JP2002177867A - Coating film forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating film forming method capable of easily and efficiently preventing defective coating film appearance owing to self-dust. SOLUTION: The coating film forming method comprises the steps of carrying out wet-on-wet coating on a substrate successively with a solvent-type metallic base coating material and a clear coating material using an electrostatic coating apparatus and then curing both coating films simultaneously. In the method, and solvent type metallic base coating material contains an ester type organic solvent with a boiling point of 140-190 deg.C and an ester type organic solvent with a boiling point of 191-280 deg.C in (1/4) to (1/1) ratio by weight in the state that the coating material is diluted to a coating viscosity and contains the total of the ester type organic solvents in amount of 2-10 wt.% in the total of diluted coating material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a coating film on a base material of an automobile body or the like by using a solvent type coating material by using an electrostatic coating machine, and a laminated coating film obtained by the method. .

[0002]

2. Description of the Related Art Coatings requiring high appearance characteristics, such as automobiles, are provided with a multilayer coating having a plurality of coatings. For example, in the case of automobiles, an electrodeposition coating with high rust resistance is applied on a metal substrate, an intermediate coating film is formed, and then a metallic base coating and a clear coating are applied on a wet-on-wet basis to apply both coatings. Are simultaneously baked and cured to form a topcoat film, thereby completing a laminated coating film.

[0003] Metallic base paint and clear paint are
Although the transition to water-based paint is progressing from consideration for the environment,
Solvent-type paints using an organic solvent as a diluent are still frequently used.

[0004] In the case of a solvent-type paint, the solvent to be mixed is determined mainly from the viewpoints of dispersibility or adaptability to resins and pigments contained in the paint, and further from the viewpoint of workability in painting. For example, Japanese Patent Application Laid-Open No. 62-163771 proposes a method in which a solvent having a boiling point of 150C or more is selectively used for a thinner for a vertical portion and a thinner for a horizontal portion. According to this method, it is possible to prevent poor appearance such as side and sagging, and the coating workability is improved.

[0005] On the other hand, when an object to be coated is applied, paint dust scattered from a portion to be applied later may fall on the previously formed continuous coating film. It is known that this may cause poor appearance of the coating film, such as a feeling of flicker and flicker. This so-called self-dusting property is more often seen when a large and uneven article such as an automobile body is painted.

Conventionally, self-dust has been prevented by a method such as the addition of a surface conditioner.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple and effective method for preventing the coating film from being defective due to self-dust as described above.

[0008]

According to the present invention, paint dust is generated when a solvent-type metallic base paint is applied and adheres to a previously formed paint film. The above object was achieved by controlling the solvent blending of the solvent-type metallic base paint itself so that a smooth surface was formed and the bad appearance of the coating film due to self-dust was minimized.

That is, according to the present invention, a solvent-type metallic base paint and a clear paint are sequentially applied on a substrate in a wet-on-wet manner using an electrostatic coating machine, and then both the coating films are cured at a time. In the method for forming a coating film, the solvent-type metallic base paint, when diluted to a coating viscosity, comprises an ester organic solvent having a boiling point of 140 to 190 ° C and an ester organic solvent having a boiling point of 191 to 280 ° C. /
Provided is a method for forming a coating film, characterized in that the weight ratio of the ester-based organic solvent is 2 to 10% by weight based on the total amount of the diluted paint in a weight ratio of 4 to 1/1.

[0010] The present invention also provides a laminated coating film formed by the above method. Further, the present invention provides a metallic base paint used in the above method. Hereinafter, the present invention will be described in more detail.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Metallic Base Coating In the coating forming method of the present invention, a metallic base coating is used to form a metallic base coating. It may contain a film-forming resin, a curing agent, a brilliant pigment, various organic or inorganic coloring pigments and extenders.

As the organic solvent as the diluting medium, an ester organic solvent having a boiling point of 140 to 190 ° C. and a boiling point of 191 to 280 ° C. in a state where the metallic base coating material used in the present invention is diluted to a coating viscosity. Containing an ester organic solvent at a weight ratio of 1/4 to 1/1, and
The ester organic solvent is contained in a total amount of 2 to 10% by weight based on the total amount of the diluted paint. Outside the above range, the coating workability and the appearance of the formed coating film deteriorate. Preferably, an ester organic solvent having a boiling point of 140 to 190 ° C. and an ester organic solvent having a boiling point of 191 to 280 ° C.
/ 3 to 1/1, and in a state where the metallic base paint is diluted to a coating viscosity, the ester organic solvent content is 3 to 9% by weight based on the total weight of the metallic base paint.
contains.

