JP6619413B2 - Coating composition and coating film - Google Patents

Description

  The present invention relates to a coating composition and a coating film.

Conventionally, coating films provided on articles such as exterior building materials used outdoors are required to have contamination resistance and acid resistance in order to prevent contamination due to rain (rain stains) and deterioration due to acid rain. On the other hand, as a method for obtaining a coating film having excellent stain resistance, various methods for hydrophilizing the coating film surface have been proposed.
For example, Patent Document 1 below discloses a coating composition containing a silicate-based material, and Patent Document 2 below discloses a coating composition containing a sulfonium-based material. In these coating compositions, the silicate material or the sulfonium-based material hydrophilizes the surface of the coating film formed from the coating composition and improves the stain resistance of the coating film.

JP 2014-198800 A Japanese Patent Laying-Open No. 2015-189889

  However, when a coating composition containing a silicate material is used as in the coating composition disclosed in Patent Document 1, in order for the coating film to exhibit hydrophilicity, the hydrolysis reaction of the silicate material Since it is necessary, the hydrophilicity (initial hydrophilicity) immediately after the formation of the coating film with insufficient hydrolysis reaction and the contamination resistance associated therewith were insufficient. In addition, if a coating composition containing a silicate material is used to form a coating film, the drying furnace is contaminated by volatile substances generated by the detachment or condensation reaction of the silicate material during baking and drying of the coating composition. There was also a problem of so-called (so-called “sag” problem).

  In addition, when a coating composition containing a sulfonium-based material is used, as in the coating composition disclosed in Patent Document 2, the formed coating film has good initial hydrophilicity, but the time-dependent (outdoor long-term Exposure) caused the sulfonium-based material to flow out, resulting in a decrease in hydrophilicity and the inability to maintain stain resistance.

Therefore, the present invention solves the above-mentioned problems of the prior art, can express and maintain stain resistance from the initial stage for a long time, and can further form a coating film having excellent acid resistance. It is an issue to provide.
Moreover, this invention makes it a further subject to provide the coating film which can express and maintain stain resistance over the long term from the beginning, and also is excellent in acid resistance.

  The gist configuration of the present invention that solves the above problems is as follows.

The coating composition of the present invention comprises at least one organic resin (A) selected from the group consisting of polyester resins, fluororesins and acrylic resins,
A copolymer resin (B) obtained by polymerizing a mixture containing an amino group or a quaternary ammonium base-containing polymerizable unsaturated monomer (b1) and another polymerizable unsaturated monomer (b2); Containing,
The solid content mass ratio (A / B) between the organic resin (A) and the copolymer resin (B) is 97/3 to 70/30,
In the copolymer resin (B), the ratio of the amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (b1) in the monomer constituting the copolymer resin (B) is 40. It is -90 mass%.
By using such a coating composition of the present invention for the formation of a coating film, it is possible to develop and maintain stain resistance from the initial stage over a long period of time, and furthermore, it is possible to form a coating film having excellent acid resistance.

［式中、Ｒ^１は水素又はメチル基であり、Ｒ^２は炭素数８〜１８の置換又は無置換のアルキル基である］で表わされる（メタ）アクリル酸アルキルエステルである。この場合、塗料組成物から形成される塗膜の、初期から長期に亘っての耐汚染性を更に向上させることができる。 In a preferred example of the coating composition of the present invention, the other polymerizable unsaturated monomer (b2) is represented by the following general formula (1):

[Wherein, R ¹ is hydrogen or a methyl group, and R ² is a substituted or unsubstituted alkyl group having 8 to 18 carbon atoms]. In this case, the stain resistance of the coating film formed from the coating composition can be further improved from the beginning to the long term.

  The coating composition of the present invention preferably further contains a curing agent (C). In this case, the acid resistance of the coating film formed from the coating composition can be further improved.

  The coating composition of the present invention is preferably for precoated metal. In this case, it is possible to produce a pre-coated metal (painted steel plate) that can express and maintain stain resistance from the initial stage over a long period of time and that is also excellent in acid resistance.

  Moreover, the coating film of this invention was formed using the said coating composition. Such a coating film of the present invention can develop and maintain stain resistance from the beginning to the long term, and is also excellent in acid resistance.

ADVANTAGE OF THE INVENTION According to this invention, the coating composition which can express and maintain stain resistance over the long term from the initial stage, and can form the coating film which is excellent also in acid resistance can be provided.
Further, according to the present invention, it is possible to provide a coating film that can express and maintain the stain resistance from the initial stage over a long period of time and further has excellent acid resistance.

  Below, the coating composition and coating film of this invention are illustrated and demonstrated in detail based on the embodiment.

<Coating composition>
The coating composition of the present invention comprises at least one organic resin (A) selected from the group consisting of a polyester resin, a fluororesin and an acrylic resin, an amino group or a quaternary ammonium base-containing polymerizable unsaturated monomer ( b1) and a copolymer resin (B) obtained by polymerizing a mixture containing another polymerizable unsaturated monomer (b2), and the organic resin (A) and the copolymer resin. (B) The solid content mass ratio (A / B) is 97/3 to 70/30, and the copolymer resin (B) is a monomer constituting the copolymer resin (B). The ratio of the amino group or the quaternary ammonium base-containing polymerizable unsaturated monomer (b1) is 40 to 90% by mass.

