AQUEOUS WHITE CONDUCTIVE PRIMER COATING COMPOSITION AND METHOD OF FORMING MULTILAYERED COATING FILM USING SAME

Abstract

An aqueous white conductive primer coating composition, includes: a binder component (A); and a carbon nanotube dispersion liquid (B); and a coating film formed by the aqueous white conductive primer coating composition has an L* value of whiteness based on a CIE color-matching function of 80 or more and a surface resistivity of 10.sup.8 Ω/□ or less.

Claims

1. An aqueous white conductive primer coating composition, comprising: a binder component (A); and a carbon nanotube dispersion liquid (B), wherein a coating film formed by the aqueous white conductive primer coating composition has an L* value of whiteness based on a CIE color-matching function of 80 or more and a surface resistivity of 10.sup.8 Ω/□ or less.

2. The aqueous white conductive primer coating composition according to claim 1, wherein the binder component (A) contains at least one selected from an acrylic resin (A1) and a polyolefin resin (A2).

3. The aqueous white conductive primer coating composition according to claim 2, wherein the acrylic resin (A1) is an acrylic resin (A11) which is obtained by polymerizing a polymerizable unsaturated monomer and which contains 10 to 50 parts by mass of isobornyl(meth)acrylate based on 100 parts by mass of the polymerizable unsaturated monomer.

4. The aqueous white conductive primer coating composition according to claim 2, wherein the polyolefin resin (A2) is a polyolefin resin (A21) having a weight average molecular weight in a range of 50,000 to 150,000.

5. The aqueous white conductive primer coating composition according to claim 1, wherein the carbon nanotube dispersion liquid (B) is a carbon nanotube dispersion liquid (B1) satisfying the following (1) to (4): (1) the carbon nanotube dispersion liquid (B1) contains a carbon nanotube (a), a water-soluble resin (b) and water; (2) the carbon nanotube (a) is a single-walled carbon nanotube, and has an average outer diameter of 0.5 nm to 5 nm and a specific surface area of 400 m.sup.2/g to 800 m.sup.2/g in image analysis using a transmission electron microscope; (3) the water-soluble resin (b) is contained in an amount of 400 parts by mass or more and 2000 parts by mass or less based on 100 parts by mass of a carbon component of the carbon nanotube (a); and (4) the carbon nanotube dispersion liquid has a 50% particle diameter (D50 diameter) of 1.5 μm to 40 μm as calculated by laser diffraction particle size distribution measurement.

6. The aqueous white conductive primer coating composition according to claim 1, further comprising a titanium oxide pigment (C).

7. The aqueous white conductive primer coating composition according to claim 6, wherein a content of the titanium oxide pigment (C) is in a range of 50 to 250 parts by mass based on 100 parts by mass of a solid content of the binder component (A).

8. A method for forming a multilayer coating film, the method comprising the following steps (1) to (4): (1) coating a plastic substrate with the aqueous white conductive primer coating composition according to claim 1 to form an uncured white conductive primer layer; (2) electrostatically coating the white conductive primer layer with an interference color base coating composition to form an uncured interference color base layer; (3) electrostatically coating the interference color base layer with a clear coating composition to form an uncured clear layer; and (4) simultaneously baking the coating films of three layers formed by the steps (1) to (3).

Description

EXAMPLES

[0197] The present invention is described more specifically below by referring to Production Examples, Examples and Comparative Examples. However, the present invention is not limited thereto. In each example, “parts” and “%” are based on mass unless otherwise specified. A thickness of the coating film is based on a cured coating film.