Further, the total amount of the organic solvent at the time of dilution of the metallic base paint containing the ester organic solvent is 55 to 85.
% By weight. Outside the above range, the coating workability and the appearance of the formed coating film deteriorate. Particularly preferably, the total amount of the organic solvent content of the metallic base paint containing the above-mentioned ester-based organic solvent when diluted is 60 to 80% by weight.

Further, the above-mentioned metallic base coating material used in the present invention is diluted with the ester-based organic solvent having a boiling point of 140 to 190 ° C. and the boiling point of 191 to 190 ° C. within the total amount of the organic solvent as a diluting medium when the coating viscosity is diluted. It is preferable that a total ester organic solvent including an ester organic solvent at 280 ° C. and other organic solvents are contained in a weight ratio of 1/5 to 1/20. If the upper limit is exceeded, poor appearance such as sagging or conformation may occur, and if the lower limit is not reached, poor appearance such as side or cracked skin may occur.

Examples of the ester organic solvent having a boiling point of 140 to 190 ° C. include ethylene glycol monoethyl ether acetate (commonly called “cellose”, boiling point 156).
° C), propylene glycol monomethyl ether acetate (commonly referred to as “PMAC”, boiling point 144 ° C), isoamyl acetate (boiling point 143 ° C), oxohexyl acetate (commonly referred to as “OHA”, boiling point 170 ° C), methyl methoxybutyl acetate (commonly known as “SOLFIT”) Acetate ", boiling point 1
88 ° C.), ethyl ethoxypropionate (commonly known as “EE
P ", boiling point 169 ° C).

Particularly, among the above organic solvents, it is preferable to use a non-glycol ester organic solvent because of its excellent compatibility in a paint state. For example, isoamyl acetate (boiling point: 143 ° C.), oxohexyl Acetate (commonly referred to as “OHA”, boiling point 170 ° C.), methyl methoxybutyl acetate (commonly referred to as “solfit acetate”, boiling point 188 ° C.), ethylethoxypropionate (commonly referred to as “EEP”, boiling point 169 ° C.) and the like can be given.

Examples of the ester-based organic solvent having a boiling point of 191 ° C. to 280 ° C. include ethylene glycol monobutyl ether acetate (commonly called “Buticello”, boiling point 191).
° C), diethylene glycol monoethyl ether acetate (commonly called “carbitol acetate”, boiling point 217 ° C), diethylene glycol monobutyl ether acetate (commonly called “butyl acetate”, boiling point 246 ° C) and the like.

Among the above-mentioned organic solvents, in particular, they have excellent compatibility in the state of a coating film. For example, diethylene glycol monoethyl ether acetate (commonly referred to as "carbitol acetate", boiling point of 217 ° C.), diethylene glycol monobutyl ether acetate ( It is preferable to use a so-called “butyl carbitol acetate”, having a boiling point of 246 ° C.).

Other organic solvents that can be used include ethyl acetate (boiling point 77 ° C.), butyl acetate (boiling point 1
26 ° C.), isobutyl acetate (boiling point 118 ° C.) and other ester-based organic solvents other than the above boiling point range, methylmethoxybutanol (commonly called “Solfit”), methoxypropanol (commonly called “MP”), ethoxypropanol (commonly called “EP”) )), Ethylene glycol monoethyl ether (commonly referred to as “Ethicello”, boiling point 135 ° C.), ethylene glycol monobutyl ether (commonly known as “Buticello”, boiling point 17)
1 ° C.), diethylene glycol monoethyl ether (commonly referred to as “Eticabi”, boiling point 196 ° C.), diethylene glycol monobutyl ether (commonly known as “Buchikabi”, boiling point 230)
° C), propylene glycol monomethyl ether (commonly known as “PM”, boiling point 121 ° C), ethylene glycol monohexyl ether (commonly known as “hexyl cellosolve”, boiling point 2)
08 ° C.), alcohol-based organic solvents such as methanol, butanol, ethanol, and propyl alcohol; ketone-based organic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone; n-hexane, heptane, cyclohexane; Examples include aliphatic organic solvents such as mineral spirits and solvent naphtha, and aromatic organic solvents such as toluene, xylene, S-100 (organic solvent manufactured by Esso), and S-150 (organic solvent manufactured by Esso).

