JP2011115686A - Method for forming coating film and coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an anodized coating formed on the surface of aluminum or aluminum alloy part and an anticorrosive primer coating film formed on the anodized coating, and a coating film composed of a top coat and excellent in adhesion with coating film and having excellent corrosion resistance, and to provide a coating film thereof. <P>SOLUTION: The method for forming an anodized coating on the surface of aluminum or aluminum alloy part includes anodizing aluminum or aluminum alloy part, forming an anticorrosive primer coating film by coating the anticorrosive primer on the anodized coating, and forming a top coat by coating a top coat on the anticorrosive primer coating film if required, wherein the anticorrosive primer has a substrate resin composed of hydroxyl group containing epoxy resin, a curing agent selected from melamine resin and polyisocyanate, and barium sulfate, and the percentage of the barium sulfate is 20-70 pts.mass to the total 100 pts.mass of the solid content of the substrate resin and curing agent. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a method for forming a coating film on the surface of an aluminum or aluminum alloy part and a coating film obtained by the method for forming the coating film.

Aluminum or aluminum alloy is used in some parts such as outboard motors. In recent years, aluminum or aluminum alloys are used in automobile parts to reduce the weight of automobiles.
Aluminum or aluminum alloy parts for outboard motors constitute part of the engine and drive system that is the power source of the ship, and it is necessary to protect the engine from heat, water, seawater, light, etc. Corrosion resistance is required. Further, high corrosion resistance is also required for aluminum or aluminum alloy parts for automobiles due to the influence of a snow melting agent or the like.

As a method of improving the corrosion resistance of aluminum or aluminum alloy parts, a method of applying an epoxy resin paint containing a chromium-based anticorrosive pigment as an anticorrosive primer has been widely used. However, a chromium-based anticorrosive pigment has an adverse effect on the environment. Since it contains chromium, which has a risk of causing rust, a method for coating a rust preventive primer containing a rust preventive pigment not containing chromium has been developed.
However, the method of applying a rust preventive primer containing a rust preventive pigment not containing chromium has a problem that the corrosion resistance is inferior to the method of applying a rust preventive primer containing a chromium-based rust preventive pigment.

On the other hand, as a method for enhancing the corrosion resistance of aluminum or aluminum alloy parts, a method of anodizing the surface of aluminum or aluminum alloy parts is also widely used, but the corrosion resistance is not sufficient only by anodizing treatment, and after anodizing treatment Sealing processing is performed (for example, refer to Patent Document 1).
However, when the sealing treatment is performed after the anodizing treatment, the corrosion resistance is improved, but the adhesion between the anodized film formed on the surface of the aluminum or aluminum alloy part by the anodizing treatment and the coating film formed thereon is improved. There was a problem that decreased. This problem is considered to be caused by the dissolution of the coating film, the sealing treatment component, and the like in the sealing treatment performed after the anodizing treatment and, in some cases, the subsequent degreasing and / or chemical conversion treatment.

On the other hand, as a ship anticorrosive paint having corrosion resistance, a ship comprising a light-transmitting inorganic filler selected from talc, mica, silica, potassium feldspar, or barium sulfate, and an epoxy resin and a curing agent for epoxy resin such as polyamide or polyamine. An anticorrosive coating composition is known (for example, see Patent Document 2). However, when this coating composition was applied to the anodized film of aluminum or aluminum alloy parts, the corrosion resistance of the obtained coating film was not sufficient.

Further, as a method for improving the corrosion resistance of a metal material, a phosphate chemical compound having a pH of 2.5 to 3.5 containing phosphate ion, chlorate ion, nitrate ion, bromate ion and 200 to 800 ppm of zirconium hexafluoride ion is used. It is known to apply a thermosetting aqueous coating composition containing barium sulfate or talc as an extender pigment on a metal material treated with a treatment liquid (see, for example, Patent Document 3). However, when this thermosetting water-based coating composition is applied to the anodized film of aluminum or aluminum alloy parts, the corrosion resistance of the obtained coating film is not sufficient.

In addition, it has both rust prevention and aesthetics, and it can be used as a base coat, intermediate coat, and top coat with a single coating. As a thermosetting paint used in the coating method, it contains barium sulfate and calcium carbonate, alkyd resin 30 to 45% by weight, melamine resin 5 to 20% by weight, epoxy resin and rust preventive pigment 0.2 to 1.5% by weight There is known a thermosetting paint characterized in that it contains (see, for example, Patent Document 4). However, when this thermosetting coating composition is applied to an anodized film of aluminum or an aluminum alloy part, the corrosion resistance of the obtained coating film is not sufficient.

