JP2001276724A - Method for forming metallic coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably provide a metallic coating film excellent in flip-flop properties by enhancing the orientation properties of brilliant pigment in a metallic base coating film and preventing color recession generated by the minute mixing of the metallic base coating film and a clear coating film. SOLUTION: In a metallic coating film forming method for forming the metallic base coating film and the clear coating film on a base material on which an undercoating film and, if necessary, an intercoating film are formed, a metallic base paint forming the metallic base coating film contains a non- crosslinked polymer fine particles with a means particle size (D50) of 0.05-10 μm and crosslinked polymer fine particles with a means particle size (D50) of 0.01-1 μm and a solid weight ratio of the non-crosslinked polymer fine particles and the crosslinked polymer fine particles is 5/1-1/5.

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, a metallic coating film formed by a so-called metallic paint containing a brilliant pigment has been increasing as a top coating film for automobiles. This metallic coating film forms a metallic base coating film and a clear coating film on a wet-on-wet basis, and when the metallic base coating film and the clear coating film are mixed, the arrangement of the glitter pigments in the metallic base coating film is reduced. Become uneven, causing a reduction in flip-flop properties and a decrease in gloss of the coating film.

In addition, it is generally known that a metallic base paint contains crosslinked polymer fine particles as a viscosity-imparting agent in order to control the viscosity at the time of painting or baking and hardening, but this alone may not be sufficient. Was.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the orientation of a brilliant pigment in a metallic base coating film and to prevent color reversion caused by minute mixing of the metallic base coating film and the clear coating film. Accordingly, it is to stably provide a metallic coating film having excellent flip-flop properties.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for forming a metallic coating film for forming a metallic base coating film and a clear coating film on a substrate on which an undercoating film and, if necessary, an intermediate coating film have been formed. The metallic base paint forming the metallic base coating film has an average particle size (D ₅₀ )
Non-crosslinked polymer fine particles having a particle size of 0.05 to 10 μm and crosslinked polymer fine particles having an average particle diameter (D ₅₀ ) of 0.01 to 1 μm, and the above non-crosslinked polymer fine particles and crosslinked polymer fine particles are contained. Wherein the weight ratio of the solid content to the solid content is 5/1 to 1/5.

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

[0007]

BEST MODE FOR CARRYING OUT THE INVENTIONMetallic base coating  In the method for forming a metallic coating film of the present invention,
The base coating is formed using a metallic base paint.
Is This metallic base paint is a non-crosslinked
Particles, crosslinked polymer fine particles, brilliant pigments, organic or
Various inorganic coloring pigments, film-forming resins, curing agents, etc.
It contains.

In the present invention, the non-crosslinked resin particles used in the metallic base paint are prepared by copolymerizing a polymerizable monomer in a mixed liquid of a dispersion-stable resin and an organic solvent, so that the non-crosslinked resin particles are insoluble in the mixed liquid. It can be prepared as resin particles. The monomer to be copolymerized in the presence of a dispersion-stable resin to obtain non-crosslinked resin particles is not particularly limited as long as it is a radically polymerizable unsaturated monomer.

However, in order to synthesize the dispersion stable resin and the non-crosslinked polymer fine particles, it is preferable to use a polymerizable monomer having a functional group. This is because the non-crosslinked polymer fine particles having a functional group can react with a curing agent described below together with the dispersion-stable resin containing the functional group to form a three-dimensionally crosslinked coating film.

The dispersion-stable resin is not particularly limited as long as it can stably synthesize non-crosslinked polymer fine particles in an organic solvent. Specifically, the hydroxyl value is 10 to 2
50, preferably 20 to 180, and an acid value of 0 to 10
0 mgKOH / g, preferably 0 to 50 mgKOH / g
g, it is preferable to use an acrylic resin, a polyester resin, a polyether resin, a polycarbonate resin, a polyurethane resin or the like having a number average molecular weight of 800 to 100,000, preferably 1,000 to 20,000. When the ratio exceeds the upper limit, the handling property of the resin decreases, and the handling of the non-crosslinked polymer fine particles themselves also decreases. If the ratio is below the lower limit, the resin is desorbed when the coating film is formed, or the stability of the particles is lowered.

The method for synthesizing the above-mentioned dispersion-stable resin is not particularly limited, but a method obtained by radical polymerization in the presence of a radical polymerization initiator, a method obtained by a condensation reaction or an addition reaction, and the like are preferred. . Furthermore,
The monomer used to obtain the dispersion-stable resin may be appropriately selected depending on the properties of the resin, but may include a polymerizable monomer used to synthesize non-crosslinked polymer fine particles described below. It is preferable to use a compound having a functional group such as a hydroxyl group or an acid group, and if necessary, a compound having a functional group such as a glycidyl group or an isocyanate group.

The composition ratio of the above-mentioned dispersion-stable resin and the above-mentioned polymerizable monomer can be arbitrarily selected according to the purpose. For example, the dispersion-stable resin is 3 to 3 based on the total weight of the two components.
80% by weight, especially 5 to 60% by weight, the polymerizable monomer is 97%
-20% by weight, especially 95-40% by weight is preferred. Further, the total concentration of the dispersion-stable resin and the polymerizable monomer in the organic solvent is preferably 30 to 80% by weight, particularly preferably 40 to 60% by weight based on the total weight.

