JP2001212499A - Method for forming metallic coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic coating film of a metallic base pigment free from uneven or cloudy appearance of the coating film due to the fine aggregation of a flake-like luster pigment and excellent in depth, glitter and flip-flop characteristics and prevented from color change considered to be due to the aggregation of an organic coloring pigment caused at the time of circulation of a coating material in a circulation pipe line. SOLUTION: In this method for forming a metallic coating film and a clear coating film on a base material on which an under coating film and an intermediate film have been formed, a metallic base coating material forming the metallic coating film is prepared by dispersing the flake-like luster pigment and a phosphate group-containing acrylic resin and subsequently blending other coating material components.

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 metallic coating film for automobiles used for painting automobile bodies and the like, and a metallic coating film obtained by the method.

[0002]

2. Description of the Related Art In recent years, an overcoat for automobiles formed by a so-called metallic paint containing a brilliant pigment has been increasing year by year. These metallic paints have a problem caused by the brilliant pigment, and various methods for solving the problem have been proposed. For example, JP-A-6-1284
No. 42, in order to prevent blackening of aluminum particles and improve the dispersion stability of the aluminum particles, a specific vinyl acetate-acrylic obtained by using a phosphate group-containing vinyl monomer, a vinyl acetate monomer and other monomers. It discloses that a copolymer resin composition is used.

Further, JP-A-8-283625 discloses an esterification reaction of a polyfunctional epoxy compound and a phosphorus compound with a phosphate ester or a phosphate amine salt obtained by neutralizing the phosphate ester with an amine compound or an amide compound. A metallic paint which uses an aluminum pigment treated with a treatment agent obtained at least and has excellent discoloration and storage stability has been proposed.

[0004] However, these publications are mainly aimed at countermeasures against blackening of aluminum pigments, and do not consider minute aggregation of pigments which affect design properties such as flip-flop properties.

On the other hand, when a metallic base paint is industrially used in a painting line, a gear pump or a plunger pump is used to prevent the paint from staying in a tank or a transport pipe and being precipitated. In addition, there is always a paint circulation that constantly circulates through the piping.

However, since the paint circulation causes a violent turbulence near the pump, the glitter pigment and the organic coloring pigment, which have been uniformly dispersed in the paint beforehand, cause minute agglomeration, and the scaly pigment is formed. Adsorption occurs or the size of such pigment particles changes, causing a color change (hereinafter referred to as "color skipping"). No effective measures are given for this.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate unevenness and white turbidity of a coating film due to fine agglomeration of flaky glittering pigments, and to provide excellent depth, glitter and flip-flop properties. It is an object of the present invention to provide a metallic coating film using a metallic base paint which is excellent in color skipping which is considered to be caused by agglomeration of an organic coloring pigment which occurs during circulation in a circulation pipe or the like.

[0008]

The present invention relates to a method of forming a metallic coating film for forming a metallic base coating film and a clear coating film on a substrate on which an undercoat coating film and an intermediate coating film are formed. Metallic base coating forming a base coating film, a metallic coating characterized by being a coating prepared by dispersing a scaly glittering pigment and a phosphoric acid group-containing acrylic resin and then blending other coating components. It is intended to provide a method for forming a film.

[0009] The present invention also relates to the present invention, wherein the scaly glittering pigment is made of a metal, and as the other coating component, at least one kind of organic coloring pigment selected from the group consisting of a bat pigment or a phthalocyanine pigment. It is intended to provide a method for forming a metallic coating film characterized by including the following.

The present invention further provides a metallic coating formed by the above method. Hereinafter, the present invention will be described in more detail.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Metallic Base Coating In the method for forming a metallic coating according to the present invention, the formation of the metallic base coating is carried out with a metallic base coating. This metallic base paint contains a scaly brilliant pigment and a phosphoric acid group-containing acrylic resin. One or more organic coloring pigments selected from the group consisting of bat pigments or phthalocyanine pigments as other paint components , A film-forming resin, a curing agent, and other various pigments, if necessary.

The scaly brilliant pigment contained in the metallic base paint is not particularly limited in its shape, and may be further colored. For example, the pigment has an average particle size (D ₅₀ ) of 2 to ₅₀ μm. And those having a thickness of 0.1 to 5 μm are preferred. Those having an average particle size in the range of 10 to 35 μm are excellent in glitter and are more preferably used.

The pigment concentration (PWC) of the scaly brilliant pigment in the coating material is generally 23.0% or less. If it exceeds the upper limit, the appearance of the coating film will be reduced. Preferably, 0.01% or more
21.0%, more preferably 0.01% to 1%.
9.0%.

Examples of the scaly glittering pigments include uncolored or colored metallic glittering materials such as metals or alloys and mixtures thereof, interference mica powder, colored mica powder, white mica powder, scaly graphite or colorless colored flat. Pigments and the like can be mentioned. Preferably, excellent dispersibility,
A non-colored or colored metal glittering material such as a metal or an alloy thereof, and a mixture thereof because a highly transparent coating film can be formed. As a specific example of the metal,
Examples thereof include aluminum, aluminum oxide, copper, zinc, iron, nickel, and tin.

The above-mentioned phosphoric acid group-containing acrylic resin is an acrylic resin obtained by copolymerizing a monomer (i) represented by the following general formula (I) and another ethylenic monomer (ii).

