JP2020007497A - Powder coating, method for producing base material with coating film, and base material with coating film - Google Patents

Abstract

To provide a powder coating that can form a coating film with excellent impact resistance and excellent in-plane uniformity of impact resistance, and provide a method for producing a base material with a coating film, and a base material with a coating film.SOLUTION: A powder coating contains: a fluorine-containing polymer containing a unit based on fluoroolefin and a unit based on a monomer having a carboxy group; a curing agent; and a curing catalyst. The curing catalyst is an organic phosphorus compound having one or more phosphorus atoms and 12 or more carbon atoms.SELECTED DRAWING: None

Description

  The present invention relates to a powder coating, a method for producing a coated substrate, and a coated substrate.

2. Description of the Related Art In recent years, in the area of paints, it has been required to suppress emission of volatile organic compounds (VOCs) such as organic solvents into the air from the viewpoint of environmental load. Therefore, from the viewpoint of VOC removal, powder coating materials that do not contain an organic solvent have attracted attention. Powder coatings do not require exhaust treatment and wastewater treatment at the time of painting, and can be recovered and reused, so they have low environmental impact.
Patent Document 1 discloses a powder coating containing a fluorinated polymer having a carboxy group and a curing agent.

JP 2000-26767 A

In recent years, the performance required of powder coating materials containing a fluoropolymer has been further improved. For example, there is a need for a powder coating that can form a coating film on a substrate that has excellent impact resistance and also has excellent in-plane uniformity of impact resistance.
The present inventors have found that, depending on the type of the curing catalyst contained in the powder coating, at least one of the in-plane uniformity of the impact resistance and the impact resistance of the coating film formed using the same is inferior. .

  The present invention has been made in view of the above problems, and provides a powder coating material capable of forming a coating film having excellent in-plane uniformity of impact resistance and impact resistance, a method for producing a coated substrate, and a coated substrate The purpose is to provide.

  The present inventors have conducted intensive studies on the above-described problems, and as a result, when a powder coating containing a fluoropolymer containing a unit based on a specific monomer, a curing agent, and a curing catalyst having a specific structure is used, desired results can be obtained. The inventors have found that effects can be obtained, and have reached the present invention.

That is, the present inventors have found that the above-described problems can be solved by the following configuration.
[1] A powder coating comprising a fluoropolymer containing a unit based on a fluoroolefin and a unit having a carboxy group, a curing agent, and a curing catalyst, wherein the curing catalyst has one or more phosphorus atoms and 12 A powder coating, which is an organic phosphorus compound having at least two carbon atoms.
[2] The powder coating according to [1], wherein the curing catalyst is a compound containing no oxygen atom.
[3] The powder coating according to [1] or [2], wherein the curing catalyst is a phosphine or phosphonium salt.
[4] The powder according to any one of [1] to [3], wherein the curing catalyst is at least one selected from the group consisting of compounds represented by Formulas 1, 2, and 3 described below. paint.
[5] The powder according to any one of [1] to [4], wherein the content of the unit having a carboxy group is 3 to 30 mol% based on all units contained in the fluoropolymer. paint.
[6] The powder according to any one of [1] to [5], wherein the curing agent is a compound having two or more epoxy groups, carbodiimide groups, oxazoline groups, or β-hydroxyalkylamide groups in one molecule. paint.
[7] The composition of [1] to [6], wherein the curing agent is contained in an amount of 1 to 20 parts by mass and the curing catalyst is contained in an amount of 0.01 to 10 parts by mass with respect to 100 parts by mass of the fluoropolymer. Powder coating according to any one of the above.
[8] The powder coating material according to any one of [1] to [7] is applied to a substrate to form a powder coating layer, and the powder coating layer is heat-treated to be applied on the substrate. A method for producing a coated substrate, comprising forming a film.
[9] A base material, and a coating film formed on the base material by the powder coating material according to any of [1] to [7], wherein the gel fraction of the coating film is 80% or more. A substrate with a coating film, characterized in that:

  ADVANTAGE OF THE INVENTION According to this invention, the powder coating material which can form the coating film excellent in the in-plane uniformity of impact resistance and impact resistance, the manufacturing method of the base material with a coating film, and the base material with a coating film can be provided.

The meanings of the terms in the present invention are as follows.
The numerical range represented by using “to” means a range including the numerical values described before and after “to” as the lower limit and the upper limit.
“(Meth) acrylate” is a generic term for acrylate and methacrylate, and “(meth) acryl” is a generic term for “acryl” and “methacryl”.
The “unit” is a general term for an atomic group formed directly by polymerization of a monomer and based on one molecule of the monomer, and an atomic group obtained by chemically converting a part of the atomic group. The content (mol%) of each unit with respect to all units contained in the polymer can be determined by analyzing the polymer by a nuclear magnetic resonance spectroscopy.
The “acid value” and “hydroxyl value” are values measured according to the method of JIS K 0070-3 (1992), respectively.
"Number average molecular weight" and "weight average molecular weight" are values measured by gel permeation chromatography using polystyrene as a standard substance. "Number average molecular weight" is also called "Mn", and "weight average molecular weight" is also called "Mw".
"Glass transition temperature" is the midpoint glass transition temperature measured by differential scanning calorimetry (DSC). “Glass transition temperature” is also referred to as “Tg”.
The “melt viscosity” means the value of the melt viscosity of a sample at 170 ° C. when the temperature is measured from 130 ° C. to 200 ° C. at a rate of 10 ° C./min using a rotary rheometer. I do.
“Powder” means a collection of a plurality of particles. The average particle diameter of the particles constituting the powder is measured on a volume basis using a known particle size distribution measuring device (manufactured by Sympatec, trade name “Helos-Rodos” or the like) using a laser diffraction method as a measurement principle. Is a value at a cumulative frequency of 50% calculated from the particle size distribution of.
"Gel fraction" is a value measured by the following procedure.
First, a coating film is added to tetrahydrofuran so as to have a concentration of 5% by mass, and left standing for 16 hours to dissolve soluble components. Thereafter, the supernatant is collected and dropped into ethanol to precipitate ethanol-insoluble components. The precipitate is collected, dried at 60 ° C. for 1 hour, and the mass of the precipitate is measured, and the gel fraction can be calculated from the following equation.
Gel fraction (%) = 100 × (w1-w2) / w1
Here, w1 is the mass of the coating film added to tetrahydrofuran, and w2 is the mass of the precipitate. When the gel fraction is 90% or more, it is determined that the fluororesin has a crosslinked structure.
The “film thickness” is a value measured using an eddy current film thickness meter (trade name “EDY-5000”, manufactured by Sanko Electronics Co., Ltd.).

