Hydrophilic coating composition

Abstract

To provide a coating composition that has a superior hydrophilic antifouling property, and allows for easy removal of any fur fixed thereon.SOLUTION: A hydrophilic coating composition includes a resin (A) including a quaternary ammonium base with a specific structural unit and a hydroxy group, a binder resin (B) including a hydroxy group, and a curing agent (C). The hydrophilic coating composition gives a cured coating having a dynamic glass transition temperature of 80°C-140°C. A cured coating and a coated article obtained therefrom are also provided.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention resin having a specific group This relates to hydrophilic coating compositions and coated articles containing these components. [Background technology]

[0002] Surface properties required for plastic substrates include stain resistance, anti-fogging properties, antistatic properties, and recoatability. Generally, these surface properties are achieved by imparting hydrophilicity to the substrate, and various hydrophilic resins and hydrophilic coating compositions have been proposed to date.

[0003] Patent Document 1 discloses a hydrophilic copolymer containing two types of quaternary ammonium salts. However, although the composition described in Patent Document 1 exhibits highly persistent hydrophilicity, a problem arises in that limescale adheres to it and cannot be removed if water remains after washing.

[0004] Patent Document 2 discloses an antistatic layer formed from an antistatic agent composition containing a (meth)acrylic polymer containing a quaternary ammonium salt and a crosslinking agent. However, although the composition described in Patent Document 2 exhibits hydrophilicity, it has high water absorption, and problems such as whitening occur when it comes into contact with moisture. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6408096 [Patent Document 2] Patent No. 6263379 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The objective of the present invention is to provide a paint composition that exhibits excellent stain resistance due to its hydrophilic properties, and furthermore, allows for easy removal of limescale even if it adheres to the surface.

Means for Solving the Problem

[0007] The inventors of the present invention have conducted intensive studies to solve the above problems. As a result, it has become possible to provide a resin having a specific structure (The following formula (1)) that has both antifouling properties due to hydrophilicity and the performance of removing the adhesion of scale deposits.

[0008] That is, the present invention provides the following aspects: [1] The base represented by formula (1) A hydrophilic coating composition comprising a resin (A) containing a hydroxyl group, a binder resin (B) containing a hydroxyl group, and a curing agent (C), Formula (1):

Chemical formula

Chemical formula

[0009] According to the present invention, a specific structure The base (the base represented by formula (1)) A coating film formed using a resin containing both hydroxyl groups exhibits excellent stain resistance and durability due to the development of surface hydrophilicity, and furthermore, water stains can be easily removed even if they adhere to the surface. [Modes for carrying out the invention]

[0010] The embodiments for carrying out the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below. Furthermore, in this specification, "X~Y" indicating a range means "X or more and Y or less," and "weight" and "mass," "weight%" and "mass%," and "parts by weight" and "parts by mass" are treated as synonyms.

[0011] In this specification, the term "(meth)acrylic" includes both acrylic and methacrylic. Therefore, for example, the term "(meth)acrylic acid" includes both acrylic acid and methacrylic acid. Similarly, the term "(meth)acrylate" includes both acrylate and methacrylate.

[0012] < The base represented by formula (1) and resins containing hydroxyl groups (A) The resin (A) used in the present invention is of formula (1) The base represented by : [ka] (In formula (1), Ra 1 is a hydrogen atom or a substituted or unsubstituted C1-C6 alkyl group, Ya ー The formula is as follows (1'): [ka] (In the above formula (1’), R’ is a substituted or unsubstituted linear or branched C12-C14 alkyl group, A’ is a linear or branched C2-C4 alkylene group, and m is the average number of moles of addition of A’O, which is an integer of 2-50.) (It is an anion represented by) represented by base characterized by having However, the anion (counter anion) in formula (1) above is the Ya ー This includes only that and does not include other counter anions.

[0013] The above In formula (1) , R a 1 is a substituted or unsubstituted C1-C6 alkyl group, and from the viewpoint of improving the surface hydrophilicity of the coating film, it is preferably a substituted or unsubstituted C1-C3 alkyl group, more preferably a substituted or unsubstituted C1-C2 alkyl group, and they may be the same or different from each other. At this time, the substituent that may be present is preferably a C6-C18 aryl group, more preferably a phenyl group, from the viewpoint of compatibility with the binder resin.)

[0014] In the above formula (1), Y a - is an anion represented by the following formula (1’), [Chemical formula]<00资源标签专利文本直链状 分枝状 平均付加 表面亲水性 相溶性In formula (1') above, R' is a substituted or unsubstituted C12-C14 linear or branched alkyl group, i.e., a substituted or unsubstituted dodecyl group (n-dodecyl group, isododecyl group, etc.), a substituted or unsubstituted tridecyl group (n-tridecyl group, isotridecyl group, etc.), or a substituted or unsubstituted tetradecyl group (n-tetradecyl group, isotetradecyl group, etc.). From the viewpoint of availability, it is preferable that R' be a substituted or unsubstituted dodecyl group or a substituted or unsubstituted tridecyl group, and particularly preferable that R' be a substituted or unsubstituted tridecyl group. Furthermore, from the viewpoint of further improving the effects of the present invention, it is preferable that the C12-C14 alkyl group in R' is branched. Therefore, in a preferred embodiment of the present invention, R' is a substituted or unsubstituted branched tridecyl group.

[0015] In formula (1') above, A' is a linear or branched alkylene group of C2 to C4. Examples of linear or branched alkylene groups of C2 to C4 include ethylene group, trimethylene group, propylene group (-CH2-CH(CH3)-), n-butylene group, 1-methylpropylene group (-CH2-CH2-CH(CH3)-), 2-methylpropylene group (-CH2-CH(CH3)-CH2-), dimethylethylene group (-CH2-C(CH3)2-), ethylethylene group (-CH2-CH(CH2CH3)-), etc.

[0016] In the above formula (1'), m is the average number of moles of A'O added, which is between 2 and 50, preferably between 2 and 30, more preferably between 2 and 20, and even more preferably between 2 and 10, from the viewpoint of improving workability by reducing the surface hydrophilicity and viscosity of the coating film.

[0017] That is, in the above equation (1'), (A'O) m (A'O) represents a polyoxyalkylene group. mIt preferably contains two or more oxyalkylene groups, and more preferably an oxybutylene group (-C4H8O-). The inclusion of such groups prevents the copolymer from becoming excessively hydrophilic, resulting in good affinity with binder resins and organic solvents. (A'O) m It is preferable that the compound further contains an oxyethylene group (-C2H4O-). The oxybutylene group preferably has a branched alkylene group, and more preferably contains at least one of the groups represented by the following formula. Including such groups further improves the affinity with the binder resin and organic solvents, as well as the surface hydrophilicity of the coating film.

