JP2002239457A - Method for applying water paint and coated material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for applying a water paint in which a wiping trace after wiping does not appear in the appearance of a multiple coating film even if the surface of a base material to be coated is wiped to remove the coating dust or outside soil on the base material to be coated at the time of forming the multiple coating film in a water paint coating system and to provide a coated material. SOLUTION: The method of applying the water paint to a base material comprises the steps of (1) wiping the coated base material on which the coating film is to be formed with an aqueous alcohol solution having a water/alcohol ratio of (1 to 2)/(99 to 80), (2) forming a coating film of the water paint on the base material, and (3) baking the coating film formed of the water paint to harden it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a water-based paint and a coated article coated by the method.

[0002]

2. Description of the Related Art In recent years, it has been proposed to use water-based paints from the viewpoint of environmental protection and to shorten the coating process from the viewpoints of resource saving and energy saving. For example, in the coating of an automobile body, a tipping primer is optionally applied to an electrodeposition coating film, and an intermediate coating film and a top coating film are further formed.

[0003] In forming a multi-layer coating film, in order to remove coating dust and external stains on the substrate on which the coating film has been formed, wiping of the coating substrate on which the coating film has been formed is performed. A step of performing From this point of view, for example,
No. 224533 discloses that after using a high-viscosity water-based paint, the water-based paint is applied a plurality of times at predetermined intervals in order not to degrade the appearance quality of the coated product.
It is described that pure water or a mixed solution with a solvent component of a water-based paint is applied to a painted surface at a predetermined interval and then heated and cured. However, in the prior art of the above publication, a mixed solution with pure water or a solvent component of an aqueous paint is applied to the painted surface by spraying or the like, but the technique of the above publication increases the surface roughness of the overcoated coating film. It is not a wiping method for removing paint dust and external stains on a substrate on which a coating film is formed. Also, even if pure water used in the above publication is used for wiping, traces of wiping after wiping appear on the appearance of the overcoated film, and when a solvent component of an aqueous paint is used, depending on the composition of the solvent, Is not sufficient to solve the problem that the trace of wiping after wiping appears on the appearance of the overcoated film as in the case of pure water.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an overcoated film in an aqueous coating system.
In order to remove paint dust and external stains on the coated substrate on which the coating has been formed, even when wiping the coated substrate surface on which the coating has been formed, cissing, unevenness, and worms after wiping It is an object of the present invention to provide a method of applying a water-based paint and a painted product in which traces of wiping do not appear in the appearance of the overcoated film.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, have reached the present invention. 1. The following steps (1) to-
(3) A method of applying a water-based paint sequentially through the steps. (1) a step of wiping the substrate on which the coating is formed with an aqueous alcohol solution having water / alcohol = 1 to 20/99 to 80; (2) a substrate having the coating formed thereon And (3) baking and curing the coating film formed from the water-based paint; The above-mentioned method for applying a water-based coating, wherein the coating formed on the substrate on which the coating is formed is any one of an electrodeposition coating, an intermediate coating and a top coating. 3. The method for coating an aqueous paint as described above, wherein the alcohol of the alcohol aqueous solution is isopropyl alcohol. 4. A painted product obtained by the above-mentioned method for applying a water-based paint.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.

Method for Coating Water-Based Paint The method for coating a water-based paint according to the present invention comprises: (1) water / alcohol = 1-20 / 99-
Wiping with an aqueous alcohol solution that is 80, (2)
A step of forming a coating film on the base material on which the coating film is formed with a water-based paint, and (3) a step of baking and curing the coating film formed with the water-based paint.

Step (1) Step (1) in the present invention is a step of wiping the coated substrate with an aqueous alcohol solution in which water / alcohol = 1 to 20/99 to 80.

The substrate to be coated is not limited to metals such as iron, aluminum, copper and alloys thereof; polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer resin. And resins such as polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin and epoxy resin, and various kinds of plastic materials such as FRP which are subjected to conductive treatment. Preferably, the coating film formed on the substrate on which the coating film is formed is any one of an electrodeposition coating film, an intermediate coating film, and a top coating film.

In the method for applying a water-based paint according to the present invention, when the coated material obtained by the method for applying a water-based paint according to the present invention on a substrate on which the coating film is formed is an automobile body and parts, It is preferable to apply a degreasing treatment or a chemical conversion treatment to the base material to be coated, further form an electrodeposition coating film with a cationic electrodeposition coating material, bake and cure, and form an intermediate coating film thereon with an intermediate coating material. . In addition, those on which an overcoat is formed can also be preferably used when recoating such as repairing the overcoat.

