AQUEOUS RESIN COMPOSITION, AQUEOUS PAINT, AND PLASTIC MOLDED ARTICLE COATED WITH THE AQUEOUS PAINT

Abstract

Provided is an aqueous resin composition containing a polycarbonate-modified acrylic resin that is a reaction product of a polycarbonate diol (A) made from 1,4-butanediol as an essential raw material and an unsaturated monomer mixture (B) containing methyl methacrylate, an unsaturated monomer (b1) having a hydroxy group, an unsaturated monomer (b2) having a carboxy group, and an unsaturated monomer (b3) having an alicyclic structure as essential components, and an aqueous medium, in which the ratio of the unsaturated monomer (b3) in the unsaturated monomer mixture (B) is in the range of 3 to 60% by mass. This aqueous resin composition is suitable for aqueous paints and plastic molded articles since the composition can form a coating film having high adhesion to a plastic substrate and having high water-resistant adhesion and fragrance resistance.

Claims

1. An aqueous resin composition comprising: a polycarbonate-modified acrylic resin that is a reaction product of a polycarbonate diol (A) made from 1,4-butanediol as an essential raw material and an unsaturated monomer mixture (B) containing methyl methacrylate, an unsaturated monomer (b1) having a hydroxy group, an unsaturated monomer (b2) having a carboxy group, and an unsaturated monomer (b3) having an alicyclic structure as essential components; and an aqueous medium, wherein a ratio of the unsaturated monomer (b3) in the unsaturated monomer mixture (B) is in a range of 3 to 60% by mass.

2. The aqueous resin composition according to claim 1, wherein a ratio of the unsaturated monomer (b2) in the unsaturated monomer mixture (B) is in a range of 1 to 10% by mass.

3. The aqueous resin composition according to claim 1, wherein a mass ratio [(A)/(B)] of the polycarbonate diol (A) to the unsaturated monomer mixture (B) is in a range of 2/100 to 60/100.

4. The aqueous resin composition according to claim 1, wherein a ratio of the methyl methacrylate in the unsaturated monomer mixture (B) is in a range of 20 to 80% by mass, and a ratio of the unsaturated monomer (b1) in the unsaturated monomer mixture (B) is in a range of 1 to 50% by mass.

5. The aqueous resin composition according to claim 1, wherein the unsaturated monomer (b3) is cyclohexyl (meth)acrylate.

6. An aqueous paint comprising: the aqueous resin composition according to claim 1; and a curing agent.

7. A plastic molded article coated with the aqueous paint according to claim 6.

8. The aqueous resin composition according to claim 2, wherein a mass ratio [(A)/(B)] of the polycarbonate diol (A) to the unsaturated monomer mixture (B) is in a range of 2/100 to 60/100.

9. The aqueous resin composition according to claim 2, wherein a ratio of the methyl methacrylate in the unsaturated monomer mixture (B) is in a range of 20 to 80% by mass, and a ratio of the unsaturated monomer (b1) in the unsaturated monomer mixture (B) is in a range of 1 to 50% by mass.

10. The aqueous resin composition according to claim 3, wherein a ratio of the methyl methacrylate in the unsaturated monomer mixture (B) is in a range of 20 to 80% by mass, and a ratio of the unsaturated monomer (b1) in the unsaturated monomer mixture (B) is in a range of 1 to 50% by mass.

11. The aqueous resin composition according to claim 2, wherein the unsaturated monomer (b3) is cyclohexyl (meth)acrylate.

12. The aqueous resin composition according to claim 3, wherein the unsaturated monomer (b3) is cyclohexyl (meth)acrylate.

13. The aqueous resin composition according to claim 4, wherein the unsaturated monomer (b3) is cyclohexyl (meth)acrylate.

