JPH10216620A - Production of coating film and coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a coating film having excellent uniformity and easy toning property and to provide a coating film. SOLUTION: After an opaque coating material is applied on the surface of a body to be coated, a light-transmitting powder coating material having different color from that of the opaque coating material is applied on the coated layer. Or, an opaque powder coating material is mixed with a light-transmitting powder coating material having different color from that of the opaque powder coating material and having <=1/2 particle size in comparison with that of the opaque powder material, and then the mixture is applied on the objective body and molten. Thus, a coating film with controlled tone can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toned paint film and a paint film.

[0002]

2. Description of the Related Art Powder coatings that do not require a solvent have attracted attention as pollution control coatings that do not adversely affect the danger of fire, environmental pollution, etc., as compared with other solvent-based coatings.
However, in the production of powder coatings, curing agents, leveling agents,
Pigments and the like are mixed by a mixer, the mixture is melt-kneaded by an extruder or the like, and then many steps such as cooling, pulverization, and classification are performed. Therefore, in order to produce paints of various colors, it is necessary to perform the above-mentioned work process for each paint of each color, which requires a great deal of time and labor.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 8-143788 discloses a method of forming a coating film having a uniform color simply by applying and fusing two or more kinds of powder coating materials having different colors. A method is disclosed. Also, JP-A-8-183
No. 916 discloses a highly transparent powder coating containing a polyolefin resin and an organic pigment uniformly mixed therein.

Further, JP-A-7-188586 discloses that two or more colors of primary color powder coating having an average particle diameter of 10 μm or less are dry-mixed without melting and color matching is performed.
Next, a method of granulating to a particle size in a range suitable for coating is disclosed.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. Hei 7-188 is disclosed.
The powder coating disclosed in Japanese Patent No. 586 and JP-A-8-143788 is opaque and has a hiding power so as not to be affected by the color of the base material to be coated. However, even if this opaque powder paint is dry-mixed in two or more colors,
It is difficult to uniformly mix the powder coatings of the respective colors, and color spots and the like are generated due to aggregates, which is a cause of impairing color uniformity.

On the other hand, the powder coating disclosed in Japanese Patent Application Laid-Open No. 8-183916 has a high transparency in order to utilize the surface cosmetics of the object to be coated. There is no disclosure of a method for toning the film. An object of the present invention is to provide a method for producing a coating film having excellent uniformity and easy toning, and a coating film.

[0007]

According to the present invention, there is provided a method for producing a coated film, comprising: applying an opaque paint to the surface of an object to be coated; And a translucent powder paint having a different color is applied. According to the present invention, since a light-transmitting coating film is formed on an opaque coating film and toning is performed, a coating film having a uniform tint without color spots due to agglomerates can be obtained. Since it is easy to control the film thickness of the light-sensitive coating film, the color can be easily adjusted.

For forming an opaque coating film in this manufacturing method, it is preferable to use an opaque powder coating from the viewpoint of toning and working efficiency. Another production method of the present invention is to provide an opaque powder coating, and a translucent powder coating that is different in color from the opaque powder coating and has a particle diameter of 1/2 or less than the opaque powder coating. After mixing, the mixture is applied to an object to be coated and melted.

That is, by setting the particle size of the translucent powder coating to 1/2 or less of the particle size of the opaque powder coating as described above, the surface of the opaque powder coating has a large number of translucent particles. A mixture is formed on which the volatile powder coating adheres. Therefore, when the mixture is applied and melted on the object to be coated, the translucent powder coating adhered to the surface of the opaque powder coating particles, the translucent powder positioned on top of the opaque powder coating. With the powder coating, a light-transmitting coating is formed on the opaque coating, and a toning coating in which the respective colors of both powder coatings are uniformly mixed is obtained.

The average particle size of the light-transmitting powder coating used in the other production method of the present invention is preferably 20 μm or less in order to provide a uniform coating film without spots. Furthermore, the toned coating film of the present invention is obtained by laminating an opaque colored film and a colored film having a light-transmitting property of a different color from the colored film on the object to be coated in this order. It is characterized by the following.

