JPH03284376A - Formation of pattern coating film on aluminum material - Google Patents

Abstract

PURPOSE:To enhance the weatherability, etc., of a coating film and to save energy by forming a primer coating film and a ground coating film on the surface of an aluminum material, curing the films, then laminating a pattern coating film and a clear coating film and curing the films. CONSTITUTION:A primer coating film consisting of an epoxy resin and a curing agent is provided on the surface of a surface-treated aluminum material, a colored ground coating film consisting of a fluorocarbon resin and a thermoplastic acrylic resin and added with a binder and a silane coupling agent is laminated thereon, and both films are baked and cured. A colored coating agent is then applied on the ground-coat film to provide a pattern coating film, a clear coating film with a mixture of the fluorocarbon resin and thermoplastic resin as a binder is laminated, and the pattern coating film and clear coating film are baked and cured.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a method for forming a patterned film that has excellent durability on aluminum materials and can shorten the process of forming the film.

<Conventional technology and its problems to be solved> Aluminum materials have traditionally been coated with patterns, finished with designs, and used as various building materials.
For example, it is widely used for exterior materials such as siding materials, entrance frames, sliding door frames and lattices, and interior materials such as shoji frames and lattices, fusuma frames, pillars, and interior walls.

The conventional design finishing method for aluminum materials typically involves applying a primer using an epoxy resin, oil-free alkyd resin, etc. as a binder, and then applying a primer using an acrylic resin, oil-free alkyd resin, etc. as a binder. A colored coating material (ground coat) is applied, then a coating material containing oil-modified alkyd resin, acrylic resin, etc. as a binder is printed in a pattern, and finally acrylic resin, oil-free alkyd resin, etc. are bonded. A four-coat, three-bake method was used in which a clear coating agent was applied. However, these conventional finishing methods tend to cause chalking at the interface between the clear coating and the ground coat or pattern coating due to the ultraviolet rays that have passed through the clear coating, resulting in decreased interlayer adhesion and clouding of the clear coating. The pattern becomes unclear, blisters and the like occur in the clear film, and the above-mentioned coating film defects usually occur after 5 to 7 years, posing problems in terms of durability.

Furthermore, as mentioned above, there are many baking steps, which poses problems from the viewpoint of painting workability and energy saving.

As a result of intensive study in view of the current situation, the present inventors found that
We have discovered a method for forming a patterned film on aluminum that has excellent long-term durability and can shorten the baking process, leading to the present invention.

<Means for Solving the Problems> That is, the present invention provides: (1) Applying a thixotropic primer containing an epoxy resin and its curing agent as a binder to the surface of a surface-treated aluminum material, and forming a primer film. (2) forming a mixed resin of a fluorocarbon resin and a thermoplastic acrylic resin in a mixing ratio (solid content weight) [100:20-60] as a binder on the primer film, and a silane coupling agent; (3) baking and curing the primer film and the ground coat film; (4) applying a colored coating material containing a fluorocarbon resin and a thermoplastic resin on the ground coat film; A step of printing or applying a thixotropic colored coating using a mixed resin of acrylic resin at a mixing ratio (solid content weight) [:100:20 to 601 as a binder to form a patterned coating, (5) ) Mixing ratio of fluorocarbon resin and thermoplastic acrylic resin (converted to solid content weight) on the pattern coating [
100:20 to 60] as a binder to form a clear coating, and (6) baking and curing the pattern coating and the clear coating. The present invention relates to a method for forming a patterned film.

The present invention will be explained in detail below.

The primer used in the present invention contains a binder consisting of an epoxy resin and its curing agent, a viscosity imparting agent, and an organic solvent as essential components, and further includes a coloring pigment, an antirust pigment, an extender pigment, an acrylic resin, and a vinylidene fluoride resin as necessary. , a modifier such as oil-free liquid resin, and additives such as a surface conditioner.

The epoxy resin has a weight average molecular weight of 1500 to 60.
000 resin is suitable, and specific examples include diglycidyl ether of bisphenol A and novolak epoxy resin.

