Method for applying a spalling prevention layer

Abstract

The present invention aims to provide a method for constructing a spalling prevention layer that simplifies the work process compared to conventional methods and can form a spalling prevention layer with sufficient strength and elongation at fracture. [Solution] A method for applying a peeling prevention layer, comprising a step of forming a peeling prevention layer by applying a urethane-based composition to the exterior wall of a building and curing it, wherein the urethane-based composition contains a urethane prepolymer having isocyanate groups and a filler, and the urethane prepolymer is formed from a polyisocyanate compound having multiple isocyanate groups per molecule and a polyol containing butanediol and polyoxyalkylene polyol, and the molar equivalent ratio of butanediol to polyoxyalkylene polyol (butanediol:polyoxyalkylene polyol) is 60:40 to 75:25.

Description

Technical Field

[0001] The present invention relates to a method for applying an anti-peeling layer.

Background Art

[0002] Conventionally, the outer wall of a building may be a tiled outer wall or a mortar-coated outer wall. Some or all of these outer walls are at risk of floating or peeling off from the concrete structure due to earthquakes or aging deterioration. The detachment or breakage and falling of a part of the outer wall from the building will be described below using the attached drawings. FIG. 1 is a cross-sectional view schematically showing the outer wall of a building. In FIG. 1(a), in the outer wall 2 of the building 1, tiles 5 are attached to the surface of the wall 3 of the building 1 via a mortar layer 4. However, due to an earthquake or the like, a part of the mortar layer 6 including the tiles 5 and the tiles 7 are shown to have peeled off from the building 1. Further, FIG. 1(b) shows that a part of the wall 3 of the building 1 has been damaged due to an earthquake or the like, and the damaged wall 8 has fallen from the building 1. Note that in FIGS. 1(a) and (b), the outer wall of the building does not have an anti-peeling layer. Regarding the above problems, it is known that a urethane-based composition can be used as an anti-peeling paint or the like (for example, Patent Document 1). In addition, a resin layer having a fibrous body formed by arranging fiber yarns in a mesh shape on a concrete structure (for example, Patent Document 2), or a construction method for preventing the peeling of concrete by forming a reinforcing cloth is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventionally, anti-spraying layers were applied to the exterior walls of buildings by first installing a mortar layer, and then applying a surface coating layer (for example, the tile anti-spraying paint described above) on top of the mortar layer. The conventional method of applying anti-spraying layers described above will be explained below with reference to the attached diagrams. Figure 2 is a schematic cross-sectional perspective view showing the exterior wall of a building using a conventional method for constructing a spalling prevention layer. Note that in Figure 2, each layer of the building's exterior wall is shown in a cut-out state. In Figure 2, the building's exterior wall 21 has tiles 23 attached to the surface of the wall, a primer layer 25 on the tiles 23, a mortar layer 27 on the primer layer 25, and a spalling prevention layer 29 on the mortar layer 27. Alternatively, as described above, there have been construction methods to prevent concrete spalling by forming a resin layer having fibrous material (for example, Patent Document 2) or a reinforcing cloth on a concrete structure, which is formed by arranging fibrous threads in a mesh-like manner. However, conventional construction methods, such as applying a mortar layer outside of the tiles or applying a resin layer containing the aforementioned fibers onto a concrete structure, are complicated. If such steps can be eliminated, the work process can be simplified up to the point of applying the anti-spraying layer. Furthermore, the present inventors, assuming a situation where there is no resin layer having the above-mentioned fibrous material on the mortar layer or concrete structure outside the tile, evaluated a cured urethane composition based on Patent Document 1 as a spalling prevention layer, and found that the strength and / or elongation at fracture of the resulting cured product may be insufficient.

[0005] Therefore, the object of the present invention is to provide a method for constructing a spalling prevention layer that simplifies the work process compared to conventional methods and can form a spalling prevention layer having sufficient strength and elongation rate at fracture. [Means for solving the problem]

[0006] As a result of diligent research to solve the above problems, the present inventors have found that the above problems can be solved by having a forming step in which a urethane composition is applied to the exterior wall of a building and cured to form a peeling prevention layer, wherein the method for applying a peeling prevention layer includes a urethane prepolymer having isocyanate groups and a filler, the urethane prepolymer being formed from a polyisocyanate compound having multiple isocyanate groups per molecule and a polyol containing butanediol and polyoxyalkylene polyol, and the molar equivalent ratio of the butanediol to the polyoxyalkylene polyol (butanediol:polyoxyalkylene polyol) is 60:40 to 75:25, and the urethane composition is applied to the exterior wall of a building and cured to form a peeling prevention layer, thus leading to the present invention. The present invention is based on the above findings, and specifically solves the above problems with the following configuration.

[0007] [1] The process includes a step of forming a peeling prevention layer by applying a urethane-based composition to the exterior wall of a building and curing it to form a peeling prevention layer, The above urethane-based composition It contains a urethane prepolymer having an isocyanate group and a filler, The above-mentioned urethane prepolymer is formed from a polyisocyanate compound having multiple isocyanate groups per molecule and a polyol containing butanediol and polyoxyalkylene polyol, and the molar equivalent ratio of the butanediol to the polyoxyalkylene polyol (butanediol:polyoxyalkylene polyol) is 60:40 to 75:25, and is a method for applying a peeling prevention layer. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for constructing a spalling prevention layer that simplifies the work process compared to conventional methods and can form a spalling prevention layer having sufficient strength and elongation rate at fracture. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing the exterior wall of a building. [Figure 2] This is a schematic cross-sectional perspective view showing the exterior wall of a building constructed using a conventional method for applying a delamination prevention layer. [Figure 3] This is a schematic cross-sectional perspective view showing an example of a building exterior wall constructed using the method for applying the peeling prevention layer of the present invention. [Figure 4] This is a schematic cross-sectional perspective view showing another example of the exterior wall of a building constructed using the method for applying the peeling prevention layer of the present invention. [Figure 5] This is a schematic diagram illustrating the apparatus used for bending tests in this specification. [Figure 6] This is a schematic diagram illustrating the changes in an evaluation sample before and after applying a load during a bending test. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below. The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, when using a certain component, unless otherwise specified, that component may be used alone or in combination of two or more types. In this specification, if two or more components are present, the "content" of those components means the total content of those two or more components unless otherwise specified. In this specification, the method of producing a certain component is not limited unless otherwise specified. Examples include conventionally known methods. In this specification, the urethane-based composition used in the method for applying the peeling prevention layer of the present invention is also referred to as the "specific urethane-based composition." In this specification, the urethane prepolymer contained in the urethane composition is also referred to as the "specific urethane prepolymer."

