JP2000271536A - Method for forming metallic coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a concealing property so that a difference in a hue according to a coated part is not generated while a flip-flop property is maintained as it is in a metallic coating film. SOLUTION: In a method for forming a metallic coating film by two coat one bake wherein a metallic base coating film layer containing a brilliant pigment and a clear coating film layer are finished by wet on wet on a base material precoated and intercoated when necessary, a metallic base coating to be used for forming the metallic base coating film layer contains 0.01-15.0 pts.wt. of a flaked graphite pigment of about 3-10 μm average particle size and at most 1 μm thickness to 100 pts.wt. of a scaly aluminum pigment.

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 metallic coating film used for painting automobile bodies and the like, and a laminated coating film obtained by the method.

[0002]

2. Description of the Related Art In order to respond to various needs and various colors of an overcoat, a metallic coating film formed by a so-called metallic base paint containing a scaly brilliant pigment is increasing. Although this coating film can form a coating film having excellent flip-flop properties and appearance as compared with a so-called solid coating film, there are many problems related to “transparency” due to the use of a scaly glittering pigment.

For example, when a repair is performed for a coating film abnormality, a "transparent" coating film has a low hiding power, so that a difference in film thickness between an unrepaired portion and a repaired peripheral portion that has been coated twice is used. And a hue shift may occur. In addition, when a "transparent" metallic coating is formed on top of a sash black coating as a base, a hue shift occurs on the appearance due to the difference in brightness between the bases, May be significantly reduced.

[0004] In order to solve these problems, there is a method of coating a middle coat in which the brightness and chromaticity of the middle coat are adjusted.
The addition of special coating for special coating colors is economically disadvantageous and does not solve the problem of "transparency" of metallic coatings.

[0005] On the other hand, a means for increasing the film thickness in order to eliminate the "transparency" of the coating film is conceivable. However, at present, the coating film abnormality such as sagging and cracking occurs. It is known that the addition of a carbon black pigment can improve the concealing property. However, the usable coating color is limited, and the flip-flop property is also reduced.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the concealing property of a metallic coating so as to prevent the occurrence of a hue difference depending on the coated portion while maintaining the flip-flop property.

[0007]

According to the present invention, a metallic base coating layer containing a brilliant pigment and a clear coating layer are finished by wet-on-wet on an undercoated and, if necessary, an intermediate-coated substrate. In the method for forming a metallic coating film by two coats and one bake, the metallic base paint used for forming the metallic base coating layer is
A metallic coating film characterized by containing a scaly graphite pigment having an average particle diameter of about 3 to 10 μm and a thickness of 1 μm or less with respect to 100 parts by weight of a flaky aluminum pigment, in an amount of 0.01 to 15.0 parts by weight. The present invention provides a forming method. The present invention further provides a coating film formed by the above method.

Hereinafter, the present invention will be described in more detail.

In the method for forming a metallic coating film of the present invention, a metallic base coating material containing a luminous flaky aluminum pigment is applied to a substrate on which an undercoat and, if necessary, an intermediate coating have been formed. . Metallic base paints containing flaky aluminum pigments, other than flaky aluminum pigments, flaky graphite pigments, other brilliant materials, various organic or inorganic coloring pigments and extenders, thermosetting coating film formation It may further contain a resin and a curing agent.

The metallic base paint used for forming the metallic coating film of the present invention has an average particle size of about (D50) 5-5.
It contains a scale-like aluminum pigment having a thickness of 0 μm and a thickness of 0.1 to 10 μm. Particularly, it is possible to form a coating film excellent in design in a metallic base paint containing a flaky aluminum pigment having an average particle size of about 15 to 30 μm, and further has an average particle size of about 15 to 25 μm and a thickness of 0.2 to 2.5 μm. When a high-brightness aluminum pigment is contained, a coating film having very strong glitter, high flip-flop property, and excellent design can be formed.

