Paint composition and hydrophilic coating for forming a hydrophilic coating film

Abstract

The present invention provides a paint composition for forming a coating film that possesses both high hydrophilicity and high flexibility, and a hydrophilic coating film formed using the same. [Solution] A coating composition for forming a hydrophilic coating or film is disclosed, comprising (A) an active energy ray curable resin having an anionic hydrophilic group, and (B) a (meth)acryloyl group-containing polyester polyol. The polycarboxylic acid constituting component (B) may include at least one alicyclic dicarboxylic acid selected from the group consisting of 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, and norbornanedicarboxylic acid. The anionic hydrophilic group of component (A) may be selected from the group consisting of a sulfonic acid group, a carboxyl group, and a phosphate group.

Description

[Technical Field]

[0001] The present invention relates to a paint composition for forming a hydrophilic coating film and a hydrophilic coating film. In particular, the present invention relates to a paint composition containing specific components for forming a coating film that is both hydrophilic and flexible, and to a hydrophilic coating film formed using the same. [Background technology]

[0002] Hydrophilic coatings are widely used as coatings that provide various properties such as hydrophilicity, anti-fogging, anti-fouling, and antistatic properties. Ideally, hydrophilic coatings should possess not only high hydrophilicity but also high flexibility.

[0003] As an attempt to obtain a paint composition for forming a flexible hydrophilic coating film, it is known that a component containing a highly hydrophilic polyethylene glycol structure has been added. As such a hydrophilic coating film, for example, Patent Document 1 reports a hydrophilic resin containing a first aqueous polyurethane resin obtained by reacting at least a polyisocyanate, a macropolyol containing a polyoxyethylene polyol, a polyoxyethylene side chain-containing active compound, and a chain extender containing a polyamine, and a second aqueous polyurethane resin obtained by reacting at least a polyisocyanate, a macropolyol containing a hydrophobic macropolyol, and a chain extender. Furthermore, Patent Document 2 reports an anti-fogging laminate in which a water-absorbing layer (B) made of a crosslinked resin containing a polyethylene glycol structure and having high water absorption is laminated below a hydrophilic layer (A) made of a crosslinked resin with high scratch resistance, which has anionic, cationic, or nonionic hydrophilic groups segregated on the surface, and between the hydrophilic cured product and the substrate. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5149241 [Patent Document 2] Patent No. 6731486 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the inventors have confirmed that while using a highly hydrophilic polyethylene glycol structure to impart flexibility to a hydrophilic coating film significantly improves flexibility, it also impairs the hydrophilicity of the coating film's surface. In other words, it was found that while the use of a polyethylene glycol structure in a hydrophilic coating film can provide high flexibility, it may come at the expense of maintaining high hydrophilicity on the coating film's surface.

[0006] Therefore, the first problem to be solved by the present invention is to provide a coating composition for forming a coating film that has both high hydrophilicity and high flexibility, and a hydrophilic coating film formed using the same. Furthermore, an additional problem to be solved by the present invention is to provide a coating composition for forming a coating film that possesses both high hydrophilicity and high flexibility, and furthermore, excellent scratch resistance and / or adhesion to the substrate, as well as a hydrophilic coating film formed using the same. [Means for solving the problem]

[0007] Based on the above findings, the inventors conducted further intensive research and discovered that, in order to impart flexibility to a hydrophilic coating film, by using a component with a highly lipophilic (i.e., highly hydrophobic) structure, specifically a component with the following specific structure that substantially does not contain a polyethylene glycol structure, in combination with a hydrophilic active energy ray curable resin, a coating film that maintains hydrophilicity on the surface while also possessing flexibility can be obtained, thus completing the present invention.

[0008] The following are some aspects or embodiments that may be included in the present invention. [1]. A coating composition for forming a hydrophilic coating or film, (A) Active energy ray curable resin having an anionic hydrophilic group, and (B) (meth)acryloyl group-containing polyester polyol A paint composition containing the following: [2]. The paint composition according to item [1] above, wherein the polycarboxylic acid constituting the (B)(meth)acryloyl group-containing polyester polyol comprises at least one selected from the group consisting of linear aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and ester-forming derivatives thereof. [3]. The paint composition according to item [2], wherein the polycarboxylic acid constituting the (B)(meth)acryloyl group-containing polyester polyol comprises at least one alicyclic dicarboxylic acid selected from the group consisting of 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, and norbornanedicarboxylic acid. [4]. The coating composition according to any one of the above items [1] to [3], wherein the anionic hydrophilic group of the active energy ray curable resin having an anionic hydrophilic group (A) comprises at least one selected from the group consisting of a sulfonic acid group, a carboxyl group, and a phosphate group. [5]. The paint composition according to any one of the above items [1] to [4], wherein the active energy ray curable resin having an anionic hydrophilic group (A) comprises a polymer formed from a monomer containing a hydroxy(meth)acrylate having a sulfonic acid group. [6]. The coating composition according to any one of the above items [1] to [5], wherein the (B) (meth)acryloyl group-containing polyester polyol comprises a polyester polyol having two or more (meth)acryloyl groups in its molecule. [7]. (C) A paint composition according to any one of the above items [1] to [6], further comprising a photopolymerization initiator. [8]. A hydrophilic coating film formed from any one of the paint compositions described in item [1] to [7] above. [9]. A hydrophilic film formed from a paint composition described in any one of the above items [1] to [7].

[0009] In this specification, the term "resin" is used to include resin mixtures containing two or more resins, as well as resin compositions containing components other than resins. In this specification, the term "greater than or equal to" in relation to a numerical range means a certain number or greater than a certain number. For example, "20% or more" means 20% or greater than 20%. The term "less than or equal to" in relation to a numerical range means a certain number or less than a certain number. For example, "20% or less" means 20% or less than 20%. The symbol "~" in relation to a numerical range means a certain number, greater than a certain number and less than another certain number, or another certain number. Here, the other certain number is a number greater than a certain number. For example, "10~90%" means 10%, greater than 10% and less than 90%, or 90%. Furthermore, the upper and lower limits of a numerical range can be combined arbitrarily, and embodiments with such arbitrary combinations should be discernible. For example, from descriptions relating to the numerical range of a certain characteristic, such as "usually 10% or more, preferably 20% or more. On the other hand, usually 40% or less, preferably 30% or less," or "usually 10-40%, preferably 20-30%," it can be inferred that, in one embodiment, the numerical range of that characteristic is 10-40%, 20-30%, 10-30%, or 20-40%. Except in the examples, or unless otherwise specified, all numerical values ​​used herein and in the claims should be understood to be modified by the term “approximately.” Without attempting to limit the application of the doctrine of equivalents to the claims, each numerical value should be interpreted in terms of significant figures and by applying common rounding methods. In this specification, when describing "including a certain substance", in one embodiment, it is construed as including a certain substance, consisting of a certain substance, or consisting only of a certain substance. For example, from the description "Composition A includes substance a1 and substance a2", in one embodiment, it is construed that Composition A includes substance a1 and substance a2, Composition A consists of substance a1 and substance a2, or Composition A consists only of substance a1 and substance a2.

