JP2003096378A - Fluoroplastic powder coating material composition and coated product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluoroplastic powder coating material composition which can form a coating film that is excellent in antistaticity, coating workability, contamination resistance, resistance to dust adhesion, weather resistance and lustering. SOLUTION: This fluoroplastic powder coating material composition comprises (A) a fluoroplastic and (B) an antistatic agent comprising an organic hydrophilic compound, wherein the fluoroplastic has a fluorine content of 10% or more; and the organic hydrophilic compound has a SP value of 19 (J/m<3> )<1/2> ×10<-3> or more. Preferably, (A) the fluoroplastic is a thermosetting fluoroplastic comprising a reactive fluorine-containing copolymer and a curing agent, wherein the reactive fluorine-containing copolymer has a fluoroolefin unit and a crosslinkable reactive group, the curing agent reacting with the crosslinkable reactive group to form a crosslinkage. A coated product comprises the coating film formed from the fluoroplastic powder coating material composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororesin powder coating material which is excellent in antistatic properties and coating workability and which forms a coating film excellent in stain resistance, dust adhesion, weather resistance and glossiness. Compositions and coated articles.

[0002]

2. Description of the Related Art Liquid fluororesin paints prepared by dissolving, emulsifying or dispersing a solvent-soluble fluororesin in a solvent are conventionally known as fluororesin paints utilizing the excellent weather resistance of fluororesins. Examples of the liquid fluororesin paint include the fluorocopolymer 100 described in JP-A-6-248222.
Disclosed is an antifouling fluororesin coating composition containing 0.1 to 70 parts by mass of one or more kinds selected from ethylene glycol compounds or polyethylene oxide compounds with respect to parts by mass. Similarly, Japanese Patent Application Laid-Open No. 7-76667 discloses a composition for a fluororesin coating obtained by mixing 0.1 to 100 parts by mass of a (meth) acrylate copolymer with 100 parts by mass of the fluorocopolymer. ing. In addition,
In 001-72928, (a) an emulsion of an organic synthetic resin, (b) a coupling agent, and (c) a group other than the organic synthetic resin (a) and capable of reacting with the coupling agent (b). Disclosed is a resin composition for low-contamination type water-based coatings, which comprises an organic compound for hydrophilicity having the above.

Further, a fluororesin powder paint capable of powder coating is known as a form different from the above-mentioned liquid fluororesin paint. Powder coating is widely used for coating on metal surfaces because of its advantages in terms of pollution-free, resource saving, and labor saving, and especially for bridges, balustrades, gates, fences, household siding agents that are important for weather resistance. It is also widely used in road construction materials, automobile bodies and parts, and home appliances. Examples of the fluororesin powder coating include, for example, JP-A-61-181567 and JP-A-61-1.
No. 81571, Japanese Patent Laid-Open No. 61-181572, powder coatings using a thermoplastic fluororesin such as ethylene-tetrafluoroethylene copolymer, and Japanese Patent Publication No. 6-104792. Known thermosetting fluororesin powder coatings are known. The thermosetting fluororesin powder coating material disclosed in JP-B-6-104792 contains a fluoroolefin unit, has a fluorine content of 10% by mass or more, and has an intrinsic viscosity measured in tetrahydrofuran at 30 ° C. 0.05-2 dl /
It is in the range of g, has a glass transition temperature of 30 to 120 ° C., and reacts with the fluorocopolymer (A) having a crosslinkable reactive group, and the crosslinkable reactive group of the fluorocopolymer. A curing agent capable of forming crosslinks (however, excluding a polyfunctional organosilicon compound containing an isocyanate group directly bonded to a silicon atom) (B), (A) /
(B) is blended in a mass ratio of 40/60 to 98/2, and the weight loss on heating of the fluorocopolymer is 5 mass% or less at 105 ° C. for 3 hours. It is characterized by that.

[0004]

However, when electrostatic coating is carried out using the above-mentioned fluororesin powder coating material, if the fluororesin powder coating material is discharged from the electrostatic coating spray gun, the fluororesin powder coating particles will be mixed with each other. Since the particles are rubbed and charged, and the charged fluororesin powder adheres to the tip of the gun and the like, it is necessary to frequently remove the adhered particles, which causes a problem that work efficiency is deteriorated. Further, as a result of a mass of fluororesin powder once attached to the tip of the gun adhering to the surface of the object to be coated, there is a problem that the surface smoothness of the coated surface deteriorates.