Binder Component (A)

Preparation of Acrylic Resin (A1)

Production of Acrylic Resin (A11)

[0198] Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser and the like, 40 parts of ethylene glycol monobutyl ether and 30 parts of isobutyl alcohol were charged, the mixture was heated and stirred, and after reaching 100° C., a mixture of the following monomers and the like was added dropwise over 3 hours. [0199] Styrene: 10 parts [0200] Methyl methacrylate: 18 parts [0201] Isobornyl acrylate: 35 parts [0202] n-butyl acrylate: 10 parts [0203] 2-hydroxyethyl methacrylate: 20 parts [0204] Acrylic acid: 7 parts [0205] 2,2′-azobisisobutyronitrile: 1 part [0206] Isobutyl alcohol: 5 parts

[0207] After the completion of the dropwise addition, the temperature was further maintained at 100° C. for 30 minutes, and then an additional catalyst solution, which is a mixture of 0.5 parts of 2,2′-azobisisobutyronitrile and 10 parts of ethylene glycol monobutyl ether, was added dropwise over 1 hour. After the mixture was further stirred at 100° C. for 1 hour, the mixture was cooled, 15 parts of isobutyl alcohol was added, 4 parts of N,N-dimethylaminoethanol was added when the temperature reached 75° C., and the mixture was stirred for 30 minutes to obtain an acrylic resin (A11-1) solution having a solid content of 50%. The acrylic resin (A11-1) had a hydroxyl value of 86 mgKOH/g, an acid value of 54.5 mgKOH/g, and a number average molecular weight of 22,000.

Production of Acrylic Rresin (A12)

[0208] Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser and the like, 40 parts of ethylene glycol monobutyl ether and 30 parts of isobutyl alcohol were charged, the mixture was heated and stirred, and after reaching 100° C., a mixture of the following monomers and the like was added dropwise over 3 hours. [0209] Styrene: 10 parts [0210] Methyl methacrylate: 38 parts [0211] n-butyl acrylate: 25 parts [0212] 2-hydroxyethyl methacrylate: 20 parts [0213] Acrylic acid: 7 parts [0214] 2,2′-azobisisobutyronitrile: 1 part [0215] Isobutyl alcohol: 5 parts

[0216] After the completion of the dropwise addition, the temperature was further maintained at 100° C. for 30 minutes, and then an additional catalyst solution, which is a mixture of 0.5 parts of 2,2′-azobisisobutyronitrile and 10 parts of ethylene glycol monobutyl ether, was added dropwise over 1 hour. After the mixture was further stirred at 100° C. for 1 hour, the mixture was cooled, 15 parts of isobutyl alcohol was added, 4 parts of N,N-dimethylaminoethanol was added when the temperature reached 75° C., and the mixture was stirred for 30 minutes to obtain an acrylic resin (A12-1) solution having a solid content of 50%. The acrylic resin (A12-1) had a hydroxyl value of 86 mgKOH/g, an acid value of 54.5 mgKOH/g, and a number average molecular weight of 20,000.

Polyolefin Resin (A2)

[0217] Aqueous polyolefin-based resin (A2-1): melting point: 80° C., weight average molecular weight (Mw): 80,000

[0218] Aqueous polyolefin-based resin (A2-2): melting point: 95° C., weight average molecular weight (Mw): 90,000

Polyester Resin

[0219] Esterification reaction was carried out by a common method using trimethylolpropane, cyclohexanedimethanol, isophthalic acid, and adipic acid. Number average molecular weight: 4500, hydroxyl value: 120, acid value: 10

Melamine Resin

[0220] An imino group-containing methylbutyl mixed etherified melamine having a weight average molecular weight of 1200.

Blocked Polyisocyanate Compound (E)

[0221] A compound in which hexamethylene diisocyanate is fully blocked with dimethyl malonate.

Preparation of Carbon Nanotube Dispersion Liquid (B)

Carbon Nanotube (a)

[0222] TUBALL (80%): single-walled carbon nanotube manufactured by OCSiAl, average outer diameter: 1.5 nm, carbon component: 80%, average length: 12 μm, 50% particle diameter (D50): 920 μm, specific surface area: 490 m.sup.2/g, single-walled [0223] TUBALL (93%): single-walled carbon nanotube manufactured by OCSiAl, average outer diameter: 1.5 nm, carbon component: 93%, average length: 10 μm, 50% particle diameter (D50): 1010 μm, specific surface area: 850 m.sup.2/g, single wall [0224] Carbon nanotube (a-1): average outer diameter: 1.5 nm, carbon component: 70%, average length: 8 μm, 50% particle diameter (D50): 1190 μm, specific surface area: 750 m.sup.2/g, single-walled [0225] Carbon nanotube (a-2): average outer diameter: 1.5 nm, carbon component: 91%, average length: 9 μm, 50% particle diameter (D50): 1350 μm, specific surface area: 1200 m.sup.2/g, single-walled

[0226] The carbon nanotubes (a-1) and (a-2) were produced according to the following Production Examples.

