JPH09125007A - Water-based coating composition and formation of coating layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-based coating composition containing an emulsified polymer of black japan at a specific ration to the vehicle, giving jet-black coating layer excellent in deep and clear tones and useful in coating household electric appliances which are required to have high-quality appearance and in household articles. SOLUTION: This coating composition contains (A) an emulsified polymer of black japan and (B) a vehicle (other than the component A) at a weight ration of (A) (10-70)/(B) 100 in solid basis. The component A is preferably prepared by subjecting a japan component containing urushiol such as purified japan or black japan to oxidative polymerization in an aqueous solution and suspending or emulsifying the polymer in the vehicle comprising a water-based film-forming polymer mixed with a curing agent. The water-based film-forming polymer is a polymer which can be appropriately used as a component B. In an embodiment, an aqueous acrylic polymer, an aqueous polyester resin and the like can be used. The curing agent is, for example, a melamine resin, blocked polyisocyanate and the like.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to home electric appliances, furniture,
Aqueous coating composition containing an emulsion polymer of black lacquer suitable for forming a jet black coating film having excellent depth and clarity for coating materials such as building materials and automobile interior parts, and the aqueous coating composition The present invention relates to a method for forming a coating film using a material.

[0002]

2. Description of the Related Art A coating composition and a film forming method for forming a jet black coating film having a deep feeling and a clear feeling with no cloudiness or a yellowish or brownish tint in the bottom color of the coating film are known from the related art. Has been. For example, in JP-A-60-106866, a polymer component containing at least substantially 25% by weight of a thermosetting acrylic resin and a mono-component substituted with amino-phenol and having 2-naphthoyl bonded thereto.
Ultra jet black coating compositions comprising a pigment component containing at least substantially 5% by weight of a 1: 1 chromium complex of an azo dye are disclosed. However, since this composition contains a dye as a component for forming a deep dark blue jet-blackness, an alcohol solvent having a strong polarity must be frequently used in order to achieve dispersion stability. For this reason, the resistance value of the coating composition is lowered and discharge sparks are generated, so that there is a drawback that the industrially advantageous electrostatic coating means cannot be applied. In addition, when carbon black is used as the pigment component, it is not possible to develop a jet black tone in a state where there is little color blur due to the dispersion.

In Japanese Patent Laid-Open No. 3-12263,
Mushi which is characterized in that an electrodeposition paint and an intermediate paint are applied, a base coat and a transparent clear are applied on the baked coating film by wet on wet and baked, and then a color clear and a transparent clear are applied by wet on wet and baked. A method for forming a toned coating film has been proposed. However, when a black color clear is used in this forming method,
As the pigment concentration is lowered, a reddish tint, yellowish tint, brownish tint or the like is generated, and it is difficult to obtain a clear black lacquer coating film.

On the other hand, Japanese Patent Application Laid-Open No. 3-127668 discloses a method for coating a glittering paint containing a natural lacquer paint. That is, in this coating method, an undercoat coating film is formed on a base material made of a synthetic resin, a slow-drying coating material such as a natural lacquer coating material is applied at least once on the undercoat coating film, and the slow-drying coating material has a glittering property. A powder is applied, and then a lacquer paint modified with a two-component urethane paint is applied and dried to form a clear paint film on this paint film. Therefore, the purpose of coating is to form a pattern such as wood grain due to the interference effect of the glittering powder, and it is not intended to obtain a jet-black coating film.

[0005]

As described above, a technique for obtaining a jet-black coating composition which can be industrially coated by blending a natural lacquer component containing urushiol has not been developed so far. In view of such circumstances, the present inventors have made earnest studies to develop an aqueous paint capable of industrially forming a jet black coating film using black lacquer as a black source, and as a result, specify an emulsion polymer of black lacquer. When blended in the vehicle in a quantity ratio, an aqueous coating composition capable of forming a jet-black coating film having excellent depth and clarity is obtained, and an achromatic undercoating film having a specific brightness using the aqueous coating composition as a base coating material. It was confirmed that a high-grade jet-black coating film with less color blur can be formed with good workability by applying it on top and forming a clear coating film on the uppermost surface, leading to the development of the present invention.

[0006] Therefore, the problem to be solved by the present invention is to provide an aqueous coating composition capable of industrially forming a jet black coating film having excellent depth and clarity, and to use the aqueous coating composition as a base coating. It is an object of the present invention to provide a coating film forming method capable of efficiently forming a high-quality jet black coating film with little color blur.

