JP6693075B2 - Thermosetting powder coating, coated product, and method of manufacturing coated product - Google Patents

Description

  The present invention relates to a thermosetting powder coating material, a coated article, and a method for producing a coated article.

  In electrostatic coating of powder coatings, the emission of volatile organic compounds (VOCs) in the coating process is small, and after coating, powder coatings that have not adhered to the coated object can be collected and reused. Therefore, it is attracting attention in terms of protecting the global environment. Various powder coating materials have been disclosed.

  For example, Patent Document 1 discloses a coating powder composed of associated particles having an average particle size of 3 μm to 70 μm containing polymer particles having an average particle size of 0.01 μm to 2 μm.

International Publication No. 1995/25145

  The present invention is a coating film having excellent image clarity as compared with the case where the content of ethylenediaminetetraacetic acid is less than 0.0001 mass% or more than 0.05 mass% with respect to the total mass of the powder particles. An object of the present invention is to provide a thermosetting powder coating material that forms a film.

  Specific means for solving the problems include the following modes.

The invention according to < 1 > is
A heat containing powder particles produced by a wet method, wherein the content of ethylenediaminetetraacetic acid is 0.0001% by mass or more and 0.05% by mass or less based on the total mass of the powder particles. Curable powder coating.

The invention according to < 2 > is
The viscoelastic spectra of the thermosetting powder coating material measured under the conditions of a temperature range of 80 ° C. to 200 ° C., a temperature rising rate of 1 ° C./min, and a frequency of 1 rad / sec are as follows (1), (2) and ( The thermosetting powder coating material according to < 1 > , which satisfies 3).
(1) The temperature T1 at which the storage elastic modulus G ′ starts to fall below 10000 Pa is 120 ° C. or lower.
(2) There is a temperature region where the loss tangent exceeds 1 at 120 ° C or lower.
(3) There is a temperature T2 at which the loss tangent starts to fall below 1 in a temperature region higher than the temperature region where the loss tangent exceeds 1, and the temperature T2 is more than 120 ° C and 190 ° C or less.

The invention according to < 3 > is
The thermosetting powder coating material according to < 2 > , wherein the viscoelastic spectrum further satisfies the following (4).
(4) 20 ° C. ≦ (temperature T2−temperature T1) <100 ° C.

The invention according to < 4 > is
The thermosetting powder coating material according to any one of < 1 > to < 3 > , wherein the volume average particle diameter of the powder particles is 4 μm or more and 12 μm or less.

The invention according to < 5 > is
The thermosetting powder coating material according to any one of < 1 > to < 4 > , wherein the average circularity of the powder particles is 0.965 or more and 0.995 or less.

The invention according to < 6 > is
The thermosetting powder coating material according to any one of < 1 > to < 5 > , which contains an external additive attached to the surface of the powder particles.

The invention according to < 7 > is
The thermosetting powder coating material according to < 6 > , wherein the external additive is silica particles surface-treated with hexamethyldisilazane.

The invention according to < 8 > is
A coated article coated with the thermosetting powder coating material according to any one of < 1 > to < 7 > .

The invention according to < 9 > is
< 1 > to < 7 > A method for producing a coated article, which comprises applying the thermosetting powder coating material according to any one of < 1 > to < 7 > .

According to the inventions related to < 1 > , < 2 > , and < 3 >, when the content of ethylenediaminetetraacetic acid is less than 0.0001% by mass or more than 0.05% by mass with respect to the total mass of the powder particles. The thermosetting powder coating material that forms a coating film having excellent image clarity is provided.

According to the invention of < 4 > , the thermosetting powder coating material forms a coating film having excellent image clarity as compared with the case where the volume average particle diameter of the powder particles is less than 4 μm or more than 12 μm. Will be provided.

According to the invention of < 5 > , the thermosetting property of forming a coating film having excellent image clarity as compared with the case where the average circularity of the powder particles is less than 0.965 or more than 0.995. A powder coating is provided.

According to the inventions related to < 6 > and < 7 > , there is provided a thermosetting powder coating which forms a coating film having excellent image clarity as compared with the case where no external additive is contained.

According to the inventions related to < 8 > and < 9 >, when the content of ethylenediaminetetraacetic acid is less than 0.0001% by mass or more than 0.05% by mass with respect to the total mass of the powder particles. In comparison, a coated article or a method for producing a coated article having excellent coating film clarity is provided.

It is an example of a viscoelastic spectrum of the powder coating material according to the present embodiment.

  Embodiments of the invention will be described below. These descriptions and examples are illustrative of the embodiments and are not intended to limit the scope of the invention.

  In the present specification, the “thermosetting powder coating material” is also simply referred to as “powder coating material”.

<Thermosetting powder coating>
The powder coating material according to the present embodiment is powder particles manufactured by a wet manufacturing method, and the content of ethylenediaminetetraacetic acid (EDTA) is 0.0001% by mass or more and 0.1% by mass or less based on the mass of the entire powder particles. The powder particles are contained in an amount of 05 mass% or less.
The powder coating material according to the present embodiment forms a coating film having excellent image clarity.

  There is "mirror surface painting" in the technology of product painting. Mirror painting is a technique that polishes the paint film to create a surface that is so sharp that the scenery looks like a mirror. Until now, it has been difficult to form a coating film with high image clarity that is close to mirror-finishing by coating powder coating itself (that is, without going through the polishing step). In order to form a coating film with high image clarity that is close to a mirror surface coating with powder coating, (a) high uniformity of the coating before baking, and (b) melt flowability of the powder coating. It is considered necessary to satisfy that is high.

The powder particles constituting the powder coating material are generally produced by a method of mixing and melting materials and then pulverizing them into particles (so-called kneading and pulverizing method), but powder produced by the kneading and pulverizing method. Since the particles have a wide particle size distribution and the shape of the particles is indefinite, it is difficult to satisfy at least (a).
On the other hand, powder particles produced by a wet method (for example, agglomeration-coalescence method, suspension polymerization method, dissolution suspension method, etc.) have a narrow particle size distribution and the shape of the particles is close to spherical. It is considered easy to satisfy. However, it was difficult to satisfy (b). One of the reasons is that the curing temperature of the powder coating composition is the composition of the resin so that the coating film is cured even if the temperature rise of the surface to be coated is uneven due to the nonuniformity of the thickness of the object to be coated. There are circumstances in which it is designed to be relatively low depending on the type of curing agent. Considering the easiness of curing the powder coating material and the manufacturing cost, in the powder particles manufactured by the wet manufacturing method without changing the above design (resin composition and type of curing agent) and baking conditions, It is desirable to satisfy b) and enhance the sharpness.

  As a result of diligent study, the present inventor has found that in powder particles produced by a wet manufacturing method, the EDTA content of the powder particles is 0.0001% by mass or more and 0.05% by mass or less, and thus (a) is further improved. They were satisfied, and also satisfied (b), and found that the sharpness of the coating film was improved. The following mechanism is supposed as the mechanism.

The high uniformity of the coating film before baking is achieved by the powder coating adhered to the surface to be coated with high uniformity, and the high uniformity of adhesion of the powder coating constitutes the powder coating. This is achieved by the narrow particle size distribution of the powder particles and the high charge amount per powder particle. The powder particles produced by the wet process have a narrow particle size distribution, but the charge amount per particle tends to be inferior to that of the powder particles produced by the kneading and pulverizing method. The reason is considered to be the influence of metal ions as impurities derived from the aqueous medium (mainly water) used in the manufacturing process of the wet manufacturing method.
On the other hand, when EDTA is used in an appropriate amount in the manufacturing process of the wet manufacturing method, it is presumed that EDTA chelates metal ions as impurities to increase the charge amount per powder particle.

On the other hand, the melt fluidity of the powder coating material is determined by the balance between lowering the viscosity by melting the resin and increasing the viscosity by the progress of curing of the resin. If the melt fluidity is low, that is, if the resin is sufficiently melted to have a low viscosity and hardening of the resin proceeds before flowing, the clarity of the coating film will not be improved. In the powder particles manufactured by the wet manufacturing method, metal ions as impurities derived from the aqueous medium (mainly water) used in the manufacturing process are scattered around the resin, and the metal ions are (i) anions of the resin. Curing rate of the resin by excessively forming ionic cross-links with the functional group (for example, carboxyl group), inhibiting the viscosity reduction of the resin, and (ii) acting as a catalyst for promoting the reaction between the resin and the curing agent. It is considered that the speed is unintentionally increased. As a result, it is assumed that the melt fluidity of the powder coating does not increase.
On the other hand, when an appropriate amount of EDTA is used in the manufacturing process of the wet process, (i) and (ii) are suppressed by the chelation of metal ions as impurities, and the melt fluidity of the powder coating material is increased. Guessed.

EDTA is suitable as a chelating agent for chelating metal ions as impurities. Where the content of the chelating agent is large, the charge amount per powder particle tends to decrease, but EDTA efficiently chelates metal ions among various chelating agents, so a relatively small amount can be used. preferable. However, if the EDTA content of the powder particles is more than 0.05% by mass, the charge amount per one particle of the powder particles will be low. Therefore, in this embodiment, the EDTA content is 0.05% by mass or less. ..
On the other hand, if the EDTA content is less than 0.0001% by mass, the amount of EDTA used in the manufacturing process of the wet manufacturing method is too small, metal ions as impurities cannot be sufficiently chelated, and the charge amount per powder particle is increased. That is, it is difficult to suppress (i) and (ii).

According to the above mechanism, the powder coating material according to the present embodiment further satisfies (a) because the EDTA content of the powder particles is 0.0001 mass% or more and 0.05 mass% or less. It is assumed that (b) is also satisfied and a coating film having excellent image clarity is formed.
In the present embodiment, the EDTA content of the powder particles is more preferably 0.001% by mass or more, further preferably 0.01% by mass or more; more preferably 0.04% by mass or less, More preferably, it is 0.03 mass% or less. In the present embodiment, the EDTA content of the powder particles is, for example, 0.001 mass% or more and 0.05 mass% or less, 0.001 mass% or more and 0.04 mass% or less, and 0.01 mass% or less. % Or more and 0.04 mass% or less, and 0.01 mass% or more and 0.03 mass% or less.

