Thermosetting composition, paint finishing method and method for producing a painted article

Abstract

The present invention relates to a thermosetting composition characterized in that it contains (A) a polyester resin of number average molecular weight 1,000-10,000, hydroxyl value 5-200 mg KOH/g and, (B) 0.5-2.0 equivalents relative to the hydroxyl groups of the aforesaid component (A) of a compound (B) which is a blocked aliphatic isocyanate compound having reactivity with the hydroxyl groups of component (A), wherein the blocking is with methyl ethyl ketoxime and/or ε-caprolactam, (C) 0.05-5 parts by weight of a bismuth compound, per 100 parts by weight of total resin solids of component (A) and component (B), and (D) 0.5-50 parts by weight of an organosilicate represented by the following general formula (I) and/or a condensation product thereof, relative to 100 parts by weight of total resin solids of component (A) and component (B) wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 in the formula each mean hydrogen atom or 1-10 carbon organic group, and can be the same or different, n is 1. By using the thermosetting, not only does stain resistance appear a short time after painting, but also excellent stain resistance is maintained for a long period, which fulfil the paint film performance requirements for painted steel sheet such as water resistance and bending workability and which have high environmental protection qualities and safety. ##STR00001##

Claims

1. A thermosetting composition comprising (A) a polyester resin of number average molecular weight 1,000-10,000, hydroxyl value 5-200 mg KOH/g, wherein the polyester resin is the reaction product of from 22.5 to 24.5 parts by weight of solids of isophthalic acid, from 14.8 to 18.8 parts by weight of solids of phthalic anhydride, from 16.5 to 19.3 parts by weight of solids of adipic acid, from 10.2 to 34.1 parts by weight of solids of neopentyl glycol, from 4.4 to 8.5 parts by weight of solids of 1,6-hexanediol, and from 0.5 to 31.5 parts by weight of solids of trimethylolpropane; (B) a compound (B) which is hexamethylenediisocyanate or isophorone diisocyanate each of which has NCO groups blocked with methyl ethyl ketoxime and/or ε-caprolactam, wherein the amount of the compound (B) is an amount that provides 0.5-2.0 molar equivalents of blocked NCO relative to the hydroxyl groups of the polyester resin (A); (C) 0.5-3.0 parts by weight of a bismuth compound, per 100 parts by weight of total resin solids of component (A) and component (B), wherein the bismuth compound is bismuth tris(2-ethylhexanoate) or bismuth tris(isostearate) or bismuth carboxylate; (D) 1.0-20 parts by weight of an organosilicate represented by the following general formula (I) and/or a condensation product thereof, relative to 100 parts by weight of total resin solids of component (A) and component (B), ##STR00004## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently represent hydrogen, methyl or ethyl, and n is 1; and (E) 0.5-50 parts by weight, per 100 parts by weight of total resin solids of component (A) and component (B), of a compound (E) selected from trimethyl orthoacetate, triethyl orthoformate and triethyl orthopropionate.

2. A method for paint finishing of a metal sheet, the method comprising applying the thermosetting composition as claimed in claim 1 onto a metal sheet, and thermally curing the thermosetting composition.

3. The method for paint finishing as claimed in claim 2, wherein the thermosetting composition is applied with a roller coater.

4. The method for paint finishing as claimed in claim 3, wherein the aforesaid metal sheet is any of: a cold rolled steel sheet, a galvanized steel sheet, an aluminum-zinc plated steel sheet, a zinc-magnesium-plated steel sheet, an aluminum-zinc-magnesium-plated steel sheet, a stainless steel sheet, an aluminum sheet and an aluminum alloy sheet.

5. The method for paint finishing as claimed in claim 2, wherein the aforesaid metal sheet is any of: a cold rolled steel sheet, a galvanized steel sheet, an aluminum-zinc plated steel sheet, a zinc-magnesium-plated steel sheet, an aluminum-zinc-magnesium-plated steel sheet, a stainless steel sheet, an aluminum sheet and an aluminum alloy sheet.

6. A method for paint finishing of a metal sheet, the method comprising applying an undercoat paint onto the metal sheet and thermally curing the undercoat paint to form an undercoat layer, optionally applying a midcoat paint on top of the undercoat layer and thermally curing the midcoat paint to form a midcoat layer, and applying the thermosetting composition as claimed in claim 1 on top of the paint layer(s) as a topcoat paint and thermally curing the thermosetting composition.

