JP5177377B2 - Water-based base coating composition, metal-type laminated coating film and method for forming the same - Google Patents

Description

  The present invention relates to an aqueous base coating composition capable of imparting a metallic luster close to the metallic luster possessed by metal plating, metal foil, etc., and a metallic tone laminate coating that can be formed using the aqueous base coating composition. The present invention relates to a film and a method for forming the same.

  As a paint capable of imparting a metallic luster close to the metallic luster possessed by metal plating, metal foil, etc. by forming a coating film, a paint composition comprising a glittering pigment obtained by pulverizing a deposited metal film into a metal piece Known (for example, Patent Document 1). In such a coating composition, the content of the glitter pigment is set to 15% or more by PWC, and the glitter pigment is oriented in a plane on the surface of the object to be coated by using a large amount of solvent. . In this way, the glossy pigment having a very thin thickness is orientated in a planar shape along the surface of the base material, so that metallic gloss can be imparted to the object to be coated.

  In such a conventional coating composition, an organic solvent is used as a solvent, and after coating the coating material on the coating object, the organic solvent in the coating film volatilizes, so that the coating film on the coating material is coated. Accordingly, the gradient of the glitter pigment contained in the coating film with respect to the substrate becomes gentle, and as a result, the glitter pigment is oriented in a planar shape. That is, such a coating composition contains a large amount of an organic solvent because it requires a drastic reduction in the thickness of the coating film in order to orient the glitter pigment in a planar shape.

  However, in recent years, from the viewpoints of improving the working environment and protecting the environment, there has been a demand for water-based paints that do not use organic solvents or reduce the amount of organic solvents used to the minimum. Such water-based coatings are variously studied for metallic coatings using aluminum flakes obtained by pulverizing metal powder or metal foil with a ball mill or the like.

  Examples of the aqueous metallic paint containing an aqueous cellulose derivative include a paint composition disclosed in Patent Document 2 and a paint composition disclosed in Patent Document 3.

  In paragraph [0042] of Patent Document 2, it is disclosed that the aqueous cellulose derivative is used at a ratio of 1 to 30% by weight with respect to the resin solid content of the aqueous resin. Further, paragraph [0033] of Patent Document 3 discloses that the acrylic resin solid content and the cellulose acetate butyrate resin solid content are used in a weight ratio of 100: 45 to 55.

However, even if the formulation proposed in the conventional aqueous metallic paint composition including the paint compositions disclosed in Patent Document 2 and Patent Document 3 is applied to the paint composition exhibiting the above metallic gloss. A good metallic luster could not be obtained.
Japanese Patent Laid-Open No. 11-80620 JP 7-331118 A JP 2006-297268 A

  An object of the present invention is to provide an aqueous base coating composition capable of imparting a good metallic gloss, a metal-based laminated coating film that can be formed using the aqueous base coating composition, and a method for forming the same. It is in.

  The aqueous base coating composition of the present invention comprises a glittering pigment obtained by pulverizing a deposited metal film into a metal piece, and an aqueous cellulose derivative having an acid value of 20 to 150 mgKOH / g (solid content), and an aqueous cellulose derivative Is the main binder resin, and the content of the glitter pigment is 20 to 70% by mass in terms of PWC.

  By using the aqueous base coating composition of the present invention, a good metallic gloss can be imparted to the coating film.

  In the present invention, an aqueous cellulose derivative having an acid value of 20 to 150 mgKOH / g (solid content) is used as the main binder resin. By using such an aqueous cellulose derivative as a main binder resin, the glitter pigment in the coating film can be oriented in a planar state in a good state, and a good metallic gloss can be obtained.

  The aqueous cellulose derivative in the present invention has an acid value of 20 to 150 mgKOH / g (solid content) as described above. If the acid value is too low, the water-solubilizing ability when neutralized is low, and it does not separate into a water-based paint. On the other hand, if the acid value is too high, it may become incompatible with other binder resins and become cloudy. A more preferable range of the acid value of the aqueous cellulose derivative is in the range of 30 to 150 mgKOH / g (solid content), and particularly preferably in the range of 40 to 70 mgKOH / g (solid content).

