JP6335092B2 - Coating composition, coating film forming method, and transparent coating film - Google Patents

Description

  The present invention relates to a coating composition, a coating film forming method, and a transparent coating film. More specifically, the present invention is formed by a coating composition used for forming a transparent coating film covering the surface of a reinforced concrete structure, a coating film forming method using the coating composition, and the coating composition. It relates to a transparent coating film.

  2. Description of the Related Art Conventionally, a technique is known in which a coating film is formed on a surface of a reinforced concrete structure with a curable (paint) composition to suppress the progress of aging of the reinforced concrete structure due to wind and rain or salt damage (for example, Patent Document 1). reference).

  In general, the above-described curable (paint) composition is blended with a coloring pigment such as titanium oxide for the purpose of imparting weather resistance or aesthetics, or when a thick coating is applied to the vertical surface. To prevent paint flow, extender pigments such as talc are blended. When a coating film is formed on the surface of a reinforced concrete structure using a curable (paint) composition containing these color pigments and extender pigments, the coating film becomes opaque and the reinforced concrete structure as a base material It becomes difficult to visually confirm changes in the surface state (such as the occurrence of cracks). In order to solve this problem, a method of forming a transparent coating film on the surface of a reinforced concrete structure by using a liquid A (main agent) containing an isocyanate group-terminated urethane prepolymer and a liquid B (curing agent) containing a polyamine is known. (For example, refer to Patent Documents 2 and 3).

  Further, marine steel structures are corroded by seawater by a glass flake coating composition in which about 5 to 60% by weight of scaly glass flake having a thickness of 10 μm or less and a size of 30 to 1,000 μm is blended in the coating composition. There is known a technique for protecting from the above (for example, see Patent Document 4).

  Furthermore, a gas barrier film having a gas barrier property is formed by a gas barrier resin composition comprising an inorganic layered compound having a particle size of 5 μm or less and an aspect ratio of 50 or more and 5,000 or less and a high hydrogen bonding resin. The technique to obtain is also known (for example, refer patent document 5).

JP 2002-60282 A JP 2011-132052 A JP 2012-92266 A JP-A 63-68679 JP 2005-68441 A

  By the way, the deterioration of the reinforced concrete structure proceeds by the interaction of the deterioration of the concrete and the corrosion of the reinforcing bars. Accordingly, there is a need for a technique that prevents gas (oxygen and carbon dioxide) and liquid (water) that cause deterioration from entering the concrete. Among these, oxygen is a factor that itself causes corrosion of reinforcing bars, and also promotes corrosion of reinforcing bars by interaction with moisture. Therefore, there is a need for a technique for imparting oxygen barrier properties to reinforced concrete structures. For such problems, by forming a coating film on the surface of a reinforced concrete structure using a coating composition containing an inorganic filler, moisture and carbon dioxide are blocked and oxygen barrier properties are improved. It is possible.

  On the other hand, it is important in the maintenance of reinforced concrete structures to detect and repair cracks, blisters, and defects that occur on the surface of reinforced concrete structures at an early stage. Deterioration of the surface of a reinforced concrete structure is required to be visually confirmed using naked eyes or binoculars, without depending on hammering that requires a scaffold or the use of dedicated measuring equipment. However, as described above, the coating film formed by the coating composition containing the inorganic filler (color pigment such as titanium dioxide, extender pigment such as talc) is opaque, and the reinforced concrete structure in which the coating film is formed. It is difficult to visually observe the state of the surface of an object. Therefore, an inorganic filler cannot be simply contained in the coating composition used to form a transparent coating film that covers the surface of a reinforced concrete structure.

  The techniques described in Patent Documents 2 and 3 form a coating film on the surface of a reinforced concrete structure by mixing liquid A and liquid B using a special spray device such as a two-liquid collision mixing type spray. doing. Therefore, in the techniques described in Patent Documents 2 and 3, it is considered that when the coating material contains a large amount of an inorganic filler, a malfunction occurs in the apparatus.

  Further, the technique disclosed in Patent Document 4 is for protecting marine steel structures from seawater corrosion, and is applied to a reinforced concrete structure with excellent weather resistance that achieves both transparency and high oxygen barrier properties. It is not intended to form a film. In addition, Patent Document 4 neither describes nor suggests the weather resistance required for the coating film formed on the surface of the reinforced concrete structure.

  Furthermore, the gas barrier resin composition disclosed in Patent Document 5 is formed by using a polysaccharide such as hydroxymethylcellulose as a high hydrogen bonding resin for the purpose of packaging food, medicine, electronics, chemistry, machinery, etc. The coated film is a thin film (for example, 10 μm or less). Therefore, with the technique described in Patent Document 5, the surface of the reinforced concrete structure cannot be covered with a transparent thick film.

Thus, the present condition is not found about the coating composition which can form the coating film with the high transparency, oxygen barrier property, and weather resistance which coat | covers the surface of a reinforced concrete structure.
The present invention has been made in view of the above problems, and a coating composition capable of forming a coating film having high transparency, oxygen barrier properties and weather resistance, covering the surface of a reinforced concrete structure, It aims at providing the coating-film formation method using a coating composition, and the transparent coating film formed with the coating composition.

