and 8.

<Preparation of Cross-Linkable Microparticles>

[0093] Cross-linkable microparticles belonging to the hydrophilic compound (E) recited in Examples of Table 2 were prepared as follows. A monomer solution in which 70 parts by mass of N-methylolacrylamide and 30 parts by mass of methoxypolyethylene glycol monomethacrylate (a polyethylene chain with a number of repeating units of 90) were dissolved in 200 parts by mass of methoxy propanol and a solution in which ACVA (an azo-based initiator from Otsuka Chemical Co., Ltd.) was dissolved in 50 parts by mass of methoxy propanol were each added dropwise to 150 parts by mass of methoxy propanol through separate inlets at 105 C. over 3 hours under a nitrogen atmosphere, and further heated with stirring for 1 hour to allow for polymerization. Cross-linkable microparticles in the resulting dispersion liquid had an average particle size of 250 nm.

<Production of Test Plates>

[0094] A piece of 1000 series aluminum material having a dimension of 150 mm200 mm0.13 mm was degreased with a 1% solution of Surfcleaner EC370 from Nippon Paint Surf Chemicals Co., Ltd. at 70 C. for 5 seconds. Subsequently, treatment with phosphoric acid chromate was performed at 40 C. for 5 seconds using a 10% solution of Alsurf 407/47 from Nippon Paint Surf Chemicals Co., Ltd. Subsequently, the hydropilization agents obtained from Examples 38 to 56 and Comparative Examples 7 and 8 were each prepared so as to have 5% solid content, and each applied to the above aluminum material with a bar coater #4, and heated at 220 C. for 20 seconds, and dried to produce a test plate.

<Evaluation of Initial Hydrophilicity>

[0095] The contact angle of a water droplet against each test plate was evaluated. A water contact angle was measured with an automatic contact angle meter (model number: DSA20E, KRUSS GmbH). A contact angle between a test plate and a water droplet was measured under a room temperature environment, 30 seconds after the droplet was dropped. Evaluation results are shown in Table 2. It is noted that when the contact angle is 30 or less, hydrophilicity is considered good.

(Evaluation Criteria)

[0096] 4: water contact angle was 20 or less
3: more than 20 but 30 or less
2: more than 30 but 50 or less
1: more than 50

<Evaluation of Sustained Hydrophilicity>

[0097] A test plate was immersed into pure water for 240 hours, and then removed and dried. Subsequently, the water contact angle with a water droplet on the dried test plate was measured. A water contact angle was measured with an automatic contact angle meter (model number: DSA20E, KRUSS GmbH). A contact angle between a test plate and a water droplet was measured under a room temperature environment, 30 seconds after the droplet was dropped. Evaluation results are shown in Table 2. It is noted that when the contact angle is 30 or less, sustained hydrophilicity is considered good.

(Evaluation Criteria)

[0098] 4: water contact angle was 20 or less
3: more than 20 but 30 or less
2: more than 30 but 50 or less
1: more than 50

<Evaluation of WET Adhesiveness>

[0099] Pure water was sprayed on a test plate, and then a coating was rubbed under a load of 500 g. One reciprocating motion was counted as one stroke, and maximumly 10 strokes of rubbing were performed until an underlying material was exposed, and then evaluation was performed. Evaluation results are shown in Table 2. When the number of strokes until the underlying material of a test plate was exposed was 7 or more, adhesiveness is considered good.

(Evaluation Criteria)

[0100] 4: a hydrophilic coating was not removed after 10 strokes of sliding.
3: a hydrophilic coating was removed after 7 strokes or more of sliding but less than 10 strokes.
2: a hydrophilic coating was removed after 3 strokes or more of sliding but less than 7 strokes.
1: a hydrophilic coating was removed after less than 3 strokes of sliding.

<Drainage>

[0101] A 10-L water droplet was placed on a horizontally arranged test plate. Subsequently, the test plate was positioned vertically, and time until the water droplet moved downward by 8 cm was measured. Drainage was then evaluated according to the following criteria. Evaluation results are shown in Table 2. It is noted that drainage was considered good when the evaluation score was 3 or more.