[0011] [Application method for the anti-spraying layer] The method for applying the anti-peeling layer of the present invention (the application method of the present invention) is characterized by having an anti-peeling layer forming step of applying a urethane-based composition to the outer wall of a building and curing it to form an anti-peeling layer. The above urethane-based composition contains a urethane prepolymer having an isocyanate group and a filler. The above urethane prepolymer is formed by a polyisocyanate compound having a plurality of isocyanate groups per molecule and a polyol containing butanediol and polyoxyalkylene polyol, and the molar equivalent ratio of the above butanediol to the above polyoxyalkylene polyol (butanediol: polyoxyalkylene polyol) is 60:40 to 75:25. This is the method for applying the anti-peeling layer.

[0012] [Anti-peeling layer forming step] The method for applying the anti-peeling layer of the present invention (the application method of the present invention) has an anti-peeling layer forming step of applying a specific urethane-based composition to the outer wall of a building and curing it to form an anti-peeling layer.

[0013] [Outer wall of a building] In the anti-peeling layer forming step, when applying the specific urethane-based composition, examples of the outer wall of the building include the wall of the building (the wall of the building itself). Also, the outer wall of the building may be, for example, an outer wall with tiles or an outer wall painted with mortar. There is a risk that these outer walls or a part of them may float or peel off from the concrete structure due to aging deterioration. The tiles that the outer wall of the building may have are not particularly limited. The tiles may be arranged one or more than one on one outer wall. When two or more tiles are arranged on one outer wall, there may be a gap between adjacent tiles. The gap between the tiles may be filled with a sealing material. The sealing material that the outer wall of the building may have is not particularly limited. For example, conventionally known ones can be mentioned. The tiles may be attached to the exterior wall of a building (the exterior wall of a building before the tiles are placed; for example, the wall of the building itself) via an adhesive layer. An example of the adhesive layer is a mortar layer. The mortar layer is not particularly limited as long as it is formed using a mortar composition containing at least water and sand. The mortar composition may further contain gravel, aggregate, etc. The adhesive layer may also be, for example, a concrete layer.

[0014] [Urethane-based composition] The urethane-based composition (specific urethane-based composition) used in the peeling prevention layer formation process is: It contains a urethane prepolymer having an isocyanate group and a filler, The above-mentioned urethane prepolymer is a urethane-based composition formed from a polyisocyanate compound having multiple isocyanate groups per molecule and a polyol containing butanediol and polyoxyalkylene polyol, wherein the molar equivalent ratio of the butanediol to the polyoxyalkylene polyol (butanediol:polyoxyalkylene polyol) is 60:40 to 75:25.

[0015] [Urethane prepolymer] The specific urethane composition contains a urethane prepolymer having an isocyanate group. The above-mentioned urethane prepolymer is formed from a polyisocyanate compound having multiple isocyanate groups per molecule and a polyol containing butanediol and polyoxyalkylene polyol, and is a urethane prepolymer (specific urethane prepolymer) in which the molar equivalent ratio of butanediol to polyoxyalkylene polyol (butanediol:polyoxyalkylene polyol) is 60:40 to 75:25.

[0016] One preferred embodiment of the specific urethane prepolymer is that it has the above-mentioned isocyanate group at its terminal end. From the viewpoint of having superior strength and / or elongation at break of the resulting cured product (i.e., the delamination prevention layer; the same applies hereinafter), it is preferable that the specific urethane prepolymer has two of the above-mentioned isocyanate groups in one molecule of the specific urethane prepolymer.

[0017] [Polyisocyanate compounds] The polyisocyanate compounds used to form specific urethane prepolymers are not particularly limited as long as they are compounds having multiple isocyanate groups per molecule. Examples include aromatic diisocyanates such as diphenylmethane-4,4'-diisocyanate (MDI), carbodiimide-modified diphenylmethane diisocyanate (liquid MDI), polymethylene polyphenyl isocyanate (crude MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), and xylylene diisocyanate (XDI); and aliphatic diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate (IPDI). The polyisocyanate compound used to form a specific urethane prepolymer preferably contains an aliphatic diisocyanate, and more preferably contains an isophorone diisocyanate, from the viewpoint of having superior strength and / or elongation at break of the resulting peeling-resistant layer (cured product).

[0018] [Polyol] In the present invention, the polyol used to form a specific urethane prepolymer includes butanediol and polyoxyalkylene polyol. Polyols refer to compounds that have multiple hydroxyl groups per molecule.

[0019] [Butanediol] In the present invention, the butanediol used to form the specific urethane prepolymer is not particularly limited, but it is preferable to include 1,4-butanediol from the viewpoint of having superior strength and / or elongation at fracture of the resulting peeling-resistant layer (cured product).

[0020] [Polyoxyalkylene polyol] In the present invention, the polyoxyalkylene polyol used to form a specific urethane prepolymer refers to a polyoxyalkylene compound having multiple hydroxyl groups per molecule. Examples of oxyalkylene groups that constitute polyoxyalkylene polyols include oxyethylene groups, oxypropylene groups, and combinations thereof. Examples of polyoxyalkylene polyols include polyoxyalkylenediol and polyoxyalkylentriol, and specifically, examples include polyoxypropylenediol and polyoxypropylenetriol. From the viewpoint of obtaining superior strength and / or elongation at fracture of the resulting peeling prevention layer (cured product), the polyoxyalkylene polyol preferably contains polyoxyalkylenediol, and more preferably contains polyoxypropylenediol. When the polyoxyalkylene polyol contains polyoxyalkylenediol, one preferred embodiment is one in which the polyoxyalkylene triol is not included. The number-average molecular weight of the polyoxyalkylene polyol is preferably 1500 to 5000, and more preferably 1800 to 2500, from the viewpoint of obtaining superior strength and / or elongation at break of the resulting peeling-preventing layer (cured product). In this specification, the number-average molecular weight of a compound can be obtained in terms of polystyrene equivalent by gel permeation chromatography.