14. An aqueous paint comprising: the aqueous resin composition according to claim 2; and a curing agent.

15. An aqueous paint comprising: the aqueous resin composition according to claim 3; and a curing agent.

16. An aqueous paint comprising: the aqueous resin composition according to claim 4; and a curing agent.

17. An aqueous paint comprising: the aqueous resin composition according to claim 5; and a curing agent.

18. A plastic molded article coated with the aqueous paint according to claim 14.

19. A plastic molded article coated with the aqueous paint according to claim 15.

20. A plastic molded article coated with the aqueous paint according to claim 16.

Description

EXAMPLES

[0046] The present invention will be described in more detail below with specific examples. The hydroxy value of the polycarbonate-modified acrylic resin of the present invention was determined in accordance with the JIS test method K 0070-1992. The particle size was measured using Nanotrac UPA-EX150 manufactured by NIKKISO CO, LTD. The average molecular weight was measured under the following conditions of GPC measurement.

[Conditions of GPC Measurement]

[0047] Measuring system: High-speed GPC system (“HLC-8220GPC” manufactured by Tosoh Corporation) Column: The following columns manufactured by Tosoh Corporation were connected in series.

[0048] “TSKgel G5000” (7.8 mm I.D.×30 cm)×1

[0049] “TSKgel G4000” (7.8 mm I.D.×30 cm)×1

[0050] “TSKgel G3000” (7.8 mm I.D.×30 cm)×1

[0051] “TSKgel G2000” (7.8 mm I.D.×30 cm)×1

Detector: RI (differential refractometer)
Column temperature: 40° C.

Eluent: Tetrahydrofuran (THF)

[0052] Flow rate: 1.0 mL/min
Injection volume: 100 μL (tetrahydrofuran solution having a sample concentration of 4 mg/mL)
Standard sample: A calibration curve was prepared using the following monodisperse polystyrene.

(Monodisperse Polystyrene)

[0053] “TSKgel Standard polystyrene A-500” manufactured by Tosoh Corporation

[0054] “TSKgel Standard polystyrene A-1000” manufactured by Tosoh Corporation

[0055] “TSKgel Standard polystyrene A-2500” manufactured by Tosoh Corporation

[0056] “TSKgel Standard polystyrene A-5000” manufactured by Tosoh Corporation

[0057] “TSKgel Standard polystyrene F-1” manufactured by Tosoh Corporation

[0058] “TSKgel Standard polystyrene F-2” manufactured by Tosoh Corporation

[0059] “TSKgel Standard polystyrene F-4” manufactured by Tosoh Corporation

[0060] “TSKgel Standard polystyrene F-10” manufactured by Tosoh Corporation

[0061] “TSKgel Standard polystyrene F-20” manufactured by Tosoh Corporation

[0062] “TSKgel Standard polystyrene F-40” manufactured by Tosoh Corporation

[0063] “TSKgel Standard polystyrene F-80” manufactured by Tosoh Corporation

[0064] “TSKgel Standard polystyrene F-128” manufactured by Tosoh Corporation

[0065] “TSKgel Standard polystyrene F-288” manufactured by Tosoh Corporation

[0066] “TSKgel Standard polystyrene F-550” manufactured by Tosoh Corporation

Example 1: Synthesis of Aqueous Resin Composition (1)

[0067] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 60 parts by mass of polycarbonate diol (“DURANOL G4672” manufactured by Asahi Kasei Chemicals Corporation, number-average molecular weight 2000; hereinafter abbreviated as “polycarbonate diol (A-1)”) made from 1,4-butanediol as an essential raw material and 144.7 parts by mass of diethylene glycol dimethyl ether were added. The temperature in the flask was raised to 135° C. Then, a mixture of 45 parts by mass of cyclohexyl methacrylate, 259.0 parts by mass of methyl methacrylate, 9.5 parts by mass of butyl acrylate, 125.2 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 15 parts by mass of cyclohexyl methacrylate, 86.3 parts by mass of methyl methacrylate, 4.0 parts by mass of butyl acrylate, 41.8 parts by mass of 2-hydroxyethyl methacrylate, 15.4 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 686.9 parts by mass of ion-exchange water, resulting in an aqueous resin composition (1). The aqueous resin composition (1) had a non-volatile content of 46.3% and a weight-average molecular weight (Mw) of 12,000.

