JP6261559B2 - Concrete peeling prevention method - Google Patents

Description

  The present invention relates to a method for preventing concrete from peeling off from a concrete structure (hereinafter also referred to as a concrete peeling prevention method), and in particular, a brush even when applied with a two-component reaction-curable water-based paint containing an epoxy resin. A thick film with good visibility can be formed by painting or roller coating, which makes it possible to form all the coating films that make up the laminate from water-based paints and visually check the deformation of the concrete surface It relates to concrete peeling prevention method.

  As for viaducts, tunnels, bridges and other structures, concrete structures are widely used because of the need to improve the strength and durability. However, in recent years, concrete has deteriorated due to corrosion of steel bars due to salt damage, neutralization by exhaust gas, etc., alkali aggregate reaction, freezing of moisture that has penetrated into cracks, etc. The concrete pieces are peeled off, causing problems such as a decrease in strength and aesthetics of the concrete structure itself, and the risk of accidents due to peeling.

  Japanese Patent Application Laid-Open No. 2011-99209 (Patent Document 1) describes a concrete exfoliation prevention method that imparts anti-exfoliation performance to a concrete structure, is environmentally friendly, and generates almost no toxic gas during a fire. Specifically, it describes a concrete peeling prevention method characterized in that the surface of a concrete structure is covered with a polymer cement mortar for adhesion and a mesh-like sheet, and then covered with a water-based paint.

  However, in the concrete exfoliation preventing method described in Patent Document 1, since the surface of the concrete structure is covered with polymer cement mortar, it is difficult to visually confirm the change in the state of the surface of the concrete structure.

  Japanese Patent Application Laid-Open No. 2006-342538 (Patent Document 2) applies an undercoat resin to a concrete structure surface, adheres a fiber base material to the application surface, and applies an overcoat resin to the fiber base surface. A concrete structure repair method that can visually check the progress of deformation of a concrete structure or new deterioration or deformation after repair without selecting the type of fiber base material. Describes how to repair the item. However, the repair method described in Patent Document 2 is characterized by adjusting the viscosity of the undercoat resin and the overcoat resin, and has not been studied for environmental load. In fact, the undercoat resin and the overcoat resin are not studied. An acrylic adhesive is used as the resin.

  JP 2007-247290 A (Patent Document 3) discloses that a primer layer (A), a main material layer (B), a concrete peeling prevention sheet (C), a main material layer (B), and a top coat are applied to a concrete surface. The concrete peeling prevention surface coating method which laminates | stacks a film layer (D) sequentially is described. However, in the concrete peeling prevention surface coating method described in Patent Document 3, a water-based polyurethane paint is used for forming the main material layer.

  JP 2010-1707 (Patent Document 4) is a reinforcement of concrete structure expression in which a transparent polyurethane resin solution is applied to a concrete structure surface, a glass continuous fiber sheet is attached, and a transparent polyurethane resin solution is further applied. A reinforced coating method capable of visually confirming the surface state of a base material of a concrete structure from the outside is described. However, in the reinforced coating method described in Patent Document 4, an organic solvent-based coating agent is actually used in a part of the method, and the load on the environment is large.

JP 2011-99209 A JP 2006-342538 A JP 2007-247290 A JP 2010-1707 A

  Under such circumstances, the object of the present invention is to form a thick film with good visibility by brush coating or roller coating, even when coating with a two-component reaction-curable water-based paint containing an epoxy resin. Thereby, it is providing the concrete peeling prevention construction method which can form all the coating films which comprise a laminated body from a water-system paint, and can confirm the deformation | transformation of the concrete surface visually.

  As a result of intensive studies to achieve the above object, the present inventor has formulated brushes by blending extender pigments into a two-component reaction curable paint containing an epoxy resin-containing main agent and a curing agent in a specific ratio or more. The present inventors have found that a thick film with good visibility can be formed even when painting with a roller or a roller.

That is, the concrete exfoliation prevention method of the present invention is a method for preventing the exfoliation of concrete from a concrete structure by forming a laminate comprising an undercoat film, a fiber sheet and a topcoat film on the surface of the concrete structure. There,
A first step of painting a surface of a concrete structure with a water-based undercoating paint by brush coating or roller coating to form a coating film, wherein the water-based undercoating paint contains an epoxy resin, a curing agent and an extender pigment 2 A first step in which the content of the extender pigment in the aqueous undercoat paint is in the range of 0.1 to 10% by mass, which is a liquid reaction curable paint;
A second step of disposing a fiber sheet on the undercoat film;
A third step of applying a water-based top coat so as to cover the undercoat film and the fiber sheet, and forming a top coat film;
The laminate has a visible light transmittance of 30% or more at a wavelength of 360 to 750 nm.