As the electrodeposition paint used for forming the above electrodeposition coating film, a cationic electrodeposition paint or an anion electrodeposition paint can be used. From the viewpoint of corrosion resistance, it is preferable to use a cationic electrodeposition paint. As the cationic electrodeposition paint, a modified epoxy resin into which an amino group has been introduced and a blocked isocyanate-curable amino-modified epoxy resin-based cationic electrodeposition paint using a blocked polyisocyanate curing agent are used. The electrodeposition conditions are preferably set so that a current is applied at 200 to 300 V for 90 to 300 seconds and the dry film thickness becomes 10 to 30 μm.

The intermediate coating used for forming the intermediate coating film is a vehicle commonly used for the intermediate coating.
It contains a pigment, a solvent and, if necessary, various additives. The formation of the intermediate coating film is performed by spray coating or roll coating.
Bake and dry at 20 ° C. for 20 to 30 minutes. The dry film thickness of the intermediate coating film is preferably from 10 to 100 μm. 10
If it is less than μm, it is difficult to conceal the underlayer, and if it exceeds 100 μm, the coating film appearance may be poor. More preferably 1
0 to 50 μm.

The top coat used to form the above-mentioned top coat is a vehicle commonly used as a top coat,
It contains a brilliant pigment and / or a coloring pigment, a solvent, and various additives as required. Further, it is preferable to form an overcoating top clear coating which is overcoated on the overcoating basecoat containing the glitter pigment and / or the coloring pigment. The formation of the top coat is performed by spray coating or roll coating.
Bake and dry at 20 ° C. for 20 to 30 minutes. The dry film thickness of the above top coat is preferably 10 to 50 μm. 10μ
If it is less than m, it is difficult to conceal the underlayer, and if it exceeds 50 μm, the coating film appearance may be poor. More preferably, 10
40 μm.

[0014] In forming the wipe- applied repetitive coating film, the surface of the substrate on which the coating film is formed is removed in order to remove coating dust and external stains on the substrate on which the coating film is formed. Although wiping is performed, in the present invention, an aqueous alcohol solution is used for the substrate on which the coating film is formed. By wiping using an alcohol aqueous solution, it is possible to form a high-appearance coating film without wiping traces after wiping appearing in the appearance of the overcoated coating film.

The alcohol in the aqueous alcohol solution is preferably methyl alcohol, ethyl alcohol, 1-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, isobutyl alcohol, 2-butyl alcohol, tert-butyl alcohol, 1-pentanol or 3 -Methyl-1-butyl alcohol and the like. More preferably, isopropyl alcohol is used because of its balance with water.

The mass mixing ratio of the alcohol aqueous solution is as follows:
Preferably, water / alcohol = 1-20 / 99-80. If the mass mixing ratio is less than 1/99 (the alcohol ratio is too large), repelling or wetting traces of the alcohol aqueous solution may occur. If it exceeds 20/80 (the alcohol ratio is too small), water remains. May cause abnormal appearance of the overcoated film. More preferably, 1 to 10
/ 99-90.

As a specific method of wiping, a method of wiping a dry coating film on a coating film forming surface with a water-based paint with a rag or the like soaked in the above-mentioned alcohol aqueous solution is performed. The time for wiping is preferably immediately before forming a coating film with the aqueous paint.

Step (2) Step (2) in the present invention is a step of forming a coating film on the substrate on which the coating film is formed, using an aqueous coating material.

The above-mentioned aqueous paint contains a solvent consisting of a vehicle and water and, if necessary, a bright pigment and / or a coloring pigment, an extender pigment and various additives. The acid value of the resin for forming a coating film used as a vehicle for the water-based paint is adjusted and neutralized with an amine or the like before use. The solvent is mainly water, but a hydrophilic organic solvent can be used in combination.

The vehicle comprises a resin for forming a coating film and, if necessary, a crosslinking agent. As the coating film forming resin,
(A) acrylic resin, (b) polyester resin, (c)
Alkyd resin, (d) fluororesin, (e) epoxy resin, (f) polyurethane resin, (g) polyether resin, etc., and these can be used alone or in combination of two or more, and are preferable. Is an acrylic resin or a polyester resin.

In the case of a type having curability, amino resins, (block) polyisocyanate compounds, amines, polyamides, imidazoles, imidazolines,
It is used by mixing with a crosslinking agent such as a polyvalent carboxylic acid, and the curing reaction can proceed at heating or at room temperature. Also,
It is also possible to use a lacquer type coating film forming resin having no curability and a curable type in combination.