(A) (meth) acrylic acid ester resin emulsion, styrene / acrylic acid ester copolymer emulsion, vinyl acetate resin emulsion, vinyl acetate / (meth) acrylic acid ester copolymer emulsion, urethane resin emulsion, A synthetic resin component consisting of one or more selected from ethylene / vinyl acetate copolymer emulsion, polyester resin, and aqueous epoxy resin, and (B) titanium, talc, kaolin, bentonite, mica, silica, heavy carbonic acid A filler component consisting of one or more selected from calcium, clay, precipitated barium sulfate, barium carbonate, glass beads, and resin beads, and (C-1) specific acetylene glycol and / or specific acetylene glycol 10 to 95% by mass of ethoxylated product of C-2) polyoxy (metal coating material such as galvanized steel sheet, which comprises ethylene-propylene) mixture components of the block polymer 5 to 90% by weight is known (e.g., see Patent Document 5). However, when this metal coating composition is applied to the anodized film of aluminum or aluminum alloy parts, the resulting coating film has insufficient corrosion resistance.

In addition, as a thermosetting aqueous composition for metal coating, as an essential film-forming component, a saturated carboxylic acid or derivative thereof; an ethylenically unsaturated carboxylic acid or derivative thereof; a carboxylic acid having an aromatic ring or derivative thereof; Modified epoxy obtained by reacting an epoxy resin with at least one carboxylic acid selected from the group consisting of acids or derivatives thereof, at least two compounds having a hydroxyl group bonded to a phosphorus atom in one molecule Except for the resin (a), the modified epoxy resin (a), a water-soluble or water-dispersible resin (b), an aminoplast resin; a phenoplast resin and a block isocyanate resin, at least A thermosetting aqueous composition for metal coating, comprising one curing agent (c). Known (e.g., see Patent Document 6). However, this thermosetting aqueous composition for metal coating was not sufficient in corrosion resistance of the obtained coating film under severe immersion test conditions.

JP 2004-60044 A JP 2000-037658 A JP 2003-10774 A JP 2003-313492 A JP 2008-063472 A JP 08-325509 A

The present invention provides adhesion between an anodized film formed on the surface of an aluminum or aluminum alloy component, and a rust preventive primer film formed on the anodized film and, if necessary, a film comprising a top coat film. An object of the present invention is to provide a method of forming a coating film having excellent corrosion resistance and excellent corrosion resistance and a coating film obtained by the method of forming the coating film.

The present inventors have made a specific primer coating in which a specific amount of barium sulfate is blended in an anodized film formed on the surface of an aluminum or aluminum alloy part by anodizing an aluminum or aluminum alloy part and, if necessary, an overcoat. The present inventors have found that the above-mentioned problems can be solved by sequentially applying paints and forming a coating film, thereby completing the present invention.

That is, the present invention comprises anodizing an aluminum or aluminum alloy part to form an anodized film on the surface of the aluminum or aluminum alloy part, and coating the rust preventive primer on the anodized film to prevent the rust primer film In the method of forming a top coat film by applying a top coat on the rust preventive primer coat as necessary, the rust preventive primer comprises a base resin comprising a hydroxyl group-containing epoxy resin, a melamine resin, and a polymer. It contains a curing agent selected from isocyanate and barium sulfate, and the content ratio of the barium sulfate is a ratio of 20 to 70 parts by mass with respect to 100 parts by mass of the total amount of solids of the base resin and the curing agent. A method of forming a characteristic coating film is provided.

Moreover, this invention provides the formation method of the coating film in which the said anodizing process is performed in dilute sulfuric acid in the formation method of the said coating film.
Moreover, this invention provides the formation method of the coating film in which the anodic oxide coating which coats the said rust preventive primer is sealing-processed in the formation method of the said coating film.
Moreover, this invention provides the coating film obtained by the formation method of one of said coating films.

The coating film of the present invention comprises an anodized film formed on the surface of an aluminum or aluminum alloy part by anodizing an aluminum or aluminum alloy part, a rust preventive primer film formed on the anodized film, and a necessity Accordingly, it has excellent adhesion to a coating film composed of a top coating film, and also has excellent corrosion resistance.

FIG. 1 is a schematic view of an example of an electrolysis apparatus used for anodizing treatment.