[0007]

[Means for Solving the Problems] An aqueous coating composition according to the present invention for achieving the above object comprises an emulsion polymer of black lacquer as a vehicle (excluding the emulsion polymer of black lacquer; hereinafter not particularly indicated). The composition is characterized in that the content is 10 to 70 parts by weight (solid content) with respect to 100 parts by weight (solid content).

The coating film forming method according to the present invention is as follows.
The constitutional feature is that the jet-black coating layer is formed by sequentially performing the coating forming steps (1) to (3). (1) Applying an achromatic undercoating on the surface of the base material to be coated with a brightness of N3
A base coating film forming step of forming the following achromatic coating film, (2) the base coating film surface, a base coating film forming step of forming a black coating film by applying the above-mentioned aqueous coating composition, and (3) A clear coating film forming step in which a clear coating film is formed by applying a clear coating material on the surface of the base coating film.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The emulsion polymer of black lacquer that constitutes the aqueous coating composition of the present invention is an oxidized heavy lacquer obtained by oxidative polymerization of a lacquer component containing urushiol such as purified lacquer or black lacquer in an alkaline aqueous solution. A vehicle consisting of an aqueous film-forming polymer mixed with a curing agent (excluding the black lacquer emulsion polymer)
It is prepared by suspending and emulsifying. As the lacquer oxidation polymer, for example, "Urushipearl" (black water suspension having a nonvolatile content of 29 to 33%) manufactured by Honshu Chemical Industry Co., Ltd. is effectively used.

As the aqueous film-forming polymer used as a vehicle, those usually used in aqueous coating compositions can be appropriately used. For example, an addition polymer such as an aqueous acrylic polymer or a vinyl polymer, an aqueous polyester. Examples thereof include condensation polymers of alkyd, polyurethane, amine and the like. As the curing agent, for example, melamine resin, blocked polyisocyanate, epoxy resin or the like can be used. A thickener, a surface conditioner, and the like can be added to the water-based coating composition as an additive, and a black pigment such as carbon black may be added as long as the jet black property is not impaired.

Specific aqueous film-forming polymers include the following aqueous polymer compositions developed by the present applicant. (1) (A) Acidic group-containing ethylenic monomer, hydroxyl group-containing ethylenic monomer, and other ethylenic monomer copolymerizable therewith, acid value 5-100, hydroxyl value 20 -100, solubility parameter- (δsp) 9.0-12.0, number average molecular weight 5,000-50,000 copolymer 95-60
Parts by weight, (B) 5 to 40 parts by weight of a cross-linking component, (C) an ethylenic monomer having an acidic group, an ethylenic monomer having a hydroxyl group, and another ethylenic monomer copolymerizable therewith Acid value 5-100,
Hydroxyl number 20-100, solubility parameter- (δ
sp) 9.0 to 13.0, and 95 to 60 parts by weight of a copolymer having an absolute value of the difference from the solubility parameter of the copolymer (A) of 0.3 or more. Composition (JP-A-62-289267).

(2) (A) An acid value of 5 to 100 obtained by copolymerizing an ethylenic monomer having an acidic group, an ethylenic monomer having a hydroxyl group and another ethylenic monomer copolymerizable therewith, Hydroxyl number 20 ~
100, solubility parameter- (δsp) 9.0 to 13.
0, 94 to 30 parts by weight of a vinyl polymer having a number average molecular weight of 3,000 to 50,000, and (B) a crosslinking component of 5 to 40
An aqueous polymer composition consisting of parts by weight (JP-A-63-111976).

(3) (A) Among the copolymerizable ethylenic monomers, 5 to 40% by weight of amide group-containing ethylenic monomer, 3 to 15% by weight of acidic group-containing ethylenic monomer, and 10 to 40 of hydroxyl group-containing ethylenic monomer. %, And 100 parts by weight of a film-forming polymer obtained by neutralizing at least a part of acidic groups of a copolymer having a number average molecular weight of 6,000 to 50,000 obtained from the remaining ethylenic monomer. _{, (B) C n F 2n.1} - or C _n F _2n - group (provided that
n shows the integer of 1-20. ), And 0.01 to 5 parts by weight of a fluorine-containing compound having at least one acidic group or at least one acid group thereof, (C) an amino compound, an isocyanate compound and an epoxy compound which can be heat-cured with (A). 5 to 120 parts by weight of at least one crosslinking component selected from the group consisting of: (D) a compound selected from the group consisting of phosphoric acid mono- or diesters of C _{11 to} C ₂₄ organic compounds and a phosphorus-containing titanate coupling agent. Aqueous polymer composition consisting of and (JP-A-3-47875)
.