When the vehicle contains a cross-linking agent, the ratio of the resin for forming a film to the cross-linking agent is 90 to 50% by mass and the content of the cross-linking agent is 10 to 50% by mass in terms of solid content. Preferably, the coating film forming resin is 85 to 60% by mass, and the crosslinking agent is 15 to 40% by mass. If the amount of the crosslinking agent is less than 10% by mass (the amount of the resin for forming a coating film exceeds 90% by mass), the crosslinking in the coating film is insufficient. On the other hand, if the crosslinking agent exceeds 50% by mass (the
), The storage stability of the coating material is reduced and the curing speed is increased, so that the appearance of the coating film is deteriorated.

As the pigment to be blended as required, a brilliant pigment and / or a coloring pigment, and if necessary, an extender pigment can be used. As the glitter pigment,
Preferably aluminum flake pigment, metal oxide coated aluminum flake pigment, metal oxide coated alumina flake pigment, metal oxide coated silica flake pigment, graphite pigment, interference mica pigment, colored mica pigment, metal titanium flake pigment, stainless steel flake pigment, Examples include plate-like iron oxide pigments, phthalocyanine flake pigments, metal-plated glass flake pigments, metal oxide-coated glass flake pigments, and hologram pigments. Further, as the coloring pigment, as an organic pigment, an azo lake pigment, an insoluble azo pigment, a condensed azo pigment, a phthalocyanine pigment, an indigo pigment, a perinone pigment, a perylene pigment, a phthalone pigment, a dioxazine pigment, and a quinacridone pigment are used. Pigments,
Examples include isoindolinone pigments, metal complex pigments, and the like, and inorganic substances include yellow iron oxide, red iron oxide, carbon black, and titanium dioxide. Examples of the extender include talc, calcium carbonate, precipitated barium sulfate, and silica.

In addition to the above-mentioned components, the above-mentioned water-based paint contains a polyamide wax which is a lubricating dispersion of an aliphatic amide, a polyethylene wax which is a colloidal dispersion mainly composed of polyethylene oxide, an antisettling agent, a curing catalyst, an ultraviolet absorbing agent. Agents, antioxidants, leveling agents, surface modifiers such as silicone and organic polymers, anti-sagging agents, thickeners, defoamers, lubricants, and additives such as cross-linkable polymer particles (microgels) as appropriate. Can be contained.

The aqueous coating film is formed by spray coating or roll coating, and the formed aqueous coating film is set at room temperature. In the case where the coating film formed on the substrate on which the coating film is formed is an electrodeposition coating film, an aqueous intermediate coating film or an aqueous top coating film, or the substrate on which the coating film is formed In the case where the coating film formed as above is an intermediate coating film, an aqueous overcoating film is formed, and when recoating for repair is performed, an aqueous coating film conforming to specifications is formed. The dry film thickness of the aqueous coating film is the same as the intermediate coating film or the top coating film in the above step (1).

Step (3) Step (3) in the present invention is a step of baking and curing a coating film formed from the above-mentioned aqueous paint.

That is, the aqueous coating film formed in the above step (2) and set at room temperature is baked and cured under baking curing conditions as an intermediate coating film or a top coating film. Baking and drying are preferably performed at 120 to 180 ° C for 20 to 30 minutes. If the baking and drying temperature is lower than 120 ° C., the coating film may be insufficiently dried, and if it exceeds 180 ° C., the coating film performance may be reduced. More preferably 130 to 140
° C.

Coated object The coated object of the present invention is obtained by the above-mentioned method of applying a water-based paint. (1) Water / alcohol = 1 to 20/99 (2) a step of forming a coating film with an aqueous paint on the substrate on which the coating film is formed, and (3) a coating film formed with the aqueous coating solution. Baking and hardening; a multi-layer coating film formed sequentially is formed. Painted products formed with these multi-layer coatings do not suffer from deterioration of the coating appearance which tends to occur with water-based coatings, are smooth and have good coating appearance, and contribute to environmental conservation, resource saving and energy saving. .

[0029]

EXAMPLES Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the compounding amount represents a mass part unless there is particular notice. The names of paints and equipment are
Unless otherwise specified, the product name is shown.

