JP2011225674A - Coating composition for surface application used for blade of wind-power generator, and blade of wind-power generator and process for production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition for surface application used for a blade of the wind-power generator which can form a coating film excellent in workability, scratch resistance, and weather resistance on the blade surface of the wind-power generator, and a blade and a process for production thereof.SOLUTION: The coating composition for surface application used for a blade of a wind-power generator contains a fluororesin. The blade of the wind-power generator having a coating film formed on the blade substrate surface from the coating composition for surface application used for the blade of the wind-power generator is also provided. The process for production of the blade is also provided.

Description

  The present invention relates to a coating composition for surface coating used for a blade of a wind power generator, a blade of a wind power generator, and a method for producing the same.

  Wind power generators have been popularized in various places because clean energy can be obtained. Such a wind power generator is generally installed in a place where strong winds blow for a long time, and is often installed especially on a coastline where there are no high buildings or trees in the vicinity. As the wind power generator, for example, there is a wind power generator having a tower body, a tower top rotating part provided on the tower body, and a blade attached to the tower top rotating part via a rotation support part. Can be mentioned. The tower top rotating part rotates in accordance with the direction of the wind so that the blade is directed toward the direction where the wind is blowing. As the blade, for example, a blade in which the surface of a wing-like plate piece made of wood is reinforced with fiber reinforced plastic (FRP) is used. In recent years, wind power generators have become larger, and for example, the height of the tower is several tens of meters.

  The blades of such large wind power generators rotate at a high speed, so that insects and birds are likely to collide with each other, and are easily deteriorated due to lightning strikes, salt damage, and the like. However, the blades of large wind power generators are difficult to repair because they are in a very high place, especially when the wind power generator is installed on the sea. Therefore, in order to reduce the repair work as much as possible, it is desirable that the blade of the wind power generator is provided with a coating film that suppresses damage due to insect and bird collisions, lightning strikes, deterioration due to salt damage, and the like.

  Under such required characteristics, for example, a blade (Patent Document 1) formed with a block copolyestercarbonate protective coating layer on the surface has been proposed.

Special table 2007-523765 gazette

However, the weather resistance of the protective coating layer of Patent Document 1 was not sufficient.
The present invention provides a coating composition for surface coating used for a blade of a wind power generator capable of forming a coating film having excellent workability and excellent scratch resistance and weather resistance as a coating film provided on the blade surface of a wind power generator. For the purpose of provision.
Another object of the present invention is to provide a blade of a wind power generator having a coating film excellent in workability and weather resistance, and a manufacturing method thereof.

The present invention employs the following configuration in order to solve the above problems.
[1] A fluorine-containing copolymer (A) having a repeating unit based on ethylene and a repeating unit based on tetrafluoroethylene, and the fluorine-containing copolymer at a temperature below the melting point of the fluorine-containing copolymer (A) A coating composition for surface coating used for a blade of a wind power generator, comprising a solvent capable of dissolving (A).
[2] The ratio of repeating units based on monomers other than tetrafluoroethylene and ethylene to the total monomer units in the fluorine-containing copolymer (A) is 0.1 to 30 mol%. ] The coating composition for surface application | coating used for the blade of a wind power generator as described in above.
[3] The coating composition for surface coating used for a blade of a wind power generator according to [1] or [2], wherein the fluorine-containing copolymer (A) is a fluorine-containing polymer having a crosslinkable group.
[4] The crosslinkable group is at least one selected from the group consisting of a hydroxy group, a carboxyl group, an acid anhydride group, an acid halide group, an amino group, an epoxy group, an alkoxysilyl group, and an isocyanate group. ] The coating composition for surface application | coating used for the blade of a wind power generator as described in above.
[5] Any of [1] to [4], wherein a solubility index (R) for the fluorinated copolymer (A) based on a Hansen solubility parameter represented by the following formula (1) in the solvent is less than 25 The coating composition for surface coating used for the blade of the wind power generator described in 1.
R = 4 × (δd−15.7) ² + (δp−5.7) ² + (δh−4.3) ² (1)
(In the formula (1), δd, δp, and δh represent a dispersion term, a polar term, and a hydrogen bond term in the Hansen solubility parameter, respectively, and the unit is (MPa) ^1/2 .)
[6] Used for a blade of a wind power generator according to any one of [1] to [5], which contains one or more pigment components (C) selected from the group consisting of rust preventive pigments, colored pigments and extender pigments. A coating composition for surface application.
[7] For surface coating according to any one of [1] to [6], comprising a step of dissolving the fluoropolymer (A) in the solvent at a temperature not higher than the melting point of the fluoropolymer (A). A method for producing a coating composition.
[8] The surface coating composition used for the blade of the wind power generator according to any one of [1] to [6] is applied to the blade substrate surface to form a coating layer, and then the solvent is removed from the coating layer. A method of manufacturing a blade of a wind power generator that forms a coating film.
[9] A blade of a wind power generator having a coating film formed from the coating composition for surface coating used for the blade of the wind power generator according to any one of [1] to [6] on the blade base surface.

The coating composition for coating a blade surface of a wind power generator according to the present invention can form a coating film having excellent workability and excellent scratch resistance and weather resistance as a coating film provided on the blade surface of a wind power generator.
In addition, the blade of the wind power generator of the present invention has a coating film excellent in workability and excellent in scratch resistance and weather resistance.
Moreover, according to the manufacturing method of this invention, the blade of the wind power generator which has a coating film excellent in abrasion resistance and a weather resistance can be manufactured simply.

<Coating composition for surface coating used for blade of wind power generator>
The coating composition for surface coating used for the blade of the wind power generator of the present invention is a coating composition that is applied to the blade surface of the wind power generator to form a coating film, and contains the fluorine-containing copolymer (A). To do. By forming the coating film with the coating composition containing the fluorine-containing copolymer, the weather resistance of the blade of the wind power generator is improved.

  The fluorine-containing copolymer (A) contained in the surface coating composition of the present invention is preferably a polymer having polymer units based on fluoroolefin.

[Fluorine-containing copolymer (A)]
The fluorine-containing copolymer (A) is not particularly limited as long as it is a fluorine-containing copolymer containing a repeating unit based on ethylene and a repeating unit based on tetrafluoroethylene. As an example of such a fluorine-containing copolymer, specifically, a repeating unit based on ethylene and a repeating unit based on tetrafluoroethylene (hereinafter sometimes referred to as “TFE”) are mainly contained in the copolymer. ETFE, which is a repeating unit. Here, in this specification, the term “ETFE” may include a repeating unit based on a comonomer other than TFE and ethylene as a constituent unit of the copolymer. It is used as a general term for fluorine-containing copolymers having repeating units.

  As the fluorine-containing copolymer (A) in the present invention, the molar ratio of the repeating unit based on TFE / the repeating unit based on ethylene is preferably 70/30 to 30/70, more preferably 65/35 to 40/60. The most preferable examples are 60/40 to 40/60.