7. The method for paint finishing as claimed in claim 6, wherein the thermosetting composition is applied with a roller coater.

8. The method for paint finishing as claimed in claim 6, wherein the aforesaid metal sheet is any of: a cold rolled steel sheet, a galvanized steel sheet, an aluminum-zinc plated steel sheet, a zinc-magnesium-plated steel sheet, an aluminum-zinc-magnesium-plated steel sheet, a stainless steel sheet, an aluminum sheet and an aluminum alloy sheet.

9. A method for the production of a painted article, the method comprising applying the thermosetting composition as claimed in claim 1 onto an outer metal sheet of an article, and thermally curing the thermosetting composition.

10. The method for the production of a painted article as claimed in claim 9, wherein the thermosetting composition is applied with a roller coater.

11. The method for the production of a painted article as claimed in claim 9, wherein the aforesaid outer metal sheet is any of: a cold rolled steel sheet, a galvanized steel sheet, an aluminum-zinc plated steel sheet, a zinc-magnesium-plated steel sheet, an aluminum-zinc-magnesium-plated steel sheet, a stainless steel sheet, an aluminum sheet and an aluminum alloy sheet.

12. A method for the production of a painted article, the method comprising applying an undercoat paint onto an outer metal sheet of an article and thermally curing the undercoat paint to form an undercoat layer, optionally applying a midcoat paint on top of the undercoat layer and thermally curing the midcoat paint to form a midcoat layer, and applying the thermosetting composition as claimed in claim 1 on top of the paint layer(s) as a topcoat paint and thermally curing the thermosetting composition.

13. A painted article produced by the method of claim 9.

14. A painted article produced by the method of claim 10.

15. A painted article produced by the method of claim 11.

16. A painted article produced by the method of claim 12.

Description

EXAMPLES

(1) Below, the present invention is explained in more detail by giving practical examples, but the present invention is not limited to these. Also, unless especially stated, parts, % and ratio in each example respectively represent parts by weight, weight % and weight ratio.

Production Example: Production of Polyester Resin Solutions Pe-1 to 13

(2) The monomers shown in Table 1 were placed in a flask fitted with thermometer, Dean-Stark tube, reflux condenser, nitrogen feed tube and stirrer, gradually heated to 240° C. with stirring, a reflux solvent (xylene) was introduced and a dehydrative condensation polymerization reaction performed. When the acid value reached the values shown in Table 1, the mixture was diluted by adding a mixed solvent (aromatic solvent (brand name “Solvesso 100”, Exxon Mobile Chemical Corp.)/cyclohexanone=50/50 (weight ratio) such that the solids content was 50%. As a result, the hydroxyl group-containing polyester resin solutions P-1 to 13 with solid fractions having the properties shown in Table 1 were obtained as components (A).

(3) TABLE-US-00001 TABLE 1 1. Polyester resin production examples 2. polyester resin solutions PE-1 PE-2 PE-3 PE-4 PE-5 PE-6 PE-7 3. monomer 4. isophthalic acid a 22.5 22.5 22.5 22.5 22.5 22.5 22.5 (parts by polybasic phthalic anhydride b 14.8 14.8 14.8 14.8 14.8 14.8 14.8 weight) carboxylic adipic acid c 19.43 18.66 18.88 19.3 19.43 19.97 19.45 acid 5. neopenty glycol a 23.6 32.3 29.8 21.6 20.2 41.5 19.5 polyhydric 1,6-hexanediol b 8.5 8.5 8.5 8.5 8.5 1.1 8.5 alcohol trimethylolpropane c 11.17 3.24 5.52 13.3 14.57 0.13 15.25 6. acid value 10 10 10 3 3 43 2 7. solid fraction ratio (%) 50% 50% 50% 50% 50% 50% 50% 8. solid fraction number average a 3,000 1,600 1,750 5,500 8,000 800 11,000 properties molecular weight hydroxyl b 80 80 80 80 80 80 80 value (mgKOH/g) 2. polyester resin solutions PE-8 PE-9 PE-10 PE-11 PE-12 PE-13 3. monomer 4. isophthalic acid a 24.5 23.5 22.5 22.5 26.5 22.5 (parts by weight) polybasic phthalic anhydride b 18.8 16.8 14.8 14.8 20.8 14.8 carboxylic adipic acid c 16.58 18.22 17.41 16.56 14.01 15.53 acid 5. neopenty glycol a 34.1 30.5 13.8 10.2 35.5 6.3 polyhydric 1,6-hexanediol b 5.5 5.5 8.5 4.4 2.5 1.1 alcohol trimethylolpropane c 0.52 5.48 22.99 31.54 0.69 39.77 6. acid value 25 18 5 5 37 3 7. solid fraction ratio (%) 50% 50% 50% 50% 50% 50% 8. solid fraction number average a 3,000 3,000 3,000 3,000 3,000 3,000 properties molecular weight hydroxyl b 15 45 140 180 4 220 value (mgKOH/g)

