Tile fall prevention method

Abstract

This invention provides a tile fall prevention method that offers excellent design aesthetics while also achieving efficient repairs and long-lasting repair effects. [Solution] The tiled wall surface contains a urethane prepolymer composed of acrylic polyol and aliphatic polyisocyanate, with a viscosity of 150-2,000 mPa·s at 23°C and 20 rpm measured with an E-type viscometer, and a tensile strength of 20 N / mm² after curing. 2 The above describes a tile fall prevention method comprising a first step of coating with a one-component moisture-curing urethane resin composition having an elongation of 50% or more at break, and a second step of injecting an epoxy resin composition into the back surface of the tile.

Description

[Technical Field]

[0001] This invention relates to a method for preventing tiles from falling. More specifically, it relates to a method for preventing tiles from falling from tiled walls, such as exterior and interior walls, and which offers excellent aesthetic appeal. [Background technology]

[0002] In tiled walls, such as the exterior and interior walls of concrete structures, tiles are bonded to the concrete or to each other using mortar or other adhesives. However, over time, delamination from the wall surface can occur, causing the tiles to lift. These lifted tiles, due to their mass, can detach from the wall and fall, potentially leading to accidents, which is a significant problem.

[0003] To address these problems, Patent Document 1 discloses an anchor pinning epoxy resin injection method that uses a special jig and injects epoxy resin for fixing, while Patent Document 2 discloses a method that, in addition to anchor pins, consists of a specific primer, a specific transparent reinforcing layer, and a transparent protective layer for protecting the reinforcing layer.

[0004] However, the method disclosed in Patent Document 1 has the problem of being inefficient for repairs because it requires the use of special jigs, which complicates the work. Furthermore, when tiles begin to peel, peeling and cracking may also occur in the grout between the tiles, and the epoxy resin injected to repair the peeling tiles may leak out from there. The leaked epoxy resin contaminates the grout and tiles, negatively affecting the aesthetic appearance.

[0005] Furthermore, the construction method disclosed in Patent Document 2 basically relies on anchor bolts for strength, and then forms three transparent layers on top of them: a primer, a reinforcing layer, and a protective layer. However, since the anchor bolts remain even after repair, there are issues with aesthetics. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 5127945 [Patent Document 2] Japanese Patent Publication No. 2023-98459 [Patent Document 3] WO2024 / 194971 [Patent Document 4] Patent No. 7546990 [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide a tile fall prevention method that is aesthetically pleasing, efficient in repair, and maintains its repair effect over a long period of time. [Means for solving the problem]

[0008] The objective of this invention is to provide a tiled wall surface containing a urethane prepolymer composed of an acrylic polyol and an aliphatic polyisocyanate, with a viscosity of 150 to 2,000 mPa·s at 23°C and 20 rpm measured using an E-type viscometer, and a tensile strength of 20 N / mm² after curing. 2 This is achieved by a tile fall prevention method consisting of a first step of coating with a one-component moisture-curing urethane resin composition having an elongation of 50% or more at break, and a second step of injecting an epoxy resin composition into the back surface of the tile. [Effects of the Invention]

[0009] The tile fall prevention method according to the present invention provides excellent effects in that, when a tiled wall surface experiences delamination from the concrete or other structural body, or when this delamination progresses to a state called bulging, specifically when multiple tiles have delaminated and multiple tiles appear to bulge outwards, the entire tile-mortar surface is coated with a one-component moisture-curing urethane resin composition that exhibits high tensile strength and desired elongation in its cured form. This coating reinforces and protects the surface, preventing the epoxy resin injected into the delamination area from flowing onto the tile surface through cracks in the mortar (joints). Furthermore, even if epoxy resin flows out during the construction phase, the epoxy resin adhering to the polyurethane resin can be easily removed, thus preventing direct contamination of the tiles. Moreover, even if tile delamination occurs at the repair site in the future, the presence of the urethane resin layer with specific physical properties prevents the tiles from falling.

[0010] Furthermore, by using an epoxy resin with a viscosity of 1,000 to 40,000 mPa·s at 23°C and 10 rpm as measured by a B-type viscometer, injection into areas where tiles have been removed becomes easier, improving work efficiency. Additionally, when the tiles are pressed down, the outflow of epoxy resin from the injection port becomes easier to control, thus reducing contamination of the hardened urethane resin coating.