For example, as a scaly high-brightness aluminum pigment, "Alpaste 91-0562 (trade name)" (trade name: solid content: 7 μm, manufactured by Toyo Aluminum Co., Ltd.) having an average particle size of 16 μm.
2%).

The metallic base paint used in the present invention has an average particle size of about 3 to 10 μm as a hiding agent.
Is added in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the flaky aluminum pigment (solid content).

The scaly graphite pigment contained in the metallic base paint used in the method for forming a metallic coating film of the present invention is such that graphite is pulverized into a scaly shape and is suitable as a pigment for a paint for adjusting the particle diameter and the like. And a graphite pigment coated with a metal oxide, for example, titanium dioxide, which emits interference light, and those having no interference light are excellent in improving the concealing property.

The size is 3 to 10 μm in average particle size,
Those having a thickness of 1 μm or less and having good dispersibility are preferred.
More preferably, the average particle diameter is 5 to 9 μm and the thickness is 0.01 to 0.5 μm.

For example, examples of the flaky graphite pigment include "Graphtan 7525 (trade name)" manufactured by Ciba-Geigy and having an average particle size of 8 μm.

The content of the flaky graphite pigment is based on 100 parts by weight of the flaky aluminum pigment (solid content).
It is 0.01 to 15.0 parts by weight, and if it exceeds the upper limit, the appearance (gloss) of the coating film is reduced, and if it is less than the lower limit, the concealing property is reduced. Preferably it is 0.01 to 12.0 parts by weight, more preferably 0.01 to 10.0 parts by weight. The pigment concentration (PWC) in the paint of the flaky graphite pigment is 3.0% or less. If it exceeds the upper limit, the coating film is colored by the flaky graphite pigment, and the hue is remarkably reduced. Preferably, it is 0.01% to 2.0%, and more preferably, 0.01% to 1.0%.

As other glittering pigments that can be used in combination, colored aluminum powder, bronze powder, alumina powder, stainless steel powder, titanium powder, mica powder, interference mica powder, colored mica powder, and other colored and colored flat pigments are used. May be.
Further, an organic / inorganic color pigment or the like can be used in combination.

The color pigments include organic azo chelate pigments, insoluble azo pigments, condensed azo pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, dioxane pigments, quinacridone pigments, Inorganic pigments such as indolinone pigments and metal complex pigments include, for example, graphite, yellow iron oxide, red iron oxide, carbon black, and titanium dioxide. Further, as the extender pigment, calcium carbonate, barium sulfate, clay,
Talc or the like is used.

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

The thermosetting resin used in the metallic base paint is not particularly limited, but
A film-forming resin such as an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin, or a urethane resin can be used, and these are used in combination with a curing agent such as an amino resin and / or a blocked isocyanate resin. A combination of an acrylic resin and / or a polyester resin and a melamine resin is preferred from the viewpoint of pigment dispersibility or coating workability.

When the above-mentioned metallic base paint is used as an aqueous paint, it is specifically described in US Pat. Nos. 5,151,125 and 5,183,504 as a film-forming resin. Thermosetting film-forming resins can be used. In particular, a thermosetting film-forming resin obtained by combining an acrylic resin having an acrylamide group, a hydroxyl group and an acid group described in U.S. Pat. No. 5,183,504 with a melamine resin has a good finish and good appearance performance.

The metallic base paint used in the method for forming a metallic coating film of the present invention may contain a viscosity controlling agent. The viscosity controlling agent is used for favorably forming a coating film without unevenness and sagging, and generally, those exhibiting thixotropic properties can be used.

Examples of such a dispersion include swelling dispersions of fatty acid amides, amides such as amide fatty acids and phosphates of long-chain polyaminoamides, and polyethylenes such as colloidal swelling dispersions of polyethylene oxide. , Organic acid smetite clay, organic bentonite type such as montmorillonite, aluminum silicate, inorganic pigments such as barium sulfate, flat pigments that exhibit viscosity depending on the shape of the pigment, non-crosslinking utilizing the interaction of polar groups or Crosslinkable resins or particles can be mentioned as viscosity control agents.