The present invention relates to a coating composition used for forming a transparent coating film for coating the surface of a reinforced concrete structure, which is an epoxy resin (a) having no aromatic ring, a modified aliphatic amine compound ( b) and flat inorganic particles (c), wherein the inorganic particles (c) are at least one of mica and glass flakes, and the average aspect ratio of the inorganic particles (c) is 20 to 1. The oxygen permeability of the coating film formed using the coating composition and having a film thickness after curing of 1,000 μm is 0.05 mg / (cm ² · day) or less, The concealment rate of the coating film formed using the composition and having a film thickness after curing of 300 μm relates to a coating composition having 45% or less.

  Moreover, it is preferable to further include (meth) acrylic resin (d) having at least one crosslinkable silyl group and a silane coupling agent (e).

  Moreover, it is preferable that content of the said inorganic particle (c) in the total solid of a coating composition is 6-28 mass%.

  In addition, the present invention provides a coating process for coating the coating composition on the surface of the reinforced concrete structure so that the film thickness after curing is 300 μm to 1,500 μm using a trowel or a roller, and the reinforced concrete structure. And a curing step of curing the coating composition applied to the surface of the product to form a transparent coating film.

  Moreover, this invention provides the transparent coating film formed using the said coating composition.

  ADVANTAGE OF THE INVENTION According to this invention, the coating composition which can form the coating film with the high transparency, oxygen barrier property, and weather resistance which coat | covers the surface of a reinforced concrete structure, and coating film formation using the coating composition A transparent coating film formed by the method and the coating composition thereof can be provided.

<Coating composition>
Hereinafter, embodiments of the present invention will be described. In addition, this invention is not limited to the following embodiment.
The coating composition according to this embodiment is used to form a transparent coating film that covers the surface of a reinforced concrete structure. Examples of the reinforced concrete structure in the present embodiment include a bridge, a tunnel, an elevated road, and a building.
The coating composition according to the present embodiment includes an epoxy resin (a), a modified aliphatic amine compound (b), and flat inorganic particles (c).

The epoxy resin (a) according to this embodiment does not have an aromatic ring. Since the epoxy resin (a) does not have an aromatic ring, a transparent coating film having high weather resistance can be formed. Examples of the epoxy resin (a) having no aromatic ring include hydrogenated bisphenol type epoxy resin, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol di Examples thereof include glycidyl ether, glycerin diglycidyl ether, and trimethylolpropane triglycidyl ether.
Examples of the hydrogenated bisphenol type epoxy resin include bisphenol A type epoxy resin, bisphenol B type epoxy resin, bisphenol C type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, and bisphenol S type. Examples thereof include hydrogenated bisphenol type diglycidyl ether (for example, hydrogenated bisphenol A type epoxy resin) obtained by adding a hydrogen atom to a bisphenol polyglycidyl ether type epoxy resin such as an epoxy resin. Specific examples of the hydrogenated bisphenol type epoxy resin include Epolite 4000 (Kyoeisha Chemical Co., Ltd.), EPICLON EXA-7015 (made by DIC Corporation), ST-3000 (made by Nippon Steel & Sumikin Chemical Co., Ltd.), and the like. .

  As the epoxy resin (a), one having at least two epoxy groups in one molecule is preferable because it has high reactivity with the modified aliphatic amine compound (b) and the cured product can easily form a three-dimensional network. . Moreover, in order for the hardened | cured material when hardening the coating composition which concerns on this embodiment to be transparent, it is preferable that compatibility with the other component of an epoxy resin (a) is high. For example, a hydrogenated bisphenol A type epoxy resin is preferable because it has high compatibility with other components, and it is easy to obtain a transparent cured product, and the obtained cured coating film is excellent in weather resistance.

  The content of the epoxy resin (a) in the solid content of the coating composition according to this embodiment is preferably 25 to 70% by mass. When content of the epoxy resin (a) in solid content of a coating composition is less than 25 mass%, it exists in the tendency for the intensity | strength of the coating film formed and the adhesiveness to a reinforced concrete structure to fall. When the content of the epoxy resin (a) in the solid content of the coating composition is higher than 70% by mass, the weather resistance of the formed coating film is lowered and tends to be yellowed.

The modified aliphatic amine compound (b) in this embodiment reacts with the epoxy resin (a) to form a transparent coating film having high weather resistance. The modified aliphatic amine compound (b) has high reactivity with the epoxy resin (a) and high compatibility with the (meth) acrylic resin (d) described later.
Examples of the modified aliphatic amine compound (b) include aliphatic polyamine epoxy adducts, alicyclic (alicyclic) polyamines, and polyamide amines. Examples of the modified aliphatic amine compound (b) include tomide 225X, Fujicure FXU870, Fujicure 5420F (manufactured by T & K TOKA Co., Ltd.) and Ancamide 500 (produced by Air Products Japan Co., Ltd.).

  The solid content of the modified aliphatic amine compound (b) in the solid content of the coating composition according to this embodiment is preferably 2 to 26% by mass. When the content of the modified aliphatic amine compound (b) in the solid content of the coating composition is less than 2% by mass, the strength of the coating film formed and the adhesiveness to the reinforced concrete structure tend to be lowered. When the content of the modified aliphatic amine compound (b) in the solid content of the coating composition is higher than 26% by mass, the weather resistance of the formed coating film tends to decrease and yellowing tends to occur.

  The inorganic particles (c) in the present embodiment are flat. The inorganic particles (c) are at least one of mica and glass flakes, and the average aspect ratio is 20 to 1,000. By using mica and glass flakes having an average aspect ratio in the above range as the inorganic particles (c), the oxygen barrier property of the formed coating film can be improved. When the average aspect ratio of the inorganic particles (c) is less than 20, the oxygen barrier property of the formed coating film decreases, and when it exceeds 1,000, handling of the coating composition becomes difficult. The average aspect ratio of the inorganic particles (c) is more preferably 20 to 200, and further preferably 32 to 150. Moreover, it is preferable that an inorganic particle (c) is a glass flake from a viewpoint of improving the transparency of a coating film by reducing the concealment rate of the coating film formed.