[0011] Furthermore, by using anchor pins that can press multiple tiles against the concrete structure after the first or second step in order to suppress bulging of the tiles during epoxy resin curing, it is possible to improve the aesthetic appearance of the tiled exterior wall surface and to suppress tile peeling over the long term after construction. [Modes for carrying out the invention]

[0012] The present invention provides a tile fall prevention method for the exterior wall surface, which contains a urethane prepolymer composed of acrylic polyol and aliphatic polyisocyanate. The viscosity measured using an E-type viscometer at 23°C and 20 rpm is 150 to 2,000 mPa·s, and the tensile strength after curing is 20 N / mm². 2 The above describes a method consisting of a first step of coating with a one-component moisture-curing urethane resin composition having an elongation of 50% or more at break, and a second step of injecting epoxy resin into the back surface of the tiles from the tile joints.

[0013] Prior to applying the one-component moisture-curing urethane resin composition in the first step, a primer is preferably applied to the tiles first. As the primer, an acrylic resin-containing primer is used, and the amount applied is such that the dry film thickness is 20 μm or more, preferably 40 to 60 μm. If the film thickness is less than this, sufficient adhesion strength cannot be obtained, and the tiles may fall off when they peel off. On the other hand, if the film thickness is greater, a drip pattern will occur, impairing the design of the tiles.

[0014] The one-component moisture-curable urethane resin composition contains a urethane prepolymer consisting of an acrylic polyol and an aliphatic polyisocyanate, has a viscosity of 150 to 2,000 mPa·s, preferably 150 to 1,500 mPa·s, at 23°C and 20 rpm using an E-type viscometer, and has a tensile strength of 20 N / mm² after curing. 2In a moisture-curable urethane resin composition having an elongation at break of 50% or more, preferably 100% or more, for example, a moisture-curable resin composition comprising a urethane prepolymer and an oxazolidine, one of which can be used is a one-component moisture-curable urethane resin composition in which the urethane prepolymer is synthesized from a polyol consisting of a polycarbonate polyol and an acrylic polyol and a polyisocyanate (Patent Document 3), a urethane prepolymer synthesized from a polyol consisting of 20 to 80 parts by mass of acrylic polyol, 0 to 80 parts by mass of polycarbonate polyol, 0 to 80 parts by mass of polyester polyol, and 0 to 20 parts by mass of other polyols in 100 parts by mass of polyol and an aliphatic isocyanate, a one-component moisture-curable resin composition comprising a latent curing agent and a hydrolyzable silyl group-containing polymer, etc. A one-component moisture-curable urethane resin can be produced, for example, as follows.

[0015] Examples of polyols include acrylic polyols and those having 2 to 10 hydroxyl groups per molecule, such as polycarbonate polyols, polyether polyols, and polyester polyols. Preferably, a polyol consisting of at least one polyol such as polycarbonate polyol, polytetramethylene polyol, or polyester polyol, and an acrylic polyol is used.

[0016] Examples of the polycarbonate polyol include those obtained by reacting at least one aliphatic polyhydric alcohol such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, cyclohexanedimethanol, etc. with a dialkylene carbonate or a dialkyl carbonate such as diethylene carbonate, dimethyl carbonate, diethyl carbonate, etc. Here, the number of carbon atoms of the alkylene group or dialkyl group is 2 to 10. As such a polycarbonate polyol, those having a number average molecular weight Mn of 500 to 3,000 are preferably used, and commercially available products such as UBE products ETERNACOLL UH-50, UH-100, UH-200, UH-300, PH-50, PH-100, PH-200, PH-300, UC-100, UM-90U, Toray products Nipporan 981, 980R, 982R, 965, 963, 964, 968, etc. can be used as they are.

[0017] As the polyether polyol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. are suitable, but polytetramethylene glycol is more suitable in terms of weather resistance and mechanical properties of the polyurethane. As the number average molecular weight Mn, those of 500 to 2,000 are preferably used.

