JPH05195292A - Forming method of coating film - Google Patents

Abstract

PURPOSE:To provide a forming method of patterned films on aluminum material excellent in long-term durability by which the process time for baking can be reduced. CONSTITUTION:Patterned films on aluminum material are formed by the following process. (i) After the surface of an aluminum material is treated by anodic oxidation, a ground coating film treated by secondary electrolytic pigmentation is formed thereon. (ii) A colored coating material showing thixotropy is applied on the ground coating film by printing or coating to form a patterned film. This colored coating material contains a binder consisting of a mixture resin of fluorocarbon resin with thermoplastic acryl resin by 100:(20 to 60) mixing ratio (calculated as solid weight). (iii) A clear coating material containing a binder resin consisting of a mixture resin of fluorocarbon resin with thermoplastic acryl resin by 100:(20 to 60) mixing ratio (calculated as solid weight) is applied on the patterned film to form a clear coating film. (iv) The patterned film and clear coating film are cured by baking.

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 pattern coating which has excellent durability of an aluminum material and can shorten the coating forming step.

[0002]

2. Description of the Related Art Conventionally, aluminum materials have been subjected to pattern coatings, finished with a design, various building materials,
For example, they are widely used as exterior materials such as siding materials, entrance frames, sliding door frames and lattices, or interior materials such as shoji frames and lattices, bran frames, columns, inner walls and the like. As a conventional design finishing method for aluminum materials, typically, epoxy resin,
A primer that uses an oil-free alkyd resin as a binder is applied, then a colored coating agent (grand coat) that uses an acrylic resin, an oil-free alkyd resin, etc. as a binder is applied, and then an oil-modified alkyd resin, A 4-coat 3-bake method is adopted in which a coating agent containing an acrylic resin as a binder is printed in a pattern and finally a clear coating agent containing an acrylic resin or oil-free alkyd resin as a binder is applied. Was there. However, these conventional finishing methods tend to cause chalking at the interface between the clear coating and the ground coating or the pattern coating due to the ultraviolet rays that have passed through the clear coating, resulting in a decrease in interlayer adhesion or clouding of the clear coating. The pattern becomes unclear, a clear coating film is formed in a blister, etc., and the above-mentioned coating film defects usually occur in 5 to 7 years, and there is a problem in durability. Further, as described above, there are many baking processes, and there are problems from the viewpoint of coating workability and energy saving.

The inventors of the present invention have made earnest studies in view of the above circumstances, and as a result, have found a method for forming a pattern coating film of an aluminum material, which is excellent in long-term durability and can shorten the baking process, and arrived at the present invention.

[0004]

That is, the present invention is
(i) a step of forming a ground coat film subjected to secondary electrolytic coloring treatment after anodizing the surface of the aluminum material, (ii) a mixing ratio of a fluorocarbon resin and a thermoplastic acrylic resin on the ground coat film ( A step of forming a pattern film by printing or applying a colored coating agent showing thixotropy, which uses a mixed resin of solid content weight (100: 20 to 60) as a binder, and (iii) a fluorocarbon on the pattern film. Mixing ratio of resin and thermoplastic acrylic resin (in terms of solid content weight) [100: 20-60]
A step of applying a clear coating agent using the mixed resin of as a binder to form a clear coating, and (iv) the pattern coating,
The present invention relates to a method for forming a pattern coating of an aluminum material, which comprises a step of baking and curing the clear coating.

The present invention will be described in detail below. The colored coating agent for forming the pattern coating used in the present invention is a mixed resin consisting of a fluorocarbon resin and a thermoplastic acrylic resin, a binder, a coloring pigment, an organic solvent and a viscosity-imparting agent as essential components, and if necessary, the constitution It is composed of a pigment, a modifier such as an oil-free alkyd resin, a silane coupling agent, and various additives such as a surface modifier.

The fluorocarbon resin is described in US Pat.
Representative examples include polyvinyl fluoride, polyvinylidene fluoride, vinyl fluoride copolymers, vinylidene fluoride copolymers and the like described in 19010, 2510783, 2835818, 2970988 and the like. The thermoplastic acrylic resin has 1 to 8 carbon atoms of acrylic acid or methacrylic acid.
Alkyl ester polymer or acrylic acid,
Copolymers with methacrylic acid, alkyl esters of hydroxyethyl acrylic acid, alkyl esters of hydroxyethyl methacrylic acid, styrene, acrylonitrile, etc., having a weight average molecular weight of 100,000 to 300,000 are suitable.