The phenomenon in which the resin powder adheres to the tip of the gun or the like due to the above-mentioned charging during coating is particularly noticeable in the fluororesin powder coating, as disclosed in JP-A-2-178.
The resin powder coating mainly composed of acrylic resin, polyester resin, epoxy resin, etc. described in Japanese Patent No. 361 has not been a practical problem. JP-A-2-178361
In order to improve the blocking resistance at the time of storage in powder coating and the flowability at the time of baking after coating,
A glass transition temperature of 8 is present on at least the surface of each powder particle.
0 to 150 ° C, SP value 18.4 to 30.7 (J /
A powder coating composition having m ³ ) ^1/2 × 10 ^-3 and resin fine particles having an average particle diameter of 0.01 to 10 µ is disclosed. However, in this publication, there is no description about a resin powder coating mainly composed of a fluororesin, and it is even suggested about the above-mentioned problems associated with charging of powder during coating, which is peculiar to the fluororesin powder coating. It has not been. Therefore, in order to solve the above-mentioned problems associated with the charging of powder during coating, which is peculiar to fluororesin powder coatings, JP-A-2-1783 has been proposed.
The person skilled in the art could not expect to apply the technique described in Japanese Patent No. 61. No means has been provided so far for solving the above-mentioned problems associated with the charging of powder during coating, which is peculiar to fluororesin powder coatings.

The present invention has been made in view of the above circumstances, and forms a coating film having excellent antistatic properties, coating workability, stain resistance, dust resistance, weather resistance and gloss. It is intended to provide a fluororesin powder coating composition.

[0007]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies and as a result, have found that a fluorine-containing resin (A) having a fluorine content of 10% or more has an SP value of 19%.
^Addition of an antistatic agent (B) composed of (J / m ³ ) ^1/2 × 10 ^-3 or more of an organic hydrophilic compound imparts antistatic property without impairing the weather resistance of the resin (A). The present invention has been completed, and it was found that the coating workability can be improved, and that the stain resistance and glossiness of the coating film after baking can be improved.

Namely, the fluororesin powder coating composition according to the present invention, a fluorine content of 10% or more of the fluorine-containing resin (A), SP value ^{19 (J / m 3) 1/2} × 10 - ^An antistatic agent (B) composed of ^three or more organic hydrophilic compounds is included. In the fluororesin powder coating composition according to the present invention, the fluororesin (A) has a reactive fluorocopolymer having a fluoroolefin unit and a crosslinkable reactive group, and the reactive fluorocopolymer has It is desirable that the thermosetting resin composition contains a curing agent capable of reacting with the crosslinkable reactive group to form crosslinks. Further, the present invention is
There is provided a coated article having a coating film formed by using the fluororesin powder coating composition.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The fluororesin powder coating composition according to the present invention is characterized by containing a fluorine-containing resin (A) as a main component and an antistatic agent (B). As the fluorine-containing resin (A), either a thermoplastic fluorine-containing resin or a thermosetting fluorine-containing resin may be used, and preferably a reactive fluorine-containing copolymer containing a fluoroolefin unit and a crosslinkable reactive group and cured. A thermosetting property that may cause a crosslinking reaction between the crosslinkable reactive group of the reactive fluorine-containing copolymer and the curing agent when the powder coating composition is coated on the surface of the object to be coated and then baked. A fluorine-containing resin is used. The following description exemplifies the case where a thermosetting fluorine-containing resin containing a combination of a reactive fluorine-containing copolymer (denoted by the following symbol (A)) and a curing agent is used as the fluorine-containing resin (A). is doing.

Examples of the raw material for the fluoroolefin unit of the reactive fluorine-containing copolymer (A) include tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, etc. The following can be used and can be appropriately selected according to the properties required for the coating film, the combination with the copolymer component or the curing agent. Further, these fluoroolefins may be used alone or in combination.
More than one species can be used.

The crosslinkable reactive group of the reactive fluorine-containing copolymer (A) used in the present invention includes a hydroxyl group, a carboxyl group, an amide group, an amino group, a mercapto group, a glycidyl group, an active halogen such as bromine and iodine, Examples thereof include an isocyanate group, a carbonyl group and an oxazoline group.
The method of introducing such a curing reaction site into the copolymer includes a method of copolymerizing a monomer having a crosslinkable reactive group, a method of decomposing a part of the copolymer, and a crosslinkable reaction to a functional group of the copolymer. Means such as a method of reacting a compound giving a group can be mentioned.

The crosslinkable reactive group suitable for use in the present invention is a monomer having a hydroxyl group or a group capable of being converted into a hydroxyl group and having a double bond copolymerizable with a fluoroolefin. Can be used, for example, hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, and hydroxycyclohexyl vinyl ether, vinyl hydroxyacetate, vinyl hydroxypropionate, vinyl hydroxybutyrate, and hydroxy Esters of hydroxyalkylcarboxylic acids such as vinyl herbate, vinyl hydroxyisobutyrate and vinyl hydroxycyclohexanecarboxylate with vinyl alcohol, hydroxyethyl ants Hydroxyalkyl allyl ethers such as ether, hydroxypropyl allyl ether, hydroxybutyl allyl ether, hydroxyisobutyl allyl ether, hydroxycyclohexyl allyl ether, hydroxyethyl allyl ester, hydroxypropyl allyl ester, hydroxybutyl allyl ester, hydroxyisobutyl allyl ester, hydroxy Hydroxy allyl esters such as cyclohexyl allyl ester, hydroxy alkyl esters of acrylic acid or methacrylic acid such as 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, and the like, and partial thereof. And compounds substituted with fluorine.