[0018] [ka]

[0019] In the above equation (1'), (A'O) m The proportion of oxybutylene groups in is preferably 3 to 90 mol%, more preferably 10 to 80 mol%, even more preferably 20 to 50 mol%, and particularly preferably 30 to 40 mol%. If the oxybutylene group has two or more structures, the proportion of oxybutylene groups represents the sum of the proportions (mol%) of each structure. (A'O) m If the material contains two or more oxyalkylene groups, the arrangement may be random or block-shaped, but a block-shaped arrangement is preferred from the viewpoint of further enhancing the surface hydrophilic effect of the coating film. In the case of a block-shaped arrangement, the order of the arrangement does not matter. That is, the sulfonic acid group may be linked to a polyoxyethylene chain and then a polyoxybutylene chain in that order, or vice versa.

[0020] The above resin (A) is represented by the above formula (1). The base It is formed by reacting three monomers: a (meth)acrylic monomer (a) having a hydroxyl group, a (meth)acrylic monomer (b) containing a hydroxyl group, and optionally a monomer (c) that can copolymerize with them. Therefore, in the resin (A) of the present invention, the hydrophilic group is represented by the above formula (1) The baseIt is necessary that it does not contain any other hydrophilic groups. Furthermore, when resin (A) uses a (meth)acrylic monomer as described above, it may also be called (meth)acrylic resin (A).

[0021] The above-mentioned (meth)acrylic monomer (a) specifically includes salts of (meth)acrylic monomers such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate with polyoxyalkylene alkyl ether sulfates. These compounds may be used individually or in combination of two or more. The (meth)acrylic monomer (a) may be either a synthetic product or a commercially available product.

[0022] This invention The base represented by formula (1) The hydroxyl group-containing (meth)acrylic monomer (b) used in the synthesis of the hydroxyl group-containing resin (A) is a commonly used hydroxyl group-containing (meth)acrylic monomer, specifically including 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl acrylate, N-methylol (meth)acrylamide, and the like.

[0023] (Meth)acrylic monomer (b) may be either a synthetic or commercially available product. Monomer B may be used alone or in combination of two or more types.

[0024] The resin (A) of the present invention is synthesized using specific (meth)acrylic monomers (a) and (b) as described above, but monomer (c) which can copolymerize with monomers (a) and (b) may be used as needed. Monomer (c) is as described above. The base represented by formula (1) Any material is acceptable as long as it does not contain groups that affect hydroxyl groups. Specifically, alkyl (meth)acrylates that do not contain functional groups (specifically, methyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.); acrylonitrile; styrene; etc. are common. In addition, (meth)acrylic monomer (c) is as described above. The base represented by formula (1)They may also contain carboxylic acid groups, silicone-modified groups, fluorine-containing groups, etc., as long as they do not affect the hydroxyl groups. Specific examples of such (meth)acrylic monomers (c) include carboxylic acid group-containing (meth)acrylic monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, and fumaric acid; silicone-modified group-containing (meth)acrylic monomers such as AK-30, AK-32, and AK-5 manufactured by Toagosei Co., Ltd.; and fluorine-containing (meth)acrylic monomers such as 2,2,3,3,3-pentafluoropropyl (meth)acrylate and 2-(perfluorohexyl)ethyl (meth)acrylate.

[0025] In the synthesis of resin (A) of the present invention, the amount of (meth)acrylic monomer (a) used is 5 to 80% by weight relative to the total weight of monomers (a), (b), and (c) (total resin (A)). If the amount is 5% by weight or more, the surface hydrophilicity is excellent. On the other hand, if the amount is 80% by weight or less, the affinity with organic solvents and binder resins is good, and the water resistance of the coating film itself is also excellent. In particular, from the viewpoint of further achieving the effects of the present invention, it is more preferably 30 to 75% by weight, and even more preferably 50 to 70% by weight.

[0026] In the synthesis of resin (A) of the present invention, the amount of (meth)acrylic monomer (b) used is 5% by weight or more and less than 40% by weight relative to the total weight of monomers (a), (b), and (c) (total resin (A)). If it is less than 5% by weight, the formation of a crosslinked structure including the hydrophilic copolymer will be insufficient. That is, the hydrophilic copolymer will not be firmly fixed in the coating film, and the surface hydrophilicity will not last. In addition, the hardness of the coating film will also decrease. On the other hand, if it is 40% by weight or more, the compatibility with the binder resin will be poor, and it will not be possible to form a coating film, or even if a coating film can be formed, the transparency will be significantly inferior. In particular, from the viewpoint of further achieving the effects of the present invention, it is preferably 10% by weight or more and less than 35% by weight, and more preferably 20% by weight or more and less than 30% by weight.

[0027] In the synthesis of resin (A) of the present invention, the amount of (meth)acrylic monomer (c) used is preferably 40% by weight or less, more preferably 30% by weight or less, and particularly preferably 20% by weight or less (lower limit: 0% by weight) relative to the total weight of monomers (a), (b), and (c) (total resin (A)).

[0028] <Physical properties of resin (A)> The weight-average molecular weight of resin (A) of the present invention is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, even more preferably 10,000 to 30,000, and particularly preferably 15,000 to 20,000, from the viewpoint of affinity with organic solvents and binder resins and workability. The weight-average molecular weight is determined by gel permeation chromatography (GPC) (standard substance: polyethylene glycol / polyethylene oxide).

[0029] The glass transition temperature of resin (A) of the present invention is preferably -10 to 50°C.

[0030] The hydroxyl value of resin (A) of the present invention is preferably 20 to 170 mg KOH / g, more preferably 50 to 150 mg KOH / g, and even more preferably 90 to 120 mg KOH / g. Within this range, the effects of the present invention are further enhanced. Note that the hydroxyl value of resin (A) refers to the number of milligrams of potassium hydroxide required to acetylate the hydroxyl groups contained in 1 g of the hydrophilic copolymer. Specifically, Resin (A) The hydroxyl value is, Resin (A) This value is measured by preparing a pyridine solution containing acetic anhydride, acetylating the hydroxyl groups in the hydrophilic copolymer, hydrolyzing the excess acetylating reagent with water, and titrating the resulting acetic acid with potassium hydroxide.

[0031] The resin (A) of the present invention may be an alternating copolymer, a random copolymer, or a block copolymer.

[0032] <Method for manufacturing resin (A)> This invention The base represented by formula (1) Resins (A) containing hydroxyl groups can be produced by polymerizing the corresponding monomers using various polymerization methods, such as conventionally known polymerization methods, including solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, reverse-phase suspension polymerization, thin-film polymerization, and spray polymerization. Methods for controlling polymerization include adiabatic polymerization, temperature-controlled polymerization, and isothermal polymerization. Among these, solution polymerization using a polymerization initiator (preferably a thermal polymerization initiator) is preferred because it allows for easy adjustment of molecular weight and results in low levels of impurities.