Since the coating film of the present invention is formed by forming a light-transmitting coating film on an opaque coating film and performing color matching, a coating film having a uniform tint without color spots due to agglomerates is obtained. Since it is easy to control the thickness of the obtained light-transmitting coating film, the color can be easily adjusted.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing a coating film according to the present invention will be described with reference to the drawings. The methods for producing the two coating films of the present invention are referred to as production method A and production method B. (Manufacturing Method A) FIGS. 1A to 1C show the order of forming coating films by this manufacturing method A. First, as shown in FIG. 1A, an opaque powder coating material 2 is applied on an object 1 to be coated.
Next, as shown in FIG. 1B, an opaque powder coating 2 and a translucent powder coating 3 having a different color are applied. Thereafter, as shown in FIG. 1C, the opaque powder coating 2 and the translucent powder coating 3 are melted by heating, and the translucent coating 5 is formed on the opaque coating 4. To form

When a viewer views the coating film formed by such a manufacturing method, the viewer sees the color of the opaque coating film 4 through the color of the light-transmitting coating film 5 having a different color. As a result, the colors appear uniformly mixed. In the above-mentioned production method A, the opaque powder coating 2 and the translucent powder coating 3 are simultaneously melted to form a coating film. Apply
The same coating film as described above can also be formed by applying and melting the translucent powder coating material 3 on the opaque coating film 4 obtained by melting.

Further, the opaque coating film 4 can be formed in a similar manner by applying a solvent-based coating material using an organic solvent or water as a solvent or a dispersion medium to an object to be coated. In the production method A of the present invention, the thickness of the translucent coating film 5 having different colors formed on the opaque coating film 4 can be controlled by multi-coating or the like, so that the degree of subtle toning can be adjusted. Become. The film thickness of the opaque coating film 4 that can be adjusted by the above-mentioned production method A is usually 30 to 200 μm, preferably 50 to 150 μm. The thickness of the light-transmitting coating film 5 is usually 20 to 100 μm, preferably 30 to 70 μm.
It is.

The particle size of the opaque powder coating material 2 used in the production method A of the present invention is 20 μm or more, preferably 40 to
It is 200 μm, more preferably 40 to 100 μm.
Further, the particle size of the translucent powder coating material 3 is 10 μm or more,
Preferably it is 10 to 100 μm, more preferably 10 to 100 μm.
60 μm. (Manufacturing Method B) FIGS. 2A to 2C show a coating film forming order in this manufacturing method B. First, as shown in FIG. 2 (a), an opaque powder coating 6 and a translucent powder coating 7 having a particle diameter of 1/2 or less than the particle diameter of the opaque powder coating 6. Is applied to the object 8 to be coated.

That is, the use of the opaque powder coating 6 and the light-transmitting powder coating 7 having a particle diameter of 1/2 or less than that of the opaque powder coating 6 allows the opaque powder coating 6 to be used. A mixture having a large number of light-transmitting powder coatings 7 adhered to the surface thereof. If the particle size of the translucent powder coating 7 is larger than 1/2 of the particle size of the opaque powder coating 6, a large number of translucent powder coatings 7 adhere to the surface of the opaque powder coating 6. It is difficult to form a mixed mixture. Therefore, even if this mixture is melted, the light-transmitting coating film 10 is not easily formed on the opaque coating film 9.

As shown in FIG. 2B, when this mixture is heated and melted, the mixture shown in FIG. 2C is formed by the translucent powder coating 7 attached to the upper part of the opaque powder coating 6. As described above, since the translucent coating film 10 is formed on the upper side of the opaque coating film 9, the eyes of the observer can see the color of the opaque powder coating material 6 with the translucent powder coating material 7. This is because the color of the film having the same color appears as the color of the coating film that is uniformly mixed.

The particle size of the opaque powder coating material 6 used in the production method B is 20 μm or more, preferably 40 to 20 μm.
0 μm, more preferably 40 to 100 μm. The particle size of the translucent powder coating 7 is 20 μm or less, preferably 20 to 1 μm, more preferably 10 μm.
３3 μm. When the particle size of the translucent powder coating 7 is 2
If it is larger than 0 μm, the coating film becomes mottled, which causes loss of color uniformity.