  The powder coating material according to the present embodiment has a viscoelastic spectrum measured under the conditions of a temperature range of 80 ° C. to 200 ° C., a temperature rising rate of 1 ° C./minute, and a frequency of 1 rad / second, from the viewpoint of being more excellent in the clarity of the coating film. In the above, it is preferable to satisfy the following (1), (2) and (3), and it is more preferable to satisfy the following (4).

(1) The temperature T1 at which the storage elastic modulus G ′ starts to fall below 10000 Pa is 120 ° C. or lower.
(2) There is a temperature region where the loss tangent exceeds 1 at 120 ° C or lower.
(3) There is a temperature T2 at which the loss tangent starts to fall below 1 in a temperature region higher than the temperature region where the loss tangent exceeds 1, and the temperature T2 is more than 120 ° C and 190 ° C or less.
(4) 20 ° C. ≦ (temperature T2−temperature T1) <100 ° C.

The viscoelastic spectrum of the powder coating material and the above (1) to (4) will be described with reference to FIG.
FIG. 1 is a schematic diagram showing the viscoelastic spectrum of the powder coating material according to the present embodiment, and shows the relationship between the storage elastic modulus G ′, the loss tangent (tan δ) and the temperature. In FIG. 1, the solid line graph shows the storage elastic modulus G ′, and the broken line graph shows the loss tangent (tan δ).

In the viscoelastic spectrum shown in FIG. 1, the storage elastic modulus G ′ decreases in the temperature range of 80 ° C. to 200 ° C. as the temperature rises, and starts increasing when the temperature further rises. The temperature T1 is the temperature at which the storage elastic modulus G ′ starts to fall below 10,000 Pa.
This change in the storage elastic modulus G ′ causes a decrease in elasticity (that is, softening) because the resin contained in the powder coating material melts as the temperature rises, and when the temperature further rises, the curing of the resin progresses, so that the elasticity changes. It reflects the increase.

On the other hand, tan δ increases as the temperature rises in the temperature range of 80 ° C to 200 ° C, exceeds 1 at 120 ° C or lower, and decreases to less than 1 when the temperature further rises. The temperature T2 is a temperature at the time when tan δ starts to fall below 1. The temperature region in which tan δ exceeds 1 is sufficient if at least a part thereof exists at 120 ° C. or lower, and may exist over a temperature range of 120 ° C. or lower to over 120 ° C.
This variation in tan δ reflects that the resin contained in the powder coating material melts and the fluidity increases as the temperature rises, and when the temperature further rises, the curing of the resin proceeds and the fluidity decreases. ..

When the storage elastic modulus G ′ starts to fall below 10000 Pa and tan δ exceeds 1 at 120 ° C. or lower ((1) and (2)), the resin is sufficiently softened at a relatively low temperature (120 ° C. or lower). And it means flowing.
On the other hand, if the temperature at which tan δ exceeds 1 and falls below 1 and tan δ starts to fall below 1 is more than 120 ° C. and 190 ° C. or less ((3)), the resin is sufficiently contained within the normal baking temperature range. It means that after it softens and flows, it hardens.

  Satisfying (1), (2) and (3) means that the above-mentioned phenomenon is realized together, and in this case, softening and curing of the resin contained in the powder coating material are balanced. As a result, the clarity of the coating film is improved. Further, satisfying (4) means that the softening and curing of the resin contained in the powder coating material proceed in a more balanced manner, and in this case, the sharpness of the coating film is further enhanced.

From the viewpoint described above, the temperature T1 is 120 ° C or lower, more preferably 80 ° C or higher and 120 ° C or lower, further preferably 90 ° C or higher and 120 ° C or lower, and further preferably 90 ° C or higher and 110 ° C or lower. Is.
The temperature T2 is more than 120 ° C and 190 ° C or less, more preferably 125 ° C or more and 180 ° C or less, and further preferably 130 ° C or more and 170 ° C or less.
The temperature difference between temperature T2 and temperature T1 (temperature T2−temperature T1) is 20 ° C. or higher and lower than 100 ° C., more preferably 30 ° C. or higher and 80 ° C. or lower, and further preferably 40 ° C. or higher and 70 ° C. or lower.

In the present embodiment, the viscoelastic spectrum of the powder coating material is measured by a sinusoidal vibration method using a viscoelastic measuring device (ARES measuring system, TA Instruments). Specifically, it is measured by the following method.
Powder coating is molded into tablets (25 mm diameter x 1 mm thickness), set on a parallel plate with a diameter of 25 mm, melted at 100 ° C for 5 minutes, then cooled to 80 ° C, and stabilized at 80 ° C for 10 minutes. After that, the storage elastic modulus G ′ and the loss elastic modulus G ″ are measured at a measurement frequency of 1 rad / sec and a measurement interval of 0.5 ° C. while heating from a temperature of 80 ° C. to 200 ° C. at a heating rate of 1 ° C./min. The loss tangent (tan δ) is defined by (loss elastic modulus G ″ ÷ storage elastic modulus G ′).

  Hereinafter, details of the powder coating material according to the present embodiment will be described.

  The powder coating material according to the present embodiment may be either a transparent powder coating material (clear coating material) containing no colorant in the powder particles or a colored powder coating material containing a colorant in the powder particles. In this embodiment, the powder particles preferably contain a thermosetting resin and a thermosetting agent.

  The powder coating material according to the present embodiment contains powder particles and may further contain an external additive that adheres to the surfaces of the powder particles. The powder coating material according to the present embodiment suppresses agglomeration (blocking) of the powder particles to adhere to the surface to be coated with high uniformity, and enhances the fluidity of the powder particles to improve the sharpness. From the viewpoint of forming an excellent coating film, it is desirable to have an external additive attached to the surface of the powder particles.

[Powder particles]
The structure of the powder particles is not particularly limited. The powder particles preferably have a structure having a core portion and a resin coating portion that covers the surface of the core portion. That is, the powder particles are preferably particles having a core / shell structure.

  In the present embodiment, the EDTA content of the powder particles is defined as the EDTA content (mass basis) of a dispersion prepared by dispersing 0.1 g of the powder particles in 50 mL of a 0.5 M NaOH aqueous solution at 28 ° C. The value obtained according to the following operations 1) to 6).

1) Weigh 0.1 g of powder particles, add 50 mL of 0.5 M NaOH aqueous solution and a proper amount of 20 mass% surfactant (Taika Power Co., Ltd.) and stir for 2 hours at 28 ° C. using a ball mill. To do.
2) Centrifuge the liquid obtained in 1) at 2000 rpm for 30 minutes.
3) Pass the supernatant obtained in 2) through a JIS standard 5A filter paper.
4) The filtrate (8.5 mL) obtained in 3), an acetic acid buffer solution (1.0 mL) (a solution in which 1 M acetic acid (20.0 mL), 1 M sodium acetate (30.0 mL), and ion-exchanged water (100 mL) were thoroughly mixed) and 0.19 0.5 mL of a mass% iron (III) chloride aqueous solution is weighed in an Erlenmeyer flask and mixed sufficiently.

5) The EDTA content of the sample obtained in 4) is measured by high performance liquid chromatography (HPLC). The HPLC apparatus and conditions are as follows.
Analyzer: LaChromElite L-2000, Hitachi High Technologies Column: Gelpack GL-W520-S (diameter 7.8 mm x 300 mm), Hitachi Chemical Detector: L-2455 type diode array detector, Hitachi High Technologies Measurement wavelength: UV190 nm- 400 nm
Quantitative wavelength: UV284nm
Mobile phase: 50 mM dipotassium hydrogen phosphate Liquid transfer rate: 1.0 mL / min
Sample injection volume: 10 μL
Column temperature: 50 ° C

6) Calculate the EDTA content of the dispersion according to the following formula.
EDTA content of dispersion = EDTA content of HPLC sample x (50 mL ÷ 8.5 mL)

  The volume average particle diameter D50v of the powder particles is preferably 4 μm or more and 12 μm or less, and 4.5 μm or less, from the viewpoint that the powder coating material adheres to the surface to be coated with high uniformity and, as a result, further improves the sharpness of the coating film. It is more preferably 11 μm or less and more preferably 5 μm or more and 10 μm or less.

  The volume particle size distribution index GSDv of the powder particles is 1.50 from the viewpoint of suppressing the unevenness caused by the coarse powder and the fluidity decrease caused by the fine powder, and as a result, further improving the sharpness and smoothness of the coating film. The following is preferable, 1.40 or less is more preferable, and 1.30 or less is further preferable.

  The average circularity of the powder particles is preferably 0.965 or more and 0.995 or less, from the viewpoint that voids are unlikely to be formed in the coating film before baking and, as a result, the sharpness and smoothness of the coating film are further improved, It is more preferably 0.970 or more and 0.995 or less, and still more preferably 0.975 or more and 0.995 or less.

The volume average particle diameter D50v of the powder particles and the volume particle size distribution index GSDv are measured using a Coulter Multisizer II (Beckman Coulter, Inc.) and the electrolyte solution is ISOTON-II (Beckman Coulter, Inc.). ..
In the measurement, 0.5 mg or more and 50 mg or less of the measurement sample is added to 2 ml of a 5% by mass aqueous solution of a surfactant (sodium alkylbenzenesulfonate is preferable) as a dispersant. This is added to 100 ml or more and 150 ml or less of the electrolytic solution.
The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for 1 minute with an ultrasonic disperser, and a Coulter Multisizer II is used to obtain a particle size distribution of particles in the range of 1 μm to 30 μm using an aperture of 50 μm as an aperture diameter. taking measurement. The number of particles to be sampled is 50,000.
A volume-based cumulative distribution is drawn from the small diameter side with respect to a particle size range (channel) divided based on the measured particle size distribution, and a cumulative particle size of 16% is a volume particle size D16v and a cumulative particle size is 50%. The particle diameter is defined as a volume average particle diameter D50v, and the cumulative particle diameter of 84% is defined as a volume particle diameter D84v. The volume particle size distribution index GSDv is calculated as (D84v / D16v).

