JP6859209B2 - Clear paint composition, clear coating film, base material with clear coating film, and concrete structure repair method, reinforcement method, and peeling prevention method. - Google Patents

Description

The present invention relates to a clear coating composition, a clear coating film, a substrate with a clear coating film, and a method for repairing and reinforcing a concrete structure and a method for preventing peeling.

Traditionally, concrete has been used in numerous structures and facilities such as viaducts, tunnels, harbor facilities, and dams that require long-term durability. However, such concrete structures are subject to expansion and contraction due to changes in environmental temperature and humidity such as frost damage and drying shrinkage, rusting of reinforcing bars in concrete due to salt damage and neutralization, and alkali-aggregate reaction. Deterioration progresses due to various factors, and there is a problem that the structure is cracked or concrete pieces are peeled off. In particular, it is desired to develop a simple construction method that can prevent the concrete pieces that have a high influence on a third party from peeling off.

Further, in a concrete structure in contact with seawater or fresh water such as a harbor facility or a dam, deterioration may progress rapidly due to water infiltrating into the inside from the cracked or peeled concrete piece. Further, since it is often difficult to completely dry such a large structure, it is desired that the structure can be constructed even if the construction target is a wet surface.

In order to solve such conventional problems, various methods for preventing the peeling of concrete structures have been proposed so far. For example, a continuous fiber sheet such as a glass cloth, a synthetic resin fiber sheet, or a carbon fiber sheet, as represented by Patent Document 1, has a concrete structure using an organic material (synthetic resin or the like) or an inorganic material such as cement. A method of pasting on the surface of an object is known. However, the method using the fiber sheet requires a great deal of labor and a long construction period because the fiber sheet is cut and attached according to the shape of the concrete structure, and the structure having a complicated shape or the like. There are problems that it is difficult to apply to the uneven surface and that the strength of the seam of the fiber sheet may be insufficient. On the other hand, Patent Document 2 describes an embodiment in which a urethane resin-based topcoat coating film is formed on an epoxy resin-based high-strength coating film containing vinylon fibers as a concrete peeling prevention method that can be easily applied. It is disclosed. Further, Patent Document 3 discloses a method for preventing peeling of a concrete structure using an epoxy resin composition that can be applied by a simple method such as roller coating or brush coating even if the object to be applied is a wet surface. There is.

JP-A-2002-256707 Japanese Unexamined Patent Publication No. 2005-015329 JP-A-2015-509195

Concrete has excellent durability, but deterioration progresses due to the various factors mentioned above, so regular maintenance inspections and repairs and reinforcements based on the deterioration are required. However, in the method for preventing the concrete structure from peeling off using the continuous fiber sheet disclosed in Patent Document 1 or the composition disclosed in Patent Documents 2 and 3, the deteriorated state of the concrete base material after construction. There was a problem that it was not easy to inspect. In Patent Document 2, it is proposed to visually check and repair the displacement of the coating film formed by the peeling of the concrete piece, but a method of visually checking the cracks in the concrete structure. Is not mentioned.

The present invention has been made in view of the above-mentioned problems, and has the flexibility to follow the cracks of the concrete structure when the concrete structure is cracked or the concrete pieces are peeled off, and the concrete. It is possible to form a tough coating film that prevents the pieces from falling, and it is also possible to form a coating film that can visually inspect the deterioration state of the concrete structure under the formed coating film. , A coating composition and a concrete structure that can form a coating film with excellent adhesion not only on a dry surface but also on a wet surface of a concrete structure by a simple method such as roller coating or brush coating. The purpose is to provide a method of preventing peeling.

As a result of diligent studies on a method for solving the above-mentioned problems, the inventor has found that the above-mentioned problems can be solved by using a coating composition having a specific composition, and has completed the present invention.
The configuration of the present invention is as follows.

<1> At least one epoxy resin selected from the group consisting of an alicyclic epoxy resin (a1), a bisphenol A type epoxy resin (a2), a bisphenol F type epoxy resin (a3), and a novolak type epoxy resin (a4). (A), bifunctional or higher epoxy resin (B) excluding epoxy resin (A), terminal reactive butadiene acrylonitrile copolymer (C), polyamide amine (D), organic fiber (E), and glass flakes (A). A clear coating composition containing F).
<2> As the bifunctional or higher functional epoxy resin (B) excluding the epoxy resin (A), at least one selected from the group consisting of sorbitol polyglycidyl ether (b1) and castor oil polyglycidyl ether (b2) is used. The clear coating composition according to <1>, which is characterized by containing.
<3> The clear coating composition according to <1> or <2>, which contains the oxyalkylene group-containing polyamide amine (d1) as the polyamide amine (D).
<4> The clear coating composition according to any one of <1> to <3>, wherein the organic short fiber (E) is a vinylon fiber.
<5> A clear coating film formed from the clear coating composition according to any one of <1> to <4>.
<6> A base material with a clear coating film containing the clear coating film and the base material according to <5>.
<7> A method for repairing and reinforcing a concrete structure in which the surface of a base material is covered with the clear coating film according to <5>.
<8> A method for preventing peeling of a concrete structure in which the surface of a base material is covered with the clear coating film according to <5>.
<9> A method for inspecting a concrete structure in which the surface of a base material is coated with the clear coating film according to <5>, and the deterioration state of the base material is visually confirmed from above the clear coating film.
<10> A method for producing a base material with a clear coating film, which comprises the following steps [1] and [2].
[1] Step of coating the base material with the clear coating composition according to any one of <1> to <4> to form a coating film [2] Obtained by the above step [1]. Step of drying the coating film to form a dry coating film

The clear paint composition according to the present invention (hereinafter, also simply referred to as a paint composition) has the flexibility to follow the cracks in the concrete structure when the concrete structure is cracked or the concrete pieces are peeled off. In addition, it is possible to form a tough coating film that prevents the concrete pieces from falling, and it is possible to visually inspect the deterioration state of the concrete structure under the formed coating film. A coating film having properties can be formed, and a coating film having excellent adhesion can be formed not only on a dry surface of a concrete structure but also on a wet surface by a simple method such as roller coating or brush coating. can do.

<Clear paint composition>
The clear coating composition of the present invention is selected from the group consisting of an alicyclic epoxy resin (a1), a bisphenol A type epoxy resin (a2), a bisphenol F type epoxy resin (a3) and a novolak type epoxy resin (a4). At least one type of epoxy resin (A), a bifunctional or higher epoxy resin (B) excluding the epoxy resin (A), a terminal-reactive butadiene acrylonitrile copolymer (C), a polyamide amine (D), and an organic substance. It contains a system fiber (E) and glass flakes (F).

From the viewpoint of storage stability and the like, the clear coating composition of the present invention is a two-component composition composed of a main component and a curing agent component contained so as not to come into contact with each other, or a main component, a curing agent component and at least one. It is preferable that the composition is a multi-component type composed of the three third components.