[0033] Examples of thermal polymerization initiators include 2,2-azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylbutyronitrile) (AMBN), azobiscyanovaleric acid, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 1 ,1'-Azobis(cyclohexane-1-carbonnitrile), 2,2'-Azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-Azobis(N-butyl-2-methylpropionamide), 2,2'-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(2-imidazolin-2-yl)propane]disulfate dihydrate, 2,2'-Azobis Examples include azo compounds such as (2-methylpropionamidine)dihydrochloride, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis(1-imino-1-pyrrolidino-2-methylpropane)dihydrochloride, and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]; organic peroxides such as tert-butylperoxypivalate, tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate, di-tert-butylperoxide, cumenehydroperoxide, benzoylperoxide, and tert-butylhydroperoxide; and inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate. These can be used individually or in combination of two or more.

[0034] Furthermore, a chain transfer agent may be used to adjust the molecular weight during the synthesis of the polymer precursor. The amount of chain transfer agent added is preferably 0.1 to 5% by weight, more preferably 0.5 to 3% by weight, and even more preferably 1 to 2% by weight, relative to the total weight of the monomers to be copolymerized.

[0035] Examples of chain transfer agents include mercaptans such as methyl mercaptan, t-butyl mercaptan, decyl mercaptan, benzyl mercaptan, lauryl mercaptan, stearyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid and its esters, 2-ethylhexylthioglycol, and octyl thioglycolate; methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, hexyl Examples include alcohols such as sanol, benzyl alcohol, and allyl alcohol; halogenated hydrocarbons such as chloroethane, fluoroethane, and trichloroethylene; carbonyl compounds such as acetone, methyl ethyl ketone, cyclohexanone, acetophenone, acetaldehyde, propionaldehyde, n-butyraldehyde, furfural, and benzaldehyde; and methyl-4-cyclohexene-1,2-dicarboxylic acid anhydride, α-methylstyrene, and α-methylstyrene dimer. These may be used individually or in combination of two or more.

[0036] The polymerization solvent includes each monomer to be polymerized, the polymer precursor to be produced, and, if necessary, The solvent is not particularly limited as long as it can dissolve polymerization initiators and other additives, and can be methanol, ethanol, isopropanol, tetrahydrofuran, cyclohexanone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, diethylene glycol dimethyl ether, 1-methoxy-2-propanol, 1-methoxy-2-propyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, ethyl acetate, ethyl lactate, methyl lactate, dimethyl sulfoxide, water, etc. These may be used alone or in combination of two or more.

[0037] The copolymer obtained by the above method can be modified as needed by adjusting the solid content concentration, exchanging the solvent, or filtering it, and then adding additives. Alternatively, the hydrophilic copolymer produced by polymerization can be purified by precipitation or reprecipitation with hexane or the like, and then dissolved together with additives in a solvent suitable for the application.

[0038] <Hydrophilic paint composition> The present invention The base represented by formula (1) The present invention provides a hydrophilic coating composition (hereinafter also simply referred to as "the composition") comprising a resin (A) containing hydroxyl groups, a binder resin (B) containing hydroxyl groups, and a curing agent (C).

[0039] The following describes each component of the composition. <Binder resin (B) containing hydroxyl groups (hereinafter sometimes simply referred to as "binder resin (B)")> The binder resin (B) is not particularly limited as long as it is a resin having hydroxyl groups, but it is preferable that it is a resin that can undergo a crosslinking reaction through the action of the curing agent (C) described below. This forms a crosslinked structure inside the coating film, improving the hardness and durability of the coating film. In addition, since resin (A) can bond to the binder resin (B) (via the curing agent), a coating film in which resin (A) is firmly fixed can be obtained. Therefore, the surface hydrophilicity of the coating film is more sustained (i.e., the durable hydrophilicity is further improved).

[0040] For example, binder resin (B) contains hydroxyl groups. Binder resin (B) The base represented by formula (1) Furthermore, by combining a resin (A) containing hydroxyl groups with a curing agent (C) such as polyisocyanate or melamine resin, a cross-linked structure can be formed between the three. That is, The base represented by formula (1) and present in resin (A) containing hydroxyl groups The base represented by formula (1) A coating film containing [the specified element] can be obtained.

[0041] Examples of binder resins (B) containing hydroxyl groups include macropolyols such as acrylic polyols, polyether polyols, polyester polyols, polycarbonate polyols, epoxy polyols, natural oil polyols, silicone polyols, fluorine polyols, polyolefin polyols, and polyurethane polyols. Among these, acrylic polyols are preferred from the viewpoint of compatibility with the hydrophilic copolymer and, consequently, the transparency of the coating film.

[0042] Examples of acrylic polyols include copolymers obtained by copolymerizing a polymerizable monomer having one or more hydroxyl groups with another monomer copolymerizable thereto. Examples of polymerizable monomers having hydroxyl groups include 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl acrylate, 2,2-dihydroxymethylbutyl (meth)acrylate, polyhydroxyalkyl maleate, and polyhydroxyalkyl fumarate. Examples of other monomers copolymerizable with these include (meth)acrylic acid, alkyl (meth)acrylate (1-12 carbon atoms), maleic acid, alkyl maleate, fumaric acid, alkyl fumarate, itaconic acid, alkyl itaconate, styrene, α-methylstyrene, vinyl acetate, and (meth)acrylonitrile.

[0043] Polyether polyols can be obtained, for example, by ring-opening addition polymerization (homopolymerization or copolymerization (block copolymerization and / or random copolymerization when ethylene oxide and propylene oxide are used in combination as alkylene oxides) or cyclic ethers (tetrahydrofuran, 3-methyltetrahydrofuran, oxetane compounds) of low molecular weight polyols and / or low molecular weight polyamines.

[0044] Examples of polyester polyols include polyester polyols obtained by condensation or transesterification reactions of low molecular weight polyols with polybasic acids, their alkyl esters, their acid anhydrides, and their acid halides; lactone-based polyols such as polycaprolactone polyols and polyvalerolactone polyols obtained by ring-opening polymerization of low molecular weight polyols with lactones such as ε-caprolactone and γ-valerolactone; and further, lactone-based polyester polyols obtained by copolymerizing these polycaprolactone polyols, polyvalerolactone polyols, etc., with the above-mentioned dihydric alcohols.

[0045] Examples of polycarbonate polyols include polycarbonate polyols obtained by polymerizing low molecular weight polyols with carbonates such as ethylene carbonate and dimethyl carbonate.

[0046] Examples of epoxy polyols include epoxy polyols obtained by reacting a low molecular weight polyol with a polyfunctional halohydrin such as epichlorohydrin or β-methylepichlorohydrin.

[0047] Examples of natural oil polyols include hydroxyl group-containing natural oils such as castor oil and coconut oil.

[0048] Examples of silicone polyols include copolymers in which a vinyl group-containing silicone compound is used as another copolymerizable monomer in the copolymerization of the acrylic polyols mentioned above, and terminal alcohol-modified polydimethylsiloxanes.

[0049] Examples of fluorinated polyols include copolymers in which, in the copolymerization of the acrylic polyols described above, a vinyl group-containing fluorinated compound is used as another copolymerizable monomer.

[0050] Examples of polyolefin polyols include polybutadiene polyols and partially saponified ethylene-vinyl acetate copolymers.