Further, as described in an embodiment described later,
By changing the mixing ratio of the translucent powder coating 7 to the opaque powder coating 6, the degree of subtle toning can be adjusted. Hereinafter, the paint used in the present invention will be described in detail. The opaque powder coating and the translucent powder coating used in the production method of the present invention include, for example, a coloring agent and, if necessary, a curing agent and a smoothing agent in a binder resin,
The mixture is mixed by a mixer, melt-kneaded by an extruder or the like, and then manufactured by a process of pulverization and classification.

The mixing of the opaque powder coating and the translucent powder coating is performed by a Henschel mixer, a dry blender, a ball mill, or the like. As a result, a mixture in which the light-transmitting powder coating is adhered to the surface of the opaque powder coating is obtained. (Binder Resin) As the binder resin, various conventionally known resins can be used. For example, polystyrene, acrylic resin, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene −
Propylene copolymer, styrene-butadiene copolymer,
Styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene
Acrylic ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer,
Styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-ethyl methacrylate copolymer, (styrene-ethyl methacrylate copolymer, styrene- Butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α-methyl methacrylate copolymer, styrene-acrylonitrile-
Styrene-based resins such as acrylate copolymers (homopolymers or copolymers containing styrene or styrene substituents), polyvinyl chloride, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-ethyl acrylate copolymer, polyvinyl Butyral, ethylene-vinyl acetate copolymer, rosin-modified maleic resin, phenolic resin,
Epoxy resin, polyester resin, ionomer resin,
Examples thereof include a polyurethane resin, a silicone resin, a ketone resin, a xylene resin, and a polyamide resin, and these can be used alone or in combination of two or more.

The translucent powder coating used in the production method of the present invention is preferably a binder resin having high transparency and good pigment dispersibility among the above binder resins. Further, as the opaque powder coating used in the toning method of the present invention, a known powder coating or a powder coating prepared using a commercially available binder resin may be used. The opaque powder coating used in the method for producing a coating film of the present invention is a light-transmitting powder in order to improve the compatibility of the resins with the opaque powder coating and enhance the interlayer adhesion. It is preferable to use the same kind of resin as the paint.

Polyester resins and acrylic resins are examples of resins having high transparency and good pigment dispersibility. In such a resin, even if the content of the pigment is set to be about the same as or higher than that of a usual powder coating material, the transparency of the coating material is not impaired. The polyacrylic resin is obtained by copolymerizing acrylic acid or methacrylic acid, or an alkyl ester thereof. Examples of the alkyl include methyl, ethyl, butyl, isobutyl, n-
Hexyl, n-octyl, lauryl, stearyl and the like can be mentioned.

The above polyester resin has the following general formula (i):
(1):

[0024]

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(Wherein R ¹ and R ² are the same or different and represent a lower alkylene group. X and y are the same or different and represent 0 or an integer of 1 or more, provided that x and y are not simultaneously 0) X + y is 1 to 7), and (ii) a dicarboxylic acid;
(Iii) 3 acid anhydrides or lower alkyl esters thereof;
It is obtained by co-polycondensation of a polyvalent carboxylic acid having a valency of 3 or more, an anhydride thereof or a lower alkyl ester thereof, or a polyhydric alcohol having a valency of 3 or more.

The ratio OHV / AV of the hydroxyl value (OHV) to the acid value (AV) of the polyester resin is 1.2 or more, preferably 1.2 to 50, more preferably 2 to 40.
When the OHV / AV is less than 1.2, there are many acidic groups at the terminals, and complete melting (referred to as “sharp melt”) at a certain temperature is stopped, so that the minimum melting temperature of the resin becomes high and the fluidity of the powder coating becomes poor. The problem of lowering occurs.

The acid value (AV) of the polyester resin is
It is an index indicating the content of free acid in the resin, and represents the amount of potassium hydroxide required to neutralize the free acid in mg per 1 g of the polyester resin.
Further, the hydroxyl value (OHV) is an index indicating the content of the hydroxyl group in the polyester resin, and the amount of potassium hydroxide required for acetylating the hydroxyl group and neutralizing acetic acid required for the acetylation. Is expressed in mg per 1 g of the sample.