For example, in the case of a multi-component composition, the main component is an acrylonitrile epoxy resin (a1), a bisphenol A type epoxy resin (a2), a bisphenol F type epoxy resin (a3), and a novolak type epoxy resin (a4). It contains at least one epoxy resin (A) selected from the group consisting of, and a bifunctional or higher epoxy resin (B) excluding the epoxy resin (A), and the curing agent component is a terminal-reactive butadiene acrylonitrile copolymer. An embodiment containing (C) and polyamide amine (D) and containing an organic fiber (E) and a glass flake (F) in any of the main agent component, the curing agent component and the third component can be mentioned. When forming a clear coating film, a coating composition obtained by mixing a main component, a curing agent component and a third component is used.

Further, the coating composition according to the present invention is optionally a monofunctional epoxy resin (G) or a silane coupling agent (H) that contributes to improving coating workability and physical properties of a clear coating film formed from the composition. ) Are preferably contained, and other components described later can be contained within a range that does not impair the object of the present invention.

Here, the clear coating composition is a coating composition capable of visually confirming the characters written on the concrete base material through a coating film (dry coating film thickness 2000 μm) formed from the composition on the concrete structure. Say.

<Epoxy resin (A)>
The epoxy resin (A) is at least selected from the group consisting of an alicyclic epoxy resin (a1), a bisphenol A type epoxy resin (a2), a bisphenol F type epoxy resin (a3) and a novolak type epoxy resin (a4). It is a kind of epoxy resin.

The alicyclic epoxy resin (a1) is long as it has two or more epoxy groups in one molecule and one or more saturated or unsaturated carbon rings having no aromaticity. Although not particularly limited, for example, a hydrogenated epoxy resin obtained by hydrogenating an aromatic ring-containing epoxy resin (hereinafter, also referred to as hydrogenation) can be mentioned, and more specifically, hydrogenated bisphenol A type. Examples thereof include epoxy resins and hydrogenated bisphenol F-type epoxy resins. The alicyclic epoxy resin (a1) may be used alone or in combination of two or more.

As the alicyclic epoxy resin (a1), when the coating composition of the present invention is applied to a concrete structure, it is possible to form a coating film in which the visibility of the concrete structure is not easily deteriorated due to yellowing of the coating film. , One or more selected from hydrogenated bisphenol A type epoxy resin and hydrogenated bisphenol F type epoxy resin is preferable from the viewpoint of being able to form a coating film having excellent flexibility to follow cracks in a concrete structure. Yes, more preferably a hydrogenated bisphenol A type epoxy resin.

The alicyclic epoxy resin (a1) may be obtained by synthesizing it by a conventionally known method, or may be a commercially available product. Examples of the synthesis method include a method of hydrogenating the aromatic ring-containing epoxy resin in the presence of a hydrogenation catalyst such as ruthenium or rhodium and under pressure. In addition, as the above-mentioned commercial products, "Adecaledin EP-4080E" (manufactured by Adeca Co., Ltd., epoxy equivalent 200 to 230 g / eq), which is a hydrogenated bisphenol A type epoxy resin, and EPALLOY 5000 (manufactured by CVC Thermoset Specialties, epoxy equivalent). 210-230 g / eq) and the like.

The bisphenol A type epoxy resin (a2) is not particularly limited as long as it has two or more epoxy groups in one molecule and has a bisphenol A structure, but for example, bisphenol A diglycidyl ether. , Bisphenol A ethylene oxide diglycidyl ether, bisphenol A polypropylene oxide diglycidyl ether and the like, and preferred are bisphenol A diglycidyl ethers.

The bisphenol A type epoxy resin (a2) may be obtained by synthesizing by a conventionally known method, or may be a commercially available product. Examples of the commercially available product include NPEL-128 (manufactured by NANYAEPOXY Corp., epoxy equivalent: 185 to 186.5 g / eq).

The bisphenol F type epoxy resin (a3) is not particularly limited as long as it has two or more epoxy groups in one molecule and has a bisphenol F structure, but for example, bisphenol F diglycidyl ether. , Bisphenol F ethylene oxide diglycidyl ether, bisphenol F polypropylene oxide diglycidyl ether and the like, and preferred are bisphenol F diglycidyl ethers.

The bisphenol F type epoxy resin (a3) may be obtained by synthesizing it by a conventionally known method, or may be a commercially available product. Examples of the commercially available product include Adeka Resin EP-4901 (manufactured by Adeka Corporation, epoxy equivalent: 210-230 g / eq).

The novolak type epoxy resin (a4) is not particularly limited as long as it has two or more epoxy groups in one molecule and has a novolak structure. For example, phenol novolac resin and epichlorohydrin. Examples thereof include a phenol novolac epoxy resin which is a polycondensate of the above, a cresol novolac epoxy resin which is a polycondensate of a cresol novolak resin and epichlorohydrin, and the like, and a phenol novolac epoxy resin is preferable.

The novolak type epoxy resin (a4) may be obtained by synthesizing by a conventionally known method, or may be a commercially available product. Examples of the commercially available product include "EPALLOY 8250" (manufactured by CVC Thermoset Specialties, phenol novolac epoxy resin, epoxy equivalent 165 to 178 g / eq).

The epoxy resin (A) is preferably liquid at room temperature (15 to 25 ° C., the same applies hereinafter), and preferably has an epoxy equivalent calculated in accordance with JIS K 7236 (perchloric acid titration method). Is 100 to 350 g / eq, more preferably 150 to 300 g / eq, and particularly preferably 160 to 280 g / eq.

The refractive index of the epoxy resin (A) is usually 1.50 to 1.65, preferably 1.51 to 1.60. When the refractive index of the epoxy resin (A) is in the above range, it is about the same as the refractive index of the glass flakes (F) described later. Therefore, from the clear coating film of the present invention formed on the concrete structure, It becomes easy to visually confirm the deteriorated state of the concrete structure. The refractive index in the present invention shall be measured in accordance with JIS K 0062.

The content of the epoxy resin (A) is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, based on 100% by mass of the non-volatile content of the coating composition of the present invention.
When the base material such as a concrete structure coated with the coating film of the epoxy resin (A) is exposed to sunlight or the like, the visibility of the base material is lowered due to yellowing or whitening of the coating film. From the viewpoint of suppressing, the alicyclic epoxy resin (a1) is preferable. More specifically, in a weather resistance test based on the xenon lamp method specified in JIS K5600, the color difference measured with a spectrophotometer (manufactured by JUKI Denshi Kogyo Co., Ltd., model "JP7100F") even after 500 hours. From the point that (ΔE) is less than 10, and a coating film having a gloss retention rate of 70% or more at 60-degree gloss measured by a gloss meter (manufactured by BYK, model “micro-TRI-gloss”) can be formed. The epoxy resin (A) is preferably an alicyclic epoxy resin (a1).

Further, the epoxy resin (A) tends to easily obtain crack followability and peeling prevention performance of the formed coating film on the base material, so that it is an alicyclic epoxy resin (a1) and a bisphenol A type. It is preferably any one of the epoxy resins (a2), and more preferably the alicyclic epoxy resin (a1).

