JP2002224616A - Coating film forming method and base material having coating film by coating film forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating film forming method, in which a color of a car main body of an automobile is made different from plastic parts, an optical interfering flake pigment is used and a coating film exhibiting excellent designability is obtained with a reduced cost by the simplification of processes or the like without damaging the finish appearance. SOLUTION: The coating film forming method includes a process for applying a base coating material containing the optical interfering flake pigment on a base material having a metallic part and a plastic part and a process for applying a clear coating material and the difference of a L value of the surface- to-be coated of the metallic part from a L value of the surface-to-be-coated of the plastic part is 15-70.

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 coating film including a step of applying a base coating material containing a light interference flake pigment and a clear coating material, and more particularly, to a coating method suitably used for an automobile body having plastic parts. The present invention relates to a method for forming a film, and to a substrate having a film formed by the method for forming a film.

[0002]

2. Description of the Related Art In a coating film forming method in which an electrodeposition coating film is formed as an undercoat on an automobile body or parts, an intermediate coating film, a base coating film, and a clear coating film are sequentially formed thereon and baked and cured. If the base coating contains light-interfering flake pigments, it exhibits light interference polychroism, which is observed so that the color changes according to the angle of the incident light or the angle of viewing, so there is a need for various designs. It is expected to be used according to the requirements.

This light coherent flake pigment is disclosed, for example, in Japanese Patent No.
As disclosed in Japanese Patent No. 0526253, a translucent metal layer such as a chromium layer, a dielectric layer such as a magnesium fluoride layer, a metal reflective layer such as an aluminum layer, the translucent metal layer and the dielectric layer It has a multilayer structure formed in order.

[0004] On the other hand, an automobile is generally provided with a metal body such as a door and a hood and a plastic part such as a bumper and a mirror mounted on a body made of a steel plate. In this case, conventionally, plastic parts have a low heat-resistant temperature and may be deformed at the baking temperature applied to metal parts. Therefore, after applying and baking a conductive primer or a top coating paint separately from the vehicle body, the plastic parts may be deformed. Was attached to the vehicle body. However, in this method, different paints are required for plastic parts and metal parts because the baking temperature is different, and the number of steps is reduced because the painting and baking steps are performed for each vehicle body and each part. In many cases, there is a problem that colors do not slightly match between parts that are not simultaneously subjected to the painting and baking processes, and it has been desired to reduce the cost by using a common paint and reducing the number of processes.

[0005]

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a method for forming a coating film using a light-coherent flake pigment in which a vehicle body of an automobile and a plastic component are made to have different colors. It is an object of the present invention to provide a coating film forming method which can obtain a coating film having excellent designability without any problem and realize cost reduction by simplification of steps and the like.

[0006]

Means for Solving the Problems The present inventor has paid attention to the special design of a base paint containing a light coherent flake pigment so as to transmit the color of a base for a design that emphasizes a high design. As a method of using different base paints to make the vehicle body and the plastic part of an automobile different colors, a body part and a plastic part having a specific L value difference are pre-assembled, and the By applying the base paint and clear paint and baking and curing, the paint can be shared for plastic parts and for the vehicle body, making it possible to form a simple two-tone coating with fewer steps than before. The present inventors have found that a coating film having both a desired design property based on the light interference flake pigment and an excellent finished appearance can be obtained, and completed the present invention.

That is, the present invention relates to a method for forming a coating film comprising a step of applying a base paint containing a light interference flake pigment to a substrate having a metal part and a plastic part, and a step of applying a clear paint. The difference between the L value of the coated surface of the metal portion and the L value of the coated surface of the plastic portion is 15 to 70. The difference between the L values is preferably 15 to 60, and the substrate preferably has an L value of 75 or less on the surface to be coated. The base material has an L value difference of 15 to 70 on the surface to be coated.
It may be formed after separately adjusting the metal part and the plastic part so that

The light coherent flake pigment has a pigment weight concentration (PWC) of 6% by weight based on the solid content of the base paint.
If the clear paint is at least 1
In this case, the clear coating has a dry film thickness of 25 to 40 μm by one application.
It is preferably applied so that In the present invention, it is preferable that the metal portion of the base material is made of a vehicle body, and the plastic portion of the base material is made of a vehicle component. The present invention is also a substrate having a coating film formed by the above coating film forming method. Hereinafter, the present invention will be described in detail.

The coating film forming method of the present invention includes a step of applying a base paint containing a light interference flake pigment to a substrate having a metal part and a plastic part, and a step of applying a clear paint. The substrate used in the present invention has a metal part and a plastic part.

[0010] The metal portion is not particularly limited, and includes, for example, a simple metal such as iron, copper, aluminum, tin, and zinc, and an alloy and a cast containing the simple metal. Specifically, the vehicle body (body) and the vehicle parts (parts) such as doors and hoods, which are the main parts of vehicles such as passenger cars, trucks, motorcycles, and buses, may be mentioned. The base material may have two or more metal parts, and in this case, the material and shape of each part may be the same or different. It is particularly preferable that the metal portion has been subjected to a chemical conversion treatment with a phosphate, a chromate or the like in advance. On the steel sheet thus chemically treated, an electrodeposition coating film can be further formed using a cationic or anion type electrodeposition coating material. A cationic electrodeposition paint is preferred because it gives an excellent laminated coating.