As the raw material for the hydroxyl group-containing unit, one or more of these can be selected and used. Further, it is desirable to use a vinyl-based or allyl-based compound because of its copolymerizability with fluoroolefin.

Examples of the above-mentioned monomer having a carboxyl group used in the present invention include (meth) acrylic acid and carboxyl alkyl allyl ether. Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate, glycidyl vinyl ether, glycidyl allyl ether, and the like. Examples of the monomer having an amino group include aminoalkyl vinyl ether and aminoalkyl allyl ether. Examples of the amide group-containing monomer include (meth) acrylamide and N-methylol acrylamide. Examples of the monomer having a nitrile group include (meth) acrylonitrile. Examples of the monomer having an isocyanate group include vinyl isocyanate and isocyanate ethyl acrylate. Examples of the monomer having an active halogen group include vinyl chloride and vinylidene chloride.

As a method for decomposing a part of the copolymer, a copolymer having a hydrolyzable ester group-containing monomer is copolymerized, and then the copolymer is hydrolyzed. A method for producing a carboxyl group in the polymer is exemplified. Further, it is also possible to form a cross-linkage by a transesterification reaction in a direct curing reaction without performing ester hydrolysis as described above. As a method of reacting a compound that gives a crosslinkable reactive group to the copolymer, a method of introducing a carboxyl group by reacting a hydroxyl group-containing copolymer with a divalent carboxylic acid anhydride such as succinic anhydride is preferable. Can be adopted.

Further, as the monomer for providing the above-mentioned crosslinkable reaction site, especially from the viewpoint of copolymerizability with fluoroolefin,
It is preferable to employ a vinyl type or allyl type compound.

Further, the reactive fluorine-containing copolymer (A) used in the present invention lowers the melting point or glass transition temperature of the reactive fluorine-containing copolymer in addition to the above-mentioned two types of units to further improve coating workability. A copolymerizable comonomer can be copolymerized with the above-mentioned two kinds of components for the purpose of improving the properties and imparting appropriate hardness, flexibility, luster and other physical properties to the coating film.

As such a comonomer, one having an unsaturated group active to the extent that it can be copolymerized with a fluoroolefin and not significantly impairing the weather resistance of the coating film is adopted. Usually, an ethylenically unsaturated compound, For example, alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, etc., vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl cyclohexanecarboxylate, etc. Esters with alcohols, alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, cyclohexyl allyl ether, ethyl allyl ester, Alkyl allyl esters such as luaryl ester, butyl allyl ester, isobutyl allyl ester, cyclohexyl allyl ester, alkenes such as ethylene, propylene, butylene, isobutylene, acrylic acid, methacrylic acid or ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl Acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, propyl methacrylate,
Butyl methacrylate, isobutyl methacrylate, 2
Examples thereof include esters of acrylic acid or methacrylic acid such as ethylhexyl methacrylate, and partially fluorine-substituted compounds thereof. These monomers may be used alone or in combination of two or more. As these comonomers, vinyl type, allyl type compounds or alkenes having excellent copolymerizability with fluoroolefins are preferably adopted.

When a vinyl-based or allyl-based alkyl ester or alkyl ether is used, the alkyl group is preferably a linear, branched or alicyclic alkyl group having about 2 to 10 carbon atoms. it can.

The reactive fluorine-containing copolymer (A) used in the present invention must have a fluorine content of 10% by mass or more. Usually, this fluorine content is related to the constitution ratio of the fluoroolefin unit in the reactive fluorine-containing copolymer (A). However, it is also possible to increase or decrease the content by polymer reaction after once producing the copolymer (A).

When the fluorine content in the reactive fluorine-containing copolymer (A) used in the present invention is less than 10% by mass, a coating film having sufficient weather resistance cannot be obtained. The fluorine content in the copolymer (A) is particularly preferably 15 to 72% by mass in view of the overall performance balance such as weather resistance of coating film and coating workability. Further, the reactive fluorine-containing copolymer (A) used in the present invention has a fluorine content of 10% by mass or more, and a fluoroolefin unit further contained in the range of 70 to 30 mol%. It can be preferably used. That is, when the content of the fluoroolefin unit is 30 mol% or more, the weather resistance is further remarkably improved, and when the content of the fluoroolefin unit is 70 mol% or less, the fluorine-containing copolymer tends to be non-crystalline, that is, the fluorine-containing copolymer. Since the copolymer is less likely to be crystallized, adhesion is good, a coating film having a uniform and smooth surface is easily formed, and high temperature is not required during baking of the coating material, which is particularly preferable.

