WO2016052111A1 - Coated body - Google Patents

Abstract

The present invention addresses the problem of providing a coated body which has excellent weather resistance, wear resistance and adherability. The present invention is a coated body which is provided with a base and a coating film that is arranged on the surface of the base, and which is characterized in that: the coating film is formed from a coating material composition that contains at least a fluororesin and a resin other than the fluororesin; if the ratio of fluorine atoms in the total mass of fluorine atoms and carbon atoms in the surface of the coating film is defined as a first fluorine concentration (mass%), the first fluorine concentration is 30-50 mass%; and if the film thickness of the coating film is defined as T (μm) and the ratio of fluorine atoms in the total mass of fluorine atoms and carbon atoms at a depth of T/2 (μm) from the surface of the coating film is defined as a second fluorine concentration (mass%), the mass ratio of the second fluorine concentration (A) to the first fluorine concentration (B), namely A/B is from 13/87 to 49/51.

Description

Painted body

The present invention relates to a coated body comprising a substrate and a coating film disposed on the surface of the substrate, and relates to a coated body having excellent weather resistance, wear resistance and adhesion.

In recent years, global environmental problems such as global warming, ozone depletion, and acid rain have been greatly raised, and international countermeasures against environmental pollution have been called out. Has come to be done. Among them, the release of organic solvents (especially volatile organic compounds VOC) into the atmosphere has become a major problem, and the movement to deorganic solvents (especially de-VOCs) is active along with the trend of strengthening VOC regulations in each industry. It has become. In the paint industry, environmentally friendly paints that do not contain VOC at all, do not require exhaust treatment / wastewater treatment, and can be recovered and reused are required as alternatives to conventional organic solvent paints. Expectations are growing.

Under such circumstances, use of a layer-separated powder coating composition containing a fluorine resin having excellent weather resistance and a low-cost polyester resin has been proposed (see, for example, Patent Documents 1 to 3).

JP2011-12119A JP 2012-41383 A JP 2013-76019 A

However, when a layer-separated powder coating composition as described in Patent Documents 1 to 3 is used, a coating film that still has room for improvement in terms of weather resistance is formed, and although weather resistance can be secured, wear resistance It was found that a coating film with room for improvement in terms of property and adhesion was formed.

Therefore, an object of the present invention is to provide a coated body having a base material and a coating film disposed on the surface of the base material, which is excellent in weather resistance, wear resistance and adhesion.

As a result of intensive studies to achieve the above object, the present inventor has found that these layer-separated type powder coating compositions have a composition ratio of resins constituting the fluororesin layer and the polyester resin layer formed after coating. I found a difference.
For example, in the layer-separated type powder coating composition described in Patent Document 2, most of the resin component constituting the fluororesin layer located on the upper side of the coating film is a fluororesin, and the polyester located on the lower side. Most of the resin components constituting the resin layer are polyester resins. About the coating film formed by the layer-separation type powder coating composition described in Patent Document 2, since the composition of the resin component constituting each layer is greatly different, adhesion between each layer is not sufficiently obtained, It has been found that delamination may occur.
On the other hand, the layer-separated type powder coating composition described in Patent Document 3 is a resin component constituting the fluororesin layer as compared with the layer-separating type powder coating composition described in Patent Document 2. The ratio of the polyester resin is high, the ratio of the fluorine resin as the resin component constituting the polyester resin layer is high, and the composition of the resin component constituting each layer is relatively close. However, it has been found that the ratio of the fluororesin constituting the fluororesin layer is not sufficiently high from the viewpoint of weather resistance and wear resistance, and there is room for improvement.

Therefore, in order to solve these technical problems, the present inventor specified the ratio of the fluorine resin on the coating film surface and the ratio of the fluorine resin at a position where the depth from the coating film surface corresponds to half of the film thickness. By adjusting to the range, it was found that a coated body excellent in weather resistance, abrasion resistance and adhesion was obtained, and the present invention was completed.

That is, the coated body of the present invention is a coated body comprising a substrate and a coating film disposed on the surface of the substrate,
The coating film is formed of a coating composition containing at least a fluororesin and a resin other than the fluororesin,
When the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms on the surface of the coating film is defined as the first fluorine concentration (% by mass), the first fluorine concentration is 30 to 50% by mass,
The film thickness of the coating film is T (μm), and the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms at the position of depth T / 2 (μm) from the coating film surface is the second fluorine concentration (mass%). ), The mass ratio (A / B) of the second fluorine concentration (A) to the first fluorine concentration (B) is 13/87 to 49/51.

In a preferred example of the coated body of the present invention, the thickness of the coating film is 40 to 200 μm.

In another preferred embodiment of the coated body of the present invention, the base material is a metal base material.

In another preferred embodiment of the coated body of the present invention, the resin other than the fluorine resin is at least one resin selected from the group consisting of a polyester resin and an epoxy resin.

In another preferred embodiment of the coated body of the present invention, the coating composition is a powder coating composition.

In another preferred embodiment of the coated body of the present invention, the coating film has a scratch coefficient of 45 to 500.

According to the present invention, by adjusting the ratio of the fluorine resin on the coating film surface and the ratio of the fluorine resin at a position where the depth from the coating film surface corresponds to half of the film thickness, the weather resistance Thus, it is possible to provide a coated body excellent in wear resistance and adhesion.

Hereinafter, the coated body of the present invention will be described in detail. The coated body of the present invention is a coated body comprising a substrate and a coating film disposed on the surface of the substrate, wherein the coating film includes at least a fluorine resin and a resin other than the fluorine resin. Is formed by
When the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms on the surface of the coating film is defined as the first fluorine concentration (% by mass), the first fluorine concentration is 30 to 50% by mass,
The film thickness of the coating film is T (μm), and the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms at the position of depth T / 2 (μm) from the coating film surface is the second fluorine concentration (mass%). ), The mass ratio (A / B) of the second fluorine concentration (A) to the first fluorine concentration (B) is 13/87 to 49/51.

In the coated body of the present invention, when the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms on the surface of the coating film is defined as the first fluorine concentration (mass%), the first fluorine concentration is 30 to 50 mass%. It is necessary to be. If the first fluorine concentration is within the above specified range, the ratio of the fluorine resin on the coating film surface is sufficiently high, so that weather resistance and wear resistance can be improved. On the other hand, when the first fluorine concentration is less than 30% by mass, sufficient weather resistance and wear resistance cannot be obtained. In addition, although the weather resistance and the wear resistance can be improved as the first fluorine concentration is higher, the first fluorine concentration is higher than 50% by mass after satisfying the regulations on the second fluorine concentration. It is difficult to control the distribution of the fluororesin.

