JPWO2017094861A1 - Coating composition and painted body - Google Patents

Abstract

Provided are a coating composition capable of forming a cured coating film excellent in processability and weather resistance, and a coated body having a cured coating film formed from the coating composition.
The coating composition of the present invention includes a fluorine-containing polymer having a hydroxyl group having a hydroxyl value of 5 to 100 mgKOH / g, a (meth) acrylate polymer having a hydroxyl group having a glass transition temperature of 15 to 70 ° C, A coating composition containing an isocyanate curing agent, a blocked isocyanate curing agent, and at least one curing agent selected from the group consisting of amino resins, wherein the number average molecular weight of the fluoropolymer and the ( The absolute value of the difference from the number average molecular weight of the (meth) acrylate polymer is within 5000.

Description

  The present invention relates to a coating composition and a coated body.

Fluoropolymer paints are used as building exterior materials such as roofing materials, wall materials, and glass opening members, which have excellent weather resistance of coating films and high maintenance-free requirements.
For example, a metal plate coated with a fluororesin paint is excellent in physical and chemical properties of a fluororesin coating film, that is, weather resistance, chemical resistance, stain resistance, etc. As popular. From the viewpoint of workability at the time of forming, a thermoplastic fluororesin paint mainly made of polyvinylidene fluoride is generally used for the metal plate coated with the fluororesin paint.
On the other hand, thermosetting fluororesin paints are superior to thermoplastic fluororesin paints in terms of coating strength, chemical resistance, and heat resistance, but the base material is rusted due to cracks and cracks in the processed parts. In other applications where strict processability is not required. In order to improve the processability of the coating film and the adhesion to the base material, Patent Documents 1 and 2 provide a thermosetting (meth) acrylate polymer to the thermosetting fluororesin for such a problem. A blended thermosetting fluoropolymer paint is disclosed.

JP-A-9-87575 JP-A-2015-875

However, the cured coating film obtained even if the paint containing the hydroxyl group-containing fluoropolymer and the hydroxyl group-containing (meth) acrylate polymer, which are thermosetting fluororesins, are poorly compatible and the paint after mixing is uniform in appearance. May take a sea-island structure between the cured portion of the fluoropolymer and the cured portion of the (meth) acrylate polymer, and as a result, the UV degradation of the cured portion of the (meth) acrylate polymer over time may occur. There was a problem of being conspicuous. Moreover, there was a problem that cracking occurred with time after construction.
Further, the workability was not at a sufficiently satisfactory level, and there was a problem that a crack occurred in the processed portion during the construction of the coated plate.

  The subject of this invention is made | formed in view of this subject, Comprising: It is provision of the composition for coating materials which can form the cured coating film excellent in workability and a weather resistance.

The present invention has configurations described in [1] to [12] below.
[1] A fluorine-containing polymer having a hydroxyl group with a hydroxyl value of 5 to 100 mgKOH / g, a (meth) acrylate polymer having a hydroxyl group with a glass transition temperature of 15 to 70 ° C., an isocyanate curing agent, A coating composition containing a blocked isocyanate curing agent and at least one curing agent selected from the group consisting of amino resins, wherein the number average molecular weight of the fluoropolymer and the (meth) acrylate weight The coating composition whose absolute value of the difference with the number average molecular weight of coalescence is 5000 or less.
[2] The coating composition according to [1], wherein the hydroxyl value of the (meth) acrylate polymer is 20 to 80 mg KOH / g.
[3] The coating composition according to [1] or [2], wherein the absolute value of the difference between the glass transition temperature of the fluoropolymer and the glass transition temperature of the (meth) acrylate polymer is within 30 ° C.
[4] The (meth) acrylate polymer has a unit based on hydroxyalkyl (meth) acrylate and a unit based on (meth) acrylate having no crosslinkable group. Y / Z (mol) when the content of units based on hydroxyalkyl (meth) acrylate with respect to the total amount is Y mol% and the content of units based on (meth) acrylate having no crosslinkable group is Z mol%. The coating composition according to any one of [1] to [3], which is a polymer having a ratio of 1/99 to 30/70.

[5] The coating composition according to [4], wherein the (meth) acrylate having no crosslinkable group is an alkyl (meth) acrylate having an alkyl group having 6 or less carbon atoms.
[6] First unit based on at least one alkyl (meth) acrylate wherein the unit based on (meth) acrylate having no crosslinkable group is selected from methyl (meth) acrylate and ethyl (meth) acrylate And a second unit based on at least one alkyl (meth) acrylate selected from n-butyl (meth) acrylate, i-butyl (meth) acrylate and t-butyl (meth) acrylate, Z ¹ / Z ² (molar ratio) when the content of the first unit is Z ¹ mol% and the content of the second unit is Z ² mol% with respect to the total amount of units based on the monomer [5] The coating composition according to [4], in the range of 5/99 to 70/30.
[7] The coating composition according to [5] or [6], wherein the alkyl (meth) acrylate is alkyl methacrylate.
[8] The coating composition according to any one of [1] to [7], wherein the glass transition temperature of the (meth) acrylate polymer is 15 to 40 ° C.
[9] Further, a pigment component is contained, and the content of the pigment component is more than 30% and 100% by mass or less with respect to the total content of the fluoropolymer and the (meth) acrylate polymer. , [1] to [8].
[10] A coated body having a cured coating film formed from the coating composition according to any one of [1] to [9].
[11] The painted body according to [10], wherein the base material of the painted body is a building exterior member.
[12] The coated body according to [10] or [11], wherein the cured coating film has a thickness of 20 to 60 μm.

According to the coating composition of this invention, the cured coating film excellent in workability can be formed. That is, since the cured coating film is excellent in followability, when the base material having the cured coating film is formed by bending or the like, cracks occur in the processed portion of the cured coating film immediately after the molding. Can be suppressed.
Moreover, according to the coating composition of this invention, since the cured coating film excellent in the weather resistance is obtained, even if it uses outdoors for a long period of time, a crack does not generate | occur | produce in a process part.

Hereinafter, the coating composition of the present invention and the coated body will be described in detail.
In this specification, “unit based on monomer” means an atomic group directly formed by polymerization of one monomer molecule and an atomic group obtained by chemically converting a part of the atomic group. It is a generic name. Hereinafter, the unit based on the monomer is also simply referred to as “unit”.
In this specification, “(meth) acrylate” is a general term for “acrylate” and “methacrylate”, and “(meth) acrylate-based polymer” is a polymer containing units based on (meth) acrylate. The polymer is different from the fluorine-containing polymer in the present invention.
In this specification, the number average molecular weight of a polymer is a number average molecular weight measured by gel permeation chromatography using polystyrene as a standard substance. The number average molecular weight is also simply referred to as “Mn”.
In this specification, the glass transition temperature of a polymer is a glass transition temperature measured by the method of JIS K 6240: 2011. The glass transition temperature is also simply referred to as “Tg”.