  In addition, the fluorine-containing copolymer (A) in the present invention includes a repeating unit based on a comonomer other than these in addition to TFE and ethylene in order to add various functions to the obtained copolymer. It is preferable that As a comonomer used with such TFE and ethylene, a monomer having no crosslinkable group (hereinafter referred to as “non-crosslinkable monomer”) and a monomer having a crosslinkable group (hereinafter referred to as “non-crosslinkable monomer”). And “crosslinkable monomer”). The crosslinkable group may contribute to adhesion to the substrate when chemically bonded to the substrate or interacts by hydrogen bonding or the like.

Non-crosslinkable monomers include fluoroethylenes such as CF ₂ = CFCl and CF ₂ = CH ₂ (excluding TFE); CF ₂ = CFCF ₃ , CF ₂ = CHCF ₃ , CH ₂ = CHCF ₃ CF ₃ CF ₂ CH═CH ₂ , CF ₃ CF ₂ CF ₂ CF ₂ CH═CH ₂ , CF ₃ CF ₂ CF ₂ CF═CH ₂ , CF ₃ CF ₂ CF ₂ CF ₂ CF═CH _{2, CF 2 HCF 2 CF 2} CF = polyfluoroalkyl ethylenes CH ₂ carbon atoms, such as having from 2 to 12 fluoroalkyl ^{_{group; R f (OCFXCF 2) m}} OCF = CF 2 ( wherein ^{R f} is A perfluoroalkyl group having 1 to 6 carbon atoms, X represents a fluorine atom or a trifluoromethyl group, and m represents an integer of 0 to 5.) Ters; C3 olefins having 3 carbon atoms such as propylene, C4 olefins having 4 carbon atoms such as butylene and isobutylene, olefins such as 4-methyl-1-pentene, cyclohexene, styrene and α-methylstyrene (however, ethylene Vinyl esters such as vinyl acetate, vinyl lactate, vinyl butyrate, vinyl pivalate, vinyl benzoate; allyl esters such as allyl acetate; methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, tert- Vinyl ethers such as butyl vinyl ether and cyclohexyl vinyl ether; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. (Meth) acrylic acid esters; chloroolefins such as vinyl chloride and vinylidene chloride.

Among these monomers, fluoroolefins, particularly CF ₂ ═CH ₂ is preferable from the viewpoint of improving the solubility of the fluorinated copolymer (A) in a solvent. Further, from the viewpoint of improving the toughness and stress crack resistance of the fluorinated copolymer, polyfluoroalkylethylene, particularly CF ₃ CF ₂ CF ₂ CF ₂ CH═CH ₂ is preferred.
These non-crosslinkable monomers may be used alone or in combination of two or more.

Examples of the crosslinkable group possessed by the crosslinkable monomer include a hydroxy group, a carboxylic acid group, a residue obtained by dehydration condensation of two carboxy groups in one molecule (hereinafter referred to as “acid anhydride group”), and a sulfonic acid group. , Epoxy group, cyano group, carbonate group, isocyanate group, ester group, amide group, aldehyde group, amino group, hydrolyzable silyl group, carbon-carbon double bond, carboxylic acid halide group. The carboxylic acid group is a carboxy group and a salt thereof (—COOM ¹ : M ¹ is a metal atom or an atomic group capable of forming a salt with a carboxylic acid), and the sulfonic acid group is a sulfo group and a salt thereof (—SOSO). ₃ M ² : M ² means a metal atom or atomic group capable of forming a salt with sulfonic acid.
Most preferably, it is at least one selected from the group consisting of a hydroxy group, a carboxylic acid group, an acid anhydride group, and a carboxylic acid halide group.

Examples of the monomer having a hydroxy group include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, 5- Examples include hydroxy group-containing vinyl ethers such as hydroxypentyl vinyl ether and 6-hydroxyhexyl vinyl ether; and hydroxy group-containing allyl ethers such as 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and glycerol monoallyl ether. Among these, hydroxy group-containing vinyl ethers, particularly 4-hydroxybutyl vinyl ether and 2-hydroxyethyl vinyl ether are more preferable in terms of easy availability, excellent polymerization reactivity, and excellent crosslinkability of the crosslinkable group.
Examples of the acid anhydride include itaconic anhydride, maleic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, and the like. Of these, itaconic anhydride is preferred.

As monomers having a carboxyl group, acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid, cinnamic acid, undecylenic acid, 3-allyloxypropionic acid, 3- (2-allyloxyethoxycarbonyl) propionic acid, phthalic acid Unsaturated monocarboxylic acids such as vinyl; unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; unsaturated dicarboxylic acid esters such as itaconic acid monoester, maleic acid monoester and fumaric acid monoester . Examples of the monomer having an epoxy group include monomers having an epoxy group such as glycidyl vinyl ether and glycidyl allyl ether.
Among these, a monomer having a hydroxy group and an acid anhydride are preferable from the viewpoint of obtaining a coating film having high hardness and improving the adhesion to a substrate.
These crosslinkable monomers may be used alone or in combination of two or more. That is, two or more different types of crosslinkable groups may exist in one molecule of the fluorinated copolymer (A).
When the fluorinated copolymer (A) contains a unit based on a crosslinkable monomer, the content is preferably 0 among all the monomer repeating units of the fluorinated copolymer (A). 0.1 to 10 mol%, more preferably 0.1 to 5 mol%.

  When the fluorine-containing copolymer (A) contains a repeating unit based on a comonomer other than TFE and ethylene, the total content thereof is the total amount of the fluorine-containing copolymer (A). Among the body repeating units, it is preferably 0.1 to 30 mol%, more preferably 0.1 to 25 mol%, further preferably 0.1 to 20 mol%, most preferably 0.1. ~ 15 mol%. Depending on the purpose such as further improving the solubility, the upper limit may be 50 mol%, and a repeating unit based on a comonomer other than TFE and ethylene may be contained.

  In the fluorine-containing copolymer (A) used for the surface coating composition of the present invention, when the content of the repeating unit based on a comonomer other than TFE and ethylene is in this range, it is almost only TFE and ethylene. Functions such as high solubility, water repellency, oil repellency, curability and adhesion to a substrate can be imparted without impairing the properties of the constructed ETFE.

  From the viewpoint of the hardness of the coating film obtained from the composition for surface coating and the adhesion to the substrate, the fluorinated copolymer (A) used in the composition for surface coating of the present invention contains the crosslinkable group. It is preferable to have in the main chain or side chain of the molecule. The crosslinkable group may be present at either the molecular end, the side chain or the main chain of the fluorine-containing copolymer (A). Moreover, this crosslinking | crosslinked group may be used individually by 1 type in the fluorine-containing copolymer (A), and 2 or more types may be used together. The type and content of the functional group having adhesiveness to the substrate depends on the type, shape, application, required adhesiveness, adhesion method, functional group introduction method, etc. of the substrate to which the surface coating composition is applied. It is selected appropriately.