  The powder coating material of the present invention (hereinafter also referred to as “the present coating material”) includes a unit based on fluoroolefin (hereinafter also referred to as “unit F”) and a unit having a carboxy group (hereinafter also referred to as “unit 1”). ), A curing agent, and a curing catalyst, wherein the curing catalyst is an organic phosphorus compound having at least one phosphorus atom and at least 12 carbon atoms (hereinafter referred to as an organic phosphorus compound). , "Specific curing catalyst").

A coating film formed by heating the present coating material (hereinafter, also referred to as “the present coating film”) is excellent in impact resistance and in-plane uniformity of impact resistance. Here, "excellent in-plane uniformity of impact resistance" means a state where there is little variation in impact resistance values at different positions on the coating film surface.
The present inventors presume the reason for this as follows.
Since the specific curing catalyst is a compound containing a large number of carbon atoms, it has excellent miscibility with the fluoropolymer in the present coating composition. Thereby, the crosslinking between the fluoropolymer and the curing agent is promoted, and since the fluoropolymer is uniformly cured throughout the coating film, excellent in-plane uniformity of impact resistance and impact resistance is obtained. It is believed that the present coating film is obtained.

Fluoroolefins are olefins in which one or more of the hydrogen atoms have been replaced by fluorine atoms. In the fluoroolefin, one or more hydrogen atoms not substituted with a fluorine atom may be substituted with a chlorine atom.
Specific examples of the _{fluoroolefin, CF 2 = CF 2, CF} 2 = CFCl, CF 2 = CHF, CH 2 = CF 2, CF 2 = CFCF 3, CF 2 = CHCF 3, CF 3 CH = CHF, CF 3 CF = CH ₂ and the like. Fluoroolefins, from the viewpoint of _{copolymerizability, CF 2 = CF 2, CF} 2 = CFCl, CF 3 CH = CHF, the CF 3 CF = CH _{2 Preferably,} CF 2 = CFCl is particularly preferred. Two or more fluoroolefins may be used in combination.
The content of the unit F is preferably from 20 to 70 mol%, particularly preferably from 40 to 60 mol%, from the viewpoint of the weather resistance of the present coating film, based on all units contained in the fluoropolymer.

  The unit 1 may be a unit based on a monomer having a carboxy group (hereinafter, also referred to as “monomer 1”), and an acid is added to a hydroxyl group of a fluoropolymer including a unit having a hydroxyl group described later. A unit obtained by reacting an anhydride (such as succinic anhydride) and converting a part or all of the hydroxyl groups to a carboxy group may be used. The unit 1 is preferably a unit based on a monomer having a carboxy group from the viewpoint of blocking resistance of the present coating composition. Unit 1 has no fluorine atom.

The unit 1 is a unit based on the monomer 1 from the viewpoint of suitably imparting an acid value to the fluoropolymer, particularly from the viewpoint of obtaining a fluoropolymer having only an acid value without a hydroxyl value. Is preferred. If the fluoropolymer has only an acid value without a hydroxyl value, the fluoropolymer of the present invention can be powdered more stably.
Examples of the monomer 1 include an unsaturated carboxylic acid, (meth) acrylic acid, and a monomer obtained by reacting a polycarboxylic acid or an acid anhydride thereof with a hydroxy group of the above-mentioned monomer having a hydroxy group. No.
The monomer 1 is preferably a monomer represented by the formula X ¹ -Y ¹ .
X ¹ _{is, CH 2 = CH-, CH (} CH 3) = CH- or _{CH 2 = C (CH 3)} - and _is, CH 2 = CH- or _{CH (CH} 3) = CH- are preferred.
Y ¹ is a carboxy group or a monovalent saturated hydrocarbon group having 1 to 12 carbon atoms having a carboxy group, and is preferably a carboxy group or a carboxyalkyl group having 1 to 10 carbon atoms.

As specific examples of the monomer 1, CH ₂ ＣＨCHCOOH, CH (CH ₃ ) ＝ CHCOOH, CH ₂ ＣC (CH ₃ ) COOH, a compound represented by the formula CH ₂式 CH (CH ₂ ) _n1 COOH ( However, n1 shows the integer of 1-10.).
As the monomer 1, two or more kinds may be used in combination.

When the powder coating contains a curing agent, the carboxy group of unit 1 serves as a crosslinking point, and the crosslinking reaction between the fluoropolymers proceeds through the curing agent, and the hardness of the present coating film is improved. The coating properties such as weather resistance, water resistance, chemical resistance and heat resistance are improved.
The content of the unit 1 is preferably 3 to 30 mol%, more preferably 4 to 20 mol%, and more preferably 5 to 20 mol%, based on all the units contained in the fluoropolymer, in that the impact resistance of the coating film is more excellent. -10 mol% is particularly preferred.