[0018] As the polyester polyol, for example, a reaction product of a compound having two or more hydroxyl groups and a polybasic carboxylic acid can be used.

[0019] Examples of compounds having two or more carboxyl groups include ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, hexanediol, neopentyl glycol, hexamethylene glycol, glycerin, trimethylolpropane, bisphenol A or bisphenol F, and alkylene oxide adducts thereof. Among these, 2,4-diethyl-1,5-pentanediol or 2-ethyl-2-butyl-1,3-propanediol is preferably used from the viewpoint of weather resistance.

[0020] Examples of polybasic carboxylic acids include adipic acid, glutaric acid, pimelic acid, suberic acid, dimer acid, sebacic acid, undecanedicarboxylic acid, hexahydroterephthalic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, etc. Among these, phthalic acid is preferably used from the viewpoints of better adhesion to the fabric and film strength.

[0021] The number average molecular weight Mn of the polyester polyol is preferably in the range of 500 to 50,000 from the viewpoint of obtaining better adhesion and mechanical properties. For example, commercially available products such as the DIC product Polyrite series, the Tosoh product Nipolan series, and the ADEKA product Adeka New Ace series, which are liquid or solid at room temperature, can be used as they are.

[0022] Examples of acrylic polyols include homopolymers or copolymers of (meth)acrylic monomers having a hydroxyl group, or those having a predetermined hydroxyl value obtained by copolymerizing a (meth)acrylic monomer having a hydroxyl group with another monomer having a polymerizable unsaturated bond. The number of hydroxyl groups in the acrylic polyol used in the one-component moisture-curable urethane resin is preferably 2 to 10 on average per molecule.

[0023] Examples of (meth)acrylic monomers having a hydroxyl group include hydroxyalkyl (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, as well as triol (meth)acrylic acid monoesters such as glycerin (meth)acrylic acid monoester and trimethylolpropane (meth)acrylic acid monoester. These may be used individually or in combination of two or more.

[0024] Other monomers having polymerizable unsaturated bonds can also be used in combination, such as alkyl (meth)acrylates like methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; alkoxyalkyl (meth)acrylates like 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and 3-methoxybutyl (meth)acrylate; unsaturated carboxylic acids like (meth)acrylic acid, maleic acid, and itaconic acid; unsaturated amides like (meth)acrylamide and N-methylol(meth)acrylamide; styrene, vinyltoluene, vinyl acetate, and acrylonitrile. These may be used individually or in combination of two or more. Among these, (meth)acrylic acid esters such as alkyl (meth)acrylate and / or alkoxyalkyl (meth)acrylate are preferably used from the viewpoint of weather resistance.

[0025] As a urethane prepolymer, it is essential to primarily use aliphatic isocyanates from the viewpoint of weather resistance, and specifically, aliphatic or alicyclic polyisocyanates are used. Examples of such polyisocyanates include hydrogenated diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated XDI, tetramethylxylene diisocyanate, 1,8-diisocyanatomethyloctane, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, bicycloheptane triisocyanate and their modified forms (biuret, allophanate, isocyanurate modified forms), and derivatives such as trimethylolpropane adducts. From the viewpoint of weather resistance and strength of the coating film, isophorone diisocyanate and its derivatives are preferably used.

[0026] In the synthesis of urethane prepolymers, hydroxyl group-containing oxazolidines can also be used in a proportion of 0.5 equivalents or less relative to the remaining isocyanate groups. As hydroxyl group-containing oxazolidines, hydroxyalkyl oxazolidines such as 2-isopropyl-3-(2-hydroxyethyl)oxazolidine, 2-(1-methylbutyl)-3-(2-hydroxyethyl)oxazolidine, N-hydroxyethyl-2-phenyloxazolidine, and 2-(p-methoxyphenyl)-3-(2-hydroxyethyl)oxazolidine are used, with 2-isopropyl-3-(2-hydroxyethyl)oxazolidine being preferred from the viewpoint of storage stability, curability, and physical properties after curing. These hydroxyalkyl oxazolidines are synthesized from the corresponding aldehyde or ketone and a hydroxyalkylamine by known methods.