<Bifunctional or higher epoxy resin (B) excluding epoxy resin (A)>
The bifunctional or higher functional epoxy resin (B) other than the epoxy resin (A) is not particularly limited as long as it has two or more epoxy groups in one molecule, and a conventionally known epoxy resin is used. Can be done. By using the epoxy resin (B) in the coating composition of the present invention, the crosslink density between the epoxy group and the amino group is improved, and the clear coating film has sufficient toughness to prevent the concrete pieces from peeling off. Can be formed. Examples of such an epoxy resin (B) include diethylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, trimethylpropanpolyglycidyl ether, 1,4-butanediol diglycidyl ether, and 1,6-hexanediol diglycidyl ether. Examples thereof include neopentyl glycol diglycidyl ether, sorbitol polyglycidyl ether, and caster oil polyglycidyl ether. The epoxy resin (B) may be used alone or in combination of two or more.

The epoxy resin (B) is preferably liquid at room temperature, and the epoxy equivalent calculated in accordance with JIS K 7236 (perchloric acid titration method) is preferably 140 to 800 g / eq, more preferably 140 to 800 g / eq. It is 150 to 700 g / eq, particularly preferably 170 to 650 g / eq.

The refractive index of the epoxy resin (B) is preferably the same as the refractive index of the epoxy resin (A) and the glass flakes (F) described later.
The epoxy resin (B) may be obtained by a conventionally known method or may be a commercially available product. Examples of the commercially available product include, as a bifunctional aliphatic epoxy resin, "Adecaglycyrol ED-503" which is a 1,6-hexanediol diglycidyl ether (manufactured by Adeca Co., Ltd., epoxy equivalent 165 g / eq). "Denacol EX212L" (manufactured by Nagase ChemteX Corporation, epoxy equivalent 135g / eq); "Denacol EX-214L" (same as above, epoxy equivalent 115g / eq), which is a 1,4-butanediol diglycidyl ether; Glysidyl ether "Denacol EX-850L" (same as above, epoxy equivalent 122g / eq); neopentyl glycol diglycidyl ether "Adecaglycyrol ED-523T" (manufactured by Adeca Co., Ltd., epoxy equivalent 140g / eq), Examples thereof include "Denacol EX-211L" (manufactured by Nagase ChemteX Corporation, epoxy equivalent 130 g / eq), and as a trifunctional or higher polyfunctional aliphatic epoxy resin, "Adecaglycyllol" which is trimethylpropanpolyglycidyl ether. ED-505 "(Adeca Co., Ltd., epoxy equivalent 150 g / eq)," Denacol EX-321 "(Nagase Chemtex Co., Ltd., epoxy equivalent 140 g / eq); caster oil polyglycidyl ether" Erisys GE- 35 ”(CVC Thermoset Specialties, epoxy equivalent 550-650 g / eq); sorbitol polyglycidyl ether“ Erisys GE-60 ”(CVC Thermoset Specialties, etc., epoxy equivalent 160-180 g / q).

Such an epoxy resin (B) is preferably at least one selected from sorbitol polyglycidyl ether (b1) and castor oil polyglycidyl ether (b2).

More specifically, the epoxy resin (B) has different preferred embodiments depending on the type of the epoxy resin (A), and the clear coating composition of the present invention is selected from the group consisting of the following (i) to (iv). It is preferable that at least one condition is satisfied.

(I) The epoxy resin (A) contains an alicyclic epoxy resin (a1), and the epoxy resin (B) contains a sorbitol polyglycidyl ether (b1).
(Ii) The epoxy resin (A) contains a bisphenol A type epoxy resin (a2), and the epoxy resin (B) contains castor oil polyglycidyl ether (b2).
(Iii) The epoxy resin (A) contains a bisphenol F type epoxy resin (a3), and the epoxy resin (B) contains castor oil polyglycidyl ether (b2).
(Iv) The epoxy resin (A) contains a novolak type epoxy resin (a4), and the epoxy resin (B) contains castor oil polyglycidyl ether (b2).

Under the condition (i), the sorbitol glycidyl ether (b1) imparts toughness to the formed clear coating film, and under the conditions (ii) to (iv), the castor oil polyglycidyl ether (b2). ) Gives flexibility to the formed coating film and improves the peeling prevention performance of the concrete base material.
The content of the epoxy resin (B) is preferably 3 to 30% by mass, more preferably 5 to 25% by mass, based on 100% by mass of the non-volatile content of the coating composition of the present invention.

<Terminal reactive butadiene acrylonitrile copolymer (C)>
The terminally reactive butadiene acrylonitrile copolymer (C) has an acrylonitrile polybutadiene skeleton in the main chain and an epoxy group or a functional group that reacts with an epoxy group (for example, an amino group, a carboxyl group, etc.) at the terminal. The terminal-reactive butadiene acrylonitrile copolymer (C) may be used alone or in combination of two or more.

The terminal-reactive butadiene acrylonitrile copolymer (C) imparts flexibility to the clear coating film formed from the composition of the present invention, and the clear coating film adheres to the concrete substrate and has crack followability. Can be improved. Generally, a coating film formed from a coating composition containing a rubber component such as a non-reactive butadiene acrylonitrile copolymer has excellent flexibility, but tends to have poor water resistance. On the other hand, the coating composition of the present invention containing the terminally reactive butadiene acrylonitrile copolymer (C) has the epoxy resin (A), the epoxy resin (B), or the polyamide amine (D) described later at the time of forming the coating film. ), The above-mentioned problem of reduced water resistance does not occur.

The content of the terminally reactive butadiene acrylonitrile copolymer (C) is preferably 1 to 6% by mass, more preferably 2 to 5% by mass, based on 100% by mass of the non-volatile content of the coating composition of the present invention. .. If the content of the terminally reactive butadiene acrylonitrile copolymer (C) is less than 1% by mass, the flexibility of the formed clear coating film becomes insufficient, and if it is more than 6% by mass, the coating composition Since the viscosity becomes too high, the coating workability is reduced. Further, in the coating composition of the present invention, when the coating workability is lowered, bubbles are likely to be generated at the time of coating, and the bubbles remain as bubbles in the formed clear coating film, so that the visibility of the concrete base material is visible. It tends to lead to a decrease in the amount of water.

The terminally reactive butadiene acrylonitrile copolymer (C) may be obtained by a conventionally known method or may be a commercially available product. Examples of the commercially available products include "Hypro 1300X16 ATBN" and "Hypro 1300X42 ATBN" which are amino group-terminated butadiene acrylonitrile copolymers; "Hypro 1300X8 CTBN" and "Hypro 1300X31 CTBN" which are carboxyl group-terminated butadiene acrylonitrile copolymers. Etc .; Examples thereof include "HyproRA840" which is an epoxy group-terminated butadiene acrylonitrile copolymer (all of which are manufactured by CVC Thermoset Specialties) and the like.