The aluminum or aluminum alloy part used in the present invention is not particularly limited and includes various parts. Examples thereof include ADC12 and ADC10 which are aluminum die casts, AC material which is an aluminum casting material, and aluminum exhibition. Examples thereof include drawn materials.
The types of components of the aluminum alloy are not particularly limited, and examples include aluminum / magnesium alloys, aluminum / magnesium / silicon alloys, aluminum / copper alloys, and aluminum / zinc / magnesium alloys. Can be mentioned.
The shape of the aluminum or aluminum alloy part is not particularly limited, and various shapes such as a plate and a rod can be mentioned.

In the present invention, aluminum or aluminum alloy parts are anodized.
The anodic oxide coating treatment is preferably performed in a bath of dilute sulfuric acid, oxalic acid, phosphoric acid, chromic acid, more preferably a dilute sulfuric acid bath or an oxalic acid bath, and particularly preferably a dilute sulfuric acid bath. These baths may be used alone or in combination of two or more, but are preferably used alone.
The electrolyte concentration in each bath is preferably 1 to 20% by volume, and more preferably 2 to 15% by volume. In particular, the sulfuric acid concentration in the dilute sulfuric acid bath is preferably 6 to 14% by volume, and more preferably 8 to 12% by volume.
The temperature of the anodizing treatment is usually preferably 1 to 40 ° C, more preferably 5 to 30 ° C, and particularly preferably 10 to 25 ° C.

The anodizing treatment can be performed using various apparatuses. An example is shown in FIG.
The apparatus shown in FIG. 1 is an electrolytic apparatus for anodizing treatment composed of an electrolytic cell 2, a pair of cathode plates 3, an anode transmission line 4, a cathode transmission line 5, and a power source 6. The aluminum alloy part 1 can be attached. This electrolysis apparatus has a DC power supply 61 that performs DC electrolysis as a constituent element, but is not limited to a DC power supply, and AC electrolysis using an AC power supply as a power supply, or AC / DC weight electrolysis using a combination of DC and AC. Can also be done.

In the present invention, an anodized film is formed on the surface of the aluminum or aluminum alloy part by anodizing the aluminum or aluminum alloy part.
This anodized film may be subjected to sealing treatment, or may be subjected to subsequent degreasing and / or chemical conversion treatment.
Sealing treatment is performed by immersing a metal hydrate and metal oxide sol as a main component in a sealing agent bath, applying a metal hydrate and metal oxide sol as a main component by spraying a sealing agent, It can be carried out by electrolytic treatment with a sealing agent with a metal hydrate and metal oxide sol as the main component, or a combination thereof.

As metals in metal hydrate and metal oxide sols, aluminum, silicon, zinc, tin, chromium, molybdenum, nickel, cobalt, copper, titanium, zircon, yttrium, antimony, indium, calcium, germanium, strontium, vanadium, Examples include tantalum, neodymium, magnesium, and barium.
The sealing treatment can also be performed by a normal steam method such as a pure water boiling water method.
Degreasing can be performed by a known method such as immersing in various degreasing agents. As the degreasing agent, a known degreasing agent such as an alkaline degreasing agent can be used.
The chemical conversion treatment can be performed by a known method such as immersion in various chemical conversion treatment agents. As the chemical conversion treatment agent, a known chemical conversion treatment agent such as a chromium-based chemical conversion treatment agent can be used.

The anodized film is a film containing an aluminum oxide as a main component, and is a film containing a metal hydrate, a hydrated oxide, or the like by sealing treatment, degreasing and / or chemical conversion treatment. May be.
Although the thickness of an anodized film is not specifically limited, Usually, 3-30 micrometers is preferable, 4-20 micrometers is more preferable, and 5-18 micrometers is especially preferable.

In the present invention, a rust preventive primer coating is formed by coating a rust preventive primer on the anodized film formed on the surface of the aluminum or aluminum alloy part.
In the present invention, the rust preventive primer contains a base resin composed of a hydroxyl group-containing epoxy resin, a curing agent selected from melamine resin and polyisocyanate, and barium sulfate, and the content of the barium sulfate is the base resin and the curing agent. It is a rust preventive primer which is 20-70 mass parts with respect to 100 mass parts of total amounts of solid content.