  The average circularity of the powder particles is measured by using a flow type particle image analyzer (FPIA-3000, Sysmex). Specifically, 0.1 ml or more and 0.5 ml or less of a surfactant (alkylbenzene sulfonate) as a dispersant is added to 100 ml or more and 150 ml or less of water from which impure solids have been removed in advance, and a measurement sample Add 0.1 g or more and 0.5 g or less. The suspension in which the measurement sample is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for 1 minute or more and 3 minutes or less, and the concentration of the dispersion liquid is set to 3000 particles / μl or more and 10,000 particles / μl or less. The average circularity of the powder particles is measured for this dispersion using a flow-type particle image analyzer.

  The average circularity of the powder particles is a value calculated by the following formula by obtaining the circularity (Ci) of each of the n particles measured for the powder particles. In the following formula, Ci represents the circularity (= perimeter of a circle equal to the projected area of the particle / perimeter of the projected image of the particle), and fi represents the frequency of powder particles.

[Core]
When the powder particles have a structure having a core part and a resin coating part, the core part preferably contains a thermosetting resin and a thermosetting agent, and may further contain other additives such as a coloring agent. Good.

-Thermosetting resin-
The thermosetting resin is a resin having a thermosetting reactive group. As the thermosetting resin, various kinds of resins conventionally used for powder particles of powder coating materials can be mentioned.
The thermosetting resin may be a water-insoluble (hydrophobic) resin. When a water-insoluble (hydrophobic) resin is applied as the thermosetting resin, the environmental dependence of the charging characteristics of the powder coating material (powder particles) is reduced. Further, when the powder particles are produced by the aggregation and coalescence method, the thermosetting resin is preferably a water-insoluble (hydrophobic) resin also from the viewpoint of realizing emulsion dispersion in an aqueous medium. Water-insoluble (hydrophobic) means that the amount of the target substance dissolved in 100 parts by mass of water at 25 ° C. is less than 5 parts by mass.

  The thermosetting resin is preferably at least one selected from the group consisting of thermosetting (meth) acrylic resins and thermosetting polyester resins.

Thermosetting (meth) acrylic resin The thermosetting (meth) acrylic resin is a (meth) acrylic resin having a thermosetting reactive group. For introducing the thermosetting reactive group into the thermosetting (meth) acrylic resin, it is preferable to use a vinyl monomer having a thermosetting reactive group. The vinyl monomer having a thermosetting reactive group may be a (meth) acrylic monomer (a monomer having a (meth) acryloyl group), or a vinyl monomer other than the (meth) acrylic monomer. It may be a monomer.

  Examples of the thermosetting reactive group of the thermosetting (meth) acrylic resin include an epoxy group, a carboxyl group, a hydroxyl group, an amide group, an amino group, an acid anhydride group, and a (block) isocyanate group. Among these, the thermosetting reactive group of the (meth) acrylic resin is at least one selected from the group consisting of an epoxy group, a carboxyl group, and a hydroxyl group from the viewpoint of easy production of the (meth) acrylic resin. preferable. From the viewpoint of excellent storage stability of the powder coating material and appearance of the coating film, at least one of the thermosetting reactive groups is preferably an epoxy group.

  Examples of vinyl monomers having an epoxy group as a thermosetting reactive group include various chain epoxy group-containing monomers (eg, glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, glycidyl vinyl ether, Allyl glycidyl ether, etc.), various (2-oxo-1,3-oxolane) group-containing vinyl monomers (for example, (2-oxo-1,3-oxolane) methyl (meth) acrylate, etc.), various fats Cyclic epoxy group-containing vinyl monomers (eg, 3,4-epoxycyclohexyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, etc.) Can be mentioned.

  Examples of the vinyl monomer having a carboxyl group as a curable reactive group include various carboxyl group-containing monomers (for example, (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, etc.), Monoesters of various α, β-unsaturated dicarboxylic acids and monohydric alcohols having 1 to 18 carbon atoms (eg, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monoisobutyl fumarate, monotert fumarate) -Butyl, monohexyl fumarate, monooctyl fumarate, mono-2-ethylhexyl fumarate, monomethyl maleate, monoethyl maleate, monobutyl maleate, monoisobutyl maleate, monotert-butyl maleate, monohexyl maleate, monomaleate Octyl, mono-2-ethyl maleate Xyl, etc.), various itaconic acid monoalkyl esters (eg, monomethyl itaconate, monoethyl itaconate, monobutyl itaconate, monoisobutyl itaconate, monohexyl itaconate, monooctyl itaconate, mono-2-ethylhexyl itaconate, etc.) Can be mentioned.

  Examples of vinyl monomers having a hydroxyl group as a curable reactive group include, for example, various hydroxyl group-containing (meth) acrylates (eg, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxy). Propyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, etc.) , Addition reaction products of the above-mentioned various hydroxyl group-containing (meth) acrylates and ε-caprolactone, various hydroxyl group-containing vinyl ethers (for example, 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2- Droxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 3-hydroxybutyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, etc.), the various hydroxyl group-containing vinyl ethers and ε- Addition reaction products with caprolactone, various hydroxyl group-containing allyl ethers (for example, 2-hydroxyethyl (meth) allyl ether, 3-hydroxypropyl (meth) allyl ether, 2-hydroxypropyl (meth) allyl ether, 4-hydroxy) Butyl (meth) allyl ether, 3-hydroxybutyl (meth) allyl ether, 2-hydroxy-2-methylpropyl (meth) allyl ether, 5-hydroxypentyl (meth) allyl Ether, 6-hydroxyhexyl (meth) allyl ether), and addition reaction products of the various hydroxyl group-containing allyl ether and ε- caprolactone.

  Examples of the (meth) acrylic monomer having no curable reactive group which is a constituent unit of the thermosetting (meth) acrylic resin include (meth) acrylic acid alkyl esters (for example, (meth) acrylic acid methyl ester, (meth ) Ethyl acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, (meth) acrylic Acid n-hexyl, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethyloctyl (meth) acrylate, (meth) Dodecyl acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylic acid (Thearyl, etc.), various (meth) acrylic acid aryl esters (for example, benzyl (meth) acrylate, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, etc.), various alkylcarbitol (meth) acrylates ( For example, ethyl carbitol (meth) acrylate, etc., various other (meth) acrylic acid esters (eg, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclo). Pentenyloxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate and the like), various amino group-containing amide unsaturated monomers (for example, N-dimethylaminoethyl (meth) acrylamide, N-diethylaminoethyl ( (Meth) acrylamide, N- Methylaminopropyl (meth) acrylamide, N-diethylaminopropyl (meth) acrylamide, etc.), various dialkylaminoalkyl (meth) acrylates (eg, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, etc.), various Amino group-containing monomer (for example, tert-butylaminoethyl (meth) acrylate, tert-butylaminopropyl (meth) acrylate, aziridinylethyl (meth) acrylate, pyrrolidinylethyl (meth) acrylate, piperidinyl Ethyl (meth) acrylate etc.) etc. are mentioned.

In addition to the (meth) acrylic monomer, the thermosetting (meth) acrylic resin may be copolymerized with another vinyl monomer having no curing reactive group.
Other vinyl monomers include various α-olefins (eg, ethylene, propylene, butene-1), various halogenated olefins other than fluoroolefins (eg, vinyl chloride, vinylidene chloride), various aromas. Group vinyl monomers (eg, styrene, α-methylstyrene, vinyltoluene, etc.), diesters of various unsaturated dicarboxylic acids and monohydric alcohols having 1 to 18 carbon atoms (eg, dimethyl fumarate, diethyl fumarate) , Dibutyl fumarate, dioctyl fumarate, dimethyl maleate, diethyl maleate, dibutyl maleate, dioctyl maleate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, dioctyl itaconate, etc.) Polymer (eg, maleic anhydride, itaconic anhydride, anhydrous Citraconic acid, anhydrous (meth) acrylic acid, tetrahydrophthalic anhydride, etc.), various phosphoric acid ester group-containing monomers (for example, diethyl-2- (meth) acryloyloxyethyl phosphate, dibutyl-2- (meth)) Acryloyloxybutyl phosphate, dioctyl-2- (meth) acryloyloxyethyl phosphate, diphenyl-2- (meth) acryloyloxyethyl phosphate, etc.), various hydrolyzable silyl group-containing monomers (eg, γ- (Meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, etc., various aliphatic vinyl carboxylates (for example, vinyl acetate, propion) Vinyl acetate, vinyl butyrate , Vinyl isobutyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, branched aliphatic vinyl carboxylates having 9 to 11 carbon atoms, vinyl stearate, etc.), and carboxylic acids having a cyclic structure. Examples thereof include various vinyl esters (for example, vinyl cyclohexanecarboxylate, vinyl methylcyclohexanecarboxylate, vinyl benzoate, vinyl p-tert-butylbenzoate, etc.).

  The thermosetting (meth) acrylic resin preferably has a number average molecular weight of 1,000 or more and 20,000 or less, and preferably 1,500 or more and 15,000 or less, from the viewpoint of excellent smoothness of the coating film. More preferable.

Thermosetting polyester resin The thermosetting polyester resin is, for example, a polycondensate obtained by polycondensing at least a polybasic acid and a polyhydric alcohol. The thermosetting reactive group is introduced into the thermosetting polyester resin by adjusting the amounts of the polybasic acid and the polyhydric alcohol used. By this adjustment, a thermosetting polyester resin having at least one of a carboxyl group and a hydroxyl group as a thermosetting reactive group can be obtained.