In the present invention, the surface of the coating film is a surface located on the side opposite to the surface where the coating film is in contact with the substrate.

In the coated body of the present invention, the film thickness of the coating film is T (μm), and the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms at a position of depth T / 2 (μm) from the coating film surface is defined as When the second fluorine concentration (% by mass) is used, it is necessary that the mass ratio (A / B) of the second fluorine concentration (A) to the first fluorine concentration (B) is 13/87 to 49/51, It is preferably 25/75 to 49/51, and more preferably 30/70 to 45/55. If the mass ratio (A / B) is within the above-specified range, the composition ratio of the resin components in the coating film is greatly different (for example, the fluororesin layer and polyester constituting the coating film described in Patent Document 2) The interface of the resin layer) hardly occurs, and sufficient adhesion can be ensured. Further, since the fluorine concentration is moderately contained also in the vicinity of the inner middle of the film, it has good wear resistance.
In the coated body of the present invention, the region in which the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms is 30 to 50% by mass usually varies depending on the fluorine resin and other compounding agents used. This is a region closer to the coating film surface than the position of T / 2 (μm). For this reason, if the 2nd fluorine density | concentration which is a parameter | index of the fluororesin density | concentration in the position of depth T / 2 (micrometer) from the coating-film surface is in the specified range, the composition ratio of the resin component in the coating film A greatly different region (for example, the interface between the fluororesin layer and the polyester resin layer described in Patent Document 2) does not occur, and sufficient adhesion can be ensured.

In the present invention, the film thickness of the coating film is an average film thickness. For example, 10 arbitrary points of the coating film are selected, the film thickness is measured with an optical microscope or a scanning electron microscope, and the average value is calculated. It can be obtained by calculating. In the coated body of the present invention, the coating film is not a coating film obtained by coating a coating composition containing a resin other than a fluorine resin, for example, and then coating a coating composition containing a fluorine resin. Since it is a coating film obtained by coating a coating composition containing a resin and a resin other than the fluororesin, the thickness of the coating film is, for example, 40 to 200 μm.

In the present invention, the fluorine resin in the position where the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms on the surface of the coating film (first fluorine concentration) and the depth from the coating film surface corresponds to half of the film thickness (Second fluorine concentration) can be measured using an SEM / EDS (Scanning Electron Microscope “Scanning Electron Microscope” / Energy Dispersive X-ray Spectroscope “Energy Dispersive X-ray Spectroscopy”).
When measuring the first fluorine concentration, first, the surface of the coating film is observed with SEM, and then elemental analysis is performed using EDS to measure the ratio of fluorine atoms to carbon atoms. In addition, when observing the coating film surface with SEM, the value of the 1st fluorine concentration may change with the acceleration voltage of SEM, and the tendency is large especially when acceleration voltage is low. Therefore, it is preferable to measure by setting the SEM acceleration voltage to 10 kV to 20 kV. In addition, in order to reduce the damage of the coating film surface by the electron beam accompanying a SEM measurement, you may vapor-deposit a conductive substance (for example, gold | metal | money etc.) in advance on a measurement sample surface before a measurement.
When measuring the second fluorine concentration, first, the cross section of the coating film is observed with an SEM. Next, the second fluorine concentration can be measured by determining the ratio of fluorine atoms and carbon atoms at a position where the depth from the coating film surface corresponds to half of the film thickness by line analysis using EDS. In addition, when observing the coating-film surface with SEM, the value of 2nd fluorine concentration may change with the acceleration voltage of SEM, and the tendency is large especially when acceleration voltage is low. Therefore, it is preferable to measure by setting the SEM acceleration voltage to 10 kV to 20 kV. In addition, in order to reduce the damage of the coating film surface by the electron beam accompanying a SEM measurement, you may vapor-deposit a conductive substance (for example, gold | metal | money etc.) in advance on a measurement sample surface before a measurement.

When measuring the film thickness and the second fluorine concentration, the cross section of the coating film is observed. In general, as a method for preparing a measurement sample for observing the cross section of the coating film, the coating film is mechanically cut directly, Cleave or break, and then embed it in a resin such as an epoxy resin in a state in which the coating film stands upright, and then perform processing such as grinding, polishing, etching, etc. perpendicular to the coating film with a microtome, etc. And a method for producing a measurement sample by applying.

Since the coated body of the present invention has high abrasion resistance of the coating film as described above, the scratch coefficient of the coating film is, for example, 45 to 500. In addition, the scratch coefficient of a coating film can be measured as follows.
(Measuring method)
It can be measured according to ASTM D968 (falling sand test method). Specifically, using a Gardner falling sand abrasion tester, a test plate was installed at an angle of 45 ° with respect to the horizontal plane, and No. 4 cinnabar (average particle size: 0.6-1. 2 mm), and the scratch coefficient is calculated from the following equation. In addition, the fall height of sand is 940 mm from the center position of a coating film.
Scratch coefficient = V / T
[In the formula, V is the total amount of sand used in the sandfall test (unit: liter L), and T is a value obtained by subtracting the film thickness after the sandfall test from the film thickness before the sandfall test (that is, , Worn film thickness, unit: μm)]

The coated body of the present invention includes a base material and a coating film disposed on the surface of the base material, and the coating film includes, for example, a coating composition containing at least a fluorine resin and a resin other than the fluorine resin, preferably Is formed by applying a powder coating composition to the surface of a substrate and then melting and curing at a temperature preferably in the range of 170 to 250 ° C, more preferably in the range of 170 to 210 ° C. In the coated body of the present invention, the ratio of the fluorine resin on the coating film surface and the ratio of the fluorine resin at a position where the depth from the coating film surface corresponds to half the film thickness are adjusted to the above specific range. However, in order to satisfy these regulations, it is preferable to add a combination of an acrylic surface conditioner and a wax to the coating composition as described later.

Fluorine resin used in the coating composition is preferably a solid resin at normal temperature, and its softening point is preferably 50 to 150 ° C. In the coated body of the present invention, the fluororesin becomes a factor that brings the weather resistance and abrasion resistance to the coating film. The normal temperature is a temperature in the range of 20 ° C. ± 15 ° C. (5 to 35 ° C.) defined by JIS Z 8703.