Advantages of the Invention

[0010] According to the present invention, by including a (meth)acryloyl group-containing polyester polyol, which is a component having a high lipophilicity (i.e., high hydrophobicity), together with a hydrophilic active energy ray-curable resin, it is possible to provide a coating composition for forming a coating film having both high hydrophilicity and high flexibility, and a hydrophilic coating film formed using the same. This coating film has high flexibility in addition to high hydrophilicity. Here, for example, the measure of high hydrophilicity may be an evaluation by a water contact angle or a magic floating test described later, and the measure of high flexibility may be the prevention of curling due to shrinkage during curing. Further, according to a preferred embodiment of the present invention, it is possible to provide a coating composition for forming a coating film having both high hydrophilicity and high flexibility, and further having at least one of excellent abrasion resistance and / or substrate adhesion, and a hydrophilic coating film formed using the same. In addition, in this specification, the description of the structure and effects of the hydrophilic coating film also applies to the hydrophilic film in the same manner.

[0011] As described later regarding the curing shrinkage curl test in the examples, when a large shrinkage occurs when the film cures to form a coating film, the flexibility of the coating film is impaired and a large curl occurs. On the other hand, when the shrinkage that occurs when the film cures to form a coating film is small, it is considered that the curl that occurs becomes small and the flexibility of the coating film is maintained. Therefore, in the present application, the high flexibility referred to for the hydrophilic film is substantially synonymous with that the curl due to shrinkage during curing is small, or the curl prevention property due to shrinkage during curing is high. Thus, when the hydrophilic film has high flexibility, that is, when the curl prevention property due to shrinkage during curing is high, it is considered that such a hydrophilic film can also be suitably applied to the surface of a flexible substrate or a three-dimensional shaped substrate.

Brief Description of Drawings

[0012] [Figure 1] FIG. 1 is a view showing a perspective view from above a test set as a schematic of the curing shrinkage curl test in the examples.

Modes for Carrying Out the Invention

[0013] The coating composition for forming a hydrophilic coating film or film according to the present invention contains (A) an active energy ray-curable resin having an anionic hydrophilic group and (B) a (meth)acryloyl group-containing polyester polyol, and may further contain other optional components as required. Hereinafter, each component will be described in detail.

[0014] Component (A): Active energy ray curable resin having anionic hydrophilic groups The coating composition according to the present invention contains, as component (A), an active energy ray-curable resin having an anionic hydrophilic group in order to impart hydrophilicity to the coating film or film formed therefrom. The anionic hydrophilic group possessed by this active energy ray-curable resin is not particularly limited as long as it is a hydrophilic group having anionicity, but preferably contains at least one selected from the group consisting of a sulfonic acid group, a carboxyl group, and a phosphate group. Non-limiting examples of anionic hydrophilic groups other than sulfonic acid groups, carboxyl groups, and phosphate groups that an active energy ray curable resin may have include phenolic hydroxyl groups, halogen groups, and sulfate groups. In one embodiment, the anionic hydrophilic group of the active energy ray curable resin may consist of only at least one selected from the group consisting of sulfonic acid groups, carboxyl groups, and phosphate groups. In another embodiment, the anionic hydrophilic group of the active energy ray curable resin may include at least one selected from the group consisting of phenolic hydroxyl groups, halogen groups, and sulfate groups, in addition to at least one selected from the group consisting of sulfonic acid groups, carboxyl groups, and phosphate groups.

[0015] The active energy ray curable resin having an anionic hydrophilic group of component (A) is not particularly limited as long as it is a substance that polymerizes and hardens with active energy rays such as ultraviolet rays or electron beams to form a coating film. Examples of active energy ray curable resins that constitute the skeletal structure of an active energy ray curable resin having anionic hydrophilic groups include (meth)acryloyl group-containing prepolymers or oligomers such as urethane (meth)acrylate (or polyurethane (meth)acrylate), polyester (meth)acrylate, polyacrylic (meth)acrylate, epoxy (meth)acrylate, polyalkylene glycol poly(meth)acrylate, and polyether (meth)acrylate.

[0016] In other embodiments, examples of active energy ray curable resins that constitute the skeletal structure of an active energy ray curable resin having an anionic hydrophilic group include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and phenyl (meth)acrylate. (meth)acryloyl group-containing monofunctional reactive monomers such as phenyl cellosolve (meth)acrylate, 2-methoxyethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, 2-acryloyloxyethyl hydrogen phthalate, dimethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, and trimethylsiloxyethyl methacrylate; monofunctional reactive monomers such as N-vinylpyrrolidone and styrene; (meth)acryloyl group-containing bifunctional reactive monomers such as diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2,2'-bis(4-(meth)acryloyloxypolyethyleneoxyphenyl)propane, and 2,2'-bis(4-(meth)acryloyloxypolypropyleneoxyphenyl)propane; trimethylolpropane tri(meth)acrylate, and Examples include trifunctional reactive monomers containing (meth)acryloyl groups, such as trimethylolethane tri(meth)acrylate; tetrafunctional reactive monomers containing (meth)acryloyl groups, such as pentaerythritol tetra(meth)acrylate; hexafunctional reactive monomers containing (meth)acryloyl groups, such as dipentaerythritol hexaacrylate; octafunctional reactive monomers containing (meth)acryloyl groups, such as tripentaerythritol octaacrylate; and prepolymers or oligomers comprising one or more of these monomers. In this specification, (meth)acrylate means acrylate or methacrylate. Also, (meth)acryloyl group means acryloyl group or methacryloyl group.

[0017] In yet another embodiment, the active energy ray curable resin constituting the skeletal structure of the active energy ray curable resin having an anionic hydrophilic group is, for example, a compound having two thiol groups in one molecule, such as 1,2-ethanedithiol, ethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptopropionate), 1,4-bis(3-mercaptobutyryloxy)butane, and tetraethylene glycol bis(3-mercaptopropionate); and 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H) Examples include compounds having three thiol groups in one molecule, such as trione, trimethylolpropanetris(3-mercaptobutyrate), trimethylolethanetris(3-mercaptobutyrate), and tris[(3-mercaptopropionyloxy)ethyl]isocyanurate; compounds having four thiol groups in one molecule, such as pentaerythritoltetrakis(3-mercaptopropionate) and pentaerythritoltetrakis(3-mercaptobutyrate); and compounds having six thiol groups in one molecule, such as dipentaerythritolhexakis(3-mercaptopropionate).