Production of Carbon Nanotube (a-1)

[0227] An iron metal having a thickness of 1 nm was deposited on a silicon wafer using a sputter deposition apparatus. This was inserted into a reaction furnace, and reacted in an argon hydrogen mixed gas at 1000 cc/min and an ethylene gas at 100 cc/min for 10 minutes after raising the temperature to 800° C. under an argon atmosphere to recover the carbon nanotubes. Further, a stainless-steel container was charged with carbon nanotubes and glass beads, and a dry grinding treatment was performed for 1 hour with a paint conditioner to adjust a length of the carbon nanotubes to a predetermined length, thereby obtaining carbon nanotubes (a-1).

Production of Carbon Nanotube (a-2)

[0228] An iron metal having a thickness of 1 nm was deposited on a silicon wafer using a sputter deposition apparatus. This was inserted into a reaction furnace, and reacted in an argon hydrogen mixed gas at 1000 cc/min and an ethylene gas at 100 cc/min for 10 minutes after raising the temperature to 1000° C. under an argon atmosphere to recover the carbon nanotubes. Further, a stainless-steel container was charged with carbon nanotubes and glass beads, and a dry grinding treatment was performed for 1 hour with a paint conditioner to adjust a length of the carbon nanotubes to a predetermined length, thereby obtaining carbon nanotubes (a-2).

Water-Soluble Resin (b)

[0229] Joncryl HPD-96J: manufactured by BASF Japan Ltd., styrene-acrylic acid-based, solid acid value: 240 mgKOH/g, non-volatile content: 34% [0230] Joncryl JDX-6500: manufactured by BASF Japan Ltd., all acrylic (styrene-free), solid acid value: 215 mgKOH/g, non-volatile content: 29.5% [0231] Dispex Ultra PA4550: manufactured by BASF Japan Ltd., modified polyacrylate polymer, solid acid value: 0 mgKOH/g, solid amine value: 54 mg KOH/g, non-volatile content: 50% [0232] BYK-190: manufactured by BYK company, styrene-based block copolymer, solid acid value: 25 mgKOH/g, non-volatile content: 40% [0233] BYK-2010: manufactured by BYK company, acrylic emulsion, solid acid value: 50 mgKOH/g, solid amine value: 50 mgKOH/g, non-volatile content: 40%

[0234] The 50% particle diameter (D50) of the carbon nanotubes used in the present invention was calculated by a laser diffraction particle size distribution (“SALD-2300” manufactured by Shimadzu Corporation), and the specific surface area was calculated by a full-automatic specific surface area measuring apparatus (“HM Model-1200” manufactured by Mountech Co., Ltd.).

Production of Carbon Nanotube Dispersion Liquid (B)

Carbon Nanotube Dispersion Liquid B-1

[0235] 0.5 parts of TUBALL as the carbon nanotube (a), 4.7 parts of Joncryl JPD-96J as the water-soluble dispersing resin (b), 0.3 parts of Surfynol 104E as an antifoaming agent, and 94.5 parts of purified water were preliminarily dispersed with a spatula, then 200 g of zirconia beads having a diameter of 0.5 mm were charged as a dispersion medium, and the mixture was subjected to a dispersion treatment with a paint shaker for 4 hours to obtain a carbon nanotube dispersion liquid B-1.

Carbon Nanotube Dispersion Liquids B-2 to B-13 and B-15 to B-33

[0236] Carbon nanotube dispersion liquids B-2 to B-13 and B-15 to B-33 were obtained in the same manner as in the case of the carbon nanotube dispersion liquid B-1 except that the kind and amount of the water-soluble resin (b) shown in Table 1 and a dispersion treatment time were changed.