Specific examples of the aqueous cellulose derivative having the acid value as described above include carboxymethyl cellulose acetate butyrate. This is a cellulose derivative obtained by further butyl esterifying and carboxylating a partially acetylated product of cellulose. Carboxymethylcellulose acetate butyrate has a structure as shown below, and R represents a CH ₂ COOH group (carboxymethyl group), a COCH ₃ group (acetyl group), a COCH ₂ CH ₂ CH ₃ group, or H It is a group. In the case of the product name “CMCAB-641-0.2” used in the examples of the present specification, n is 90 to 170.

  As acetyl group content, the range of 1-30 weight% is preferable, More preferably, it is the range of 1-14 weight%. The butyl group content is preferably in the range of 10 to 60% by weight, more preferably 20 to 50% by weight. Further, the hydroxyl group content is preferably in the range of 0.5 to 5% by weight, more preferably 0.5 to 2% by weight.

  In addition to the aqueous cellulose derivative, other cellulose derivatives can be used in combination. Other cellulose derivatives are not particularly limited, and preferred examples include cellulose acetate butyrate, nitrocellulose, cellulose acetate, and cellulose acetate propionate.

  The glitter pigment used in the present invention is a glitter pigment obtained by pulverizing a deposited metal film into a metal piece. Such a luster pigment can be generally obtained by vapor-depositing a metal film on a base film, peeling off the base film, and then pulverizing the deposited metal film into a metal piece. The average thickness of the glitter pigment is preferably in the range of 0.01 to 0.1 μm. Moreover, it is preferable that an average particle diameter (median value) is the range of 5-100 micrometers. The average particle diameter can be measured by a laser diffraction method.

  The material of the deposited metal film is not particularly limited, and examples thereof include metal films such as aluminum, gold, silver, copper, brass, titanium, chromium, nickel, nickel chromium, and stainless steel. Among these, aluminum is particularly preferable. Accordingly, the glitter pigment of the present invention is preferably an aluminum pigment.

  It is known that when an aluminum pigment is blended in an aqueous paint, metal aluminum reacts with moisture to generate hydrogen. Therefore, the aluminum pigment used in the present invention is preferably one in which such generation of hydrogen is suppressed. Examples thereof include an aluminum pigment coated with an organic film or an inorganic film.

  Organic coatings include monomeric or polymer (oligomer) fatty acids such as dimer acids, organic phosphates, phosphate ester compounds, organic phosphonic acid compounds (esters), aminosilane compounds, organosilane compounds such as silane coupling agents, etc. Examples of inorganic coatings include borate, phosphate, phosphite, silicate, molybdate, vanadate, chromium oxide, zirconium oxide, and aluminum oxide. .

  Use of such an aluminum pigment whose surface of the metal pigment is stabilized is preferred because generation of hydrogen gas in the aqueous base coating composition can be suppressed.

  The aluminum pigment used in the present invention preferably has a hydrogen gas generation amount described below of 3 ml or less per gram of aluminum pigment. By using such an aluminum pigment, generation of hydrogen gas in the aqueous base coating composition can be suppressed, and safety when the coating is stored can be improved.

  The hydrogen gas generation amount is the hydrogen gas generation amount when a non-volatile component containing 2.5% by mass of an aluminum pigment is prepared and 10 days have passed after preparation of the paint at 50 ° C. Since the amount of hydrogen gas generated is easily affected by the aqueous solvent in the paint, it was measured here with a nonvolatile content of 2.5% by mass.

  In the aqueous base coating composition of the present invention, the content of the glitter pigment is preferably in the range of 20 to 70% by mass in terms of PWC. By increasing the PWC in the coating composition, the planar orientation of the glitter pigment can be promoted, and better metallic gloss can be imparted. However, if the PWC is too high, the adhesion in the laminated coating, that is, the adhesion to the underlying coating layer and the clear coating layer tends to be reduced. A more preferable range of PWC is in the range of 20 to 50% by mass, and particularly preferably in the range of 25 to 40% by mass.