  Examples of polybasic acids include terephthalic acid, isophthalic acid, phthalic acid, methylterephthalic acid, trimellitic acid, pyromellitic acid, and anhydrides of these acids; succinic acid, adipic acid, azelaic acid, sebacic acid, and these acids. Anhydrides; maleic acid, itaconic acid, anhydrides of these acids; fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, anhydrides of these acids; cyclohexanedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid; and the like.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl. Glycol, triethylene glycol, bis-hydroxyethyl terephthalate, cyclohexanedimethanol, octanediol, diethylpropanediol, butylethylpropanediol, 2-methyl-1,3-propanediol, 2,2,4-trimethylpentanediol, water Added bisphenol A, hydrogenated bisphenol A ethylene oxide adduct, hydrogenated bisphenol A propylene oxide adduct, trimethylolethane, trimethylolpropane, glycerin, petroleum Data erythritol, tris-hydroxyethyl isocyanurate, hydroxypivalic valyl hydroxy pivalate and the like.

The thermosetting polyester resin may be polycondensed with a monomer other than the polybasic acid and the polyhydric alcohol.
As the other monomer, for example, a compound having both a carboxyl group and a hydroxyl group in one molecule (for example, dimethanolpropionic acid, hydroxypivalate, etc.), a monoepoxy compound (for example, “Cadura E10 (Shell Co.)”) Such as glycidyl ester of branched aliphatic carboxylic acid)), various monohydric alcohols (eg, methanol, propanol, butanol, benzyl alcohol, etc.), various monovalent basic acids (eg, benzoic acid, p-tert. -Butylbenzoic acid, etc.), various fatty acids (for example, castor oil fatty acid, coconut oil fatty acid, soybean oil fatty acid, etc.) and the like.

  The structure of the thermosetting polyester resin may be a branched structure or a linear structure.

  The thermosetting polyester resin has a total acid value and hydroxyl value of 10 mgKOH / g or more and 250 mgKOH / g or less and a number average molecular weight of 1,000 or more and 100,000 or less from the viewpoint of excellent smoothness of the coating film. Polyester resins are preferred.

  The thermosetting resin contained in the core has a glass transition temperature (Tg) of preferably 60 ° C. or lower, and preferably 55 ° C. or lower, from the viewpoint of excellent smoothness of the coating film even when baked at a low temperature. More preferable. Further, the glass transition temperature (Tg) of the thermosetting resin contained in the core is preferably 40 ° C. or higher from the viewpoint of storage stability such as blocking.

  The thermosetting resins may be used alone or in combination of two or more.

  20 mass% or more and 99 mass% or less are preferable, and, as for content of the thermosetting resin of a core part, 30 mass% or more and 95 mass% or less are preferable.

-Other resins-
The core portion may include a non-curable resin. However, the proportion of the non-curable resin in the total resin in the core portion is preferably 5% by mass or less, more preferably 1% by mass or less, and substantially contained from the viewpoint of improving the curing density (crosslinking density) of the coating film. Preferably not. That is, the resin contained in the core is preferably only thermosetting resin.
When the core contains a non-curable resin, the non-curable resin is preferably at least one selected from the group consisting of (meth) acrylic resin and polyester resin.

-Thermosetting agent-
The thermosetting agent is selected according to the type of thermosetting reactive group of the thermosetting resin.
Specifically, when the thermosetting reactive group of the thermosetting resin is an epoxy group, as the thermosetting agent, for example, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, Dodecanedioic acid, eicosanedioic acid, maleic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, trimellitic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexene-1,2-dicarboxylic acid, tri Acids such as meritic acid and pyromellitic acid; anhydrides of these acids; urethane-modified products of these acids. Among these, as the thermosetting agent, an aliphatic dibasic acid is preferable from the viewpoint of coating film physical properties and storage stability, and dodecanedioic acid is particularly preferable from the viewpoint of coating film physical properties.

  When the thermosetting reactive group of the thermosetting resin is a carboxyl group, examples of the thermosetting agent include various epoxy resins (eg, polyglycidyl ether of bisphenol A), epoxy group-containing acrylic resins (eg, glycidyl group). Containing acrylic resin, etc.), polyglycidyl ethers of various polyhydric alcohols (eg, 1,6-hexanediol, trimethylolpropane, trimethylolethane, etc.), various polycarboxylic acids (eg, phthalic acid, terephthalic acid, Polyglycidyl ester of isophthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, trimellitic acid, pyromellitic acid, etc., various alicyclic epoxy group-containing compounds (for example, bis (3,4-epoxycyclohexyl) methyl) Adipate), hydroxyamide (eg triglyceride) Jill isocyanurate, beta-hydroxyalkylamide and the like) and the like.

  When the thermosetting reactive group of the thermosetting resin is a hydroxyl group, examples of the thermosetting agent include blocked isocyanate and aminoplast. As the isocyanate compound constituting the block type isocyanate, an organic diisocyanate, a polymer of an organic diisocyanate (including an isocyanurate type polyisocyanate compound), a polyhydric alcohol adduct of an organic diisocyanate, a low molecular weight polyester resin of an organic diisocyanate (for example, Polyester polyols) adducts, water adducts of organic diisocyanates, and the like. Here, as the organic diisocyanate, various aliphatic diisocyanates (for example, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, etc.), various cyclic aliphatic diisocyanates (for example, xylylene diisocyanate, isophorone diisocyanate, etc.), various aromatic diisocyanates (For example, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, etc.) and the like. Examples of the isocyanate group blocking agent include oxime compounds such as formaldoxime, acetoaldoxime, acetoxime, methylethylketoxime, methylisobutylketoxime, and cyclohexanoneoxime.

  The thermosetting agents may be used alone or in combination of two or more.

  The content of the thermosetting agent is preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 20% by mass or less with respect to the thermosetting resin of the core portion.

-Colorant-
Examples of the colorant include pigments. The colorant may use a dye together with the pigment.
Examples of the pigment include inorganic pigments such as iron oxide (eg, red iron oxide), titanium oxide, titanium yellow, zinc white, lead white, zinc sulfide, lithopone, antimony oxide, cobalt blue, carbon black; quinacridone red, phthalocyanine blue. , Phthalocyanine green, permanent red, Hansa yellow, indanthrene blue, brilliant fast scarlet, benzimidazolone yellow, and other organic pigments;
As the pigment, other bright pigments can also be used. Examples of bright pigments include pearl pigments, metal powders such as aluminum powder and stainless steel powder; metal flakes; glass beads; glass flakes; mica; scaly iron oxide (MIO);

  The colorants may be used alone or in combination of two or more.

  The content of the colorant is selected according to the type of pigment, the color required for the coating film, the brightness, the depth, and the like. For example, the content of the colorant is preferably 1% by mass or more and 70% by mass or less, and more preferably 2% by mass or more and 60% by mass or less with respect to the total resin of the core portion and the resin coating portion.

-Other additives-
Other additives include various additives used in powder coatings. Specifically, other additives include, for example, surface modifiers (silicone oil, acrylic oligomers, etc.), foaming (armpit) inhibitors (eg, benzoin, benzoin derivatives, etc.), curing accelerators (amine compounds, imidazole compounds). , Cationic polymerization catalysts, etc.), plasticizers, charge control agents, antioxidants, pigment dispersants, flame retardants, fluidizing agents and the like.

[Resin coating part]
The resin coating portion contains resin. The resin coating part may be composed only of resin, or may contain other additives (such as the thermosetting agent described in the core part and other additives). From the viewpoint of reducing the occurrence of bleeding on the surface of the powder particles, the resin coating portion is preferably made of resin only.

  The resin of the resin coating portion may be a non-curable resin or a thermosetting resin. The resin of the resin coating portion is preferably a thermosetting resin from the viewpoint of improving the curing density (crosslink density) of the coating film. When a thermosetting resin is applied as the resin of the resin coating portion, the thermosetting resin is preferably at least one selected from the group consisting of a thermosetting (meth) acrylic resin and a thermosetting polyester resin. The thermosetting resin of the resin coating portion may be the same type of resin as the thermosetting resin of the core portion, or may be a different type of resin. When the non-curable resin is applied as the resin of the resin coating portion, the non-curable resin is preferably at least one selected from the group consisting of (meth) acrylic resin and polyester resin.

  The resin contained in the resin coating portion preferably has a glass transition temperature (Tg) of 60 ° C. or lower, and more preferably 55 ° C. or lower, from the viewpoint of excellent smoothness of the coating film even when baked at a low temperature. .. Further, the glass transition temperature (Tg) of the resin contained in the resin coating portion is preferably 40 ° C. or higher from the viewpoint of storage stability such as blocking.

  From the viewpoint of suppressing the occurrence of bleeding on the powder particle surface, the coverage of the resin coating portion on the powder particle surface is preferably 30% or more and 100% or less, and more preferably 50% or more and 100% or less.

The coverage of the resin coating portion on the surface of the powder particles is obtained by X-ray photoelectron spectroscopy (XPS). Specifically, XPS is performed by using JPS-9000MX (JEOL Ltd.) as a measuring device, MgKα ray as an X-ray source, an accelerating voltage of 10 kV, and an emission current of 30 mA.
From the spectrum obtained under the above conditions, the component due to the material of the core of the powder particle surface and the component due to the material of the coating resin part are peak-separated to quantify the coverage of the resin coating part. In the peak separation, the measured spectrum is separated into each component by using curve fitting by the least square method. As the component spectrum that serves as a base for peak separation, a spectrum obtained by independently measuring the resin of the core portion, the curing agent, the pigment, the additive, and the resin of the resin coating portion used in the production of the powder particles is used. Then, the coverage is determined from the ratio of the spectrum intensity due to the resin of the resin coating portion to the total sum of all spectrum intensities.

The thickness of the resin coating portion is preferably 0.05 μm or more and 0.7 μm or less, more preferably 0.1 μm or more and 0.5 μm or less, from the viewpoint of suppressing bleeding on the surface of the powder particles.
The thickness of the resin coating part is a value measured by the following method. A thin section is prepared by embedding powder particles in epoxy resin or the like and cutting with a diamond knife or the like. This thin section is observed with a transmission electron microscope (TEM) or the like, and cross-sectional images of a plurality of powder particles are photographed. The thickness of the resin coating portion is measured at 20 locations from the cross-sectional image of the powder particles, and the average value is adopted. When it is difficult to distinguish between the resin coating portion and the core portion in a cross-sectional image of clear paint or the like, it is possible to facilitate the measurement by dyeing and observing.

