Coating composition

Abstract

To provide a coating composition which is suitable for use in an exfoliation prevention material requiring load resistance.SOLUTION: A coating composition contains a silylated urethane resin (A) and water, wherein coated film strength when formed into a coated film having a dry film thickness of 300 μm is 25-80 N, an elongation rate is 50-400%, and crosslinking density is 1.0×10-4(mol / cc) to 5.0×10-3(mol / cc).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a coating composition, and more particularly to a coating composition suitable for use in a peeling prevention method that requires load resistance. [Background technology]

[0002] Concrete is widely used for structures such as viaducts, tunnels, and bridges due to its excellent strength and durability. However, concrete structures can deteriorate due to corrosion of internal reinforcing bars caused by salt damage, neutralization of concrete due to exhaust gases, alkali-aggregate reaction, and freezing of water that has penetrated cracks. As pieces of deteriorated concrete peel off from the surface, the strength and aesthetics of the concrete structure itself decrease, and there is a risk of accidents due to spalling.

[0003] Surface protection is a proven method for preventing concrete deterioration. This involves applying a coating to the surface of a structure to prevent or inhibit the penetration of deterioration factors. For areas where damage to third parties is expected if concrete pieces fall off, it is preferable to use a method that improves reinforcing effects by placing fiber sheets or the like within the coating (a method to prevent concrete from falling off).

[0004] Required performance of anti-spadding methods includes load-bearing capacity, adhesion, durability, and elongation performance, and evaluation standards for each performance are often established depending on the area where the anti-spadding method is applied. For example, Metropolitan Expressway Company Limited's "Bridge Structure Design Guidelines: Concrete Piece Anti-Spadding Pieces" (August 2014 (partially revised)) classifies anti-spadding methods into Type A and Type B, and specifies the scope of application of the anti-spadding method and evaluation standards for load-bearing capacity, etc. for each type. The scope of application of Type A anti-spadding methods is specified as the side of the balustrade where a water drainage section is installed and the underside of the overhanging deck, and based on the evaluation standards, it is considered that these are areas where load-bearing capacity is particularly required.

[0005] Furthermore, in recent years, due to considerations of the environment and safety, there has been a demand to avoid the use of covering materials that are classified as hazardous materials, and development is underway to achieve both environmental friendliness and performance. Note that hazardous materials here are those defined in the Fire Service Act, and generally include materials that pose a high risk of fire, a high risk of fire spreading, and are difficult to extinguish.

[0006] Japanese Patent Laid-Open Publication No. 2011-99209 (Patent Document 1) describes a concrete spalling prevention method for concrete structures, which involves covering the surface of the concrete structure with adhesive polymer cement mortar and a mesh sheet, and then covering that with a water-based paint. The spalling prevention method described in Patent Document 1 can be said to be environmentally friendly because it uses water-based paint and generates almost no toxic gases even in the event of a fire, but there is room for improvement in that adhesive polymer cement mortar is considered a hazardous material.

[0007] Japanese Patent Application Laid-Open Publication No. 2019-7312 (Patent Document 2) describes a method for preventing concrete from spalling from a concrete structure by forming a laminate comprising an undercoat coating film, a fiber sheet, and a topcoat coating film on the surface of the concrete structure. The spalling prevention method described in Patent Document 2 uses a water-based paint to form the undercoat coating film and the topcoat coating film, and is a method that takes into consideration environmental and safety aspects. Furthermore, this water-based paint contains an emulsion resin or dispersion resin and is a paint that can form a coating film with a dry film thickness of 400 μm that has a visible light transmittance of 50% or more and a haze of 70 or less. Therefore, the spalling prevention method described in Patent Document 2 makes it easy to check the film thickness during construction and the concrete surface after construction. On the other hand, the spalling prevention method described in Patent Document 2 does not have high load-bearing capacity, and its range of application is limited.

[0008] Japanese Patent Publication No. 2007-247290 (Patent Document 3) describes a concrete spalling prevention surface coating method in which a primer layer (A), a main material layer (B), a concrete spalling prevention sheet (C), a main material layer (B), and a topcoat coating layer (D) are sequentially layered on the surface of concrete. Patent Document 3 describes how all of the paints used in each process can be water-based, and favorable results have been shown in load-bearing evaluation tests, making this surface coating method both environmentally friendly and highly functional. However, the description of the amount of coating of the main material layer indicates that its thickness is relatively thick, and it is believed that the good load-bearing properties of this surface coating method are limited to thick main material layers. In the concrete spalling prevention surface coating method described in Patent Document 3, if the main material layer is thin, the strength of the main material layer alone is insufficient, and the concrete spalling prevention sheet may penetrate the coating, resulting in insufficient load-bearing properties.

[0009] Japanese Patent Laid-Open Publication No. 2018-159250 (Patent Document 4) describes a concrete chip spalling prevention structure that includes a primer layer formed on a concrete substrate and formed from a primer coating composition containing a water-soluble resin composition, an intermediate coating layer formed on the primer layer and including a mesh sheet, and formed from an intermediate coating composition containing a water-soluble resin composition, and a top coating layer formed on the intermediate layer and formed from a top coating composition containing a water-soluble resin composition. While Patent Document 4 shows good results for punching strength, which is an indicator of load-bearing capacity, this spalling prevention structure uses a relatively high-strength mesh sheet with a tensile strength of 2,500 to 4,300 N / 50 mm. This is thought to be a major factor in the load-bearing capacity (punching strength), and there is room for improvement in the intermediate coating composition. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-99209 [Patent Document 2] Japanese Patent Application Publication No. 2019-7312 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-247290 [Patent Document 4] Japanese Patent Application Laid-Open No. 2018-159250 Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, an object of the present invention is to provide a coating composition suitable for use in a spalling prevention method that requires load resistance. [Means for solving the problem]

[0012] As a result of intensive research to achieve the above object, the present inventors have found that a coating composition that uses a silylated urethane resin as the resin in the coating composition, adjusts the crosslink density, and is capable of forming a coating film that satisfies specific coating film strength and elongation can improve the load resistance evaluation in the anti-peeling method, and have completed the present invention. Furthermore, because this coating composition uses water as the solvent, it can be a safe coating that puts less strain on the environment.

[0013] Therefore, one embodiment of the present invention is a coating composition containing a silylated urethane resin (A) and water, which has a coating strength of 25 to 80 N, an elongation of 50 to 400%, and a crosslink density of 1.0 × 10 when formed into a coating film having a dry thickness of 300 μm. -4 (mol / cc) ~ 5.0 × 10 -3 (mol / cc).

[0014] In a preferred embodiment of the coating composition of the present invention, the coating composition is -1 The viscosity at 23°C is 10 to 2000 Pa·s, and the shear rate is 1000 s -1 The viscosity at 23°C is 0.05 to 3.0 Pa·s.

[0015] In another preferred embodiment of the coating composition of the present invention, the coating composition has no flash point.

[0016] Another preferred embodiment of the coating composition of the present invention further contains a crosslinking agent (B) that reacts with the silylated urethane resin (A).

[0017] In another preferred embodiment of the coating composition of the present invention, the crosslinking agent is a carbodiimide.

[0018] In another preferred embodiment of the coating composition of the present invention, the mass ratio of the silylated urethane resin (A) to the crosslinking agent (B) is (A) / (B)=60 / 40 to 99 / 1. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a coating composition suitable for use in a spalling prevention method that requires load resistance. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in detail below.

[0021] One aspect of the present invention is a coating composition comprising a silylated urethane resin and water. In this specification, this coating composition is also referred to as the "coating composition of the present invention."

[0022] The coating composition of the present invention contains water. The water used in the coating composition of the present invention is not particularly limited, but suitable examples include tap water, ion-exchanged water, distilled water, and other pure water. When the coating composition is to be stored for a long period of time, water that has been sterilized by ultraviolet irradiation or the like may be used to prevent the growth of mold and bacteria. The amount of water in the coating composition of the present invention is preferably 15 to 75 mass %, more preferably 20 to 65 mass %.

[0023] When the silylated urethane resin has alkoxysilyl groups, a hydrolysis reaction between the alkoxysilyl groups and water may occur in the coating composition, and therefore, in the silylated urethane resin, some or all of the alkoxysilyl groups may be converted to silanol groups and / or siloxane bonds.

[0024] The coating composition of the present invention is preferably a water-based coating composition. In this specification, "water-based coating composition" refers to a coating composition containing water as the main solvent. Water-based coatings have a low environmental impact and can be made into coating compositions without a flash point. Water-based coatings are also preferred from the viewpoint of preventing organic solvent poisoning in workers, and are coatings that take health and safety into consideration, and do not cause secondary disasters such as the spread of fire even if a fire occurs.

[0025] In a preferred embodiment, the coating composition of the present invention has no flash point. As used herein, "no flash point" means that no ignition is observed in a test according to the rapid equilibrium closed-circuit method specified in JIS K 2265-2:2007.