Hereinafter, each component of the coating composition of this invention is explained in full detail.
The hydroxyl value of the fluoropolymer in the present invention is 5 to 100 mgKOH / g, preferably 7 to 95 mgKOH / g, more preferably 9 to 90 mgKOH / g. When the hydroxyl value of the fluoropolymer is 5 mgKOH / g or more, it reacts with the curing agent, and a tough cured coating film is obtained. Moreover, if the hydroxyl value of a fluoropolymer is 100 mg / g or less which is an upper limit, the softness | flexibility of a cured coating film and the adhesiveness to a base material will become favorable.
Hereinafter, the cured coating film is also simply referred to as “coating film”.

The Mn of the fluoropolymer is preferably from 3,000 to 500,000, more preferably from 5,000 to 300,000, particularly preferably from 10,000 to 100,000.
5-100 degreeC is preferable, as for Tg of a fluoropolymer, 10-80 degreeC is more preferable, and 15-60 degreeC is especially preferable. When Tg is 5 ° C. or higher, the adhesion to the substrate is good, and when Tg is 100 ° C. or lower, the heat resistance of the coating film is good.

The fluorinated polymer preferably contains a unit having a hydroxyl group.
The fluorine-containing polymer is preferably a fluorine-containing polymer containing the following units (1) to (3) from the viewpoint of the weather resistance of the coating film and the adhesion to the substrate.
Unit (1): Unit based on fluoroolefin.
Unit (2): A unit based on a monomer having a hydroxyl group.
Unit (3): A unit based on a monomer having neither a fluorine atom nor a hydroxyl group.

A fluoroolefin is a compound in which one or more hydrogen atoms of the olefin are substituted with fluorine atoms.
2-8 are preferable and, as for carbon number of a fluoro olefin, 2-6 are more preferable.
The number of fluorine atoms in the fluoroolefin (hereinafter referred to as “fluorine substitution number”) is preferably 2 or more, and more preferably 3-4. If the fluorine substitution number is 2 or more, the weather resistance of the formed coating film is improved. In the fluoroolefin, one or more hydrogen atoms not substituted with fluorine atoms may be substituted with chlorine atoms.

Examples of the fluoroolefin include CF ₂ = CF ₂ , CF ₂ = CFCl, CF ₂ = CHF, CH ₂ = CF ₂ , CF ₂ = CFCF ₃ , CF ₂ = CHCF _{3 and the} like. Therefore, CF ₂ = CF ₂ or CF ₂ = CFCl is preferable, and CF ₂ = CFCl is more preferable.
The unit (1) may be one type or two or more types. The unit (1) is preferably a structural unit directly formed by polymerizing a fluoroolefin.

  Examples of the monomer having a hydroxyl group include hydroxyalkyl vinyl ether, polyalkylene glycol monovinyl ether, hydroxyalkyl allyl ether, hydroxyalkyl vinyl ester, polyalkylene glycol monoallyl ether, polyalkylene glycol monovinyl ester, hydroxyalkyl isopropenyl ether, hydroxycyclohexane. Examples thereof include alkyl vinyl ethers, hydroxyalkyl-substituted cycloalkyl vinyl ethers, and hydroxyalkyl (meth) acrylates. The hydroxyalkyl group is preferably a hydroxyalkyl group having 6 or less carbon atoms, and the polyalkylene glycol has 2 to 6 repeating units of the oxyalkylene group, and the oxyalkylene group has 2 or 3 carbon atoms. Certain polyalkylene glycols are preferred. The monomer having a hydroxyl group may be a monomer having two or more hydroxyl groups.

Specific examples of the monomer having a hydroxyl group include the following monomers.
Hydroxyalkyl vinyl ether: 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, 5- Hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether.
Polyalkylene glycol monovinyl ether: diethylene glycol monovinyl ether, triethylene glycol monovinyl ether, tetraethylene glycol monovinyl ether.
Hydroxyalkyl allyl ether: 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, glycerol monoallyl ether.
Hydroxyalkyl vinyl ester, other monomers: 2-hydroxyethyl vinyl ester, 4-hydroxybutyl vinyl ester, hydroxyethyl allyl ester, hydroxybutyl allyl ester, hydroxyethyl (meth) acrylate.

The monomer having a hydroxyl group is preferably hydroxyalkyl vinyl ether, more preferably 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether and 4-hydroxybutyl vinyl ether, 2-hydroxyethyl vinyl ether and 4-hydroxyethyl vinyl ether, and 4-hydroxybutyl vinyl ether. More preferred is hydroxybutyl vinyl ether.
The unit (2) may be one type or two or more types. The unit (2) is preferably a unit formed directly by polymerizing a monomer having a hydroxyl group.

The unit (3) is a unit based on a monomer having no fluorine atom and hydroxyl group.
The monomer preferably does not have a crosslinkable group such as a carboxy group, an epoxy group, an oxetane group and an alkoxysilyl group in addition to the hydroxyl group.
The monomer has neither a fluorine atom nor a hydroxyl group, vinyl ether, allyl ether, isopropenyl ether, carboxylic acid vinyl ester, carboxylic acid allyl ester, carboxylic acid isopropenyl ester, methallyl ether, carboxylic acid methallyl ester, An α-olefin, (meth) acrylate, and the like can be given.

As monomers having no fluorine atom and hydroxyl group, alkyl vinyl ethers, cycloalkyl vinyl ethers, carboxylic acid vinyl esters, alkyl allyl ethers and carboxylic acids having no fluorine atom and hydroxyl group are preferred because of their excellent copolymerizability with fluoroolefins. Preferred are allyl esters of acids, carboxylic acids which are derivatives of alkyl vinyl ethers having a linear, branched or alicyclic alkyl group having 1 to 10 carbon atoms and saturated fatty acids which may have branches having 12 or less carbon atoms. More preferred are vinyl esters.
The unit (3) may be one type or two or more types.

Specific examples of the monomer having no fluorine atom or hydroxyl group include the following monomers.
Ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, ethyl allyl ether, cyclohexyl allyl ether, methyl isopropenyl ether, Veover 10 (trade name, saturated fatty acid vinyl ester which is a derivative of C10 branched fatty acid, manufactured by Shell Chemicals Japan, Inc. ), Vinyl butyrate, vinyl acetate, vinyl pivalate, vinyl versatate, allyl propionate, allyl acetate, ethylene, propylene, isobutylene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate.