  The average aspect ratio of the inorganic particles (c) is, for example, a 50% average particle diameter (L) measured by a laser diffraction particle size distribution analyzer (LMS-30; manufactured by Seishin Enterprise Co., Ltd.) and a surface measured by a transmission electron microscope. From the average thickness (a) of the interval, it can be calculated as average aspect ratio = L / a.

The average particle diameter of the inorganic particles (c) is preferably 10 to 1,000 μm. When the average particle size of the inorganic particles (c) is less than 10 μm, the oxygen barrier property of the formed coating film tends to decrease, and when it exceeds 1,000 μm, the transparency of the formed coating film tends to decrease. It is in.
The average particle size of the inorganic particles (c) can be measured by a laser diffraction particle size distribution measuring device (SALD-3100: manufactured by Shimadzu Corporation).

Examples of mica used as the inorganic particles (c) include A-21S (average aspect ratio 70, average particle diameter 23 μm), A-41S (average aspect ratio 80, average particle diameter 47 μm), and SYA-21RS (average aspect). Ratio 90, average particle diameter 27 μm) and B-82 (average aspect ratio 100, average particle diameter 180 μm, all of which are manufactured by Yamaguchi Mica Co., Ltd.).
Moreover, as glass flakes used as inorganic particles (c), for example, RCF-600 (the ratio of the component having an average aspect ratio of 120, an average thickness of 5 μm, and a particle diameter of 150 to 1,700 μm is 80% or more), RCF -2300 (average aspect ratio 1150, average thickness 2 μm, proportion of particle diameter 150-1700 μm accounted for 85% or less), RCF-160 (average aspect ratio 32, average thickness 5 μm, particle diameter 45-300 μm) (The ratio of which is accounted for 65% or more), (all of which are manufactured by Nippon Sheet Glass Co., Ltd.)

  The content of the inorganic particles (c) in the total solid content of the coating composition according to this embodiment is preferably 6 to 28% by mass. When the content of the inorganic particles (c) in the total solid content of the coating composition is less than 6% by mass, the oxygen barrier property of the formed coating film is lowered. When the content of the inorganic particles (c) in the total solid content of the coating composition is higher than 28% by mass, the transparency of the formed coating film is lost. As for content of an inorganic particle (c), it is more preferable that it is 8-22 mass%, and it is still more preferable that it is 10-20 mass%.

Furthermore, the coating composition according to this embodiment preferably contains a (meth) acrylic resin (d) having at least one crosslinkable silyl group. The (meth) acrylic resin (d) is a so-called acrylic silicon resin.
The (meth) acrylic resin (d) may be obtained by copolymerizing a crosslinkable silyl group-containing ethylenically unsaturated monomer and another ethylenically unsaturated monomer, and already exists as a polymer. The acrylic resin to be obtained may be obtained by modifying with a silicate oligomer having a crosslinkable silyl group. As the silicate oligomer having a crosslinkable silyl group, tetraalkoxysilane such as tetramethoxysilane or tetraethoxysilane, tetraphenoxysilane or a hydrolysis condensate thereof is used.

  Specific examples of the crosslinkable silyl group-containing ethylenically unsaturated monomer include vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, allyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, and γ-methacryloxypropyl. Examples include trimethoxysilane, γ-acryloxypropyltributoxysilane, and γ-methacryloxypropylmethyldimethoxysilane.

  Other ethylenically unsaturated monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, Examples include cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, styrene, vinyltoluene, α-methylstyrene, (meth) acrylonitrile, (meth) acrylamide, and vinyl acetate.

  The method for modifying the acrylic resin with a silicate oligomer having a crosslinkable silyl group is not particularly limited, and an ordinary radical polymerization method can be exemplified. The organic solvent used at that time can be appropriately selected as long as it dissolves the silicate oligomer and the (meth) acrylic resin. Specific examples thereof include methanol, ethanol, ethylene glycol monomethyl ether, toluene, xylene and the like.

Examples of the crosslinkable silyl group possessed by the (meth) acrylic resin (d) include a functional group represented by the formula (1).
[Chemical 1]
^{_{- [Si (R 1) 2}} -b (Y) b O] m -Si (R 2) 3-a (Y) a (1)

{In the formula, R ¹ and R ² are all alkyl groups having 1 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, aralkyl groups having 7 to 20 carbon atoms, or (R ′) ₃ SiO— (R 'Is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and three R's may be the same or different), and represents a triorganosiloxy group represented by R ¹ or When two or more R ² are present, they may be the same or different. Y represents a hydroxyl group or a hydrolyzable group, and when two or more Y exist, they may be the same or different. a represents 0, 1, 2, or 3, and b represents 0, 1, or 2. m is an integer of 0-19. However, it shall be satisfied that a + mb ≧ 1. }

  Examples of the hydrolyzable group include functional groups such as a hydrogen atom, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an aminooxy group, a mercapto group, and an alkenyloxy group. Among these, an alkoxy group, an amide group, and an aminooxy group are preferable, but an alkoxy group is particularly preferable because it is easily hydrolyzed under mild conditions. Among alkoxy groups, the lower the number of carbon atoms, the higher the reactivity. For example, since the reactivity decreases in the order of methoxy group, ethoxy group, and propoxy group, these functional groups can be selected according to the purpose and application.