(4) Formula (A) represented by the general formula (wherein X represents a hydrogen atom or a methyl group, Y represents an alkylene group having 2 to 4 carbon atoms, and n represents an integer of 3 to 30). Number average molecular weight of 1,000 to 50,000 and an acid value of 15 obtained by copolymerizing the above-mentioned monomer with (B) another ethylenic monomer.
To 200 and an acrylic resin having a hydroxyl value of 20 to 200 (JP-A-4-25578).

[0015]

Embedded image

(5) (A) Amido group-containing ethylenic monomer 5 to 40% by weight, acidic group-containing ethylenic monomer 3-1
5% by weight, 10 to 40% by weight of a hydroxyl group-containing ethylenic monomer and the remaining amount of other ethylenic monomer are copolymerized to obtain a number average molecular weight of 6,000 to 50,000.
0 to 10 parts by weight (solid content) of the film-forming polymer obtained by neutralizing at least a part of the acidic groups of the copolymer of
(B) having a terminal hydroxyl group, a molecular weight of 1,000 to
A hydrophilic group-containing oligomer obtained by reacting 5,000 diol compounds, diisocyanate compounds and compounds having at least one active hydrogen in the molecule and having a hydrophilic group under an isocyanate-rich condition is used. Aqueous polymer composition containing 5 to 90% by weight (solid content) of a urethane-containing water dispersion obtained by dispersing in a water medium containing a primary and / or secondary polyamine (Japanese Patent Laid-Open Publication No. Hei 4 (1998) -264242).
-25582).

The mixing ratio of the vehicle composed of these aqueous film-forming polymers and the emulsion polymer of black lacquer is 1
10 parts by weight (solid content) of black lacquer emulsion polymer 10 to
70 parts by weight (solid content), preferably 30 to 50 parts by weight (solid content) is set. Emulsion polymer of black lacquer is 10
When the composition is less than part by weight (solid content), the formed coating film cannot exhibit jet blackness having excellent depth and clarity, while when it exceeds 70 parts by weight (solid content), the formed coating film has Strength is reduced.

In order to form a jet-black coating film using the above-mentioned component-based aqueous coating composition, a coating operation of sequentially performing the following base coating film forming step, base coating film forming step and clear coating film forming step is carried out. Applied.

The base coating film forming step is a step of applying an achromatic base coating material to the surface of the base material to be coated to form an achromatic coating film having a brightness of N3 or less. The lightness is an index displayed on the lightness axis among the hue, lightness, and saturation shown in JIS Z8721 “Color display method based on three attributes”, and the lightness N3 or less is a region belonging to the dark color gamut. The lightness of the formed achromatic coating film is N
When it exceeds 3, the hiding property of the enamel base is weakened and the color feeling of the colored undercoat is not exhibited, and the lightness is increased and jet blackness cannot be exhibited in the final coating layer.

The achromatic base paint used in the base coating film forming step uses black pigments such as carbon black, titanium black and iron black and white pigments such as titanium dioxide as coloring pigments, and if necessary, talc, clay, Using an extender pigment such as calcium carbonate or barium sulfate, the brightness is N
Adjust the color to 3 or less. As a vehicle resin,
For example, a component system in which a basic resin such as a polyester resin, an alkyd resin, an acrylic resin, a silicone resin, or a fluororesin is mixed with a crosslinking agent such as an amino resin or a (block) polyisocyanate compound is used. Besides, it is also possible to use a two-component polyurethane resin or silicone resin which is cured by drying at room temperature. The paint may be blended with various additives usually used for paints. The base coating film formed in this step has a dry film thickness of 25 to 50 μm.
m.

The base coating film forming step is a step of forming a black coating film by applying the aqueous coating composition containing the above-mentioned emulsion polymer of black lacquer to the surface of the base coating film, and the preferable thickness of the formed coating film is The dry film thickness is in the range of 10 to 30 μm.