The coating composition of the present invention contains a specific organic resin (A) and a specific copolymer resin (B) in a solid content mass ratio (A / B) of 97/3 to 70/30, By setting the ratio of the amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (b1) in the monomer constituting the copolymer resin (B) in the range of 40 to 90% by mass. The coating film to be formed can be imparted with stain resistance and acid resistance, and the coating film to be formed can exhibit the stain resistance from the beginning, and further, it depends on the time (external long-term exposure). Since the decrease in hydrophilicity is suppressed, stain resistance can be expressed over a long period of time.
In addition, since the copolymer resin (B) does not require a hydrolysis reaction for the expression of hydrophilicity like a silicate-based material, it has hydrophilicity and stain resistance immediately after the formation of the coating film (from the beginning). In addition, since no volatile matter is generated during baking and drying of the coating composition, there is no so-called “smear” problem, and the drying furnace is not contaminated. Moreover, since the copolymer resin (B) does not flow out during outdoor exposure unlike the sulfonium-based material, the formed coating film is hydrophilic and resistant to contamination even after lapse of time (outdoor long-term exposure). High nature.

<< Organic Resin (A) >>
The coating composition of the present invention contains at least one organic resin (A) selected from the group consisting of a polyester resin, a fluororesin, and an acrylic resin. Polyester resins, fluororesins, and acrylic resins have a high degree of freedom in resin design. These organic resins may be used alone or in combination of two or more. The organic resin (A) is a resin different from the copolymer resin (B) described later, and has neither an amino group nor a quaternary ammonium base.

(Polyester resin)
The polyester resin is preferably a resin obtained by an ester reaction between a polybasic acid and a polyhydric alcohol.
Examples of the polybasic acid include terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, phthalic acid, maleic anhydride, tetrahydromaleic anhydride, hexahydrophthalic anhydride and other dibasic acids, trimellitic anhydride, methyl Trivalent or higher polybasic acids such as hydroexcentricarboxylic acid and pyromellitic anhydride are used, and these may be used in combination.
Examples of the polyhydric alcohol include aliphatic or alicyclic such as ethylene glycol, propylene glycol, diethylene glycol, butanediol, neopentyl glycol, 3-methylpentadiol, 1,4-hexanediol, and 1,6-hexanediol. A dihydric alcohol is mainly used, and if necessary, a trihydric or higher polyhydric alcohol such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol may be used in combination. Esterification of polybasic acid and polyhydric alcohol can be performed by a known method.

The number average molecular weight of the polyester resin is preferably in the range of 1,000 to 30,000. When the number average molecular weight is within the above range, the mechanical strength of the coating film is maintained, and the viscosity of the coating composition is maintained moderately, so that the paintability is excellent. From this viewpoint, the number average molecular weight of the polyester resin is more preferably 2,000 to 20,000, still more preferably 2,000 to 15,000.
In addition, in this invention, a number average molecular weight is the value which converted the measured value by the gel permeation chromatography (GPC) method by the polystyrene standard. The number average molecular weight of each resin described later is also measured in the same manner.

  When a polyester resin is used as the organic resin (A), the content of the polyester resin in the solid content of the coating composition is preferably 20 to 90 from the viewpoint of the balance between physical properties of the coating film such as processability and weather resistance. It is 30 mass%, More preferably, it is 30-70 mass%.

(Fluorine resin)
The fluororesin may be a thermoplastic fluororesin or a thermosetting fluororesin. The fluororesin can be obtained by homopolymerization of fluorine-containing monomers such as tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, trifluoroethylene, vinyl fluoride, vinylidene fluoride, or copolymerization with other monomers. All of the fluoropolymers are included. Among these, polyvinyl fluoride and polyvinylidene fluoride are preferable, and polyvinylidene fluoride is more preferable from the viewpoint of obtaining a coating film that is excellent in stain resistance, weather resistance, and corrosion resistance and maintains the stain resistance for a long period of time. Polyvinylidene fluoride is a polymer of vinylidene fluoride, and is obtained, for example, by polymerization using a radical polymerization initiator or the like under high temperature and pressure. The weight average molecular weight of the polyvinylidene fluoride is preferably 300,000 to 700,000.

  A commercially available product may be used as the fluororesin. Examples of commercially available products include Kyner 500 (thermoplastic polyvinylidene fluoride) manufactured by Arkema Inc., Hylar 5000 (polyvinylidene fluoride) manufactured by Solvay Solexis, and Lumiflon 200 manufactured by Asahi Glass Co., Ltd. (thermosetting fluorine). Resin) and the like.

  When the fluororesin is used as the organic resin (A), the content of the fluororesin in the solid content of the coating composition is preferably 30 to 90% by mass, more preferably from the viewpoint of the balance between workability and weather resistance. Is 40-70 mass%.