Example 2: Synthesis of Aqueous Resin Composition (2)

[0068] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 60 parts by mass of polycarbonate diol (A-1) and 144.7 parts by mass of diethylene glycol dimethyl ether were added, and the temperature in the flask was raised to 135° C. Then, a mixture of 90 parts by mass of cyclohexyl methacrylate, 220.7 parts by mass of methyl methacrylate, 2.7 parts by mass of butyl acrylate, 125.1 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 30 parts by mass of cyclohexyl methacrylate, 73.6 parts by mass of methyl methacrylate, 0.9 parts by mass of butyl acrylate, 41.7 parts by mass of 2-hydroxyethyl methacrylate, 15.6 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 686.9 parts by mass of ion-exchange water, resulting in an aqueous resin composition (2). The aqueous resin composition (2) had a non-volatile content of 46.2% and a weight-average molecular weight (Mw) of 13,000.

Example 3: Synthesis of Aqueous Resin Composition (3)

[0069] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 60 parts by mass of polycarbonate diol (“DURANOL T4671” manufactured by Asahi Kasei Chemicals Corporation, number-average molecular weight 1000; hereinafter abbreviated as “polycarbonate diol (A-2)”) made from 1,4-butanediol as an essential raw material and 144.7 parts by mass of diethylene glycol dimethyl ether were added. The temperature in the flask was raised to 135° C. Then, a mixture of 90 parts by mass of cyclohexyl methacrylate, 220.7 parts by mass of methyl methacrylate, 2.7 parts by mass of butyl acrylate, 125.1 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 30 parts by mass of cyclohexyl methacrylate, 73.6 parts by mass of methyl methacrylate, 0.9 parts by mass of butyl acrylate, 41.7 parts by mass of 2-hydroxyethyl methacrylate, 15.6 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 686.9 parts by mass of ion-exchange water, resulting in an aqueous resin composition (3). The aqueous resin composition (3) had a non-volatile content of 46.0% and a weight-average molecular weight (Mw) of 13,000.

Example 4: Synthesis of Aqueous Resin Composition (4)

[0070] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 60 parts by mass of polycarbonate diol (“DURANOL G3452” manufactured by Asahi Kasei Chemicals Corporation, number-average molecular weight 2000; hereinafter abbreviated as “polycarbonate diol (A-3)”) made from 1,4-butanediol as an essential raw material and 144.7 parts by mass of diethylene glycol dimethyl ether were added. The temperature in the flask was raised to 135° C. Then, a mixture of 90 parts by mass of cyclohexyl methacrylate, 220.7 parts by mass of methyl methacrylate, 2.7 parts by mass of butyl acrylate, 125.1 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 30 parts by mass of cyclohexyl methacrylate, 73.6 parts by mass of methyl methacrylate, 0.9 parts by mass of butyl acrylate, 41.7 parts by mass of 2-hydroxyethyl methacrylate, 15.6 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 686.9 parts by mass of ion-exchange water, resulting in an aqueous resin composition (4). The aqueous resin composition (4) had a non-volatile content of 45.9% and a weight-average molecular weight (Mw) of 12,000.

Example 5: Synthesis of Aqueous Resin Composition (5)

[0071] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 60 parts by mass of polycarbonate diol (A-1) and 144.7 parts by mass of diethylene glycol dimethyl ether were added, and the temperature in the flask was raised to 135° C. Then, a mixture of 90 parts by mass of cyclohexyl methacrylate, 200.3 parts by mass of methyl methacrylate, 1.8 parts by mass of butyl acrylate, 146.3 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 30 parts by mass of cyclohexyl methacrylate, 66.8 parts by mass of methyl methacrylate, 0.6 parts by mass of butyl acrylate, 48.8 parts by mass of 2-hydroxyethyl methacrylate, 15.6 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 686.9 parts by mass of ion-exchange water, resulting in an aqueous resin composition (5). The aqueous resin composition (5) had a non-volatile content of 44.5% and a weight-average molecular weight (Mw) of 13,000.