As the curing agent, those commonly used as curing agents for epoxy resins can be used without particular limitation, and typical examples thereof include amino resins, phenol resins, blocked polyisocyanates, and the like.

The tackifying agent is added so that the colored coating agent that forms the ground coat film (described later) can be coated over and over in a wet/wet manner. Immediately after application, the organic solvent evaporates and the brimer film immediately undergoes thixotropy. It is appropriate to add about 0.1 to 10% by weight based on 100 parts by weight of the binder.

Cellulose acetate butyrate as a viscosity imparting agent;
Typical examples include cellulose resins such as ethyl cellulose acetate butyrate, ethyl cellulose, and acetyl cellulose, aluminum stearate, zinc stearate, aluminum octylate, organic bentonite, white carbon, polyethylene, and rosin resins.

The organic solvents include methyl ethyl ketone, methyl isobutyl ketone, and methyl isobutyl ketone, which are commonly used for epoxy resins.
Typical examples include xylene, toluene, butyl acetate, and ethyl acetate.

The amount of organic solvent varies depending on the coating method, etc., but in the case of spray coating, for example, the appropriate amount is such that the viscosity at the time of coating is Ford Cup Nn4 (20 DEG C.) 10 to 30 seconds.

The colored coating material that forms the ground coat film used in the present invention contains a binder, which is a mixed resin consisting of a fluorocarbon resin and a thermoplastic acrylic resin, a colored pigment, an organic solvent, and a silane coupling agent as essential components, and further contains, as necessary, It is composed of an extender pigment, a modifier such as an oil-free alkyd resin, and various additives such as a surface conditioner.

The fluorocarbon resin is disclosed in US Pat. No. 2,419,010.
No. 2510783, 2935818, 29709
Typical examples include polyvinyl fluoride, polyvinylidene fluoride, vinyl fluoride copolymer, and vinylidene fluoride copolymer described in No. 88 and the like.

The thermoplastic acrylic resin is a polymer of an alkyl ester having 1 to 8 carbon atoms of acrylic acid or methacrylic acid, or a polymer thereof and an alkyl ester of acrylic acid, methacrylic acid, hydroxyethyl acrylic acid, an alkyl ester of hydroxyethyl methacrylic acid, styrene, acrylonitrile, etc. A copolymer with a weight average molecular weight of 100,000 to 300,000 is suitable.

In addition, the mixing ratio of fluorocarbon resin and thermoplastic acrylic resin is (100:20-60) in terms of solid content weight.
If the amount of the acrylic resin is more than the above range, the weather resistance of the resulting coating will be reduced, and if it is less than the above range, the coating workability will be poor, and cracks will easily occur in the resulting coating, which is not preferable.

The coloring pigments include various inorganic and organic coloring pigments that are commonly used as coloring pigments for paints, such as titanium oxide, iron oxide, yellow lead, carbon black, calcined metal oxides, phthalocyanine blue, isoindolinone yellow, and quinacridone red. Color pigments can be used without particular restrictions.

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

The silane coupling agent includes vinyltrichlorosilane, vinyltriethoxysilane, T-methacryloxypropyltrimethoxysilane, T-glycidoxypropyltrimethoxysilane, T-glycidoxypropylmethyljethoxysilane, and T-aminopropyltriethoxysilane. Typical examples include silane, N-phenyl-T-aminopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane. The silane coupling agent is added in order to form a ground coat film with good adhesion to the primer film, and also to improve transferability of a coating material forming a patterned film, which will be described later.

The colored coating material forming the ground coat film used in the present invention is a coating material containing the above-mentioned components as essential components, and the blending ratio is 100 parts by weight of the binder to 10 parts by weight of the colored pigment.
Appropriate proportions include ~100 parts by weight of the organic solvent, 100 to 250 parts by weight of the organic solvent, and 0.1 to 10 parts by weight of the silane coupling agent.