The non-crosslinked polymer fine particles can be obtained by polymerizing a radically polymerizable monomer in the presence of a dispersion stable resin. The non-crosslinked polymer fine particles have a hydroxyl value of 50 to 400, preferably 100 to 3
00, an acid value of 0 to 200 mgKOH / g, preferably 0 to ₅₀ mgKOH / g, and an average particle diameter (D50) of 0.
Those having a thickness of from 0.05 to 10 μm, preferably from 0.1 to 2 μm are preferred. If it exceeds the lower limit, the particle shape cannot be maintained, and if it exceeds the upper limit, the stability when dispersed in the coating material is reduced.

Typical examples of the polymerizable monomer having a functional group used for synthesizing the non-crosslinked polymer fine particles are as follows. As those having a hydroxyl group, for example, hydroxyethyl (meth) acrylate,
Examples include hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxymethyl methacrylate, allyl alcohol, and adducts of hydroxyethyl (meth) methacrylate with ε-caprolactone.

On the other hand, those having an acidic group include polymerizable monomers having a carboxyl group, a sulfonic acid group and the like. Examples of those having a carboxyl group include:
(Meth) acrylic acid, crotonic acid, 3-butenoic acid, 4-
Pentenoic acid, 2-methyl-3-butenoic acid, itaconic acid,
Maleic anhydride, fumaric acid and the like can be mentioned. Examples of the polymerizable monomer having a sulfonic acid group include t-butylacrylamide sulfonic acid. When a polymerizable monomer having an acidic group is used, a part of the acidic group is preferably a carboxyl group.

Further, glycidyl group-containing unsaturated monomers such as glycidyl (meth) acrylate, m-isopropenyl-
Isocyanate group-containing unsaturated monomers such as α, α-dimethylbenzyl isocyanate and isocyanatoethyl acrylate are mentioned as polymerizable monomers having a functional group.

Other polymerizable monomers include, for example,
Methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate,
T-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Alkyl (meth) acrylates such as n-octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and tridecyl methacrylate; acrylic acid or methacrylate monomers having an oil fatty acid and oxirane structure (E.g., an addition reaction product of stearic acid and glycidyl methacrylate), an addition reaction product of an oxirane compound containing an alkyl group having at least C3 and acrylic acid or methacrylic acid, styrene, α-methylstyrene, ο- Methylstyrene, m
-Methylstyrene, p-methylstyrene, pt-butylstyrene, benzyl (meth) acrylate, itaconic acid ester (dimethyl itaconate, etc.), maleic acid ester (dimethyl oleic acid, etc.), fumaric acid ester (dimethyl fumarate Acrylonitrile, methacrylonitrile, methyl isopropenyl ketone, vinyl acetate, beoba monomer (trade name, manufactured by Shell Chemical Co., Ltd.), vinyl propionate, vinyl pivalate, ethylene, propylene, butadiene, N, N-dimethylamino Examples include polymerizable monomers such as ethyl acrylate, N, N-dimethylaminoethyl methacrylate, acrylamide, and vinylpyridine.

The polymerization reaction for obtaining the non-crosslinked polymer fine particles is preferably carried out in the presence of a radical polymerization initiator. Examples of the radical polymerization initiator include, for example, 2,2′-
Examples include azo-based initiators such as azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile), benzoyl peroxide, lauryl peroxide, and t-butyl peroctoate. The amount of these initiators to be used is preferably 0.2 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the total of polymerizable monomers. The polymerization reaction for obtaining non-crosslinked polymer fine particles in an organic solvent containing a dispersion-stable resin is generally carried out by 60
It is preferable to carry out the reaction in a temperature range of about 160 ° C. for about 1 to 15 hours.

Further, the non-crosslinked polymer fine particles are different from the crosslinked polymer fine particles in that they are a particle component in a coating material but do not form a particle structure in a coating film. In other words, the non-crosslinked polymer fine particles differ from the crosslinked polymer fine particles in that the crosslinked portion does not exist in the particles, so that the particle shape changes during the baking process and can become a resin component.

However, even if the non-crosslinked polymer fine particles themselves are added to the coating system alone, no structural viscosity is exhibited. When used in combination with the crosslinked polymer fine particles, a greater structural viscosity is exhibited.

Furthermore, for example, NAD (Non Aqueous Disper) used for NAD paint described in Coloring Materials, Vol. 48 (1975), pp. 28-34.
resin particles (non-aqueous polymer dispersion) can also be used.