The hydroxyl group-containing epoxy resin that is the base resin is not particularly limited, and examples thereof include alkyd, polyester, polyether, acrylic, urethane, and the like, which are glycidyl etherified epoxy resins such as bisphenol A, bisphenol F, or novolak. Modified epoxy resin modified with These hydroxyl group-containing epoxy resins can be used alone or in combination of two or more.
Although the hydroxyl value of a hydroxyl-containing epoxy resin is not specifically limited, Usually, 30-250 mgKOH / g is preferable, 60-210 mgKOH / g is more preferable, 90-190 mgKOH / g is further more preferable. When the hydroxyl value of the hydroxyl group-containing epoxy resin is less than 30 mgKOH / g, corrosion resistance and adhesion may be deteriorated. If it is larger than 250 mgKOH / g, the water resistance may be lowered.

Although the weight average molecular weight of a hydroxyl-containing epoxy resin is not specifically limited, Usually, 6000-30000 are preferable, 7000-25000 are preferable, and 9000-20000 are more preferable. When the weight average molecular weight of the hydroxyl group-containing epoxy resin is less than 6000, corrosion resistance and adhesion may be deteriorated. When it is larger than 30000, the viscosity becomes high and it may be difficult to form a paint. In the present invention, the weight average molecular weight is a value obtained by converting the weight average molecular weight measured by gel permeation chromatography (GPC) on the basis of the weight average molecular weight of polystyrene.
The base resin may contain a base resin other than the hydroxyl group-containing epoxy resin within a range not contrary to the object of the present invention. Other base resins include unmodified epoxy resins, alkyd resins, polyester resins, acrylic resins, urethane resins and the like. The content of the other base resin is preferably 40% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less with respect to the total amount of the base resin.

As the melamine resin which is one kind of curing agent, various materials can be used as long as they function as a curing agent for the epoxy resin. As the melamine resin, for example, methyl etherified melamine resin, butyl etherified melamine resin or mixed alkyl etherified melamine resin can be used. These melamine resins can be used alone or in combination of two or more.

As the polyisocyanate which is one kind of the curing agent, various ones can be used as long as they function as a curing agent for the epoxy resin. Examples of the polyisocyanate include aliphatic polyisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, and 1,3-butylene diisocyanate. Or a polymer of these mixtures, a cycloaliphatic polyisocyanate such as 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 1,2-cyclohexane diisocyanate, isophorone diisocyanate or a mixture of these, 2,4- Toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, m-xylylene diisocyanate DOO, polymer of p- aromatic such as xylylene diisocyanate polyisocyanates or mixtures thereof can be mentioned.

The content ratio of the base resin and the curing agent may be a normal content ratio. When the curing agent is a melamine resin, the mass ratio of the base resin and the melamine resin is preferably 50/50 to 90/10 in terms of solid content. Yes, more preferably 55/45 to 85/15, and particularly preferably 60/40 to 80/20. If the mass ratio of the melamine resin is more than 50/50 in terms of solid content, adhesion or paint stability may be reduced. If it is less than 90/10, corrosion resistance and adhesion may be reduced. When the curing agent is a polyisocyanate, the molar ratio of the functional group of the base resin to the isocyanate group of the polyisocyanate is preferably 3: 1 to 1: 3, more preferably 1.5: 1 to 1: 2. When the molar ratio of the isocyanate group of the polyisocyanate is less than 3: 1, the corrosion resistance may be lowered. If it is more than 1: 3, the adhesion may be lowered.

Barium sulfate used for the rust preventive primer is not particularly limited. For example, barium sulfate SS-50 manufactured by Sakai Chemical Industry Co., Ltd., precipitated barium sulfate # 100, Variace B-30, Varifine BF-1, Commercial products such as Fine BF-10 can be mentioned.
The content ratio of barium sulfate in the rust preventive primer is a ratio of 20 to 70 parts by mass, more preferably 25 to 60 parts by mass with respect to 100 parts by mass of the total amount of the solid content of the base resin and the curing agent. The ratio is particularly preferably 30 to 45 parts by mass. When the content ratio of barium sulfate is less than 20 parts by mass with respect to 100 parts by mass of the solid content of the base resin and the curing agent, the adhesion to aluminum or aluminum alloy parts is reduced, and sufficient corrosion resistance is obtained. I can't get it. Moreover, when the content rate of barium sulfate exceeds 70 mass parts with respect to 100 mass parts of solid content of the said base resin and the said hardening | curing agent, barium sulfate will precipitate and the stability of an antirust primer coating will fall. There is a case.