<Polyamide amine (D)>
The polyamide amine (D) is not particularly limited, and dehydration condensation of an amine compound such as an aliphatic amine, an alicyclic amine, an aromatic amine, an aromatic aliphatic amine, or a heterocyclic amine with a carboxylic acid such as dimer acid. Things can be mentioned. Such a polyamide amine (D) may be used alone or in combination of two or more.

Examples of the aliphatic amine include alkylene polyamines, polyalkylene polyamines, and alkylaminoalkylamines.
The alkylene polyamine is, for example, the formula: "H ₂ N-R ^1- NH ₂ " (R ¹ is a divalent hydrocarbon group having 1 to 12 carbon atoms, and any hydrogen atom of the hydrocarbon group can be used. , May be substituted with a hydrocarbon group having 1 to 10 carbon atoms.) Specific examples thereof include methylenediamine, ethylenediamine, 1,2-diaminopropane, and 1,3-diaminopropane. , 1,4-Diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, trimethyl Hexamethylenediamine and the like can be mentioned.

Examples of the polyalkylene polyamine include the formula: "H ₂ N- (C _m H _2m NH) _n H" (m is an integer of 1 to 10, n is an integer of 2 to 10, preferably 2 to 6). ), Specifically, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripropylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylenehexamine, nonaethylenedecamine, Examples thereof include bis (hexamethylene) triamine.

Examples of other aliphatic amines include tetra (aminomethyl) methane, tetrakis (2-aminoethylaminomethyl) methane, 1,3-bis (2'-aminoethylamino) propane, and 2,2'-[. Ethylenebis (iminotrimethyleneimino)] Bis (ethaneamine), tris (2-aminoethyl) amine, bis (cyanoethyl) diethylenetriamine, polyoxyalkylenepolyamine (particularly diethyleneglycolbis (3-aminopropyl) ether) and the like can be mentioned. ..

Examples of the alicyclic amine include bis (aminomethyl) cyclohexane (particularly 1,3-bisaminomethylcyclohexane), 1,4-cyclohexanediamine, 4,4'-methylenebis (cyclohexaneamine), and 4,4'-isopropi. Examples thereof include redenbis (cyclohexaneamine), norbornandiamine, isophoronediamine, mensendiamine (MDA) and the like.

Examples of the aromatic amine include an aromatic polyamine compound having two or more primary amino groups bonded to a benzene ring.
More specifically, such aromatic amines include phenylenediamine, naphthylenediamine, diaminodiphenylmethane, 2,2-bis (4-aminophenyl) propane, 4,4'-diaminodiphenyl ether, 4,4'-. Diaminobenzophenone, 4,4'-diaminodiphenylsulfone, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 2,4'-diaminobiphenyl, 2,3'-dimethyl-4,4'-diaminobiphenyl, Examples thereof include 3,3'-dimethoxy-4 and 4'-diaminobiphenyl.

Examples of the aromatic aliphatic amine include bis (aminoalkyl) benzene and bis (aminoalkyl) naphthalene.
More specifically, as such aromatic aliphatic amines, o-xylylenediamine, m-xylylenediamine (MXDA), p-xylylenediamine, bis (aminomethyl) naphthalene, bis (aminoethyl) naphthalene and the like. Can be mentioned.

Examples of heterocyclic amines include N-methylpiperazine, morpholine, 1,4-bis- (3-aminopropyl) piperazine, 1,4-diazacycloheptane, 1- (2'-aminoethylpiperazine), 1-. [2'-(2" -aminoethylamino) ethyl] piperazin, 1,11-diazacycloeikosan, 1,15-diazacyclooctacosane and the like can be mentioned.
Examples of other amine compounds include amines described in JP-A-49-48480.

In addition, the dimer acid is a dimer of unsaturated fatty acids and usually contains a small amount of a monomer or a trimer. The unsaturated fatty acid preferably has 12 to 24 carbon atoms including carbon atoms of the carboxyl group, more preferably 16 to 18 carbon atoms, and has one unsaturated bond in one molecule. Alternatively, a carboxylic acid compound having two or more is desirable. Examples of such unsaturated fatty acids include fatty acids having one unsaturated bond such as oleic acid, elaidic acid and setoleic acid; fatty acids having two unsaturated bonds such as sorbic acid and linoleic acid; linoleic acid and arachidone. Examples thereof include fatty acids having three or more unsaturated bonds such as acids. Further, fatty acids obtained from animals and plants can also be used, and examples thereof include soybean oil fatty acid, tall oil fatty acid, and linseed oil fatty acid.

Examples of the polyamide amine (D) include the following modified polyamide amines, such as amine adducts with epoxy compounds, Mannich compounds (eg, Mannich-modified polyamide amines, phenylcamides, etc.), Michael adducts, and urethane-modified products. Etc. can be used.

The viscosity at 25 ° C. measured with such a polyamide amine (D) B-type viscometer (manufactured by HAAKE, Viscotester model "VT6plus") is preferably from the viewpoint of excellent handleability, coating workability, and the like. It is in the range of 100 to 100,000 mPa · s, more preferably 500 to 10,000 mPa · s.

The coating composition of the present invention may contain at least a polyoxyalkylene group-containing polyamide amine (d1) among the polyamide amines (D), that is, a polyoxyalkylene group-containing polyamide amine (d1) on the wet surface of the concrete structure. It is particularly preferable from the viewpoint of workability and adhesion to the concrete substrate and from the viewpoint of crack followability to the concrete base material.

The polyamide amine (D) may be obtained by a conventionally known method or may be a commercially available product. Examples of the commercially available product include "sanmide 75" which is an aliphatic polyamide amine; "Ancamide 2353" and "Ancamide 2396" which are alicyclic polyamide amines (all of which are manufactured by Air Products Japan Co., Ltd.) and the like. Polyamide amine adducts "Tomide 213A", "Tomide 238" (all manufactured by T & K TOKA Co., Ltd.), "Versamide 230" (manufactured by BASF Japan Co., Ltd.), etc .; Polyoxyalkylene polyamines are polycarboxylic acids. Examples thereof include "Ancamide 910" (manufactured by Air Products Japan Co., Ltd.), which is a polyamide amine modified with.
In addition to the polyamide amine (D), a conventionally known amine compound other than the polyamide amine (D) may be used in combination as long as the effects of the present invention are not impaired.

In the coating composition of the present invention, the epoxy resin (A), the epoxy resin (B) excluding the epoxy resin (A), and the monofunctional epoxy resin (G) described later (hereinafter, these are collectively referred to as "epoxy component". The total content of the polyamide amine (D) and an amine compound other than the polyamide amine (D) (hereinafter, these are also collectively referred to as “amine component”) is the visibility of the substrate. From the viewpoint of being excellent in flexibility and easily obtaining a tough coating film, it is preferably 40 to 90% by mass, more preferably 50% with respect to 100% by mass of the non-volatile content of the coating composition of the present invention. ~ 85% by mass.

