Paint compositions and painted products

Abstract

To provide a two-component, room-temperature drying paint composition that offers excellent workability and drying properties at low temperatures. [Solution] A two-component, room-temperature drying paint composition comprising at least (A) an acrylic resin having hydroxyl groups, (B) a coloring pigment, (C) a rust-preventive pigment, (D) a viscosity modifier, (E) a solvent having a mixed aniline point or aniline point in the range of 12 to 70°C as specified in JIS K 2256, and (F) an isocyanate compound, wherein the (A) acrylic resin having hydroxyl groups comprises (A-1) a hydroxyl group-containing solvent-soluble acrylic resin and (A-2) a hydroxyl group-containing non-aqueous dispersion acrylic resin, the weight-average molecular weight of the (A-1) hydroxyl group-containing solvent-soluble acrylic resin being 5,000 to 200,000, and the weight-average molecular weight of the (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin being 30,000 to 300,000.

Description

Technical Field

[0001] The present invention relates to a paint composition and a painted article using the paint composition.

Background Art

[0002] For large structures such as transmission towers for power transmission and communication, bridge facilities, and plants, a primer paint composition excellent in adhesion to a base material such as an epoxy resin-based paint composition and a topcoat paint composition excellent in weather resistance such as a silicone-based paint composition are applied (two-coat finish). However, for the purpose of shortening the construction period, there is an increasing demand for a paint composition capable of one-coat finish.

[0003] JP-A-2016-89029 (Patent Document 1) describes a paint composition for coating the surface of a galvanized steel material, which contains a film-forming resin (A) having an (a1) acrylic resin component and an (a2) alkyd resin component, and a rust preventive pigment (B). The solid content mass ratio (a1):(a2) of the (a1) acrylic resin component and the (a2) alkyd resin component in the film-forming resin (A) is 50:50 to 80:20, the weight average molecular weight of the film-forming resin (A) is 10,000 or more, and the blending ratio of the rust preventive pigment is 1 to 30% by mass in the solid content of the paint composition. The paint composition for galvanized steel material is described as a one-component type and capable of one-coat finish, and is excellent in adhesion to galvanized steel material and capable of forming a rust preventive coating film excellent in weather resistance and rust prevention.

[0004] Japanese Patent Publication No. 2020-143236 (Patent Document 2) describes a two-component curing type paint composition comprising, as a main component, a hydroxyl group-containing resin with a weight-average molecular weight of 5000 or more, a coloring pigment, a condensed phosphate, a viscosity modifier, and a solvent, and as a curing agent component, an isocyanate compound, characterized in that the content of condensed phosphate in the nonvolatile content of the paint composition is 5 to 15% by mass, and the content of pigment with a particle size of 1 μm or more in the nonvolatile content is 1.5 to 12% by volume, and it is stated that such a paint composition can provide a paint composition that enables thick film coating and can form a coating film with excellent adhesion, drying properties, and weather resistance to galvanized steel materials. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-89029 [Patent Document 2] Japanese Patent Publication No. 2020-143236 [Overview of the project] [Problems that the invention aims to solve]

[0006] The paint composition described in Patent Document 1 is a paint composition that can form a coating film with excellent adhesion, weather resistance, and rust prevention. However, the resin in the coating film is composed of acrylic resin and alkyd resin, and it is thought that its weather resistance and durability are lower compared to a coating film containing urethane resin. The paint composition described in Patent Document 2 is a two-component curing type paint composition containing a hydroxyl group-containing resin and an isocyanate compound as a curing agent component. The reaction between the two forms a urethane bond, resulting in a coating film with excellent weather resistance. However, the paint composition described in Patent Document 2 sometimes has problems with paint workability at low temperatures and problems with drying at low temperatures, indicating room for improvement.

[0007] Therefore, an object of the present invention is to provide a two-component, room-temperature drying paint composition that exhibits excellent workability and drying properties at low temperatures. Another object of the present invention is to provide a painted product using such a paint composition. [Means for solving the problem]

[0008] As a result of diligent research to achieve the above objective, the inventors have discovered that in a two-component, room-temperature drying paint composition containing a hydroxyl group-containing acrylic resin, a coloring pigment, a rust-preventive pigment, a viscosity modifier, a weak solvent, and an isocyanate compound, by using in combination a hydroxyl group-containing solvent-soluble acrylic resin with a weight-average molecular weight of 5,000 to 200,000 and a hydroxyl group-containing non-aqueous dispersion acrylic resin with a weight-average molecular weight of 30,000 to 300,000 as the hydroxyl group-containing acrylic resin, it is possible to achieve both low-temperature painting workability and drying properties, thus completing the present invention.

[0009] Therefore, the paint composition of the present invention is (A) Acrylic resin having hydroxyl groups, (B) Coloring pigments, (C) Rust-preventive pigments, (D) Viscosity modifier, (E) Solvents having a mixed aniline point or aniline point within the range of 12 to 70°C as specified in JIS K 2256, (F) Isocyanate compound It includes at least, The (A) acrylic resin having hydroxyl groups comprises (A-1) a hydroxyl group-containing solvent-soluble acrylic resin and (A-2) a hydroxyl group-containing non-aqueous dispersion acrylic resin, wherein the weight-average molecular weight of the (A-1) hydroxyl group-containing solvent-soluble acrylic resin is 5,000 to 200,000, and the weight-average molecular weight of the (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin is 30,000 to 300,000. This is a two-component, room-temperature drying paint composition.