The fluororesin preferably has a reactive site that reacts with a curing agent or the like, and preferably contains a hydroxyl group or a carboxyl group as the reactive site. A fluorine resin having a hydroxyl group or a carboxyl group can be produced, for example, by copolymerizing a fluorine-containing monomer with a monomer containing a specific reactive group.

Examples of the fluorine-containing monomer include vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, bromotrifluoroethylene, chlorotrifluoroethylene, pentafluoropropylene, hexafluoropropylene, and (per) fluoroalkyltrifluoro. Vinyl ether [(per) fluoroalkyl group has 1 to 18 carbon atoms. ] Etc. are mentioned.

On the other hand, a monomer containing a specific reactive group is a polymerizable monomer containing a hydroxyl group or a carboxyl group as a group (reactive group) that reacts with a curing agent or the like.

Specifically, examples of the hydroxyl group-containing polymerizable monomer include allyl alcohol; hydroxyalkyl vinyl ethers such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxycyclohexyl vinyl ether; 2-hydroxy Hydroxyalkyl allyl ethers such as ethyl allyl ether, 3-hydroxypropyl allyl ether, 4-hydroxybutyl allyl ether, 4-hydroxycyclohexyl allyl ether; hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate; Vinyl hydroxyacetate, vinyl hydroxyisobutyrate, vinyl hydroxypropionate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, Esters of hydroxyalkyl carboxylic acids such as vinyl droxycyclohexylcarboxylate and vinyl alcohol; esters of hydroxy acids such as hydroxypropanoic acid, hydroxybutanoic acid, hydroxypentanoic acid, hydroxy-2-methylbutanoic acid, and allyl alcohol Is mentioned.

Also, examples of the carboxyl group-containing polymerizable monomer include monoesters of dicarboxylic acid and allyl alcohol, (meth) acrylic acid, carboxyalkyl (meth) acrylates, and the like.

In addition, for the polymerization of the fluororesin, a polymerizable monomer other than the fluorine-containing monomer and a monomer containing a specific reactive group may be used. Such polymerizable monomers include vinyl ethers, olefins, allyl ethers, vinyl esters, allyl esters, (meth) acrylic acid esters, (meth) acrylic acid amides, cyano group-containing monomers, dienes, etc. And crotonic acid esters.

Specific examples of the polymerizable monomer other than the fluorine-containing monomer and the monomer containing a specific reactive group include, for example, alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, and chloroethyl vinyl ether. Olefins such as ethylene, propylene, 1-butene, isobutylene, cyclohexene, vinyl chloride and vinylidene chloride; styrene monomers such as styrene and α-methylstyrene; methyl allyl ether, ethyl allyl ether, butyl allyl ether, cyclohexyl allyl Alkyl allyl ethers such as ether; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl hexanoate, octa Vinyl esters of carboxylic acids (preferably fatty acids) such as vinyl acid and vinyl versatate; allyl esters of carboxylic acids (preferably fatty acids) such as allyl propionate and allyl acetate; methyl (meth) acrylate, (meta ) (Meth) acrylic esters such as ethyl acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate; (meth) acrylic amides such as (meth) acrylic amide; acrylonitrile, 2,4- And cyano group-containing monomers such as dicyanobutene-1; dienes such as isoprene and butadiene; and crotonic acid esters such as 2-hydroxyethyl crotonic acid and 4-hydroxybutyl crotonic acid.

The fluorine resin preferably has a fluorine content of 5 to 80% by mass, more preferably 10 to 70% by mass. Further, when the fluorine resin is a hydroxyl group-containing fluorine resin, the hydroxyl value of the fluorine resin is preferably 100 mgKOH / g or less from the viewpoint of maintaining the flexibility of the coating film. From the viewpoint of imparting impact properties, it is preferably 10 mgKOH / g or more. In particular, the hydroxyl value of the fluororesin is preferably 30 to 70 mgKOH / g.

In the coating composition, the fluorine resin content is preferably 20 to 60% by mass.

The resin other than the fluororesin used in the coating composition is preferably at least one resin selected from the group consisting of polyester resins and epoxy resins. By using a resin other than the fluorine resin in combination, the appearance and workability of the coating film can be improved and the manufacturing cost can be reduced as compared with the case where only the fluorine resin is used as the resin component. In the coating composition, the content of the resin other than the fluorine resin is preferably 25 to 64% by mass.

The polyester resin that can be used in the coating composition can be produced by reacting a carboxylic acid component and a polyhydric alcohol component by a known method. The polyester resin is preferably a solid resin at normal temperature, and its softening point is preferably 100 to 150 ° C. Moreover, it is preferable that the said polyester resin has a reactive site | part which reacts with a hardening | curing agent etc., and it is preferable to contain a hydroxyl group or a carboxyl group as a reactive site | part.

Examples of carboxylic acid components that can be used in the production of the polyester resin include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,2-octadecanedicarboxylic acid, maleic acid, fumaric acid, cyclohexanedicarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid Polycarboxylic acids such as trimellitic acid and pyromellitic acid, lower alkyl esters of these polycarboxylic acids and acid anhydrides thereof, and malic acid, tartaric acid, 1,2-hydroxystearic acid, paraoxybenzoic acid, etc. And hydroxycarboxylic acid.

Examples of the polyhydric alcohol component that can be used in the production of the polyester resin include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4 -Butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, spiroglycol, 1,10-decanediol, 1,4- Examples include cyclohexanedimethanol, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol and the like.

As described above, the polyester resin can be produced by an ordinary method known for producing a polyester resin for a coating composition using a carboxylic acid component and a polyhydric alcohol component as raw materials. For example, the above-mentioned raw materials are used in appropriate combinations and mixing ratios, subjected to esterification or transesterification at 200 to 280 ° C. according to a conventional method, and then subjected to polycondensation reaction at 230 to 290 ° C. using a catalyst under reduced pressure. In some cases, a polyester resin can be produced by performing a depolymerization reaction with a polyhydric alcohol.

The polyester resin may have a reactive group other than a hydroxyl group and a carboxyl group. Examples of such reactive sites include functional groups such as amide groups, amino groups, nitrile groups, glycidyl groups, and isocyanate groups.

The polyester resin is preferably a hydroxyl group-containing polyester resin from the viewpoint of cross-linking reaction and control of coating film properties. From the viewpoint of controlling the melt viscosity, the polyester resin preferably has a number average molecular weight of 5,000 or less and a weight average molecular weight of 10,000 to 20,000. Here, the number average molecular weight and the weight average molecular weight can be determined using polystyrene as a standard substance by gel permeation chromatography (GPC).