(4) Production of Thermosetting Compositions PA-1 to PA-42

(5) Among the components stated in the following Table 2, titanium dioxide and the components (A) were mixed, introduced into a ring mill and dispersed until the titanium dioxide particle size was 10 μm or less. After this, the respective components stated in Table 2 were added and mixed in to give the thermosetting compositions PA-1 to PA-42. The viscosities of the thermosetting compositions PA-1 to PA-42 obtained were adjusted to Ford Cup No. 4 80±10 secs with mixed solvent (aromatic solvent (brand name “Solvesso 100”, Exxon Mobile Chemical Corp.)/cyclohexanone=50/50 (weight ratio).

(6) TABLE-US-00002 TABLE 2 1. Table 2A: thermosetting composition production examples 1. 2. thermosetting composition PA- PA- PA- PA- PA- PA- PA- PA- PA-1 PA-2 PA-3 PA-4 PA-5 PA-6 PA-7 PA-8 PA-9 10 11 12 13 14 15 16 17 3. titanium dioxide 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 4. A: polyester resin PE-1 (calc. solids content) 71.2 79.1 77.1 62.2 52.2 89.2 45.4 70.0 66.7 71.2 79.1 71.2 71.2 67.5 70.3 70.3 71.2 B: B-1 28.8 37.8 10.8 28.8 28.8 28.8 28.8 blocked B-2 20.9 47.8 54.6 20.9 32.5 isocyanate B-3 22.9 29.7 29.7 (calc. solids B-4 30.0 content) B-5 33.3 C: C-1 0.5 0.5 0.5 3.0 bismuth C-2 0.5 compound C-3 0.5 0.5 0.5 0.5 0.5 0.03 6.0 or other C-4 0.5 0.5 (calc. solids C-5 0.5 content) C-6 0.5 C-7 0.5 D: D-1 5.0 5.0 5.0 5.0 5.0 5.0 organosilicate D-2 5.0 5.0 5.0 5.0 5.0 5.0 5.0 D-3 5.0 5.0 5.0 5.0 E: E-1 5.0 5.0 5.0 5.0 5.0 5.0 compound (E) E-2 5.0 5.0 5.0 5.0 5.0 E-3 5.0 5.0 5.0 5.0 5.0 5.0 5. equivalents of 1 0.55 0.7 1.5 1.9 0.3 2.5 1 1 1 0.55 1 1 1 1 1 1 component (B) relative to hydroxyl groups of component (A). Table 2B: thermosetting composition production examples 1. 2. thermosetting composition PA-18 PA-19 PA-20 PA-21 PA-22 PA-23 PA-24 PA-25 PA-26 PA-27 PA-28 PA-29 PA-30 3. titanium dioxide 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 A: polyester resin PE-1 4. (calc. solids content) 67.5 70.3 71.2 67.5 71.2 70.3 71.2 67.5 71.2 70.3 71.2 67.5 70.3 B: blocked B-1 28.8 28.8 28.8 28.8 28.8 isocyanate B-2 32.5 32.5 32.5 32.5 (calc. solids B-3 29.7 29.7 29.7 29.7 content) B-4 B-5 C: bismuth C-1 0.5 0.5 0.5 compound C-2 0.5 0.5 0.5 or other C-3 0.5 0.5 0.5 (calc. solids C-4 0.5 0.5 content) C-5 0.5 0.5 C-6 C-7 D: organosilicate D-1 3.0 0.4 5.0 5.0 D-2 10.0 55.0 5.0 5.0 D-3 1.0 20.0 5.0 5.0 E. compound (E) E-1 5.0 5.0 5.0 0.3 2.0 E-2 5.0 5.0 10.0 E-3 5.0 5.0 0.5 20.0 5. equivalents of 1 1 1 1 1 1 1 1 1 1 1 1 1 component (B) relative to hydroxyl groups of component (A) 6. total resin 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 solids content X of component (A) and component (B) 7. weight % of 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 component (C) relative to total weight X 8. weight % of 1.0 3.0 10.0 20.0 0.0 0.4 55.0 5.0 5.0 5.0 5.0 5.0 5.0 component (D) relative to total weight X 9. weight % of 5.0 5.0 5.0 5.0 5.0 5.0 5.0 0.0 0.3 0.5 2.0 10.0 20.0 component (E) relative to total weight X 1. Table 2C thermosetting composition production examples; 2. thermosetting composition PA-31 PA-32 PA-33 PA-34 PA-35 PA-36 PA-37 PA-38 PA-39 PA-40 PA-41 PA-42 3. titanium dioxide 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 4. A: polyester resin PE-2 PE-3 PE-4 PE-5 PE-6 PE-7 PE-8 PE-9 PE-10 PE-11 PE-12 PE-13 (calc. solids content) 70.3 71.2 87.5 70.3 71.2 67.5 92.7 81.4 54.2 51.2 98.0 43.1 B: blocked isocyanate B-1 28.8 28.8 18.6 2.0 (calc. solids content) B-2 32.5 32.5 45.8 56.9 B-3 29.7 29.7 7.3 48.8 B-4 B-5 C: bismuth compound C-1 0.5 0.5 0.5 or other C-2 0.5 0.5 0.5 (calc. solids content) C-3 0.5 0.5 C-4 0.5 0.5 C-5 0.5 0.5 C-6 C-7 D: organosilicate D-1 5.0 5.0 5.0 5.0 D-2 5.0 5.0 5.0 5.0 D-3 5.0 5.0 5.0 5.0 E: compound (E) E-1 5.0 5.0 5.0 5.0 E-2 5.0 5.0 5.0 5.0 E-3 5.0 5.0 5.0 5.0 5. equivalents of component (B) 1 1 1 1 1 1 1 1 1 1 1 1 relative to hydroxyl groups of component (A) 6. total resin solids content X of 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 component (A) and component (B) 7. weight % of component (C) 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 relative to total weight X 8. weight % of component (D) 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 relative to total weight X 9. weight % of component (E) 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 relative to total content X