[0018] As the active energy ray curable resin for the skeletal structure constituting the active energy ray curable resin having anionic hydrophilic groups, one or more of these, a mixture of two or more, or a copolymer formed from two or more specific types among them can be used.

[0019] The active energy ray curable resin having anionic hydrophilic groups may more preferably include a polymer formed from monomers containing hydroxy(meth)acrylate having sulfonic acid groups. By using a coating composition containing a polymer formed from monomers containing hydroxy(meth)acrylate having sulfonic acid groups, a better balance of hydrophilicity and flexibility can be achieved in the coating film formed from this coating composition. The hydroxy(meth)acrylate constituting the hydroxy(meth)acrylate having sulfonic acid groups may be, for example, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate, or a mixture of two or more of these.

[0020] Active energy ray curable resins having anionic hydrophilic groups may be formed by including, in addition to the monomer group exemplified above, a monomer containing one or more polyfunctional monomers as a comonomer, such as vinyl esters including vinyl acetate, vinyl propionate, vinyl laurate, maleic acid esters including dibutyl maleate, diethyl maleate, fumarate, dibutyl fumarate, diethyl fumarate, vinyl ethers including vinyl methyl ether, vinyl butyl ether, vinyl octyl ether, vinyl cyanides including acrylonitrile, methacrylonitrile, α-olefins including ethylene, propylene, styrene, vinyl halides or vinyl halides including vinyl chloride, vinylidene chloride, vinyl bromide, non-conjugated dienes including dicyclopentadiene (DCPD), methyltetrahydroindene (MTHI), methylene norbornene (MNB), ethylidene norbornene (ENB), diacrylphthalate, ethylene glycol dimethacrylate, etc. The mass ratio of these comonomers to the total monomer is not particularly limited, but may be, for example, 20% by mass or less or 10% by mass or less.

[0021] As the active energy ray curable resin having anionic hydrophilic groups, the resins exemplified above may be used individually or as a mixture of two or more. The molecular weight of the active energy ray curable resin having anionic hydrophilic groups is not particularly limited, but for example, the number average molecular weight may be 1,000 to 300,000, 3,000 to 200,000, or 5,000 to 100,000. In this specification, the number average molecular weight refers to the polystyrene-converted number average molecular weight (Mn) obtained from the differential molecular weight distribution curve (GPC curve) measured by gel permeation chromatography (GPC) using tetrahydrofuran as the mobile phase.

[0022] In a non-limiting preferred embodiment, the active energy ray curable resin having an anionic hydrophilic group of component (A) may include at least one copolymer that is a hydrophilic compound as disclosed in International Publication 2007 / 064003. Specifically, International Publication No. 2007 / 064003 discloses a copolymer represented by the following formula as a hydrophilic resin that can be used as an active energy ray curable resin having an anionic hydrophilic group of component (A). [X] a [M 1 ] b [M 2 ] c (In the formula, a represents 1 or 2, b represents 1 or 2, and m represents 0 or 1. 1 M 2 X represents a hydrogen ion, ammonium ion, alkaline metal ion, or alkaline earth metal ion, which may be the same or different. X represents one of the hydrophilic groups selected from the general formulas (1-1) to (1-4) below. [ka] [ka] [ka] [ka] (In the formula, J and J' represent H or CH3, which may be the same or different; n represents 0 or 1; and R is an aliphatic hydrocarbon group having 1 to 600 carbon atoms, which may be the same or different, and may include an aromatic ring, an aliphatic cyclic group, an ether group, or an ester group.)

[0023] The amount of component (A) an active energy ray curable resin having an anionic hydrophilic group in the paint composition is not particularly limited, but is usually 30% by mass or more and 95% by mass or less based on the total amount of solids in the paint composition, preferably 40% by mass or more and 90% by mass or less, or 50% by mass or more and 85% by mass or less.

[0024] Component (B): (meth)acryloyl group-containing polyester polyol The coating composition according to the above embodiment of the present invention contains a (meth)acryloyl group-containing polyester polyol as component (B) in order to maintain the hydrophilicity of the surface of the coating film or film formed therefrom, and to provide high flexibility.

[0025] The polycarboxylic acid constituting the (meth)acryloyl group-containing polyester polyol may include at least one selected from the group consisting of linear aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and ester-forming derivatives thereof. Polycarboxylic acid anhydrides may also be used as the polycarboxylic acid. Such polycarboxylic acids are not particularly limited, but include, for example, phthalic acid, phthalic anhydride, chlorendic acid, chlorendic anhydride, succinic acid, adipic acid, oxalic acid, glutaric acid, pimelic acid, malonic acid, butanediic acid, glutaric acid, suberic acid, azelaic acid, sebacic acid, 1,12-dodecanediic acid, hexahydrophthalic acid, isophthalic acid, terephthalic acid, ortho-phthalic acid, tetrachlorophthalic acid, 1,5-naphthalenedicarboxylic acid, and fuma. Examples include lic acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, tetrahydrophthalic acid, citric acid, tartaric acid, dimer acid, trimellitic acid, trimesic acid, pyromellitic acid, succinic anhydride, adipic anhydride, trimellitic anhydride, pyromellitic dianhydride, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedimethylcarboxylic acid.

[0026] In a preferred embodiment, the polycarboxylic acid constituting the (B)(meth)acryloyl group-containing polyester polyol may include at least one alicyclic dicarboxylic acid selected from the group consisting of 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, and norbornanedicarboxylic acid. More preferably, the polycarboxylic acid constituting the (B)(meth)acryloyl group-containing polyester polyol may include at least one alicyclic dicarboxylic acid selected from the group consisting of 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. By using a (meth)acryloyl group-containing polyester polyol composed of such alicyclic dicarboxylic acids, the coating film formed from the coating composition may maintain high surface hydrophilicity while simultaneously possessing excellent flexibility.

[0027] The polyhydric alcohols constituting the (meth)acryloyl group-containing polyester polyols are not particularly limited, but include propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, dipropylene glycol, dibutylene glycol, 2-methyl-1,3-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, bisphenol A, or propylene oxide adducts of hydrogenated bisphenol A. Polyols such as glycerin, trimethylolethane, trimethylolpropane, di-trimethylolethane, di-trimethylolpropane, and pentaerythritol may also be used. These polyhydric alcohols may be used individually or as a mixture of two or more.

