JP2001293428A - Method for depositing double-layered coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for depositing a new metallic double-layered coating film using a scaly bright pigment. SOLUTION: The face coated with an uncured water-base coating is coated with a brilliant coating consisting essentially of the scaly brilliant pigment and an organic solvent to deposit a double-layered coating film by this method.

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 novel metallic multilayer coating film using a flaky glittering pigment.

[0002]

2. Description of the Related Art A metallic paint containing a brilliant pigment such as aluminum flakes is applied, and a clear paint is applied without curing the paint film, and both the paint films are cured simultaneously by heating. The metallic multi-layer coating film obtained at least has a glittering glitter and excellent design, and is widely used as a top coating film on the outer plate of an automobile body. However, a single coating of this metallic paint is mainly composed of a resin component, aluminum flakes and coloring pigments, and among these, the aluminum flakes are oriented parallel to the coating surface in the coating. Is ideal, but in fact, it is often irregularly oriented, so it is necessary to form a metallic coating film that aluminum flakes originally have excellent whiteness and metallic luster and have strong flip-flop properties. Making it difficult.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a metallic multilayer coating film using a scaly glittering pigment, and more particularly, to a method for applying a scaly glittering pigment to a coated surface in a coating film. Provide a new method of forming a metallic coating film that is oriented in parallel to the flake-like brilliant pigment and has excellent characteristics such as white and metallic luster, which are inherently possessed by this scaly brilliant pigment, and has strong flip-flop properties. It is to be. The feature is that a glitter paint containing a flaky glitter pigment and an organic solvent as main components is applied to the uncured coating surface of the water-based paint.

Thus, according to the present invention, the aqueous paint (A)
A method of forming a multi-layer coating film (hereinafter referred to as the present method), which comprises applying a glittering paint (B) containing a flaky glitter pigment and an organic solvent as main components to the uncured coating surface.

Hereinafter, the present method will be described in detail.

[0006] Metal articles and plastic articles are examples of objects to be coated to form a multi-layer coating film according to the present method, and automobile bodies such as passenger cars, trucks, motorcycles, buses, etc. formed using these materials. The skin is particularly suitable. Prior to the application of the water-based paint (A), these objects are subjected to a surface treatment and the like, and if necessary, a cationic electrodeposition coating and an intermediate coating are performed to cure these coating films. Is preferred.

The water-based paint (A) is a paint to be applied to an object to be coated prior to the glittering paint (B), and is a water-based paint containing water as a main solvent or a dispersion medium. And a thermosetting water-based paint containing a base resin such as a polyester resin and a hardener.

As the vinyl resin, those known per se can be used, for example, a carboxyl group-containing polymerizable monomer,
A number average molecular weight of about 3,000 to about 400, obtained by copolymerizing a hydroxyl group-containing polymerizable monomer and other polymerizable monomers.
00, acid value about 20 to about 100, hydroxyl value about 20 to about 20
0 acrylic resin and vinyl resin.

The carboxyl group-containing polymerizable monomers include monoethylenically unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, and itaconic acid; and the hydroxyl group-containing polymerizable monomers include (meth) acrylic acid. Examples include hydroxyalkyl esters of monoethylenically unsaturated carboxylic acids such as 2-hydroxyethyl and 2-hydroxypropyl (meth) acrylate. Other polymerizable monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) lauryl acrylate, (meth)
Alkyl esters of monoethylenically unsaturated carboxylic acids such as decyl acrylate, (meth) acrylamide, N
-Acrylamide derivatives such as methylol (meth) acrylamide and diacetone acrylamide; glycidyl esters of monoethylenically unsaturated carboxylic acids such as glycidyl (meth) acrylate; vinyl esters of saturated carboxylic acids such as vinyl acetate and vinyl propionate And aromatic unsaturated monomers such as styrene, α-methylstyrene and vinyltoluene.

The acrylic resin and the vinyl resin thus obtained can be used in the form of a basic compound such as ammonia or amines such as triethylamine, monoethanolamine, diethanolamine, triethanolamine and dimethylaminoethanol; and alkali metal hydroxides such as sodium hydroxide. It can be made aqueous by neutralizing with a substance. Further, with or without using a carboxyl group-containing polymerizable monomer, water is obtained by dispersing a copolymer in water using a hydroxyl group-containing polymerizable monomer and other polymerizable monomers. Dispersions can also be used.