The above film-forming resin has a number average molecular weight of 5
It is preferably from 000 to 30,000, more preferably from 7,000 to 25,000. If it is smaller than 5,000, the workability and curability are not sufficient, and if it exceeds 30,000, the non-volatile content at the time of coating becomes too low, and the workability worsens. In the present specification, the molecular weight is determined by a GPC method using a styrene polymer as a standard.

Further, the film-forming resin is preferably 20 to 18
It preferably has a hydroxyl value of 0, preferably 30
~ 160. Exceeding the upper limit lowers the water resistance of the coating film, while lowering the lower limit lowers the curability of the coating film. Also, 2
Preferably having an acid value of ~ 30 mg KOH / g,
More preferably, it is 3 to 25 mgKOH / g. Exceeding the upper limit lowers the water resistance of the coating film, while lowering the lower limit lowers the curability of the coating film.

Preferred examples of the film-forming resin include an acrylic resin, a polyester resin, an alkyd resin, a polyether resin, a polyolefin resin, and a urethane resin. One type or a combination of two or more types may be used. Can be used. It is preferable to use an acrylic resin or a polyester resin from the viewpoint of coating performance such as weather resistance and water resistance.

Preferred examples of the curing agent include amino resins, blocked isocyanate resins, epoxy compounds, aziridine compounds, carbodiimide compounds, oxazoline compounds and the like. Amino resins and / or blocked isocyanate resins are generally used from the viewpoints of various properties and cost of the obtained coating film.

The content of the above curing agent is 20 to 100% by weight based on the solid content of the film-forming resin. 20 content
If the amount is less than 100% by weight, the curability becomes insufficient. If the amount exceeds 100% by weight, the cured film becomes too hard and brittle.

The brilliant pigment is not particularly limited in its shape and may be further colored. For example, the brilliant pigment has an average particle size (D ₅₀ ) of 2 to ₅₀ μm and a thickness of 0.1 to 0.1 μm.
Those having a thickness of 5 μm are preferred. In addition, the average particle size is 10
Those having a range of 35 μm have excellent glitter and are more preferably used.

[0026] The pigment concentration (PW
C) is generally at most 20.0%. If it exceeds the upper limit, the appearance of the coating film will be reduced. Preferably, 0.01% to 1%
8.0%, and more preferably 0.1% to 15.0.
%. When the content of the glittering agent exceeds 20.0% by weight, the appearance of the coating film deteriorates.

The glitter pigments include aluminum,
Non-colored or colored metal glitters such as metals or alloys such as copper, zinc, iron, nickel, tin and aluminum oxide, and mixtures thereof. Further, interference mica pigments, white mica pigments, graphite pigments, and other colored or colored flat pigments may be used in combination.

The total pigment concentration (PWC) in the paint, including the bright pigment and all other pigments, is 0.1.
1% to 50%, preferably 0.5% to 40%, more preferably 1.0% to 30%. If it exceeds the upper limit, the appearance of the coating film will be reduced.

Examples of the coloring pigment include organic azo chelate pigments, insoluble azo pigments, condensed azo pigments, diketopyrrolopyrrole pigments, benzimidazolone pigments, phthalocyanine pigments, indigo pigments, and perinone pigments. And perylene-based pigments, dioxane-based pigments, quinacridone-based pigments, isoindolinone-based pigments, metal complex pigments, and the like. Inorganic-based pigments include graphite, yellow iron oxide, red iron oxide, carbon black, and titanium dioxide.
As the extender, calcium carbonate, barium sulfate, clay, talc and the like are used.

Further, a viscosity controlling agent can be added to the metallic base paint in order to prevent break-in with the clear coating film and to secure coating workability. As the viscosity control agent, those which generally exhibit thixotropic properties can be used, for example, swelling dispersions of fatty acid amides, amide-based fatty acids, polyamide-based ones such as long-chain polyaminoamide phosphates, and colloidal swelling dispersions of polyethylene oxide. Polyethylene bentonite, organic acid smectite clay, organic bentonite such as montmorillonite,
Examples of the viscosity control agent include inorganic pigments such as aluminum silicate and barium sulfate, flat pigments exhibiting viscosity depending on the shape of the pigment, and crosslinked or non-crosslinked resin particles.

In the metallic base paint used in the present invention, in addition to the above components, additives usually added to the paint,
For example, a surface conditioner, an antioxidant, an antifoaming agent and the like may be added. These amounts are within the range known to those skilled in the art.