  The content of the total thermosetting resin in the powder particles is preferably 20% by mass or more and 99% by mass or less, and more preferably 30% by mass or more and 95% by mass or less, based on the entire powder particles.

  The content of the total thermosetting agent in the powder particles is preferably 1% by mass or more and 35% by mass or less, and more preferably 3% by mass or more and 25% by mass or less, based on the total thermosetting resin of the entire powder particles.

[Metal ion with two or more valences]
From the viewpoint of the storability of the powder coating material, the powder particles preferably contain divalent or higher valent metal ions (hereinafter, also simply referred to as “metal ions”). When the powder particles have a structure having a core portion and a resin coating portion, the divalent or higher valent metal ions may be contained in either the core portion or the resin coating portion. The divalent or higher valent metal ions interact with the carboxyl groups or hydroxyl groups of the resin contained in the powder particles to form ionic crosslinks. By this ionic crosslinking, bleeding of various components on the surface of the powder particles is suppressed, and the storability of the powder coating material is improved.

  Examples of the divalent or higher valent metal ion include divalent or higher and tetravalent or lower metal ions. Specifically, for example, at least one metal ion selected from the group consisting of aluminum ion, magnesium ion, iron ion, zinc ion, and calcium ion can be mentioned.

  Examples of the metal ion supply source (compound to be included in the powder particles as an additive) include metal salts, inorganic metal salt polymers, and metal complexes. These are added to the powder particles as an aggregating agent, for example, when the powder particles are produced by the aggregation and coalescence method. In addition, for example, it is added to the powder particles as a catalyst for accelerating the thermosetting reaction, or is added without any particular limitation.

Examples of the metal salt include aluminum sulfate, aluminum chloride, magnesium chloride, magnesium sulfate, iron (II) chloride, zinc chloride, calcium chloride, calcium sulfate and the like.
Examples of the inorganic metal salt polymer include polyaluminum chloride, polyaluminum hydroxide, polyiron (II) sulfate, calcium polysulfide and the like.
Examples of the metal complex include metal salts of aminocarboxylic acid. As the metal complex, specifically, for example, a metal salt based on a known chelate acid such as ethylenediaminetetraacetic acid, propanediaminetetraacetic acid, nitriletriacetic acid, triethylenetetraminehexaacetic acid, diethylenetriaminepentaacetic acid (for example, calcium salt , Magnesium salt, iron salt, aluminum salt, etc.) and the like.

  The higher the valence of the metal ion, the easier it is to form a network-like ionic crosslink, which is preferable from the viewpoint of further improving the storability of the powder coating material. Therefore, Al ions are preferable as the metal ions. That is, as the metal ion supply source, an aluminum salt (eg, aluminum sulfate, aluminum chloride, etc.) and an aluminum salt polymer (eg, polyaluminum chloride, polyaluminum hydroxide, etc.) are preferable. Further, from the viewpoint of further improving the storability of the powder coating material, the inorganic metal salt polymer is preferable to the metal salt even if the metal ions have the same valence among the metal ion sources. Therefore, an aluminum salt polymer (for example, polyaluminum chloride, polyaluminum hydroxide, etc.) is particularly preferable as the metal ion supply source.

The content of the metal ion is preferably 0.002% by mass or more and 0.2% by mass or less, and 0.005% by mass or more 0 from the viewpoint of improving the storability of the powder coating material. 0.15 mass% or less is more preferable.
When the content of metal ions is 0.002% by mass or more, ionic crosslinking due to metal ions is appropriately formed, bleeding on the surface of the powder particles is suppressed, and the storability of the coating composition is improved. On the other hand, when the content of the metal ions is 0.2% by mass or less, excessive formation of ionic cross-links due to the metal ions does not occur and the smoothness of the coating film is excellent.

  When the powder particles are produced by the aggregating and coalescing method, the metal ion source (eg, metal salt, inorganic metal salt polymer, metal complex) added as an aggregating agent may have a particle size distribution and a shape of the powder particles. Contribute to control.

  Specifically, the higher the valence of the metal ion, the more suitable it is from the viewpoint of obtaining a narrow particle size distribution. Further, from the viewpoint of obtaining a narrow particle size distribution, an inorganic metal salt polymer is preferable to a metal salt even if the valences of the metal ions are the same. Therefore, also from these viewpoints, as the metal ion supply source, an aluminum salt (eg, aluminum sulfate, aluminum chloride, etc.), an aluminum salt polymer (eg, polyaluminum chloride, polyaluminum hydroxide, etc.) is preferable, Aluminum salt polymers (eg, polyaluminum chloride, polyaluminum hydroxide, etc.) are particularly preferred.

  Further, when the aggregating agent is added so that the content of the metal ion is 0.002% by mass or more, the aggregation of the resin particles in the aqueous medium progresses, which contributes to the realization of a narrow particle size distribution. Further, the aggregation of the resin particles forming the resin coating portion progresses with respect to the aggregated particles forming the core portion, which contributes to the formation of the resin coating portion on the entire surface of the core portion. On the other hand, when a flocculant is added so that the content of metal ions is 0.2% by mass or less, excessive formation of ionic crosslinks in the flocculated particles is suppressed, and powder particles produced at the time of coalescence. The shape of will be closer to a sphere. Therefore, from these viewpoints as well, the content of metal ions is preferably 0.002% by mass or more and 0.2% by mass or less, and more preferably 0.005% by mass or more and 0.15% by mass or less.

  The content of metal ions in powder particles is measured by X-ray fluorescence analysis (XRF). Specifically, for example, first, a resin and a metal ion supply source are mixed to obtain a resin mixture having a known metal ion concentration. From 200 mg of this resin mixture, pellet samples are obtained using a tableting machine with a diameter of 13 mm. The mass of this pellet sample is precisely weighed, the fluorescent X-ray intensity of the pellet sample is measured, and the peak intensity is obtained. Similarly, the pellet sample in which the addition amount of the metal ion supply source is changed is also measured, and a calibration curve is prepared from these results. Then, using this calibration curve, the content of metal ions in the powder particles to be measured is quantitatively analyzed.

  As the method for adjusting the content of the metal ions, for example, 1) a method of adjusting the addition amount of the metal ion supply source, and 2) when the powder particles are produced by the aggregation and coalescence method, in the aggregating step, After adding an aggregating agent (eg, metal salt, inorganic metal salt polymer) as a supply source, a chelating agent (eg, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, etc.) is added at the end of the aggregating step to form a chelate. Examples include a method of forming a complex of an agent and a metal ion, and removing a complex salt formed in a subsequent washing step or the like to adjust the content of the metal ion.

[External additive]
The external additive suppresses the occurrence of agglomeration between the powder particles. Thereby, a coating film having high smoothness can be formed with a small amount of powder coating material. Specific examples of the external additive include inorganic particles. As the inorganic particles, SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO.SiO. Examples thereof include particles of ₂ , K ₂ O. (TiO ₂ ) n, Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO ₄ .

  The surface of the inorganic particles as an external additive may be subjected to a hydrophobic treatment. The hydrophobic treatment is performed, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobizing agent is not particularly limited, and examples thereof include a silane coupling agent, silane, silicone oil, a titanate coupling agent, and an aluminum coupling agent. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is, for example, 1 part by mass or more and 10 parts by mass with respect to 100 parts by mass of the inorganic particles.

  As the external additive, silica particles are preferable, silica particles whose surface is hydrophobized are more preferable, and silica particles whose surface is hydrophobized with hexamethyldisilazane are preferable because they are more excellent in the clarity of the coating film. More preferable.

  The volume average particle diameter of the external additive is preferably 10 nm or more and 50 nm or less, more preferably 10 nm or more and 30 nm or less. By using an external additive having a volume average particle size of 10 nm or more and 50 nm or less, when the powder coating material is applied with a spray gun or the like, the powder particles are loosened by the air flow and easily fly as primary particles, The body particles may adhere to the object to be coated in the state of primary particles.

  The external addition amount of the external additive is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less, based on the powder particles.

<Production method of powder coating>
Next, a method for manufacturing the powder coating material according to the present embodiment will be described.
The powder coating material according to the present embodiment is obtained by producing powder particles and then externally adding an external additive to the powder particles, if necessary.

  In this embodiment, the powder particles are manufactured by a wet manufacturing method. Examples of the wet manufacturing method include an aggregation and coalescence method, a suspension polymerization method, and a dissolution suspension method, and the powder particles may be manufactured by any of these manufacturing methods. There is no particular limitation on these manufacturing methods, and known manufacturing methods are used. Among these, powder particles are preferably obtained by the aggregation and coalescence method from the viewpoint of easily controlling the volume particle size distribution index GSDv and the average circularity within the above ranges.

In particular,
A first aggregating step of aggregating the composite particles to form first agglomerated particles in a dispersion liquid in which composite particles containing a thermosetting resin and a thermosetting agent are dispersed;
The first agglomerated particle dispersion liquid in which the first agglomerated particles are dispersed, the second resin particle dispersion liquid in which the second resin particles containing a resin are dispersed, and ethylenediaminetetraacetic acid are mixed to obtain a mixture of the first agglomerated particles. A second aggregating step of aggregating the second resin particles on the surface to form second agglomerated particles in which the second resin particles adhere to the surface of the first agglomerated particles;
Heating the second aggregated particle dispersion liquid in which the second aggregated particles are dispersed to fuse and unite the second aggregated particles;
It is preferable to produce powder particles through
In the powder particles produced by the agglomeration and coalescence method, the portion where the first agglomerated particles are fused and coalesced is the core portion, and the portion where the second resin particles attached to the surface of the first agglomerated particles are fused and coalesced is the resin. It becomes the covering part.
In this aggregation and coalescence method, instead of "the second resin particle dispersion liquid in which the second resin particles containing the resin are dispersed", "the dispersion liquid in which the composite particles containing the thermosetting resin and the thermosetting agent are dispersed" May be used. In this case, the resin coating portion also contains a thermosetting agent.

  The details of each step will be described below. In the following description, a method for producing powder particles containing a colorant will be described, but the colorant is contained as necessary.