Examples of the plastic part include a part composed of polypropylene resin, polycarbonate resin, urethane resin, polyester resin, polystyrene resin, ABS resin, vinyl chloride resin, polyamide resin and the like. From the viewpoint of enabling the above, those made of a non-three-dimensionally crosslinked product such as a polypropylene resin are preferable. Examples of the plastic part include vehicle parts such as a spoiler, a bumper, a mirror cover, a grill, a door knob, a fascia, a fender, and a back door. The base material may have two or more plastic parts. In this case, the material and shape of each part may be the same or different.

In the present invention, the plastic part is
It is preferable that the heat resistance temperature is 140 ° C. or higher. 140
When the temperature is lower than ℃, the heat-resistant temperature is too low, and when the film is formed by baking and hardening integrally with the metal part in the coating film forming method of the present invention, there is a possibility that deformation, alteration and the like may occur. Preferably, it is 160 ° C. or higher.

The above plastic part is preferably subjected to steam cleaning with trichloroethane or cleaning with a neutral detergent. Further, a conductive primer coating for enabling electrostatic coating is applied. ~ 30
It may be baked for minutes.

The above-mentioned metal part, or the above-mentioned metal part and the above-mentioned plastic part may be provided with the above-mentioned chemical conversion film if necessary.
An intermediate coating film may be further formed on the electrodeposition coating film or the primer coating film. When the intermediate coating film is formed, the defects of the base material and the electrodeposition coating film are concealed, the surface smoothness after the top coating is secured and the appearance is improved, and the impact resistance, chipping resistance, etc. It is easy to impart physical properties of the coating film. The intermediate coating material for forming the intermediate coating film is not particularly limited, but usually contains a pigment, a film-forming resin and a curing agent, and generally, a melamine-curable or isocyanate-curable resin is used. Can be

[0015] The coated surface of the at least one metal part and the coated surface of the at least one plastic part have different colors. Although such a case is not particularly limited, for example, a case in which the vehicle body, which is the metal part, and an automobile part, such as a bumper of a passenger car, which is the plastic part, have different colors, or the like.

The difference between the L value of the coated surface of the metal portion and the L value of the coated surface of the plastic portion is 15 to 70.
In the present invention, since the base coating film containing the light interference flake pigment easily transmits the color of the base, the coated surface of the metal portion and the coated surface of the plastic portion are in the above range. By having the L value difference, these colors having different lightness can be seen through the base coating film. As a result, in the finished appearance, the metal portion and the plastic portion are observed to have different colors.

If the difference between the L values is less than 15, the metal portion and the plastic portion may not be observed to have different colors. If the difference exceeds 70, the color of the metal portion and the plastic portion may not be observed. The colors may be too different from each other, giving an impression that the appearance is impaired. In addition, the portion having a higher L value has too high a lightness of the base, and the light based on the light coherent flake pigment which is applied thereon is superposed. Interference polychromaticity does not appear effectively. Preferably, it is 15 to 60.

When the metal portion forms two or more portions,
And / or when the plastic portion forms two or more portions, the color of the coated surface of at least one metal portion and the color of the coated surface of at least one plastic portion may be different from each other. L for two different colors
The difference between the values may be 15 to 70. In this case, the L value of the other color other than the two different colors is a value between the L values of the two colors, and the L value of the two colors is lower than the lower L value of the L values of the two colors. Alternatively, any of the two L values of the two colors may be higher than the higher L value.

In the case where the metal portion and / or the plastic portion each form two or more portions, the difference between all L values of the color of the coated surface of each portion is 15 to 70, that is, which 2 The difference in L value is also 15 in the combination of colors.
A value of from 70 to 70 is preferable because excellent two-tone appearance can be obtained in a well-balanced lightness of each color. Also, the coated surfaces of the two or more metal portions may have the same or different colors, and the coated surfaces of the two or more plastic portions may have the same or different colors.

It is preferable that any L value of the coated surface of the substrate having the metal portion and the plastic portion is 75 or less. If it exceeds 75, the lightness of the undercoat layer becomes too high, and the color of the undercoat layer excessively passes through the base coating film. The light interference is relatively weak, and the light interference polychromaticity is not clearly exhibited. If the light interference polychromaticity is to be obtained, it is necessary to increase the PWC of the light interference flake pigment, and the workability and This leads to a decrease in the finished appearance.
Preferably, it is 65 or less.

In order for the coated surface of the substrate to have an L value in the above range, for example, (a) a method of adjusting the L value of the intermediate coating film to 75 or less; A method of further providing a color base coating film whose L value is adjusted to the above range on a normal intermediate coating film, and (c) adjusting the L value to the above range by both the intermediate coating film and the color base coating film formed thereon. There is a method of adjusting the value. Of these, either (a) or (b) is preferable from the viewpoint of reducing the number of steps and the like. If the L value of the intermediate coating film is adjusted to the above range, a color base becomes unnecessary and cost reduction is achieved. In contributing to
The above (a) is more preferable. In order for the surface to be coated of the plastic part to have the L value in the above range,
It is also possible to adopt a method of adjusting by coloring the resin composition forming the plastic part.

The adjustment of the L value of the surface to be coated of these substrates can be carried out mainly with a coloring pigment. The color pigment for adjusting the L value is not particularly limited, and includes, for example, an azo chelate pigment, an insoluble azo pigment, a condensed azo pigment,
Monoazo pigment, disazo pigment, diketopyrrolopyrrole pigment, benzimidazolone pigment, phthalocyanine pigment, indigo pigment, thioindigo pigment, perinone pigment, perylene pigment, dioxane pigment, quinacridone pigment, iso Organic color pigments such as indolinone pigments, naphthol pigments, pyrazolone pigments, anthraquinone pigments, anthorapyrimidine pigments, metal complex pigments; graphite, yellow iron oxide, chromium oxide, molybdate orange, red iron, titanium White, titanium yellow, zinc white,
Carbon black, titanium dioxide, cobalt green,
And inorganic coloring pigments such as phthalocyanine green, ultramarine blue, cobalt blue, phthalocyanine blue, and cobalt violet.