The method for producing the coating composition used in the present invention is not particularly limited, including those described below, and those skilled in the art such as kneading and dispersing a compound such as a pigment using a kneader or a roll. All known methods can be used.

The clear coating is used to form the clear coating the clear coating film. The clear paint is not particularly limited, and a paint containing a film-forming resin, a curing agent, and the like can be used. Examples of the form of the clear coating include a solvent type, an aqueous type and a powder type.

Preferred examples of the solvent-type clear paint include a combination of an acrylic resin and / or a polyester resin and an amino resin, or an acrylic resin having a carboxylic acid / epoxy curing system in terms of transparency or acid etching resistance. Resins and / or polyester resins.

Examples of the water-based clear paint include a resin obtained by neutralizing a film-forming resin contained in the above-mentioned solvent-based clear paint with a base to make it water-based. Things can be mentioned. This neutralization can be carried out before or after the polymerization by adding a tertiary amine such as dimethylethanolamine and triethylamine.

On the other hand, as the powder type clear coating material, an ordinary powder coating material such as a thermoplastic and thermosetting powder coating material can be used. A thermosetting powder coating is preferred because a coating film having good physical properties can be obtained. Specific examples of the thermosetting powder coating include epoxy, acrylic, and polyester powder clear coatings, and the like.
An acrylic powder clear coating having good weather resistance is particularly preferred.

As the powder type clear coating material used in the present invention, there is no volatile matter at the time of curing, a good appearance is obtained, and there is little yellowing.
Powder coatings based on polycarboxylic acids are particularly preferred.

Further, it is preferable that a viscosity control agent is added to the clear coating material in order to ensure the workability of coating, similarly to the intermediate coating material described above. As the viscosity controlling agent, those exhibiting thixotropy can be generally used. As such a material, for example, those described in the description of the intermediate coating material can be used. If necessary, a curing catalyst, a surface conditioner and the like can be included.

Substrate The coating film forming method of the present invention can be advantageously used for various substrates, for example, metals, plastics, foams and the like, particularly metal surfaces and castings. Can be particularly preferably used.

Examples of the above metal products include iron, copper,
Aluminum, tin, zinc, and the like, and alloys containing these metals are included. Specific examples include automobile bodies and parts such as passenger cars, trucks, motorcycles, and buses. It is particularly preferable that these metals have been previously subjected to a chemical conversion treatment with a phosphate, a chromate or the like.

Further, the substrate used in the method for forming a metallic coating film of the present invention may have an electrodeposition coating film and an intermediate coating film formed on a steel sheet which has been subjected to a chemical conversion treatment. As the electrodeposition paint for forming the electrodeposition coating film, a cationic type and an anion type can be used, but a cationic type electrodeposition coating composition is preferable because it gives a laminated coating film having excellent corrosion resistance.

As the intermediate coating material for forming the intermediate coating film, a gray-based melamine-curable or isocyanate-curable paint containing carbon black and titanium dioxide as main pigments is used. Further, a combination of a hue with the top coat and a combination of various coloring pigments can also be used.

[0043] In the coating film formation method of a coating film forming method invention, on a substrate, a metallic base coating film and clear coating film is formed by wet-on-wet using an electrostatic sprayer.

When a metallic base paint is applied to an automobile body in the present invention, an electrostatic coating machine is used in order to improve workability and appearance. As an example of this electrostatic coating machine, for example, an air electrostatic spray coating called “react gun” or a so-called “μμ (micro micro) bell”,
A rotary atomization type electrostatic coating machine called "μ (micro) bell" or "meta bell" is exemplified. These include multi-stage coating, preferably 2-3 stage coating, and a coating film can also be formed by a coating method or the like in which air electrostatic spray coating and a rotary atomizing electrostatic coating machine are combined. .

The state in which the metallic base paint is diluted to the coating viscosity is defined as the atomization method of the electrostatic coating machine described above or the coating viscosity determined empirically based on factors such as the coating environment such as temperature and humidity. 2 shows a state in which the mixture is diluted with an organic solvent as a diluting medium and the viscosity is adjusted.
Generally, the coating viscosity at a temperature of 10 ° C. to 40 ° C. and a humidity of 10% to 98% is 10 to 30 seconds (/ 20 ° C. · No.
4 Ford Cup). Outside this range, defects in appearance such as sagging and armpits are likely to occur. More preferably, it is 11 to 20 seconds (/ 20 ° C, No. 4 Ford cup).