[0051] The binder resin (B) containing hydroxyl groups may be used alone or in combination of two or more types.

[0052] The binder resin (B) containing hydroxyl groups must have a solubility parameter (SP) of 10.4 to 11.7, preferably 10.6 to 11.2, and more preferably 10.8 to 11.0. If the solubility parameter is less than 10.4, hydrophilicity decreases. If the solubility parameter is higher than 11.7, water resistance decreases.

[0053] The solubility parameter (SP) is an abbreviation for solubility parameter and is a measure of solubility. A higher SP value indicates higher polarity, while a lower SP value indicates lower polarity. The unit of SP value is (MPa). 1 / 2 It is used, but it is often not used.

[0054] For example, the SP value can be measured by the following method [Reference: SUH, CLARKE, JPSA-1, 5, 1671~1681 (1967)].

[0055] As a sample, 0.5 g of organic solvent is weighed into a 100 ml beaker, 10 ml of acetone is added using a volumetric pipette, and the solvent is dissolved using a magnetic stirrer. A poor solvent is added dropwise to this sample using a 50 ml burette at a measurement temperature of 20°C, and the point at which turbidity occurs is recorded as the volume added. Deionized water is used as the high-SP poor solvent, and n-hexane is used as the low-SP poor solvent, and turbidity is measured for each. The SP value δ of the organic solvent is given by the following formula. δ=(V ml 1 / 2 δ ml +V mh 1 / 2 δ mh ) / (Vml 1 / 2 +V mh 1 / 2 ) V m =V1V2 / (φ1V2+φ2V1) δ m =φ1δ1+φ2δ2 Vi: Molecular volume of solvent (ml / mol) φi: Volume fraction of each solvent at the turbidity point δi: SP value of the solvent ml: Low SP poor solvent mixed system mh: High SP poor solvent mixed system

[0056] Furthermore, the SP value can be calculated using the energy parameters described in "KLHoy JPT42,76 (1970)" and following the method proposed by Small in "PASmall J.Appl.Chem.3,71 (1953)".

[0057] The calculated glass transition temperature (Tg) of the binder resin (B) is preferably 10 to 100°C, more preferably 50 to 90°C, and even more preferably 70 to 80°C. In this specification, "calculated glass transition temperature" refers to the value calculated by Fox's formula shown in formula (1) below. In the examples of this specification, the calculated glass transition temperature for each binder resin used was calculated from the Tg of the monomers shown in the table.

[0058] 1 / Tg=Wa / Tga+Wb / Tb+...Wn / Tgn (1) In formula (1), Tg: Glass transition temperature (K) of the binder resin Tga: Glass transition temperature (K) of the homopolymer of monomer A Wa: Weight fraction of monomer A Tgb: Glass transition temperature (K) of monomer B homopolymer Wb: Weight fraction of monomer B Tgn: Glass transition temperature (K) of monomer N homopolymer Wn: Weight fraction of monomer N (Wa + Wb + .....Wn = 1)

[0059] The hydroxyl value of the binder resin (B) containing hydroxyl groups is preferably 20 to 170 mg KOH / g, more preferably 50 to 150 mg KOH / g, and even more preferably 80 to 120 mg KOH / g. The hydroxyl value of the binder resin refers to the number of milligrams of potassium hydroxide required to acetylate the hydroxyl groups contained in 1 g of the binder resin. Specifically, the hydroxyl value of the binder resin is measured by preparing the binder resin as a pyridine solution containing acetic anhydride, acetylating the hydroxyl groups contained in the binder resin, hydrolyzing the excess acetylating reagent with water, and titrating the resulting acetic acid with potassium hydroxide.

[0060] The weight-average molecular weight of the binder resin (B) containing hydroxyl groups is preferably 1,000 to 500,000, more preferably 4,000 to 40,000, and particularly preferably 10,000 to 30,000. The weight-average molecular weight is determined by gel permeation chromatography (GPC) (standard substance: polystyrene).

[0061] <Hardening agent (C)> The hardening agent (C) is The base represented by formula (1) Furthermore, it promotes the crosslinking reaction of the resin (A) containing hydroxyl groups and the binder resin (B) containing hydroxyl groups, contributing to the formation of a crosslinked structure inside the coating film.

[0062] In the case of a hardening agent incorporated into a cross-linked structure, The base represented by formula (1) It is preferable that the resin (A) containing hydroxyl groups and the binder resin (B) containing hydroxyl groups have functional groups or structures that crosslink with each other. In this case, the crosslinking can be covalent, ionic, hydrogen, or coordinate, but covalent bonding is preferred.

[0063] The curing agent (C) is specifically a polyisocyanate compound or melamine resin. Examples of polyisocyanate compounds include aliphatic, alicyclic, or aromatic polyisocyanates. Specifically, examples include isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, triene diisocyanate, polymeric MDI (diphenylmethane diisocyanate), naphthalene diisocyanate, tetramethyl xylylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate methyl ester, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, methylenebis(4,1-cyclohexylene) diisocyanate, 1,3-bis(isocyanate methyl)cyclohexane, adducts of diisocyanate compounds and polyol compounds such as trimethylolpropane, and isocyanate derivatives such as biuret and isocyanurate forms of diisocyanate compounds. Among these, polyisocyanates derived from hexamethylene diisocyanate are preferred from the viewpoint of suppressing yellowing of the coating film. Commercially available products include Duranate® TPA-100, TKA-100, 24A-100, 22A-75P, P301-75E, etc. from Asahi Kasei Corporation; Coronate® HX, HK, 2715, etc. from Tosoh Corporation; and Takenate® 500, 600, Stabio P-370N, etc. from Mitsui Chemicals, Inc. These may be used individually or in combination of two or more types.

[0064] The curing agent may be melamine resin, specifically guanamine, melamine, N-butylmelamine, N-phenylmelamine, N,N-diphenylmelamine, N,N-diallylmelamine, N,N',N''-triphenylmelamine, N,N',N''-trimethylolmelamine, benzoguanamine, 2,4-diamino-6-methyl-sym-triazine, 2,4-diamino-6-butyl-sym-triazine, 2,4-diamino-6-benzyloxide These are condensates of melamines such as cy-sym-triazine, 2,4-diamino-6-butoxy-sym-triazine, 2,4-diamino-6-cyclohexyl-sym-triazine, 2,4-diamino-6-chloro-sym-triazine, 2,4-diamino-6-mercapto-sym-triazine, and amelin (N,N,N',N'-tetracyanoethylbenzoguanamine), along with formaldehyde and alcohols (e.g., methanol). Commercially available products include Yuban® 20SE and 225 from Mitsui Chemicals, Inc., and Amidia® L-117-60, L-109-65, 47-508-60, L-118-60, G821-60, and J820-60 from DIC Corporation. These may be used individually or in combination of two or more.