The surface to be coated of the substrate may further contain a glitter pigment and / or extender. The glitter pigment is not particularly limited and includes, for example, colorless colored flats such as interference mica powder, colored mica powder, white mica powder, graphite, aluminum, colored aluminum, plate iron oxide pigment, plate graphite pigment, and glass flake. Pigment: a non-colored or colored metallic glitter such as a metal or alloy such as aluminum oxide, copper, zinc, iron, nickel and tin. The extender is not particularly limited, for example, calcium carbonate, barium sulfate, barium carbonate,
Extenders such as magnesium silicate, clay, talc, silica, and calcined kaolin; One or more of these can be used.

When the L value of the surface to be coated under the base coating film is 75 or less, the intermediate coating film may be, for example, the same as the intermediate coating film in the general coating film forming method. One or two or more of the system-based and inorganic-based color pigments and extender pigments may be used, and for example, a gray intermediate coating material containing carbon black and titanium dioxide as main pigments may be used. The method for preparing the above-mentioned electrodeposition paint, intermediate coating and color base paint is not particularly limited, and for example, conventionally known methods can be used.

The base material used in the present invention has the metal part and the plastic part, and the base material and the clear paint are integrally applied to the base material having these parts and baked and cured. Is done. Therefore, in the present invention, as described above, the difference in L value between the coated surface of the metal portion and the coated surface of the plastic portion is one.
It has a different color of 5 to 70, and the base coating film easily transmits the color of the base, so that the base material is integrally coated with the base paint or the like so that the metal portion and the plastic portion Have different colors from each other, and a coating film exhibiting light interference polychromaticity in each portion can be obtained by a simple method.

As a method of forming the base material, for example,
(A) As described above, a metal part whose L value is 75 or less, and which is separately adjusted so that the difference in L value of the coated surface of at least one metal part and at least one plastic part is 15 to 70. A method of forming a plastic part by assembling it by a known method or the like can be given.

In the above method (A), the intermediate coating and / or the color base coating is applied to each of the metal part and the plastic part,
After adjusting the values, it is preferable to perform baking and curing at 100 to 180 ° C., preferably 120 to 160 ° C., before forming the base material from both portions. The curing time varies depending on the curing temperature, but is suitably from 120 to 160 ° C. for 10 to 60 minutes. By the above-mentioned curing, a coat having excellent workability and a good finished appearance can be obtained in forming the base material from the metal part and the plastic part later.

In the case of the method (A), after the formation of the base material, the base paint described above and then the clear paint described above are applied integrally to the base material and baked and cured.
In this case, the clear coating can be applied after the base coating is cured under the same conditions as the baking conditions of the intermediate coating or the like, but from the viewpoint of reducing the number of steps, the base coating is applied. Without curing the film,
It is preferable to apply a so-called two-coat, one-bake method in which the upper surface is coated by a wet-on-wet method and then baked and cured at once.

In the case of the method (A), before the baking and curing of the intermediate coating film and / or the color base coating film and / or after the application of the base coating material and before the application of the clear coating material. A preheating step of leaving the coating film in advance by leaving it at room temperature for a certain period of time, or by heating it at, for example, 60 to less than 100 ° C. for 2 to 10 minutes, whereby a cured coating film having a high degree of crosslinking can be obtained. Can be

The method of forming the base material includes
(B) A method of forming the above-mentioned metal part on which a chemical conversion coating or an electrodeposition coating is formed as required and the above-mentioned plastic part on which a primer coating is formed as necessary by assembling by a known method or the like. Is mentioned.

In the case of the method (B), the intermediate coating and / or the color base coating are applied integrally to the base material including the metal portion and the plastic portion, and the L value is adjusted. . In adjusting the L value,
Normally, after applying the first color integrally to the base material including the metal portion and the plastic portion, the second color is applied to either the metal portion or the plastic portion of the obtained coating film. Thus, the difference between the L values is set to 15 to 70. The base coating film and the clear coating film are formed on the coating film thus obtained, and are baked and cured. In this case, from the viewpoint of cost reduction by reducing the number of steps, the intermediate coating film and / or the color base coating film, the base coating film, and the clear coating film are wet-on-
It is preferable to perform the so-called three-coat one-bake method, in which the coating is sequentially performed on a wet system and then baked and cured at a time. In this case, before the application of the base coating and / or the application of the clear coating, the coating may be left at room temperature for a certain period of time or may be subjected to the preheating step, whereby a cured coating film having a high degree of crosslinking is obtained.

The substrate used in the present invention may have another portion such as a foam portion in addition to the metal portion and the plastic portion.

The base paint used in the present invention contains a light interference flake pigment. The light coherent flake pigment is generally present in a coating film, for example, gold to green, green to crimson, green to blue, silver to green, depending on the angle of incident light or a change in viewing angle. It is observed that the color of the coating film gradually changes between each color such as gold to silver, blue to red, etc., and exhibits light interference polychromaticity. The light coherent flake pigment is, for example, a thin platelet having a multilayer structure including an interference structure, as disclosed in the above-mentioned Japanese Patent No. 3056253, and each platelet has a longest dimension of an outer surface. It is preferred that it has an aspect ratio of at least 2: 1, preferably 5: 1 with thickness, and has a maximum dimension of 2 to 200 μm on any side.