In the present invention, the dry film thickness of the coating film formed by the metallic base paint varies depending on the desired application, but the dry film thickness can be set to 5 to 35 μm, preferably 7 to 25 μm. is there. If the thickness of the metallic base coating film exceeds 35 μm, the sharpness may be reduced, or the coating film may be uneven or run off.
If the ratio is less than 30, the base concealing property becomes insufficient, and the film may be cut (a state where the coating film is discontinuous), which is not preferable.

In the method for forming a coating film of the present invention, a clear coating material is further applied on the uncured metallic base coating film on a wet basis to form a clear coating film.

In the method of forming a coating film of the present invention, the clear coating film formed after the formation of the metallic base coating film may include irregularities caused by the metallic base coating film, and flickering that occurs when a brilliant pigment is contained. , And
Formed to protect. Specifically, as a coating method, it is preferable to form a coating film by using a rotary atomizing electrostatic coating machine such as a μμ bell or μ bell described above.

The dry film thickness of the clear coating film formed by the clear coating is generally preferably about 10 to 80 μm, more preferably about 20 to 60 μm. If the upper limit is exceeded, problems such as splashes or sagging may occur during coating. If the lower limit is not reached, irregularities on the base cannot be concealed.

The laminated coating film obtained as described above is cured at the same time, that is, a coating film is formed by so-called two coats and one bake. In this case, the baking / drying furnace can be omitted, which is preferable in terms of economy and environment.

The curing temperature for curing the laminated coating film is 80
By setting the temperature to 180 ° C, preferably 120 ° C to 160 ° C, a cured coating film having a high degree of crosslinking can be obtained. When the amount exceeds the upper limit, the coating film becomes hard and brittle, and when the amount is less than the lower limit, curing is not sufficient. The curing time varies depending on the curing temperature.
A temperature of 160 ° C. for 10 to 30 minutes is appropriate.

The film thickness of the laminated coating film formed in the present invention is usually 30 to 300 μm, preferably 50 to 2 μm.
50 μm. If it exceeds the upper limit, the physical properties of the film such as a thermal cycle decrease, and if it falls below the lower limit, the strength of the film itself decreases.

[0053]

EXAMPLES The present invention will be described in detail with reference to specific examples, but the present invention is not limited to the following examples. In the following, “parts” means “parts by weight”.

Production Example Production of Film-Forming Resin 80 parts of xylene and 20 parts of butyl acetate were charged into a 1 L reaction vessel equipped with a nitrogen inlet tube, a stirrer, a temperature controller, a dropping funnel and a cooling tube. 120 ° C. 5 parts of styrene, 30 parts of methyl methacrylate, 10.4 parts of 2-hydroxyethyl methacrylate, 44.4 parts of ethyl acrylate, 7 parts of ethyl methacrylate, 2.3 parts of methacrylic acid and 2 parts of t-butylperoxy-2-hexanoate A monomer solution was separately prepared by mixing. This monomer solution was added to the reaction vessel over 3 hours with stirring, and then stirring was continued for 1 hour. Number average molecular weight 21000, hydroxyl value 45 and acid value 15 mg KOH
/ G of acrylic resin 1 was obtained.

Example 1 Metallic base paint 1 Aluminum pigment paste "Alpaste 91-056"
2 "(Toyo Aluminum Co., Ltd., aluminum content 65
%) (10 parts) and 30 parts of "Uban 20N60" (butylated melamine resin manufactured by Mitsui Toatsu Co., Ltd.) were added and mixed uniformly.
Further, 10 parts of crosslinkable resin particles (manufactured by Nippon Paint Co., Ltd., average particle size 55 nm by dynamic light scattering method, solid content 20%, xylene solution) were added to 70 parts of the acrylic resin 1 obtained in the above Production Example. In addition, the mixture was further uniformly dispersed to obtain a metallic base paint 1 (organic solvent content: 64% by weight). In addition, the compounding amount (part) was shown by solid content. Then
Ethyl ethoxypropionate (commonly referred to as “EEP”, boiling point 169 ° C.) was added in an amount of 6% to this metallic base paint 1, and diethylene glycol monobutyl ether acetate (commonly known as “butyl acetate”, boiling point 246 ° C.) was added. Toluene /
The mixture was diluted with a diluting solvent consisting of ethyl acetate / ethoxypropanol = 5/2/3 for 12.5 seconds (measured at 20 ° C. using a No. 4 Ford cup).