When the polyester resin is a hydroxyl group-containing polyester resin, the hydroxyl value of the polyester resin is preferably 20 to 100 mgKOH / g, more preferably 30 to 80 mgKOH / g. The acid value of the polyester resin is preferably 20 to 80 mgKOH / g, and more preferably 30 to 80 mgKOH / g.

When the coating composition contains a polyester resin, the content of the polyester resin in the coating composition is preferably 25 to 64% by mass, and more preferably 25 to 63% by mass.

The epoxy resin that can be used in the coating composition is preferably a resin that is solid at room temperature, and its softening point is preferably 50 to 150 ° C. By using an epoxy resin, the adhesion to the substrate can be improved. It does not specifically limit as said epoxy resin, The epoxy resin conventionally used in the epoxy resin-type coating composition can be used.

Specifically, as the epoxy resin, for example, bisphenol A type diglycidyl ether resin, bisphenol F type diglycidyl ether resin, aminoglycidyl ether resin, bisphenol AD type diglycidyl ether resin, bisphenol Z type diglycidyl ether resin, O -Cresol novolac epoxy resin, phenol novolac epoxy resin, biphenol glycidyl ether resin, cyclopentadiene skeleton epoxy resin, naphthalene skeleton epoxy resin, GMA acrylic resin, etc., and other substituents other than epoxy groups of these resins are replaced with other substituents Examples thereof include resins obtained by a modification reaction using a carboxyl group-terminated polybutadiene-acrylonitrile (CTBN) or a modification reaction such as esterification. The epoxy resin preferably has an epoxy equivalent of 300 to 1200, particularly preferably 400 to 1000.

When the coating composition contains an epoxy resin, the content of the epoxy resin in the coating composition is preferably 0.3 to 5% by mass.

The coating composition preferably contains an acrylic surface conditioner and a wax. Although the detailed mechanism is unknown, the effect of blending an acrylic surface conditioner and wax in the coating composition is that the surface tension of the coating composition is lowered and the fluorine resin is more likely to be unevenly distributed on the coating film surface. In addition, since the effect of preventing the viscosity of the coating composition from increasing during melting after painting appears, the ratio of fluorine resin on the coating film surface and the depth from the coating film surface corresponds to half of the film thickness. It becomes possible to easily adjust the ratio of the fluororesin at the position to be within the above specified range. The acrylic surface conditioner and the wax may be blended separately in the raw material of the coating composition, or a mixture obtained by previously mixing the acrylic surface conditioner and the wax in the raw material of the coating composition. You may mix in.

Since the acrylic surface conditioner that can be used in the coating composition is a compounding agent that contributes to the surface adjustment of the coating film, it has a property of melting at the temperature at which the coating film is formed. Therefore, the softening point of the acrylic surface conditioner is preferably 75 to 100 ° C. In the present invention, the softening point of the acrylic surface conditioner can be measured by a ring and ball softening point test method based on JIS K 2207 (2006). JIS K 2207 (2006) is originally a standard for petroleum asphalt, but can also be applied to the measurement of the softening point of acrylic surface conditioners.

The acrylic surface conditioner is a dibasic acid ester having a polymerizable unsaturated double bond (component X), at least one selected from an acrylic acid alkyl ester and a methacrylic acid alkyl ester (component Y), and optionally Is preferably a copolymer obtained by copolymerizing at least one of acrylic acid and methacrylic acid. Examples of the dibasic acid ester include maleic acid diesters such as maleic acid diethyl ester, maleic acid monoesters, fumaric acid diesters such as diethyl fumarate, and fumaric acid monoesters. Examples of the alkyl acrylate include normal butyl acrylate. Examples of the alkyl methacrylate include normal butyl methacrylate.

Note that the acrylic surface conditioner is, for example, a copolymer of the component X and the component Y as described above, and thus is a component different from the core-shell type acrylic resin particles described later.

When the coating composition contains an acrylic surface conditioner, the content of the acrylic surface conditioner in the coating composition is preferably 0.5 to 6% by mass.

The wax that can be used in the coating composition is preferably a wax having a melting point of 40 ° C. or higher, and the melting point of the wax is more preferably 50 ° C. to 100 ° C. In the present invention, the melting point of the wax can be measured by a visual method described in JIS K 0064 (1992). Specific examples of the wax include castor oil, amide compounds, polyolefins such as polyethylene and polypropylene, acrylic compounds such as ethylene-vinyl acetate copolymer and ethylene-acrylic acid copolymer. These waxes may be used alone or in combination of two or more.

When the coating composition contains a wax, the content of the wax in the coating composition is preferably 0.3 to 10% by mass. In the coating composition, the mass ratio (w / s) of the wax (w) to the acrylic surface conditioner (s) is preferably 0.06 to 20.

The coating composition preferably contains a curing agent. The curing agent is not particularly limited as long as it reacts with a fluororesin or a resin other than the fluororesin to form a cross-linked bond, but from β-hydroxyalkylamide, triglycidyl isocyanurate and an isocyanate compound. A curing agent selected from the group consisting of: When the coating composition contains a curing agent, the content of the curing agent in the coating composition is preferably 2 to 25% by mass.

β-Hydroxyalkylamides can be suitably used when the resin component has a carboxyl group, and those having two or more functional groups per molecule can be used for low-temperature curability and coating films obtained by coating. Particularly preferred from the viewpoint of water resistance. Examples of β-hydroxyalkylamide include N, N-di (β-hydroxyethyl) acetamide, bis (β-hydroxyethyl) adipamide, bis (β-hydroxypropyl) adipamide, bis [N, N-di (β-hydroxy). Ethyl)] adipamide and bis [N, N-di (β-hydroxypropyl)] adipamide are particularly preferred. The β-hydroxyalkylamide preferably has a hydroxylamide group of 0.5 to 1.5 equivalents relative to the carboxyl group in the resin.

Triglycidyl isocyanurate can be suitably used when the resin component has a carboxyl group. Examples of the triglycidyl isocyanurate include Araldite (registered trademark) PT 710, Araldite (registered trademark) PT 810, Araldite (registered trademark) PT 910, Araldite (registered trademark) PT 912 (all manufactured by Huntsman). Etc. The triglycidyl isocyanurate preferably has 0.5 to 1.5 equivalents of glycidyl group based on the carboxyl group in the resin.

The isocyanate compound can be suitably used when the resin component has a hydroxyl group, and is more preferably a blocked isocyanate compound. The isocyanate compound is preferably solid at room temperature. In the isocyanate compound, the isocyanate group is preferably from 0.05 to 1.5 equivalents, particularly preferably from 0.8 to 1.2 equivalents, based on the hydroxyl groups in the resin.