[0010] In a preferred example of the coating composition of the present invention, the mass ratio (A-1:A-2) of the (A-1) hydroxyl group-containing solvent-soluble acrylic resin and the (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin is 10:90 to 90:10.

[0011] In other preferred examples of the coating composition of the present invention, the hydroxyl value of the (A-1) hydroxyl group-containing solvent-soluble acrylic resin is 10 to 70 mgKOH / g, and the hydroxyl value of the (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin is 10 to 100 mgKOH / g.

[0012] Furthermore, the coated product of the present invention is characterized by comprising a coating film formed from the above-mentioned coating composition. [Effects of the Invention]

[0013] The present invention provides a two-component, room-temperature drying paint composition that exhibits excellent workability and drying properties at low temperatures. Furthermore, the present invention provides a painted product using such a paint composition. [Modes for carrying out the invention]

[0014] The coating composition and coated product according to the present invention will be described in detail below.

[0015] The paint composition of the present invention, (A) Acrylic resin having hydroxyl groups, (B) Coloring pigments, (C) Rust-preventive pigments, (D) Viscosity modifier, (E) Solvents having a mixed aniline point or aniline point within the range of 12 to 70°C as specified in JIS K 2256, (F) Isocyanate compound It includes at least, (A) The acrylic resin having a hydroxyl group contains (A-1) a hydroxyl group-containing solvent-soluble acrylic resin and (A-2) a hydroxyl group-containing non-aqueous dispersion acrylic resin. The weight average molecular weight of (A-1) the hydroxyl group-containing solvent-soluble acrylic resin is 5,000 to 200,000, and the weight average molecular weight of (A-2) the hydroxyl group-containing non-aqueous dispersion acrylic resin is 30,000 to 300,000. It is a two-component room temperature drying type paint composition.

[0016] In this specification, the acrylic resin having a hydroxyl group is used as the component (A), and may also be referred to as “(A) acrylic resin having a hydroxyl group” or “(A) acrylic resin”. The terms “acrylic resin having a hydroxyl group” and “hydroxyl group-containing acrylic resin” are used synonymously. The coloring pigment is used as the component (B), and may also be referred to as “(B) coloring pigment”. The rust preventive pigment is used as the component (C), and may also be referred to as “(C) rust preventive pigment”. The viscosity modifier is used as the component (D), and may also be referred to as “(D) viscosity modifier”. The solvent having a mixed aniline point or aniline point specified in JIS K 2256 within the range of 12 to 70 ° C is used as the component (E), and may also be referred to as “(E) solvent having a mixed aniline point or aniline point specified in JIS K 2256 within the range of 12 to 70 ° C” or “(E) solvent”. The isocyanate compound is used as the component (F), and may also be referred to as “(F) isocyanate compound”. The hydroxyl group-containing solvent-soluble acrylic resin is used as the component (A-1), and may also be referred to as “(A-1) hydroxyl group-containing solvent-soluble acrylic resin” or “(A-1) soluble acrylic resin”. The hydroxyl group-containing non-aqueous dispersion acrylic resin is used as the component (A-2), and may also be referred to as “(A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin” or “(A-2) non-aqueous dispersion acrylic resin”.

[0017] In this specification, a two-component paint composition is a paint composition comprising a main agent and a curing agent. The two-component paint composition is divided into two parts (main agent and curing agent) until immediately before use, and can be prepared by mixing them immediately before use. When mixing the main agent and the curing agent, additives, solvents, etc. may be added to prepare the two-component paint composition. In the present invention, the agent containing an acrylic resin having a hydroxyl group (A) is the main agent, and the agent containing an isocyanate compound (F) is the curing agent. Other components may be incorporated into either the main agent or the curing agent, or may be added when mixing the main agent and the curing agent. For example, components (B), (C), (D) and (E) may be contained in the main agent.

[0018] In this specification, a room-temperature drying type paint composition is a paint composition capable of forming a paint film by drying at room temperature. Here, "room temperature" means a temperature of 0 to 40°C.

[0019] (A) The acrylic resin having a hydroxyl group reacts with the (F) isocyanate compound described later to form a urethane bond, and a paint film excellent in weather resistance and adhesion to a substrate (substrate adhesion) can be obtained. Therefore, the paint composition of the present invention may be referred to as a two-component urethane paint.

[0020] In the paint composition of the present invention, the content of the acrylic resin having a hydroxyl group (A) in the non-volatile matter is preferably 25 to 70% by mass, and more preferably 30 to 60% by mass.

[0021] In this specification, the non-volatile matter refers to the components excluding the volatile components such as water and organic solvents, and is the component that finally forms the paint film. In the present invention, the components remaining when the paint composition is dried at 130°C for 60 minutes are treated as non-volatile matter. The content of the non-volatile matter in the paint composition of the present invention is preferably 50 to 90% by mass, and more preferably 55 to 75% by mass.