[0026] The coating composition of the present invention contains a silylated urethane resin. The silylated urethane resin refers to a urethane resin having a reactive silyl group. The silylated urethane resin is a resin capable of forming a coating film with high adhesion, water resistance, and flexibility, and by further adjusting the crosslink density, it is possible to achieve a balance between the flexibility and strength of the coating film formed. In this specification, the silylated urethane resin may also be referred to as "silylated urethane resin (A)."

[0027] The urethane resin can be obtained by reacting a polyol component, a polyisocyanate component, and optionally a chain extender. The silylated urethane resin can be obtained by further using a silane compound having a functional group reactive with a hydroxyl group or an isocyanate group to introduce a silyl group during the preparation of the urethane resin. The silylated urethane resin may be used alone or in combination of two or more.

[0028] The silylated urethane resin is preferably a urethane resin having an alkoxysilyl group (an alkoxysilylated urethane resin). The silylated urethane resin is preferably a urethane resin having a silyl group at its terminal (a terminally silylated urethane resin). The silylated urethane resin is preferably a urethane resin having an alkoxysilyl group at its terminal (a terminally alkoxysilylated urethane resin). Such a silylated urethane resin can be obtained, for example, by preparing a urethane prepolymer (preferably an isocyanate-terminated urethane prepolymer) from a polyol component and a polyisocyanate component, and then reacting this urethane prepolymer with a silane compound (preferably an alkoxysilane compound) having a functional group reactive with the terminal group of the urethane prepolymer. Furthermore, a chain extender may be further reacted with the isocyanate group remaining in the reaction product of the urethane prepolymer and the silane compound.

[0029] When the silylated urethane resin is a urethane resin having an alkoxysilyl group, the alkoxysilyl group may be converted to a silanol group upon hydrolysis by water in the coating composition, and therefore the silylated urethane resin may have a silanol group and / or a siloxane bond.

[0030] The polyol component is a compound having at least two hydroxyl groups therein, and examples thereof include polyhydric alcohols, polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, polyacrylic polyols, castor oil, etc. Among these, polyether polyols, polyester polyols, and polycarbonate polyols are preferred. The polyol component may be used alone or in combination of two or more.

[0031] Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene diol, 1,3-tetramethylene diol, 1,5-pentamethylene diol, neopentyl glycol, 1,6-hexamethylene diol, glycerin, trimethylolpropane, trimethylolethane, 1,4-cyclohexanediol, bisphenols (such as bisphenol A), and sorbitol.

[0032] Examples of polyether polyols include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, as well as copolymers of multiple alkylene oxides such as ethylene oxide and propylene oxide.

[0033] Examples of polyester polyols include condensation polymers of polyhydric alcohols and polycarboxylic acids; ring-opening polymers of cyclic esters (lactones); and reaction products of three components: polyhydric alcohols, polycarboxylic acids, and cyclic esters. Examples of polyhydric alcohols that can be used to synthesize polyester polyols include the polyhydric alcohols described above. Examples of polycarboxylic acids that can be used to synthesize polyester polyols include aliphatic dicarboxylic acids such as malonic acid, maleic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and trimellitic acid. Examples of cyclic esters that can be used to synthesize polyester polyols include propiolactone, β-methyl-δ-valerolactone, and ε-caprolactone.

[0034] Examples of polycarbonate polyols include reaction products of polyhydric alcohols and phosgene; ring-opening polymerization products of cyclic carbonates (such as alkylene carbonates); etc. Examples of polyhydric alcohols that can be used to synthesize polycarbonate polyols include the polyhydric alcohols described above. Examples of cyclic carbonates that can be used to synthesize polycarbonate polyols include alkylene carbonates such as ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate.

[0035] Polyolefin polyol is a polyol having a skeleton (or main chain) with one or more olefin repeating units and at least two hydroxyl groups in the molecule (especially at the terminals). The olefin is not particularly limited and may be an olefin having a carbon-carbon double bond at the terminal (e.g., α-olefins such as ethylene and propylene), or an olefin having a carbon-carbon double bond at a position other than the terminal (e.g., isobutene), or even one having multiple carbon-carbon double bonds such as a diene (e.g., butadiene, isoprene).

[0036] Polyacrylic polyol is a polyol having a skeleton (or main chain) with one or more (meth)acrylate repeating units and at least two hydroxyl groups in the molecule (especially at the terminals). The (meth)acrylate is a (meth)acrylic acid alkyl ester, preferably (meth)acrylic acid C 1-20 Alkyl esters, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

[0037] In polyolefin polyols and polyacrylic polyols, in order to introduce hydroxyl groups into the molecules, a monomer having a hydroxyl group, for example, an α,β-unsaturated compound such as a hydroxyalkyl (meth)acrylate, such as 2-hydroxyethyl (meth)acrylate or 3-hydroxypropyl (meth)acrylate, can be used as a copolymerization component of the olefin or (meth)acrylate.

[0038] The polyol component preferably contains an anionic group-containing polyol, and more preferably contains both an anionic group-free polyol and an anionic group-containing polyol. By using an anionic group-containing polyol, an anionic group can be introduced into the silylated urethane resin. Such a silylated urethane resin is also referred to as an anionic group-containing silylated urethane resin. Suitable anionic groups include carboxyl groups and sulfo groups, with carboxyl groups being the most preferred. When the coating composition of the present invention contains a basic compound, the anionic group-containing silylated urethane resin may form a salt by a neutralization reaction with the basic compound. Therefore, the silylated urethane resin may be in the form of a salt.

[0039] Examples of the anionic group-containing polyol include carboxyl group-containing polyols obtained by introducing carboxyl groups into the above-mentioned polyols. Furthermore, the anionic group-containing polyol is preferably a polyhydroxycarboxylic acid represented by structural formula (1). (HO) x L(COOH) y (1) In structural formula (1), L represents a hydrocarbon moiety having 1 to 12 carbon atoms, x is an integer of 2 or more, and y is an integer of 1 or more.

[0040] In structural formula (1), L is preferably an aliphatic hydrocarbon moiety, and may be either linear or branched. When a compound has a plurality of hydroxyl groups, the plurality of hydroxyl groups may be bonded to the same carbon atom or different carbon atoms. When a compound has a plurality of carboxyl groups, the plurality of carboxyl groups may be bonded to the same carbon atom or different carbon atoms.

[0041] The polyhydroxycarboxylic acid is preferably a dimethylolalkanoic acid (particularly 2,2-dimethylolalkanoic acid), such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolpentanoic acid, 2,2-dimethylolhexanoic acid, 2,2-dimethylolheptanoic acid, 2,2-dimethyloloctanoic acid, 2,2-dimethylolnonanoic acid, or 2,2-dimethyloldecanoic acid.

[0042] When an anionic group is introduced into the silylated urethane resin, a polythiol compound having an anionic group or a polyamine compound having an anionic group may be used together with the polyol.

[0043] The polyisocyanate component is a compound having at least two isocyanate groups therein, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and araliphatic polyisocyanates. Among these, aliphatic polyisocyanates and araliphatic polyisocyanates are preferred. The use of aliphatic polyisocyanates or araliphatic polyisocyanates can suppress discoloration of the silylated urethane resin. The polyisocyanate component may be used alone or in combination of two or more.

[0044] Examples of the aliphatic polyisocyanate include aliphatic diisocyanates such as 1,3-trimethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,3-pentamethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate, 3-methyl-1,5-pentamethylene diisocyanate, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 2,6-diisocyanate methylcaproate, and lysine diisocyanate.

[0045] Examples of alicyclic polyisocyanates include alicyclic diisocyanates such as 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, and norbornane diisocyanate.

[0046] Examples of aromatic polyisocyanates include aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 4,4'-diphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, and 3,3'-dimethoxydiphenyl-4,4'-diisocyanate.

[0047] Examples of the aromatic aliphatic polyisocyanate include aromatic aliphatic diisocyanates such as 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3-bis(1-isocyanato-1-methylethyl)benzene, 1,4-bis(1-isocyanato-1-methylethyl)benzene, and 1,3-bis(α,α-dimethylisocyanatomethyl)benzene.

[0048] Suitable examples of the polyisocyanate component include 1,6-hexamethylene diisocyanate, 4,4'-methylenebis(cyclohexylisocyanate), 1,3-bis(isocyanatemethyl)cyclohexane, 1,4-bis(isocyanatemethyl)cyclohexane, isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, norbornane diisocyanate, and 1,3-bis(α,α-dimethylisocyanatemethyl)benzene.

