JP7078032B2 - Compositions for powder coatings and coated articles - Google Patents

Description

The present invention relates to a composition for powder coating material and a coated article.

The powder coating material is a coating material that does not contain a volatile component such as an organic solvent and that forms a coating film by coating and melting only the coating film forming component on a base material. Compared to conventional solvent-based paints, powder paints have the advantages of being able to be applied thicker at one time, being able to recover and reuse powder that did not adhere, and having less waste paint. From the viewpoint of rationalization of painting and environmental friendliness, there are various fields such as building / building materials field, electricity / communication field, automobile / vehicle field, road material field, water / gas material field, steel furniture field and construction machine / industrial machine field. Widely used in the field of industrial products.

Epoxy-based, vinyl chloride-based, polyolefin-based, acrylic-based and polyester-based compositions are known as compositions for powder coating materials, but they have high weather resistance especially in outdoor applications such as construction / building materials and automobiles / vehicles. As a result, polyesters are widely used as paints with well-balanced coating performance. However, in recent years, the demand for weather resistance has been increasing year by year, and there is a demand for a composition for powder coating material which is remarkably excellent in weather resistance under more severe conditions.
In addition, in outdoor applications such as the field of construction / building materials and the field of automobiles / vehicles, the coating film is not only slippery (hereinafter referred to as "slip resistance") from the viewpoint of ensuring the safety of users and passersby as well as weather resistance. ) And the 60 ° mirror surface gloss of the coating film should be suppressed to 40% or less (hereinafter referred to as "matte property"), and the smoothness of the coating film should be satisfied at the same time from the viewpoint of design. Has been done.

Conventionally, various compositions for powder coating materials containing a specific polyester resin have been proposed.

Patent Document 1 discloses a composition for a coating material for powder, which comprises a polyester resin having a specific structure and a blocked isocyanate.

Patent Document 2 discloses a composition for powder coating material containing a polyester resin having a specific hydroxyl value, a blocked isocyanate, and a specific surface conditioner having an ultraviolet absorbing ability.

Patent Document 3 discloses a composition for powder coating materials in which a fluororesin is blended with a polyester resin having a specific melt viscosity. This is because the polyester resin and the fluororesin are separated into layers in the process of forming the coating film, and the polyester layer is arranged on the base material side and the fluororesin layer is arranged on the air side, so that a coating film having significantly excellent weather resistance can be obtained. Be done.

Patent Document 4 discloses a composition for powder coating material containing a polyester resin having a specific structure and a blocked isocyanate.

Patent Document 5 discloses a composition for powder coating materials containing a hydroxyl group-containing polyester resin, polyisocyanate and polyolefin wax.

Japanese Unexamined Patent Publication No. 6-220359 Japanese Unexamined Patent Publication No. 11-124541 Japanese Unexamined Patent Publication No. 2011-12119 Japanese Unexamined Patent Publication No. 2004-18547 Japanese Unexamined Patent Publication No. 9-143401

However, although the composition described in Patent Document 1 is excellent in weather resistance by the sunshine carbon arc type weather meter test, it is weather resistant under harsh conditions close to the spectral distribution of sunlight by the xenon type weather meter test. There was a problem of inferior sex.
The compositions described in Patent Documents 2 and 3 have a problem that the smoothness of the coating film is excellent, but the weather resistance by the xenon type weather meter test is inferior.
The composition described in Patent Document 4 is excellent in smoothness and mattness of the coating film, but has a problem that the weather resistance by the xenon type weather meter test is inferior and the anti-slip property is also inferior.
In the composition described in Patent Document 5, although the smoothness of the coating film is excellent, no weather resistance is suggested, and the anti-slip property and matte property of the coating film are inferior.
As described above, it was difficult to simultaneously satisfy the weather resistance, anti-slip property, matte property and smoothness.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a composition for a powder coating material having excellent weather resistance, anti-slip property, matte property and smoothness of a cured film.

As a result of diligent studies to solve the above problems, the present inventors have obtained a coating film obtained from a composition for powder coating material containing a hydroxyl group-containing polyester resin having a specific weight average molecular weight, molecular weight distribution and structure and blocked isocyanate. The present invention has been completed by finding that it is excellent in weather resistance, anti-slip property, matte property and smoothness.