In addition to the above-mentioned coating film-forming resin and barium sulfate, the rust-preventing primer, if necessary, within the range of content that does not impede practical use, is a rust-preventing pigment, extender pigment, colored pigment, anti-settling agent, coating surface It can contain a conditioner, other paint additives, organic solvents, and the like.
The rust preventive pigment is not particularly limited. For example, tetrabasic zinc chromate, basic zinc potassium chromate, strontium chromate, basic lead chromate, calcium chromate, barium chromate, lead oxide , Basic lead sulfate, calcium lead acid, lead cyanamide, zinc phosphate, calcium phosphate, magnesium phosphate, aluminum phosphate, magnesium tripolyphosphate, aluminum tripolyphosphate, aluminum calcium tripolyphosphate, zinc aluminum tripolyphosphate, zinc molybdate, molybdenum Examples thereof include calcium oxide, zinc calcium molybdate, zinc phosphomolybdate, calcium phosphomolybdate, and zinc aluminum phosphomolybdate.

The extender pigment is not particularly limited, and examples thereof include hydrous aluminum oxalate, hydrous magnesium oxalate, and silica powder. The amount of the extender is preferably 40 parts by mass or less and more preferably 20 parts by mass or less with respect to 100 parts by mass of barium sulfate.
The coloring pigment is not particularly limited. For example, inorganic pigments such as titanium oxide, carbon black, yellow iron oxide, bismuth vanadate, ultramarine blue, azo, metal complex, condensed polycyclic, phthalocyanine And organic pigments such as

The rust preventive primer is preferably an organic solvent type rust preventive primer.
As the organic solvent used for the organic solvent-type rust preventive primer, various organic solvents that are usually used in paints can be applied. For example, aromatic hydrocarbon solvents, alicyclic hydrocarbon solvents, ketone solvents, alcohols Examples thereof include an organic solvent, an ester solvent, an ether solvent, and a nitrogen-containing solvent, and an aromatic hydrocarbon solvent, an alcohol solvent, an ester solvent, or a mixture of two or more of these is preferable.
Preferred examples of the aromatic hydrocarbon solvent include toluene, xylene, ethylbenzene, aromatic naphtha and the like. Preferred examples of the alicyclic hydrocarbon solvent include cyclohexane and ethylcyclohexane. Preferred examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone. Preferable examples of the alcohol solvent include methyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, and 2-ethylhexyl alcohol.

Examples of ester solvents include aliphatic carboxylic acid alkyl esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, and ethyl propionate, and alkoxy aliphatic carboxylic acids such as 3-methoxybutyl acetate and ethyl-3-ethoxypropionate. Preferred examples include ethylene glycol aliphatic carboxylic acid esters such as acid esters and cellosolve acetate, propylene glycol monoalkyl ether aliphatic carboxylic acid esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol monopropyl ether acetate. It is done. Preferred ether solvents include butyl cellosolve, dibutyl ether, tetrahydrofuran, 1,4-dioxane, 1,3,5-trioxane and the like. Preferred examples of the nitrogen-containing solvent include acetonitrile, valeronitrile, N, N-dimethylformamide, N, N-diethylformamide and the like. The organic solvent may be one kind alone or a mixed solvent of two or more kinds of plural solvents.

The anti-corrosion primer can be heated as necessary, adjusted to the desired viscosity by adding an organic solvent or reactive diluent, and then applied to air spray, airless spray, rotary atomizer-type coating machines, etc. Electrostatic coating or non-electrostatic coating is performed using a commonly used coating machine. Of these, spray coating is preferred.
It is preferable to bake the rust preventive primer coating film. What is necessary is just to select a baking temperature suitably in the range of 80-160 degreeC normally. Furthermore, what is necessary is just to select baking time normally in the range for 10 to 60 minutes. The thickness of the rust-preventing primer coating formed by coating the rust-preventing primer is not particularly limited, but usually the dry film thickness is preferably 10 to 80 μm, more preferably 15 to 60 μm, and more preferably 20 to 20 μm. 40 μm is particularly preferable.

In the present invention, it is preferable to form a top coat by coating a top coat on the rust preventive primer coat.
The top coat in the present invention is not particularly limited, and examples thereof include a normal top coat composed of a film-forming resin and a curing agent, and may be a solid color paint or a metallic paint. If necessary, an overcoat paint may be further applied on the coating film formed by applying the solid color paint or the metallic paint. The top coating applied on the solid color coating or metallic coating may be a clear coating or a colored coating containing a colorant such as a pigment.

Various resin paints can be used as the solid color paint, and examples thereof include acrylic / melamine paints, alkyd / melamine paints, polyester / melamine paints, and polyurethane paints. The paint used as the metallic paint is the same as the solid color paint, and examples thereof include acrylic / melamine paint, alkyd / melamine paint, polyester / melamine paint, polyurethane paint and the like. Examples of the paint used as the clear paint and the colored paint include acrylic / melamine paints, polyester / melamine paints, polyurethane paints, and acid / epoxy paints.