  In the aqueous base coating composition of the present invention, an aqueous cellulose derivative is used as a main binder resin. However, if necessary, other binder resins may be further contained. Examples of such other binder resins include at least one selected from the group consisting of acrylic resins, melamine resins, urethane resins, and polyester resins. These resins are generally used as water-soluble resins or water-based emulsion resins. Preferable examples include acrylic resin, melamine resin and polyester resin, but those having high affinity with the surface of the aluminum pigment, for example, functional groups such as amino group, carboxyl group, phosphoric acid group or silicic acid group It is preferable to use one having This is because cohesive failure in the base coating layer can be suppressed.

  The above “main” means that the aqueous cellulose derivative is the main component of the binder in the coating composition.

  The ratio of the binder resin to the other binder resin is a solid content mass ratio (main binder resin: other binder resin), and is preferably in the range of 100: 0 to 50:50. If the ratio of the other binder resin is larger than this range, the glitter pigment cannot be oriented in a planar state in a good state, and the metallic gloss is lowered.

  The aqueous base coating composition of the present invention can be prepared by mixing a glitter pigment, an aqueous cellulose derivative (main binder resin), and, if necessary, another binder resin in an aqueous solvent. The aqueous cellulose derivative is preferably dissolved in a hydrophilic solvent, neutralized with a neutralizing agent such as an amine, and then dispersed in water, and this aqueous dispersion is added to the paint.

  The aqueous solvent used in the aqueous base coating composition of the present invention is not particularly limited, but a solvent having high water solubility is desirable. Examples include isopropyl alcohol, methanol, methyl glycol, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, methyl diglycol, hexyl glycol, methylpropylene glycol, methoxypropanol (propylene glycol monomethyl ether), methylpropylene diglycol, and the like. .

  The aqueous base paint composition of the present invention may be prepared in a state where the concentration of components other than the aqueous solvent is high, and when applying the paint, an aqueous solvent may be added and diluted to a predetermined concentration. The aqueous base coating composition of the present invention preferably has a coating non-volatile content of 5% by mass or less in a state where it can be applied after being diluted to a paintable viscosity. Furthermore, it is preferable to set it as the range of 2-4 mass%. By reducing the non-volatile content in this way, the angle formed between the coating film surface and the bright pigment can be reduced, and the planar orientation of the bright pigment can be increased, so that a good metallic gloss is obtained. It becomes easier to obtain.

  Further, in the aqueous base coating composition of the present invention, as necessary, waxes such as polyethylene wax and polypropylene wax, drying agents, dispersants, thickeners, ultraviolet absorbers, and light stabilizers may be used as additives. An agent, an antioxidant, a curing catalyst, and the like can be blended.

  The concentration of the binder resin (main binder resin and other binder resin) in the aqueous base coating composition of the present invention is preferably in the range of 30 to 80% by mass, more preferably in the range of 60 to 75% by mass. It is preferable to do.

  The laminated coating film of the present invention comprises a base coating layer formed on a substrate, a base coating layer formed on the base coating layer by applying the aqueous base coating composition of the present invention, and a base coating. And a clear coating layer formed on the film layer.

  The metal-tone laminated coating film of the present invention has a structure in which the base coating film layer, the base coating film layer, and the clear coating film layer are laminated as described above. In this state, the glitter pigment is oriented in a planar shape. For this reason, favorable metallic luster is shown.

  The article of the present invention is characterized in that the metallic tone laminated coating film of the present invention or the metallic tone multilayer coating film formed by the method of the present invention is provided on a substrate.

  The base material in this invention is not specifically limited, The thing in which metal glossiness is required can be used as a base material. For example, the metal-tone laminated coating film of the present invention can be formed on various parts such as automobile parts such as automobile wheels and handles, automobile bodies, electrical appliances, and cellular phones.