  As a method for introducing a crosslinkable group into the fluorinated copolymer (A), (i) other monomers having an adhesive functional group may be used in the polymerization of the fluorinated copolymer (A). (Ii) a method of introducing an adhesive functional group into the molecular terminal of the fluorine-containing copolymer (A) at the time of polymerization using a polymerization initiator, a chain transfer agent, and the like (iii) Examples thereof include a method of grafting a compound (graft compound) having an adhesive functional group and a functional group capable of grafting onto the fluorine-containing copolymer (A). These introduction methods can be used alone or in appropriate combination. In view of durability, the fluorine-containing copolymer (A) produced by at least one of the methods (i) and (ii) is preferable.

  The composition for surface coating of the present invention is a comonomer essential for the production of the fluorine-containing copolymer as the fluorine-containing copolymer (A) having the repeating unit based on ethylene and the repeating unit based on TFE. It is possible to use a copolymer obtained by copolymerizing ethylene and TFE as described above, and other comonomer described above which may optionally be contained, by a usual method. It can also be used. As a commercially available product of such a fluorinated copolymer (A), specifically, Asahi Glass Co., Ltd .: Fluon (registered trademark) ETFE Series, Fluon (registered trademark) LM-ETFE Series, Fluon (registered trademark) LM- ETFE AH Series, Daikin Industries, Ltd .: Neoflon (registered trademark), Dyneon: Dyneon (registered trademark) ETFE, DuPont: Tefzel (registered trademark), and the like.

  In the composition for surface coating of the present invention, one of these fluorine-containing copolymers (A) can be used alone, or two or more thereof can be used in combination.

[solvent]
The composition for surface coating of this invention contains a solvent with the said fluorine-containing copolymer (A). The solvent used in the composition for surface coating of the present invention is a solvent capable of dissolving the fluorine-containing copolymer (A) at a temperature not higher than the melting point of the fluorine-containing copolymer (A). Furthermore, when the fluorine-containing copolymer (A) is precipitated from a solution in which the fluorine-containing copolymer (A) is dissolved in this solvent, the dispersion state can be maintained at least at normal temperature and pressure. Is preferred.

  Examples of the solvent used in the present invention include various solvents within a range that satisfies the above conditions. Here, in order for the solvent to be used to meet the above conditions, the polarity of the solvent is preferably within a specific range. In the present invention, the following method is used in which a solvent that satisfies the above conditions is selected as a solvent having a certain range of polarities based on Hansen solubility parameters.

  The Hansen solubility parameter is obtained by dividing the solubility parameter introduced by Hildebrand into three components of a dispersion term δd, a polar term δp, and a hydrogen bond term δh, and representing it in a three-dimensional space. The dispersion term δd indicates the effect due to the dispersion force, the polar term δp indicates the effect due to the force between the dipoles, and the hydrogen bond term δh indicates the effect due to the hydrogen bond force.

  The definition and calculation of Hansen solubility parameters are described in Charles M. et al. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007).

  In addition, Hansen Solubility Parameters in Practice (HSPiP) can be used to easily estimate Hansen solubility parameters. In the present invention, it is preferable to select a solvent to be used by using the value registered for the database in HSPiP version 3 and the estimated value for the solvent not in the database.

  In general, the Hansen solubility parameter for a particular polymer can be determined by conducting a test to measure the solubility of a sample of the polymer in a number of different solvents in which the Hansen solubility parameter is established. Specifically, a sphere in which all three-dimensional points of the solvent in which the polymer is dissolved among the solvents used in the solubility test are included inside the sphere, and the non-dissolved solvent points are outside the sphere. (Solubility sphere) is found and the center coordinate of the sphere is used as the Hansen solubility parameter of the polymer.

  Here, for example, when the Hansen solubility parameter of another solvent that has not been used for the measurement of the Hansen solubility parameter of the polymer is (δd, δp, δh), the point indicated by the coordinates is the polymer. If it is encapsulated inside the solubility sphere, the solvent is considered to dissolve the polymer. On the other hand, if the coordinate point is outside the solubility sphere of the polymer, it is considered that this solvent cannot dissolve the polymer.

  In the present invention, the Hansen solubility parameter is used to dissolve the fluorine-containing copolymer (A) contained in the surface coating composition at a temperature below its melting point. Based on diisopropyl ketone, which is an optimum solvent for dispersing the polymer (A) as fine particles, a group of solvents at a certain distance from the coordinates (15.7, 5.7, 4.3) which are Hansen solubility parameters. It can be used as a preferred solvent.

That is, R, which is a value based on the Hansen solubility parameter represented by the following formula (1), was used as a solubility index for the fluorine-containing copolymer (A).
R = 4 × (δd−15.7) ² + (δp−5.7) ² + (δh−4.3) ² (1)
(In the formula (1), δd, δp, and δh represent a dispersion term, a polar term, and a hydrogen bond term in the Hansen solubility parameter, respectively, and the unit is (MPa) ^1/2 .)

  The solvent used in the present invention preferably has a solubility index (R) calculated by the above formula (1) of less than 25 using Hansen solubility parameter coordinates (δd, δp, δh) of the solvent, and less than 16. More preferably. A solvent having a Hansen solubility parameter in which R represented by the above formula (1) falls within this range has high affinity with the fluorine-containing copolymer (A), and the solubility and fluorine-containing copolymer (A) are High dispersibility in the case of fine particles.

  Further, in the solvent used in the present invention, the value of R calculated based on the Hansen solubility parameter by the above formula (1), whether it is a solvent composed of one compound or a mixed solvent of two or more compounds, , And can be used as a solubility index for the fluorinated copolymer (A). For example, when a mixed solvent is used, the average Hansen solubility parameter based on the mixing ratio (volume ratio) of the solvent to be used is obtained, and the solubility index (R) can be calculated using the Hansen solubility parameter.

  In addition, the boiling point of the solvent used in the present invention is preferably 210 ° C. or less, and more preferably 180 ° C. or less from the viewpoints of handleability and solvent removability after coating. Further, when the boiling point of the solvent is too low, for example, there is a problem that bubbles are easily generated when the solvent is evaporated and removed after coating the composition (hereinafter also referred to as drying). More preferably, it is 80 ° C. or higher.