[0049] The polyisocyanate component also includes multimers (e.g., dimers and trimers), reaction products, or polymers of the above-mentioned polyisocyanates, such as a dimer or trimer of diphenylmethane diisocyanate, a reaction product of trimethylolpropane and tolylene diisocyanate, a reaction product of trimethylolpropane and hexamethylene diisocyanate, polymethylene polyphenylisocyanate, polyether polyisocyanate, and polyester polyisocyanate.

[0050] The polyisocyanate component also includes modified products. Examples of modified polyisocyanates include polyisocyanates having a structure such as uretdione, isocyanurate, urethane, urea, allophanate, biuret, carbodiimide, iminooxadiazinedione, oxadiazinetrione, and oxazolidone.

[0051] In preparing the silylated urethane resin, a diisothiocyanate (for example, phenyl diisothiocyanate) may be used in combination with the polyisocyanate component.

[0052] The silane compound used to introduce a silyl group in the preparation of the silylated urethane resin is preferably a silane compound having a functional group (e.g., an amino group) that is reactive with a hydroxyl group or an isocyanate group, more preferably an alkoxysilane compound having a functional group (e.g., an amino group) that is reactive with a hydroxyl group or an isocyanate group, even more preferably an alkoxysilane compound containing an amino group, and particularly preferably an alkoxysilane compound containing a secondary amino group. These silane compounds may be used alone or in combination of two or more.

[0053] The secondary amino group-containing alkoxysilane compound can be obtained, for example, by reacting a primary amino group-containing alkoxysilane compound (particularly an alkoxysilane compound having one primary amino group) with an unsaturated aliphatic monocarboxylic acid ester (particularly an unsaturated aliphatic monocarboxylic acid ester not having an aromatic ring). The secondary amino group-containing alkoxysilane compound is preferably a reaction product of a primary amino group-containing alkoxysilane compound and an unsaturated aliphatic monocarboxylic acid ester. When silylation is performed using such a secondary amino group-containing alkoxysilane compound, even if the silylated urethane resin forms silanol groups by reacting with water in the coating composition, the silanol groups can remain stable in water, making it possible to suppress or prevent condensation reactions between silanol groups.

[0054] The primary amino group-containing alkoxysilane compound is preferably a silane compound having one primary amino group (unsubstituted amino group) and at least one alkoxy group in the molecule. The primary amino group-containing alkoxysilane compound may be used alone or in combination of two or more.

[0055] Examples of the alkoxy group include a C alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutyloxy group, a s-butyloxy group, and a t-butyloxy group. 1-4 An alkoxy group is preferred. As the alkoxy group, a methoxy group, an ethoxy group, and a propoxy group are more preferred, and a methoxy group and an ethoxy group are even more preferred. The alkoxy group is usually bonded to the silicon atom of the primary amino group-containing alkoxysilane compound, and the number thereof is usually 1 to 3 (preferably 2 or 3). When a plurality of alkoxy groups are present, the plurality of alkoxy groups may be the same or different.

[0056] The primary amino group may be directly bonded to the silicon atom, but is preferably bonded to the silicon atom via a linker. Examples of linkers include divalent groups, specifically, divalent hydrocarbon groups such as alkylene groups, arylene groups, alkylene-arylene groups, and alkylene-arylene-alkylene groups; and various divalent groups formed by combining hydrocarbon groups such as alkylene-oxy-alkylene groups, alkylene-carbonyl-oxy-alkylene groups, alkylene-oxy-carbonyl-alkylene groups, and alkylene-poly(oxyalkylene) groups with other groups (e.g., oxy groups, carbonyl groups, carbonyl-oxy groups). When the primary amino group is bonded to the silicon atom via a linker, the primary amino group-containing alkoxysilane compound preferably has an aminoalkyl group. Examples of aminoalkyl groups include amino-C groups such as aminomethyl groups, 1-aminoethyl groups, 2-aminoethyl groups, 1-aminopropyl groups, 2-aminopropyl groups, and 3-aminopropyl groups. 1-3 Examples thereof include alkyl groups.

[0057] The primary amino group-containing alkoxysilane compound is preferably a compound represented by structural formula (2). [ka] In structural formula (2), R 1 and R 2 may be the same or different and represent an alkyl group; R 3 represents an alkylene group, and m is an integer of 1 to 3.

[0058] In structural formula (2), R 1 Suitable examples of the alkyl group in R include alkyl groups having about 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and t-butyl groups. 2 Examples of the alkyl group in R include alkyl groups having about 1 to 4 carbon atoms, and methyl and ethyl groups are preferred. 3The alkylene group is preferably an alkylene group having about 1 to 3 carbon atoms, such as a methylene group, an ethylene group, or a trimethylene group.

[0059] Specific examples of the primary amino group-containing alkoxysilane compound represented by structural formula (2) include aminomethyltrimethoxysilane, aminomethyltriethoxysilane, β-aminoethyltrimethoxysilane, β-aminoethyltriethoxysilane, β-aminoethyltrippropoxysilane, β-aminoethyltriisopropoxysilane, β-aminoethyltributoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrippropoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltributoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltripropoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltribut ... Aminoalkyltrialkoxysilanes such as β-aminoethylmethyldimethoxysilane, β-aminoethylmethyldiethoxysilane, β-aminoethylmethyldipropoxysilane, β-aminoethylmethyldiisopropoxysilane, β-aminoethylmethyldibutoxysilane, β-aminoethylethyldimethoxysilane, β-aminoethylethyldiethoxysilane, β-aminoethylethyldipropoxysilane, β-aminoethylethyldiisopropoxysilane, β-aminoethylethyldibutoxysilane, β-aminoethyl Propyldimethoxysilane, β-aminoethylpropyldiethoxysilane, β-aminoethylpropyldipropoxysilane, β-aminoethylpropyldiisopropoxysilane, β-aminoethylpropyldibutoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylmethyldipropoxysilane, γ-aminopropylmethyldiisopropoxysilane, γ-aminopropylmethyldibutoxysilane, γ-aminopropylethyldimethoxysilane, γ-aminopropylethyldiethoxysilane Examples thereof include (aminoalkyl)alkyldialkoxysilanes such as γ-aminopropylethyldipropoxysilane, γ-aminopropylethyldiisopropoxysilane, γ-aminopropylethylmethyldibutoxysilane, γ-aminopropylpropyldimethoxysilane, γ-aminopropylpropyldiethoxysilane, γ-aminopropylpropyldipropoxysilane, γ-aminopropylpropyldiisopropoxysilane, and γ-aminopropylpropyldibutoxysilane, as well as the corresponding aminoalkyldialkyl(mono)alkoxysilanes.

[0060] As the primary amino group-containing alkoxysilane compound, from the viewpoints of reactivity and availability, for example, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, etc. are preferred.

[0061] The unsaturated aliphatic monocarboxylic acid ester is preferably an unsaturated aliphatic monocarboxylic acid ester having no aromatic ring. The unsaturated aliphatic monocarboxylic acid ester may be used alone or in combination of two or more.

[0062] The unsaturated aliphatic monocarboxylic acid ester is preferably a compound in which a carboxyl group or an ester thereof (e.g., an alkoxycarbonyl group, a cycloalkyloxycarbonyl group, an aryloxycarbonyl group, etc.) is directly bonded to a carbon atom forming a carbon-carbon double bond. Examples of such compounds include acrylic acid esters, methacrylic acid esters, crotonates, isocrotonic acid esters, 2-butenoic acid esters, 3-methyl-2-butenoic acid esters, 2-pentenoic acid esters, and 2-octenoic acid esters.

[0063] Examples of the ester moiety of the unsaturated aliphatic monocarboxylic acid ester include esters (e.g., alkyl esters) based on aliphatic hydrocarbons such as methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester, isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester, tridecyl ester, tetradecyl ester, hexadecyl ester, and octadecyl ester; esters (e.g., cycloalkyl esters) based on alicyclic hydrocarbons such as cyclohexyl ester, isobornyl ester, bornyl ester, dicyclopentadienyl ester, dicyclopentanyl ester, dicyclopentenyl ester, and tricyclodecanyl ester; and esters (e.g., aryl esters) based on aromatic hydrocarbons such as phenyl ester and benzyl ester.

[0064] In particular, acrylic acid esters and methacrylic acid esters are preferred as unsaturated aliphatic monocarboxylic acid esters. Acrylic acid esters and methacrylic acid esters are sometimes collectively referred to as "(meth)acrylic acid esters." Furthermore, as unsaturated aliphatic monocarboxylic acid esters, compounds represented by structural formula (3) are preferred, and (meth)acrylic acid esters represented by structural formula (3) are particularly preferred. [ka] In structural formula (3), R 4 , R 6 , R 7 may be the same or different and represent a hydrogen atom or an alkyl group, and preferably, R 4 is a hydrogen atom or a methyl group, and R 6 and R 7 Both R and R are hydrogen atoms. 5 represents an alkyl group, an aryl group, or a cycloalkyl group.