[0021] [Molar equivalent ratio of butanediol and polyoxyalkylene polyol] In the present invention, the molar equivalent ratio (butanediol:polyoxyalkylene polyol) of the butanediol and polyoxyalkylene polyol used to form a specific urethane prepolymer is 60:40 to 75:25. By keeping the above molar equivalent ratio within the specified range, the resulting delamination-preventing layer (hardened material) exhibits superior strength and elongation at fracture. The above molar equivalent ratio is preferably 68:32 to 75:25, from the viewpoint of obtaining superior strength and / or elongation at fracture of the resulting delamination-preventing layer (cured product).

[0022] (Isocyanate group content of specific urethane prepolymers) From the viewpoint of obtaining superior strength and / or elongation at break of the resulting peeling prevention layer (cured product), the isocyanate group content of the specific urethane prepolymer is preferably 6.0 to 9.0% by mass, and more preferably 7.0 to 8.0% by mass.

[0023] The above polyol may further contain polyols other than the above butanediol and polyoxyalkylene polyol (other polyols). Examples of other polyols include polyester polyols. The polyester polyol is not particularly limited.

[0024] From the viewpoint of obtaining superior strength and / or elongation at fracture of the resulting peeling prevention layer (cured product), it is preferable that the above polyol contains the above butanediol and the above polyoxyalkylene polyol in a total amount of 50 to 100% by mass of the total polyol.

[0025] (Content of specific urethane prepolymers) From the viewpoint of achieving a better balance between the strength and / or elongation at fracture and workability of the resulting peeling prevention layer (cured product), the content of the specific urethane prepolymer is preferably 30 to 50% by mass of the total amount of the specific urethane composition.

[0026] (Method for preparing specific urethane prepolymers) The method for preparing the specific urethane prepolymer is not particularly limited, but for example, a solution is prepared by weighing and mixing 1,4-butanediol and polypropylene glycol (polyoxypropylenediol) with a number average molecular weight of 2000 in a predetermined molar equivalent ratio, and then, taking into account the amount of water in the polypropylene glycol, isophorone diisocyanate (IPDI) is added so that the molar equivalent ratio (NCO / OH) of isocyanate groups of the isophorone diisocyanate to the total amount of hydroxyl groups of the 1,4-butanediol and polypropylene glycol is greater than 1.0 and less than or equal to 3.0 to form a liquid mixture, and then heating the liquid mixture while stirring, adding a catalyst in an amount of 0.01 to 1% by mass of the total liquid mixture, and reacting under conditions of 70 to 110°C to prepare the specific urethane prepolymer. In this specification, the above molar equivalent ratio (NCO / OH) represents the molar equivalent ratio of isocyanate groups in a polyisocyanate compound to hydroxyl groups in a polyol containing butanediol and polyoxyalkylene polyol used in the preparation of a specific urethane prepolymer. Regarding the molar equivalent of hydroxyl groups in the above molar equivalent ratio (NCO / OH), as described above, the amount of water contained in the polyoxyalkylene polyol, such as polypropylene glycol, may or may not be added to the total molar equivalent of the hydroxyl groups.

[0027] The catalysts that can be used when preparing specific urethane prepolymers are not particularly limited as long as they are compounds that can promote the reaction between the isocyanate group and the polyol. Examples include organotin compounds (tin catalysts) such as dibutyltin diacetate, dibutyltin dilaurate, and dibutyltin bis(3-mercaptopropionate ethoxybutyl ester) salt; organotitanium compounds such as titanic acid, tetraisopropyl titanate, tetra-n-butyl titanate, polyhydroxytitanium stearate, and titanium acetylacetonate; and tertiary amine compounds such as triethylenediamine, N-methylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylhexamethylenediamine, triethylamine, and N,N-dimethylaminoethanol.

[0028] [Filler] It contains a specific urethane-based composition and fillers. Certain urethane compositions can exhibit thixotropy by containing fillers. Examples of fillers include calcium carbonate, surface-treated calcium carbonate, and silica. From the viewpoint of adjusting the filler to a state in which a specific urethane composition can be applied to the exterior wall (excellent thixotropy), it is preferable that the filler contains at least one or more selected from the group consisting of calcium carbonate, surface-treated calcium carbonate, and silica, more preferably calcium carbonate and / or surface-treated calcium carbonate, and even more preferably calcium carbonate and / or surface-treated calcium carbonate and silica.

[0029] (silica) Examples of silica include natural silica obtained by crushing quartz, silica sand, diatomaceous earth, etc.; and synthetic silica such as wet silica (e.g., sedimentation silica) and dry silica (e.g., fumed silica). Silica may be either hydrophilic or hydrophobic.

[0030] (Calcium carbonate) Examples of calcium carbonate include precipitated calcium carbonate, light calcium carbonate, and heavy calcium carbonate. In this specification, calcium carbonate does not include surface-treated calcium carbonate.

[0031] (Surface-treated calcium carbonate) Examples of surface-treated calcium carbonate include calcium carbonate whose surface has been treated with a surface treatment agent. Examples of surface treatment agents include fatty acids, fatty acid alkyl esters, fatty acid metal salts, metal salts of resin acids such as rosinic acid, reaction products of organic polyisocyanates and stearyl alcohol, and silane coupling agents. Examples of fatty acid metal salts include sodium, potassium, calcium, and aluminum salts of fatty acids having 10 to 25 carbon atoms, such as stearic acid.

[0032] (Filler content) From the viewpoint of obtaining superior strength and / or elongation at fracture of the resulting peeling prevention layer (cured product), the filler content is preferably 20 to 50% by mass of the total amount of the specific urethane composition.