The reactive fluorine-containing copolymer (A) used in the present invention has a crosslinkable reactive group, and by reacting with a curing agent, a coating film having toughness and excellent adhesion can be obtained. Crosslinkable reactive group 1 present in the molecule of a fluorinated copolymer (A)
The average molecular weight of the copolymer chain per unit is 250 to 25
It is desirable to set it to 000. The average molecular weight is 2500
When it is 0 or less, crosslinking is sufficient and physical properties such as solvent resistance can be kept good. When it is 250 or more, the crosslinking density is not too high and the flexibility of the coating film is good. become. The average molecular weight of the copolymer chain per one crosslinkable reactive group present in the molecule of the reactive fluorocopolymer (A) is: [molecular weight of fluorocopolymer / number of crosslinkable reactive groups in one molecule] expressed. Specifically, this average molecular weight is determined by taking the crosslinkable reaction group value (mgKOH / g) of the reactive fluorine-containing copolymer (A) such as hydroxyl value, acid value or epoxy group value as IR.
It can be measured by a method such as a spectrum, an NMR spectrum and a titration, and can be calculated by the following formula. (56.1 / Crosslinkable reactive group value) × 10 ³ [wherein 5
6.1 is the molecular weight of KOH. When the crosslinkable reactive group is an epoxy group, the epoxy equivalent corresponds to this value.

The hydroxyl value of the reactive fluorocopolymer (A) having a hydroxyl group as a crosslinkable reactive group is 1 to 200 mg.
KOH / g, particularly preferably 20 to 140 mg KOH
/ G is desirable. Hydroxyl value is 1mgKOH /
If it is at least g, crosslinking will be sufficient and the physical properties of the coating film will be good. When the hydroxyl group is less than 200 mgKOH / g, the crosslink density does not become too high, and good flexibility can be obtained.

The intrinsic viscosity of the reactive fluorine-containing copolymer (A) used in the present invention measured in tetrahydrofuran at 30 ° C. is preferably 0.05 to 2 dl / g.
When the intrinsic viscosity is 0.05 or more, it becomes solid and can be used as a powder coating composition. When the intrinsic viscosity is 2 or less, the softening point does not become too high and the flowability of the coating film becomes good.

The glass transition temperature of the reactive fluorine-containing copolymer (A) used in the present invention is 30 to 120 ° C., preferably 35 to 100 ° C. When the glass transition temperature is 30 ° C. or higher, it becomes solid and easy to use as a powder coating composition. Further, by setting the glass transition temperature to 120 ° C. or less, the softening point does not become too high, and the flowability can be kept good.

When a crystalline polymer is used as the reactive fluorine-containing copolymer (A), a high temperature is required during baking. When a crystalline polymer is used, it has a melting point of 200.
It is preferably below ℃.

The reactive fluorine-containing copolymer (A) used in the present invention can be synthesized by a conventionally known method. Polymerization can be carried out by allowing a polymerization initiator to act on a monomer mixture in a predetermined ratio in the presence or absence of a catalyst. Further, it can be produced by any method of solution polymerization, emulsion polymerization and suspension polymerization.

In the present invention, the reactive fluorine-containing copolymer (A) is used in the form of powder. The method for obtaining such a powdery fluorine-containing copolymer can be carried out by an appropriate method depending on the polymerization mode. When the copolymer is obtained by emulsion polymerization or suspension polymerization, the dispersion medium is removed from the polymerization solution under a reduced pressure of 0.01
It can be produced by evaporating and removing at 3 MPa or less at 50 to 100 ° C., and then pulverizing with a milling machine such as a wheelet type, a vibration mill type, and an impact type hammer mill type. When it is obtained by solution polymerization, it can be produced by removing the solvent of the polymerization liquid or by pouring it into a solution in which the polymer is not dissolved to precipitate the fluorine-containing copolymer, removing the solvent and then pulverizing.

The reactive fluorine-containing copolymer (A) used in the present invention is used in the form of powder, and such powder has a residual amount of solvent (hereinafter, used to include a dispersion medium) (heating). The weight loss) is preferably 5% by mass or less. By setting the residual amount of the solvent in the copolymer to 5% by mass or less, the storage stability of the powder coating material becomes good, and after baking and curing of the powder coating material, foaming, blistering, pinholes, etc. on the coating film occur. Does not occur. In particular, the residual amount of the solvent is preferably 2% by mass or less.