The content of the polyamide amine (D) is such that the reaction ratio calculated from the following formula (1) is preferably 0.7 to 1.2, more preferably 0.8 to 1.1. When the reaction ratio is in the above range, the coating film formed from the composition of the present invention tends to be excellent in toughness and crack followability to the concrete base material.

Reaction ratio = (Amine component compounding amount / Amine component active hydrogen equivalent + Amine component compounding amount / Epoxy component reactive component functional group equivalent) / (Epoxy component / Epoxy equivalent of the epoxy component + Amount of the component having a reactivity with the amine component / Amount of the functional group of the component having a reactivity with the amine component) ... (1)
Here, for example, when a plurality of types of epoxy components are contained, more specifically, when the epoxy resin (A) and the epoxy resin (B) are contained, the blending amount of the epoxy resin (A) / the epoxy equivalent thereof. , And the compounding amount of the epoxy resin (B) / the epoxy equivalent thereof are calculated, and the calculation results are totaled to calculate the “blending amount of the epoxy component / the epoxy equivalent of the epoxy component”.

The "component having reactivity with the epoxy component" and the "component having reactivity with the amine component" in the formula (1) include, for example, the terminal-reactive butadiene acrylonitrile copolymer (C). And the silane coupling agent (H) described later can be mentioned. The "functional group equivalent" of each of the components means the mass (g) per functional group in 1 mol of these components. In the present invention, the terminal reactive butadiene acrylonitrile copolymer (C) and the silane coupling agent (H) are an epoxy group or a functional group that reacts with an epoxy group (for example, an amino group or a carboxyl group) as a reactive group. Etc.), so it is necessary to determine whether it is reactive with the epoxy resin or with the amine curing agent and calculate the reaction ratio depending on the type of reactive group. ..

<Organic fiber (E)>
The organic fiber (E) is, for example, a fiber made of synthetic resin fibers such as nylon, vinylon, aramid, polypropylene, and acrylic. Among these, vinylon fiber is preferable from the viewpoint of being more excellent in miscibility with the epoxy resin (A) and the epoxy resin (B). As described above, the organic fiber (E) is excellent in miscibility with the coating film forming component, so that the formed coating film exhibits excellent peeling prevention performance of the concrete base material.

Further, the organic fiber (E) is preferably formed by using an organic fiber (E) having an average fiber length of 2.0 mm or less and 0.3 mm or more, and an average fiber length in the above range. It is difficult to reduce the visibility of the base material due to the clear coating film, and it is possible to impart toughness to prevent the concrete pieces from peeling off. Such an organic fiber (E) may be used alone or in combination of two or more.

The average fiber length of the organic fiber (E) is the number obtained by observing the length (fiber length) in the long side direction of the fiber with a digital microscope (manufactured by Keyence Co., Ltd., model "VHX-900"). By measuring the lengths of ten to several hundred fibers, it can be calculated as the average value. The content of the organic fiber (E) is preferably 1 to 10% by mass, more preferably 3 to 8% by mass, based on 100% by mass of the non-volatile content of the coating composition of the present invention. If the content of the organic fiber (E) is less than 1% by mass, the toughness of the formed clear coating film may be insufficient, and if it is more than 10% by mass, the group of the clear coating film formed. The visibility of the material may be insufficient.

<Glass flakes (F)>
The glass flakes (F) have a median diameter (D50) of preferably 20 to 140 μm, more preferably 25 to 100 μm, and particularly have an aspect ratio (median diameter (D50) / average thickness of particles). , 2-35, more preferably 2.5-30. When the aspect ratio is in the above range, the coating workability of the obtained coating composition is excellent, the hiding rate of the formed coating film is low, and the visibility of the base material is excellent. Such glass flakes (F) may be used alone or in combination of two or more.

As described above, the aspect ratio of the glass flakes (F) can be calculated from the average thickness of the particles of the D50 and the glass flakes (F). D50 can be measured using a laser scattering diffraction type particle size distribution measuring device (manufactured by Shimadzu Corporation, model "SALD 2200"). The average thickness of the particles is observed from the horizontal direction with respect to the main surface of the glass flakes (F) using a scanning electron microscope (SEM) (manufactured by Phillips, model "XL-30"). By measuring the thickness of tens to hundreds of particles, it can be calculated as the average value.

The refractive index of the glass flakes (F) is usually 1.40 to 1.70, more preferably 1.45 to 1.65, and particularly preferably 1.50 to 1.60. When the refractive index of the glass flakes (F) is in the above range, the refractive index becomes about the same as the refractive index (1.50 to 1.65) of the epoxy resin (A) and the epoxy resin (B). , It is possible to form a clear coating film having more excellent visibility of the base material.

The content of the glass flakes (F) is preferably 8 to 30% by mass, more preferably 10 to 20% by mass, based on 100% by mass of the non-volatile content of the coating composition of the present invention. If the content of the glass flakes (F) is less than 8% by mass, the toughness of the formed clear coating film may be insufficient, and if it is more than 30% by mass, the coating workability of the coating composition is poor. May become.

<Monofunctional epoxy resin (G)>
The monofunctional epoxy resin (G) is not particularly limited, and is an epoxy resin having one epoxy group in one molecule. By using the epoxy resin (G) in the composition of the present invention, the viscosity of the composition can be reduced without lowering the non-volatile content of the composition, and high solid differentiation of the composition becomes possible. Painting workability can be improved. Further, as the coating workability is improved, the number of bubbles generated during coating is reduced, and the visibility of the base material of the formed clear coating film tends to be improved. Such an epoxy resin (G) may be used alone or in combination of two or more.

Examples of the monofunctional epoxy resin (G) include phenylglycidyl ether, alkyl glycidyl ether (the alkyl group has 1 to 15 carbon atoms, preferably 11 to 15 carbon atoms), and glycidyl ester (R ¹ R ² R). ³ C-COO-Gly, where ^{the total number of carbon atoms of the alkyl groups represented by R 1} , R ² and R ³ is 8 to 10, where Gly represents a glycidyl group), α-olefin epoxiside (CH). _3- (CH ₂ ) _n- Gly, where n is an integer of 11 to 13 and Gly represents a glycidyl group), alkylphenyl glycidyl ether (alkyl group has 1 to 20, preferably 1 to 20 carbon atoms). Example: Methylphenyl glycidyl ether, ethylphenyl glycidyl ether, propylphenyl glycidyl ether), alkylphenol glycidyl ether (the number of carbon atoms of the alkyl group is 1 to 20) and the like.

As the monofunctional epoxy resin (G), one obtained by synthesizing by a conventionally known method may be used, or a commercially available product may be used. Examples of the commercially available products include "Epodil 759" (manufactured by Air Products Japan Co., Ltd., alkyl (C12-C13) glycidyl ether, epoxy equivalent 275-290 g / eq), "Cardlite Lite2513HP" (manufactured by Cardlite, alkyl (Cardlite). C15) Phenolic glycidyl ether, epoxy equivalent 375-450 g / eq), "GE-10" (manufactured by CVC Thermoset Specialties, o-cresyl glycidyl ether, epoxy equivalent 170-195 g / eq) and the like.

