JP2001162220A - Method for applying pattern coating to outer panel of car body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern coating method for forming a pattern coating film of which the color is not influenced by the coating color of the topcoating film applied to the outer panel of a car body. SOLUTION: A method for applying pattern coating to the surface of the topcoating film applied to the outer panel of a car body has (1) a process for applying a white substrate paint, wherein the L* value in an L*a*b* color system of a concealing coating film is within a range of 70-85, to a place where a pattern must be formed by an automatic coating machine having a coating head equipped with an exclusive fine caliber nozzle to form a coating film of which the L* value is 65-85 and the value of [(a*)2+(b*)2]1/2 is 15 or less, (2) a process for drawing a pattern on the white substrate coating film by a pattern forming coating using the automatic coating machine to form a pattern coating film and (3) a process for applying a clear coating on the pattern coating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for painting a pattern of an outer panel of an automobile body.

[0002]

2. Description of the Related Art The demands of automobile users for paint colors of car body outer panels are diversifying year by year. Particularly, automobile users, mainly young people, have strong demands for unique colors, patterns and marking designs. There is a strong demand for RV vehicles (recreational vehicles). Also,
In commercial vehicles such as microbuses, there is an increasing demand for differentiation through pattern painting such as company logos and product images. In order to respond to these trends, it has become an important issue to expand the range of designability by pattern painting.

[0003] In some automobile users, an original seal or an emblem or the like is applied to the top coat of the outer panel of the automobile body, or partial painting or pattern painting is performed. Also, the weather resistance is inferior to the existing top coat, or the step between the seal or emblem and the existing top coat lowers the aesthetics,
Also, depending on the type of pattern, it is necessary to prepare many paint colors, but when there are not many paint colors, the color arrangement and design are limited, and originality is limited.

Japanese Patent Application Laid-open No.
JP-A-94527 discloses a method in which a paint for pattern formation is drawn directly on a coating film of an automobile outer panel by an automatic coating machine having a coating head equipped with a small-diameter nozzle, and then a clear paint is applied. Have been. However, in this method, although the weather resistance is improved by applying the clear paint, when the paint color of the outer body coating film of the automobile body is a high-color paint color or a low-light dark paint color, it is used for pattern formation. Because the thickness of the coating film formed by the paint is thin, the pattern coating film is transparent and greatly affected by the coating color of the outer coating film as the base, and the desired color pattern is obtained. Therefore, there is a problem that an automobile on which a pattern coating film can be formed is limited by a color of a coating film on an outer plate.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of applying a paint on a top coat of an automobile body outer panel to form a pattern paint film by applying the paint color of the automobile outer panel paint film. It is an object of the present invention to provide a method capable of forming a desired color pattern regardless of the coating color of an automobile outer panel coating, in which the color of the film is not substantially affected.

[0006]

Means for Solving the Problems As a result of diligent studies to achieve the above object, the present inventor has found that a white base material having a specific brightness is formed on a portion of a vehicle body outer plate where a pattern is to be formed. The above object can be achieved by applying a paint with an automatic coating machine having a special nozzle of a small diameter to form a base coat of a specific color, and forming a pattern coat on the coat with a pattern forming paint. The present invention has been completed based on the heading.

That is, the present invention relates to a method of applying a pattern on a surface of a top coat of an automobile body outer plate having a top coat formed thereon, and (1) to form a pattern on the surface of the top coat. Where the L ^* value in the L ^* a ^* b ^* color system of the concealment coating film is in the range of 70 to 85 by an automatic coating machine having a coating head equipped with a special nozzle having a small diameter. A step of applying a paint to form a coating film having an L ^* value of 65 to 85 and a value of [(a ^* ) ² + (b ^* ) ² ] ^1/2 of 15 or less; (2) the white color A step of drawing a paint for forming a pattern by an automatic coating machine having a coating head provided with a dedicated nozzle having a small diameter on the base base coating film to form a pattern coating film, and (3) on the pattern coating film And a step of applying a clear paint to the pattern.

[0008]

In DETAILED DESCRIPTION OF THE INVENTION The article to be coated present invention method, the automobile body external panel which top coating film is formed as a coating object, do this pattern painting.

The vehicle body skin may be each part (part) constituting a vehicle body skin of various automobiles such as a four-wheeled vehicle and a motorcycle, or may be a vehicle body skin obtained by combining the parts. There may be.

[0010] An automobile body outer panel as an object to be coated is usually formed with a top coat on a base material, usually with a primer coat and, if necessary, an intermediate coat. In particular, an automobile body outer panel having an overcoat film to be coated is formed on a metal substrate, a chemical conversion-treated metal substrate or a plastics substrate, with a primer coating film, an intermediate coating film and a top coating film. Are preferably formed sequentially.

The above-mentioned base material can be used without limitation as long as it is a base material that can be used for an automobile body outer panel. For example, metal base materials such as a steel plate, an aluminum plate, a galvanized steel plate, and an iron-zinc alloy-plated steel plate; Chemical conversion metal substrates obtained by subjecting the metal substrate to a chemical conversion treatment such as chromate treatment, zinc phosphate treatment, and iron phosphate treatment, and plastics substrates such as FRP.

The formation of a primer coating on the above-mentioned substrate can be carried out by applying an undercoat on the substrate by a known method such as spray coating, dip coating, brush coating, etc. Is a base material having conductivity such as a metal base material or a chemical conversion-treated metal base material, a primer coating is performed by electrodeposition coating using a known anion-type or cation-type electrodeposition coating as an undercoat. Preferably, a film is formed.