[0033] (Latent curing agent) Preferably, the specific urethane-based composition further contains a latent curing agent. If a specific urethane composition further contains a latent curing agent, the latent curing agent can be hydrolyzed upon contact with moisture (e.g., moisture in the air) to produce a compound having a functional group containing an active hydrogen group (e.g., an amino group, an imino group, or a hydroxyl group). If the specific urethane-based composition further contains a latent curing agent, the specific urethane-based composition can be made into a one-component urethane-based composition.

[0034] The latent curing agent preferably contains a compound having an oxazolidine ring, and more preferably contains a bis-oxazolidine compound in which two oxazolidine rings are crosslinked by a linking group having a urethane bond, from the viewpoint of providing superior strength and / or elongation at fracture of the resulting peeling-preventing layer (cured product). The latent curing agent having an oxazolidine ring can be hydrolyzed to produce a curing agent having a reactive amine (e.g., an imino group) and a hydroxyl group. The oxazolidine ring that the latent curing agent may have is not particularly limited. For example, one preferred embodiment is that the carbon atom at position 2 of the oxazolidine ring (the single carbon atom between the oxygen atom and the nitrogen atom) is substituted with an alkyl group. The alkyl group is not particularly limited. The alkyl group may be linear or branched, and one preferred embodiment is that it is branched. Examples of the linking groups having the above-mentioned urethane bond include groups represented as -ABCDE-, where A, C, and E are each independently alkylene groups having 1 to 10 carbon atoms, and B and D are each urethane bonds. The alkylene group having 1 to 10 carbon atoms may be linear or branched, with linear being one preferred embodiment. In the above embodiment, the alkylene group having 1 to 10 carbon atoms as A and E is preferably an alkylene group having 1 to 6 carbon atoms. In one preferred embodiment, the alkylene group having 1 to 10 carbon atoms as C is an alkylene group having 4 to 8 carbon atoms. The above linking group can be bonded to, for example, a nitrogen atom on the oxazolidine ring.

[0035] Examples of bis-oxazolidine compounds in which two oxazolidine rings are crosslinked by a linking group having a urethane bond include the compound represented by the following formula. [ka] The method for preparing compounds having an oxazolidine ring as latent curing agents is not particularly limited. For example, conventionally known methods can be used.

[0036] (Content of latent hardening agent) From the viewpoint of obtaining superior strength and / or elongation at fracture of the resulting peeling prevention layer (cured product), the content of the latent curing agent is preferably 0 to 20% by mass, and more preferably 5.0 to 15% by mass, of the total amount of the specific urethane composition.

[0037] (At least one selected from the group consisting of UV absorbers, light stabilizers, and antioxidants) The specific urethane composition preferably further contains at least one selected from the group consisting of ultraviolet absorbers, light stabilizers, and antioxidants, and more preferably contains ultraviolet absorbers, light stabilizers, and antioxidants.

[0038] (UV absorber) Examples of UV absorbers include benzotriazole-based UV absorbers such as 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, triazine-based UV absorbers such as 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol, benzophenone-based UV absorbers such as octabenzone, and benzoate-based UV absorbers such as 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate.

[0039] (Light stabilizer) Examples of light stabilizers include hindered amine-based light stabilizers, specifically bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0040] (Antioxidant) Examples of antioxidants include hindered phenol antioxidants, specifically pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexane-1,6-diyrbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propioamide], benzenepropanoate 3,5-bis(1,1-dimethylethyl)-4-hydroxyC7-C9 side-chain alkyl ester, and 2,4-dimethyl-6-(1-methylpentadecyl)phenol.

[0041] (At least one selected from the group consisting of UV absorbers, light stabilizers, and antioxidants) The content of at least one selected from the group consisting of ultraviolet absorbers, light stabilizers, and antioxidants (or the total content of all of these if all of them are included) is preferably 0.1 to 3.0% by mass of the total amount of the specific urethane composition, and more preferably 0.1 to 1.0% by mass, from the viewpoint of having superior strength and / or elongation at break of the resulting peeling prevention layer (cured product).

[0042] (Additives) The specific urethane-based composition may, if necessary, contain additional additives in addition to the above-mentioned components, to the extent that it does not impair the objective of the present invention. Examples of additives include pigments, defoamers, stabilizers, metal catalysts, organic solvents, dispersants, acid catalysts, and drying agents. When the specific urethane-based composition further contains various additives, their types and amounts can be selected as appropriate.

[0043] (Organic solvents) If a specific urethane composition further contains an organic solvent, the organic solvent is not particularly limited as long as it is a compound that does not react with the above components. Examples of organic solvents include conventionally known organic solvents such as aliphatic solvents such as n-hexane, alicyclic solvents such as cyclohexane, aromatic solvents such as toluene and xylene, and petroleum-based solvents containing these. The solvent content can be 0 to 20% by mass of the total amount of the specific urethane composition.

[0044] (Plasticizer) One preferred embodiment is that the specific urethane composition is substantially free of plasticizers. In the present invention, "substantially free of plasticizers" means that the plasticizer content is 0 to 2.0% by mass of the total amount of the specific urethane composition.

[0045] (Method for manufacturing urethane-based compositions) The method for producing the specific urethane-based composition is not particularly limited. For example, the specific urethane-based composition can be produced by mixing the above-mentioned components in the amounts described above.

[0046] [apply] In the process of forming a peeling prevention layer, there are no particular restrictions on the method of applying the specific urethane-based composition to the exterior wall of the building. For example, it can be applied using a roller, brush, spray gun, etc. In the process of forming a peeling prevention layer, it is preferable to apply a specific urethane-based composition to at least a part or all (entire surface) of the exterior wall of the building. In the construction method of the present invention, the amount of the specific urethane composition used is determined from the viewpoint of having superior strength and / or elongation at break of the resulting peeling prevention layer, for a 1m section of the exterior wall of a building. 2 It is preferable that the amount is 1 to 5 kg per serving.

