JP2001342382A - Method for color matching of powder coating for mottled coating, powder coating, and coated article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color matching method for powder coatings giving for a mottled coated appearance according to the growing demand for design diversi fication and to provide coated articles with a mottled coated appearance. SOLUTION: This is a method in which two or more primary color powder paints are mixed and toned for the preparation of an intended color. The two or more primary color powder paints are (a) different in hue from the intended color, respectively; (b) their particles have average diameters falling in between 20-100 μm, respectively; and (c) the remotest chrominance ΔE between the particles is not less than 50. The color matching method using the toned mixture of two or more primary color powders results in a spotted pattern coating wherein the color mixture provides an average color of the powders.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for toning a powder coating for obtaining a spot pattern appearance, a powder coating used for this method, and a coated article.

[0002]

2. Description of the Related Art Powder coatings are attracting attention as coatings suitable for environmental measures because they do not contain organic solvents released into the atmosphere, and the amount and field of use thereof are expanding.

[0003] Toning of a powder coating is performed by adding two or more kinds of coloring materials to a resin, a curing agent, an additive, etc. so as to obtain a desired hue and color tone, in a raw material mixing step and a melt kneading step. This is performed through a powder coating manufacturing process (1) including a pulverizing process and a classification process, a coating film forming process (2) including a coating process and a heating process, and a hue / color tone checking process (3). In the above hue / tone confirmation step (3), if the desired hue / tone is not obtained, the process returns to the raw material mixing step in the powder coating production step (1), and the amount of the raw material or the colorant It is necessary to change the blending amount and type and repeat the above steps (1) to (3) again.

[0004] To reduce the complexity of such steps, a toning method of dry-mixing a powder coating has been used.
For example, JP-A-7-188586 discloses that, without melting two or more types of primary color powder coatings having an average particle diameter of 10 μm or less, dry-mixing and color matching are performed, and then to a particle diameter in a range suitable for coating. It describes a method for toning a powder coating which comprises granulating.

The above-mentioned toning method can easily perform toning by using two or more kinds of fine-grained primary color powder coating materials, appropriately mixing them according to a desired color tone, and visually judging. The powder coating thus obtained is capable of forming a coating film with little color shift and no color spots.

[0006]

On the other hand, with the diversification of designs, there is a need to form a coating film having a spotted pattern appearance, but the toning method described in the above publication cannot form a spotted pattern. .

[0007] Accordingly, an object of the present invention is to provide a method of toning for obtaining a spotted pattern appearance, a powder coating and a coated article having a spotted pattern appearance, which have been demanded with the diversification of designs. To provide.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, have reached the present invention. 1. A method of toning a powder coating in which two or more primary color powder coatings are mixed to obtain a desired color, wherein the two or more primary color powder coatings have the following (a) hue: (B) each average particle diameter is 20 to 1
(C) the color difference Δ farthest between them
E is 50 or more, and the mixed color of the coating film obtained by mixing and toning two or more primary color powder coatings is an average mixed color, powder for forming a speckled coating film. How to paint paint. 2. The above method for toning a powder coating, wherein the color mixture is intermediate between the average color mixture and the subtractive color mixture. 3. The (b) average particle diameter of the primary color powder coating is 30 to 50 μm, respectively, and (c) the farthest color difference ΔE is:
The method for toning a powder paint, which is 60 or more. 4. A powder coating for forming a speckled coating film obtained by the above method for toning a powder coating. 5. A coated article having a spot pattern appearance, wherein a coating film is formed from the powder coating.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.

The method for toning a powder coating is a method for forming a coating film having a spotted appearance by mixing two or more primary color powder coatings. Perform toning.