On the other hand, the crosslinked polymer fine particles are insoluble in an organic solvent and have an average particle size (D ₅₀ ) of 0.01 to 1 μm. If the average particle size exceeds the upper limit, the stability decreases,
Below the lower limit, difficulty in production equipment is high, and maintenance of the particle shape is also difficult. As the above crosslinked polymer fine particles, a resin having an emulsifying ability such as an alkyd resin or a polyester resin synthesized using a monomer having a zwitterionic group in the molecule as one of the polyhydric alcohol components, and a polymerization initiator And those obtained by emulsion-polymerizing a polymerizable monomer in an aqueous medium in the presence of

The above zwitterionic group is represented by -N ⁺ -R-CO
O ^- or -N ⁺ -R-SO ₃ ^- expressed as (wherein, R represents a linear or branched alkylene group of C ₁ ~C _6),
As a monomer having this in the molecule, a monomer having two or more hydroxyl groups can be used. As such a monomer, a hydroxyl group-containing aminosulfonic acid-type zwitterionic compound is preferable from the viewpoint of resin synthesis. Specific examples include bishydroxyethyl taurine.

The resin having an emulsifying zwitterionic group in the molecule, which is synthesized using the above monomer, has an acid value of 30 to 150 mgKOH / g, preferably 40 to 1 mgKOH / g.
50 mgKOH / g, number average molecular weight of 500 to 500
0, preferably 700 to 3000 polyester resin. If the upper limit is exceeded, the handleability of the resin will be reduced. If the lower limit is not reached, the resin having emulsifying ability will be desorbed when the coating film is formed, or the solvent resistance will be reduced.

In the synthesis of the crosslinked polymer fine particles, it is necessary to include, as the polymerizable monomer to be emulsion-polymerized, a monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule. Such a monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule is preferably contained in the range of 0.1 to 70% by weight of all the monomers. The amount is selected to provide sufficient crosslinking to dissolve the particulate polymer in the solvent.

Examples of the monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and trimethylolpropane di ( (Meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin di (meth) acrylate and the like.

The crosslinked polymer fine particles used in the present invention are generally contained in an emulsion resin, do not contain a low-molecular emulsifier or a protective colloid which lowers the performance when formed into a coating film, and have an intramolecular structure. Since the polymer is crosslinked by copolymerizing a monomer having two or more radically polymerizable ethylenically unsaturated groups, the coating film is excellent in water resistance, solvent resistance, gloss and the like.

The amount of the crosslinked polymer fine particles to be added is 0.1 to 100 parts by weight of the solid resin content of the metallic base paint.
It is added in an amount of from 0.01 to 20 parts by weight, preferably from 0.1 to 17 parts by weight, more preferably from 0.2 to 15 parts by weight. If the amount of the crosslinked polymer fine particles exceeds 20 parts by weight, the appearance will be deteriorated. If the amount is less than 0.01 parts by weight, the effect of controlling the viscosity will not be obtained, which will cause compatibility between layers and inversion.

The weight ratio of the mixed solid content of the non-crosslinked polymer fine particles and the crosslinked polymer fine particles contained in the metallic base paint is in the range of 5/1 to 1/5 and in the range of 2/1 to 1/2. Is more preferred. If the ratio is out of the above range, the viscosity control effect cannot be obtained.

The glitter pigment contained in the metallic base paint is not particularly limited in its shape, and may be further colored. For example, the glitter pigment has an average particle diameter (D ₅₀ ) of 2 to 5%.
A scaly one having a thickness of 0 μm and a thickness of 0.1 to 5 μm is preferable. 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 (PW)
C) is generally at most 23.0%. If it exceeds the upper limit, the appearance of the coating film will be reduced. Preferably, from 0.01% to 20.
0%, more preferably 0.01% to 18.0%
It is.

Examples of the above-mentioned brilliant pigments include uncolored or colored metallic brilliant materials such as metals or alloys and mixtures thereof, interference mica powder, colored mica powder, white mica powder, graphite and colorless colored flat pigments. be able to. A non-colored or colored metallic brilliant material such as a metal or an alloy and a mixture thereof are preferred because they are excellent in dispersibility and can form a highly transparent coating film. Specific examples of the metal include aluminum, aluminum oxide, copper, zinc, iron, nickel, and tin.

Examples of the color pigments include organic azo chelate pigments, insoluble azo pigments, condensed azo pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, dioxane pigments, quinacridone pigments, isoquinone pigments, and isoquinone pigments. Indolinone pigments, metal complex pigments and the like can be mentioned. Inorganic pigments such as graphite, yellow iron oxide, red iron oxide, carbon black, titanium dioxide and the like can be mentioned. Further, as an extender, calcium carbonate, barium sulfate,
Clay, talc, etc. may be used in combination.

The total pigment concentration (PW) in the metallic base paint, including the above-mentioned brilliant pigment and all other pigments
C) is from 0.1 to 50%, preferably
0.5% to 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 may be a film-forming resin such as an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin, or a urethane resin. And these are 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.

When the above-mentioned metallic base paint is used as 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.

Further, other viscosity control agents may be added to the metallic base paint in order to ensure the workability of coating. Such materials include, for example, swelling dispersions of fatty acid amides, amide-based fatty acids, polyamides such as phosphates of long-chain polyaminoamides, polyethylene-based materials such as colloidal swelling dispersions of polyethylene oxide, and organic materials. Examples thereof include organic bentonites such as acid smetite clay and montmorillonite, inorganic pigments such as aluminum silicate and barium sulfate, and flat pigments which exhibit viscosity depending on the shape of the pigment.