[0047] [Cure] In the peeling prevention layer formation process, a specific urethane-based composition applied to the exterior wall of a building is cured. The temperature conditions for curing the specific urethane-based composition are not particularly limited, but for example, the specific urethane-based composition can be cured in air under conditions of 0 to 40°C. The curing time for a specific urethane-based composition can be, for example, 1 to 24 hours. After the above hardening process, a peeling prevention layer can be formed on the exterior wall of the building. In other words, the exterior wall of the building will have a peeling prevention layer. The thickness of the peeling prevention layer after hardening is preferably 1.0 to 3.0 mm, from the viewpoint of having superior strength and / or elongation at fracture.

[0048] [Peeling prevention layer] The spalling prevention layer formed (constructed) by the construction method of the present invention is a spalling prevention layer for the exterior walls of a building. According to the construction method of the present invention, it is possible to prevent the exterior walls of a building from peeling off the building. Specifically, for example, it is possible to prevent some mortar layers (mortar layers that bond the building's walls to the tiles) or tiles themselves from peeling off from tiled exterior walls, to prevent the mortar layer from peeling off from mortar-coated exterior walls, and to prevent damaged walls from falling off the building's exterior walls even if the building's walls themselves are damaged.

[0049] According to the construction method of the present invention, a spalling prevention layer with excellent strength and elongation ratio at fracture can be formed on the exterior wall of a building. In other words, by forming the above-mentioned spalling prevention layer on the exterior wall of a building (the exterior wall of a building having the above-mentioned spalling prevention layer), it is possible to prevent the exterior wall of the building or a part thereof from peeling off from the building. Therefore, in the construction method of the present invention, when forming a peeling prevention layer with a specific urethane-based composition on, for example, a tiled exterior wall or a mortar exterior wall, it is not necessary to apply a mortar layer outside the tiles (especially outside the primer layer on top of the tiles) as in existing construction methods, nor is it necessary to use a resin layer with fibers (e.g., mesh) or reinforcing fabric in the peeling prevention layer.

[0050] (Anchor pin insertion process) In the construction method of the present invention, before performing the primer layer formation step described later, a step may be performed to fix the existing exterior wall finish layer of the building to the structure (concrete structure) with anchor pins. This makes it possible to more reliably prevent the existing exterior wall of the building or a part thereof from peeling off (or falling off). Existing exterior wall of the building 1m 2 1 to 10 anchor pins (preferably 2 to 8, more preferably 3 to 5) can be used per unit.

[0051] (Primer layer formation process) The construction method of the present invention may further include a primer layer formation step, in which a primer is applied to the exterior wall of a building and cured to form a primer layer, prior to the peeling prevention layer formation step. The primer used to form the primer layer is not particularly limited. Examples include epoxy resin primers and urethane resin primers. In the primer layer formation process, there are no particular restrictions on the method of applying the primer to the exterior wall of the building. For example, it can be applied using a roller, brush, spray gun, etc. In the exterior walls of a building, at least a primer should be applied to the portion where a specific urethane-based composition is to be applied. There are no particular restrictions on the temperature conditions for drying the primer, but for example, the primer can be dried in air at temperatures between 0 and 40°C. The drying time for the primer can be, for example, 1 to 24 hours. The thickness of the primer layer can be, for example, 0.01 to 1.00 mm. If the construction method of the present invention further includes a primer layer formation step, a peeling prevention layer formation step may be performed after the primer layer formation step, and a specific urethane-based composition may be applied on top of the primer layer. Furthermore, if the exterior wall of a building is an uneven surface such as a tiled exterior wall, a mortar layer may be formed before forming the primer layer, not for the purpose of preventing the exterior wall from peeling off, but for the purpose of smoothing out the unevenness of the exterior wall, in order to prepare the substrate (smoothing treatment).

[0052] (Top coat layer formation process) The construction method of the present invention may further include a topcoat layer formation step, in which, after the peeling prevention layer formation step, a topcoat agent is applied to the peeling prevention layer and cured to form a topcoat layer. The topcoat agent used to form the topcoat layer is not particularly limited. Examples include water-based acrylic urethane resin topcoat agents and solvent-based acrylic urethane resin topcoat agents. However, specific urethane compositions can be excluded from the above-mentioned water-based and / or solvent-based acrylic urethane resin topcoat agents. In the topcoat layer formation process, there are no particular limitations on the method of applying the topcoat agent onto the peeling prevention layer. For example, it can be applied using a roller, brush, spray gun, etc. In the topcoat layer formation process, the topcoat agent should be applied on top of the peeling prevention layer. There are no particular restrictions on the temperature conditions for curing the topcoat agent, but for example, it can be cured in air under conditions of 0 to 40°C. The curing time for the topcoat can be, for example, 1 to 24 hours. The thickness of the top coat layer can be, for example, 0.01 to 1.00 mm.

[0053] The construction method for the anti-spraying layer of the present invention, applied to the exterior wall of a building, will be described below with reference to the attached drawings. The present invention is not limited to the attached drawings.

[0054] (Figure 3) Figure 3 is a schematic cross-sectional perspective view showing an example of an exterior wall of a building constructed using the delamination prevention layer construction method of the present invention. In Figure 3, the exterior wall 31 of the building has a primer layer 35 on top of tiles 33 placed on the wall of the building itself, a delamination prevention layer 37 on top of the primer layer 35, and a topcoat layer 39 on top of the delamination prevention layer 37. The delamination prevention layer 37 is a cured product formed from a specific urethane-based composition. A mortar layer may be formed between the tile 33 and the primer layer 35 for surface preparation (smoothing treatment), not for the purpose of preventing the exterior wall from peeling off, but for the purpose of smoothing out the unevenness of the tile 43.

[0055] (Figure 4) Figure 4 is a schematic cross-sectional perspective view showing another example of the exterior wall of a building constructed using the delamination prevention layer construction method of the present invention. In Figure 4, the exterior wall 41 of the building has a primer layer 45 on the wall 43 of the building itself, a delamination prevention layer 47 on the primer layer 45, and a topcoat layer 49 on the delamination prevention layer 47. The delamination prevention layer 47 is a cured product formed from a specific urethane-based composition. If the surface of the wall 43 is uneven, a mortar layer may be formed between the wall 43 and the primer layer 45 for surface preparation (smoothing treatment), not for the purpose of preventing the exterior wall from peeling off, but for the purpose of smoothing out the unevenness of the wall 43.