-Dispersion liquid preparation step-
First, each dispersion used in the aggregation and coalescence method is prepared. Specifically, a first resin particle dispersion liquid in which first resin particles containing a thermosetting resin in a core portion are dispersed, a thermosetting agent dispersion liquid in which a thermosetting agent is dispersed, and a colorant in which a coloring agent is dispersed. A dispersion liquid and a second resin particle dispersion liquid in which the second resin particles containing the resin of the resin coating portion are dispersed are prepared.
Alternatively, instead of the thermosetting agent dispersion liquid in which the first resin particle dispersion liquid and the thermosetting agent are dispersed, prepare a composite particle dispersion liquid in which composite particles containing the thermosetting resin and the thermosetting agent in the core part are dispersed. To do.
Hereinafter, the first resin particles, the second resin particles, and the composite particles will be collectively referred to as “resin particles” and described.

  The resin particle dispersion liquid is prepared, for example, by dispersing resin particles in a dispersion medium with a surfactant.

Examples of the dispersion medium used for the resin particle dispersion include an aqueous medium.
Examples of the aqueous medium include water such as distilled water and ion-exchanged water, alcohols and the like. These may be used alone or in combination of two or more.

As the surfactant, for example, sulfate ester-based, sulfonate-based, phosphate ester-based, soap-based anionic surfactants; amine salt-type, quaternary ammonium salt-type, etc. cationic surfactants; polyethylene glycol Examples thereof include nonionic surfactants such as polyphenols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly preferable. The nonionic surfactant may be used in combination with the anionic surfactant or the cationic surfactant.
The surfactants may be used alone or in combination of two or more.

Examples of the method for dispersing the resin particles in the dispersion medium in the resin particle dispersion include a general dispersion method using a rotary shear homogenizer, a ball mill having a medium, a sand mill, a dyno mill and the like. Further, depending on the type of resin particles, for example, the resin particles may be dispersed in the resin particle dispersion liquid by a phase inversion emulsification method.
The phase inversion emulsification method is to dissolve a resin to be dispersed in a hydrophobic organic solvent in which the resin is soluble, neutralize the organic continuous phase (O phase) by adding a base, and then to an aqueous medium (W phase). Is a method of converting the resin from W / O to O / W (so-called phase inversion) to form a discontinuous phase, and dispersing the resin in an aqueous medium into particles.

Specifically, in the case of a (meth) acrylic resin particle dispersion liquid, the monomer that constitutes the (meth) acrylic resin is emulsified in an aqueous medium, a water-soluble initiator and a chain transfer agent are added, and heating is performed to perform emulsion polymerization. As a result, a resin particle dispersion in which the (meth) acrylic resin particles are dispersed is obtained.
In the case of a polyester resin particle dispersion, the monomers constituting the polyester resin are melted by heating and polycondensed under reduced pressure, a solvent (for example, ethyl acetate) is added to the obtained polycondensate and dissolved, and an alkaline aqueous solution is further added. The resin particles are dispersed to obtain a resin particle dispersion in which the polyester resin particles are dispersed.

  The composite particle dispersion liquid is obtained by mixing a resin and a thermosetting agent and dispersing them in a dispersion medium (for example, emulsification such as phase inversion emulsification).

The volume average particle diameter of the resin particles dispersed in the resin particle dispersion is, for example, preferably 1 μm or less, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and 0.1 μm or more 0 0.6 μm is more preferable.
The volume average particle size of the resin particles is measured by a laser diffraction type particle size distribution measuring device (for example, LA-700, Horiba, Ltd.), and the volume average particle size is measured in terms of volume with respect to divided particle size ranges (channels). The cumulative distribution is drawn from the small particle size side, and the particle size at which the volume is 50% of all particles is defined as the volume average particle size D50v. The volume average particle size of the particles in the other dispersions is measured in the same manner.

  The content of the resin particles contained in the resin particle dispersion liquid is, for example, preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

  A thermosetting agent dispersion and a colorant dispersion are prepared in the same manner as the method for preparing the resin particle dispersion. That is, the dispersion medium, the surfactant, the dispersion method, the volume average particle diameter of the particles, and the particle content of the thermosetting agent dispersion liquid and the colorant dispersion liquid are the same as those of the resin particle dispersion liquid.

-First aggregation step-
Next, the first resin particle dispersion, the thermosetting agent dispersion, and the colorant dispersion are mixed.
Then, in the mixed dispersion liquid, the first resin particles, the thermosetting agent, and the colorant are hetero-aggregated, and the first resin particles, the thermosetting agent, and the colorant have a diameter close to the diameter of the target powder particle. Forming a first agglomerated particle containing.

  Specifically, for example, after adding a flocculant to the mixed dispersion, adjusting the pH of the mixed dispersion to acidic (for example, pH is 2 or more and 5 or less), and adding a dispersion stabilizer as necessary, The particles dispersed in the mixed dispersion are heated to a temperature close to the glass transition temperature of the first resin particles (specifically, for example, the glass transition temperature of the first resin particles −30 ° C. or more and the glass transition temperature or less). Aggregate to form first aggregated particles.

  In the first aggregating step, a composite particle dispersion liquid containing a thermosetting resin and a thermosetting agent is mixed with a colorant dispersion liquid, and the composite particles and the colorant are heteroaggregated in the mixed dispersion liquid. The first aggregated particles may be formed.

  In the first flocculation step, for example, the flocculating agent is added at room temperature (for example, 25 ° C.) while stirring the mixed dispersion with a rotary shear homogenizer, and the pH of the mixed dispersion is acidic (for example, pH is 2 or more and 5 or less). The temperature may be adjusted to 1, and a dispersion stabilizer may be added if necessary, and then heating may be performed.

  Examples of the aggregating agent include a surfactant having a polarity opposite to that of the surfactant contained in the mixed dispersion liquid, a metal salt, an inorganic metal salt polymer, and a metal complex. When a metal complex is used as the aggregating agent, the amount of the surfactant used is reduced and the charging characteristics are improved.

  The metal salt as the coagulant, the inorganic metal salt polymer, and the metal complex serve as a supply source of metal ions contained in the powder coating material. Examples of the metal salt, the inorganic metal salt polymer, and the metal complex are as described above.

-Second aggregation step-
Next, the first aggregated particle dispersion liquid in which the obtained first aggregated particles are dispersed, the second resin particle dispersion liquid, and ethylenediaminetetraacetic acid (EDTA) are mixed. The second resin particles may be the same as or different from the first resin particles.

  Then, in the mixed dispersion liquid in which the first aggregated particles and the second resin particles are dispersed, the first aggregated particles are aggregated so that the second resin particles are attached to the surface of the first aggregated particles and The second aggregated particles to which the resin particles are attached are formed.

Specifically, for example, in the first aggregation step, the second resin particle dispersion and EDTA are mixed with the first aggregated particle dispersion when the first aggregated particles reach the target particle size. At this time, in order to promote the aggregation of the second resin particles on the surface of the first aggregated particles, the second resin particle dispersion liquid and EDTA may be mixed while continuing to heat the first aggregated particle dispersion liquid. Next, the pH of the dispersion after mixing is adjusted to a range of, for example, 6.5 or more and 10.0 or less, and the progress of aggregation is stopped.
As a result, the second agglomerated particles obtained by aggregating the second resin particles on the surface of the first agglomerated particles are obtained.

In the present embodiment, it is preferable to add EDTA after mixing the second resin particle dispersion liquid and before adjusting the pH of the mixed dispersion liquid to the above range. EDTA and a metal ion contained as an impurity in the aqueous medium and a metal ion derived from the coagulant (for example, Ca ²⁺ , Mg ²⁺ , Cu ²⁺ , Fe ^2+, etc.) form a complex, and excess metal ion is formed. Chelate.

  The addition amount of EDTA is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, and more preferably 0.3 parts by mass or more and 1.5 parts by mass or less with respect to 100 parts by mass of all the resin particles.

A chelating agent other than EDTA may be added to the second aggregated particle dispersion liquid. Other chelating agents include water-soluble chelating agents, and specific examples thereof include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; aminocarboxylic acids such as iminodiacetic acid and nitrilotriacetic acid; Is mentioned.
The total addition amount of the chelating agent containing EDTA is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably 0.3 parts by mass or more and 1.5 parts by mass or less with respect to 100 parts by mass of all the resin particles. preferable.

-Fusion and unification process-
Next, with respect to the second aggregated particle dispersion liquid in which the second aggregated particles are dispersed, for example, the glass transition temperature of the first and second resin particles or higher (for example, from the glass transition temperature of the first and second resin particles Then, the second agglomerated particles are fused and coalesced to form powder particles.

  Powder particles are obtained through the above steps.

  After the completion of the coalescence step, the powder particles formed in the dispersion liquid are subjected to known washing step, solid-liquid separation step and drying step to obtain dry powder particles. In the washing step, from the viewpoint of chargeability, it is preferable to sufficiently perform displacement washing with ion-exchanged water. In the solid-liquid separation step, suction filtration, pressure filtration or the like may be performed from the viewpoint of productivity. From the viewpoint of productivity, it is preferable to perform freeze-drying, air-flow drying, fluidized drying, vibration-type fluidized drying and the like in the drying step.

  The powder coating material according to the present embodiment is manufactured by adding an external additive to the obtained powder particles in a dry state and mixing them, if necessary. The mixing is performed by, for example, a V blender, a Henschel mixer, a Loedige mixer, or the like. Further, if necessary, coarse particles of the powder coating material may be removed using a vibration sieving machine, a wind sieving machine or the like.

  The powder coating material according to the present embodiment is applied to known powder coating technology such as electrostatic coating and fluidized dipping.

<Coated products, manufacturing method of coated products>
The coated product according to the present embodiment is a coated product coated with the powder coating material according to the present embodiment. And the manufacturing method of the coated product which concerns on this embodiment is a manufacturing method of the coated product which coats with the powder coating material which concerns on this embodiment.