From the viewpoint of adjusting various physical properties (such as hardness and flexibility of the coating film) of the present fluorine-containing polymer, vinyl ether, vinyl ester, allyl ether, allyl ester, and (meth) It may contain a unit (hereinafter, also referred to as “unit 2”) based on at least one monomer selected from acrylic acid esters (hereinafter, also referred to as “monomer 2”). In addition, the monomer 2 and the unit 2 do not have a fluorine atom. Further, examples of the crosslinkable group include a carboxy group, a hydroxyl group, an amino group, an alkoxysilyl group, and the like. Monomer 2 is preferably a monomer represented by the formula ^X 2 -Z ^2.
X ² _{is, CH 2 = CHC (O)} O-, CH 2 = C (CH 3) C (O) O-, CH 2 = CHOC (O) -, CH 2 = CHCH 2 OC (O) -, CH ₂ ＣＨCHO— or CH ₂ ＣＨCHCH ₂ O—, and from the viewpoint of excellent weather resistance of the present coating film, CH ₂ ＣＨCHOC (O) —, CH ₂ ＣＨCHCH ₂ OC (O) —, CH ₂ ＣＨCHO. — Or CH ₂ ＣＨCHCH ₂ O— is preferred.

Z ² is a monovalent hydrocarbon group having 1 to 24 carbon atoms. The monovalent hydrocarbon group may be linear or branched. Further, the monovalent hydrocarbon group may have a ring structure or may have a ring structure. Further, the monovalent hydrocarbon group may be a monovalent saturated hydrocarbon group or a monovalent unsaturated hydrocarbon group.
The monovalent hydrocarbon group is preferably an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aryl group or an aralkyl group, and is an alkyl group having 2 to 12 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, An aryl group having 10 to 10 or an aralkyl group having 7 to 12 carbon atoms is more preferable.
Specific examples of the alkyl group include a methyl group, an ethyl group, a tert-butyl group, a hexyl group, a nonyl group, a decyl group, and a dodecyl group.
Specific examples of the cycloalkyl group include a cyclohexyl group.
Examples of the cycloalkylalkyl group include a cyclohexylmethyl group.
Specific examples of the aralkyl group include a benzyl group.
Specific examples of the aryl group include a phenyl group and a naphthyl group.

Z ² is an alkyl group having 4 to 8 carbon atoms represented by the formula —C (Z ²¹ ) ₃ (however, 3 number of ^{Z 21} are each independently an alkyl group having 1 to 5 carbon atoms.), a cycloalkyl group having 6 to 10 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or preferably an aralkyl group having 7 to 12 carbon atoms, an alkyl group having 4 to 8 carbon atoms and more preferably of the formula ^{-C (Z} _{21) 3,} carbon atoms of the formula ^{-C (Z} _{21) 3} 6-8 alkyl groups are particularly preferred.

The monomer 2 may be used in combination of two or more kinds.
Specific examples of the monomer 2 include ethyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, vinyl acetate, vinyl pivalate, and vinyl neononanoate (trade name “Veoba 9” manufactured by HEXION). , Neodecanoic acid vinyl ester (manufactured by HEXION, trade name "Veoba 10"), benzoic acid vinyl ester, tert-butyl (meth) acrylate, and benzyl (meth) acrylate.
When the fluorinated polymer contains the unit 2, the content of the unit 2 is preferably from 1 to 70 mol%, more preferably from 10 to 50 mol%, based on all units contained in the fluorinated polymer.

The fluorinated polymer may include a unit (hereinafter, also referred to as “unit 3”) based on a monomer having a hydroxyl group (hereinafter, also referred to as “monomer 3”). However, it is preferable that the fluoropolymer does not contain the unit 3 from the viewpoint of more stably powdering the fluoropolymer. Unit 3 has no fluorine atom.
Monomer 3 include allyl alcohol, or a hydroxyl group, vinyl ethers, vinyl esters, allyl ethers, allyl esters or (meth) acrylic acid ester, from the viewpoint of excellent copolymerizability with the unit F, wherein X ³ monomer or an allyl alcohol represented by -Y ³ are preferred.
X ³ represents CH ₂ ＣＨCHC (O) O—, CH ₂ ＣC (CH ₃ ) C (O) O—, CH ₂ ＣＨCHOC (O) —, CH ₂ ＣＨCHCH ₂ OC (O) —, CH ₂ = CHO- or _CH 2 = CHCH ₂ is O-.
Y ³ is a monovalent saturated hydrocarbon group having 2 to 12 carbon atoms and having a hydroxyl group. The monovalent saturated hydrocarbon group may be linear or branched. Further, the monovalent saturated hydrocarbon group may have a ring structure or may have a ring structure.
The monovalent saturated hydrocarbon group is preferably an alkyl group having 2 to 6 carbon atoms or an alkyl group containing a cycloalkylene group having 6 to 8 carbon atoms.

Specific examples of the monomer _{3, CH 2 = CHOCH 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, include _{CH 2 = CHCH 2 OCH 2 CH} 2 CH 2 CH 2 OH. Incidentally, "- cycloC ₆ H ₁₀ -" represents cyclohexylene, "- cycloC ₆ H ₁₀ -" binding site is usually 1,4.
Two or more monomers 3 may be used in combination. Further, as described above, the hydroxyl group of the fluorinated polymer containing the unit 3 can be converted into a carboxy group for use.

  When the fluoropolymer contains unit 3, the content of unit 3 is preferably less than 35 mol%, more preferably less than 20 mol%, and more preferably less than 5 mol%, based on all units contained in the fluoropolymer. Particularly preferred.