[0027] The hydroxyl value of the acrylic polyol is preferably 40 to 150 mg KOH / g, more preferably 60 to 150 mg KOH / g. Below this value, the hardness of the coating film tends to decrease, and its stain resistance decreases. Above this value, the coating film tends to become too hard and brittle.

[0028] Furthermore, the Tg of the acrylic polyol is preferably -70 to 120°C or lower. Above 120°C, the impact resistance of the coating film decreases. Even if the Tg of the acrylic polyol is low, the mechanical properties can be controlled by increasing the number of hydroxyl groups, so it can be appropriately selected according to the properties of the polyol used simultaneously.

[0029] Acrylic polyols can be used as is, for example, commercially available products such as Toa Gosei's UH-2000 (Tg: -56℃, hydroxyl value: 20), UH-2401 (Tg: -50℃, hydroxyl value: 120), UH-2170 (Tg: 60℃, hydroxyl value: 88), Asia Kogyo's Excelol series, and DIC's Acrydec series A-801-P (Tg: 50℃, hydroxyl value: 47, acid value 1-4), WBU1218 (Tg: 100℃, hydroxyl value: 55, acid value 1-3).

[0030] Preferably, the above components consist of 20 to 80 parts by mass of acrylic polyol, 0 to 80 parts by mass of polycarbonate polyol, 0 to 80 parts by mass of polytetramethylene glycol, and 0 to 80 parts by mass of polyester polyol per 100 parts by mass of polyol. Other polyols may also be used in the range of 0 to 20 parts by mass to adjust viscosity and mechanical properties.

[0031] As a latent curing agent incorporated into the urethane prepolymer, a hydroxyl group-containing oxazolidine compound is used. Examples of hydroxyl group-containing oxazolidine compounds incorporated into the urethane prepolymer include the oxazolidine compounds exemplified in the urethane prepolymer. Here, an oxazolidine compound obtained by pre-reacting a hydroxyl group-containing oxazolidine compound with a polyisocyanate, preferably a compound obtained by reacting the hydroxyl group-containing oxazolidine compound (OH) with the isocyanate group (NCO) in a ratio of NCO / OH = 1 / 0.1 to 1 / 1, can also be incorporated. Here, as the polyisocyanate, an aliphatic polyisocyanate is preferably used.

[0032] The equivalent ratio of isocyanate groups (NCO) to oxazolidine groups (OX) in the urethane resin composition is preferably NCO / OX = 1.0 to 3.0. If the NCO / OX equivalent ratio is less than 1.0, the oxazolidine will be in excess of the isocyanate groups, resulting in unreacted amino groups remaining during curing, which will worsen weather resistance. On the other hand, if the NCO / OX equivalent ratio exceeds 3.0, the amount of oxazolidine groups, which are the curing agent, will be significantly less than the amount of isocyanate groups, leading to poor curing performance.

[0033] The above essential components are mixed into the urethane prepolymer using various dispersers such as dispersers, planetary mixers, rolls, and bead mills to prepare a one-component moisture-curable polyurethane composition.

[0034] These one-component moisture-curing polyurethane resins offer excellent storage stability as a one-component type, and their moisture-curing properties mean they harden and form a cured product due to humidity in the atmosphere. In addition, the cured product has high weather resistance and impact resistance, does not impair the aesthetic appearance of the tiles, and has high coating strength, preventing tiles from falling off when they detach from concrete or other structures.

[0035] The application of the one-component moisture-curing urethane resin composition is carried out in such an amount that the dry film thickness is 200 μm or more, preferably 300 to 400 μm. If the film thickness is less than this, the coating may tear when the tile bulges, causing it to fall off. On the other hand, if the film thickness is greater than this, the texture of the tile will be impaired, negatively affecting its aesthetic appeal.

[0036] In the second step, a hole of about 2 to 4 mm in diameter is made in a portion of the cured urethane resin composition, preferably in the mortar (grout) portion filling the gaps between the tiles, and the epoxy resin composition is injected through this hole into the detached tile portion and / or joint crack portion, and curing is performed at room temperature.