The solid content of the metallic base paint used in the present invention at the time of coating is 15 to 70% by weight, preferably 20 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 coating material is preferably used in the form of a solution. If it is a solution type, 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.

[0041]Clear coating  In the method for forming a metallic coating film of the present invention, the clear coating film
Use clear paint to form This clear
As paint, contains film-forming resin and hardener
Clear paint is available. As the above film-forming resin
Is not particularly limited, acrylic resin, poly
Use ester resin, epoxy resin, urethane resin, etc.
These can be amino resins and / or
Used in combination with a curing agent such as a isocyanate resin
It is. In terms of transparency or acid etching resistance,
Kuryl resin and / or polyester resin and amino tree
Combination with fat, or carboxylic acid / epoxy curing system
Acrylic resin and / or polyester resin having
It is preferable to use such as.

The solid content in the clear coating is 2
It is 0 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, in order to prevent break-in, inversion, sagging, etc. between layers, the clear paint described in the above-mentioned metallic base paint is used. 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.

[0045]Base material  The coating film forming method of the present invention can be applied to various substrates, for example, metals and gas.
Can be used for glass, plastic, foam, etc.
It can be suitably used for metal products which can be coated by electrodeposition.
Examples of the above metal products include iron, copper, and aluminum.
Alloys and castings containing metals, tin, zinc, etc.
Structure. Specifically, passenger cars, trucks,
Vehicle bodies and parts such as motorcycles and buses.
You. These metals are previously formed with phosphate, chromate, etc.
Treated ones are particularly preferred.

[0046]Undercoat  On the substrate used in the metallic coating film forming method of the present invention
The applied undercoat film is formed by electrodeposition paint.
Is done. As the electrodeposition paint, there are cationic type and anionic type.
ON type can be used, but cationic electrodeposition coating composition is
Provides a laminated coating with excellent food properties.

[0047]Intermediate coating  In the method for forming a metallic coating film of the present invention,
The intermediate coating film formed by
You. This intermediate paint is used for various organic and inorganic colored face
Pigments, extender pigments, film-forming resins and curing agents
I do. The intermediate coating film conceals the base,
Ensuring surface smoothness (improving appearance), coating film properties (impact resistance,
Chipping resistance).

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 coating 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 base material. 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. This is not the case when used uncured.

[0052]Method of forming metallic coating film  In the method for forming a metallic coating film of the present invention,
On the substrate on which the coating film and, if necessary, the intermediate coating film are formed
First, apply a metallic base paint containing a bright pigment
To form a metallic base coating.

In general, when a metallic base paint is applied to an automobile body or the like, a multi-stage paint by air electrostatic spray paint, preferably 2 paints, is used to enhance the design.
Painting on stage or air electrostatic spray painting, commonly called “μμ (micro micro) bell”, “μ
A coating film is formed by a coating method combining a (micro) bell "or a" metabell "or the like with a rotary atomizing type electrostatic coating machine. The method of the present invention can be suitably used for these coating methods.

The metallic base paint used in the method for forming a metallic coating film of the present invention contains non-crosslinked polymer fine particles and crosslinked polymer fine particles. The non-crosslinked polymer fine particles themselves do not exhibit structural viscosity when added to a coating system by themselves, but exhibit a greater structural viscosity when used in combination with crosslinked polymer fine particles.

This remarkably appears in the color return due to minute mixing of the metallic base coating film and the clear coating film, and in the crushability of the coating particles immediately after application in spray coating. For example, the shear rate (shear force) at the moment when the paint particles collide with the object is 10 (1 / sec), and the shear rate (shear force) immediately after the paint particles collide with the article is 0. .
1 (1 / sec), it can be inferred by measuring the paint viscosity at each shear rate (shearing force) of the paint. The greater the difference between them, the more easily the paint particles are crushed, and This means that the orientation of the glitter pigment included in the particles to the surface of the object to be coated advances. However, the viscosity after coating is preferably low, but it is necessary to maintain the glitter pigment oriented parallel to the object to be coated so that the pigment is not realigned by sagging or flowing.

Actually, particles of the spray paint immediately before application are captured by a liquid immersion method using silicone oil, and the particle size is measured. By measuring the diameter of the paint particles and dividing by the previously measured particle size, the deformation rate as a measure of the crushability can be determined.

That is, the large deformation ratio means that the coating particles containing the glittering pigment have a large deformation ratio at the same time as the application, which collapses from a spherical shape to a dome shape and a dish shape. The higher the ratio of crushing, the more the glitter pigment contained therein is oriented parallel to the object to be coated, and the higher the flip-flop property when viewed as a coating film.
When the deformation ratio is small, the glitter pigment included is not parallel to the object to be coated, and the flip-flop property is reduced.

As described above, by imparting structural viscosity to the metallic base paint, the viscosity of the paint and the deformation rate after the application of the paint particles are increased, and the flip-flop property of the obtained metallic paint film is improved. can do.