In the method for toning a powder coating according to the present invention, first, two or more primary color powder coatings are prepared. These two or more types of primary color powder coatings have different (a) hues from target colors. Here, the hue of the primary color powder coating means the hue of the coating film formed by applying each primary color powder coating. That is, "the hue is different from the target color" means that the Hue H of the Munsell color system obtained by measuring in this manner is different from the target color for each primary color powder coating material. It means that it is a paint color. The primary color powder coating may be a mixture of at least two types having different hues, and three or more types of primary color powder coatings having different hues may be mixed with each other. The hues of the two or more primary color powder coatings prepared here need to be the desired hues when they are mixed. The method for selecting the hue is not particularly limited, but is preferably performed using a method such as CCM (computer color matching) well known to those skilled in the art.

In the method for toning a powder coating according to the present invention, (b)
The average particle size of the primary color powder coating is 20 to 100 μ, respectively.
m.

The average particle size is measured by a particle size measuring device using laser scattering (for example, SK LASE manufactured by Seishin Enterprise Co., Ltd.).
R Sizer PRO-7000). When the average particle size is less than 20 μm, the coating film surface does not look like a speckled appearance, and when it exceeds 100 μm, a smooth coating film surface is not formed. Preferred average particle size is
It is 30 to 50 μm.

[0014] The method for toning a powder coating according to the present invention comprises:
(C) The farthest color difference ΔE between the primary color powder coatings is 5
Must be 0 or more. If the color difference ΔE is less than 50, a speckled coating film cannot be formed. The preferred color difference ΔE is 6
0 or more. The color difference can be calculated from the L, a, and b values using a Hunter's color difference formula by measuring the coating surface with a C light source according to the method of JISZ8729.

In the method for toning a powder coating according to the present invention, two or more primary color powder coatings satisfying the above requirements (a), (b) and (c) are then mixed to obtain a target. Toning a color. In this toning, the color is adjusted to the target color by mixing and colorimetry. If the target color is not the target color, this operation is repeated. It is characterized by being. The average color mixture is a method of arranging colors by fine dots (dots) to make the colors mixed to average the lightness, and is also called juxtaposed color mixture. In the region where the particle diameters of the two or more primary color powder coating materials are fine, the average color mixture and the subtractive color mixture in which the brightness decreases are performed in an intermediate position. The toning here may be a manual toning, but is preferably an automatic toning in which a theoretical formula of average mixing is constructed using a common color computer matching or the like. By performing the toning in this manner, the mixing mass ratio of the primary color powder coating is determined, and the powder coating for forming the speckled coating film can be obtained.

The powder coating for forming a speckled coating film The powder coating for forming a speckled coating film contains two or more types of primary color powder coating materials. (A) the hue is different from the target color,
(B) The average particle diameter of each is 20 to 100 μm, and (c) the color difference ΔE, which is the farthest between them, is 50 or more, which satisfies three conditions.

Primary Color Powder Coating Here, the primary color powder coating used in the present invention will be described. The primary color powder coating uses a synthetic resin as a binder component, and may be either a thermosetting resin or a thermoplastic resin. Examples of the synthetic resin used for the thermosetting resin-based primary color powder coating include an epoxy resin, an acrylic resin, and a polyester resin.

Examples of the epoxy resin include a glycidyl ester resin, a glycidyl ether resin such as a condensate of bisphenol A and epichlorohydrin, an alicyclic epoxy resin, a linear aliphatic epoxy resin, a brominated epoxy resin,
Compounds containing two or more oxirane groups in the molecule, such as phenol novolak epoxy resin and cresol novolak epoxy resin, may be mentioned.

Examples of the acrylic resin include styrene, acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, glycidyl acrylate, glycidyl methacrylate, and 2-methylglycidyl. Examples thereof include those obtained by polymerizing a monomer such as methacrylate by an ordinary method.

Examples of the polyester resin include a condensate obtained by heating and condensing a polybasic acid and a polyhydric alcohol. Examples of the polybasic acid include maleic acid, terephthalic acid, isophthalic acid, phthalic acid, succinic acid, glutamic acid, adipic acid, sebacic acid, β-oxypropionic acid, and the like.Examples of the polyhydric alcohol include:
Examples include ethylene glycol, diethylene glycol, propanediol, pentanediol, hexanediol, neopentyl glycol, trimethylolpropane, and pentaerythritol.