The interference structure generally has at least one metal reflective layer, one dielectric layer, and one translucent metal layer. As the interference structure, for example, (1) a structure (a) in which a semi-transparent metal layer, a dielectric layer, a metal reflection layer, a dielectric layer, and a semi-transparent metal layer are laminated in this order, The dielectric layers and the translucent metal layers are made of the same material and are symmetrical with respect to the thickness with respect to the metal reflective layer. (2) The laminated structure (a) and the two dielectric layers In the present invention, there are mentioned a structure in which the layer is asymmetric with respect to the thickness, (3) a structure in which a metal reflective layer, a dielectric layer and a translucent metal layer are laminated in this order, and the like. Is preferred.

The above-mentioned light interference polychromaticity is obtained by setting the dielectric layer to have an appropriate optical thickness according to a desired color, for example, 400 nm.
From a thickness of 2/4 wavelength at a design wavelength of か ら to a thickness of 6/4 wavelength at a design wavelength of 700 nm. As the metal reflection layer, for example, aluminum is often used, but gold, copper, silver, or the like may also be used.
The translucent metal layer can be formed from a metal such as chromium, nickel, or inconel. The dielectric layer,
It can be formed from silicon dioxide, magnesium fluoride, aluminum oxide, or the like.

The light coherent flake pigment is prepared by applying the above-mentioned semi-transparent metal layer, dielectric layer and metal reflection layer on a flexible web, separating the web from the multilayer structure, and forming a pigment free layer.
It is manufactured by forming a block. The web generally comprises a polymeric material, such as polyvinyl alcohol, polyethylene terephthalate, and the like. In order to perform the separation, it is preferable to deposit a release layer on the web by a known method and then apply the interference structure. As the release layer, for example, acrylic resin, cellulose propionate, polyvinylpyrrolidine / polyvinyl alcohol-
And an organic solvent-soluble or water-soluble coating film such as polyvinyl acetate. In the separation step, heat and / or
Alternatively, a solvent can be used. For example, the web can be separated by dissolving the web in an appropriate solvent such as water or an organic solvent according to the solubility of the material forming the web.

The multilayer structure having the interference structure generally breaks into a flake having an irregular shape and size when separated from the web. Generally, it is preferred that these flakes be further processed to provide the required size for the coating composition. The above treatment can be performed by a known technique, for example, ultrasonic stirring, pulverization or grinding. The light coherent flake pigment processed to the required size depends on the specific properties desired for the pigment, for example,
Each of said translucent metal layers is 50-150 °, preferably about 70 °.
金属, the metal reflective layer has a thickness of 80 to 500 Å, preferably about 100 、, and each of the dielectric layers has a thickness of a multiple of a half wavelength of a specific design wavelength. preferable.

Examples of such a light interference flake pigment include, for example, Flex Products (Flex Produ).
cts, Inc. Chroma Flare (Chroma)
Flair) series and the like. The chroma flare series includes, for example, gold / silver 080,
Red / Gold 000, Magenta / Gold 33
0, purple / orange 300, blue / red 28
0, cyan / purple 230, green / purple 19
0, silver / green 060 and the like.

In the present invention, the above-mentioned light interference flake pigment
As PASFIOCHROM Magic Series manufactured by BASF
For example, Magic Gold L-1400, Magic
Purple L-5520, Magic Red L-4420, etc.
Can also be used. Can be used in the present invention
Examples of the light interference flake pigment include JP-A-2-173162.
As disclosed in Japanese Patent Application Publication No.
A film is formed on the carrier by plasma
Pigment flakes produced, for example, in the visible region of the spectrum
To reflect or absorb light and transmit light with a wavelength of 2 to 4 μm.
Designed for SiO_Two Layers and alternately arranged Si layers
Or a multilayer film consisting of _Two / TiO_Two Multi-layer body
And other pigment flakes.

As the light coherent flake pigment which can be used in the present invention, as disclosed in Japanese Patent Application Laid-Open No. 3-120351, a thickness which can produce a desired color by light interference can be used. It is also possible to use a plastic molding additive obtained by pulverizing or shredding a substrate having an interference coating on the surface, for example, ZrO ₂ , ZnS, CeO on the surface of a substrate such as mica or aluminum foil.
₂ , high refractive film made of TiO ₂ , MgF ₂ , AlF ₂
A three-layer interference coating composed of a low-refractive-index film made of 3NaF, SiO ₂ , ThF ₄ , Al ₂ O _3, etc. and the above-mentioned high-refractive-index film formed, or the above-mentioned three-layered interference coating is formed by repeating the above plural times Can also be mentioned.

The amount of the light interference flake pigment is preferably 3 to 15% by weight as a pigment weight concentration (PWC) based on the solid content of the base paint. If it is less than 3% by weight, the PWC becomes too low, and it is difficult for the light interference polychromaticity based on the light interference flake pigment to be sufficiently exhibited.
If it exceeds 5% by weight, the PWC becomes too high, and the fluidity and workability of the coating material may decrease, or the physical properties of the coating film may deteriorate. More preferably, it is 3.5 to 12% by weight. P
When the WC is relatively high, depending on the brightness of the base under the base coating, generally, the obtained coating tends to be dark, and the light interference polychromaticity tends to appear more clearly. Is relatively low, the base coating film becomes light-colored, the transparency of the underlying color becomes high, and light interference polychromaticity tends to appear lighter, but these design properties are selected according to needs. be able to.