20-80 mol% is preferable and, as for content of the unit (1) with respect to all the structural units in the fluoropolymer in this invention, 30-70 mol% is more preferable. When the content of the unit (1) is at least the lower limit value, excellent weather resistance is easily obtained. If content of a unit (1) is below an upper limit, the adhesiveness to a base material is securable.
0.5-60 mol% is preferable and, as for content of the unit (2) with respect to all the structural units in a fluoropolymer, 1-50 mol% is more preferable. If content of a unit (2) is more than a lower limit, it will be easy to react with a hardening | curing agent and a tough coating film will be obtained. If content of a unit (2) is below an upper limit, the water resistance of a coating film will not fall easily.
0.5-60 mol% is preferable and, as for content of the unit (3) with respect to all the units in a fluoropolymer, 1-50 mol% is more preferable. If content of a unit (3) is more than a lower limit, the softness | flexibility of a coating film and the adhesiveness to a base material will become favorable. If content of a unit (3) is below an upper limit, there will be little influence on the weather resistance of a coating film.
A fluoropolymer may be used individually by 1 type, and may use 2 or more types together.

As a method for producing the fluorine-containing polymer, a method of copolymerizing a monomer mixture containing a fluoroolefin, a monomer having a hydroxyl group, and a monomer having no fluorine atom and hydroxyl group is preferable.
As the polymerization method, a radical polymerization method by the action of a radical polymerization initiator can be employed. As the polymerization form, solution polymerization, suspension polymerization, emulsion polymerization and the like can be employed. The reaction temperature in the polymerization is usually 0 to 130 ° C., and the reaction time is usually 1 to 50 hours.
Specific examples of the polymerization solvent in the polymerization include ion exchange water; alcohol such as ethanol, butanol and propanol; saturated hydrocarbon such as n-hexane and n-heptane; aromatic hydrocarbon such as toluene and xylene; methyl ethyl ketone and cyclohexanone. Ketones; and esters such as ethyl acetate and butyl acetate.

  Specific examples of the radical polymerization initiator include peroxydicarbonates such as diisopropyl peroxydicarbonate and di-n-propyl peroxydicarbonate; peroxydicarbonates such as t-hexyl peroxypivalate and t-butyl peroxypivalate. Oxyesters; ketone peroxides such as cyclohexanone peroxide and methyl ethyl ketone peroxide; peroxides such as 1,1-bis (t-hexylperoxy) cyclohexane and 1,1-bis (t-butylperoxy) cyclohexane Oxyketals; peroxycarbonate esters such as t-hexylperoxy-n-butyl carbonate and t-butylperoxy-n-propyl carbonate; diacyl peroxides such as isobutyryl peroxide and lauroyl peroxide; Peroxide, dialkyl peroxides such as di -t- butyl peroxide and the like.

  In the case of employing emulsion polymerization, the polymerization can be performed by the action of a polymerization initiator such as a water-soluble peroxide, a persulfate, or a water-soluble azo compound in water and in the presence of an anionic emulsifier and a nonionic emulsifier. In addition, since a trace amount of hydrochloric acid or hydrofluoric acid may be generated during the polymerization reaction, it is preferable to add a buffer in advance during the polymerization.

In the coating composition of the present invention, the content of the fluoropolymer is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, based on the solid content of the coating composition. If content of a fluoropolymer is 10 mass% or more, the weather resistance of a coating film will not fall easily. If the content of the fluorine-containing polymer is 80% by mass or less, it is easy to design a viscosity optimum for coating.
In addition, solid content of a coating composition means the composition except the component removed before hardening a coating composition, such as the below-mentioned organic solvent and an aqueous medium.

The (meth) acrylate polymer having a hydroxyl group in the present invention (hereinafter also simply referred to as “(meth) acrylate polymer”) has a Tg of 15 to 70 ° C. Since Tg is 15 ° C. or higher, the hardness of the coating film is increased and sufficient weather resistance is obtained. Therefore, even when used outdoors for a long time, cracks are unlikely to occur in the processed part. Moreover, since Tg is 70 degrees C or less, the hardness of a coating film does not become high too much and it is excellent in workability. As a result, cracks are unlikely to occur in the processed part even immediately after molding.
The lower limit of Tg of the (meth) acrylate polymer is 15 ° C. or higher, and is preferably 17 ° C., more preferably 20 ° C. or higher, and even more preferably 22 ° C. or higher from the viewpoint that the above effect is more exhibited.
The upper limit value of Tg of the (meth) acrylate polymer is 70 ° C. or less, preferably 67 ° C. or less, more preferably 65 ° C. or less, still more preferably 60 ° C. or less, from the point that the above effect is more exhibited. A temperature of 40 ° C. or lower is particularly preferable.

In the present invention, the absolute value of the difference between the Tg of the fluoropolymer and the Tg of the (meth) acrylate polymer is preferably within 30 ° C, more preferably within 25 ° C, and even more preferably within 20 ° C. When the absolute value of the difference is within the above range, the coating film formed from the coating composition is excellent in weather resistance, workability, and thermal cooling cycle properties. The lower limit of the difference between the two is not particularly limited, but may be 0 ° C.
When the Tg of the fluoropolymer and the Tg of the (meth) acrylate polymer are compared, the Tg of the (meth) acrylate polymer is superior to that of the fluoropolymer in terms of better weather resistance and workability of the coating film. It is preferable that it is higher than Tg of coalescence.

The Mn of the (meth) acrylate polymer in the present invention is preferably 3000 to 500,000, more preferably 5000 to 300,000, and particularly preferably 10,000 to 100,000.
In the present invention, the absolute value of the difference between Mn of the fluoropolymer and Mn of the (meth) acrylate polymer is within 5000, preferably within 4500, more preferably within 4000, and particularly preferably within 3000. Thereby, the compatibility between the fluoropolymer and the (meth) acrylate polymer is improved. As a result, a uniform coating film can be obtained, the followability of the coating film to the member is improved, and cracks are less likely to occur in the processed portion immediately after molding. Further, the weather resistance of the coating film is improved, and cracks are less likely to occur in the processed part even when used outdoors for a long period of time.

  The (meth) acrylate polymer in the present invention has a hydroxyl value of preferably 20 to 80 mgKOH / g, more preferably 21 to 77 mgKOH / g, and still more preferably 22 to 75 mgKOH / g. When the hydroxyl value of the (meth) acrylate polymer is in the above range, the compatibility with the fluoropolymer having a hydroxyl value in the numerical range described above is improved. As a result, a more uniform coating film is obtained, the followability of the coating film to the member is improved, and cracks are less likely to occur in the processed portion immediately after molding. Moreover, the weather resistance of a coating film improves and generation | occurrence | production of the crack in a process part can be suppressed also when used outdoors for a long period of time.