  The undercoat film layer in the present invention is preferably a colored paint film, and its color is preferably black. By making the base coating layer black, the reflection of light transmitted through the base coating layer is reduced, it is difficult to become white, and good metallic luster is exhibited.

  The thickness of the base coating layer is not particularly limited, but a range of 10 to 30 μm is common. In addition, the thickness of the clear coating layer in the present invention is not particularly limited, but generally the thickness is preferably in the range of 15 to 40 μm.

  In the present invention, the thickness of the base coating layer is preferably as thin as possible, generally 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less. The lower limit is not particularly limited, but is generally 0. .1 μm or more.

  The method for forming a metal-tone laminated coating film according to the present invention is a method by which the metal-tone laminated coating film according to the present invention can be formed. Forming a base coating layer by applying the aqueous base coating composition of the present invention on the base coating layer, and applying a clear coating on the base coating layer. And a step of forming a clear coating layer.

  The base paint and clear paint in the present invention may be solvent-based paints or water-based paints. Moreover, a powder coating material may be sufficient.

  The clear paint in the present invention may be a so-called colored clear paint.

  In the method for forming a laminated coating film of the present invention, for example, an aqueous base coating composition can be applied after applying a base coating and baking and curing. By baking and curing the base coating, it is possible to prevent the glitter pigment in the aqueous base coating composition from sinking into the base coating layer when the aqueous base coating composition is applied thereon. However, the present invention is not necessarily limited to applying the aqueous base coating composition after the base coating is baked and cured.

  In the method for forming a laminated coating film of the present invention, the aqueous base coating composition is applied and preliminarily dried, then the clear coating is applied, and then the base coating layer and the clear coating layer are simultaneously baked and cured. May be. In this way, the coating process can be simplified by performing the coating and baking hardening process by a so-called two-coat one-bake method. However, the present invention is not necessarily limited to the 2-coat 1-bake method, and after applying an aqueous base paint, it may be pre-dried, baked and cured, and then applied with a clear paint.

  Further, in the method for forming a laminated coating film of the present invention, a base coating is applied and pre-dried, an aqueous base coating composition is applied thereon and pre-dried, a clear coating is applied thereon, and then The base coating layer, the base coating layer, and the clear coating layer may be baked and cured simultaneously. That is, you may perform a painting and baking hardening process by what is called a 3 coat 1 bake system. Thus, a manufacturing process can be simplified by forming a coating film by a 3 coat 1 baking system. However, the present invention is not limited to such a 3-coat 1-bake method.

  The conditions for predrying the paint are not particularly limited, but it is generally preferable to dry the paint at a temperature in the range of 60 to 90 ° C. for 1 to 10 minutes.

  The conditions for the bake-hardening treatment are appropriately selected according to the binder resin used for each paint, but are generally bake-hardened by heating at a temperature of 120 to 160 ° C. for 10 to 40 minutes.

  ADVANTAGE OF THE INVENTION According to this invention, favorable metal-like glossiness can be provided with respect to various articles | goods using a water-based base coating composition.

  Hereinafter, the present invention will be described in detail with specific examples, but the present invention is not limited to the following examples.

  FIG. 1 is a schematic diagram for explaining a state in which an aqueous base coating composition and a glitter pigment in a coating film are oriented in a planar shape in the present invention.

  FIG. 1 (a) shows the state of the glitter pigment 1 in the aqueous base coating composition 3. In the coating composition in which a diluent is used in a large amount compared to a general coating, the glitter pigment 1 Exists in a random state.

  FIG.1 (b) has shown the state of the luster pigment 1 in the coating film 2 after coating on a base material. Since the aqueous solvent in the coating film 2 volatilizes gradually after coating, the thickness of the coating film 2 is gradually reduced. It becomes oriented in a plane.

  FIG. 1 (c) shows a state after setting the coating film 2 and after being baked and cured. In the coating film 2, the glitter pigment 1 is oriented in a planar shape to give a metallic gloss. .