  In a preferred example of the concrete peeling prevention method of the present invention, the water-based undercoat has a viscosity of 1 to 1000 (Pa · s, 23 ° C.) at a shear rate of 0.1 (1 / s), and a shear rate of 1000 (1 / S) has a viscosity of 0.05 to 10 (Pa · s, 23 ° C.).

  In another preferred embodiment of the concrete peeling prevention method of the present invention, the water-based topcoat paint is a two-component reaction curable paint containing an epoxy resin and a curing agent.

  In another preferred embodiment of the concrete peeling prevention method of the present invention, the extender pigment is silica.

  In another preferred embodiment of the concrete peeling prevention method of the present invention, the water-based undercoat further contains a thixotropic agent, and the content of the thixotropic agent in the water-based undercoat is in the range of 0.01 to 5% by mass. It is in.

  In another preferred embodiment of the concrete exfoliation preventing method of the present invention, the water-based undercoat paint further contains at least one of an ultraviolet absorbing compound and a hindered amine compound.

  In another preferred embodiment of the concrete peeling prevention method of the present invention, the laminate has a thickness in the range of 200 to 1500 μm.

  According to the present invention, a thick film with good visibility can be formed by brush coating or roller coating even with coating with a two-component reaction-curable water-based paint containing an epoxy resin. It is possible to provide a concrete exfoliation preventing method capable of forming all the coating films constituting from a water-based paint and visually confirming the deformation of the concrete surface.

  Below, the concrete peeling prevention construction method of this invention is demonstrated in detail. The concrete exfoliation prevention method of the present invention is a method for preventing the exfoliation of concrete from a concrete structure by forming a laminate comprising an undercoat film, a fiber sheet and a topcoat film on the surface of the concrete structure. The first step of coating the surface of a concrete structure with a water-based undercoating paint by brush coating or roller coating to form an undercoating film, wherein the water-based undercoating paint comprises an epoxy resin, a curing agent and an extender pigment. The first step in which the content of the extender pigment in the aqueous undercoat paint is in the range of 0.1 to 10% by mass, and the fiber sheet is disposed on the undercoat paint film Including a second step and a third step of applying a water-based topcoat so as to cover the undercoat and the fiber sheet to form a topcoat, Wherein the visible light transmittance at a wavelength of 360~750nm is 30% or more.

  The concrete exfoliation preventing method of the present invention is a method for preventing the exfoliation of concrete from a concrete structure by forming a laminate comprising an undercoat film, a fiber sheet and a topcoat film on the surface of the concrete structure. Since the laminate is obtained through the first step, the second step, and the third step described later, the visible light transmittance at a wavelength of 360 to 750 nm can be set to 30% or more. The deformation of the concrete surface located from the outside to the inside can be sufficiently confirmed visually.

  In the concrete peeling prevention method of the present invention, the laminate has a visible light transmittance of 30% or more at a wavelength of 360 to 750 nm, and the upper limit is 100%, but preferably 60 to 95%. The said visible light transmittance means the total light transmittance in a visible region (360 nm-750 nm), and is calculated | required by measuring the total light transmittance of a laminated body based on JISK7375. As described above, when the visible light transmittance at a wavelength of 360 to 750 nm of the laminate is 30% or more, the deformation of the concrete surface can be visually confirmed.

  In the concrete peeling prevention method of the present invention, first, the surface of a concrete structure is coated with a water-based undercoat paint by brush coating or roller coating to form an undercoat paint film (undercoat paint film forming process or first process). .

  The above concrete structure is a structure using concrete alone or a structure using reinforced concrete. Specific examples include viaducts, bridges, piers, abutments, girders, floor slabs, railings, dolphins, tunnels, roads. And various concrete structures such as water conduits, storage tanks, walls, roofs, balconies, and the like, and members thereof.

  The water-based undercoat paint is a two-component reaction curable paint containing an epoxy resin, a curing agent, and an extender pigment, and the content of the extender pigment in the water-based undercoat paint is in the range of 0.1 to 10% by mass. The epoxy resin is suitable as a resin component constituting the undercoat coating film from the viewpoint of securing the adhesion of the coating film to the concrete structure. However, in the conventional two-component reaction-curable water-based paint containing the epoxy resin, It was difficult to form a thick film by roller coating. However, according to the water-based undercoat paint used in the present invention, the content of the extender pigment in the water-based undercoat paint is in the range of 0.1 to 10% by mass, so that the visibility is good by brush coating or roller coating. A thick film can be formed, whereby a concrete peeling prevention method can be provided in which all the coating films constituting the laminate can be formed from a water-based paint and the deformation of the concrete surface can be visually confirmed.

  The water-based undercoat paint is a two-component reaction curable paint, but the two-component reaction curable paint in the present invention is used by mixing a main agent containing an epoxy resin and a curing agent at the time of painting. It can be easily used as a room temperature drying paint. For this reason, the two-component reaction-curable coating is suitable in consideration of the application to the already constructed concrete structure. In addition, "normal temperature" here is 5-35 degreeC.