The fluoropolymer contains 20 to 70 mol%, 3 to 30 mol%, and 0 to 70 mol% of the unit F, the unit 1 and the unit 2 in this order with respect to all units of the fluoropolymer. Is preferred.
The acid value of the fluoropolymer is preferably from 5 to 150 mgKOH / g, more preferably from 10 to 100 mgKOH / g, still more preferably from 25 to 80 mgKOH / g, and still more preferably from 30 to 60 mgKOH / g, from the viewpoint of the impact resistance of the coating film. g is particularly preferred.
When the fluoropolymer is a fluoropolymer having a hydroxyl value, the hydroxyl value of the fluoropolymer is preferably 100 mgKOH / g or less, more preferably 50 mgKOH / g, and more preferably 5 mgKOH, from the viewpoint of the stability of the coating composition. / G or less is particularly preferred. The lower limit is usually 0 mgKOH / g.
The content of the fluoropolymer is preferably from 5 to 90% by mass, more preferably from 15 to 80% by mass, and particularly preferably from 20 to 50% by mass, based on the total mass of the present coating composition. When the content of the fluoropolymer is within the above range, the weather resistance of the present coating film is further improved.

Tg of the fluoropolymer is preferably from 40 to 120 ° C, more preferably from 50 to 100 ° C, and particularly preferably from 50 to 80 ° C, from the viewpoint that the anti-blocking property of the present coating composition is more excellent.
The melt viscosity at 170 ° C. of the fluoropolymer is preferably from 1 to 200 Pa · s, more preferably from 20 to 100 Pa · s, and particularly preferably from 20 to 95 Pa · s. When the melt viscosity is 1 Pa · s or more, the impact resistance of the present coating film is more excellent. When the melt viscosity is 200 Pa · s or less, the miscibility between the fluoropolymer and the specific curing catalyst is further improved, so that the in-plane uniformity of impact resistance of the present coating film is more excellent.

The melt viscosity is preferably set within the above range by controlling the molecular weight of the fluoropolymer and the type and content of the unit contained in the fluoropolymer, particularly controlling Mw.
Mw of the fluoropolymer is preferably from 15,000 to 75,000, more preferably from 25,000 to 60,000. When the Mw of the fluoropolymer is 15,000 or more, the impact resistance and the solvent resistance of the present coating film are more excellent. When the Mw of the fluoropolymer is 75,000 or less, the surface smoothness of the coating film is more excellent.

The ratio of Mw to Mn (Mw / Mn) of the fluoropolymer is preferably from 1.0 to 5.0, and more preferably from 2.0 to 4 from the viewpoint that the in-plane uniformity of impact resistance of the present coating film is more excellent. 0.0 is more preferable, and 2.5 to 3.5 is particularly preferable.
Mn and Mw of the fluorinated polymer can be set within the above ranges by adopting a solution polymerization method as a method for producing the fluorinated polymer or by appropriately selecting a polymerization solvent.
Two or more fluoropolymers may be used in combination.

Examples of the method for producing the fluoropolymer include a method in which a monomer (fluoroolefin and monomer 1) is copolymerized in the presence of a solvent and a radical polymerization initiator. In addition, you may use the monomer 2 and the monomer 3 further.
Specific examples of the polymerization method in the method for producing a fluoropolymer include a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among these, the solution polymerization method is preferable from the viewpoint of easily controlling the Mw of the fluoropolymer and the content of the unit 1 within a predetermined range.
The solvent is preferably alcohol, and specific examples thereof include ethanol, butyl alcohol, propanol, and butanol. The alcohol is superior in the solubility of the monomer 1 as compared with a non-polar solvent such as xylene. Therefore, if alcohol is used as the polymerization solvent, the unit 1 can be easily introduced into the fluoropolymer in an appropriate amount.

Specific examples of the radical polymerization initiator include peroxydicarbonate, peroxyester, ketone peroxide, peroxyketal, peroxycarbonate ester, diacyl peroxide, and dialkyl peroxide.
The reaction temperature in the polymerization is usually 0 to 130 ° C., the reaction pressure is usually 0 to 1.0 MPa, and the reaction time is usually 1 to 50 hours.

The paint includes particles containing a fluoropolymer. The coating material may be composed of only particles containing a fluoropolymer, or may be a mixture of particles containing a fluoropolymer and particles not containing a fluoropolymer. The average particle diameter of the particles contained in the present coating composition is preferably from 1 to 100 μm, particularly preferably from 25 to 50 μm.
When the average particle size is 1 μm or more, the cohesiveness of the fluoropolymer is reduced, and the powder is easily coated uniformly during powder coating. Further, when the average particle size is 100 μm or less, the surface smoothness of the present coating film is more excellent, and the appearance of the present coating film is good.
Particles containing a fluorine-containing polymer, for example, obtained by the above-described method for producing a fluorine-containing polymer, from a solution containing a fluorine-containing polymer and a solvent, the solvent is distilled off, and then the remaining solid is pulverized. Can be manufactured.

  The curing agent contained in the present coating composition is preferably a compound having two or more epoxy groups, carbodiimide groups, oxazoline groups, or β-hydroxyalkylamide groups in one molecule. Since the fluorine-containing polymer has a carboxy group based on the unit 1, if the coating composition contains a curing agent capable of reacting with the carboxy group, the physical properties of the coating film, such as weather resistance, acid resistance, and concealing property, are more improved. improves.

Specific examples of the compound having two or more epoxy groups in one molecule include bisphenol type epoxy compounds (A type, F type, S type, etc.), diphenyl ether type epoxy compounds, hydroquinone type epoxy compounds, naphthalene type epoxy compounds, biphenyl type epoxy compounds Epoxy compound, fluorene type epoxy compound, hydrogenated bisphenol A type epoxy compound, bisphenol A nucleated polyol type epoxy compound, polypropylene glycol type epoxy compound, glycidyl ester type epoxy compound, glycidylamine type epoxy compound, glyoxal type epoxy compound, alicyclic Epoxy compounds, alicyclic polyfunctional epoxy compounds, and heterocyclic epoxy compounds (such as triglycidyl isocyanurate).
Specific examples of the compound having two or more epoxy groups in one molecule include triglycidyl isocyanurate (hereinafter referred to as “TGIC”), “TM239” in which a methylene group is introduced into a glycidyl group portion of TGIC (Nissan Chemical Industries, Ltd. "TEPIC-SP" (manufactured by Nissan Chemical Industries, Ltd.), an epoxy compound having a triazine skeleton, and "PT-910" (manufactured by HUNTSMAN), which is a mixture of glycidyl trimellitate and glycidyl terephthalate. No.