[0028] In one preferred embodiment, the (meth)acryloyl group-containing polyester polyol is substantially free of polyethylene glycol structures. The proportion of ethylene glycol structural units in the total monomers constituting the (meth)acryloyl group-containing polyester polyol may be, for example, 5 mol% or less, preferably 3 mol% or less, more preferably 1 mol% or less, even more preferably 0.1 mol% or less, and most preferably about 0 (zero) mol%. While we do not wish to be bound by theory, it is considered that, because component (B), a (meth)acryloyl group-containing polyester polyol, substantially does not contain polyethylene glycol structures, that is, mainly contains structures derived from polyhydric alcohols with relatively high lipophilicity and hydrophobicity, the coating film of a paint composition containing such components exhibits high hydrophilicity because, when the solvent it is blended with evaporates, the hydrophilic groups of the hydrophilic resin of component (A) are pulled to the surface and move, and hydrophilic groups are positioned on the coating film surface. Polyethylene glycol structures, while providing high flexibility, are extremely hydrophilic structures, and therefore, it is presumed that they may hinder the selective localization of hydrophilic groups on the coating film surface when forming a coating film from a paint composition containing them.

[0029] The (meth)acryloyl group-containing polyester polyol of component (B) may preferably contain a polyester polyol having two or more (meth)acryloyl groups in the molecule, more preferably a polyester polyol having three or more (meth)acryloyl groups in the molecule, and even more preferably a polyester polyol having four or more (meth)acryloyl groups in the molecule. By having two or more, three or more, or four or more (meth)acryloyl groups in the molecule of the polyester polyol in this way, it becomes possible to achieve an even higher balance between hydrophilicity and flexibility in the formed coating film.

[0030] In one embodiment, the acid value of the (meth)acryloyl group-containing polyester polyol of component (B) may preferably be 10 mg KOH / g or more, more preferably 10.5 mg KOH / g or more, even more preferably 11 mg KOH / g or more, or 11.5 mg KOH / g or more. In another embodiment, the acid value of the (meth)acryloyl group-containing polyester polyol of component (B) may preferably be 12 mg KOH / g or more, 14 mg KOH / g or more, 16 mg KOH / g or more, or 18 mg KOH / g or more. It is considered that by having a polyester polyol with an acid value of 10 mg KOH / g or more, or a more preferable range, it becomes possible to achieve an even higher balance of hydrophilicity and flexibility in the resulting coating film. In this specification, the acid value is the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of the sample, and is a value measured according to JIS K0070-1992, 3.1 Neutralization Titration Method.

[0031] In one embodiment, the (meth)acryloyl group-containing polyester polyol of component (B) preferably contains a polyester polyol having 2 or more, 3 or more, or 4 or more (meth)acryloyl groups in the molecule and may have an acid value of 10 mg KOH / g or more, more preferably contains a polyester polyol having 2 or more, 3 or more, or 4 or more (meth)acryloyl groups in the molecule and may have an acid value of 10.5 mg KOH / g or more, or contains a polyester polyol having 2 or more, 3 or more, or 4 or more (meth)acryloyl groups in the molecule and may have an acid value of 11 mg KOH / g or more, or contains a polyester polyol having 2 or more, 3 or more, or 4 or more (meth)acryloyl groups in the molecule and may have an acid value of 11.5 mg KOH / g or more. In other embodiments, the (meth)acryloyl group-containing polyester polyol of component (B) may preferably contain a polyester polyol having 2 or more, 3 or more or 4 or more (meth)acryloyl groups in the molecule and have an acid value of 12 mg KOH / g or more, or contain a polyester polyol having 2 or more, 3 or more or 4 or more (meth)acryloyl groups in the molecule and have an acid value of 14 mg KOH / g or more, or contain a polyester polyol having 2 or more, 3 or more or 4 or more (meth)acryloyl groups in the molecule and have an acid value of 16 mg KOH / g or more, or contain a polyester polyol having 2 or more, 3 or more or 4 or more (meth)acryloyl groups in the molecule and have an acid value of 18 mg KOH / g or more.

[0032] As the (meth)acryloyl group-containing polyester polyol, one of the examples above may be used alone, or a mixture of two or more of them may be used. The molecular weight of the (meth)acryloyl group-containing polyester polyol is not particularly limited, but for example, the number average molecular weight may be 2,000 to 500,000, 4,000 to 300,000, or 6,000 to 100,000.

[0033] The amount of component (B) (meth)acryloyl group-containing polyester polyol in the paint composition is not particularly limited, but is usually 5% by mass or more and 70% by mass or less based on the total solid content of the paint composition, preferably 10% by mass or more and 60% by mass or less, 15% by mass or more and 50% by mass or less, or 20% by mass or more and 40% by mass or less. The blending mass ratio (mass ratio by solids) of component (B) (meth)acryloyl group-containing polyester polyol to component (A) an anionic hydrophilic resin having an active energy ray curable resin in the paint composition is not particularly limited, but is usually 30:70 to 90:10, preferably 40:60 to 80:20 or 50:50 to 70:30.

[0034] <Calculation of the number of (meth)acryloyl groups contained within the molecule of component (B)> The number of (meth)acryloyl groups per molecule of the (meth)acryloyl group-containing polyester polyol of component (B) was determined by nuclear magnetic resonance spectroscopy. 13 The (meth)acryloyl group (molality) is calculated from the quantitative value obtained by an external standard method using 1C-NMR and the number-average molecular weight (Mn) measured by gel permeation chromatography (GPC). A further detailed explanation follows. In the following explanation, the specific products (trade names) of the substances and devices used in the measurements are understood to be replaceable with other products, as long as they provide similar functions and characteristics.