The thickness of the coating film when coated with the metallic base paint of the present invention varies depending on the desired use, but in many cases, a thickness of 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 combination with the clear coating film is carried out. 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 on the uncured metallic base coating by wet-on-wet coating to form a clear coating film. A curing method is preferably used.

The metallic coating film obtained by the above method is white in the front direction (perpendicular to the coating surface) and has excellent glitter as glitter, while the glitter coating looks less bright in the oblique direction. A coating film having a large difference between the two can be formed. In other words, it is possible to form a metallic coating film having a strong flip-flop property in which the metallic feeling changes significantly depending on the viewing angle.

However, when the above-mentioned metallic base paint is used as an aqueous paint, in order to obtain a paint film having a good finish, before coating the clear paint, the paint film is previously heated 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 irregularities, shining and the like 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 metallic coating film composed of the metallic base coating film and the clear coating film is 100 to 180 ° C., preferably 12 to 180 ° C.
By setting the temperature to 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, 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 in most cases 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.

[0068]

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”.

[0069]Manufacturing example I-1 Example of producing non-crosslinked polymer fine particles  (A) Production of dispersion-stable resin Acetic acid was placed in a vessel equipped with a stirrer, temperature controller, and reflux condenser.
90 parts of butyl were charged. Next, 20 parts of a solution having the following composition, 38.9 parts of methyl methacrylate, 38.8 parts of stearyl methacrylate, 22.3 parts of 2-hydroxyethyl acrylate, and 5.0 parts of azobisisobutyronitrile were added, and the mixture was heated with stirring. Raised the temperature
I let you. At 110 ° C., the remaining 85 parts of the mixed solution
Dropwise, then 0.5 parts of azobisisobutyronitrile
A solution consisting of 10 parts of butyl acetate was added dropwise over 30 minutes.
The reaction solution was further stirred and refluxed for 2 hours, and the rate of change to resin was changed.
, The reaction was terminated, and the solid content was 50%.
An acrylic resin having an average molecular weight of 5,600 was obtained.

(B) Production of non-crosslinked polymer fine particles 35 parts of butyl acetate and 60 parts of the acrylic resin obtained in the above (a) production of dispersion stable resin are charged into a vessel equipped with a stirrer, a cooler and a temperature controller. It is. Next, a solution having the following composition 7.0 parts of styrene 1.8 parts of methacrylic acid 12.0 parts of methyl methacrylate 8.5 parts of ethyl acrylate 40.7 parts of 2-hydroxyethyl acrylate 1.4 parts of azobisisobutyronitrile The mixture was added dropwise at 100 ° C. for 3 hours, and then a solution comprising 0.1 part of azobisisobutyronitrile and 1 part of butyl acetate was added to
It was dropped in 0 minutes. When the reaction solution was further stirred for 1 hour, an emulsion having a solid content of 60% and a particle size of 0.18 μm was obtained. This emulsion was diluted with butyl acetate, the viscosity was 300 cps (25 ° C.), and the particle size was 0.18 μm.
A butyl acetate dispersion having a content of non-crosslinked polymer fine particles of 40% by weight was obtained.

[0071]I-2 Production example of non-crosslinked polymer fine particles  Acetate was placed in a container equipped with a stirrer, cooler,
35 parts of the above-mentioned production example of I-1 non-crosslinked polymer particles
(A) 100 parts of acrylic resin obtained in the production of dispersion stable resin
Was charged. Next, a solution having the following composition 1.3 parts methacrylic acid 18.4 parts methyl methacrylate 18.2 parts ethyl acrylate 12.2 parts 2-hydroxyethyl methacrylate 1.4 parts azobisisobutyronitrile 1.4 parts at 100 ° C. for 3 hours And then azobisisobuty
A solution consisting of 0.1 part lonitrile and 1 part butyl acetate
It was dropped in 0 minutes. Stir the reaction solution for another hour
As a result, solid content 60%, viscosity 80ps (25 ° C)
An emulsion having a diameter of 0.14 μm was obtained.

[0072]II Preparation Examples of Crosslinked Polymer Fine Particles  (A) Production of polyester resin having zwitterionic group Stirrer, nitrogen inlet tube, temperature controller, condenser,
Bishydroxyethyl is added to 2L kolben with canter
134 parts of lutaurine, 130 neopentyl glycol
Parts, azelaic acid 236 parts, phthalic anhydride 186 parts and
And 27 parts of xylene, and the temperature was raised. Generated by reaction
The formed water was removed by azeotropic distillation with xylene. About from the start of reflux
The temperature was raised to 190 ° C. over 2 hours, and
Stirring and dehydration are continued until the acid value reaches 145.
Cooled to 0 ° C. Subsequently, the temperature of 140 ° C. is maintained,
"Cajura E-10" (Versatic made by Shell)
Glycidyl ester) in 30 minutes.
After that, stirring was continued for 2 hours to complete the reaction. in this way
The resulting polyester resin has an acid value of 59,
The syl number was 90 and the number average molecular weight was 1054.