The clear coating film forming step is a final coating step in which a clear coating film is formed by applying a clear coating material on the surface of the base coating film. As the clear paint, a commonly used transparent resin is used, but various additive components may be blended within a range not impairing the transparency. In addition, the form of clear paint is generally an organic solvent type, but water-based paint, powder paint,
It may be an ultraviolet curing type or a room temperature curing type. The clear coating film is preferably dried and cured simultaneously with the base coating film in the previous step by a 2-coat 1-bake method.
The coat 2 bake method may be used.
The base coating film and the clear coating film of the present invention can be formed by room temperature curing without baking depending on the selection of resin. The preferred dry film thickness of the clear coating film formed is in the range of 30 to 60 μm.

There is no particular limitation on the substrate to be coated for forming a coating film according to the present invention, and examples thereof include metals such as iron, aluminum, copper or alloys thereof, and inorganic materials such as glass, cement and concrete. Material, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyamide, polyacryl, polyester, ethylene-polyvinyl alcohol copolymer, vinyl chloride resin,
Various materials such as resin moldings such as vinylidene chloride resin, polycarbonate, polyurethane and the like, plastic materials such as various FRPs, wood and fiber materials can be mentioned. In addition, it is optional to perform appropriate undercoating or precoating treatment on these coated substrates in advance.

The coating can be applied directly to the base material to be coated, but, for example, when targeting electrical products and parts thereof,
After the surface chemical conversion treatment, an electrodeposition paint or an anticorrosive primer for undercoat is applied as an undercoat, and after the coating film is cured, the method of the present invention is applied to form a jet-black coating layer. As the coating method, atomization type coating or roll coater coating is used. In particular, air spray coating and electrostatic coating by the atomization coating method are industrially advantageous.

According to the above-mentioned coating film forming method, the black of the lightness N3 or less formed in the base coating film forming step and the light due to the black lacquer-containing polymer in the base coating film formed on the coating film Combined with the transmission and absorption effect, it produces a jet black color tone with an excellent depth and clearness. Furthermore, by forming a clear coating film, diffuse reflection generated from the coating film surface is suppressed, and it becomes possible to obtain a high quality coating layer with less color blur even when observed from various angles. Therefore, a yellowish or brownish color is not generated due to the scattering of the pigment surface that occurs in the case of the conventional enamel base in which the black pigment is dispersed, and it is possible to always form a jet black coating film having a high-grade feeling.

[0026]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples. However, the scope of the invention is not limited to these examples.

Example 1 (1) Achromatic undercoating; polyester / melamine resin-based color intermediate coating [Nippon Paint Co., Ltd., "Olga S-90"
Sealer N2 dark gray "] was used. The brightness of the paint is N2.

(2) Preparation of enamel base paint (water-based paint composition); ethylene glycol monobutyl ether 76 in a reaction vessel (1 l) equipped with a stirrer, a temperature controller, and a cooling pipe.
By weight, 45 parts by weight of styrene, 63 parts by weight of methyl methacrylate, 48 parts by weight of 2-hydroxyethyl methacrylate, 117 parts by weight of n-butyl acrylate, 27 parts by weight of methacrylic acid, 3 parts by weight of lauryl mercaptan, azobisiso 61 parts by weight of a monomer solution consisting of 3 parts by weight of butyronitrile was added, and 12
The temperature was kept at 0 ° C. Then, the monomer solution 24
After 5 parts by weight was added dropwise over 3 hours, stirring was continued for 1 hour. Further, 28 parts by weight of dimethylethanolamine and 200 parts by weight of deionized water were added to obtain an acrylic resin varnish having a volatile content of 50% and a resin number average molecular weight of 6,000.
This resin has a hydroxyl value of 70, an acid value of 58, and an Sp value of 11.3.
Had the following characteristics. This water-soluble acrylic varnish 14
0 parts by weight of 30 parts by weight of methoxylated methylol melamine [“CYMER 303” manufactured by Mitsui Toatsu Co., Ltd.] as a cross-linking agent was used as a vehicle, and an emulsion polymer of black lacquer [Honshu Chemical Industry Co., Ltd., “Urushi” 142 parts by weight of a pearl "; black water suspension having a nonvolatile content of 30%] was mixed with stirring. In this case, the mixing ratio of the black lacquer emulsion polymer to 100 parts by weight of the vehicle (solid content) is 42.6 parts by weight (solid content). next,
The mixed solution No. 4 Ford Cup takes 25-30 seconds / 20
Aqueous coating composition containing a black lacquer component was prepared by diluting with deionized water so that the temperature became 0 ° C.