[0016]

Embedded image (Wherein, X is a hydrogen atom or a methyl group, and Y is
An alkylene group of 4 and n represents an integer of 3 to 30. )

The above-mentioned phosphoric acid group-containing acrylic resin can be used for dispersing the above-mentioned scaly glittering pigment. This resin has an acid value of 15 to 200 mg KOH / g,
And the acid value due to the phosphoric acid group is 10 to 150 mgKOH / g
And the number average molecular weight is preferably 1,000 to 50,000.

When the acid value is less than 15 mgKOH / g,
In some cases, the effect of the present invention cannot sufficiently achieve dispersion of the flaky glittering pigment. The acid value is 200mgK
If it exceeds OH / g, the storage stability of the metallic base paint may deteriorate. Acid value 15-200mgKOH
/ G, the acid value due to the phosphate group is 10 to 150 mgK
OH / g, more preferably 15
１００100 mgKOH / g. Further, the phosphate group-containing acrylic resin may have a hydroxyl value for curing, and the value is preferably 20 to 200.
Further, if the number average molecular weight is less than 1,000, the dispersing effect of the present invention may not be sufficiently achieved, and if the number average molecular weight exceeds 50,000, the appearance of the coating film may be deteriorated.

The phosphoric acid group-containing acrylic resin is preferably contained in an amount of from 0.01 to 7 parts by weight, more preferably from 0.1 to 7 parts by weight, based on 100 parts by weight of the solid content of the flaky glittering pigment.
6 parts by weight, particularly preferably 0.2 to 5 parts by weight. If the content of the phosphate group-containing acrylic resin is too small, it may not be possible to sufficiently prevent aggregation of the flaky glittering pigment. If the content of the phosphoric acid group-containing acrylic resin is too large, the storage stability of the paint will be poor.

The monomer (i) represented by the above general formula (I) is obtained, for example, by adding an alkylene oxide to (meth) acrylic acid in a solvent using a catalyst to form a polyalkylene glycol monoester, and then adding phosphorus oxychloride. And monoesterifying phosphoric acid, and then hydrolyzing the product to synthesize. In addition, instead of phosphorus oxychloride, orthophosphoric acid, metaphosphoric acid, phosphoric anhydride, phosphorus trichloride, phosphorus pentachloride, etc.
It can also be synthesized by a conventional method.

In the above addition reaction, the amount of the alkylene oxide to be used may be essentially a stoichiometric amount corresponding to n in the general formula (I).
It is 3 to 60 mol per mol. The alkylene oxide used here has 2 to 4 carbon atoms. Specifically, ethylene oxide, propylene oxide,
And butylene oxide. Examples of the catalyst include potassium hydroxide and sodium hydroxide. Also,
Examples of the solvent include n-methylpyrrolidone.
The reaction temperature is 40 to 200 ° C, and the reaction time is 0.5 to 5
Can be done in time.

After the above addition reaction, the monoesterification of phosphorus oxychloride may be carried out by a conventional method.
It can be performed in 5 to 5 hours. The amount of phosphorus oxychloride used may be a stoichiometric amount, and is, for example, 1 to 3 mol per 1 mol of the above-mentioned addition product.

Thereafter, hydrolysis is carried out by a conventional method to obtain a monomer (i) represented by the general formula (I). Specific examples of the monomer (i) include, for example, acid phosphooxyhexaoxypropylene) monomethacrylate, acid phosphooxide deca (oxypropylene) monomethacrylate, and the like.

The other ethylenic monomer (ii) is
It is an ethylenic monomer copolymerizable with the monomer (i), and may be a mixture of plural types of monomers. Also,
This is because the obtained copolymer, that is, the acrylic resin can be cured by a curing agent described below. Examples of such a monomer (ii) include a monomer having an acidic group or a hydroxyl group.

Examples of the acidic group of the ethylenic monomer having an acidic group include a carboxyl group and a sulfonic group. Examples of the ethylenic monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, maleic anhydride, fumaric acid, and the like. Examples of the ethylenic monomer having a sulfonic acid group include t-butylacrylamide sulfonic acid. Part of the acidic group of the ethylenic monomer having an acidic group is preferably a carboxyl group.

On the other hand, examples having a hydroxyl group include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxypropyl methacrylate, Allyl alcohol, adducts of hydroxyethyl methacrylate and ε-caprolactone, and the like can be mentioned.

Other ethylenic monomers (ii) include alkyl acrylates (methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, lauryl acrylate, etc., alkyl methacrylate (methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate) Tert-butyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, lauryl methacrylate, stearyl methacrylate, tridecyl methacrylate), an oil fatty acid and an acrylic acid having an oxirane structure. Addition products of methacrylic acid ester monomers (for example, addition products of stearic acid and glycidyl methacrylate), addition products of oxirane compounds containing an alkyl group having at least C3 and acrylic acid or methacrylic acid, styrene, α-methyl Styrene, o
-Methylstyrene, m-methylstyrene, p-methylstyrene, pt-butylstyrene, benzyl acrylate, benzyl methacrylate, itaconic acid ester (dimethyl itaconate, etc.), maleic acid ester (dimethyl dimethyl maleate, etc.), fumal Neutral monomers such as acid esters (such as dimethyl fumarate).