Example 6: Synthesis of Aqueous Resin Composition (6)

[0072] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 120 parts by mass of polycarbonate diol (A-1) and 159.5 parts by mass of diethylene glycol dimethyl ether were added, and the temperature in the flask was raised to 135° C. Then, a mixture of 90 parts by mass of cyclohexyl methacrylate, 220.7 parts by mass of methyl methacrylate, 2.7 parts by mass of butyl acrylate, 125.1 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 30 parts by mass of cyclohexyl methacrylate, 73.6 parts by mass of methyl methacrylate, 0.9 parts by mass of butyl acrylate, 41.7 parts by mass of 2-hydroxyethyl methacrylate, 15.6 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 746.9 parts by mass of ion-exchange water, resulting in an aqueous resin composition (5). The aqueous resin composition (5) had a non-volatile content of 44.3% and a weight-average molecular weight (Mw) of 12,000.

Comparative Example 1: Synthesis of Aqueous Resin Composition (R1)

[0073] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 30 parts by mass of polycarbonate diol (A-1) and 137.2 parts by mass of diethylene glycol dimethyl ether were added, and the temperature in the flask was raised to 135° C. Then, a mixture of 296.7 parts by mass of methyl methacrylate, 16.5 parts by mass of butyl acrylate, 125.2 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 98.9 parts by mass of methyl methacrylate, 5.5 parts by mass of butyl acrylate, 41.8 parts by mass of 2-hydroxyethyl methacrylate, 15.4 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 656.2 parts by mass of ion-exchange water, resulting in an aqueous resin composition (R1). The aqueous resin composition (R1) had a non-volatile content of 43.9% and a weight-average molecular weight (Mw) of 12,000.

Comparative Example 2: Synthesis of Aqueous Resin Composition (R2)

[0074] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 30 parts by mass of polycarbonate diol (A-3) and 137.2 parts by mass of diethylene glycol dimethyl ether were added, and the temperature in the flask was raised to 135° C. Then, a mixture of 296.6 parts by mass of methyl methacrylate, 16.7 parts by mass of butyl acrylate, 125.1 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 98.9 parts by mass of methyl methacrylate, 5.6 parts by mass of butyl acrylate, 41.7 parts by mass of 2-hydroxyethyl methacrylate, 15.6 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 656.2 parts by mass of ion-exchange water, resulting in an aqueous resin composition (R2). The aqueous resin composition (R2) had a non-volatile content of 43.9% and a weight-average molecular weight (Mw) of 12,000.

Comparative Example 3: Synthesis of Aqueous Resin Composition (R3)

[0075] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 60 parts by mass of polycarbonate diol (“DURANOL T5652” manufactured by Asahi Kasei Chemicals Corporation, number-average molecular weight 2000; hereinafter abbreviated as “polycarbonate diol (RA-1)”) and 144.7 parts by mass of diethylene glycol dimethyl ether were added. The temperature in the flask was raised to 135° C. Then, a mixture of 90 parts by mass of cyclohexyl methacrylate, 220.7 parts by mass of methyl methacrylate, 2.7 parts by mass of butyl acrylate, 125.1 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 30 parts by mass of cyclohexyl methacrylate, 73.6 parts by mass of methyl methacrylate, 0.9 parts by mass of butyl acrylate, 41.7 parts by mass of 2-hydroxyethyl methacrylate, 15.6 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 686.9 parts by mass of ion-exchange water, resulting in an aqueous resin composition (R3). The aqueous resin composition (R4) had a non-volatile content of 45.1% and a weight-average molecular weight (Mw) of 13,000.

Comparative Example 5: Synthesis of Aqueous Resin Composition (R4)

[0076] To a flask equipped with a condenser, a thermometer, a dropping funnel, and a stirrer, 60 parts by mass of polycarbonate diol (“DURANOL T5650J” manufactured by Asahi Kasei Chemicals Corporation, number-average molecular weight 800; hereinafter abbreviated as “polycarbonate diol (RA-2)”) and 144.7 parts by mass of diethylene glycol dimethyl ether were added. The temperature in the flask was raised to 135° C. Then, a mixture of 90 parts by mass of cyclohexyl methacrylate, 220.7 parts by mass of methyl methacrylate, 2.7 parts by mass of butyl acrylate, 125.1 parts by mass of 2-hydroxyethyl methacrylate, and 17.5 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over three hours. Then, a mixture of 30 parts by mass of cyclohexyl methacrylate, 73.6 parts by mass of methyl methacrylate, 0.9 parts by mass of butyl acrylate, 41.7 parts by mass of 2-hydroxyethyl methacrylate, 15.6 parts by mass of acrylic acid, and 15.4 parts by mass of tert-butylperoxy-2-ethyl hexanoate was added dropwise over one hour. After completion of the addition, the mixture was stirred at the same temperature for two hours and then cooled to 95° C. After 15.3 parts by mass of dimethylethanolamine was added, the mixture was stirred for 30 minutes. In addition, the mixture was dispersed in water by adding 686.9 parts by mass of ion-exchange water, resulting in an aqueous resin composition (R5). The aqueous resin composition (R5) had a non-volatile content of 45.6% and a weight-average molecular weight (Mw) of 12,000.