(acrylic resin)
There is no restriction | limiting in particular as said acrylic resin, Arbitrary acrylic resins can be used. Examples of the monomer component constituting the acrylic resin include aromatic vinyl monomers such as styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene, and chlorostyrene; methyl (meth) acrylate, (meth) acrylic acid n-propyl, isopropyl (meth) acrylate, n-, i- or t-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate C1-C18 alkyl ester or cycloalkyl ester of (meth) acrylic acid such as decyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate; 2-hydroxy (meth) acrylate Ethyl, 2-hydroxypropyl (meth) acrylate, 3- (meth) acrylic acid 3- C2-C8 hydroxyalkyl ester of (meth) acrylic acid such as droxypropyl, 4-hydroxybutyl (meth) acrylate; N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N Examples thereof include N-substituted (meth) acrylamide monomers such as methoxymethyl (meth) acrylamide; one or a mixture of two or more of (meth) acrylic acid, glycidyl (meth) acrylate, and the like.
An acrylic resin can be produced by polymerizing the monomer components by a conventional method such as solution polymerization or bulk polymerization.
In the present specification, “(meth) acrylic acid” refers to acrylic acid and / or methacrylic acid (hereinafter the same).

  The number average molecular weight of the acrylic resin is not particularly limited, but is preferably 1,000 to 200,000, more preferably 5,000, from the viewpoint of obtaining a coating film excellent in coating film hardness and weather resistance. To 100,000, more preferably 10,000 to 50,000.

  When an acrylic resin is used as the organic resin (A), the content of the acrylic resin in the solid content of the coating composition is preferably 20 to 90% by mass, more preferably from the viewpoint of the balance between processability and weather resistance. Is 30-70 mass%.

(Combination of polyvinylidene fluoride and acrylic resin)
As the organic resin (A), polyvinylidene fluoride and an acrylic resin may be used in combination. In this case, the acrylic resin serves as a binder between the polyvinylidene fluoride particles when the coating composition is applied to form a coating film, and is good for the baking condition of the coating film. It exhibits heat resistance, is easily compatible with molten polyvinylidene fluoride, and exhibits a good coating appearance. Here, the content of polyvinylidene fluoride with respect to 100% by mass of the total of polyvinylidene fluoride and acrylic resin is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, from the viewpoint of heat resistance and coating film appearance. is there. From the same viewpoint, the content of the acrylic resin with respect to 100% by mass of the total of the polyvinylidene fluoride and the acrylic resin is preferably 10 to 50% by mass, and more preferably 20 to 40% by mass.

<< Copolymer resin (B) >>
The coating composition of the present invention is obtained by polymerizing a mixture containing an amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (b1) and another polymerizable unsaturated monomer (b2). A copolymer resin (B) is contained. When the coating composition contains the copolymer resin (B), the hydrophilicity of the coating film formed from the coating composition is improved, and the stain resistance is improved.

  The copolymer resin (B) used in the coating composition of the present invention is a polymerizable unsaturated monomer containing the amino group or quaternary ammonium base in the monomer constituting the copolymer resin (B). The ratio of (b1) is 40 to 90% by mass, and preferably 50 to 80% by mass. When the ratio of the amino group or the quaternary ammonium base-containing polymerizable unsaturated monomer (b1) in the monomer constituting the copolymer resin (B) is less than 40% by mass, it is formed from the coating composition. Contamination resistance over a long period from the initial stage of the coating film cannot be sufficiently improved. On the other hand, when it exceeds 90% by mass, the acid resistance of the coating film is deteriorated.

で表わされる化合物が挙げられる。また、第４級アンモニウム塩基含有重合性不飽和単量体としては、下記一般式（３）：

で表わされる化合物が挙げられる。 Regarding the amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (b1), the amino group-containing polymerizable unsaturated monomer may be represented by the following general formula (2):

The compound represented by these is mentioned. Moreover, as a quaternary ammonium base containing polymerizable unsaturated monomer, the following general formula (3):

The compound represented by these is mentioned.

R ³ in the general formulas (2) and (3) is hydrogen or a methyl group, and R ⁴ is an alkylene group having 1 to 5 carbon atoms. Here, examples of the alkylene group include an ethylene group and a propylene group.
R ⁵ and R ⁶ in the general formula (2) are each independently an alkyl group having 1 to 8 carbon atoms, and R ⁵ , R ⁶ and R ⁷ in the general formula (3) are Each independently represents an alkyl group having 1 to 8 carbon atoms. Here, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group.
X ⁻ in the general formula (3) is a monovalent anion, and examples of the monovalent anion include Cl ⁻ , Br ⁻ , PF ₆ ⁻ , and BF ₄ ⁻ .

  Examples of the compound represented by the general formula (2) include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and N, N-di (meth) acrylate. Examples include propylaminoethyl, N, N-dibutylaminoethyl (meth) acrylate, and N, N-dimethylaminopropyl (meth) acrylate.

Examples of the compound represented by the general formula (3) include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and N, N-diacrylate (meth) acrylate. Tertiary amino group-containing polymerizable unsaturated compounds such as propylaminoethyl, N, N-dibutylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and methyl chloride, ethyl chloride, methyl And quaternary ammonium salts with alkyl halides such as bromide and ethyl bromide.
Moreover, as a compound represented by the said General formula (3), a commercial item can be utilized, for example, Kyoeisha Chemical Co., Ltd. light ester DQ-100 etc. are mentioned.