  Specifically, the coated article is obtained by coating the surface to be coated with the powder coating material and then heating (baking) the cured coating material to form a coating film. The coating and heating (baking) of the powder coating material may be performed collectively. For coating powder coating, well-known coating methods such as electrostatic coating and fluidized dipping are applied.

  The heating temperature for baking (baking temperature) is preferably 90 ° C or higher and 250 ° C or lower, more preferably 100 ° C or higher and 220 ° C or lower, still more preferably 100 ° C or higher and 200 ° C or lower, and further preferably 120 ° C or higher and 200 ° C or lower. The heating time for baking (baking time) is adjusted according to the heating temperature (baking temperature).

  The thickness of the coating film of the powder coating material is, for example, 10 μm or more and 100 μm or less, preferably 25 μm or more and 60 μm or less.

  The object to be coated with the powder coating material is not particularly limited, and various metal parts, ceramic parts, resin parts and the like can be mentioned. These target articles may be unformed articles before being formed into respective articles such as plate-like articles and linear articles, or molded articles for electronic parts, road vehicles, building interior and exterior materials, etc. It may be an item. Further, the target article may be an article whose surface to be coated has been subjected to surface treatment such as primer treatment, plating treatment, and electrodeposition coating in advance.

  Hereinafter, embodiments of the invention will be described in detail with reference to examples, but the embodiments of the invention are not limited to these examples. In the following description, "part" is based on mass unless otherwise specified.

<Method of measuring physical properties of resin>
The methods for measuring the physical properties of the polyester resin are as follows.

[Glass-transition temperature]
The glass transition temperature (Tg) of the polyester resin was determined by differential scanning calorimetry according to ASTM D3418-8. The measurement was specifically performed as follows.
The sample was set in a differential scanning calorimeter (DSC-50 type, Shimadzu Corporation) equipped with an automatic tangential processing system, liquid nitrogen was set as a cooling medium, and the temperature was raised from 0 ° C to 100 ° C at a heating rate of 10 ° C / min. (First heating process) to obtain a DSC curve, then cool to 0 ° C. at a temperature lowering rate of −10 ° C./min, and heat again from 0 ° C. to 150 ° C. at a temperature raising rate of 10 ° C./min. Then, the DSC curve was obtained (second heating process). The samples were held at 0 ° C. and 100 ° C. for 10 minutes each.
The melting temperature of the mixture of indium and zinc was used to correct the temperature of the detection part of the measuring device, and the heat of fusion of indium was used to correct the amount of heat. The sample was placed in an aluminum pan, and an aluminum pan containing the sample and an empty aluminum pan for control were set.
The glass transition temperature of the amorphous resin was defined as the temperature at the intersection of the base line and the rising line in the endothermic part of the DSC curve during the second heating process.

[Acid value and hydroxyl value]
The acid value and the hydroxyl value of the polyester resin were measured according to JIS K0070-1992.

[Weight average molecular weight and number average molecular weight]
The weight average molecular weight and the number average molecular weight of the polyester resin were measured by gel permeation chromatography (GPC). For the molecular weight measurement by GPC, HLC-8120GPC and SC-8020 (Tosoh) were used as measuring devices, TSKgel Super HM-M (6.0 mm ID × 15 cm) (Tosoh) was used as a column, and tetrahydrofuran was used as an eluent. .. The measurement conditions were a sample concentration of 0.5% by mass, a flow rate of 0.6 mL / min, a sample injection amount of 10 μL, and a measurement temperature of 40 ° C., and detection was performed with an RI detector. The calibration curve is based on Tosoh "polystyrene standard sample TSK standard": "A-500", "F-1", "F-10", "F-80", "F-380", "A-2500", "A-2500". It was created from 10 samples of "F-4", "F-40", "F-128", and "F-700".

<Example 1: Preparation of blue powder coating material C1>
[Preparation of Colorant Dispersion C1]
・ Cyan pigment (CI Pigment Blue 15: 3 (copper phthalocyanine), electrophotographic grade, Dainichiseika): 150 parts ・ Anionic surfactant (Neogen RK, Daiichi Kogyo Seiyaku): 20 parts ・ Ion exchange water: 350 Parts The above materials were mixed and dispersed for 1 hour using a high pressure impact disperser Ultimaizer (HJP30006, Sugino Machine) to prepare a solid content concentration of 25% by mass to obtain a colorant dispersion C1. In the colorant dispersion C1, the volume average particle diameter of the cyan pigment was 0.13 μm.

[Preparation of Colorant Dispersion Liquid W1]
-Titanium oxide (CR-60, Ishihara Sangyo): 200 parts-Anionic surfactant (Neogen RK, Daiichi Kogyo Seiyaku): 10 parts-Ion-exchanged water: 300 parts-1.0 mass% nitric acid aqueous solution: 15 parts The above materials and 600 parts of alumina beads having a diameter of 3 mm (Azuwan Co., Ltd.) are put into a 1000 mL bottle (Aiboy, Azuwan Co., Ltd.) and mixed with a tabletop ball mill at a rotation speed of 150 rpm for 24 hours to prepare a solid content concentration of 25% by mass. Thus, a colorant dispersion liquid W1 was obtained. In the colorant dispersion liquid W1, the volume average particle diameter of the titanium oxide pigment was 0.35 μm.

[Preparation of polyester resin PES1]
-Terephthalic acid: 100 mol parts-Ethylene glycol: 60 mol parts-Neopentyl glycol: 38 mol parts-Trimethylolpropane: 2 mol parts The above materials are equipped with a stirrer, a thermometer, a nitrogen gas inlet, and a rectification tower. The reaction vessel was charged and heated to 240 ° C. with stirring under a nitrogen atmosphere to carry out a polycondensation reaction. The obtained polyester resin PES1 had a glass transition temperature of 62 ° C., an acid value of 12 mgKOH / g, a hydroxyl value of 55 mgKOH / g, a weight average molecular weight of 12,000 and a number average molecular weight of 4000.

[Preparation of Composite Particle Dispersion E1]
While maintaining a jacketed 3 liter reaction vessel (BJ-30N, Tokyo Rikakikai) equipped with a condenser, a thermometer, a water dropping device, and an anchor blade at 40 ° C. in a water circulation type thermostat, ethyl acetate was added to the reaction vessel. A mixed solvent of 300 parts and 30 parts of isopropyl alcohol was added, and the following materials were added thereto.
-Polyester resin PES1: 240 parts-Thermosetting agent (VESTAGON B1530, Evonik): 60 parts-Benzoin: 1.5 parts-Acrylic oligomer (Acronal 4F, BASF): 3 parts

After charging the above materials, stirring was performed at a rotation speed of 150 rpm using a three-one motor to dissolve the materials and obtain an oil phase. To this stirred oil phase, 30 parts of 10 mass% aqueous ammonia solution was added dropwise for 5 minutes, mixed for 10 minutes, and then 900 parts of ion-exchanged water was added dropwise at a rate of 5 parts per minute to invert the phase. An emulsion was obtained.
Immediately, 800 parts of the obtained emulsion and 700 parts of ion-exchanged water were placed in a 2-liter eggplant flask and set in an evaporator (Tokyo Rika Kikai) equipped with a vacuum control unit via a trap ball. While rotating the eggplant flask, the mixture was heated in a hot water bath at 60 ° C., and while paying attention to bumping, the pressure was reduced to 7 kPa to remove the solvent. When the solvent recovery amount reached 1100 parts, the pressure was returned to normal pressure, and the eggplant flask was water-cooled to obtain a dispersion liquid of composite particles containing the polyester resin PES1 and the thermosetting agent. There was no solvent odor in the obtained dispersion.

  Thereafter, an anionic surfactant (Dowfax2A1, Dow Chemical Co., active ingredient amount 45 mass%) was added and mixed in an amount of 2 mass% as an active ingredient to the resin component in the dispersion liquid, and ion-exchanged water was added to solid content concentration. It was adjusted to 25% by mass. This was designated as composite particle dispersion E1. The volume average particle size of the composite particles in the composite particle dispersion E1 was 145 nm.

[Coagulation process]
・ Composite particle dispersion E1: 180 parts (solid content 45 parts)
Colorant dispersion W1: 160 parts (solid content 40 parts)
Colorant dispersion C1: 8 parts (solid content 2 parts)
Ion-exchanged water: 200 parts The above materials were mixed and dispersed in a round stainless steel flask with a homogenizer (Ultra Turrax T50, IKA Co.). Then, the pH was adjusted to 3.5 using a 1.0 mass% nitric acid aqueous solution. To this, 12 parts of a 1 mass% polyaluminum chloride aqueous solution was added, and the dispersion operation was continued using a homogenizer.
A stirrer and a mantle heater were installed, and the temperature was raised at 0.2 ° C./min while adjusting the rotation speed of the stirrer so that the slurry was sufficiently stirred, and when the volume average particle size became 5.0 μm, the composite 80 parts (solid content 20 parts) of the particle dispersion E1 was slowly added.

  After being charged for 30 minutes, 1.5% by mass of ethylenediaminetetraacetic acid (EDTA) (CHIREST 40, CREST CORPORATION) was added to the resin solid content, and then the pH was adjusted using a 5% by mass sodium hydroxide aqueous solution. It was adjusted to 8.5, and 0.3 mass% of sodium dodecylbenzenesulfonate was further added to the resin solid content.

[Fusion and unification process]
Then, it heated up to 85 degreeC and hold | maintained for 2 hours. It was confirmed with an optical microscope that the particles in the dispersion were substantially spherical.

[Filtration step, washing step, drying step]
After the completion of the fusion and coalescence step, the solution in the flask was cooled and filtered to obtain a solid content. Next, this solid content was thoroughly washed with ion-exchanged water, and then solid-liquid separated by Nutsche suction filtration to obtain a solid content again. Next, this solid content was redispersed in 3 liters of ion-exchanged water at 40 ° C., and washed by stirring at a rotation speed of 300 rpm for 15 minutes. This washing operation was repeated 5 times, and the solid content obtained by solid-liquid separation by Nutsche suction filtration was vacuum dried for 12 hours to obtain blue powder particles C1. Table 1 shows the physical properties of the blue powder particles C1.