The top coating is usually heated, if necessary, or adjusted to the desired viscosity by adding an organic solvent or a reactive diluent, and is usually used for air spray, airless spray, rotary atomizer-type coating machines, etc. Electrostatic coating or non-electrostatic coating is performed using the coating machine used. Of these, spray coating is preferred.
When a clear paint or colored paint is applied on a solid color coating or metallic paint, the clear paint or colored paint may be applied after baking the solid color coating or metallic paint. Alternatively, before baking the metallic coating film, a clear paint or a colored paint may be applied in a wet-on-wet manner and simultaneously baked and cured.

What is necessary is just to select the baking temperature of top coat normally in the range of 70-160 degreeC normally. Furthermore, what is necessary is just to select baking time normally in the range for 10 to 60 minutes. The thickness of the top coat film formed by applying the top coat is not particularly limited, but usually the dry film thickness is preferably 10 to 70 μm, more preferably 15 to 50 μm. Moreover, when a top coat film is two or more layers, the thickness of each layer should just make the dry film thickness into the thickness of the said top coat film, respectively.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples. In the examples, “parts” means “parts by mass” unless otherwise specified, and “%” regarding the blending amount and content means “% by mass”.

(Rust prevention primer production example)
Production of antirust primer paint (PR-1) Alkyd-modified epoxy resin (hydroxyl value 150 mgKOH / g, acid value 30 mgKOH / g, weight average molecular weight 18000, solid content 60%, propylene glycol monomethyl ether acetate, manufactured by BASF Coatings Japan 21 parts of ethyl-3-ethoxypropionate mixed solution), 10 parts of barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd., trade name “SS-50”), anticorrosive pigment (manufactured by Societe Novele des Coutures Zinciques, trade name “Strontium”) Chromate L203E ") 4 parts, black pigment (Columbia Carbon Co., Ltd., trade name" Raven 1255 ") 0.3 parts, white pigment (DuPont, trade name" Typure R-900 ") 10 parts, additive (element Product name made by Tis Japan “Benton 34”) 0.3 parts and solvent 13.4 parts were mixed by a conventional method and dispersed to 10 μm or less, and then 10.5 parts of alkyd-modified epoxy resin manufactured by BASF Coatings Japan Co., Ltd., epoxy resin (Japan Epoxy) Resin Co., Ltd., trade name “jER1009” 40 mass% xylene, butyl alcohol, propylene glycol monomethyl ether acetate mixed solution 7 parts, melamine resin (Mitsui Chemicals, trade name “Uban 225”, solid content 60 mass%) An organic solvent-type antirust primer coating PR-1 was produced by mixing with 12 parts of propylene glycol monomethyl ether acetate, 11.5 parts of xylene and butyl alcohol mixed solvent.

Production of rust preventive primer paint (PR-2 to 11) Using the components fried in Table 1 and Table 2, in the same manner as the production of rust preventive primer paint PR-1, rust preventive primer PR-2 to 11 was produced.
However, in the rust preventive primer PR-8, the solvent is changed to a mixed solvent of toluene and propylene glycol monomethyl ether acetate, and a polyisocyanate compound (manufactured by Sumika Bayer Urethane Co., Ltd., trade name “ Sumidur N-3300 ") was mixed and used immediately before use.

Moreover, stability was evaluated by the method shown below about the obtained antirust primer coating material.
Evaluation of Stability of Rust Preventive Primer Paint The stability of the rust preventive primer paint was evaluated by visually observing the state of the paint when left at room temperature for 2 weeks and according to the following criteria. The results are shown in Tables 1 and 2.
Criteria for evaluating the stability of paint ◎: No settling.
○: Slightly settled but recovers easily when stirred.
(Triangle | delta): It has settled, but it recovers, when it stirs.
X: It has settled. No recovery after stirring.