[0065] In structural formula (3), R4 Examples of the alkyl group for R include alkyl groups having about 1 to 2 carbon atoms, such as a methyl group and an ethyl group. 5 Examples of the alkyl group in R include alkyl groups having about 1 to 20 carbon atoms, such as methyl, ethyl, propyl, butyl, isobutyl, t-butyl, hexyl, octyl, and 2-ethylhexyl groups. 5 The aryl group in R includes a phenyl group, and 5 Examples of the cycloalkyl group of R include a cyclohexyl group. 6 Examples of the alkyl group for R include alkyl groups having about 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, an isobutyl group, a t-butyl group, and a hexyl group. 7 Examples of the alkyl group include alkyl groups having about 1 to 2 carbon atoms, such as a methyl group and an ethyl group.

[0066] Examples of (meth)acrylic acid esters include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

[0067] When the secondary amino group-containing alkoxysilane compound is a reaction product of a primary amino group-containing alkoxysilane compound and an unsaturated aliphatic monocarboxylic acid ester, it is preferably a compound in which the carbon atom at the β-position of the carbon-carbon double bond of the unsaturated aliphatic monocarboxylic acid ester is bonded to at least the nitrogen atom of the primary amino group in the primary amino group-containing alkoxysilane compound. This compound is obtained by subjecting the nitrogen atom of the amino group in the primary amino group-containing alkoxysilane compound to a Michael addition reaction with the unsaturated bond (carbon-carbon double bond) of the unsaturated aliphatic monocarboxylic acid ester. This reaction can be carried out in the presence or absence of a solvent. Heating or pressure may be applied during the reaction.

[0068] The amount of the unsaturated aliphatic monocarboxylic acid ester is preferably such that the amino group-containing alkoxysilane compound obtained by reacting the unsaturated aliphatic monocarboxylic acid ester with the primary amino group-containing alkoxysilane compound has at least a secondary amino group. For example, the amount of the unsaturated aliphatic monocarboxylic acid ester is about 0.8 to 2 moles per mole of the primary amino group in the primary amino group-containing alkoxysilane compound.

[0069] The secondary amino group-containing alkoxysilane compound is preferably a compound represented by structural formula (4). [ka] In structural formula (4), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and m are as defined in structural formulas (2) and (3).

[0070] The chain extender is preferably an amine-based chain extender. The amine-based chain extender is an amine compound having one or more amino groups (primary amino group, secondary amino group, etc.) other than a tertiary amino group in the molecule, and is preferably a polyamine having multiple amino groups other than tertiary amino groups in the molecule. The chain extenders may be used alone or in combination of two or more.

[0071] The number of amino groups other than the tertiary amino group in the amine chain extender is, for example, 2 to 6, preferably 2 to 4, and more preferably 2 to 3.

[0072] Examples of the amine chain extender include aliphatic polyamines, alicyclic polyamines, aromatic polyamines, araliphatic polyamines, hydrazine, and derivatives thereof.

[0073] Examples of aliphatic polyamines include aliphatic diamines such as ethylenediamine, 1,3-trimethylenediamine, 1,4-tetramethylenediamine, 1,3-pentamethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,2-propylenediamine, 1,2-butylenediamine, 2,3-butylenediamine, 1,3-butylenediamine, 2-methyl-1,5-pentamethylenediamine, 3-methyl-1,5-pentamethylenediamine, 2,4,4-trimethyl-1,6-hexamethylenediamine, and 2,2,4-trimethyl-1,6-hexamethylenediamine, as well as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

[0074] Examples of alicyclic polyamines include alicyclic diamines such as 1,3-cyclopentanediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 1-amino-1-methyl-4-aminomethylcyclohexane, 1-amino-1-methyl-3-aminomethylcyclohexane, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(3-methyl-cyclohexylamine), methyl-2,3-cyclohexanediamine, methyl-2,4-cyclohexanediamine, methyl-2,6-cyclohexanediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, isophoronediamine, and norbornanediamine.

[0075] Examples of aromatic polyamines include aromatic diamines such as m-phenylenediamine, p-phenylenediamine, 2,4-tolylenediamine, 2,6-tolylenediamine, naphthylene-1,4-diamine, naphthylene-1,5-diamine, 4,4'-diphenyldiamine, 4,4'-diphenylmethanediamine, 2,4'-diphenylmethanediamine, 4,4'-diphenyletherdiamine, 2-nitrodiphenyl-4,4'-diamine, 2,2'-diphenylpropane-4,4'-diamine, 3,3'-dimethyldiphenylmethane-4,4'-diamine, 4,4'-diphenylpropanediamine, and 3,3'-dimethoxydiphenyl-4,4'-diamine.

[0076] Examples of aromatic aliphatic polyamines include aromatic aliphatic diamines such as 1,3-xylylenediamine, 1,4-xylylenediamine, α,α,α',α'-tetramethyl-1,3-xylylenediamine, α,α,α',α'-tetramethyl-1,4-xylylenediamine, ω,ω'-diamino-1,4-diethylbenzene, 1,3-bis(1-amino-1-methylethyl)benzene, 1,4-bis(1-amino-1-methylethyl)benzene, and 1,3-bis(α,α-dimethylaminomethyl)benzene.

[0077] Examples of hydrazine and its derivatives include hydrazine and dihydrazide compounds, etc. Dihydrazide compounds include aliphatic dicarboxylic acid dihydrazides such as carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, and adipic acid dihydrazide; aromatic dicarboxylic acid dihydrazides such as isophthalic acid dihydrazide and terephthalic acid dihydrazide; and alicyclic dicarboxylic acid dihydrazides such as 1,4-cyclohexanedicarboxylic acid dihydrazide.

[0078] Suitable examples of the amine chain extender include aliphatic, alicyclic, and araliphatic polyamines such as ethylenediamine, 1,3-pentamethylenediamine, 1,6-hexamethylenediamine, diethylenetriamine, triethylenetetramine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(3-methyl-cyclohexylamine), 1,3-bis(aminomethyl)cyclohexane, isophoronediamine, norbornanediamine, and 1,3-xylylenediamine; and hydrazines such as hydrazine and carbodihydrazide, as well as derivatives thereof.

[0079] A preferred method for producing a silylated urethane resin is to prepare an isocyanate-terminated anionic group-containing urethane prepolymer from a polyol component containing an anionic group-free polyol and an anionic group-containing polyol and a polyisocyanate component, react the isocyanate-terminated anionic group-containing urethane prepolymer with a secondary amino group-containing alkoxysilane compound to prepare a terminally partially alkoxysilylated anionic group-containing urethane prepolymer, and then react the remaining isocyanate groups of the terminally partially alkoxysilylated anionic group-containing urethane prepolymer with an amine-based chain extender to prepare an anionic group-containing alkoxysilyl group-terminated urethane polymer as a silylated urethane resin. The silylated urethane resin obtained by this method is a urethane polymer having an anionic group derived from the anionic group-free polyol in the molecule, an alkoxysilyl group derived from the secondary amino group-containing alkoxysilane compound at the terminal, and a urea bond site formed by the reaction between the isocyanate group derived from the polyisocyanate component and the amino group of the amine-based chain extender.

[0080] The reaction between the polyol component and the polyisocyanate component can be carried out in accordance with a known method. A catalyst can be used to promote the reaction, and the reaction can also be carried out in a solvent.

[0081] The reaction of the isocyanate-terminated anionic group-containing urethane prepolymer with the secondary amino group-containing alkoxysilane compound can be carried out according to a known method. A catalyst can be used to promote the reaction. The reaction can also be carried out while heating, if necessary, or in a solvent.

[0082] The reaction of the terminally partially alkoxysilylated anionic group-containing urethane prepolymer with the amine-based chain extender can be carried out in accordance with a known method. A catalyst can be used to promote the reaction. The reaction can also be carried out under heating, if necessary, or in a solvent.

[0083] Catalysts that can be used in these reactions include, for example, organotin compounds, metal complexes, basic compounds such as amine compounds, and organic phosphoric acid compounds. Organotin compounds include, for example, dibutyltin dilaurate, dibutyltin maleate, dibutyltin phthalate, stannous octoate, dibutyltin methoxide, dibutyltin diacetylacetate, and dibutyltin diversatate. Metal complexes include titanate compounds such as tetrabutyl titanate, tetraisopropyl titanate, and triethanolamine titanate; metal carboxylates such as lead octoate, lead naphthenate, nickel naphthenate, and cobalt naphthenate; and metal acetylacetonate complexes such as aluminum acetylacetonate complex and vanadium acetylacetonate complex. Examples of basic compounds such as amine compounds include aminosilanes such as γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane; quaternary ammonium salts such as tetramethylammonium chloride and benzalkonium chloride; and linear or cyclic tertiary amines or quaternary ammonium salts containing multiple nitrogen atoms such as 1,8-diazabicyclo[5.4.0]undec-7-ene. Examples of organic phosphoric acid compounds include monomethyl phosphate, di-n-butyl phosphate, and triphenyl phosphate.