Hydrolyzable groups and hydroxyl groups can be bonded to one silicon atom in the range of 1 to 3, and (a + Σb) is preferably in the range of 1 to 5. When two or more hydrolyzable groups or hydroxyl groups are bonded to the crosslinkable silyl group, they may be the same or different. The number of silicon atoms forming the crosslinkable silyl group is one or more, but in the case of silicon atoms linked by a siloxane bond or the like, it is preferably 20 or less. In particular, the crosslinkable silyl group represented by the general formula (2) is preferable because it is easily available.
[Chemical formula 2]
_{^{-Si (R 2) 3-c}} (Y) c (2)

(Wherein R ² and Y are the same as above, c is an integer of 1 to 3)

  In the (meth) acrylic resin (d), silicon of the crosslinkable silyl group is condensed by forming a siloxane bond. When the coating composition according to the present embodiment further contains the (meth) acrylic resin (d), a cured coating film having higher weather resistance can be formed.

  The content of the (meth) acrylic resin (d) in the solid content of the coating composition according to this embodiment is preferably 30 to 70% by mass, and more preferably 50 to 60% by mass. When the content of the (meth) acrylic resin (d) in the solid content of the coating composition is less than 30% by mass, the weather resistance of the formed coating film is lowered and tends to be yellowed. When the content of the (meth) acrylic resin (d) in the solid content of the coating composition is higher than 70% by mass, the amount of the crosslinkable silyl group becomes relatively large, so that the storage stability of the resulting coating composition is stable. There is a tendency for the property to easily decline. Specifically, as the (meth) acrylic resin (d), TA polymer SA120S, TA polymer SA110S, TA polymer SA100S (above, manufactured by Kaneka Corporation), ARUFON US-66170, ARUFON US-6170 (above, Toagosei Co., Ltd.) Company-made).

  Furthermore, the coating composition according to this embodiment preferably contains a silane coupling agent (e). The silane coupling agent (e) is a reaction between the polymer of (meth) acrylic resin (d), the epoxy resin (a), and the modified aliphatic amine compound (b) when the coating composition forms a coating film. The compatibility with the product is increased, and the strength of the formed coating film is further improved.

  The silane coupling agent (e) preferably contains at least one of an amino group-containing silane coupling agent and an epoxy group-containing silane coupling agent. When the amino group-containing silane coupling agent is used, the amino group of the amino group-containing silane coupling agent reacts with the epoxy group of the epoxy resin (a), and the silanol group derived from the amino group-containing silane coupling agent is It reacts with the crosslinkable silyl group of the (meth) acrylic resin (d). When an epoxy group-containing silane coupling agent is used, the epoxy group of the epoxy group-containing silane coupling agent reacts with the amino group of the modified aliphatic amine compound (b) and is derived from the epoxy group-containing silane coupling agent. The silanol group reacts with the crosslinkable silyl group of the (meth) acrylic resin (d). By such a reaction, the polymer of (meth) acrylic resin (d) and the reaction product of epoxy resin (a) and modified aliphatic amine compound (b) are cross-linked, and the strength of the formed coating film is further increased. improves.

Examples of amino group-containing silane coupling agents include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropylmethyldimethoxysilane, and γ-aminopropylmethyl. Diethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltriethoxysilane, γ- (2 -Aminoethyl) aminopropylmethyldiethoxysilane, γ- (2-aminoethyl) aminopropyltriisopropoxysilane, γ-ureidopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-benzyl- γ-amino B pills trimethoxysilane, N- vinylbenzyl -γ- aminopropyltriethoxysilane, and the like.
Specific examples of the amino group-containing silane coupling agent include KBE-903 (3-aminopropyltriethoxysilane), KBM-602 (N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane) and KBM- And 603 (N-2- (aminoethyl) -3-aminopropyltrimethoxysilane) (all of which are manufactured by Shin-Etsu Chemical Co., Ltd.).

Examples of the epoxy group-containing silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, β- (3,4-epoxy Cyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and the like.
Specific examples of the epoxy group-containing silane coupling agent include KBM-403 (3-glycidoxypropyltrimethoxysilane), KBE-403 (3-glycidoxypropyltriethoxysilane), KBE-402 (3-glycol). Sidoxypropylmethyldimethoxysilane), KBM-303 (2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane), KBM-402 (3-glycidoxypropylmethyldiethoxysilane) (all Shin-Etsu Chemical Co., Ltd.) And the like).

  It is preferable that content of the silane coupling agent (e) in solid content of the coating composition which concerns on this embodiment is 0.1-20 mass%. When content of the silane coupling agent (e) in solid content of a coating composition is less than 0.1 mass%, it exists in the tendency for the transparency of the coating film formed to fall. When the content of the silane coupling agent (e) in the solid content of the coating composition exceeds 20% by mass, the curability of the coating composition tends to decrease.

  The coating composition according to this embodiment preferably contains a fatty acid amide compound (f). The fatty acid amide compound (f) serves as a viscosity modifier and imparts structural viscosity to the coating composition.