The subscripts in the explanatory tables of Table 1 and Table 2 have the following meanings, respectively.
1) Alkyd-modified epoxy resin solution manufactured by BASF Coatings Japan, solid content 60% by mass, hydroxyl value 150 mgKOH / g, weight average molecular weight 18000,
2) H201-60BT manufactured by DIC Corporation, trade name: “Epiclon H201-60BT”, polyol type epoxy resin, solid content 60 mass%, hydroxyl value 120 mg KOH / g, weight average molecular weight 10,000, toluene, methyl isobutyl ketone mixed solution,
3) SS-50, manufactured by Sakai Chemical Industry Co., Ltd., trade name: “SS-50”, barium sulfate,
4) B-30 manufactured by Sakai Chemical Industry Co., Ltd., trade name: “B-30”, barium sulfate,
5) L203E Society Noveles des Coutures Zinciques, trade name: “Strontium chromate L203E”, strontium chromate,
6) PM300C, manufactured by Kikuchi Color Co., Ltd., trade name: “LF Bowsey PM300C”, aluminum zinc phosphomolybdate,

7) R1255 Made by Columbia Carbon Co., Ltd., trade name: “Raven 1255”, carbon black,
8) R-900 manufactured by DuPont, trade name: “Tai Pure R-900”, titanium oxide,
9) High filler # 12 Made by Matsumura Sangyo Co., Ltd., trade name: “High filler # 12”, talc,
10) R972 manufactured by Nippon Aerosil Co., Ltd., trade name: “Aerosil R972”, silica,
11) Benton 34 manufactured by Elementis Japan, trade name: “Benton 34”, tetraalkylammonium bentonite,
12) jER1009 solution, manufactured by Japan Epoxy Resin Co., Ltd., trade name: “jER1009” 40 mass% xylene, butyl alcohol, propylene glycol monomethyl ether acetate mixed solution,
13) U225, manufactured by Mitsui Chemicals, trade name: “Uban 225”, butylated melamine resin, solid content 60%, xylene, methyl alcohol, butyl alcohol mixed solution,
14) N-3300 manufactured by Sumika Bayer Urethane Co., Ltd., trade name: “Sumijour N-3300”, isocyanurate of hexamethylene diisocyanate (HDI), NCO group content 21.8% by mass, solid content 100% by mass,

(Anodized film treatment example)
Adjustment of anodized film-treated aluminum alloy part (AL-1) 10% by volume of an outboard motor part (gear case, 240 × 265 × 100 mm) made of ADC12 using the anodizing electrolytic apparatus shown in FIG. It was immersed in a 20 ° C. treatment tank filled with sulfuric acid and anodized by a direct current electrolysis method to form an anodized film of 13 to 15 μm. In the treatment bath, a direct current voltage of 35 V was applied and energized for 15 minutes to perform anodization. Then, it was immersed in a 90 ° C. solution in which a commercially available sealing agent (product name: “Top Seal”) was dissolved for 15 minutes, sealed, washed with water, and dried.

Adjustment of anodized aluminum alloy part (AL-2) An outboard motor part (housing) made of AC4B material was filled with 10% by volume sulfuric acid using the anodizing electrolytic apparatus shown in FIG. It was immersed in a treatment bath at 0 ° C. and anodized by a direct current electrolysis method to form a 13 to 15 μm film. In the treatment bath, a direct current voltage of 35 V was applied and energized for 15 minutes to perform anodization. Then, it was immersed in a 90 ° C. solution in which a commercially available sealing agent (product name: “Top Seal”) was dissolved for 15 minutes, sealed, washed with water, and dried.

Preparation of anodized film treated aluminum part (AL-3) An automotive part (lower case) made of an aluminum wrought material was used to prepare a 3% by volume oxalic acid aqueous solution using the anodizing electrolytic apparatus shown in FIG. Was immersed in a treatment bath at 30 ° C. and anodized by a direct current electrolysis method to form a film of about 15 μm. In the treatment bath, a 30 V DC voltage was applied and energized for 20 minutes to perform anodization. After that, it was sealed with a pure water boiling water method, which is a normal steam method, washed with water, and dried.

<Example 1>
The rust preventive primer PR-1 is mixed with a mixed solvent of propylene glycol monomethyl ether acetate, xylene and butyl alcohol on the anodized film of the anodized aluminum alloy part AL-1 to a dry film thickness of 25 μm. Spray coating was performed to form a rust-preventive primer coating, and baked at 130 ° C. for 20 minutes. Next, on the rust preventive primer coating, a polyurethane resin metallic paint (manufactured by BASF Coatings Japan, “High Urethane No. 5000 0EP”) is mixed with a curing agent and a diluted thinner immediately before use as a metallic paint. Then, spray coating is performed so that the dry film thickness is 15 μm, a metallic coating layer is formed, and wet-on-wet is formed on the metallic coating, and a polyurethane resin-based clear coating (BASF Coatings Japan, “High Urethane No. .5300 clear outboard motor ") was mixed with a curing agent and diluted thinner immediately before use, and spray-coated to a dry film thickness of 25 μm to form a clear coating layer, which was left at room temperature for 10 minutes. Thereafter, it was baked at 90 ° C. for 20 minutes.
The test product thus manufactured was cross-cut and subjected to an immersion test at 80 ° C. for 1 hour and 40 ° C. for 240 hours (JIS standard K5600-6-2), and then evaluated for corrosion resistance by tape peeling. As a result, high adhesion was exhibited without peeling at 20% by mass or more of barium sulfate.