[0022] In this specification, acrylic resins are polymers of acrylic acid esters or methacrylic acid esters, and include polymers obtained by polymerizing one or more acrylic components selected from acrylic acid, methacrylic acid, and their esters, amides, and nitriles, and also include polymers obtained by polymerizing acrylic components with non-acrylic components such as styrene. For example, acrylic resins having hydroxyl groups can be easily prepared by using hydroxyl group-containing monomers during the synthesis of acrylic resins. Furthermore, in this specification, acrylic resins also include modified acrylic resins such as silicone-modified and alkyd-modified acrylic resins.

[0023] (A) Acrylic resins having hydroxyl groups include (A-1) hydroxyl group-containing solvent-soluble acrylic resins and (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resins. Each of (A-1) hydroxyl group-containing solvent-soluble acrylic resin and (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin may be used individually or in combination of two or more types.

[0024] The term "solvent-soluble acrylic resin" generally refers to a resin that dissolves in organic solvents. In this specification, "solvent-soluble acrylic resin" refers to an acrylic resin that dissolves in solvents with a mixed aniline point or aniline point within the range of 12 to 70°C as defined in JIS K 2256 (in other words, an acrylic resin that can be mixed with a solvent with a mixed aniline point or aniline point within the range of 12 to 70°C as defined in JIS K 2256 to form a homogeneous liquid).

[0025] (A-1) There are no particular limitations on the method for producing hydroxyl group-containing solvent-soluble acrylic resins, but for example, they can be produced by polymerizing a resin raw material containing an acrylic component in an organic solvent in the presence of a polymerization initiator using a known method.

[0026] The term "non-aqueous dispersion acrylic resin" generally refers to an acrylic resin that can be distributed in an organic solvent to form a heterogeneous system (e.g., an emulsion or suspension). In this specification, "non-aqueous dispersion acrylic resin" refers to an acrylic resin that can be distributed in a solvent with a mixed aniline point or aniline point within the range of 12 to 70°C as defined in JIS K 2256 to form a heterogeneous system (e.g., an emulsion or suspension). Note that non-aqueous dispersion acrylic resins are sometimes also called NAD-type acrylic resins (NAD stands for Non-Aqueous Dispersion).

[0027] (A-2) There are no particular limitations on the method for producing a hydroxyl group-containing non-aqueous dispersion acrylic resin. For example, a method can be used in which monomers such as aliphatic hydrocarbons dissolve but polymers do not, and monomers having ethylenically unsaturated groups are reacted with a crosslinkable copolymer in a non-aqueous organic solvent, and the resulting fine particle copolymer is dispersed.

[0028] In one embodiment of the present invention, the paint composition contains (A) a hydroxyl group-containing acrylic resin, which is (A-1) a hydroxyl group-containing solvent-soluble acrylic resin that is dissolved in (E) a mixed aniline point or a solvent having an aniline point in the range of 12 to 70°C as specified in JIS K 2256, and (E) a hydroxyl group-containing non-aqueous dispersion acrylic resin that is dispersed in particulate form in a solvent having a mixed aniline point or a solvent having an aniline point in the range of 12 to 70°C as specified in JIS K 2256.

[0029] (E) Paint compositions containing solvents with a mixed aniline point or aniline point within the range of 12 to 70°C as specified in JIS K 2256 dry slowly. Therefore, drying properties (especially low-temperature drying properties) can be improved by using (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin. On the other hand, paint compositions using (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin experience a significant increase in viscosity at low temperatures, which can cause problems with paint application. For example, increasing the amount of solvent can suppress the increase in viscosity, but in this case, it becomes difficult to form a thick film, making it difficult to provide a paint composition that allows for a one-coat finish. Therefore, in the paint composition of the present invention, (A-1) hydroxyl group-containing solvent-soluble acrylic resin is used in combination with (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin. By using (A-1) hydroxyl group-containing solvent-soluble acrylic resin, paint application properties at low temperatures can be improved without increasing the amount of solvent. Here, "low temperature" means a temperature of 0 to 10°C.

[0030] The mass ratio (A-1:A-2) of (A-1) hydroxyl group-containing solvent-soluble acrylic resin and (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 40:60 to 80:20, from the viewpoint of achieving both good paintability and drying properties at low temperatures. Furthermore, if the mass ratio (A-1:A-2) falls outside the specified range, it may become difficult to manufacture the paint.

[0031] (A-1) The hydroxyl group-containing solvent-soluble acrylic resin preferably has a hydroxyl value of 10 to 70 mgKOH / g, and more preferably 20 to 70 mgKOH / g. When the hydroxyl value of component (A-1) is within the above specified range, the low-temperature drying properties and paint workability of the paint composition can be further improved. If the hydroxyl value of component (A-1) is less than 10 mgKOH / g, sufficient curing properties may not be obtained, and if the hydroxyl value of component (A-1) is greater than 70 mgKOH / g, the polarity of the resin increases, and it becomes difficult to dissolve in solvents with a mixed aniline point or aniline point in the range of 12 to 70°C as specified in (E) JIS K 2256.

[0032] In this specification, the hydroxyl value is measured in accordance with JIS K 0070:1992 "Test methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products".