  Specific examples of the fatty acid amide compound (f) include saturated fatty acid monoamides such as palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxy stearic acid amide, and methylol amide such as methylol stearic acid amide and methylol behenic acid amide. , Methylene bis lauric acid amide, methylene bis hydroxy stearic acid amide, methylene bis oleic acid amide, ethylene bis isostearic acid amide, hexamethylene bis hydroxy stearic acid amide, butylene bis hydroxy stearic acid amide, ethylene bis oleic acid amide, ethylene bis Bisamides such as erucic acid amide, hexamethylene bis oleic acid amide, m-xylylene bis stearic acid amide, fatty acid esters such as ethanolamine distearate De is illustrated.

  As the fatty acid amide compound (e), a paste obtained by pasting the above compound with a solvent is also commercially available. Specifically, for example, A670-20M, A650-20X, A603-20X, 603-10X, 6850-20X, 6840-10X, 6820-20M, 6810-20X, 6900-10X, 6900-20XN, 6900-20X ( As mentioned above, Enomoto Kasei Co., Ltd.) etc. are mentioned.

  The content of the fatty acid amide compound (f) in the solid content of the coating composition according to the embodiment is preferably 0.3 to 3.0% by mass. When the content of the fatty acid amide compound (f) in the solid content of the coating composition is less than 0.3% by mass, the thixotropy of the coating composition is lowered, and the coating composition having a coating film formed easily flows ( The paint tends to sag). When the content of the fatty acid amide compound (f) in the solid content of the coating composition is more than 3.0% by mass, the transparency of the formed coating film tends to decrease.

  The coating composition which concerns on this embodiment may contain additives other than the said component (a)-(f) as needed. Additives contained in the coating composition include condensation catalysts, UV absorbing compounds, antioxidants, curability modifiers, metal deactivators, ozone degradation inhibitors, phosphorus peroxide decomposers, lubricants, colored Examples thereof include particles, antifoaming agents, foaming agents, antproofing agents, and fungicides.

The coating composition according to the present embodiment is a two-component mixed coating composition including a main agent containing an epoxy resin (a) and a curing agent containing a modified aliphatic amine compound (b). By being a two-component mixed coating composition, workability at the site of repainting is improved.
In addition, a silane coupling agent (e) is suitably mix | blended with one of a main ingredient and a hardening | curing agent according to the kind of functional group which a silane coupling agent has. Specifically, when an epoxy-containing silane coupling agent is used as the silane coupling agent (e), the modified aliphatic amine compound (b) and the silane coupling agent (e) react in the curing agent. In order to avoid this, the silane coupling agent (e) is blended in the main agent. On the other hand, when an amino group-containing silane coupling agent is used as the silane coupling agent (e), in order to avoid the reaction between the epoxy resin (a) and the silane coupling agent (e) in the main agent, A ring agent (e) is mix | blended with a hardening | curing agent.

  Components other than the epoxy resin (a), the modified aliphatic amine compound (b) and the silane coupling agent (e) can be appropriately blended in one or both of the main agent and the curing agent.

As a method for preparing the main agent and the curing agent, a special method is not required, and a method commonly used by those skilled in the art can be used.
For example, as a preparation method of the main agent, a resin vehicle component, that is, a (meth) acrylic resin (d) having at least one crosslinkable silyl group and an epoxy resin (a) previously prepared as a varnish, a fatty acid amide compound ( f) and other ingredients such as the above-mentioned additives are mixed, disperse, ball mill, S.P. G. The method of preparing by disperse | distributing with dispersers, such as a mill and a roll mill, can be mentioned.

  Further, for example, as a method for preparing a curing agent, a modified aliphatic amine compound (b), a silane coupling agent (e), and an organic solvent as necessary are mixed, and a disper, ball mill, S.I. G. The method of preparing by disperse | distributing with dispersers, such as a mill and a roll mill, can be mentioned.

<Method for forming coating film>
The coating film forming method according to the present embodiment includes a mixing process, a painting process, and a curing process.
In the mixing step, the main agent and the curing agent in the above embodiment are mixed to obtain a mixed coating composition (coating composition).

  The mixing method in the mixing step is not particularly limited. Examples of the mixing method include a method in which the main agent and the curing agent are blended and mixed with a hand mixer or a static mixer.

The mixing ratio of the main agent and the curing agent is preferably 70/30 to 90/10 in terms of total solids. By setting it as such a compounding ratio, formation of a coating film advances smoothly.
In addition, you may add 3rd components other than a main ingredient and a hardening | curing agent as needed.

  The total solid content of the mixed coating composition is preferably 80 to 100% by mass. When the total solid content concentration of the mixed coating composition is less than 80% by mass, the structural viscosity of the mixed coating composition tends to decrease. When the coating composition contains the (meth) acrylic resin (d), an organic solvent having no functional group that reacts with the silyl group of the (meth) acrylic resin (d) is added to the mixed coating composition. It is also possible to adjust to an appropriate viscosity by adding. Specific examples thereof include methanol, ethanol, ethylene glycol monomethyl ether, toluene, xylene and the like.

  In the coating process, the mixed coating composition (coating composition) is applied to the surface of the reinforced concrete structure using a trowel or roller so that the film thickness after curing (target dry film thickness) is 300 μm to 1,500 μm. Paint. In the painting process, since painting is performed by hand painting using a trowel or a roller, the work can be easily performed even at the site where the reinforced concrete structure is installed.

  In the coating process, when the mixed coating composition is coated so that the film thickness after curing is less than 300 μm, the protective effect of the reinforced concrete structure is lowered. On the other hand, when the mixed coating composition is applied so that the film thickness after curing exceeds 1,500 μm, the amount of the coating composition used for forming the coating film increases, so the cost increases. The transparency of the coating film decreases.