The present invention is as follows.
[1] A composition for powder coating material containing the following components (A) and (B) as essential components.
Component (A): Aliphatic polyhydric alcohol (b) having a weight average molecular weight of 20,000 to 140,000 and a molecular weight distribution of 4.0 to 26, and does not have a dicarboxylic acid compound (а) component and a secondary hydroxyl group. ) Component-containing polyester resin containing a reactant (B) Component: Blocked isocyanate compound
[2] The composition for powder coating material according to [1], wherein the component (a) contains isophthalic acid.
[3] The composition for powder coating material according to [1] or [2], wherein the hydroxyl group β-position of the component (b) is a quaternary carbon.
[4] The composition for powder coating material according to any one of [1] to [3], wherein the component (A) has a melt viscosity at 200 ° C. of 50 to 150 dPa · s.
[5] The composition for powder coating material according to any one of [1] to [4], which further contains a wax (C) component.
[6] The composition for powder coating material according to [5], wherein the component (C) contains polypropylene wax.
[7] A coated article having a cured film formed from the composition for powder coating according to any one of [1] to [6] on the surface.

According to the composition for powder coating material of the present invention, the cured film can be excellent in weather resistance, anti-slip property, matte property and smoothness.

The present invention relates to a composition for powder coating material and a coated article containing the following components (A) and (B) as essential components.
(A) component: It has a weight average molecular weight of 20,000 to 140,000, a molecular weight distribution of 4.0 to 26, and has a dicarboxylic acid compound (hereinafter referred to as "component (a)") and a secondary hydroxyl group. Not a hydroxyl group-containing polyester resin (B) component containing a reactant of an aliphatic polyhydric alcohol (hereinafter referred to as "(b) component"): Block isocyanate or less, (A) component, (B) component, for powder coating A method for producing a composition, a composition for powder coating, a coated article, and an application will be described.

1. 1. (A) Component The component (A) has a weight average molecular weight of 20,000 to 140,000 and a molecular weight distribution of 4.0 to 26, and contains a hydroxyl group containing a reaction product of the component (a) and the component (b). It is a polyester resin.
In the present invention, the weight average molecular weight (hereinafter referred to as "Mw") and the number average molecular weight (hereinafter referred to as "Mn") are referred to as gel permeation chromatography (hereinafter referred to as "GPC"). ) Is a value obtained by converting the molecular weight into polystyrene, and the molecular weight distribution (hereinafter referred to as “Mw / Mn”) is a value obtained by dividing Mw by Mn.

The molecular weight measured by GPC in the present invention means a value measured under the following conditions.
・ Detector: Differential refractometer (RI detector)
-Column type: Cross-linked polystyrene column-Column temperature: In the range of 25 to 50 ° C.-Eluent: Tetrahydrofuran (hereinafter referred to as "THF")

Mw is 20,000 to 140,000 in that the weather resistance of the coating film can be improved. Further, 30,000 or more is preferable, and 40,000 or more is more preferable, because the smoothness of the coating film is excellent particularly in a thick film. Further, 100,000 or less is preferable, and 70,000 or less is more preferable, in that the melt viscosity can be appropriately lowered.

Mw / Mn is 4.0 to 26 in that the weather resistance of the coating film can be improved. Further, 6.0 or more is preferable, and 8.0 or more is more preferable, especially in the case of a thick film, in that the smoothness of the coating film is excellent. Further, 20 or less is preferable in that the melt viscosity can be appropriately lowered, and 15 or less is more preferable in that the smoothness of the coating film is excellent.

The hydroxyl value of the component (A) is preferably 10 to 100 mgKOH / g, more preferably 20 to 70 mgKOH / g, in terms of excellent weather resistance and strength of the coating film.
In the present invention, the hydroxyl value means the number of mg of potassium hydroxide equivalent to the hydroxyl group in 1 g of the sample.

The acid value of the component (A) is preferably 0.1 to 10 mgKOH / g, more preferably 0.1 to 7.0 mgKOH / g, in terms of excellent weather resistance and strength of the coating film.

In the present invention, the acid value means the number of mg of potassium hydroxide equivalent to the carboxyl group in 1 g of the sample.

The melt viscosity of the component (A) at 200 ° C. is preferably 50 to 150 dPa · s, more preferably 70 to 110 dPa · s, in terms of excellent smoothness of the coating film.

The component (A) can be produced by a known production method using the component (a) and the component (b) as raw materials. At the time of the reaction, if desired, a slurry can be formed by adding a small amount of water in order to maintain the fluidity in the reaction system at the initial stage of the reaction. Further, as a reaction method, either a transesterification reaction or a direct esterification reaction can be applied, and polycondensation can be promoted by a method such as a reduced pressure method or a reaction while introducing an inert gas under normal pressure. Further, in the above reaction, a known reaction catalyst such as dibutyl tin oxide can be used.

As the component (A), only one kind may be used, or two or more kinds may be used in combination.