The blocked isocyanate compound may be masked by reacting, for example, a polyisocyanate obtained by reacting an aliphatic, aromatic or araliphatic diisocyanate with a low molecular weight compound having active hydrogen with a blocking agent. Therefore, manufacturing is also easy. Examples of the diisocyanate include tolylene diisocyanate, 4,4′-diphenylmethane isocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4′-methylene bis (cyclohexyl isocyanate), methylcyclohexane diisocyanate, bis (isocyanatomethyl) cyclohexane, isophorone. Diisocyanate, dimer acid diisocyanate, lysine diisocyanate, etc. can be mentioned. Examples of the low molecular weight compound having active hydrogen include water, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, ethanolamine, diethanolamine, hexamethylenediamine. Etc., isocyanurate, uretidione, hydroxyl group Low molecular weight polyesters having, polycaprolactone and the like. Specific examples of the blocking agent include alcohols such as methanol, ethanol and benzyl alcohol, phenols such as phenol and crezone, lactams such as caprolactam and butyrolactam, and oximes such as cyclohexanone, oxime and methyl ethyl ketoxime. . For example, specific examples of the blocked isocyanate include isophorone diisocyanate blocked with ε-caprolactam (Evonik Vestagon B1530, Bayer Cleran UI), and the like.

The coating composition may contain core-shell type acrylic resin particles. By using the core-shell type acrylic resin particles, the processability of the coating film can be improved without lowering the weather resistance.

The core-shell type acrylic resin particles have a specific surface area value measured by a nitrogen gas adsorption method expressed by the formula: D = 6 / (α × S) (where D: average primary particle diameter (μm), α: The average primary particle size calculated by substituting into density (g / cm ³ ), S: specific surface area (m ² / g)), and laser diffraction / scattering particle size distribution It is preferable that the average secondary particle diameter measured by a measuring apparatus is in the range of 5 to 50 μm.

The core-shell type acrylic resin particles preferably have at least one functional group selected from the group consisting of a carbonyl group, a hydroxyl group and a glycidyl group on the particle surface.

The core-shell type acrylic resin particles are a multiphase comprising a rubbery polymer phase at room temperature where the glass transition temperature of the core layer is 20 ° C. or less and a glassy polymer phase at room temperature where the glass transition temperature of the shell layer is 50 ° C. or more. It preferably has a structure. The core-shell type acrylic resin particles include, for example, a first polymer monomer that forms a rubber-like polymer phase by emulsion and suspension polymerization to form rubber-like polymer particles having a glass transition temperature of 20 ° C. or less. By a first-stage reaction, followed by a second-stage reaction in which a polymerizable monomer forming a glassy polymer phase having a glass transition temperature of 50 ° C. or higher is radically polymerized in the presence of the rubbery polymer particles. can get. Here, in order to introduce a functional group to the particle surface of the core-shell type acrylic resin particle, the radical polymerizable monomer constituting the glassy polymer is a functional group selected from the group consisting of a carboxyl group, a hydroxyl group and a glycidyl group. It preferably has at least one group.

The rubbery polymer constituting the core layer is, for example, a polymer of an unsaturated monomer that can be used for the synthesis of a rubbery polymer. The glass transition temperature of the rubbery polymer is preferably 20 ° C. or less, and more preferably in the range of −30 to −10 ° C. Here, specific examples of the unsaturated monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl ( Alkyl (meth) acrylates such as meth) acrylate: Vinyl esters such as vinyl acetate: Vinyl halides such as vinyl chloride, vinyl fluoride, vinylidene chloride, vinylidene fluoride or vinylidene halides: (meth) acrylonitrile, (meth) acrylamide, etc. Nitrogen-containing unsaturated monomer: Aromatic compounds such as styrene, α-methylstyrene and vinyltoluene: Hydroxyl-containing unsaturated monomers such as hydroxyethyl (meth) acrylate and methylol (meth) acrylamide: (meth) acrylic acid Unsaturated carboxylic acids such as: Dienes, and diene monomers such as isoprene and the like. These unsaturated monomers may be used independently and may be used in combination of 2 or more type. Typical examples of rubber-like polymers are poly (meth) acrylate rubber, polybutadiene rubber, polyisoprene rubber, polyvinyl chloride, styrene-butadiene rubber, styrene-butadiene-styrene rubber, styrene-isoprene-styrene rubber, styrene- Examples include butylene rubber, styrene-ethylene rubber, and ethylene-propylene rubber. Among these, poly (meth) acrylate rubber, polybutadiene rubber, polyisoprene rubber, and styrene-butadiene rubber are particularly preferable.

The glassy polymer constituting the shell layer is, for example, a polymer of a radical polymerizable monomer adjusted to have a glass transition temperature of 50 ° C. or higher, preferably 80 to 100 ° C. Here, as the radical polymerizable monomer, a general vinyl monomer or the like can be used, and examples thereof include the above-described unsaturated monomer. Examples of the vinyl monomer having the functional group include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, etc. acrylic acid or methacrylic acid hydroxyalkyl having 2 to 8 carbon atoms Esters; monoesters of polyether polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and unsaturated carboxylic acids such as (meth) acrylic acid; polyether polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol; Hide Monoethers with hydroxyl-containing unsaturated monomers such as xylethyl (meth) acrylate; adducts of α, β-unsaturated carboxylic acids with monoepoxy compounds such as Cardura E10 (manufactured by Shell Chemical) and α-olefin epoxides Adducts of glycidyl (meth) acrylate with monobasic acids such as acetic acid, propionic acid, pt-butylbenzoic acid and fatty acids; acid anhydride group-containing unsaturated compounds such as maleic anhydride and itaconic anhydride Monoesterified or diesterified with ethylene glycol, 1,6-hexanediol, neopentyl glycol and the like glycols; hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 3-chloro-2-hydroxypropyl (meth) Hydroxyl-containing monomer containing chlorine such as acrylate , Allyl alcohol, epoxy-group-containing unsaturated monomers, and the like. These radically polymerizable monomers may be used alone or in combination of two or more.

The core-shell type acrylic resin particles are obtained by a conventionally known method, for example, an emulsion polymerization method or a suspension polymerization method in which a radical polymerizable monomer and a radical polymerizable initiator are added in the presence of a rubbery polymer emulsion in advance. Obtainable.