Examples 1 to 24, Comparative Examples 1 to 10 Preparation of Coated Substrate Having Coated Film After degreasing a dull steel plate (length 300 mm, width 100 mm and thickness 0.8 mm), a zinc phosphate treating agent ("Surfdyne SD2000", manufactured by Nippon Paint Co., Ltd.) and then a cationic electrodeposition paint ("Power Top U-5").
0 ", manufactured by Nippon Paint Co., Ltd.) was electrodeposited so that the dry film thickness was 25 μm. Then, it was baked at 160 ° C. for 30 minutes. The coated substrate on which the coating film was formed was referred to as coated substrate A. Further, an organic solvent type acrylic /
A melamine resin-based intermediate coating ("Olga S-90 Sealer Gray", manufactured by Nippon Paint Co., Ltd.) is applied by air spraying to a dry film thickness of 40 μm, and baked at 140 ° C. for 30 minutes to form an intermediate coating. The substrate to be coated B was used.

Wipe The coating substrate was coated with a water-based paint as shown in Table 1 to form a coating film. The wipe was soaked with a wiping agent having the composition shown in Table 1. Coating substrate A or B
Was wiped.

A step of forming a coating film with an aqueous paint;
A step of baking and curing the coating film A water-based acrylic / melamine resin-based top coating solid paint ("Super Nicks White", manufactured by Nippon Paint Co., Ltd.) is applied to the substrates A and B wiped as described above to a dry film thickness of 4
Air spray coating to a thickness of 0 μm
After setting for 140 minutes, baking and curing were performed at a temperature of 140 ° C. for 30 minutes. Coating is electrostatic coating machine ("AutoREA", A
BB Industry Co., Ltd.) and an atomization pressure of 2.8 kg /
It was carried out in cm ^2. Atmosphere of the booth during painting is temperature 25
C. and a humidity of 75%. The coating film appearance 1 and the coating film appearance 2 of the obtained multilayer coating film were evaluated by the following evaluation methods, and the results are shown in Table 1.

Evaluation method Coating appearance 1: The wiping trace after wiping of the multilayer coating was visually evaluated. 3: No wiping traces after wiping 2: Slight wiping traces after wiping 1: Wiping traces after wiping are noticeable Coating appearance 2: Visual evaluation of repelling and wetting traces of the multilayer coating did. 3: No repelling, no trace of wetness 2: Slightly repelling, no trace of repelling 1: Remarkable, remarking of repelling,

[0034]

[Table 1]

As is evident from the results in Table 1, this example is a coated article obtained by the method for coating a water-based paint of the present invention,
The finished appearance of the multilayer coating film was good. On the other hand, in the comparative example, traces of wiping after wiping remained, and the finished appearance was not sufficient.

[0036]

According to the present invention, (1) water / alcohol = 1 to 20/99 on the substrate on which the coating film is formed.
Wiping with an aqueous alcohol solution that is ~ 80,
(2) a step of forming a coating film with an aqueous paint on the substrate on which the coating film is formed, and (3) a step of baking and curing the coating film formed with the aqueous paint. By wiping with an aqueous alcohol solution,
When subsequently forming a recoating film, the water remains substantially uniformly on the wipe surface, the surface tension becomes substantially uniform due to the remaining water molecules, and the wetting of the overcoating water-based paint is improved. It is possible to form a high-appearance coating film without wiping traces appearing on the appearance of the repainted coating film.

It has become possible to provide a coating method and a coated product of a water-based paint which do not show wiping traces which tend to occur in a water-based overcoating system and contribute to environmental conservation, resource saving and energy saving. In addition, since the coating film obtained by the present invention exhibits the above-mentioned good finished appearance, it is preferably used in fields where high finishability is required, such as automobiles, motorcycles, and other vehicle outer panels, parts, container outer surfaces, coil coating, and the home appliance industry. used.

Claims (4)

[Claims] 1. A method for applying a water-based paint on a substrate on which a coating film is formed, through the following steps (1) to (3) in order. (1) a step of wiping the substrate on which the coating film is formed with an aqueous alcohol solution in which water / alcohol = 1 to 20/99 to 80; (2) a substrate to which the coating film is formed A step of forming a coating film with an aqueous paint, and (3) a step of baking and curing the coating film formed with the aqueous paint; 2. The aqueous coating composition according to claim 1, wherein the coating film formed on the substrate on which the coating film is formed is any one of an electrodeposition coating film, an intermediate coating film and a top coating film. Painting method. 3. The method according to claim 1, wherein the alcohol of the aqueous alcohol solution is isopropyl alcohol. 4. A coated article obtained by the method for coating a water-based paint according to any one of claims 1 to 3.