The (meth) acrylate polymer in the present invention is a unit based on hydroxyalkyl (meth) acrylate (hereinafter also referred to as unit b1) and a unit based on (meth) acrylate having no crosslinkable group (hereinafter referred to as unit). b2)). Thereby, the hardness of the coating film formed with a coating composition becomes high. In addition, the compatibility between the (meth) acrylate polymer and the fluoropolymer is improved, a more uniform coating film is obtained, and the followability of the coating film to the substrate is improved. Cracks are less likely to occur. Further, the weather resistance of the coating film is improved, and cracks are less likely to occur in the processed part even when used outdoors for a long period of time.
In addition, having no crosslinkable group means having no crosslinkable groups such as a hydroxyl group, a carboxy group, an epoxy group, an oxetane group, and an alkoxysilyl group.
In the case of the (meth) acrylate polymer containing the units b1 and b2, the content of the unit b1 is Y mol% and the content of the unit b2 is Z mol% with respect to all the units of the (meth) acrylate polymer. Then, the molar ratio (Y / Z) between the content of the unit b1 and the content of the unit b2 is preferably in the range of 1/99 to 30/70, more preferably 3/97 to 25/75. 95-20 / 80 is more preferable. Thereby, the processability of a coating film and the generation | occurrence | production of the crack in the process part immediately after shaping | molding by it, and the generation | occurrence | production of the crack in the process part at the time of using outdoors outdoors for a long time by the improvement of a weather resistance can be suppressed.

  Examples of the hydroxyalkyl (meth) acrylate include hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and the like. Since it is easy to obtain a polymer having physical properties such as Tg, hydroxyalkyl (meth) acrylate is preferably hydroxyalkyl methacrylate, and the coating film has high flexibility and the workability of the coated plate is better. Is particularly preferred.

As the (meth) acrylate having no crosslinkable group, an alkyl (meth) acrylate having an alkyl having 6 or less carbon atoms is preferable. Furthermore, it is more preferable that an alkyl (meth) acrylate having 1 or 2 carbon atoms and an alkyl (meth) acrylate having 3 to 6 carbon atoms are combined. In other words, the unit b2 in the (meth) acrylate polymer is a first unit based on an alkyl (meth) acrylate having 1 or 2 carbon atoms and a second unit based on an alkyl (meth) acrylate having 3 to 6 carbon atoms. More preferably, it consists of a combination with units.
In particular, as the unit b2 in the (meth) acrylate polymer, a first unit based on at least one (meth) acrylate selected from methyl (meth) acrylate and ethyl (meth) acrylate, and n-butyl ( It preferably consists of a combination with a second unit based on at least one (meth) acrylate selected from meth) acrylate, i-butyl (meth) acrylate and t-butyl (meth) acrylate.
From the viewpoint of easily obtaining a polymer having physical properties such as Tg, the alkyl (meth) acrylate is more preferably an alkyl methacrylate.
Furthermore, the first unit to the total units of the (meth) acrylate-based polymer and ^{Z 1} mol%, when the second unit was ^{Z 2} mole%, the molar ratio ^(Z 1 / ^{Z 2)} is 5 / 95 to 70/30 are preferred, 7/93 to 60/40 are more preferred, and 10/90 to 50/50 are even more preferred. Thereby, solvent solubility, compatibility with a fluorine-containing polymer, weather resistance of a coating film, adhesion, followability to a substrate, and the like are further improved.

In the coating composition, the content of the (meth) acrylate polymer is preferably 10 to 90% by mass and more preferably 20 to 80% by mass with respect to the solid content of the coating composition.
In the coating composition, the content ratio of the fluoropolymer to the (meth) acrylate polymer (content of fluoropolymer (mass%)) / (content of (meth) acrylate polymer (mass) %) Is preferably 90/10 to 30/70, more preferably 85/15 to 35/65, and still more preferably 80/20 to 40/60.

The coating composition of the present invention contains at least one curing agent selected from the group consisting of an isocyanate curing agent, a blocked isocyanate curing agent, and an amino resin.
Specific examples of the isocyanate curing agent include non-yellowing polyisocyanate and non-yellowing polyisocyanate modified. The isocyanate group of the isocyanate curing agent is not blocked.
Specific examples of the non-yellowing polyisocyanate include alicyclic polyisocyanates such as isophorone diisocyanate (IPDI) and dicyclohexylmethane diisocyanate (HMDI), and aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI).

Specific examples of the non-yellowing polyisocyanate-modified product include a diisocyanate isocyanurate, a diisocyanate polyol-modified product, a diisocyanate polyamine-modified product, a modified product obtained by modifying a part of the isocyanate group of the diisocyanate isocyanurate with a polyol, Examples thereof include a mixture of these modified products.
The blocked isocyanate curing agent is a curing agent in which the isocyanate group of the isocyanate curing agent is blocked with a blocking agent.
Examples of the blocking agent include epsilon caprolactam (E-CAP), methyl ethyl ketone oxime (MEK-OX), methyl isobutyl ketone oxime (MIBK-OX), pyralidine, triazine (TA) and the like.

Specific examples of the amino resin include melamine resin, guanamine resin, sulfoamide resin, urea resin, aniline resin and the like. Especially, a melamine resin is preferable from the point that a cure rate is quick. These resins have a reactive group such as a hydroxymethyl group bonded to a nitrogen atom of an amino group or an alkyl etherified hydroxymethyl group.
Specific examples of melamine resins include alkyl etherified melamine resins and the like. Especially, as a melamine resin, it is more preferable to consist of methylol melamine or its partial condensate by which the hydroxyl group was substituted by at least one of the methoxy group and the butoxy group.

In the coating composition, the content of the curing agent is preferably 1 to 40 parts by mass and more preferably 3 to 30 parts by mass with respect to 100 parts by mass of the fluoropolymer in the present invention. If content of a hardening | curing agent is more than a lower limit, a tough coating film will be easy to be obtained by sufficient bridge | crosslinking. If content of a hardening | curing agent is below an upper limit, it will be easy to suppress the foaming of the coating film by reaction with an isocyanate group and a water | moisture content.
A hardening | curing agent may be used individually by 1 type, or may use 2 or more types together.

The coating composition of the present invention may contain a pigment. The pigment 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 corrosion and alteration of the base material to which the coating composition is applied. Lead-free rust preventive pigments are preferred because of their low environmental impact. 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, iron oxide, moazo yellow, phthalocyanine blue, phthalocyanine green, and quinacridone red. For the purpose of further improving the weather resistance of the coating film, titanium oxide is preferably titanium oxide in which the pigment surface has been subjected to treatment for suppressing photocatalytic action. D918 (trade name, manufactured by Sakai Chemical Co., Ltd.), PFC 105 (product) Name, manufactured by Ishihara Sangyo Co., Ltd.)
The extender pigment is a pigment for improving the hardness of the coating film and increasing the thickness. Examples of extender pigments include talc, barium sulfate, mica, and calcium carbonate.
As the pigment component, titanium oxide is particularly preferable in terms of excellent weather resistance.