As the curing agent capable of reacting with the crosslinkable reactive group of the reactive fluorine-containing copolymer (A), a blocked isocyanate compound such as isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'- is used. Diphenylmethane diisocyanate, polyisocyanate compounds such as hexamethylene diisocyanate, dimers, trimers of these and isocyanate groups of isocyanate compounds such as polyisocyanate compounds modified with polyhydric alcohols such as trimethylolpropane, ε-caprolactam, phenol , A compound blocked with a blocking agent such as benzyl alcohol and methylethylketoxime. As the blocked isocyanate compound, a compound that is solid at room temperature can be preferably used.

Further, fumaric acid, succinic acid, adipic acid,
Aliphatic dibasic acids such as azelaic acid, sebacic acid, dodecanedioic acid, acid anhydrides such as phthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, acid value 10-300 mgK
OH / g, glass transition temperature of 30 to 120 ° C., number average molecular weight of 1000 to 15,000 polyester resin, acrylic resin, dicyandiamide and dicyandiamide derivative, imidazole and imidazole derivative, polyhydrazide compound, diaminophenylmethane, cyclic amidine Amine compounds such as compounds, melamine resins, terephthalic acid diglycidyl ester, paraoxybenzoic acid diglycidyl ester, triglycidyl isocyanate, spiroglycol diglycidyl ether, hydantoin compounds, alicyclic epoxy resin and other glycidyl compounds, 1,4-bis 2'-hydroxyethoxybenzene, bishydroxyethyl terephthalate, styrene-allyl alcohol copolymer, spiroglycol, tris 2-hydroxyethyl Isocyanurate, hydroxyl value 10
~ 300 mgKOH / g, glass transition temperature 30 ~ 12
A hydroxyl group compound such as polyester resin or acrylic resin having a number average molecular weight of 1,000 to 15,000 at 0 ° C., a polymercaptan compound, a polyaziridine compound,
Examples thereof include polyoxazoline compounds. As the curing agent, a compound that is solid at room temperature can be preferably used.

The amount of the curing agent blended is 1 to 1000 parts by weight, preferably 5 to 200 parts by weight, per 100 parts by weight of the reactive fluorine-containing copolymer (A). By setting the amount of the curing agent to be in the range of 5 to 200 parts by mass relative to 100 parts by mass of the copolymer (A), excellent physical properties such as surface glossiness, stain resistance, impact resistance, and weather resistance are obtained. A coating film can be formed.

The SP value of the antistatic agent (B) blended in the fluororesin powder coating material according to the present invention is 19 (J / m ³ ) ^1/2 ×
It is composed of an organic hydrophilic compound having a hydroxyl group of more than 10 ^-3 . The SP value (solubility parameter) is a cohesive energy density, that is, the evaporation energy per unit volume of one molecule raised to the power of 1/2, and is a numerical value indicating the magnitude of polarity per unit volume. The SP value can be calculated by the Fedros method (reference: RF Fedro).
s, Polym. Eng. Sci. , 14 [2] 147
(See 1974).

As the organic hydrophilic compound having an SP value of 19 (J / m ³ ) ^1/2 × 10 ^-3 or more, a polar compound, particularly SP
It can be appropriately selected and used from polymers and copolymers having a value of 19 or more. Suitable antistatic agents (B) in the present invention include, for example, CH ₂ ═C (CH ₃ ) COO.
(C ₂ H ₄ O) _p CH ₃ (p is about 9, manufactured by NOF CORPORATION, trade name “PME-400” polymer, SP value 19.0 (J /
m ³ ) ^1/2 × 10 ^-3 ), n-butyl polyacrylate (SP
Value 19.2 (J / m ³ ) ^1/2 × 10 ^-3 ), polymethylmethacrylate (19.2), PEG6000 (19.
5), polystyrene (20.4), polyallylamine (20.7), PEG1000 (20.8), CH
_{2 = CHCOO (C 2 H 4} O) p H (p is about 10, manufactured by NOF Corporation, trade name "AE-400", SP value 21.3 (J /
m ³ ) ^1/2 × 10 ^-3 ), poly N-acryloylmorpholine (SP value 22.1 (J / m ³ ) ^1/2 × 10 ^-3 ), polyvinylpyrrolidone (22.4), polymethacryl Acid (22.8), polyvinylpyridine (23.3), poly-2-acrylamido-2-methylpropanesulfonic acid (24.2), polyacrylic acid (24.6), polyacrylonitrile (26) .3), polyvinylacetamide (27.7), polyvinylformamide (3)
1.7), polyglycerin (32.1), polyvinyl alcohol (33.0), polyacrylamide (3)
4.4), chitosan (37.2) and dextrin (43.0). Among these, the antistatic agent (see Table 2) used in Examples described later is preferable.