[0084] The equivalent ratio (NCO / OH) of the isocyanate groups of the polyisocyanate component to the hydroxyl groups of the polyol component is, for example, greater than 1 and not greater than 2.0, preferably 1.02 to 1.5, and more preferably 1.05 to 1.4.

[0085] The isocyanate group-terminated anionic group-containing urethane prepolymer preferably has an isocyanate group content of 0.3 to 7.0 mass %, more preferably 0.4 to 4.0 mass %, and even more preferably 0.5 to 3.0 mass %.

[0086] The terminally partially alkoxysilylated anionic group-containing urethane prepolymer preferably has an anionic group content of 0.2 to 3.0 mass %, more preferably 0.5 to 2.5 mass %, and even more preferably 0.8 to 2.0 mass %.

[0087] The terminally partially alkoxysilylated anionic group-containing urethane prepolymer preferably has a silicon atom content of 0.05 to 1.0 mass %, more preferably 0.1 to 0.8 mass %, and even more preferably 0.2 to 0.7 mass %.

[0088] The amine chain extender is preferably reacted in an amount approximately equal to the amount of residual isocyanate groups in the terminally partially alkoxysilylated anionic group-containing urethane prepolymer, for example, 0.8 to 1 equivalent per equivalent of isocyanate groups.

[0089] The silylated urethane resin has a hydroxyl value (OVH) of, for example, 60 to 400 mgKOH / g, and preferably 80 to 350 mgKOH / g. In this specification, the hydroxyl value is the number of milligrams (mg) of potassium hydroxide equivalent to the hydroxyl groups in 1 g of sample, and can be determined in accordance with JIS K 1557-1:2007.

[0090] The silylated urethane resin is preferably prepared in the form of a dispersion or emulsion.

[0091] The amount of silylated urethane resin in the coating composition of the present invention is, for example, 50 to 90 mass %, and preferably 65 to 85 mass %.

[0092] The coating composition of the present invention contains a silylated urethane resin and water, and can be cured under conditions where the water has dried by evaporation or volatilization.

[0093] The coating composition of the present invention has a crosslink density of 1.0×10 -4 (mol / cc) ~ 5.0 × 10 -3 (mol / cc), which is 3.0×10 -4 (mol / cc) ~ 1.0 × 10 -3 (mol / cc). Because coating films formed from silylated urethane resins have high flexibility, it is preferable to adjust the crosslink density to the above-specified range. This allows the flexibility and strength of the formed coating film to be balanced.

[0094] In this specification, the crosslink density of the coating film is calculated by the formula n=E' / 3RT (where n is the crosslink density (mol / cc) of the coating film, E' is the plateau storage modulus (Pa) of the coating film at a frequency of 1 Hz, T is the absolute temperature (K) of the plateau storage modulus of the coating film, and R is the gas constant (8.31 x 10 6 ) is calculated from the following:

[0095] The details of the method for measuring the plateau storage modulus of a coating film are as follows: A coating composition is applied to a polypropylene (PP) plate using an applicator so that the dry film thickness is 250 to 350 μm, and the plateau storage modulus is obtained by curing the plateau film for 7 days at 23°C and 50% RH. The storage modulus of the isolated film is measured using a solid viscoelasticity measuring device (for example, RSA-GII (manufactured by TA Instruments)) under the following measurement conditions, and the plateau storage modulus of the coating film is read. <Measurement conditions> Temperature range: -50℃~200℃ Heating rate: 5℃ / min Measurement length: 20.0 mm Measurement width: 8.0 mm Frequency: 1Hz Distortion: 0.05%

[0096] The coating composition of the present invention preferably contains a crosslinking agent that reacts with the silylated urethane resin. The use of the crosslinking agent makes it possible to easily adjust the crosslink density. In this specification, the crosslinking agent may also be referred to as "crosslinking agent (B)." The crosslinking agent may be used alone or in combination of two or more.

[0097] Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, carbodiimide-based crosslinking agents, aziridine-based crosslinking agents, polyethyleneimine-based crosslinking agents, and melamine-based crosslinking agents. In the coating composition of the present invention, the crosslinking agent is particularly preferably a carbodiimide. Carbodiimide-based curing agents have a long pot life (usable time), high crosslinking performance, and can improve the water resistance of the coating film in the early stages of formation.

[0098] The carbodiimide crosslinking agent is a crosslinking agent having a plurality of carbodiimide groups in the molecule. Examples of carbodiimide crosslinking agents include carbodiimide compounds such as N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide, N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide methiodide, N-tert-butyl-N'-ethylcarbodiimide, N-cyclohexyl-N'-(2-morpholinoethyl)carbodiimide meso-p-toluenesulfonate, N,N'-di-tert-butylcarbodiimide, and N,N'-di-p-tolylcarbodiimide; carbodiimide compounds obtained by a known condensation reaction of polyisocyanate in the presence of a carbodiimidization catalyst; and carbodiimide compounds made from polyisocyanate and polyalkylene oxide as raw materials. Carbodiimide crosslinking agents are available from Nisshinbo Chemical Inc. and the like.

[0099] In the coating composition of the present invention, the mass ratio of the silylated urethane resin (A) to the crosslinking agent (B) is preferably (A) / (B) = 60 / 40 to 99 / 1, more preferably (A) / (B) = 80 / 20 to 95 / 5.

[0100] The coating composition of the present invention may be either a one-component or two-component type, but when a crosslinker is used, a two-component coating composition is preferred. As used herein, a "two-component coating composition" refers to a coating that is separated into two parts and mixed only immediately before use. For example, the two parts constituting the coating composition of the present invention are a base agent containing a silylated urethane resin and a curing agent containing a crosslinker. When mixing the base agent and curing agent, additives such as water or a diluent may be added for the purpose of adjusting viscosity, etc.

[0101] The coating composition of the present invention has a coating strength of 25 to 80N, preferably 30 to 70N, and more preferably 35 to 60N when formed into a coating film having a dry film thickness of 300µm.

[0102] Examples of methods for adjusting the coating strength include adjusting the mass ratio of the silylated urethane resin (A) to the crosslinking agent (B), preferably adjusting the mass ratio of the silylated urethane resin (A) to the crosslinking agent (B) so that (A) / (B) is in the range of 60 / 40 to 99 / 1; adjusting the amount of pigment in the coating film-forming components, preferably adjusting the amount of pigment in the coating film-forming components to 5 to 60 mass%; more preferably using white carbon as an extender pigment, and particularly preferably adjusting the amount of white carbon in the coating film-forming components to 1 to 30 mass%; and these methods may be combined.

[0103] In this specification, the coating strength can be measured in accordance with the Japan Road Association's "Guidelines for Salt Damage Prevention Measures for Road Bridges (Draft) and Commentary, Appendix 1. Quality Test Methods for Concrete Coating Materials (Draft) (6) Crack Tracking Test Method," published in February 1984.

[0104] The coating composition of the present invention has an elongation of 50 to 400%, preferably 150 to 350%, and more preferably 200 to 300%, when used to form a coating film having a dry thickness of 300 μm.

[0105] Examples of methods for adjusting the elongation include adjusting the amount of silylated urethane resin in the coating film-forming components, preferably adjusting the amount of silylated urethane resin in the coating film-forming components to 50 to 95% by mass, and adjusting the amount of pigment component in the coating film-forming components, preferably adjusting the amount of pigment component in the coating film-forming components to 1 to 30% by mass, and these methods may be combined.

[0106] In this specification, the elongation rate can be measured in accordance with the Japan Road Association's "Guidelines for Salt Damage Prevention Measures for Road Bridges (Draft) and Commentary, Appendix 1. Quality Test Methods for Concrete Coating Materials (Draft) (6) Crack Tracking Test Method," published in February 1984.

[0107] The coating composition of the present invention has a coating film strength of 25 to 80 N and an elongation of 50 to 400% when formed into a coating film with a dry thickness of 300 μm. Therefore, by using the coating composition of the present invention in a peeling prevention method, it is possible to improve load resistance.

[0108] Examples of methods for simultaneously adjusting the coating film strength and elongation include combining the above-mentioned methods for adjusting the coating film strength and the method for adjusting the elongation. Preferred methods include adjusting the amount of silylated urethane resin in the coating film-forming components to 50 to 95% by mass, adjusting the mass ratio of silylated urethane resin (A) to crosslinker (B) to be in the range of (A) / (B) = 60 / 40 to 99 / 1, and adjusting the amount of pigment component in the coating film-forming components to 5 to 30% by mass. Particularly preferred is a method such as adjusting the amount of white carbon in the coating film-forming components to 1 to 15% by mass.