  When the coating composition of the present invention contains a pigment, the content of the pigment is usually 5 to 250% by mass with respect to the total content of the fluoropolymer and the (meth) acrylate polymer. , More than 30 mass% and 100 mass% or less is particularly preferable. If the pigment content is equal to or higher than the lower limit value, the pigment function (coating color, rust prevention, hardness, etc.) can be easily obtained. If the pigment content is equal to or lower than the upper limit value, the processability of the coating film ( The occurrence of cracks in the coating film) and hardness (abrasion resistance due to raindrop collision, etc.) are likely to be improved.

  The coating composition of the present invention may contain a curing catalyst for the purpose of promoting the crosslinking reaction. In particular, when curing at a low temperature in a short time, it is preferable to contain a curing catalyst. The curing catalyst accelerates the curing reaction of the fluoropolymer and enhances the chemical performance and physical performance of the coating film.

The coating composition of the present invention may contain an organic solvent or an aqueous medium. The organic solvent and the aqueous medium are used to improve the coating property of the coating composition. After removing the organic solvent and the aqueous medium from the coating film of the composition containing these and the uncured composition, the composition is cured. Let it be a cured film. The removal of the organic solvent and the aqueous medium is usually performed by evaporative removal by heating, and this evaporative removal may be performed in a separate process from the curing of the composition. Can also be done.
The coating composition of the present invention may be a powder coating composition that is a coating composition that does not contain an organic solvent or an aqueous medium.

  Specific examples of the organic solvent include aromatic hydrocarbons such as xylene and toluene, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, acetate esters such as butyl acetate and amyl acetate, propylene glycol alkyl ethers such as propylene glycol monomethyl ether, and the like. Is mentioned.

When the coating composition of this invention contains an organic solvent, 5-55 mass% is preferable and, as for content of the organic solvent with respect to the coating composition containing an organic solvent, 15-50 mass% is more preferable. If the content of the organic solvent is 5% by mass or more, the viscosity of the coating composition becomes lower and the coating operation becomes easier. If content of an organic solvent is 55 mass% or less, it will become easy to remove an organic solvent and to form a coating film.
One organic solvent may be used alone, or two or more organic solvents may be used in combination.

Examples of the aqueous medium include water alone or a medium containing water and a water-soluble solvent. Specific examples of the water-soluble solvent include alcohols such as methanol and ethanol. When a water-soluble solvent is contained as the aqueous medium, the content of the water-soluble solvent is preferably 10% by mass or less, and more preferably 5% by mass or less with respect to the total mass of the aqueous medium.
When the coating composition of this invention contains an aqueous medium, 5-55 mass% is preferable and, as for content of the aqueous medium with respect to the coating composition containing an aqueous medium, 15-50 mass% is more preferable. If content of an aqueous medium is 5 mass% or more, the viscosity of a coating composition will become lower and an application | coating operation | work will become easy. If content of an aqueous medium is 55 mass% or less, it will become easy to remove an aqueous medium and to form a coating film.

The curing catalyst is appropriately selected according to the type of the curing agent and the like. When the curing agent is an isocyanate curing agent or a blocked isocyanate curing agent, the curing catalyst is preferably a tin catalyst or a zirconium catalyst.
Specific examples of the tin catalyst include tin octylate, tributyltin dilaurate, dibutyltin dilaurate, and the like.
Specific examples of the zirconium catalyst include zirconium chelate. Examples of commercially available zirconium catalysts include “K-KAT XC-4205” (trade name, manufactured by Enomoto Kasei Co., Ltd.).
When the curing agent is an amino resin, the curing catalyst is preferably a blocked acid catalyst.
Examples of the blocked acid catalyst include amine salts of various acids such as carboxylic acid, sulfonic acid, phosphoric acid, diethanolamine salt or triethylamine salt of p-toluenesulfonic acid, diethanolamine salt or triethylamine salt of dodecylbenzenesulfonic acid, etc. And higher alkyl-substituted sulfonic acid amine salts.

When the coating composition of the present invention contains a curing catalyst, the content of the curing catalyst is preferably 0.001 to 5.0 parts by mass with respect to 100 parts by mass of the curing agent. If the ratio of the curing catalyst is at least the lower limit value, the catalytic effect can be sufficiently obtained. If the ratio of a curing catalyst is below an upper limit, it will be easy to suppress that a curing catalyst remains and it affects a coating film and water resistance falls.
One curing catalyst may be used alone, or two or more curing catalysts may be used in combination.

The coating composition of the present invention may contain a light stabilizer, an ultraviolet absorber, a surfactant, a silane coupling agent, a pigment dispersant, and the like.
Examples of the light stabilizer include hindered amine light stabilizers.
Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, triazine compounds, cyanoacrylate compounds, and the like.
If the coating composition contains a surfactant, the surface tension of the coating composition can be controlled, which is effective in adjusting the surface concentration of a specific component.
As the surfactant, any of a nonionic surfactant, a cationic surfactant, and an anionic surfactant may be used.

If the coating composition contains a silane coupling agent, it is easy to form a coating film with good adhesion to the substrate.
Examples of the silane coupling agent include a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, a vinyl group, an amino group, a (meth) acryloyl group, a styryl group, a mercapto group, and an isocyanate group. A silane coupling agent having an epoxy group is preferred.

  Examples of the pigment dispersant include an anionic compound, a cationic compound, a nonionic compound, and a polymer compound having a molecular weight of several thousand to several tens of thousands. The color floating property and color separation property of cyanine blue and carbon black are included. A compound having at least one selected from the group consisting of sulfate groups, sulfonate groups, phosphate groups and fatty acid amine bases is preferred.

The coating composition of the present invention is preferably produced by mixing a fluorine-containing polymer, a (meth) acrylate polymer, and a curing agent and, if necessary, mixing the above-described components other than these. The order of mixing each component is not particularly limited.
Examples of the mixing method include a method of mixing using a ball mill, a paint shaker, a sand mill, a jet mill, a rocking mill, an attritor, a triple roll, a kneader.

The coated body of the present invention is a coated body having a coating film formed from the coating composition of the present invention on the surface of a substrate. The coating composition of the present invention may be a coating composition in which a fluorine-containing polymer, a (meth) acrylate polymer, and a curing agent are dissolved or dispersed in an organic solvent or an aqueous medium depending on the substrate and environment to be used. It may be a powder coating composition that does not contain an organic solvent and an aqueous medium.
As a base material, the base material which consists of heat-resistant materials, such as a metal material and inorganic materials other than a metal, is preferable. Examples of the metal material include iron, iron alloy, aluminum, and aluminum alloy. The surface of the substrate made of a metal material may be subjected to a surface treatment such as plating.
Examples of inorganic materials other than metal include building materials produced by high heat treatment of non-metallic raw materials such as clay, silica sand, and limestone. More specifically, glass plates, tiles, bricks, glass fiber reinforced cement plates Asbestos cement board, wood chip cement board, cement calcium silicate board, gypsum slag board and the like.
As the base material of the painted body, an architectural exterior member is preferable.
As the building exterior member, a building exterior member made of an inorganic material other than the above metal, also called a ceramic building material, is preferable.
The film thickness of a coating film is 10-100 micrometers normally, and 20-60 micrometers is preferable. If the film thickness of the coating film is equal to or greater than the lower limit value, the transparency of the coating film can be suppressed, and if the film thickness of the coating film is equal to or less than the upper limit value, it is possible to suppress a decrease in workability such as cracking of the coating film. is there. Such an effect is particularly prominent in an embodiment in which the coating composition of the present invention contains a pigment as another component.