(7) Here, the components used in Table 2 are as follows.

(8) Component (B)

(9) B-1: Desmodur BL3175 Sumika Bayer Urethane Corp., MEK oxime-blocked isocyanate, monomer type HDI, solids content 75%, NCO equivalents 378

(10) B-2: Desmodur BL4265 Sumika Bayer Urethane Corp., MEK oxime-blocked isocyanate, monomer type IPDI, solids content 65%, NCO equivalents 519

(11) B-3: Desmodur BL3272 Sumika Bayer Urethane Corp., ε-caprolactam-blocked isocyanate, monomer type HDI, solids content 72%, NCO equivalents 412

(12) B-4: Desmodur BL3575/1 Sumika Bayer Urethane Corp., dimethylpyrazole-blocked isocyanate, monomer type HDI, solids content 75%, NCO equivalents 400

(13) B-5: Product No. 7951 Baxenden Corp., dimethylpyrazole-blocked isocyanate, monomer type IPDI, solids content 65%, NCO equivalents 539.

(14) Component (C)

(15) C-1: Bismuth tris(2-ethylhexanoate) content 100 wt. %

(16) C-2: Bismuth tris(isostearate) content 100 wt. %

(17) C-3: K-KAT XK-628 King Industries Corp., bismuth carboxylate salts content 100 wt. %

(18) C-4: K-KAT XK-640 King Industries Corp., bismuth carboxylate salts content 55 wt. %

(19) C-5: K-KAT XC-227 King Industries Corp., bismuth complex content 87.5 Wt. %

(20) C-6: Dibutyltin dilaurate content 100 wt. %

(21) C-7: K-KAT XK-635 King Industries Corp., organozinc complex 100 wt. %

(22) Component (D)

(23) D-1: MKC Silicate MS56 Mitsubishi Chemical Corp.

(24) D-2: MKC Silicate MS58B30 Mitsubishi Chemical Corp.

(25) D-3: EMS-485 Colcoat Corp.

(26) Component (E)

(27) E-1: trimethyl orthoacetate

(28) E-2: triethyl orthoformate

(29) E-3: triethyl orthopropionate

(30) Preparation of Test Pieces

(31) Test pieces were prepared according to the following methods (1) to (3), by the 2 coat 2 bake, or 3 coat 3 bake methods.