Carbon Nanotube Dispersion Liquid B-14

[0237] A carbon nanotube dispersion liquid B-14 was obtained in the same manner as in the case of the carbon nanotube dispersion liquid B-7 except that 0.04 parts of “Demol N” (manufactured by Kao Corporation, sodium salt of β-naphthalenesulfonic acid formalin condensate) was added as a surfactant.

Evaluation of Carbon Nanotube Dispersion Liquid (B)

[0238] The obtained carbon nanotube dispersion liquid was evaluated as follows. The results are shown in Tables 1 and 2.

Vicosity

[0239] A viscosity value was measured immediately after the dispersion liquid was sufficiently stirred with a spatula using a B-type viscometer (“BL” manufactured by Toki Sangyo Co., Ltd.) at a dispersion liquid temperature of 25° C. and a B-type viscometer rotor rotation speed of 60 rpm. The rotor used for the measurement was No.1 when the viscosity value was less than 0.1 Pa.Math.s, No.2 when the viscosity value was 0.1 Pa.Math.s or more and less than 0.5 Pa.Math.s, No. 3when the viscosity value was 0.5 Pa.Math.s or more and less than 2.0 Pa.Math.s, and No. 4when the viscosity value was 2.0 Pa.Math.s or more and less than 10 Pa.Math.s. When the obtained viscosity value was 10 Pa.Math.s or more, it was described as “>10”, which indicates that the viscosity was too high to be evaluated by the B-type viscometer used for evaluation. The viscosity measured within 5 hours from immediately after the dispersion was defined as an initial viscosity.

Particle Size Distribution of Dispersion Liquid

[0240] As for the particle size distribution of the carbon nanotube (a) of the dispersion liquid, the 50% particle diameter (D50) was calculated by a laser diffraction type particle size distribution (“Microtrac MT300II” manufactured by MicrotracBEL Corporation).

TABLE-US-00001 TABLE 1 Water-soluble resin (b) Parts by mass of water-soluble resin (b) based on 100 Carbon nanotube (a) parts by mass Carbon 50% Average of carbon Dispersion nanotube Initial particle outer Specific Solid component treatment dispersion viscosity diameter diameter surface Content content of carbon time liquid (Pa .Math. s) (μm) Kind Structure (nm) area (%) Kind (g) nanotube (a) (hour) B-1 1.9 4.1 TUBALL Single-walled 1.5 490 0.5 Joncryl 1.6 400 4 (80%) HPD-96J B-2 3.3 6.9 TUBALL Single-walled 1.5 490 0.5 Joncryl 3.2 800 4 (80%) HPD-96J B-3 4.4 12.0 TUBALL Single-walled 1.5 490 0.5 Joncryl 6.4 1600 4 (80%) HPD-96J B-4 2.3 3.4 TUBALL Single-walled 1.5 490 0.5 Joncryl 3.2 800 8 (80%) HPD-96J B-5 0.9 2.8 TUBALL Single-walled 1.5 490 0.5 Joncryl 3.2 800 12 (80%) HPD-96J B-6 3.3 1.5 TUBALL Single-walled 1.5 490 0.5 Joncryl 3.2 800 4 (80%) JDX-6500 B-7 1.2 17.5 TUBALL Single-walled 1.5 490 0.5 BYK-190 3.2 800 4 (80%) B-8 0.7 13.2 TUBALL Single-walled 1.5 490 0.5 BYK-2010 3.2 800 4 (80%) B-9 1.3 7.7 TUBALL Single-walled 1.5 490 0.5 Dispex 3.2 800 4 (80%) Ultra PA 4550 B-10 0.2 4.5 TUBALL Single-walled 1.5 490 0.15 BYK-190 0.96 800 4 (80%) B-11 0.6 6.1 TUBALL Single-walled 1.5 490 0.3 BYK-190 1.92 800 4 (80%) B-12 1.5 24.4 TUBALL Single-walled 1.5 490 0.6 BYK-190 3.84 800 4 (80%) B-13 5.3 31.0 TUBALL Single-walled 1.5 490 1.0 BYK-190 6.4 800 4 (80%) B-14 1.0 15.0 TUBALL Single-walled 1.5 490 0.5 BYK-190 3.2 800 4 (80%) B-15 2.2 2.5 Carbon Single-walled 1.5 750 0.5 Joncryl 3.2 800 4 nanotube JDX-6500 (a-1) B-16 2.9 3.6 Carbon Single-walled 1.5 750 0.5 BYK-190 3.2 800 4 nanotube (a-1) B-17 3.5 4.4 Carbon Single-walled 1.5 750 0.5 Joncryl 3.2 800 4 nanotube HPD-96J (a-1)