The above-mentioned monomers (i) and (ii) are copolymerized by an ordinary method to obtain a phosphoric acid group-containing acrylic resin. For example, each monomer mixture is mixed with a known polymerization initiator (for example, azobisisobutyronitrile, etc.), dropped into a reaction vessel containing a solvent (for example, ethoxypropanol, etc.) heated to a polymerizable temperature, and aged. By doing so, a copolymer can be obtained.

In the above polymerization reaction composition, the monomer (ii) is added in an amount of 200 parts by weight based on 100 parts by weight of the monomer (i).
~ 5000 parts by weight are preferred. If the amount of the monomer (ii) is less than 200 parts by weight, water resistance is poor, and 5000
If the amount exceeds the weight part, the effect of the phosphate group may not be exhibited. The monomer (ii) is prepared so as to have the above-mentioned predetermined amounts of acid value and hydroxyl value.

The polymerization conditions are appropriately selected. For example, the polymerization temperature is 80 to 150 ° C., and the polymerization time is 1 to 8 hours.

The scaly glittering pigment and the phosphoric acid group-containing acrylic resin are dispersed in advance by dispersing the scaly glittering pigment in an organic solvent to be incorporated in a paint, and then dispersing the phosphoric acid group-containing acrylic resin. It is preferable to use it in an easy state for convenience of dispersion time. For the dispersion, a method of gradually adding the phosphoric acid group-containing acrylic resin to the scaly glittering material-containing organic solvent solution, stirring with a disper or the like, and dispersing, the phosphoric acid group-containing acrylic resin, A method of gradually adding an organic solvent solution containing a scaly brilliant material, stirring with a disper or the like, and dispersing. Either method may be used as long as the scaly brilliant pigment is set to a condition that allows sufficient contact with the phosphoric acid group-containing acrylic resin. It is preferable to gradually add the contained acrylic resin, and to stir and disperse the resin with a disper or the like because of good handling properties.

That is, it is preferable to disperse components as little as possible except for the organic solvent. It is considered that this is because the phosphoric acid group-containing acrylic resin is smoothly adsorbed or coated on the surface of the scaly glittering pigment.

The one or more organic coloring pigments selected from the group consisting of the bat pigments and the phthalocyanine pigments are pigments derived from naturally occurring organic substances or synthetic organic substances, and are bright and transparent or almost transparent. It is an organic color pigment that does not contain any metal.

The vat-based pigments belong to the so-called metal-free organic pigments and are mostly derived directly from vat dyes.
For example, the hue is reddish, yellowish, purple, bluish, greenish, or the like. It is commonly used to give light and pastel colors. It is harder to migrate than dyes and has slightly better heat resistance. Specific examples include anzanthrone-based pigment, sullen-based pigment, flavanthrone-based pigment, and perylene-based pigment.

Examples of the above-mentioned Anzanthrone pigments include Monolight Red 2Y (red pigment manufactured by Zeneca), Hosta Palm Scarlet GO (red pigment manufactured by Hoechst Japan), Hosta Palm Scarlet GO Trans (red pigment manufactured by Hoechst Japan), India Fast Orange OV-5974 (an orange pigment manufactured by Bayer AG) and the like.

Examples of the above-mentioned slen pigments include Monolight Blue 3R (a blue pigment manufactured by Zeneca) and Monolight Blue 3R.
RN (blue pigment manufactured by Zeneca), Paliogen Blue 647
0 (blue pigment manufactured by BASF Japan), Fast Gen Blue 6011AMA (blue pigment manufactured by Dainippon Ink),
Fast Gen Blue 6016 (blue pigment manufactured by Dainippon Ink and Chemicals), Chromophthal Blue A3R (blue pigment manufactured by Ciba Geigy) and the like.

The flavanthrone-based pigments include Chromophthalo-A2R (a yellow pigment manufactured by Ciba Geigy),
Monolite Yellow FR (yellow pigment manufactured by Zeneca), Paliogen Yellow 1870 (yellow pigment manufactured by BASF Japan)
And the like.

Examples of the perylene pigment include perylene red R.6418 (red pigment manufactured by BASF Japan).
Pariogen Red 3521K (a red pigment manufactured by BASF Japan), Irgazin Red BPT (a red pigment manufactured by Ciba Geigy), Hoster Palm Red P2GL (a red pigment manufactured by Hoechst Japan), and the like.

The above-mentioned phthalocyanine pigment is a generic term for organic pigments having _four isoindole groups C ₆ H ₄ C ₂ N, and has a very stable steric configuration and a clear hue excellent in weather resistance and coloring power. It is. For example, copper phthalocyanine containing chelated copper (blue), metal-free phthalocyanine containing no copper (blue), and chlorinated copper phthalocyanine containing 14 to 16 atoms of chlorine in one molecule (green) are most widely used. . For example, First Gen Blue GP-100
(Green pigment manufactured by Dainippon Ink and Chemicals), Shanin Blue 520
6 (blue pigment manufactured by Dainichi Seika), Shanin Blue G-31
4 (blue pigment manufactured by Sanyo Dyeing Co., Ltd.), Lionol Green 6Y
KPN (green pigment manufactured by Toyo Ink Co., Ltd.) and the like.

The pigment concentration (PWC) in the metallic base paint of one or more organic color pigments selected from the group consisting of the bat pigments or the phthalocyanine pigments is 0.1 to 9%, preferably, It is 0.2 to 8%, more preferably 0.3 to 7%. When the amount is below the lower limit, discoloration may occur. When the amount exceeds the upper limit, the coating film appearance and chipping resistance are reduced.