Further, an undercoat layer and an intermediate coat layer may be included between the surface of the substrate and the coating film formed from the above-described coating composition.
Examples of the undercoat layer include epoxy paints, acrylic paints, polyester paints and the like from the viewpoint of adhesion to the base material and base material protection.
The intermediate layer includes adhesion between the undercoat layer and the topcoat layer, relaxation of the shrinkage stress between the undercoat layer and the topcoat layer, dispersibility of pigments and pigments for producing a color, UV light passing through the topcoat layer From the viewpoint of weather resistance, acrylic paints, polyvinylidene fluoride paints, silicone paints, acrylic silicone paints and the like can be mentioned.
For example, the building exterior material preferably has an undercoat layer of an epoxy paint, an intermediate coat layer of an acrylic paint, and a coating film formed from the paint composition of the present invention.

The coated body can be produced by applying the coating composition to the surface of the substrate and then curing the formed coating layer to form a coating film.
The coating composition may be applied directly to the surface of the substrate, or may be applied after applying a known surface treatment (undercoating, intermediate coating, ground treatment, etc.) to the surface of the substrate.
Examples of the method for applying the coating composition include a method using a coating apparatus such as a brush, a roller, dipping, spraying, a roll coater, a die coater, an applicator, a spin coater, and an electrostatic coating machine.
The curing temperature is preferably room temperature to 250 ° C, more preferably 50 to 200 ° C. When the coating composition contains a volatile component such as an organic solvent, it is removed before the heating.
Examples of the heating method for heating the coating layer include a method using a sealed curing furnace, a tunnel furnace capable of continuous curing, and the like. As the heating source, hot air circulation, infrared heating, high-frequency heating or the like can be adopted. The heating method is preferably a tunnel furnace from the viewpoint of continuous productivity. The heat source is preferably hot air circulation or infrared heating from the viewpoint that the heat conduction is uniform and a uniform coating film is easily obtained.

  EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In the following description, unless otherwise specified, the component ratio indicates “mass%” as simply “%”.

<Production of fluoropolymer>
[Example 1]
In a pressure resistant reactor with a stainless steel stirrer having an internal volume of 2500 mL, 590 g of xylene, 170 g of ethanol, 129 g of 4-hydroxybutyl vinyl ether, 206 g of ethyl vinyl ether, 208 g of cyclohexyl vinyl ether, 11 g of calcium carbonate, Then, 3.5 g of perbutyl perpivalate was charged, and dissolved oxygen in the liquid was removed by deaeration with nitrogen.
Next, 660 g of CF ₂ = CFCl was introduced, the temperature was gradually raised, and the reaction was continued while maintaining the temperature at 65 ° C. After reacting for 10 hours, the reaction was stopped by cooling the reactor with water. After cooling the reaction solution to room temperature, unreacted monomers were purged, and the resulting reaction solution was filtered through diatomaceous earth to remove solids. Next, a part of xylene and ethanol were removed by distillation under reduced pressure to obtain a xylene solution of a fluoropolymer 1 containing a hydroxyl group (nonvolatile content 60%, Mn 15000). Further, the xylene solution of fluoropolymer 1 was dried, and the hydroxyl value and Tg of fluoropolymer 1 were measured. As a result, the hydroxyl value was 52.0 mgKOH / g and Tg was 35 ° C.

<Production of methacrylate polymer>
[Example 2]
Into a 500 ml four-necked flask equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, 160 parts by mass of xylene was charged and heated to 80 ° C. while stirring. Next, at a temperature of 80 ° C., 23.9 parts by mass of hydroxyethyl methacrylate (hereinafter also referred to as HEMA), 36.7 parts by mass of methyl methacrylate (hereinafter also referred to as MMA), n-butyl methacrylate (hereinafter also referred to as n-BMA). 139.4 parts by mass, peroxide-based polymerization initiator (manufactured by NOF Corporation, “Perhexyl O (trademark, purity 93%)”, hereinafter also referred to as initiator) 11 parts by mass, xylene 29 A mass part previously mixed uniformly was dropped at a constant speed with a dropping funnel over 2 hours. After completion of the dropwise addition, the temperature of 100 ° C. was maintained for 5 hours, and then the resulting reaction solution was filtered through diatomaceous earth to obtain a xylene solution of methacrylate polymer 1 containing a hydroxyl group (nonvolatile content: 50%, Mn 13000). .
Further, the xylene solution of the methacrylate polymer 1 was dried, and the hydroxyl value and Tg of the methacrylate polymer 1 were measured. As a result, the hydroxyl value was 51.8 mgKOH / g and Tg was 36.5 ° C. In addition, ¹ H-NMR analysis confirmed that the methacrylate polymer 1 contains 12 mol%, 24 mol%, and 64 mol% in this order of units based on HEMA, units based on MMA, and units based on n-BMA. did.

[Example 3]
Into a 500 ml four-necked flask equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, 160 parts by mass of xylene was charged and heated to 80 ° C. while stirring. Next, at a temperature of 80 ° C., 20.6 parts by mass of HEMA, 96.0 parts by mass of ethyl methacrylate (hereinafter also referred to as EMA), 83.4 parts by mass of i-butyl methacrylate (hereinafter also referred to as i-BMA), initiator 8 parts by mass and xylene 32 parts by mass were mixed in advance and dropped at a constant rate with a dropping funnel over 2 hours. After completion of the dropping, the temperature of 100 ° C. was maintained for 5 hours, and then the obtained reaction solution was filtered through diatomaceous earth to obtain a xylene solution of methacrylate polymer 2 containing a hydroxyl group (nonvolatile content: 50%, Mn 19000). .
Further, the xylene solution of the methacrylate polymer 2 was dried, and the hydroxyl value and Tg of the methacrylate polymer 2 were measured. As a result, the hydroxyl value was 43.2 mgKOH / g and Tg was 56.7 ° C. Moreover, it is confirmed by ¹ H-NMR analysis that the methacrylate polymer 2 contains 10 mol%, 53 mol%, and 37 mol% in this order of units based on HEMA, units based on EMA, and units based on i-BMA. did.