(3) Clear coating: An acrylic / melamine resin-based clear coating [manufactured by Nippon Paint Co., Ltd., "Superlac O-100 Clear"] was used.

(4) Formation of coating film; the above-mentioned achromatic base paint,
An enamel base paint (water-based paint composition) and a clear paint were used to sequentially coat the steel plate substrate surface by the following coating film forming process. 0.8mm thick after chemical conversion treatment with zinc phosphate
Cation electrodeposition coating [Nippon Paint Co., Ltd., "Power Top U-50"] is applied to the dull steel plate substrate of
After coating so as to be m, it was baked at 160 ° C. for 30 minutes. A dry base paint is applied to the surface of this electrodeposited coating with a dry coating.
Air spray coating was performed so that the thickness became 0 μm, and baking was performed at 140 ° C. for 30 minutes to form a base coating film. Next, enamel base paint was air-sprayed to a dry film thickness of 20 μm and preheated at 80 ° C for 5 minutes.
The clear paint was applied so that the dry film thickness was 30 μm, set for 7 minutes, and then baked in a dryer at a temperature of 140 ° C. for 30 minutes.

(5) Evaluation of coating film: Optical measurement of hue [brightness (L ^* )] in the CIE (L ^* , a ^* , b ^* ) display system according to the following criteria for the coating film formed in the above process Also, the blackness and the feeling of depth were visually evaluated by visual observation. The results are shown in Table 1.

Measurement of lightness in CIE (L ^* , a ^* , b ^* ) display system; gonio-spectroscopic colorimeter [Murakami Color Research Laboratory,
GCMS-3 type, D65 light source, 2 degree field of view], and 45 ° from the perpendicular to the measurement sample on which a coating film was formed as shown in FIG.
The light source is illuminated at an angle of 15 ° (light receiving point in the highlight direction; reference numeral), 45 ° (reference numeral) and 110 ° (light receiving point in shade direction) from the regular reflection direction of the illumination angle: The light was simultaneously received at the angle of (symbol). This was color-measured with a L ^* a ^* b ^* color system of lightness and saturation, and jetness and depth feeling were evaluated from the measured value of lightness (L ^* ).

Criteria for visual judgment and evaluation: Criteria for evaluation and evaluation by visual observation are as follows. Jetness: ○ Very strong, △ There is some, × weak Depth feeling: ○ Strong, × weak

Example 2 (1) Preparation of enamel base coating (water-based coating composition): Water-based urethane resin [Asahi Denka Kogyo KK, "Adeka BonTiter HUX-232" (nonvolatile content 30%)] 100 weight Cross-linking agent [Asahi Denka Kogyo Co., Ltd., "ADEKA BON TITER HUX-
XW "(nonvolatile content 55%)] 6 parts by weight of a water-soluble resin as a vehicle, an emulsion polymer of black lacquer [Honshu Chemical Industry Co., Ltd.," Urushipearl "; Suspension] 47.6 parts by weight was mixed with stirring, and the mixing ratio of the emulsion polymer of black lacquer to 100 parts by weight of the vehicle (solid content) in this case was 42.9 parts by weight (solid content). The liquid was diluted with deionized water to a viscosity suitable for coating to prepare an aqueous coating composition containing a black lacquer component.

(2) Formation of coating film: RIM urethane bumper was washed with trichloroethane, and urethane primer [RB110 Primer, manufactured by Nippon Bee Chemical Co., Ltd.] was applied and cured, and no coating was applied. A colored base coating [Urethane coating "R-320 BKH-3" manufactured by Nippon Bee Chemical Co., Ltd.) was mixed with a predetermined curing agent and applied to cure to form a base coating having a brightness of N1. Then, apply an enamel base coating containing the black lacquer emulsion polymer prepared in (1) above to a dry film thickness of 20 μm.
It was air spray painted so that After preheating at 80 ℃ for 5 minutes, clear acrylic / urethane paint [Nippon Paint Co., Ltd., “NAX Mightylac G-II240
"2 coat clear" is mixed with a specified curing agent and diluted to a dry film thickness of 30 μm, and then it is applied at 80 ° C for 3 days.
It was dried and cured for 0 minutes to form a jet black coating film. The results of evaluation of this coating film as in Example 1 are also shown in Table 1.

