JP6878993B2 - Powder paint - Google Patents

Description

The present invention relates to a powder coating material containing particles containing a fluorine-containing polymer.

Powder coatings are attracting attention from the viewpoint of reducing environmental load, and are required to be used in various applications. Patent Document 1 describes particles of a fluorine-containing polymer containing a unit based on a fluoroolefin, a unit based on a cyclic monomer having an aliphatic ring or the like, and a unit based on a monomer having a hydroxyl group or a carboxy group. The powder coating containing is disclosed.

Japanese Unexamined Patent Publication No. 10-23139

However, the coating film obtained by using the conventional powder coating film cannot be said to have sufficient coating film strength. The present inventors have found that the coating film obtained by using the powder coating material described in Patent Document 1 has insufficient strength.

In view of the above problems, an object of the present invention is to provide a powder coating material capable of forming a coating film having excellent coating film strength, a method for producing a base material with a coating film, and a coated article.

As a result of diligent studies on the above problems, the present inventor has found that the desired effect can be obtained by using particles containing a fluorine-containing polymer containing a unit having a hydroxyl group or a carboxy group and having an average particle size within a predetermined range. The heading led to the present invention.
That is, the present inventor has found that the above problem can be solved by the following configuration.

[1] A powder coating material containing fine particles containing a fluorine-containing polymer.
The fluorine-containing polymer contains a unit based on a fluoroolefin and a unit having a hydroxyl group or a carboxy group.
A powder coating material having an average particle size of the fine particles of 1 to 20 μm.
[2] The powder coating material according to [1], wherein the fluorine-containing polymer has a melt viscosity at 200 ° C. of 5 to 200 Pa · s.
[3] The powder coating material according to [1] or [2], wherein the fluorine-containing polymer has a glass transition temperature of 35 to 150 ° C.
[4] The powder coating material according to any one of [1] to [3], wherein the fluorine-containing polymer has a number average molecular weight of 2000 to 30000.
[5] The powder coating material according to any one of [1] to [4], wherein the ratio of the mass average molecular weight to the number average molecular weight of the fluorine-containing polymer is 1.0 to 8.0.
[6] The fluorine-containing polymer contains a unit having the hydroxyl group, and contains the unit.
The powder coating material according to any one of [1] to [5], wherein the fluorine-containing polymer has a hydroxyl value of 1 to 150 mgKOH / g.
[7] The fluorine-containing polymer contains a unit having the carboxy group and contains the unit.
The powder coating material according to any one of [1] to [5], wherein the fluorine-containing polymer has an acid value of 1 to 150 mgKOH / g.
[8] The powder coating material according to any one of [1] to [7], wherein the average circularity of the fine particles is 0.90 or more.
[9] The powder coating material according to any one of [1] to [8], wherein the volume particle size distribution index value of the fine particles is 1.30 or less.
[10] The powder coating material according to any one of [1] to [9], further containing particles containing a fluorine-containing polymer, which has a larger average particle size than the fine particles.
[11] The powder coating material according to any one of [1] to [10], further comprising particles containing an epoxy resin or particles containing a polyester resin.
[12] The powder coating material according to [11], wherein the average particle size of the particles containing the epoxy resin or the average particle size of the particles containing the polyester resin is 1 to 20 μm, respectively.
[13] The powder coating material according to [11], wherein the average particle size of the particles containing the epoxy resin or the average particle size of the particles containing the polyester resin is larger than the average particle size of the fine particles.
[14] The powder coating material according to any one of [1] to [13] is applied onto a substrate to form a coating layer, and the coating layer is heat-treated to form a coating film on the substrate. A method for producing a base material with a coating film to be formed.
[15] A coated article having a base material and a coating film formed on the base material by the powder coating material according to any one of [1] to [13].

As shown below, according to the present invention, it is possible to provide a powder coating material capable of forming a coating film having excellent coating film strength, a method for producing a base material with a coating film, and a coated article.

The meanings of the terms in the present invention are as follows.
The numerical range represented by "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
The "unit" is a general term for an atomic group directly formed by polymerizing a monomer and an atomic group obtained by chemically converting a part of the atomic group. The "unit based on a monomer" is also simply referred to as a "unit" below. The content (mol%) of each unit with respect to all the units contained in the polymer can be determined from the amount of the components used in the production of the fluorine-containing polymer.
A "particle" is a crushed object that is solid at 25 ° C.
The "average particle size of particles" is the volume average from the particle size distribution measured using a known particle size distribution measuring device (manufactured by Symbolec, trade name "Hellos-Rodos", etc.) based on the laser diffraction method. It is a value calculated and obtained.
"Angle of repose of powder coating" is defined as "JIS R 9301-2-2 Alumina powder-Part 2: Physical property measurement method-2: Angle of repose" after vacuum-drying the powder coating at 80 ° C. for 16 hours or more. It is a value measured according to.
The "acid value" and "hydroxyl value" are values measured according to the method of JIS K 0070-3 (1992), respectively.
The "glass transition temperature" is the midpoint glass transition temperature of the polymer as measured by the differential scanning calorimetry (DSC) method. The "glass transition temperature" is also referred to as "Tg".
"Melting viscosity" is the value of the melt viscosity of a polymer at a predetermined temperature when the polymer is heated from 130 ° C. to 200 ° C. under a heating condition of 10 ° C./min using a rotary rheometer. is there.
The "number average molecular weight" and the "mass average molecular weight" are values measured by gel permeation chromatography using polystyrene as a standard substance. The "number average molecular weight" is also referred to as "Mn", and the "mass average molecular weight" is also referred to as "Mw".

The "volume particle size distribution index value" draws a cumulative distribution from the small diameter side with respect to the volume with respect to the particle size range obtained by dividing the particle size distribution of the particles, and the particle size to be cumulative 16% is the volume particle size D16v, cumulative. When the particle size of 84% is defined as the volume particle size D84v, it is a value calculated as ^{(D84v / D16v) 1/2.} The "volume particle size distribution index value" can be calculated based on the particle size distribution of particles measured using Coulter Multisizer II (manufactured by Beckman-Coulter). The "volume particle size distribution index value" is also referred to as "GSDv".