Examples of the above-mentioned other organic color pigments include organic azo chelate pigments, insoluble azo pigments, condensed azo pigments, diketopyrrolopyrrole pigments, benzimidazolone pigments, indigo pigments, and the like. Pigments such as perinone pigments, dioxane pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments and the like can be mentioned.

Further, examples of the inorganic pigment include graphite, yellow iron oxide, red iron oxide, carbon black, titanium dioxide and the like. Further, calcium carbonate, barium sulfate, clay, talc and the like can be used in combination as extenders.

The total pigment concentration (PWC) in the metallic base paint including the above-mentioned brilliant pigments, organic coloring pigments and all other pigments is 0.1 to 50%, preferably 0.5 to 50%. 40%, more preferably
1.0 to 30%. If it exceeds the upper limit, the appearance of the coating film will be reduced.

The film-forming resin contained in the metallic base paint is not particularly limited, and acrylic resins, polyester resins, alkyd resins, epoxy resins, urethane resins and the like can be used. It is used in combination with a curing agent such as an amino resin and / or a blocked isocyanate resin. From the viewpoint of pigment dispersibility or workability, a combination of an acrylic resin and / or a polyester resin with a melamine resin is preferred.

The content of the curing agent is preferably 20 to 100% by weight based on the solid content of the film-forming resin. If the content is less than 20% by weight, the curability becomes insufficient, and if it exceeds 100% by weight, the cured film becomes too hard and brittle.

When the above metallic base paint is used in an aqueous paint, US Pat.
The film-forming resins specifically described in, for example, JP-A-151125 and JP-A-5183504 can be used. Particularly, a film-forming resin obtained by combining an acrylic resin having an acrylamide group, a hydroxyl group and an acid group described in US Pat. No. 5,183,504 with a melamine resin is excellent in finish and appearance performance.

It is preferable to add a viscosity control agent to the metallic base paint in order to ensure coating workability. The viscosity controlling agent is used for favorably forming a coating film without unevenness and sagging, and generally, a material exhibiting thixotropic properties can be used.

Examples of such a material include swelling dispersions of fatty acid amides, amides such as amide fatty acids and phosphates of long-chain polyaminoamides, and polyethylenes such as colloidal swelling dispersions of polyethylene oxide. Non-crosslinking or crosslinking utilizing the interaction of polar groups, such as organic bentonites such as smectite clay, montmorillonite, inorganic pigments such as aluminum silicate and barium sulfate, and flat pigments that exhibit viscosity depending on the shape of the pigment. Mold resins or particles can be mentioned as viscosity control agents.

However, those which do not affect the gloss and the coloring properties when formed into a coating film are particularly preferred. Particularly preferred viscosity control agents are non-crosslinked or crosslinked resins or particles utilizing the interaction of polar groups. Can be mentioned.

The amount of the viscosity control agent to be added is 0.01 to 100 parts by weight of the solid content of the resin of the metallic base paint.
15 parts by weight, preferably 0.1 to 13 parts by weight, more preferably 0.2 to 12 parts by weight. When the amount of the viscosity controlling agent exceeds 15 parts by weight, the appearance is deteriorated. When the amount is less than 0.01 part by weight, the effect of controlling the viscosity is not obtained, which causes compatibility between layers and inversion.

The solid content of the metallic base paint used in the present invention at the time of coating is 20 to 70% by weight, preferably 25 to 50% by weight. If the upper limit is exceeded, the viscosity is too high and the appearance of the coating film is reduced, and if it is lower than the lower limit, the viscosity is too low and poor appearance such as adaptability and unevenness occurs. Outside this range, the paint stability is reduced.

In general, the above-mentioned metallic base paint is preferably used in the form of a solution, and if it is a solution, it may be any of an organic solvent type, an aqueous type (water-soluble, water-dispersible, emulsion) or a non-aqueous type. .

The production of the coating composition used in the present invention is not particularly limited, including those described below, and those skilled in the art such as kneading and dispersing a compound such as a pigment using a kneader or a roll. All known methods can be used.

[0054] In the method of forming a metallic coating film of the clear coating the present invention, the use of clear coating to form a clear coating film. As this clear paint, a clear paint containing a film-forming resin, a curing agent and the like can be used. The film-forming resin is not particularly limited, and acrylic resins, polyester resins, epoxy resins, urethane resins and the like can be used, and these are curing agents such as amino resins and / or blocked isocyanate resins. Used in combination with In terms of transparency or acid etching resistance,
It is preferable to use a combination of an acrylic resin and / or a polyester resin and an amino resin, or an acrylic resin and / or a polyester resin having a carboxylic acid / epoxy curing system.

The solid content of the clear coating at the time of coating is 20 to 60% by weight, preferably 35 to 55% by weight. The solid content at the time of application is 10 to 50% by weight, preferably 20 to 50% by weight.