  In the curing step, the mixed coating composition painted on the surface of the reinforced concrete structure is cured to form a transparent coating film. Although the curing method of the mixed coating composition in the curing step is not particularly limited, since a reinforced concrete structure is usually installed outdoors, a coating film is formed by leaving it under natural conditions.

  The coating film forming method according to this embodiment may be applied to a reinforced concrete structure immediately after construction for the purpose of preventive maintenance, or a reinforced concrete structure that has already been cracked for the purpose of repair. You may apply to. Moreover, you may apply to what is called a precast reinforced concrete product manufactured beforehand in the factory etc.

<Transparent coating>
The transparent coating film which concerns on this embodiment is formed in the surface of a reinforced concrete structure using said coating composition.

The oxygen permeability of the coating film formed using the coating composition and having a cured film thickness of 1,000 μm is 0.05 mg / (cm ² · day) or less. When the oxygen permeability of the coating film having a thickness of 1000 μm after curing exceeds 0.05 mg / (cm ² · day), the content of the inorganic particles (c) increases, so that the transparency of the coating film formed is increased. Is damaged.
The oxygen permeability can be measured using a Seikaken type film oxygen permeability meter.

  The concealment rate of a coating film formed using the above coating composition and having a cured film thickness of 300 μm is 45% or less. When the concealment rate of the coating film having a thickness of 300 μm after curing exceeds 45%, the transparency of the coating film is impaired, so that it is difficult to observe the surface state of the reinforced concrete structure. In addition, it is preferable that the concealment rate of the coating film whose film thickness after hardening is 300 micrometers is 5-45%. When the concealment ratio of the coating film having a thickness of 300 μm after curing is less than 5%, the amount of inorganic particles (c) is substantially reduced, so that the oxygen permeability of the coating film tends to increase. It is in.

The concealment rate of the coating film can be determined by the following method.
First, the coating composition is applied to a concealment rate test paper (manufactured by Nippon Test Panel Co., Ltd.) used in a general coating test method based on JIS K 5600-4-1 (b). Next, with respect to the test specimen left at room temperature for 7 days at 23 ° C., the tristimulus value Y in the white part (Y _W ) and the black part (Y _B ) was measured using a spectrophotometer (manufactured by Konica Minolta, CR-400). Measure and calculate the concealment rate Y _B / Y _W as a percentage.

In addition, “transparent” of the transparent coating film in the present embodiment is not limited as long as it can recognize the state and the object on the other side from one side through the coating film, and requires that the other side can be clearly recognized. Not what you want. The transparent coating film may be colored or cloudy as long as the state of the object on the other side can be visually recognized through the transparent coating film.
More specifically, the transparent coating film is a coating film having a concealment rate of 45% or less.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

[Example 1]
Table 1 shows Epolite 4000 (manufactured by Kyoeisha Chemical Co., Ltd.) as the epoxy resin (a) and RCF-600 (glass flake, average aspect ratio 120, manufactured by Nippon Sheet Glass Co., Ltd.) as the inorganic particles (c). The solid content (unit: part by mass) was blended. Furthermore, xylene was added to adjust the total solid content concentration to 90% by mass, and the main component was obtained by sufficiently stirring with a desktop disper.
Adjust the solid content concentration to 90 mass% by adding xylene to tomide 225X (manufactured by T & K TOKA Co., Ltd.) as the modified aliphatic amine compound (b), and sufficiently stir with a desktop disper A curing agent was obtained.

  The above-mentioned main agent and curing agent are mixed so that each component has the solid content (unit: part by mass) shown in Table 1, and mixed sufficiently to obtain a mixed coating composition (solid content concentration 90 mass) %).

[Examples 2 to 21 and Comparative Examples 1 to 8]
In the preparation of the main agent, the curing agent and the mixed coating composition, the components shown in Tables 1 to 3 become the solid content (unit: parts by mass) shown in Tables 1 to 3 by the same method as Example 1. Mixed. At this time, the solid content concentrations of the main agent, the curing agent, and the mixed coating composition were all 90% by mass.

  Among the components shown in Tables 1 to 3, epoxy resin (a), epoxy resin containing an aromatic moiety, modified aliphatic amine compound (b), inorganic particles (c), glass flake D, synthetic mica, talc The titanium oxide and the aliphatic amide compound were blended in the main agent, and the amine compound other than the modified aliphatic amine compound (b) and the modified aliphatic amine compound was blended in the curing agent. Moreover, among the silane coupling agents (e), the amino group-containing silane coupling agent was blended with the curing agent, and the epoxy group-containing silane coupling agent was blended with the main agent.

