Two-component curing coating agent and multilayer film

Abstract

To provide a two-liquid curable coating agent capable of forming a surface protective layer excellent in weatherability, acid resistance, antifouling property and extensibility and to provide a multilayer film having a surface protective layer which is a cured film of the two-liquid curable coating agent.SOLUTION: There is provided a two-liquid curable coating agent which comprises a main agent containing a polyol including an epoxy polyol (P) which is a reaction product of an epoxy group-containing compound (e) and a carboxyl group-containing compound (c) and an acryl polyol (A) and a curing agent containing a polyisocyanate. Further, there is provided a multilayer film containing a substrate layer, a surface protective layer which is integrally laminated on a first surface of the substrate layer and is a cured film of the two-liquid curable coating agent and an adhesive layer which is integrally laminated on a second surface of the substrate layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a two-component curing type coating agent capable of forming a surface protective layer with excellent weather resistance, acid resistance, stain resistance, and elongation properties, and to a multilayer film having a surface protective layer which is a cured film of the above two-component curing type coating agent. [Background technology]

[0002] Conventionally, surface treatments have been applied to articles such as automobiles, vehicles, aircraft, glass, buildings, and signs to protect their surfaces from dirt and scratches and maintain their appearance. Such surface treatments are carried out by applying a surface protective layer to the surface of the article. Examples of surface treatment methods include (1) a method of applying a coating agent to the surface of the article to form a surface protective layer, and (2) a method of attaching a multilayer film having a surface protective layer and an adhesive layer to the surface of the article.

[0003] The surface protective layer is formed by curing a coating agent containing a polyol and a polyisocyanate. For example, Patent Document 1 discloses a high-solids content coating composition containing (A) a hydroxyl group-containing compound with a weight-average molecular weight of 1000 or less and a hydroxyl value of 200 to 800, and (B) a polyisocyanate compound. Furthermore, Patent Document 1 discloses that component (A) is a reaction product of a carboxyl group-containing compound and an epoxy group-containing compound. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2002-138247 [Overview of the project] [Problems that the invention aims to solve]

[0005] Surface-treated items are often used outdoors. Therefore, these items are exposed to wind, rain, and high humidity, and are irradiated with ultraviolet light for extended periods. In such cases, unevenness and discoloration may occur on the surface protective layer. Specifically, unevenness may initially appear on a portion of the surface, then gradually spread over time, along with discoloration to yellow or white areas. Finally, the unevenness may spread across the entire surface of the protective layer, and the entire protective layer may become discolored to yellow or white. This unevenness and discoloration of the surface protective layer is thought to be caused by the degradation of components within the protective layer due to light, or by solutes contained in rain or moisture in the air adhering to the surface of the protective layer. The occurrence of unevenness and discoloration on the surface protective layer leads to a poor appearance. Therefore, the surface protective layer is required to have excellent weather resistance.

[0006] Furthermore, when the surface of an item with surface treatment comes into contact with acid rain due to rainfall, the surface protective layer may whiten, leading to an unsightly appearance. Therefore, the surface protective layer is also required to have excellent acid resistance.

[0007] Furthermore, the adhesion of oily stains such as fingerprints to the surface protective layer could also lead to an unsightly appearance. Therefore, the surface protective layer is required to have excellent stain resistance so that oily stains can be easily wiped off even if they adhere to it.

[0008] Furthermore, tensile forces may be applied to the surface protection layer when it is attached to the surface of an article or when an article that has undergone surface treatment is molded. However, if the surface protection layer has low elongation, it may not be able to withstand the tensile force, resulting in cracks or breakage. Therefore, it is also required that the surface protection layer has excellent elongation properties.

[0009] As mentioned above, Patent Document 1 discloses a solid-content coating composition, but the surface protective layer formed using this solid-content coating composition has problems such as low weather resistance.

[0010] Therefore, the present invention aims to provide a two-component curing type coating agent that can form a surface protective layer with excellent weather resistance, acid resistance, stain resistance, and elongation properties, and a multilayer film having a surface protective layer which is a cured film of the above two-component curing type coating agent. [Means for solving the problem]

[0011] <Two-component curing coating agent> The present invention is characterized by comprising a main component containing a polyol that includes an epoxy polyol (P), which is a reaction product of an epoxy group-containing compound (e) and a carboxyl group-containing compound (c), and an acrylic polyol (A), and a curing agent containing a polyisocyanate.

[0012] In the two-component curable coating agent of the present invention, a surface protective layer can be formed by curing the two-component curable coating agent by reacting the polyol contained in the main component with the polyisocyanate contained in the curing agent to form polyurethane. In the two-component curable coating agent of the present invention, the polyol in the main component contains acrylic polyol (A), which enables the formation of a surface protective layer with excellent acid resistance and weather resistance. Furthermore, the polyol in the main component further contains epoxy polyol (P), which is a reaction product of an epoxy group-containing compound (e) and a carboxyl group-containing compound (c), which enables the formation of a surface protective layer with excellent stain resistance and elongation properties.

[0013] Thus, in the two-component curing coating agent of the present invention, the main component polyol contains a combination of acrylic polyol (A) and epoxy polyol (P), making it possible to form a surface protective layer with excellent weather resistance, acid resistance, stain resistance, and elongation properties.

[0014] [Main agent] The two-component curable coating agent of the present invention comprises a main agent containing a polyol. The polyol contained in the main agent includes an epoxy polyol (P) and an acrylic polyol (A).

[0015] [Epoxy polyol (P)] The epoxy polyol (P) contained in the main agent is a reaction product of an epoxy group-containing compound (e) and a carboxyl group-containing compound (c).

[0016] (Epoxy group-containing compound (e)) The epoxy group-containing compound (e) used for forming the epoxy polyol (P) is preferably a compound having two or more epoxy groups in one molecule. The epoxy group-containing compound (e) preferably has 5 or less epoxy groups in one molecule. It is particularly preferable that the epoxy group-containing compound (e) has two epoxy groups in one molecule.

[0017] Preferred examples of the epoxy group-containing compound (e) include a reaction product of a hydroxyl group-containing compound and epihalohydrin. The epoxy group-containing compound (e) can be obtained by subjecting epihalohydrin to ring-opening addition to the hydroxyl groups of the hydroxyl group-containing compound, then cyclizing the resulting ring-opening adduct through elimination reaction of hydrogen atoms and halogen atoms to form epoxy groups. Preferably, by reacting epihalohydrin with each of at least two hydroxyl groups of the hydroxyl group-containing compound, an epoxy group-containing compound (e) having at least two epoxy groups is obtained.

[0018] ·Hydroxyl group-containing compound The hydroxyl group-containing compound used for forming the epoxy group-containing compound (e) is a compound having two or more hydroxyl groups (-OH) in one molecule. The hydroxyl group-containing compound preferably has 6 or less hydroxyl groups in one molecule. It is particularly preferable that the hydroxyl group-containing compound has two hydroxyl groups in one molecule.

[0019] Examples of hydroxyl group-containing compounds include aromatic polyhydric phenols such as phenol, bisphenol A, bisphenol F, bisphenol AD, and bisphenol S; polyhydric alcohols having an alicyclic structure such as hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated bisphenol AD, hydrogenated bisphenol S, and 1,4-cyclohexanedimethanol; and acyclic aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, hexanediol, diethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, and dipentaerythritol. Hydroxyl group-containing compounds may be used alone or in combination of two or more.

[0020] As the hydroxyl group-containing compound, a polyhydric alcohol having an alicyclic structure is preferred. By using a polyhydric alcohol having an alicyclic structure, the alicyclic structure can be introduced into the epoxy group-containing compound (e), thereby forming a surface protective layer with excellent weather resistance, acid resistance, stain resistance, and elongation properties.

[0021] In this invention, "alicyclic structure" refers to a structure in which carbon atoms are bonded in a ring and does not possess aromaticity. Furthermore, "aromaticity" refers to a ring structure that follows Hückel's rule and has (4n+2) π electrons (where n is a natural number).

[0022] Examples of alicyclic structures in polyhydric alcohols having an alicyclic structure include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cyclooctane, and cycloalkane structures such as cyclodecane. Among these, the cyclohexane structure is preferred. The hydroxyl group-containing compound may contain one alicyclic structure, or it may contain two or more alicyclic structures.

[0023] As polyhydric alcohols having an alicyclic structure in hydroxyl group-containing compounds, hydrogenated bisphenol A and hydrogenated bisphenol F are preferred, with hydrogenated bisphenol A being more preferred.

[0024] • Epihalohydrin Examples of epihalohydrins used in the formation of epoxy group-containing compound (e) include epichlorohydrin, epibromohydrin, epifluorohydrin, epiiodohydrin, methylepichlorohydrin, and methylepibromohydrin. Among these, epichlorohydrin is preferred. Epihalohydrins may be used alone or in combination of two or more.

[0025] As a method for producing epoxy group-containing compound (e), a known method of glycidyl etherification of a hydroxyl group-containing compound using an epihalohydrin can be used. For example, a method can be described that includes a first step of reacting a hydroxyl group-containing compound with an epihalohydrin to obtain a ring-opened adduct by ring-opening addition of the epihalohydrin to the hydroxyl group of the hydroxyl group-containing compound, and a second step of forming an epoxy group by ring-closing this ring-opened adduct in the presence of a basic compound through the elimination reaction of hydrogen and halogen atoms to form an epoxy group, thereby obtaining epoxy group-containing compound (e).

[0026] Examples of basic compounds used in the second step include potassium hydroxide, sodium hydroxide, barium hydroxide, magnesium hydroxide, sodium carbonate, and potassium carbonate. Sodium hydroxide is preferred among these. The basic compounds may be used individually or in combination of two or more.

[0027] Examples of epoxy group-containing compounds (e) include diglycidyl ethers of aromatic polyhydric phenols such as bisphenol A diglycidyl ether and bisphenol F diglycidyl ether; diglycidyl ethers of polyhydric alcohols having an alicyclic structure such as hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether and 1,4-cyclohexanedimethanol diglycidyl ether; and diglycidyl ethers of acyclic aliphatic polyhydric alcohols such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether and hexanediol diglycidyl ether. Epoxy group-containing compounds (e) may be used alone or in combination of two or more.