The clear paint is usually applied in an uncured state after the metallic base paint has been applied. Therefore, the clear paint is applied in the same manner as the metallic base paint described above in order to prevent break-in, inversion or sagging between layers. It is preferable to contain a control agent. The addition amount of the viscosity control agent is 0.01 to 1 with respect to 100 parts by weight of the resin solid content of the clear coating composition.
0 parts by weight, preferably 0.02 to 8 parts by weight, more preferably 0.03 to 6 parts by weight. When the amount of the viscosity controlling agent exceeds 10 parts by weight, the appearance is deteriorated,
If the amount is less than 0.1 parts by weight, the effect of controlling the viscosity cannot be obtained, which may cause a problem such as sagging.

The form of the clear paint used in the present invention may be any of an organic solvent type, an aqueous type (water-soluble, water-dispersible, emulsion), a non-aqueous dispersion type, and a powder type. A catalyst, a surface preparation agent and the like can be used.

Substrate The coating film forming method of the present invention can be used for various substrates, for example, metals, glass, plastics, foams, etc., and can be suitably used particularly for metal products which can be cationically electrodeposited.
Examples of the metal product include iron, copper, aluminum, tin, zinc, and the like, and alloys and castings containing these metals. Specific examples include automobile bodies and parts such as passenger cars, trucks, motorcycles, and buses. It is particularly preferable that these metals have been previously subjected to a chemical conversion treatment with a phosphate, a chromate or the like.

Undercoat Film The undercoat film formed on the substrate used in the method for forming a metallic coating film of the present invention is formed of an electrodeposition paint. As the electrodeposition paint, a cationic type and an anion type can be used, but the cationic type electrodeposition paint composition gives a laminated coating film having excellent corrosion resistance.

Intermediate coating film In the method for forming a metallic coating film of the present invention, the intermediate coating film conceals underlying defects, ensures surface smoothness after overcoating (improves appearance), and provides physical properties of the coating (impact resistance). , Chipping resistance, etc.). The intermediate coating material used for forming the intermediate coating film used in the present invention includes various organic and inorganic coloring pigments, extender pigments, etc., a film-forming resin, a curing agent, and the like.

Examples of the coloring pigment used in the intermediate coating composition include the organic pigments and the inorganic pigments described in the above-mentioned metallic base coating composition. Further, extender pigments and flat pigments such as aluminum powder and mica powder may be used in combination.

As a standard, a gray intermediate paint containing carbon black and titanium dioxide as main pigments is used. Further, a so-called color intermediate paint, which is a combination of a set gray in which lightness or hue is matched with a top coat color and various color pigments, may be used.

The film-forming resin used in the intermediate coating is not particularly limited, and may be an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin,
Urethane resins and the like can be used, and these are used in combination with a curing agent such as an amino resin and / or a blocked isocyanate resin. A combination of an alkyd resin and / or a polyester resin and an amino resin is preferred from the viewpoint of pigment dispersibility or workability.

The intermediate coating film can be used in an uncured state after being applied on the undercoated substrate. When it is cured, the curing temperature is 100 to 180 ° C., preferably 12 to 180 ° C.
By baking at 0 to 160 ° C., a cured coating film having a high degree of crosslinking can be obtained. When the amount exceeds the upper limit, the coating film becomes hard and brittle, and when the amount is less than the lower limit, curing is not sufficient. The curing time varies depending on the curing temperature.
0 minutes is appropriate.

Method for Forming Metallic Coating In the method for forming a metallic coating according to the present invention, a metallic base coating is first applied onto a substrate on which an undercoat and an intermediate coating have been formed, and the metallic base coating is then applied. Form.

When a metallic base paint is applied to an automobile body in the present invention, an electrostatic coating machine is used in order to improve workability and appearance. As an example of this electrostatic coating machine, for example, an air electrostatic spray coating called “react gun” or a so-called “μμ (micro micro) bell”,
A rotary atomization type electrostatic coating machine called "μ (micro) bell" or "meta bell" is exemplified. These include multi-stage coating, preferably 2-3 stage coating, and a coating film can also be formed by a coating method or the like in which air electrostatic spray coating and a rotary atomizing electrostatic coating machine are combined. .

However, the metallic base coating film formed by the present invention includes a metallic base coating film formed by multistage coating of one kind of paint, and two or more paints, for example, a mica base paint containing a mica pigment. It may be a multilayer coating film formed by combination with a metallic base paint containing a glitter material such as aluminum.

The dry thickness of the metallic base coating film formed by the metallic base paint used in the present invention varies depending on the desired use, but in many cases, 5 to 35 μm is useful. If the upper limit is exceeded, the sharpness may deteriorate, or problems such as unevenness or flow may occur at the time of coating. If the lower limit is not reached, the base material cannot be concealed and the film is cut.

That is, the metallic base coating film itself formed by the coating film forming method of the present invention can be cured by heating at a temperature of about 100 to 180 ° C. In the method of the present invention, the clear coating film is combined with the clear coating film. And heat-curing at the same time.

In the method for forming a metallic coating film of the present invention, a clear coating is further applied by wet-on-wet coating on the uncured metallic base coating film. Perform the curing method.

However, when the above-mentioned metallic base paint is used as a water-based paint, in order to obtain a paint film having a good finish, before coating the clear paint, the paint film is previously coated at 60 to 100 ° C. for 2 to 2 hours. It is desirable to heat for 10 minutes.

The clear coating film applied after the formation of the metallic base coating layer is formed to smooth and protect unevenness and glare caused by the brilliant pigment contained in the metallic base coating layer. You. Specifically, as a coating method, it is preferable to form a coating film by using a rotary atomizing electrostatic coating machine such as a μμ bell or μ bell described above.