However, those which do not affect gloss and color development when formed into a coating film are preferred, and non-crosslinked or crosslinked resins or particles utilizing the interaction of polar groups are particularly preferred. Can be.

Among the preferred crosslinkable resin particles,
Those which are insoluble in organic solvents and have an average particle size of 0.02 to 0.5 μm are preferred. If the average particle size exceeds the upper limit, the stability will decrease. The above-mentioned crosslinkable resin particles include a resin having an emulsifying ability such as an alkyd resin or a polyester resin synthesized with a monomer having a zwitterionic group in the molecule as one of the polyhydric alcohol components, and the presence of a polymerization initiator. Below, what is obtained by carrying out emulsion polymerization of an ethylenically unsaturated monomer in an aqueous medium is preferable.

The monomer having a zwitterionic group in the molecule includes -N (+)-R-COO (-) or -N (+)-
R-SO3 (-) (wherein R represents a C1-C6 linear or branched alkylene group), and those having two or more hydroxyl groups can be used. As such a monomer, a hydroxyl group-containing aminosulfonic acid-type zwitterionic compound is preferable from the viewpoint of resin synthesis. Specific examples include bishydroxyethyl taurine.

The resin having an emulsifying zwitterionic group in the molecule, synthesized using the above monomer, has an acid value of 30 to 150 mgKOH / g, preferably 40 to 150 mgKOH / g.
It is preferable to use a polyester resin having a KOH / g and a number average molecular weight of 500 to 5,000, preferably 700 to 3,000. If the upper limit is exceeded, the handling properties of the resin will decrease,
If it is below the lower limit, a resin having an emulsifying ability is desorbed when a coating film is formed, or the solvent resistance is reduced.

In the synthesis of the crosslinkable resin particles, it is preferable to include a monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule as the ethylenically unsaturated monomer to be emulsion-polymerized. Such a monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule is preferably contained in the range of 0.1 to 10% by weight of all the monomers. The amount is selected to provide sufficient crosslinking to dissolve the particulate polymer in the solvent.

The crosslinkable resin particles used in the metallic base paint used in the method for forming a metallic coating film of the present invention are:
Generally contained in emulsion resins, but does not contain low molecular emulsifiers or protective colloids that reduce the performance when formed into a coating, and has two or more radically polymerizable ethylenically unsaturated groups in the molecule Because it is crosslinked by copolymerizing the monomer, the water resistance of the coating film,
Excellent solvent resistance and gloss.

The amount of the viscosity control agent to be added is 0.01 to 15 parts by weight, preferably 0.1 to 15 parts by weight, based on 100 parts by weight of the resin solid content of the metallic base paint used in the method for forming a metallic coating film of the present invention. To 12 parts by weight, more preferably 0.2 to 9 parts by weight. If the addition amount of the viscosity controlling agent exceeds 15 parts by weight, the appearance is reduced, and
If the amount is less than the weight part, the effect of controlling the viscosity cannot be obtained, which may cause the layer to adapt or reverse.

In addition, the metallic base paint used in the method for forming a metallic coating film of the present invention may contain a curing catalyst, an ultraviolet absorber, an antioxidant, a surface preparation agent and the like.

The metallic solid content of the metallic base paint used in the method for forming a metallic coating film of the present invention is 20 to 7%.
0% by weight, preferably 30 to 50% by weight.
Exceeding the upper and lower limits lowers the paint stability. At the time of application, it is 10 to 60% by weight, preferably 20 to 5% by weight.
0% by weight. If the upper limit is exceeded, the viscosity is too high and the appearance of the coating film is reduced, and if it is lower than the lower limit, the viscosity is too low and poor appearance such as adaptability and unevenness occurs.