As the base resin component of the electrodeposition paint, for example, one or more of epoxy resin, acrylic resin, polybutadiene resin, alkyd resin, polyester resin, silicone resin and the like can be mentioned. In the anionic electrodeposition paint, the base resin component has an acid group such as a carboxyl group, and in the cationic electrodeposition paint, the base resin component has an amino group; an onium base such as an ammonium group, a sulfonium group, and a phosphonium group. It has a basic group, and can be made aqueous by neutralizing and ionizing these acid groups or basic groups. The electrodeposition paint is preferably a cationic electrodeposition paint from the viewpoint of corrosion resistance. Among them, a paint having a base resin component of a polyamine resin represented by, for example, an amine-added epoxy resin is preferable.

When the base material is a metal base material or a chemical conversion-treated metal base material, when an undercoating film is formed by a coating method other than electrodeposition coating, for example, by spray coating, a rust-preventive pigment is usually added. An undercoat paint is applied with an emphasis on corrosion protection. As the resin, an epoxy resin, a polyester resin, an alkyd resin, a vinyl resin, an acrylic resin, or the like is used.

When the base material is a plastics base material, plastics generally have poor adhesion of a coating film.
As the undercoat paint, a paint that can improve the adhesion of the intermediate coat film or the top coat film by being applied to the surface of plastics is used. Chlorinated polyolefins such as chlorinated polypropylene,
Polybutadiene, epoxy group-containing modified polybutadiene,
Examples thereof include a modified polybutadiene containing a carboxyl group, a polyurethane resin, and an acrylic resin.

The thickness of the undercoat film is usually 5 to 5
It is about 40 μm, preferably about 15 to 30 μm.

An intermediate coating or a top coating is applied on the undercoat. As the intermediate coating, a water-based coating, an organic solvent-based coating, may be any form of powder coating,
As the resin, various resin-based paints such as alkyd resin, polyester resin, acrylic resin, polyurethane resin, and vinyl resin can be used. Among them, alkyd resin systems are generally used.

A pigment is blended with the intermediate coating for the purpose of concealing the base material. The curing of the intermediate coating film can be usually performed by baking. The thickness of the intermediate coating film is usually 15 to 50 μm, preferably 20 to 40 μm in dry film thickness.
m.

An overcoat is formed on the undercoat or intermediate coat. As a method for forming the top coat, a coating method known in the field of automobile coating, for example, (A) a method of forming a colored enamel by baking, (B) a two-coat, one-bake method of a colored base coat / clear top coat Or a method of forming by a two-coat two-bake method, (C)
A method of forming a colored base coat / clear top coat / clear top coat by a three-coat one-bake method or a three-coat two-bake method can be applied.

The thickness of the colored enamel (A) is usually
The dry film thickness is in the range of about 20 to 60 μm. The thickness of the colored base coat in the above (B) or (C) is
Usually, the dry film thickness is in the range of about 10 to 30 μm, and the thickness of the clear top coat is usually 20 to 8 in terms of the dry film thickness.
The range is 0 μm.

As the above topcoat paint, any paint which can be used as a topcoat paint in the field of automotive coating can be used without particular limitation. Examples of the resin system of the overcoat paint include acrylic resin / amino resin (melamine resin and the like, the same applies hereinafter), alkyd resin / amino resin, polyester resin / amino resin, acrylic resin / polyisocyanate, alkyd resin / poly Isocyanate type, polyester resin / polyisocyanate type, high acid value acrylic resin / epoxy compound type, high acid value polyester resin / epoxy compound type, epoxy group-containing acrylic resin / polycarboxylic acid compound (or acid anhydride compound) type, etc. Can be mentioned. The form of the top coat is not particularly limited, and any form such as an organic solvent type, a non-aqueous dispersion type, an aqueous solution type, an aqueous dispersion type, a high solid content type, and a powder type can be used.

Pattern coating process step (1) In the pattern coating method of the present invention, first, in step (1), a part of a top coat film surface of an automobile body outer plate, where a pattern is to be formed, is formed. , As a base for pattern painting,
L ^* value of L ^* a ^* b ^* color system of the concealed coating film is 70 to 85.
Is applied with a white base paint having a specific lightness within the range.
Here, the portion where the pattern which is a part of the overcoat film is to be formed means the same shape as the shape of the pattern formed in the step (2) or a shape slightly larger than the shape. For example, when a star-shaped pattern is formed in the step (2), the star-shaped pattern is formed so as to have the same shape as the star-shaped or substantially similar to the star-shaped and slightly larger star-shaped. Is coated with a white base paint so as to have a star shape larger than the outline of, for example, about 0 to 2 mm, preferably about 0 to 1 mm.

The white base paint has an L ^* value of 70 to 85 as a lightness in an L ^* a ^* b ^* color system specified in JIS Z 8729-1994 of a concealed coating film using the white base paint. Must be in range. The concealing coating film means a coating film in which the influence of the top coating film of the outer plate of the automobile body as the base is removed by thick coating or the like. When the L ^* value is smaller than 70, it is difficult to form a base coating film having an L ^* value of 65 to 85 in step (1), while when the L ^* value is larger than 85, the base coating film is concealed. And the effect of the coating color of the overcoat film on the outer panel of the vehicle body is reduced, and [(a
^* ) ² + (b ^* ) ² ] ^1/2 is not more than 15 because it is difficult to form the coating film having a value of 15 or less.

L ^* a ^* b of the concealed coating film of the white base paint
^* The L ^* value of 70 to 85 in the color system can be easily achieved by appropriately adjusting the type and the mixing ratio of the coloring pigment to be mixed in the paint. Further, the white base paint having this L ^* value can be suitably obtained, for example, by adjusting a L ^* value by mixing a black paint with a white paint which is a paint for forming a pattern.