The After zinc coating film forming method phosphoric acid treatment, the cationic electrodeposition paint "Power Top V-20" (manufactured by Nippon Paint Co., Ltd.), dry film thickness 20
μm, and an intermediate paint “Olga TO-870 Gray” (polyester melamine paint manufactured by Nippon Paint Co., Ltd.) on a coated plate baked at 160 ° C. for 30 minutes.
Was applied so as to have a dry film thickness of 20 μm.

Next, the diluted metallic base coating material 1 diluted in the above preparation example was applied to a “Metabell” under an environment of 27 ° C. and 70% humidity so as to have a dry film thickness of 15 μm.
Stage painted. There was a 1.5 minute interval between the two applications. Then, after an interval of 5 minutes, paint dust was sprayed on a half surface of the coated plate from a location about 1 m away using a hand spray gun, and setting was performed for 8 minutes.

Next, Olga TO-563 Clear (acrylic / melamine-curable clear paint manufactured by Nippon Paint Co., Ltd.)
Was subjected to one-stage coating using a “microbell” so as to have a dry film thickness of 40 μm, and set for 10 minutes.
Next, the obtained coated plate was baked at 140 ° C. for 30 minutes using a dryer. With respect to the paint dust-applied portion (dust portion) and the paint dust-unapplied portion (non-dust portion) of the obtained coated plate, the appearance of the coating film, particularly glossiness, was visually evaluated according to the following evaluation criteria. <Glossy criterion> 5: Very glossy 4; Glossy 3; Glossy 2; Slightly glossy 1; No glossiness.

Further, the non-dust portion of the obtained coated plate is referred to as “C
R-354 "(Minolta's variable angle colorimeter)
After measuring the L value at measurement angles of 15 degrees and 110 degrees, F
The F value (L value of 15 degrees / L value of 110 degrees) was calculated and evaluated as flip-flop property. Table 1 shows the above results.

Examples 2 to 4 Metallic base paint 1 previously obtained in the above preparation example
Was prepared so as to be diluted with the organic solvent components shown in Table 1, and applied in the order of a metallic base paint and a clear paint in the same manner as in Example 1 to prepare and evaluate a laminated coating film. In Example 3, diethylene glycol monobutyl ether acetate was blended in place of diethylene glycol monoethyl ether acetate. Example 4
In this example, oxohexyl acetate was added instead of ethylethoxypropionate.

Comparative Examples 1 and 2 In Comparative Example 1, the diethylene glycol monoethyl ether acetate of Example 1 was not used, and in Comparative Example 2, the mixture was diluted with the organic solvent shown in Table 1 without using ethylethoxypropionate. Other than the above, a metallic base paint and a clear paint were applied in the same manner to prepare and evaluate a laminated coating film. Table 1 shows the evaluation results of the above Examples and Comparative Examples.

[0062]

[Table 1]

In the embodiment of the present invention, the metallic base coating film and the clear coating film are coated under a condition in which the self-paint dust of the metallic base coating material is applied, and the laminated film having excellent gloss and flip-flop properties is obtained. A coating was obtained.

[0064]

As shown in the examples of the present invention, by controlling the composition of the organic solvent contained in the metallic base coating film in a state diluted to the coating viscosity, the compatibility between the layers of each coating film, It is considered that mixing can be suppressed, and on the other hand, the ability to absorb the paint dust into the paint film is exhibited by adjusting the solvent balance between the metallic base paint film and the paint dust.

According to the method of the present invention, it is possible to control a decrease in gloss caused by coating conditions when a metallic base coating film and a clear coating film are sequentially coated, and to provide a laminated coating film having a high appearance industrially. Now you can do it.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 201/00 C09D 201/00

Claims (3)

[Claims] 1. A coating film forming method in which a solvent type metallic base coating material and a clear coating material are sequentially coated on a substrate by wet-on-wet using an electrostatic coating machine, and then both coating films are cured at a time. In the above, the solvent-type metallic base paint is diluted to a coating viscosity, and has a boiling point of 140 to 19.
An ester organic solvent having a boiling point of 191 to 280.
C. and an ester organic solvent at a weight ratio of 1/4 to 1/1 and a total of 2 to 10% by weight of the ester organic solvent based on the total amount of the diluted paint. Coating film forming method. 2. A laminated coating film formed by the method according to claim 1. 3. A solvent-based metallic base paint used in the method according to claim 1.