(Evaluation Criteria)

[0102] 4: 15 seconds or less
3: more than 15 seconds but 25 seconds or less
2: more than 25 seconds but 40 seconds or less
1: more than 40 seconds

<Evaluation of Anti-Contamination Effects>

[0103] A test plate was immersed into pure water for 24 hours, and then removed and dried. Subsequently, the dried test plate was immersed for 30 seconds into a solution in which 3 parts by mass of stearic acid, 3 parts by mass of 1-octadecanol, 3 parts by mass of palmitic acids, and 3 parts by mass of bis(2-ethylhexyl)phthalate was dissolved in 1188 parts by mass of trichloroethylene. Pure water was sprayed to the test plate removed after permeation and air dried, which was then air dried. Then a water contact angle with a water droplet on the test plate was measured. A water contact angle was measured with an automatic contact angle meter (model number: DSA20E, KRUSS GmbH). A contact angle with a water droplet was measured under a room temperature environment, 30 seconds after the water droplet was dropped, and evaluation was performed according to the following criteria. Evaluation results are shown in Table 2. It is noted that when the contact angle is 30 or less, anti-contamination effects is considered good.

(Evaluation Criteria)

[0104] 4: water contact angle was 20 or less
3: more than 20 but 30 or less
2: more than 30 but 50 or less
1: more than 50

TABLE-US-00002 TABLE 2 Example Ingredients 38 39 40 41 42 43 44 45 46 47 48 (D) Aqueous resin Example 1 40 dispersion Example 6 100 100 70 70 Example 11 100 100 60 60 Example 14 100 100 Example 15 (E) Hydrophilic Cross-linkable 40 30 20 compound microparticles EO-PVA 20 40 30 PVA 10 PAA 10 CMC PVP PEG NMAM PNVF Acrylic acid copolymer Sulfonic acid copolymer (F) Cross-linking Melamine resin 2 1 25 2 2 2 2 agent Silane coupling agent 2.5 Total (parts by mass) 100 100 100 100 102 103.5 125 102 102 102 102 Initial hydrophilicity 3 3 3 3 3 3 3 4 4 4 4 Sustained Hydrophilicity 3 3 3 3 3 3 3 4 4 4 4 Wet adhesiveness 3 3 3 3 4 4 4 4 4 4 4 Drainage 3 3 3 3 3 3 3 4 4 4 4 Anti-contamination effects 3 3 3 3 3 3 3 4 4 4 4 Comparative Example Example Ingredients 49 50 51 52 53 54 55 56 7 8 (D) Aqueous resin Example 1 dispersion Example 6 60 80 100 Example 11 50 60 20 Example 14 70 60 80 Example 15 70 (E) Hydrophilic Cross-linkable 20 40 10 10 30 compound microparticles EO-PVA 30 30 30 80 PVA PAA CMC 10 PVP 10 PEG 10 NMAM 10 PNVF 10 Acrylic acid copolymer 10 Sulfonic acid copolymer 10 (F) Cross-linking Melamine resin 2 2 2 2 2 2 1 2 50 2 agent Silane coupling agent Total (parts by mass) 102 102 102 102 102 102 102 102 150 102 Initial hydrophilicity 4 4 4 4 4 4 4 4 2 3 Sustained Hydrophilicity 4 4 4 4 4 4 4 4 1 2 Wet adhesiveness 4 4 4 4 4 4 4 4 3 3 Drainage 4 4 4 4 4 4 4 4 1 1 Anti-contamination effects 4 4 4 4 4 4 4 4 1 2

[0105] In Table 2, the numerical values recited in a column of each of Examples and Comparative Examples represent the content (mass %) of each component in the solid content of a hydrophilization agent. Further, the abbreviations and descriptions of materials shown in Table 2 represent the followings. Cross-linkable microparticles: cross-linkable microparticles prepared as described above

EO-PVA: ethylene oxide-modified PVA (weight average molecular weight: 20000)
PVA: polyvinyl alcohol (weight average molecular weight: 20000, the degree of saponification: 98.5)
PAA: polyacrylic acid (weight average molecular weight: 20000, acid value: 780 mg KOH/g)
CMC: carboxymethylcellulose (weight average molecular weight: 20000)
PVP: polyvinylpyrrolidone (weight average molecular weight: 20000)
PEG: polyethylene glycol (weight average molecular weight: 20000)
NMAM: N-me thylolacrylamide
PNVF: poly-N-vinylformamide (weight average molecular weight: 100000)
Acrylic acid copolymer: a sodium salt of acrylic acid/vinylformamide copolymer (weight average molecular weight:700000)
Sulfonic acid copolymer: a sodium salt of 2-acrylamido-2-methylpropane sulfonic acid/acrylic acid copolymer (weight average molecular weight: 10000)
Melamine resin: Cymel (registered trademark) 370N from Nihon Cytec Industries Inc. Silane coupling agent: KBM-403 from Shin-Etsu Chemical Co., Ltd.