The viscosity of the white base paint is usually
10 to 30 mPa · s, preferably 15 to 25 mPa · s
s is preferable from the viewpoint of coating suitability,
The thickness of the cured coating film is generally in the range of about 1 to 10 μm, preferably 2 to 5 μm, and more preferably 3 to 4 μm. Here, if the thickness of the white base coating film is larger than 10 μm, the coating color of the top coating film on the outer body of the automobile body is hardly affected, but the coating is easily dripped or the amount of the coating used is increased. Also, if the paint film has a high pigment concentration and the coating film is too thick, the physical properties of the coating film tend to deteriorate, which is not preferable.

[0026] In the present invention, the coating film formed by the white base ^{paint, L * a * b * L} * values in color system is and at ^{65~85 [(a *) 2 +} (b *) ² ] It is necessary to use a specific color having a value of ^1/2 (hereinafter sometimes abbreviated as “MS value”) of 15 or less. This L ^* value is 70 ~
It is preferably 83, and the MS value is preferably 5-12.

When the L ^* value is less than 65, the brightness of the white base coating film is low, and the pattern coating film to be applied thereon becomes dark and turbid, while when the L ^* value is larger than 85, the white base coating material is low. The concealability of the coating film itself becomes smaller,
Both are not preferred because they are easily affected by the coating color of the overcoat formed on the vehicle body, and the color of the pattern coating is easily changed by the coating color of the overcoat. Also,
When the MS value of the white base paint film exceeds 15, the color of the pattern paint film to be applied thereon is greatly influenced by the hue of the white base paint film, and the color of the target pattern paint film is obtained. It becomes difficult.

The white base paint may be an organic solvent-based paint or a water-based paint. Among them, a water-based paint which has no problem of air pollution due to volatilization of the organic solvent is preferable.

As the water-based paint, a water-based paint containing as a main component a resin component containing a neutralized product of an acrylic copolymer (A) containing an alkoxysilyl group and a carboxyl group and a coloring pigment is preferable. . The resin component may further contain a neutralized product of the carboxyl group-containing acrylic copolymer (B) in addition to the neutralized product of the acrylic copolymer (A). Each component is described below.

The acrylic copolymer (A) (hereinafter sometimes abbreviated as “copolymer (A)”) contains an alkoxysilyl group and a carboxyl group in the copolymer. The alkoxysilyl group acts as a crosslinkable functional group of the copolymer, and improves the adhesion to an object to be coated, interlayer adhesion, water resistance, and the like. Necessary for aqueous conversion.

The copolymer (A) can be obtained by copolymerizing an alkoxysilyl group-containing polymerizable unsaturated monomer, a carboxyl group-containing polymerizable unsaturated monomer, and other monomers copolymerizable with these monomers. it can.

Representative examples of the above-mentioned alkoxysilyl group-containing polymerizable unsaturated monomer include, for example, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane,
γ- (meth) acryloyloxypropyltripropoxysilane, γ- (meth) acryloyloxypropyltri-n-butoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, γ- (meth) acryloyloxypropylmethyldi-n- Butoxysilane and the like can be mentioned. These monomers can be used alone or in combination of two or more.

Specific examples of the carboxyl group-containing polymerizable unsaturated monomer include acrylic acid, methacrylic acid, itaconic acid, itaconic anhydride, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid and the like. Can be mentioned. The carboxylic acid monomer is one kind,
Alternatively, two or more kinds can be used in combination.

The other monomer used in the production of the copolymer (A) is a polymerizable unsaturated monomer copolymerizable with the alkoxysilyl group-containing polymerizable unsaturated monomer or the carboxyl group-containing polymerizable unsaturated monomer. Any monomer can be used without particular limitation. Specific examples thereof include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
Alkyl or methacrylic acid alkyl or cycloalkyl esters of acrylic acid or methacrylic acid such as hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate and cyclohexyl (meth) acrylate; 2-hydroxyethyl (Meth) acrylate, hydroxypropyl (meth) acrylate,
Hydroxy group-containing polymerizable unsaturated monomers such as hydroxybutyl (meth) acrylate; and styrene, α-methylstyrene, vinyltoluene, (meth) acrylonitrile, and the like. These other monomers can be used alone or in combination of two or more.

The amount of the alkoxysilyl group in the copolymer (A) depends on the reactivity at the time of curing, the adhesion of the obtained coating film, the effect of lowering the viscosity of the coating, and the storage stability of the copolymer (A) before being made water-soluble. From the viewpoint of properties and the like, it is preferably in the range of about 0.03 to 2.0 equivalents / kg, and more preferably in the range of about 0.03 to 0.8 equivalents / kg, per 1 kg of the solid content of the copolymer (A). Is more preferable. The amount of the carboxyl group in the copolymer (A) is such that the acid value of the copolymer (A) is from 20 to 15 in view of the stability of the obtained water-based paint, the water resistance of the coating film and the like.
The amount is preferably in the range of 0 mgKOH / g, and more preferably in the range of 30 to 120 mgKOH / g.

The copolymer (A) does not necessarily have to have a hydroxyl group, but the hydroxyl group reacts with the alkoxysilyl group at the time of curing to contribute to the curing reaction, and the amount of the hydroxyl group in the copolymer (A) Is usually such that the hydroxyl value of the copolymer (A) is in the range of 10 to 150 mgKOH / g, more preferably 20 to 100 mgKOH / g.