  The quaternary ammonium base-containing polymerizable unsaturated monomer (b1) other than the compound represented by the general formula (3) includes 2-vinylpyridine, 4-vinylpyridine, and morpholinyl (meth) acrylate. And quaternary ammonium salts of alkyl halides such as methyl chloride, ethyl chloride, methyl bromide and ethyl bromide.

  Regarding the monomer constituting the copolymer resin (B), the other polymerizable unsaturated monomer (b2) is the above-mentioned amino group or quaternary ammonium base-containing polymerizable unsaturated monomer ( There is no particular limitation as long as it is an unsaturated monomer having a polymerizable property other than b1). Examples of the polymerizable unsaturated monomer include (meth) acrylic acid ester, (meth) acrylic acid hydroxyalkyl ester, (meth) acrylamide monomer, and aromatic vinyl monomer. Examples of the (meth) acrylic acid ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, (meth) Hexyl acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, (meth ) Lignoceryl acrylate, cyclohexyl (meth) acrylate, and the like. Examples of the (meth) acrylic acid hydroxyalkyl ester include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like. Examples of the (meth) acrylamide monomer include (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, N-methylol (meth) acrylamide and the like. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluene, and the like.

  In the coating composition of the present invention, the other polymerizable unsaturated monomer (b2) is preferably a (meth) acrylic acid alkyl ester represented by the general formula (1). When the (meth) acrylic acid alkyl ester represented by the general formula (1) is used as the other polymerizable unsaturated monomer (b2), from the initial stage of the coating film formed from the coating composition over a long period of time. It is possible to further improve the stain resistance.

In the general formula (1), R ¹ is preferably hydrogen or a methyl group, and R ² is preferably a substituted or unsubstituted alkyl group having 8 to 18 carbon atoms. Here, examples of the alkyl group include 2-ethylhexyl group, lauryl group, myristyl group, palmityl group, stearyl group and the like. Examples of the substituent for the alkyl group include a hydroxyl group. In addition, since the carbon number of the alkyl group of (meth) acrylic acid alkyl ester (the carbon number of R ^{2 in} the general formula (1)) is 8 to 18, resistance from the initial stage of the coating film to a long period of time. Contamination is further improved.

  Examples of the compound represented by the general formula (1) include 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, and (meth) acrylic acid. Stearyl etc. are mentioned.

  The copolymer resin (B) preferably has a number average molecular weight of 500 to 100,000, and more preferably 1,000 to 50,000. If the number average molecular weight of the copolymer resin (B) is 500 or more, the coating film retention with respect to rainwater is improved, and if it is 100,000 or less, the organic resin (A) in the coating composition Compatibility is improved.

  The copolymer resin (B) is a mixture containing the above-mentioned amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (b1) and another polymerizable unsaturated monomer (b2). It can be produced by polymerization by a conventional method such as solution polymerization or bulk polymerization.

  In the coating composition of this invention, solid content mass ratio (A / B) of the said organic resin (A) and the said copolymer resin (B) is 97 / 3-70 / 30, and 95/5 It is preferable that it is -80/20. When the solid content mass ratio of the organic resin (A) to the copolymer resin (B) is too high (that is, when the ratio of the organic resin (A) is too high), from the initial stage of the coating film formed from the coating composition. The contamination resistance over a long period cannot be sufficiently improved. On the other hand, if the solid content mass ratio of the organic resin (A) to the copolymer resin (B) is too low (that is, if the ratio of the organic resin (A) is too low), the coating film formed from the coating composition Acid resistance deteriorates.

<< Curing agent (C) >>
The coating composition of the present invention preferably further contains a curing agent (C). When the coating composition contains the curing agent (C), the stain resistance, weather resistance, and corrosion resistance are further improved, and the effect of maintaining the stain resistance for a long time is further improved. Also, from the viewpoint of obtaining a coating film that is excellent in stain resistance, weather resistance, and corrosion resistance and maintains stain resistance over a long period of time, a combination of a polyester resin and a curing agent, and curing with a fluorine resin other than polyvinylidene fluoride The combined use with an agent is more preferable. Here, as a hardening | curing agent (C), a melamine resin, an isocyanate compound, etc. are mentioned, for example. This hardening | curing agent (C) may be used individually by 1 type, or may use 2 or more types together.

  When the coating composition of this invention contains the said hardening | curing agent (C), the solid content of a hardening | curing agent (C) becomes like this. Preferably it is 10-50 with respect to 100 mass parts of solid content of the said organic resin (A). Part by mass. When the solid content of the curing agent (C) is 10 parts by mass or more, the curability is sufficient, and when it is 50 parts by mass or less, the cured film is suppressed from becoming too hard, and is used as a coating film. Workability during molding is improved. From this viewpoint, the solid content of the curing agent (C) is more preferably 15 to 40 parts by mass, and still more preferably 20 to 30 parts by mass with respect to 100 parts by mass of the solid content of the organic resin (A). .

(Melamine resin)
The melamine resin is not particularly limited, and methylated melamine resin, butylated melamine resin, methyl / butyl mixed melamine resin, or the like can be used. A commercially available product may be used as the melamine resin. Examples of commercially available products include the Cymel series manufactured by Nippon Cytec Co., Ltd., the Uban series manufactured by Mitsui Chemicals, and the Sumimar series manufactured by Sumika Bayer Urethane Co., Ltd.