The amount of organic solvent varies depending on the coating method, etc., but in the case of spray coating, for example, the appropriate amount is such that the viscosity at the time of coating is Ford Cup No. 4 (20° C.) for 10 to 30 seconds.

The coating material that forms the pattern film used in the present invention has almost the same composition as the colored coating material that forms the ground coat film described above, except that it does not contain a silane coupling agent as an essential component and a viscosity imparting agent is added. use.

The tackifying agent is added to improve printing characteristics (transferability) and to enable the clear coating agent described below to be applied over and over again in a wet/wet method without causing bleeding or other problems. Immediately after, the organic solvent evaporates and the binder 1 is added so that it immediately shows thixotropy.
It is appropriate to add about 0.1 to 10% by weight per 00 parts by weight.

As the tackifier, the same ones used in the primer can be used.

The clear coating material that forms the clear film used in the present invention is obtained by removing the colored pigment from the colored coating material forming the ground coat film described above, or by adding a small amount of the colored pigment to an extent that does not impair transparency. Similar coating materials can be used except that the silane coupling agent is not an essential component.

Next, a method for forming a patterned film according to the present invention will be explained.

First, in the (1) step, the above-mentioned primer is applied to the surface of the aluminum material, which has been surface-treated by chemical conversion coating treatment, alumite treatment, etc., by means such as spraying or a roll coater so that the dry film thickness is 5 to 10 μm, and the primer is coated at room temperature. Set it for several minutes or more.

In the second step, the above-mentioned colored coating material is applied onto the primer film by the same means so that the dry film thickness is 10 to 40 μm.

In the third step, the obtained primer film and ground coat film are baked at 150 to 250° C. for 10 to 40 minutes to simultaneously cure both films.

In the (4) step, the above-mentioned coating agent is printed or applied on the entire surface of the ground coat film or at any desired location using printing means such as gravure offset printing or application means such as spraying so that the dry film thickness is 1 to 5 μm. , forming a patterned film and setting at room temperature for several minutes or more.

In the (5) step, the entire surface including the patterned coating is coated to a dry film thickness of 3 to 30 μm by means of spraying, roll coater, or the like.

Next, in step (6), the patterned film and clear film obtained are baked at usually 150 to 250°C for 10 to 40 minutes to simultaneously cure both films, thereby forming the patterned film of the present invention.

<Effects of the Invention> Since the method for forming a patterned film of the present invention uses a binder containing a fluorocarbon resin as its main component, it has improved weather resistance and other properties compared to the film obtained by the conventional method for forming a patterned film on aluminum materials. The durability of the film is improved by several steps, and a 4-coat, 2-bake method becomes possible, shortening the baking process and saving energy, making it a method with high practical value.

<Examples> Hereinafter, the present invention will be explained in more detail with reference to Examples. In the examples, "parts" and "%" are expressed on a weight basis.

[Preparation of primer A]

Epoxy resin face [“Epicron H3O345” (
Dainippon Ink Chemical Industry Co., Ltd. (product name), weight average molecular weight 3
50 parts of amino resin face [Beccamin P138J (trade name manufactured by Dainippon Ink and Chemicals Co., Ltd.), solid content 60%] and 55% methyl ethyl ketone of hexamethylene diisocyanate-based blocked polyisocyanate. A binder solution consisting of 2 parts titanium dioxide, 8 parts barium sulfate, and 0.5 parts white carbon.
parts, organic bentonite 0.5 parts, xylene 10.5 parts,
Mix 14 parts of methyl isobutyl ketone to give a chichira coefficient of 3.
．． By 0CB type viscometer (6r, pom, viscosity) /
(60r, plm, viscosity) ratio (25°C)] was prepared, and before coating, a (1:1) mixed solvent of xylene and methyl ethyl ketone was added to the Ford Cup Nα viscosity.
4 (25°C) for 20 seconds to prepare Primer A.