[0056] Furthermore, according to the present invention, it is possible to provide the urethane composition described in [2] below, and the peeling prevention layer described in [3] below. [2] A urethane prepolymer having an isocyanate group and a filler, The above urethane prepolymer is formed from a polyisocyanate compound having multiple isocyanate groups per molecule and a polyol containing butanediol and polyoxyalkylene polyol, wherein the molar equivalent ratio of the butanediol to the polyoxyalkylene polyol (butanediol:polyoxyalkylene polyol) is 60:40 to 75:25. A urethane-based composition used to prevent the peeling of exterior walls of buildings. The urethane composition described in [2] is the same as the specific urethane composition used in the method for applying the peeling prevention layer of the present invention.

[0057] [3] A peeling prevention layer for the exterior wall of a building, wherein the peeling prevention layer is placed on the exterior wall of the building and is a cured product of the urethane composition described in [2]. The peeling prevention layer described in [3] is the same as the peeling prevention layer formed in the method for applying the peeling prevention layer of the present invention. [Examples]

[0058] The present invention will be described in more detail below based on examples. The materials, quantities, proportions, processing details, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples.

[0059] [Preparation of Urethane Prepolymer 1] 5.68 parts by mass of 1,4-butanediol with a molecular weight of 90 (1,4-BD, OH value 1247 mgKOH / g, manufactured by Mitsubishi Chemical Corporation; the same applies hereafter) and 54.1 parts by mass of polypropylene glycol with a number average molecular weight of 2000 (product name: Sannix PP-2000NS, bifunctional, OH value 56±2 mgKOH / g, manufactured by Sanyo Chemical Industries, Ltd.; the same applies hereafter) were weighed and mixed in a molar equivalent ratio of 1,4-butanediol:the above polypropylene glycol = 70:30, and then IPDI40.21 with a molecular weight of 222 was added to the solution. Parts by mass (product name: IPDI, manufactured by Hyulls; the same applies hereinafter) were added to a liquid mixture such that the molar equivalent ratio (NCO / OH) of isocyanate groups in IPDI to the total number of hydroxyl groups in 1,4-butanediol and polypropylene glycol was 2.00. The liquid mixture was then heated while stirring, and a tin catalyst was added to the total liquid mixture in an amount of 0.01% by mass of the total liquid mixture. The mixture was reacted at 95°C for 2.5 hours to obtain urethane prepolymer 1. Urethane prepolymer 1 includes 1,4-BD with IPDI added, and the above-mentioned polypropylene glycol with IPDI added, and the isocyanate group content of urethane prepolymer 1 was 7.6% by mass of urethane prepolymer 1. 1,4-Butanediol: Urethane prepolymer 1, in which the molar equivalent ratio of the above polypropylene glycol is 70:30, falls under the category of a specific urethane prepolymer.

[0060] [Preparation of Urethane Prepolymer 2] 4.12 parts by mass of 1,4-butanediol, 42.48 parts by mass of polypropylene glycol with a number average molecular weight of 2000, and 15.25 parts by mass of polypropylene triol (product name: Sannix GP-3000NS, trifunctional, weight average molecular weight of 3000, manufactured by Sanyo Chemical Industries, Ltd.) were weighed and mixed in a molar equivalent ratio of 1,4-butanediol:(the above polypropylene glycol + the above polypropylene triol) = 61:39 to obtain a solution. 34.78 parts by mass of IPDI were added to this solution so that the molar equivalent ratio (NCO / OH) of the isocyanate groups of IPDI to the total hydroxyl groups of the above 1,4-butanediol, polypropylene glycol, and polypropylene triol was 2.00 to obtain a liquid mixture. The liquid mixture was then heated while stirring, and a tin catalyst was added to the total liquid mixture in an amount of 0.01% by mass of the total liquid mixture. The mixture was reacted at 95°C for 2.5 hours to obtain urethane prepolymer 2. Urethane prepolymer 2 included 1,4-BD with IPDI added, the above polypropylene glycol with IPDI added, and the above polypropylene triol with IPDI added, and the isocyanate group content of urethane prepolymer 2 was 6.7% by mass. Urethane prepolymer 2, in which the molar equivalent ratio of 1,4-butanediol:(the above polypropylene glycol + the above polypropylene triol) is 61:39, is classified as a specific urethane prepolymer.

[0061] [Preparation of Urethane Prepolymer 3] Urethane prepolymer 3 was obtained by preparing urethane prepolymer 3 in the same manner as described in [Preparation of Urethane Prepolymer 1] above, except that the molar equivalent ratio of 1,4-butanediol to polypropylene glycol was changed to 50:50. The amount of 1,4-butanediol used was 3.02 parts by mass, the amount of polypropylene glycol with a number average molecular weight of 2000 was 67.06 parts by mass, and the amount of IPDI used was 29.91 parts by mass. Urethane prepolymer 3 included 1,4-BD with IPDI added, and the above-mentioned polypropylene glycol (Sannix PP-2000NS) with IPDI added, and the isocyanate group content of urethane prepolymer 3 was 5.6% by mass. 1,4-Butanediol: Urethane prepolymer 3, in which the molar equivalent ratio of the above polypropylene glycol is 50:50, does not fall under the category of a specified urethane prepolymer.

[0062] [Preparation of Urethane Prepolymer 4] Urethane prepolymer 4 was obtained by preparing urethane prepolymer 4 in the same manner as described in [Preparation of Urethane Prepolymer 1] above, except that the molar equivalent ratio of 1,4-butanediol to polypropylene glycol was changed to 80:20. The amount of 1,4-butanediol used was 7.84 parts by mass, the amount of polypropylene glycol with a number average molecular weight of 2000 used was 43.57 parts by mass, and the amount of IPDI used was 48.58 parts by mass. The urethane prepolymer 4 included 1,4-BD with IPDI added, and the above-mentioned polypropylene glycol (Sannix PP-2000NS) with IPDI added, and the isocyanate group content of the urethane prepolymer 4 was 9.2% by mass. 1,4-Butanediol: Urethane prepolymer 4, in which the molar equivalent ratio of the above polypropylene glycol is 80:20, does not fall under the category of a specified urethane prepolymer.