  In the present invention, by using the aqueous cellulose derivative as the main binder resin, when the aqueous solvent in FIG. 1 (b) is gradually evaporated and the thickness of the coating film 2 is reduced, the migration of the glitter pigment 1 is performed. Therefore, it is considered that the glitter pigment 1 is oriented in a plane as the thickness of the coating film 2 is reduced.

  On the other hand, when the aqueous cellulose derivative is not used as the main binder resin, the glitter pigment 1 is likely to migrate in the coating film 2 which is being dried, and thus the thickness of the coating film 2 is reduced. However, the bright pigment 1 cannot be oriented in a planar state in a good state. For this reason, it seems that a favorable metallic luster cannot be obtained.

  Hereinafter, the present invention will be described with reference to specific examples.

[Darkness pigment]
As the glitter pigment, an aluminum powder paste containing aluminum powder obtained by pulverizing aluminum vapor-deposited powder was used. Specifically, the product name “HYDROSHINE WS3001” (manufactured by Big Chemie) was used.

[Aqueous cellulose derivative]
As the aqueous cellulose derivative, carboxymethyl cellulose acetate butyrate (trade name “CMCAB-641-0.2”, acid value 40 mgKOH / g, manufactured by Eastman Chemical Company) was used.

[Synthesis of acrylic resin]
40 parts by mass of propylene glycol monoethyl ether is charged into a Kolben equipped with a stirrer, a temperature controller, and a cooling pipe, and 8.86 parts by mass of styrene, 8.27 parts by mass of ethylhexyl acrylate, 15.00 parts by mass of lauryl methacrylate, 2 -Hydroxyethyl methacrylate 34.80 parts by mass, methacrylic acid 3.07 parts by mass, acid phosphooxyhexa (oxypropylene) monomethacrylate (JAMP-100N, Johoku Chemical Co., Ltd.) 30.00 parts by mass, mixed monomer solution 100 parts by mass, And 43 parts by mass of an initiator solution of 3.0 parts by mass of tertiary butyl peroctoate (Kayaester O) and 40 parts by mass of propylene glycol monoethyl ether were added dropwise at 115 ° C. over 3 hours, and then stirring was continued for 30 minutes. , Then tertiary butyl peroctoate (Kaya ester O) 0.3 parts by weight was added dropwise in 1 hour initiator solution 20.3 parts by weight of 20 parts by mass of propylene glycol monoethyl ether, and further stirring continued for 1.5 hours. The obtained product was a phosphoric acid group-containing acrylic resin having an acid value of 106 mgKOH / g, an acid value of 86 mgKOH / g from a phosphoric acid group, a hydroxyl value of 150, and a number average molecular weight of 5000, and the nonvolatile content was 49%.

[Preparation of aqueous base coating composition]
Example 1
10 parts by weight of the above aqueous cellulose derivative is dissolved in 45 parts by weight of a solvent (propylene glycol monomethyl ether), and 56 parts by weight of the above aluminum powder paste (trade name WS-3001: nonvolatile content 10% by weight, solvent: propyl alcohol). Then, 3.2 parts by weight of melamine resin (trade name “Cymel 325”, manufactured by Nippon Cytec Industries, non-volatile content 80% by mass) was added and stirred, and then 24 parts by mass of dimethylmethanolamine diluted to 10% by mass with water was stirred. While being added, 200 parts by mass of water was gradually added to prepare a water-soluble paint.

  The above-mentioned paint was diluted with a mixed diluent (a diluent obtained by mixing water and propylene glycol monomethyl ether in a ratio of 4: 1) so as to have a nonvolatile content of 2.5% by mass. I got a thing.

(Examples 2-6 and Comparative Examples 1-5)
An aluminum base, an aqueous cellulose derivative, a melamine resin, and an acrylic resin were mixed in the same manner as in Example 1 so that the blending ratio shown in Table 1 was obtained, to prepare an aqueous base coating composition.