  The epoxy resin used for the water-based undercoat paint is preferably a resin having at least two epoxy groups in one molecule, and is obtained, for example, by reacting a polyhydric alcohol or polyhydric phenol with a halohydrin. Specific examples include bisphenol A type epoxy resin, halogenated bisphenol A type epoxy resin, novolac type epoxy resin, polyglycol type epoxy resin, bisphenol F type epoxy resin, epoxidized oil, 1,6-hexanediol diglycidyl Examples include ether and neopentyl glycol diglycidyl ether. Among these, bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferable from the viewpoint of durability of the coating film and adhesion to a concrete structure. In addition, these epoxy resins may be used independently and may be used in combination of 2 or more type.

  In addition, the epoxy resin usually has an epoxy equivalent of preferably 100 to 1,000 g / eq, more preferably 160 to 980 g / eq, and more preferably 160 to 550 g / eq, from the viewpoint of the finish and curability of the coating film. preferable. If the epoxy equivalent is less than 100 g / eq, sufficient film properties may not be obtained. On the other hand, if the epoxy equivalent is greater than 1,000 g / eq, the leveling property is lowered and a uniform coating is obtained. There is a risk of not being able to.

  The epoxy resin is preferably blended in the form of an epoxy resin emulsion or an epoxy resin dispersion. In the present invention, the epoxy resin emulsion means an emulsion in which an epoxy resin is dispersed in an aqueous medium such as water, and the epoxy resin dispersion means an epoxy resin in an aqueous medium such as water. It means a dispersed liquid. The epoxy resin emulsion is not particularly limited, but is prepared by emulsifying the epoxy resin in an aqueous medium such as water by a normal forced emulsification method (a method using an emulsifier and a high-speed stirrer). Here, as the emulsifier, for example, a polyoxyethylene alkylphenol ether-based nonionic surfactant, a polyether such as a polyoxyethylene / polyoxypropylene block copolymer, or at least the nonionic surfactant and the polyether Examples include adducts of one and a diisocyanate compound. These emulsifiers may be used alone or as a blend of two or more. Moreover, as a commercial item of an epoxy resin emulsion, for example, Eporation EA1, 2, 3, 7, 12, 20, 55 and HD2 (made by Henkel Japan); Yukaresin KE-002, KE-116, E-1022, KE -301C (manufactured by Yoshimura Oil Chemical Co., Ltd.); Adeka Resin EM-101-50 (manufactured by Adeka Company); jER-W3435R67, W1155R55 (manufactured by Mitsubishi Chemical Corporation), and the like. On the other hand, examples of commercially available epoxy resin dispersions include Beckpox EP2381 (manufactured by Ornex); EPI-REZ6530-WH-53 (manufactured by Momentive).

  The curing agent used for the water-based undercoating paint is not particularly limited as long as it is an epoxy resin curing agent, but is preferably an amine compound and contains two or more amino groups in one molecule and has a molecular weight of 120 or more. More preferred are polyamine compounds. Examples of the polyamine compound include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, triaminopropane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, isophoronediamine, and 1,3-bisaminomethylcyclohexane. Aliphatic polyamines; aromatic polyamines such as phenylenediamine, metaxylylenediamine, paraxylylenediamine, and diaminodiphenylmethane; such as polyoxyethylenediamine, polyoxypropylenediamine, triethyleneglycoldiamine, and tripropyleneglycoldiamine Examples include other polyamine compounds and modified polyamine compounds obtained by modifying the amino groups of these polyamine compounds. A known method can be used for the modification of the polyamine compound. Examples of the modification reaction include amidation of an amino group, Mannich reaction of an amino group and a carbonyl compound, addition reaction of an amino group and an epoxy group, and the like. It is done. Here, a modified polyamine compound in which an epoxy group or the like is added to an amino group is referred to as an adduct type modified polyamine compound, and an epoxy adduct type modified polyamine compound in which an epoxy group is added to an amino group is preferable. In addition, these amine compounds may be used independently and may be used in combination of 2 or more type.

  The amine compound is preferably blended in the form of an amine compound emulsion, an amine compound dispersion or an amine compound aqueous solution. In the present invention, the amine compound emulsion means an emulsion in which the amine compound is dispersed in an aqueous medium such as water, and the amine compound dispersion means an aqueous medium in which the amine compound is water or the like. It means a dispersion liquid dispersed in the medium. In addition, as said amine compound, the commercial item available in the form of an emulsion, a dispersion, or aqueous solution can be used conveniently.

  In the water-based undercoat paint, when the curing agent is an amine compound, the blending ratio of the curing agent is such that the active hydrogen of the amine compound is based on 1 equivalent of the epoxy group of the epoxy resin from the viewpoint of curability of the coating film. It is preferably 0.5 to 3.0 equivalents, and more preferably 0.6 to 1.5 equivalents. In addition, in the said water-system undercoat coating material, it is preferable that the total content of an epoxy resin and a hardening | curing agent is 10-80 mass%, and it is still more preferable that it is 30-50 mass%.