The acid value (AV) and the hydroxyl value (OHV) are calculated according to JIS.
It has been determined according to the method described in K0211. In the diol component represented by the general formula (1), examples of the lower alkylene group corresponding to R ¹ and R ² include carbon atoms such as methylene, ethylene, trimethylene, propylene, tetramethylene, ethylethylene, pentamethylene, and hexamethylene. Groups of Formulas 1 to 6 are mentioned.

In the diol component represented by the general formula (1), x + y is 1 to 7, preferably 3 to 5. x + y
Exceeds 7, there is a problem that the molecular weight of the diol component becomes too large and the transparency of the coating film decreases. However, the range of x + y described above is an average value. General formula (1)
As the diol component represented by, for example, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3)-
2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2) -polyoxyethylene (2) -2 , 2-bis (4
-Hydroxyphenyl) propane, polyoxypropylene (6.0) -2,2-bis (4-hydroxyphenyl) propane and the like.

In addition to the diol component represented by the general formula (1), for example, hydroquinone, ethylene glycol, diethylene glycol, triethylene glycol, 1,2
-Propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, bisphenol A, hydrogenated Other diol components such as bisphenol A may be added. The other diol component is used in a proportion of about 10 mol% or less of the polyhydric alcohol component in the raw material of the polyester resin.

As the dicarboxylic acid, for example, oxalic acid,
Examples include malonic acid, succinic acid, itaconic acid, glutaconic acid, adipic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and the like. These dicarboxylic acids may be esters with acid anhydrides or lower alkyls. As the lower alkyl group, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-
1-6 carbon atoms such as butyl, n-pentyl, n-hexyl, etc.
Alkyl group.

Examples of the trivalent or higher polycarboxylic acid, its acid anhydride or lower alkyl ester include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid,
2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methoxycarbonylpropane, tetra (methoxycarbonyl) methane, 1,2,7,8- Octanetetracarboxylic acid and the like.

Examples of the trihydric or higher polyhydric alcohol include glycerin, 2-methyl-1,2,3-propanetriol, 1,2,4-butanetriol and 2-methyl-
1,2,4-butanetriol, 1,2,5-pentatriol, pentaerythritol, dipentaerythritol, tripentaerythritol, hexitol, sorbitol, 1,4-sorbitan, 1,2,4-benzenetriol and the like. Can be

The above-mentioned trivalent or higher polyvalent carboxylic acid, its acid anhydride or lower alkyl ester, and the trivalent or higher polyhydric alcohol are obtained by setting the acid value and hydroxyl value of the polyester resin to predetermined values. The polyester resin is blended for the purpose of forming a three-dimensional network, and is used in an amount of about 5 to 60 mol% of the polyvalent carboxylic acid component in the raw material of the polyester resin.

The polyester resin used in the method for producing a coating film of the present invention can be obtained by polycondensing the above components at a temperature of 180 to 250 ° C. in an inert gas atmosphere, for example. During the reaction, an esterification catalyst usually used for the purpose of accelerating the reaction, for example, zinc oxide,
Stannous oxide, di-n-butyltin oxide, dibutyltin dilaurate and the like can be used. Further, the reaction may be performed under reduced pressure for the same purpose.

(Colorant) Examples of the colorant include pigments such as inorganic pigments and organic pigments. Organic pigments are opaque powder paints used in the production method of the present invention. preferable. As the organic pigment, for example, azo pigments such as Hansaier-G, Hansaier-10G, Hansaier-13G, Benzidine yellow-G, Benzidine yellow, Vulcan orange, Pyrazolone red, Pyrazolone red B; Acid acid R, quinoline Acidic pigments and basic pigments such as yellow, tartrazine yellow, orange II, acid bull, malachite green, methyl violet and victoria bull; for example, phthalocyanine blue, sulfonated copper phthalocyanine, quinacridone red Phthalocyanine pigments such as quinacridone violet and carbazo-dioxane violet; quinacridone pigments and dioxane pigments; for example, organic fluorescent pigments, and other organic pigments such as pigments derived from vat dyes. Gerare,
It is used in an amount of 1 to 20 parts by weight, preferably 1 to 10 parts by weight, more preferably 1 to 5 parts by weight, per 100 parts by weight of the binder resin.