When the monofunctional epoxy resin (G) is used, its content is preferably 0.5 to 5% by mass, more preferably 1 to 4% by mass, based on 100% by mass of the non-volatile content of the coating composition of the present invention. Included in% amount. If the content of the monofunctional epoxy resin (G) is more than 5% by mass, the toughness of the formed clear coating film may be insufficient.

<Silane coupling agent (H)>
The silane coupling agent (H) is not particularly limited, and conventionally known ones can be used. However, the silane coupling agent (H) has at least two hydrolyzable groups in the same molecule to improve the adhesion to the substrate and to improve the adhesion to the substrate. , It is preferable that the compound can contribute to the reduction of the viscosity of the coating material, and it is more preferable that the compound is represented by the following formula.

X-SiMe _n Y _3-n
[N is 0 or 1, and X is a reactive group capable of reacting with an organic substance (eg, amino group, vinyl group, epoxy group, mercapto group, halogeno group, and some of the hydrocarbon groups are these groups. A substituted group or a group in which a part of the hydrocarbon group is substituted with an ether bond or the like is partially substituted with these groups), Me is a methyl group, and Y is hydrolyzed. Indicates a sex group (eg, an alkoxy group such as a methoxy group or an ethoxy group). ]

Such a silane coupling agent (H) may be used alone or in combination of two or more.
As the silane coupling agent (H), a silane coupling agent having an epoxy group as a reactive group is preferable, and specifically, "KBM-403" (Shin-Etsu Chemical), which is γ-glycidoxypropyltrimethoxysilane. Examples include (manufactured by Kogyo Co., Ltd.) and "Silane Ace S-510" (manufactured by JNC Co., Ltd.).

When the silane coupling agent (H) is used, its content is preferably 0.1 to 10% by mass, more preferably 0.1 to 5 with respect to 100% by mass of the non-volatile content of the coating composition of the present invention. Included in mass%. By using the silane coupling agent (H) in the coating composition of the present invention in an amount in the above range, the coating film performance such as the adhesion of the formed clear coating film to the substrate is improved, and the coating composition The viscosity of the object is reduced and the painting workability is improved.

<Other ingredients>
In addition to the various components described above, the coating composition of the present invention contains, if necessary, an extender pigment, a solvent, a dripping / anti-settling agent, a curing accelerator, a dispersant, a surface conditioner, and a leveling agent. , Antifoaming agent, inorganic dehydrating agent (stabilizer) and the like may be blended within a range that does not impair the object of the present invention.

[Constitution pigment]
Examples of the extender pigment include calcium carbonate, potassium feldspar, kaolin, clay, talc, barium sulfate, magnesium carbonate, silica powder and the like. Of these, calcium carbonate, potassium feldspar, and silica powder are preferable. Such extender pigments may be used alone or in combination of two or more.

〔solvent〕
The solvent is not particularly limited, and conventionally known solvents can be used. For example, xylene, toluene, methyl isobutyl ketone, methyl ethyl ketone, butyl acetate, n-butanol, i-butanol, isopropyl alcohol, benzyl alcohol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and the like can be mentioned. The solvent may be used alone or in combination of two or more.

In the coating composition of the present invention, the content of the solvent is not particularly limited, but when the solvent is used in consideration of the coating workability of the selected coating method, the settling prevention property of the pigment during storage, and the like, the present invention It is contained in the coating composition of the present invention in an amount of preferably 1 to 40% by mass, more preferably 3 to 30% by mass.
Further, when applying to a wet surface, among the above-mentioned solvents, a solvent having hydrophilicity such as isopropyl alcohol and propylene glycol monomethyl ether is preferable.

[Anti-sag / sedimentation inhibitor]
The anti-dripping agent / anti-sedimentation agent can impart thixotropy to the composition of the present invention and improve the adhesion of the composition to the substrate. The dripping inhibitor / sedimentation inhibitor is not particularly limited, and examples thereof include an organic rocking agent and an inorganic rocking agent, which may be used alone or in combination of two or more. Good.

Examples of the organic rocking agent include amide-based, hydrogenated castor oil-based, polyethylene oxide-based, vegetable oil polymerized oil-based, surfactant-based rocking agents, and rocking agents in which two or more of these are used in combination. Can be mentioned.

Examples of the inorganic rocking agent include pulverized silica, bentonite, silica surface-treated with a silane compound, bentonite (organic bentonite) surface-treated with a quaternary ammonium salt, ultrafine surface-treated calcium carbonate, and the like. Can be mentioned.

[Curing accelerator]
Examples of the curing accelerator include tertiary amines. Specifically, as tertiary amines, triethanolamine, dialkylaminoethanol, triethylenediamine [1,4-diazacyclo (2,2,2) octane], 2,4,6-tri (dimethylaminomethyl) Phenol and the like can be used, and examples of commercially available products include "Ancamine K-54" (manufactured by Air Products Japan Co., Ltd., 2,4,6-tri (dimethylaminomethyl) phenol).

<Non-volatile content of paint composition>
The non-volatile content (solid content) in the present invention means a coating film (heat residue) after the composition of the present invention is sufficiently reactively cured (heated). More specifically, the non-volatile component is a residual heating when a composition obtained by mixing a main ingredient and a curing agent component is dried at 23 ° C. for 24 hours and then heated at a heating temperature of 125 ° C. for 1 hour (under normal pressure). Minutes.

<Clear coating film, substrate with coating film and its manufacturing method>
The clear coating film of the present invention is formed from the clear coating composition.
The base material with a clear coating film of the present invention is formed by coating the base material with the clear coating film. Examples of the base material include concrete, cement, mortar, fiber-reinforced cement (calcium silicate, slate), gypsum, stone and the like. The method for producing the base material with a clear coating film of the present invention is not particularly limited, and for example, it can be produced by a production method including the following steps [1] and [2].
[1] Step of coating the base material with the clear coating composition on the base material to form a coating film [2] The coating film obtained in the above step [1] is dried to form a dry coating film. Process

The method for coating the coating composition of the present invention is not particularly limited, and conventionally known methods can be used without limitation. For example, airless spray coating, air spray coating, roller coating, brush coating and the like can be mentioned. The viscosity of the coating composition can be appropriately adjusted by adding a diluting solvent according to the coating method. For example, in the case of roller coating, it is preferable to adjust the viscosity of the coating composition to 100 dPa · s. In order to ensure good adhesion between the coating film formed from the coating composition and the base material, it is preferable to clean and remove surface deposits such as rust, oils and fats, dust, and salt.

The method for drying the painted coating composition (coating film) is not particularly limited, and it can be dried by heating to about 5 to 60 ° C. in order to shorten the drying time and the curing time. It is dried by leaving it at room temperature and in the air for about 1 to 14 days.