[0028] The epoxy group-containing compound (e) preferably contains an alicyclic structure. An epoxy group-containing compound (e) having an alicyclic structure can form a surface protective layer with excellent weather resistance, acid resistance, stain resistance, and elongation properties.

[0029] Examples of alicyclic structures in epoxy group-containing compound (e) include cyclopropane structures, cyclobutane structures, cyclopentane structures, cyclohexane structures, cyclooctane structures, and cycloalkane structures such as cyclodecane structures. Among these, the cyclohexane structure is preferred. Epoxy group-containing compound (e) may contain one type of alicyclic structure, or it may contain two or more types of alicyclic structures.

[0030] The epoxy group-containing compound (e) having an alicyclic structure can be obtained, for example, by reacting a polyhydric alcohol having an alicyclic structure with an epihalohydrin. The epoxy group-containing compound (e) having an alicyclic structure is preferably a diglycidyl ether of a polyhydric alcohol having an alicyclic structure, more preferably hydrogenated bisphenol A diglycidyl ether and hydrogenated bisphenol F diglycidyl ether, and even more preferably hydrogenated bisphenol A diglycidyl ether.

[0031] The epoxy group-containing compound (e) is not limited to the reaction product of the hydroxyl group-containing compound and epihalohydrin described above. For example, as the epoxy group-containing compound (e), there is also an epoxy group-containing compound obtained by epoxidizing the carbon-carbon double bond of a compound having a carbon-carbon double bond with an oxidizing agent such as hydrogen peroxide. Examples of compounds having a carbon-carbon double bond include cyclohexene, cyclooctene, bisphenol A diallyl ether, hydrogenated bisphenol A diallyl ether, 1,5-pentanediol diallyl ether, and 1,6-hexanediol diallyl ether.

[0032] (Carboxyl group-containing compound (c)) The epoxy polyol (P) contained in the main component is obtained by reacting the epoxy group-containing compound (e) described above with the carboxyl group-containing compound (c). As shown in formula (I) below, the epoxy group of the epoxy group-containing compound (e) undergoes ring-opening addition to the carboxyl group of the carboxyl group-containing compound (c), generating a hydroxyl group along with an ester bond, thereby obtaining the epoxy polyol (P) having a hydroxyl group.

[0033] [ka]

[0034] A carboxyl group-containing compound (c) is a compound having one or more carboxyl groups (-COOH) in one molecule.

[0035] Examples of carboxyl group-containing compounds (c) include monocarboxylic acids such as acetic acid, propionic acid, butyric acid, 2-ethylhexanoic acid, octanoic acid, dodecanoic acid, palmitic acid, stearic acid, oleic acid, pivalic acid, versatic acid, benzoic acid, hydroxycaprylic acid, hydroxylauric acid, hydroxypalmitic acid, hydroxystearic acid, dihydroxystearic acid, glycolic acid, lactic acid, hydroxypivalic acid, dimethylolpropionic acid, dimethylolbutanoic acid, and gluconic acid; and polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanediic acid, tetrahydrophthalic acid, phthalic acid, butanetricarboxylic acid, butanetetracarboxylic acid, malic acid, citric acid, and tartaric acid. Carboxyl group-containing compounds (c) may be used alone or in combination of two or more.

[0036] The carboxyl group-containing compound (c) preferably contains a carboxyl group-containing compound (c1) having one carboxyl group per molecule. The carboxyl group-containing compound (c1) having one carboxyl group per molecule can improve the elongation of the surface protective layer.

[0037] The carboxyl group-containing compound (c1) preferably has a hydroxyl group. That is, the carboxyl group-containing compound (c1) preferably has a hydroxyl group and one carboxyl group per molecule. By using a carboxyl group-containing compound (c1) that has a hydroxyl group, the epoxy polyol (P) can further have hydroxyl groups derived from the carboxyl group-containing compound (c1). By reacting such an epoxy polyol (P) with a polyisocyanate, the crosslinking density of the resulting polyurethane can be moderately improved, thereby forming a surface protective layer that not only has excellent weather resistance, acid resistance, and stain resistance, but also excellent elongation.

[0038] The carboxyl group-containing compound (C1) preferably has one or more hydroxyl groups per molecule. The carboxyl group-containing compound (C1) preferably has six or fewer hydroxyl groups per molecule. The carboxyl group-containing compound (C1) is particularly preferred to have one hydroxyl group per molecule.

[0039] The carboxyl group-containing compound (C1) preferably has 8 or more carbon atoms, and more preferably 10 or more. Having 8 or more carbon atoms in the carboxyl group-containing compound (C1) improves the elongation of the surface protective layer.

[0040] Examples of carboxyl group-containing compounds (c1) include monocarboxylic acids such as acetic acid, propionic acid, butyric acid, 2-ethylhexanoic acid, octanoic acid, dodecanoic acid, palmitic acid, stearic acid, oleic acid, pivalic acid, versatic acid, benzoic acid, hydroxycaprylic acid, hydroxylauric acid, hydroxypalmitic acid, hydroxystearic acid, dihydroxystearic acid, glycolic acid, lactic acid, hydroxypivalic acid, dimethylolpropionic acid, dimethylolbutanoic acid, and gluconic acid. Among these, hydroxycaprylic acid, hydroxylauric acid, hydroxypalmitic acid, hydroxystearic acid, and dihydroxystearic acid are preferred, with hydroxystearic acid being more preferred.

[0041] In the carboxyl group-containing compound (c), the content of carboxyl group-containing compound (c1) having one carboxyl group per molecule is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 100% by mass. That is, it is preferable that the carboxyl group-containing compound (c) consists only of carboxyl group-containing compound (c1) having one carboxyl group per molecule. By setting the content of carboxyl group-containing compound (c1) having one carboxyl group per molecule to 50% by mass or more, the elongation of the surface protective layer can be further improved.

[0042] The carboxyl group-containing compound (c) may also include, in addition to the carboxyl group-containing compound (c1) having one carboxyl group in one molecule as described above, a carboxyl group-containing compound (c2) having two or more carboxyl groups in one molecule. By using carboxyl group-containing compound (c1) and carboxyl group-containing compound (c2) in combination, a surface protective layer with excellent weather resistance, acid resistance, stain resistance, and elongation properties can be formed.

[0043] The carboxyl group-containing compound (C2) preferably has two or more carboxyl groups in one molecule. Furthermore, the carboxyl group-containing compound (C2) preferably has four or fewer carboxyl groups in one molecule. It is particularly preferable that the carboxyl group-containing compound (C2) has two carboxyl groups in one molecule.

[0044] The carboxyl group-containing compound (C2) preferably has 4 or more carbon atoms, more preferably 5 or more, and even more preferably 6 or more. Having 4 or more carbon atoms in the carboxyl group-containing compound (C2) improves the elongation of the surface protective layer.

[0045] Examples of carboxyl group-containing compounds (C2) include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanediic acid, tetrahydrophthalic acid, phthalic acid, butanetricarboxylic acid, butanetetracarboxylic acid, malic acid, citric acid, and tartaric acid. Among these, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanediic acid, tetrahydrophthalic acid, and phthalic acid are preferred, with succinic acid, adipic acid, and azelaic acid being more preferred.

[0046] When carboxyl group-containing compound (c) contains carboxyl group-containing compound (c1) and carboxyl group-containing compound (c2), the content of carboxyl group-containing compound (c1) in carboxyl group-containing compound (c) is preferably 50% by mass or more, and more preferably 70% by mass or more. When carboxyl group-containing compound (c) contains carboxyl group-containing compound (c1) and carboxyl group-containing compound (c2), the content of carboxyl group-containing compound (c1) in carboxyl group-containing compound (c) is preferably 95% by mass or less, and more preferably 90% by mass or less. When the content of carboxyl group-containing compound (c1) is 50% by mass or more, the elongation of the surface protective layer can be improved.

[0047] Furthermore, when carboxyl group-containing compound (c) contains carboxyl group-containing compound (c1) and carboxyl group-containing compound (c2), the content of carboxyl group-containing compound (c2) in carboxyl group-containing compound (c) is preferably 5% by mass or more, and more preferably 10% by mass or more. When carboxyl group-containing compound (c) contains carboxyl group-containing compound (c1) and carboxyl group-containing compound (c2), the content of carboxyl group-containing compound (c2) in carboxyl group-containing compound (c) is preferably 50% by mass or less, and more preferably 30% by mass or less. When the content of carboxyl group-containing compound (c2) is 50% by mass or less, the elongation of the surface protective layer can be improved.

[0048] Epoxy polyols (P) are obtained by reacting an epoxy group-containing compound (e) with a carboxyl group-containing compound (c). Preferably, epoxy polyols (P) are obtained by reacting each of the at least two epoxy groups of the epoxy group-containing compound (e) with the carboxyl group of the carboxyl group-containing compound (c).

[0049] Furthermore, when using a carboxyl group-containing compound (c1) and a carboxyl group-containing compound (c2) having a hydroxyl group as the carboxyl group-containing compound (c), the epoxy polyol (P) is obtained by first adding the epoxy group-containing compound (e) to each of the at least two carboxyl groups of the carboxyl group-containing compound (c2) in a ring-opening manner to obtain an intermediate product having at least two epoxy groups, and then adding the carboxyl group-containing compound (c1) to each of the at least two epoxy groups of this intermediate product in a ring-opening manner to obtain the epoxy polyol (P i It is preferable that it contains ).

[0050] Such epoxy polyols (P i ) has at its molecular end a hydroxyl group that was present in the carboxyl group-containing compound (c1) and a hydroxyl group formed by the ring-opening addition reaction between the epoxy group of the intermediate product and the carboxyl group of the carboxyl group-containing compound (c1). Such epoxy polyol (P i By reacting an epoxy polyol (P) containing ) with a polyisocyanate, the crosslinking density of the resulting polyurethane can be moderately improved, thereby forming a surface protective layer that not only has excellent weather resistance, acid resistance, and stain resistance, but also excellent elongation properties.