  In the examples and comparative examples, Epolite 4000 (manufactured by Kyoeisha Chemical Co., Ltd.) and ST-3000 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) were used as the epoxy resin (a). Moreover, Epicoat 1001 X75 (made by Japan Epoxy Resin Co., Ltd.) was used as an epoxy resin containing an aromatic moiety. Moreover, TA polymer SA120S (made by Kaneka Corporation) and ARUFON US-66170 (made by Toagosei Co., Ltd.) were used as the (meth) acrylic resin (d). Further, as the modified aliphatic amine compound (b), Fuji Cure 5420F (manufactured by T & K TOKA Co., Ltd.) was used. Moreover, JER cure W (made by Mitsubishi Chemical Corporation) was used as a modified aromatic amine compound. In addition, as the inorganic particles (C), glass flake A (RCF-600, average aspect ratio 120, average thickness 5 μm, proportion of particles 150 to 1,700 μm accounted for 80% or more), glass flake B (RCF -2300, average aspect ratio 150, average thickness 2 μm, particle diameter 150-1700 μm accounted for 85% or less), glass flake C (RCF-160, average aspect ratio 32, average thickness 5 μm, particles The ratio of components having a diameter of 45 to 300 μm is 65% or more), glass flake D (RCF-015, average aspect ratio 3, average thickness of 5 μm, ratio of components having a particle diameter of 45 μm or less is 88% or more) (above, All made by Nippon Sheet Glass Co., Ltd.), synthetic mica (Na-Ts: tetrasilic mica, average aspect ratio 1043, average thickness 0. 9557 nm, average particle diameter 977 nm, manufactured by Topy Industries, Ltd.). Further, talc (talc SSS, manufactured by Nippon Talc Co., Ltd.) was used as inorganic particles that were not flat. Further, titanium dioxide (TI-PURE R-706, manufactured by DuPont) was used. Further, as silane coupling agent (e), KBM-602 (N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane), KBM-603 (N-2- (aminoethyl) -3-aminopropyl) Trimethoxysilane) and KBM-402 (3-glycidoxypropylmethyldiethoxysilane) were used. Further, stearic acid amide (manufactured by Tokyo Chemical Industry Co., Ltd., melting point 100 ° C., solid content concentration 100% by mass) was used as the aliphatic amide compound (f).

Then, the following evaluation was performed about the coating composition formed by the mixed coating composition (the test coating liquid which mixed the main ingredient and the hardening | curing agent) obtained by the Example and the comparative example.
Synthetic mica Na-Ts is destroyed when dispersed with a desktop disper during preparation of the main agent, and it is difficult to maintain the average aspect ratio at 1043. Therefore, in Comparative Example 8, synthetic mica Na-Ts could not be dispersed and a mixed coating composition could not be obtained. Therefore, Comparative Example 8 was not evaluated as follows.

<Oxygen permeability>
A release paper is laid on a Teflon (registered trademark) plate, and the mixed coating compositions obtained in the examples and comparative examples are coated so that the film thickness after drying (dry film thickness) is 1000 μm, and after drying, the release paper A free coating film was obtained by peeling off the film. In addition, about Example 17, 18, 20, and 21, the quantity used as the target dry film thickness (film thickness after hardening) described in Table 2 was painted. After coating, it was cured at a temperature of 23 ° C. and a relative humidity of 50% for 28 days. The measurement of oxygen permeability was performed by the following procedure using a Seikaken type film oxygen permeability meter. The calculated oxygen permeability is shown in Tables 1-3.
1. A platinum electrode (cathode) was adhered to the surface side of the free coating film.
2. An electrode containing 5 mL of 0.5 N calcium chloride solution in an electrode cell was placed in a beaker filled with distilled water.
3. The electrode was placed in a beaker filled with distilled water.
4). Nitrogen gas was blown into distilled water at a flow rate of 200 mL / min, oxygen gas was completely expelled to stabilize the recorder current, and then the zero point of the recorder was adjusted.
5. Oxygen gas was blown into distilled water at a flow rate of 200 mL / min, the current value was read when the oxygen permeation amount became constant, and the oxygen permeability (unit: mg / (cm ² · day)) was calculated.

<Concealment rate during coating (transparency of coating film)>
Mixed paint compositions obtained in Examples and Comparative Examples on a concealment rate test paper (manufactured by Nippon Test Panel Co., Ltd.) used in a general paint test method based on JIS K 5600-4-1 (b) (Test coating solution) was applied with a trowel. The amount of the mixed coating composition to be applied was such that the target dry film thickness (cured film thickness) was 300 μm. In addition, about Example 17, 18, 19, 20, and 21, the quantity used as the target dry film thickness (film thickness after hardening) described in Table 2 was applied.
Next, for the test body on which a coating film having a film thickness of 300 μm was formed by leaving it at room temperature for 7 days at 23 ° C., using a spectrophotometer (CR-400, manufactured by Konica Minolta Co., Ltd.), the white part (Y _W ) The tristimulus value Y in the black part (Y _B ) was measured, and the concealment rate Y _B / Y _W was calculated as a percentage. The result of the concealment rate was evaluated as the transparency of the coating film. The results are shown in Tables 1-3.
The smaller the value of Y _B / Y _W, the higher the transparency of the coating film. Y _B / Y _W is preferably 45 or less, and more preferably 35 or less. On the other hand, the coating film with Y _B / Y _W exceeding 45 has poor transparency, and it is difficult to visually observe the change in the state of the surface of the reinforced concrete structure (such as the occurrence of cracks).

<Sagging (coating workability)>
A test tape (material: asbestos slate board, length 300 mm × width 200 mm) from a lateral end of 5 cm (length 300 mm × width 50 mm) as a curing tape (manufactured by Nitto Denko Corporation, trade name: Masking Tape No. 720 for architectural painting). Next, the said coating test board was set | placed on the horizontal surface, and the mixed coating composition (test coating liquid) obtained in Examples 1-21 and Comparative Examples 1-7 was coated with the iron. In addition, the quantity of the mixed coating composition to apply | coat was made into the quantity used as the dry film thickness (film thickness after hardening) used as the target described in Tables 1-3. Remove the curing tape from the painted test plate immediately after painting, then set the painted test plate on the vertical surface so that the part covered with the curing tape is on the bottom, and let it stand for 10 minutes. It was confirmed visually. About each mixed coating composition, the length of the produced sauce was measured with calipers on the basis of the boundary between the portion covered with the curing tape and the portion not covered with the curing tape. The results are shown in Tables 1-3. Within 3 cm is acceptable and more preferably within 1 cm.