The dry film thickness of the clear coating film formed by the clear coating is generally preferably about 10 to 70 μm, more preferably about 20 to 60 μm. If the upper limit is exceeded, problems such as splashes or sagging may occur during coating. If the lower limit is not reached, irregularities on the base cannot be concealed.

After the application of the clear coating film, the curing temperature for curing the coating film is 100 to 180 ° C., preferably 120 to 180 ° C.
By setting the temperature at 160 ° C., a cured coating film having a high degree of crosslinking can be obtained. When the amount exceeds the upper limit, the coating film becomes hard and brittle, and when the amount is less than the lower limit, curing is not sufficient. The curing time varies depending on the curing temperature, but is suitably from 120 ° C to 160 ° C for 10 to 30 minutes.

The thickness of the laminated coating film formed in the present invention is usually 30 to 300 μm, preferably 50 to 2 μm.
50 μm. If it exceeds the upper limit, the physical properties of the film such as a thermal cycle decrease, and if it falls below the lower limit, the strength of the film itself decreases.

[0076]

EXAMPLES The present invention will be described in detail with reference to specific examples, but the present invention is not limited to the following examples. In the following, “parts” means “parts by weight”.

Preparation Example Preparation of Acrylic Resin Containing Phosphate Group 40 parts of ethoxypropanol was charged into a 1-liter reaction vessel equipped with a stirrer, a temperature controller and a cooling tube, and 4 parts of styrene and 35.96 of n-butyl acrylate were added thereto. Parts, 18.45 parts of ethylhexyl methacrylate, 13.92 parts of 2-hydroxyethyl methacrylate, 7.67 parts of methacrylic acid, 20 parts of ethoxypropanol, and phosmer PP (acid phosphooxyhexa (oxypropylene) monomethacrylate manufactured by Unichemical Co., Ltd.). ) 40 parts of a solution obtained by dissolving 20 parts and 121.7 parts of a monomer solution consisting of 1.7 parts of azobisisobutyronitrile at 120 ° C.
, And the mixture was further stirred for 1 hour.

The obtained resin had an acid value of 105 mgKOH /
g, of which acrylic acid varnish having an acid value of 55 mgKOH / g due to a phosphoric acid group, a hydroxyl value of 60, and a number average molecular weight of 6000,
The nonvolatile content was 63%.

Preparation of Crosslinkable Resin Particles In a reaction vessel equipped with a stirring and heating device, a thermometer, a nitrogen inlet tube, a cooling tube and a decanter, 213 parts of bishydroxyethyltaurine, 208 parts of neopentyl glycol, 296 parts of phthalic anhydride, 376 parts of azelaic acid and 30 parts of xylene were charged and heated. Water generated by the reaction was removed by azeotropic distillation with xylene. The temperature of the reaction solution was set to 210 ° C. over about 3 hours from the start of reflux, and stirring and dehydration were continued until the acid value equivalent to carboxylic acid reached 135 mgKOH / g (solid content).

After the temperature of the solution was cooled to 140 ° C., 500 parts of Kjular E10 (glycidyl versatate ester manufactured by Shell Co.) was added dropwise over 30 minutes. Thereafter, stirring was continued for about 2 hours to complete the reaction. Acid value of solid content 55mg
KOH / g, hydroxyl value 91, and number average molecular weight 125
Thus, a zwitterionic group-containing polyester resin having a weight of 0 was obtained.

This amphoteric ion-containing polyester resin 10
Parts, 140 parts of deionized water, dimethylethanolamine 1
Parts, 50 parts of styrene and 50 parts of ethylene glycol dimethacrylate were vigorously stirred in a stainless steel beaker to prepare a monomer suspension. Also, an aqueous initiator solution was prepared by mixing 0.5 parts of azobiscyanovaleric acid, 40 parts of deionized water and 0.32 parts of dimethylethanolamine.

A reaction vessel equipped with a stirring and heating device, a thermometer, a nitrogen inlet tube and a cooling tube was charged with 5 parts of the amphoteric group-containing polyester resin, 280 parts of deionized water and 0.5 part of dimethylethanolamine. The temperature rose.
Here, 251 parts of the monomer suspension and 40.
82 parts were simultaneously added dropwise over 60 minutes, and the reaction was further continued for 60 minutes, and then the reaction was terminated.

A crosslinkable resin particle emulsion having a particle diameter of 55 nm as measured by a dynamic light scattering method was obtained. Xylene was added to this crosslinkable resin particle emulsion, water was removed by azeotropic distillation under reduced pressure, and the medium was replaced with xylene to obtain a xylene solution of crosslinkable resin particles having a solid content of 20% by weight.