(B) Production of Crosslinked Polymer Fine Particles In a 1 L reaction vessel equipped with a stirrer, a cooler, and a temperature controller, 232 parts of deionized water and the polyester resin having the above II (a) zwitterionic group were added. 10 parts of the polyester resin obtained in the production and 0.75 parts of dimethylethanolamine were charged and dissolved while maintaining the temperature at 80 ° C. with stirring.
To this, 4.5 parts of azobiscyanovaleric acid was added with 45 parts of deionized water.
And a solution dissolved in 4.3 parts of dimethylethanolamine. Next, a mixed solution consisting of 130 parts of methyl methacrylate, 40 parts of styrene and 140 parts of ethylene glycol dimethacrylate was dropped over 60 minutes. After the dropwise addition, a solution prepared by dissolving 1.5 parts of azobiscyanovaleric acid in 15 parts of deionized water and 1.4 parts of dimethylethanolamine was added, and stirring was continued at 80 ° C. for 60 minutes. .2, viscosity 92 cps
(25 ° C.), an emulsion having a particle size of 0.1 μm was obtained. This emulsion was replaced with a xylol solution by utilizing azeotropic distillation to obtain a xylol dispersion having a crosslinked polymer fine particle diameter of 0.07 μm and a crosslinked polymer fine particle content of 20% by weight.

[0074]III-1 Production of acrylic resin  A container equipped with a stirrer, temperature controller and reflux condenser
50 parts of len and 25 parts of n-butanol were charged. Then below
Solution of the above composition Styrene 5.0 parts Methacrylic acid 1.5 parts Methyl methacrylate 20.0 parts Ethyl acrylate 45.0 parts 2-hydroxyethyl acrylate 6.6 parts Butoxymethylacrylamide 5.0 parts PLUXEL FM-2 17. 6 parts (Daicel Chemical Industries, Ltd. hydroxyl group-containing monomer) Add 20 parts of 7.0 parts of azobisisobutyronitrile, heat while stirring, and raise the temperature.
I let you. While refluxing, 87.7 parts of the remaining mixed solution
Drop in 3 hours, then azobisisobutyronitrile
Drop a solution consisting of 0.2 parts and 8 parts of xylol in 30 minutes
I dropped it. The reaction solution is further stirred and refluxed for one hour to form a resin.
After increasing the rate of change of the
%, An acrylic resin varnish having a number average molecular weight of 3800
Was.

[0075]III-2 Production of acrylic resin  Using the same apparatus as in Production Example III-1, xylene 55
Parts, n-butanol 25 parts, and then the following composition
5.0 parts of styrene 3.6 parts of methacrylic acid 3.6 parts of methyl methacrylate 15.0 parts of ethyl acrylate 37.4 parts of 2-hydroxyethyl acrylate 9.0 parts of butoxymethylacrylamide 10.0 parts of Plaxel FM-2 20.0 parts (Hydroxyl-containing monomer manufactured by Daicel Chemical Industries, Ltd.) 20 parts of azobisisobutyronitrile 7.0 parts were added, and the mixture was heated with stirring to raise the temperature.
I let you. While refluxing, 87.0 parts of the remaining mixed solution
Drop in 3 hours, then azobisisobutyronitrile
A solution consisting of 0.2 parts and 8 parts of xylene is dropped in 30 minutes
did. The reaction solution was stirred and refluxed for another hour to complete the reaction.
Acrylic with 55% solids and 3700 number average molecular weight
A resin varnish was obtained.

[0076]III-3 Production of acrylic resin  82 parts of xylene using the same apparatus as in Production Example III-1
And then a solution having the following composition: 4.5 parts of methacrylic acid, 26.0 parts of ethyl acrylate, 64.5 parts of Praccel FM-1 (hydroxyl-containing monomer manufactured by Daicel Chemical Industries, Ltd.) 5.0 parts of MSD-100 (Mitsui Toatsu) 20 parts of 13.0 parts of azobisisobutyronitrile were added, and the mixture was heated with stirring to increase the temperature.
I let you. While refluxing, 93.0 parts of the remaining mixed solution
Drop in 3 hours, then azobisisobutyronitrile
A solution consisting of 1.0 part and 12 parts of xylene was dropped in 30 minutes
I dropped it. After the reaction solution was stirred and refluxed for another hour,
Then, 63 parts of the solvent was distilled off under reduced pressure to complete the reaction.
Acrylic resin with a solid content of 75% and a number average molecular weight of 2,000
I got a varnish.

[0077]IV Production of metallic base paint  In a stainless steel container, 73 parts of varnish of Production Example III-1
27 parts of varnish of Production Example III-3, Uban 20N60
(Melamine resin manufactured by Mitsui Toatsu Co., solid content 60%) 50 parts,
50 parts of the crosslinked polymer fine particles of Production Example II,
25 parts of non-crosslinked polymer particles, aluminum paste 91-056
2 (Toyo Aluminum Co., Ltd. aluminum pigment) 15 parts,
Weigh and stir with a tabletop stirrer
Was adjusted.