(32) (1) Undercoat Painting

(33) (1-1) Application of Epoxy Resin Undercoat Paint

(34) The undercoat paint film was formed by applying an epoxy resin undercoat paint (brand name “Precolor Primer HP32”, BASF Japan (Corp.)) onto 0.35 mm thick passivated aluminum/zinc alloy plated steel sheet (Al55%) with a bar coater to give a dry film thickness of 5 μm, and baking in a hot air dryer for 40 secs at a maximum attained sheet temperature of 210° C.

(35) (1-2) Application of Polyester Urethane Undercoat Paint

(36) An undercoat paint film was formed by applying a polyester urethane undercoat paint (brand name “Coiltec U HP 300”, BASF Japan (Corp.)) onto the same material as in (1-1) with a bar coater to give a dry film thickness of 25 μm, and baking in a hot air dryer for 40 secs at a maximum attained sheet temperature of 230° C.

(37) (2) Application of Midcoat

(38) In practical examples 4-5, a midcoat paint film was formed by applying the thermosetting composition PA-22 as midcoat onto the undercoat painted sheet previously painted by the method of (1-2) with a bar coater to give a dry film thickness of 5 μm, and baking in a hot air dryer for 40 secs at a maximum attained sheet temperature of 230° C.

(39) (3) Preparation of Topcoat Painted Sheet

(40) The thermosetting compositions PA-1 to 42 were charged into test roller coater paint machines, and while continuously rotating the pickup roller and applicator roller under the conditions in Table 3, they were intermittently applied onto (1) the undercoat painted sheet or (2) the midcoat painted sheet under the 3 conditions directly after charging, 2 hours afterwards and 4 hours afterwards, and test pieces were obtained by forming the topcoat paint films by baking in a hot air dryer for 40 secs at a maximum attained sheet temperature of 230° C.

(41) TABLE-US-00003 TABLE 3 Roller coater paint machine operating conditions Pickup roller Applicator roller Backing roller peripheral speed peripheral speed peripheral speed (m/min) (m/min) (m/min) When idling 20 20 — When painting 50 80 65

(42) The following paint film performance assessments were performed on the 3 topcoat painted sheets obtained in each practical example and comparative example, and the results are shown in Table 4. Also, it is preferable that not only the articles (painted sheets) painted directly afterwards, but also those painted 2 hours afterwards and 4 hours afterwards, show satisfactory performance.

(43) (i) 60° specular gloss retention

(44) The 60° specular gloss values of the sheets painted directly afterwards, 2 hours afterwards and 4 hours afterwards were measured, and the gloss retention of the sheets painted 2 hours afterwards and 4 hours afterwards was calculated by the following formula (Num. 1), and assessed by the following criteria.
Gloss retention (%)=(60° specular gloss value of target painted sheet)/(60° specular gloss value of sheet painted directly afterwards)×100  [Num. 1]

(45) : 90% or more

(46) ◯: 80% or more, less than 90%

(47) X: less than 80%

(48) (ii) Bending Workability (1)

(49) At 20° C. room temperature, test pieces cut to width 5 cm were bent into a letter U around a cylindrical rod of diameter 10 mm such that the paint film surface was on the outside, then 6 painted sheets identical in thickness to the test piece were placed inside, and subjected to 180° bending with the paint film on the outside. For the assessment, the end parts were inspected with a 10× magnifying glass, and assessed by the following criteria.

(50) : no cracking

(51) ◯: less than 20% cracking

(52) Δ: 20-50% cracking

(53) X: more than 50% cracking

(54) (iii) Bending Workability (2)

(55) At 20° C. room temperature, the test pieces were bent 180° by the same method as in (ii) Bending Workability (1), changing to placing 2 sheets inside. For the assessment, the bent end parts were then peeled with cellophane adhesive tape, and assessed by the following criteria.

(56) : no peeling

(57) ◯: less than 20% peeling

(58) Δ: 20-50% peeling

(59) X: more than 50% peeling

(60) (iv) Bending Workability (3)

(61) At 20° C. room temperature, test pieces cut to width 5 cm, previously immersed in boiling water for 2 hrs, were bent 180° by the same method as in (ii) Bending workability (1), changing to placing 2 sheets inside. For the assessment, the bent end parts were then peeled with cellophane adhesive tape, and assessed by the following criteria.