Preparation of Metallic Base Paint 1 16.20 parts of Alpaste 7640NS (aluminum pigment manufactured by Toyo Aluminum Co., solid content 60%, average particle size 18 μm) was dissolved in 10 parts of toluene, and 0.31 part of the group-containing acrylic resin (2% based on the solid content of the brilliant pigment) is gradually added, and a desktop disper is used for about 10 minutes until the aluminum pigment and the phosphate group-containing acrylic resin are uniformly dispersed. Sprinkled and dispersed. Next, a thermosetting acrylic resin A, the following coloring pigment previously dispersed in the thermosetting acrylic resin A, and other components are added, and a green-colored metallic resin is prepared in the following composition (PWC = 18%). Base paint 1 was prepared. Alpaste 7640NS 16.20 parts (Toyo Aluminum Co., Ltd. aluminum pigment, solid content 60%, average particle size 18 μm) Mitsubishi Carbon MA-100 (Mitsubishi Chemical Corporation black pigment) 0.80 parts Monolight Blue 3R 1.50 parts (Slen-based blue pigment manufactured by Zeneca) 4.50 parts of Lionol Green 6YKPN (phthalocyanine-based green pigment manufactured by Toyo Ink) 3.90 parts of Transoxide Red 30-1005 (iron oxide-based red pigment manufactured by Dainichi Seika) 0.31 part of phosphoric acid group-containing acrylic resin of Production Example (acid value by phosphoric acid group: 30 mg KOH / g, hydroxyl value: 60, acid value: 15, number average molecular weight: 6000, solid content: 63%) Thermosetting acrylic resin A 130.30 parts (manufactured by Nippon Paint Co., Ltd., hydroxyl value 45, acid value 15 mgKOH / g, number average molecular weight 21,000, solid 14.50 parts of Uban 20N60 (butylated melamine resin manufactured by Mitsui Toatsu Co., solid content 60%) Acrylic surface conditioner 0.20 parts Crosslinked resin particles of the above production example (solid content 20%) 15. 00 parts n-butanol 8.00 parts Xylol 5.90 parts Toluene 10.00 parts Total 243.21 parts

Preparation of Metallic Base Coating 2 After dissolving 24.00 parts of Alpaste 7640NS (aluminum pigment manufactured by Toyo Aluminum Co., solid content 60%, average particle size 18 μm) in 10 parts of toluene, 0.23 parts of a phosphoric acid group-containing acrylic resin (1% based on the brilliant pigment solids) was gradually added in the same manner as in the preparation example, and the aluminum pigment and the phosphoric acid group-containing acrylic resin were uniformly mixed with a desktop disper. It took about 10 minutes to disperse and dispersed. Next, the following color pigment component previously dispersed in the thermosetting acrylic resin A and other components were added in the same manner as in the preparation of the metallic base paint 1, and the compounding ratio shown below (PWC = 14%) Was used to prepare a blue light-colored metallic base paint 2. Alpaste 7640NS 24.00 parts (Toyo Aluminum Co., Ltd., aluminum pigment, solid content 60%, average particle size 18 μm) First Gen Super Violet RBL 0.11 part (Dai Nippon Ink Co., Ltd. dioxazine purple pigment) Shanin Blue 5206 46 parts (Dainichi Seika's copper phthalocyanine brown pigment) Monarch 1300 (Colombia's black pigment) 0.06 parts

Example 1 Formation of Metallic Coating Thickness 0.8 cm, 20 cm × 30 c treated with zinc phosphate
Power Top U-50 (manufactured by Nippon Paint Co., Ltd.), a cationic electrodeposition coating, was applied to a dull steel plate having a dry film thickness of 20 μm.
And baked at 160 ° C. for 30 minutes. Next, Olga TO-870 gray (Nippon Paint Co., Ltd., polyester melamine resin paint), which is a gray intermediate coat, was applied on the obtained electrodeposition coating film so that the dry film thickness became 30 μm. Spray painted, 140 ℃ 2
A baking base coat was prepared for 0 minutes.

On the resulting intermediate coating film, the green-colored metallic base coating material 1 prepared above was applied with a dry film thickness of 1
Coating was performed by "Metabell" (Ransburg air electrostatic coating machine) on two stages at intervals of 2 minutes so as to be 5 μm. Then, after setting for 7 minutes, Mac Flow O-600 clear (Nippon Paint Co., Ltd., an acid / epoxy-curable acrylic resin-based paint) as a clear paint was applied with a μμ bell so that the dry film thickness became 30 μm. Rotary atomization type electrostatic coating was performed. The coating was baked at 140 ° C. for 20 minutes to form a coating film for evaluation of appearance.

The appearance of the obtained metallic coating film was compared with the coating film obtained in Comparative Example 1 shown below (standard), and was visually observed from the viewpoints of depth, transparency, unevenness, and glitter. The judgment was made based on the following criteria. Criterion 5; fairly good 4; fairly good 3; equivalent to standard 2; fairly poor 1; fairly poor

Further, the metallic coating film obtained at a magnification of 600 was photographed with a microscope (an electron microscope manufactured by Keyence Corporation) to obtain a photograph (FIG. 1).

Further, as an index of the flip-flop property,
The lightness (L *) of the obtained coating film was increased by 15 ° (∠15 °) and 45 ° using CR-354 (color difference meter manufactured by Minolta).
Measure at 45 degrees and 110 degrees
The FF value was calculated by substituting into the following equation. Table 1 shows the evaluation results. The higher the FF value, the larger the difference between the appearance in the shade and the appearance in the highlight. FF value = 2.69 (L * ∠15 ° −L * ∠110 °)
^1.11 / (L * ∠45 °) ^0.85

Further, in order to evaluate the cohesiveness of the organic coloring pigment which occurs when the paint is circulated in a circulation pipe or the like, 1% by weight of ion-exchanged water was added to the green metallic base paint 1 prepared above. After the coating was aged at 50 ° C. for 3 days, the coating was applied in the same manner as in the preparation of the coating film for evaluating the appearance, and the change in hue was measured by CR-354 (a color difference meter manufactured by Minolta). Table 2 shows the evaluation results.