[0109] The coating composition of the present invention is applied at a shear rate of 0.1 s -1The viscosity at a temperature of 23°C is preferably 10 to 2000 Pa·s, more preferably 100 to 1000 Pa·s, and even more preferably 120 to 600 Pa·s. -1 The viscosity at a temperature of 23°C is preferably 0.05 to 3.0 Pa·s, and more preferably 0.05 to 2.5 Pa·s. By adjusting the viscosity of the coating composition of the present invention to fall within the above-specified range, it is possible to improve sagging properties when forming a thick film and improve coating workability.

[0110] In this specification, viscosity can be measured using a rotational viscometer (for example, a rheometer (such as the ARES rheometer manufactured by TA Instruments)).

[0111] The viscosity of the coating composition can be adjusted by using a viscosity modifier or an extender pigment. In particular, it is preferable to use an extender pigment, especially white carbon, to adjust the viscosity of the coating composition.

[0112] The coating composition of the present invention preferably contains a viscosity modifier. The viscosity modifier is preferably a polyacrylic acid-based viscosity modifier or a polyurethane-based viscosity modifier. Polyacrylic acid-based viscosity modifiers are, for example, amine salts, amide salts, or sodium salts of polymers obtained by polymerizing one or more acrylic components selected from acrylic acid or its esters, amides, and nitriles, and have multiple carboxyl groups or salts thereof within the molecule. Commercially available polyacrylic acid-based viscosity modifiers include Thixol K-130B (Kyoeisha, aqueous dispersion of aliphatic polyamide acrylic acid). Examples of polyurethane-based viscosity modifiers include compounds having a urethane moiety and a hydrophilic moiety within the molecule formed by the reaction of a hydroxyl group and an isocyanate group, compounds having a urea moiety and a hydrophilic moiety within the molecule formed by the reaction of an amino group and an isocyanate group, and compounds having a urethane moiety, a urea moiety, and a hydrophilic moiety within the molecule. Commercially available polyurethane viscosity modifiers include, for example, BYK-7420ES (BYK, urea-urethane solution).

[0113] The amount of viscosity modifier in the coating composition of the present invention is, for example, 0 to 3 mass %, and preferably 0.15 to 1.5 mass %. The viscosity modifier may be used alone or in combination of two or more.

[0114] The coating composition of the present invention preferably contains an extender pigment, such as calcium carbonate, silica, alumina, hydrated alumina, magnesia, talc, kaolin, clay, barium sulfate, barium carbonate, wollastonite, ceramic powder, glass fiber powder, white carbon, magnesium silicate, and silica sand. Of these, white carbon, talc, silica sand, calcium carbonate, silica, and barium sulfate are preferred, with white carbon being particularly preferred.

[0115] The amount of the extender pigment in the coating composition of the present invention is, for example, 1 to 15% by mass, preferably 1 to 10% by mass, and more preferably 1 to 5% by mass. The extender pigment may be used alone or in combination of two or more.

[0116] The coating composition of the present invention may contain a coloring pigment. Suitable examples of the coloring pigment include titanium oxide and carbon black. The amount of the coloring pigment in the coating composition of the present invention is, for example, 0 to 20% by mass, and preferably 0 to 10% by mass. The coloring pigment may be used alone or in combination of two or more types.

[0117] In the coating composition of the present invention, the proportion of the coating film-forming component is preferably 25 to 85 mass %, more preferably 35 to 80 mass %.

[0118] In this specification, the term "film-forming components" refers to the components excluding volatile components such as water, and are the components that ultimately form a coating film. In this specification, the components that remain after drying at 130°C for 30 minutes are considered to be film-forming components. The proportion (R) (mass%) of film-forming components in a paint composition is calculated using the following formula. Note that "film-forming components" can also be referred to as "non-volatile components." R = (mass of film-forming components) x 100 / (mass of coating composition)

[0119] The coating composition of the present invention can contain other components, such as other resins, surface conditioners, wetting agents, dispersants, emulsifiers, anti-settling agents, anti-skinning agents, defoamers, color-flux inhibitors, leveling agents, drying agents, plasticizers, preservatives, antifungal agents, antibacterial agents, insecticides, antiviral agents, light stabilizers, UV absorbers, antistatic agents, and conductivity-imparting agents, as appropriate depending on the purpose. Organic solvents may be used as additives, but from the viewpoint of reducing the environmental impact, the coating composition of the present invention preferably contains less than 10% by mass of organic solvent, more preferably less than 5% by mass, and most preferably contains no organic solvent.

[0120] The coating composition of the present invention can be prepared by mixing various components appropriately selected as needed. When the coating composition of the present invention is a two-component coating composition, the base agent and curing agent are prepared in advance and then mixed at the time of application. The base agent contains a silylated urethane resin and water, and may further contain a viscosity modifier, an extender pigment, etc. as needed. The curing agent contains, for example, a crosslinking agent, and may further contain water or other additives as needed.

[0121] The means for applying the coating composition of the present invention is not particularly limited, and known coating means such as brush coating, roller coating, trowel coating, spatula coating, flow coater coating, and spray coating (e.g., air spray coating, airless spray coating, etc.) can be used. However, when taking into consideration the coating of already constructed concrete structures, brush coating, roller coating, trowel coating, and spatula coating are preferred.

[0122] The coating composition of the present invention can be cured at ambient temperature, but may also be heated during curing. The coating composition of the present invention is preferably a cold-setting coating composition, and the temperature during application is preferably 5°C to 40°C.

[0123] The coating composition of the present invention is suitable for use in a method for preventing spalling, specifically a method for preventing spalling of concrete pieces. Preferably, the coating composition of the present invention is used to form a coating film comprising a fiber sheet. In such applications, the coating composition of the present invention is sometimes called an impregnating adhesive because it penetrates into the fiber sheet and fixes the fiber sheet.

[0124] A method for preventing concrete fragments from peeling off is described below. In one embodiment of the method for preventing concrete fragments from peeling off, a layered structure is formed on the surface of a concrete structure by applying a primer, applying an impregnating adhesive, installing a fiber sheet, applying an impregnating adhesive, and applying a topcoat paint in this order. It is preferable to prepare the concrete structure before applying the primer. The layered structure formed according to this embodiment comprises a layer formed from the primer, a layer containing a fiber sheet formed from the impregnating adhesive, and a layer formed from the topcoat paint. In this embodiment, the coating composition of the present invention is preferably used as the impregnating adhesive. Furthermore, for areas of severe unevenness on the painted surface of a concrete structure, it is preferable to add a step of filling in the unevenness of the painted surface using a polymer cement or the like (unevenness adjustment step) before applying the primer.

[0125] Concrete structures are structures that use concrete alone or reinforced concrete, and specific examples include various concrete structures and their components, such as viaducts, bridges, piers, abutments, girders, decks, parapets, dolphins, tunnels, roads, water channels, storage tanks, walls, roofs, and balconies. The Metropolitan Expressway Company's "Bridge Structure Design Guidelines: Concrete Piece Spalling Prevention Plates" (partially revised in August 2014) specifies that Type A applies to parapet sides with water cutouts and the undersides of overhanging decks with water cutouts, while Type B applies to parapet sides without water cutouts, the sides and undersides of crossbeams of bridge piers, the sides and undersides of girders, the ceilings and side walls of tunnels, and haunches.

[0126] The primer contains a resin, specific examples of which include acrylic resin, silicone resin, acrylic silicone resin, styrene-acrylic copolymer resin, polyester resin, fluororesin, rosin resin, petroleum resin, coumarone resin, phenolic resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, xylene resin, alkyd resin, aliphatic hydrocarbon resin, butyral resin, maleic acid resin, fumaric acid resin, vinyl resin, amine resin, and ketimine resin. The primer preferably contains the resin such that the amount of resin in the primer layer formed after application is, for example, 10 to 70 mass%. The resins may be used alone or in combination of two or more.

[0127] The primer preferably contains an epoxy resin. Epoxy resins have excellent adhesion to concrete structures. Examples of epoxy resins include bisphenol A epoxy resins, halogenated bisphenol A epoxy resins, novolac epoxy resins, polyglycol epoxy resins, bisphenol F epoxy resins, epoxidized oils, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether. Modified epoxy resins, such as amine-modified epoxy resins, isocyanate-modified epoxy resins, acrylic-modified epoxy resins, urethane-modified epoxy resins, and polyester-modified epoxy resins, are also included. Among these, bisphenol A epoxy resins and bisphenol F epoxy resins are preferred from the viewpoints of coating film durability and adhesion to concrete structures. The epoxy resins may be used alone or in combination of two or more.

[0128] The primer is preferably a water-based primer. In this specification, the term "water-based primer" refers to a primer containing water as a main solvent.