<Weather resistance (color difference)>
Mixed coating compositions (test coating liquids) obtained in Examples 1-21 and Comparative Examples 1-7 on a test plate (70 mm × 70 mm × 20 mm mortar, water: cement: sand = 0.6: 1: 2) ) Was painted with a trowel. In addition, the quantity of the mixed coating composition to apply | coat was made into the quantity used as the dry film thickness (film thickness after hardening) used as the target described in Tables 1-3. Subsequently, using a Super UV tester (I Super Tester SUV-W151, manufactured by Iwasaki Electric Co., Ltd.) on the coating film on the surface of the test plate, a wavelength of 295 to 450 nm, an illuminance of 100 mW / cm, and a black panel temperature of 63 ± 3 ° C. Ultraviolet rays were irradiated at a distance of 240 nm from the light source. A cycle of 4 hours of UV irradiation, 4 hours of dew condensation (ion-exchange water showering) and 0.1 hour of rest was repeated until the total UV irradiation time reached 100 hours. The degree of yellowing of the coating after irradiation with ultraviolet rays for 100 hours was confirmed.
The degree of yellowing is measured by the reflection method according to JIS K 7105 (FY 2004), by measuring the b value in accordance with JIS K 7105 (FY 2004), by coating the white part of the concealment rate test paper based on JIS K 5600 4-1 B method. The difference (color difference Δb) between the b value and the b value after reflection was determined. The results are shown in Tables 1-3. Δb is preferably less than 20, and more preferably less than 5.

  From a comparison between Examples 1 to 5 and Comparative Example 3, the coating compositions of Examples 1 to 5 have higher oxygen barrier properties of the coating film formed than the coating composition of Comparative Example 3. I understood. From this result, it was confirmed that the oxygen barrier property of the formed coating film is improved by containing inorganic particles having a specific aspect ratio (20 to 1,000) in the coating composition.

  From a comparison between Example 6 and Comparative Example 5, it was found that the mixed coating composition of Example 6 had higher oxygen barrier properties than the coating composition of Comparative Example 5. Further, from comparison between Example 7 and Comparative Example 6, it was found that the coating composition of Example 7 had higher transparency of the coating film formed than the coating composition of Comparative Example 6. From these results, it was confirmed that the transparency of the coating film to be formed and high oxygen barrier properties can be achieved by adding 6 to 28 mass% of inorganic particles having a specific aspect ratio in the coating composition.

  From comparison between Example 1 and Comparative Example 1, it was found that the coating composition of Example 1 had higher weather resistance than the coating composition of Comparative Example 1. From this result, it was confirmed that the weather resistance of the coating film to be formed is improved by containing an epoxy resin having no aromatic ring as the epoxy resin in the coating composition.

  From a comparison between Example 1 and Comparative Example 2, it was found that the coating composition of Example 1 had higher weather resistance than the coating composition of Comparative Example 2. From this result, it was confirmed that the weather resistance of the formed coating film was improved by containing the modified aliphatic amine compound as an amine compound in the coating composition.

  Furthermore, from a comparison between Example 17 and Example 20 in which coating films with different film thicknesses were formed, the coating film with a film thickness of 350 μm formed using the coating composition of Example 17 was the coating material of Example 20. It was found that the oxygen barrier property was higher than that of a coating film having a film thickness of 200 μm formed using the composition. On the other hand, from a comparison between Example 18 and Example 21 in which coating films having different film thicknesses were formed, a coating film having a film thickness of 1,450 μm formed using the coating composition of Example 18 was found to be Example 21. It was found that the film thickness formed using this coating composition was higher in transparency than a coating film having a thickness of 1,600 μm. From these results, when applying the coating composition according to the present embodiment to the surface of the reinforced concrete structure, by setting the film thickness after curing to 300 μm to 1,500 μm, high transparency, oxygen barrier properties and It was confirmed that a coating film having weather resistance could be formed and a change in the state of the surface of the reinforced concrete structure as a base material (such as occurrence of cracks) could be visually confirmed.

Claims (5)

A coating composition used to form a transparent coating film for coating the surface of a reinforced concrete structure,
An epoxy resin (a) having no aromatic ring;
A modified aliphatic amine compound (b);
Flat inorganic particles (c),
The inorganic particles (c) are at least one of mica and glass flakes,
The average aspect ratio of the inorganic particles (c) is 20 to 1,000,
The oxygen permeability of the coating film formed using the coating composition and having a thickness after curing of 1,000 μm is 0.05 mg / (cm ² · day) or less,
A coating composition having a concealment rate of 45% or less of a coating film formed using the coating composition and having a film thickness after curing of 300 μm. (Meth) acrylic resin (d) having at least one crosslinkable silyl group;
The coating composition according to claim 1, further comprising a silane coupling agent (e).   The coating composition according to claim 1 or 2, wherein the content of the inorganic particles (c) in the total solid content of the coating composition is 6 to 28% by mass. The coating process which coats the surface of the said reinforced concrete structure with the coating composition in any one of Claim 1 to 3 using a iron or a roller so that the film thickness after hardening may be 300 micrometers-1,500 micrometers. When,
And a curing step of curing the coating composition applied to the surface of the reinforced concrete structure to form a transparent coating film.   The transparent coating film formed using the coating composition in any one of Claim 1 to 3.