The base paint used in the present invention is not particularly limited as long as it contains the above-mentioned light interference flake pigment. For example, the base paint further contains a film-forming resin, a curing agent, a pigment and other additives. Can be listed. The film-forming resin is not particularly limited, for example, acrylic resin, polyester resin, alkyd resin,
Epoxy resins, urethane resins and the like can be mentioned, and these are usually used in combination with a curing agent such as an amino resin and / or a blocked isocyanate resin. The film-forming resin is preferably a combination of an acrylic resin and / or a polyester resin and a melamine resin from the viewpoint of pigment dispersibility and workability.

It is preferable that the coating film-forming resin is 20 to 80 parts by weight as a solid content based on 100 parts by weight of the solid content of the base paint. If it is less than 20 parts by weight,
The coating film becomes hard and brittle and may have poor physical properties.
When the amount exceeds the weight part, workability, appearance and physical properties of a coating film may be deteriorated.

As the curing agent used in the base paint,
Amino resins, blocked isocyanate resins, epoxy compounds, aziridine compounds, carbodiimide compounds, oxazoline compounds and the like are preferred, and mixtures can be used. An amino resin and / or a blocked isocyanate resin are particularly preferably used in view of various properties and cost of the obtained coating film.

The content of the curing agent is preferably from 15 to 100% by weight as a solid content based on the total solid content of the film-forming resin. If it is less than 15% by weight, curability tends to be insufficient, and if it exceeds 100% by weight,
The cured film may be too hard and brittle.

The amino resin is not particularly limited, and a methylated melamine resin, a butylated melamine resin, or a mixed melamine resin of methyl and butyl can be used. For example, "Symel series" such as "Symel-303" and "Symel 254", which are commercially available from Mitsui Chemicals, Inc .; and "Yuban series" such as "Yuban 226" and "Yuban 20N60";"Sumimarseries" commercially available from Co., Ltd. and the like.

The content of the amino resin is preferably 15 to 100% by weight, more preferably 20 to 100% by weight, based on the solid content of the film-forming resin.
% By weight. If it is less than 15% by weight, the curability will be insufficient, and if it exceeds 100% by weight, the cured film will be too hard and brittle.

The above-mentioned blocked isocyanate resin is obtained by adding a blocking agent having active hydrogen to polyisocyanate, and the blocking agent is dissociated by heating to generate an isocyanate group. Those which react with groups and cure.

The above-mentioned blocked isocyanate resin is not particularly limited, and typical polyisocyanates include:
Aliphatic isocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate;
Aliphatic cyclic isocyanates such as cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, and 1,2-cyclohexane diisocyanate; aromatic isocyanates such as xylylene diisocyanate, 2,4-tolylene diisocyanate, and 2,6-tolylene diisocyanate; Alicyclic isocyanates such as isophorone diisocyanate and norbornane diisocyanate methyl;
Multimers and mixtures of these nurate compounds can be used.

Examples of the blocking agent include aliphatic, aromatic and heterocyclic compounds such as halogenated hydrocarbons, methanol, ethanol, n-propanol, isopropanol, furfuryl alcohol, alkyl-substituted furfuryl alcohol and benzyl alcohol. Alcohols; oximes such as methyl ethyl ketone oxime, methyl isobutyl ketone oxime, acetone oxime and cyclohexane oxime; and caprolactam. Of these, oximes and alcohols are preferred. In the base paint, a catalyst for dissociating the blocking agent can be further used.

The amount of the blocked isocyanate is as follows:
The content is preferably 20 to 100% by weight, more preferably 40 to 100% by weight, based on the solid content of the film-forming resin. Outside the above range, curing is insufficient.

The pigments that can be used in the base paint used in the present invention can include other glittering pigments in combination with the above-mentioned light interference flake pigments. Pigments. By including these other brilliant pigments, various design properties can be exhibited in combination with the above-mentioned light interference flake pigment.

The brilliant pigment other than the above-mentioned light coherent flake pigment is not particularly limited in its shape and may be further colored. For example, the brilliant pigment may have an average particle size (D ₅₀ ) of 2 to ₅₀ μm.
It is preferable that the thickness is 0.1 to 5 μm.
Those having an average particle size of 10 to 35 μm are excellent in glitter and are more preferably used.

The brilliant pigment other than the above-mentioned light coherent flake pigment has a total amount of 3 to 23% by weight as a pigment weight concentration (PWC) based on the solid content of the base paint of the present invention. It is preferable to mix them so that
The blending amount of the light interference flake pigment / the other glittering pigment is preferably 100/0 to 50/50 in weight ratio. If the amount of the other brilliant pigments, especially the flat pigments such as mica powder, exceeds the above upper limit, the finished appearance may be inferior, such as excessive brilliancy.

The base coating material may contain an organic or inorganic coloring pigment as described in connection with the above-mentioned base material, and further, an extender pigment, in combination with the above-mentioned light interference flake pigment. These may be used alone or in combination of two or more.

Of these, by using the above-mentioned organic coloring pigment in combination with the above-mentioned light coherent flake pigment, it is possible to exhibit a design property in which light interference polychromaticity is suppressed, thereby expanding the variety of design properties. Thus, the range of selection can be expanded according to the needs of the user. The method of the combination is not particularly limited, but in the Munsell display, the light interference flake pigment exhibiting light interference polychroism observed as the color shifts between the highlight color and the shade color, the highlight color When at least one kind of color pigment that independently presents any hue between the shade color and the shade color, the color presented alone of the color pigment alone is emphasized as a whole,
The light interference flake pigment is preferable because the degree of light interference polychroism exhibited by the light interference flake pigment alone can be suppressed.