The "average circularity" is a value calculated from the circularity of 100 randomly selected particles by the following formula (however, in the following formula, Ci indicates circularity and fi indicates the frequency of particles). .. The circularity is the perimeter of a circle equal to the projected area of the particles with respect to the perimeter of the projected image of the particles when measured using the flow-type particle image analyzer "FPIA-3000 (manufactured by Sysmex)".

The powder coating material of the present invention is a powder coating material containing fine particles containing a fluorine-containing polymer, and the fluorine-containing polymer has a unit based on a fluoroolefin and a unit based on a monomer having a hydroxyl group or a carboxy group. The average particle size of the fine particles is 1 to 20 μm.
The coating film formed by heating the powder coating film of the present invention (hereinafter, also referred to as “the present coating film”) is excellent in coating film strength. This is presumed to be due to the following reasons.
Conventionally, in a powder coating material containing particles of a fluorine-containing polymer, the average particle size of the particles of the fluorine-containing polymer is large, so that the particle surface is easily heated when forming a coating film using the powder coating. , The inside of the particles is hard to be heated, and the melting of the particles becomes non-uniform. As a result, it is considered that the coating film becomes unevenly cured and the coating film strength is insufficient.
As a method for solving such a problem, miniaturization of particles of a fluorine-containing polymer can be mentioned. However, when the particles are miniaturized, the particles are partially aggregated or repelled by the charge on the surface of the particles, and it is difficult for the particles to be densely packed. As a result, it is considered that the coating film becomes unevenly cured and the strength of the coating film is insufficient.
The fluorine-containing polymer contained in the powder coating material of the present invention has a unit based on a monomer having a hydroxyl group or a carboxy group having a small particle size and high hydrophilicity. Therefore, it is presumed that the present coating film has excellent coating film strength because the action of suppressing the aggregation of the particles and the action of making the molten state of the particles uniform due to the atomization function synergistically.

The powder coating material of the present invention contains fine particles containing a fluorine-containing polymer (hereinafter, also referred to as “first particles”). The fluorine-containing polymer contained in the first particles contains a unit based on a fluoroolefin (hereinafter, also referred to as “unit F”).
Fluoroolefins are α-olefins in which one or more hydrogen atoms are substituted with fluorine atoms. In the fluoroolefin, one or more hydrogen atoms which are not substituted with fluorine atoms may be substituted with chlorine atoms.
Specific examples of fluoroolefins include tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene and vinylidene fluoride. As the fluoroolefin, one type may be used alone, or two or more types may be used in combination.
The content of the unit F is preferably 20 to 70 mol%, particularly preferably 40 to 60 mol%, based on the total units of the fluorine-containing polymer, from the viewpoint of weather resistance of the present coating film.

The fluorine-containing polymer contained in the first particles contains a unit (hereinafter, also referred to as “unit C”) based on a monomer having a hydroxyl group or a carboxy group (hereinafter, also referred to as “monomer C”). .. This reduces the charge on the particles and packs them tightly. Further, since the hydroxyl group or the carboxy group serves as a cross-linking point in the coating and the cross-linking of the fluorine-containing polymer proceeds, the coating film strength of the present coating film is improved. In addition, the interaction between the hydroxyl group or carboxy group and the surface of the substrate improves the adhesion of the coating film to the substrate.
The fluorine-containing polymer contained in the first particles is a unit based on a monomer having a hydroxyl group (hereinafter, also referred to as "unit C1") and a unit based on a monomer having a carboxy group (hereinafter, "unit C2"). It may also contain both of (also referred to as), or may include only one of them.
When the unit C1 is included, if an isocyanate-based curing agent is used as the curing agent, the coating film strength of the present coating film is further improved. When the unit C2 is contained, the strength of the coating film is further improved by using a carbodiimide-based curing agent, an amine-based curing agent, an oxazoline-based curing agent, or an epoxy-based curing agent. In particular, the curing agent used when the unit C2 is contained has an advantage that it does not require a high temperature (about 200 ° C.) as in the case of using an isocyanate-based curing agent.

Specific examples of the monomer having a hydroxyl group include CH ₂ = CHO-CH _2- cycloC ₆ H _10- CH ₂ OH, CH ₂ = CHCH ₂ O-CH _2- cycloC ₆ H _10- CH ₂ OH, CH ₂ = CHOCH ₂ CH ₂ OH, CH ₂ = CHCH ₂ OCH ₂ CH ₂ OH, CH ₂ = CHOCH ₂ CH ₂ CH ₂ CH ₂ OH, CH ₂ = CHCH ₂ OCH ₂ CH ₂ CH ₂ CH ₂ OH and CH ₂ = CHCH ₂ OH can be mentioned. As the monomer C1, one type may be used alone, or two or more types may be used in combination.

Specific examples of the monomer having a carboxy group are represented by CH ₂ = CHCOOH, CH (CH ₃ ) = CHCOOH, CH ₂ = C (CH ₃ ) COOH and the formula CH ₂ = CH (CH ₂ ) _n2 COOH. Compounds (where n2 represents an integer of 1 to 10) can be mentioned.
In the present specification, the hydroxyl group of the fluorine-containing polymer containing the unit C1 may be converted into a group having a carboxy group to obtain a fluorine-containing polymer containing the unit C2. Specifically, the fluorine-containing polymer containing the unit C1 was reacted with an acid anhydride (succinic anhydride, phthalic anhydride, etc.), and the hydroxyl group of the fluorine-containing polymer was converted into a group having a carboxy group. , Fluorine-containing polymer containing the unit C2.
As the monomer C2, one type may be used alone, or two or more types may be used in combination.
From the viewpoint of the coating film strength of the present coating film, the content of the unit C is preferably 3 to 20 mol%, preferably 5 to 15 mol%, based on all the units contained in the fluorine-containing polymer contained in the first particles. More preferred.

The fluorine-containing polymer contained in the first particles further contains an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group from the viewpoint of adjusting the physical properties of the coating film such as water resistance, chemical resistance, heat resistance and flexibility. It preferably contains a unit based on vinyl ether, vinyl ester or allyl ester (hereinafter, also referred to as “unit D”).
Specific examples of the vinyl ether, vinyl ester or allyl ester include ethyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, vinyl acetate, pivalic acid vinyl ester, and neononanoic acid vinyl ester (manufactured by HEXION, trade name "". Beova 9 ".), Neodecanoic acid vinyl ester (manufactured by HEXION, trade name" Beova 10 "), benzoic acid vinyl ester, tert-butyl (meth) acrylate, and benzyl (meth) acrylate.
The vinyl ether, vinyl ester or allyl ester may be used alone or in combination of two or more.
The content of the unit D is preferably 0 to 50 mol%, more preferably 25 to 40 mol%, based on all the units of the fluorine-containing polymer.