[Example 4]
In a 500 ml four-necked flask equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, 160 parts by mass of xylene was charged and heated with stirring to 80 ° C. Next, at a temperature of 80 ° C., 14.3 parts by mass of HEMA, 179.3 parts by mass of i-BMA, 8 parts by mass of initiator, and 32 parts by mass of xylene were previously mixed uniformly at a constant speed with a dropping funnel over 2 hours. It was dripped. After completion of the dropwise addition, the temperature of 100 ° C. was maintained for 5 hours, and then the resulting reaction solution was filtered through diatomaceous earth to obtain a xylene solution of methacrylate polymer 3 containing a hydroxyl group (nonvolatile content: 50%, Mn 19000). .
Further, the xylene solution of the methacrylate polymer 3 was dried, and the hydroxyl value and Tg of the methacrylate polymer 3 were measured. As a result, the hydroxyl value was 60.5 mgKOH / g and Tg was 97.1 ° C. Further, ¹ H-NMR analysis confirmed that the methacrylate polymer 3 contained 11 mol% and 89 mol% in this order of units based on HEMA and units based on i-BMA.

[Example 5]
In a 500 ml four-necked flask equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, 160 parts by mass of xylene was charged and heated with stirring to 80 ° C. Next, at a temperature of 80 ° C., HEMA 24.0 parts by mass, MMA 38.4 parts by mass, t-butyl methacrylate (hereinafter also referred to as t-BMA) 137.6 parts by mass, initiator 6 parts by mass, and xylene 34 parts by mass What was previously mixed uniformly was dropped at a constant speed with a dropping funnel over 2 hours. After completion of the dropwise addition, the temperature of 90 ° C. was maintained for 5 hours, and the resulting reaction solution was filtered through diatomaceous earth to obtain a xylene solution of methacrylate polymer 4 containing a hydroxyl group (nonvolatile content: 50%, Mn 22000). .
Further, the xylene solution of the methacrylate polymer 4 was dried, and the hydroxyl value and Tg of the methacrylate polymer 4 were measured. As a result, the hydroxyl value was 51.8 mgKOH / g and Tg was 99.5 ° C. Moreover, it is confirmed by ¹ H-NMR analysis that the methacrylate polymer 4 contains 12 mol%, 25 mol%, and 63 mol% in this order of units based on HEMA, units based on MMA, and units based on t-BMA. did.

The solid content concentration was determined by measuring the heating residue according to JIS K 5601-1-2 (established in 2009).
The number average molecular weight (Mn) was measured by GPC (HLC-8220, manufactured by Tosoh Corporation). Tetrahydrofuran was used as a developing solvent, and polystyrene was used as a standard substance.
The glass transition temperature (Tg) was measured using a thermal analyzer DSC (manufactured by Seiko Instruments Inc.) under a nitrogen atmosphere under a temperature increase rate of 10 ° C./min.
The structures of the methacrylate polymers 1 to 4 produced in Examples 2 to 5 are summarized in the following table.
In the description in the table, “first unit” refers to the first unit of the unit b2, and “second unit” refers to the second unit of the unit b2. Specific units are indicated by abbreviations of monomers. The “Mn difference” means the absolute value of the difference between Mn (15000) of the fluoropolymer and Mn of the methacrylate polymers 1 to 4.

<Manufacture of coating composition>
In the production of the coating composition, a titanium oxide pigment (manufactured by Sakai Chemical Co., Ltd., trade name “D-918”), a curing agent (HDI isocyanurate, product of Nippon Polyurethane Co., Ltd., trade name “Coronate HX”), A curing catalyst (a solution of dibutyltin dilaurate diluted 4 to 10 times with xylene) was further used.
[Example 6]
To 50.1 g of xylene solution of fluoropolymer 1 (nonvolatile content 60%) and 30.1 g of methacrylate polymer 1 (nonvolatile content 50%), add 200 g of titanium oxide pigment, 105.7 g of xylene, and 105.7 g of butyl acetate. Further, 369 g of glass beads having a diameter of 1 mm were added, and the mixture was stirred with a paint shaker for 2 hours. After stirring, filtration was performed to remove the glass beads to obtain a pigment composition.
Next, to 100 g of the pigment composition, 96.5 g of a xylene solution of fluoropolymer 1 (nonvolatile content: 60%), 49.6 g of methacrylate polymer 1, 18.7 g of xylene, and 16.5 g of a curing agent, Further, 5.4 g of a curing catalyst was further added and mixed to obtain a coating composition I.

[Example 7]
To 58.5 g of xylene solution of fluoropolymer 1 (nonvolatile content 60%) and 36.1 g of methacrylate polymer 2 (nonvolatile content 50%), add 200 g of titanium oxide pigment, 102.7 g of xylene, and 102.7 g of butyl acetate. Further, 369 g of glass beads having a diameter of 1 mm were added, and the mixture was stirred with a paint shaker for 2 hours. After stirring, filtration was performed to remove the glass beads to obtain a pigment composition.
Next, to 100 g of the pigment composition, 96.5 g of a xylene solution of fluoropolymer 1 (nonvolatile content: 60%), 59.5 g of methacrylate polymer 2, 8.8 g of xylene, and 16.5 g of curing agent. And 5.4 g of the curing catalyst were further added and mixed to obtain a coating composition II.

[Example 8]
To 55.9 g of xylene solution of fluoropolymer 1 (nonvolatile content 60%) and 25.9 g of methacrylate polymer 3 (nonvolatile content 50%), add 200 g of titanium oxide pigment, 107.8 g of xylene, and 107.8 g of butyl acetate. Further, 369 g of glass beads having a diameter of 1 mm were added, and the mixture was stirred with a paint shaker for 2 hours. After stirring, filtration was performed to remove the glass beads to obtain a pigment composition.
Next, to 100 g of the pigment composition, 96.5 g of a xylene solution of fluoropolymer 1 (nonvolatile content: 60%), 42.7 g of methacrylate polymer 3, 25.6 g of xylene, and 16.5 g of curing agent, Further, 5.4 g of a curing catalyst was added and mixed to obtain a coating composition III.

[Example 9]
To 58.5 g of a xylene solution of fluoropolymer 1 (nonvolatile content 60%) and 30.1 g of acrylic resin 4 (nonvolatile content 50%), 200 g of titanium oxide pigment, 105.7 g of xylene, and 105.7 g of butyl acetate were added. Further, 369 g of glass beads having a diameter of 1 mm were added, and the mixture was stirred for 2 hours with a paint shaker. After stirring, filtration was performed to remove the glass beads to obtain a pigment composition.
Next, to 100 g of the pigment composition, 96.5 g of a xylene solution of fluoropolymer 1 (nonvolatile content: 60%), 49.6 g of methacrylate polymer 4, 18.7 g of xylene, and 16.5 g of curing agent, Further, 5.4 g of a curing catalyst was added and mixed to obtain a coating composition IV.