(62) : no peeling

(63) ◯: less than 20% peeling

(64) Δ: 20-50% peeling

(65) X: more than 50% peeling

(66) (v) Hydrophilicity, Carbon Stain Resistance

(67) Each test piece was immersed in distilled water at room temperature for 12 hrs, then the following tests were performed.

(68) (v-a) Hydrophilicity

(69) The distilled water contact angle with 2 μl liquid drop volume was measured with a Kyowa Interface Science Corp. DM-501 type contact goniometer.

(70) : contact angle=less than 40°

(71) ◯: contact angle=40-50°

(72) X: contact angle=more than 50°

(73) (v-b) Carbon Stain Resistance

(74) A mixture of distilled water:carbon black FW200 (Orion Engineered Carbons (Corp.))=90/10 (weight ratio) was applied onto the painted sheets then dried under the conditions 2 hours at 40° C., and then washed in one direction 30 times with a dish-washing sponge scourer under running water. The color difference (ΔE) before and after testing was measured, and assessed by the following criteria.

(75) : ΔE=less than 2.0

(76) ◯: ΔE=2.0-5.0

(77) X: ΔE=more than 5.0

(78) (vi) Rain Streak Stain Resistance

(79) On a fixed house frontage-modelling platform at the BASF Japan (Corp.) Totsuka Works, test pieces (100 mm×200 mm×0.35 mm) were placed so that the paint surface faced northwards, an exposure test was performed, and test pieces exposed for 6 months were obtained. The condition of the paint surface of each test piece was observed visually, and assessed according to the following criteria:

(80) : no rain streak tracks observed

(81) ◯: rain streak tracks observed to a slight extent

(82) X: rain streak tracks observed.