The melt viscosity of the fluorine-containing polymer contained in the first particles at 200 ° C. is preferably 5 to 200 Pa · s, more preferably 5 to 150 Pa · s from the viewpoint of surface smoothness of the present coating film, and 5 to 100 Pa · s. s is particularly preferable.
The Tg of the fluorine-containing polymer is preferably 35 to 150 ° C., more preferably 40 to 100 ° C., and even more preferably 50 to 60 ° C. from the viewpoint of blocking resistance of the powder coating material.
From the viewpoint of the flexibility of the present coating film, the Mn of the fluorine-containing polymer is preferably 2000 to 30000, more preferably 5000 to 20000, and particularly preferably 800 to 18000.
The ratio of Mw to Mn of the fluorine-containing polymer is preferably 1.0 to 8.0, more preferably 1.0 to 6.0, and 1.0 to 5. From the viewpoint of impact resistance of the present coating film. 0 is more preferable.
When the fluorinated polymer is a fluorinated polymer containing the unit C1, the hydroxyl value of the fluorinated polymer is preferably 1 to 150 mgKOH / g, more preferably 3 to 100 mgKOH / g, and 10 to 60 mgKOH / g. Especially preferable. Within this range, the flexibility, impact resistance and substrate adhesion of the present coating film due to the crosslink density of the fluorine-containing polymer are balanced with the thermal stability of the fluorine-containing polymer.
When the fluorinated polymer is a fluorinated polymer containing the unit C2, the acid value of the fluorinated polymer is preferably 1 to 150 mgKOH / g, more preferably 3 to 100 mgKOH / g, and 5 to 50 mgKOH / g. It is particularly preferable, and 10 to 20 mgKOH / g is most preferable. Within this range, the flexibility, impact resistance and substrate adhesion of the present coating film due to the crosslink density of the fluorine-containing polymer are balanced with the thermal stability of the fluorine-containing polymer.
The fluorinated polymer in the present invention may be a mixture of two or more kinds of fluorinated polymers, and specifically, contains a fluorinated polymer containing the unit C1 and not containing the unit C2 and the unit C2. It may be a mixture with a fluorine-containing polymer, and more specifically, a fluorine-containing polymer having a hydroxyl value of 3 to 100 mgKOH / g and an acid value of 0 mgKOH / g and an acid value of 5 to 50 mgKOH / g. It may be a mixture with a fluorine-containing polymer which is g. When a mixture of two or more kinds of fluorine-containing polymers is used, the acid value of the mixture is preferably 10 to 20 mgKOH / g.

The average particle size of the first particles in the present invention is 1 to 20 μm, preferably 3 to 20 μm, and more preferably 5 to 15 μm from the viewpoint of the coating film strength of the present coating film.
The average circularity of the first particles is preferably 0.90 or more, more preferably 0.92 to 0.99, and 0.95 to 0. From the viewpoint of the fluidity of the powder coating film and the smoothness of the present coating film. 99 is particularly preferable.
The GSDv of the first particle is preferably 1.30 or less, more preferably 1.10 to 1.30, and 1.15 to 1.30 from the viewpoint of charge stability of the powder coating film and smoothness of the present coating film. Is particularly preferable.
The first particles may be composed of only the fluorine-containing polymer of the present invention, and may further contain components that can be contained in the epoxy resin or polyester resin described later or the powder coating material described later. The first particles preferably contain the fluorinated polymer of the present invention as a main component, and preferably contain 25 to 100% by mass of the fluorinated polymer of the present invention.

The first particles are obtained by atomizing the fluorine-containing polymer into fine particles by a kneading and pulverizing method, a spray-drying method, a precipitation method and the like. When the first particles contain an epoxy resin or a polyester resin described later, these resins may be used together with the fluorine-containing polymer. Similarly, components that can be contained in the powder coating material (additives such as an organic ultraviolet absorber, an organic light stabilizer, a curing agent, and a curing catalyst) may be used together with the fluorine-containing polymer.
Here, the kneading and pulverizing method is a method of pulverizing and classifying a fluorine-containing polymer that has been kneaded and dried to obtain first particles. The spray-drying method is a method of obtaining first particles by spraying and drying a solution containing a fluorine-containing polymer. The precipitation method is a method of obtaining first particles by crystallizing the fluorine-containing polymer from a solution containing a solvent and a fluorine-containing polymer, in which the fluorine-containing polymer is dissolved in the solvent or dispersed in the form of particles. Is.

The powder coating material of the present invention may further contain particles containing a fluorine-containing polymer (hereinafter, also referred to as “second particles”) having an average particle size larger than that of the first particles. As a result, when the particles are packed on the base material, the first particles having a small particle size enter the gaps between the second particles having a large particle size, so that the voids between the particles can be reduced and the coating film adheres to the base material. The properties and coating film strength are improved.
The fluorinated polymer contained in the second particle may be the same fluorinated polymer as the fluorinated polymer contained in the first particle, and has a fluorinated weight other than the fluorinated polymer contained in the first particle. It may be coalesced. Since the physical characteristics of the fluorine-containing polymer contained in the second particles are the same as those of the fluorine-containing polymer contained in the first particles described above, the description thereof will be omitted.
The second particles may be composed of only a fluorine-containing polymer, and may further contain components that can be contained in an epoxy resin or polyester resin described later or a powder coating material described later. The second particles preferably contain a fluorine-containing polymer as a main component, and preferably contain 25 to 100% by mass of the fluorine-containing polymer in the present invention.
The average particle size of the second particle is not particularly limited as long as it is larger than the average particle size of the first particle, and is usually more than 20 μm and 100 μm or less, preferably 25 to 90 μm, and more preferably 25 to 80 μm.
When the powder coating material of the present invention contains the second particles, the mass ratio of the second particles to the first particles in the powder coating material of the present invention is preferably 4.0 or less, more preferably 3.0 or less, and 2 5.5 or less is more preferable.