The curing agent blended in the thermosetting resin-based primary color powder coating material is appropriately selected depending on the functional group of the resin. For example, blocked isocyanate compounds, aliphatic polycarboxylic acids such as sebacic acid, amino resins, aliphatic acid anhydrides, polyepoxy compounds such as triglycidyl isocyanurate, amine-based curing agents, dicyandiamide, phenolic resins, epoxy resins, epoxy An acrylic resin having a group, a polyester resin having an epoxy group, an epoxy resin and the like are included.

The thermosetting resin / curing agent solid content ratio of the thermosetting resin-based primary color powder coating is preferably 55/45 to 45/45.
It is 99/5, more preferably 60/40 to 85/15. If it is out of the range of 55/45 to 99/5, there is a possibility that a problem may occur in the curability.

On the other hand, examples of the synthetic resin used for the thermoplastic resin-based primary color powder coating include a vinyl resin such as a polyvinyl chloride resin, a polyethylene resin, and a polyamide resin.

The synthetic resins contained in the two or more primary color powder coatings may be the same or different.

The above-mentioned primary color powder coating is colored by containing a coloring pigment such as titanium dioxide, red iron oxide, yellow iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, and quinacridone. In addition, the above primary color powder coating, if necessary, extender pigment, rust preventive pigment, surface modifier such as polysiloxane, plasticizer, ultraviolet absorber,
Antioxidants, anti-sparkling agents, pigment dispersants, amine compounds,
It may also contain a curing catalyst such as an imidazole compound, a cationic polymerization initiator, and other types of resins.

In the method for producing a primary color powder coating, first, the raw material powder of each component is uniformly mixed by a mixer. As the mixer, a general mixer such as a Henschel mixer, a ball mill, or a Banbury mixer can be used. Next, the obtained mixture is melt-kneaded. Here, the mixture is heated by a kneader such as an extruder or a hot roll to uniformly disperse other solid components in the molten synthetic resin component. Next, the pellets obtained by the melt-kneading step are pulverized using a pulverizer such as an atomizer or a jet mill,
By classifying with a cyclone classifier so as to satisfy the above-mentioned requirement of the average particle diameter, a primary color powder coating used in the present invention can be obtained. Alternatively, the primary color powder coating can be obtained by, for example, mixing the above raw materials in a molten state and pulverizing the obtained mixture by a spray drying method.

Coated Product Having Spotted Pattern Appearance The coated article having the spotted pattern appearance of the present invention has a coating film formed by the powder coating obtained by the above-described toning method.

Examples of the base material of the above-mentioned coated product include various metal plates or processed products such as cold-rolled steel plates, various types of plated steel plates, stainless steel plates and aluminum plates, and various metal plates obtained by surface-treating these metals by degreasing or chemical conversion treatment. Alternatively, a processed product, a plastic plate or a processed product, a plastic plate or a processed product subjected to conductive treatment by applying a conductive primer, or the like may be used.

The substrate is pretreated with a chemical conversion treating agent or the like, and the powder coating for forming a speckled coating film is applied by a spray coating method or an electrostatic coating method to form a coating film, followed by baking. Thus, a coated product having a coating film having a speckled pattern can be obtained. The printing conditions are, for example, 160 to 200.
C., preferably at a temperature of 170 to 180 C. for 15 to 20 minutes.

[0030]

EXAMPLES Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

Examples 1 to 5 and Comparative Examples 1 to 2 Two or more primary color powder coatings 1 to 8 shown below having different hues were selected for the color samples shown in Table 1. Next, using these, color matching was performed by a color computer matching method, and the mass mixing ratio shown in Table 1 was determined. Based on this mass mixing ratio, a cold-rolled steel sheet having a thickness of 0.8 mm was mixed with a blender, and a cold-rolled steel sheet having a thickness of 0.8 mm was subjected to a chemical conversion treatment using a zinc phosphate treating agent ("Surfdine SD2000", manufactured by Nippon Paint Co., Ltd.). About 80μ with powder electrostatic gun
m, and baked at 190 ° C. for 20 minutes. Whether or not the obtained coated article had an average color mixture and whether or not it had an appearance of a spotted pattern was visually evaluated based on the following evaluation criteria, and the results are shown in Table 1. The color difference was measured by a method based on JIS Z8729.