TABLE-US-00002 TABLE 2 Water-soluble resin (b) Parts by mass of water-soluble resin (b) with respect to 100 parts by Carbon nanotube (a) mass of Carbon 50% Average carbon Dispersion nanotube Initial particle outer Specific Solid component treatment dispersion viscosity diameter diameter surface Content content of carbon time liquid (Pa .Math. s) (μm) Kind Structure (nm) area (%) Kind (g) nanotube (a) (hour) B-18 0.6 0.8 TUBALL Single-walled 1.5 490 0.5 Joncryl 0.4 100 4 (80%) HPD-96J B-19 0.8 1.7 TUBALL Single-walled 1.5 490 0.5 Joncryl 0.8 200 4 (80%) HPD-96J B-20 >10 45.0 TUBALL Single-walled 1.5 490 0.5 Joncryl 12 3000 4 (80%) HPD-96J B-21 2.0 1.2 TUBALL Single-walled 1.5 490 0.5 Joncryl 0.8 200 4 (80%) JDX-6500 B-22 1.8 3.8 TUBALL Single-walled 1.5 490 0.5 BYK-190 0.8 200 4 (80%) B-23 0.9 2.2 TUBALL Single-walled 1.5 490 0.5 BYK-2010 0.8 200 4 (80%) B-24 2.7 2.1 TUBALL Single-walled 1.5 490 0.5 Dispex 0.8 200 4 (80%) Ultra PA 4550 B-25 3.6 3.2 TUBALL Single-walled 1.5 850 0.5 Joncryl 4.16 800 4 (93%) HPD-96J B-26 2.9 3.9 TUBALL Single-walled 1.5 850 0.5 Joncryl 4.16 800 4 (93%) JDX-6500 B-27 0.8 5.3 TUBALL Single-walled 1.5 850 0.5 BYK-190 4.16 800 4 (93%) B-28 1.0 2.8 TUBALL Single-walled 1.5 850 0.5 BYK-2010 4.16 800 4 (93%) B-29 1.1 4.6 TUBALL Single-walled 1.5 850 0.5 Dispex 4.16 800 4 (93%) Ultra PA 4550 B-30 3.0 4.5 Carbon Single-walled 1.5 1200 1.65 Dispex 4.16 800 4 nanotube Ultra PA (a-2) 4551 B-31 4.1 4.8 Carbon Single-walled 1.5 1200 2.65 Dispex 4.16 800 4 nanotube Ultra PA (a-2) 4552 B-32 3.4 51.2 TUBALL Single-walled 1.5 490 0.5 Joncryl 3.2 800 1 (80%) HPD-96J B-33 1.3 0.8 TUBALL Single-walled 1.5 490 0.5 Joncryl 3.2 800 20 (80%) HPD-96J

Production of Aqueous White Conductive Primer Coating Composition

[0241] In addition to the binder component (A) and the carbon nanotube dispersion liquid (B) described above, the following materials were used as materials of the aqueous white conductive primer coating composition. [0242] Titanium oxide (C-1): trade name “TI-PURE R-706”, manufactured by KEMMERS Co., Ltd., rutile titanium oxide [0243] Titanium oxide (C-2): trade name “JR-806”, manufactured by Tayca Corporation, rutile titanium oxide [0244] Conductive titanium oxide: trade name “ET-500W”, manufactured by Ishihara Sangyo Kaisha, Ltd., white conductive titanium oxide [0245] Conductive mica: trade name “Iriotec 7310”, manufactured by Merck Ltd. [0246] Ionic liquid: trade name “CIL-313”, manufactured by Japan Carlit Co., Ltd.