  Preferred examples of the solvent that satisfies the above conditions include ketones having 3 to 10 carbon atoms, esters, carbonates, ethers, and the like, and more preferably, ketones and esters having 5 to 9 carbon atoms. . Specific examples include methyl ethyl ketone, 2-pentanone, methyl isopropyl ketone, 2-hexanone, methyl isobutyl ketone, pinacholine, 2-heptanone, 4-heptanone, diisopyrrole ketone, isoamyl methyl ketone, 2-octanone, 2-nonanone. , Diisobutyl ketone, ethyl formate, propyl formate, isopropyl formate, butyl formate, isobutyl formate, sec-butyl formate, t-butyl formate, amyl formate, isoamyl formate, hexyl formate, cyclohexyl formate, heptyl formate, octyl formate, 2-formate 2- Ethylhexyl, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, t-butyl acetate, amyl acetate, isoamyl acetate, hexyl acetate, cyclohexyl acetate, acetic acid Butyl, octyl acetate, 2-ethylhexyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, isobutyl propionate, sec-butyl propionate, t-butyl propionate, amyl propionate, Isoamyl propionate, hexyl propionate, cyclohexyl propionate, heptyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, sec-butyl butyrate, t-butyl butyrate, amyl butyrate, isoamyl butyrate, Hexyl butyrate, cyclohexyl butyrate, methyl isobutyrate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, butyl isobutyrate, isobutyl isobutyrate, sec-butyl isobutyrate, iso T-butyl acid, amyl isobutyrate, isoamyl isobutyrate, hexyl isobutyrate, cyclohexyl isobutyrate, methyl valerate, ethyl valerate, propyl valerate, isopropyl valerate, butyl valerate, isobutyl valerate, sec-butyl valerate , T-butyl valerate, amyl valerate, methyl isovalerate, ethyl isovalerate, propyl isovalerate, isopropyl isovalerate, butyl isovalerate, isobutyl isovalerate, sec-butyl isovalerate, isoyoshi T-butyl herbate, amyl isovalerate, methyl hexanoate, ethyl hexanoate, propyl hexanoate, isopropyl hexanoate, butyl hexanoate, isobutyl hexanoate, sec-butyl hexanoate, t-butyl hexanoate, methyl heptanoate, Ethyl heptanoate, propyl heptanoate, iso-heptanoate Propyl, methyl octoate, ethyl octoate, methyl nonanoate, methyl cyclohexane carboxylate, ethyl cyclohexane carboxylate, propyl cyclohexane carboxylate, isopropyl cyclohexane carboxylate, 2-propoxyethyl acetate, 2-butoxyethyl acetate, 2-pentyl acetate Oxyethyl, 2-hexyloxyethyl acetate, 1-ethoxy-2-acetoxypropane, 1-propoxy-2-acetoxypropane, 1-butoxy-2-acetoxypropane, 1-pentyloxy-2-acetoxypropane, acetic acid 3- Methoxybutyl, 3-ethoxybutyl acetate, 3-propoxybutyl acetate, 3-butoxybutyl acetate, 3-methoxy-3-methylbutyl acetate, 3-ethoxy-3-methylbutyl acetate, 3-propoxy-3-methyl acetate Butyl acetate 4-methoxybutyl acetate 4-ethoxy butyl, acetic acid 4-propoxybutyl, acetic acid 4-butoxybutyl, methyl ethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, tetrahydrofuran and the like. In addition, all of these solvents are solvents in which R calculated from the above formula (1) is less than 25.

Among these, the following compounds can be specifically exemplified as more preferable compounds as the solvent used in the present invention.
Methyl ethyl ketone, 2-pentanone, methyl isopropyl ketone, 2-hexanone, methyl isobutyl ketone, pinacholine, 2-heptanone, 4-heptanone, diisopyrrole ketone, isoamyl methyl ketone, 2-octanone, 2-nonanone, diisobutyl ketone, formic acid Isopropyl, isobutyl formate, sec-butyl formate, t-butyl formate, amyl formate, isoamyl formate, hexyl formate, heptyl formate, octyl formate, 2-ethylhexyl formate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, t-acetate Butyl, amyl acetate, isoamyl acetate, hexyl acetate, cyclohexyl acetate, heptyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, propiate Isobutyl acetate, sec-butyl propionate, t-butyl propionate, amyl propionate, isoamyl propionate, hexyl propionate, cyclohexyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, Sec-butyl butyrate, t-butyl butyrate, amyl butyrate, isoamyl butyrate, methyl isobutyrate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, butyl isobutyrate, isobutyl isobutyrate, sec-butyl isobutyrate, t-isobutyrate Butyl, amyl isobutyrate, isoamyl isobutyrate, methyl valerate, ethyl valerate, propyl valerate, isopropyl valerate, butyl valerate, isobutyl valerate, sec-butyl valerate, t-butyl valerate, methyl isovalerate , Isovaleric acid Propyl isovalerate, isopropyl isovalerate, butyl isovalerate, isobutyl isovalerate, sec-butyl isovalerate, t-butyl isovalerate, methyl hexanoate, ethyl hexanoate, propyl hexanoate, hexanoic acid Isopropyl, methyl heptanoate, ethyl heptanoate, methyl octanoate, methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, propyl cyclohexane carboxylate, isopropyl cyclohexane carboxylate, 2-propoxyethyl acetate, 2-butoxyethyl acetate, 2-pentyl acetate Oxyethyl, 1-ethoxy-2-acetoxypropane, 1-propoxy-2-acetoxypropane, 1-butoxy-2-acetoxypropane, 3-ethoxybutyl acetate, 3-propoxybutyl acetate, 3-methoxy acetate Ci-3-methylbutyl, 3-ethoxy-3-methylbutyl acetate, 4-methoxybutyl acetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate. In addition, all of these solvents are solvents in which R calculated from the above formula (1) is less than 16.

As long as the said solvent is the range which satisfy | fills the conditions of the said invention, it may be used independently or may be used in mixture of 2 or more types. Moreover, as long as it has the said predetermined Hansen solubility parameter, you may mix and use solvents other than the above in the said solvent. Furthermore, as long as the mixed solvent satisfies the above conditions, two or more kinds of solvents other than the above can be mixed and used.
When such a mixed solvent is used as a mixed solvent, the value of the solubility index (R) in the mixed solvent calculated from the Hansen solubility parameter of each solvent constituting the mixed solvent and the mixing ratio thereof is preferably less than 25, more preferably Is prepared by appropriately adjusting the blending amount so as to be less than 16.

[Surface coating composition]
The fluorine-containing copolymer (A) contained in the composition for surface coating of the present invention may be present in a dissolved state, but is preferably present in a dispersed state in a solvent described below. . Here, when the fluorine-containing copolymer (A) is present in a dispersed state, the fluorine-containing copolymer (A) is a fluorine-containing copolymer precipitated from a solution dissolved in a solvent described below. It is preferable that it is a coalescence (A). The fluorine-containing copolymer (A) is dispersed in the solvent in the form of fine particles by being precipitated from a solution dissolved in the solvent. In this case, the average particle diameter of the fine particles of the fluorinated copolymer (A) is preferably in the range of 0.005 to 2 μm as an average particle diameter measured by a small angle X-ray scattering method at 20 ° C. More preferably, it is 0.005 to 1 μm. In the composition for surface coating of the present invention, if the average particle diameter of the fine particles of the fluorinated copolymer (A) is within this range, a uniform coating film having excellent transparency, flatness and adhesion is formed. Can do.

  The content of the fluorine-containing copolymer (A) in the composition for surface coating of the present invention can be appropriately changed according to the film thickness of the target molded product. From the viewpoint of film formability, the content of the fluorine-containing copolymer (A) is preferably 0.05 to 30% by mass, more preferably 0.1 to 20% by mass in the total amount of the composition. When the content is within this range, handling properties such as viscosity, drying speed, and film uniformity are excellent, and a homogeneous coating film made of the fluorinated copolymer (A) can be formed.