The colorant of the translucent powder coating used in the method for producing a coating film of the present invention may be selected from general formulas according to a desired color.
(2):

[0038]

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[Wherein X ¹ , X ² , X ³ and X ⁴ are the same or different and are each a hydrogen atom, a group (3) or a group (4):

[0040]

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Wherein R ³ and R ⁴ represent an alkylene group having 1 to 5 carbon atoms. Where X ¹ , X ² , X
³ and X ⁴ are not simultaneously hydrogen atoms. A copper phthalocyanine pigment represented by the general formula (5):

[0042]

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(Wherein, Q ¹ and Q ² are the same or different and each represents a hydrogen atom, an alkyl group or an alkoxy group, provided that Q ¹ and Q ² are not hydrogen atoms at the same time). Quinacridone pigment, general formula (6)
:

[0044]

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(Wherein, R ⁵ represents a nitro group, an alkyl group or an alkoxy group. R ⁶ represents a halogen atom, an alkyl group, an alkoxy group, a nitro group, an aryl-substituted sulfamoyl group, and Ca, Ba, Mn, It represents a sulfo group or a carboxyl group substituted with a heavy metal such as Sr.
R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are the same or different and represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. ) And general formula (7):

[0046]

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(Wherein R ¹¹ represents a hydrogen atom, an alkyl group or an alkoxy group; R ¹² represents a hydrogen atom, an alkyl group or a halogen atom; R ¹³ represents a hydrogen atom or an alkyl group). Azoacetate anilide-based monoazo and bisazo-based pigments.

The copper phthalocyanine pigment represented by the general formula (2) is a coloring agent for cyan paint. Group (3) and group
Examples of the alkylene group corresponding to (4) include a lower alkylene group having 1 to 5 carbon atoms among the above exemplified lower alkylene groups.
The quinacridone pigment represented by the general formula (5) is a colorant for a magenta paint. In general formula (5), Q ¹ and Q ²
As the alkyl group corresponding to
To 6 groups. Examples of the alkoxy group include groups having 1 to 6 carbon atoms such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, n-pentyloxy, and n-hexyloxy.

The azoacetoacetic anilide monoazo and bisazo pigments represented by the general formulas (6) and (7) are colorants for yellow paints. In the general formulas (6) and (7), the alkyl group and the alkoxy group include the same groups as described above. The pigments represented by the above general formulas (2), (5), (6) and (7) are used in amounts of 1 to 100 parts by weight of the binder resin.
To 20 parts by weight, preferably 2 to 10 parts by weight. If the amount of the pigment is less than the above range, the color becomes light and a clear color may not be obtained. On the other hand, if the amount of the pigment exceeds the above range, the light transmittance of the coating material may be reduced.

(Other Additives) In addition to the binder resin and the colorant described above, the light-transmitting and opaque powder coating used in the method for producing a coating film of the present invention may further comprise a curing agent,
Contains external additives, leveling agents, charge control agents and the like. As the additive, it is preferable to use an additive composed of the same or the same type of resin in order to improve the compatibility of the above-mentioned binder resin and the interlayer adhesion.

(Curing Agent) Examples of the curing agent include block isocyanate, epoxy resin, amino resin, aziridine compound, and polycarboxylic acid. Since the compounding amount of the curing agent is determined by the equivalent of the functional group of the binder resin that undergoes a curing reaction, it is preferable to use the curing agent appropriately in accordance with the equivalent of the functional group.

(Smoothing agent) Examples of the above-mentioned smoothing agent include olefin-based resins, epoxy resins, polyester resins, styrene-butadiene-based copolymers, olefin-based copolymers, polyvinylpyrrolidone, maleic anhydride copolymers, phenol-
Resin and the like, and the light-transmitting and opaque powder coating used in the production method of the present invention contains 0.1 to 2 parts by weight, preferably 0.5 to 1 part by weight, per 100 parts by weight of the binder resin. It is good to contain by weight.