[0247] The above components were mixed in a blending ratio shown in Table 1 below (the carbon nanotube dispersion liquid (B) represents parts by mass of the solid content of the carbon nanotube (a), and the components other than the carbon nanotube dispersion (B) represent parts by mass of the solid content), and the mixture was sufficiently stirred with a mixer to obtain various aqueous white conductive primers.

Preparation of Test Coated Sheet

[0248] Each coating composition prepared as described above was applied to a polypropylene sheet (degreased) by air spray coating so as to have a cured film thickness of 30 μm. The obtained coated coating film was left to stand at room temperature for 3 minutes for setting, and was then pre-heated at 60° C. for 3 minutes to form a white primer layer.

[0249] Next, the uncured white primer layer was electrostatically coated with “WBC-713T No.062” (aqueous interference color base coating material, manufactured by Kansai Paint Co., Ltd.) so as to have a cured film thickness of 15 μm, left to stand at room temperature for 2 minutes for setting, and then pre-heated at 80° C. for 3 minutes to form an interference color base coat layer. Subsequently, the uncured white primer layer was electrostatically coated with “Soflex 7175” (acrylic resin-urethane resin-based thermosetting clear coating, manufactured by Kansai Paint Co., Ltd.) as a clear coating composition so as to have a cured film thickness of 25 μm, left to stand at room temperature for 7 minutes for setting, and then dried by heating at 120° C. for 30 minutes to prepare a test coated sheet.

Evaluation of Aqueous White Conductive Primer Coating Composition

[0250] Each of the test coated sheets produced as described above was subjected to the following performance test. The results are shown in Table 2.

(1) Surface Resistivity of Primer Coating Film Surface

[0251] A primer coating film formed by spray-coating a black polypropylene sheet (degreased) with each of the coating compositions prepared as described above so as to have a cured film thickness of 30 μm was left to stand at room temperature for 3 minutes for setting, was then pre-heated at 60° C. for 3 minutes, and then the surface resistivity (Ω/□) of each coating film surface was measured at 20° C. by “MODEL 150” (manufactured by TREK). A indicates that the surface resistivity is less than 10.sup.6 (Ω/□), B indicates that the surface resistivity is 10.sup.6 (Ω/□) or more and 10.sup.8 (Ω/□) or less, and C indicates that the surface resistivity is more than 10.sup.8 (Ω/□).

(2) Brightness (L* Value)

[0252] A primer coating film formed by spray-coating a black polypropylene sheet (degreased) with each of the coating compositions prepared as described above so as to have a cured film thickness of 30 μm was left to stand at room temperature for 3 minutes for setting, and was then pre-heated at 60° C. for 3 minutes. Next, after heating at 120° C. for 30 minutes, each test coated sheet was irradiated with light from an angle of 45° with respect to an axis perpendicular to the coating film surface using a multi-angle spectrophotometer “CM-512m3” (manufactured by Konica Minolta, Inc.), and the brightness L* value of light in a direction perpendicular to the coating film surface among the reflected light was measured. A indicates that the L* value is 83 or more, B indicates that the L* value is 80 or more and less than 83, and C indicates that the L* value is less than 80.

(3) Weather Resistance

[0253] Each of the test coated sheets prepared as described above was subjected to an accelerated weather resistance test using a “super xenon weather meter” (manufactured by Suga Test Instruments Co., Ltd., weather resistance tester) under the conditions of a test piece wetting cycle of 18 minutes/2 hours and a black panel temperature of 61° C. to 65° C. in accordance with JIS K5600-7-7. Next, when an irradiation time of a lamp reached 1000 hours, an appearance of the test coated sheet was visually evaluated. A indicates that there is no abnormality in the appearance, and C indicates that there is an abnormality in the appearance.