  In addition, the aluminum pigment A shown in Table 1 is an aluminum pigment using said aluminum powder paste. As the aluminum pigment B, the following aluminum paste containing aluminum flakes used for general metallic paints obtained by grinding aluminum powder or aluminum foil with a ball mill or the like was used. Specifically, the trade name “Alpaste 7160” manufactured by Toyo Aluminum Co., Ltd. and aluminum flakes were used.

  Cellulose derivative A shown in Table 1 is the above-mentioned aqueous cellulose derivative, and cellulose derivative B used was cellulose acetate butyrate manufactured by Eastman Chemical Product Co., Ltd. under the trade name “CAB-381-2”.

  The acrylic resin shown in Table 1 is an acrylic resin produced as described above.

[Formation of laminated coating film]
Cationic electrodeposition paint (trade name “Power Top U-50”, cation type electrodeposition paint manufactured by Nippon Paint Co., Ltd.) is applied to a 0.8 mm thick, 10 cm × 30 cm thick steel plate treated with zinc phosphate. After electrodeposition coating to 20 μm, baking was performed at 170 ° C. for 30 minutes. On the substrate electrodeposited as described above, as a base paint, water-based paint (trade name “AR-2000 Black”, manufactured by Nippon Paint Co., Ltd., is spray-coated so that the dry film thickness is 20 μm. After pre-drying at 80 ° C. for 5 minutes, baking and curing treatment was performed at 140 ° C. for 20 minutes.

  Next, after spray-coating the aqueous base coating composition of Example 1-5 and Comparative Example 1-4 shown in Table 1 to a dry film thickness of 0.5 μm and pre-drying at 80 ° C. for 5 minutes, The clear paint was spray-coated so that the dry film thickness was 30 μm and set for 10 minutes. Then, the baking process was performed at 140 degreeC for 20 minute (s), and the laminated coating film was formed.

  As the clear paint, an acrylic melamine paint (trade name “Super Lac O-200 Clear”, manufactured by Nippon Paint Co., Ltd.) was used. In Comparative Example 5, a solvent-based base paint (trade name “Super Lac 5000 Sword Silver”, manufactured by Nippon Paint Co., Ltd.) using an organic solvent was used in place of the aqueous base paint composition.

  About the obtained coating film, the external appearance (metallic gloss), gloss (45 ° ∠) and initial adhesion were evaluated as follows.

[Appearance of coated film (metallic luster)]
The appearance of the coating film was evaluated by the naked eye according to the following criteria.

5: Extremely strong metal view 4: Strong metal view 3: There is a metal view 2: Some metal view is felt 1: Metallic view [Gloss (45 °)]
The gloss at an incident angle and an output angle of 45 ° was evaluated using a gloss meter.

[Initial adhesion]
Hold the cutting blade of the cutter (NT cutter S type, A type or equivalent) at about 30 degrees with respect to the coating film, draw 11 parallel lines with a spacing of 2 mm to reach the substrate, and further to these parallel lines Eleven parallel lines that intersected each other at an interval of 2 mm were drawn to form 100 grids on the coating film. After the adhesive tape (industrial adhesive tape manufactured by Nichiban Co., Ltd.) is uniformly pressed with fingertips on this grid so that no air bubbles remain, immediately hold one end of the adhesive tape and approximately 45 degrees to the coating surface. The tape was peeled off from the coating film at a sharp angle to remove the tape from the coating film, and the number of grids from which 100 coating films were peeled was measured.

[Water dilution stability]
The state of the paint when diluted with a mixed diluent to a non-volatile content of 2.5% by mass was evaluated as “water dilution stability” and shown in Table 1. “Stable” indicates that a stable state is maintained even when diluted with water, and “separated” means that the paint separated into two layers when diluted with water.

[Hydrogen gas generation amount]
About the coating material diluted so that the non volatile matter might be 2.5 mass%, the hydrogen gas generation amount was calculated | required as follows. The diluted water-based base paint was placed in a pressure-resistant container having a gas vent so that the filling rate would be 80% at room temperature and sealed. It was left to stand at 50 ° C. for 10 days, and then left to return to room temperature. Next, the generated gas was recovered from the gas vent into the graduated cylinder by an underwater substitution method, and its volume was measured and converted per 1 g of pigment.