[0078]Example 1 Formation of metallic coating  0.8mm thick dull steel plate with zinc phosphate chemical conversion treatment
Cationic electrodeposition paint “V-50” (Nippon Paint Co., Ltd.)
Electrodeposition coating so that the cured film thickness is about 20 μm,
After heating and curing at 160 ° C for 30 minutes, apply gray middle coat
"Olga P-2 Primer" (Nippon Paint Co., Ltd.)
Air spray coating so that the cured film thickness is about 25 μm
And leave it at room temperature for 3 minutes, then heat it at 140 ° C for 30 minutes to harden it.
It was made into an object to be coated.

The above-prepared IV metallic base paint was coated with No. 5 using a diluted thinner consisting of 50 parts of Solvesso 150 (hydrocarbon solvent manufactured by Exxon Petroleum), 25 parts of ethyl acetate and 25 parts of toluene. 11. 4 Ford Cup
The dilution was adjusted to 5 seconds / 20 ° C.

The substrate to be coated, which has been degreased with a solvent, is set upright, and the metallic base paint is "metabell" in two stages at 1.5 minute intervals so that the dry film thickness is 15 μm.
(Ransburg's rotary atomizing electrostatic coating machine). It was left at room temperature for 4 minutes to form a metallic base coating film.

Next, the No. A clear paint “Macflow O-380” (manufactured by Nippon Paint Co., Ltd.) diluted and adjusted to 25 seconds / 20 ° C. with a 4 Ford cup was wet-on-wet to give a dry coated film of 35 μm.
m was applied once. Then at room temperature,
After standing for 7 minutes in the vertical direction,
Bake for 30 minutes in oven at ℃. A metallic coating was obtained by 2 coats / 1 bake.

[0082]Formation of Metallic Base Single Layer Coating for Comparison  In the same gray as used in the formation of the metallic coating
On the painted plate, apply the previously manufactured IV metallic base paint.
In the same way, apply the base paint twice and dry it.
And paint to a thickness of 15μm, metallic base coating
It was created. Then, after standing at room temperature vertically for 7 minutes,
Bake in a dryer at 140 ° C for 30 minutes while keeping it vertical
Thus, a metallic base single-layer coating film was obtained.

The obtained metallic coating film was evaluated according to the following evaluation method. <Orientation of aluminum> The flip-flop property of the metallic coating film obtained by 2 coats / 1 bake and the metallic base single-layer coating film was visually determined, and evaluated according to the following criteria. Criterion 5; fairly good 4; fairly good 3; equivalent to standard 2; fairly poor 1; fairly poor

<Color return property> The color difference from the metallic coating film obtained by 2 coats / 1 bake was measured based on the corresponding metallic base single-layer coating film, and judged according to the following criteria. Criterion 5; color difference of 0.5 or less 4; color difference of 1.0 to 0.63; color difference of 1.5 to 1.12; color difference of 2.0 to 1.6 1, color difference of 2.1 that's all

<Gloss> The gloss of the metallic coating film obtained by 2 coats / 1 bake was measured using “Grostesta GOT-01” manufactured by Tokai Rika Electric Co., Ltd.

<Paint Viscosity> After the metallic base paint of Production Example IV was previously adjusted to a solid content (70%) immediately after application, the rheometer MR-300 (a solid liquid meter manufactured by Rheology) was used. , Shear rate (shear force) 10
When the viscosity at (1 / sec) was measured, it was 150 poise, and it was found that the viscosity at a shear rate (shear force) of 0.1 (1 / sec) had a viscosity of 620 poise.

<Particle Diameter of Spray Paint> Particles immediately before application of the spray paint were captured by a liquid immersion method using silicone oil, and the particle diameter was measured. At the same time, the diameter of the particles crushed by coating on the portion without silicon oil was measured, and divided by the previously measured particle size to determine the deformation ratio as a measure of the crushability.

The metallic base paint of Production Example IV, which is a combined system of crosslinked polymer fine particles and non-crosslinked polymer fine particles, had a particle diameter of 12.6 μm and a deformation rate of 1.89. Table 1 shows the evaluation results.

[0089]Examples 2 and 3  The metallic base paint of Example 1 with the composition shown in Table 1
Example using a metallic base paint manufactured in the same way
Metallic coating and metallic base single layer coating as in 1
Was prepared and evaluated in the same manner.

[0090]Examples 4 to 10  In the formulation shown in Table 1, Shanin Blue 5206 (large
Nissei Chemical Corporation blue pigment) and Shinkasha Magenta BRT-
343D (red pigment manufactured by Ciba-Geigy)
The aluminum pigment used in Example 1 was dispersed in Alpe
Strike MH-8801 (aluminum pigment manufactured by Asahi Kasei Corporation) and
And Alpaste MH-9901 (Aluminium manufactured by Asahi Kasei Corporation)
Pigment base) except for the metallic base of Example 1.
Using a metallic base paint manufactured in the same way as
In the same manner as in Example 1,
A single-layer coating film was prepared and evaluated in the same manner.