[0033] (A-1) The hydroxyl group-containing solvent-soluble acrylic resin has a weight-average molecular weight of 5,000 to 200,000, preferably 10,000 to 100,000. If the weight-average molecular weight of component (A-1) is within the specified range, a paint composition can be obtained that exhibits excellent drying properties at low temperatures and paintability. If the weight-average molecular weight of component (A-1) is less than 5,000, drying properties at low temperatures will not be obtained despite the presence of component (A-2), and substrate adhesion and sagging will also deteriorate. If the weight-average molecular weight of component (A-1) exceeds 200,000, paintability at low temperatures will deteriorate significantly.

[0034] In this specification, weight-average molecular weight is the value measured by gel permeation chromatography, and polystyrene is used as the standard substance.

[0035] In the paint composition of the present invention, the content of (A-1) hydroxyl group-containing solvent-soluble acrylic resin in the paint composition is preferably 2.5 to 63% by mass, and more preferably 3.0 to 54% by mass. If the content of component (A-1) is within the above specified range, the paint composition's workability at low temperatures can be further improved, as can its storage stability.

[0036] (A-2) The hydroxyl group-containing non-aqueous dispersion acrylic resin preferably has a hydroxyl value of 10 to 100 mgKOH / g, and more preferably 20 to 70 mgKOH / g. When the hydroxyl value of component (A-2) is within the above specified range, the low-temperature drying properties and paint workability of the paint composition can be further improved. If the hydroxyl value of component (A-2) is less than 10 mgKOH / g, sufficient curing properties may not be obtained. If the hydroxyl value of component (A-2) is too high, the number of crosslinking points increases, and the adhesion to the substrate tends to decrease due to increased internal stress.

[0037] Furthermore, the difference between the hydroxyl values ​​of component (A-1) and component (A-2) is preferably 50 mg KOH / g or less, and more preferably 30 mg KOH / g or less. When the difference between the hydroxyl values ​​of component (A-1) and component (A-2) is within the specified range, it is thought that the uniformity of components (A-1) and (A-2) will be high during coating film formation, and the increase in internal stress can be suppressed. On the other hand, if the difference between the hydroxyl values ​​of component (A-1) and component (A-2) is too large, components (A-1) and (A-2) will be unevenly distributed during coating film formation, and an unevenness in crosslinking density may occur during the reaction with the isocyanate compound. If the internal stress of the coating film is uneven, it may lead to cracking or peeling.

[0038] (A-2) The hydroxyl group-containing non-aqueous dispersion acrylic resin has a weight-average molecular weight of 30,000 to 300,000, preferably 50,000 to 200,000. If the weight-average molecular weight of component (A-2) is within the specified range, a paint composition can be obtained that has excellent drying properties at low temperatures and paintability. While a higher weight-average molecular weight can be obtained for component (A-2) compared to component (A-1), if the weight-average molecular weight is excessive, although the coating film properties may be excellent, the storage stability may be poor. Furthermore, if the weight-average molecular weight of component (A-2) exceeds 300,000, the paintability at low temperatures deteriorates significantly, even when used in combination with component (A-1). On the other hand, if the weight-average molecular weight of component (A-2) is less than 30,000, drying properties at low temperatures cannot be obtained, and sagging also deteriorates.

[0039] In the paint composition of the present invention, the content of (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin in the paint composition is preferably 2.5 to 63% by mass, and more preferably 3.0 to 54% by mass. When the content of component (A-2) is within the above specified range, the paint composition's workability at low temperatures can be further improved, as can its storage stability.

[0040] The paint composition of the present invention may contain further resins. From the viewpoint of weather resistance, fluororesins are preferred as the further resins. The content of fluororesins in the nonvolatile content is, for example, 0.5 to 20% by mass.

[0041] (B) The coloring pigment is not particularly limited, and any coloring pigment commonly used in the paint industry can be used. Specific examples include inorganic pigments such as titanium dioxide, iron oxide, and carbon black, and organic pigments such as phthalocyanine copper, azo pigments, and condensed polycyclic pigments. (B) The coloring pigment may be used alone or in combination of two or more types. In the paint composition of the present invention, the content of (B) coloring pigment in the non-volatile content is preferably 2 to 60% by mass, and more preferably 10 to 50% by mass.

[0042] (C) The rust-preventive pigment is not particularly limited, and rust-preventive pigments commonly used in the paint industry can be used. Specific examples include phosphate-based rust-preventive pigments, boric acid-based rust-preventive pigments, molybdate-based rust-preventive pigments, vanadate-based rust-preventive pigments, etc. From the viewpoint of adhesion to galvanized steel, phosphate-based rust-preventive pigments are preferred as the (C) rust-preventive pigment.

[0043] Phosphate-based rust-preventive pigments are preferably condensed phosphates. Examples of condensed phosphates include orthophosphate metal salts such as zinc orthophosphate, calcium orthophosphate, aluminum orthophosphate, and magnesium orthophosphate; pyrophosphate metal salts such as aluminum pyrophosphate, calcium pyrophosphate, tin pyrophosphate, iron pyrophosphate, titanium pyrophosphate, magnesium pyrophosphate, and manganese pyrophosphate; tripolyphosphate metal salts such as iron tripolyphosphate and aluminum tripolyphosphate; metaphosphate metal salts such as aluminum metaphosphate, calcium metaphosphate, iron metaphosphate, and tin metaphosphate; and further, phosphate metal salt layered compounds such as layered titanium phosphate, layered zirconium phosphate, and layered tin phosphate. Among these, from the viewpoint of adhesion to galvanized steel, the condensed phosphate is preferably condensed aluminum phosphate or condensed zinc phosphate, and more preferably condensed aluminum phosphate.