<Preparation of paint plate and its evaluation>
The coating composition I to IV is applied to the surface of the chromate-treated aluminum plate so that the thickness of the coating film after drying is 40 μm, and is cured in a constant temperature room at 25 ° C. for 1 week. Formed to obtain a test plate with a coating film, respectively.
About each test plate with a coating film, the workability of a coating film and the weather resistance test of a process part coating film were done.

[Evaluation method]
(Processability)
In accordance with JIS K 5600-5-1 (flexibility, cylindrical mandrel method), evaluation was performed according to the following criteria.
That is, the evaluation was performed using a 2 mm mandrel using a cylindrical mandrel bending tester manufactured by Allgood.
○: Cracking of the coating film and peeling of the coating film were not observed.
(Triangle | delta): The crack of a coating film was confirmed a little at the edge part of a test plate.
X: The crack of the coating film and peeling of the coating film were confirmed on the whole surface of the processed part.
(Accelerated weather resistance test)
Using an accelerated weathering tester (manufactured by Q-PANEL LAB PRODUCTS, model: QUV / SE), the presence or absence of coating film cracking and coating film peeling after exposure for 5000 hours was evaluated according to the following criteria.
○: Cracking of the coating film and peeling of the coating film were not observed.
(Triangle | delta): The crack of a coating film was confirmed a little at the edge part of a test plate.
X: The crack of the coating film and peeling of the coating film were confirmed on the whole surface of the processed part.
(Actual exposure test)
A test plate with a coating film was installed outdoors in Naha City, Okinawa Prefecture, and the presence or absence of coating film peeling after one year was evaluated according to the following criteria.
○: Cracking of the coating film and peeling of the coating film were not observed.
(Triangle | delta): The crack of a coating film was confirmed a little at the edge part of a test plate.
X: The crack of the coating film and peeling of the coating film were confirmed on the whole surface of the processed part.
The results are summarized in the following table.

<Preparation of painted plate and its evaluation (2)>
The coating composition is the same as the coating composition I except that the content of the titanium oxide pigment in the coating composition I (the content of the titanium oxide pigment is 33% by mass relative to the total mass of the fluoropolymer and the methacrylate polymer) is changed. Composition I-1 (content of the titanium oxide pigment 110% by mass) and coating composition I-2 (content of the titanium oxide pigment 10% by mass) were prepared. As a result of evaluating the coated plates obtained from the respective coating compositions, it was found that the coating composition I-1 was inferior to that of the coating composition I in terms of processability and accelerated weathering test, and equivalent to that of the coating composition II. Met. The coated plate of the coating composition I-2 had an evaluation result equivalent to that of the coating composition I, but was inferior in the effect (coloring effect of the coating film) by the pigment blending.

<Preparation of painted plate and its evaluation (Part 3)>
The coating composition I was applied so that the film thickness of the coating film after drying was 15 μm, 45 μm, and 75 μm, respectively, to obtain coated plates having different film thicknesses obtained from the coating composition I. As a result of evaluating each coated plate, the coated plate having a film thickness of 75 μm had lower workability compared to that having a film thickness of 45 μm, and was equivalent to that of the coating composition II. The coated plate with a film thickness of 15 μm had an evaluation result equivalent to that with a film thickness of 45 μm, but was inferior in the effect of pigment blending (coloring effect of the coating film).

As shown in Table 2, the coating compositions (I, II) of the examples, particularly the coating composition (I), were excellent in the processability of the coating film. Moreover, it was confirmed by the accelerated test and the actual exposure test that the weather resistance is excellent. Furthermore, in the coating composition I, it was confirmed that a coating film having further excellent workability can be formed by controlling the blending amount of the pigment or the film thickness of the coating film to be formed.
In addition, the entire contents of the specification, claims and abstract of Japanese Patent Application No. 2015-235684 filed on December 2, 2015 are incorporated herein as the disclosure of the specification of the present invention. It is.

Claims (12)

A fluorine-containing polymer having a hydroxyl group having a hydroxyl value of 5 to 100 mgKOH / g, a (meth) acrylate polymer having a hydroxyl group having a glass transition temperature of 15 to 70 ° C., an isocyanate curing agent, and a blocked isocyanate A coating composition containing at least one curing agent selected from the group consisting of a system curing agent and an amino resin,
The coating composition whose absolute value of the difference of the number average molecular weight of the said fluoropolymer and the number average molecular weight of the said (meth) acrylate type polymer is 5000 or less.   The coating composition of Claim 1 whose hydroxyl value of the said (meth) acrylate type polymer is 20-80 mgKOH / g.   The coating composition according to claim 1 or 2, wherein the absolute value of the difference between the glass transition temperature of the fluoropolymer and the glass transition temperature of the (meth) acrylate polymer is within 30 ° C. The (meth) acrylate polymer has a unit based on hydroxyalkyl (meth) acrylate and a unit based on (meth) acrylate having no crosslinkable group,
The content of units based on hydroxyalkyl (meth) acrylate with respect to the total amount of units based on monomer was Y mol%, and the content of units based on (meth) acrylate having no crosslinkable group was Z mol%. The coating composition according to any one of claims 1 to 3, which is a polymer having a Y / Z (molar ratio) in the range of 1/99 to 30/70.   The coating composition according to claim 4, wherein the (meth) acrylate having no crosslinkable group is an alkyl (meth) acrylate having an alkyl group having 6 or less carbon atoms. A unit based on (meth) acrylate having no crosslinkable group is a first unit based on at least one alkyl (meth) acrylate selected from methyl (meth) acrylate and ethyl (meth) acrylate, and n A combination with a second unit based on at least one alkyl (meth) acrylate selected from butyl (meth) acrylate, i-butyl (meth) acrylate and t-butyl (meth) acrylate,
Z ¹ / Z ² (molar ratio) when the content of the first unit is Z ¹ mol% and the content of the second unit is Z ² mol% with respect to the total amount of units based on the monomer The coating composition of Claim 4 which exists in the range of 5 / 99-70 / 30.   The coating composition according to claim 5 or 6, wherein the alkyl (meth) acrylate is an alkyl methacrylate.   The coating composition of any one of Claims 1-7 whose glass transition temperature of the said (meth) acrylate type polymer is 15-40 degreeC. In addition, it contains a pigment component,
Content of the said pigment component is any one of Claims 1-8 which are more than 30 masses and 100 mass% or less with respect to the total content of the said fluoropolymer and the said (meth) acrylate type polymer. The coating composition as described in 2.   The coating body which has a cured coating film formed from the coating composition of any one of Claims 1-9.   The coating body of Claim 10 whose base material of the said coating body is a building exterior member.   The coating body of Claim 10 or 11 whose film thickness of the said cured coating film is 20-60 micrometers.