[0035] <Measurement of the number-average molecular weight (Mn) of component (B)> The number-average molecular weight of the (meth)acryloyl group-containing polyester polyol of component (B) is calculated as the polystyrene-equivalent molecular weight from the differential molecular weight distribution curve (hereinafter sometimes abbreviated as "GPC curve") measured by gel permeation chromatography (hereinafter sometimes abbreviated as "GPC"). GPC measurements are performed using the Tosoh Corporation's HLC-8320 high-performance liquid chromatography system, which includes a degasser, liquid delivery pump, autosampler, column oven, and RI (differential refractive index) detector; four GPC columns from Shodex, consisting of two KF-806L, one KF-802, and one KF-801, connected in the order of KF-806L, KF-806L, KF-802, and KF-801 from upstream; and tetrahydrofuran for high-performance liquid chromatography (without stabilizers) from Wako Pure Chemical Industries, Ltd. as the mobile phase; under the following conditions: flow rate of 1.0 ml / min, column temperature of 40°C, sample concentration of 1 ml / ml, and sample injection volume of 100 microliters. The elution amount at each retention capacity can be determined from the detection amount of the RI detector, assuming that the refractive index of the sample does not depend on the molecular weight. Furthermore, calibration curves from each retention capacity to polystyrene-equivalent molecular weight can be prepared using standard polystyrene. In this case, it should be noted that the standard polystyrene used should be appropriately selected so that the retention capacity of the sample is interpolated into the calibration curve plot. The analysis program that can be used is "TOSOH HLC-8320GPC EcoSEC" (product name) manufactured by Tosoh Corporation. For the theory and practical application of GPC, you can refer to reference books such as "Size Exclusion Chromatography: High-Performance Liquid Chromatography of Polymers" by Kyoritsu Shuppan Co., Ltd., author: Sadao Mori, 1st edition, 1st printing, December 10, 1991. Furthermore, the number-average molecular weight of the active energy ray-curable resin having anionic hydrophilic groups in component (A) of the paint composition can also be measured using the same method as described here.

[0036] <Quantification of (meth)acryloyl groups per molecule by NMR> Using a single - molecule substance with a known number of (meth)acryloyl groups in one molecule as a standard sample, the quantification of (meth)acryloyl groups is carried out by an external standard method using nuclear magnetic resonance spectroscopy ( 13 13C - NMR). As such a standard sample in this external standard method, typically pentaerythritol triacrylate or pentaerythritol tetraacrylate may be used. The external standard method is a method that determines the correlation between concentration (molality) and peak intensity in advance using a standard sample with a known concentration, and determines the concentration in the test sample based on the information (calibration curve) obtained there. The 13 measurement conditions by ¹³C - NMR are as follows. · Measuring device: AVANCE III Cryo - 500 type nuclear magnetic resonance device manufactured by Bruker BioSpin · Measured nucleus: 13 ¹³C (125 MHz) · Pulse conditions: 45° (5.00 μs) · Number of integrations: 64 times · Measurement solvent: chloroform - d

[0037] From the quantification value (molality) of (meth)acryloyl groups per molecule obtained by NMR measurement by the above method and the measured value of the number - average molecular weight (Mn) by GPC, the number of (meth)acryloyl groups per molecule of the (meth)acryloyl - group - containing polyester polyol as component (B) in the present invention is determined by the following formula. Number of (meth)acryloyl groups per molecule (N)=Quantification of (meth)acryloyl groups by NMR (mol / kg)×Number - average molecular weight (Mn) / 1000

[0038] (C) Photopolymerization initiator The coating composition according to the above - described embodiment of the present invention may optionally contain (C) a photoinitiator in order to promote the formation of a coating film by curing with active energy rays of the active energy ray - curable resin having an anionic hydrophilic group as component (A) (particularly when it is a resin having an unsaturated double - bond group).

[0039] Such photopolymerization initiators are not particularly limited, but examples include acetophenone, 2,2-dimethoxyacetophenone, p-dimethylaminoacetophenone, Michler ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-propyl ether, benzoin isobutyl ether, benzoin n-butyl ether, benzyldimethyl ketal, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1 Examples include -one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 1-[4-(phenylthio)phenyl]-1,2-octanedione=2-(O-benzoyl oxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyl oxime), 2,4-diethylthioxanthone, etc. These photopolymerization initiators may be used individually or in combination of two or more.

[0040] The amount of the photopolymerization initiator used in a paint composition containing component (C) is not particularly limited, but is usually 0.01% to 10% by mass, preferably 0.1% to 8% by mass, more preferably 0.2% to 6% by mass, and even more preferably 0.4% to 5% by mass, relative to the total solid content of the paint composition.

[0041] Other optional components The coating composition may further contain, as desired, any components other than those described above, to the extent that they do not contradict the purpose of the present invention. Examples of such optional components that may be added as needed include, in addition to the photopolymerization initiators described above, flame retardants, antistatic agents, surfactants, leveling agents, thixotropic agents, antifouling agents, printability improvers, antioxidants, weather stabilizers, light stabilizers, ultraviolet absorbers, heat stabilizers, pigments, and fillers.

[0042] In one preferred embodiment, the paint composition may include a leveling agent from the viewpoint of making the surface of the coating film smooth. Examples of leveling agents include acrylic leveling agents, silicone leveling agents, fluorine leveling agents, silicone-acrylic copolymer leveling agents, fluorine-modified acrylic leveling agents, fluorine-modified silicone leveling agents, and leveling agents to which functional groups (e.g., alkoxy groups such as methoxy groups and ethoxy groups, acyloxy groups, halogen groups, amino groups, vinyl groups, epoxy groups, methacryloxy groups, acryloxy groups, and isocyanate groups, etc.) have been introduced. Among these, silicone-acrylic copolymer leveling agents are preferred. One or more of these can be used as leveling agents.

[0043] The amount of the optional components other than the photopolymerization initiator (if used) in the paint composition is not particularly limited, but it is usually about 0.01 to 10% by mass relative to the total solid content of the paint composition.

[0044] In addition to the components that make up the solid content described above, paint compositions may usually contain solvents. The solvents that can be used are not particularly limited, but examples include ketones such as acetone, ethyl methyl ketone, cyclohexanone, and cyclopentanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as ethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol diethyl ether; esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, carbitol acetate, propylene glycol monomethyl ether acetate, and γ-butyrolactone; alcohols such as methanol, ethanol, cellosolve, and methyl cellosolve; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. These solvents may be used individually or in mixtures of two or more. The amount of solvent included in the paint composition is not particularly limited, but from the viewpoint of coatability to the surface of the object to be painted, it may be, for example, 5% by mass or more and 95% by mass or less of the total amount of the paint composition, and preferably 10% by mass or more and 90% by mass or less.

[0045] Base material The substrate is positioned as a target for applying the coating composition of the above embodiment to its surface to form a coating film that possesses both hydrophilicity and flexibility. The substrate is not particularly limited as long as it is capable of having the coating composition applied to its surface. The surface of the substrate may be substantially flat, or it may have a three-dimensional shape (a shape with partial or overall irregularities). Furthermore, the overall shape of the substrate may be, for example, a flat plate, i.e., a film (or sheet), or it may be any other three-dimensional object. The thickness of the substrate when it is a film is not particularly limited, but may be, for example, 5 μm to 2000 μm, preferably 10 μm to 1000 μm, 15 μm to 500 μm, or 20 μm to 300 μm.