[0065] Examples of curing catalysts include inorganic acids, organic acids, organometallic salts, and Lewis acids. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, nitrite, perchloric acid, and sulfamic acid. Examples of organic acids include formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, succinic acid, maleic acid, lactic acid, p-toluenesulfonic acid, and citric acid. Examples of organometallic salts include lithium hydroxide, sodium hydroxide, potassium hydroxide, n-hexylamine, dimethylamine, tributylamine, diazabicycloundecene, ethanolamine acetate, dimethylaniline formate, tetraethylammonium benzoate, sodium acetate, potassium acetate, sodium propionate, potassium propionate, sodium formate, potassium formate, benzoyltrimethylammonium acetate, tetramethylammonium acetate, and tin octoate. Examples of Lewis acids include tetraisopropyl titanate, tetrabutyl titanate, aluminum triisobutoxide, aluminum triisopropoxide, aluminum acetylacetonate, tin chloride (SnCl4), titanium chloride (TiCl4), and zinc chloride (ZnCl4). These may be used individually or in combination of two or more.

[0066] In the hydrophilic coating composition of the present invention, the content of the curing agent (C) is preferably 0.5 to 1.5, more preferably 0.8 to 1.3, and more preferably 0.9 to 1.2 in terms of the equivalent ratio of NCO / OH when the curing agent (C) is a polyisocyanate compound, and in the case of melamine resin, the main component ( The base represented by formula (1) The ratio of the total weight of the resin (A) containing hydroxyl groups and the binder resin (B) containing hydroxyl groups to the weight of the curing agent (C) is 50 / 50 to 90 / 10, preferably 60 / 40 to 80 / 20. If the content of curing agent (C) is too low or too high, curing will be insufficient.

[0067] [solvent] The hydrophilic coating composition of the present invention preferably contains a solvent. The solvent is The base represented by formula (1)The solvent is not particularly limited as long as it can dissolve or disperse the contained resin, binder resin, curing agent, and other additives as needed, does not react with each component, and can be easily removed in the drying step described later. Specific examples of solvents include methanol, ethanol, isopropanol, tetrahydrofuran, cyclohexanone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, diethylene glycol dimethyl ether, 1-methoxy-2-propanol, 1-methoxy-2-propyl acetate, toluene, ethyl acetate, water, etc. For example, when using polyisocyanate as a curing agent, it is preferable to use a solvent that does not react with the isocyanate group (e.g., a ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone). These may be used alone or in combination of two or more.

[0068] [Additives] The hydrophilic coating composition of the present invention may further contain, as needed, additives such as pigments, film-forming aids, fillers, toners, wetting agents, antistatic agents, pigment dispersants, plasticizers, antioxidants, flow control agents, viscosity modifiers, defoaming agents, ultraviolet absorbers, and dispersants.

[0069] The solid content concentration of the coating composition of the present invention is preferably 5 to 80% by weight, more preferably 10 to 60% by weight, even more preferably 20 to 50% by weight, and particularly preferably 30 to 40% by weight, from the viewpoint of coating properties and workability.

[0070] The hydrophilic coating composition of the present invention may be a one-component type, or it may be a type that requires mixing two or more components before use.

[0071] <coating film> By applying the hydrophilic coating composition of the present invention to a substrate and heating it, a coating film with excellent hardness, transparency, and initial and post-curing surface hydrophilicity can be formed on the substrate. In other words, the present invention also provides a coating film obtained by curing the above-mentioned hydrophilic coating composition. A colored layer may be provided as needed.

[0072] Examples of substrates include inorganic materials such as glass, metals, metal oxides, and silica, and organic materials such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), triacetylcellulose (TAC), polystyrene, polyethylene, polypropylene, vinyl chloride resin, urethane resin, epoxy resin, silicone resin, paper, and pulp. The surfaces of these substrates may be subjected to physical or chemical treatments such as plasma treatment, corona treatment, glow discharge treatment, flame treatment, primer coating treatment, and oxidation treatment with chemicals.

[0073] The method of coating the composition is not particularly limited, and known methods such as spray coating, wire bar coating, spin coating, and dip coating can be employed. Furthermore, coating can also be performed using continuous coating equipment such as die coaters, gravure coaters, and comma coaters.

[0074] After applying the composition to a substrate, a cured coating can be obtained by heating. The heating temperature is preferably 40 to 250°C, more preferably 50 to 200°C, even more preferably 60 to 150°C, and particularly preferably 70 to 120°C. The drying time is preferably 1 minute to 3 hours, more preferably 10 minutes to 2 hours, and even more preferably 20 minutes to 1 hour. Alternatively, pre-drying may be performed under the same conditions as above to remove the solvent from the composition.

[0075] The thickness of the coating film (dry film thickness) of the present invention is not particularly limited, but is preferably 2 to 200 μm, more preferably 10 to 100 μm, even more preferably 20 to 70 μm, and particularly preferably 30 to 60 μm.

[0076] <Physical properties of the coating film> The hydrophilic coating composition of the present invention requires that the dynamic glass transition temperature during curing, under conditions of a heating rate of 2°C / min and a frequency of 8Hz, be 80°C to 140°C, preferably 100°C to 130°C, and more preferably 110°C to 120°C. When the dynamic glass transition temperature (dynamic Tg) is within this temperature range, it is possible to suppress the penetration and adhesion of limescale to the coating film when limescale formation occurs. Therefore, even in situations where further dirt accumulates, it is possible to suppress the accumulation of dirt triggered by limescale.

[0077] The dynamic glass transition temperature (dynamic Tg) is determined by first applying a paint composition to a polypropylene test plate using an air spray to achieve a single-layer dry film thickness of 50 μm, and then heating and curing it at 100°C for 1 hour to form a coating film. Next, the coating film is peeled from the test plate and cut into 5 mm x 20 mm pieces to form test specimens. Dynamic viscoelasticity measurements are performed on these specimens using a forced-stretch vibration type viscoelasticity measuring device (Orientec's "Vibron"). Under conditions of a heating rate of 2°C / min and a measurement frequency of 8 Hz, the -20°C loss tangent tanδ is determined from the phase difference between the stress generated during heating and the vibration strain. The dynamic Tg of the coating film is defined as the temperature at which the loss tangent tanδ shows its maximum value. The "loss tangent tanδ" is a value measured in accordance with the tensile vibration-non-resonant method of JIS-K7244-4:1999.

[0078] <Application> By applying the hydrophilic coating composition of the present invention to various substrates such as glass, metal, and organic materials, hydrophilicity can be imparted to the substrate surface, and the adhesion of water stains can also be prevented. Therefore, surfaces such as automobile glass and mirrors can be easily made hydrophilic. Anti-fogging and self-cleaning functions can be imparted to mirrors, solar panel glass surfaces, and residential window glass, and the adhesion of water stains will also be reduced. Furthermore, it can prevent the adhesion of dust and dirt to optical films such as liquid crystal displays by preventing static electricity. In addition, since wettability is improved, it is also useful for inkjet image receiving layers and applications requiring recoating. As described above, a colored coating can also be formed on a coating film formed from the hydrophilic coating composition of the present invention. [Examples]

[0079] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto. In the examples, "parts" and "%" are based on mass unless otherwise specified.