[0051] Epoxy polyol (P i ) more preferably, An epoxy group-containing compound (e) having two epoxy groups in one molecule, A carboxyl group-containing compound (c2) having two carboxyl groups in one molecule, A reaction product of a carboxyl group-containing compound (c1) having one carboxyl group and one or more hydroxyl groups in one molecule, After obtaining an intermediate product having epoxy groups at both molecular terminals respectively, obtained by subjecting the epoxy group-containing compound (e) to ring-opening addition to each of the two carboxyl groups of the carboxyl group-containing compound (c2), an epoxy polyol (P i ) can be mentioned.

[0052] Epoxy polyol (P i ) particularly preferably has a structure represented by the following general formula (II).

[0053]

Chemical Formula

[0054] The content of epoxy polyol (P i ) in epoxy polyol (P) is preferably 20% by mass or more, more preferably 40% by mass or more. The content of epoxy polyol (P i ) in epoxy polyol (P) is preferably 100% by mass or less. By setting the content of epoxy polyol (P i ) to 20% by mass or more, it is possible to form a surface protective layer that not only has excellent weather resistance, acid resistance and antifouling properties, but also excellent stretchability.

[0055] When using carboxyl group-containing compound (c1) and carboxyl group-containing compound (c2) as carboxyl group-containing compound (c), the order in which the epoxy group-containing compound (e), carboxyl group-containing compound (c1), and carboxyl group-containing compound (c2) are mixed is not particularly limited. For example, it is preferable to mix epoxy group-containing compound (e), carboxyl group-containing compound (c1), and carboxyl group-containing compound (c2) and then react them. This results in the epoxy polyol (P) described above. i An epoxy polyol (P) containing ) is obtained.

[0056] The reaction between the carboxyl group-containing compound (c) and the epoxy group-containing compound (e) may be carried out in the presence of a catalyst. The catalyst is not particularly limited, but examples include alkali metal hydroxides such as sodium hydroxide and lithium hydroxide; tertiary amines such as triethylamine, tributylamine, pyridine, and dimethylbenzylamine; imidazoles such as 2-ethyl-4-methylimidazole; quaternary ammonium salts such as triethylbenzylammonium chloride and tetramethylammonium chloride; phosphonium salts such as tetrabutylphosphonium chloride and ethyltriphenylphosphonium iodide; and phosphines such as triphenylphosphine. The catalyst may be used alone or in combination of two or more types.

[0057] In the two-component curing coating agent of the present invention, the content of epoxy polyol (P) in the polyol main component is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, and more preferably 40 parts by mass or more, based on 100 parts by mass of the total amount of epoxy polyol (P) and acrylic polyol (A). The content of epoxy polyol (P) in the polyol contained in the main component is preferably 99 parts by mass or less, more preferably 95 parts by mass or less, more preferably 92 parts by mass or less, more preferably 80 parts by mass or less, and more preferably 65 parts by mass or less, based on 100 parts by mass of the total amount of epoxy polyol (P) and acrylic polyol (A). When the epoxy polyol (P) content is 30 parts by mass or more, the elongation of the surface protective layer can be improved. When the epoxy polyol (P) content is 99 parts by mass or less, the excellent elongation of the surface protective layer can be maintained and weather resistance can also be improved.

[0058] [Acrylic polyol (A)] The polyol contained in the main component of the two-component curable coating agent of the present invention includes, in addition to the epoxy polyol (P) described above, acrylic polyol (A). Acrylic polyol (A) is an acrylic polymer obtained by polymerizing (meth)acrylic monomers and having hydroxyl groups at the terminal or side chains. Acrylic polyol (A) can be obtained by polymerizing (meth)acrylic monomers using a conventional method for producing acrylic polymers in the presence of a radical polymerization initiator.

[0059] Note that (meth)acrylic means acrylic or methacrylic. Also, (meth)acrylate means acrylate or methacrylate.

[0060] The acrylic polyol (A) preferably contains a (meth)acrylic monomer (x) component having a glass transition temperature exceeding -10°C and an alicyclic structure, and a (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or lower.

[0061] As the acrylic polyol (A), a polymer of (meth)acrylic monomers containing a (meth)acrylic monomer (x) having a glass transition temperature greater than -10°C and an alicyclic structure, and a (meth)acrylic monomer (y) having a glass transition temperature of -10°C or lower is preferred, and a copolymer of a (meth)acrylic monomer (x) having a glass transition temperature greater than -10°C and an alicyclic structure and a (meth)acrylic monomer (y) having a glass transition temperature of -10°C or lower is more preferred.

[0062] Furthermore, a (meth)acrylic monomer (x) having a glass transition temperature exceeding -10°C and an alicyclic structure is sometimes simply referred to as "(meth)acrylic monomer (x)". Similarly, a (meth)acrylic monomer (y) having a glass transition temperature of -10°C or lower is sometimes simply referred to as "(meth)acrylic monomer (y)".

[0063] • (meth)acrylic monomer(x) The glass transition temperature of the (meth)acrylic monomer (x) is preferably above -10°C, more preferably above 0°C, and even more preferably above 15°C. The glass transition temperature of the (meth)acrylic monomer (x) is preferably 200°C or less, more preferably 150°C or less, and even more preferably 120°C or less. Using a (meth)acrylic monomer (x) with a glass transition temperature above -10°C can improve the antifouling and weather resistance of the surface protective layer.

[0064] In this invention, "(meth)acrylic monomer glass transition temperature" refers to the glass transition temperature of a homopolymer obtained by homopolymerizing (meth)acrylic monomers. The glass transition temperature of the homopolymer of (meth)acrylic monomers is measured by differential scanning calorimetry (DSC) in accordance with JIS K7121 (1987), and the measured value obtained is referred to as "(meth)acrylic monomer glass transition temperature".

[0065] The (meth)acrylic monomer (x) preferably has an alicyclic structure. Examples of alicyclic structures in the (meth)acrylic monomer (x) include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cyclooctane, and cyclodecane structures, as well as cycloalkane structures, tetrahydrodicyclopentadiene, adamantane, and isobornyl structures. Among these, the cycloalkane structure is preferred, and the cyclohexane structure is more preferred.

[0066] Examples of (meth)acrylic monomers (x) include isobornyl acrylate (Tg: 94°C), isobornyl methacrylate (Tg: 180°C), cyclohexyl acrylate (Tg: 16°C), cyclohexyl methacrylate (Tg: 56°C), dicyclopentanyl acrylate (Tg: 120°C), 1,4-cyclohexanedimethanol monoacrylate (Tg: 18°C), 1-ethylcyclohexyl acrylate (Tg: 26°C), 1-ethylcyclooctyl acrylate (Tg: 80°C), 2-methyl-2-adamantyl acrylate (Tg: 115°C), 2-methyl-2-adamantyl methacrylate (Tg: 180°C), and adamantyloxymethyl methacrylate (Tg: 100°C). The glass transition temperature of each (meth)acrylic monomer (x) is shown in parentheses. The (meth)acrylic monomer (x) may be used alone or in combination of two or more types.

[0067] Among these, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, and isobornyl methacrylate are preferred as (meth)acrylic monomers (x), cyclohexyl acrylate and cyclohexyl methacrylate are more preferred, and cyclohexyl methacrylate is even more preferred.

[0068] • (meth)acrylic monomer (y) The acrylic polyol (A) preferably contains a (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or lower.

[0069] The glass transition temperature of the (meth)acrylic monomer (y) is preferably -10°C or lower, more preferably -12°C or lower, and even more preferably -15°C or lower. The glass transition temperature of the (meth)acrylic monomer (y) is preferably -90°C or higher. Using a (meth)acrylic monomer (y) with a glass transition temperature of -10°C or lower can improve the elongation of the surface protective layer.

[0070] Examples of (meth)acrylic monomers (y) include hydroxyl group-containing (meth)acrylic monomers (y1) with a glass transition temperature of -10°C or lower, such as 2-hydroxyethyl acrylate (Tg: -15°C), 4-hydroxybutyl acrylate (Tg: -32°C), and the adduct of hydroxyethyl methacrylate and 2 moles of caprolactone (CH2=C(CH3)COO(CH2)2O[CO(CH2)5O]2H) (Tg: -28°C), and caprolactone acrylate [adduct of hydroxyethyl acrylate and 2 moles of caprolactone (CH2=CHCOO(CH2)2O[CO(CH2)5O]2H)] (Tg: -53°C); ethyl acrylate (Tg: -22°C), n-butyl acrylate (Tg: -54°C), isobutyl acrylate (Tg: - Examples include alkyl (meth)acrylates (y2) with a glass transition temperature of -10°C or lower, such as isononyl acrylate (Tg:-90°C), 2-ethylhexyl acrylate (Tg:-85°C), lauryl acrylate (Tg:-30°C), lauryl methacrylate (Tg:-64°C), isodecyl acrylate (Tg:-60°C), isooctyl acrylate (Tg:-54°C), tridecyl acrylate (Tg:-55°C), and tridecyl methacrylate (Tg:-40°C); 2-(2-ethoxyethoxy)ethyl acrylate (Tg:-54°C), 2-methoxyethyl acrylate (Tg:-50°C), ethyl carbitol acrylate (Tg:-67°C), and methoxytriethylene glycol acrylate (Tg:-55°C). The glass transition temperature of each (meth)acrylic monomer (y) is shown in parentheses. (Meth)acrylic monomer (y) may be used alone or in combination of two or more types.

[0071] The (meth)acrylic monomer (y) is preferably a hydroxyl group-containing (meth)acrylic monomer (y1) with a glass transition temperature of -10°C or lower, and an alkyl (meth)acrylate (y2) with a glass transition temperature of -10°C or lower. More preferably, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, isononyl acrylate, and 2-ethylhexyl acrylate are used, and even more preferably, 2-hydroxyethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are used. It is preferable that the alkyl (meth)acrylate (y2) with a glass transition temperature of -10°C or lower does not have a hydroxyl group.