[0063] [Preparation of urethane-based compositions] Each urethane-based composition was prepared by mixing the components shown in Table 2 in the amounts (mass%) shown in the same table.

[0064] [evaluation] [Bending test] The bending test in this invention conforms to the "Confirmation of Reinforcement Effect of Composite Repair Layer (Out-of-Plane Bending) Test (Test Number 04)" for exterior wall composite construction methods, as specified in the "Registered Specifications for Quality Judgment Criteria of Equipment and Construction Methods" (FY2017 edition), supervised by the Housing Management Department of the Urban Renaissance Agency, as the test method. (Preparation of evaluation samples) In accordance with the method specified in JIS R 5201:2015 (Physical Testing Methods for Cement) 1.15 (Preparation of Test Specimens), cement, standard sand, and water were mixed in a ratio of 1:3:0.5, filled into a mold, and then removed the mold the following day. Mortar boards (60 cm long, 10 cm deep, and 3 cm thick) were cured in water for 7 days and in a machine for 28 days. Mortar boards (60 cm long, 10 cm deep, 3 cm thick) were cured indoors for more than a week, then loaded at the center along the longitudinal direction to split them in two (divided into two pieces along the 60 cm center line). The two split pieces were joined together, and a primer, a spalling prevention layer, and a topcoat were applied to the surface that had been in contact with the formwork, in the order shown in Table 1 below, under conditions of 23°C and 50% relative humidity. After curing, evaluation samples for bending tests were prepared. When preparing evaluation samples for bending tests, the primer used was the product name NN Primer, manufactured by Sika Japan Co., Ltd. Furthermore, the urethane compositions prepared in the above-mentioned [Preparation of Urethane Compositions] section were used for the peeling prevention layer. In each example and comparative example, the same urethane composition was used to apply the first, second, and third layers of the peeling prevention layer. As the top coat used, we used product name NN Top, manufactured by Sika Japan Co., Ltd. The same top coat was used in each example and comparative example. Table 1 below shows the amount of peeling prevention layer and other coatings used when preparing evaluation samples for bending tests, as well as the time interval between processes.

[0065] [Table 1]

[0066] (Bending test) Using the three evaluation samples prepared as described above, the following bending tests were performed under 23°C conditions to measure the bending strength of the cured urethane composition, and the average bending strength of the three evaluation samples was calculated. The results are shown in Table 2.

[0067] The bending test described above will be explained below using the attached drawings. (Figure 5) Figure 5 is a schematic diagram illustrating the apparatus used for the bending test in this specification. In Figure 5, the apparatus 51 used for the bending test includes a support column 61 and a load device 65. For the bending test, one evaluation sample 53 prepared as described above is used. The evaluation sample 53 has two mortar boards 55 obtained by breaking one mortar board by pressing it, and a film 59 made of hardened urethane composition, with the two mortar boards 55 in contact with each other at the fracture surface 57. The film 59 corresponds to the peeling prevention layer. Although each of the two mortar boards 55 has a fracture surface 57, the two fracture surfaces 57 are shown as a single unit in Figure 5. In the apparatus 51, the evaluation sample 53 is placed on the support column 61 such that the membrane 59 is in contact with the tip of the support column 61. The evaluation sample 53 is held horizontal by the support column 61. The distances 71 and 79 from the end of the evaluation sample 53 to the centerlines of the support column 61 are 75 mm, respectively. The distance between the centerlines of the two support columns 61 is 450 mm.

[0068] A load-bearing device 65 is placed on two mortar boards 55. The load-bearing device 65 has load-bearing sections 63 at each end. The distance from the fracture surface 57 to each of the two load-bearing sections 63 is equal. The distances 73 and 77 from the center line of the support column 61 to the center line of the load-bearing section 63, and the distance 75 between the center lines of the two load-bearing sections 63 are all 150 mm.

[0069] As described above, a load device 65 is placed on the evaluation sample 53, and a load 67 is applied vertically from the load device 65 toward the evaluation sample 53.

[0070] (Figure 6) Figure 6 is a schematic diagram illustrating the changes in the evaluation sample before and after applying a load during a bending test. Figure 6(a) is a schematic diagram illustrating the evaluation sample 81 before a load is applied in a bending test. In Figure 6(a), the evaluation sample 81 has two mortar boards 83 and 84 and a film 87, and there is no gap between the fracture surfaces 85 of the two mortar boards 83 and 84. Figure 6(b) is a schematic diagram illustrating the evaluation sample 91 after a load has been applied in a bending test. In Figure 6(b), the evaluation sample 91 consists of two mortar boards 93 and 94 and two membranes 95 and 96, with the two mortar boards 93 and 94 being simulated to bend, and the membranes 95 and 96 being cut. In this specification, the bending strength was measured as the load applied when the membrane 87 in Figure 6(a) completely fractured during the bending test.

[0071] (Evaluation criteria for the strength of the peeling prevention layer) In this invention, if the average bending strength of the evaluation samples was 490 N or higher, the strength of the delamination prevention layer was evaluated as excellent. The greater the average value above 490 N, the better the strength of the delamination prevention layer. On the other hand, if the above average value was less than 490N, it was evaluated that the strength of the peeling prevention layer was insufficient.

[0072] (mechanical properties) In accordance with JIS A6021-2000, each urethane composition prepared in the above [Preparation of Urethane Composition] was cured for 7 days under conditions of 23°C and 50% relative humidity to prepare test specimens. The tensile strength, elongation at fracture, elastic modulus at 5% and 10% elongation, and tear strength of the test specimens obtained as described above were measured in accordance with JIS A6021-2000. The results are shown in Table 2. Note that if the elastic modulus at 5% elongation (5% modulus) could not be measured, it was indicated as "unmeasurable." The same applies to the elastic modulus at 10% elongation (10% modulus).