The molecular weight of the copolymer (A) is preferably about 3,000 to 200,000 in weight average molecular weight (about 1,000 to 60,000 in number average molecular weight). More preferably, it is in the range of 10,000 to 100,000.

The copolymer (A) may be a single type or a mixture of two or more types.

The carboxyl group-containing acrylic copolymer (B) (hereinafter, may be abbreviated as “copolymer (B)”) comprises the carboxyl group-containing monomer used for producing the copolymer (A) and It is obtained by copolymerizing other monomers.

The amount of the carboxyl group in the copolymer (B) should be such that the acid value is in the range of 20 to 150 mgKOH / g from the viewpoint of the stability of the obtained water-based paint and the water resistance of the coating film. Is preferably 30 to 120 mgKOH / g
It is more preferable that the amount falls within the range described above.

The copolymer (B) does not necessarily have to have a hydroxyl group, but the hydroxyl group reacts with the alkoxysilyl group in the copolymer (A) at the time of curing and contributes to the curing reaction. The hydroxyl value of the combination (B) is 10 to 150 mg.
KOH / g is preferably in the range of 20 to 100.
More preferably, it is in the range of mgKOH / g.

The molecular weight of the copolymer (B) is usually preferably about 3,000 to 200,000 in weight average molecular weight (about 1,000 to 60,000 in number average molecular weight). About 10,000-100,0 in molecular weight
More preferably, it is within the range of 00.

The copolymer (B) may be a single type or a mixture of two or more types.

By using the acrylic copolymer (B) as a resin component when dispersing the pigment, a coating composition having excellent pigment dispersibility and storage stability can be obtained.

The water-based coating material suitable as a white base coating material contains a resin component containing a neutralized product of the copolymer (A) and a coloring pigment as main components. It may contain a neutralized product of the copolymer (B) in addition to the neutralized product of the polymer (A).

The neutralization of the copolymer (A) and the copolymer (B) is carried out by converting a carboxyl group in these copolymers into a basic substance which is a neutralizing agent, for example, amine, ammonia, alkali metal hydroxide. It can be performed by neutralizing with a substance or the like. By this neutralization, the copolymer (A) is dissolved in an aqueous medium.
And the copolymer (B) are dissolved or dispersed.

In the above water-based paint, the blending ratio of the copolymer (A) and the copolymer (B) is about 10/90 to 100/0 in terms of the solid content weight ratio of (A) / (B). Is preferably, and more preferably in the range of 10/90 to 90/10.

The coloring pigments to be mixed in the water-based paint include, for example, titanium white, zinc white, antimony white,
It mainly contains white pigments such as lead white and monobasic lead sulfate, and may contain trace amounts of other coloring pigments such as carbon black and chromatic pigments as necessary. The compounding amount of the color pigment is 100 parts of the resin component containing the neutralized product of the copolymer (A).
It is usually appropriate to set the amount to about 50 to 250 parts by weight with respect to parts by weight.

The water-based coating composition contains a neutralized product of the copolymer (A) or a resin component containing the neutralized product of the copolymer (A) and the copolymer (B), a coloring pigment, and water. An organic solvent is inevitably included as a solvent or the like at the time of polymer synthesis or for adjusting viscosity. In addition, this water-based paint, if necessary, a crosslinking agent, a pigment dispersant, a surface conditioner, a surfactant, an antifoaming agent, a fluidity regulator, an ultraviolet absorber, a light stabilizer,
A curing catalyst, a transparent pigment, an extender and the like can be appropriately contained. Examples of the crosslinking agent include butyl etherified melamine resin, methyl etherified melamine resin, methyl-butyl mixed etherified melamine resin, amino resin such as urea resin, and blocked polyisocyanate compound. Examples of the transparent pigment include a transparent iron oxide pigment and the like, and examples of the extender include fine particles of zinc white and barium sulfate.

The white base paint can be suitably applied on the surface of the top coat of the outer panel of an automobile body by an automatic coating machine having a coating head equipped with a special nozzle having a small diameter.

The automatic coating machine used in the method of the present invention is controlled by a computer, and the coating head provided with a special nozzle is controlled by a computer so that the coating head, which is a short distance from a three-dimensional object, is usually 2 mm or less, according to position data. ~ 5
This is a coating machine that moves in a two-dimensional or three-dimensional space separated by about a centimeter, and discharges paint from a dedicated nozzle in conjunction with it. It can form a coating film by applying paint as needed as needed. it can. As this coating machine, for example, "Michelangelo" (trade name, manufactured by LAC Co., Ltd.)
And the like.

There are two types of paint atomization types in the automatic coating machine: an air spray type using a micro two-fluid nozzle having a mechanism for suppressing spray diffusion and an airless type using a single-hole nozzle. It can be used properly depending on the size of the area. In general, a single-hole nozzle is used to make the boundary line clear or a fine pattern is drawn, and a very small two-fluid nozzle is used to blur or paint a large area. In each case, the paint is discharged only to a necessary portion by an on-demand type spray ON / OFF (on / off) mechanism. The diameter of the micro-aperture nozzle is usually 20 μm to 0.8 mm, preferably 0.1 mm to 0.4 mm for a single-hole nozzle, and 0.1 μm for a micro two-fluid nozzle.
Suitably, it is in the range of 2 mm to 0.5 mm.

Since it is necessary to apply the entire area of the portion where the pattern is to be formed, it is preferable to use a micro two-fluid nozzle from the viewpoint of shortening the coating time. The outer surface of the portion where the pattern is to be formed is painted using a single-hole nozzle or a very small two-fluid nozzle with a particularly small nozzle diameter, and the inside is a very small two-fluid nozzle with a larger diameter than the nozzle diameter used for painting the outer surface. Can also be used for painting. Hereinafter, a coating method using an automatic coating machine having a coating head provided with a special nozzle having a small diameter may be abbreviated as a “micro nozzle coating method”.