As the aqueous polyester resin, those known per se can be used. For example, a number average molecular weight of about 1,000 to about 20,000, an acid value of about 20 to about 20, obtained by an esterification reaction of a polyhydric alcohol and a polybasic acid. Polyester resins having a hydroxyl value of about 100 and a hydroxyl value of about 20 to about 200 can be used. Polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, 2,2-dimethylpropanediol, glycerin, trimethylolpropane, and pentaerythritol; and polybasic acids such as phthalic anhydride, isophthalic acid, and tetrahydroanhydride Phthalic acid, hexahydrophthalic anhydride, maleic anhydride, succinic anhydride, adipic acid, sebacic acid, trimellitic anhydride, pyromellitic anhydride, etc. can be used, and if necessary, benzoic acid or t-butylbenzoic acid, etc. Monobasic acid, castor oil, tung oil, safflower oil, soybean oil, linseed oil, tall oil, coconut oil, and oil components of these fatty acids can be used.

Thus, the polyester resin is neutralized with ammonia or basic substances such as amines such as triethylamine, monoethanolamine, diethanolamine, triethanolamine and dimethylaminoethanol, and alkali metal hydroxides such as sodium hydroxide. By doing so, it can be made aqueous.

As the curing agent, a melamine resin, a benzoguanamine resin or the like can be suitably used, and these can be used regardless of hydrophilicity or hydrophobicity.

The ratio of the base resin and the curing agent in the water-based coating composition (A) is preferably about 50 to about 90% by weight, preferably about 60 to about 85% by weight, based on the total solid content of both. The curing agent is used in the range of about 10 to about 50% by weight, preferably about 15 to about 40% by weight.

The single coating film of the water-based paint (A) may be colorless and transparent, colored and transparent, or colored and opaque. For coloring, a solid color tone coating film is suitable.

The water-based paint (A) is adjusted to a viscosity of about 10 to about 50 seconds (20 ° C.) with a Ford cup # 4 at the time of coating, and is subjected to the above coating by air spray coating, airless spray coating, electrostatic coating or the like. Can be applied to painted objects. Its film thickness is about 5 to about 30 μm, especially about 1 μm, based on the cured coating film.
0 to about 20 μm is preferred.

In the present method, the glitter coating (B) containing a scaly glitter pigment and an organic solvent as main components is applied to the uncured coating surface of the aqueous coating (A) applied to the object to be coated. In particular, the uncured coating film of the water-based paint (A) at the time of applying the glitter paint (B) has a water content of 50 to 50%.
It is preferably 90% by weight, especially 60 to 80% by weight, viscosity of 1000 centipoise or more (20 ° C), particularly 1300 to 2000 centipoise (20 ° C), and a gel fraction of 10% by weight or less. In order to adjust the water content, viscosity and gel fraction of the uncured coating film of the water-based paint (A) to the above ranges,
It is preferable that the uncured coating film of the water-based paint (A) applied to the object is left at room temperature to 100 ° C. for 1 to 30 minutes.

The viscosity of the “uncured coating film” of the water-based coating material (A) is determined by applying the coating material to a glass plate under conditions that are practically applicable.
After leaving it for a predetermined time, it was collected in a glass bottle, and it was sheared at a shear rate of 10 sec ^-1 using a cone and plate viscometer.
Was measured by reading the viscosity at. In the same manner, about 2 g of the collected paint was heated at 100 ° C. for 3 hours, and the weight loss rate before heating was measured. The gel fraction is
In the same manner, the residual ratio after extracting the collected paint with acetone for 3 hours at the reflux temperature was measured (calculated excluding the pigment).

In the present method, the glittering paint (B) has a water content, a viscosity and a gel fraction adjusted to the above ranges.
This is a paint to be applied to the uncured coating surface of the water-based paint (A), and is a glitter paint containing a scaly glitter pigment and an organic solvent as main components.

The brilliant paint (B) is a brilliant paint containing a flaky brilliant pigment and an organic solvent, and may further contain, if necessary, a resin composition for a paint, an anti-settling agent, an electrostatic assistant, etc. It is possible to mix.

As the scaly brilliant pigment, a flake pigment exhibiting a glittering metallic luster or light interference can be used. Specifically, aluminum (leafing, non-leafing), vapor-deposited aluminum, oxybismuth chloride , Alumina (auminium oxide), mica, graphite, mica-like iron oxide, titanium oxide coated mica, iron oxide coated mica and the like. Each of these shapes is scaly, and preferably has a size in the longitudinal direction of 2 to 50 μm and a thickness of 0.001 to 2 μm. In addition, as organic solvents, hydrocarbons used in ordinary paints,
Ester, ether, alcohol, and ketone solvents can be used.