Example 2 The amount of the phosphoric acid group-containing acrylic resin used in the metallic base paint of Example 1 was changed to 0.62 parts (4% based on the brilliant pigment solids) in advance. A coating material was prepared in the same manner as in Example 1, and a metallic coating film was formed in the same manner as in Example 1 except for the above, and evaluated similarly. Further, after adding 1% by weight of ion-exchanged water and aging at 50 ° C. for 3 days, the paint was applied in the same manner as in Example 1, and the change in hue was evaluated as CR-35.
4 (Minolta color difference meter).

Example 3 A coating film for evaluating the appearance was prepared and evaluated in the same manner as in Example 1 except that the above-prepared blue light-colored metallic base coating material 2 was used. After adding 1% by weight of ion-exchanged water and aging at 50 ° C. for 3 days, the paint was applied in the same manner as in Example 1, and the change in hue was measured with a CR-354 (color difference meter manufactured by Minolta). did.

Comparative Example 1 A metallic base paint was prepared without using the phosphoric acid group-containing acrylic resin used in Example 1, a metallic coating film was prepared in the same manner as in Example 1, and the Examples and Comparative Examples were evaluated. (Standard) for comparison. Further, the metallic coating film obtained at a magnification of 600 was photographed with a microscope to obtain a photograph (FIG. 2).

Also, 1% by weight of ion-exchanged water was added to the green metallic base paint 1 prepared above,
After 3 days of aging at ℃, the coating was applied in the same manner as in Example 1, and the change in hue was measured with a CR-354 (color difference meter manufactured by Minolta).

Comparative Example 2 An acrylic paste containing a phosphate group
The process of dispersing 40NS was not performed, and the other components were blended at the same time. Finally, a metallic coating film was prepared by dispersing and dispersing with a disper, and a metallic coating film was prepared in the same manner as in Example 1 except for the above. Was evaluated.

Further, 1% by weight of ion-exchanged water was added to the green metallic base paint 1 prepared above,
After 3 days of aging at ℃, the coating was applied in the same manner as in Example 1, and the change in hue was measured with a CR-354 (color difference meter manufactured by Minolta). Tables 1 and 2 show the evaluation results of the above examples and comparative examples.

[0098]

[Table 1]

From the above results, the laminated coating film of the example according to the present invention can suppress the fine aggregation caused by the flaky aluminum pigment and the organic coloring pigment. Unevenness was eliminated, and a sparkling feeling with a sense of depth and transparency could be exhibited. Furthermore, FF
It is considered that the coating film excellent in uniform glitter (glitter) was obtained from the higher value.

Further, looking at FIGS. 1 and 2 in which the arrangement of the scaly glittering material obtained as described above is shown, it can be seen that the content of the scaly aluminum pigment used in Example 1 and Comparative Example 1 is the same. Regardless, the brightener concentration appears to be different. This is presumably because in FIG. 2, fine aggregation occurred in the glitter pigment and the pigment concentration was uneven, so that a cross section in which many glitter materials were present was visible. In FIG. 1, there is no unevenness in the pigment concentration on any plane, and the glittering materials are evenly divided. Therefore, it seems that the gaps between the glittering materials are large and uniformly arranged. In Example 1, the metallic coating film had increased transparency, depth, and flip-flop properties, and was able to obtain a metallic coating film with excellent brightness without unevenness. The white part in the figure is a scaly luminous agent, and the black part between them represents the resin part.

[0101]

[Table 2]

Further, in order to evaluate the cohesiveness of the organic color pigment which occurs when the paint is circulated in a circulation pipe or the like, the paint was evaluated under severe conditions of adding water to the metallic base paint. The metallic base paint was found to be an excellent metallic base paint even against color skipping, which is considered to be caused by aggregation of the organic coloring pigment.

[0103]

The method of the present invention can also prevent fine agglomeration and aggregation of an organic coloring pigment, which are considered to occur when an aluminum pigment is dispersed in a paint, and can be used in a coating film of a scaly glittering material. Unevenness can be eliminated, whereby the opacity of the coating film formed by wet-on-wet can also be improved, and a multilayer coating film having excellent depth, glitter, and flip-flop properties can be formed. Was.

[Brief description of the drawings]

FIG. 1 is a photograph of the arrangement of scaly glitter pigments in a metallic base coating film of Example 1 taken with a microscope.

FIG. 2 is a photograph of the arrangement of scaly glitter pigments in the metallic base coating film of Comparative Example 1 taken with a microscope.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 201/00 C09D 201/00

Claims (3)

[Claims] 1. A method of forming a metallic coating film for forming a metallic base coating film and a clear coating film on a base material on which an undercoat coating film and an intermediate coating film are formed, wherein the metallic base coating film is formed. A method for forming a metallic coating film, wherein the paint is a paint prepared by dispersing a flaky glitter pigment and a phosphoric acid group-containing acrylic resin and then blending other paint components. 2. The method according to claim 1, wherein the scaly brilliant pigment is made of metal, and contains, as the other coating component, at least one organic coloring pigment selected from the group consisting of bat pigments and phthalocyanine pigments. Characteristic method of forming a metallic coating film. 3. A metallic coating formed by the method according to claim 1.