The compounding amount of the coloring pigment in the above combination is preferably 1 to 30 parts by weight based on 100 parts by weight of the light coherent flake pigment as a solid content, and 100 parts by weight of the solid content of the base paint. The amount is preferably 0.2 to 5.0 parts by weight with respect to the weight. Below these lower limits, the diversification of the design by adding the coloring pigment may not be realized effectively, and above the upper limit, the light interference polychromaticity based on the light interference flake pigment is suppressed. Too much
It is not efficient in diversifying design.

As the above combination, for example, chroma flare green / purple (manufactured by Flex Products), which exhibits green as the highlight color and purple as the shade color, is used alone as the light coherent flake pigment. When used together with Fasten Blue 10GN (manufactured by Dainippon Ink and Chemicals, Inc.), which independently exhibits blue, which is a color between green and purple in the hue circle, as an organic color pigment, the overall color tone is On the other hand, while the latter independently exhibits blue, the degree of light interference polychroism inherent in the former is suppressed.

The pigment weight concentration (PWC) based on the solid content of the base paint including the light interference flake pigment, other glitter pigments and all other pigments is generally 3 to 5%.
0% by weight, preferably 4 to 40% by weight. 5
If it exceeds 0% by weight, physical properties of the coating film are inferior.

The base paint used in the present invention may contain additives in addition to the above-mentioned components. The additive is not particularly limited, and examples thereof include a viscosity control agent in order to ensure coating workability. The viscosity control agent is not particularly limited, but those generally exhibiting thixotropic properties can be used.For example, crosslinkable or non-crosslinkable polymer fine particles, swelling dispersion of fatty acid amide, amide-based fatty acid, long-chain polyamino acid Polyamides such as amide phosphates; polyethylenes such as colloidal swelling dispersions of polyethylene oxide; organic bentonites such as organic acid smectite clay and montmorillonite; inorganics such as aluminum silicate and barium sulfate Pigment; flat pigments which exhibit viscosity depending on the shape of the pigment; As the above-mentioned additive, in addition to the above-mentioned viscosity control agent, an additive which is usually added to a paint, for example, a surface conditioner, an antioxidant, an antifoaming agent, etc. may be blended. The amounts used are those commonly used by those skilled in the art.

The total solid content of the base paint of the present invention is 10
It is preferably about 70% by weight. If the amount is less than 10% by weight, the viscosity is too low, causing poor appearance such as conformity and unevenness. If the amount is more than 70% by weight, the viscosity may be too high and the appearance of the coating film may be deteriorated. Preferably, it is 15 to 60% by weight.

The form of the base paint may be water-soluble, water-dispersible, or an aqueous type comprising an emulsion.
Any of an organic solvent type, a non-aqueous dispersion type, and a powder type may be used. The method for producing the base paint of the present invention is not particularly limited. For example, a method known to those skilled in the art, such as dispersing a compound such as a pigment using a pigment dispersing resin or the like as desired, can be used.

In the method for forming a coating film of the present invention, the above-mentioned base paint is applied to the above-mentioned substrate, and then a clear paint is applied. The clear coating is not particularly limited, and includes, for example, a coating composed of a film-forming resin, a curing agent, and other additives. The film-forming resin is not particularly limited, and includes, for example, an acrylic resin, a polyester resin, an epoxy resin, a urethane resin and the like, and these are used in combination with a curing agent such as an amino resin and / or a blocked isocyanate resin. . In terms of transparency or acid etching resistance, acrylic resin and / or
Alternatively, it is preferable to use a combination of a polyester resin and an amino resin, or an acrylic resin and / or a polyester resin having a carboxylic acid / epoxy curing system.

In the method for forming a coating film of the present invention, the clear paint is preferably applied after the base paint is applied.
Since the coating is performed in an uncured state, it is preferable to contain the viscosity control agent described for the base coating, in order to prevent the adaptation, inversion, and sagging between the layers. The addition amount of the viscosity control agent is preferably 0.01 to 10 parts by weight based on 100 parts by weight of the resin solid content of the clear coating. If the amount is less than 0.01 part by weight, the effect of controlling the viscosity cannot be obtained, which may cause problems such as sagging. If the amount exceeds 10 parts by weight, the appearance tends to deteriorate. More preferably, it is 0.02 to 8 parts by weight, and still more preferably, 0.1 to 8 parts by weight.
03 to 6 parts by weight.

The solid content in the clear coating is preferably 30 to 80% by weight, more preferably 40 to 80% by weight.
The solid content at the time of coating is preferably 25 to 75% by weight, and more preferably 30 to 70% by weight.

The form of the clear coating may be any of water-soluble, water-dispersible or water-based emulsions, organic solvents, non-aqueous dispersions and powders.
If necessary, a curing catalyst, a surface conditioner and the like can be used. The method for preparing the clear coating is not particularly limited, and for example, a conventionally known method can be used.

The above intermediate paint, the above color base paint,
The method for applying the base paint and the clear paint is not particularly limited, and for example, a method known to those skilled in the art can be used. Such a method includes, for example, an air electrostatic spray commonly referred to as a “react gun”; a rotary atomization commonly referred to as a “micro-micro (μμ) bell”, a “micro (μ) bell”, a “metabell” and the like. It can be performed by using a type electrostatic coating machine or the like. Preferably, a method using a rotary atomization type electrostatic coating machine or the like is used.

When the base paint is applied to an automobile body or the like, in order to enhance the design, multi-stage painting by air electrostatic spraying, preferably two-stage painting, or air electrostatic spraying is used. It is preferable to carry out by a coating method combining the above-mentioned and the above-mentioned rotary atomizing type electrostatic coating machine.