[0044] (C) The rust-preventive pigment may be used alone or in combination of two or more types. In the paint composition of the present invention, the content of (C) rust-preventive pigment in the non-volatile content is preferably 5 to 15% by mass.

[0045] The paint composition of the present invention may contain extender pigments, but from the viewpoint of improving weather resistance, it is preferable not to include extender pigments. Examples of extender pigments include silica, talc, mica, calcium carbonate, and barium sulfate. In the paint composition of the present invention, the content of extender pigments in the non-volatile content is, for example, 0 to 20% by mass.

[0046] In the paint composition of the present invention, the total amount of pigment in the non-volatile content is preferably 7 to 65% by mass, and more preferably 20 to 60% by mass.

[0047] (D) Viscosity modifiers are preferably used from the viewpoint of paint workability, especially workability when applying thick films, and viscosity modifiers commonly used in the paint industry can be used. Specific examples include viscosity modifiers such as fatty acid amides, polyethylene, fatty acid esters, modified urea, castor oil derivatives, organic modified clay minerals such as organic bentonite and organic modified sepiolite, and hydrophilic silica. Among these, viscosity modifiers selected from the group consisting of fatty acid amides, fatty acid esters, and organic modified clay minerals are preferred.

[0048] In the paint composition of the present invention, (D) viscosity modifier may be used alone or in combination of two or more types. In the paint composition of the present invention, the content of (D) viscosity modifier in the nonvolatile content is preferably 0.1 to 10% by mass.

[0049] Component (E) is a solvent whose mixed aniline point or aniline point is within the range of 12 to 70°C as specified in JIS K 2256, and is classified as a weak solvent. Component (E) is a solvent with a relatively low environmental impact and can be removed by drying at room temperature. JIS K 2256 refers to JIS K 2256:2013 "Petroleum products - Method for determining aniline point and mixed aniline point". The aniline point and mixed aniline point are indicators of the dissolving power of a solvent; the higher the aniline point or mixed aniline point, the weaker the dissolving power. The aniline point is the lowest temperature at which a mixture of aniline and a sample (volume ratio 1:1) exists as a homogeneous solution, and the mixed aniline point is the lowest temperature at which a mixture of aniline, a sample, and heptane (volume ratio 2:1:1) exists as a homogeneous solution.

[0050] (E) Solvents with a mixed aniline point or aniline point within the range of 12 to 70°C as specified in JIS K 2256 include, for example, hydrocarbon organic solvents such as aliphatic solvents, naphthenic solvents, and aromatic naphtha. Among these, aliphatic hydrocarbon organic solvents are particularly suitable as weak solvents with low odor and minimal adverse effects on the environment. Specific examples of aliphatic hydrocarbon organic solvents include methylcyclohexane (aniline point: 40°C), ethylcyclohexane (aniline point: 44°C), mineral spirits (aniline point: 56°C), and turpentine oil (aniline point: 44°C). Furthermore, some aliphatic hydrocarbon organic solvents are commercially available as petroleum hydrocarbons, such as HAWS (manufactured by Shell Chemicals Japan, aniline point: 17°C), LAWS (manufactured by Shell Chemicals Japan, aniline point: 44°C), Pegasol 3040 (manufactured by ExxonMobil, aniline point: 55°C), Pegasol AN45 (manufactured by ExxonMobil, aniline point: 42°C), A Solvent (manufactured by JX Nippon Oil & Energy Corporation, aniline point: 45°C), Clensol HS (manufactured by JX Nippon Oil & Energy Corporation, aniline point: 64°C), Mineral Spirit A (manufactured by JX Nippon Oil & Energy Corporation, aniline point: 43°C), Exol D30 (manufactured by ExxonMobil, aniline point: 64°C), and Exol D Examples include 40 (manufactured by ExxonMobil, aniline point: 69°C), NewSol DX High Soft (manufactured by JX Nippon Oil & Energy Corporation, aniline point: 68°C), Solvesso 100 (manufactured by ExxonMobil, mixed aniline point: 14°C), Solvesso 150 (manufactured by ExxonMobil, mixed aniline point: 18.3°C), Swazol 1000 (manufactured by Maruzen Petrochemical Co., Ltd., mixed aniline point: 12.7°C), Swazol 1500 (manufactured by Maruzen Petrochemical Co., Ltd., mixed aniline point: 16.5°C), Swazol 1800 (manufactured by Maruzen Petrochemical Co., Ltd., mixed aniline point: 15.7°C), Idemitsu Ipsol 100 (manufactured by Idemitsu Kosan Co., Ltd., mixed aniline point: 13.5°C), and Idemitsu Ipsol 150 (manufactured by Idemitsu Kosan Co., Ltd., mixed aniline point: 15.2°C).

[0051] In the paint composition of the present invention, component (E) may be used alone or in combination of two or more types. In the paint composition of the present invention, the content of component (E) in the paint composition is preferably 1 to 50% by mass.