  The content of the solvent in the composition for surface coating of the present invention is preferably 70 to 99.95% by mass in the total amount of the composition, from the viewpoint of moldability when a molded product is obtained using this, and 80 to 99. 9 mass% is more preferable. When the content is in this range, the coating composition containing the fluorine-containing copolymer (A) is homogeneous and uniform, and the surface coating composition is excellent in handling at the time of coating in coating film production. Can be.

[Method for producing surface coating composition]
The manufacturing method of the composition for surface coating of this invention is demonstrated below. Specifically, the production method of the present invention is used as a method for producing the surface coating composition of the present invention described above.

The method for producing a composition for surface coating of the present invention preferably includes the following steps (1) and (2).
(1) A fluorine-containing copolymer (A) having a repeating unit based on ethylene and a repeating unit based on tetrafluoroethylene is obtained at a temperature not higher than the melting point of the fluorine-containing copolymer (A). A step of dissolving (A) in a soluble solvent to form a solution (hereinafter referred to as “dissolution step”).
(2) A step of precipitating the fluorine-containing copolymer (A) as fine particles in the solvent in the solution to make the solution a dispersion in which the fine particles are dispersed in the solvent (hereinafter referred to as “precipitation step”). )
(1) Dissolution Step The solvent used in the dissolution step is a solvent that satisfies the above conditions, that is, a solvent that can dissolve this fluorine-containing copolymer at a temperature not higher than the melting point of the fluorine-containing copolymer (A). Further, when the precipitation step is carried out to precipitate the fine particles of the fluorine-containing copolymer (A) from the solution in which the fluorine-containing copolymer is dissolved in this solvent, the solvent used is at least at room temperature and normal pressure. It is preferable that the fluorinated copolymer (A) can be stably dispersed as fine particles.

  The temperature, pressure, stirring, and other conditions in the dissolution step are not particularly limited as long as the fluorine-containing copolymer (A) is dissolved in the solvent, but the temperature conditions in the dissolution step are used. The temperature is preferably lower than the melting point of the fluorinated copolymer (A). Since the melting point of the fluorinated copolymer (A) used in the present invention is the highest and is approximately 275 ° C., the temperature of the step of dissolving it in the solvent is approximately 275 ° C. or less. preferable. The temperature at which the fluorinated copolymer (A) is dissolved in the solvent is more preferably 230 ° C. or less, and particularly preferably 200 ° C. or less. Moreover, as a minimum of the temperature of this melt | dissolution process, 0 degreeC is preferable and 20 degreeC is more preferable. If the temperature of the melting step is less than 0 ° C., a sufficient dissolved state may not be obtained, and if it exceeds 275 ° C., it may not be easily performed when performing actual work.

  In the melting step of the method for producing a composition for surface coating of the present invention, conditions other than temperature are not particularly limited, and the conditions are usually carried out under normal pressure to about 0.5 MPa. It is preferable. Depending on the type of the fluorine-containing copolymer (A) and the solvent, when the boiling point of the solvent is lower than the temperature of the dissolution step, etc., in the pressure vessel, at least naturally occurring pressure or less, preferably 3 MPa or less, more preferably 2 MPa or less. More preferably, there is a method of dissolving under conditions of 1 MPa or less, most preferably under conditions of normal pressure or less, but in general, dissolution can be carried out under conditions of about 0.01 to 1 MPa. .

  The dissolution time depends on the content of the fluorinated copolymer (A) in the surface coating composition of the present invention, the shape of the fluorinated copolymer (A), and the like. The shape of the fluorine-containing copolymer (A) used is preferably in the form of a powder in terms of work efficiency for shortening the dissolution time, but in other shapes such as a pellet because of its availability. It is also possible to use.

  The dissolution means in the dissolution step is not special and may be a general method. For example, the necessary amount of each component to be blended in the composition for surface coating is weighed, preferably a temperature not higher than the melting point of the fluorine-containing copolymer used at 0 ° C. or higher, more preferably 0 to 230 ° C., particularly preferably 20 to 200. What is necessary is just to mix these components uniformly at the temperature of 0 degreeC, and to make it melt | dissolve in the said solvent. In addition, it is preferable in terms of efficiency to carry out the dissolution using a general stirring mixer such as a homomixer, a Henschel mixer, a Banbury mixer, a pressure kneader, a single screw or twin screw extruder. Moreover, when heating is required in the dissolution step, mixing and heating of various raw material components may be performed simultaneously, or after mixing various raw material components, heating may be performed while stirring as necessary.

When dissolving under pressure, an apparatus such as an autoclave with a stirrer can be used. As the shape of the stirring blade, a marine propeller blade, a paddle blade, an anchor blade, a turbine blade, or the like is used. When performing on a small scale, a magnetic stirrer or the like may be used.
As the composition for surface coating of the present invention, a composition containing the fluorinated copolymer (A) in a state of being dissolved in a solvent by a dissolving step can be used without performing a precipitation step.

(2) Precipitation step The fluorine-containing copolymer (A) is precipitated in the solvent from a solution obtained by dissolving the fluorine-containing copolymer (A) obtained in the dissolution step (1) in the solvent. Under conditions, generally, the fluorinated copolymer (A) is precipitated in the solvent by being kept at normal temperature and pressure. Specifically, when the (1) dissolution step is performed under heating, the resulting solution is cooled to a temperature not higher than the temperature at which the fluorinated copolymer (A) precipitates, usually to room temperature. Fine particles of the fluorine-containing copolymer (A) can be precipitated in the solvent. In this case, the cooling method is not particularly limited, and may be slow cooling or rapid cooling.

  In the precipitation step, the fluorine-containing copolymer (A) is usually precipitated as fine particles, and a composition in which the fine particles are dispersed in the solvent is obtained. In addition, the average particle diameter of the fluorine-containing copolymer (A) fine particles precipitated in the precipitation step may be in the range of 0.005 to 2 μm as an average particle diameter measured by a small angle X-ray scattering method at 20 ° C. Preferably, it is 0.005 to 1 μm.

  In the present invention, it is preferable to use a composition containing the fluorine-containing copolymer (A) in a dispersed state as fine particles as the surface coating composition.

[Other optional ingredients]
The composition for surface coating in the present invention can contain other optional components as needed within a range not impairing the effects of the present invention. Examples of such optional components include a curing agent, a curing accelerator, an adhesion improver, a surface conditioner, an antioxidant, a light stabilizer, an ultraviolet absorber, a crosslinking agent, a lubricant, a plasticizer, a thickener, and a mat. Various additives such as an agent, a dispersion stabilizer, a filler (filler), a reinforcing agent, a leveling agent, a pigment, a dye, a flame retardant, an antistatic agent, and other resins. Moreover, as content of these arbitrary components which do not impair the effect of this invention, content of 30 mass% or less can be mentioned with respect to the surface coating composition whole quantity.
Since the composition for surface coating in the present invention includes a step of dissolving the fluorine-containing copolymer (A) in a solvent to form a solution, the additive is necessary as compared with a method such as melt kneading. Accordingly, it is possible to mix in a large amount and uniformly. In addition, if a composition for surface coating containing such an additive at a high concentration is used, it is possible to exhibit a necessary function with a thinner film thickness. Therefore, the fluorine-containing copolymer (A) The amount of use can be reduced.