The ratio of the flaky brilliant pigment to the organic solvent is based on the total weight of these two components, and the flaky brilliant pigment is 1 to 60% by weight, particularly 2 to 10% by weight, Is suitably in the range of 99 to 40% by weight, especially 98 to 90% by weight.

In the glittering paint (B), in addition to the above-mentioned two components, a paint resin composition which can be contained as required includes acrylic resins, polyester resins and alkyds having a functional group such as a hydroxyl group. Examples of the composition include a resin, a base resin such as a urethane resin, and a curing agent such as a melamine resin and a (block) polyisocyanate compound. The compounding amount of these resin compositions for paints is suitably not more than 300 parts by weight, especially in the range of 0.1 to 100 parts by weight, per 100 parts by weight of the flaky glittering pigment.
As an anti-settling agent, for example, fatty acid amide wax,
Oxidized polyethylene and the like.
A suitable amount is 50 parts by weight or less, especially 0.1 to 30 parts by weight, per 100 parts by weight of the flaky glittering pigment.

In the present method, the glitter coating (B) is applied to the uncured coating surface of the water-based coating (A) by adjusting the viscosity during coating to about 10 to about 50 seconds (20 ° C.) with a Ford cup # 4. The coating can be performed by air spray coating, airless spray coating, electrostatic coating, or the like. The film thickness is generally from about 0.5 to about 5 μm, particularly from about 0.8 to about 2 μm, as a cured coating film (only a flaky glittering pigment or a resin for a coating may coexist). preferable.

When an organic solvent-based brilliant paint (B) is applied to the uncured coating surface of the water-based paint (A), the brilliant paint (B) is applied to the uncured coating surface as if the oil was poured on the water surface. It spreads quickly and uniformly, and as a result, the scaly glittering pigment is uniformly and densely oriented parallel to the uncured coating surface, and each characteristic that the scaly glittering pigment originally has, For example, flaky aluminum can form a metallic coating film that is white, has excellent metallic luster, and has strong flip-flop properties.

In the present method, the glitter coating (B) is applied to the uncured surface of the water-based coating (A) and then left at room temperature or further forcibly dried at 50 to 100 ° C. for about 1 to 30 minutes. ,
By heating at 100 to 170 ° C. for about 10 to 40 minutes to simultaneously cure the water-based coating (A) coating and the glittering coating (B) coating, the metallic multilayer coating of the present invention is intended. Can be formed.

Further, in the present method, the water-based paint (A) and the glitter paint (B) are applied as described above, and if necessary, these coating films are heated and cured, and then the glitter paint (B) is applied. Can be coated with the clear paint (C).

The clear paint (C) is a paint that forms a colorless and transparent or colored and transparent coating film. The clear coating material (C) has a multi-layer coating film which has good cosmetic, finished appearance, weather resistance, chemical resistance, water resistance, moisture resistance and the like. It can be further improved. Specifically, a hydroxyl group,
Base resins such as acrylic resin, polyester resin, alkyd resin, fluororesin, urethane resin and silicon-containing resin having functional groups such as carboxyl group, silanol group and epoxy group, melamine resin, (block) polyisocyanate compound, epoxy resin Or, an organic solvent-based or non-aqueous dispersion type paint containing a thermosetting resin composition comprising a compound, a carboxyl group-containing resin or a compound, an acid anhydride, a crosslinker such as an alkoxysilane group-containing resin or a compound as a vehicle component. Is mentioned. An ultraviolet absorber, a coloring agent, and the like can be appropriately compounded in these clear paints.

The clear paint (C) is preferably of a high solid content type from the viewpoint of preventing pollution and saving resources. Specifically, the non-volatile content at the time of coating is about 35% by weight or more, preferably about 35% by weight. It is preferably adjusted to 40 to about 80% by weight, more preferably to about 45 to about 80% by weight.

The clear paint (C) is an air spray paint,
It can be applied by airless spray coating, electrostatic coating, or the like, and is preferably applied to a thickness of about 5 to about 50 μm based on the cured coating film.

The multilayer coating film according to the present method can be formed by applying the above-mentioned water-based paint (A), glitter paint (B), and, if necessary, clear paint (C).