[0080] Synthesis Example 1 ( The base represented by formula (1) Synthesis of resin (A) containing hydroxyl groups: For simplicity, this will be referred to as "ammonium base-containing resin" in the examples. In a flask equipped with a stirrer, dropping funnel, condenser, and thermometer, 50.00 parts by weight of 1-methoxy-2-propanol (hereinafter referred to as PM) and 50.00 parts by weight of methyl ethyl ketone (hereinafter referred to as MEK) were charged, and the temperature was raised to 70°C in a nitrogen atmosphere. Dimethylaminoethyl acrylate-polyoxybutylene / polyoxyethylene tridecyl ether sulfate ([C 13 H 27 -O-(BO)3-(EO)5-SO3]-[(CH3)2NH-(CH2)2-OCO-CH2=CH2] + A mixture of 55.00 parts by mass of (manufactured by Nippon Emulsifier Co., Ltd.), 17.16 parts by weight of methyl methacrylate (hereinafter referred to as MMA), 27.84 parts by weight of 2-hydroxyethyl methacrylate (hereinafter referred to as 2-HEMA), 1.00 part by weight of α-methylstyrene dimer (manufactured by NOF Corporation), and 3.00 parts by weight of 2,2'-azobis(2-methylbutyronitrile) (hereinafter referred to as AMBN) was added dropwise at a constant rate over 180 minutes using a dropping funnel. After aging at 70°C for 30 minutes, 1.00 part by weight of AMBN was added and aged at 70°C for 180 minutes. Subsequently, 50 parts by weight of MEK was added to dilute the mixture, and it was cooled to obtain ammonium salt-containing resin 1. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and was found to be 19,300. The non-volatile content measured at 120°C for 1 hour was 41.2%.

[0081] Synthesis Example 2 (Synthesis of Ammonium Base-Containing Resin 2 (Comparative Synthesis Example)) In a flask equipped with a stirrer, dropping funnel, condenser, and thermometer, 50.00 parts by weight of PM, 50.00 parts by weight of MEK, and 40.00 parts by weight of a 75% aqueous solution of dimethylaminopropylacrylamide-methyl chloride quaternary salt (hereinafter referred to as DMAPAA-Q) (manufactured by KJ Chemicals Co., Ltd.) were charged and heated to 70°C in a nitrogen atmosphere. Dimethylaminoethyl acrylate-polyoxybutylene / polyoxyethylene tridecyl ether sulfate ([C 13 H 27 -O-(BO)3-(EO)5-SO3]-[(CH3)2NH-(CH2)2-OCO-CH2=CH2] + A mixture of 25.00 parts by weight of (manufactured by Nippon Emulsifier Co., Ltd.), 10.00 parts by weight of MMA, 7.16 parts by weight of n-butyl acrylate (hereinafter referred to as NBA), 27.84 parts by weight of 2-HEMA, 1.00 part by weight of α-methylstyrene dimer, and 3.00 parts by weight of AMBN was added dropwise at a constant rate over 180 minutes using a dropping funnel. After aging at 70°C for 30 minutes, 1.00 part by weight of AMBN was added and aged at 70°C for 180 minutes. Subsequently, 40 parts by weight of MEK was added to dilute the mixture, and it was cooled to obtain ammonium salt-containing resin 2. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and was found to be 18,700. The non-volatile content measured at 120°C for 1 hour was 42.0%.

[0082] Synthesis Example 3 (Synthesis of Ammonium Base-Containing Resin 3 (Comparative Synthesis Example)) In a flask equipped with a stirrer, dropping funnel, condenser, and thermometer, 50.00 parts by weight of PM, 50.00 parts by weight of MEK, and 3.30 parts by weight of DMAPAA-Q were charged and heated to 70°C in a nitrogen atmosphere. A mixture of 17.16 parts by weight of NBA, 20.88 parts by weight of 2-HEMA, 1.00 part by weight of α-methylstyrene dimer, and 3.00 parts by weight of AMBN was added dropwise at a constant rate over 180 minutes using a dropping funnel. After aging at 70°C for 30 minutes, 1.00 part by weight of AMBN was added and aged at 70°C for another 180 minutes. Subsequently, 31.70 parts by weight of MEK was added to dilute the mixture, and it was cooled to obtain ammonium salt-containing resin 2. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and found to be 18,300. The non-volatile content measured at 120°C for 1 hour was 42.1%.

[0083] Synthesis Example 4 (Synthesis of Ammonium Base-Containing Resin 4 (Comparative Synthesis Example)) In a flask equipped with a stirrer, dropping funnel, condenser, and thermometer, 50.00 parts by weight of PM, 50.00 parts by weight of MEK, and 30.00 parts by weight of dimethylaminopropyl acrylamide (hereinafter referred to as DMAPAA) (manufactured by KJ Chemicals Co., Ltd.) were charged and the mixture was heated to 70°C in a nitrogen atmosphere. A mixture of 21.62 parts by weight of NBA, 20.88 parts by weight of 2-HEMA, 0.73 parts by weight of α-methylstyrene dimer, and 2.20 parts by weight of AMBN was added dropwise at a constant rate over 180 minutes using a dropping funnel. After aging at 70°C for 30 minutes, 1.00 part by weight of AMBN was added and the mixture was aged at 70°C for 180 minutes. Subsequently, 27.50 parts by weight of diethyl sulfuric acid (hereinafter referred to as DES) was added and the mixture was reacted further at 70°C for 6 hours. 50.00 parts by weight of MEK was added to dilute the mixture, and it was cooled to obtain ammonium salt-containing resin 2. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and found to be 22,300. The non-volatile content, measured at 120°C for 1 hour, was 40.1%.

[0084] Table 1 below shows the monomer composition and amount used, the type and amount of initiator used, the type and amount of solvent used, and the characteristic values ​​of the resin obtained by synthesis (hydroxyl value, weight-average molecular weight, and non-volatile content (%)) of the ammonium base-containing resin synthesized in Synthesis Examples 1 to 4.

[0085] [Table 1]

[0086] Synthesis Example 5 (Synthesis of Binder Resin 1 containing hydroxyl groups: For simplicity, this will be referred to simply as "binder resin" in the examples.) 90.00 parts by weight of 1-methoxy-2-propanol (hereinafter referred to as PM) was charged into a flask equipped with a stirrer, dropping funnel, condenser, and thermometer, and the mixture was subsequently heated to 120°C under reflux in a condenser in a nitrogen atmosphere. After heating, a monomer mixture of 0.77 parts by weight of methacrylic acid (hereinafter, MAA), 27.84 parts by weight of 2-hydroxyethyl methacrylate (hereinafter, 2-HEMA), 22.76 parts by weight of methyl methacrylate (hereinafter, MMA), 22.94 parts by weight of isobornyl methacrylate (hereinafter, IBOMA), 20.00 parts by weight of styrene (hereinafter, ST), and 5.69 parts by weight of n-butyl acrylate (hereinafter, NBA), along with 1.80 parts by weight of t-butyl peroxy-2-ethylhexanate (manufactured by Kayaku Nurion, hereinafter, Trigonox 21S), was dissolved in 8.20 parts by weight of PM. This solution was added dropwise at a constant rate over 180 minutes from separate dropping funnels. After aging for 30 minutes, a solution of 0.20 parts by weight of Trigonox 21S dissolved in 1.80 parts by weight of PM was added dropwise at a constant rate over 30 minutes, and the mixture was aged for 60 minutes. Subsequently, the mixture was cooled to obtain a hydroxyl group-containing copolymer solution. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and was found to be 21,200. The non-volatile content, measured at 120°C for 1 hour, was 51.2%.

[0087] Synthesis Example 6 (Synthesis of Binder Resin 2) A hydroxyl group-containing copolymer solution was obtained in the same manner as in Synthesis Example 1, except that the monomer mixture in Synthesis Example 5 was changed to 0.77 parts by weight of MAA, 3.20 parts by weight of 2-HEMA, 40.31 parts by weight of MMA, 31.22 parts by weight of ST, and 4.50 parts by weight of NBA. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and was found to be 20,400. The non-volatile content measured at 120°C for 1 hour was 52.5%.

[0088] Synthesis Example 7 (Synthesis of Binder Resin 3) A hydroxyl group-containing copolymer solution was obtained in the same manner as in Synthesis Example 1, except that the monomer mixture in Synthesis Example 5 was changed to 2.30 parts by weight of MAA, 27.84 parts by weight of 2-HEMA, 60.35 parts by weight of MMA, 1.13 parts by weight of NBA, and 8.38 parts by weight of n-butyl methacrylate (hereinafter referred to as NBMA). The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and was found to be 21,900. The non-volatile content measured at 120°C for 1 hour was 51.0%.

[0089] Synthesis Example 8 (Synthesis of Binder Resin 4) A hydroxyl group-containing copolymer solution was obtained in the same manner as in Synthesis Example 1, except that the monomer mixture in Synthesis Example 5 was changed to 0.77 parts by weight of MAA, 27.84 parts by weight of 2-HEMA, 40.52 parts by weight of MMA, 29.37 parts by weight of ST, and 1.50 parts by weight of NBA. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and was found to be 19,900. The non-volatile content measured at 120°C for 1 hour was 51.6%.

[0090] Synthesis Example 9 (Synthesis of Binder Resin 5) A hydroxyl group-containing copolymer solution was obtained in the same manner as in Synthesis Example 1, except that in Synthesis Example 5, the monomer mixture was changed to 0.77 parts by weight of MAA, 27.84 parts by weight of 2-HEMA, 40.52 parts by weight of MMA, 9.37 parts by weight of ST, and 1.50 parts by weight of NBA. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and was found to be 21,900. The non-volatile content measured at 120°C for 1 hour was 51.6%.

[0091] Synthesis Example 10 (Synthesis of Binder Resin 6 (Comparative Synthesis Example)) A hydroxyl group-containing copolymer solution was obtained in the same manner as in Synthesis Example 1, except that the monomer mixture was changed to 0.77 parts by weight of MAA, 27.84 parts by weight of 2-HEMA, 8.18 parts by weight of MMA, 29.46 parts by weight of ST, and 33.75 parts by weight of NBA. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and was found to be 20400. The non-volatile content measured at 120°C for 1 hour was 51.2%.

[0092] Synthesis Example 11 (Synthesis of Binder Resin 7 (Comparative Synthesis Example)) A hydroxyl group-containing copolymer solution was obtained in the same manner as in Synthesis Example 1, except that the monomer mixture was changed to 0.77 parts by weight of MAA, 34.80 parts by weight of 2-HEMA, 28.18 parts by weight of MMA, 34.72 parts by weight of IBOMA, and 1.53 parts by weight of NBA. The weight-average molecular weight of the obtained copolymer was measured by gel permeation chromatography (GPC) (standard substance: polystyrene) and was found to be 19400. The non-volatile content measured at 120°C for 1 hour was 51.3%.

[0093] Table 2 below shows the monomer composition and amount used for the binder resin (B) synthesized in Synthesis Examples 5-11, the type and amount of initiator used, and the characteristic values ​​of the resin (B) obtained by synthesis (SP value, hydroxyl value, acid value, glass transition temperature (Tg [°C]), weight-average molecular weight, and non-volatile content (%)).

[0094] [Table 2]

[0095] The glass transition temperature (Tg) and SP value were calculated from the Tg and SP values ​​of each monomer. The Tg and SP values ​​of the monomers used in binder resin (B) are shown in Table 3 below.

[0096] [Table 3]

[0097] Example 1 Ammonium-containing resin 1 (solids content 41.1% by weight) prepared in Synthesis Example 1 and binder resin 1 (solids content 51.2% by weight) prepared in Synthesis Example 5 were mixed in a ratio of 6.0 / 94.0 for the main component. Stabio D-370N (manufactured by Mitsui Chemicals, Inc., solids content 100%) was added as a curing agent (C) in a ratio of NCO / OH = 1.0, and PM was used as a diluent thinner to adjust the non-volatile content to 35% by weight. The obtained composition was applied to a polymer alloy of PC (polycarbonate) and PBT (polybutylene terephthalate) using a spray gun, set for 10 minutes, and then baked in a hot air dryer at 100°C for 1 hour to produce a coating film with a thickness of 30 μm.

[0098] The obtained coating film was evaluated for its initial appearance, hydrophilicity (water contact angle [°]), water stain removal properties, and impact resistance as described below. The results are shown in the initial section of the Results column in Table 4. In addition, the coated board was immersed in 70°C hot water for 500 hours, and after removal, the water was thoroughly wiped off and left at room temperature for 1 hour. The appearance, hydrophilicity, and water stain removal properties (properties after water resistance) were evaluated in the same manner. The results are listed in the After Water Resistance section of the Results column in Table 4. Table 4 lists the compounding amounts for each example, the characteristic values ​​of the resin used in each example (specifically, the SP value of the binder resin (B)), and the dynamic Tg value of the coating film.

[0099] [Initial appearance] The coating was visually evaluated. ○: No change from the initial state. ×: Out of focus

[0100] [Hydrophilicity] Hydrophilicity was determined by dropping 0.1 ml of pure water onto the painted surface and measuring the water contact angle after 1 second. ◎ :≦55° ○ :>55° ≤60° ○△:>60° ≤65° △ :>65° ≦70° × :>70°

[0101] [Scale removability] The painted surface was sprayed with Evian (manufactured by Danone) and dried in a 50°C hot air dryer for 1 hour. Afterwards, it was lightly washed five times back and forth with tap water using a Scotch-Brite (manufactured by 3M) urethane sponge, and the amount of remaining limescale was visually inspected. ○: No residue at all ○△: If you look closely, you can see that a small amount remains. △: A thin ring-shaped layer remains. △×: Clearly remains in a ring shape. ×: It remains clearly visible throughout.

[0102] [Impact Resistance] Using a DuPont drop impact tester, under conditions of 23±2°C and 50±5% humidity (relative humidity), a hemispherical firing pin with a radius of 6.35 mm was placed on the painted surface, and a 500 g weight was dropped from a height of 50 cm to check for cracking of the paint film. ○: No cracks ×: Cracks occurred

[0103] Characteristics after water resistance (after water resistance testing) [Appearance after water resistance] ○: No change ×: Water absorption and whitening occur The hydrophilicity (water contact angle [°]) and limescale removal properties after water resistance testing are the same as before the water resistance test (initial stage).

[0104] Examples 2-5 The composition was prepared in the same manner as in Example 1, except that the formulation was as shown in Table 4, and a coating film was prepared. Measurements were performed in the same manner as in Example 1, and the results are shown in Table 4.

[0105] [Table 4]

[0106] Furthermore, the dynamic Tg of the coating film was measured as follows. [Coating film dynamic Tg] The paint obtained in the example was applied to a PP (polypropylene) substrate, and after baking at 100°C for 1 hour, the cured coating was peeled off to prepare a 50μ film. The viscoelasticity of the prepared film was measured using Rheogel E-4000 (manufactured by UBM Co., Ltd.), and the temperature at which the value of tanδ was maximum was defined as the dynamic Tg.

[0107] Comparative Example 1 The ammonium-containing resin 2 (50.2% by weight solids) shown in Synthesis Example 2 and the binder resin 2 (52.5% by weight solids) prepared in Synthesis Example 6 were mixed in a ratio of 6.0 / 94.0 to form the main component. Stabio D-370N (manufactured by Mitsui Chemicals, Inc., 100% solids) was added as a curing agent (C) in a ratio of NCO / OH = 1.0, and PM was used as a diluent thinner to adjust the non-volatile content to 35% by weight. The resulting composition was applied to a PC / PBT substrate using a spray gun, set for 10 minutes, and then baked in a 100°C hot air dryer for 1 hour to produce a coating film with a thickness of 30 μm.

[0108] The obtained coating films were evaluated for appearance, hydrophilicity (water contact angle [°]), limescale removal properties, and impact resistance in the same manner as in the examples. The results are shown at the beginning of the "Results" column in Table 5. In addition, the coated panels were immersed in 70°C hot water for 500 hours, and after removal, the water was thoroughly wiped off and left at room temperature for 1 hour. The appearance, hydrophilicity, and limescale removal properties (properties after water resistance) were evaluated in the same manner. The results are listed in the "After Water Resistance" column of the "Results" column in Table 5. Table 5 lists the compounding amounts for each example, the characteristic values ​​of the resins used in each example (specifically, the SP value of the binder resin (B)), and the dynamic Tg value of the coating film.

[0109] Comparative Examples 2-7 In Comparative Example 1, the composition was prepared in the same manner as in Example 1, except that the formulation was as shown in Table 5, and a coating film was prepared. Measurements were performed in the same manner as in Comparative Example 1, and the results are shown in Table 5.

[0110] [Table 5]

[0111] In the above examples and comparative examples, Examples 1 to 5 satisfy the requirements of the present invention, and therefore exhibit excellent appearance, hydrophilicity, limescale removal properties, and initial impact resistance both immediately after painting (initial) and after the water resistance test (post-water resistance). In Comparative Example 1, the ammonium salt-containing resin is quaternary ammonium salt-containing resin 2, and this resin contains, in addition to the quaternary ammonium base specified in the present invention, another quaternary ammonium base (specifically, a methyl chloride quaternary base of a dimethylaminopropylamide group), so limescale removal properties are poor. In Comparative Example 2, the ammonium salt-containing resin is ammonium salt-containing resin 3, and this resin does not contain the quaternary ammonium base specified in the present invention, but only has a methyl chloride quaternary base of a dimethylaminopropylamide group, so limescale removal properties are very poor. In Comparative Example 3, the ammonium salt-containing resin is ammonium salt-containing resin 4, and this resin does not contain the quaternary ammonium base specified in the present invention, but only has a base that has been quaternized with diethyl sulfate of a dimethylaminopropylamide group, so limescale removal properties are very poor. Comparative Example 4 is an example where a small amount of ammonium salt-containing resin 3 was used, but the limescale removal performance was still reduced. Comparative Example 5 is an example where a small amount of ammonium salt-containing resin 3 used in Comparative Example 1 was added to ammonium salt-containing resin 1 used in the example, but there was a tendency for inferior limescale removal performance. Comparative Examples 6 and 7 are examples where the dynamic Tg of the coating film falls outside the useful range of the present invention (80°C to 140°C). In Comparative Example 6, the dynamic Tg is lower than the lower limit, and the limescale removal performance is poor. In Comparative Example 7, the dynamic Tg is higher than the upper limit, and there is a tendency for good limescale removal performance, but the impact resistance in the initial stages of coating is poor, making it unusable.

Claims

1. A hydrophilic coating composition comprising a resin (A) containing a group represented by formula (1) and a hydroxyl group, a binder resin (B) containing a hydroxyl group, and a curing agent (C), Formula (1): 【Chemistry 1】 (In formula (1), Ra １ is a hydrogen atom, a methyl group, or an ethyl group, Ya ー The formula is as follows (1'): 【Chemistry 2】 (In formula (1') above, R' is an unsubstituted C12-C14 linear or branched alkyl group, A' is a C2-C4 linear or branched alkylene group, and m is the average number of moles of A'O added, an integer from 2 to 50.) This is an anion represented by [the formula shown]. It is a base represented by, The anion in formula (1) above is Ya ー That is all, The aforementioned resin (A) (i) A polymerization product of only two types of (meth)acrylates: (i) a salt of dimethylaminoethyl (meth)acrylate or diethylaminoethyl (meth)acrylate with an unsubstituted linear or branched alkyl ether sulfate of polyoxy(C2-C4) linear or branched alkylene (C12-C14); and (ii) a (meth)acrylate containing a hydroxyl group. (i) A polymerization reaction product of only three types: (i) a salt of dimethylaminoethyl (meth)acrylate or diethylaminoethyl (meth)acrylate with a polyoxy(C2-C4) linear or branched alkylene (C12-C14) unsubstituted linear or branched alkyl ether sulfate; (ii) a (meth)acrylate containing a hydroxyl group; and (iii) an alkyl (meth)acrylate. However, (iii) alkyl (meth)acrylate is selected from methyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or a combination thereof. The dynamic glass transition temperature of the cured coating is 80°C to 140°C. A hydrophilic coating composition characterized by the following features.

2. The hydrophilic coating composition according to claim 1, wherein the curing agent (C) is an isocyanate compound or a melamine resin.

3. A cured coating film obtained by curing the hydrophilic coating composition according to claim 1 or 2.

4. A painted article having a cured coating film of the hydrophilic coating composition according to claim 1 or 2 on its surface.

Images