  Specific examples of the compound having two or more carbodiimide groups in one molecule include alicyclic carbodiimides, aliphatic carbodiimides, aromatic carbodiimides, and multimers and modified products thereof.

Specific examples of the compound having two or more oxazoline groups in one molecule include an addition-polymerizable oxazoline having a 2-oxazoline group and a polymer of the addition-polymerizable oxazoline.
Specific examples of the compound having two or more oxazoline groups in one molecule include Nippon Shokubai's Epocros WS-500, WS-700, K-2010, K-2020, and K-2030 (all trade names). No.

  Specific examples of the compound having two or more β-hydroxyalkylamide groups in one molecule include N, N, N ′, N′-tetrakis- (2-hydroxyethyl) -adipamide (PrimidXL-552, manufactured by EMS). , N, N, N ', N'-tetrakis- (2-hydroxypropyl) -adipamide (Primid QM 1260, manufactured by EMS).

Two or more curing agents may be used in combination.
The content of the curing agent is preferably 0.01 to 100 parts by mass, more preferably 0.1 to 50 parts by mass, and particularly preferably 1 to 20 parts by mass, based on 100 parts by mass of the fluoropolymer in the present coating composition. preferable. When the content of the curing agent is 0.01 parts by mass or more, the flexibility of the present coating film is more excellent. When the content of the curing agent is 100 parts by mass or less, the impact resistance of the present coating film is more excellent.

The specific curing catalyst is an organic phosphorus compound having one or more phosphorus atoms and 12 or more carbon atoms, and is a compound that promotes a curing reaction when a curing agent is used.
The number of phosphorus atoms in the specific curing catalyst is preferably 5 or less, more preferably 2 or less, and particularly preferably 1.
The number of carbon atoms in the specific curing catalyst is preferably from 12 to 60, and particularly preferably from 18 to 30, from the viewpoint that the impact resistance and the in-plane uniformity of impact resistance of the coating film are more excellent.

  The specific curing catalyst is preferably a compound containing no oxygen atom. Thereby, the affinity between the specific curing catalyst and the fluoropolymer is further improved, and thus the impact resistance and the in-plane uniformity of the impact resistance of the present coating film are further improved.

As the specific curing catalyst, a phosphine or phosphonium salt is preferable, and a phosphonium salt is particularly preferable.
The specific curing catalyst is represented by the following formula 1 (hereinafter, also referred to as “compound 1”) and the following formula 2 from the viewpoint of further improving the affinity between the specific curing catalyst and the fluoropolymer. Preferably, the compound is at least one selected from the group consisting of a compound represented by the following formula (hereinafter, also referred to as “compound 2”) and a compound represented by the following formula 3 (hereinafter, also referred to as “compound 3”). Compounds 1 to 3 may be used in combination of two or more.
The specific curing catalyst preferably contains Compound 2, and particularly preferably Compound 2, from the viewpoint that the impact resistance of the coating film and the in-plane uniformity of impact resistance are more excellent. In particular, the present coating composition is a fluorine-containing polymer containing a unit 2 in which Z ² is an alkyl group having 4 to 8 carbon atoms (more preferably, 6 to 8 carbon atoms) represented by the formula —C (Z ²¹ ) _3. And the compound 2, the affinity between the specific curing catalyst and the fluorinated polymer is excellent, and the impact resistance and the in-plane uniformity of the impact resistance of the coating film are more excellent.

^{(R 11 R 12 R 13)} P Equation 1
^{(R 21 R 22 R 23 R} 24) P + X - wherein 2
(R ³¹¹ R ³¹² R ³¹³ R ³¹⁴ ) P ⁺ B ⁻ (R ³²¹ R ³²² R ³²³ R ³²⁴ ) Formula 3
The symbols in the formula represent the following meanings.
R ^{11 to} R ¹³ , R ^{21 to} R ²⁴ , R ^{311 to} R ³¹⁴ and R ^{321 to} R ³²⁴ each independently represent an alkyl group having 2 or more carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, and 6 carbon atoms. A cycloalkylalkyl group having 10 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or an aralkyl group having 7 to 12 carbon atoms.
However, the total of carbon atoms in R ^{11 to} R ¹³ and the total of carbon atoms in R ^{21 to} R ²⁴ are each 12 or more, preferably 12 to 30, and particularly preferably 16 to 24. The total number of carbon atoms in R ^{311 to} R ³¹⁴ and R ^{321 to} R ³²⁴ is 16 or more, preferably 16 to 60, and particularly preferably 18 to 50.
X ^{- is, Cl -, Br -, I} -, (SCN) - or {N _(CN) 2} ^- and is, Cl ^- or Br ^- is preferred.
Note that P is a phosphorus atom and B is a boron atom.

The carbon number of the alkyl group having 2 or more carbon atoms is preferably 2 to 10, more preferably 2 to 6. When the alkyl group has 3 or more carbon atoms, the alkyl group may be linear or branched.
The cycloalkyl group having 6 to 10 carbon atoms is preferably a cyclohexyl group.
The cycloalkylalkyl group having 6 to 10 carbon atoms is preferably a cyclohexylmethyl group.
The aralkyl group having 7 to 12 carbon atoms is preferably a benzyl group.
The aryl group having 6 to 10 carbon atoms is preferably a phenyl group or a naphthyl group, and particularly preferably a phenyl group.
In addition, the hydrogen atom of a cycloalkyl group, a cycloalkylalkyl group, an aryl group, or an aralkyl group may be substituted with an alkyl group. In this case, the carbon number of the alkyl group as the substituent is not included in the carbon number of the cycloalkyl group or the aryl group.