The translucent and opaque powder coating used in the method for producing a coating film of the present invention may contain hydrophobic silica fine particles, titanium oxide, alumina Per 100 parts by weight of powder coating.
It is preferable to add 1 to 3 parts by weight, preferably 0.1 to 1 part by weight. The translucent and opaque powder coating used in the method for producing a coating film of the present invention may further contain a charge control agent, if necessary. The charge control agent is compounded when the powder coating is applied by electrostatic coating so that the powder coating easily adheres to the object to be coated. The pigments represented by the general formulas (2), (5), (6) and (7) used in the light-transmitting powder coating in the method for producing a coating film of the present invention can also be used as a charge control agent. Although it works, in order to make the charge amount of the powder coating at the time of coating more sufficient, various conventionally known charge control agents may be blended.

Examples of such charge control agents include, for example, quaternary ammonium salts, nigrosine-based electron-donating dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, alkylamides and chelates. Fluorinated activators, pigments and the like. Examples of the charge controlling agent for negative charging include electron-accepting organic complexes, other chlorinated paraffins, aromatic dicarboxylic acids, aromatic oxycarboxylic acids, chlorinated polyesters, polyesters having an excess acid group, and sulfonylamines of copper phthalocyanine. Is raised.

In the light-transmitting and opaque powder coating used in the production method of the present invention, an incompatible and highly dispersible aromatic dicarboxylic acid or aromatic oxycarboxylic acid is used as a charge control agent for negative charging. As the acid and the charge controlling agent for positive charging, a quaternary ammonium salt which does not affect the color development of the colorant is preferable, and 0.1 to 1 part by weight per 100 parts by weight of the binder resin.
0 parts by weight, preferably 0.1 to 5 parts by weight.

Examples of the method of applying the powder coating include a frame spray method, a plasma spray method, a fluid immersion method, an electrostatic coating method, and the like. An electrostatic coating method with good adsorption efficiency is preferable, and either a tribogun of a triboelectric charging type or a corona gun of a corona charging type can be used.

[0057]

EXAMPLES The present invention will be specifically described below with reference to reference examples, examples and toning examples. Reference Example 1 [Synthesis of polyester resin as binder resin] Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane (840 g), polyoxyethylene (2.0) -2,2 -Bis (4-hydroxyphenyl)
Propane (195 g), terephthalic acid (249 g), fumaric acid (132 g), 1,2,5-benzenetricarboxylic acid (29 g), dibutyltin oxide (2 g) and hydroquinone (1.5 g) were mixed with 2 l of glass. , A thermometer, a stainless steel stirring rod, a falling condenser and a nitrogen inlet tube.
The reaction was carried out at 200 ° C. in a nitrogen stream under a nitrogen atmosphere. Subsequently, the reaction was terminated when the degree of polymerization reached a softening point of 122 ° C. according to ASTM E 28-51T.