  The water-based undercoat paint can be used in combination with an acrylic resin emulsion or the like that does not contribute to the reaction, thereby further improving the weather resistance and water resistance. When blending the resin of the water-based undercoat paint, it is preferable that the compatibility between the resins is excellent in order to ensure the transparency of the cured film.

  Examples of extender pigments used in the water-based undercoat paint include calcium carbonate, silica, alumina, hydrated alumina, magnesia, talc, clay, barium sulfate, barium carbonate, wollastonite, ceramic powder, and glass fiber powder. However, silica is particularly preferable from the viewpoint of industrial availability and ensuring the visible light permeability of the coating film. In addition, these extender pigments may be used individually by 1 type, and may be used in combination of 2 or more types.

  The extender pigment is usually blended in the main agent containing an epoxy resin, but can also be used in combination with a curing agent. In the water-based undercoat paint, the content of the extender pigment is in the range of 0.1 to 10% by mass, but is preferably 3 to 6% by mass. When the content of the extender pigment is less than 0.1% by mass, it becomes difficult to form a thick film by brush coating or roller coating. On the other hand, when the content of the extender pigment exceeds 10% by mass, the concrete surface changes. It becomes difficult to visually confirm the state.

  The water-based undercoat paint contains water as a main solvent and has a low environmental load. Water is usually used for both the main agent containing the epoxy resin and the curing agent, but the curing agent may be used alone without being used together with water. In the water-based undercoat paint, the water content is preferably 15 to 70% by mass, and more preferably 30 to 50% by mass. When the water content in the water-based undercoating material is less than 15% by mass, it is difficult to prepare the coating material. On the other hand, when the content exceeds 70% by mass, it is difficult to perform thick film coating.

  It is preferable that the water-based undercoat paint further contains a thixotropic agent. The thixotropic agent can impart thixotropic properties to the paint and prevent dripping, and is preferable from the viewpoint of thick film coating. Examples of the thixotropic agent include bentonite, acrylic oligomer, amide wax, polyethylene oxide and the like, in addition to metal soaps such as aluminum stearate and zinc stearate. The thixotropic agent is usually blended with the main agent containing an epoxy resin, but can be used in combination with a curing agent. In addition, these thixotropic agents may be used individually by 1 type, and may be used in combination of 2 or more type. In the water-based undercoat paint, the content of the thixotropic agent is preferably in the range of 0.01 to 5% by mass, and more preferably 0.5 to 3% by mass. Here, if content of the said thixotropic agent is 0.01 mass% or more, dripping of a coating material can be prevented effectively. On the other hand, when the content of the thixotropic agent exceeds 5% by mass, it is difficult to visually confirm the deformation of the concrete surface.

  The water-based undercoat paint preferably further contains at least one of an ultraviolet absorbing compound and a hindered amine compound. By blending a UV-absorbing compound or a hindered amine compound with the water-based undercoat paint, the weather resistance of the coating film can be improved, and the deformation of the concrete base material over time can be easily visually confirmed. The UV-absorbing compound and the hindered amine compound are usually blended in the main agent containing an epoxy resin, but can be used in combination with a curing agent. In the water-based undercoat paint, the total content of the ultraviolet absorbing compound and the hindered amine compound is preferably 0.05 to 10% by mass. If the total content of the ultraviolet absorbing compound and the hindered amine compound is within the above specified range, weather resistance can be imparted without impairing the visibility of the coating film.

  Examples of the ultraviolet absorbing compound include triazine compounds, malonic acid ester compounds, oxalic acid anilide compounds, and the like. Examples of the triazine compound include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5 [(hexyl) oxy] -phenol, 2- [4- [6 (2- Hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine and 2- [4- [6 (2-hydroxy -3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2,4-bis (2,4- Dimethylphenyl) -6- (2-hydroxy-4-iso-octyloxyphenyl) -s-triazine, 2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-octyloxy) Phenyl) -1,3,5-triazine and the like. Examples of the malonic ester compounds include dimethyl 2- (p-methoxybenzylidene) malonate, tetraethyl-2,2- (1,4-phenylenedimethylidene) bismalonate, 2- (p-methoxybenzylidene) -bis ( 1,2,2,6,6-pentamethyl-4-piperidinyl) malonate and the like. Examples of oxalic acid anilide compounds include 2-methyl-2′-ethoxyoxalanilide, 2-ethyl-2′-ethoxyoxalanilide, 4,4′-dioctyloxyoxalanilide, and 2,2′-diethoxy. Oxalanilide, 2,2′-dioctyloxy-5,5′-di-tert-butoxylanilide, 2,2′-didodecyloxy-5,5′-di-tert-butoxyanilide, N , N′-bis (3-dimethylaminopropyl) oxalamide, 2-ethoxy-5-tert-butyl-2′-ethoxalanilide and its 2-ethoxy-2′-ethyl-5,4′-di-tert. Examples thereof include a mixture with butoxalanilide, a mixture of o- and p-methoxy-disubstituted oxalanilide, a mixture of o- and p-ethoxy-disubstituted oxalanilide, and the like. In addition, these ultraviolet absorbing compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