Specific examples of compound 1 include triphenylphosphine, triparatolylphosphine, diphenylcyclohexylphosphine, and tricyclohexylphosphine.
Specific examples of compound 2 include tetraphenylphosphonium bromide, n-butyltriphenylphosphonium bromide, tetrabutylphosphonium bromide, ethyltriphenylphosphonium bromide, and benzyltriphenylphosphonium chloride. Among these, ethyltriphenylphosphonium bromide is preferred from the viewpoint of more excellent impact resistance and impact resistance in-plane uniformity of the present coating film.
Specific examples of compound 3 include tetraphenylphosphonium tetra-p-tolylborate and tetraphenylphosphonium tetraphenylborate.

Two or more specific curing catalysts may be used in combination.
The content of the specific curing catalyst is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 1 part by mass, and more preferably 0.1 to 0.1 part by mass, based on 100 parts by mass of the fluoropolymer in the present coating composition. 5 parts by weight are particularly preferred. Further, the content of the specific curing catalyst is preferably 0.01 to 10 mmol, more preferably 0.05 to 1 mmol, and particularly preferably 0.1 to 0.4 mmol based on 100 parts by mass of the fluoropolymer. When the content of the specific curing catalyst is within the above range, curing of the present coating film is suitably promoted, and impact resistance and impact resistance in-plane uniformity are more excellent.

The paint may include a resin having no fluorine atom (hereinafter, also referred to as “non-fluorine resin”).
When the present coating material contains a non-fluorine resin, the non-fluorine resin on the substrate side, from the viewpoint of easily obtaining a coating film in which the fluoropolymer is disposed on the coating film surface side, from the viewpoint of the SP value of the fluoropolymer, The difference from the SP value of the non-fluororesin is preferably 0.4 to 16 (J / cm ³ ) ^{1/2 in} absolute value.
When the present coating composition contains a non-fluorinated resin, the mass ratio of the fluoropolymer to the non-fluorinated resin in the present coating composition (mass of the fluoropolymer / mass of the non-fluorinated resin) is preferably 0.30 to 3.5. Preferably, 0.35-3.0 is more preferable.
Specific examples of the non-fluorine resin include alkyd resin, amino alkyd resin, polyester resin, epoxy resin, urethane resin, epoxy polyester resin, polyvinyl acetate resin, (meth) acrylic resin, vinyl chloride resin, phenol resin, and modified polyester resin. , Acrylic silicone resin and silicone resin.

As the non-fluorinated resin, a polyester resin, a (meth) acrylic resin, an epoxy resin or a urethane resin is preferable, and a polyester resin, a (meth) acrylic resin or an epoxy resin is preferable. A polyester resin or a (meth) acrylic resin is preferred from the viewpoint that the fluorine-containing polymer is hardly mixed into the layer mainly composed of the fluororesin.
Specific examples of the polyester resin include “CRYLCOAT (trade name) 4642-3”, “CRYLCOAT (trade name) 4890-0”, and “CRYLCOAT (trade name) 4842-3” manufactured by Daicel Ornex Co., Ltd. "Yupika coat (trade name) GV-740", "Yupika coat (trade name) GV-175", and "Uralac (trade name) 1680" manufactured by DSM. .

  Specific examples of the (meth) acrylic resin include “FINEDIC (trade name) A-249”, “FINEDIC (trade name) A-251”, and “FINEDIC (trade name) A-266” manufactured by DIC. "Almatex (trade name) PD6200" and "Almatex (trade name) PD7310" manufactured by Mitsui Chemicals, Inc., and "Sanpex PA-55" manufactured by Sanyo Chemical Industries.

  Specific examples of the epoxy resin include “Epicoat (trade name) 1001”, “Epicoat (trade name) 1002”, “Epicoat (trade name) 4004P” manufactured by Mitsubishi Chemical Corporation, and “Epiclon (trade name)” manufactured by DIC Corporation. 1050 "," Epiclon (trade name) 3050 "," Epototo (trade name) YD-012 "," Epototo (trade name) YD-014 ", manufactured by Nippon Steel & Sumitomo Metal Corporation," Denacol (trade name, manufactured by Nagase ChemteX Corporation) " EX-711 "and" EHPE3150 "manufactured by Daicel Corporation.

  The urethane resin is a mixture of a polyol (acrylic polyol, polyester polyol, polyether polyol, propylene glycol, etc.) and an isocyanate compound, or a resin obtained by reacting the mixture. As the urethane resin, a resin obtained by reacting a mixture of a powdered polyol (acrylic polyol, polyester polyol, polyether polyol) and a powdered isocyanate is preferable.

  The paint may include additives. The additive is a component other than the above-described fluoropolymer, curing agent, specific curing catalyst, and non-fluorinated resin. Specific examples of additives include pigments, ultraviolet absorbers (various organic ultraviolet absorbers, inorganic ultraviolet absorbers, etc.), light stabilizers (hindered amine light stabilizers, etc.), matting agents (ultrafine synthetic silica, etc.) , Leveling agents, surface conditioners (to improve the surface smoothness of the coating), degassing agents, plasticizers, fillers, heat stabilizers, thickeners, dispersants, antistatic agents, rust inhibitors, Examples include a silane coupling agent, an antifouling agent, and a stain-reducing agent.

Examples of the pigment that can be included in the present composition as an additive include a rust preventive pigment, an extender pigment, and a coloring pigment.
Specific examples of the rust preventive pigment include zinc cyanamide, zinc oxide, zinc phosphate, calcium magnesium phosphate, zinc molybdate, barium borate, and zinc cyanamide zinc.
Specific examples of the extender include talc, barium sulfate, mica, and calcium carbonate.