To impart antistatic properties to the fluororesin powder coating composition of the present invention by blending an antistatic agent having an SP value of 19 (J / m ³ ) ^1/2 × 10 ^-3 or more. You can The mixing ratio of the antistatic agent (B) is 0.1 to 100 parts by mass of the reactive fluorine-containing copolymer (A).
The amount is 100 parts by mass, preferably 0.5 to 50 parts by mass. The compounding amount of the antistatic agent (B) is 100% of the copolymer (A).
By setting the range of 0.5 to 50 parts by mass with respect to parts by mass, sufficient antistatic property can be obtained without impairing the stain resistance, weather resistance, glossiness and impact resistance of the coating film after baking. It can be applied, the amount of powder adhering to the spray gun in the coating process can be reduced, and the number of times of cleaning the gun can be reduced. Therefore, the efficiency of the coating work using powder coating mainly composed of fluororesin can be improved. .

In the fluororesin powder coating composition of the present invention, the antistatic agent (B) may be present on at least the surface of the reactive fluorocopolymer (A) powder (fluorine-containing resin). . That is, the antistatic agent (B) may be a mixed powder in a state in which at least a part of the reactive fluorocopolymer (A) is compatible, or the antistatic agent (B) may be reactive. The fluorine-containing copolymer (A) is not compatible with each other and exists as separate powders, and the antistatic agent (B) powder is attached to the surface of the reactive fluorine-containing copolymer (A) powder. May be. Furthermore, the reactive fluorine-containing copolymer (A) and the curing agent may be capable of causing a crosslinking reaction when the fluororesin powder coating composition is applied onto the surface of an object to be coated and baked. In the fluororesin powder coating composition,
The reactive fluorine-containing copolymer (A) and the curing agent may be present as a mixed powder in which at least a part is compatible, or may be present as separate powders in which both are not compatible.

The fluororesin powder coating composition of the present invention comprises
Additives normally used in coating compositions can be included as the third component. That is, coloring pigments (for example, titanium dioxide, red iron oxide, yellow iron oxide, inorganic pigments such as carbon black and phthalocyanine blue, phthalocyanine green, quinacridone red pigment, organic pigments such as isoindolinone yellow pigment), talc, silica, Extender pigments such as calcium carbonate, metal powders such as aluminum powder and stainless powder, mica powder and leveling agents, ultraviolet absorbers,
Add additives such as heat deterioration inhibitor and anti-foaming agent if desired 1
One kind or two or more kinds can be mixed. In the present invention, the above-mentioned third component, which is optionally blended, may be blended in advance with at least one of the components (A) and (B) of the composition of the present invention. The composition of the present invention can be prepared in the same manner as a known thermosetting powder coating manufacturing method.

The fluororesin powder coating composition produced as described above has a particle size of 400 μm or less, and can be applied to metals such as iron, aluminum, copper, zinc or mixtures thereof such as stainless steel and brass, for example. A uniform coating can be formed by uniformly coating with a commercially available electrostatic powder coating machine, fluidized dipping device, etc., and then baking with a hot air oven, infrared oven, dielectric heating oven, or the like.

[0039]

EXAMPLES [Synthesis of Reactive Fluorine-Containing Copolymer (A) (Fluorine-Containing Resin)] (Synthesis Example 1) In a pressure resistant reactor with a stirrer made of stainless steel and having an internal capacity of 300 ml, t-butanol 15 was added.
7 g, cyclohexyl vinyl ether (CHVE) 16
g, 9 g of isobutyl vinyl ether (iBVE), 25 g of hydroxybutyl vinyl ether (HBVE), 1 g of potassium carbonate, 0.07 g of 2,2'-azobisisobutyronitrile (AIBN), and dissolved oxygen by solidification degassing with liquid nitrogen To remove. Then, 50 g of chlorotrifluoroethylene (CTFE) is introduced, and the temperature is gradually raised. The reaction is continued under stirring while maintaining the temperature at 65 ° C, and after 10 hours, the reaction is stopped by cooling the reactor with water.
After cooling to room temperature, unreacted monomer is purged and the reactor is opened. After filtration with diatomaceous earth, the solvent was removed under reduced pressure to obtain a reactive fluorine-containing copolymer (hereinafter abbreviated as resin) (A-1).

(Synthesis Examples 2 to 6) Monomer mixtures having the composition ratios shown in Table 1 were polymerized in the same manner as in Synthesis Example 1. However, resins A-2 to A-6 shown in Table 1 were obtained by appropriately changing the amounts of t-butanol and AIBN.

[0041]

[Table 1]

[Antistatic Agent (B)] The abbreviation of the antistatic agent (B) used in this example, the weight average molecular weight and S.
The P value is shown in Table 2. The SP value was calculated by the Fedros method.