[0106] Comparison of Examples 38 to 56 with Comparative Example 7 revealed that the hydrophilic coatings formed with the hydrophilization agents from Examples 38 to 56 was superior in any of initial hydrophilicity, sustained hydrophilicity, wet adhesiveness, drainage, and anti-contamination effects. These results demonstrate that according to the hydrophilization agent of the present invention including the cross-linking agent (F) in an amount within the range of 30 mass % or less relative to the total amount of the aqueous resin dispersion (D), the hydrophilic compound (E), and the cross-linking agent (F), a hydrophilic coating excellent in any of initial hydrophilicity, sustained hydrophilicity, wet adhesiveness, drainage, and anti-contamination effects can be obtained.

[0107] Comparison of Examples 38 to 56 with Comparative Example 8 revealed that the hydrophilic coatings formed with the hydrophilization agents from Examples 38 to 56 was superior in initial hydrophilicity, sustained hydrophilicity, wet adhesiveness, drainage, and anti-contamination effects. These results demonstrate that according to the hydrophilization agent of the present invention including the hydrophilic compound (E) and the cross-linking agent (F) in an amount within the range of 70 mass % or less relative to the total amount of the aqueous resin dispersion (D), the hydrophilic compound (E), and the cross-linking agent (F), a hydrophilic coating excellent in any of initial hydrophilicity, sustained hydrophilicity, wet adhesiveness, drainage, and anti-contamination effects can be obtained.

[0108] According to the aqueous resin dispersion of the present invention, a dispersion with excellent dispersion stability can be obtained. Further, according to the hydrophilization agent including that aqueous resin dispersion, a hydrophilic coating can be obtained having excellent (initial) hydrophilicity, in particular, excellent sustained hydrophilicity after adhesion of contaminants, and also having excellent adhesiveness, drainage, and anti-contamination effects. Therefore, the aqueous resin dispersion according to the present invention, a hydrophilization agent including the aqueous resin dispersion, and a hydrophilic coating obtainable with the hydrophilization agent are preferably used for metal, in particular, aluminum and alloys thereof.

Example 57 to Example 89

[0109] The aqueous resin dispersion (D) manufactured in Examples 22, 26, 31, 34, and 37, the hydrophilic compound (E), the cross-linking agent (F), and anticorrosive material (G) were mixed according to the blended amounts (contents) shown in

[0110] Table 3 to prepare the hydrophilization agents of Examples 57 to 89 and Comparative Examples 9 to 11.

<Preparation of Cross-Linkable Microparticles>

[0111] The cross-linkable microparticles belonging to the hydrophilic compound (E) recited in Examples of Table 3 were prepared in a similar way as described above.

<Production of Test Heat Exchanger>

[0112] For a test heat exchanger, the 1000 series aluminum material described above was used to produce an aluminum heat exchanger for automobile air-conditioners (NB heat exchanger). Subsequently, the test heat exchanger was subjected to surface treatment under the following treatment conditions. In each of Examples 57 to 89 and Comparative Examples 9 to 11 shown in Table 3, the above test heat exchanger was used for the following evaluation.

(Treatment Conditions)

[0113] Condition I: A surface of the test heat exchanger was acid-washed with a 5% liquid of sulfuric acid, and then washed with water. Subsequently, this was dip-coated with a 10% liquid of Alsurf 900 from Nippon Paint Surf Chemicals Co., Ltd. at 60 C. for 60 seconds to form a chemical conversion coating on the surface of the test heat exchanger. Subsequently, the hydrophilization agents obtained from Examples 57, 62, 63, 70, 71, and 81 to $9 and Comparative Examples 9 to 11 were each prepared so as to have 5% solid content, and used to perform dip-coating of the surface of the test heat exchanger. The resulting heat exchanger was then allowed to stand for 30 minutes under a 160 C. environment to produce a test heat exchanger.