Specific examples of the coloring pigment include quinacridone, diketopyrrolopyrrole, isoindolinone, indanthrone, perylene, perinone, anthraquinone, dioxazine, benzimidazolone, triphenylmethanequinophthalone, anthrapyrimidine, graphite, phthalocyanine, and halogenated. Examples include phthalocyanine, azo pigments (azomethine metal complex, condensed azo, etc.), titanium oxide, carbon black, iron oxide, copper phthalocyanine, and condensed polycyclic pigments.
Examples of the coloring pigments include bright pigments. Specific examples thereof include metal particles (metals such as aluminum, zinc, copper, bronze, nickel, titanium, and stainless steel and alloys thereof), mica particles (mica powder), Examples include pearl particles, graphite particles, glass flakes, and scale-like iron oxide particles.
When the present paint contains a pigment, the content of the pigment is preferably more than 0% by mass and 40% by mass or less based on the total mass of the present paint.

The following method is mentioned as a method for producing the present paint.
First, a fluorine-containing polymer, a curing agent, a specific curing catalyst, and, if necessary, other components (non-fluorine resin and other additives) are melt-kneaded at 80 to 130 ° C. to obtain a melt-kneaded product. obtain. Next, the obtained melt-kneaded material is cooled to obtain a solidified melt-kneaded material. Then, the solidified melt-kneaded material is pulverized and classified to obtain the present coating material having a desired particle size.

The substrate with a coating film of the present invention has a substrate and a coating film formed on the substrate with the coating material.
Specific examples of the material of the substrate include an inorganic substance, an organic substance, and an organic-inorganic composite material.
Specific examples of the inorganic substance include concrete, natural stone, glass, and metal (iron, stainless steel, aluminum, copper, brass, titanium, and the like).
Specific examples of the organic substance include plastic, rubber, adhesive, and wood.
Specific examples of the organic-inorganic composite include fiber-reinforced plastic, resin-reinforced concrete, fiber-reinforced concrete, and the like.
In addition, a substrate that has been subjected to a known surface treatment (for example, chemical conversion treatment) may be used as the substrate. Further, a resin layer (polyester resin, acrylic resin, or the like) may be formed on the surface of the base material.

Among the above, the substrate is preferably a metal, and more preferably aluminum. The aluminum base material has excellent anticorrosion properties, is lightweight, and is suitable for building materials such as exterior members.
The shape and size of the substrate are not particularly limited.
Specific examples of the base material include a building panel such as a composite panel, a curtain wall panel, a curtain wall frame and a window frame, an automobile member such as a tire wheel, a construction machine, and a motorcycle frame.

The thickness of the present coating film is preferably from 20 to 1000 μm, particularly preferably from 20 to 500 μm. For applications such as members for high-rise buildings such as aluminum curtain walls, 20 to 90 μm is preferable. For applications requiring high weather resistance, such as outdoor units of air conditioners, signal poles, and signs installed along the coast, 100 to 200 μm is preferable.
The gel fraction of the present coating film is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. The upper limit of the gel fraction is usually 100%. When the gel fraction of the present coating film is 80% or more, the present coating film is sufficiently cured, and the present coating film is excellent in impact resistance.

  In the method for producing a coated substrate according to the present invention, the present coating composition is applied to a substrate to form a powder coating layer, and the powder coating layer is heat-treated to form the present coating layer on the substrate. Is preferred.

The powder coating layer is formed by a coating method such as an electrostatic coating method, an electrostatic spraying method, an electrostatic immersion method, a spraying method, a fluid immersion method, a spraying method, a spraying method, a thermal spraying method, or a plasma spraying method. Is preferably applied on a substrate. The electrostatic coating method using a powder coating gun is preferable from the viewpoint that the surface smoothness and the concealing property of the present coating film are more excellent.
Specific examples of the powder coating gun include a corona charging type coating gun and a friction charging type coating gun. The corona charging type coating gun is a coating gun which sprays a powder coating by corona discharge treatment. The triboelectric coating gun is a coating gun that sprays a powder coating by triboelectric treatment.

When heat-treating the powder coating layer, it is preferable to heat the powder coating layer on the base material to form a molten film made of a powder coating melt on the base material. The formation of the molten film may be performed simultaneously with the formation of the powder coating layer on the base material, or may be performed separately after the formation of the powder coating layer.
The heating temperature (hereinafter, also referred to as “baking temperature”) and the heating maintaining time (hereinafter, also referred to as “baking time”) for heating and melting the present coating material and maintaining the molten state for a predetermined time are determined by the present invention. It is appropriately set according to the type and composition of the raw material components of the paint, the desired film thickness of the present coating film, and the like.

For example, the carboxy group of the fluoropolymer in the present coating material reacts with the curing agent to cure the present coating film.
The baking temperature is preferably from 120 to 200C, more preferably from 140 to 180C. The baking time is usually 2 to 60 minutes.
It is preferable to cool the molten film formed on the substrate to 20 to 25 ° C. to form the present coating film. Cooling may be rapid cooling or slow cooling. Slow cooling is preferred from the viewpoint of more excellent substrate adhesion of the present coating film.

  Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples. In addition, the compounding quantity of each component in the table | surface mentioned later shows a mass reference | standard. Examples 1 to 5 are Examples, and Examples 6 to 9 are Comparative Examples.