[0052] The coating composition of the present invention may contain further solvents. Known coating solvents such as alcohols, ethers, ketones, esters (including lactones), nitrogen-containing compounds (amides, lactams, etc.), sulfur-containing compounds, and hydrocarbons (aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, etc.) can be used as further solvents. In the coating composition of the present invention, the content of the further solvent in the coating composition is, for example, 0.1 to 10% by mass.

[0053] The coating composition of the present invention may contain a silane coupling agent. By incorporating a silane coupling agent, adhesion to the substrate can be improved. Known silane coupling agents can be used, but examples include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxytrimethoxysilane, and γ-mercaptopropyltrimethoxysilane. The silane coupling agent may be used alone or in combination of two or more. In the coating composition of the present invention, the content of the silane coupling agent in the non-volatile content is, for example, 0 to 5.0% by mass.

[0054] (F) The isocyanate compound is a compound used to cure the paint, and by reacting with (A) the acrylic resin having hydroxyl groups, it forms urethane bonds, and a coating film with excellent weather resistance and adhesion to the substrate can be obtained. The isocyanate compound preferably has an isocyanate group content of 0.5 to 1.5 equivalents, and more preferably 0.8 to 1.2 equivalents, relative to the hydroxyl groups of the acrylic resin having hydroxyl groups. The content of the (F) isocyanate compound can be appropriately adjusted according to the amount of hydroxyl groups in the acrylic resin having hydroxyl groups, but for example, in the paint composition of the present invention, the content of the (F) isocyanate compound in the nonvolatile content is preferably 2 to 20% by mass. The (F) isocyanate compound may be used alone or in combination of two or more types.

[0055] (F) Examples of isocyanate compounds include aliphatic, aromatic, or aromaticaliphatic isocyanate compounds, and it is preferable that they are compounds having two or more isocyanate groups (also called polyisocyanates). Specific examples include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methylcyclohexane diisocyanate, bis(isocyanate-methyl)cyclohexane, isophorone diisocyanate, dimer acid diisocyanate, lysine diisocyanate, and modified forms of these isocyanates. Specific examples of modified forms include biuret modified forms, isocyanurate modified forms, adduct modified forms (e.g., trimethylolpropane adducts), allophanate modified forms, uretdione modified forms, and the like. Among these, various modified forms of hexamethylene diisocyanate and various modified forms of isophorone diisocyanate are preferred from the viewpoint of curability and coating film properties.

[0056] The paint composition of the present invention may contain a curing catalyst. By using a curing catalyst, the reaction between (A) an acrylic resin having hydroxyl groups and (F) an isocyanate compound can be accelerated. Known curing catalysts can be used, but examples include tin-based catalysts such as dibutyltin diacetate, dibutyltin dioctate, and dibutyltin dilaurate; amine-based catalysts such as triethylenediamine; carboxylate-based catalysts such as copper naphthenate; and trialkylphosphine-based catalysts such as triethylphosphine. The curing catalyst may be used alone or in combination of two or more. In the paint composition of the present invention, the content of the curing catalyst in the non-volatile content is, for example, 0 to 1.0% by mass.

[0057] The paint composition of the present invention may further contain, as appropriate for the purpose, matting agents, surface modifiers, wetting agents, dispersants, settling inhibitors, sagging inhibitors, defoaming agents, color separation inhibitors, leveling agents, drying agents, plasticizers, antifungal agents, antialgal agents, ultraviolet absorbers, light stabilizers, antistatic agents, and conductivity imparters.

[0058] The paint composition of the present invention can be prepared by preparing the main component and the hardener in advance and mixing them at the time of application. Alternatively, additional additives may be prepared separately from the main component and hardener, and these additives may be added when mixing the main component and hardener. For example, a diluting solvent may be added for purposes such as adjusting viscosity. The main component and hardener can be prepared by mixing components that are appropriately selected as needed.

[0059] The paint composition of the present invention can be used as a paint composition for both undercoat and topcoat, or as a paint composition that allows for a one-coat finish.

[0060] The paint composition of the present invention has a shear rate of 0.1 s measured after adjusting the liquid temperature to 23°C. -1 The viscosity is 100 to 1,000,000 Pa·s, and the shear rate is 1,000 s. -1The viscosity is preferably 1 to 1000 Pa·s. Furthermore, the paint composition of the present invention has a shear rate of 0.1 s measured after adjusting the liquid temperature to 5°C. -1 The viscosity is 100 to 1,000,000 Pa·s, and the shear rate is 1,000 s. -1 The viscosity is preferably 1 to 1000 Pa·s. Here, viscosity is measured using a rheometer (such as the ARES rheometer manufactured by TA Instruments).

[0061] The coating method for the paint composition of the present invention is not particularly limited, and known coating methods such as spray coating, roller coating, brush coating, trowel coating, spatula coating, etc., can be used.