The mixing ratio of the fluorocarbon resin and the thermoplastic acrylic resin is (100:
20 to 60) is suitable, and when the amount of the acrylic resin is more than the above range, the weather resistance of the obtained coating is lowered, and conversely, when it is less, the coating workability is deteriorated, and cracks are apt to occur in the obtained coating. It is not preferable. Examples of the color pigment include titanium oxide, iron oxide, yellow lead, carbon black,
Various inorganic and organic color pigments used as usual color pigments for paints such as calcined metal oxide, phthalocyanine blue, isoindolinone yellow, and quinacridone red can be used without particular limitation.

Examples of the organic solvent include hydrocarbon solvents such as toluene and xylene, ester solvents such as ethyl acetate and butyl acetate, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and isophorone, and ethylene glycol monoethyl ether acetate. Typical examples include ether solvents such as acetic acid diethylene glycol monobutyl ether.

The viscosity-imparting agent is added so as to improve printing characteristics (transferability), and a clear coating agent described below can be applied by a wet / wet method so that it can be applied repeatedly without causing bleeding. .. As the viscosity-imparting agent, cellulose acetate butyrate, ethyl cellulose acetate butyrate, ethyl cellulose, acetyl cellulose, and other fibrin-based resins, aluminum stearate, zinc stearate, aluminum octylate, organic bentonite, white carbon, polyethylene, rosin-based resins, etc. Is a typical example.

Further, it is desirable to incorporate a silane coupling agent in order to further improve the transferability of the colored coating agent. Examples of the silane coupling agent include vinyltrichlorosilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-aminopropyl. Typical examples include triethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

The colored coating agent for forming the pattern coating used in the present invention comprises the above-mentioned components as constituent components, and the mixing ratio is 10 to 100 parts by weight of the color pigment to 100 parts by weight of the binder. The section is appropriate. Further, the viscosity-imparting agent is preferably about 0.1 to 10 parts by weight so that the organic solvent volatilizes immediately after printing or coating and also exhibits thixotropy.

The amount of the organic solvent is preferably such that the viscosity during printing or coating is Fort Cup No. 4 (25 ° C.) for 20 to 50 seconds. The clear coating agent for forming the clear coating used in the present invention is the same as the above-mentioned coloring coating agent for forming the pattern coating except that the coloring pigment is removed or the coloring pigment is blended in a small amount so as not to impair the transparency. A coating agent can be used. Further, it may be a clear coating agent which does not show thixotropy. Next, the method for forming the pattern film of the present invention will be described.

First, in the step (i), the surface of the aluminum material is adjusted as necessary by degreasing, etching, removing smut, etc., and then a direct current of about 15 V is passed in a sulfuric acid aqueous solution according to a conventional method, Corrosion-proof thickness of about 5
An anodic oxide film of about 20 μm is formed. Then, a secondary electrolytic coloring treatment by an alternating current electrolytic coloring method or the like is performed to form a ground coat film.

Specifically, the thickness is about 5 to 25 μm by alternating current electrolysis according to a conventional method in a sulfuric acid metal salt bath of nickel, tin, cobalt or a mixture thereof.
The colored coat is formed, and the pores are subjected to a sealing treatment by washing with hot water to obtain a ground coat. In the step (ii), a dry film thickness of about 1 to 5 μm is formed on the entire surface of the ground coat film or at an arbitrary position by a printing means such as gravure offset printing or a coating means such as a spray. Print or apply to form a pattern film and set at room temperature for several minutes or longer. Then, without baking, a clear coating agent is applied by a wet / wet method in step (iii) to a dry film thickness of about 3 to 30 μm by means such as a spray or roll coater on the entire surface including the pattern coating.

In the step (iv), the obtained pattern coating and clear coating are baked and simultaneously cured to form the pattern coating of the present invention. Although the baking conditions differ depending on the type of blocked polyisocyanate compound used, etc.
It is suitable to bake at 0 to 250 ° C. for 10 to 40 minutes.

[0016]

The method of forming a pattern coating of the present invention uses a binder containing a fluorocarbon resin as a main component, so that it has better weather resistance than a coating obtained by a conventional method of forming a pattern coating of an aluminum material. It can be said to be a method of high practical value because the durability of the coating is improved several steps, and the coating and baking processes can be shortened and energy can be saved.