It is preferable to add a curing agent to cure the paint, but depending on the type of the crosslinkable group, it can be cured only by drying, so there is a case where addition of the curing agent is unnecessary. What is necessary is just to select a hardening | curing agent suitably with the crosslinkable group contained in a fluorine-containing copolymer (A).
For example, when the crosslinkable group is a hydroxy group, an isocyanate curing agent, a melamine resin, a silicate compound, an isocyanate-containing silane compound, or the like is selected. When a carboxyl group is selected, an amino curing agent or an epoxy curing agent is selected. In the case of an amino group, a carbonyl-containing curing agent, an epoxy curing agent, and an acid anhydride curing agent are selected. In the case of an epoxy group, a carboxyl group is selected. In the case of an isocyanate group, a hydroxy group is selected. . Crosslinkable groups that do not require a curing agent include hydrolyzable silyl groups.

In particular, when the fluorine-containing copolymer has a hydroxy group, a polyisocyanate is preferable as the curing agent, and among them, a non-yellowing polyisocyanate or a modified product of a non-yellowing polyisocyanate is more preferable.
As the non-yellowing modified polyisocyanate, IPDI (isophorone diisocyanate), HMDI (hexamethylene diisocyanate), HDI (hexane diisocyanate), or a modified product thereof is preferable.
Examples of modified products include epsilon caprolactam (E-CAP), methyl ethyl ketone oxime (MEK-OX), methyl isobutyl ketone oxime (MIBK-OX), pyralidine or triazine (TA), blocked isocyanate groups, and polyisocyanates A uretdione bond and the like are preferably coupled.
As the curing accelerator, for example, tin-based, other metal-based, organic acid-based, and amino-based curing accelerators can be used.

  Although an adhesive improvement agent is not specifically limited, For example, a silane coupling agent can be used suitably. Examples of the silane coupling agent include aminoalkyls such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and ureidopropyltriethoxysilane. Silanes; Unsaturated alkylsilanes such as vinyltriethoxysilane, vinyltrimethoxysilane, 3- (trimethoxysilyl) propyl (meth) acrylate, 3- (triethoxysilyl) propyl (meth) acrylate; 2- Epoxysilanes such as (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane; 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, methyltriethoxy Orchids, etc. methyltrimethoxysilane is preferred.

The coating composition for surface coating of the present invention preferably contains a pigment component for the purpose of rust prevention, coloring, reinforcement and the like. The pigment component is preferably at least one pigment selected from the group consisting of rust preventive pigments, colored pigments and extender pigments.
The rust preventive pigment is a pigment for preventing the blade base from being corroded or altered. Lead-free rust-proof pigments with low environmental impact are preferred.
Examples of lead-free rust preventive pigments include cyanamide zinc, zinc oxide, zinc phosphate, calcium magnesium phosphate, zinc molybdate, barium borate, and calcium cyanamide zinc.
The color pigment is a pigment for coloring the coating film. Examples of the color pigment include titanium oxide, carbon black, and iron oxide.
The extender pigment is a pigment for improving the hardness of the coating film and increasing the thickness of the coating film. Examples of extender pigments include talc, barium sulfate, mica, and calcium carbonate.

The content of the pigment component in the coating composition for surface coating of the present invention is 100 parts by mass with respect to the total solid content of the coating composition at the time of use (including the curing agent component when a curing agent component is used). 50-500 mass parts is preferable, and 100-400 mass parts is more preferable. When the content of the pigment component is 50 parts by mass or more, the function of the pigment component is easily obtained. When the content of the pigment component is 500 parts by mass or less, the coating film is hardly cracked or damaged by impacts such as insect and bird collisions, and the weather resistance of the coating film is improved.
Among pigments, titanium oxide is known to decompose and deteriorate a coating film containing a pigment by photocatalysis. Therefore, as titanium oxide, in order from the inside, particles containing titanium oxide, a first coating layer containing cerium oxide covering the outside of the particles, and a second coating containing silicon oxide covering the outside of the first coating layer It is preferable to use a composite particle including a layer.
The composite particle may have another coating layer inside or outside the cerium oxide coating layer and the silicon oxide coating layer. For example, it is preferable to have a silicon oxide coating layer between a particle containing titanium oxide and a first coating layer containing cerium oxide covering the outside of the particle.

In addition, it is preferable to add a metal compound different from the metal compound constituting the coating layer to the outermost coating layer of the composite particle according to the required characteristics of the composite particle. For example, it is preferable to add zirconia for the purpose of hardening and preventing the pigment from collapsing, or alumina for the purpose of improving the hydrophilicity and improving the dispersibility. When the outermost layer of the composite particles is the second layer containing the silicon oxide, it is preferable to add the zirconia and alumina to the silicon oxide. The amount in the case where a metal compound different from the metal compound constituting the coating layer is added to the coating layer is preferably 10 to 50% by mass with respect to the total mass of the metal compound constituting the coating layer, and 20 to 30 masses. % Is more preferable.
As the leveling agent, for example, polyether-modified polydimethylsiloxane, polyether-modified siloxane and the like are preferable.

Since a wind power generator is used outdoors for a long time with strong ultraviolet rays, it is important to take measures against deterioration of the blades due to ultraviolet rays. Therefore, it is preferable to add an ultraviolet absorber to the coating material containing the fluorinated copolymer (A) as an essential component to impart an ultraviolet absorbing function to the coating film.
As the ultraviolet absorber, both organic and inorganic ultraviolet absorbers can be used. Examples of organic compound systems include salicylic acid ester systems, benzotriazole systems, benzophenone systems, cyanoacrylate systems, and other external line absorbers, and inorganic systems include filler type inorganic UV absorbers such as titanium oxide, zinc oxide, and cerium oxide. Etc. are preferable.
When titanium oxide is used as the ultraviolet absorber, it is preferable to use titanium oxide as the composite particles.
An ultraviolet absorber may be used individually by 1 type, and may be used in combination of 2 or more type. It is preferable that the quantity of a ultraviolet absorber is 0.1-15 mass% with respect to the solid content total mass of the fluorine-containing copolymer (A) in a coating material. When the amount of the ultraviolet absorber is too small, the effect of improving the light resistance cannot be sufficiently obtained, and when the amount is too large, the effect is saturated.

Examples of the light stabilizer include hindered amine-based light stabilizers and the like. Adekastab LA62, Adekastab LA67 (above, manufactured by Adeka Argus Chemical Co., Ltd., trade name), Tinuvin 292, Tinuvin 144, Tinuvin 123, Tinuvin 440 (above, Ciba Specialty Chemicals, trade name) and the like are preferable.
The light stabilizer may be used alone or in combination of two or more kinds, and may be used in combination with an ultraviolet absorber.
Examples of the thickener include a polyurethane-based associative thickener.
As the matting agent, a conventional inorganic or organic matting agent such as ultrafine powdered synthetic silica can be used.