The powder coating material of the present invention may contain an epoxy resin from the viewpoint of the flexibility of the coating film.
The epoxy resin in the present invention may be contained in the first particles. In this case, the first particles are particles containing the above-mentioned fluorine-containing polymer and epoxy resin. When the first particles contain the fluorine-containing polymer and the epoxy resin, the first particles are produced by adding the epoxy resin together with the fluorine-containing polymer in the particle formation step as described above.
On the other hand, the epoxy resin in the present invention may be contained as particles mainly containing the epoxy resin (hereinafter, also referred to as “particle E”) in the powder coating material. In this case, the particle E is a particle different from the first particle and the second particle. The particles E preferably contain 25 to 100% by mass of the epoxy resin.
The average particle size of the particles E is preferably 1 to 20 μm, more preferably 3 to 20 μm, and even more preferably 5 to 15 μm. As a result, the particle diameters of the particles E and the first particles become close to each other, the particles are more likely to be packed more densely, and the coating film strength of the present coating film is further improved.
Another aspect of the average particle size of the particle E is an aspect larger than the average particle size of the first particle. As a result, the first particles having a small particle size enter the gaps between the particles E having a large particle size, and the voids between the particles become smaller, so that the adhesion of the coating film to the substrate is improved. In this case, the average particle size of the particles E is preferably more than 20 μm and 100 μm or less, more preferably 25 to 50 μm.

Specific examples of the epoxy resin include "Epicoat (registered trademark) 1001", "Epicoat (registered trademark) 1002", "Epicort (registered trademark) 4004P" manufactured by Mitsubishi Chemical Corporation, and "Epiclon (registered trademark)" manufactured by DIC. 1050 "," Epicron (registered trademark) 3050 "," Epototo (registered trademark) YD-012 "," Epototo (registered trademark) YD-014 "," Epototo (registered trademark) YDCN704 ", Nagase manufactured by Nippon Steel & Sumitomo Metal Corporation. Examples include "Denacol (registered trademark) EX-711" manufactured by Chemtex and "EHPE3150" manufactured by Daicel.

The powder coating material of the present invention may contain a polyester resin from the viewpoint of the flexibility of the present coating film.
The polyester resin in the present invention may be contained in the first particles. In this case, the first particles are particles containing the above-mentioned fluorine-containing polymer and polyester resin. When the first particles contain the fluorine-containing polymer and the polyester resin, the first particles are produced by adding the polyester resin together with the fluorine-containing polymer in the particle formation step as described above.
On the other hand, the polyester resin in the present invention may be contained as particles mainly containing the polyester resin (hereinafter, also referred to as "particles P") in the powder coating material. In this case, the particle P is a particle different from the first particle and the second particle. The particles P preferably contain 25 to 100% by mass of the polyester resin.
The average particle size of the particles P is preferably 1 to 20 μm, more preferably 3 to 20 μm, and even more preferably 5 to 15 μm. As a result, the particle diameters of the particles P and the first particles become close to each other, the particles are more likely to be packed more densely, and the coating film strength of the present coating film is further improved.
Another aspect of the average particle size of the particles P is an aspect larger than the average particle size of the first particle. As a result, the first particles having a small particle size enter the gaps between the particles P having a large particle size, and the voids between the particles become smaller, so that the adhesion of the coating film to the substrate is improved. In this case, the average particle size of the particles P is preferably more than 20 μm and 100 μm or less, more preferably 25 to 50 μm.

Specific examples of the polyester resin include "CRYLCOAT (registered trademark) 4642-3", "CRYLCOAT (registered trademark) 4890-0", "CRYLCOAT (registered trademark) 4842-3" manufactured by Daicel Ornex, and Japan U-Pica Company. "Yupica Coat (registered trademark) GV-250", "Yupica Coat (registered trademark) GV-740", "Yupica Coat (registered trademark) GV-175", "Yupica Coat (registered trademark) GV-110", manufactured by DSM "Uralac® 1680" can be mentioned.

The powder coating material of the present invention may contain both an epoxy resin and a polyester resin. In this case, both the particles containing the epoxy resin and the particles containing the polyester resin may be contained, or the particles containing both the resins of the epoxy resin and the polyester resin may be contained. Both the epoxy resin and the polyester resin may be contained in the first particles.

When the powder coating material of the present invention contains an epoxy resin or a polyester resin, a layer mainly composed of an epoxy resin or a polyester resin and a layer mainly composed of a fluorine-containing polymer are laminated in this order on a base material. From the viewpoint that a coating film can be easily obtained, the difference between the SP value of the fluoropolymer and the SP value of the epoxy resin or polyester resin is preferably ^{0.4 to 16 (J / cm 3} ) ^{1/2 in absolute value.} .. When both the epoxy resin and the polyester resin are contained, it is preferable that the SP value of both resins and the SP value of the fluorine-containing polymer have the above relationship.
When the powder coating material of the present invention contains an epoxy resin or a polyester resin, the fluorine-containing polymer in the powder coating material of the present invention (when the powder coating material of the present invention contains the first particles and the second particles, the fluorine-containing polymer contained in these particles). The mass ratio of the epoxy resin or the polyester resin (the total amount of both resins when they are contained) is preferably 0.3 to 3.5, more preferably 0.35 to 3.

From the viewpoint of the light resistance of the present coating film, the powder coating material of the present invention preferably further contains an organic ultraviolet absorber.
Examples of the organic ultraviolet absorber include salicylic acid ester-based, benzotriazole-based, benzophenone-based, and cyanoacrylate-based compounds.
Specific examples of the organic ultraviolet absorber include "Tinuvin 326" (molecular weight: 315.8, melting point: 139 ° C.), "Tinuvin 405" (molecular weight: 583.8, melting point: 74 to 77 ° C.), manufactured by BASF. "Tinuvin 460" (molecular weight: 629.8, melting point: 93-102 ° C), "Tinuvin 900" (molecular weight: 447.6, melting point: 137-141 ° C), "Tinuvin 928" (molecular weight: 441.6, melting point) : 109-113 ° C), Clarant's "Sanduvor VSU power" (molecular weight: 312.0, melting point: 123-127 ° C), Clarant's "Hastavin PR-25 Gran" (molecular weight: 250.0, melting point: 55) ~ 59 ° C.).
As the organic ultraviolet absorber, one type may be used alone, or two or more types may be used in combination.
When the powder coating material of the present invention contains an organic ultraviolet absorber, the content of the organic ultraviolet absorber is preferably 0.01 to 15% by mass, preferably 0.1 to 15% by mass, based on the total mass of the powder coating material. 3% by mass is more preferable.