Powder coating paint 1: Epoxy polyester powder coatings of A and B shown in Table 1 having an average particle diameter of 40 μm and a hue of 50/50 were mixed to obtain a color sample hue. Paint 2: The average particle system was 40 μm, and the hues were mixed 50/50 with the polyester powder paints A and B shown in Table 1 to obtain a color sample hue. Coating 3: Epopoly powder coating of A, B, C, D shown in Table 1 having an average particle system of 40 μm and a hue of 97/3 / 0.0
The mixture was mixed at 2 / 0.02 to obtain a color sample hue. Paint 4: Epopoly powder paint having an average particle system of 40 μm and a hue of A, B, C, D shown in Table 1 was obtained on 73/21/1 /
5 to obtain a color sample hue. Paint 5: A polyester powder paint having an average particle system of 50 μm and a hue of A, B, and C shown in Table 1 was mixed at 70/20/5 to obtain a color sample hue. Paint 6: Epopoly powder paint of A and B shown in Table 1 was mixed at 50/50 with an average particle system of 15 μm and a hue to obtain a color sample hue. Paint 7: Epopoly powder paint of A and B shown in Table 1 was mixed at 50/50 with an average particle system of 15 μm and a hue to obtain a color sample hue. Paint 8: A polyester sample paint having an average particle size of 15 μm and a hue of 50/50 shown in Table 1 was mixed with a polyester powder paint of A and B to obtain a color sample hue.

Evaluation Criteria Spot Pattern A: Average color mixture, remarkable spot pattern, painted material with extremely high designability. Δ: Intermediate color mixture between average color mixture and subtractive color mixture, and speckle pattern appears. , Painted material with high design ×: Painted material that cannot be said to be an average color mixture and does not show spotted patterns

[0034]

[Table 1]

As is clear from the results shown in Table 1, the coated articles obtained by the methods of Examples 1 to 5 had a mixed color which can be said to be an average mixed color, and had an appearance having a speckled pattern. On the other hand, Comparative Examples 1 to
The coated product obtained by the method of No. 3 could not obtain an appearance having a speckled pattern.

[0036]

According to the present invention, a powder coating for forming a speckled coating film is obtained by mixing two or more primary color powder coatings each satisfying specific conditions with respect to hue, average particle diameter and color difference and performing toning. The coating film formed by the method is an average color mixture, and the formation of the spot pattern is clear, and the pattern of the spot is remarkably exhibited. Therefore, a method of toning a powder coating material having extremely high designability and a coated article having a spot pattern are provided. Made it possible.

The coated product of the present invention, which forms a coating film having a speckled pattern, is preferably used in applications requiring design properties such as the home appliance industry, building interior and exterior materials, and office furniture.

Claims (5)

[Claims] 1. A method for toning a powder coating in which two or more primary color powder coatings are mixed to obtain a desired color by mixing the two or more primary color powder coatings, a) the hue is different from the target color, and (b) the average particle size of each is
(C) the color difference ΔE, which is the most distant between them, is 50 or more, and the color mixture of the coating film obtained by mixing and mixing two or more kinds of primary color powder coatings is average. A method for toning a powder paint for forming a speckled coating film, which is a mixed color. 2. The method of claim 1, wherein the color mixture is intermediate between an average color mixture and a subtractive color mixture. 3. The primary color powder coating composition according to claim 1, wherein (b) the average particle size is:
3. The method of claim 1, wherein the color difference ΔE is 30 to 50 μm, and (c) the farthest color difference ΔE is 60 or more. 4. 4. A powder coating for forming a speckled coating film obtained by the method for toning a powder coating according to any one of claims 1 to 3. 5. A coated article having a spot-like appearance, wherein a coating film is formed by the powder coating according to claim 4.