[0032]

When the organic solvent-based glittering paint (B) is applied to the uncured coating surface of the water-based paint (A), the paint (B) is applied to the coating surface of the paint (A) as if oil was floating on the water surface. ) Is thin and easy to spread uniformly, and since the paint (B) is mainly composed of an organic solvent and a scaly glittering pigment, the scaly glittering pigment is uniformly and uniformly applied to the uncured coating surface. It is easy to orient in the direction parallel to the painted surface. As a result, aluminum flakes are white, have excellent metallic luster, and have a strong flip-flop property compared to those coated with conventional metallic paint. Can be formed.

[0033]

EXAMPLES Examples and comparative examples according to the present invention will be described below. All parts and percentages are based on weight, and the thickness of the coating film is based on the cured coating film. 1. Preparation of sample 1) Coating object Thermosetting epoxy resin-based cationic electrodeposition paint (“Elecron 9600”, trade name, manufactured by Kansai Paint Co., Ltd.) on a 0.8 mm thick dull steel plate that has been subjected to zinc phosphate conversion treatment. Is electrodeposited so as to have a film thickness of 20 μm, and heated at 170 ° C. for 30 minutes to cure the coating film. Then, an intermediate coating for automobiles (“TP-37 Primer Surfacer”, manufactured by Kansai Paint Co., trade name, A thermosetting polyester resin / melamine resin organic solvent system) was applied by air spraying so as to have a film thickness of 25 μm, and heated at 140 ° C. for 30 minutes to cure the coating film to obtain an object to be coated. 2) Aqueous paint (A) a): 25 parts of polymer (a) (Note 1), 60 parts of polymer (B) (Note 2), "Cymel 327" (trade name, melamine resin, manufactured by Scitech) 15 Parts and 80 parts of titanium white pigment, and water was added to the mixture to obtain a viscosity of 40 seconds / Ford Cup # 4/2
The temperature was adjusted to 0 ° C. to obtain water-based paints (A) and (a). (The compounding ratio is the solid content ratio.) (Note 1) Polymer (a): 15 parts of styrene, 20 parts of methyl methacrylate, 25 parts of ethyl acrylate, 20 parts of n-butyl acrylate, 15 parts of hydroxyethyl acrylate and 5 parts of acrylic acid Of a polymer having a hydroxyl value of 7
2, acid value 39, number average molecular weight 12000) neutralized with dimethylethanolamine. (Note 2) Polymer (b): Polymer composed of 15 parts of styrene, 20 parts of methyl methacrylate, 25 parts of ethyl acrylate, 25 parts of n-butyl acrylate, 5 parts of acrylic acid and 10 parts of diacetone acrylamide (hydroxyl value 0, Acid value 39, carbonyl value 0.6 mmol / g / solid content, number average molecular weight 12000) neutralized with dimethylethanolamine. b): 80 parts of polymer (c) (Note 3) and Cymel 32
7 "was mixed, and water was added to adjust the viscosity to 40 seconds / Ford cup # 4/20 ° C. (The compounding ratio is a solid content ratio.) (Note 3) Polymer (C): 15 parts of styrene, 20 parts of methyl methacrylate, 25 parts of ethyl acrylate, 15 parts of n-butyl acrylate, 15 parts of hydroxyethyl acrylate, 5 parts of acrylic acid And a polymer consisting of 5 parts by weight of diacetone acrylamide (hydroxyl value 72, acid value 39, carbonyl value 0.3 mmol / g / solid content, number average molecular weight 12
000) neutralized with dimethylethanolamine.

3) Bright paint (B) a): Non-leafing aluminum flake (Note 4) 5
And 95 parts of "Swazol 1000". (Note 4) Non-leafing aluminum flakes: "Alpaste 7680NS" (manufactured by Toyo Aluminum Co., Ltd., trade name, longitudinal dimension 13 μm, thickness 0.1 to 2 μm) b): Non-leafing aluminum flakes (Note 4) 5
Parts, 2 parts of the resin composition (Note 5) and “Swazol 100
0 "a mixture of 93 parts. (Note 5) Resin composition: hydroxyl value 100, number average molecular weight 1
A mixture consisting of 5000 acrylic resin / butyl etherified melamine resin = 75/25 (weight ratio). c) Non-leafing aluminum flakes (Note 4) 1
Parts, 6 parts of the resin composition (Note 5) and “Swazol 100
0 "a mixture of 93 parts.