(83) TABLE-US-00004 TABLE 4 1. Table 4A 2. examples 1 2 3 4 5 6 7 8 9 10 11 12 13 14 3. type i HP32 HP300 HP300 HP300 HP300 HP32 HP32 HP32 HP300 HP300 HP32 HP32 HP32 HP300 Undercoat thickness (μm) ii  5 25 25 25 25  5  5  5 25 25  5  5  5 25 4. type i PA-22 PA-22 Midcoat thickness (μm) ii  5  5 5. type i PA-1 PA-1 PA-2 PA-1 PA-2 PA-3 PA-4 PA-5 PA-10 PA-11 PA-12 PA-13 PA-18 PA-19 Topcoat thickness (μm) ii 20 20 20 20 20 20 20 20 20 20 20 20 20 20 6. paint film performance 7. b-g bending workability (1) ◯ ⊚ ◯ ⊚ ◯ ⊚ ⊚ ◯ ⊚ ◯ ◯ ⊚ ◯ ⊚ directly bending workability (2) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ afterwards bending workability (3) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ◯ ◯ ⊚ hydrophilicity ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ carbon staining ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ rain streak ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ stain resistance 8. a-g % gloss retention ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ 2 hrs bending workability (1) ◯ ⊚ ◯ ⊚ ◯ ⊚ ⊚ ◯ ⊚ ◯ ◯ ⊚ ◯ ⊚ afterwards bending workability (2) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ bending workability (3) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ◯ ◯ ⊚ hydrophilicity ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ carbon staining ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ rain streak ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ stain resistance 9. a-g % gloss retention ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ 4 hrs bending workability (1) ◯ ⊚ ◯ ⊚ ◯ ⊚ ⊚ ◯ ⊚ ◯ ◯ ⊚ ◯ ⊚ afterwards bending workability (2) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ bending workability (3) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ◯ ◯ ⊚ hydrophilicity ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ carbon staining ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ◯ rain streak ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ stain resistance 1. Table 4B 2. Practical example 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 3. type i HP300 HP300 HP300 HP32 HP32 HP300 HP300 HP32 HP32 HP300 HP300 HP32 HP32 HP32 HP300 HP300 Undercoat thickness (μm) ii 25 25 25  5  5 25 25  5  5 25 25  5  5  5 25 25 4. type i PA-20 PA-21 PA-25 PA-26 PA-27 PA-28 PA-29 PA-30 PA-31 PA-32 PA-33 PA-34 PA-37 PA-38 PA-39 PA-40 Topcoat thickness (μm) ii 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 5. paint film performance 6. b-g bending workability (1) ⊚ ◯ ◯ ⊚ ◯ ⊚ ◯ ⊚ ◯ ◯ ◯ ⊚ ⊚ ⊚ ◯ ◯ directly bending workability (2) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ afterwards bending workability (3) ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ hydrophilicity ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ carbon staining ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ◯ ⊚ ⊚ ⊚ rain streak ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ stain resistance 7. a-g % gloss retention ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ 2 hrs bending workability (1) ⊚ ◯ ◯ ⊚ ◯ ⊚ ◯ ⊚ ◯ ◯ ◯ ⊚ ⊚ ⊚ ◯ ◯ afterwards bending workability (2) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ bending workability (3) ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ hydrophilicity ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ carbon staining ⊚ ⊚ ◯ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ◯ ⊚ ⊚ ⊚ rain streak ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ stain resistance 8. a-g % gloss retention ⊚ ⊚ X X ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ 4 hrs bending workability (1) ⊚ ◯ ◯ ⊚ ◯ ⊚ ◯ ⊚ ◯ ◯ ◯ ⊚ ⊚ ⊚ ◯ ◯ afterwards bending workability (2) ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ bending workability (3) ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ hydrophilicity ⊚ ⊚ ◯ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ carbon staining ⊚ ⊚ ◯ ◯ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ◯ ⊚ ⊚ ⊚ rain streak ⊚ ⊚ ◯ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ stain resistance 1. Table 4C 2. Comparative example 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 3. type i HP32 HP300 HP32 HP300 HP300 HP300 HP32 HP32 HP32 HP300 HP300 HP300 HP300 HP32 HP300 undercoat thickness (μm) ii  5 25  5 25 25 25  5  5  5 25 25 25 25  5 25 4. type i PA-6 PA-7 PA-8 PA-9 PA-14 PA-15 PA-16 PA-17 PA-22 PA-23 PA-24 PA-35 PA-36 PA-41 PA-42 topcoat thickness (μm) ii 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 5. paint film performance 6. b-g bending workability (1) ⊚ X ⊚ ◯ ◯ ⊚ ◯ ◯ ⊚ ⊚ X Δ ⊚ ⊚ Δ directly bending workability (2) ⊚ X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ X Δ ⊚ ⊚ Δ afterwards bending workability (3) X X ⊚ ◯ Δ ⊚ ⊚ ⊚ ⊚ ⊚ X X Δ Δ X hydrophilicity ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ carbon staining ◯ ◯ ⊚ ⊚ X ⊚ ⊚ ⊚ X ◯ ⊚ ⊚ X X ⊚ rain streak ◯ ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ X ◯ ⊚ ⊚ X X ⊚ stain resistance 7. a-g % gloss retention ⊚ ⊚ X ◯ ⊚ ◯ X ◯ ⊚ ◯ ⊚ ⊚ ⊚ ⊚ ⊚ 2 hrs bending workability (1) ⊚ X ⊚ ◯ ◯ ⊚ ◯ ◯ ⊚ ⊚ X Δ ⊚ ⊚ Δ afterwards bending workability (2) ⊚ X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ X Δ ⊚ ⊚ Δ bending workability (3) X X ⊚ ◯ Δ ⊚ ⊚ ⊚ ⊚ ⊚ X X Δ Δ X hydrophilicity ⊚ ⊚ X X ⊚ ◯ X X X ◯ ⊚ ⊚ ⊚ ⊚ ⊚ carbon staining X ◯ X X X X X X X X ⊚ ⊚ X X ⊚ rain streak X ⊚ X X ◯ X X X X X ⊚ ⊚ X X ⊚ stain resistance 8. a-g % gloss retention ⊚ ⊚ X X ⊚ X X X ⊚ X ⊚ ⊚ ⊚ ⊚ ⊚ 4 hrs bending workability (1) ⊚ X ⊚ ◯ ◯ ⊚ ◯ ◯ ⊚ ⊚ X Δ ⊚ ⊚ Δ afterwards bending workability (2) ⊚ X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ X Δ ⊚ ⊚ Δ bending workability (3) X X ⊚ ◯ Δ ⊚ ⊚ ⊚ ⊚ ⊚ X X Δ Δ X hydrophilicity ⊚ ⊚ X X ⊚ X X X X X ⊚ ⊚ ⊚ ⊚ ⊚ carbon staining X X X X X X X X X X ⊚ ⊚ X X ⊚ rain streak X ◯ X X X X X X X X ⊚ ⊚ X X ⊚ stain resistance