[External addition of external additives]
100 parts of blue powder particles C1 and 0.5 parts of hydrophobic silica particles (RX300, hydrophobic fumed silica surface-modified with hexamethyldisilazane, Nippon Aerosil Co., Ltd.) as an external additive were put into a sample mill (SK. -M10, Kyoritsu Riko), and the mixture was stirred at a rotation speed of 13000 rpm for 30 seconds. Then, it was sifted with a vibrating screen having openings of 45 μm to obtain a blue powder coating material C1.

<Example 2: Preparation of blue powder coating C2>
In the aggregation step of Example 1, blue powder particles C2 and blue powder coating material C2 were prepared in the same manner as in Example 1 except that the composite particle dispersion liquid E1 was added when the volume average particle diameter reached 3.6 μm. It was made.

<Example 3: Preparation of blue powder coating C3>
In the aggregation step of Example 1, the same procedure as in Example 1 was carried out except that the composite particle dispersion E1 was added when the volume average particle size reached 9.8 μm and the amount of EDTA added was changed to 3.0% by mass. Thus, blue powder particles C3 and blue powder coating material C3 were produced.

<Example 4: Preparation of blue powder coating C4>
In the aggregation step of Example 1, blue powder was obtained in the same manner as in Example 1 except that 0.1% by mass of EDTA was added, and then the pH was adjusted to 9.3 using a 5% by mass aqueous sodium hydroxide solution. Body particles C4 and blue powder coating material C4 were produced.

<Example 5: Preparation of blue powder coating C5>
Blue powder was prepared in the same manner as in Example 1 except that the polyester resin PES1 was changed to 260 parts and the thermosetting agent (VESTAGON B1530, Evonik) was changed to 40 parts in the preparation of the composite particle dispersion E1 of Example 1. Particles C5 and blue powder coating material C5 were prepared.

<Example 6: Preparation of blue powder coating material C6>
Blue powder particles C6 and blue powder coating material C6 were produced in the same manner as in Example 1 except that the thermosetting agent was changed to VESTAGON B1358 (Evonik) in the preparation of the composite particle dispersion liquid E1 of Example 1. ..

<Example 7: Preparation of blue powder coating C7>
Blue powder particles C7 and blue powder coating material C7 were produced in the same manner as in Example 6 except that the polyester resin PES1 was changed to 210 parts and the thermosetting agent was changed to 90 parts.

<Example 8: Preparation of blue powder coating C8>
[Preparation of polyester resin PES2]
-Terephthalic acid: 80 parts by mole-Isophthalic acid: 20 parts by mole-2,2-diethyl-1,3-propanediol: 70 parts by mole-Neopentyl glycol: 28 parts by mole-Trimethylolpropane: 2 parts by mole Was charged into a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet, and a rectification column, and the temperature was raised to 240 ° C. under stirring in a nitrogen atmosphere to carry out a polycondensation reaction. The obtained polyester resin PES2 had a glass transition temperature of 50 ° C., an acid value of 15 mgKOH / g, a hydroxyl value of 50 mgKOH / g, a weight average molecular weight of 13,500 and a number average molecular weight of 3,800.

[Preparation of Composite Particle Dispersion E2]
A composite particle dispersion E2 was obtained by the same operation as in the preparation of the composite particle dispersion E1 of Example 1, except that the polyester resin PES1 was changed to the polyester resin PES2. The volume average particle size of the composite particles in the composite particle dispersion E2 was 130 nm.

  Hereinafter, blue powder particles C8 and blue powder coating material C8 were produced in the same manner as in Example 1 except that the composite particle dispersion liquid E1 was changed to the composite particle dispersion liquid E2.

<Example 9: Preparation of blue powder coating C9>
[Preparation of polyester resin PES3]
・ Terephthalic acid: 80 parts by mole ・ Isophthalic acid: 20 parts by mole ・ 2,2-diethyl-1,3-propanediol: 78 parts by mole ・ Neopentyl glycol: 20 parts by mole ・ Trimethylolpropane: 2 parts by mole Was charged into a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet, and a rectification column, and the temperature was raised to 240 ° C. under stirring in a nitrogen atmosphere to carry out a polycondensation reaction. The obtained polyester resin PES3 had a glass transition temperature of 47 ° C., an acid value of 13 mgKOH / g, a hydroxyl value of 52 mgKOH / g, a weight average molecular weight of 13,000, and a number average molecular weight of 3,500.

[Preparation of Composite Particle Dispersion E3]
A composite particle dispersion E3 was obtained by the same operation as in the preparation of the composite particle dispersion E1 of Example 1, except that the polyester resin PES1 was changed to the polyester resin PES3. The volume average particle diameter of the composite particles in the composite particle dispersion E3 was 180 nm.

  Hereinafter, blue powder particles C9 and blue powder coating material C9 were prepared in the same manner as in Example 1 except that the composite particle dispersion liquid E1 was changed to the composite particle dispersion liquid E3.

<Example 10: Preparation of blue powder coating C10>
Blue powder particles C10 and blue powder coating material C10 were prepared in the same manner as in Example 1 except that the external additive was changed to RY300 (dimethyl silicone oil treatment, Nippon Aerosil Co., Ltd.).

<Example 11: Preparation of blue powder coating C11>
Blue powder particles C11 and blue powder coating material C11 were prepared in the same manner as in Example 1 except that the external additive was changed to Alu130 (aluminum oxide particles, octylsilane treatment, Nippon Aerosil Co., Ltd.). ..

<Example 12: Preparation of blue powder coating C12>
Blue powder particles C12 and blue powder were obtained in the same manner as in Example 1 except that the external additive was changed to RX50 (hexamethyldisilazane treatment, primary particle size about 50 nm, Nippon Aerosil Co., Ltd.). Paint C12 was prepared.

<Comparative Example 1: Preparation of blue powder coating material XC1>
In the aggregation step of Example 1, blue powder particles XC1 and blue powder were obtained in the same manner as in Example 1 except that EDTA was not added and the pH was adjusted to 9.5 using a 5 mass% sodium hydroxide aqueous solution. Body paint XC1 was prepared.

<Comparative Example 2: Preparation of blue powder coating material XC2>
In the aggregation step of Example 3, blue powder particles XC2 and blue powder coating material XC2 were produced in the same manner as in Example 3 except that the addition amount of EDTA was changed to 3.5% by mass with respect to the resin solid content. did.

<Comparative Example 3: Preparation of blue powder coating material XC3>
In the aggregation step of Example 1, except that EDTA was changed to 4-sodium 3-hydroxy-2,2′-iminodisuccinate (HIDS) (Nippon Catalyst) and 3.0 mass% was added to the resin solid content. In the same manner as in Example 1, blue powder particles XC3 and blue powder coating material XC3 were produced.

<Evaluation>
[Preparation of coating film sample]
The powder coating was applied to a mirror-finished aluminum plate test panel (30 cm × 30 cm) from a distance of 30 cm from the front with a corona gun (XR4-110C, Asahi Sunac Co., Ltd.), and then the object to be coated was set to 190 ° C. It was placed in a high temperature chamber and heated (baked) for 30 minutes to obtain a coating film sample.

[Smoothness and sharpness of coating film]
Using a surface roughness measuring instrument (SURFCOM 1400A, Tokyo Seimitsu Co., Ltd.), according to the manual of the measuring apparatus, the center line average roughness Ra (unit: μm) and the filtered center line waviness Wca (unit: μm) of the surface of the coating film sample ) Was measured. In both cases, the smaller the number, the better the surface smoothness of the coating film.
Ra is a general surface smoothness index and is known to have a high correlation with the glossiness. Wca is a smoothness index including large undulations and is associated with sharpness. In the present embodiment, Wca of 0.1 or less means sharpness in which the shape of the fluorescent lamp is clearly visible.

[Solvent resistance of coating film]
The obtained coating film was rubbed 10 times with a cotton swab dipped in a methyl ethyl ketone solvent, and then left standing at room temperature for 12 hours, and the surface condition was visually observed. There was no damage in any of the coatings.

Claims (9)

A powder particles produced by the wet process, the powder particles is the content of ethylenediaminetetraacetic acid is 0.05 wt% or more 0.0001 wt% based on the total weight of the powder particles,
Adhering to the surface of the powder particles, see containing silica particles surface-treated with hexamethyldisilazane, and
A thermosetting powder whose viscoelastic spectrum measured under the conditions of a temperature range of 80 ° C. to 200 ° C., a temperature rising rate of 1 ° C./min, and a frequency of 1 rad / sec satisfies the following (1), (2) and (3). paint.
(1) The temperature T1 at which the storage elastic modulus G ′ starts to fall below 10000 Pa is 120 ° C. or lower.
(2) There is a temperature region where the loss tangent exceeds 1 at 120 ° C or lower.
(3) There is a temperature T2 at which the loss tangent starts to fall below 1 in a temperature region higher than the temperature region where the loss tangent exceeds 1, and the temperature T2 is more than 120 ° C and 190 ° C or less. The thermosetting powder coating material according to claim 1 , wherein the viscoelastic spectrum further satisfies the following (4).
(4) 20 ° C. ≦ (temperature T2−temperature T1) <100 ° C. The powder particles have a core portion containing a thermosetting resin and a thermosetting agent, and a resin coating portion containing a thermosetting resin and coating the core portion. Thermosetting powder coating of. The thermosetting powder coating material according to claim 3, wherein the core portion and the resin coating portion contain a thermosetting polyester resin. The thermosetting powder coating material according to claim 4, wherein the thermosetting polyester resin contains a thermosetting polyester resin having a glass transition temperature of 60 ° C or lower. The volume average particle diameter of the powder particles is 4μm or more 12μm or less, according to claim 1 thermosetting powder paint according to any one of claims 5. The thermosetting powder coating material according to any one of claims 1 to 6 , wherein the average circularity of the powder particles is 0.965 or more and 0.995 or less.   A coated article coated with the thermosetting powder coating material according to any one of claims 1 to 7.   A method for producing a coated article, which comprises coating with the thermosetting powder coating material according to any one of claims 1 to 7.