[0077] The compositions and the evaluation results of the aqueous resin compositions (1) to (6) obtained as described above are listed in Table 1.

TABLE-US-00001 TABLE 1 Example Example Example Example Example Example 1 2 3 4 5 6 Aqueous resin composition (1) (2) (3) (4) (5) (6) Composition Polycarbonate diol (A-1) 10 10 10 20 (parts by (A-2) 10 mass) (A-3) 10 Unsaturated MMA 57.5 49.0 49.0 49.0 44.5 49.0 monomer Unsaturated HEMA 27.8 27.8 27.8 27.8 32.5 27.8 mixture monomer (b1) Unsaturated AA 2.6 2.6 2.6 2.6 2.6 2.6 monomer (b2) Unsaturated CHMA 10.0 20.0 20.0 20.0 20.0 20.0 monomer (b3) Unsaturated BA 2.1 0.6 0.6 0.6 0.4 0.6 monomer (b4) Mass ratio (%) of 10.0 20.0 20.0 20.0 20.0 20.0 unsaturated monomer (b3) Polycarbonate diol/unsaturated monomer 10/100 10/100 10/100 10/100 10/100 20/100 mixture (mass ratio) Weight-average molecular weight 12,000 13,000 13,000 12,000 13,000 13,000

[0078] The abbreviations in Table 1 and Table 2 are as follows.

[0079] MMA: Methyl methacrylate

[0080] HEMA: 2-Hydroxyethyl methacrylate

AA: Acrylic acid
CHMA: Cyclohexyl methacrylate
BA: Butyl acrylate

[0081] The compositions of the comparative aqueous resin compositions (R1) to (R4) obtained as described above are listed in Table 2.

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Aqueous resin composition (R1) (R2) (R4) (R5) Composition Polycarbonate diol (A-1) 5 (parts by (A-3) 5 mass) (RA-1) 10 (RA-2) 10 Unsaturated MMA 65.9 65.9 49.0 49.0 monomer mixture Unsaturated HEMA 27.8 27.8 27.8 27.8 monomer (b1) Unsaturated AA 2.6 2.6 2.6 2.6 monomer (b2) Unsaturated CHMA 20.0 20.0 monomer (b3) Unsaturated BA 3.7 3.7 0.6 0.6 monomer (b4) Mass ratio (%) of 0 0 20.0 20.0 unsaturated monomer (b3) Polycarbonate diol/unsaturated monomer 5/100 5/100 10/100 10/100 mixture (mass ratio) Weight-average molecular weight 12,000 12,000 13,000 13,000

Examples 7 to 12: Preparation and Evaluation of Paints (1) to (6)

[Preparation of Aqueous Paint]

[0082] The aqueous resin composition obtained as described above and a curing agent (“BURNOCK DNW-5500” manufactured by DIC Corporation, water-dispersible polyisocyanate) were blended. The hydroxy equivalent weight in the polycarbonate-modified acrylic resin and the isocyanate equivalent weight in the curing agent were set to be 1.0:1.2. Then, an aqueous paint was prepared by diluting the mixture with ion-exchange water so that the viscosity determined by “Viscosity Cup NK-2” manufactured by ANEST IWATA Corporation indicated approximately 13 seconds (23° C.)

[Preparation of Cured Coating Film X for Evaluation]

[0083] The aqueous paint obtained as described above was applied to an ABS (acrylonitrile-butadiene-styrene copolymer) substrate (50 mm×70 mm×1 mm) by spraying to a film thickness of approximately 25 pm after drying, and then heated and dried in a dryer at 80° C. for 30 minutes, followed by drying at 25° C. for seven days to produce a cured coating film X for evaluation.