  The content of the melamine resin in the solid content of the coating composition is preferably 1 to 50% by mass, more preferably 2 to 40% by mass, from the viewpoint of the balance between processability and weather resistance.

  The number average molecular weight of the melamine resin is preferably 500 to 200,000, more preferably 800 to 10,000, and still more preferably 1,000 to 5,000, from the viewpoint of excellent hardness and weather resistance of the coating film. .

(Isocyanate compound)
The isocyanate compound is not particularly limited as long as it is a compound having at least two isocyanate groups in one molecule. For example, aliphatic diisocyanates such as hexamethylene diisocyanate (HMDI) and trimethylhexamethylene diisocyanate (TMDI); Alicyclic diisocyanates such as isophorone diisocyanate (IPDI); aromatic-aliphatic diisocyanates such as xylylene diisocyanate (XDI); aromatic diisocyanates such as tolylene diisocyanate (TDI) and 4,4-diphenylmethane diisocyanate (MDI) Hydrogenated diisocyanates such as dimer acid diisocyanate (DDI), hydrogenated TDI (HTDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), etc. Dimers, trimers, tetramers or higher polyisocyanates; adducts of these with polyhydric alcohols such as trimethylolpropane, water, or low molecular weight polyester resins. be able to.

In order to increase the stability of the resulting coating composition, the isocyanate compound is usually used as a blocked isocyanate compound in which a reactive group is blocked with an appropriate blocking agent. The blocking agent is not particularly limited, and examples thereof include oxime blocking agents such as methyl ethyl ketoxime, acetoxime, cyclohexanone oxime, acetophenone oxime, and benzophenone oxime; phenol blocking agents such as m-cresol and xylenol; methanol, ethanol Alcohol-based blocking agents such as butanol, 2-ethylhexanol, cyclohexanol, ethylene glycol monoethyl ether; lactam-based blocking agents such as ε-caprolactam; diketone-based blocking agents such as diethyl malonate and acetoacetate; Examples include mercaptan blocking agents such as thiophenol; urea blocking agents such as thiourea; imidazole blocking agents; carbamic acid blocking agents. Among these, a lactam blocking agent, an oxime blocking agent, and a diketone blocking agent are preferable from the viewpoint of increasing the temperature at which the blocking agent dissociates and extending the pot life of the coating composition.
The blocked isocyanate compound is obtained by reacting the isocyanate compound and the blocking agent until the free isocyanate group disappears by a conventional method. A commercially available product can be used as the blocked isocyanate compound. Commercially available products include, for example, the Death Module series manufactured by Sumika Bayer Urethane, the Bernock D series manufactured by DIC, the Takenate B series manufactured by Takeda Pharmaceutical Company Limited, and the Coronate 2500 series manufactured by Nippon Polyurethane Industry Co., Ltd. Can do.

(Combination of polyester resin and curing agent)
When a polyester resin is used as the organic resin (A), the melamine resin and the isocyanate compound are preferable as the curing agent (C).

  When using together the said polyester resin and the said melamine resin, Preferably solid content of a melamine resin is 10-50 mass parts with respect to 100 mass parts of solid content of a polyester resin. When the solid content is 10 parts by mass or more, curability is sufficient, and when it is 50 parts by mass or less, it is suppressed that the cured film becomes too stiff, and the workability at the time of molding when a coating film is formed. Will improve. From this viewpoint, the solid content of the melamine resin is more preferably 15 to 40 parts by mass, and still more preferably 20 to 30 parts by mass with respect to 100 parts by mass of the solid content of the polyester resin.

When the polyester resin and the isocyanate compound are used in combination, the compounding amount of the isocyanate compound may be an amount capable of providing an equivalent amount of isocyanate groups with respect to the hydroxyl value of the polyester resin. , 0.8 to 5.0 times the equivalent, and more preferably 1.0 to 2.5 times the equivalent. When the blending amount of the isocyanate compound is 0.8 times or more of the above equivalent, curability is improved, a coating film having sufficient hardness is obtained, and acid resistance, alkali resistance, and stain resistance are further improved. Moreover, if the compounding amount of the isocyanate compound is 5.0 times or less of the equivalent, sufficient effects corresponding to the added amount can be obtained, and the strength of the coating film designed based on the physical properties of the polyester resin, Physical properties such as hardness and workability can be sufficiently maintained, acid resistance and alkali resistance can be further improved, and yellowing and weather resistance of the coating film can be sufficiently maintained.
When the polyester resin and the isocyanate compound are used in combination, it is usually preferable to use a known tin compound such as dibutyltin laurate as a “catalyst” for promoting the reaction between the polyester resin and the isocyanate compound.