Other resins include non-fluorinated resins such as acrylic resins, polyester resins, acrylic polyol resins, polyester polyol resins, urethane resins, acrylic silicone resins, silicone resins, alkyd resins, epoxy resins, oxetane resins, amino resins, etc. It is done. The other resin may be a resin having a crosslinkable group and cured by being crosslinked by a curing agent.
When mix | blending other resin with the coating composition for surface coatings of this invention, content of other resin has preferable 1-200 mass parts with respect to 100 mass parts of a fluorine-containing copolymer (A).
The concentration of the fluorine-containing copolymer (A) in the surface coating composition prepared as described above is preferably 1 to 50% by mass with respect to the total mass of the coating material.

  If the coating composition for surface coating of the present invention described above is used, a coating film having excellent scratch resistance and weather resistance can be easily formed as a coating film for protecting a blade of a wind power generator. Furthermore, if a functional group having crosslinkability is introduced into the fluorinated copolymer (A) and a cured coating film layer is formed as a coating film, the acid resistance is improved by the crosslinked structure. It is easy to suppress blade deterioration. In addition, since the cured coating layer also improves water repellency due to the crosslinked structure, it is easy to inhibit the rotation of the blade from being hindered by snow adhesion. Furthermore, since a harder coating film is formed by the crosslinked structure, the scratch resistance is improved, and durability such as heat resistance, water resistance, and moisture resistance is improved.

<Wind generator blade>
Hereinafter, an example of an embodiment of a blade of a wind power generator according to the present invention will be described.
As the blade base, a blade base usually used in a wind power generator can be adopted, and examples thereof include a blade base in which the surface of a wing-like plate piece made of wood is reinforced with fiber reinforced plastic (FRP). The shape and size of the blade base are not particularly limited.

  The coating film is a layer formed on the blade substrate in order to improve the weather resistance and mechanical durability of the blade substrate, and is formed by the above-described coating composition for surface coating of the present invention. The thickness of the coating film is preferably 50 to 150 μm. The coating film is a cured coating formed from a coating composition for surface coating containing the fluorinated copolymer (A) from the viewpoint of improving acid resistance, water repellency, durability, and scratch resistance in addition to weather resistance. A film layer is preferred.

  There may be another layer between the blade substrate and the coating. As another layer, the layer which consists of a silane coupling agent for improving the adhesiveness of the resin layer which consists of alkyd resin, an epoxy resin, an acrylic resin, and a cured coating film layer, etc. are mentioned.

(Production method)
As an example of the method for producing the blade of the wind power generator of the present invention, a method for producing the blade 1 using the coating composition for surface coating containing the fluorine-containing copolymer (A) described above will be described.
As a method for manufacturing a blade, for example, a coating composition for coating a surface is formed by applying a coating composition for surface coating containing at least a fluorinated copolymer (A) to the surface of the blade substrate, thereby forming a coating film comprising a coating film. The method of doing is mentioned.

The coating composition for surface coating can be applied using a brush, roller, spray, flow coater, applicator or the like. What is necessary is just to select suitably the application quantity of the coating composition for surface application | coating so that a dry film thickness may become in the said range. The temperature for thermosetting the coating composition for surface application is preferably from room temperature to 250 ° C.
When the coating composition for surface coating contains a solvent, the solvent is preferably removed by volatilization by heating, decompression or the like before or after curing.

The blade of the wind power generator described above has a coating film excellent in weather resistance, and its construction is easier than the method of attaching a film. Moreover, if the coating film is a cured coating film layer having a cross-linked structure using the fluorine-containing copolymer (A), the acid resistance and water repellency are also improved, deterioration due to acid rain and bird dung, rotation due to snow It becomes easy to suppress the obstruction. Furthermore, if the cured coating layer having the crosslinked structure is used, durability such as heat resistance, water resistance, moisture resistance and the like is improved, and scratch resistance is also improved, so that damage caused by insect and bird collisions is suppressed. Cheap.
In addition, the manufacturing method of the blade of the wind power generator of this invention is not limited to the method mentioned above. For example, when a coating film is not a cured coating film layer, the method of apply | coating the coating composition for surface coating, forming an application layer, and drying and making it a coating film is mentioned.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description.
[Production of Fluorocopolymer Surface Coating Composition (A1)]
<Surface coating composition (A1)>
In a pressure-resistant reactor made of borosilicate glass, ETFE (constituent monomer and molar ratio: tetrafluoroethylene / ethylene / hexafluoropropylene / 3,3,4,4,5,5,6, is used as a fluorine-containing copolymer. 6,6-nonafluoro-1-hexene / itaconic anhydride = 44.6 / 45.6 / 8.1 / 1.3 / 0.4, melting point: 192 ° C., hereinafter referred to as “ETFE1”) 40 g, 37.60 g of diisopropyl ketone (R calculated by the above formula (1) (hereinafter simply referred to as “R”) = 0) was added and heated to 140 ° C. with stirring. It became a solution.

  When the reactor was gradually cooled to room temperature, a surface-coating composition (A1) was obtained as a fluorine-containing copolymer fine particle dispersion (ETFE1 concentration 6% by weight) that was uniform and free of sediment. The average particle size of the fluorine-containing copolymer fine particles was 20 nm as an average particle size measured by a small angle X-ray scattering method at 20 ° C. Further, when this dispersion was diluted to 0.05% by weight and observed with a transmission electron microscope, it was confirmed that the primary particle diameter was 20-30 nm.

This dispersion was applied to a glass substrate by potting at room temperature and air-dried, and then heated and dried on a hot plate at 120 ° C. for 5 minutes to obtain a glass substrate having a ETFE1 thin film formed on the surface. When the obtained thin film was observed with an optical microscope (50 times), it was confirmed to be a uniform and smooth film. Moreover, it was 3 micrometers when the film thickness was measured with the stylus type surface shape measuring device. When the adhesion of the obtained ETFE1 film was evaluated, no peeling was observed.
<Surface coating composition (A2)>
A surface coating composition (A2) was obtained in the same manner as the surface coating composition (A1) except that cyclohexanone (R = 25.6) was used as the solvent.

[Preparation of pigment composition]
<Pigment composition (B1)>
Methyl ethyl ketone dispersion (solid content concentration) of titanium oxide pigment (manufactured by Ishihara Sangyo Co., Ltd., CR97, average particle size: 0.25 μm) to 40 g of the surface coating composition (A1) containing the obtained fluorinated copolymer : 34.2%) 2.50 g, and 40 g of 1 mm diameter glass beads are added, and the mixture is stirred for 2 hours with a paint shaker. After stirring, filtration was performed to remove the glass beads to obtain a pigment composition (B1). This pigment composition (B1) was applied to a polyethylene terephthalate (PET) film by potting at room temperature and air-dried, and then dried by heating on a hot plate at 120 ° C. for 5 minutes to form a thin film of the pigment composition (B1) on the surface. A PET film with a formed was obtained. When the visible light and UV transmittance of the obtained thin film were examined, it was 2% or less over the entire range of 200 to 800 nm.
<Pigment composition (B2)>
A pigment composition (B2) is obtained in the same manner as the pigment composition (B1) except that the surface coating composition (A2) is used in place of the surface coating composition (A1).