As the metallic base paint used in the method for forming a metallic coating film of the present invention, a solution type paint is preferably used, and if it is a solution type, an organic solvent type or an aqueous type (water-soluble, water-dispersible, emulsion) ) And non-aqueous dispersion type.

The method for producing each paint used in the method for forming a metallic coating film of the present invention, including those described below, is not particularly limited, and a compound such as a pigment is kneaded and dispersed using a kneader or a roll. All methods known to those skilled in the art can be used.

Clear Paint The clear paint used in the method for forming a metallic coating film of the present invention contains a film-forming thermosetting resin, a curing agent and the like. The thermosetting resin capable of forming a film is not particularly limited, and a film-forming resin such as an acrylic resin, a polyester resin, an epoxy resin, or a urethane resin can be used. Alternatively, it is used in combination with a curing agent such as a blocked isocyanate resin. Further, from the viewpoint of transparency or acid etching resistance, a combination of an acrylic resin and / or a polyester resin and an amino resin, or an acrylic resin and / or a polyester resin having a carboxylic acid group / epoxy group curing system may be used. .

The total solid content in the clear coating is 20
６０60% by weight, preferably 35-55% by weight. Further, the total solid content at the time of coating is 10 to 50% by weight, preferably 20 to 50% by weight.

The above-mentioned clear paint preferably contains a viscosity controlling agent since it is applied on a wet basis with the metallic base paint used in the metallic coating film forming method of the present invention. Examples of the viscosity control agent include those described above, and the amount added to the clear coating is 0.01 to 10 parts by weight based on 100 parts by weight of the resin solid content of the coating composition.
Parts by weight, preferably from 0.02 to 8 parts by weight, more preferably from 0.03 to 6 parts by weight. When the amount of the viscosity controlling agent exceeds 10 parts by weight, the appearance is deteriorated,
If the amount is less than 0.1 parts by weight, the effect of controlling the viscosity cannot be obtained, which may cause infiltration or inversion between layers.

The coating form of the clear coating used in the method for forming a metallic coating film of the present invention may be any of an organic solvent type, an aqueous type (water-soluble, water-dispersible, emulsion), a non-aqueous dispersion type, and a powder type. If necessary, a curing catalyst, a surface preparation agent and the like can be used.

Substrate The method for forming a metallic coating film of the present invention can be performed by any substrate,
For example, it can be advantageously used for coating metals, glass, plastics, foams and the like, especially for metal surfaces and castings, but it can be particularly preferably used for metal products which can be subjected to cationic electrodeposition coating.

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 for these metals to be subjected to a chemical conversion treatment with a phosphate, a chromate, or the like in view of rust prevention.

Undercoating As the electrodeposition paint for forming an undercoat layer applied on the chemical conversion-treated substrate used in the method for forming a metallic coating film of the present invention, cationic and anion type electrodeposition paints can be used. The cationic electrodeposition coating gives a laminated coating excellent in corrosion resistance.

Intermediate paint The intermediate paint used in the method for forming a metallic coating film of the present invention conceals underlying defects, ensures surface smoothness after coating the metallic coating film (improves appearance), and provides physical properties of the coating film. (Impact resistance, chipping resistance, etc.)
Various organic and inorganic color pigments, extenders, thermosetting film-forming resins, curing agents and the like are included.

As the color pigment for the intermediate coating, for example, an organic azo chelate pigment, an insoluble azo pigment,
Condensed azo pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, dioxane pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments, and the like. Examples include iron, red iron, carbon black, and titanium dioxide. As the extender, calcium carbonate, barium sulfate, clay, talc and the like are used. Further, flat pigments such as aluminum powder and mica powder may be added. As a standard, a gray intermediate paint containing carbon black and titanium dioxide as main pigments is used. Further, a so-called color intermediate coating which is a combination of set gray and various color pigments may be used.

The thermosetting film-forming resin of the intermediate coating composition is not particularly limited, and may be an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin,
A film-forming resin such as a urethane resin can be used, and these are used in combination with a curing agent such as an amino resin and / or a blocked isocyanate resin. A combination of an alkyd resin and / or a polyester resin and an amino resin is preferred from the viewpoint of pigment dispersibility or workability.

After coating on the undercoated base material, it can be formed as a cured or uncured intermediate coating film. When cured, the curing temperature is 100 to 180 ° C., preferably 120 to 160 ° C. A cured coating film with a high degree of crosslinking is 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. Although the curing time varies depending on the curing temperature, curing at 120 ° C. to 160 ° C. for 10 to 30 minutes is appropriate.

Method for Forming Metallic Coating Film The method for forming a metallic coating film of the present invention is to apply the above-mentioned metallic base paint to an undercoated and, if necessary, an intermediately coated base material, and to form a clear-on-wet coating on the coated film. Apply paint.

That is, the above-mentioned metallic base paint is diluted with water or thinner as necessary to a viscosity suitable for painting, and then applied onto the above-mentioned substrate, and then a clear coating film is formed without baking it. This is done by applying a clear paint for the coating and then baking.

The thickness of the metallic base coating varies depending on the desired application, but in most cases, it is useful to have a thickness of 5 to 35 μm, and more preferably about 7 to 20 μm. If the upper limit is exceeded, the sharpness may deteriorate, or problems such as unevenness or flow may occur at the time of coating. If the lower limit is not reached, the base material cannot be concealed and the film is cut. In order to suppress unevenness of the glittering material, it is more preferable to apply the paint in two stages than in one stage.

When the metallic base paint is applied to an automobile body, it is preferably applied by a coating method such as air spray, air atomization type electrostatic coating, and rotary atomization type electrostatic coating.

When the above-mentioned metallic base paint is used as a water-based paint, the metallic base paint is heated at 60 to 100 ° C. for 2 to 10 minutes before applying the clear paint in order to obtain a good finished paint. It is desirable to keep.

The above clear paint is preferably applied on an uncured metallic base coating film by a method such as electrostatic coating or air spraying. The dry film thickness of the formed coating film is generally about 10 to 60 μm. And more preferably about 20 to 50 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 clear coating film itself is about 100-180.
Although it can be heated and cured at a temperature of ° C., in the present invention, by forming a laminated coating film in combination with the metallic base coating film and simultaneously heating and curing, it is possible to exhibit excellent appearance and coating film performance. .

The thickness of the metallic coating film containing the metallic base coating film and the clear coating film is from 30 to
It is 300 μm, preferably 50 to 250 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.

[0054]

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 Preparation of Crosslinkable Resin Particles In a reaction vessel equipped with a stirring and heating device, a thermometer, a nitrogen inlet tube, a cooling tube and a decanter, 213 parts of bishydroxyethyl taurine, 208 parts of neopentyl glycol, 296 parts of phthalic anhydride were added. , 376 parts of azelaic acid and 30 parts of xylene were charged and heated. Water generated by the reaction was removed by azeotropic distillation with xylene. The temperature of the reaction solution was set at 210 ° C. over about 3 hours from the start of reflux, and stirring and dehydration were continued until the acid value equivalent to carboxylic acid reached 135 mgKOH / g (solid content).

After cooling the liquid temperature to 140 ° C., 500 parts of “Kajura E10 (trade name; glycidyl ester of versatic acid manufactured by Shell)” was dropped in 30 minutes, and then stirring was continued for about 2 hours. The reaction was completed. An amphoteric ionic group-containing polyester resin having an acid value of 55 mgKOH / g, a hydroxyl value of 91 mgKOH / g and a number average molecular weight of 1250 was obtained.