(Combination of fluorine resin and curing agent other than polyvinylidene fluoride)
When the fluororesin other than polyvinylidene fluoride is used as the organic resin (A), the melamine resin and the isocyanate compound are preferable as the curing agent (C). This hardening | curing agent (C) can form the coating film which has favorable heat resistance and external appearance by bridge | crosslinking fluororesins other than a polyvinylidene fluoride.
Here, the content of the fluororesin other than polyvinylidene fluoride with respect to the total of 100 mass% of the fluororesin other than polyvinylidene fluoride and the curing agent is preferably 30 to 90 mass%, more preferably from the viewpoint of heat resistance and appearance. It is 40-80 mass%. From the same viewpoint, the content of the curing agent with respect to 100% by mass in total of the fluororesin and the curing agent other than polyvinylidene fluoride is preferably 10 to 50% by mass, more preferably 20 to 40% by mass.

<< Solvent >>
The coating composition of the present invention may contain a solvent. Examples of the solvent include water; ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, Glycol organic solvents such as dipropylene glycol monoethyl ether and propylene glycol monomethyl ether acetate; Alcohol organic solvents such as methanol, ethanol, isopropyl alcohol, isobutanol and benzyl alcohol; Ether organic solvents such as dioxane and tetrahydrofuran; 3- Methoxybutyl acetate, ethyl acetate, isopropyl acetate Ester-based organic solvents such as butyl acetate; Ketone-based organic solvents such as methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclohexanone, isophorone; N-methyl-2-pyrrolidone, toluene, pentane, iso-pentane, hexane, iso-hexane, cyclohexane , Solvent naphtha, mineral spirit, Solvesso 100, Solvesso 150 (all are aromatic hydrocarbon solvents, manufactured by Shell Chemical Co., Ltd.) and the like. Among these, alcohol-based organic solvents are preferable, and benzyl alcohol is more preferable. These solvents may be used alone or in combination of two or more.

<< Pigment >>
The coating composition of the present invention may contain a pigment. That is, the coating composition of the present invention may be an enamel coating composition containing a pigment or a clear coating composition not containing a pigment. Addition of the pigment imparts a base hiding property to the coating film.
As the pigment, conventionally known pigments used in coating compositions can be used, for example, azo chelate pigments, insoluble azo pigments, condensed azo pigments, diketopyrrolopyrrole pigments, benzimidazolone pigments. Organic pigments such as pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, dioxane pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments, chrome yellow, yellow iron oxide, bengara Inorganic pigments such as carbon black, titanium dioxide, and various fired pigments. These may be used alone or in combination of two or more.
Content of the said pigment is 1-70 mass% normally in solid content of a coating composition, Preferably it is 10-60 mass%. When the pigment content is 1% by mass or more, sufficient base hiding property can be imparted. When the pigment content is 70% by mass or less, the coating film becomes strong, for example, as a coating composition for pre-coating. When it is, the coating film has good scratch resistance when processing the precoated steel sheet.

<< Other >>
The coating composition of the present invention is not limited to the object of the present invention, but various additives generally used for coatings other than the above, for example, fillers other than the pigments, leveling agents, thickeners, An antifoaming agent, plasticizer, antioxidant, ultraviolet absorber, repellency inhibitor, anti-skinning agent, wax, matting agent, dispersant or resin may be included.

  The coating composition of the present invention includes, for example, an organic resin (A), a copolymer resin (B), and other optional additives, such as a roller mill, a ball mill, a bead mill, a pebble mill, a sand grind mill, a pot mill, and a paint. It can prepare by mixing using mixers, such as a shaker and a disper.

  The coating composition of the present invention is preferred as a coating composition for pre-coated metal (coated steel sheet). By using the coating composition of the present invention for the production of a pre-coated metal, it is possible to produce a pre-coated metal (painted steel plate) that can exhibit stain resistance from the initial stage over a long period of time and is also excellent in acid resistance. .

<Coating film>
The coating film of the present invention is formed using the above-mentioned coating composition. Such a coating film of the present invention can develop stain resistance from the beginning to a long period of time, and is also excellent in acid resistance.

Although the coating object which forms the coating film of this invention is not restrict | limited in particular, It is preferable to form the coating film of this invention in a steel plate. As the steel sheet, for example, a galvanized steel sheet, an alloyed galvanized steel sheet, a hot dip zinc-aluminum alloy plated steel sheet, an aluminum alloy plated steel sheet, a hot dip zinc-aluminum-magnesium alloy plated steel sheet, a stainless steel sheet, a cold-rolled steel sheet or the like may be used. it can.
The steel sheet may be subjected to surface treatment such as zinc phosphate treatment, chromium-free treatment, coating type chromate, etc., and in particular, when corrosion resistance is required, an epoxy is further provided on the surface treatment layer. It may be provided with a primer layer such as a resin primer, a polyurethane-modified epoxy resin primer, or a polyester resin primer.

  The film thickness (dry film thickness) of the coating film of the present invention is not particularly limited, but is preferably 2 μm or more, more preferably 5 μm or more, and still more preferably 10 μm or more from the viewpoint of stain resistance and acid resistance. For example, when used for precoat metal, the film thickness (dry film thickness) of the coating film is preferably 50 μm or less, more preferably 40 μm or less, from the viewpoint of followability of the coating film during precoat metal processing. Preferably it is 30 micrometers or less.