[0043]

[Table 2]

[Examples 1 to 26] The resin (A), the antistatic agent (B), the curing agent, the additive and the pigment were blended in the proportions shown in Tables 3 to 6 (in Tables 3 to 6, "parts blended"). "Denotes all parts by weight.)" After uniformly mixing with a dry blender (Mitsui Kakoki Co., Ltd., trade name “Henschel Mixer”) for 1 minute, melt kneading with an extrusion kneader (Bus Co., Ltd., trade name “Busco Kneader”) at a temperature of 80 to 100 ° C. Then, after cooling, it was finely pulverized using a hammer mill. Subsequently, it was filtered through a 150-mesh wire net to obtain a powder coating material. An electrostatic powder coating gun (manufactured by Onoda Cement Co., Ltd., with the obtained powder coating on a 0.8 mm thick zinc phosphate-treated iron plate
Electrostatic coating was performed for 4 minutes under the conditions of a voltage of 70 kV, a powder discharge amount of 100 g / min, a temperature of 20 ° C. and a humidity of 60% using a product name “GX-501”). Furthermore, 20 at 190 ℃
Baking for minutes gave a cured coating with a thickness of about 40 microns. Tables 3 to 6 show the antistatic properties of the powder coating materials of Examples 1 to 26 and various evaluation results of coated plates. Each evaluation item described in these tables was measured according to the following methods.

<Antistatic Property> Regarding the antistatic property of each powder coating material, as described above, when each powder coating material is electrostatically coated on a surface-treated iron plate using an electrostatic coating gun, the powder coating material at the tip of the gun is coated. The degree of adhesion of No. 1 was visually observed. Regarding Examples 1 to 20 and Example 22, the amount of powder adhering to the tip of the gun was reduced and the number of times of cleaning the gun was reduced, as compared with the powder coating composition containing no (B) (Example 21). That is, the case where it was judged that the antistatic improvement effect by the blending of (B) was observed was expressed as ◯. On the other hand, the amount of powder adhering to the tip of the gun is similar to that of powder coating without (B),
Those in which the number of times of cleaning of the gun was about the same, that is, those in which it was judged that the antistatic improvement effect due to the blending of (B) was not observed are marked with x. Examples 23 and 2 in which as the resin, Resin A-6 having a fluorine content equal to or less than the fluorine content of the fluorine-containing resin according to the present invention (fluorine content 9.8%) was used.
Regarding No. 4, the antistatic property of Example 24 is described as a criterion of the above antistatic improvement effect in comparison with Example 23 using this resin A-6 and containing no antistatic agent. Regarding Examples 25 and 26 in which a polyester resin different from the fluorine-containing resin of the present invention was used as the resin, the antistatic property of Example 26 was higher than that of Example 25 in which this polyester resin was not blended with an antistatic agent. The criteria for the antistatic improvement effect in the case of the above are shown.

<Glossiness> 6 according to JIS Z8741
The specular gloss of 0 degree was measured. The larger the value, the better the gloss.

<Octane desorption work> The octane desorption work is calculated from the contact angle of an oily substance (octane) present on the surface of a coating film in water and measured from the contact angle. This octane desorption work (W _A ') can be expressed by the following equation 1. W _A '= γsw + γwo−γso (Equation 1) (where γsw is the interfacial tension between the coating surface and water (J / m
² ), γwo is the interfacial tension between water and octane (J / m ² ),
γso is the interfacial tension between the coating surface and octane (J / m ² )
Represents ) Young's equation γsw = γso + γwo = cos θ (Equation 2) (where θ is the contact angle that octane makes with the coating film in water) is substituted into Equation 1 above, and the extended Fowkes equation is used to obtain water and octane. Paying attention to the fact that the dispersion components of the surface tension are equal, the following equation can be derived. W _A '= C (1 + cos θ) (Equation 3) (where C is a polar component of the surface tension of water, and C =
It is 0.051 (J / m ² ). ) Θ can vary from 0 to 180 °, so W _A 'is 0-1
It changes in the range of 0.2 × 10 ^-2 (J / m ² ). _A smaller W _A 'means that less energy is required to separate octane from the film surface in water. On the other hand, a large amount of oily substances are contained in the substances that cause dirt, and the coating surface from which oily substances such as octane are easily separated in water is a coating surface on which oily substances are easily washed away by rain, etc. It is presumed that the surface of the coating has good stain resistance. In order to exhibit stain resistance, octane desorption work in water is 3.0 × 10 ^-2 J / m.
It is preferably less than ² . Furthermore, 2.0 × 10 ^-2
It is preferably less than J / m ² .