The amphoteric ion-containing polyester resin 10
Parts, 140 parts of deionized water, dimethylethanolamine 1
Parts, 50 parts of styrene and 50 parts of ethylene glycol dimethacrylate were vigorously stirred in a stainless steel beaker to prepare a monomer suspension. Also, an aqueous initiator solution was prepared by mixing 0.5 parts of azobiscyanovaleric acid, 40 parts of deionized water and 0.32 parts of dimethylethanolamine.

A reaction vessel equipped with a stirring and heating device, a thermometer, a nitrogen inlet tube and a cooling tube was charged with 5 parts of the amphoteric group-containing polyester resin, 280 parts of deionized water, and 0.5 part of dimethylethanolamine. The temperature rose.
Here, 251 parts of the monomer suspension and 40.
82 parts were simultaneously added dropwise over 60 minutes, and the reaction was further continued for 60 minutes, and then the reaction was terminated.

A crosslinkable resin particle emulsion having a particle diameter of 55 nm measured by a dynamic light scattering method was obtained. Xylene was added to this crosslinkable resin particle emulsion, water was removed by azeotropic distillation under reduced pressure, and the medium was replaced with xylene to obtain a xylene solution of crosslinkable resin particles having a solid content of 20% by weight.

Example 1 Preparation of Metallic Base Paint A metallic base paint (PWC of aluminum pigment = 7%) was prepared with the following composition as a paint used for forming a metallic base coating film. Alpaste 91-0562 7.0 parts (Toyo Aluminum Co., Ltd. aluminum pigment, solid content 72%, average particle size 16 μm) GRAPHItan 7525 0.7 parts (Ciba Geigy Co., Ltd. graphite pigment, average particle size 8 μm) Thermosetting acrylic Resin 130.2 parts (Nippon Paint Co., Ltd., hydroxyl value 45, acid value 15, number average molecular weight 21000, solid content 50%) Uban 20N60 46.5 parts (Mitsui Toatsu Butylated melamine resin, solid content 60% 12. ) Acrylic surface conditioner 0.2 part Crosslinked resin particles of the above production example 14.0 parts (Nippon Paint Co., Ltd. structural viscosity imparting agent, solid content: 20%) n-butanol 4.0 parts Xylol 19.5 parts toluene 12. 8 copies 234.9 copies in total

Method of forming metallic coating : 0.8 mm thick, zinc phosphate treated, 30 cm long × 40 cm wide
Cation electrodeposition paint "Power Top U-5"
0 (manufactured by Nippon Paint Co., Ltd., cationic electrodeposition paint) "was electrodeposited such that the dry film thickness became 20 μm, and baked at 160 ° C. for 30 minutes. Next, on the obtained electrodeposition coating film, a gray intermediate coating material “Olga P-2 Gray (manufactured by Nippon Paint Co., Ltd., polyester / melamine resin-based gray coating material)” is dried to a thickness of 30 μm. After spray coating and setting for 10 minutes, baking was performed at 140 ° C. for 20 minutes to complete an undercoating film.

The metallic base paint previously diluted for 15 seconds (/ 20 ° C., # 4 FordCup) is coated on the surface of the obtained gray intermediate coating film so as to form a gradient coating having a dry film thickness of 0 to 40 μm. First, paint with air spray, then use the same paint as the whole, and apply 3.5kg / c air pressure.
Air electrostatic spray coating was carried out by "Auto REA" (Ransburg air electrostatic coating machine) at m2. After an interval of 5 minutes, “Super Rack O-150 Clear (Nippon Paint Co., Ltd. acrylic / melamine resin paint)” diluted in advance for 20 seconds (/ 20 ° C. # 4 FordCup) by wet-on-wet, Spray coating was performed so that the dry film thickness became 30 μm, and a baked coating film was formed at 140 ° C. for 20 minutes.

With respect to the obtained coating film, the concealment limit film thickness of the metallic coating film was evaluated and measured in the gradient coating portion. Also,
When the thickness of the metallic base coating film was about 20 μm, the hue and flip-flop property (F) were compared with those of the primary color reference plate formed using the metallic base coating material of Comparative Example 5.
/ F property) was visually evaluated. Further, the color difference (ΔE) from the primary color reference plate was measured using a gonio colorimeter GCMS-3 (manufactured by Minolta).