<< Formation method of coating film >>
The coating film of the present invention can be produced by applying the above-mentioned coating composition to an object to be coated such as a steel plate and then baking it by heating.
The coating method is not particularly limited, and a conventionally known method such as a roll coater, airless spray, electrostatic spray, curtain flow coater, etc. can be employed.
In addition, the baking temperature in the baking treatment (that is, the temperature of the steel plate when the article to be coated is a steel plate) is preferably 120 to 300 from the viewpoint of preventing decomposition of the resin component and obtaining a uniform coating film. ° C, more preferably 150-280 ° C, still more preferably 180-260 ° C.
Further, the baking time in the baking treatment is not particularly limited, and is preferably 3 to 90 seconds, more preferably 10 to 70 seconds, and still more preferably 20 to 60 seconds from the same viewpoint as described above.

  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. In the examples, “parts” and “%” are based on mass unless otherwise specified.

<Example 1>
(Preparation of copolymer resin (B-1) (quaternary ammonium base-containing copolymer resin))
In a reaction vessel equipped with a thermometer, a condenser, a stirrer, a dropping funnel and a reflux condenser, 30 parts by mass of butyl cellosolve was charged, and the temperature was raised to 100 ° C. while stirring in a nitrogen atmosphere. To this, 9 parts by mass of lauryl methacrylate [(b2); number of alkyl groups: 12)], 21 parts by mass of light ester DQ-100 [(b1), manufactured by Kyoeisha Chemical Co .; methyl chloride salt of dimethylaminoethyl methacrylate)] And 20 parts by mass of butyl cellosolve, and 1.5 parts by mass of Kayaester O (made by Kayaku Akzo, tertiary butyl 2-ethylhexanoate peroxide) as an initiator and 18.5 parts by mass of butyl cellosolve. The resulting initiator solution was simultaneously dropped at a constant rate over 2 hours through separate dropping funnels. After completion of dropping, the solution is further stirred at 110 ° C. for 30 minutes to form copolymer resin (B-1) (quaternary ammonium base-containing acrylic resin; resin solid content concentration: 30% by mass, copolymer resin. The ratio of light ester DQ-100 in the monomer: 70% by mass, number average molecular weight: 10,000) was obtained.

  BYK-180 (manufactured by BYK-chemie, pigment dispersant) 0.8 part by mass, TIPAQUE CR-93 (manufactured by Ishihara Sangyo Co., Ltd., titanium oxide) 40 parts by mass, solvent (T-SOL150, manufactured by ExxonMobil) 30 parts by mass Parts were mixed, bead mill kneaded, and after kneading, Beckolite M-6163-60S (made by DIC, polyester resin; solid content concentration: 60% by mass, number average molecular weight: 4,400 as organic resin (A-1). ) 63 parts by mass and 14 parts by mass of copolymer resin (B-1) were added while mixing with a disper to prepare coating composition 1.

<Examples 2 to 26, Comparative Examples 1 to 10>
Copolymer resins (B-2) to (B-22) were obtained in the same manner as in Example 1 except that the types and amounts of the respective components were changed as described in Tables 1 and 2 below. It was. In addition, about copolymer resin (B-2)-(B-5), the amount of initiators was prepared and the number average molecular weight was changed.
Further, instead of the organic resin (A-1), the organic resins (A-2) to (A-5) are replaced with the copolymer resins (B-2) to (A-5) instead of the copolymer resins (B-1). Coating compositions 2-36 were prepared in the same manner as in Example 1 except that B-22) was used.

  In Example 26, the organic resin (A-1), the copolymer resin (B-1) and the superbecamine L-109-65 (made by DIC, melamine resin) as the curing agent (C) 5. 8 parts by mass and 4.7 parts by mass of Coronate 2507 (manufactured by Tosoh Corporation, blocked isocyanate resin) were added to prepare a coating composition.

  Moreover, in Comparative Examples 9 and 10, instead of the copolymer resin (B), Newcol 291-M (manufactured by Nippon Emulsifier Co., Ltd., sodium dialkylsulfosuccinate emulsifier; active ingredient concentration) as a sulfonic acid surfactant, respectively. 70 parts by mass) 3 parts by mass and 8 parts by mass of MKC silicate MS-51 (Mitsubishi Chemical Co., Ltd., methyl silicate; active ingredient concentration: 100% by mass) as a silicate compound were added to prepare a coating composition.

The organic resin (A) used in each example and comparative example is as follows.
(A-2): Byron 63CS (manufactured by Toyobo Co., Ltd., polyester resin; solid content concentration: 33% by mass, number average molecular weight: 15,000)
(A-3): Kyner 201 (manufactured by ARKEMA, polyvinylidene fluoride resin; solid content concentration: 100% by mass, number average molecular weight: 85,000)
(A-4): Acridic A-452 (manufactured by DIC, acrylic resin; solid content concentration: 40 mass%, number average molecular weight: 17,000)
(A-5): Vylonal MD-2000 (manufactured by DIC, polyester resin emulsion; solid content concentration: 40% by mass, number average molecular weight: 18,000)

The curing agent (C) used in each example and comparative example is as follows.
(C-1): Super Becamine L-109-65 (manufactured by DIC, melamine resin; solid content concentration: 65% by mass)
(C-2): Coronate 2507 (manufactured by Tosoh Corporation, block isocyanate resin; solid content concentration: 80% by mass)

<Preparation of test plate for evaluation>
Obtained as described above on a zinc-aluminum alloy-plated steel sheet (plate thickness: 0.35 mm) on which a 5 μm dry coating film (NSC667 (S) primer manufactured by Nippon Paint Industrial Coatings Co., Ltd.) was formed. The coating compositions 1 to 36 were applied with a roll coater so that the dry film thickness was 20 μm, and baked for 40 seconds under the condition that the maximum material arrival temperature was 230 ° C. to obtain test plates.
Each test plate thus obtained was evaluated as follows.