The white base coating film applied in the step (1) is dried by touch, semi-cured or heat-cured.
The paint for forming a pattern in the step (2) can be drawn.
In particular, it is preferable from the viewpoint of energy saving to paint the pattern forming paint in the touch-dried or semi-cured state of the coating film in the step (1) from the viewpoint of energy saving. A method by hot air spraying or the like can be used.

In the method of the present invention, the coating color of the top coating film of the outer panel of the automobile body may be any color, and the base color of the pattern forming portion can be improved by forming the white base coating film. It can be uniformized in a range where a pattern can be formed. The effect of the method of the present invention is remarkably exhibited particularly when the coating color of the overcoat film, which has not been able to form a good pattern conventionally, is a high-color coating color or a low-lightness dark color.

Step (2) In the step (2) of the method of the present invention, a pattern-forming paint is applied on the white base paint film of a specific color formed in the step (1) by a fine nozzle coating method. draw. At this time, it is preferable that the range to be drawn is usually the same as the range of the outline of the white base coating film, or a range narrower than the outline by, for example, about 2 mm or less, particularly about 1 mm or less.

When forming a pattern, a predetermined pattern having a shape and a paint color to be painted is set in a computer in advance. When setting a pattern, a pattern having a shape and a paint color registered in the computer is set. May be selected as desired by the user, or the pattern may be set by causing the computer to read a pattern created by the user.

The type of the pattern forming paint is not particularly limited, but at least three primary color paints of red, blue and yellow are used as basic color paints, and if necessary, black paint and
It is preferable to use at least one paint selected from paints of colors other than the three primary colors such as white, or paints of mixed colors, and paints containing glitter pigments. Each of these paints can be drawn and ejected from a dedicated nozzle of each minute diameter provided in the coating head. Therefore, dedicated nozzles for the number of paints to be used are required. These paints for pattern formation are drawn by a micro-nozzle coating method in accordance with instructions from a computer, and if necessary, a desired color is obtained by successively coating the paints, and a desired shape is applied to form a pattern paint film. .

There are no particular restrictions on the resin for the three primary color paints, paints of colors or mixed colors other than the three primary colors, and paints containing glitter pigments, which are pattern forming paints, and are not particularly limited, and include acrylic resin, alkyd resin, polyester resin, and the like. The paint may be thermosetting, lacquer-curable, or oxidative-curable. The paint for forming a pattern may be an organic solvent-based paint or a water-based paint, but among them, a water-based paint that does not have a problem of air pollution due to volatilization of the organic solvent is preferable.

As in the case of the white base paint, the water-based paint mainly comprises a resin component containing a neutralized product of an acrylic copolymer (A) containing an alkoxysilyl group and a carboxyl group, and a coloring pigment. A water-based paint contained as a component is preferred. The resin component may further contain a neutralized product of the carboxyl group-containing acrylic copolymer (B) in addition to the neutralized product of the acrylic copolymer (A).

The components of the neutralized product of the acrylic copolymer (A) containing an alkoxysilyl group and a carboxyl group and the neutralized product of the carboxyl group-containing acrylic copolymer (B) are the same as those of the white base. Same as paint.

The viscosity of the pattern forming paint is usually
10 to 30 mPa · s, preferably 15 to 25 mPa · s
s is preferable from the viewpoint of coating suitability,
The film thickness of the cured coating film is usually in the range of about 1 to 10 μm, preferably 2 to 5 μm.
Here, when the thickness of the paint film for forming a pattern is larger than 10 μm, the paint is easily dripped, the amount of the paint used is large, and the paint concentration is high, so that when the paint film is thick, the physical properties of the paint film are increased. This is not preferable because it causes a problem that the temperature tends to decrease.

As the coloring pigment, various pigments are selectively used according to the color of the paint. For example, the three primary colors of paint are as pure red, pure blue, and pure yellow paint as possible, so that a wider range of paint colors can be produced. Since there is no paint, a paint in which pigments of colors close to these colors are dispersed is appropriately selected and used as a three primary color paint.

As red pigments for red paint, one of the three primary color paints, lake red 4R, carmine FB, dinitroaniline orange, pyrazolone orange, pyrazolone red, perinone orange, permanent red 2
B, Rake Red R, Bon Maroon Light, Bordeaux 1
0B, Bonmaroon Medium, Thioindigo Bordeaux, Bonmaroon L, Perylene Vermillion, Perylene Scarlet, Perylene Maroon, Benzimidazolone Orange, Chrome Vermillion Molybdenum Red, Bengala, Toluidine Red, γ-type Quinacridone Red, etc. Can be.

As blue pigments for blue paints, one of the three primary color paints, copper phthalocyanine blue (Pigment Blue 15, 15: 1, 15: 2, 15: 3, 1)
5: 4 etc.), metal-free cyanine blue, induslen blue, navy blue, ultramarine blue, cobalt blue and the like.