[0046] Various materials can be used as the base material. Examples of materials that constitute the base material include, in addition to the resin materials exemplified below, inorganic materials such as glass, silica, metals, and metal oxides, and organic materials such as paper and pulp.

[0047] In one embodiment, the base material is preferably made of resin. The resin base material is not particularly limited, but examples include organic base materials such as synthetic resins and natural resins. As the synthetic resin constituting the base material, at least one type of thermoplastic resin or curable resin (thermosetting resin, photocurable resin, moisture-curable resin, etc.) can be used. Non-limiting specific examples of synthetic resins include silicone resin, acrylic resin, methacrylic resin, fluororesin, alkyd resin, aminoalkyd resin, vinyl resin, polyester resin, styrene-butadiene resin, polyolefin resin, polystyrene resin, polyketone resin, polyamide resin, polycarbonate resin, polyacetal resin, polyetheretherketone resin, polyphenylene oxide resin, polysulfone resin, polyphenylene sulfone resin, polyether resin, polyvinyl chloride resin, polyvinylidene chloride resin, urea resin, phenolic resin, melamine resin, epoxy resin, urethane resin, silicone-acrylic resin, and the like. Furthermore, the above-mentioned natural resins are not particularly limited, but examples include cellulose resins, isoprene resins such as natural rubber, and protein resins such as casein.

[0048] Examples of methods for molding the substrate include so-called three-dimensional molding methods such as membrane press molding, pressure press molding, vacuum molding, and vacuum pressure molding of a thermoplastic resin sheet; injection molding, blow molding, and extrusion molding of a thermoplastic resin; and methods of injecting a curable resin into a mold of a desired shape and curing it. In one embodiment, the surface of the resin plate may be subjected to surface treatments such as corona discharge treatment, flame treatment, or plasma treatment, but these surface treatments are not essential. The type and thickness of the substrate, as well as the thickness of the film formed by the surface treatment, are not particularly limited and can be set as appropriate depending on the application.

[0049] Hydrophilic coating or hydrophilic film The method for forming a hydrophilic coating film on part or all of the surface of a substrate using the coating composition of the above embodiment is not particularly limited, and known web coating methods can be used. Examples of web coating methods include rod coating, roll coating, gravure coating, reverse coating, kiss reverse coating, dip coating, spray coating, spin coating, air knife coating, and die coating. Among these methods, rod coating, roll coating, gravure coating, reverse coating, kiss reverse coating, and die coating are preferred from the viewpoint of applying the coating composition productively using a roll-to-roll method, rod coating is more preferred from the viewpoint of making the thickness of the coating film uniform, and rod coating using a Meyer bar as the rod (referred to as the "Meyer bar method") is even more preferred. The coating film can be formed by applying the coating composition once or twice or more times in the manner exemplified herein to form a wet coating film, optionally pre-drying it, and then curing it by irradiation with active energy rays such as ultraviolet rays or electron beams. The optional pre-drying is not particularly limited, but for example, it can be performed at a temperature of 30°C to 200°C or 40°C to 150°C for a period of 10 seconds to 10 minutes or 15 seconds to 5 minutes.

[0050] The surface of the substrate may be subjected to physical or chemical treatments such as corona treatment, flame treatment, plasma treatment, glow discharge treatment, or oxidation treatment using chemicals, as necessary, before applying the paint composition. Alternatively, the substrate may be treated with a coating agent such as a primer coat agent, undercoat agent, or anchor coat agent, for example, a polyurethane-based coating agent, before applying the paint composition to form a coating film.

[0051] A laminate consisting of a hydrophilic coating and a substrate is obtained by applying a coating composition to a substrate to form a hydrophilic coating. The hydrophilic coating usually forms the outermost surface of the laminate. A laminate in which a hydrophilic coating is formed on a film-like substrate is referred to herein simply as a "hydrophilic film" (or "hydrophilic film"). The cured thickness of the hydrophilic coating film formed on the substrate, or the cured thickness of the hydrophilic coating film constituting the hydrophilic film, is not particularly limited, but may be, for example, 0.5 μm to 500 μm, 1 μm to 100 μm, 1.5 μm to 50 μm, or 2 μm to 30 μm.

[0052] The hydrophilic coating film formed from the paint composition may preferably possess both excellent hydrophilicity and excellent flexibility in a highly balanced manner. The hydrophilic coating may have a water contact angle (one of the measures of hydrophilicity) that is measured using the KRUSS automatic contact angle meter "DSA20 (product name)" by the method shown in the examples described below, i.e., in accordance with JIS R 3257:1999, and is usually 30° or less, preferably 25° or less, more preferably 20° or less, even more preferably 15° or less, and even more preferably 10° or less. Furthermore, while it is preferable for the hydrophilic coating to possess both excellent hydrophilicity and excellent flexibility, for example, it is preferable that the hydrophilic film (cured product) formed on a film-like substrate has such high flexibility that the shrinkage curl, measured by the method shown in the examples described later, is smaller than a predetermined standard.

[0053] A laminate having a hydrophilic coating on a substrate, such as a hydrophilic film, may have an adhesive layer on the substrate surface on the side of the laminate where the coating is not formed. A release film may be provided on the surface of the adhesive layer. The laminate having a hydrophilic coating on a substrate can be bonded to the surface of another object via the adhesive layer. The thickness of the adhesive layer is not particularly limited, but may be in the range of, for example, 2 μm to 50 μm, or 4 μm to 30 μm. The adhesive forming the adhesive layer is not particularly limited, but may be, for example, an acrylic adhesive, a rubber adhesive, a vinyl ether polymer adhesive, a silicone adhesive, or any other known adhesive.

[0054] In one embodiment, at least one other layer may be interposed between the substrate and the hydrophilic coating. Such other layers are not particularly limited, but may be, for example, a hard coat layer if flexibility is not particularly required for the laminate as a whole, and / or an anchor coat layer to assist in the adhesion between the substrate and the hydrophilic coating. Any known hard coat layer and / or anchor coat layer can be appropriately selected and used. The paint for forming the hard coat layer may contain one or more of any active energy ray curable resins. As an anchor coat agent for forming the anchor coat layer, for example, one or more of polyester resins, acrylic resins, polyurethane resins, acrylic urethane resins, polyester urethane resins, ethylene-vinyl acetate copolymer resins, and vinyl chloride-vinyl acetate copolymer resins can be used. If such other layers are present, their thickness is not particularly limited, but may be, for example, 1 μm to 100 μm, 2 μm to 50 μm, or 3 μm to 30 μm.