In the clear coating, the light coherent flake pigment has a pigment weight concentration (P) based on the solid content of the base coating.
If it exceeds 6% by weight as WC), at least 2
It is preferable to apply it once. In the case of once or less, the light interference flake pigment having a multilayer structure as described above is about 1 to 100
Since the film has a thickness of as much as μm, it has a cresting state on the surface of the finished coating film, and the finished appearance and physical properties of the coating film tend to be inferior. In the present invention, it is sufficient to apply the clear paint twice in order to eliminate the above-mentioned state of cueing. If the number of coatings is three or more, the effect corresponding to the number of coatings cannot be obtained, so that it is uneconomical and contravenes the simplification of the process. In addition, the finished appearance such as coloring may be rather poor.

In the clear coating, the light coherent flake pigment has a pigment weight concentration (P) based on the solid content of the base coating.
When WC) is 6% by weight or less, it is preferable to apply at least once. The light coherent flake pigment has a relatively thick shape as described above. However, when the PWC is at most 6% by weight, no cue is formed on the finished coating film. It is sufficient to apply the clear paint once, which can further simplify the process. Therefore, it is possible to apply the coating two or more times, but it is not necessary in terms of economy and simplification of the process. In the present invention, as described above, by selecting the number of times of application of the clear coating according to the PWC of the light coherent flake pigment, both excellent finished appearance such as smoothness and economy and simplification of the process can be achieved. can do.

The dry film thickness of each of the above-mentioned coating films varies depending on the application, but is respectively an intermediate coating film of 5-45 μm, a color base coating film of 5-35 μm, and a base coating film of 5-35 μm. 10 to 80 μm in total film thickness, 25 to 40 μm as a clear coating film by one application
m. Exceeding these upper limits may result in poor image clarity or inconveniences such as unevenness and flow during coating. Below the lower limit, the unevenness of the base may not be concealed and the film may break.

The baking hardening after the application of the clear paint can be carried out usually at 100 to 180 ° C., whereby a cured coating film having a high crosslinking density can be obtained. If the temperature is lower than 100 ° C., the curing is not sufficient. If the temperature is higher than 180 ° C., the coating film becomes hard and brittle, and the above-mentioned plastic part may be deformed or deteriorated. Preferably, 12
0-160 ° C. The curing time varies depending on the curing temperature, but is suitably from 120 to 160 ° C. for 10 to 60 minutes.

The total thickness of the base coating film and the clear coating film and the intermediate coating film and the color base coating film as required is usually 30 to 30.
0 μm. If it exceeds 300 μm, the physical properties of the film such as a thermal cycle decrease, and if it is less than 30 μm, the strength of the film itself decreases. Preferably, it is 50 to 250 μm.

In the method for forming a coating film of the present invention, the difference between the L value of the coated surface of the metal portion and the L value of the coated surface of the plastic portion is 10%. Since the method includes a step of applying a base paint containing a light interference flake pigment to a base material
As described above, the metal part and the plastic part have different color tones of different tones, and a coating film having an excellent appearance having a design property in which the color is transferred to multiple colors based on the light interference flake pigment is obtained, It can respond to various design needs.

The method for forming a coating film according to the present invention further comprises a step of integrally applying the base coating material and then the clear coating material to a base material previously formed from the metal portion and the plastic portion, and baking and curing the base coating material. Therefore, it can be performed by a simpler process than a conventional coating film forming method in which a base coating film and a clear coating film are separately formed on a metal portion and a plastic portion and baking and curing are performed separately. Since the coating film forming method of the present invention has such advantageous effects, in particular, in order to manufacture a vehicle such as a passenger car having a plastic part in a different color from other parts,
It is preferably applied.

[0076]

The present invention will now be described in detail with reference to specific examples.
However, the present invention is limited by these.
There is no. Parts and% mean parts by weight and% by weight, respectively.
You.Production example Production of base paint  Thermosetting acrylic resin (hydroxyl value 45, acid value 15mgK
OH / g, number average molecular weight 21,000, solid content 50%, day
126.0 parts, butylated melamine resin
(Youban 20N60, solid content 60%, manufactured by Mitsui Toatsu)
45.0 parts, 0.2 part of acrylic surface conditioner, cross-linked resin
Particles (structure viscosity imparting agent, solid content 20%, Nippon Paint Co., Ltd.
35.0 parts, n-butanol 2.2 parts, toluene
2.4 parts and the pigment were mixed to produce a base paint. face
As the pigment, light interference flake pigment (Chroma Flare Green)
/ Purple (GR / P) # 190, flexpro
Pigment weight concentration based on solid content of base paint
(PWC) 6.0% by weight, a black pigment (Raben 5)
000 Ultra 3, Carbon black made by Columbia)
With PWC 0.3% by weight and a blue pigment (Fast Genbu)
Lou 10GN, manufactured by Dainippon Ink and Chemicals, Inc.)
0.7% by weight was used.

[0077]Example  (Coating film forming method) 1) After treating a steel plate automobile body with zinc phosphate,
Thion electrodeposition paint (Power Top U-50, Nippon Paint
Co., Ltd.) to a dry film thickness of 20 μm.
For 30 minutes. 2) Meanwhile, bumpers and fenders made of polypropylene resin
-, Rear spoilers, door mirrors, etc.
Resin accessories, conductive primer (dark gray, Japan
Spray (Paint Co., Ltd.) to a dry film thickness of 30 μm.
-Painted and cured by heating at 100 ° C for 20 minutes.