The yellow pigments for the yellow paint which is one of the three primary color paints, such as Lake Yellow 6G, Shimura Yellow 3056, Fast Yellow G, Fast Yellow 10G, Shimura Yellow 4119, Permanent Yellow FGL, Benzimidazolone, etc. Monoazo pigments: Disazo Yellow AMX, Disazo Yellow AAOT,
Disazo Yellow AAAA, Disazo Yellow AAA,
Permanent Yellow HR, Lionol Yellow FFR
Condensed azo pigments such as Chromophthal Yellow 3G, Chromophthal Yellow 6G and Chromophthal Yellow GR; Irgazine Yellow 3RLTN, Irgazin Yellow 2RTL, Irgazin Yellow 2GLT, Fastgen Super Yellow GROH, Fastgen Super Yellow Isoindolinone pigments such as GRO and Sandrin Yellow 6GL; anthrapyrimidine yellow,
Surlenic pigments such as flavantron yellow and acylamino yellow; green gold, palio yellow 1
070, Palio Tol Yellow 1770, Irgazine Yellow 5GT and the like; quinophthalone yellow;
Examples include isoindoline yellow, graphite, yellow iron oxide, and titanium yellow.

The above-mentioned red, blue, and
Examples of paints of colors other than the three primary yellow paints include, for example, black paints containing black pigments such as carbon black, pine smoke, graphite, and iron black; titanium white, zinc white, antimony white,
White paint containing white pigment such as lead white or monobasic lead sulfate as a pigment; chrome green, cobalt green, chromium oxide, cyanine green, brominated green, cobalt.
A green paint having a green pigment such as chrome green, titanium / nickel / cobalt / zinc green as a pigment; a purple paint having a purple pigment such as cobalt violet, manganese violet, dioxazine violet or β-quinacridone violet as a pigment; It can be paint of various colors. In addition, the mixed color paint may be a paint containing two or more pigments that can be used for the three primary color paints and the paints of the respective colors other than the three primary colors.

The glitter pigment of the glitter pigment-containing paint used as required includes aluminum powder, bronze powder, copper powder, stainless steel powder, nickel powder, titanium oxide-coated mica powder, iron oxide-coated mica powder, and the like. Can be used.

In each paint for forming a pattern, the pigment concentration is not particularly limited. However, since the opacity in a thin film (brightness in a paint containing a brilliant pigment) is required, the pigment content is generally high. Usually, the pigment is 20 to 10 in the three primary color paints with respect to 100 parts by weight of the resin component.
0 parts by weight, preferably in the range of 30 to 50 parts by weight,
In the paint containing the glitter pigment, the glitter pigment is 5 to 10%.
0 parts by weight, preferably in the range of 10 to 50 parts by weight,
In a black paint, the pigment is in a range of 5 to 50 parts by weight, preferably 10 to 20 parts by weight, and in a white paint, the pigment is 50 to 250 parts by weight, preferably 100 to 2 parts by weight.
In the green paint, the pigment is in the range of 20 to 100 parts by weight, preferably 30 to 50 parts by weight, and in the purple paint, the pigment is in the range of 20 to 100 parts by weight, preferably 30 to 50 parts by weight. Suitably, it is in the range of 50 parts by weight.

In the method of the present invention, the coating head of the automatic coating machine using the fine nozzle coating system usually has a red, blue,
Each of the nozzles has a dedicated nozzle for the three primary colors of yellow, and when a paint containing a brilliant pigment, a paint of a color other than the above-mentioned three primary colors, or a mixed color paint is used, a nozzle for these paints is further provided.

Although a considerable range of coating colors can be obtained with the three primary color paints, it is preferable to provide a nozzle for a black paint in addition to the three primary color paints. Can be greatly expanded. Further, by using a dedicated nozzle for a paint of a color other than the three primary colors and black or a mixed color, it is possible to widen the range of paint colors.

In the method of the present invention, in step (1) and step (2), the automatic coating machine may be the same or different, but the same and the same coating head can be used.
It is suitable in terms of equipment load, workability, and the like. In this case, it is appropriate to further provide a dedicated nozzle for a white base paint used in step (1) as a dedicated nozzle. Therefore, in step (1) and step (2), the coating head is a nozzle dedicated to red, blue, yellow, and black basic color paints and a white base paint, and if necessary, to a paint containing a brilliant pigment. It is preferred to use a common coating machine with a coating head with dedicated nozzles.

In the step (2), when the pattern-forming paint is drawn to form a pattern coating, the white base paint applied in the step (1) is dried by touch, semi-cured or heat-cured. After that, the paint for pattern formation can be drawn.

The paint film for pattern formation applied in the step (2) may be dried by touch, semi-cured or cured by heating, and then coated with the clear paint in the step (3). In particular, it is preferable from the viewpoint of energy saving to paint the pattern forming paint in the touch-dried or semi-cured state of the coating film in the step (2) from the viewpoint of energy saving. A method by hot air spraying or the like can be used.

In the method of the present invention, in the step (1) and the step (2), the white base paint or the pattern forming paint is sprayed onto the object from a short distance, usually about 2 to 5 cm. It has a great advantage that the landing efficiency is close to 100%, so that it is possible to greatly reduce the supply / exhaust facilities and the running cost required for the supply / exhaust. The coating time for forming the pattern varies depending on the type of the coating film and the coating area, but since an automatic coating machine (automatic coating robot) is used, continuous coating can be performed and productivity can be improved. However, since the number of times of coating varies depending on the desired color, the film thickness in a small area tends to be different, and since the flight distance of the coating particles is short, the viscosity of the coating coating is not increased and the coating is easily sagged, so that thick coating is difficult. Therefore, the film thickness of the pattern forming paint in the step (2) is usually 10 μm
Hereinafter, it is preferably a thin film of about 5 μm or less, and in order to conceal with a thin film, it is necessary to contain a large amount of pigment as described above. In the method of the present invention, as a step (3), a clear paint is applied on the patterned coating film as a step (3) since the weather resistance and the chemical resistance are apt to decrease.