1-1. (A) Component The component (a) is a dicarboxylic acid compound.
Specific examples of the component (a) include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, 1,9-nonandicarboxylic acid, 1,10-decandicarboxylic acid, and 1,12. -Adicyclic dicarboxylic acid compounds such as dodecanedicarboxylic acid and 1,2-octadecanedicarboxylic acid, alicyclic dicarboxylic acid compounds such as 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and hexahydrophthalic acid, phthal. Examples thereof include acids, isophthalic acids, terephthalic acids, naphthalenedicarboxylic acids, aromatic dicarboxylic acid compounds of trimellitic acid and pyromellitic acid, and acid anhydrides thereof.

Among these, aromatic dicarboxylic acid compounds are preferable, and isophthalic acid is particularly preferable, because the weather resistance can be improved. In this case, the content of isophthalic acid is preferably 60 to 100 mol% in the total amount of the dicarboxylic acid compound in that the weather resistance of the coating film can be improved.

These may be used alone or in combination of two or more.

In terms of excellent weather resistance, the content of the component (а) is preferably 40 to 60 mol%, more preferably 45 to 55 mol% in 100 mol% of the total amount of the component (а) and the component (b). ..

1-2. (B) Component The component (b) is an aliphatic polyhydric alcohol having no secondary hydroxyl group.
Specific examples of the component (b) include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6. -Dihydric alcohols such as hexanediol, 1,10-decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, spiroglycol and 2-butyl-2-ethyl-1,3-propanediol, trimethylolpropane and the like. Examples thereof include trihydric alcohols and tetrahydric alcohols such as pentaerythritol.

Among these, neopentyl glycol, spiroglycol, 2-butyl-2-ethyl-1,3-propanediol, trimethylolpropane and pentaerythritol, whose hydroxyl group β-position is a quaternary carbon, are excellent in weather resistance. Is preferable, and neopentyl glycol, trimethylolpropane and 2-butyl-2-ethyl-1,3-propanediol are particularly preferable.

Further, from the viewpoint of excellent weather resistance, neopentyl glycol and trimethylolpropane having an alkyl group directly connected to the quaternary carbon at the β-position of the hydroxyl group having 3 or less carbon atoms are preferable.

These may be used alone or in combination of two or more.

In terms of excellent weather resistance, the content of the component (b) is preferably 40 to 60 mol%, more preferably 45 to 55 mol% in 100 mol% of the total amount of the component (а) and the component (b). .. Further, the content of the divalent alcohol is preferably 30 to 60 mol% in 100 mol% of the total amount of the component (а) and the component (b) in that the melt viscosity can be appropriately lowered, and is trivalent or 4 The content of the valent alcohol is preferably 0 to 10 mol% in 100 mol% of the total amount of the component (а) and the component (b).

2. 2. Component (B) The component (B) is a blocked isocyanate compound, preferably a solid at room temperature.

The component (B) is produced by reacting an aliphatic, aromatic and aromatic aliphatic polyhydric isocyanate compound with a blocking agent and masking, and those skilled in the art can easily produce the component. Is.

Specific examples of the polyhydric isocyanate compound include hexamethylene diisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), methylcyclohexanediisocyanate, bis (isocyanatemethyl) cyclohexane, isophorone diisocyanate, dimerate diisocyanate, lysine diisocyanate, and tolylene diisocyanate. Examples thereof include dihydric isocyanate compounds such as 4,4'-diphenylmethane isocyanate and xylylene diisocyanate, trimerics of hexamethylene diisocyanate and trivalent isocyanate compounds such as lysine triisocinenate.

Specific examples of the blocking agent include alcohols such as methanol, ethanol and benzyl alcohol, phenols such as phenol and crezone, lactams such as caprolactam and butyrolactam, and oximes such as cyclohexanone, oxime and methylethylketooxime.

As the component (B), a polyisocyanate compound obtained by reacting an aliphatic, aromatic and aromatic aliphatic polyhydric isocyanate compound with a low molecular weight compound having active hydrogen is reacted with a blocking agent to mask it. It may be manufactured by the above.

Specific examples of the low molecular weight compound having active hydrogen include water, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, ethanolamine, diethanolamine, hexamethylenediamine and the like, as well as isocyanurate. Examples thereof include uretidione, hydroxyl group-containing low molecular weight polyester and polycaprolactone.

The content of the component (B) is such that the hardness, heat resistance, moisture resistance and chemical resistance of the cured film are excellent, and the molar ratio of the isocyanate group to the hydroxyl group in the composition for powder coating material is 0.5 to 1. It is preferably 5, more preferably 0.9 to 1.2.

3. 3. Composition for powder coating material The composition for powder coating material of the present invention contains the above-mentioned components (A) and (B) as essential components, but various other components may be blended depending on the purpose. can. The composition for powder coating material of the present invention does not contain fluororesin in that it has excellent adhesion to the primer layer in coating (hereinafter referred to as 2-coat coating) in which a primer treatment is applied onto a substrate. Is preferable.

Specific examples of the other components include wax [hereinafter referred to as "(C) component". ], Curing catalyst [hereinafter referred to as "(D) component". ], UV absorber [hereinafter referred to as "(E) component". ], Hindered amine-based light stabilizer [hereinafter referred to as "(F) component". ], Pigment [hereinafter referred to as "(G) component". ], Leveling agents, pinhole inhibitors and the like.

Hereinafter, these components will be described.
As the other components described later, only one of the exemplified compounds may be used, or two or more of them may be used in combination.

3-1. Component (C) The component (C) is a wax and can be blended for the purpose of imparting a matte property to the coating film.

Examples of the component (C) include synthetic wax and animal / vegetable or mineral natural wax.

Specific examples of the synthetic wax include hydrocarbon waxes such as polyethylene wax and polypropylene wax, and long-chain alcohols such as aliphatic amine wax, palmityl alcohol and stearyl alcohol obtained by the reaction of hydrogenated castor oil with monoethanolamine. Examples thereof include reaction products with acids such as palmitic acid and myristic acid, fatty acid esters such as fatty acid glycerides, and glycol esters.

Specific examples of the natural wax include Japanese wax, carnaupa wax, shellac wax, paraffin wax and the like.

Among these, hydrocarbon wax is preferable because it can be excellent in matte property and weather resistance of the coating film, and polypropylene wax is preferable in that it can be balanced with anti-slip property.

The melting point of the component (C) is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. When the melting point is 100 ° C. or higher, the storage stability of the coating powder is improved, and when the melting point is 150 ° C. or higher, the anti-slip property is improved.

The content ratio of the component (C) is preferably 1 to 15 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B). When the proportion of the component (C) is 1 part by mass or more, the matting property is excellent, and when the ratio is 15 parts by mass or less, the weather resistance is excellent.

3-2. Component (D) The component (D) is a curing catalyst and can be blended for the purpose of accelerating curing and obtaining excellent coating film physical characteristics.
The composition for powder coating material of the present invention preferably further contains the component (D) from the viewpoint of ease of curing and physical characteristics of the coating film.

As the component (D), a tin catalyst is preferable, and specific examples thereof include tin octylate, tributyltin laurate, dibutyltin dilaurate, and di-normalbutyltin malate polymers.

As the curing catalyst, one type may be used alone, or two or more types may be used in combination.

The content ratio of the component (D) is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). When the proportion of the component (D) is 0.001 part by mass or more, a sufficient catalytic effect can be easily obtained, and when it is 10 parts by mass or less, the composition is melted and cured in the process of melting and curing the composition for powder coating. Gas such as air caught in the gas is easily released, and the heat resistance, weather resistance, and water resistance of the cured film caused by the residual gas tend to be small.

3-3. Component (E ) Component (E) is an ultraviolet absorber and can be blended for the purpose of improving the light resistance of the cured film.

Examples of the component (E) include a triazine-based ultraviolet absorber and a benzotriazole-based ultraviolet absorber.

The molecular weight of the component (E) is preferably 200 to 1,000. When the molecular weight is 200 or more, it is difficult to volatilize in the melting and curing process of the composition for powder coating, and it can remain in the cured film. When the molecular weight is 1,000 or less, it has good compatibility with the molten coating and impairs the smoothness of the cured film. do not have.

The melting point of the component (E) is preferably a compound having a melting point of 50 to 150 ° C. When the melting point is 50 ° C. or higher, the smoothness of the coating film is improved, and when the melting point is 150 ° C. or lower, the coating film is easily melted in the melting and curing processes and can be uniformly present in the coating film.

As the component (E), a commercially available product may be used, and the commercially available products include TINUVIN326 (molecular weight: 315.8, melting point: 139 ° C.) and TINUVIN405 (molecular weight: 583.8, melting point: 74 to 77 ° C.) manufactured by BASF. , TINUVIN460 (molecular weight: 629.8, melting point: 93 to 102 ° C.), TINUVIN900 (molecular weight: 447.6, melting point: 137 to 141 ° C.) and TINUVIN928 (molecular weight: 441.6, melting point: 109 to 113 ° C.). Can be mentioned.

The content ratio of the component (E) may be appropriately set according to the purpose, and is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B), more preferably. Is 0.1 to 5 parts by mass. When the content ratio is 0.01 parts by mass or more, the light resistance of the cured film can be improved, and when it is 5 parts by mass or less, the strength of the cured film can be improved.

3-4. Component (F ) Component (F) is a hindered amine-based light stabilizer, and can be blended for the purpose of improving the light resistance of the cured film.

The molecular weight of (F) is preferably 300 to 3,000. When the molecular weight is 300 or more, it is difficult to volatilize in the melting and curing process of the composition for powder coating, and it can remain in the cured film. When the molecular weight is 5,000 or less, it has good compatibility with the molten coating and impairs the smoothness of the cured film. do not have.

As the melting point of (F), a compound having a melting point of 50 to 250 ° C. is preferable. When the melting point is 50 ° C. or higher, the smoothness of the coating film is improved, and when the melting point is 250 ° C. or lower, the coating film is easily melted in the melting and curing processes and can be uniformly present in the coating film.

As the component (F), a commercially available product may be used, and the commercially available products include Adecastab LA-52 (molecular weight: 847, melting point:> 65 ° C.) and Adecastab LA-57 (molecular weight: 791, melting point: melting point:) manufactured by ADEKA Co., Ltd. 125-135 ° C.), Adecastab LA-63P (Molecular Weight: 2,000, Melting Point: 85-105 ° C.), Adecasterb LA-68 (Molecular Weight: 1,900, Melting Point: 80-110 ° C.), BASF TINUVIN 144 (Molecular Weight: 1,900 ° C.) Molecular Weight: 685, Melting Point: 146-150 ° C.), TINUVIN152 (Molecular Weight: 756.6, Melting Point: 83-90 ° C.), Clarant's Sanduvor 3051powerer (Molecular Weight: 364.0, Melting Point: 225 ° C.) (Molecular weight: 1,500, melting point: 148 ° C.) and Clarant's "VP Sanduvor PR-31" (molecular weight: 529, melting point: 120-125 ° C.).

The content ratio of the component (F) may be appropriately set according to the purpose, and is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B), more preferably. Is 0.1 to 5 parts by mass. When the content ratio is 0.01 parts by mass or more, the light resistance of the cured film can be improved, and when it is 5 parts by mass or less, the strength of the cured film can be improved.

3-5. Component (G) The component (G) is a pigment and can be blended for various purposes.

Examples of the component (G) include coloring pigments, extender pigments, rust preventive pigments and bright pigments.

The coloring pigment is a pigment for coloring a coating film. Specific examples of the coloring pigment include carbon black, titanium oxide, iron oxide, red iron oxide, phthalocyanine blue, phthalocyanine green, quinacridone, isoindolenone, benzimidazolone, and dioxazine.

The extender pigment is a pigment for improving the hardness of the coating film and increasing the thickness of the coating film. Further, when the painted article is cut, it is preferable to mix it because the cut surface can be cleaned. Specific examples of the extender pigment include silica powder, mica, calcium carbonate, barium sulfate, barium carbonate, calcium carbonate, clay, diatomaceous earth, talc, basic magnesium carbonate, alumina and the like.

The rust-preventive pigment is a pigment for preventing corrosion and deterioration of the base material, which requires rust-preventive properties. Specific examples of the rust preventive pigment include condensed calcium phosphate, aluminum phosphate, condensed aluminum phosphate, zinc phosphate, aluminum phosphite, zinc phosphite, calcium phosphite, zinc molybdenate, calcium molybdenate and manganese molybdenum. Can be mentioned.

The bright pigment is a pigment for making the coating film shine. Specific examples of bright pigments include aluminum powder, nickel powder, stainless steel powder, copper powder, bronze powder, gold powder, silver powder, mica powder, graphite powder, glass flakes, scaly iron oxide powder, and shredded plastic pigments. Can be mentioned.

Each of these pigments can be contained alone, or two or more of these pigments can be used in combination.

The content ratio of the component (G) may be appropriately set according to the purpose, and is preferably 0 to 200 parts by mass, more preferably 0 with respect to 100 parts by mass of the total amount of the components (A) and (B). ~ 100 parts by mass.

4. Method for Producing Composition for Powder Coating The composition for powder coating of the present invention can be produced by a known method.

Specific examples thereof include the methods (1) to (3) described later.
(1) The components (A) and (B), and if necessary, the components (C) to (G), a leveling agent and a pinhole preventive agent (hereinafter collectively referred to as "raw materials") are powdered in advance. (2) Method of mixing the raw materials in a solid state and then crushing them into a powder (3) After mixing the raw materials in a solid state, melt-knead and cool to form a lump, which is in the form of powder. How to crush

The method (3) is preferable in that the homogeneity of the obtained cured film is excellent because each component is uniformly distributed in the obtained powder.

Mixing of raw materials in a solid state can be performed using a mixer such as a high-speed mixer, a V-type mixer, or an inversion mixer.

Melt kneading can be performed using various types of extruders such as uniaxial and biaxial and planetary gears. The mixture of each component is kneaded in a heated and melted state to make each component uniform. It is preferable to cool the extruded melt-kneaded product into pellets.

The pellets can be crushed using a crusher such as a pin mill, a hammer mill or a jet mill. After pulverization, it is preferable to use a cyclone and a classifier (vibration sieve, etc.) to align the particle size within a certain particle size range (hereinafter referred to as “classification”). When classifying, it is preferable to remove at least one of the particles having a diameter of less than 10 μm and the particles having a diameter of more than 100 μm.

5. Painted Article The coated article of the present invention has a cured film formed from a composition for powder coating on the surface of a base material.

Examples of the material of the base material include metal plates such as iron plates, steel plates and aluminum plates, and surface-treated ones thereof. The shape and size of the base material are not particularly limited.

In order to improve the adhesion between the base material and the cured film and to improve the corrosion resistance, a two-coat coating having a primer layer between the base material and the coating film may be used.
As the primer, various paints containing at least one selected from acrylic resin, polyester resin and epoxy resin as a main component can be appropriately used.
The film thickness of the primer layer is preferably 1 to 60 μm, more preferably 5 to 30 μm.

[Manufacturing method of painted articles]
In the coated article of the present invention, the composition for powder coating of the present invention is coated on a base material to form a coating film composed of a melt of the composition on the base material, and the reaction component in the composition is applied. It is preferable to carry out the reaction and then cool the melted coating film to room temperature to solidify it.

The melt film composed of the melt of the composition for powder coating material may be formed at the same time as the coating of the composition on the base material, and after the powder of the composition is adhered to the base material, the melt film is formed on the base material. The powder may be formed by heating and melting.

Since the curing reaction of the reaction components in the composition starts almost at the same time as the composition for powder coating is heated and melted, the composition is heated and melted and adhered to the substrate almost at the same time, or the composition is formed. It is necessary to heat-melt the composition after the substance adheres to the substrate.

The heating temperature (hereinafter, also referred to as “baking temperature”) and the heating maintenance time (hereinafter, also referred to as “baking time”) for heating and melting the composition for powder coating material and maintaining the molten state for a predetermined time are also referred to as “baking temperature”. ) Is appropriately set depending on the type and composition of the raw material components of the composition for powder coating material, the desired film thickness of the cured film, and the like. In particular, the baking temperature is preferably about 170 to 210 ° C. The baking time is preferably 1 to 120 minutes, more preferably 5 to 60 minutes.

[Painting method]
Examples of the coating method include an electrostatic coating method, an electrostatic spraying method, an electrostatic dipping method, a spraying method, a flow dipping method, a spraying method, a spraying method, a thermal spraying method, and a plasma spraying method. The electrostatic coating method using a powder coating gun is preferable because the surface smoothness of the molten film is excellent and the hiding property of the coating film is excellent.

Examples of the powder coating gun include a corona charging type coating gun and a triboelectric coating gun. The corona charge type coating gun sprays powder paint by corona discharge treatment. The triboelectric coating gun is a triboelectric coating gun that is subjected to triboelectric treatment and sprayed.

The discharge rate of the powder coating material from the powder coating gun is preferably 50 to 200 g / min.

The distance from the tip of the gun portion of the powder coating gun to the base material is preferably 100 to 400 mm from the viewpoint of coating efficiency.

When a corona charge type coating gun is used, the load voltage applied to the components constituting the powder coating by the corona discharge treatment is preferably -20 to -100 kV, and the coating efficiency (the rate at which the powder coating adheres to the substrate). From the viewpoint of excellent appearance of the coating film, -50 to -80 kV is preferable.
When a triboelectric coating gun is used, the internal current value of the powder coating by the triboelectric treatment is preferably 1 to 8 μA from the viewpoint of excellent coating efficiency and appearance of the coating film.

When the electrostatic coating method is industrially implemented, for example, a grounded conductive horizontal belt conveyor for installing an unpainted base material and grounding is laid in the painting room. Install a gun at the top of the painting room. The coating pattern width is preferably 50 to 500 mm, the gun operating speed is preferably 1 to 30 m / min, the conveyor speed is preferably 1 to 50 m / min, and suitable conditions may be selected from the above range according to the purpose.

6. Applications The coated articles formed from the powder coating composition of the present invention include the building / building materials field, the electric / communication field, the automobile / vehicle field, the road material field, the water / gas material field, the steel furniture field and the construction machine. -Can be used in various industrial product fields such as industrial machinery fields. In particular, examples of preferable applications include outdoor applications in the fields of construction / building materials and automobiles / vehicles.

Examples of applications in the field of construction and building materials include roofs, fences, gates, handrails, grids, residential steel frames, shutters, curtain walls, partitions, gutter metal fittings, and reinforced bars.

Examples of applications in the electrical and communication fields include backsheets for solar cells, backside paint for heat collectors for solar thermal power generation, blades for wind power generation, ranges, range hoods, air conditioners, refrigerators, washing machines, heaters, sewing machines, and freezer showcases. , Lighting equipment, switchboards, generators, motors and telephones.

Examples of applications in the field of automobiles and vehicles include bodies, wipers, bumpers, springs, wheels, brake drums, brake pads, oil filters, engine blocks, roof rails, drive shafts, truck bed parts, train interior poles, and the like.

Examples of applications in the field of road materials include guardrails, guard pipes, bridge railings, balustrades, sign poles, traffic lights, and the like.

Examples of applications in the field of water and gas materials include steel pipes, cast iron pipes, deformed pipes, nipples, sluice valves, joints, gas water heaters, faucet fittings, and the like.

Examples of applications in the field of steel furniture include desks, chairs, display shelves, bookshelves, lockers, commercial wagons and beds.

Examples of applications in the field of construction machinery and industrial machinery include power shovels, forklifts, FA equipment, machine tools, bombs, agricultural machinery, and the like.

Examples of applications in other fields include medical equipment, developing machines, precision equipment, IT equipment, office machines, fire extinguishers, gardening supplies, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

1. 1. Physical characteristics of the hydroxyl group-containing polyester resin In Table 1 below, the aliphatic polyhydric alcohol other than the (а) component, (b) component, and (b) component of the hydroxyl group-containing polyester resin used (hereinafter referred to as "(b') component"). ), Mw, Mw / Mn, hydroxyl value, acid value and melt viscosity.

◆ Molecular weight measurement method (GPC measurement conditions)
-Device: Waters Co., Ltd. GPC system name 1515 2414 717P RI
-Detector: RI detector-Column: Guard column Showa Denko Co., Ltd. Shodex KFG (8 μm 4.6 x 10 mm), 2 types of this column Waters Co., Ltd. stylel HR 4E THF (7.8 x 300 mm) + stylel HR 1 THF (7.8 x 300 mm)
-Column temperature: 40 ° C
-Eluent composition: THF (containing 0.03% sulfur as an internal standard), flow rate 0.75 mL / min

◆ Measurement method of hydroxyl value Add acetic anhydride as an acetylation reagent to a sample in a pyridine solvent and heat-treat it in a warm bath at 92 ° C for 1 hour. After allowing to cool, a small amount of water is added and heat-treated in a warm bath at 92 ° C. for 10 minutes. After allowing to cool, acetic acid was back-titrated with a potassium hydroxide ethanol solution using a phenolphthalein solution as an indicator to determine the hydroxyl value.

◆ Acid value measurement method The acid value was determined by titrating a sample with a potassium hydroxide ethanol solution using a phenolphthalein solution as an indicator in an acetone solvent.

◆ Method for measuring melt viscosity The viscosity at 200 ° C. was measured by the cone plate method.

The parentheses in Table 1 mean mol%.

2. 2. Examples 1 to 7, Comparative Examples 1 and 2
1) Preparation of composition for powder coating powder The compounds shown in Table 2 below are mixed by the mass parts shown in Table 2, then melt-kneaded, cooled to form a lump, and crushed into a powder to form a powder. A coating composition was prepared.
The obtained composition was used and evaluated later. The results are shown in Table 2.

The numbers in the components (A) to (G) in Table 2 mean parts by mass.
The abbreviations in Table 2 mean the following.
・ B1530: Isophorone diisocyanate ・ Adduct ・ ε-caprolactam ・ Block body, VESTAGON B1530 manufactured by Evonik Degussa Japan Co., Ltd.
CF970: Polypropylene wax (melting point 160 ° C), CERAFLOUR 970 manufactured by BYK
-AH3: High-density polyethylene wax (melting point 114 ° C.), Luwax AH3 manufactured by BASF.
KS1B: Di-normal butyltin malate polymer, KS-1B manufactured by Kyodo Yakuhin Co., Ltd.
TI460: 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3,5-triazine (molecular weight 629.8, melting point: 93-102 ° C.) ), BASF TINUVIN460
-LA63P: High molecular weight hindered amine-based light stabilizer (molecular weight about 2,000, melting point: 85 to 105 ° C.), ADEKA ADEKA STAB LA-63P manufactured by ADEKA Corporation
・ Heavy Calcium A: Heavy Calcium Carbonate, Maruo Calcium Co., Ltd. Heavy Calcium Carbonate A
・ 20L: Carbon Black, High Black 20L manufactured by Orion Engineered Carbons Co., Ltd.

2) Manufacture of painted articles On one surface of a cold-rolled steel sheet (hereinafter referred to as "steel sheet") that has been subjected to chemical conversion treatment with zinc phosphate using the composition for powder coating obtained in 2.1) above. , Electrostatic coating using an electrostatic coating machine (manufactured by Nippon Parkerizing Co., Ltd., trade name: GX7500C), held in an atmosphere of 200 ° C. for 15 minutes, then left to cool to room temperature, and average film thickness. A steel sheet with a hardened film (hereinafter referred to as “painted steel sheet”) having a hardness of 105 μm (minimum: 60 μm, maximum 150 μm) was obtained.

3) Evaluation of painted articles The coated steel plate obtained in 2.2) above was used for the evaluation described later.
(1) Weather resistance
340nm lamp Illuminance 0.55W / m ² , relative humidity 50% RH, black panel temperature 70 ° C, rainfall, irradiation 2 hours + dark 1 hour cycle, xenon weather meter (manufactured by ATLAS, trade name: Ci4000) ) Was used for the accelerated weather resistance test. The color difference ΔE of the cured film after the accelerated weather resistance test was measured using a spectrophotometer (manufactured by Konica Minolta Co., Ltd., trade name CM-5), and the amount of energy up to exceeding 3.0 was measured. Evaluation was performed at the following five levels. The results are shown in Table 2.
◎: 2,750 kJ / m ² or more 〇: 2,000 kJ / m ² or more, less than 2,750 kJ / m ² Δ: 1,500 kJ / m ² or more, less than 2,000 kJ / m ² ×: 1,000 kJ / m ² or more, less than 1,500 kJ / m ² XX: less than 1,000 kJ / m ²
(2) Anti-slip property
The dynamic friction coefficient of the coated steel plate was measured using a surface property measuring machine (manufactured by Shinto Kagaku Co., Ltd., trade name TYPE-14), and evaluated at the following four levels. The results are shown in Table 2.
◎: 0.15 or more 〇: 0.10 or more, less than 0.15 Δ: 0.05 or more, less than 0.10 ×: less than 0.05
(3) Matte
The 60 ° gloss of the coated steel plate was measured using a gloss meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., trade name VG2000), and evaluated at the following four levels. The results are shown in Table 2.
◎: Less than 30% 〇: 30% or more, less than 40% △: 40% or more, less than 50% ×: 50% or more
(4) Smoothness
The smoothness of the coated steel plate surface was visually observed and evaluated at the following four levels. The results are shown in Table 2.
◎: Very good 〇: Good △: Slightly bad ×: Very bad

4) Evaluation Results As is clear from the results of Examples 1 to 7, the composition for powder coating material of the present invention is excellent in all of the weather resistance, anti-slip property, matte property and smoothness of the cured film. It was a thing.
On the other hand, the compositions of Comparative Examples 1 and 2 are compositions containing a hydroxyl value-containing polyester resin composed of an aliphatic polyhydric alcohol other than the component (b), and are compared with the compositions of Examples. , The weather resistance of the cured film was very poor.

The present invention relates to a composition for powder coating and a coated article, and is related to a building / building material field, an electric / communication field, an automobile / vehicle field, a road material field, a water / gas material field, a steel furniture field, and a construction machine / industrial machine. It can be used in various fields of industrial products such as fields, and in particular, it can be preferably used for outdoor applications such as the fields of construction / building materials and automobiles / vehicles.

Claims (5)

A composition for powder coating material containing the following components (A), (B) and (C) as essential components.
(A) Component: Weight average molecular weight of 20,000 to 140,000, molecular weight distribution of 4.0 to 26, melt viscosity at 200 ° C. of 70 to 110 dPa · s, acid value of 10 mgKOH / g or less, and dicarboxylic acid. It contains a reaction product of an acid compound (а) component and an aliphatic polyhydric alcohol (b) component having no secondary hydroxyl group, the component (a) containing isophthalic acid, and the component (b) containing neopentyl glycol. , The hydroxyl group-containing polyester resin (B) component: the blocked isocyanate compound (C) component, wherein the content of neopentyl glycol is 30 to 60 mol% in the total amount of 100 mol% of the (а) component and the (b) component. :wax The composition for powder coating material according to claim 1 , wherein the β-position of the hydroxyl group of the component (b) is a quaternary carbon. The component (b) contains a trihydric or tetrahydric alcohol, and the content of the trivalent or tetrahydric alcohol is more than 0 mol% in 100 mol% of the total amount of the component (a) and the component (b), 10 mol. % Or less, the composition for powder coating according to claim 1 or 2 . The composition for powder coating material according to any one of claims 1 to 3 , wherein the component (C) contains polypropylene wax. A coated article having a cured film formed from the composition for powder coating according to any one of claims 1 to 4 on the surface thereof.