[0062] The substrates that can be coated with the coating composition of the present invention are not particularly limited, but from the viewpoint of adhesion between the coating film and the substrate, metal-based substrates containing at least a portion of a metal or alloy such as steel, galvanized steel, tin-plated steel, stainless steel, magnesium alloy, aluminum, and aluminum alloy can be preferably mentioned. The coating composition of the present invention can exhibit particularly outstanding adhesion to galvanized steel substrates. Examples of galvanized steel substrates include galvanized steel materials (steel plates, steel pipes, steel bars, etc.) and structures in which galvanized steel materials are used (transmission and communication towers, bridge facilities, plants, etc.).

[0063] The substrate may have a primer treatment such as corrosion protection applied to its surface, or at least a portion of its surface may have a prior coating (a coating already formed on the substrate when painting with the coating composition of the present invention).

[0064] Next, the coated article of the present invention will be described in detail. The coated article of the present invention is characterized by comprising a coating film formed from the paint composition of the present invention. The coating film can be formed by coating a substrate with the paint composition of the present invention. The substrate is as described above. [Examples]

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0066] Following the formulations shown in Tables 1-4, the main component and hardener were prepared, and then mixed to prepare the paint compositions of Examples 1-19 and Comparative Examples 1-6. The amounts of each component shown in the formulations are by mass.

[0067] The details of the materials used in preparing the paint composition are shown below.

[0068] 1. (A) Acrylic resin having hydroxyl groups 1-1. Hydroxyl group-containing solvent-soluble acrylic resin Synthetic resin A: Non-volatile content 50% by mass (solvent: mineral spirits), hydroxyl value 50 mgKOH / g, weight-average molecular weight 30,000 Synthetic resin B: Non-volatile content 50% by mass (solvent: mineral spirits), hydroxyl value 50 mg KOH / g, weight-average molecular weight 5,000 Synthetic resin C: Non-volatile content 50% by mass (solvent: mineral spirits), hydroxyl value 50 mg KOH / g, weight-average molecular weight 200,000 Synthetic resin D: Non-volatile content 50% by mass (solvent: mineral spirits), hydroxyl value 50 mg KOH / g, weight-average molecular weight 3,000 Synthetic resin E: Non-volatile content 50% by mass (solvent: mineral spirits), hydroxyl value 50 mg KOH / g, weight-average molecular weight 250,000 Synthetic resin F: Non-volatile content 50% by mass (solvent: mineral spirits), hydroxyl value 10 mg KOH / g, weight-average molecular weight 30,000 Synthetic resin G: Non-volatile content 50% by mass (solvent: mineral spirits), hydroxyl value 70 mgKOH / g, weight-average molecular weight 30,000 Synthetic resin H: Non-volatile content 50% by mass (solvent: mineral spirits), hydroxyl value 5 mg KOH / g, weight-average molecular weight 30,000 Synthetic resin I: Non-volatile content 50% by mass (solvent: mineral spirits), hydroxyl value 80 mg KOH / g, weight-average molecular weight 30,000 Synthetic resins A through I are solutions in which acrylic resin is dissolved, but for convenience, they are referred to simply as "synthetic resins." 1-2. Hydroxyl group-containing non-aqueous dispersion acrylic resin Synthetic resin 1: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 44 mg KOH / g, weight-average molecular weight 140,000 Synthetic resin 2: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 58 mg KOH / g, weight-average molecular weight 140,000 Synthetic resin 3: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 44 mg KOH / g, weight-average molecular weight 30,000 Synthetic resin 4: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 44 mg KOH / g, weight-average molecular weight 300,000 Synthetic resin 5: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 44 mg KOH / g, weight-average molecular weight 20,000 Synthetic resin 6: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 44 mg KOH / g, weight-average molecular weight 400,000 Synthetic resin 7: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 10 mg KOH / g, weight-average molecular weight 150,000 Synthetic resin 8: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 100 mg KOH / g, weight-average molecular weight 140,000 Synthetic resin 9: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 5 mg KOH / g, weight-average molecular weight 150,000 Synthetic resin 10: Non-volatile content 58% by mass (solvent: mineral spirits), hydroxyl value 110 mg KOH / g, weight-average molecular weight 140,000 Synthetic resins 1-10 are dispersions in which acrylic resin is dispersed, but for convenience, they are referred to simply as "synthetic resins."

[0069] 2. Other resins Fluororesin solution: Lumiflon LF-800 (manufactured by AGC Corporation), non-volatile content 60% by mass, hydroxyl value 32.5 mg KOH / g

[0070] 3. (B) Coloring pigments Titanium dioxide: JR-806 (manufactured by Teika Co., Ltd.)

[0071] 4. (C) Anti-corrosion pigment Rust-preventive pigment 1: K-WHITE#105 (manufactured by Teika Co., Ltd., aluminum dihydrogen tripolyphosphate) Non-volatile content 100% by mass Rust-preventive pigment 2: K-WHITE#82 (manufactured by Teika Co., Ltd., aluminum dihydrogen tripolyphosphate) Non-volatile content 100% by mass

[0072] 5. (D) Viscosity modifier Fatty acid amide: Disparon D6820-10M (manufactured by Kusumoto Chemical Co., Ltd.), non-volatile content 10% by mass. The product itself is a swollen form of fatty acid amide, but for convenience, it is referred to as "fatty acid amide". Organically modified clay mineral: GARAMITE-7303 (manufactured by BYK), non-volatile content 100% by mass

[0073] 6. (E) Solvent Mineral spirits (boiling point 138-144°C, aniline point 43.0°C) Solvesso 100 (manufactured by ExxonMobil, boiling point 162-178°C, mixed aniline point 12.4°C) The solvents listed in (E) in the table do not refer to solvents used in other materials (for example, mineral spirits used in synthetic resins A-I and synthetic resins 1-10), but rather to solvents used during the preparation of the main component.