3) The above-mentioned automobile body to which the resin accessory parts are attached is conveyed by a conveyor, and in the intermediate coating zone, the resin accessory parts and the body are integrated with the gray melamine-curable polyester resin. A paint (Olga P-2 Gray, manufactured by Nippon Paint Co., Ltd.) is spray-coated so as to have a dry film thickness of 30 μm.
After standing for minutes, it was cured by heating at 140 ° C. for 20 minutes.
When the L value was measured using Minolta CR-300 (manufactured by Minolta), it was 60. Next, a dark gray melamine-curable polyester resin intermediate coating (Olga P-2) was applied to the resin accessory part of the resulting intermediate coating.
Dark gray, manufactured by Nippon Paint Co., Ltd.)
m, and apply at room temperature about 3 times.
After standing for minutes, it was cured by heating at 140 ° C. for 20 minutes.
The L value of the obtained resin accessory part was 30.

4) The base paint obtained in the production example was integrated with the obtained resin accessory parts and body to a dry film thickness of 1
Two-stage coating was performed in the base coating zone using an internally applied metabell to an applied voltage of −60 kV, a rotation speed of 25,000 rpm, a shaving air pressure of 3.5 kg / cm ² , and a discharge rate of 250 cc / min so that the thickness became 5 μm. 2
1.5 minutes interval between each application
The setting was performed for 7 minutes after the second application. 5) Next, the object to be coated is transported to the clear coating zone,
Wet-on-wet clear paint (Super Lac O-381 Clear, Nippon Paint Co., Ltd. acid / epoxy curable acrylic resin paint) with dry film thickness of 30μ
m, a 1-stage rotary atomization type electrostatic coating is performed using a micro-micro bell at an applied voltage of -90 kV, a rotation speed of 25,000 rpm, a shaving air pressure of 1.5 kg / cm ² , and a discharge amount of 280 cc / min. For 7 minutes. 6) Finally, the obtained coated product is dried in a dryer at 140 ° C. for 20 minutes.
Baking was carried out for a minute to obtain a coating film for evaluation.

(Evaluation) Appearance The finished appearance of the obtained coated article was evaluated by G value (SW) of wave scan (manufactured by Big Chemie). The G value of the horizontal part of the body / the vertical part of the body / the vertical part of the resin accessory was 12/16/16. The smaller the value, the better the appearance was obtained. 2. Designability The resulting finished coating film was visually evaluated for designability. The resin accessory had a distinctly different color from the body. Regarding the light interference polychromaticity, the body was light-colored, the resin accessory was sufficiently dark, and all were good.

[0081]Comparative example  According to the same method as 2) for the body obtained by the coating film forming method 1)
Without assembling the obtained resin accessories
And separately performing the above steps 3) to 6).
Other than that, after painting and baking as in the example,
Attach the resin accessory parts to the body,
evaluated. Horizontal part of body / Vertical part of body /
The G value of the vertical part of the resin accessory is 12/16/16
there were. The design was equivalent to that of the examples.

The method of forming a coating film in the example was simpler than the comparative example in that the step of applying and baking a base paint and a clear paint did not need to be performed separately for each component. The coated product obtained in the example was as good as the comparative example in both the finished appearance and the design.

[0083]

According to the method for forming a coating film of the present invention having the above-mentioned structure, a plastic part and a metal part are used in a coating system in which the above-mentioned light coherent flake pigment is used to make the plastic part a different color from the metal part. Each part has a different hue, each part also has light interference polychromaticity, a variety of excellent coatings that achieve both good design and finished appearance, a two-tone coating finish in a wide range and simple process In particular, in the case of painting a vehicle such as a passenger car, it is possible to meet a wide variety of customer needs for designability, and it is also excellent in economical efficiency such as cost reduction.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI theme coat ゛ (reference) C09D 201/00 C09D 201/00 F term (reference) 4D075 CB08 CB36 CB40 DB02 DC12 EA43 EC11 EC23 EC54 4F100 AA37H AB01A AB03 AK01A AK07 AK25 AK36 AK41 AL05 AL06 BA03 BA04 BA05 BA10A BA10C BA13 CA13B CC00B CC00C GB32. PC02 PC08

Claims (8)

[Claims] 1. A method for forming a coating film comprising a step of applying a base paint containing a light interference flake pigment to a substrate having a metal part and a plastic part, and a step of applying a clear paint. A coating film forming method, wherein the difference between the L value of the coated surface of the portion and the L value of the coated surface of the plastic portion is 15 to 70. 2. The method according to claim 1, wherein the difference between the L values is 15 to 60.
The method for forming a coating film according to the above. 3. The coating film forming method according to claim 1, wherein the substrate has an L value of 75 or less on a surface to be coated. 4. The substrate according to claim 1, wherein the difference in L value of the surface to be coated is 15 to 70.
The coating film forming method according to claim 1, wherein the metal portion and the plastic portion are separately adjusted so as to be formed, and then formed. 5. The light interference flake pigment has a pigment weight concentration (PWC) of 6% by weight or less based on the solid content of the base paint, and the clear paint is applied at least once. Or the coating film forming method according to 4. 6. The coating film forming method according to claim 5, wherein the clear coating is applied so that the dry film thickness is 25 to 40 μm by one application. 7. The metal part of the base material comprises a vehicle body, and the plastic part of the base material comprises a vehicle part. Coating film forming method. 8. A substrate having a coating film formed by the coating film forming method according to claim 1, 2, 3, 4, 5, 6, or 7.