[Preparation of colored paint A]

Vinylidene fluoride resin varnish [Kynar #500J (
16 parts of titanium dioxide and silane coupling were added to a binder solution consisting of 43 parts of ethyl acrylate-methacrylic acid copolymer varnish (product name manufactured by Nihon Pennwalt Co., Ltd.), solid content 50%] and 22 parts of ethyl acrylate-methacrylic acid copolymer varnish (solid content 40%). 1 part of agent, 9 parts of xylene,
Mix 9 parts of methyl isobutyl ketone, and then apply before painting.
Colored paint A was prepared by adding a mixed solvent of xylene and methyl ethyl ketone (1:1) to give a viscosity of 15 seconds.

[Preparation of colored paint B]

Colored paint B was prepared in the same manner as colored paint A except that the silane coupling agent was removed.

[Preparation of ink A]

1 part of titanium dioxide is added to a binder solution consisting of 40 parts of the vinylidene fluoride resin varnish mentioned above and 20 parts of the copolymer face mentioned above.
6 parts, calcined metal oxide [Dipyroxide 9550J
(trade name manufactured by Dainichiseika Kagyo Co., Ltd.)], kneaded and dispersed, added 1 part of white carbon as a viscosity imparting agent, and polyethylene paste ["Disparon 4200-2 (IJ
(Product name manufactured by Suisui Kasei Co., Ltd.)] 11 parts, xylene 10 parts, and methyl isobutyl ketone 10 parts to give a chicken coefficient of 6.0, and then immediately before printing, add a mixed solvent of xylene and methyl ethyl ketone (1: 1). Ink A was prepared by adding the mixture to a viscosity of 35 seconds.

[Preparation of ink B]

Ink B without thixotropy was prepared in the same manner as ink A except that the viscosity imparting agent was removed.

[Preparation into clear paint]

Add 6 parts of xylene to a binder solution consisting of 58 parts of the vinylidene fluoride resin varnish described above and 30 parts of the copolymer varnish described above.
Mix 6 parts of methyl isobutyl ketone and then apply before painting.
A mixed solvent of xylene and methyl ethyl ketone (1:1) was added to give a viscosity of 15 seconds to prepare a clear paint.

Examples 1 to 2 and Comparative Examples 1 to 3 A pattern film was formed on the surface of an aluminum material that had been subjected to a chromate conversion coating treatment and an alumite treatment in the steps shown in Table 1.

The primary adhesion, secondary adhesion, salt spray resistance, and
Tests were conducted on castability, accelerated weather resistance, ink transferability, and ink bleedability, and the results are shown in the lower part of Table 1.

As is clear from Table 1, the patterned coating 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 no silane coupling agent was added as the colored paint for forming the ground coat film, the secondary adhesion was poor and the ink transferability was also poor.

Furthermore, in Comparative Example 2 in which an ink without thixotropy was used, the transferability of the ink was poor and bleeding of the ink also occurred.

Furthermore, in Comparative Example 3 using the conventional method, not only the baking process was increased (weather resistance was very poor).

Claims (6)

[Claims] (1) A step of applying a thixotropic primer using an epoxy resin and its curing agent as a binder to the surface of the surface-treated aluminum material to form a primer film; (2) Coloring on the primer film using a mixed resin of a fluorocarbon resin and a thermoplastic acrylic resin in a mixing ratio (solid content weight) [100:20-60] as a binder and a silane coupling agent added. A process of applying a coating agent and forming a ground coat film, (3) baking and curing the primer film and ground coat film; (4) A colored coating material showing thixotropy, which uses as a binder a mixed resin consisting of a fluorocarbon resin and a thermoplastic acrylic resin in a mixing ratio (solid content weight) [100:20-60] on the ground coat film. The process of printing or coating to form a patterned film, (5) Mixing ratio of fluorocarbon resin and thermoplastic acrylic resin on the patterned film (based on solid content weight)
100:20-60] coating a clear coating agent using a mixed resin as a binder to form a clear coating; (6) A method for forming a patterned film on an aluminum material, comprising the steps of baking and curing the patterned film and clear film.