[0055] Preferably, the hydrophilic coating film formed from the paint composition possesses both hydrophilicity and flexibility, and furthermore, has excellent scratch resistance and / or adhesion to the substrate. Furthermore, the hydrophilic coating film formed from the paint composition may have excellent stain resistance. The hydrophilic coating film formed from the paint composition can be suitably used as an anti-fogging coating (or anti-drip coating), an anti-fouling coating, an anti-static coating, and the like.

[0056] In one embodiment, examples of articles that may use a hydrophilic coating or a laminate having a hydrophilic coating on a substrate include, but are not limited to, the following: Vehicles and vehicle materials; ships and ship materials; aircraft and aircraft materials; buildings and building materials; windows, mirrors, exterior walls, exteriors, bodies, wheels, interior walls, interior finishes, floors, furniture and furniture materials for vehicles, ships, aircraft and buildings, etc.; utilities and materials such as piping and wiring; clothing and textile products such as cloth; household equipment and materials such as washbasins, bathrooms, powder rooms, ventilation fans and kitchens; electrical appliances and materials such as washing machines, dish dryers, refrigerators, microwave ovens, ovens and shavers; monitors, displays, signs, instruments, indicators and materials therefor; optical films, Optical articles and materials such as optical discs, optical lenses, eyeglass lenses, glasses, sunglasses, contact lenses, goggles, helmet shields, headlamps, taillamps, etc.; dental materials such as dentures and dentures; lighting articles and materials such as lamps and lights; heat exchanger components and materials such as cooling fins; recording and printing materials such as photoresists and inkjet recording plates; cosmetic containers and materials; reflective materials such as reflective films and reflectors; sound insulation panels installed on highways, etc.; display materials; primers for printing or marking, and other primers; flat panels, etc. [Examples]

[0057] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0058] Measurement method 1) Hardening shrinkage curl test (flexibility test) As described below, the central part of the obtained A4-sized test film was cut to a size of 10 cm x 10 cm to serve as a test specimen for the curing shrinkage curl test. The test specimen was positioned on the edge of the test table with the coated surface of the paint composition facing upwards and the side opposite to the coated surface (i.e., the substrate side) facing downwards, so that only the side opposite to the coated surface of the 1 cm wide strip portion in the MD direction from one side in the CD direction (the direction perpendicular to the MD direction, which is the winding direction from the film manufacturing machine) was in contact with the surface of the test table. The portion of the test specimen from 1 cm to 10 cm opposite the side in the MD direction from one side in the CD direction (i.e., the remaining portion excluding the 1 cm wide strip portion) was left suspended in the air without contact with the surface of the test table. When the contact surface between the test table and the test specimen is used as the reference surface, the midpoint between the highest and lowest curvature heights of the coated surface on opposite sides of the edge fixed to the end of the test table of the test specimen was measured and evaluated according to the following criteria. It is considered that if a large shrinkage occurs when the film hardens and forms a coating, the flexibility of the coating is impaired and a large curl occurs, while if the shrinkage that occurs when the film hardens and forms a coating is small, the resulting curl is small and the flexibility of the coating is maintained. ◎ (Excellent): The height of the midpoint was less than 0 mm. (Note: "Less than 0 mm" means that the floating portion of the test specimen hangs below the reference plane.) ○ (Good): The height of the midpoint was between 0 mm and 10 mm. △ (Moderate): The height of the midpoint was between 10 mm and 30 mm. × (Defective): The height of the midpoint was 30 mm or more.

[0059] For ease of understanding, Figure 1 shows an overhead perspective view of the test set as an overview of this curing shrinkage curl test. Each reference number in Figure 1 represents, respectively: 1: Test piece of the test film, 1a: Coating film (coated surface of the paint composition) constituting the test film, 1b: Substrate constituting the test film, arrow CD: CD direction of the test piece, 1t: Strip portion of the test piece placed and fixed on the edge of the test table (1 cm wide from one side in the CD direction to the MD direction), S1: One side of the test piece in the CD direction (the side placed and fixed on the edge of the test table), S2: Opposite side of side S1 in the CD direction of the test piece, 2: Test table for placing and fixing the test piece, a: The highest curvature height of the coated surface of side S2 opposite side S1 fixed on the edge of the test table of the test piece, b: The lowest curvature height of side S2 opposite side S1 fixed on the edge of the test table of the test piece. The "midpoint" mentioned above is the midpoint between heights a and b in Figure 1 (i.e., (a+b) / 2).

[0060] 2) Magic Floating Test 1 (Hydrophilicity Test) As described below, lines were drawn on the coated surface of the obtained test film with an oil-based pen (Zebra Corporation's "Hi-Mackie" black). After 30 seconds, pure water was dripped over the entire surface using a washing bottle, and the state of the ink was visually observed for 30 seconds. After that, the surface was wiped with a cotton gauze soaked in water, and the state of the ink on the surface of the coating was visually observed and evaluated according to the following criteria. Rating A: When pure water was added, the ink immediately floated to the surface. Rating B: When pure water was dropped onto the paper, the ink floated to the surface after more than 5 seconds. Rating C: The ink did not float when pure water was added. The ink could be removed by wiping with water. No ink residue remained after removal. Rating D: The ink did not float even when pure water was added. The ink could be removed by wiping with water, but ink stains remained. Rating E: The ink could not be removed at all, neither by adding pure water nor by wiping with water.

[0061] 3) Magic Floating Test 2 (Hydrophilic Durability Test) The above Magic Test 1 was repeated twice. That is, the Magic Test 1 was repeated again on the coated surface of the test film after the Magic Test 1 had been performed. This was evaluated using the same criteria as Magic Test 1.

[0062] 4) Steel wool resistance (SW) test (scratch resistance test) As described below, the test pieces of the obtained test film were placed on a JIS L0849:2013 JSPS-type testing machine (friction testing machine type 2) with the coated surface facing outwards. Subsequently, #0000 steel wool was attached to the friction terminal of the JSPS-type testing machine, a 200g load was applied, and the surface of the test piece was rubbed back and forth 10 times under conditions of a friction terminal movement speed of 300mm / min and a movement distance of 30mm. After that, the friction area was visually observed and evaluated according to the following criteria. ○ (Good): No blemishes, or 1-5 blemishes. △ (Moderate): There were 6 to 15 scratches. × (Defective): There were 16 or more scratches.