[0073] (Elongation rate at fracture) In this invention, when the elongation rate at fracture of the test specimen obtained as described above was 200-350%, the elongation of the delamination prevention layer was evaluated as excellent. However, from the viewpoint of balancing the strength and elongation of the delamination prevention layer, an elongation rate at fracture of 200-310% is also acceptable. On the other hand, if the elongation rate at the time of fracture was as described above, it was evaluated that the elongation of the delamination prevention layer was insufficient. In addition, in the measurement of elongation at fracture described above, if the test specimen fractured with an elongation rate of 50% or less, it was indicated as "unmeasurable".

[0074] (Hardness (D)) The Shore D hardness of cylindrical test specimens (20 mm in diameter, 5 mm in thickness) obtained by curing each urethane composition prepared in the above [Preparation of Urethane Compositions] section at 23°C and 50% relative humidity for 7 days was measured according to DIN 53505. The results are shown in the "Hardness (D)" column of Table 2.

[0075] [Table 2]

[0076] The details of each component shown in Table 2 above are as follows: (Urethane prepolymer) • Urethane prepolymers 1-4: Urethane prepolymers 1-4 prepared as described above.

[0077] • Pigment: Titanium oxide paste, manufactured by Dainichi Seika Co., Ltd.

[0078] • Filler 1: Calcium carbonate. Product name P-30, Toyo Fine Chemical Co., Ltd. • Filler 2: Surface-treated calcium carbonate. Product name: CCR-B, manufactured by Shiraishi Kogyo Co., Ltd.

[0079] • Eversorb S02: A blend of UV absorbers, hindered amine light stabilizers (HALS), and antioxidants. Manufactured by Everlight Chemical. • Antifoaming agent: Floren AC-2230EF, manufactured by Kyoeisha Chemical Co., Ltd. • Organic solvent: C9 and C10 alkylcyclohexane isomer compound (Swaclean 150), manufactured by Maruzen Petrochemical Co., Ltd. • Dispersant: Polyether ester-type polycarboxylic acid. Dispalon 3350, manufactured by Kusumoto Chemical Co., Ltd. • Latent curing agent: A urethane-crosslinked bis-oxazolidine compound (structure shown below). Hydrolysis yields a reactive amine and a crosslinking agent having a hydroxyl group. [ka] The method for preparing the above-mentioned urethane-crosslinked bis-oxazolidine compound is as follows. 435.0 g of diethanolamine was placed in a reaction vessel equipped with a stirrer, thermometer, nitrogen-sealed tube, and heating / cooling device, followed by the addition of 183.3 g of toluene. While stirring, 328.3 g of isobutyraldehyde was added, and the dehydration reaction was continued at 110-150°C for 3 hours, after which 74.5 g of water was removed using an ester tube. The mixture was then reduced in pressure to remove excess isobutyraldehyde and toluene, yielding a hydroxyl-containing oxazolidine compound. 341.0 g of hexamethylene diisocyanate was added to 658.9 g of this hydroxyl-containing oxazolidine compound, and the mixture was heated at 80°C for 8 hours. The urethane reaction was terminated when the measured isocyanate group content, determined by titration, fell to 0.0% by mass or less. The resulting reaction product was a translucent liquid at room temperature. The resulting reaction product is a urethane-crosslinked bis-oxazolidine compound having the structure described above.

[0080] The results in Table 2 show that the cured products of the urethane compositions in Comparative Examples 1 and 2, which contained urethane prepolymers other than the specified urethane prepolymer, were insufficient in at least one of the following: strength as a delamination prevention layer and elongation at fracture. On the other hand, the cured product of the specific urethane-based composition exhibited excellent strength and elongation at fracture. Therefore, it is believed that the resulting layer can prevent the peeling of tiles and other materials without the need for the conventional process of applying fibrous materials. Based on the above results, it is considered that, according to the construction method of the present invention, by applying a specific urethane-based composition to the exterior wall of a building and allowing it to harden, the work process (for example, the process of applying a resin layer having fibers or reinforcing fabric, or the process of applying a mortar layer to a concrete structure outside of the tiles) can be simplified compared to conventional methods, and a spalling prevention layer having sufficient strength and elongation rate at fracture can be formed (constructed). Furthermore, the construction process that can be simplified in this invention does not include the process of forming a mortar layer inside the concrete structure (between the concrete structure and the tiles) relative to the concrete structure. Furthermore, in the present invention, the simplified work process does not include the step of forming a mortar layer for surface preparation (smoothing treatment) on the uneven exterior wall of a building, such as a tiled exterior wall, before forming the primer layer on the uneven exterior wall, not for the purpose of preventing the exterior wall from peeling off, but for the purpose of smoothing the unevenness of the exterior wall. [Explanation of Symbols]

[0081] 1 Building 2, 21, 31, 41 Exterior walls 3, 43 Wall 4, 6 Mortar layer 5, 7, 23, 33 tiles 8. Damaged wall 25, 35, 45 Primer layer 27 Mortar layer 29, 37, 47 Anti-peeling layer 39, 49 Top coat layer 51 Equipment 53, 81, 91 Evaluation Samples 55, 83, 84, 93, 94 Mortar board 57, 85, fracture surface 59, 87, 95, 96 membrane (peeling prevention layer) 61 Pillar 65 Loading device 63 Load-bearing section 67 Load 71, 73, 75, 77, 79 distance

Claims

[Claim 1] The process includes a step of forming a peeling prevention layer by applying a urethane-based composition to the exterior wall of a building and curing it to form a peeling prevention layer. The urethane-based composition is It contains a urethane prepolymer having an isocyanate group and a filler, A method for applying a peeling prevention layer, wherein the urethane prepolymer is formed from a polyisocyanate compound having multiple isocyanate groups per molecule and a polyol containing butanediol and polyoxyalkylene polyol, and the molar equivalent ratio of the butanediol to the polyoxyalkylene polyol (butanediol:polyoxyalkylene polyol) is 60:40 to 75:25.

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