[0072] In acrylic polyol (A), the mass ratio of (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or less to (meth)acrylic monomer (x) component having a glass transition temperature exceeding -10°C and an alicyclic structure [mass of (meth)acrylic monomer (y) component / mass of (meth)acrylic monomer (x) component] is preferably 1.1 or higher, more preferably 1.2 or higher, and more preferably 2.0 or higher. In acrylic polyol (A), the mass ratio of (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or less to (meth)acrylic monomer (x) component having a glass transition temperature exceeding -10°C and an alicyclic structure [mass of (meth)acrylic monomer (y) component / mass of (meth)acrylic monomer (x) component] is preferably 3.6 or lower, more preferably 3.5 or lower, and more preferably 3.0 or lower. If the above mass ratio [(meth)acrylic monomer (y) component / (meth)acrylic monomer (x) component] is 1.1 or higher, the elongation of the surface protective layer can be improved. If the above mass ratio [(meth)acrylic monomer (y) component / (meth)acrylic monomer (x) component] is 3.6 or lower, the antifouling properties of the surface protective layer can be improved.

[0073] The acrylic polyol (A) preferably contains a hydroxyl group-containing (meth)acrylic monomer (z) component whose glass transition temperature exceeds -10°C. Note that "hydroxyl group-containing (meth)acrylic monomer (z) whose glass transition temperature exceeds -10°C" is sometimes simply referred to as "hydroxyl group-containing (meth)acrylic monomer (z)". The hydroxyl group-containing (meth)acrylic monomer (z) preferably does not have an alicyclic structure.

[0074] The glass transition temperature of the hydroxyl group-containing (meth)acrylic monomer (z) is preferably above -10°C, more preferably above -8°C, and even more preferably above -7°C. The glass transition temperature of the hydroxyl group-containing (meth)acrylic monomer (z) is preferably 80°C or lower. Using a hydroxyl group-containing (meth)acrylic monomer (z) with a glass transition temperature above -10°C can improve the acid resistance and antifouling properties of the surface protective layer.

[0075] Examples of hydroxyl group-containing (meth)acrylic monomers (z) include 2-hydroxyethyl methacrylate (Tg: 55°C), 2-hydroxypropyl methacrylate (Tg: 26°C), and 2-hydroxypropyl acrylate (Tg: -7°C). The hydroxyl group-containing (meth)acrylic monomer (z) may be used alone or in combination of two or more. Among these, 2-hydroxyethyl methacrylate is preferred.

[0076] • Acrylic polyol (A1) As the acrylic polyol (A), more preferably, is an acrylic polyol (A1) comprising a (meth)acrylic monomer (x) component having a glass transition temperature greater than -10°C and an alicyclic structure, a hydroxyl group-containing (meth)acrylic monomer (y1) component having a glass transition temperature of -10°C or less, and an alkyl (meth)acrylate (y2) component having a glass transition temperature of -10°C or less, and a (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or less.

[0077] Furthermore, "an acrylic polyol (A1) comprising a (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or lower, which includes a (meth)acrylic monomer (x) component having a glass transition temperature exceeding -10°C and an alicyclic structure, a hydroxyl group-containing (meth)acrylic monomer (y1) component having a glass transition temperature of -10°C or lower, and an alkyl (meth)acrylate (y2) component having a glass transition temperature of -10°C or lower," is sometimes simply referred to as "acrylic polyol (A1)."

[0078] Furthermore, it is preferable that the acrylic polyol (A1) does not contain a hydroxyl group-containing (meth)acrylic monomer (z) component whose glass transition temperature exceeds -10°C.

[0079] In acrylic polyol (A1), the content of the (meth)acrylic monomer (x) component is preferably 10% by mass or more, more preferably 15% by mass or more, and particularly preferably 20% by mass or more. In acrylic polyol (A1), the content of the (meth)acrylic monomer (x) component is preferably 50% by mass or less, more preferably 45% by mass or less, and particularly preferably 42% by mass or less. When the content of the (meth)acrylic monomer (x) component is 10% by mass or more, the acid resistance of the surface protective layer can be improved. When the content of the (meth)acrylic monomer (x) component is 50% by mass or less, the excellent elongation of the surface protective layer can be maintained.

[0080] In acrylic polyol (A1), the content of hydroxyl group-containing (meth)acrylic monomer (y1) component having a glass transition temperature of -10°C or lower is preferably 7% by mass or more, more preferably 10% by mass or more, and particularly preferably 14% by mass or more. In acrylic polyol (A1), the content of hydroxyl group-containing (meth)acrylic monomer (y1) component having a glass transition temperature of -10°C or lower is preferably 35% by mass or less, more preferably 30% by mass or less, and particularly preferably 27% by mass or less. When the content of hydroxyl group-containing (meth)acrylic monomer (y1) component is 7% by mass or more, the weather resistance and antifouling properties of the surface protective layer can be improved. When the content of hydroxyl group-containing (meth)acrylic monomer (y1) component is 35% by mass or less, the excellent elongation properties of the surface protective layer can be maintained.

[0081] In acrylic polyol (A1), the content of alkyl (meth)acrylate (y2) component having a glass transition temperature of -10°C or lower is preferably 30% by mass or more, more preferably 35% by mass or more, and particularly preferably 42% by mass or more. In acrylic polyol (A1), the content of alkyl (meth)acrylate (y2) component having a glass transition temperature of -10°C or lower is preferably 80% by mass or less, more preferably 70% by mass or less, and particularly preferably 66% by mass or less. When the content of alkyl (meth)acrylate (y2) component is 30% by mass or more, the elongation of the surface protective layer can be improved. When the content of alkyl (meth)acrylate (y2) component is 80% by mass or less, the acid resistance of the surface protective layer can be improved.

[0082] • Acrylic polyol (A2) Furthermore, as the acrylic polyol (A), more preferably, is an acrylic polyol (A2) comprising a (meth)acrylic monomer (x) component having a glass transition temperature greater than -10°C and an alicyclic structure, an alkyl (meth)acrylate (y2) component having a glass transition temperature of -10°C or less, a (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or less, and a hydroxyl group-containing (meth)acrylic monomer (z) component having a glass transition temperature greater than -10°C.

[0083] Furthermore, an acrylic polyol (A2) containing a (meth)acrylic monomer (x) component having a glass transition temperature exceeding -10°C and an alicyclic structure, an alkyl (meth)acrylate (y2) component having a glass transition temperature of -10°C or less, a (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or less, and a hydroxyl group-containing (meth)acrylic monomer (z) component having a glass transition temperature exceeding -10°C, is sometimes simply referred to as "acrylic polyol (A2)".

[0084] In acrylic polyol (A2), the content of the (meth)acrylic monomer (x) component is preferably 10% by mass or more, more preferably 15% by mass or more, and particularly preferably 20% by mass or more. In acrylic polyol (A2), the content of the (meth)acrylic monomer (x) component is preferably 50% by mass or less, more preferably 45% by mass or less, and particularly preferably 42% by mass or less. When the content of the (meth)acrylic monomer (x) component is 10% by mass or more, the acid resistance of the surface protective layer can be improved. When the content of the (meth)acrylic monomer (x) component is 50% by mass or less, the excellent elongation of the surface protective layer can be maintained.

[0085] In acrylic polyol (A2), the content of alkyl (meth)acrylate (y2) component having a glass transition temperature of -10°C or lower is preferably 30% by mass or more, more preferably 35% by mass or more, and particularly preferably 42% by mass or more. In acrylic polyol (A2), the content of alkyl (meth)acrylate (y2) component having a glass transition temperature of -10°C or lower is preferably 80% by mass or less, more preferably 70% by mass or less, and particularly preferably 66% by mass or less. When the content of alkyl (meth)acrylate (y2) component is 30% by mass or more, the elongation of the surface protective layer can be improved. When the content of alkyl (meth)acrylate (y2) component is 80% by mass or less, the acid resistance of the surface protective layer can be improved.

[0086] In acrylic polyol (A2), the content of hydroxyl group-containing (meth)acrylic monomer (z) component having a glass transition temperature exceeding -10°C is preferably 7% by mass or more, more preferably 10% by mass or more, and particularly preferably 16% by mass or more. In acrylic polyol (A2), the content of hydroxyl group-containing (meth)acrylic monomer (z) component having a glass transition temperature exceeding -10°C is preferably 40% by mass or less, more preferably 35% by mass or less, and particularly preferably 30% by mass or less. When the content of hydroxyl group-containing (meth)acrylic monomer (z) component is 7% by mass or more, the weather resistance and antifouling properties of the surface protective layer can be improved. When the content of hydroxyl group-containing (meth)acrylic monomer (z) component is 40% by mass or less, the excellent elongation properties of the surface protective layer can be maintained.

[0087] Conventional known methods can be used as the polymerization method for acrylic polyol (A). For example, one method is to polymerize the above-mentioned monomer in the presence of a radical polymerization initiator. For example, one method is to supply the above-mentioned monomer, polymerization initiator, and polymerization solvent into a reactor and heat at a temperature of 60 to 80°C for 4 to 48 hours to radically polymerize the monomer.

[0088] The weight-average molecular weight of acrylic polyol (A) is preferably 8,000 or more, and more preferably 10,000 or more. The weight-average molecular weight of acrylic polyol (A) is preferably 120,000 or less, and more preferably 100,000 or less. When the weight-average molecular weight of acrylic polyol (A) is 8,000 or more, the acid resistance and weather resistance of the surface protective layer can be improved. When the weight-average molecular weight of acrylic polyol (A) is 120,000 or less, the elongation and antifouling properties of the surface protective layer can be improved.

[0089] The weight-average molecular weight of acrylic polyol (A) refers to the value obtained by converting the molecular weight measured by gel permeation chromatography (GPC) to a polystyrene equivalent. For example, it can be measured under the following measurement conditions.