[0114] Condition II: A surface of the test heat exchanger was acid-washed with a 5% liquid of sulfuric acid, and then washed with water. Subsequently, the hydrophilization agents obtained from Examples 58, 65, and 72 were each prepared so as to have 5% solid content, and used to perform dip-coating of the above surface of the test heat exchanger. The resultant heat exchanger was then allowed to stand for 30 minutes under a 160 C. environment. Subsequently, a 5-times diluted Surfalcoat 1100 from Nippon Paint Surf Chemicals Co., Ltd. was applied to this test heat exchanger, and heated and dried at 160 C. for 30 minutes to produce a test heat exchanger.

[0115] Condition III: A surface of the test heat exchanger was acid-washed with a 5% liquid of sulfuric acid, and then washed with water. Subsequently, this was dip-coated with Surfalcoat 510 from Nippon Paint Surf Chemicals Co., Ltd., and the resultant heat exchanger was then allowed to stand for 30 minutes under a 160 C. environment. Subsequently, the hydrophilization agents obtained from Examples 59 and 67 were each prepared so as to have 5% solid content, and used to perform dip-coating of the above surface of the test heat exchanger. The resultant heat exchanger was then allowed to stand for 30 minutes under a temperature environment of 160 C. to produce a test heat exchanger.

[0116] Condition IV: A surface of the test heat exchanger was washed with hot water, and then washed with water. Subsequently, the hydrophilization agents obtained from Examples 60, 64, 68, 69, 73 to 80 were each prepared so as to have 5% solid content, and used to perform dip-coating of the above surface of the test heat exchanger. The resultant heat exchanger was then allowed to stand for 30 minutes under a temperature environment of 160 C. to form a chemical conversion coating on the surface of the test heat exchanger.

[0117] Condition V: A surface of the test heat exchanger was acid-washed with a 5% liquid of sulfuric acid, and then washed with water. Subsequently, this was dip-coated with a 10% liquid of Alsurf 900 from Nippon Paint Surf Chemicals Co., Ltd. at 60 C. for 60 seconds to form a chemical conversion coating on the surface of the test heat exchanger. Subsequently, this was dip-coated with Surfalcoat 510 from Nippon Paint Surf Chemicals Co., Ltd., and heated and dried at 160 C. for 30 minutes. Subsequently, the hydrophilization agents obtained from Examples 61 and 66 were each prepared so as to have 5% solid content, and used to perform dip-coating of the above surface of the test heat exchanger. The resultant heat exchanger was then allowed to stand for 30 minutes under a temperature environment of 160 C. to form a chemical conversion coating on the surface of the test heat exchanger.

<Evaluation of Initial Hydrophilicity>

[0118] The contact angle of a water droplet against a fin surface of a test heat exchanger was evaluated according to similar evaluation criteria as in the evaluation of the initial hydrophilicity in Example 38 as described above. Evaluation results are shown in Table 3.

<Evaluation of Sustained Hydrophilicity>

[0119] Sustained hydrophilicity of a test heat exchanger was evaluated according to similar evaluation criteria as in the evaluation of initial hydrophilicity in Example 38 as described above. Evaluation results are shown in Table 3.

<Corrosion Resistance>

[0120] Test heat exchangers were evaluated for corrosion resistant (white rust resistance) in accordance with JIS 2371. Specifically, a solution of 5% sodium chloride was sprayed at 35 C. on each of the test heat exchangers produced in Examples and Comparative Examples, and then the area of portion(s) where white rust was developed was visually evaluated after 480 hours had passed in accordance with the following evaluation criteria. Evaluation results are shown in Table 3.

(Evaluation Criteria)

[0121] 4: no white rust was developed, or white rust was observed with an area of white rust of less than 10%.
3: the area of white rust was 10% or more but less than 20%.
2: the area of white rust was 20% or more but less than 50%.
1: the area of white rust was 50% or more.

<Moisture Resistance>

[0122] The test heat exchangers were subjected to moisture resistance tests under an atmosphere of a temperature of 50 C. and a humidity of 98% or more for 480 hours. The area of a blackened portion after the test was visually evaluated in accordance with the following criteria for evaluating corrosion resistance. Evaluation results are shown in Table 3. It is noted that blackening may eventually turn into white rust, and thus the area of portion(s) wherein white rust was developed was added to the area of blackened portion(s).