The obtained polyester resin was a light yellow solid, and the glass transition point measured by DSC (differential calorimetry) was 66 ° C. The acid value of the polyester resin is 1
4 KOH mg / g and the hydroxyl value were 36 KOH mg / g. Example 1 (1) Preparation of Opaque Powder Coating Resin 85 parts by weight of polyester resin prepared in Reference Example 1 Hardener "Vestagon B1530" (manufactured by Huls) 15 parts by weight Lubricant "Acronal 4F" [BASF Corporation] 1 part by weight Pigment Titanium oxide 10 parts by weight Pigment C.I. I. Solvent Blue 1 part by weight The resin, curing agent, smoothing agent, and pigment described above are mixed, mixed for 1 minute with a Henschel mixer, and kneaded at 110 ° C. using an extruder. The kneaded product was pulverized by a jet mill, classified by a 150-mesh sieve, and finally silica fine particles were externally added to prepare an opaque powder coating having an average particle diameter of 40 μm. (2) Preparation of Transparent Powder Coating Resin 85 parts by weight of polyester resin prepared in Reference Example 1 above 15 parts by weight of curing agent block isocyanate 1 part by weight of "Acronal 4F" (manufactured by BASF) Part pigment C.I. I. Pigment Yellow-13 1 part by weight The resin, curing agent, leveling agent and pigment described above are blended, mixed for 1 minute with a Henschel mixer, and kneaded at 110 ° C. using an extrusion kneader. This kneaded material was pulverized by a jet mill, classified by a 150-mesh sieve, and finally silica fine particles were externally added to prepare a title powder coating having an average particle diameter of 20 μm. Example 2 (Toning by Production Method A) The opaque blue powder coating prepared in Example 1 (1) was electrostatically coated on a steel plate so as to have a film thickness of 50 μm using a corona gun. Next, the yellow translucent powder coating prepared in Example 1 (2) was applied on the opaque powder coating to a thickness of 40 μm using a corona gun, and baked at 180 ° C. for 20 minutes. . Immediately after being placed in the furnace, the two kinds of powder coatings having different colors gradually melted, and finally a dark green coating film having a thickness of 90 μm and having a light-transmitting property was formed. Example 3 (Toning by Production Method A)
A spray gun was used to apply a dry film thickness of 20 .mu.m to the plate and dried. Next, the yellow translucent powder paint prepared in Example 1 (2) was evenly applied on the coating film formed of the opaque paint by electrostatic spraying, and baked at 180 ° C. for 20 minutes. Done. Immediately, the yellow translucent powder coating gradually melted, and finally a translucent dark green coating film was formed. Example 4 (Toning by Production Method A) On the dark green coating film formed in Example 2 or 3, the yellow translucent powder paint prepared in Example 1 (2) was formed to a film thickness of 40 μm. And then melted at 180 ° C. for 20 minutes to give a film thickness of 1
A pale green coating having a translucency of 30 μm was obtained. Example 5 (Toning by Production Method B) The opaque blue powder coating (100 g) prepared in Example 1 (1) and the yellow translucent powder coating prepared in Example 1 (2) ( 20 g) were mixed in a Henschel mixer and dry-mixed for about 10 minutes. The uniformly mixed powder coating was applied to a steel plate in the same manner as in Example 2 using an electrostatic spray gun. Then at 180 ° C 2
Bake for 0 minutes. After the start of baking, the powder paints of two different colors gradually melted, forming a 70 μm-thick light-transmissive dark green coating film. Example 6 (Toning by Production Method B) The opaque blue powder coating (100 g) prepared in Example 1 (1) was used in Example 1 (2).
The same procedure as in Example 5 was carried out except that the yellow translucent powder paint (100 g) prepared in the above was used and applied so that the thickness after melting was 70 μm, and the translucent light green color was obtained. Was formed.

[0059]

According to the method for producing a coating film of the present invention,
Without impairing the uniformity of the coating film by coagulation, color spots, etc.
We can provide beautiful coatings. Even if the number of colors of the opaque powder coating and the translucent powder coating is small, desired toning can be achieved by changing the application amount or the mixing ratio of the translucent powder coating. is there.

[Brief description of the drawings]

FIG. 1 is a process explanatory view showing one embodiment of the present invention.

FIG. 2 is a process explanatory view showing another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 coated object 2 opaque powder coating 3 translucent powder coating 4 opaque coating 5 translucent coating 6 opaque powder coating 7 translucent powder coating 8 coating 9 opaque Coating film 10 Transparent coating film

Claims (5)

[Claims] An opaque paint is applied to the surface of an object to be coated, and a translucent powder paint different in color from the opaque paint is applied to the coating layer. Method of manufacturing painted coatings. 2. The method according to claim 1, wherein the opaque paint is an opaque powder paint. 3. Mixing an opaque powder coating and a light-transmitting powder coating which is different in color from the opaque powder coating and has a particle diameter of 1/2 or less than that of the opaque powder coating. And applying the mixture to an object to be coated and melting the coated object. 4. The translucent powder coating material has an average particle size of 20.
The method for producing a coating film according to claim 3, which is not more than μm. 5. A toned color coating characterized by laminating an opaque colored coating film and a colored coating film having a light-transmitting color different from that of the colored coating film on a substrate in this order. Paint film.