<Evaluation items>
(1) Initial hydrophilicity (initial contamination resistance)
20 μL of ion-exchanged water was dropped on the coating film surface of the obtained test plate, and the receding contact angle when the dropped water droplet was sucked at a speed of 2 μL / second was measured using a syringe to determine the initial hydrophilicity of the coating film. Sex was evaluated. For the measurement, a contact angle meter PCA-1 (manufactured by Kyowa Kagaku) was used. The evaluation criteria are as follows.
◎ Contact angle is less than 5 ° ○ Contact angle is 5 ° or more and less than 10 ° △ Contact angle is 10 ° or more and less than 20 ° × Contact angle is 20 ° or more

(2) Raindrop contamination (contamination resistance after long-term exposure)
Under the corrugated sheet having a 10 ° inclination (having a groove of 3 mm depth and 3 mm depth), each test board was installed vertically so that rainwater dropped, and the test board after outdoor exposure for 6 months The contamination state was evaluated visually. The evaluation criteria are as follows.
◎ No dirt at all ○ Thin dirt on the whole △ Some rain streaks × Some noticeable rain streaks on the whole

(3) Acid resistance Each test plate was immersed in a 5% aqueous sulfuric acid solution at 20 ° C. for 48 hours, and then the appearance of the coating film was visually evaluated. The evaluation criteria are as follows.
◎ The blister area is 0%
○ The swelling area exceeds 0% and 5% or less △ The swelling area exceeds 5% and 50% or less × The swelling area exceeds 50%

  From Tables 3 and 4, it can be seen that the coating films formed from the coating compositions of the examples according to the present invention have good stain resistance from the initial stage over a long period of time and are also excellent in acid resistance.

On the other hand, from Comparative Examples 1 and 2 in Table 5, the ratio of the amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (b1) in the monomer constituting the copolymer resin (B) is as follows. When it exceeds 90 mass%, it turns out that the acid resistance of the coating film formed from the coating composition deteriorates.
Moreover, from Comparative Examples 3-4, the ratio of the amino group or the quaternary ammonium base containing polymerizable unsaturated monomer (b1) in the monomer which comprises copolymer resin (B) is 40 mass%. Below, it can be seen that the stain resistance of the coating film formed from the coating composition decreases.

Moreover, from Comparative Examples 5-6 of Table 5, when the solid content mass ratio with respect to the copolymer resin (B) of an organic resin (A) is too high, the stain resistance of the coating film formed from the coating composition will fall. I understand that.
Moreover, from Comparative Examples 7-8, when the solid content mass ratio with respect to copolymer resin (B) of organic resin (A) is too low, it turns out that the acid resistance of the coating film formed from the coating composition deteriorates.

Further, it can be seen from Comparative Example 9 in Table 5 that when a sulfonium-based material is used, the stain resistance after long-term exposure is insufficient and the acid resistance is also insufficient.
In addition, it can be seen from Comparative Example 10 that when a silicate-based material is used, the initial stain resistance is insufficient.

  The coating composition of the present invention can be used for forming a coating film, and the coating film can exhibit stain resistance from the initial stage over a long period of time, and is also excellent in acid resistance.

Claims (4)

At least one organic resin (A) selected from the group consisting of polyester resins, fluororesins and acrylic resins;
A copolymer resin (B) obtained by polymerizing a mixture containing a quaternary ammonium base- containing polymerizable unsaturated monomer (b1) and another polymerizable unsaturated monomer (b2) And
The quaternary ammonium base-containing polymerizable unsaturated monomer (b1) has the following general formula (3):

[Wherein R ³ is hydrogen or a methyl group, R ⁴ is an alkylene group having 1 to 5 carbon atoms, and R ⁵ , R ⁶ and R ⁷ are each independently an alkyl group having 1 to 8 carbon atoms. A quaternary ammonium base-containing polymerizable unsaturated monomer represented by
The other polymerizable unsaturated monomer (b2) is represented by the following general formula (1):

[Wherein, R ¹ is hydrogen or a methyl group, and R ² is a substituted or unsubstituted alkyl group having 8 to 18 carbon atoms]
The solid content mass ratio (A / B) between the organic resin (A) and the copolymer resin (B) is 97/3 to 70/30,
In the copolymer resin (B), the ratio of the quaternary ammonium base- containing polymerizable unsaturated monomer (b1) in the monomer constituting the copolymer resin (B) is 40 to 90 mass. %, A coating composition, characterized in that Furthermore, the coating composition of Claim 1 containing a hardening | curing agent (C). The coating composition according to claim 1 or 2 , which is used for a precoat metal. A coating film formed using the coating composition according to any one of claims 1 to 3 .