When the coating composition contains core-shell type acrylic resin particles, the content of the core-shell type acrylic resin particles in the coating composition is preferably 0.1 to 5% by mass.

The coating composition may further contain a bright pigment. In addition, when a luster pigment is used, alkali resistance can be improved. There are also scaly pigments. Bright pigments include, for example, aluminum powder pigment, nickel powder pigment, gold powder, silver powder, bronze powder, copper powder, stainless steel powder pigment, mica pigment, graphite pigment, glass flake pigment, metal-coated glass powder, metal coating Mica powder, metal-coated plastic powder, and scaly iron oxide pigment.

The coating composition may contain a commonly used pigment such as a colored pigment or an extender pigment in addition to the bright pigment. Examples of the color pigment include inorganic pigments such as titanium oxide, yellow iron oxide, titanium yellow, bengara, lithopone and antimony oxide, Hansa Yellow 5G, Permanent Yellow FGL, Phthalocyanine Blue, Indanthrene Blue RS, Permanent Red F5RK, And organic pigments such as Brilliant First Scarlet G. On the other hand, examples of extender pigments include barium sulfate, barium carbonate, calcium carbonate, clay, silica powder, diatomaceous earth, talc, basic magnesium carbonate, and alumina white. Moreover, the said coating composition may contain a rust prevention pigment, when the rust prevention property is required for the base material which should be painted. Examples of rust preventive pigments include condensed calcium phosphate, aluminum phosphate, condensed aluminum phosphate, zinc phosphate, aluminum phosphite, zinc phosphite, calcium phosphite, zinc molybdate, calcium molybdate, and manganese molybdate. Can be mentioned. These pigments may be used alone or in combination of two or more.

When the coating composition contains a pigment, the total content of the pigment in the coating composition is preferably 0.2 to 35% by mass.

In the coating composition, as additives for general coatings, plasticizers, curing accelerators, crosslinking accelerators, ultraviolet absorbers, light stabilizers, antioxidants, fluidity modifiers, anti-sagging agents and antifoaming agents You may mix | blend an agent etc. as needed.

The method for producing the coating composition includes, for example, melting and kneading a mixture containing the fluororesin, a resin other than the fluororesin, an acrylic surface conditioner and a wax at 100 to 160 ° C., and then cooling and pulverizing the mixture. And a method for preparing a powder coating composition. Preferably, a mixture containing the above fluororesin, a resin other than fluororesin, an acrylic surface conditioner and wax is dry blended with a Henschel mixer or the like, and then melt-kneaded at 120 to 140 ° C. using a co-kneader or the like, and cooled. After pulverization, the powder coating composition can be obtained by classification using a 180 mesh (96 μm) wire mesh or the like.

Examples of the coating method of the coating composition include corona charging electrostatic powder coating, friction charging electrostatic powder coating, fluidized immersion powder coating, electrostatic fluidized immersion powder coating, and electric field cloud powder. Examples include body painting. After coating, the coating composition can be formed by melting and curing the coating composition at a temperature of preferably 160 to 250 ° C., more preferably 170 to 220 ° C.

Examples of the substrate constituting the coated body of the present invention include metal substrates such as steel, zinc, aluminum, copper, and tin. In order to improve adhesion to the coating film, the surface of the metal substrate is used. Those subjected to ground treatment are preferred. The base material has various shapes depending on its use, and examples thereof include a plate shape. However, the coating film constituting the coated body of the present invention is usually formed on one surface of the base material. ing.

Specific examples of the coated body of the present invention include automobiles, trains, aircraft and other transportation equipment and members thereof, bridges and members thereof, steel towers and members thereof, civil engineering members, waterproof sheets, tanks, pipes and other industrial equipment, Building exteriors, doors, window gates, monuments, building components such as poles, road median strips, guardrails, sound barriers, polycarbonate translucent plates, traffic lights and other road components, communication equipment and components, home appliances, electricity And electronic components.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

<Example of production of acrylic surface conditioner>
(Acrylic surface conditioner A)
In a polymerization apparatus equipped with a reflux condenser, a thermometer, a stirrer, and a dropping tank, 300 parts by mass of butyl acetate was added, and a dropping solution A shown below was dropped at 110 ° C. over about 3 hours under a nitrogen atmosphere. After completion of the dropwise addition, 5 parts by mass of t-amylperoxy-2-ethylhexanoate was added and kept at 110 ° C. for 2 hours. Thereafter, the temperature was raised to 130 ° C., and butyl acetate was distilled off under reduced pressure to obtain an acrylic surface conditioning agent A. When the number average molecular weight in terms of polystyrene of the acrylic surface conditioning agent A was measured by gel permeation chromatography, it was 3500. Moreover, it was 83 degreeC when the softening point of the acrylic surface conditioning agent A was measured by the ring-and-ball type softening point test method based on JISK2207 (2006).
Dropping solution A: a solution comprising 324 parts by weight of normal butyl acrylate, 65 parts by weight of acrylic acid, 28 parts by weight of maleic acid diethyl ester, 15 parts by weight of t-amylperoxy-2-ethylhexanoate, and 200 parts by weight of butyl acetate .

(Acrylic surface conditioner B)
An acrylic surface conditioning agent B was obtained in the same manner as in the production example of the acrylic surface conditioning agent A, except that the dropping solution B shown below was used instead of the dropping solution A. When the number average molecular weight in terms of polystyrene of the acrylic surface conditioning agent B was measured by gel permeation chromatography, it was 4100. Moreover, it was 92 degreeC when the softening point of the acrylic type surface conditioning agent B was measured by the ring and ball type softening point test method based on JISK2207 (2006).
Dropping solution B: a solution comprising 324 parts by weight of normal butyl acrylate, 65 parts by weight of acrylic acid, 28 parts by weight of fumaric acid diethyl ester, 15 parts by weight of t-amylperoxy-2-ethylhexanoate, and 200 parts by weight of butyl acetate .

(Acrylic surface conditioner C)
An acrylic surface conditioning agent C was obtained in the same manner as in the production example of the acrylic surface conditioning agent A, except that the following dropping solution C was used instead of the dropping solution A. It was 2900 when the polystyrene conversion number average molecular weight of the acrylic surface conditioning agent C was measured by gel permeation chromatography. Moreover, it was 78 degreeC when the softening point of the acrylic type surface conditioning agent C was measured by the ring and ball type softening point test method based on JISK2207 (2006).
Drop solution C: From 324 parts by weight of normal butyl acrylate, 47 parts by weight of maleic acid diethyl ester, 46 parts by weight of fumaric acid diethyl ester, 15 parts by weight of t-amylperoxy-2-ethylhexanoate, and 200 parts by weight of butyl acetate Solution.