  The hindered amine compound is a compound having a piperidine ring in which the carbon atom adjacent to the N atom has no hydrogen atom, and can be used as a light stabilizer. Examples of such a piperidine ring include a 2,2,6,6-tetramethylpiperidine ring in which a methyl group is bonded to a carbon atom adjacent to the N atom. These hindered amine compounds may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, a commercial item can be used conveniently.

  Various additives such as rust preventives, dispersants, antifoaming agents, dehydrating agents, leveling agents, anti-settling agents, anti-algae agents, anti-fungal agents, preservatives, etc., are appropriately added to the above water-based undercoat paints as necessary May be. In addition, although an organic solvent may be used for the additive, in the water-based paint used in the present invention, the content of the organic solvent is less than 10% by mass from the viewpoint of suppressing environmental load. Preferably there is.

  The water-based undercoat paint is stored separately from an epoxy resin and a curing agent, and is prepared by mixing them immediately before painting. Epoxy resins are usually stored in combination with extender pigments and water, as well as various components appropriately selected as necessary, and are referred to as main agents. Further, the curing agent is usually stored in combination with water and various components appropriately selected as necessary, and this is referred to as a curing agent mixture. In order to adjust the viscosity of the water-based undercoat paint, water may be further added after mixing the main agent and the curing agent mixture.

  The water-based undercoat has a viscosity of 1 to 1000 (Pa · s, 23 ° C.) at a shear rate of 0.1 (1 / s), and a viscosity of 0.05 to 10 (at a shear rate of 1000 (1 / s). Pa · s, 23 ° C.). By adjusting the viscosity within the specified range, the coating workability can be improved. The reason why the viscosity is defined based on two shear rates of 0.1 (1 / s) and 1000 (1 / s) is that the viscosity at the shear rate of 0.1 (1 / s) is just after coating. The viscosity at a shear rate of 1000 (1 / s) is an index of the viscosity of the paint during brush coating or roller coating, and the viscosity of the paint immediately after coating from the time of coating is sagging and leveling. This is because it correlates with gender. In the present invention, the viscosity is measured after adjusting the liquid temperature to 23 ° C. using a rheometer ARES manufactured by TA Instruments.

  In the undercoat coating film forming step, the coating method is brush coating or roller coating, but from the viewpoint of coating a large-scale structure, a coating means such as a pressure brush or a pressure roller can also be used. According to the concrete exfoliation preventing method of the present invention, it is possible to form an undercoating film having a good visibility with a film thickness of 100 μm or more by one brush coating or roller coating.

  The undercoat coating film obtained by the undercoat coating film forming step preferably has a dry film thickness of 100 to 600 μm. In the present invention, the dry film thickness of the coating film refers to the film thickness after drying for 24 hours under the conditions of 23 ° C. and 50% relative humidity.

  In the concrete exfoliation preventing method of the present invention, a fiber sheet is then placed on the undercoat film formed in the first step (second step). Here, the fiber sheet is preferably placed on the coating film before the curing of the water-based undercoat paint is completed. Thereby, a fiber sheet can be affixed on an undercoat coating film.

  The said fiber sheet can be used with the shape of the sheet | seat used for the usual concrete peeling prevention construction method. For example, the fiber sheet has a lattice shape. In this case, the thickness of the fiber sheet is preferably 0.1 to 3 mm, and the mesh is preferably 0.1 to 20 mm on one side. In the anti-peeling performance, the tensile strength of the sheet is preferably 150 (N / 5 cm) or more. Examples of the fiber sheet include sheets composed of fibers such as glass fiber, vinylon fiber, polyamide fiber, polyethylene fiber, polyparaphenylene fiber, polyarylate fiber, aramid fiber, and carbon fiber. From the viewpoint of visibility, a glass fiber sheet is particularly preferable.

  In the concrete exfoliation preventing method of the present invention, next, a water-based top coating is applied so as to cover the undercoat coating film and the fiber sheet to form a top coating film (top coating film forming step or third step).

  Various paints can be used as long as the water-based topcoat is a paint containing water as a main solvent. Before the water-based basecoat is cured, the fiber sheet is applied and the topcoat is applied. From the viewpoint of finishing, it is preferable that the water-based top coating is a two-component reaction curable coating containing an epoxy resin and a curing agent. Thereby, the whole construction can be completed in a short time. The water-based topcoat paint preferably contains extender pigments, thixotropic agents, UV-absorbing compounds, and hindered amine compounds for the same reasons as described in the description of the water-based undercoat paint. The described paint can be suitably used as a water-based top coat.