The powder coating material of the present invention preferably contains an organic light stabilizer from the viewpoint of protecting the coating film from ultraviolet rays.
As the organic light stabilizer, a hindered amine compound is preferable. Specific examples of the hindered amine compound include "Tinuvin 111FDL" (molecular weight: 2,000 to 4,000, melting point: 63 ° C.), "Tinuvin 144" (molecular weight: 685, melting point: 146 to 150 ° C.), ""Tinuvin152" (Molecular Weight: 756.6, Melting Point: 83-90 ° C), "Sanduvor 3051 powerer" (Molecular Weight: 364.0, Melting Point: 225 ° C) manufactured by Clarant, "Sanduvor 3070 powerer" (Molecular Weight: 3070 ° C) manufactured by Clariant. 1,500, melting point: 148 ° C.), Clariant's "VP Sanduvor PR-31" (molecular weight: 529, melting point: 120-125 ° C.).
As the organic light stabilizer, one type may be used alone, or two or more types may be used in combination.
When the powder coating material of the present invention contains an organic light stabilizer, the content of the organic light stabilizer is preferably 0.01 to 15% by mass, preferably 0.1 to 15% by mass, based on the total mass of the powder coating material. 3% by mass is more preferable.

The powder coating material of the present invention preferably contains a curing agent. The curing agent is a compound having two or more groups capable of reacting with a hydroxyl group or a carboxy group, and is a compound that crosslinks a fluorine-containing polymer. A curing agent is a compound usually having 2 to 30 of the reactive groups.
When the fluorine-containing polymer contains the unit C1, the curing agent is preferably a compound having an isocyanate group or a compound having two or more blocked isocyanate groups.
When the fluorine-containing polymer contains the unit C2, the curing agent is preferably a compound having two or more epoxy groups, carbodiimide groups, oxazoline groups, or β-hydroxyalkylamide groups.

Specific examples of compounds having two or more isocyanate groups include alicyclic polyisocyanates such as isophorone diisocyanate and dicyclohexylmethane diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and these. Examples include denatured compounds.

Specific examples of compounds having two or more blocked isocyanate groups include diisocyanate (trilened isocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4'. -A compound obtained by reacting methylenebis (cyclohexylisocyanate), methylcyclohexanediisocyanate, bis (isocyanatemethyl) cyclohexaneisophorone diisocyanate, dimerate diisocyanate, lysine diisocyanate, etc.) with a blocking agent. Can be mentioned.
Specific examples of the blocking agent include alcohol, phenol, active methylene, amine, imine, acid amide, lactam, oxime, pyrazole, imidazole, imidazoline, pyrimidine and guanidine.

Specific examples of the compound having two or more epoxy groups include triglycidyl isocyanurate (hereinafter referred to as "TGIC"), "TM239" (manufactured by Nissan Chemical Industries, Ltd.) in which a methylene group is introduced into the glycidyl group portion of TGIC. Examples thereof include "TEPIC-SP" (manufactured by Nissan Chemical Industries, Ltd.) which is an epoxy compound having a triazine skeleton, and "PT-910" (manufactured by HUNTSMAN) which is a mixture of glycidyl ester of trimellitic acid and glycidyl ester of terephthalate.

Specific examples of compounds having two or more carbodiimide groups include dicarbodiimide and polycarbodiimide (poly (1,6-hexamethylenecarbodiimide), poly (4,4'-methylenebiscyclohexylcarbodiimide), poly (1,3-cyclohexyl). Silencarbodiimide), poly (1,4-cyclohexylenecarbodiimide), poly (4,4'-dicyclohexylmethanecarbodiimide), poly (4,4'-diphenylmethanecarbodiimide), poly (3,3'-dimethyl-4,4) '-Diphenylmethane carbodiimide), poly (naphthalene carbodiimide), poly (p-phenylene carbodiimide), poly (m-phenylene carbodiimide), poly (trilcarbodiimide), poly (diisopropylcarbodiimide), poly (methyl-diisopropylphenylenecarbodiimide), poly (1,3,5-triisopropylbenzene) polycarbodiimide, poly (1,3,5-triisopropylbenzene) polycarbodiimide, poly (1,5-diisopropylbenzene) polycarbodiimide, poly (triethylphenylenecarbodiimide), poly ( Triisopropylphenylene carbodiimide) and the like).

Specific examples of the compound having two or more oxazoline groups include Epocross WS-500, WS-700, K-2010, K-2020, and K-2030 manufactured by Nippon Shokubai Co., Ltd. (all of which are trade names).
Specific examples of the compound having two or more β-hydroxyalkylamide groups include PrimidXL-552 (manufactured by EMS).
When the powder coating material of the present invention contains a curing agent, the content of the curing agent is preferably 1 to 50% by mass, preferably 1 to 20% by mass, based on the total mass of the fluoropolymer in the powder coating material. More preferred.

The powder coating material of the present invention may contain a curing catalyst. The curing catalyst is a compound that promotes a curing reaction when a curing agent is used, and can be selected from known curing catalysts according to the type of curing agent.

The powder coating material of the present invention contains components other than the above, for example, an inorganic ultraviolet absorber, a matting agent, a leveling agent, a surface conditioner, a degassing agent, a plasticizer, a filler, a heat stabilizer, and an increase, if necessary. It may contain a thickener, a dispersant, a surfactant, an antistatic agent, a rust preventive, a silane coupling agent, an antifouling agent, a decontamination treatment agent and the like.

The powder coating material of the present invention may contain the first particles and may contain other components. For example, the powder coating material of the present invention contains the first particle and other components (second particle, particle E, particle P, organic ultraviolet absorber, organic light stabilizer, curing agent, curing catalyst, etc.). May be dry-blended and manufactured.

The base material with a coating film of the present invention has a coating film (the present coating film) formed by the powder coating material of the present invention.
Specific examples of the material of the base material include inorganic substances, organic substances, and organic-inorganic composite materials.
Specific examples of inorganic substances include concrete, natural stone, glass, and metals (iron, stainless steel, aluminum, copper, brass, titanium, alloys thereof, etc.).
Specific examples of organic substances include plastics, rubbers, adhesives, and wood.
Specific examples of the organic-inorganic composite material include fiber reinforced plastic, resin reinforced concrete, and fiber reinforced concrete.
The base material is preferably metal, more preferably aluminum or an aluminum alloy. The aluminum base material has excellent corrosion resistance, is lightweight, and is suitable for use as a building material such as an exterior member.
The base material may be a base material that has undergone surface treatment such as chemical conversion treatment.
When a base material made of aluminum or an aluminum alloy is used as the base material, the base material is preferably surface-treated with a chemical conversion treatment agent. In other words, the base material is preferably a base material made of aluminum or an aluminum alloy having a chemical conversion coating film on its surface.
As the type of chemical conversion treatment agent, a chromium-free chemical conversion treatment agent is preferable, and a zirconium-based chemical conversion treatment agent or a titanium-based chemical conversion treatment agent is more preferable.

The shape, size, etc. of the base material are not particularly limited.
Specific examples of the base material include composite panels, curtain wall panels, curtain wall frames, window frames and other building exterior members, tire wheels, automobile members, construction machinery, motorcycles and other transportation equipment members. Can be mentioned.

The thickness of the present coating film is preferably 20 to 1000 μm, more preferably 20 to 500 μm. In particular, 20 to 90 μm is preferable for applications such as members for high-rise buildings such as aluminum curtain walls. For applications with high weather resistance requirements such as outdoor units of air conditioners installed along the coast, poles of traffic lights, signs, etc., 100 to 200 μm is preferable.

In the method for producing a base material with a coating film of the present invention, the powder coating material of the present invention is applied onto the base material to form a coating layer, and the coating layer is heat-treated to form the present coating film on the base material. It is preferable to manufacture the product.
The coating layer can be formed by a coating method such as electrostatic coating method, electrostatic spraying method, electrostatic immersion method, spraying method, smoke atomization method, flow immersion method, spraying method, spraying method, thermal spraying method, and plasma spraying method. , The method of coating the powder coating material of the present invention on a substrate is preferable. From the viewpoint of surface smoothness and hiding property of the present coating film, an electrostatic coating method or a fumes method using a powder coating gun is preferable.
Specific examples of the powder coating gun include a corona charging type coating gun and a triboelectric coating gun. The corona charging type coating gun is a coating gun that sprays powder paint by corona discharge treatment. The triboelectric coating gun is a coating gun in which powder coating is subjected to triboelectric treatment and sprayed.

When the coating layer is heat-treated, it is preferable to heat the coating layer on the substrate to form a molten film made of a melt of the powder coating material on the substrate. The molten film may be formed at the same time as the coating layer is formed on the base material, or may be formed separately after the coating layer is formed.
The heating temperature and the heating maintenance time for heating and melting the powder coating material and maintaining the molten state for a predetermined time are appropriately set depending on the composition of the powder coating material, the film thickness of the coating film, and the like.
The heating temperature is usually 120 ° C. to 300 ° C., more preferably 140 ° C. to 250 ° C. The heating maintenance time is usually 2 to 60 minutes.
The molten film formed on the base material is preferably cooled to 20 to 25 ° C. to form the present coating film. Cooling may be rapid cooling or slow cooling, and slow cooling is preferable from the viewpoint of substrate adhesion of the present coating film.

As one of the preferred embodiments of the method for producing a coated article of the present invention, a powder coating material A containing particles containing a curable resin containing no fluorine atom and a curing agent is coated on the surface of a base material to form a coating layer A. Then, the powder coating B containing the first particles and the curing agent is applied to the surface of the coating layer A to form the coating layer B, and then the coating layer A and the coating layer B are simultaneously applied. Examples thereof include a method for producing a coated article (hereinafter, also referred to as “2-coat 1-bake method”) in which the main coating film is formed on the surface of the base material by curing.

In the two-coat one-baking method, examples of the curable resin containing no fluorine atom in the powder coating material A include the above-mentioned epoxy resin and polyester resin. Further, the powder coating material A may contain a component that can be contained in the powder coating material of the present invention described above, and preferably contains a pigment. The curing agent contained in the powder coating material A may be contained in the particles containing the resin containing no fluorine atom.
The powder coating material B in the two-coat, one-baking method may contain components that can be contained in the powder coating material of the present invention described above, except that the curing agent is essentially contained, but it is preferable that the powder coating material B does not contain a pigment. As described above, if the powder coating material A contains the pigment and the powder coating material B does not contain the pigment, the pigment is less likely to be exposed on the surface of the main coating film, and as a result, the weather resistance of the main coating film is improved. This effect is remarkably exhibited at the edge of the base material.
The powder coating material B preferably contains the above-mentioned organic ultraviolet absorber from the viewpoint of further improving the light resistance of the present coating film. The curing agent contained in the powder coating material B may be contained in the first particles.

In the two-coat one-baking method, the melt viscosity of the fluorine-containing polymer contained in the powder coating material B at 200 ° C. contains the fluorine atoms contained in the powder coating material A from the viewpoint of better weather resistance of the present coating film. It is preferably higher than the melt viscosity of the non-resin at 200 ° C.
The absolute value of the difference between the angle of repose of the powder coating material A and the angle of repose of the powder coating material B is preferably 20 degrees or less from the viewpoint of more excellent weather resistance of the present coating film.

Further, in the two-coat one-baking method, the heating temperature when the coating layer A and the coating layer B are simultaneously cured is preferably 200 ° C. or lower.

As one of the preferred embodiments of the method for producing a coated article of the present invention, a powder coating material containing first particles and a curing agent is formed after forming a film by anodizing on the surface of a base material made of aluminum or an aluminum alloy. Examples thereof include a method for manufacturing a coated article (hereinafter, also referred to as "secondary electrolytic coloring method") in which coating is performed to form a coating layer, and the coating layer is cured to form a present coating film on the surface of the base material. Be done.
Here, the film formed by the anodizing treatment is a porous film in which innumerable pores are formed. Therefore, in the case of a powder coating material containing first particles having a fine average particle size, the powder coating material uniformly penetrates into the pores of the porous coating film, and the adhesion of the coating layer to the substrate is further improved.

The anodizing treatment is carried out by connecting the base material to the anode and applying an electric current in an electrolytic solution containing an inorganic acid such as sulfuric acid or phosphoric acid or an organic acid such as oxalic acid.
Prior to the anodizing treatment, the surface of the substrate may be degreased or etched. The natural oxide film on the surface of the base material can be removed by the etching process.

In the secondary electrolytic coloring method, the film formed by the anodic acid treatment may be subjected to the electrolytic coloring treatment after the anodic oxide film treatment and before the coating of the powder coating material. Further, after the electrolytic coloring treatment and before the coating of the powder coating material, a temporary sealing treatment may be performed.
As the coating method of the powder coating material, various methods are used as described above, but the electrostatic coating method is preferable. In the secondary electrolytic coloring method, the heating temperature when curing the coating layer is preferably 200 ° C. or lower.
The powder coating material may contain components that can be contained in the powder coating material of the present invention described above, except that the powder coating material contains a curing agent indispensably. The curing agent may be contained in the first particles.

The coated article of the present invention has the coated substrate of the present invention. Therefore, since the coated article of the present invention has a coating film having excellent coating film strength, it can be suitably used for applications requiring processability and high durability.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples. The blending amount of each component in the table described later indicates a mass standard.

[Ingredients used in the production of powder paint]
(Fluorine-containing polymer)
Unit F: Chlorotrifluoroethylene (CTFE)
Unit C: 4-Hydroxybutyl vinyl ether (HBVE)
Unit D: Cyclohexyl vinyl ether (CHVE), ethyl vinyl ether (EVE)
(Polymer other than fluorine-containing polymer)
Epoxy resin: Epototo (trade name) YDCN704 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.
Polyester resin: Made by Japan U-Pica Company, GV-110

(Additive)
Hardener 1: A compound having two or more blocked isocyanate groups (Evonik, Bestagon (registered trademark) B1530)
Hardener 2: A compound having two or more epoxy groups (manufactured by HUNTSMAN, PT-910 (trade name))
Surface conditioner: BYK-360P (trade name) manufactured by Big Chemie
Degassing agent: Benzoin Pigment: Titanium oxide pigment (DuPont, Ti-Pure R960 (trade name), titanium oxide content: 89% by mass)
Curing catalyst: xylene solution of dibutyltin dilaurate (100-fold diluted product)

[Production example of fluorine-containing polymer]
[Example 1]
CTFE (387 g), CHVE (326 g), HBVE (84.9 g), potassium carbonate (12.3 g), xylene (503 g) and ethanol (142 g) were introduced into the autoclave, the temperature was raised, and the temperature was maintained at 65 ° C. .. Subsequently, a 50% by mass xylene solution (20 mL) of tert-butylperoxypivalate was added to the autoclave and polymerized for 11 hours. Subsequently, the solution in the autoclave was filtered, and the obtained filtrate was degassed to obtain a solution containing a fluorine-containing polymer. The solution was vacuum-dried at 65 ° C. for 24 hours, and further vacuum-dried at 130 ° C. for 20 minutes, and the obtained block-shaped fluorine-containing polymer was pulverized to obtain a powdery fluorine-containing polymer 1. ..
The fluorine-containing polymer 1 was a polymer containing 50 mol%, 39 mol%, and 11 mol% of units based on CTFE, CHVE, and HBVE in this order. Table 1 shows the detailed physical properties of the fluorine-containing polymer 1.

[Example 2]
Succinic anhydride (9.8 g) and triethylamine (0.70 g) as a catalyst are added to a varnish (220 g) obtained by dissolving the powdered fluorine-containing polymer 1 of Example 1 in methyl ethyl ketone, and the reaction is carried out at 75 ° C. for 5 hours. Then, a solution containing the fluorine-containing polymer 3 was obtained. The solution was vacuum-dried at 65 ° C. for 24 hours, and further vacuum-dried at 130 ° C. for 20 minutes, and the obtained block-shaped fluorine-containing polymer was pulverized to obtain a powdery fluorine-containing polymer 2. ..
The fluorine-containing polymer 2 is a unit formed by adding succinic anhydride to a hydroxyl group of a CTFE-based unit, a CHVE-based unit, an HBVE-based unit, and an HBVE-based unit (-O (CH _{2) on the side chain.} ) ₄ A unit having OC (O) CH ₂ CH ₂ COOH; hereinafter also referred to as “HBVE-SA”), which is a polymer containing 50 mol%, 39 mol%, 4 mol% and 7 mol% in this order. It was. Table 1 shows the detailed physical properties of the fluorine-containing polymer 2.

[Example 3]
The powdery fluorine-containing polymer 3 is the same as in Example 1 except that the monomer used is changed to CTFE (387 g), CHVE (327 g), EVE (47.9 g), and HBVE (7.7 g). Got
The fluorine-containing polymer 3 is a polymer containing 50 mol%, 39 mol%, 10 mol% and 1 mol% of CTFE-based units, CHVE-based units, EVE-based units and HBVE-based units in this order. It was. Table 1 shows the detailed physical properties of the fluorine-containing polymer 3.

[Production example of powder coating]
[Examples 4 to 7]
Average particles by spray-drying using a solution obtained by mixing the components contained in the particles, tridecylphosphite (0.12 g), and methyl ethyl ketone (67 g) shown in Table 2 until uniform. Powder coatings 1 to 4 composed of particles 1 to 4 having a diameter of 15 μm were obtained, respectively.
The acid value and the hydroxyl value of the particles 2 are values measured again with respect to the mixture obtained by mixing the fluorine-containing polymer 1 and the fluorine-containing polymer 2.
[Examples 8 to 10]
The components contained in the particles shown in Table 2 are mixed by a high-speed mixer (manufactured by Yuzaki Co., Ltd.), and a barrel is set at 120 ° C. using a twin-screw extruder (manufactured by Thermoprism, 16 mm extruder). Melting and kneading at temperature gave pellets. The pellets are pulverized at 25 ° C. using a pulverizer (manufactured by FRITSCH, product name: rotor speed mill P14), and further classified using a 150 mesh net to obtain particles 5 to 7 having an average particle diameter of 40 μm. I got each.
Table 2 shows the detailed physical properties of the particles 1 to 7 obtained in Examples 4 to 10.