Step (3) In the step (3), a clear paint is applied on the pattern coating film in the step (2). As a result, it is possible to prevent a decrease in the appearance of the coated surface and a decrease in the weather resistance.

As the clear paint, any clear paint having good weather resistance can be used without limitation, such as an organic solvent-based paint, an aqueous paint, and a powder paint. As a resin system,
Various resins such as an acrylic resin, a polyester resin, an alkyd resin, a silicone resin, and a fluorine resin can be used, and may be a thermosetting type, or may be cured by an actinic ray such as an ultraviolet ray or an electron beam. There may be. As the clear paint, those used as a top clear paint for automobiles are preferably used, and among them, an acrylic resin-based two-pack urethane clear paint is suitable. Further, the clear paint may contain an ultraviolet absorber for improving weather resistance.

The clear paint may be applied after the pattern paint is cured. However, when the clear paint is a room temperature curing type or a thermosetting type, the pattern paint is not applied after the pattern formation paint is applied. In the state of curing (including touch-drying and semi-curing), apply a clear paint on this, then forcibly dry or heat at a specified temperature to simultaneously bake the pattern coating and clear coating to cure This is preferred from the viewpoints of interlayer adhesion between the pattern coating film and the clear coating film, reduction in the amount of heating energy, and the like.
In addition, after sequentially applying a white base paint, a paint for forming a pattern, and a clear paint on the top coat of the automobile body,
It is also preferable to simultaneously heat and cure the three uncured coatings of the white base coating, the patterned coating, and the clear coating.

The clear coating is preferably applied by a coating method such as an air spray coating method, an electrostatic air spray coating method, or an electrostatic rotary atomization type coating method. Clear paint is
The coating may be performed only on a portion having a pattern, may be applied to the periphery of the pattern, or may be applied to the entire top coat. It is preferable that the thickness of the cured coating film is usually in the range of about 10 to 50 μm. The heating and curing conditions of the clear paint are usually from 60 to
10 minutes to 1 hour at about 160 ° C., preferably 80
At about 140 ° C. for about 20 to 40 minutes. On this occasion,
When the white base paint film and / or the pattern paint film are uncured, these films are also cured at the same time.

Thus, according to the coating method of the present invention, a pattern can be suitably applied to the outer panel of an automobile body.

[0081]

The present invention will now be described more specifically with reference to examples and comparative examples. % In each case is% by weight
Means

Example 1 A cationic electrodeposition coating material “ELECRON 9600” (trade name, product name) was applied to an automobile body made of a cold-rolled steel sheet having a thickness of 0.5 mm.
(Kansai Paint Co., Ltd.) is electrodeposited and baked to a thickness of about 2
An electrodeposition coating film of 2 μm was formed. A polyester resin-melamine resin-based intermediate coating “WS HS-27 Primer” (trade name, manufactured by Kansai Paint Co., Ltd.) is applied as an intermediate coating on the electrodeposition coating film by electrostatic spraying and baked to a thickness of approx. An intermediate coating film of 30 μm was formed. On this intermediate coating film, a top coating material “WS Amirac (DM13 RC) each coating color” (trade name, manufactured by Kansai Paint Co., Ltd., polyester resin-melamine resin system top coating material) is applied by electrostatic spraying and baked. An overcoat film having a thickness of about 30 μm was formed. The coating colors of the above top coat were five colors of black (black), yellow (yellow), blue (blue), green (green), and red (red). L ^* value of coating color of top coat, a
^* Value and b ^* value are shown in Table 1 below.

[0083]

[Table 1]

Next, specific patterns and characters are set in the computer in advance, and the three primary colors, red and red, are applied by an automatic coating machine [Michelangelo V7 (trade name) manufactured by LAC Co., Ltd.] which is controlled and operated by the computer. Acrylic resin paints of a total of five colors including blue, yellow paints and black paints, and white base paints with adjusted L ^* values, are provided with dedicated nozzles 5 for these paints.
Using a coating head with individual pieces, apply a white base paint to the place where pictures and characters are to be drawn on the overcoating film.
m to form a white base paint film,
Specific patterns and characters were drawn thereon using each basic color paint, and baked at 90 ° C. for 30 minutes. Here, after the white base paint was applied, it was air-dried for about 2 to 3 minutes, and then each basic color paint was applied.

In the above white base paint, the L ^* value of the concealed coating film was 80. Each of the acrylic resin paints of the above colors has an acid value of 78 mg KOH / g and a hydroxyl value of 97.
mgKOH / g, a methoxysilyl group content of 0.41 equivalent / kg, a carboxyl group having a weight average molecular weight of about 25,000, a hydroxyl group and a methoxysilyl group having a neutralized product of 75% by weight of an acrylic resin (A-1), Acid value 48mgKOH
/ G, a hydroxyl value of 43 mgKOH / g, a weight average molecular weight of about 30,000, a carboxyl group and a resin component consisting of 25% by weight of a neutralized product of a hydroxyl group-containing acrylic resin (B-1), and each of the coloring pigments mixed therein Water-based paint. The viscosity of each of these paints is 18 mP
a · s.

In the above coating, the coating head is
Use two types of nozzles, one with a dedicated single-hole nozzle (nozzle diameter 0.15 mm) and the other with a very small two-fluid nozzle (nozzle diameter 0.3 mm). Was about 3 cm.

Then, an organic solvent-dilutable acrylic urethane resin-based clear paint “Rethane PG60 Clear” (trade name, manufactured by Kansai Paint Co., Ltd.) was applied to the top coat, the white base coat, and the pattern and character. Painted with an electric rotary atomizing type coating machine and baked at 80 ° C for 30 minutes to obtain a film thickness of about 35μm
To form a clear coating film, a pattern and characters on the top coating film,
And a coated article having a clear coating film was prepared.