[0090] Acrylic polyol (A) is dissolved in tetrahydrofuran to obtain a sample with an acrylic polyol (A) concentration of 2.0 g / L. Using this sample, the weight-average molecular weight of acrylic polyol (A) is measured using a gel permeation chromatograph (GPC) equipped with a differential refractive index detector (RID). The weight-average molecular weight of acrylic polyol (A) can be measured using the following measuring apparatus and conditions. Measuring device: Tosoh Corporation, product name "HLC-8320GPC" Differential refractive index detector: An RI detector built into the above measuring device. Columns: Two "TSKgel SuperHZM-H" columns manufactured by Tosoh Corporation. Mobile phase: tetrahydrofuran Column flow rate: 0.35 mL / min Sample concentration: 2.0 g / L Injection volume: 10μL Measurement temperature: 40℃ Molecular weight marker: Standard polystyrene (standard material manufactured by POLYMER LABORATORIES LTD.) (POLYSTYRENE-MEDIUM MOLECULAR WEIGHT CALIBRATION KIT)

[0091] The hydroxyl value of acrylic polyol (A) is preferably 25 mg KOH / g or more, more preferably 30 mg KOH / g or more, and even more preferably 36 mg KOH / g or more. The hydroxyl value of acrylic polyol (A) is preferably 135 mg KOH / g or less, more preferably 130 mg KOH / g or less, and particularly preferably 125 mg KOH / g or less. When the hydroxyl value of acrylic polyol (A) is 25 mg KOH / g or more, the weather resistance of the surface protective layer can be improved. When the hydroxyl value of acrylic polyol (A) is 135 mg KOH / g or less, the excellent elongation of the surface protective layer can be maintained.

[0092] The hydroxyl value of acrylic polyol (A) refers to the value measured in accordance with Method 4.2 B of JIS K 1557-1:2007 (ISO 14900:2001) "Plastics - Test methods for polyurethane raw material polyols - Part 1: Method for determining hydroxyl value".

[0093] The glass transition temperature of acrylic polyol (A) is preferably -60°C or higher, and more preferably -50°C or higher. The glass transition temperature of acrylic polyol (A) is preferably 0°C or lower, and more preferably -2°C or lower. When the glass transition temperature of acrylic polyol (A) is -60°C or higher, the acid resistance and antifouling properties of the surface protective layer can be improved. When the glass transition temperature of acrylic polyol (A) is 0°C or lower, the elongation properties of the surface protective layer can be improved.

[0094] The glass transition temperature of acrylic polyol (A) can be calculated using the Fox equation shown in equation (1) below, using the content ratio (weight fraction) of each monomer constituting acrylic polyol (A) and the glass transition temperature of each monomer.

[0095]

number

[0096] The "glass transition temperature of monomer i" refers to the glass transition temperature of a homopolymer obtained by homopolymerizing monomer i. The glass transition temperature of the monomer i homopolymer is measured by differential scanning calorimetry (DSC) in accordance with JIS K7121 (1987), and the measured value obtained is referred to as the "glass transition temperature of monomer i."

[0097] In the two-component curing coating agent of the present invention, the content of acrylic polyol (A) in the polyol contained in the main component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, more preferably 8 parts by mass or more, more preferably 20 parts by mass or more, and more preferably 35 parts by mass or more, based on 100 parts by mass of the total amount of epoxy polyol (P) and acrylic polyol (A). The content of acrylic polyol (A) in the polyol contained in the main component is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and more preferably 60 parts by mass or less, based on 100 parts by mass of the total amount of epoxy polyol (P) and acrylic polyol (A). When the content of acrylic polyol (A) is 1 part by mass or more, the acid resistance and weather resistance of the surface protective layer can be improved. When the content of acrylic polyol (A) is 70 parts by mass or less, the elongation and antifouling properties of the surface protective layer can be improved.

[0098] The main component of a two-component curing coating agent may contain a curing catalyst. Examples of curing catalysts include organometallic compounds such as dibutyltin oxide, 2-ethylcaproate tin, octoate tin, and dibutyltin dilaurate. The curing catalyst may be used alone or in combination of two or more types.

[0099] [Hardening agent] The two-component curing coating agent of the present invention contains a curing agent containing polyisocyanate. The polyisocyanate has two or more isocyanate groups (-NCO) in one molecule, but preferably three or more. Using a polyisocyanate having three or more isocyanate groups in one molecule can improve the antifouling properties of the surface protective layer.

[0100] Examples of polyisocyanates include aliphatic polyisocyanates and polyisocyanates having an alicyclic structure. Polyisocyanates may be used alone or in combination of two or more types.

[0101] Examples of aliphatic polyisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, and acyclic aliphatic polyisocyanates such as 2-isocyanatoethyl-2,6-diisocyanatohexanoate. Among these, hexamethylene diisocyanate is preferred.

[0102] Examples of polyisocyanates having an alicyclic structure include 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), isophorone diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), and 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated m-XDI).

[0103] Examples of polyisocyanates include modified polyisocyanates. Modified polyisocyanates include isocyanurates, biuretes, and adducts of polyisocyanates. Three molecules of polyisocyanate can form isocyanurates or biuretes. In addition, a trimer adduct is formed by the reaction of three molecules of polyisocyanate with trimethylolpropane.

[0104] Examples of modified polyisocyanates include, for example, Biuret and isocyanurate derivatives of aliphatic polyisocyanates such as ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, and dodecamethylene diisocyanate; Biuret and isocyanurate derivatives of polyisocyanates having an alicyclic structure, such as 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), isophorone diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), and 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated m-XDI); Trimeric adduct of trimethylolpropane (TMP) and hydrogenated MDI; A trimer adduct of 3 moles of any one polyisocyanate, such as isophorone diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), and 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated m-XDI), and 1 mole of trimethylolpropane (TMP); Adducts of trimethylolpropane (TMP), 2 moles of isophorone diisocyanate, and 1 mole of hexamethylene diisocyanate (HDI); and Examples include bifunctional polyurethane diisocyanates obtained by the addition reaction of a diol with an aliphatic diisocyanate such as ethylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate.

[0105] As for the polyisocyanate, biuret polyisocyanates and isocyanurates of polyisocyanates are preferred, isocyanurates of polyisocyanates are more preferred, and isocyanurates of aliphatic polyisocyanates are particularly preferred. These polyisocyanates can be used to form a surface protective layer with excellent weather resistance, acid resistance, stain resistance, and elongation properties.

[0106] In a two-component curing coating agent, the equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate groups of the polyisocyanate contained in the curing agent to the hydroxyl groups of the polyol contained in the main component is preferably 0.8 or higher, and more preferably 0.9 or higher. In a two-component curing coating agent, the equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate groups of the polyisocyanate contained in the curing agent to the hydroxyl groups of the polyol contained in the main component is preferably 1.2 or lower, and more preferably 1.1 or lower. By setting the equivalent ratio (isocyanate group / hydroxyl group) to 0.8 or higher, a surface protective layer with excellent stain resistance can be formed. By setting the equivalent ratio (isocyanate group / hydroxyl group) to 1.2 or lower, a surface protective layer with excellent weather resistance can be formed.

[0107] The equivalent ratio (isocyanate groups / hydroxyl groups) of the polyisocyanate contained in the curing agent to the hydroxyl groups of the polyol contained in the main component is determined by dividing the number of isocyanate groups in the polyisocyanate by the total number of hydroxyl groups in the polyol.

[0108] The polyol contained in the main component includes multiple types of polyols, such as epoxy polyol (P) and acrylic polyol (A). Therefore, the total number of hydroxyl groups in the polyol is calculated based on the following formula. Number of hydroxyl groups in the entire polyol =(W1×H1 / 56100)+(W2×H2 / 56100)+···+(W m ×H m (56100) (In the formula, W m This is the content (g) of the m-type polyol in the total polyol, H m (where m is the hydroxyl value of m-type polyols, and m is an integer representing the number of polyol types.)

[0109] Furthermore, the hydroxyl value of type m polyol refers to the value obtained by measurement in accordance with Method 4.2 B of JIS K 1557-1:2007 (ISO 14900:2001) "Plastics - Test methods for polyols used in polyurethane raw materials - Part 1: Determination of hydroxyl value".

[0110] The number of isocyanate groups in polyisocyanate is calculated based on the following formula. The isocyanate equivalent is the value obtained by dividing the molecular weight of the polyisocyanate by the number of isocyanate groups in one molecule. Specifically, it refers to the value measured in accordance with JIS K1603. Number of isocyanate groups in polyisocyanates = Polyisocyanate content (g) / Isocyanate equivalent

[0111] The main component and curing agent of a two-component curing coating agent may contain additives as needed, within limits that do not impair the physical properties of the two-component curing coating agent. Examples of additives include antioxidants, light stabilizers, heat stabilizers, antistatic agents, and defoamers.

[0112] The main component and curing agent of a two-component curing coating agent may contain a solvent. If the main component of the two-component curing coating agent contains a solvent, the solid content concentration of the main component is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass. If the curing agent of the two-component curing coating agent contains a solvent, the solid content concentration of the curing agent is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass.

[0113] Examples of solvents include hydrocarbons such as pentane, hexane, heptane, and cyclohexane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and esters such as ethyl acetate and butyl acetate. The solvent may be used alone or in combination of two or more.

[0114] The two-component curable coating agent of the present invention is preferably used to form a surface protection layer for protecting the surface of an article. The cured film of the two-component curable coating agent of the present invention can be used as this surface protection layer. The surface protection layer is preferably used as a multilayer film having this surface protection layer and an adhesive layer. The surface protection layer can then be applied to the surface of the article by adhering this multilayer film to the article surface using the adhesive layer.

[0115] As described above, the two-component curing coating agent of the present invention can form a surface protective layer with excellent weather resistance, acid resistance, and stain resistance. By using such a surface protective layer, the appearance of the surface of an article can be maintained beautifully for a long period of time. Furthermore, the surface protective layer formed by the two-component curing coating agent of the present invention is flexible and has excellent elongation properties. The multilayer film including the surface protective layer is attached to the surface of an article by placing the multilayer film on the surface of the article and then pressing and sliding a squeegee over the surface protective layer. At this time, a tensile force is applied to the multilayer film by the squeegee, but the surface protective layer can withstand such a tensile force, and it is possible to reduce the occurrence of cracks and cuts in the surface protective layer. Therefore, the surface protective layer made using the two-component curing coating agent of the present invention is suitably used as a multilayer film. A multilayer film including a surface protective layer will be described below. <Multilayer film> The multilayer film of the present invention includes a substrate layer, a surface protection layer laminated and integrated on a first surface of the substrate layer and being a cured film of the two-component curable coating agent described above, and an adhesive layer laminated and integrated on a second surface of the substrate layer.