[0063] 5) Grid test (adhesion test) In accordance with JIS K5600-5-6:1999, 100 grid-like cuts (1 grid = 1 mm x 1 mm) were made on the coated side of the test film obtained as described below. Then, adhesion test tape was applied to the grid, rubbed with a finger, and peeled off. Adhesion was evaluated according to Table 1 of the above JIS standard. Classification 0: The edges of the cuts were perfectly smooth, and there was no peeling in any of the grid lines. Classification 1: There was minor paint peeling at the intersection of the cuts. The affected area at the cross-cut sections never clearly exceeded 5%. Classification 2: The paint film peeled along the edges of the cuts and / or at the intersections. The affected area in the cross-cut sections clearly exceeded 5%, but never exceeded 15%. Classification 3: The paint film was partially or completely peeling along the edges of the cuts, and / or peeling was partially or completely in various parts of the grain. The affected area in the cross-cut sections was clearly more than 15%, but never exceeded 35%. Classification 4: The paint film was partially or completely peeling along the edges of the cuts, and / or several areas were partially or completely peeling. The affected area in the cross-cut sections clearly exceeded 35%, but never exceeded 65%. Classification 5: This classification applies when the degree of peeling exceeds that of Classification 4.

[0064] 6) Measurement of initial water contact angle (hydrophilicity test) Following the method for calculating the water contact angle from the width and height of a water droplet (JIS R 3257:1999), the water contact angle (in degrees) of the low refractive index layer surface of the test film (coating stage C) obtained as described below was measured using KRUSS's automatic contact angle meter "DSA20" (product name).

[0065] Raw materials used (A) Active energy ray curable resin having anionic hydrophilic groups (hydrophilic resin) (A-1) Nostra SA manufactured by Mitsui Chemicals, Inc. (Solid content: 80% by mass)

[0066] (B) (meth)acryloyl group-containing polyester polyol (flexibility agent) (B-1) "Arronix M-8060" (product name) manufactured by Toagosei Co., Ltd.: A polyester polyol containing four (meth)acryloyl groups in its molecule. (B') Comparative substance of component (B) (B'-2) "KARAYAD DPHA" (product name) manufactured by Nippon Kayaku Co., Ltd.: Dipentaerythritol pentaacrylate / dipentaerythritol hexaacrylate mixture (B'-3) "UA-4400" (product name) manufactured by Shin Nakamura Chemical Industry Co., Ltd.: Polyester-based urethane acrylate resin (B'-4) "UA-W2A" (product name) manufactured by Shin Nakamura Chemical Industry Co., Ltd.: Polyether-based urethane acrylate resin (B'-5) "M-1100" (product name) manufactured by Toagosei Co., Ltd.: Urethane acrylate resin (B'-6) "M-1200" (product name) manufactured by Toagosei Co., Ltd.: Urethane acrylate resin (B'-7) "EBECREL 80" (product name) manufactured by Daicel Ornex Co., Ltd.: Amine-modified polyether acrylate resin

[0067] (C) Photopolymerization initiator (C-1) IGM Resins' hydroxyacetophenone-based photopolymerization initiator (2-Hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methyl-propan-1-one) "Omnirad 127" (trade name)

[0068] (D) Solvent (D-1) methanol (D-2)n-butanol

[0069] (P) Film substrate (P-1) Mitsubishi Chemical Corporation's 50μm thick biaxially oriented polyethylene terephthalate film "Diafoil T600E50 (W07-)" (product name)

[0070] Example 1 To 100 parts by mass of the solid content of (A-1) above, 7.5 parts by mass of (B-1), 82.5 parts by mass of (B'-2), 3.75 parts by mass of (C-1), 51.25 parts by mass of (D-1), and 28.75 parts by mass of (D-2) above were thoroughly mixed and stirred at room temperature to prepare a hydrophilic paint composition (Q-1). Using this hydrophilic coating composition (Q-1), a wet coating film was formed on one side of the film substrate (P-1) using a film Mayer bar coating apparatus, with a cured thickness of 3 μm. Next, this wet coating film was pre-dried in a drying oven, and then cured by irradiation with ultraviolet light to form a hydrophilic coating film, thereby obtaining a hydrophilic film having a hydrophilic coating film on one side of the film substrate. This hydrophilic film was cut to A4 size with the machine direction (MD direction) of the film substrate (P-1) as the long side, and used as a test film. Physical property tests 1) to 6) above were performed on this test film to measure and evaluate its physical properties. Table 1 below shows the composition of components (A) and (B) of the paint composition in Example 1, as well as the measurement and evaluation results of each physical property test on the test film.

[0071] Examples 2-8 Except for changing the compositions of components (A) and (B) as shown in Table 1 to prepare paint compositions (Q-2) to (Q-8), the preparation of test films and each physical property test were carried out in the same manner as in Example 1 (Examples 2 to 8). Table 1 below shows the compositions of components (A) and (B) of the paint compositions used in Examples 2 to 8, as well as the measurement and evaluation results of each physical property test on the test films.

[0072] [Table 1]

[0073] The results shown in the table above indicate that by using a coating composition containing a hydrophilic active energy ray curable resin along with a highly lipophilic (meth)acryloyl group-containing polyester polyol, it is possible to form a coating film that possesses both high hydrophilicity and high flexibility. Furthermore, it was found that the coating film formed from the preferred embodiment of the coating composition exhibits high hydrophilicity and high flexibility, as well as excellent scratch resistance and adhesion to the substrate.

Claims

1. A coating composition for forming a hydrophilic coating or film, (A) Active energy ray curable resin having anionic hydrophilic groups, and (B) (meth)acryloyl group-containing polyester polyol A paint composition containing the following:

2. The coating composition according to claim 1, wherein the polycarboxylic acid constituting the (B) (meth)acryloyl group-containing polyester polyol comprises at least one selected from the group consisting of linear aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and ester-forming derivatives thereof.

3. The coating composition according to claim 2, wherein the polycarboxylic acid constituting the (B) (meth)acryloyl group-containing polyester polyol comprises at least one alicyclic dicarboxylic acid selected from the group consisting of 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, and norbornanedicarboxylic acid.

4. The coating composition according to claim 1 or claim 2, wherein the anionic hydrophilic group of the active energy ray curable resin having an anionic hydrophilic group (A) comprises at least one selected from the group consisting of a sulfonic acid group, a carboxyl group, and a phosphate group.

5. The paint composition according to claim 1 or claim 2, wherein the (A) active energy ray curable resin having an anionic hydrophilic group comprises a polymer formed from a monomer containing a hydroxy(meth)acrylate having a sulfonic acid group.

6. The coating composition according to claim 1 or claim 2, wherein the (B) (meth)acryloyl group-containing polyester polyol comprises a polyester polyol having two or more (meth)acryloyl groups in its molecule.

7. (C) The coating composition according to claim 1 or claim 2, further comprising a photopolymerization initiator.

8. A hydrophilic coating film formed from the paint composition according to claim 1 or claim 2.

9. A hydrophilic film formed from the paint composition according to claim 1 or claim 2.

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