In the above five color paints, the pigment type in the red paint is γ-type quinacridone red, and the P / B ratio [weight ratio of the amount of the pigment to the resin solid content] is 0.4.
It is. The pigment type in the blue paint is cyanine blue, and the P / B ratio is 0.4. The pigment type in the yellow paint is Irgazine Yellow 2RLT, and the P / B ratio is 0.4. The pigment type in the black paint is carbon black, and the P / B ratio is 0.15. The white base paint is a paint obtained by adding 1 to 2% of the above-mentioned black paint to a white paint having a pigment type of titanium white and a P / B ratio of 2.0 to adjust the L ^* value.

Example 2 In Example 1, the mixing ratio of the black paint to the white paint was slightly increased as the white base paint (3 to 4).
%) Except that the coated article was prepared in the same manner as in Example 1. This white base paint has a L
^{* The} value was 75.

Comparative Example 1 A coated article was prepared in the same manner as in Example 1, except that a white paint whose L ^* value was not adjusted was used instead of the white base paint. In this white paint, the L ^* value of the concealed coating film was 95.

The coated articles obtained in Example 1, Example 2 and Comparative Example 1 were tested for pattern establishment of a white base paint film based on the following test method.

Test Method Pattern Establishability: L ^* value of a white base paint film when a white base paint is applied on top coat films of various paint colors, a
^* Value and b ^* value were measured, and the value (MS value) of [(a ^* ) ² + (b ^* ) ² ] ^1/2 was calculated. It is considered that the smaller the MS value, the higher the color stability. In addition, the visibility of the pattern and characters of each coated article was visually observed, and the pattern formation was evaluated according to the following criteria.

：: Practical as a pattern, Δ: Slightly affected by the background color, lacking in clearness of the pattern, ×: The effect of the background color is remarkable, and the pattern is difficult to understand.

The test results are shown in Table 2 below.

[0095]

[Table 2]

[0096]

According to the coating method of the present invention, the change in the color of the pattern coating film due to the coating color of the top coating film of the object to be coated is reduced by forming a white base coating film of a specific color. The pattern can be suitably formed by an automatic coating method having a good coating efficiency without adversely affecting the color of the pattern coating film by the coating color of the top coating film.

Therefore, a pattern coating film having a desired pattern can be efficiently and suitably formed regardless of the coating color of the top coating film of the automobile body. In addition, the presence of the clear coating film on the uppermost layer makes it possible to form a pattern coating film having excellent weather resistance and the like with good coating efficiency.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 143/04 C09D 143/04 201/00 201/00 (72) Inventor Masaaki Kobayashi Kanzakicho, Amagasaki City, Hyogo Prefecture 33-1 Kansai Paint Co., Ltd. (72) Inventor Hideo Sugai 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Kansai Paint Co., Ltd. (72) Inventor Fumiya Yoshida 1st Daihatsu-cho, Ikeda-shi, Osaka No. 1 Daihatsu Industry Co., Ltd. (72) Inventor Kazuyuki Kuwano 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. F-term (reference) 4D075 AA02 AA37 AE03 BB26Z BB73X CB13 DA06 DB02 DC12 EA06 EA43 EB22 EB42 EC11 4J038 CG141 CJ131 DB391 DD121 DD231 EA011 GA06 GA15 HA026 HA216 HA376 KA08 NA01 NA04 NA12 NA24 PA08 PA10 PA19 PB07 PC02 PC08

Claims (7)

[Claims] 1. A method for applying a pattern on a surface of a top coat of an automobile body outer plate having a top coat formed thereon, the method comprising: By an automatic coating machine having a coating head equipped with a special nozzle having a small diameter, a white base paint having an L ^* value of 70 to 85 in the L ^* a ^* b ^* color system of the concealment coating film is applied. The L ^* value is 65-85 and [(a ^* ) ² +
(B ^* ) ² ] a step of forming a coating film whose value of ^1/2 is 15 or less, (2) automatic coating having a coating head equipped with a special nozzle having a small diameter on the white base coating film coating film And (3) a step of applying a clear paint on the pattern coating film by drawing a paint for pattern formation with a machine. 2. The coating method according to claim 1, wherein the white base paint is a paint obtained by mixing a black paint with a white paint. 3. The coating method according to claim 1, wherein both the white base paint and the pattern forming paint are water-based paints. 4. The water-based paint according to claim 3, wherein each of said white base paint and said pattern-forming paint contains a neutralized acrylic resin having an alkoxysilyl group and a carboxyl group as a resin component. Painting method. 5. In the step (1) and the step (2), the coating head has a dedicated nozzle for a red, blue, yellow and black basic color paint and a white base paint, and if necessary, a brilliant pigment. The coating method according to any one of claims 1 to 4, wherein a common coating machine having a coating head provided with a dedicated nozzle for a coating material is used. 6. An automobile body outer plate on which a top coat as an object to be coated is formed, is provided with a primer coat, an intermediate coat and a primer coat on a metal substrate, a chemical conversion treated metal substrate or a plastics substrate. 6. An overcoat film is formed sequentially.
The coating method according to any one of the above. 7. A white base paint, a pattern forming paint, and a clear paint are sequentially applied on the top coat film surface, and then a white base paint film, a pattern paint film, and a clear paint film are applied. The coating method according to any one of claims 1 to 6, wherein the cured coating film is simultaneously cured by heating.