[0129] The primer may contain other components, such as other resins, curing agents, viscosity modifiers, pigments, surface modifiers, wetting agents, dispersants, emulsifiers, anti-settling agents, anti-skinning agents, defoamers, anti-color separation agents, leveling agents, drying agents, plasticizers, preservatives, anti-mold agents, antibacterial agents, insecticides, antiviral agents, light stabilizers, ultraviolet absorbers, antistatic agents, and conductivity imparting agents, as appropriate depending on the purpose.

[0130] The primer may be a one-component type or a two-component type, and is preferably a room temperature drying type or a room temperature curing type.

[0131] In the method for preventing concrete pieces from peeling off, the thickness of the layer formed from the primer is preferably 5 to 50 μm.

[0132] As described above, the coating composition of the present invention is preferably used as the impregnating adhesive. To form a layer containing a fiber sheet, it is preferable to apply the impregnating adhesive before and after placing the fiber sheet. The impregnating adhesives used in each application may be different, but are preferably the same.

[0133] In the method for preventing concrete fragments from peeling off, the thickness of the layer containing the fiber sheet formed from the impregnating adhesive is preferably 200 to 1000 μm, and the thickness of each layer formed from each coating of the impregnating adhesive is preferably 100 to 500 μm.

[0134] The fiber sheet may be a nonwoven fabric, but is preferably a lattice-shaped sheet. Examples of the fiber sheet include sheets made of fibers such as glass fiber, polyester fiber, vinylon fiber, polyamide fiber, polyethylene fiber, polyparaphenylene fiber, polyarylate fiber, aramid fiber, and carbon fiber, and among these, polyester fiber sheets are preferred.

[0135] The topcoat paint contains a resin, specific examples of which include acrylic resin, silicone resin, acrylic silicone resin, styrene-acrylic copolymer resin, polyester resin, fluororesin, rosin resin, petroleum resin, coumarone resin, phenolic resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, xylene resin, alkyd resin, aliphatic hydrocarbon resin, butyral resin, maleic acid resin, fumaric acid resin, vinyl resin, amine resin, ketimine resin, etc. The topcoat paint preferably contains the resin so that the amount of resin in the topcoat layer formed after application is, for example, 15 to 50 mass%. The resins may be used alone or in combination of two or more.

[0136] The resin that can be used in the topcoat paint may be a modified resin. Specific examples of modified resins include alkyl-modified, alkyl ether-modified, alkylphenol novolac-modified, acrylic-modified, fatty acid-modified, urethane-modified, amino-modified, isocyanate-modified, silicone-modified, and other modified resins such as graft-modified resins using allyl groups (preferably epoxy resins, hydroxyl-containing resins, etc.). Here, examples of hydroxyl-containing resins include hydroxyl-containing acrylic resins, hydroxyl-containing acrylic silicone resins, and hydroxyl-containing fluororesins. The topcoat paint preferably contains the modified resin so that the amount of the modified resin in the topcoat layer formed after application is, for example, 1 to 15% by mass.

[0137] The topcoat paint is preferably a paint for forming a layer containing a urethane resin. That is, the topcoat paint is preferably a paint containing a urethane resin or a paint containing a base agent containing a polyol and a curing agent containing a polyisocyanate. Urethane resins have excellent weather resistance.

[0138] The urethane resin can be obtained, for example, by reacting a polyol component, a polyisocyanate component, and optionally a chain extender, but the urethane resin contained in the layer formed from the topcoat paint is preferably a urethane resin obtained by reacting a polyisocyanate, a polycarbonate polyol, and a chain extender. The polyol component, polyisocyanate component, and chain extender here are as described in the explanation of the polyol component, polyisocyanate component, and chain extender for the silylated urethane resin above.

[0139] The top coat paint is preferably a water-based paint.

[0140] The topcoat paint may contain other components, such as other resins, curing agents, viscosity modifiers, pigments, surface conditioners, wetting agents, dispersants, emulsifiers, anti-settling agents, anti-skinning agents, defoamers, anti-color separation agents, leveling agents, drying agents, plasticizers, preservatives, anti-mold agents, antibacterial agents, insecticides, antiviral agents, light stabilizers, ultraviolet absorbers, antistatic agents, and conductivity imparting agents, as appropriate depending on the purpose.

[0141] The top coat paint may be a one-component type or a two-component type, and is preferably a room temperature drying type or a room temperature curing type.

[0142] In the method for preventing concrete pieces from peeling off, the thickness of the layer formed from the top coat paint is preferably 10 to 100 μm.

[0143] The means for applying the primer, impregnating adhesive, and topcoat paint are not particularly limited, and known application means such as brush application, roller application, trowel application, spatula application, flow coater application, and spray application (e.g., air spray application, airless spray application, etc.) can be used. However, when considering application to an already constructed concrete structure, brush application, roller application, trowel application, and spatula application are preferred.

[0144] The laminated structure formed by the anti-flaking method using the coating composition of the present invention preferably has a punching load of 1.5 kN or more, and more preferably 2.0 kN or more per 10 cm diameter, in a load-bearing test in accordance with the "Metropolitan Expressway Co., Ltd. Bridge Structure Design Guidelines, Concrete Fragment Flaking Prevention Edition, August 2006 Edition." There is no particular upper limit to the punching load per 10 cm diameter, but it is, for example, about 3 kN.

[0145] For the load-bearing test, for example, a U-shaped cover, designated as Type 1 (400 x 600 x 60 mm), as specified in JIS A 5372:2004 (precast reinforced concrete products) can be used as the concrete substrate. [Example]

[0146] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0147] ≪Materials used≫ The following materials were used to prepare the coating compositions: [Main ingredient] (1) Resin Silylated urethane dispersion-1 (Konishi Co., Ltd., Aqualinker SU-500, non-volatile content: 37.5% by mass) Silylated urethane dispersion-2 (Konishi Co., Ltd., Aqualinker SU-501A, non-volatile content: 35.0% by mass) Silylated urethane dispersion-3 (Konishi Co., Ltd., Aqualinker SU-100, non-volatile content: 30.0% by mass) Polyurethane dispersion (DAOTAN VTW 6462 / 36WA, manufactured by Daicel Allnex Co., Ltd., non-volatile content: 36% by mass) EVA resin (ethylene-vinyl acetate copolymer resin) emulsion (Sumikaflex S-355HQ, manufactured by Sumika Chemtex Co., Ltd., non-volatile content: 55% by mass) Epoxy resin emulsion (Mitsubishi Chemical Corporation, jER W1155R55, non-volatile content: 55% by mass) (2) Pigments White carbon (AEROSIL200, manufactured by Nippon Aerosil Co., Ltd.) Talc (Talc C, manufactured by Nippon Talc Co., Ltd.) Calcium carbonate (TF heavy calcium carbonate, manufactured by Maruo Calcium Co., Ltd.) Color pigment (a mixture of the following white and black pigments in a 100:1 ratio (by mass)) White pigment (Sakai Chemical Co., Ltd., TITONE R-5N) Black pigment (Mitsubishi Chemical Corporation, Mitsubishi Carbon Black MA-100) (3) Additives Viscosity adjuster (BYK-420, manufactured by BYK Japan Co., Ltd., non-volatile content: 52% by mass) Dispersant (BYK-011, manufactured by BYK Japan Co., Ltd., non-volatile content: 29% by mass) Antifoaming agent (BYK Japan Co., Ltd., DISPERBYK-190, non-volatile content: 40% by mass) [Hardening agent] (4) Crosslinking agent Carbodiimide crosslinking agent-1 (Nisshinbo Chemical Co., Ltd., Carbodilite E-05, non-volatile content: 40% by mass) Carbodiimide crosslinking agent-2 (Nisshinbo Chemical Co., Ltd., Carbodilite V-10, non-volatile content: 40% by mass) Carbodiimide crosslinking agent-3 (Nisshinbo Chemical Co., Ltd., Carbodilite E-02, non-volatile content: 40% by mass) Isocyanate-based crosslinking agent (Asahi Kasei Corporation, Duranate WE-100, non-volatile content: 100% by mass) Amine-based crosslinking agent (Mitsubishi Chemical Corporation, jER Cure WD11M60, non-volatile content: 60% by mass)

[0148] Examples and Comparative Examples The main components were prepared by stirring the main components using a disperser according to the formulations shown in Tables 1 and 2. The resulting main components and curing agent were mixed according to the formulations shown in Tables 1 and 2 to prepare coating compositions. The numerical values ​​for each component in the formulations in Tables 1 and 2 are in parts by mass. The "Film-forming components (%)" column in the tables indicates the amount (% by mass) of the film-forming components in the coating composition. The "Silylated urethane resin (A)," "Crosslinker (B)," and "Pigment" columns in the "Contents in Film-forming Components" column in the tables indicate the content (% by mass) of the silylated urethane resin (A) in the film-forming components of the coating composition, the content (% by mass) of the crosslinker (B) in the film-forming components of the coating composition, and the content (% by mass) of the pigment in the film-forming components of the coating composition, respectively. The "Silylated urethane resin (A) / Crosslinker (B)" column indicates the mass ratio of the silylated urethane resin (A) / crosslinker (B) in the coating composition.