Further, with respect to the specular reflection angle for the incident light (45 degrees), the L * value (L
* (35 ° and L * ∠−5 °) were measured, and the measured values were substituted into the following equation to calculate the F / F value. The higher the F / F value, the better the flip-flop property, indicating that the difference in the appearance of the coating film depends on the viewing angle.

[0065]

(Equation 1)

Visual Evaluation After forming the laminated coating film, the appearance was visually determined according to the following criteria.

Flip-flop property (F / F property) 5: Excellent. 4: Excellent. 3: Normal 2: Slightly inferior. 1: considerably poor.

Hue 5 of the metallic coating: not colored at all compared to the primary colors. 4: Although slightly colored compared to the primary colors, there is no problem. 3: Slightly colored compared to the primary colors. 2: Feels slightly colored compared to the primary colors. 1: It is considerably colored compared to the primary colors.

Examples 2 to 4 and Comparative Examples 1 to 5 The metallic base paints of Examples 2 and 3 were prepared by changing the amount of the graphite pigment "Graphtan 7525" of Example 1 as shown in Table 1. . Example 4 is a graphite pigment that emits interference light coated with titanium and has an average particle size of 8 μm (Iriodin NEW T
G BLUE WII "was replaced with the graphite pigment of Example 1 to prepare a paint.

Comparative Examples 1 and 2 were prepared by using a small particle size aluminum pigment “Alpaste 7580NS” having an average particle size of 12 μm manufactured by Toyo Aluminum Co. instead of the flaky graphite pigment of Example 1. Comparative Examples 3 and 4 were prepared using a carbon black pigment “Degussa FW-200” manufactured by Degussa.
P "was prepared in place of the scaly graphite pigment of Example 1. However, Comparative Example 5 was prepared by removing the graphite pigment from Example 1 and was used to prepare a reference plate for hue evaluation.

Using the above coating material, a metallic coating film was prepared in the same manner as in Example 1, and evaluated in the same manner as in Example 1.

Table 1 shows the above evaluation results.

[0073]

[Table 1]

As is evident from the results in Table 1, the laminated coating films obtained using the metallic base coating materials of Examples 1 to 4 according to the present invention were obtained by using a coating film using a small particle size aluminum powder and a carbon black pigment. In comparison with the above, there is no colored feeling, indicating that it has become possible to achieve both excellent concealing power and flip-flop properties which have not been achieved in the past.

[0075]

The metallic coating obtained by the present invention has a high flip-flop property and a high concealing property, and does not cause a hue difference depending on the coated portion, so that it suffers from a problem caused by the undercoat being transparent. It was possible to provide a coating film having no color, and industrially, stable color development became possible.

According to the method for forming a metallic coating film of the present invention, it is possible to eliminate the difference in hue of the metallic coating film even on a bright and dark clear undercoating film in which a black paint for sash is applied on the middle coat, and Even in its own thin film portion, the color developability of the top coat can be sufficiently ensured, and the color can be made uniform throughout the coated object. Further, even when partial repair is performed, the laminated coating film formed by the present method can be repaired effectively.

Claims (2)

[Claims] 1. A two-coat, one-bake metallic coating in which a metallic base coating layer containing a brilliant pigment and a clear coating layer are wet-on-wet finished on an undercoated and optionally intermediate coated base material. In the method of forming, the metallic base paint used for forming the metallic base coating layer has an average particle diameter of about 3 to 10 μm and a thickness of 1 μm with respect to 100 parts by weight of the flaky aluminum pigment.
A method for forming a metallic coating film, comprising 0.01 to 15.0 parts by weight of the following flaky graphite pigment. 2. A laminated coating film formed by the method according to claim 1.