  The top coat film may be formed by a plurality of different water based top coats. For example, when two types of water-based topcoat are used, the topcoat is composed of a first layer formed so as to cover the undercoat and the fiber sheet, and a second layer formed on the first layer. Is done. For this reason, a preferable coating material can be selected for the first layer from the relationship with the undercoat coating film and the fiber sheet, and a preferable coating material for forming the outermost layer can be selected for the second layer. .

  In the top coat film forming step, the coating method is not particularly limited, and a known coating means, for example, brush coating, roller coating, trowel coating, spatula coating, spray coating, etc. can be used. In consideration of even coating on objects, brush coating and roller coating are suitable.

  The top coating film obtained by the top coating film forming step preferably has a dry film thickness of 30 to 600 μm. In the present invention, the dry film thickness of the coating film refers to the film thickness after drying for 24 hours under the conditions of 23 ° C. and 50% relative humidity.

  According to the concrete exfoliation preventing method of the present invention, all the coating films (specifically, the undercoat film and the topcoat film) constituting the laminate can be formed from a water-based paint, and the load on the environment is low. Therefore, the present invention is a healthy and safe concrete peeling prevention method that is preferable from the viewpoint of prevention of organic solvent poisoning to workers, and is applied in an area where many people gather, such as urban areas and downtown areas. Even odor problems do not occur. Moreover, if all the coating films which comprise a laminated body can be formed from a water-system coating material, it will not lead to secondary disasters, such as a fire spread, even if a fire occurs.

  In the concrete peeling prevention method according to the present invention, the laminate preferably has a thickness in the range of 200 to 1500 μm, and more preferably in the range of 300 to 1500 μm.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

  In accordance with the formulation shown in Tables 1-2, main agents 1-16 and curing agent mixtures 1-4 were prepared.

(Note 1) Beckpox EP2381 (Ornex bisphenol A type epoxy resin emulsion, solid content 55% by mass, epoxy equivalent 500 g / eq (solid content))
(Note 2) Epolsion EA55 (Nippon NSC bisphenol A type epoxy resin emulsion, solid content 55% by mass, epoxy equivalent 495 g / eq (solid content))
(Note 3) jER W3435R67 (Mitsubishi Chemical Corporation bisphenol A type epoxy resin dispersion, solid content 67% by mass, epoxy equivalent 273 g / eq (solid content))
(Note 4) AEROSIL R972 (hydrophobic foamed silica manufactured by Nippon Aerosil Co., Ltd.)
(Note 5) Silicia 350 (Fuji Silysia fine powder silica, average particle size 3.9 μm)
(Note 6) MC-K (Calcium carbonate manufactured by Maruo Calcium Co., Ltd., average particle size 0.05 μm)
(Note 7) Varifine BF-20 (barium sulfate, Sakai Chemical Co., Ltd., average particle size 0.03 μm)
(Note 8) Thixol W-502 (Aqueous dispersion of polyacrylic acid thixotropic agent manufactured by Kyoeisha, thixotropic agent content: 21% by mass)
(Note 9) Tinuvin 400 (manufactured by BASF, hydroxyphenyltriazine (HPT) UV absorber)
(Note 10) Fuji Cure FXS-918-FA (manufactured by T & K TOKA, an aqueous dispersion of an epoxy adduct type modified polyamine compound in which an epoxy group is added to an amino group, solid content 60 mass%)
(Note 11) EK8545-W52 (Momentive Co., Ltd., modified polyamidoamine aqueous dispersion obtained by amidating the amino group of polyamine, solid content 52 mass%)
In Tables 1 and 2, the heating residue refers to a component remaining when the main agent or the curing agent mixture is heated at 150 ° C. for 60 minutes.

(Examples 1-19 and Comparative Examples 1-2)
A paint according to the formulation shown in Table 3 was prepared as an undercoat paint, and various tests were performed. The results are shown in Table 3. In the case of using the top coat, except for Example 18, the same paint as the undercoat was used as the top coat. The top coat of Example 18 is a DNT view urethane clear (Dai Nippon Paint, 1-component reactive water-based urethane resin paint, clear paint), which is a paint different from the undercoat paint. Was performed after curing the undercoat film for 24 hours. Moreover, in Comparative Example 1, when a coating film having a film thickness of 100 μm was formed, the coating was repeated a plurality of times.

<Coating workability>
The horizontal surface of the concrete base material was painted with a paint, and the coating workability was evaluated according to the following criteria. The paint workability was evaluated for both brushes and rollers.
A: A uniform coating film of 300 μm or more can be easily formed by a single coating.
○: A uniform coating film of 100 μm or more but less than 300 μm can be easily formed by one coating.
X1: The film thickness becomes thin, and a uniform coating film of 100 μm or more cannot be formed by one coating.
X2: Although a thick film can be formed partially, coating unevenness is large and a uniform coating film cannot be formed.