TABLE-US-00003 TABLE 3 Example 1 2 3 4 5 6 7 8 Binder Base Acrylic Acrylic resin 20 20 20 30 20 20 20 component resin resin (A11-1) (A) (A1) Acrylic resin 20 20 (A12-1) Polyester resin 20 20 20 15 20 20 20 Polyolefin resin (A2) Polyolefin resin 25 25 25 20 25 25 25 (A2-1) Polyolefin resin 25 (A2-2) Crosslinking Blocked polyisocyanate 20 20 20 15 20 35 20 agent compound Melamine resin 15 15 15 20 15 35 15 Carbon B-1 nanotube B-2 dispersion B-3 liquid (B) B-4 B-5 B-6 B-7 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.08 B-8 B-9 B-10 B-11 B-12 B-13 B-14 B-15 B-16 B-17 B-18 B-19 B-20 B-21 B-22 B-23 B-24 B-25 B-26 B-27 B-28 B-29 B-30 B-31 B-32 B-33 Titanium R706 150 150 150 150 150 150 150 130 oxide (C) JR806 Conductive titanium oxide Conductive mica Ionic liquid Whiteness A A A A A A A A Surface resistivity A A A A A A A B Weather resistance B B B B B B B B Example 9 10 11 12 13 14 15 Binder Base Acrylic Acrylic resin 20 20 20 20 20 20 20 component resin resin (A11-1) (A) (A1) Acrylic resin (A12-1) Polyester resin 20 20 20 20 20 20 20 Polyolefin resin (A2) Polyolefin resin 25 25 25 25 25 25 25 (A2-1) Polyolefin resin (A2-2) Crosslinking Blocked polyisocyanate 20 20 20 20 20 20 20 agent compound Melamine resin 15 15 15 15 15 15 15 Carbon B-1 0.1 nanotube B-2 0.1 dispersion B-3 0.1 liquid (B) B-4 0.1 B-5 0.1 B-6 0.1 B-7 0.15 B-8 B-9 B-10 B-11 B-12 B-13 B-14 B-15 B-16 B-17 B-18 B-19 B-20 B-21 B-22 B-23 B-24 B-25 B-26 B-27 B-28 B-29 B-30 B-31 B-32 B-33 Titanium R706 170 150 150 150 150 150 150 oxide (C) JR806 Conductive titanium oxide Conductive mica Ionic liquid Whiteness B A A A A A A Surface resistivity A A A A A A A Weather resistance B B B B B B B

TABLE-US-00004 TABLE 4 Example 16 17 18 19 20 21 22 Binder Base Acrylic Acrylic resin 20 20 20 20 20 20 20 component resin resin (A11-1) (A) (A1) Acrylic resin (A12-1) Polyester resin 20 20 20 20 20 20 20 Polyolefin resin (A2) Polyolefin resin 25 25 25 25 25 25 25 (A2-1) Polyolefin resin (A2-2) Crosslinking Blocked polyisocyanate 20 20 20 20 20 20 20 agent compound Melamine resin 15 15 15 15 15 15 15 Carbon B-1 nanotube B-2 dispersion B-3 liquid (B) B-4 B-5 B-6 B-7 B-8 0.1 B-9 0.1 B-10 0.1 B-11 0.1 B-12 0.1 B-13 0.1 B-14 0.1 B-15 B-16 B-17 B-18 B-19 B-20 B-21 B-22 B-23 B-24 B-25 B-26 B-27 B-28 B-29 B-30 B-31 B-32 B-33 Titanium R706 150 150 150 150 150 150 150 oxide (C) JR806 Conductive titanium oxide Conductive mica Ionic liquid Whiteness A A A A A A A Surface resistivity B A B B A A A Weather resistance B B B B B B B Example 23 24 25 26 27 28 29 Binder Base Acrylic Acrylic resin 20 20 20 20 20 20 20 component resin resin (A11-1) (A) (A1) Acrylic resin (A12-1) Polyester resin 20 20 20 20 20 20 20 Polyolefin resin (A2) Polyolefin resin 25 25 25 25 25 25 25 (A2-1) Polyolefin resin (A2-2) Crosslinking Blocked polyisocyanate 20 20 20 20 20 20 20 agent compound Melamine resin 15 15 15 15 15 15 15 Carbon B-1 nanotube B-2 dispersion B-3 liquid (B) B-4 B-5 B-6 B-7 0.1 0.1 0.1 0.1 B-8 B-9 B-10 B-11 B-12 B-13 B-14 B-15 0.1 B-16 0.1 B-17 0.1 B-18 B-19 B-20 B-21 B-22 B-23 B-24 B-25 B-26 B-27 B-28 B-29 B-30 B-31 B-32 B-33 Titanium R706 150 150 150 150 150 150 oxide (C) JR806 150 Conductive titanium oxide 5 Conductive mica 5 Ionic liquid 5 Whiteness A A A A A A A Surface resistivity B A A A A A A Weather resistance B B B B B B B