[0116] [Base material layer] The multilayer film of the present invention includes a substrate layer. Preferably, the substrate layer contains at least one of a thermoplastic resin and a thermoplastic elastomer. This improves the elongation of the multilayer film.

[0117] Examples of thermoplastic resins include polyurethane resins, polyolefin resins, polyester resins, polyamide resins, polyvinyl resins, and polycarbonate resins. Examples of thermoplastic elastomers include thermoplastic polyurethane elastomers, thermoplastic styrene elastomers, thermoplastic acrylic elastomers, thermoplastic polyolefin elastomers, thermoplastic polyvinyl chloride elastomers, thermoplastic polyester elastomers, and thermoplastic polyamide elastomers. Each of the thermoplastic resins or thermoplastic elastomers may be used alone or in combination of two or more types.

[0118] In particular, the base layer preferably contains a thermoplastic resin, and more preferably a polyurethane resin. Furthermore, the base layer preferably contains a thermoplastic elastomer, and more preferably a thermoplastic polyurethane elastomer. The thickness of the base layer is not particularly limited, but may be 10 to 300 μm, and preferably 20 to 200 μm.

[0119] [Surface protection layer] The multilayer film of the present invention includes a surface protection layer laminated and integrated onto the first surface of the substrate layer. The surface protection layer is a cured film of the two-component curable coating agent described above.

[0120] Furthermore, any surface of the base layer is defined as the "first surface of the base layer," and the surface of the base layer opposite to the first surface is defined as the "second surface of the base layer." Preferably, one or both of the first and second surfaces of the base layer are the surfaces that have the maximum surface area of ​​the base layer.

[0121] The thickness of the surface protective layer is preferably 1 μm or more, and more preferably 5 μm or more. The thickness of the surface protective layer is preferably 50 μm or less, and more preferably 30 μm or less. By making the surface protective layer thickness 1 μm or more, scratch resistance can be improved. Furthermore, by making the surface protective layer thickness 50 μm or less, the occurrence of appearance defects can be reduced.

[0122] As a method for forming a surface protective layer, a method is used in which the main component and curing agent of a two-component curing type coating agent are mixed, and the two-component curing type coating agent is applied to the first surface of the substrate layer and heated. It is preferable to mix the main component and curing agent of the two-component curing type coating agent immediately before applying the two-component curing type coating agent to the substrate layer.

[0123] Methods for applying a two-component curing coating agent to a substrate layer include, for example, dip coating, spray coating, roll coating, doctor blade coating, and screen printing, as well as casting using a bar coater or applicator.

[0124] Then, the two-component curing coating agent applied to the substrate layer is heat-cured. Upon heating, the polyol and polyisocyanate contained in the two-component curing coating agent react to form polyurethane, causing the two-component curing coating agent to harden and form a surface protective layer.

[0125] The heating temperature for the two-component curing coating agent is preferably 60 to 180°C, and more preferably 80 to 150°C. The heating time for the two-component curing coating agent is preferably 1 to 30 minutes, and more preferably 1 to 10 minutes.

[0126] [Adhesive layer] The multilayer film of the present invention includes an adhesive layer laminated and integrated on the second surface of the substrate layer. The thickness of the adhesive layer is not particularly limited, but is preferably 10 to 200 μm, and more preferably 20 to 100 μm.

[0127] The adhesive layer contains an adhesive. The adhesive is not particularly limited and includes, for example, acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, polyurethane adhesives, fluorine adhesives, and epoxy adhesives, with acrylic adhesives being preferred. The adhesive may be used alone or in combination of two or more types.

[0128] Furthermore, the adhesive layer may contain additives as needed. Examples of additives include tackifiers such as rosin derivative resins, polyterpene resins, petroleum resins, and oil-soluble phenolic resins, as well as plasticizers, fillers, antioxidants, antioxidants, and colorants such as pigments and dyes like carbon black. The adhesive may also be crosslinked with general-purpose crosslinking agents such as aziridine crosslinking agents, epoxy crosslinking agents, and isocyanate crosslinking agents.

[0129] The formation of the adhesive layer is not particularly limited, but is carried out by applying an adhesive composition containing an adhesive, and optionally additives and crosslinking agents, to the second surface of the substrate layer and drying it. This forms an adhesive layer laminated and integrated on the second surface of the substrate layer.

[0130] (metallic glitter layer) The multilayer film of the present invention may further include a metallic gloss layer. The metallic gloss layer allows the multilayer film to exhibit glossiness, enabling the surface of articles such as automobiles to be decorated with a metallic appearance.

[0131] The metallic gloss layer is not particularly limited, but it is sufficient that it be disposed on at least one of the first and second surfaces of the substrate layer. An anchor coat layer may be further disposed between the metallic gloss layer and any adjacent layer as needed.

[0132] The metallic gloss layer preferably contains a metal. Examples of metals include copper, nickel, chromium, titanium, cobalt, molybdenum, zirconium, tungsten, palladium, indium, tin, gold, silver, and aluminum. Among these, indium and aluminum are preferred. These metals may be used individually or in combination of two or more. The thickness of the metallic gloss layer is preferably 1 nm to 100 nm, and more preferably 1.5 nm to 7.5 nm.

[0133] The anchor coat layer is used to improve the adhesion between the metallic gloss layer and the adjacent layer. The anchor coat layer preferably contains an anchor coating agent. Examples of anchor coating agents include polyester resins, melamine resins, urea resins, urea-melamine resins, urethane resins, acrylic resins, and nitrocellulose resins. These anchor coating agents may be used individually or in combination of two or more. The thickness of the anchor coat layer is not particularly limited and may be 0.01 to 1 μm.

[0134] The multilayer film of the present invention is preferably used to protect the surfaces of transportation equipment such as automobiles, trains, and airplanes, as well as glass, buildings, and signs. In other words, the multilayer film of the present invention is preferably used as a surface protection multilayer film. By adhering and integrating the multilayer film to the surface of an article with an adhesive layer, it is possible to protect the surface of the article from dirt and scratches and maintain its appearance for a long period of time.

[0135] In particular, the multilayer film of the present invention is suitably used as a multilayer film for protecting the surface of automobiles. For example, the multilayer film can be used by adhering it to the painted surface of an automobile via an adhesive layer. This makes it possible to maintain the beautiful appearance of the automobile surface for a long period of time.

[0136] The surface protection layer, which consists of a cured film of the two-component curable coating agent of the present invention, is preferably used as a multilayer film as described above, but the application of the surface protection layer is not limited to this form. For example, the surface protection layer can also be formed on the surface of an article by directly applying the two-component curable coating agent to the surface of the article. Such a surface protection layer is laminated and integrated onto the surface of the article without an adhesive layer or substrate layer in between. The surface protection layer can also protect the surface of the article. The article is not particularly limited and can be anything from transportation equipment such as automobiles, trains, and airplanes, to glass, buildings, and signs.

[0137] As a method for directly forming a surface protective layer on the surface of an article using a two-component curing coating agent, the method may be carried out in the same manner as described above for forming a surface protective layer in the multilayer film of the present invention, except that the two-component curing coating agent is applied directly to the surface of the article instead of to the first surface of the substrate layer. [Effects of the Invention]

[0138] The two-component curing coating agent of the present invention provides a surface protection layer with excellent weather resistance, acid resistance, and stain resistance. Therefore, the appearance of the surface of an article to which the surface protection layer is applied can be maintained beautifully for a long period of time.

[0139] Furthermore, the two-component curing coating agent of the present invention can also provide a surface protection layer that is flexible and has excellent elongation properties. Therefore, even when the surface protection layer is subjected to tensile forces, such as when the surface protection layer is attached to the surface of an article or when an article having the surface protection layer is molded, the surface protection layer can withstand the tensile force, and the occurrence of cracks or breakage in the surface protection layer can be reduced. [Modes for carrying out the invention]

[0140] The present invention will be described more specifically below with reference to examples, but the present invention is not limited thereto. [Examples]

[0141] The following raw materials were used in the production of the two-component curing type coating agents in the examples and comparative examples. (Epoxy group-containing compound (e)) • Epoxy group-containing compound (e1) (Hydrogenated bisphenol A diglycidyl ether, which is a reaction product of hydrogenated bisphenol A and epichlorohydrin) • Epoxy group-containing compound (e2) (Neopentyl glycol diglycidyl ether, a reaction product of neopentyl glycol and epichlorohydrin) • Epoxy group-containing compound (e3) (Bisphenol A diglycidyl ether, which is a reaction product of bisphenol A and epichlorohydrin)

[0142] [Synthesis of epoxy polyols (P)] (Synthesis of epoxy polyol (P1)) In a reaction vessel, 34.7 parts by mass of epoxy group-containing compound (e1) (hydrogenated bisphenol A diglycidyl ether) and 45.3 parts by mass of 12-hydroxystearic acid were supplied, and then 20.0 parts by mass of methyl isobutyl ketone were supplied and mixed to obtain a raw material composition adjusted to have a non-volatile content of 80%. The raw material composition was then heated to 110°C, and while stirring the raw material composition, 0.8 parts by mass of triphenylphosphine was supplied to the reaction vessel, and the epoxy group-containing compound (e1) and 12-hydroxystearic acid were reacted until the acid value was 1.0 mgKOH / g or less. This resulted in the addition of the carboxyl group of 12-hydroxystearic acid to each of the two epoxy groups of epoxy group-containing compound (e1) (hydrogenated bisphenol A diglycidyl ether) by a ring-opening addition reaction to obtain epoxy polyol (P1).