[0017]

EXAMPLES The present invention will now be described in more detail with reference to examples. In the examples, "parts" and "%" are shown by weight. (Preparation of Colored Coating Agent A) 40 parts of vinylidene fluoride resin varnish ["Kainer # 500" (trade name of Japan Penwalt Co., Ltd., solid content 50%), ethyl acrylate-methacrylic acid copolymer varnish (solid content 40%) To a binder solution consisting of 20 parts, 16 parts of titanium dioxide and 2 parts of calcined metal oxide [Dyviloxide 9550] (trade name, manufactured by Dainichiseika Kogyo Co., Ltd.) are added and kneaded and dispersed. As a result, 1 part of white carbon, 1 part of polyethylene paste [“Disparlon 4200-20” (trade name of Kusumoto Kasei Co.)], 10 parts of xylene and 10 parts of methyl isobutyl ketone were mixed to give a thixo coefficient of 6.0, and further just before printing. Add a mixed solvent of xylene and methyl ethyl ketone (1: 1) to a viscosity of 3
Color coating agent A was prepared by adding 5 seconds. (Preparation of Colored Coating Agent B) From Colored Coating Agent A to Silane Coupling Agent [“KBE903”, Shin-Etsu Chemical Co., Ltd. trade name]
A colored coating agent B was prepared in the same manner except that was added. (Preparation of Colored Coating Material C) A colored coating material C having no thixotropic property was prepared in the same manner except that the viscosity imparting agent was removed from the colored coating material A. (Preparation of clear coating agent A) 6 parts of xylene and 6 parts of methyl isobutyl ketone were added to a binder solution consisting of 58 parts of the above-mentioned vinylidene fluoride resin varnish and 30 parts of the above-mentioned copolymer varnish.
The parts were mixed, and immediately before coating, a mixed solvent of xylene and methyl ethyl ketone (1: 1) was added to have a viscosity of 15 seconds to prepare a clear coating agent A. Examples 1 and 2 and Comparative Example 1 An aluminum material degreased, etched, and smut-removed by a conventional method is immersed in a 17.5 w / v% sulfuric acid aqueous solution to form an anode, which is provided between an aluminum cathode provided as a counter electrode. Direct current of voltage 15V for 35 minutes, about 15μm
The anodic oxide film of was formed and washed with water.

Then, this was heated to a liquid temperature of 20 ° C. having the following composition.
Immerse in the electrolytic coloring solution of to make the distance between the electrodes 25 mm,
AC electrolysis was performed for 10 minutes at an applied voltage of 15 V to obtain a colored film, which was further washed with hot water for sealing treatment and dried to form a ground coat film. Nickel sulfate 50 g / liter Cobalt sulfate 50 g / liter Boric acid 40 g / liter Sulfosalicylate 10 g / liter Then, a pattern coating was formed on the surface of the aluminum material in the steps shown in Table 1. Comparative Example 2 A pattern coating was formed on the surface of an aluminum material treated with a chromate conversion coating in the steps shown in Table 1.

The primary adhesion, secondary adhesion, and
Each test of salt sprayability, castability, accelerated weathering resistance, ink transferability and ink smearing property was conducted, and the results are shown in Table 1.
It is shown in the bottom row. As is clear from Table 1, the coating film on which the pattern coating film was formed by the method of the present invention was excellent in adhesion, water resistance, cast resistance and weather resistance, and was also excellent in ink transferability and bleeding resistance.

On the other hand, in Comparative Example 1 in which a colored coating agent without thixotropy was used, the transferability of the ink was poor, and ink bleeding also occurred. Further, in Comparative Example 3 of the conventional method, not only the number of baking steps was increased, but also the weather resistance was very poor.

[0021]

[Table 1]

Claims (1)

[Claims] 1. A step of: (i) forming a ground coat film that has been subjected to a secondary electrolytic coloring treatment after anodizing the surface of the aluminum material; and (ii) fluorocarbon resin and thermoplastic acrylic resin on the ground coat film. A step of forming a pattern film by printing or applying a thixotropic colored coating material using a mixed resin having a mixing ratio (in terms of solid content weight) of [100: 20 to 60] as a binder, (iii) Mixing ratio of fluorocarbon resin and thermoplastic acrylic resin on the pattern film (solid content weight conversion)
An aluminum material comprising a step of applying a clear coating agent having a mixed resin of [100: 20 to 60] as a binder to form a clear coating, and (iv) the step of pattern coating and the step of baking and curing the clear coating. The method of forming the pattern film.