[0037] The epoxy resin composition used is one in which an epoxy resin such as a bisphenol A type epoxy resin is blended with various compounding agents such as a curing agent, and the viscosity at 23°C and 10 rpm measured using a B-type viscometer is preferably 1,000 to 40,000 mPa·s, more preferably 1,000 to 18,000 mPa·s, and particularly preferably 1,000 to 8,000 mPa·s, and the thixotropic index, which is the ratio of the values ​​at 2 rpm and 20 rpm measured using a B-type viscometer (2 rpm / 20 rpm), is 1.5 to 6.0, preferably 3.0 to 5.0, and more preferably 1.5 to 3.5. By using such an epoxy resin, it is easier to inject into areas where tiles have peeled off, and when the tiles are pressed down, it is easier to control the outflow of epoxy resin from the injection port, thus reducing contamination of the cured urethane resin coating.

[0038] Here, since bisphenol A type epoxy resin and bisphenol F type epoxy resin have relatively high viscosity, their viscosity is preferably adjusted with a monofunctional epoxy compound called a reactive diluent, or a glucidyl ether of an aliphatic polyhydric alcohol. As a reactive diluent, commercially available products such as ADEKA products ED-502, ED-509E, ED-529, ED-503, ED-506, ED-523, and ED-505 can be used. If the viscosity is below this level, the injected epoxy resin may flow out due to its low viscosity. On the other hand, if the viscosity exceeds this level, not only will injection become difficult, but the epoxy resin will also have difficulty penetrating into the gaps in the delaminated area. Furthermore, if the thixotropic index is below this level, the epoxy resin is easy to inject and penetrates into gaps easily, but it may flow out and contaminate joints, tiles, etc. On the other hand, if the thixotropic index exceeds this level, it will have difficulty penetrating into gaps, and sufficient strength may not be obtained.

[0039] Preferably, a curing agent for epoxy resins is one that allows the epoxy resin to cure at room temperature. Specifically, two-component curing agents include aliphatic polyamines, polyamidoamines, and mercaptans, while one-component curing agents include ketimines. These are used individually or in combination, taking into consideration curability, curing time, and the strength of the cured product.

[0040] From the perspective of ensuring the tile fall prevention effect is sustained, the tensile strength after epoxy resin curing should be 25 N / mm². 2 The following is required: Tensile strength of 25 N / mm². 2 Below this level, it becomes difficult to maintain sufficient tile fall prevention effectiveness under outdoor conditions such as prolonged temperature and humidity changes, wind and rain, and earthquakes.

[0041] Preferably, a fluorescent substance is added to the epoxy resin composition in a proportion of 0.001 to 1.0% by mass, preferably 0.01 to 0.1% by mass, so that any excess epoxy resin can be detected with a black light or the like. The fluorescent color is not particularly limited, but for example, blue or green can be used.

[0042] Furthermore, from the viewpoint of imparting flexibility to the epoxy resin, a flexibility component is preferably added. As the flexibility component, a resin having hydrolyzable alkoxysilyl groups at the ends or side chains of polymers with molecular weights ranging from several thousand to tens of thousands is used, known as core-shell type rubber particles or modified silicone. As core-shell type rubber particles, commercially available products such as Kaneka's Kaneace MX series and Mitsubishi Chemical's Metabren are used. Adding these core-shell type rubber particles increases the viscosity of the epoxy resin, so it is preferable to add them at about 10% by mass relative to the epoxy resin (10 parts by mass per 100 parts by mass of epoxy resin). As modified silicones, Kaneka's MS Polymer and Cyryl are examples, but those with a viscosity of 5,000 mP·s or less are particularly preferred. Although epoxy resin has high adhesive strength, it is also brittle, and when materials with different coefficients of thermal expansion are bonded together, repeated temperature differences can cause distortion at the bonding surface, leading to delamination. However, by adding such a flexibility component, this situation can be avoided.

[0043] In the above process, after the first or second step and before the epoxy resin composition hardens, preferably after the first step, anchor pins capable of pressing at least two tiles into the structure are inserted. The anchor pins are press-fitted into anchor holes drilled continuously in the urethane resin layer, tiles or mortar, and the structure.

[0044] Anchor pins are typically those with a curved resin head and a screw made of iron, stainless steel, or aluminum in the center. The head of such a pin contacts the tile surface of the exterior wall tile only over the required area, fixing and holding the exterior wall tile in place against the building structure.