(Evaluation Criteria)

[0123] 4: no color change, or color change was observed with an area of discolored portion(s) of less than 10%.
3: the area of discolored portion(s) was 10% or more but less than 20%.
2: the area of discolored portion(s) was 20% or more but less than 50%.
1: the area of discolored portion(s) was 50% or more.

<Odorlessness>

[0124] After contacting the test heat exchanger with a stream of tap water for 72 hours, odor was evaluated in accordance with the following evaluation criteria. Evaluation results are shown in Table 3. It is noted that when an odor evaluation score is 2 or more, odorlessness is considered good.

(Evaluation Criteria)

[0125] 3: no odor was sensed.
2: an odor was slightly sensed.
1: an odor was obviously sensed.

TABLE-US-00003 TABLE 3 Example Ingredients 57 58 59 60 61 62 63 64 65 66 67 68 69 (D) Aqueous resin Example 22 100 100 100 100 dispersion Example 26 100 Example 31 100 Example 34 100 100 100 100 100 Example 37 100 100 (E) Hydrophilic Cross-linkable compound microparticles EO-PVA PVA PAA PVP PEG Acrylic acid copolymer Sulfonic acid copolymer (F) Cross-linking Melamine resin 2 2 2 2 2 2 2 2 2 2 2 2 2 agent Silane coupling agent (G) Anticorrosive Zirconium compound 2 5 5 material Venadium compound 1 1 1 1 1 1 1 1 1 5 5 Titanium compound 1 1 1 1 1 1 1 1 1 Niobium compound Phosphorus compounds 20 Cerium compound Chromium compound Total (parts by mass) 104 104 104 104 104 104 104 104 104 102 104 112 132 Conditions I Conditions II Conditions III Conditions IV Conditions V Initial hydrophilicity 4 4 4 4 4 4 4 4 3 4 4 4 3 Sustained Hydrophilicity 4 4 4 4 4 4 4 4 3 4 4 4 3 Corrosion resistance 4 4 4 4 4 4 4 4 4 4 4 4 4 Moisture resistance 4 4 4 4 4 4 4 4 4 4 4 4 4 Odorlessness 3 3 3 3 3 3 3 3 3 3 3 3 2 Example Ingredients 70 71 72 73 74 75 76 77 78 79 80 81 82 (D) Aqueous resin Example 22 100 100 100 100 78 dispersion Example 26 100 100 100 Example 31 100 100 100 Example 34 78 Example 37 100 (E) Hydrophilic Cross-linkable 10 20 compound microparticles EO-PVA PVA PAA PVP PEG Acrylic acid copolymer Sulfonic acid copolymer (F) Cross-linking Melamine resin 2 2 2 2 2 2 2 2 2 2 10 1 2 agent Silane coupling agent 25 (G) Anticorrosive Zirconium compound 1 1 1 3 5 0.1 1 material Venadium compound 3 5 1 Titanium compound 1 1 1 3 2 5 1 1 Niobium compound Phosphorus compounds 14 Cerium compound Chromium compound 3 Total (parts by mass) 105 102 104 104 104 122 107 107 107 107 112 91.6 102 Conditions I Conditions II Conditions III Conditions IV Conditions V Initial hydrophilicity 4 4 4 4 4 3 4 4 4 4 3 4 4 Sustained Hydrophilicity 4 4 4 4 4 3 4 4 4 4 3 4 4 Corrosion resistance 4 4 4 4 4 4 4 4 4 4 4 4 4 Moisture resistance 4 4 4 4 4 4 4 4 4 4 4 4 4 Odorlessness 2 3 3 3 3 2 3 3 3 3 3 3 3 Example Comparative Example Ingredients 83 84 85 86 87 88 89 9 10 11 (D) Aqueous resin Example 22 88 20 dispersion Example 26 88 88 Example 31 88 88 Example 34 88 Example 37 88 100 100 (E) Hydrophilic Cross-linkable compound microparticles EO-PVA 10 PVA 10 80 PAA 10 PVP 10 PEG 10 Acrylic acid copolymer 10 Sulfonic acid copolymer 10 (F) Cross-linking Melamine resin 2 2 2 2 2 2 50 agent Silane coupling agent (G) Anticorrosive Zirconium compound 1 1 5 40 material Venadium compound 1 5 1 1 2 Titanium compound 1 Niobium compound 1 Phosphorus compounds Cerium compound 1 Chromium compound 1 Total (parts by mass) 102 106 102 100 101 107 101 150 100 140 Conditions I Conditions II Conditions III Conditions IV Conditions V Initial hydrophilicity 4 4 4 4 4 4 4 1 3 1 Sustained Hydrophilicity 4 4 4 4 4 4 4 1 2 1 Corrosion resistance 4 4 4 4 4 4 4 3 1 3 Moisture resistance 4 4 4 4 4 4 4 3 1 3 Odorlessness 3 3 3 3 3 3 3 1 2 1