TABLE-US-00005 TABLE 5 Comparative Example 1 2 3 4 5 6 7 8 9 Binder Base Acrylic Acrylic resin 20 20 20 20 20 20 20 20 20 component resin resin (A11-1) (A) (A1) Acrylic resin (A12-1) Polyester resin 20 20 20 20 20 20 20 20 20 Polyolefin resin (A2) Polyolefin resin 25 25 25 25 25 25 25 25 25 (A2-1) Polyolefin resin (A2-2) Crosslinking Blocked polyisocyanate 20 20 20 20 20 20 20 20 20 agent compound Melamine resin 15 15 15 15 15 15 15 15 15 Carbon B-1 nanotube B-2 dispersion B-3 liquid (B) B-4 B-5 B-6 B-7 B-8 B-9 B-10 B-11 B-12 B-13 B-14 B-15 B-16 B-17 B-18 0.1 B-19 0.1 B-20 0.1 B-21 0.1 B-22 0.1 B-23 0.1 B-24 0.1 B-25 0.1 B-26 0.1 B-27 B-28 B-29 B-30 B-31 B-32 B-33 Titanium R706 150 150 150 150 150 150 150 150 150 oxide (C) JR806 Conductive titanium oxide Conductive mica Ionic liquid Whiteness A A A A A A A A A Surface resistivity C C C C C C C C C Weather resistance B B B B B B B B B Comparative Example 10 11 12 13 14 15 16 17 18 Binder Base Acrylic Acrylic resin 20 20 20 20 20 20 20 20 20 component resin resin (A11-1) (A) (A1) Acrylic resin (A12-1) Polyester resin 20 20 20 20 20 20 20 20 20 Polyolefin resin (A2) Polyolefin resin 25 25 25 25 25 25 25 25 25 (A2-1) Polyolefin resin (A2-2) Crosslinking Blocked polyisocyanate 20 20 20 20 20 20 20 20 20 agent compound Melamine resin 15 15 15 15 15 15 15 15 15 Carbon B-1 nanotube B-2 dispersion B-3 liquid (B) B-4 B-5 B-6 B-7 B-8 B-9 B-10 B-11 B-12 B-13 B-14 B-15 B-16 B-17 B-18 B-19 B-20 B-21 B-22 B-23 B-24 B-25 B-26 B-27 0.1 B-28 0.1 B-29 0.1 B-30 0.1 B-31 0.1 B-32 0.1 B-33 0.1 Titanium R706 150 150 150 150 150 150 150 0 40 oxide (C) JR806 Conductive titanium oxide 150 Conductive mica 60 Ionic liquid Whiteness A A A A A A A B C Surface resistivity C C C C C C C B B Weather resistance B B B B B B B C B

[0254] As shown in Tables 3 to 5, it was found that Examples using the aqueous white conductive primer coating composition of the present invention can form a coating film having high brightness and excellent conductivity on a plastic substrate as compared with Comparative Examples.

[0255] Although the present application is described in detail with reference to the specific embodiment, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

[0256] The present application is based on Japanese Patent Application No. 2019-172015 filed on Sep. 20, 2019, the contents of which are incorporated herein by reference.