[0074] 7. Additives Silane coupling agent: 3-glycidoxypropyltrimethoxysilane, non-volatile content 97% by mass UV absorber and light stabilizer: EVERSORB 80 (manufactured by Eiko Chemical Co., Ltd., benzotriazole-based UV absorber), non-volatile content 84% by mass; Antifoaming agent: Dappo SN359 (manufactured by Sunopco), non-volatile content 27% by mass.

[0075] 8. (F) Isocyanate compounds HDI isocyanate: Duranate TSS100 (manufactured by Asahi Kasei Corporation, polyisocyanate derivative of hexamethylene diisocyanate), non-volatile content 100% by mass

[0076] The prepared paint compositions were evaluated for their low-temperature drying properties (walkability), low-temperature paint application properties, adhesion, and sagging. The results are shown in Tables 1-4.

[0077] <Low temperature, dry (walkable)> Under 5°C conditions, a paint composition was applied to a 75 x 150 mm tin plate using an 8 mil applicator. After 5 hours, the coated plate was stepped on, and the low-temperature drying properties were evaluated based on the adhesion to shoes according to the following evaluation criteria. Paint compositions that receive a "○" or "△" evaluation are paint compositions with excellent low-temperature drying properties. (Evaluation Criteria) ○: No paint adheres to the shoes, and no deformation occurs in the paint film. △: No paint adheres to the shoes, but there is slight deformation in the paint film, although the base material is not exposed. ×: Paint adheres to the shoes, or the paint film peels off (exposing the base material).

[0078] <Low-temperature painting workability> Under 5°C conditions, paint compositions were applied to 300 x 300 mm tinplate using rollers and brushes, and their paintability was evaluated according to the following evaluation criteria. Paint compositions with an evaluation of "○" or "△" are paint compositions with excellent paintability at low temperatures. (Evaluation Criteria) ○: Easy to apply with rollers and brushes, and leaves minimal paint marks. △: Application with rollers and brushes is possible, but the degree of paint marks is significant. ×: Difficult to apply with rollers and brushes.

[0079] <Adhesion> A 3.2 x 70 x 150 mm hot-dip galvanized steel sheet was exposed outdoors at the Nasu Plant of Dainippon Paint Co., Ltd. for 12 months to obtain a degraded galvanized steel sheet. Next, a paint composition was brush-applied onto this degraded galvanized steel sheet at 23°C to a dry film thickness of 60 μm, and dried at 23°C for 7 days to obtain a test plate. After immersing the test board in 23°C tap water for 168 hours, it was removed, the surface water was wiped off, and it was dried for 2 hours. Then, based on JIS K 5600-5-6 Adhesion (cross-cut method), a grid adhesion test was performed using 25 squares spaced 2 mm apart, and the adhesion was evaluated according to the following evaluation criteria. (Evaluation Criteria) ○: No peeling (25 squares remaining) △: Some peeling (1-24 squares remaining) ×: Peeling present (no residue remaining)

[0080] <Saucy> Under conditions of 23°C, the paint composition was applied to a tin plate using a 20 mil applicator. Immediately afterward, the coated plate was dried in a vertical position, and the degree of sagging of the paint film was evaluated according to the following evaluation criteria. (Evaluation Criteria) ○: No sauce △: No sagging, some sagging ×: With sauce

[0081] [Table 1]

[0082] [Table 2]

[0083] [Table 3]

[0084] [Table 4]

Claims

1. (A) Acrylic resin having hydroxyl groups, (B) Coloring pigments, (C) Anti-corrosion pigment, (D) Viscosity modifier, (E) Solvents having a mixed aniline point or aniline point in the range of 12 to 70°C as specified in JIS K 2256, (F) Isocyanate compounds It includes at least, A two-component, room-temperature drying paint composition characterized in that the (A) acrylic resin having hydroxyl groups comprises (A-1) a hydroxyl group-containing solvent-soluble acrylic resin and (A-2) a hydroxyl group-containing non-aqueous dispersion acrylic resin, wherein the weight-average molecular weight of the (A-1) hydroxyl group-containing solvent-soluble acrylic resin is 5,000 to 200,000, and the weight-average molecular weight of the (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin is 30,000 to 300,000.

2. The paint composition according to claim 1, characterized in that the mass ratio (A-1:A-2) of the (A-1) hydroxyl group-containing solvent-soluble acrylic resin and the (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin is 10:90 to 90:

10.

3. The paint composition according to claim 1, characterized in that the hydroxyl value of the (A-1) hydroxyl group-containing solvent-soluble acrylic resin is 10 to 70 mgKOH / g, and the hydroxyl value of the (A-2) hydroxyl group-containing non-aqueous dispersion acrylic resin is 10 to 100 mgKOH / g.

4. A painted article characterized by comprising a coating film formed from a coating composition according to any one of claims 1 to 3.

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