<Sauce limit>
The vertical surface of the polypropylene plate (thickness 150 mm, width 70 mm) was painted with a brush with a paint, and the coating was completed when sagging occurred. Thereafter, the coating film was dried at a temperature of 23 ° C. and a relative humidity of 50% for 168 hours, and the thickness of the coating film located 20 mm below the upper end of the polypropylene plate was evaluated as a sagging limit. The film thickness was measured using a caliper after peeling the coating film from the polypropylene plate.

<Visible light transmittance>
With a brush, a polypropylene plate is applied with a paint so that the film thickness becomes 100 μm to form an undercoat film, then the fiber sheet described below is placed, and then with a brush, the film thickness becomes 100 μm. The undercoat film and the fiber sheet were coated with a paint to form a topcoat film. Thereafter, the laminate was dried at a temperature of 35 ° C. and a relative humidity of 90% for 168 hours, and peeled off from the polypropylene plate. A 50 mm × 50 mm test piece was cut out from the laminate. The total light transmittance of the test piece was measured based on JIS K 7375 using a Macbeth spectrophotometer CE-3100 manufactured by Sakata Inx Corporation. Specifically, the total light transmittance was measured every 10 nm from 360 nm to 750 nm, and a value obtained by dividing the total of the obtained 40 data by the number of data was defined as the visible light transmittance.
In addition, as for a fiber sheet, Examples 1-18 and Comparative Examples 1-2 are glass crenette G44126 [made by Kurashiki Boseki Co., Ltd., tensile strength, length: 480, width: 420 ((N / 5cm (the number of yarns, length : 20 pieces, width: 15 pieces)), thickness: 0.20 (mm)], and Example 19 is polyester krenette E4500 [manufactured by Kurashiki Boseki Co., Ltd., tensile strength, length: 800, width: 860 (( N / 5 cm) (number of yarns, length: 5, length: 5)), thickness: 0.26 (mm)].

<Base material visibility>
With a brush, those that can easily form a uniform coating of 100 μm or more by one coating (Examples 1 to 19 and Comparative Example 2) have a uniform coating of 100 μm or more so that the film thickness becomes 100 μm. For those that cannot be formed by a single coating (Comparative Example 1), a concrete base material is coated with a paint so as to have a film thickness limit of one coating (40 μm), and then an undercoat film is formed. Then, a top coat film was formed by brushing in the same manner as the undercoat. Thereafter, the laminate was dried at a temperature of 35 ° C. and a relative humidity of 90% for 168 hours, and the concrete substrate was visually observed from above the laminate, and evaluated according to the following criteria.
In addition, as for a fiber sheet, Examples 1-18 and Comparative Examples 1-2 are glass crenette G44126 [made by Kurashiki Boseki Co., Ltd., tensile strength, length: 480, width: 420 ((N / 5cm (the number of yarns, length : 20 pieces, width: 15 pieces)), thickness: 0.20 (mm)], and Example 19 is polyester krenette E4500 [manufactured by Kurashiki Boseki Co., Ltd., tensile strength, length: 800, width: 860 (( N / 5 cm) (number of yarns, length: 5, length: 5)), thickness: 0.26 (mm)].
(Double-circle): The base-material surface can be confirmed clearly.
◯: The surface of the substrate that is not clear can be confirmed.
X: The substrate surface cannot be confirmed.

<Peeling prevention performance>
With a brush, those that can easily form a uniform coating of 100 μm or more by one coating (Examples 1 to 19 and Comparative Example 2) have a uniform coating of 100 μm or more so that the film thickness becomes 100 μm. For those that cannot be formed by a single coating (Comparative Example 1), a concrete base material is coated with a paint so as to have a film thickness limit of one coating (40 μm), and then an undercoat film is formed. Next, with a paint, the thickness of the fiber sheet is set to 100 μm (Examples 1 to 17, 19 and Comparative Example 2), 40 μm (Comparative Example 1), or 30 μm (Example 18) with a brush. The undercoating film and the fiber sheet were applied to form an overcoating film, and then the laminate was dried at a temperature of 35 ° C. and a relative humidity of 90% for 168 hours.
In addition, as a concrete base material, the U type lid prescribed | regulated to JIS A 5372: 2004 (precast reinforced concrete product) and 1 type (400x600x60mm) nominal name were used.
In addition, as for the fiber sheet, Examples 1 to 18 and Comparative Examples 1 and 2 were made of glass krenette G44126 [manufactured by Kurashiki Boseki Co., Ltd., tensile strength, length: 480, width: 420 ((N / 5 cm (number of yarns, length : 20 pieces, width: 15 pieces)), thickness: 0.20 (mm)], and Example 19 is polyester krenette E4500 [manufactured by Kurashiki Boseki Co., Ltd., tensile strength, length: 800, width: 860 (( N / 5 cm) (number of yarns, length: 5, length: 5)), thickness: 0.26 (mm)].
Next, the concrete base material provided with the laminate was subjected to the anti-peeling performance test in accordance with the “Tokyo Metropolitan Expressway Co., Ltd. Bridge Structure Design Guidelines, Concrete Fragment Prevention Version August 2006”, and in accordance with the following standards: evaluated.
-Load resistance ◯: punching load per φ10 cm is 0.3 kN or more.
X: The punching load per φ10 cm is less than 0.3 kN.