2. Examples and Comparative Examples Example 1 A water-based paint (A) (a) was applied to an object to be coated so as to have a film thickness of 25 μm, and allowed to stand at room temperature for 15 minutes (the viscosity of the uncured coating film was 1500 centipoise). , Moisture content is 65
%, The gel fraction was 0%), and the glittering paint (B) (a)
Is coated to a thickness of 1 μm and left at room temperature for 3 minutes.
"Magiclon clear" (manufactured by Kansai Paint Co., Ltd., trade name, organic solvent type thermosetting acrylic resin clear paint) with a film thickness of 4
0 μm, leave at room temperature for 3 minutes,
For 30 minutes to simultaneously cure these multilayer coating films.

When the glitter coating (B) (a) is applied to the uncured coating surface of the water-based coating (A) (a), the coating surface of the coating (A) (a) is applied to the coating surface as if oil was floating on the water surface. Since the paint (B) (a) spreads thinly and uniformly, and because the paint (B) (a) is mainly composed of an organic solvent and flaky aluminum pigment,
The scaly aluminum pigment is entirely uniform on the uncured coating surface and is oriented in a direction parallel to the coating surface. As a result, compared to Comparative Example 1, the aluminum pigment is white, has excellent metallic luster, and has flip-flop properties. , A metallic coating film having a strong

Example 2 A water-based paint (A) (b) was applied to an object to be coated so as to have a film thickness of 25 μm, and was allowed to stand at room temperature for 15 minutes. Content rate is 65
%, The gel fraction was 0%), and the glittering paint (B)
(b) was coated to a thickness of 1 μm, left at room temperature for 3 minutes, and then coated with “MAGICRON CLEAR” (trade name, manufactured by Kansai Paint Co., Ltd., organic solvent type thermosetting acrylic resin clear coating) to a thickness of 40 μm. And leave it at room temperature for 3 minutes.
These multilayer coatings were simultaneously cured by heating at 40 ° C. for 30 minutes.

When the glitter coatings (B) and (b) are applied to the uncured coating surfaces of the aqueous coatings (A) and (b), the coating surfaces of the coatings (A) and (b) are applied as if oil were floating on the water surface. Since the paints (B) and (b) spread thinly and uniformly, and because the paints (B) and (b) are mainly composed of an organic solvent and flaky aluminum pigment,
The scaly aluminum pigment is entirely uniform on the uncured coating surface and is oriented in a direction parallel to the coating surface. As a result, compared to Comparative Example 1, the aluminum pigment is white, has excellent metallic luster, and has flip-flop properties. , A metallic coating film having a strong

COMPARATIVE EXAMPLE 1 A water-based paint (A) (a) was applied to an object to be coated so as to have a film thickness of 25 μm, and allowed to stand at room temperature for 15 minutes. Content rate is 65
%, The gel fraction was 0%), and the brilliant paint (B) (c)
Is coated to a thickness of 1 μm and left at room temperature for 3 minutes.
"Magiclon clear" (manufactured by Kansai Paint Co., Ltd., trade name, organic solvent type thermosetting acrylic resin clear paint) with a film thickness of 4
0 μm, leave at room temperature for 3 minutes,
For 30 minutes to simultaneously cure these multilayer coating films.

When the glitter coatings (B) and (c) are applied to the uncured coating surface of the aqueous coatings (A) and (a), the coatings (B) and (c) become thin on the coating surfaces of the coatings (A) and (a). It does not spread uniformly, and paints (B) and (c) contain a large amount of paint resin.
It is difficult to orient the flaky aluminum pigment uniformly on the uncured coating surface and in a direction parallel to the coating surface. As a result, the whiteness is inferior to that of Examples 1 and 2, and the metallic luster is low. The feeling was not enough, and the flip-flop property was weak.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C09D 201/00 C09D 201/00 F term (reference) 4D075 CB13 EA06 EB52 EB56 EC23 4J038 CG031 CG071 CG141 CH121 CJ021 CJ101 CJ131 CJ141 DD061 DD081 DD231 GA03 GA06 HA066 HA216 HA546 JA01 JA17 JA25 JA32 JA55 KA06 KA08 KA20 MA07 MA08 MA15 NA01 PA19 PB07 PC02

Claims (2)

[Claims] 1. A method for forming a multi-layer coating film, comprising applying a glitter paint (B) containing a flaky glitter pigment and an organic solvent as main components to the uncured coating surface of the aqueous paint (A). 2. The method for forming a multilayer coating film according to claim 1, wherein the uncured coating film of the water-based coating material (A) has a water content of 20 to 80% by weight and a viscosity of 1000 centipoise or more (20 ° C.).