[0091]Comparative Examples 1-4  The crosslinked polymer fine particles used in Examples 1 to 10 or
Metallic base paint without using non-crosslinked polymer fine particles
And adjust the metallic coating and metallic
A base single-layer coating film was prepared and evaluated in the same manner.

Further, the shear rate (shear force) at the time of spray coating of the metallic base paint used in Comparative Examples 1 and 2 was 10
When the viscosity at (1 / sec) was measured in the same manner as in Example 1, the polish was 250 poise for the metallic base paint containing the crosslinked polymer fine particles of Comparative Example 1, and 120 poise for the metallic base paint containing the non-crosslinked polymer fine particles of Comparative Example 2. Met. Shedding speed (shearing force) at the time of coating 0.1 (1 / sec)
In Comparative Example 1, the metallic base paint containing the crosslinked polymer fine particles of Comparative Example 1 had a viscosity of 650 poise, and the metallic base paint containing the non-crosslinked polymer fine particles of Comparative Example 2 had a viscosity of 120 poise.

Further, particles of the spray paint of the metallic base paint used in Comparative Example 1 were captured by a liquid immersion method using silicone oil in the same manner as in Example 1, and the particle diameter was measured. At the same time, the diameter of the particles crushed by coating on the portion without silicon oil was measured, and divided by the previously measured particle size to determine the deformation ratio as a measure of the crushability. The metallic base paint containing the crosslinked polymer fine particles of Comparative Example 1 was found to have a paint particle size of 13.4 μm and a deformation rate of 1.46. Furthermore, the particle diameter of the paint particles in Comparative Example 2 was 1
It was 2.5 μm, and the deformation ratio was found to be 1.90. Table 1 shows the evaluation results of the above examples and comparative examples.

[0094]

[Table 1]

From the results in Table 1, it can be seen that Examples 1 to 5 according to the present invention were used.
By adding non-crosslinked polymer particles and crosslinked polymer particles to the metallic coating film of No. 10, the orientation and color reversion of the aluminum pigment contained in the obtained metallic base coating film were improved, and 2 coats were further added. The luster of the metallic coating film obtained by baking is also good.

That is, since fine return of the aluminum pigment can be suppressed, the coating film has no unevenness and a glossy coating film having a high flip-flop property is obtained. However, the system in which the non-crosslinked polymer particles of the comparative example did not enter had poor aluminum orientation, color return properties, and gloss.

Further, a shear rate (shearing force) of 10 (1 / sec.)
c) and the shear rate (shear force) 0.1 (1 /
From the difference in viscosity in sec), it can be seen that the structural viscosity of the combined system of crosslinked polymer particles and non-crosslinked polymer particles is the largest. This is remarkable in the particle size of the paint particles at the time of spray coating and the ease of crushing of the paint particles at the time of application, and this deformation ratio is higher in the case of the combined use of crosslinked polymer fine particles and non-crosslinked polymer fine particles. It means that the aluminum pigment is excellent in atomization and crushability, and indicates that the aluminum pigment is easily oriented in parallel with the coating surface.

[0098]

The metallic coating film obtained in the present invention can be obtained by using a non-crosslinked polymer fine particle and a crosslinked polymer fine particle together within the above range in a metallic base coating material. The appearance of structural viscosity is larger than that of the above, and the metallic base coating film and the clear coating film are mixed with each other, without causing color reversion, and the aluminum pigment is easily oriented parallel to the coating surface. It is possible to industrially stably form a metallic coating film having a strong flip-flop property, which significantly changes the feeling.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshio Tsuji 19-17 Ikedanakacho, Neyagawa-shi, Osaka Japan Paint Co., Ltd. F-term within the company (Reference) 4D075 AE06 CA04 CA33 CB04 CB13 DA06 DA25 DB02 DB05 DB06 DB07 DB13 DB31 DC12 DC13 EA06 EA07 EA13 EA43 EB13 EB14 EB19 EB20 EB22 EB32 EB33 EB35 EB36 EB37 EB38 EB38 EB38 EB38 EB38 EB45 CG45 CG082 CG141 CG142 CG182 CH122 DA112 DA161 DB001 DD001 DD002 DD121 DD122 DE002 DF022 DG001 DG002 DG101 DG111 DG161 DG191 DG302 EA011 HA026 HA036 HA066 HA216 HA286 HA376 HA526 HA536 HA546 KA03 KA07 KA08 KA09 MA20 MA14 MA15

Claims (3)

[Claims] A method for forming a metallic coating film for forming a metallic base coating film and a clear coating film on a base material on which an undercoating film and, if necessary, an intermediate coating film have been formed,
The metallic base coating film metallic base coating to form a can, and a non-crosslinked polymer microparticles with an average particle diameter (D ₅₀₎ 0.05 to 10 [mu] m, an average particle diameter (D ₅₀₎ 0.01~1μ
m, wherein the weight ratio of solid content between the non-crosslinked polymer fine particles and the crosslinked polymer fine particles is 5/1 to 1/5. Formation method. 2. A metallic base paint used in the method according to claim 1. 3. A metallic coating formed by the method according to claim 1.