<Use of paint composition>
The coating composition of the present invention can form a clear coating film having visibility to the substrate by coating the surface of the substrate by a simple method such as roller coating or brush coating. Further, the clear coating film has excellent adhesion even when the base material is a wet surface, has flexibility to follow cracks in the base material, and has toughness to prevent the base material from peeling off. Has.

The object of construction of the coating composition of the present invention having the above performance is preferably a concrete structure constructed using concrete. Examples of such concrete structures include large structures such as viaducts, tunnels, harbor facilities, and dams. The clear coating film of the present invention is excellent in adhesion to the wet surface and flexibility. It is suitable for construction in tunnels, harbor facilities and dams, and is also suitable for construction in viaducts and tunnels because of its excellent flexibility and toughness.

The coating composition of the present invention having the above-mentioned effects can be used for reinforcement / repair of concrete structures and the like, and is particularly useful as a coating composition for preventing peeling of concrete pieces. That is, the present invention can provide a method for repairing and reinforcing a concrete structure by covering the surface of the concrete structure with the clear coating film. Further, by covering the surface of the concrete structure with a clear coating film, it is possible to provide a method for preventing the concrete structure from peeling off.

Further, since the clear coating film has a low hiding rate, when the surface of the concrete structure is coated, the clear coating film visually inspects the deterioration state of the concrete structure under the coating film from above the coating film. It has the property that it can be used, that is, it has high visibility to the base material. Therefore, the present invention provides a method for inspecting a concrete structure by covering the surface of the concrete structure with the clear coating film and visually confirming the deteriorated state of the concrete structure from above the clear coating film. Can be done.

Further, the base material with a clear coating film containing the clear coating film and the base material is further coated with a topcoat clear coating composition containing a solvent-based or water-based fluororesin, urethane resin, or the like as a main component, and the fluororesin is applied. By forming a topcoat clear coating film of a system or a urethane resin system, the long-term weather resistance of the substrate with a clear coating film can be improved.

[Examples 1 to 14, Comparative Examples 1 to 8]
(Preparation of main agent)
The main ingredients used in each Example and Comparative Example are prepared by mixing each of the raw materials shown in Table 1 at the blending ratio (mass ratio) shown in "Main ingredient" in Tables 2 and 3 and stirring with a high speed disper. did.

(Preparation of curing agent)
The curing agents used in each Example and Comparative Example by mixing each of the raw materials shown in Table 1 at the blending ratio (mass ratio) shown in "Curing agent components" in Tables 2 and 3 and stirring with a high-speed disper. Was prepared.

(Preparation of epoxy resin composition)
Immediately before the test, the main agent and the curing agent prepared by the above method are mixed with a disper at the mixing ratio (mass ratio) shown by the subtotals in Tables 2 and 3 to form a clear coating composition. (Examples 1 to 14 and Comparative Examples 1 to 8) were prepared. These clear paint compositions were subjected to the following tests.

<Wet surface workability>
A 300 mm × 300 mm × 60 mm concrete pavement board (base material) specified in JIS A5371 was completely submerged in water at 23 ° C. for 24 hours and then pulled out of the water. Immediately after that, each of the clear paint compositions obtained by mixing the main agent and the curing agent adjusted to a temperature of 23 ° C. by the above preparation method was applied to a concrete pavement board in an amount of 1.25 kg / m ² Using the roller "WAKABA" (manufactured by Otsuka Brush Manufacturing Co., Ltd., hair length: 13 mm, size: 4 inch, product number: 4S-WBA), the roller is moved to the pavement at a roller moving speed of 10 to 20 cm / s. While maintaining an angle of about 45 ° upward from the plate surface, paint from one end to the other end of the pavement plate to improve the adhesiveness of each clear paint composition to the substrate and the slipperiness of the rollers. evaluated. The evaluation criteria are shown below.
◯: Can be applied to the base material, and the roller does not slip during painting.
Δ: It can be applied to the base material, but the roller slips during coating.
X: Cannot be applied to the base material.

<Crack followability>
The crack followability test was based on the 6) crack followability test method of the quality test method for concrete coating materials in the "Steel Road Bridge Anticorrosion Handbook".
Each clear coating composition was coated on a polypropylene resin plate with a trowel so that the dry coating thickness was 2000 μm, cured at 23 ° C. for 120 hours, and then heated at 80 ° C. for 60 minutes and allowed to cool. Next, the formed clear coating film was peeled off from the polypropylene resin plate to obtain a free coating film. Subsequently, it was confirmed that the free coating film had no deformation or pinholes, and a test piece was obtained using a punching machine. Using a material testing machine (Shimadzu Corporation, Shimadzu small desktop testing machine model "EZ-L") that can keep the crosshead separation speed constant, the above test piece is labeled with a crosshead separation speed of 5 mm / min. It was pulled at a line-to-line distance of 40 mm and a test temperature of 23 ° C. In the process of the tensile test, a tensile load-displacement curve with the tensile load on the vertical axis and the displacement on the horizontal axis was recorded. Calculated from the tensile load-displacement curve obtained in the test by dividing the elongation at the time of yielding or the elongation at the moment of fracture (displacement length) by the distance between marked lines (40 mm) and multiplying by 100. The crack followability was evaluated based on the elongation rate.

<Adhesiveness (standard condition)>
The adhesion test was based on the Japan Society of Civil Engineers standard JSCE-K531-2010 "Adhesion strength test method for surface coating material".

A mortar with a water-cement ratio of 50% and a sand-cement ratio of 3 is molded using a metal mold with an inner glue size of 70 mm × 70 mm × 20 mm, cured at a temperature of 20 ° C. and a relative humidity of 80% for 24 hours, and then demolded. Then, a test substrate was obtained. Next, the test substrate was cured in water at a temperature of 20 ° C. for 6 days. After the completion of underwater curing, the test substrate was further cured at a temperature of 23 ° C. and a relative humidity of 50% for 7 days, and then the lower surface at the time of molding was sufficiently polished using No. 150 abrasive paper specified in JIS R 6252. ..

Each clear coating composition was coated on the obtained test substrate with a trowel so that the dry coating thickness was 2000 μm, and cured at a temperature of 23 ° C. and a relative humidity of 50% for 28 days. The following test was performed using the obtained test substrate with a clear coating film as a test body.

The test piece was placed horizontally in an atmosphere having a temperature of 23 ° C. and a relative humidity of 50%, an adhesive was applied to a part of the clear coating surface side, and a 40 mm square upper tension steel jig was gently placed on the test piece to make it light. The adhesive was glued so as to be rubbed, a weight having a weight of 1 kg was placed on the weight, the adhesive squeezed out from the periphery was wiped off, and the mixture was allowed to stand for 24 hours. Then, the weight was removed, and a square notch was made in the test piece along the circumference of the steel jig for upper tension adhered to the test piece until the depth reached 1 mm from the surface of the substrate.