<Abbreviations of used ingredients>
· Fluorinated polymer 1: for all units fluorinated polymer 1 comprises, CF 2 ₌ units based on CFCl, units based on pivalic acid vinyl ester, 40 mole% of units based on 10-undecylenic acid in this order, Polymer containing 51 mol% and 9 mol% (Tg: 54.0 ° C., acid value: 32 mgKOH / g, Mw: 32,000)
· Fluorinated polymer 2: for all units fluorinated polymer 2 includes, units based on CF 2 ₌ CFCl, units based on pivalic acid vinyl esters, units based on vinyl neononanoate ester, based on the 10-undecylenic acid Polymer containing 42 mol%, 39 mol%, 10 mol%, and 9 mol% of units in this order (Tg: 50.5 ° C., acid value: 34 mgKOH / g, Mw: 36,000)
Curing agent 1: Compound having two or more epoxy groups in one molecule (PT-910 (trade name) manufactured by HUNTSMAN)
Curing agent 2: Compound having two or more β-hydroxyalkylamide groups in one molecule (manufactured by EMS, Primid XL-552 (trade name))
-Surface conditioner: BYK-360P (trade name) manufactured by BYK-Chemie
-Degassing agent: benzoin Pigment: titanium oxide pigment (manufactured by DuPont, Ti-Pure R960 (trade name), titanium oxide content: 89% by mass)
Specific curing catalyst 1: Ethyl triphenylphosphonium bromide Specific curing catalyst 2: Triphenylphosphine Specific curing catalyst 3: Triparatolyl phosphine Curing catalyst 4: Methyl acid phosphate Curing catalyst 5: Triethylenediamine Curing catalyst 6: Para Toluenesulfonic acid / curing catalyst 7: dibutyltin dilaurate

(Manufacture of powder paint)
The components described in Table 1 were mixed for about 10 to 30 minutes using a high-speed mixer (manufactured by Yuzaki Co., Ltd.), and then mixed using a twin-screw extruder (a 16 mm extruder manufactured by Thermo Prism). Melt kneading was performed at a barrel setting temperature of ° C to obtain a melt. After cooling the melt, it was pulverized at 25 ° C. using a pulverizer (manufactured by FRITSCH, product name: Rotor Speed Mill P14) to obtain a powdery pulverized material, and classified by 150 mesh to obtain an average particle. Each powder coating having a diameter of about 40 μm was obtained.

(Production of coating film)
Each of the obtained powder coatings was subjected to electrostatic coating using an electrostatic coating machine (manufactured by Onoda Cement Co., Ltd., GX3600C) on one surface of an aluminum plate (substrate) that had been subjected to a chromate treatment. For 20 minutes to obtain a powder coating molten film. The melted film was allowed to cool to room temperature to obtain an aluminum plate with a coating having a thickness of 55 to 65 μm, and the obtained aluminum plate with a coating was evaluated as a test piece. Details are shown in Table 1.

(Evaluation)
<Impact resistance of coating film>
It was determined by a DuPont impact test (JIS K 5600-5-3). Using a DuPont impact tester, a weight was dropped on the coating surface of the test piece, and the presence or absence of cracks or cracks on the coating surface was observed.
S: No crack or crack occurs even when dropped from a height of 60 cm or more.
A: If it falls from a height of 50 cm or more and less than 60 cm, no crack or crack occurs.
B: If it falls from a height of 20 cm or more and less than 50 cm, no crack or crack occurs.
C: Cracks and cracks occur even when dropped from a height of less than 20 cm.

<In-plane uniformity of impact resistance of coating film>
When the impact resistance was evaluated at any five points of the coating film on the test piece, the variation in the height at which the coating film surface cracked or cracked was evaluated as follows.
A: The standard deviation of the measured values at five points is 2.0 or less.
B: The standard deviation of the measured values at 5 points is more than 2.0.

  As shown in Table 1, it was confirmed that a powder coating containing a specific curing catalyst could be used to form a coating film having excellent impact resistance and impact resistance in-plane uniformity.

Claims (9)

A fluorine-containing polymer containing a unit based on a fluoroolefin and a unit having a carboxy group, a curing agent, and a powder coating containing a curing catalyst,
A powder coating, wherein the curing catalyst is an organic phosphorus compound having at least one phosphorus atom and at least 12 carbon atoms.   The powder coating according to claim 1, wherein the curing catalyst is a compound containing no oxygen atom.   The powder coating according to claim 1, wherein the curing catalyst is a phosphine or a phosphonium salt. The powder coating according to any one of claims 1 to 3, wherein the curing catalyst is at least one selected from the group consisting of compounds represented by the following formulas 1, 2, and 3.
^{(R 11 R 12 R 13)} P Equation 1
^{(R 21 R 22 R 23 R} 24) P + X - wherein 2
(R ³¹¹ R ³¹² R ³¹³ R ³¹⁴ ) P ⁺ B ⁻ (R ³²¹ R ³²² R ³²³ R ³²⁴ ) Formula 3
The symbols in the formula represent the following meanings.
R ^{11 to} R ¹³ , R ^{21 to} R ²⁴ , R ^{311 to} R ³¹⁴ and R ^{321 to} R ³²⁴ each independently represent an alkyl group having 2 or more carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, and 6 carbon atoms. A cycloalkylalkyl group having 10 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or an aralkyl group having 7 to 12 carbon atoms. However, the total of the carbon atoms in R ^{11 to} R ¹³ and the total of the carbon atoms in R ^{21 to} R ²⁴ are each 12 or more. The total of the carbon atoms in R ^{311 to} R ³¹⁴ and R ^{321 to} R ³²⁴ is 16 or more.
X ^{- is, Cl -, Br -, I} -, (SCN) - or {N _(CN) 2} ^- a.   The powder coating according to any one of claims 1 to 4, wherein the content of the unit having a carboxy group is 3 to 30 mol% with respect to all units contained in the fluoropolymer.   The powder coating according to any one of claims 1 to 5, wherein the curing agent is a compound having two or more epoxy groups, carbodiimide groups, oxazoline groups, or β-hydroxyalkylamide groups in one molecule.   The curing agent according to any one of claims 1 to 6, wherein the curing agent is contained in an amount of 1 to 20 parts by mass, and the curing catalyst is contained in an amount of 0.01 to 10 parts by mass with respect to 100 parts by mass of the fluoropolymer. Powder coating as described.   A powder coating layer is formed by applying the powder coating composition according to any one of claims 1 to 7 on a substrate, and the powder coating layer is heat-treated to form a coating film on the substrate. A method for producing a coated substrate.   It has 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 7, and a gel fraction of the coating film is 80% or more. A substrate with a coating film, characterized in that: