Coating composition and coated article

Abstract

Provided are: a coating composition which has excellent film-forming properties in a low-temperature environment and is capable of forming a coating film having excellent adhesion to a concrete substrate; and a coated article. The coating composition according to the present invention comprises a fluorine-containing polymer, a (meth) acrylic polymer and water, the particle size of the (meth) acrylic polymer in the coating composition being 150 nm or more, the glass transition temperature of the (meth) acrylic polymer being 40 DEG C or less, the minimum film-forming temperatures of the fluorine-containing polymer and the (meth) acrylic polymer being 50 DEG C or less, and the minimum film-forming temperatures of the fluorine-containing polymer and the (meth) acrylic polymer being 50 DEG C or less. The absolute value of the difference between the minimum film-forming temperature of the fluorine-containing polymer and the minimum film-forming temperature of the (meth) acrylic polymer is 20 DEG C or less, and the absolute value of the difference between the particle diameter of the fluorine-containing polymer and the particle diameter of the (meth) acrylic polymer is 35 nm or less. The minimum film formation temperature of the fluorine-containing polymer may be 60 DEG C or less.

Description

Technical Field

[0001] The present invention relates to coating compositions and coated articles. Background Art

[0002] A coating composition containing a fluorine-containing polymer can form a coating film having excellent weather resistance. As such a coating composition, Patent Document 1 discloses a coating containing a fluorine-containing polymer and a (meth)acrylic polymer.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2020 / 090749 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] Coating compositions containing fluorine-containing polymers are used in various applications and environments, and for example, are sometimes used for forming coating films in low-temperature environments.

[0008] Furthermore, a coating film obtained using a coating composition containing a fluorinated polymer is sometimes disposed on a concrete substrate in order to impart weather resistance, water resistance, etc. to the substrate made of concrete (hereinafter also referred to as a concrete substrate).

[0009] The present inventors evaluated the coating composition comprising a fluorinated polymer and a (meth)acrylic polymer described in Patent Document 1 and found that there is room for improvement in at least one of film-forming properties in a low-temperature environment and adhesion of the formed coating film to a concrete substrate.

[0010] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a coating composition and a coated article which are excellent in film-forming properties in a low-temperature environment and can form a coating film having excellent adhesion to a concrete substrate.

[0011] Solutions for solving problems

[0012] The present inventors have conducted intensive studies on the above-mentioned problems and have found that the desired effects can be obtained if the coating composition comprises a fluorinated polymer, a (meth)acrylic polymer and water, wherein the particle size of the (meth)acrylic polymer is 150 nm or more, the glass transition temperature of the (meth)acrylic polymer is 40° C. or less, the minimum film-forming temperature of the fluorinated polymer and the (meth)acrylic polymer is 50° C. or less, the absolute value of the difference in the minimum film-forming temperature between the fluorinated polymer and the (meth)acrylic polymer is 20° C. or less, and the absolute value of the difference in the particle size between the fluorinated polymer and the (meth)acrylic polymer is 35 nm or less, thereby completing the present invention.

[0013] Furthermore, the present inventors have found that, in the above-mentioned coating composition, even if the minimum film-forming temperature of the fluorinated polymer is 60° C. or lower, the desired effect can be obtained.

[0014] That is, the inventors have found that the above-mentioned technical problems can be solved by the following configuration.

[0015] [1] A coating composition comprising a fluorine-containing polymer, a (meth)acrylic polymer and water,

[0016] The particle size of the (meth)acrylic polymer in the coating composition is 150 nm or more.

[0017] The glass transition temperature of the (meth)acrylic polymer is 40° C. or less.

[0018] The minimum film-forming temperature of the fluorine-containing polymer and the (meth)acrylic polymer is 50° C. or less.

[0019] The absolute value of the difference between the minimum film-forming temperature of the fluorine-containing polymer and the minimum film-forming temperature of the (meth)acrylic polymer is 20° C. or less,

[0020] The absolute value of the difference between the particle size of the fluorine-containing polymer and the particle size of the (meth)acrylic polymer is 35 nm or less.

[0021] [2] The coating composition according to [1], wherein the fluorine-containing polymer comprises a unit based on CF2=CFCl.

[0022] [3] The coating composition according to [1] or [2], which has a viscosity at 25°C of 200 mPa·s or more.

[0023] [4] The coating composition according to any one of [1] to [3], further comprising a film-forming aid.

[0024] [5] The coating composition according to any one of [1] to [4], wherein the mass ratio of the content of the (meth)acrylic polymer to the content of the fluorinated polymer is 10 / 90 to 60 / 40.

[0025] [6] A coated article comprising a substrate and a coating film disposed on the substrate, wherein the coating film is formed using the coating composition according to any one of [1] to [5].

[0026] The material of the substrate is concrete.

[0027] [7] A coating composition comprising a fluorine-containing polymer, a (meth)acrylic polymer and water, wherein the particle size of the (meth)acrylic polymer in the coating composition is 150 nm or more, the glass transition temperature of the (meth)acrylic polymer is 40°C or less, the minimum film-forming temperature of the fluorine-containing polymer is 60°C or less, the minimum film-forming temperature of the (meth)acrylic polymer is 50°C or less, the absolute value of the difference between the minimum film-forming temperature of the fluorine-containing polymer and the minimum film-forming temperature of the (meth)acrylic polymer is 20°C or less, and the absolute value of the difference between the particle size of the fluorine-containing polymer and the particle size of the (meth)acrylic polymer is 35 nm or less.

[0028] [8] The coating composition according to [7], wherein the fluorine-containing polymer comprises a unit based on CF2=CFCl.

[0029] [9] The coating composition according to [7] or [8], which has a viscosity at 25°C of 200 mPa·s or more.

[0030]

[10] The coating composition according to any one of [7] to [9], further comprising a film-forming aid.

[0031]

[11] The coating composition according to any one of [7] to

[10] , wherein the mass ratio of the content of the (meth)acrylic polymer to the content of the fluorinated polymer is 10 / 90 to 60 / 40.

[0032]

[12] A coated article comprising a substrate and a coating film disposed on the substrate, wherein the coating film is formed using the coating composition according to any one of [7] to

[11] ,

[0033] The material of the substrate is concrete.

[0034] Effects of the Invention

[0035] According to the present invention, it is possible to provide a coating composition and a coated article which are excellent in film-forming properties in a low-temperature environment and can form a coating film having excellent adhesion to a concrete substrate. DETAILED DESCRIPTION

[0036] The meanings of the terms used in the present invention are as follows.

[0037] The numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit.

[0038] Unit refers to the general term for the atomic group based on one molecule of the monomer directly formed by polymerization of the monomer and the atomic group obtained by chemical conversion of a part of the atomic group. The content (mol %) of each unit relative to all units contained in the polymer can be determined by the input amount of the components used in the production of the polymer.

[0039] “(Meth)acrylic acid” is a general term for “acrylic acid” and “methacrylic acid”, and “(meth)acrylate” is a general term for “acrylate” and “methacrylate”.

[0040] The hydrolyzable silyl group refers to a group that can undergo a hydrolysis reaction to form a silanol group.

[0041] The acid value and the hydroxyl value are values ​​measured by the method according to JIS K 0070-3 (1992), respectively.

[0042] The glass transition temperature (Tg) is the midpoint glass transition temperature of a polymer as measured by differential scanning calorimetry (DSC).

[0043] The minimum film forming temperature (MFT) is the lowest temperature at which a uniform coating film without cracks can be formed when a polymer is dried, and can be measured using, for example, a film forming temperature measuring apparatus IMC-1535 (manufactured by Imoto Seisakusho Co., Ltd.).

[0044] The number average molecular weight (Mn) is a value measured by gel permeation chromatography using polystyrene as a standard substance.

[0045] The coating composition of the present invention (hereinafter also referred to as the present coating) comprises a fluorine-containing polymer, a (meth) acrylic polymer and water, wherein the particle size of the (meth) acrylic polymer in the present coating is 150 nm or more, the Tg of the (meth) acrylic polymer is 40° C. or less, the MFT of the fluorine-containing polymer and the (meth) acrylic polymer are both 50° C. or less, the absolute value of the difference between the MFT of the fluorine-containing polymer and the MFT of the (meth) acrylic polymer is 20° C. or less, and the absolute value of the difference between the particle size of the fluorine-containing polymer and the particle size of the (meth) acrylic polymer is 35 nm or less. It should be noted that the MFT of the fluorine-containing polymer may be 60° C. or less.

[0046] It is believed that in the present coating, by making the MFT of the fluorinated polymer and the (meth) acrylic polymer below 50°C, the absolute value of the difference between the MFT of the fluorinated polymer and the (meth) acrylic polymer below 20°C, the absolute value of the difference between the particle size of the fluorinated polymer and the (meth) acrylic polymer below 35nm, and the particle size of the (meth) acrylic polymer above 150nm, the effects generated by satisfying these various physical properties function synergistically, and the film-forming property in a low temperature environment is improved. It should be noted that the MFT of the above-mentioned fluorinated polymer can be below 60°C.

[0047] In addition, it is considered that the use of a (meth)acrylic polymer having a Tg and a particle size satisfying the above values ​​improves the adhesion to the concrete base material.

[0048] The fluorine-containing polymer contains a unit having a fluorine atom. As the unit having a fluorine atom, a unit based on a fluoroolefin (hereinafter also referred to as a unit F1) is preferred.

[0049] The fluoroolefin is an olefin in which one or more hydrogen atoms are substituted with fluorine atoms. One or more hydrogen atoms of the fluoroolefin that are not substituted with fluorine atoms may be substituted with chlorine atoms.

[0050] Specific examples of fluoroolefins include CF2=CF2, CF2=CFCl, CF2=CHF, CH2=CF2, CF2=CFCF3, CF2=CHCF3, CF3CH=CHF, CF3CF=CH2, CH2=CX f1 (CF2) n1 Y f1 (Where X f1 and Y f1 The monomer represented by ) is preferably CF2=CF2, CH2=CF2, CF2=CFCl, CF3CH=CHF, CF3CF=CH2, more preferably CF2=CF2 or CF2=CFCl, and further preferably CF2=CFCl from the viewpoint of excellent weather resistance of the present coating film.

[0051] Two or more fluoroolefins may be used in combination.

[0052] From the viewpoint of weather resistance of the present coating film, the content of the units F1 is preferably from 20 to 100 mol %, more preferably from 30 to 70 mol %, further preferably from 40 to 60 mol %, based on all units contained in the fluorinated polymer.

[0053] The fluorine-containing polymer may contain a unit having at least one of an aliphatic hydrocarbon ring and an aromatic ring (hereinafter also referred to as unit F2). The unit F2 is preferably a unit based on a monomer having at least one of an aliphatic hydrocarbon ring and an aromatic ring (hereinafter also referred to as monomer f2).

[0054] The unit F2 is preferably a unit having no fluorine atom.

[0055] Specific examples of aliphatic hydrocarbon rings include monocyclic aliphatic hydrocarbons such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane, polycyclic aliphatic hydrocarbons such as 4-cyclohexylcyclohexane and decalin, norbornane, aliphatic hydrocarbons having a bridged ring structure such as 1-adamantyl, and aliphatic hydrocarbons having a spiro ring structure such as spiro[3.4]octyl.

[0056] Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, toluene, xylene, naphthalene, phenol, and benzoic acid, and aromatic heterocyclic rings such as furan, thiophene, pyrrole, and pyridine.

[0057] As the monomer f2, vinyl ether, vinyl ester, allyl ether, allyl ester, and (meth)acrylate having at least one of an aliphatic hydrocarbon ring and an aromatic ring are preferred.

[0058] Specific examples of monomer f2 include cyclohexyl (meth)acrylate, cyclohexyl vinyl ether, cyclohexanedimethanol monovinyl ether (CH2=CHO-CH2-cycloC6H 10 -CH2OH), CH2=CHCH2O-CH2-cycloC6H 10 -CH2OH, CH2=CHO-CH2-cycloC6H 10 -CH2-(OCH2CH2) 15 OH, vinyl benzoate, vinyl tert-butyl benzoate, benzyl (meth)acrylate.

[0059] It should be noted that "-cycloC6H 10 -" indicates cyclohexylene, "-cycloC6H 10 -" is usually a 1,4-bonding site.

[0060] Two or more monomers f2 may be used in combination.

[0061] When the fluorinated polymer contains the unit F2, the content of the unit F2 is preferably from 0.1 to 15 mol %, more preferably from 0.5 to 10 mol %, further preferably from 1 to 5 mol %, based on all the units contained in the fluorinated polymer.

[0062] The fluorine-containing polymer may include a unit having neither an aliphatic hydrocarbon ring nor an aromatic ring and having at least one of a hydroxyl group and a carboxyl group (hereinafter also referred to as a unit F3). The unit F3 is preferably a unit having no fluorine atom.

[0063] Unit F3 may be a unit based on a monomer having at least one of a hydroxyl group and a carboxyl group (hereinafter also referred to as monomer f3), or may be a unit obtained by converting a unit having a group that can be converted into a hydroxyl group or a carboxyl group in a fluoropolymer containing a unit having a group that can be converted into a hydroxyl group or a carboxyl group. As such a unit, a unit obtained by reacting a polycarboxylic acid, an acid anhydride thereof, etc. with a fluoropolymer containing a unit having a hydroxyl group to convert a part or all of the hydroxyl groups into carboxyl groups may be cited.

[0064] Examples of the monomer f3 having a hydroxyl group include vinyl ethers, vinyl esters, allyl ethers, allyl esters, (meth)acrylates, and allyl alcohols having a hydroxyl group. From the viewpoint of weather resistance of the present coating film, the monomer f3 having a hydroxyl group is preferably vinyl ether.

[0065] Specific examples of the monomer f3 having a hydroxyl group include CH2=CHOCH2CH2OH, CH2=CHCH2OCH2CH2OH, CH2=CHOCH2CH2CH2CH2OH, and CH2=CHCH2OCH2CH2CH2CH2OH. From the viewpoint of copolymerizability with fluoroolefins, CH2=CHCH2OCH2CH2OH or CH2=CHOCH2CH2CH2CH2OH is preferred.

[0066] Examples of the monomer f3 having a carboxyl group include unsaturated carboxylic acid, (meth)acrylic acid, and monomers obtained by reacting a carboxylic anhydride with a hydroxy group of the above-mentioned monomer having a hydroxy group.

[0067] Specific examples of the monomer f3 having a carboxyl group include CH2=CHCOOH, CH(CH3)=CHCOOH, CH2=C(CH3)COOH, HOOCCH=CHCOOH, CH2=CH(CH2) n11 COOH (where n11 represents an integer from 1 to 10), CH2=CHO(CH2) n12 OC(O)CH2CH2COOH (wherein n12 represents an integer of 1 to 10). From the viewpoint of copolymerizability with fluoroolefins, CH2═CH(CH2) is preferred. n11 COOH or CH2=CHO(CH2) n12 OC(O)CH2CH2COOH.

[0068] Two or more monomers f3 may be used in combination.

[0069] When the fluorinated polymer contains the unit F3, the content of the unit F3 is preferably more than 0 mol % and 30 mol % or less, more preferably 1 to 15 mol %, further preferably 1.5 to 5 mol %.

[0070] The fluorine-containing polymer may include a unit (hereinafter also referred to as unit F4) based on a monomer (hereinafter also referred to as monomer f4) having neither an aliphatic hydrocarbon ring nor an aromatic ring and neither a hydroxyl group nor a carboxyl group. Unit F4 is preferably a unit having no fluorine atom.

[0071] Unit F4 may have a crosslinkable group other than a hydroxyl group and a carboxyl group. Specific examples of such a group include an amino group, an epoxy group, an oxetanyl group, and a hydrolyzable silyl group.

[0072] Monomer f4 may be one or more selected from the group consisting of olefins, vinyl ethers, vinyl esters, allyl ethers, allyl esters and (meth)acrylates. From the viewpoint of copolymerizability with fluoroolefins and weather resistance of the fluorinated polymer, at least one of vinyl ethers and vinyl esters is preferred, and vinyl ether is particularly preferred.

[0073] Specific examples of monomer f4 include ethylene, propylene, 1-butene, ethyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, vinyl acetate, vinyl pivalate, vinyl neononanoate (manufactured by HEXION, trade name "VeoVa9"), vinyl neodecanoate (manufactured by HEXION, trade name "VeoVa10"), and tert-butyl (meth)acrylate.

[0074] Two or more monomers f4 may be used in combination.

[0075] When the fluorinated polymer contains the unit F4, the content of the unit F4 is preferably 5 to 60 mol %, more preferably 10 to 50 mol %, further preferably 45 to 50 mol %, based on all the units contained in the fluorinated polymer.

[0076] The fluorine-containing polymer is preferably dispersed in water. In this case, the fluorine-containing polymer is dispersed in the coating in the form of fluorine-containing polymer particles.

[0077] The particle size of the fluorine-containing polymer in the present coating is preferably 130 to 190 nm, more preferably 135 to 180 nm, and still more preferably 140 to 170 nm. When the particle size of the fluorine-containing polymer is 130 nm or more, the followability to the concrete substrate becomes good. When the particle size of the fluorine-containing polymer is 190 nm or less, the adhesion to the concrete substrate is more excellent.

[0078] The particle size of the fluorinated polymer in the present coating material is measured in the following manner.

[0079] First, 10 g of the present coating material was dried at 60° C. for 24 hours to obtain a coating film having a thickness of 50 μm. The obtained coating film was cut in the thickness direction using a microtome to expose a cross section of the coating film.

[0080] Next, a scanning electron microscope (SEM-EDS) equipped with an energy dispersive X-ray detector is used to obtain an observation image of the coating cross section. Then, the particles contained in the obtained observation image are subjected to elemental analysis to determine the particles of the fluoropolymer and to determine the particle size (equivalent circle diameter) of the particles of the fluoropolymer. The particle sizes of 100 different fluoropolymers are measured, and the value obtained by arithmetic averaging is used as the particle size of the fluoropolymer in this coating.

[0081] Here, when the number of fluorine-containing polymer particles contained in one observation image is 100 or less, the above analysis is performed using cross sections at different positions of the sample until the number of fluorine-containing polymer particles reaches 100.

[0082] As SEM-EDX, JSM-IT700HR (manufactured by JEOL Ltd.) can be used.

[0083] The Tg of the fluorinated polymer is preferably 0°C or higher, more preferably 10°C or higher.

[0084] The Tg of the fluorinated polymer is preferably 80°C or lower, more preferably 30°C or lower.

[0085] The MFT of the fluorinated polymer is 50° C. or lower, and preferably 45° C. or lower from the viewpoint of better film-forming properties at low temperatures.

[0086] In addition, from the viewpoint of film-forming property, the MFT of the fluorinated polymer may be 60° C. or lower.

[0087] In addition, the lower limit of the MFT of the fluorinated polymer is usually 0°C or higher.

[0088] The Mn of the fluorinated polymer is preferably 1,000 to 1,000,000.

[0089] When the fluorinated polymer has a hydroxyl value, the hydroxyl value of the fluorinated polymer is preferably from 1 to 80 mgKOH / g, particularly preferably from 10 to 30 mgKOH / g.

[0090] When the fluorinated polymer has an acid value, the acid value of the fluorinated polymer is preferably from 1 to 80 mgKOH / g, particularly preferably from 10 to 30 mgKOH / g.

[0091] The fluorinated polymer may have only one of an acid value and a hydroxyl value, or may have both.

[0092] The fluorinated polymers may be used in combination of two or more kinds.

[0093] The content of the fluorine-containing polymer is preferably 10 to 90% by mass, more preferably 15 to 60% by mass, and even more preferably 20 to 40% by mass relative to the total mass of the coating material. When the content of the fluorine-containing polymer is 10% by mass or more, the coating film has excellent weather resistance.

[0094] The fluorinated polymer can be obtained by copolymerizing each monomer in the presence of a solvent and a free radical polymerization initiator. Specific examples of polymerization methods include emulsion polymerization, suspension polymerization, and solution polymerization, preferably emulsion polymerization. In addition, after solution polymerization is performed to obtain a polymer, solvent replacement is performed to disperse it in water. The polymerization temperature and polymerization time can be appropriately selected.

[0095] During the polymerization, a surfactant, a radical polymerization initiator, a chain transfer agent, a chelating agent, a pH adjuster, and the like may be added.

[0096] The (meth)acrylic polymer is a polymer containing a (meth)acrylic acid ester-based unit.

[0097] The (meth)acrylic polymer may contain only units based on (meth)acrylic acid ester, or may contain units based on a monomer other than (meth)acrylic acid ester, such as styrene and (meth)acrylic acid.

[0098] The (meth)acrylic polymer may have a crosslinkable group such as a carboxyl group, a hydroxyl group, an amino group, an epoxy group, an oxetanyl group, or a hydrolyzable silyl group.

[0099] The (meth)acrylic polymer may be a silicone-modified (meth)acrylic polymer.

[0100] The (meth)acrylic polymer may have a hindered amine group.

[0101] Specific examples of (meth)acrylates include alkyl (meth)acrylates (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), hydroxyalkyl (meth)acrylates (e.g., hydroxyethyl (meth)acrylate, etc.), and glycidyl (meth)acrylate.

[0102] As the (meth)acrylic polymer, commercially available products can be used. Specific examples thereof include Udouble (registered trademark) E-771SI (manufactured by NIPPON SHOKUBAI CO., LTD.), Polyzol (registered trademark) AP-3900, AP-4710N, AP-4765N (manufactured by Showa Denko K.K.), Acronal 7067, YJ3031D AP (manufactured by BASF), ELASTENE 1500, 2471 (manufactured by Dow), and ZH140 (manufactured by Aqua Union).

[0103] The (meth)acrylic polymer may be dispersed in the present coating material in the form of (meth)acrylic polymer particles.

[0104] The particle size of the (meth)acrylic polymer in the present coating is 150 nm or more, preferably 150 nm or more, more preferably 155 nm or more, from the viewpoint of better film-forming properties of the coating film and better adhesion to a concrete substrate.

[0105] The particle size of the (meth)acrylic polymer in the present coating material is preferably 200 nm or less, more preferably 190 nm or less.

[0106] The particle size of the (meth)acrylic polymer in the present coating material is calculated by the same method as the particle size of the fluorinated polymer described above, except that the particle size of the (meth)acrylic polymer determined from the result of elemental analysis is measured.

[0107] The absolute value of the difference between the particle size of the fluorinated polymer and the particle size of the (meth)acrylic polymer is 35 nm or less, preferably 34 nm or less, more preferably 33 nm or less, from the viewpoint of uniform fusion of polymer particles during film formation and better film-forming properties at low temperatures.

[0108] The lower limit of the absolute value of the difference between the particle size of the fluorinated polymer and the particle size of the (meth)acrylic polymer is usually 0 nm or more.

[0109] The Tg of the (meth)acrylic polymer is preferably 0°C or higher, more preferably 30°C or higher.

[0110] The Tg of the (meth)acrylic polymer is 40° C. or lower, and preferably 39.5° C. or lower from the viewpoint of achieving better adhesion to a concrete base material.

[0111] In addition, when a plurality of Tg values ​​are detected, the lowest temperature among them is adopted as the Tg of the (meth)acrylic polymer.

[0112] The MFT of the (meth)acrylic polymer is preferably 10°C or higher, more preferably 15°C or higher.

[0113] The MFT of the (meth)acrylic polymer is 50° C. or lower, and preferably 45° C. or lower from the viewpoint of more excellent film-forming properties at low temperatures.

[0114] The absolute value of the difference between the MFT of the fluorinated polymer and the MFT of the (meth)acrylic polymer is 20°C or less, preferably 19°C or less, more preferably 18°C ​​or less, from the viewpoint of further suppressing the occurrence of deformation of the coating film during film formation and achieving better film-forming properties at low temperatures.

[0115] The lower limit of the absolute value of the difference between the MFT of the fluorine-containing polymer and the MFT of the (meth)acrylic polymer is usually 0° C. or more.

[0116] The Mn of the (meth)acrylic polymer is preferably 1,000 to 1,000,000.

[0117] Two or more (meth)acrylic polymers may be used in combination.

[0118] The content of the (meth)acrylic polymer is preferably 20 to 90% by mass, more preferably 10 to 50% by mass, and even more preferably 15 to 30% by mass, based on the total mass of the coating material.

[0119] From the viewpoint of achieving more excellent effects of the present invention, the mass ratio of the content of the (meth)acrylic polymer to the content of the fluorinated polymer (content of (meth)acrylic polymer / content of fluorinated polymer) is preferably 10 / 90 to 60 / 40.

[0120] The water content is preferably 30 to 60% by mass, more preferably 40 to 50% by mass, based on the total mass of the coating material.

[0121] The present coating material preferably contains a film-forming aid. The film-forming aid improves the uniformity of the fluorine-containing polymer and the (meth)acrylic polymer in the present coating film, thereby forming the present coating film having more excellent water resistance.

[0122] The film-forming aid is preferably a compound having a boiling point of 100 to 400°C, more preferably a compound having a boiling point of 130 to 300°C, and particularly preferably a compound having a boiling point of 150 to 250°C.

[0123] Examples of the film-forming aid include glycol ethers, glycol ether acetates, and esters.

[0124] If the glycol ether, glycol ether acid ester, ester etc. whose boiling point is in the above-mentioned range, then it is difficult to evaporate compared with water when film is formed, so it is possible to suppress the water-based paint coated on the substrate to be rapidly film-coated.Thus, it is inferred that film-coating is carried out under the state of the uniformity of the composition of the fluoropolymer and the (methyl) acrylic polymer being maintained, so the water resistance of this film is more excellent.On the other hand, owing to being difficult to remain in the film after the formation, it is therefore believed that water is difficult to be introduced into the film, and the water resistance of this film is more excellent.

[0125] Specific examples of the film-forming aid include glycol ethers such as diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol monobenzyl ether, dipropylene glycol mono-n-butyl ether, ethylene glycol mono-2-ethylhexyl ether, and ethylene glycol monoallyl ether; glycol ether acetates such as ethylene glycol mono-n-butyl ether acetate and diethylene glycol mono-n-butyl ether acetate; esters such as 2,2,4-trimethylpentane-1,3-diol monoisobutyrate (Texanol), triacetin, diethyl adipate, diisodecyl adipate, adipic acid (2-butoxyethyl ester), and dibutyl sebacate.

[0126] Two or more film-forming aids may be used in combination.

[0127] The content of the film-forming aid is preferably 1 to 30% by mass, more preferably 4 to 20% by mass, and even more preferably 8 to 18% by mass, based on the total mass of the coating material.

[0128] The coating may also contain additives such as pigments (inorganic pigments, organic pigments, etc.), surfactants, curing agents, curing aids, thickeners, dispersants, defoamers, light stabilizers, ultraviolet absorbers, surface conditioners, and the like.

[0129] The viscosity of the present coating at 25°C is preferably 200 mPa·s or more, more preferably 300 mPa·s or more, further preferably 500 mPa·s or more, and is preferably 10000 mPa·s or less, more preferably 7000 mPa·s or less, further preferably 5000 mPa·s or less.

[0130] The method for measuring the viscosity of the present coating material is as described in the Examples section below.

[0131] The coated article of the present invention comprises a substrate and a coating film (present coating film) formed by using the present coating material and disposed on the substrate, wherein the material of the substrate is concrete. In this specification, a substrate whose material includes concrete is also referred to as a concrete substrate.

[0132] The thickness of the present coating film is preferably 5 to 300 μm, more preferably 10 to 100 μm. When the thickness of the present coating film is at least the lower limit, the durability of the present coating film is improved, and when it is at most the upper limit, the weather resistance of the present coating film is improved.

[0133] The coated article can be manufactured by applying this coating on the surface of the substrate and drying it to form this coating. This coating can be directly applied to the surface of the substrate, or it can be applied after the surface of the substrate is subjected to a known surface treatment (substrate treatment, etc.). Furthermore, it can also be applied to the primer layer after forming a primer layer on the substrate.

[0134] The concrete base material may crack due to the construction method, the use environment, etc. The cracked portion of the concrete base material may be repaired by injecting a repair material such as epoxy resin.

[0135] The coating film formed using the present coating material exhibits excellent adhesion even to a concrete base material whose cracks have been repaired with epoxy resin or the like, and can therefore be suitably used.

[0136] The coating can also be used for substrates made of materials other than concrete. Specific examples of the material of such substrates include organic materials such as resins, rubber, and wood, inorganic materials such as glass, ceramics, and stone, and metals such as iron, iron alloys, aluminum, and aluminum alloys.

[0137] Specific examples of the coating method of the present coating material include methods using a coating device such as a brush, a roller, a dipper, a sprayer, a roll coater, a die coater, an applicator, or a spin coater.

[0138] The coating film is preferably formed by applying the coating to form a coating layer and drying the obtained coating layer. The drying temperature after coating is preferably 0 to 50° C. The coating film can be formed by heat curing as needed after forming the coating layer and drying it. The heat curing temperature is preferably 50 to 200° C. The drying time is usually 30 minutes to 2 weeks, and the heat curing time is usually 1 minute to 24 hours.

[0139] Example

[0140] The present invention is described in detail below with examples. Examples 1 and 4 are embodiments, and Examples 2, 3, and 5 are comparative examples. However, the present invention is not limited to these examples. It should be noted that the blending amount of each component in the table described below represents a mass basis.

[0141] <Abbreviations and details of ingredients used>

[0142] 〔monomer〕

[0143] CTFE: Chlorotrifluoroethylene

[0144] CHVE: Cyclohexyl vinyl ether

[0145] CHMVE: Cyclohexanedimethanol monovinyl ether

[0146] CM-EOVE: CH2=CHOCH2-cycloC6H 10 -CH2O(CH2CH2O)nH(n=15)

[0147] EVE: Ethyl Vinyl Ether

[0148] MMA: Methyl Methacrylate

[0149] IBA: Isobutyl Acrylate

[0150] 〔Dispersion liquid〕

[0151] Dispersion F1: An aqueous dispersion in which particles of a fluorinated polymer (hydroxyl value: 13 mgKOH / g) are dispersed in water and the polymer concentration is 50% by mass, wherein the fluorinated polymer comprises 50 mol% of units based on CTFE, 2.0 mol% of units based on CHMVE, 0.3 mol% of units based on CM-EOVE, 46.7 mol% of units based on EVE, and 1.0 mol% of units based on CHVE, relative to all units contained in the fluorinated polymer.

[0152] Dispersion F2: Aqueous dispersion in which PVDF (polyvinylidene fluoride) particles are dispersed in water and the polymer concentration is 50% by mass

[0153] Dispersion F3: An aqueous dispersion in which particles of a fluorinated polymer (hydroxyl value: 50 mgKOH / g) are dispersed in water and the polymer concentration is 50% by mass, wherein the fluorinated polymer comprises 50 mol% of units based on CTFE, 10 mol% of units based on CHMVE, 0.5 mol% of units based on CM-EOVE, 17 mol% of units based on EVE, and 22.5 mol% of units based on CHVE, relative to all units contained in the fluorinated polymer

[0154] Dispersion A1: Udouble (registered trademark) E-771SI (manufactured by NIPPON SHOKUBAI CO., LTD.), an aqueous dispersion in which particles of a (meth)acrylic polymer are dispersed in water and the polymer concentration is 44% by mass

[0155] Dispersion A2: Containing (meth)acrylic polymer (MFT: 0°C or less, SP value: 26.8 (J / cm 3 ) 1 / 2, an average particle size of 110 nm) and an aqueous dispersion having a polymer concentration of 44% by mass, wherein the (meth)acrylic polymer comprises 50 mol% of units based on MMA and 50 mol% of units based on IBA relative to all monomer units contained in the (meth)acrylic polymer.

[0156] Dispersion A3: ZH140 (manufactured by Aqua Union), an aqueous dispersion in which particles of a (meth)acrylic acid polymer are dispersed in water and the polymer concentration is 44% by mass

[0157] Dispersion A4: #3000 (registered trademark) 3401MA (manufactured by TAISEI FINE CHEMICAL CO., LTD.), an aqueous dispersion in which particles of a (meth)acrylic acid polymer are dispersed in water and the polymer concentration is 40% by mass

[0158] In addition, dispersion liquid F1, dispersion liquid F2, dispersion liquid F3, and dispersion liquid A2 were produced using a known method.

[0159] [Example 1]

[0160] Dispersion liquid F1 (50 g), dispersion liquid A1 (50 g), and a film-forming aid (ethylene glycol mono-2-ethylhexyl ether (EHG), boiling point: 229° C.) (10 g) were mixed to obtain a coating composition 1 as a water-based coating.

[0161] [Example 2~Example 5]

[0162] Except having changed the kind of dispersion liquid as shown in Table 1, it carried out similarly to Example 1, and obtained the coating composition 2-5 which is a water-based coating material.

[0163] [Particle size]

[0164] The particle sizes of the fluorine-containing polymer particles and the (meth)acrylic polymer particles contained in each coating composition were measured by the above-mentioned method.

[0165] [Viscosity]

[0166] The viscosity (unit: mPa·s) of the coating composition at 25° C. was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name “TV-35 type viscometer TVE-35H”) at a rotation speed of 50 rpm.

[0167] [Film forming properties in low temperature environments]

[0168] Coating compositions 1 to 5 were applied to the surface of a concrete substrate having a length of 120 mm, a width of 60 mm, and a thickness of 15 mm so that the dry film thickness was 40 μm, and dried at room temperature (23° C.) for 2 weeks. After 2 weeks, the surface of the coating film formed using each coating composition was touched with a finger, and the film-forming property in a low temperature environment of 23° C. without heating during film formation was evaluated according to the following criteria. If the evaluation was A, it can be said that the film-forming property in a low temperature environment is excellent.

[0169] A: There is no coating film attached when touched with fingers

[0170] B: When touched with fingers, there is more or less coating adhesion

[0171] [Adhesion]

[0172] The adhesion of the coating film to the concrete substrate was evaluated by the cross-cut method (JIS K 5600-5-6).

[0173] Specifically, for the substrate with a coating film produced in the film-forming property evaluation under a low temperature environment, the coating film was cut into a checkerboard shape of 100 squares with an interval of 1 mm, and an adhesive tape was attached thereto. Then, the adhesion was evaluated according to the number of squares (number of squares / 100) that were not peeled off by the adhesive tape out of 100 squares when the adhesive tape was peeled off, according to the following criteria. If the evaluation is A, it can be said that the adhesion to the concrete substrate is excellent. It should be noted that the values ​​in parentheses in the evaluation results of the adhesion in Table 1 refer to the number of squares (number of squares that were not peeled off) / 100.

[0174] A: The number of grids exceeds 95.

[0175] B: The number of grids is 70 or more and 95 or less.

[0176] C: The number of cells is less than 70.

[0177] [Table 1]

[0178]

[0179] As shown in Table 1, it was confirmed that the coating composition of the present invention has excellent film-forming properties in a low-temperature environment and can form a coating film having excellent adhesion to a concrete substrate (Example 1, Example 4).

[0180] It should be noted that the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2022-161676 filed on October 6, 2022 are cited herein and introduced as a disclosure of the specification of the present invention.

Claims

1. A coating composition, characterized in that Comprising a fluorine-containing polymer, a (meth)acrylic polymer and water, The particle size of the (meth)acrylic polymer in the coating composition is 150 nm or more, The (meth)acrylic polymer has a glass transition temperature of 40° C. or less, The minimum film-forming temperatures of the fluorine-containing polymer and the (meth)acrylic polymer are both below 50° C., The absolute value of the difference between the lowest film-forming temperature of the fluorine-containing polymer and the lowest film-forming temperature of the (meth)acrylic polymer is 20° C. or less, The absolute value of the difference between the particle size of the fluorine-containing polymer and the particle size of the (meth)acrylic polymer is 35 nm or less.

2. The coating composition according to claim 1, wherein The fluoropolymer comprises units based on CF2=CFCl. 3 . The coating composition according to claim 1 , which has a viscosity at 25° C. of 200 mPa·s or more. The coating composition according to claim 1 , further comprising a film-forming aid.

5. The coating composition according to claim 1, wherein The mass ratio of the content of the (meth)acrylic polymer to the content of the fluorine-containing polymer is 10 / 90 to 60 / 40.

6. A coated article, characterized in that: A method of manufacturing a coating material comprising a substrate and a coating film disposed on the substrate, wherein the coating film is formed using the coating composition according to any one of claims 1 to 5. The material of the substrate is concrete.

7. A coating composition, characterized in that: Comprising a fluorine-containing polymer, a (meth)acrylic polymer and water, The particle size of the (meth)acrylic polymer in the coating composition is 150 nm or more, The (meth)acrylic polymer has a glass transition temperature of 40° C. or less, The minimum film-forming temperature of the fluorine-containing polymer is below 60°C. The (meth)acrylic polymer has a minimum film-forming temperature of 50° C. or less. The absolute value of the difference between the lowest film-forming temperature of the fluorine-containing polymer and the lowest film-forming temperature of the (meth)acrylic polymer is 20° C. or less, The absolute value of the difference between the particle size of the fluorine-containing polymer and the particle size of the (meth)acrylic polymer is 35 nm or less.

8. The coating composition according to claim 7, wherein The fluoropolymer comprises units based on CF2=CFCl. 9 . The coating composition according to claim 7 , which has a viscosity at 25° C. of 200 mPa·s or more.

10. The coating composition according to claim 7, further comprising a film-forming aid.

11. The coating composition according to claim 7, wherein The mass ratio of the content of the (meth)acrylic polymer to the content of the fluorine-containing polymer is 10 / 90 to 60 / 40.

12. A coated article, characterized in that: A coating composition comprising a substrate and a coating film disposed on the substrate, wherein the coating film is formed using the coating composition according to any one of claims 7 to 11, The material of the substrate is concrete.

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