<Slope Contamination Resistance> Painted Plate (Size: 200
(× 95 × 8 mm) was bent at a portion of 100 mm, and the coated surface was outside so that the upper part was at an angle of 30 degrees from the horizontal plane and the lower part was vertical, and subjected to an outdoor exposure test in Kawasaki City, Kanagawa Prefecture. The L * value of the 30 ° inclined surface was measured after 3 months of exposure of this coated plate. Difference in L * value before and after the test ΔL *
Was calculated and described as an absolute value. The L * value is SQ2
000 (manufactured by Nippon Denshoku Industries Co., Ltd.), JIS Z87
It measured according to 30. The smaller this value is, the better the slope stain resistance is.

<Rain streak resistance> The outdoor exposure plate evaluated for slope contamination was evaluated for rain streak on the vertical surface. When the rain streaks were not conspicuous, the marks were marked as ○, the ones that were somewhat conspicuous were marked as △, and the conspicuous ones were marked as ×.

<Dirt wipeability> Carbon black 5%
An aqueous solution was prepared and sprayed on the coating film. 40 ° C
After being dried for 2 hours, the surface was lightly wiped with gauze moistened with water. When the carbon black was wiped off well, it was indicated as ◯, and when the carbon black was not wiped off so much, it was indicated as x.

<Accelerated weather resistance> JIS K5400 9.
The gloss retention rate after 4000 hours of the carbon arc lamp accelerated weathering test described in 8.1 was measured. Gloss retention rate 8
0% or more is represented by O, and gloss retention less than 80% is represented by X.

[0052]

[Table 3]

[0053]

[Table 4]

[0054]

[Table 5]

[0055]

[Table 6]

From the evaluation results of Tables 3 to 6, the powder coating materials of Examples 1 to 20 according to the present invention were the powder coating material of Example 21 containing no antistatic agent and polymethacrylic acid having an SP value of less than 19. Compared with the powder coating of Example 22 containing n-butyl (PBuMA), the performance was improved in each item of antistatic property, octane desorption work, 3 months slope stain resistance, 3 months rain line stain resistance and stain wipeability. Was recognized. Further, the powder coating materials of Examples 23 and 24 using the resin A-6 (fluorine content of 9.8%) having a fluorine content equal to or lower than the fluorine content of the fluorine-containing resin according to the present invention are used as the resin of the present invention. 1 to 2 according to
The stain-wipeability and accelerated weather resistance were inferior to those of the powder coating material of No. 0. Further, each powder of Example 25 in which a polyester resin containing no fluorine is used as a resin and an antistatic agent is not blended, and Example 26 in which an antistatic agent (PAAm) is blended using the same polyester resin As a result of comparing the paints, in the powder paint mainly composed of polyester resin, the improvement of the antistatic property of the powder paint by the addition of the antistatic agent was not recognized. Furthermore, the powder coatings of Examples 25 and 26 are compared with the powder coatings of Examples 1 to 20 according to the invention,
The stain-wipeability and accelerated weather resistance were poor.

[0057]

According to the present invention, the fluorine content is 10%.
SP value of 19 (J / m
³ ) By blending an antistatic agent consisting of ^1/2 × 10 ^-3 or more organic hydrophilic compounds, charged fluororesin powder adheres to the gun tip during electrostatic coating, resulting in poor work efficiency. Can be solved, the problem that the lump of fluororesin powder once attached to the tip of the gun adheres and the surface smoothness of the object to be coated deteriorates, and it has excellent antistatic properties, coating workability, and stain resistance. It is possible to provide a fluororesin powder coating composition which forms a coating film excellent in dust adhesion resistance, weather resistance and glossiness.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J038 BA162 BA192 CC032 CD091                       CD111 CD121 CD131 CE022                       CG032 CG142 CG162 CG172                       CH032 CH142 CH192 CK032                       CK042 GA02 GA03 GA06                       GA07 GA08 GA09 GA11 GA12                       GA13 KA03 KA12 MA02 MA16                       NA01 NA03 NA05 NA20 NA23                       PA03 PA04 PB05 PB07 PB09                       PC02

Claims (3)

[Claims] 1. An antistatic agent comprising a fluorine-containing resin (A) having a fluorine content of 10% or more and an organic hydrophilic compound having an SP value of 19 (J / m ³ ) ^1/2 × 10 ^-3 or more. (B) is contained, The fluororesin powder coating composition characterized by the above-mentioned. 2. The fluorine-containing resin (A) reacts with a reactive fluorocopolymer having a fluoroolefin unit and a crosslinkable reactive group, and a crosslinkable reactive group of the reactive fluorocopolymer. A curing agent capable of forming a crosslink is included.
The fluororesin powder coating composition as described in 1. 3. A coated article having a coating film formed using the fluororesin powder coating composition according to claim 1 or 2.