<Example 2>
On the anodized aluminum alloy part AL-1, rust preventive primer PR-8 was mixed with toluene and propylene glycol monomethyl ether acetate mixed solvent, and then spray coated to a dry film thickness of 20 μm. Immediately before forming a rust-preventing primer coating layer, wet-on-wet on the rust-preventing primer coating layer, and using polyurethane resin-based metallic paint (BASF Coatings Japan, "High Urethane No. 5000 0EP") as the metallic paint After mixing with a curing agent and diluted thinner, spray coating is performed to a dry film thickness of 15 μm to form a metallic coating layer, and wet-on-wet polyurethane resin-based clear coating (BASF) is formed on the metallic coating layer. “High Urethane No. 5” manufactured by Coatings Japan 00 clear outboard motor ") was mixed with a curing agent and dilution thinner immediately before use, and spray-coated to a dry film thickness of 25 μm to form a clear coating film layer, which was left at room temperature for 10 minutes. And baked at 90 ° C. for 20 minutes. The test article thus manufactured was subjected to the same immersion test as in Example 1. As a result, it showed high adhesion without peeling.

<Examples 3 to 10, Comparative Examples 1 and 2>
The test products of Examples 3 to 10 and Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except that the components of the anodized treatment and the composition of the rust preventive primer were changed to the paints shown in Table 1. was made work was subjected to the same immersion test as in example 1.

<Examples 11 and 12>
Example 11 is basically the same as the test product produced in Example 1, except that it was degreased after anodizing. The degreasing conditions were performed at 60 ° C. for 6 minutes using an alkaline degreasing agent.
Further, Example 12 differs from Example 1 in that degreasing and subsequent chemical conversion treatment are performed. The degreasing conditions were 60 ° C. × 6 minutes using an alkaline degreasing agent, and the chemical conversion treatment was performed at 45 ° C. × 3 minutes using a chromium-based chemical conversion treating agent. After the test product was prepared, the same immersion test as in Example 1 was performed. As a result, high adhesion was exhibited without peeling.
The result of the immersion test of Examples 1-12 was shown in Table 3 and Table 4, and the result of the immersion test of Comparative Examples 1-2 was shown in Table 5.

The adhesion after the immersion test was evaluated by the following method.
Adhesion after immersion test Adhesion after the immersion test was evaluated according to the following evaluation criteria.
A: No peeling at all from the cross-cut portion due to tape peeling.
○: There is peeling of less than 2 mm from the crosscut portion due to tape peeling.
X: There is peeling of 2 mm or more from the crosscut portion due to tape peeling.

  The coated article of aluminum or aluminum alloy part on which the coating film of the present invention is formed can be used in various fields such as parts such as outboard motors and automobile parts.

DESCRIPTION OF SYMBOLS 1 Aluminum or aluminum alloy components 2 Electrolyzer 3 Cathode plate 4 Anode power wire 5 Cathode power wire 6 Power supply 61 DC power supply

Claims (4)

Anodizing the aluminum or aluminum alloy part to form an anodized film on the surface of the aluminum or aluminum alloy part, and coating the rust-preventing primer on the anodized film to form a rust-preventing primer film. Accordingly, in the method of forming a top coat by applying a top coat onto the rust preventive primer coating, the rust preventive primer is selected from a base resin composed of a hydroxyl group-containing epoxy resin, a melamine resin, and a polyisocyanate. A coating film comprising an agent and barium sulfate, wherein the content of the barium sulfate is 20 to 70 parts by mass with respect to 100 parts by mass of the solid content of the base resin and the curing agent. Forming method. The method for forming a coating film according to claim 1, wherein the anodizing treatment is performed in a dilute sulfuric acid bath. The method for forming a coating film according to claim 1 or 2, wherein the anodized film for coating the rust preventive primer is sealed. The coating film obtained by the formation method of the coating film in any one of Claims 1-3.

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