[0126] In Table 3, the numerical values recited in a column of each of Examples and Comparative Examples represent the content (mass %) of each component in the solid content of a hydrophilization agent. Further, the abbreviations and descriptions of materials shown in Table 3 represent the followings. Cross-linkable microparticles: cross-linkable microparticles prepared as described above

EO-PVA: ethylene oxide-modified PVA (weight average molecular weight: 20000)
PVA: polyvinyl alcohol (weight average molecular weight: 20000, the degree of saponification: 98.5)
PAA: polyacrylic acid (weight average molecular weight: 20000, acid value: 780 mg KOH/g)
PVP: polyvinylpyrrolidone (weight average molecular weight: 20000)
PEG: polyethylene glycol (weight average molecular weight: 20000)
Acrylic acid copolymer: a sodium salt of acrylic acid/N-vinylformamide copolymer (weight average molecular weight:700000)
Sulfonic acid copolymer: a sodium salt of 2-acrylamido-2-methylpropane sulfonic acid/acrylic acid copolymer (weight average molecular weight: 10000)
Melamine resin: Cymel (registered trademark) 370N from Nihon Cytec industries Inc. Silane coupling agent: KBM-403 from Shin-Etsu Chemical Co., Ltd. Zirconium compound: ammonium hexafluorozirconate
Vanadium compound: ammonium metavanadate
Titanium compound: titanium diisopropoxy
bis(triethanolaminate)
Niobium compound: niobium hydroxide
Phosphorus compounds: polyphosphoric acid
Cerium compound: ceric ammonium nitrate
Chromium compound: chromium nitrate

[0127] Comparison of Examples 57 to 89 with Comparative Examples 9 to 11 shown in Table 3 revealed that the hydrophilic coatings formed with the hydrophilization agents from Examples 57 to 89 were superior in any of initial hydrophilicity, sustained hydrophilicity, corrosion resistance, moisture resistance, and odorlessness. These results demonstrate that according to the hydrophilization agent of the present invention including the hydrophilic compound (E) and the cross-linking agent (F) in an amount within the range of 70 mass % or less relative to the total amount of the aqueous resin dispersion (D), the hydrophilic compound (E), and the cross-linking agent (F), and including the cross-linking agent (F) in an amount within the range of 30 mass % or less relative to the total amount of the aqueous resin dispersion (D), the hydrophilic compound (E), and the cross-linking agent (F), and including the anticorrosive material (G) in an amount within the range of 30 mass % or less relative to the total amount of the aqueous resin dispersion (D), the hydrophilic compound (E), and the cross-linking agent (F), a hydrophilic coating excellent in any of initial hydrophilicity, sustained hydrophilicity, corrosion resistance, moisture resistance, and odorlessness can be obtained.

[0128] According to the hydrophilization agent including an inorganic compound of the present embodiment, a hydrophilic coating having excellent (initial) hydrophilicity and sustained hydrophilicity, and also having excellent corrosion resistance, moisture resistance, and odorlessness can be formed regardless of a precoat to be applied to a base material (aluminum material) before assembling a heat exchanger or a post coat to be applied to a heat exchanger (base material) after assembly. Therefore, the aqueous resin dispersion according to the present invention, a hydrophilization agent including the aqueous resin dispersion, and a hydrophilic coating obtainable with the hydrophilization agent are preferably used for heat exchangers of automobiles, air-conditioners, and the like.