<Adhesion test>
Except for the type of concrete base material and the drying conditions of the laminate, the laminate was formed in the same manner as in the <Prevention of peeling-off performance>. As a concrete base material, a mortar piece having a size of 20 × 70 × 70 mm was used. As drying conditions, curing was performed for 7 days and 30 days in a thermostatic chamber (humidity 50% RH) at 23 ° C. and 5 ° C., respectively. Next, a peeling test using a Kenken-type adhesion tester was performed on the concrete base material provided with the laminate, and the numerical value at the time of peeling was evaluated according to the following criteria.
A: 1.5 N / mm ² or more.
×: 1.5N / mm less than ^2.

<Durability (weather resistance) test>
With a brush, the concrete base material is applied with a paint so that the film thickness becomes 100 μm to form an undercoat film, and then the fiber sheet described below is arranged, and then with the brush, the film thickness becomes 100 μm. As described above, the undercoat film and the fiber sheet were coated with a paint to form a topcoat film. Thereafter, the laminate was dried at a temperature of 35 ° C. and a relative humidity of 90% for 168 hours to prepare a test plate. The obtained test plate was subjected to an irradiation test for 400 hours using EYE SUPER UV TESTER SUV-W23 manufactured by Iwasaki Electric Co., Ltd. With respect to the test plate after irradiation, the concrete base material was visually observed from the top of the laminate, and evaluated according to the following criteria.
In addition, as for a fiber sheet, Examples 1-3, 7-14, 16-18, and the comparative example 1 are glass crenet G44126 [the Kurashiki Boseki Co., Ltd. make, tensile strength, length: 480 width: 420 (N / 5cm ( Number of yarns, length: 20 pieces, width: 15 pieces)), thickness: 0.20 (mm)], and Example 19 is polyester krenette E4400 [manufactured by Kurashiki Boseki Co., Ltd., tensile strength, length: 320 width: 350 (N / 5 cm (number of yarns, length: 10 pieces, width: 10 pieces)), thickness: 0.26 (mm)].
(Double-circle): The base-material surface can be confirmed clearly.
◯: The surface of the substrate that is not clear can be confirmed.
(Triangle | delta): The base-material surface of what the coating film turned yellow can be confirmed.
X: The substrate surface cannot be confirmed.

<Viscosity>
After adjusting the liquid temperature of the paint to 23 ° C., the viscosity (Pa · s) at a shear rate of 0.1 s ⁻¹ and 1,000 s ⁻¹ was measured using a rheometer ARES manufactured by TA Instruments.

Claims (6)

A method of preventing a concrete from peeling off from a concrete structure by forming a laminate including an undercoat film, a fiber sheet, and a topcoat film on the surface of the concrete structure,
A first step of painting a surface of a concrete structure with a water-based undercoating paint by brush painting or roller coating to form an undercoating film, wherein the water-based undercoating paint contains an epoxy resin, a curing agent and an extender pigment It is a two-component reaction curable paint, the content of extender pigment in the water-based undercoat paint is in the range of 0.1 to 10% by mass, and the content of water in the water-based undercoat paint is 15 to 70% by mass. A first step which is
A second step of disposing a fiber sheet on the undercoat film;
Including a third step of applying a water-based topcoat so as to cover the undercoat and the fiber sheet, and forming a topcoat
The laminate state, and are visible light transmittance of the wavelength 360~750nm 30% or more,
The water-based undercoat has a viscosity of 1 to 1000 (Pa · s, 23 ° C.) at a shear rate of 0.1 (1 / s), and a viscosity of 0.05 to 10 (shear rate of 1000 (1 / s). Pa · s, 23 ℃) der wherein the Rukoto. The method according to claim 1, wherein the water-based top coating is a two-component reaction curable coating containing an epoxy resin and a curing agent. The method according to any one of claims 1-2, wherein the extender pigment is silica. Wherein said water-based primer coating further thixotrope, claim 1-3 in which the content of the thixotropic agent in the water-based undercoat paint is characterized in that in the range of 0.01 to 5 mass% The method according to one item. The aqueous primer coating further method according to any one of claims 1 to 4, characterized in that it comprises at least one ultraviolet absorbing compound and hindered amine compound. The method according to any one of claims 1 to 5, wherein said laminate of thickness, characterized in that in the range of 200～1500Myuemu.