[0143] (Synthesis of epoxy polyol (P2)) In a reaction vessel, 26.7 parts by mass of epoxy group-containing compound (e2) (neopentyl glycol diglycidyl ether) and 53.3 parts by mass of 12-hydroxystearic acid were supplied, and then 20.0 parts by mass of methyl isobutyl ketone were supplied and mixed to obtain a raw material composition adjusted to have a non-volatile content of 80%. The raw material composition was then heated to 110°C, and while stirring the raw material composition, 0.8 parts by mass of triphenylphosphine was supplied to the reaction vessel, and the epoxy group-containing compound (e2) and 12-hydroxystearic acid were reacted until the acid value was 1.0 mgKOH / g or less. This resulted in the addition of the carboxyl group of 12-hydroxystearic acid to each of the two epoxy groups of epoxy group-containing compound (e2) (neopentyl glycol diglycidyl ether) by a ring-opening addition reaction to obtain epoxy polyol (P2).

[0144] (Synthesis of epoxy polyol (P3)) In a reaction vessel, 29.5 parts by mass of epoxy group-containing compound (e3) (bisphenol A diglycidyl ether) and 50.5 parts by mass of 12-hydroxystearic acid were supplied, and then 20.0 parts by mass of methyl isobutyl ketone were supplied and mixed to obtain a raw material composition adjusted to have a non-volatile content of 80%. The raw material composition was then heated to 110°C, and while stirring the raw material composition, 0.8 parts by mass of triphenylphosphine was supplied to the reaction vessel, and the epoxy group-containing compound (e3) and 12-hydroxystearic acid were reacted until the acid value was 1.0 mgKOH / g or less. This resulted in the addition of the carboxyl group of 12-hydroxystearic acid to each of the two epoxy groups of epoxy group-containing compound (e3) (bisphenol A diglycidyl ether) by a ring-opening addition reaction to obtain epoxy polyol (P3).

[0145] (Synthesis of epoxy polyol (P4)) In a reaction vessel, 44.2 parts by mass of epoxy group-containing compound (e1) (hydrogenated bisphenol A diglycidyl ether), 7.0 parts by mass of adipic acid, and 28.8 parts by mass of 12-hydroxystearic acid were supplied, and then 20.0 parts by mass of methyl isobutyl ketone was supplied and mixed to obtain a raw material composition adjusted to have a non-volatile content of 80%. The raw material composition was then heated to 110°C, and while stirring the raw material composition, 0.8 parts by mass of triphenylphosphine was supplied to the reaction vessel, and the epoxy group-containing compound (e1), adipic acid, and 12-hydroxystearic acid were reacted until the acid value was 1.0 mg KOH / g or less. This yielded epoxy polyol (P4).

[0146] Epoxy polyol (P4) is obtained by adding epoxy groups of epoxy group-containing compound (e1) (hydrogenated bisphenol A diglycidyl ether) to each of the two carboxyl groups of adipic acid via a ring-opening addition reaction, thereby obtaining an intermediate product having epoxy groups at both ends of the molecule, and then adding carboxyl groups of 12-hydroxystearic acid to each of the epoxy groups at both ends of this intermediate product via a ring-opening addition reaction. i It contained 20% by mass or more of this epoxy polyol (P i ) is the above general formula (II) [in general formula (II), R 1 However, it shows the residue with the two carboxyl groups of adipic acid removed, R 2 However, it shows the residues obtained by removing two epoxy groups from hydrogenated bisphenol A diglycidyl ether, R 3 However, it had the structure shown by [showing the residue with the carboxyl group of 12-hydroxystearic acid removed].

[0147] [Synthesis of Acrylic Polyol (A)] (Synthesis Examples 1-9) 233 parts by mass of methyl isobutyl ketone were charged into a reaction vessel as a solvent, and the temperature was raised to 70°C. Next, monomer compositions containing cyclohexyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, n-butyl acrylate, and 2-ethylhexyl acrylate in the proportions shown in Table 1 were mixed with azobis-2-methylbutyronitrile as a polymerization initiator in the proportions shown in Table 1 by stirring to prepare monomer mixtures. The obtained monomer mixture was added dropwise to the solvent over 3 hours, and polymerization was carried out for a further 3 hours. This yielded an acrylic polyol (A) solution (solid content 30% by mass) containing acrylic polyol (A).

[0148] Table 1 shows the weight-average molecular weight (Mw), hydroxyl value [mgKOH / g], and glass transition temperature (°C) of the acrylic polyols (A) obtained in Synthesis Examples 1 to 9. Table 1 also shows the mass ratio [mass of (meth)acrylic monomer (y) component (y) having a glass transition temperature of -10°C or less] to the (meth)acrylic monomer (x) component (x) having a glass transition temperature exceeding -10°C and an alicyclic structure in the acrylic polyols (A) obtained in Synthesis Examples 1 to 9.

[0149] [Polyisocyanate] • Polyisocyanate (1) (A bifunctional polyurethane diisocyanate obtained by the addition reaction of 1 mol of diol and 2 mol of hexamethylene diisocyanate; number of isocyanate groups in one molecule: 2) • Polyisocyanate (2) (biuret compound of hexamethylene diisocyanate, number of isocyanate groups in one molecule: 3) • Polyisocyanate (3) (Isocyanurate derivative of hexamethylene diisocyanate; number of isocyanate groups in one molecule: 3)

[0150] (Examples 1-18 and Comparative Examples 1-2) Epoxy polyols (P1) to (P4) and acrylic polyol (A) obtained in Synthesis Examples 1 to 9 were supplied to a reaction vessel in the amounts shown in Table 2, and then methyl isobutyl ketone was supplied. These were mixed to obtain the main component (solid content 30% by mass).

[0151] For the acrylic polyols (A) obtained in Synthesis Examples 1 to 9, the acrylic polyol (A) solution containing each acrylic polyol (A) was supplied to the reaction vessel in the amount (solid content) shown in Table 2.

[0152] Next, polyisocyanates (1) to (3) were supplied to another reaction vessel in the proportions shown in Table 2, followed by the supply of methyl isobutyl ketone. These were then mixed to obtain a curing agent (solid content 30% by mass). This yielded a two-component curing type coating agent containing the main component and the curing agent.

[0153] In addition, for two-component curing type coating agents, the equivalent ratio (isocyanate groups / hydroxyl groups) of the isocyanate groups of the polyisocyanate contained in the curing agent to the hydroxyl groups of the polyol contained in the main component is shown in the "Equivalent Ratio (Isocyanate Groups / Hydrogen Groups)" column of Table 2.

[0154] Next, the curing agent was added to the main component and mixed. Immediately thereafter, the two-component curing coating agent was applied to the first surface of the substrate layer (thermoplastic polyurethane elastomer sheet, 150 μm thick) using a bar coater (No. 16). The applied two-component curing coating agent was heated at 120°C for 10 minutes to remove the solvent and heat-cur it, forming a laminated and integrated surface protection layer (10 μm thick) on the first surface of the substrate layer.

[0155] Next, 100 parts by mass of an acrylic adhesive (manufactured by Harima Chemicals, trade name "Hariakron 560CH") and 0.5 parts by mass of an isocyanate crosslinking agent were mixed to obtain an adhesive composition. Immediately thereafter, the adhesive composition was applied to the second surface of the substrate layer using a bar coater (No. 24) to obtain a coating film. This coating film was heated at 100°C for 3 minutes to remove the solvent. After heating, the release paper was laminated onto the coating film by slowly rolling a roller (weighing 10 kg) wrapped with release paper over the coating film. The coating film was then cured at 40°C for 3 days to form an adhesive layer (thickness 25 μm) on the second surface of the substrate layer. This resulted in a multilayer film containing a substrate layer, a surface protection layer laminated and integrated on the first surface of the substrate layer, and an adhesive layer laminated and integrated on the second surface of the substrate layer.

[0156] [evaluation] The surface protective layers of the multilayer films obtained in the examples and comparative examples were evaluated for acid resistance, weather resistance, elongation, and antifouling properties according to the following procedures.

[0157] [Acid resistance] A multilayer film was cut to obtain a flat rectangular test specimen measuring 20 mm in width and 70 mm in length. The release paper was peeled off the test specimen to expose the adhesive layer. The test specimen was attached to the center of a flat rectangular glass plate (25 mm in width and 75 mm in length) using the adhesive layer to obtain a laminate. Next, the entire laminate was immersed in a sulfuric acid aqueous solution containing 60% by mass of sulfuric acid at a temperature of 50°C for 1 hour. After that, the laminate was removed from the sulfuric acid aqueous solution. The HAZE (H1) [%] of the laminate before immersion in the sulfuric acid aqueous solution and the HAZE (H2) [%] of the laminate after immersion in the sulfuric acid aqueous solution were measured using a HAZE meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., product name "HAZE METER NDH 5000") in accordance with JIS K7136 (2000), and the change in HAZE (%) was calculated based on the following formula. The calculated change in HAZE was then evaluated according to the following criteria, and the results are shown in the "Acid Resistance" column of Table 2. Change in haze (%) = H2 - H1

[0158] (Evaluation criteria for changes in haze) A: The change in HAZE was greater than or equal to 0% and less than 2%. B: The change in HAZE was 2% or more and less than 5%. The change in C:HAZE was 5% or more and less than 10%. D: The change in HAZE was 10% or more and less than 20%. E: The change in HAZE was 20% or more.

[0159] [Weather resistance] The appearance of the surface protective layer of the multilayer film before the accelerated weathering test was observed visually in accordance with JIS K5600-1.1, 4.4 "Appearance of coating film". The surface protective layers of the multilayer films obtained in both the examples and comparative examples were colorless and transparent, with no irregularities formed on the surface.

[0160] Next, using an accelerated weathering tester (Iwasaki Electric Co., Ltd., product name "iSuper UV Tester: SUV-W161"), ultraviolet light at an irradiance of 100 mW / cm² was applied to the surface protective layer of the multilayer film under conditions of 63°C and 70% relative humidity. 2 After irradiation for 6 hours, the multilayer film was left for 2 hours in an atmosphere of 50°C and 90% relative humidity without irradiation of ultraviolet light. This process constituted one cycle, and this cycle was repeated for 500 hours in an accelerated weathering test. The appearance of the surface protective layer of the multilayer film after the accelerated weathering test was observed visually in accordance with JIS K5600-1.1 4.4 "Appearance of coating film" and evaluated according to the following criteria. The results are shown in the "Weather Resistance" column of Table 2.