[Coating composition for surface application]
<Coating composition for surface application (D1)>
10 g of the surface coating composition (A1) is added to and mixed with 40 g of the pigment composition (B1) to obtain a coating composition (D1) for surface coating.
<Coating composition (D2)>
The coating composition for surface coating except that the pigment composition (B2) is used instead of the pigment composition (B1) and the surface coating composition (A2) is used instead of the surface coating composition (A1). In the same manner as the product D1, a surface coating composition (D2) is obtained.

<Evaluation of coating film (cured coating film layer) formed by coating composition for surface application>
[Example 1]
The coating composition (D1) for surface coating is applied to the surface of the glass substrate so that the film thickness becomes 20 μm, and the coating film is formed by curing in a constant temperature room at 25 ° C. for 1 week. A test plate I-1 is obtained.
In addition, the coating composition (D1) for surface coating was applied to the surface of the chromate-treated aluminum plate so as to have a film thickness of 20 μm, and was cured in a constant temperature room at 25 ° C. for 1 week to form a coating film. As a result, a coated test plate I-2 is obtained.
About the test board I-1 with a coating film, the hardness of a coating film, water resistance, and heat resistance are evaluated. Moreover, the weather resistance test of a coating film is done about the test plate with a coating film I-2.

[Comparative Example 1]
Test plate with coating film II in which a coating film was formed on a glass substrate in the same manner as in Example 1 except that the coating composition for surface coating (D2) was used instead of the coating composition for surface coating (D1). -1 and test plate II-2 with a coating film in which a coating film is formed on the surface of an aluminum plate are obtained.
About the test board II-1 with a coating film, the hardness of a coating film, water resistance, and heat resistance are evaluated. Moreover, the weather resistance test of a coating film is done about the test plate with a coating film II-1.

[Evaluation methods]
(hardness)
The hardness of the coating film is measured by a method based on JIS K 5600-5-4 (1999) and evaluated according to the following criteria.
“◯”: Pencil hardness H or higher “Δ”: Pencil hardness 2B to F
“×”: pencil hardness of 3B or less (water resistance)
The water resistance test of the coating film is performed by a method based on JIS K 5600-6-2 (1999), and evaluated according to the following criteria.
“◯”: The coating film was swollen and no damage was observed.
"X": The coating film was swollen and damaged.

(Heat resistance (1): Thermal decomposition temperature)
Using a differential thermogravimetric simultaneous measurement device TG / DTA220 (manufactured by Seiko Instruments Inc.), thermogravimetric analysis was performed at a temperature rising rate of 10 ° C./min and a nitrogen flow rate of 50 mL / min, and the thermal decomposition temperature of the coating Measure. In addition, let the temperature at the time of the mass of a coating film reduce 5% be thermal decomposition temperature (degreeC). The measurement results are evaluated according to the following criteria.
“◯”: 250 ° C. or higher “Δ”: 150-250 ° C.
“×”: 150 ° C. or less (weather resistance)
Installed test plates I-2 and II-2 with paint film outdoors in Naha City, Okinawa Prefecture, and measured the gloss of the paint film surface immediately before installation and two years later with PG-1M (Gloss meter: Nippon Denshoku Industries Co., Ltd.) ). When the gloss value immediately before installation is 100%, the ratio of the gloss value after 2 years is calculated as the gloss retention (unit:%), and the weather resistance is evaluated according to the following criteria.
“◯”: The gloss retention was 80% or more.
“Δ”: The gloss retention was 60% or more and less than 80%.
"X": The gloss retention was less than 60%.

  As shown in Table 1, the coating film of Example 1 formed with the coating composition for surface coating of the present invention is excellent in scratch resistance. In addition, it has a high thermal decomposition temperature, excellent heat resistance, and excellent water resistance. Furthermore, in the weather resistance test, since the gloss of the aluminum plate on which the coating film is formed is maintained at a high level, it has excellent weather resistance.

  Further, by using the surface coating composition (D1) prepared from the surface coating composition (A1) in which the fine fluorine-containing copolymer is dispersed using diisopropyl ketone, which is a solvent having an optimum R value. The formed coating film of Example 1 was compared with the surface coating composition (D2) prepared from the surface coating composition (A2) prepared using cyclohexanone with R = 25.6 as a solvent. Compared to the coating film of Example 1, the scratch resistance is superior and the heat resistance is also superior.

Claims (9)

  A fluorine-containing copolymer (A) having a repeating unit based on ethylene and a repeating unit based on tetrafluoroethylene, and the fluorine-containing copolymer (A) at a temperature below the melting point of the fluorine-containing copolymer (A) A coating composition for surface coating used for a blade of a wind power generator, which contains a solvent capable of dissolving   The ratio of the repeating unit based on monomers other than tetrafluoroethylene and ethylene to the total monomer units in the fluorine-containing copolymer (A) is 0.1 to 50 mol%. Coating composition for surface coating used for blades of wind power generators.   The coating composition for surface coating used for a blade of a wind power generator according to claim 1 or 2, wherein the fluorinated copolymer (A) is a fluorinated polymer having a crosslinkable group.   4. The crosslinkable group is at least one selected from the group consisting of a hydroxy group, a carboxyl group, an acid anhydride group, an acid halide group, an amino group, an epoxy group, an alkoxysilyl group, and an isocyanate group. Coating composition for surface coating used for blades of wind power generators. The wind power generation according to any one of claims 1 to 4, wherein a solubility index (R) for the fluorine-containing copolymer (A) based on a Hansen solubility parameter represented by the following formula (1) in the solvent is less than 25. A coating composition for surface coating used for a blade of a machine.
R = 4 × (δd−15.7) ² + (δp−5.7) ² + (δh−4.3) ² (1)
(In the formula (1), δd, δp, and δh represent a dispersion term, a polar term, and a hydrogen bond term in the Hansen solubility parameter, respectively, and the unit is (MPa) ^1/2 .)   The coating composition for surface coating used for the blade of the wind power generator in any one of Claims 1-5 containing 1 or more types of pigment components (C) chosen from the group which consists of a rust preventive pigment, a color pigment, and an extender. object.   The production of the coating composition for surface coating according to any one of claims 1 to 6, further comprising a step of dissolving the fluoropolymer (A) in the solvent at a temperature not higher than the melting point of the fluoropolymer (A). Method.   The coating composition for surface coating used for the blade of the wind power generator according to any one of claims 1 to 6 is applied to the blade substrate surface to form a coating layer, and then the solvent is removed from the coating layer to form a coating film. A method of manufacturing a blade of a wind power generator to be formed.   A blade of a wind power generator having a coating film formed from a coating composition for surface coating used for a blade of the wind power generator according to any one of claims 1 to 6 on a blade base surface.