<Preparation example of powder coating composition>
In accordance with the formulation shown in Table 1, the raw materials were put into a high speed mixer and mixed for 1 minute. Next, the obtained mixture is kneaded using a biaxial kneader (manufactured by Toshiba) whose temperature is adjusted to 120 ° C., the discharged kneaded material is cold-rolled with a cooling roll, and then pulverized using a pin mill. The powder coating compositions of Examples 1 to 11 and Comparative Examples 1 to 3 (50% volume average particle size: 32 μm) were obtained.

<Preparation example of painted body>
Test plates (coated bodies) were prepared using the powder coating compositions of Examples 1 to 11 and Comparative Examples 1 to 3. Specifically, a chromic acid chromate-treated aluminum plate having a thickness of 1.5 mm is suspended in the vertical direction, and a voltage of −60 kV using a corona-charged electrostatic powder coating machine (PG-1 type manufactured by Asahi Sunac Corporation). The film was electrostatically coated to a film thickness of 60 μm, baked in an electric furnace at 190 ° C. for 20 minutes, and allowed to cool to room temperature as it was to prepare a test plate.

<< Evaluation >>
Various measurements and evaluation tests were performed on the obtained test plate, and the results are shown in Table 1.

<Measuring method of film thickness>
Stand the test plate vertically in the clear cup for embedding using the sample clip, and pour the epoxy resin “Epocure (Buhler) main agent + curing agent” into it to completely cure the epoxy resin and wrap it in the epoxy resin. A buried test plate was obtained. Using a polishing machine “Ecomet 3000 + Automet 2000 (Buhler)”, a test plate embedded in epoxy resin by pouring Metadai and Masterprep (Buhler) onto # 320 and # 600 polishing paper and buff. Was polished to obtain a cross-section of the coating film. Using the SEM (SU-70, manufactured by Hitachi High-Technologies Corporation), the film thickness was measured at 10 points with an acceleration voltage of 1 kv and a magnification of 900 times, and the average value was obtained. Asked.

<Measurement method of mass ratio of fluorine atom to carbon atom>
As measuring instruments, SU-70 manufactured by Hitachi High-Technologies Corporation was used as SEM, and INCA X-Sight (Model 7969) manufactured by Oxford Instruments Co., Ltd. was used as EDS. In EDS, cobalt was selected as an element for quantitative optimization, and conditions were set. The parameters of the apparatus at that time were Livetime 100 seconds, Process time 5, Spectrum range 0-20 kev, Number of channels 1K.
(Measurement method of the first fluorine concentration)
The first fluorine concentration is the ratio (mass%) of fluorine atoms to the total mass of fluorine atoms and carbon atoms on the coating film surface. First, the test plate was cut out to about 1 cm × 1 cm, and in order to reduce damage to the coating film surface by the electron beam, gold was vapor-deposited on the cut-out sample, and the gold-deposited sample was fixed to the SEM observation stand with conductive tape. Thereafter, SEM observation was performed at an acceleration voltage of 15 kv and a magnification of 500 times. Next, the coating surface having an area of 245 μm × 185 μm is arbitrarily selected by EDS, elemental mapping measurement is performed on the coating surface, the ratio of carbon atoms to fluorine atoms is measured, and the total of fluorine atoms and carbon atoms is measured. The proportion of fluorine atoms in the mass was determined. Then, the place where element mapping measurement was performed was changed, and the ratio of fluorine atoms in the total mass of fluorine atoms and carbon atoms on the coating film surface (245 μm × 185 μm) was measured nine times. The average of 10 measurement results was defined as the first fluorine concentration.
(Measurement method of the second fluorine concentration)
The second fluorine concentration is a ratio (mass%) of fluorine atoms in the total mass of fluorine atoms and carbon atoms at a position where the depth from the coating film surface corresponds to half of the film thickness. First, gold was vapor-deposited on a test plate embedded in an epoxy resin used for film thickness measurement in order to reduce damage to the coating film surface by an electron beam, and this gold-deposited sample was conducted to an SEM observation stand. After fixing with the adhesive tape, SEM observation was performed at an acceleration voltage of 15 kv and a magnification of 900 times. Next, at a position where the depth from the coating film surface corresponds to half of the film thickness, a line parallel to the coating film surface and having a length of 135 μm is arbitrarily selected, and element mapping measurement of the line by EDS (line Analysis), the ratio of carbon atoms to fluorine atoms was measured, and the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms was determined. Then, the place where element mapping measurement was performed was changed, and the ratio of fluorine atoms in the total mass of fluorine atoms and carbon atoms at a position where the depth from the coating film surface corresponds to half of the film thickness was measured nine times. The average value of 10 measurement results was defined as the second fluorine concentration.

<Abrasion resistance>
Measured according to ASTM D968 (falling sand test method). Specifically, using a Gardner-type sandfall wear tester, install a test plate at an angle of 45 ° to the horizontal plane, drop No. 4 sand at the center of the coating film, and calculate the scratch coefficient from the following equation. calculate. In addition, the fall height of sand was 940 mm from the center position of the coating film.
Scratch coefficient = V / T
[In the formula, V is the total amount of sand used in the sandfall test (unit: liter L), and T is a value obtained by subtracting the film thickness after the sandfall test from the film thickness before the sandfall test (that is, , Worn film thickness, unit: μm)]
In addition, based on the calculated scratch coefficient, the wear resistance was evaluated according to the following evaluation criteria.
◎ ・ ・ ・ Scratch coefficient is 100 or more ○ ・ ・ ・ Scratch coefficient is 45 or more and less than 100 △ ・ ・ ・ Scratch coefficient is 40 or more and less than 45 × ・ ・ ・ Scratch coefficient is less than 40

<Weather resistance>
Accelerated weathering tester based on JIS B7753 (Sunshine weatherometer method) for test plates (coating bodies) obtained using the powder coating compositions of Examples 1 to 11 and Comparative Examples 1 to 3 Was used to evaluate the weather resistance. The test time was 3000 hours. The 60 ° specular gloss value before the test and after the 3000 hour test was measured with a gloss meter (manufactured by micro-TRI-gross BYK: incident reflection angle 60 °), and the 60 ° specular gloss value before the test after the 3000 hour test. The change rate of the specular gloss value was determined, and the weather resistance was evaluated according to the following evaluation criteria.
◎ ・ ・ ・ Change rate is 90% or more ○ ・ ・ ・ Change rate is 70% or more and less than 90% △ ・ ・ ・ Change rate is 50% or more and less than 70% × ・ ・ ・ Change rate is less than 50%