[0161] (Evaluation criteria for the appearance of the surface protective layer after accelerated weathering testing) A: No irregularities were formed on the surface of the protective layer, and no discoloration to white or yellow occurred on the protective layer. B: Although there were slight irregularities on a very small portion of the surface of the protective layer, no discoloration to white or yellow occurred in the protective layer. C: Slight irregularities were formed on the surface of the protective layer, and furthermore, a small portion of the protective layer was discolored to white or yellow. D: The surface of the protective layer had unevenness throughout, and furthermore, the protective layer had discolored to white or yellow overall.

[0162] [Stretchability] After cutting the multilayer film into the shape of "Test Specimen Type 5" as specified in JIS K7127, the release paper was peeled off to obtain a test specimen (width 25 mm, length 115 mm). The elongation of this test specimen was measured using a tensile testing machine (Shimadzu Corporation, product name "Precision Universal Testing Machine Autograph AGS-X") in accordance with JIS K7127 "Plastics - Test Method for Tensile Properties". Specifically, the test specimen was pulled under the conditions of a tensile speed of 100 mm / min, a chuck distance of 80 mm, a gauge length of 50 mm, and a temperature of 23°C. The length L (mm) between the gauges of the test specimen was measured at the point when a crack appeared in the surface protective layer, and the elongation was calculated based on the following formula. The calculated elongation was then evaluated according to the following criteria. The results are shown in the "Elongation" column of Table 2. Growth rate (%) = 100 × (L - 50) / 50

[0163] (Evaluation criteria for growth rate) A: The growth rate was over 85%. B: The growth rate was 80% or more but less than 85%. C: The growth rate was 75% or more but less than 80%. D: The growth rate was less than 75%.

[0164] [Stain-resistant] A line was drawn on the surface of the multilayer protective layer using a commercially available oil-based pen (ZEBRA Corporation, product name "Mackie") and left for 1 minute. Next, 0.1 g of n-hexadecane was dropped onto the line drawn on the surface of the protective layer. Then, the n-hexadecane adhering to the surface of the protective layer was wiped off 10 times with a cellulose nonwoven fabric (Asahi Kasei Corporation, product name "Bencot M-3") under a load of 300 g. After that, the appearance of the protective layer was observed visually in accordance with JIS K5600-1.1 4.4 "Appearance of coating film" and evaluated according to the following criteria. The results are shown in the "Antifouling Properties" column of Table 2.

[0165] (Evaluation criteria for the appearance of the surface protective layer after wiping) A: All the lines drawn on the surface of the protective layer were wiped away, and the lines were no longer visible. B: The lines drawn on the surface of the protective layer appeared extremely faint. C: The lines drawn on the surface of the protective layer were faintly visible. D: The lines drawn on the surface of the protective layer appeared darker.

[0166] [Table 1] TIFF0007912386000004.tif220153

[0167] [Table 2] TIFF0007912386000005.tif237153 [Industrial applicability]

[0168] According to the present invention, a two-component curing type coating agent can be provided that can form a surface protective layer with excellent weather resistance, acid resistance, stain resistance, and elongation properties. The surface protective layer, which consists of a cured film of the two-component curing type coating agent, can protect the surface of an article from dirt and scratches and maintain an excellent appearance.

Claims

1. The main component comprises a polyol containing an epoxy polyol (P), which is a reaction product of an epoxy group-containing compound (e) containing an alicyclic structure and a carboxyl group-containing compound (c), and an acrylic polyol (A), and a curing agent containing a polyisocyanate. The above carboxyl group-containing compound (c) is characterized by containing acetic acid, propionic acid, butyric acid, 2-ethylhexanoic acid, octanoic acid, dodecanoic acid, palmitic acid, stearic acid, oleic acid, pivalic acid, versatic acid, benzoic acid, hydroxycaprylic acid, hydroxylauric acid, hydroxypalmitic acid, hydroxystearic acid, dihydroxystearic acid, glycolic acid, lactic acid, hydroxypivalic acid, dimethylolpropionic acid, dimethylolbutanoic acid, gluconic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanediic acid, tetrahydrophthalic acid, phthalic acid, butanetricarboxylic acid, butanetetracarboxylic acid, malic acid, citric acid, or tartaric acid.

2. The main component comprises a polyol containing an epoxy polyol (P), which is a reaction product of an epoxy group-containing compound (e) and a carboxyl group-containing compound (c), and an acrylic polyol (A), and a curing agent containing a polyisocyanate. The above carboxyl group-containing compound (c) is characterized by containing hydroxycaprylic acid, hydroxylauric acid, hydroxypalmitic acid, hydroxystearic acid, dihydroxystearic acid, glycolic acid, lactic acid, hydroxypivalic acid, dimethylolpropionic acid, dimethylolbutanoic acid, or gluconic acid, making it a two-component curable coating agent.

3. The main component comprises a polyol containing an epoxy polyol (P), which is a reaction product of an epoxy group-containing compound (e) and a carboxyl group-containing compound (c), and an acrylic polyol (A), and a curing agent containing a polyisocyanate. The epoxy polyol (P) described above contains 20% by mass or more and 100% by mass or less of an epoxy polyol having the structure shown in the following general formula (II). A two-component curable coating agent characterized in that the content of the epoxy polyol (P) in the polyol of the main component is 30 parts by mass or more and 99 parts by mass or less, based on 100 parts by mass of the total amount of the epoxy polyol (P) and the acrylic polyol (A). 【Chemistry 1】 However, in the above general formula (II), R 1 This indicates the residue obtained by removing the two carboxyl groups from a carboxyl group-containing compound (c2) that has two carboxyl groups in one molecule. R 2 This represents the residue obtained by removing the two epoxy groups from epoxy group-containing compound (e), which has two epoxy groups in one molecule. R 3 This indicates the residue obtained by removing the carboxyl group from a carboxyl group-containing compound (c1) having one carboxyl group and one or more hydroxyl groups in one molecule.

4. A two-component curable coating agent according to any one of claims 1 to 3, characterized in that the content of epoxy polyol (P) in the polyol is 40 parts by mass or more and 92 parts by mass or less, based on 100 parts by mass of the total amount of epoxy polyol (P) and acrylic polyol (A).

5. The acrylic polyol (A) comprises a (meth)acrylic monomer (x) component having a glass transition temperature exceeding -10°C and an alicyclic structure, and a (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or lower, and A two-component curable coating agent according to any one of claims 1 to 4, characterized in that, in the above acrylic polyol (A), the mass ratio of the (meth)acrylic monomer (y) component having a glass transition temperature of -10°C or less to the (meth)acrylic monomer (x) component having a glass transition temperature exceeding -10°C and an alicyclic structure is 1.1 or more and 3.6 or less.

6. The acrylic polyol (A) is characterized in that it has a glass transition temperature of -50°C or higher and -2°C or lower, and a weight-average molecular weight of 10,000 or higher and 100,000 or lower, as described in any one of claims 1 to 5.

7. A two-component curing coating agent according to any one of claims 1 to 6, characterized in that the polyisocyanate has three or more isocyanate groups in one molecule.

8. A two-component curable coating agent according to any one of claims 1 to 7, characterized in that the polyisocyanate includes an isocyanurate of the polyisocyanate.

9. It includes a base layer, a surface protection layer which is a cured film of a two-component curing type coating agent and is laminated and integrated on the first surface of the base layer, and an adhesive layer which is laminated and integrated on the second surface of the base layer. The above two-component curing coating agent comprises a main component containing a polyol including an epoxy polyol (P) which is a reaction product of an epoxy group-containing compound (e) and a carboxyl group-containing compound (c), and an acrylic polyol (A), and a curing agent containing a polyisocyanate. The above carboxyl group-containing compound (c) is characterized by containing acetic acid, propionic acid, butyric acid, 2-ethylhexanoic acid, octanoic acid, dodecanoic acid, palmitic acid, stearic acid, oleic acid, pivalic acid, versatic acid, benzoic acid, hydroxycaprylic acid, hydroxylauric acid, hydroxypalmitic acid, hydroxystearic acid, dihydroxystearic acid, glycolic acid, lactic acid, hydroxypivalic acid, dimethylolpropionic acid, dimethylolbutanoic acid, gluconic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanediic acid, tetrahydrophthalic acid, phthalic acid, butanetricarboxylic acid, butanetetracarboxylic acid, malic acid, citric acid, or tartaric acid.

10. It includes a base layer, a surface protection layer which is a cured film of a two-component curing type coating agent and is laminated and integrated on the first surface of the base layer, and an adhesive layer which is laminated and integrated on the second surface of the base layer. The above two-component curing coating agent comprises a main component containing a polyol including an epoxy polyol (P) which is a reaction product of an epoxy group-containing compound (e) and a carboxyl group-containing compound (c), and an acrylic polyol (A), and a curing agent containing a polyisocyanate. The epoxy polyol (P) described above contains 20% by mass or more and 100% by mass or less of an epoxy polyol having the structure shown in the following general formula (II). A multilayer film characterized in that the content of the epoxy polyol (P) in the polyol of the main component is 30 parts by mass or more and 99 parts by mass or less, based on 100 parts by mass of the total amount of epoxy polyol (P) and acrylic polyol (A). 【Chemistry 2】 However, in the above general formula (II), R 1 This indicates the residue obtained by removing the two carboxyl groups from a carboxyl group-containing compound (c2) that has two carboxyl groups in one molecule. R 2 This represents the residue obtained by removing the two epoxy groups from epoxy group-containing compound (e), which has two epoxy groups in one molecule. R 3 This indicates the residue obtained by removing the carboxyl group from a carboxyl group-containing compound (c1) having one carboxyl group and one or more hydroxyl groups in one molecule.

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