[Preparation of Cured Coating Film Y for Evaluation]

[0084] The aqueous paint obtained as described above was applied to a PC (polycarbonate) substrate (50 mm×70 mm×1 mm) by spraying to a film thickness of approximately 25 pm after drying, and then heated and dried in a dryer at 80° C. for 30 minutes, followed by drying at 25° C. for seven days to produce a cured coating film Y for evaluation.

[Adhesion Evaluation]

[0085] Using a cutter, cuts having a width of 1 mm were made in the cured coating film for evaluation obtained as described above to make a grid pattern of 100 squares. Then, an adhesive tape was affixed to cover the entire grid pattern and peeled off quickly. This operation was repeated four times. The adhesion was evaluated by the following criteria, based on the number of squares of the grid pattern kept adhering.

[0086] A: 100

[0087] B: 99 to 90

[0088] C: 89 to 70

[0089] D: 69 or less

[Evaluation of Water-Resistant Adhesion]

[0090] After the cured coating film for evaluation obtained as described above was immersed in water at 40° C. for 240 hours, the same operation as in the adhesion evaluation was performed, and the water-resistant adhesion was evaluated by the following criteria.

[0091] A: 100

[0092] B: 99 to 90

[0093] C: 89 to 70

[0094] D: 69 or less

[Evaluation of Fragrance Resistance]

[0095] A 15 mm×15 mm piece cut from an air freshener (Little Trees Air Freshener “Royal Pine”) was placed on the cured coating film X for evaluation obtained as described above, and dried at 74° C. for four hours while being loaded with a weight of 500 g. Subsequently, the air freshener was removed by hand, and the appearance of the cured coating film was visually observed, and the fragrance resistance was evaluated by the following criteria.

[0096] 5: No traces or some slight traces

[0097] 4: Slight traces all over

[0098] 3: Traces found

[0099] 2: Air freshener removable but substrate exposed

[0100] 1: Air freshener sticky and unremovable from substrate

Comparative Examples 5 to 8: Preparation and Evaluation of Aqueous Paints (R1) to (R4)

[0101] An aqueous paint was prepared by the same operation as in Examples and then a coating film for evaluation was prepared and evaluated.

[0102] The evaluation results of the aqueous paints (1) to (6) obtained as described above are listed in Table 3.

TABLE-US-00003 TABLE 3 Example Example Example Example Example Example 7 8 9 10 11 12 Aqueous paint (1) (2) (3) (4) (5) (6) Evaluation Adhesion (ABS substrate) A A A A A A Adhesion (PC substrate) A A A A A A Water-resistant adhesion (ABS substrate) A A A A A A Water-resistant adhesion (PC substrate) A A A B A A Fragrance resistance 5 5 5 5 5 5

[0103] The evaluation results of the paints (R1) to (R4) obtained above are listed in Table 4.

TABLE-US-00004 TABLE 4 Comparative Comparative Comparative Comparative Example 5 Example 6 Example 7 Example 8 Aqueous paint (R1) (R2) (R3) (R4) Evaluation Adhesion (ABS substrate) D D A A Adhesion (PC substrate) D D B B Water-resistant adhesion D D B B (ABS substrate) Water-resistant adhesion D D B B (PC substrate) Fragrance resistance 4 4 2 2

[0104] The results demonstrated that the cured coating films obtained in Examples 1 to 6 that are the aqueous resin compositions of the present invention have high adhesion, water-resistant adhesion, and fragrance resistance (Examples 7 to 12).

[0105] On the other hand, Comparative Examples 1 and 2, which are examples in which the unsaturated monomer mixture (B) does not contain the unsaturated monomer (b3) having an alicyclic structure, demonstrated that the adhesion and the water-resistant adhesion of the resulting coating films were inferior (Comparative Examples 5 and 6).

[0106] Comparative Examples 3 and 4, which are examples in which a polycarbonate diol made from 1,4-butanediol as an essential raw material is not used, demonstrated that the fragrance resistance of the resulting cured coating film was inferior (Comparative Examples 7 and 8).