<Adhesiveness>
In accordance with JIS K5600-5-6 (cross-cut method), the coating on the test plate was cut into a grid of 100 squares at 1 mm intervals, a peel test was performed using an adhesive tape, and the residual rate after the peel test The adhesion was evaluated according to the following evaluation criteria.
○: 100/100 (number of cut parts remaining after the test / total number of cut parts before the test)
Δ: 85/100 to 99/100
X: 84/100 or less

In addition, the detail of the raw material described in Table 1 is shown below.
(* 1) Fluorine resin (Asahi Glass Co., Ltd., trade name: Lumiflon LF710F, hydroxyl group-containing fluorine resin)
(* 2) Polyester resin (manufactured by Daicel Cytec Co., Ltd., trade name: Krill Coat 4642-3)
(* 3) Epoxy resin (manufactured by Toto Kasei Co., Ltd., trade name: Epototo DT-112)
(* 4) Curing agent (ε-caprolactam block isocyanate, manufactured by Evonik Degussa, trade name: Vestagon B1530)
(* 5) Silica-based surface conditioner (manufactured by Big Chemie, trade name: BYK360P)
(* 6) The acrylic surface conditioners A to C obtained in the above-described production examples of the acrylic surface conditioner were used.
(* 7) Wax (castor oil, melting point 80 ° C., manufactured by Ito Oil Co., Ltd., trade name: castor oil)
(* 8) Crosslinked resin fine particles prepared by the following method were used.
(* 9) Core-shell type acrylic resin particles prepared by the following method were used.

(Preparation example of crosslinked resin fine particles)
Hereinafter, preparation examples of the crosslinked resin fine particles shown in Table 1 will be described. Using a homomixer (manufactured by Mizuho Kogyo Co., Ltd., tabletop quick homomixer LR), the oil phase shown below was dispersed in the water phase shown below at a rotational speed of 12000 rpm. This dispersion was put into a polymerization reactor equipped with a stirrer, a heating device and a thermometer, and suspension polymerization was carried out by continuing stirring at 60 ° C. for 6 hours. This suspension was filtered under reduced pressure, and the resulting reaction product was washed with water, dried and pulverized to obtain crosslinked resin fine particles having a volume average particle diameter of 6.8 μm.
Oil phase Butyl acrylate 80 parts by mass Tetradecaethylene glycol dimethacrylate 20 parts by mass Benzoyl peroxide 0.3 parts by mass Aqueous phase Deionized water 400 parts by mass Polyvinyl alcohol (saponification degree 85%) 8 parts by mass Sodium lauryl sulfate 0 .07 parts by mass

(Example of preparation of core-shell type acrylic resin particles)
Hereinafter, preparation examples of the core-shell type acrylic resin particles shown in Table 1 will be described.
To a 5 L polymerization vessel, add 1500 g of deionized water and 300 g of a 5% by volume aqueous polyvinyl alcohol solution, and stir at 4500 rpm using a homomixer (manufactured by ASONE Co., Ltd.). A monomer mixture obtained by dissolving 12 g of 4-butylene glycol diacrylate, 12 g of allyl methacrylate and 6 g of lauroyl peroxide (polymerization initiator) was added all at once and dispersed for 1 hour to obtain a monomer dispersion. Next, a stirrer and a reflux condenser were attached to the polymerization vessel, and the temperature was raised to 70 ° C. while stirring under a nitrogen stream. The reaction was carried out for 2 hours while stirring at 70 ° C. At this time, sampling was performed from the obtained suspension of polymer particles, and the polymerization conversion rate of the monomer was measured and found to be 94%. The resulting polymer particle suspension was then cooled to 60 ° C. While stirring this suspension at 4500 rpm, a monomer emulsion for the second stage reaction shown below was continuously added over 15 minutes. (The monomer emulsion for the second stage reaction was 352 g of methyl methacrylate, 40 g of ethyl acrylate, 10 g of 2-hydroxyethyl methacrylate, 8 g of ethylene glycol dimethacrylate, 4 g of 2,2′-azobisisobutyronitrile, 1 mass. % 100% sodium dodecyl sulfonate aqueous solution and 100 g of deionized water were mixed to prepare.)
When polymerization was started and exotherm was observed, the temperature was raised to 80 ° C., and an aging reaction was performed for 3 hours. The obtained suspension was cooled to room temperature, dehydrated and washed using a centrifuge, and further air-dried at 60 ° C. overnight to obtain core-shell type acrylic resin particles.
From the DSC measurement of the core-shell type acrylic resin particles, the glass transition temperature of the rubber-like polymer phase (core layer) was −20 ° C., and the glass transition temperature of the glass-like polymer phase (shell layer) was 83 ° C. Specific primary surface area / pore distribution measuring device Asap 2020 (manufactured by Shimadzu Corporation) has an average primary particle size calculated from specific surface area measurement of 0.1 μm, and a laser diffraction / scattering particle size distribution measuring device Partica. The average secondary particle diameter measured by LA-950V2 (manufactured by Horiba, Ltd.) was 6 μm.

Claims (6)

1. A coated body comprising a substrate and a coating film disposed on the surface of the substrate,
   The coating film is formed of a coating composition containing at least a fluororesin and a resin other than the fluororesin,
   When the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms on the surface of the coating film is defined as the first fluorine concentration (% by mass), the first fluorine concentration is 30 to 50% by mass,
   The film thickness of the coating film is T (μm), and the ratio of fluorine atoms to the total mass of fluorine atoms and carbon atoms at the position of depth T / 2 (μm) from the coating film surface is the second fluorine concentration (mass%). ), The mass ratio (A / B) of the second fluorine concentration (A) to the first fluorine concentration (B) is 13/87 to 49/51.
2. The coated body according to claim 1, wherein the coating film has a thickness of 40 to 200 µm.
3. The coated body according to claim 1 or 2, wherein the substrate is a metal substrate.
4. The coated body according to any one of claims 1 to 3, wherein the resin other than the fluorine resin is at least one resin selected from the group consisting of a polyester resin and an epoxy resin.
5. The coated body according to any one of claims 1 to 4, wherein the coating composition is a powder coating composition.
6. The coated body according to any one of claims 1 to 5, wherein the coating film has a scratch coefficient of 45 to 500.