A steel jig for lower tension and a steel backing plate are attached to the steel jig for upper tension of the test piece with the notch, and a material testing machine (manufactured by A & D Co., Ltd., model "RTC-1350A") The maximum tensile load T (N) was determined by applying a tensile force with a load rate of 1500 N / min until it broke in the direction perpendicular to the clear coating film on the surface of the test piece. The above test was performed twice, and the adhesiveness was evaluated according to the following criteria based on the average value of the adhesive strength. The adhesion strength was calculated by the following formula.
Adhesion strength (N / mm ² ) = T / 1600
◯: Adhesion strength was 2.0 N / mm ² or more.
X: The adhesion strength was less than ^{2.0 N / mm 2.}

<Adhesiveness (wet state)>
The test substrate prepared in the adhesion (standard state) evaluation test was completely submerged for 6 days, and immediately after pulling up, each clear paint was applied to the surface of the test substrate with a trowel so that the dry coating thickness was 2000 μm. The composition was applied, the same operation as in the above-mentioned adhesion (standard state) evaluation test was performed, and the adhesion strength was evaluated according to the same evaluation criteria.

<Punching test>
The punching test was based on the Japan Society of Civil Engineers standard JSCE-K533-2010 "Punching test method for surface covering materials applied to prevent the peeling of concrete pieces".
The test was conducted using a nominal name 300 (400 mm × 600 mm × 60 mm), which is one of the lids (hereinafter referred to as lids) of the upper lid type U-shaped gutter specified in JIS A5372. The central part of the lid was cored out into a circular shape with a diameter of 100 mm using a concrete core drill. The core removal was performed in a direction from the back surface (the surface opposite to the surface on which the clear paint composition is applied (hereinafter referred to as the construction surface)) toward the construction surface, to a depth of 55 mm from the back surface.

After surface-treating the construction surface using a diamond cup, the lid was immersed in water maintained at 23 ° C. for 24 hours so that the construction surface was on top. Next, the upper part of the lid was pulled up from the water, and the lower part of the lid was immersed in water, and water droplets on the construction surface were removed with a waste cloth. Within 5 minutes after the upper part of the lid was pulled out of the water, each clear coating composition was applied to the central portion 400 mm × 400 mm of the construction surface with a trowel so that the dry coating thickness was 2000 μm. The construction was carried out with the lower part of the lid 30 mm submerged in water. Then, the lower part of the lid was soaked in water and cured at a temperature of 23 ° C. for 28 days to obtain a specimen.

The test was carried out by the following test method using the obtained specimen material testing machine (manufactured by A & D Co., Ltd., model "RTC-1350A").
The specimen was set on the fulcrum with a span of 450 mm with the surface coated with the clear coating film facing down, and it was confirmed that the fulcrum was not in contact with the clear coating film. The load was placed vertically and evenly on the center of the core with the ball seat in between. In the loading process, a load-displacement curve was recorded with the load on the vertical axis and the displacement on the horizontal axis. First, the load was carried out at a speed of 1 mm / min until the concrete in the core portion was destroyed. After that, when the initial load peak was confirmed, loading was continued at 5 mm / min, and the maximum load appearing after that was measured. After measuring the maximum load, loading was completed when the load was reduced to about 50% of the maximum load. The three specimens prepared under the same conditions were tested as a set.

In the above test, loading was suspended at displacements of 10 mm, 20 mm, and 30 mm, the peeling range was marked on the specimen, and photographs were recorded. The test was completed when the final load bearing capacity was confirmed. From the load and displacement stroke data obtained in the test, a load-displacement curve was drawn and the maximum load when the displacement was 10 mm or more was obtained. The maximum load was obtained for each of the three specimens, the average value P was calculated, and the value was used as the punching strength. The average value P is rounded off to the second decimal place. The evaluation criteria are shown below.
◯: The punching strength was 1.5 kN or more.
X: The punching strength was less than 1.5 kN.

<Hiding rate>
In accordance with JIS K 5600-4-1 (b), after applying each clear coating composition to a hiding ratio test paper (manufactured by TP Giken Co., Ltd.) with a spatula so that the dry coating thickness is 2000 μm, the temperature It was dried for 7 days under the conditions of 23 ° C. and 50% relative humidity. Using a color difference meter (manufactured by JUKI Co., Ltd., model "JP700F"), measure the tristimulus value Y in the white part and the black part under the condition of C light source and 60 °, and measure the concealment rate as a percentage. Calculated in. In the present invention, the hiding ratio of the clear coating film is preferably 30% or less, more preferably 25% or less.

<Visibility>
Draw a straight line in the center of a 300 mm x 300 mm x 60 mm concrete pavement board (base material) specified in JIS A5371 using an oil-based black magic with a thickness of 1 mm, and use a trowel to make a dry coating thickness of 2000 μm. After each clear coating composition was coated as described above, it was dried under the conditions of a temperature of 23 ° C. and a relative humidity of 50% for 7 days. It was evaluated whether the straight line could be visually visually recognized from the clear coating film after drying. The evaluation criteria are shown below.
◯: The straight line could be visually recognized.
X: The straight line could not be visually recognized.
The evaluation results of Examples and Comparative Examples in each of the above tests are shown in the evaluation items of Tables 2 and 3, respectively.

Claims (10)

At least one epoxy resin (A) selected from the group consisting of an alicyclic epoxy resin (a1), a bisphenol A type epoxy resin (a2), a bisphenol F type epoxy resin (a3) and a novolak type epoxy resin (a4). , Bifunctional or higher epoxy resin (B) excluding epoxy resin (A), terminal reactive butadiene acrylonitrile copolymer (C), polyamide amine (D), organic fiber (E), and glass flakes (F). A clear coating composition to be contained. Claim that the bifunctional or higher functional epoxy resin (B) excluding the epoxy resin (A) contains at least one selected from the group consisting of sorbitol polyglycidyl ether (b1) and castor oil polyglycidyl ether (b2). The clear coating composition according to 1. The clear coating composition according to claim 1 or 2, which contains the oxyalkylene group-containing polyamide amine (d1) as the polyamide amine (D). The clear coating composition according to any one of claims 1 to 3, wherein the organic short fiber (E) is a vinylon fiber. A clear coating film formed from the clear coating composition according to any one of claims 1 to 4. A base material with a clear coating film, which comprises the clear coating film and the base material according to claim 5. The method for repairing and reinforcing a concrete structure in which the surface of a base material is covered with the clear coating film according to claim 5. The method for preventing the concrete structure from peeling off, which covers the surface of the base material with the clear coating film according to claim 5. A method for inspecting a concrete structure in which the surface of a base material is coated with the clear coating film according to claim 5, and the deteriorated state of the base material is visually confirmed from above the clear coating film. A method for producing a base material with a clear coating film, which comprises the following steps [1] and [2].
[1] Step of coating the base material with the clear coating composition according to any one of claims 1 to 4 to form a coating film [2] Obtained by the step [1]. Step of drying the coating film to form a dry coating film