[0149] [Table 1]

[0150] [Table 2]

[0151] <Measurement and evaluation methods> Various measurements and tests were carried out on each of the coating compositions of Examples 1 to 19 and Comparative Examples 1 to 7, and the results are shown in Tables 3 and 4. 1.Paint properties <Flash point measurement> Whether or not a flash point was detected was determined using the SETAFLASH SERIES3 FLASHPOINT TESTERS (Seta closed system) manufactured by STANHOPE-SETA Co., Ltd. In the table, if no flash point was detected, it is indicated as "None," and if a flash point was detected, it is indicated as "Yes."

[0152] <Viscosity measurement> Using a TA Instruments ARES rheometer, the viscosities were measured at shear rates of 0.1 (1 / s), 10 (1 / s), and 1000 (1 / s) (all at a temperature of 23°C). The measurement result at a shear rate of 0.1 (1 / s) was taken as the viscosity in the sagging region, and the measurement result at a shear rate of 1000 (1 / s) was taken as the viscosity during application.

[0153] 2.Coating film performance (single film) <How to prepare specimen A> The coating compositions of Examples 1 to 19 and Comparative Examples 1 to 7 were applied to a polypropylene (PP) plate using an applicator so that the dry film thickness was 300 μm, and the plate was cured at 23°C and 50% RH for 7 days to form an isolated film, and specimen A was obtained for each coating composition.

[0154] <Coating strength> Using the obtained specimen A, the coating strength was measured in accordance with the Japan Road Association's "Guidelines for salt damage prevention measures for road bridges (draft) and commentary, Appendix 1. Quality test methods for concrete coating materials (draft) (6) Crack follow-up test method" (published February 1984).

[0155] <Growth rate> Using the obtained specimen A, the elongation rate was measured in accordance with the Japan Road Association's "Guidelines for salt damage prevention measures for road bridges (draft) and commentary, Appendix 1. Quality test methods for concrete coating materials (draft) (6) Crack follow-up test method" (published February 1984).

[0156] <Crosslink density> The storage modulus of the obtained specimen A was measured under the following measurement conditions using a solid viscoelasticity measuring device (RSA-GII (manufactured by TA Instruments)), and the flat region storage modulus of the coating film was read to determine the crosslink density. Measurement conditions Temperature range: -50℃~200℃ Heating rate: 5℃ / min Measurement length: 20.0 mm Measurement width: 8.0 mm Frequency: 1Hz Distortion: 0.05%

[0157] 3. Evaluation <Sauce properties> The coating compositions of Examples 1 to 19 and Comparative Examples 1 to 7 were applied to the vertical surface of a PP plate (thickness 150 mm, width 70 mm) with a roller until sagging occurred, and after drying at 23°C and 50% RH for 168 hours, the film thickness measured at a position 20 mm from the top end of the PP plate was defined as the sagging limit and evaluated according to the following criteria. The film thickness was measured by peeling the coating from the PP plate and using a vernier caliper. 〇: Droop limit is 1000μm or more. △: The sagging limit is 700 μm or more and less than 1000 μm. ×: The sagging limit is less than 700 μm.

[0158] <Painting workability> A water-based epoxy resin primer (Water-based Epool, manufactured by Dai Nippon Toryo Co., Ltd.) was applied to the horizontal surface of a concrete substrate with a roller to a dry film thickness of 15 μm, and after drying at 23°C and 50% RH for 24 hours, the coating compositions of Examples 1 to 19 and Comparative Examples 1 to 7 were applied with a roller to a dry film thickness of 150 μm, and the results were evaluated according to the following criteria. The concrete substrate used was a U-shaped cover, designated Type 1 (400 × 600 × 60 mm), with a smooth surface as specified in JIS A 5372:2004 (Precast reinforced concrete products). ◯: The coating composition was easily applied, the finish was uniform, and it was easy to apply to the specified film thickness. Δ: The coating composition can be easily applied and finished uniformly, but it is difficult to apply to the specified film thickness. ×: The coating composition cannot be easily applied or does not achieve a uniform finish.

[0159] <Initial water resistance> The coating compositions of Examples 1 to 19 and Comparative Examples 1 to 7 were applied to a PP plate (thickness 150 mm, width 70 mm) to a dry film thickness of 300 μm, and after drying at 23°C and 50% RH for 12 hours, 5 ml of water at 23°C was dropped onto a part of the coating surface, and the coating surface after 24 hours was evaluated according to the following criteria. ◯: There was no cracking or swelling in the area where water was dropped, and there was no visible difference in hue compared to the area where water was not dropped. △: There was no cracking or swelling in the area where water was dropped, but there was a clear difference in hue from the area where water was not dropped. ×: Cracks and swelling were observed at the locations where water was dropped. The coating compositions of Examples 2 and 3 were evaluated as having initial water resistance inferior to the other Examples when the drying time was 12 hours, but when the drying time was 24 hours at 23°C and 50% RH, no cracking or swelling was observed where water was dripped. Therefore, under general coating conditions (for example, conditions in which a topcoat is applied the day after application of the coating composition of the present invention), the coating compositions of Examples 2 and 3 can be used without any problems.

[0160] <Pot life> For the coating compositions of Examples 1 to 19 and Comparative Examples 1 to 7, the base resin and curing agent were mixed together to a total of 300 g using an electric mixer until uniform, and the initial viscosity was measured using a BH-type rotational viscometer (manufactured by Tokyo Keiki Co., Ltd.) at 23°C and 50% RH. The compositions were then allowed to stand at 23°C and 50% RH, and the time until the viscosity measured using the BH-type rotational viscometer exceeded 130% of the initial viscosity was defined as the pot life, which was evaluated according to the following criteria. ○: Pot life is 180 minutes or more. △: Pot life is 90 minutes or more and less than 180 minutes. ×: Pot life is less than 90 minutes.

[0161] <Load-bearing capacity (multi-layer membrane)> A water-based epoxy resin primer (Epool, manufactured by Dai Nippon Toryo Co., Ltd.) was applied to the horizontal surface of a concrete substrate with a roller to a dry film thickness of 15 μm and dried at 23 °C, 50% RH for 24 hours. The coating compositions of Examples 1-19 and Comparative Examples 1-7 were then applied with a roller to a dry film thickness of 150 μm. A polyester fiber sheet (Polyester Crenet E4500, manufactured by Kurabo Industries Co., Ltd.) was then placed on the uncured coating film. The coating compositions of Examples 1-19 and Comparative Examples 1-7 were then applied with a roller to a dry film thickness of 150 μm and dried at 23 °C, 50% RH for 24 hours to form an intermediate coating layer. A water-based urethane resin topcoat (V-Top #100H, manufactured by Dai Nippon Toryo Co., Ltd.) was then applied with a roller to a dry film thickness of 30 μm and dried at 23 °C, 50% RH for 168 hours to form a laminate on the concrete substrate. Next, a spalling prevention performance test was conducted on the concrete substrate equipped with the laminate in accordance with the Metropolitan Expressway Co., Ltd. Bridge Structure Design Guidelines, Concrete Piece Spalling Prevention Edition, August 2006 Edition, and the load-bearing capacity was evaluated according to the following criteria. ○: Push-out load of 1.5kN or more per φ10cm. △: Punching load per φ10cm is 0.5kN or more to less than 1.5kN. ×: Punching load less than 0.5 kN per φ10 cm.

[0162] Table 3

[0163] Table 4

Claims

1. A composition comprising a silylated urethane resin (A), a crosslinking agent (B) that reacts with the silylated urethane resin (A), an extender pigment, and water, the silylated urethane resin (A) accounts for 50 to 95% by mass of the coating film-forming components; the mass ratio of the silylated urethane resin (A) to the crosslinking agent (B) is (A) / (B)=60 / 40 to 99 / 1; the amount of the extender pigment component in the coating film-forming components is 1 to 15% by mass, When the dry film thickness is 300 μm, the coating strength is 25 to 80 N, the elongation is 50 to 400%, and the crosslink density is 1.0 × 10 －４ (mol / cc) ~5.0×10 －３ (mol / cc).

2. The shear rate of the coating composition is 0.1 s －１ , viscosity at a temperature of 23°C is 10 to 2000 Pa·s, and shear rate is 1000 s －１ 2. The coating composition according to claim 1, characterized in that the viscosity at a temperature of 23°C is 0.05 to 3.0 Pa·s.

3. 3. The coating composition according to claim 1, wherein the coating composition has no flash point.

4. 4. The coating composition according to claim 1, wherein the crosslinking agent is a carbodiimide.

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