[Example 10]
30 parts by mass of the particles 1 (powder coating material 1) and 70 parts by mass of the particles 4 were mixed with a high-speed mixer to obtain a powder coating material 5. Powder coatings 6 and 7, respectively, were obtained in the same manner, except that the type of particles was changed. The particle composition (mass%) of the obtained powder coating material is summarized in Table 3.

[Example of using powder paint]
[Examples 11 to 22]
The powder coating material 1 is electrostatically coated on one surface of a chromate-treated aluminum plate (base material) using an electrostatic coating machine (GX3600C manufactured by Onoda Cement Co., Ltd.) and held at 200 ° C. for 20 minutes. , An aluminum plate 1 with a coating film having a thickness of 55 to 65 μm formed from a powder coating material was obtained. The obtained aluminum plate with a coating film was used as a test piece 1 for evaluation described later.
Aluminum plates 2 to 6 with a coating film and test pieces 2 to 7 were obtained in the same manner except that the powder coating material 1 was changed to the powder coating materials 2 to 7, respectively.
Further, the aluminum plates 8 to 12 with a coating film and the test pieces 8 to 8 to 12 were used in the same manner except that the powder coating materials 1 were changed to the respective particles shown in Table 3 and the powder coating materials 8 to 12 were used. I got twelve. The obtained test pieces 2 to 12 were subjected to the evaluation described later. The evaluation results are summarized in Table 3.

[Evaluation method of coating film]
(Coating film strength 1)
Using a DuPont type impact tester, a weight was dropped on the coating film side of the test pieces 1 to 12, and the presence or absence of cracks or cracks at the drop point was observed.
◯: No cracks or cracks occur even when dropped from a height of 40 cm or more.
Δ: No cracks or cracks occur if the product is dropped from a height of 20 cm or more and less than 40 cm.
X: Cracks and cracks occur even if dropped from a height of less than 20 cm.
(Coating film strength 2)
Using a DuPont type impact tester, a weight was dropped on the substrate side of the test pieces 1 to 12, and the presence or absence of cracks or cracks at the drop point was observed.
◯: No cracks or cracks occur even when dropped from a height of 30 cm or more.
Δ: No cracks or cracks occur if the product is dropped from a height of 10 cm or more and less than 30 cm.
X: Cracks and cracks occur even if dropped from a height of less than 10 cm.
The evaluation results are shown in Table 3.

As shown in Table 3, a coating film formed from a powder coating material containing fine particles of a fluorine-containing polymer based on a monomer having a hydroxyl group or a carboxy group and having an average particle size in a predetermined range has a coating strength. Excellent.

Claims (15)

The first particle containing the fluorine-containing polymer and
A powder coating material having a larger average particle size than the first particles and containing second particles containing a fluorine-containing polymer different from the fluorine-containing polymer contained in the first particles.
The fluorine-containing polymer contained in the first particles contains a unit based on a fluoroolefin and a unit having a hydroxyl group or a carboxy group.
The mass ratio of the second particle to the first particle is 4.0 or less, and the mass ratio is 4.0 or less.
A powder coating material having an average particle size of the first particles of 1 to 20 μm. The first particle containing the fluorine-containing polymer and
A powder coating material having a larger average particle size than the first particles and containing second particles containing the same fluorine-containing polymer as the fluorine-containing polymer contained in the first particles.
The fluorine-containing polymer contained in the first particles contains a unit based on a fluoroolefin and a unit having a hydroxyl group or a carboxy group.
The mass ratio of the second particle to the first particle is 4.0 or less, and the mass ratio is 4.0 or less.
The average particle size of the first particle is 1 to 20 μm.
A powder coating material in which the first particles and the second particles are mixed and used. The first particle containing the fluorine-containing polymer and
A powder coating material containing particles containing an epoxy resin or particles containing a polyester resin.
The fluorine-containing polymer contained in the first particles contains a unit based on a fluoroolefin and a unit having a hydroxyl group or a carboxy group.
A powder coating material having an average particle size of the first particles of 1 to 20 μm. The powder coating material according to any one of claims 1 to 3, wherein the fluorine-containing polymer contained in the first particles has a melt viscosity at 200 ° C. of 5 to 200 Pa · s. The powder coating material according to any one of claims 1 to 4, wherein the glass transition temperature of the fluorine-containing polymer contained in the first particles is 35 to 150 ° C. The powder coating material according to any one of claims 1 to 5 , wherein the number average molecular weight of the fluorine-containing polymer contained in the first particles is 2000 to 30000. The powder coating material according to any one of claims 1 to 6 , wherein the ratio of the mass average molecular weight to the number average molecular weight of the fluorine-containing polymer contained in the first particles is 1.0 to 8.0. .. The fluorine-containing polymer contained in the first particles contains a unit having the hydroxyl group, and contains the unit.
The powder coating material according to any one of claims 1 to 7 , wherein the fluorine-containing polymer has a hydroxyl value of 1 to 150 mgKOH / g. The fluorine-containing polymer contained in the first particles contains a unit having the carboxy group, and contains the unit.
The powder coating material according to any one of claims 1 to 7 , wherein the fluorine-containing polymer has an acid value of 1 to 150 mgKOH / g. The powder coating material according to any one of claims 1 to 9 , wherein the average circularity of the first particles is 0.90 or more. The powder coating material according to any one of claims 1 to 10 , wherein the volume particle size distribution index value of the first particle is 1.30 or less. The powder coating material according to claim 3 , wherein the average particle size of the particles containing the epoxy resin or the average particle size of the particles containing the polyester resin is 1 to 20 μm, respectively. The powder coating according to claim 3 , wherein the average particle size of the particles containing the epoxy resin or the average particle size of the particles containing the polyester resin is larger than the average particle size of the first particles. A coating film according to any one of claims 1 to 13 is applied onto a substrate to form a coating layer, and the coating layer is heat-treated to form a coating film on the substrate. Method of manufacturing a base material with a base material. A coated article having a base material and a coating film formed on the base material by the powder coating material according to any one of claims 1 to 13.