  As is clear from the results shown in Table 1, in Examples 1 to 6 according to the present invention, a good metallic gloss was obtained and the initial adhesion was excellent. On the other hand, in Comparative Example 1 in which the PWC is 10% by mass and in Comparative Example 2 in which the PWC is 80% by mass, good metallic gloss is not obtained.

  Alternatively, in Comparative Example 5 using an aqueous cellulose derivative having an acid value of 0 mgKOH / g, the paint was in a separated state, and a coating film could not be formed.

  Further, in Comparative Example 4 using the conventional aluminum flake pigment, the metallic luster as in the present invention was not obtained.

  As described above, according to the present invention, a good metallic gloss similar to that of a conventional solvent-based paint can be obtained using an aqueous base paint.

The schematic diagram for demonstrating the orientation state of a luster pigment when forming a base coating film layer using the water-based base coating composition of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bright pigment 2 ... Coating film 3 ... Water-based base coating composition

Claims (13)

A glittering pigment obtained by pulverizing a deposited metal film into a metal piece, and an aqueous cellulose derivative as a binder resin having an acid value of 20 to 150 mg KOH / g (solid content), the aqueous cellulose derivative and other binder resins Is a solid content mass ratio (aqueous cellulose derivative: other binder resin) and is in the range of 100: 0 to 50:50, and the content of the glitter pigment is 20 to 70% by mass in PWC An aqueous base coating composition characterized by the above.   The aqueous base coating composition according to claim 1, wherein the aqueous cellulose derivative is carboxymethyl cellulose acetate butyrate.   The aqueous base paint composition according to claim 1 or 2, wherein the non-volatile content of the paint at the time of application is 5% by mass or less. The aqueous base according to any one of claims 1 to 3, wherein the other binder resin is at least one selected from the group consisting of an acrylic resin, a melamine resin, a urethane resin, and a polyester resin. Paint composition. The water-based paint composition according to any one of claims 1 to 4 , wherein the glitter pigment is an aluminum pigment. 6. The aqueous base coating composition according to claim 5 , wherein the aluminum pigment is an aluminum pigment coated with an organic coating or an inorganic coating. A paint having a non-volatile content of 2.5% by mass containing an aluminum pigment was prepared, and the hydrogen gas generation amount after 10 days at 50 ° C. after the preparation of the paint was 3 ml or less per gram of aluminum pigment contained in the paint. The aqueous base coating composition according to claim 5 or 6 , wherein an aluminum pigment such as is used as the glitter pigment. A base coating layer formed on a substrate;
A base coating layer formed on the undercoat coating layer by applying the aqueous base coating composition according to any one of claims 1 to 7 ,
And a clear coating film layer formed on the base coating film layer. A method for forming a metallic laminate film according to claim 8 , comprising:
Forming the base coating layer by applying a base coating on the substrate; and
Forming the base coating layer by applying the aqueous base coating composition on the base coating layer;
And a step of forming the clear paint film layer by applying a clear paint on the base paint film layer. The method for forming a metallic layered coating film according to claim 9 , wherein the aqueous base coating composition is applied after the base coating is applied and baked and cured. The aqueous base coating composition was applied, after pre-drying, the clear paint was coated, according to claim 9 or 10, then the base coating film layer and the said simultaneously baking and curing a clear coating film layer The formation method of the metal-tone laminated coating film of description. The base coating is applied and pre-dried, the aqueous base coating composition is applied thereon and pre-dried, and the clear coating is applied thereon, and then the base coating layer and the base coating are applied. The method for forming a metal-tone laminated coating film according to claim 9 , wherein the layer and the clear coating film layer are baked and cured simultaneously. A metal-tone laminate coating film according to claim 8 or a metal-tone laminate coating film formed by the method according to any one of claims 9 to 12 is provided on a substrate. Goods to do.

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