Comparative Example 1 A copolymer of styrene / methyl methacrylate / ethyl methacrylate / ethyl acrylate and hydroxyethyl methacrylate / methacrylic acid having a number average molecular weight of 20,000, a hydroxyl value of 45, an acid value of 15 and a solid content of 50. %
70 parts by weight of acrylic resin and 15 parts by weight of melamine resin [Mitsui Toatsu Chemicals, Inc., "Uban 20SE" solid content 60%] in 15 parts by weight of solvent (xylene / butyl acetate / normal butanol = 5/5/3). In a vehicle mixed with 3 parts by weight,
Carbon black pigment ["FW-200" manufactured by Degussa)
2.0 parts by weight were compounded and dispersed by a ball mill until the particle size became 10 μm or less (JIS K5400). This black paint is 12 to 15 seconds in 4 Ford Cup
The viscosity was adjusted with a solvent (toluene / xylene / ethyl acetate / butyl acetate = 70/15/10/5) so as to be 20 ° C., and a dry coating film of 16 to 20 μm was formed on the base coating film surface of Example 1.
It was painted to become. The coating is carried out using an electrostatic coating machine [Landsburg Gema, "Auto REA"] with an atomization pressure of 2.8 kg / cm ^2.
The booth atmosphere during painting is 25 ° C.
The humidity was kept at 75%. After coating for 3 minutes after coating, an acrylic resin-based clear coating [manufactured by Nippon Paint Co., Ltd., "Superlac O-100"] was coated to a dry film thickness of about 35 μm. Then, after setting at room temperature for about 10 minutes, baking was performed at 140 ° C. for 30 minutes. The coating film thus formed was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 On a base coating film formed in the same manner as in Comparative Example 2, 100 parts by weight of an acrylic resin-based clear coating [Nippon Paint Co., Ltd., "Superlac O-100"] was added to a carbon black pigment [ 0.1 parts by weight of "FW-200" manufactured by Degussa Co., Ltd. was mixed and dispersed in a ball mill for a predetermined time to apply a color clear paint to a dry film thickness of 30 μm.
It was baked at 30 ° C. for 30 minutes. The coating film thus formed was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 3 A three-layer coating film was formed by the same coating film forming process as in Example 1 except that the undercoating film of Example 1 was formed from a polyester / melamine resin coating having a lightness of N4. The results of evaluation of the formed coating film in the same manner as in Example 1 are also shown in Table 1.

[0039]

[Table 1]

From the results shown in Table 1, the coating films of the examples satisfying the requirements of the present invention are low jetness at all angles, little color blurring, and excellent jetness and clarity. Was recognized. On the other hand, the comparative example 1 using the carbon black pigment, the comparative example 2 using the color clear containing carbon black, and the undercoat have a lightness of N.
It was confirmed that in Comparative Example 3 formed with the coating material exceeding 3, the lightness was high and the blackness was lowered, resulting in a black coating film that gives a sense of depth.

[0041]

As described above, according to the present invention, a black lacquer emulsion polymer is formed in a vehicle in a specific amount ratio to form a jet black coating film having excellent depth and clarity. An aqueous coating composition can be provided. According to the coating film forming step of the present invention, the aqueous coating composition is applied as a base coating onto an achromatic undercoating coating having a lightness of N3 or less,
By forming the clear coating film on the uppermost surface, a high-quality jet black coating film with less color blur can be industrially efficiently formed. Therefore, it is expected to be useful as a black paint and a coating film forming means for home electric appliances, furniture, building materials, automobile interior parts, etc., which require particularly high quality.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a lightness measurement angle in an example.

Claims (2)

[Claims] 1. An emulsion polymer of black lacquer is added to 1 part per 100 parts by weight (solid content) of a vehicle (excluding the emulsion polymer of black lacquer).
A water-based coating composition containing 0 to 70 parts by weight (solid content). 2. A method for forming a coating film, characterized in that a jet-black coating film layer is formed by sequentially performing the following coating film forming steps (1) to (3). (1) Applying an achromatic undercoating on the surface of the base material to be coated with a brightness of N3
The following base coating film forming step of forming an achromatic coating film, (2) a base coating film forming step of forming the black coating film by applying the aqueous coating composition of claim 1 on the surface of the base coating film, and ( 3) A clear coating film forming step of forming a transparent coating film by applying a clear coating on the surface of the base coating film.