[0045] Furthermore, an elastic body can be used in the intermediate portion between the anchor pin head and the foot, which is thicker than the shaft diameter of the foot, shorter than the major axis of the head, and taller than the height of the curved head. When the anchor pin is pressed into the anchor hole, this elastic body deforms and is crushed, thereby pressing the loose portion of the exterior wall tile to be repaired against the building structure.

[0046] After the epoxy resin has cured, the anchor pins are removed, and the screw holes are either filled with urethane resin or filled with mortar before applying urethane resin, so that the entire exterior wall surface is coated with urethane. [Examples]

[0047] Next, the present invention will be described with reference to examples.

[0048] Example 1 An epoxy resin composition consisting of 10 parts by mass of high-viscosity epoxy resin (ADEKA product EP4100), 90 parts by mass of low-viscosity epoxy resin (ADEKA product EP-4530), 40 parts by mass of curing agent (ADEKA product EH-2300), 0.14 parts by mass of fluorescent substance (BASF product Tinopal OB), and 2.8 parts by mass of thixotropic agent (Tokuyama product Reolosil MT-10) was used to evaluate fluidity, construction performance, and tensile strength. The viscosity at 23°C and 10 rpm measured with a B-type viscometer was 1,660 mPa·s, and the thixotropic index (ratio of values ​​at 2°C and 20 rpm (2 rpm / 20 rpm)) was 1.74. Fluidity evaluation, construction evaluation, and tensile strength measurements were performed using this composition. Flowability: A glass capillary with an inner diameter of 270 μm is bonded to a 1 mm thick epoxy resin at 23°C. The capillary was immersed vertically in the material, and the distance (cm) the capillary tip traveled after 1 minute was measured. Construction evaluation: The resin injected into the gap between the structure and the tiles spread quickly to the peeling surface, ○ indicates that it does not spill out from here, and ○ indicates that it spills out from the opening, etc. △, If resin injection is difficult, or if it does not spread to the peeled surface after injection. The case is evaluated as ×. Tensile strength: Complies with JIS K6301

[0049] Example 2 In Example 1, the epoxy resin composition used was modified to contain 20 parts by mass of high-viscosity epoxy resin (EP4100), 80 parts by mass of low-viscosity epoxy resin (EP-4530), and 3.5 parts by mass of thixotropic agent (Reolosil MT-10), resulting in a viscosity of 4,060 mPa·s and a thixotropic index of 2.54.

[0050] Example 3 In Example 1, the epoxy resin composition used was modified to contain 50 parts by mass of high-viscosity epoxy resin (EP4100), 50 parts by mass of low-viscosity epoxy resin (EP-4530), and 4.5 parts by mass of thixotropic agent (Reolosil MT-10), resulting in a viscosity of 7,100 mPa·s and a thixotropic index of 3.07.

[0051] Example 4 In Example 3, the epoxy resin composition used was one to which 20 parts by mass of modified silicone (Kaneka product Cyryl SAT115; a polyether containing two hydrolyzable silyl groups) and 0.2 parts by mass of curing catalyst (Nitto Chemical product Neostan U-220H) were further added, resulting in a viscosity of 5,100 mPa·s and a thixotropic index of 3.09.

[0052] Example 5 In Example 1, the epoxy resin composition was modified by not using a high-viscosity epoxy resin. Instead, the amount of low-viscosity epoxy resin (EP-4530) was changed to 90 parts by mass, the amount of curing agent (EH-2300) to 41 parts by mass, and the amount of thixotropic agent (Reolosil MT-10) to 0.5 parts by mass. In addition, 10 parts by mass of diluent (ADEKA product ED503) was used, resulting in a viscosity of 800 mPa·s and a thixotropic index of 1.35.

[0053] Example 6 In Example 1, the epoxy resin composition used was modified to contain 50 parts by mass of high-viscosity epoxy resin (EP4100), 50 parts by mass of chelate-modified epoxy resin (EP-49-10P), and 5.0 parts by mass of thixotropic agent (Reolosil MT-10), resulting in a viscosity of 42,000 mPa·s and a thixotropic index of 5.05.

[0054] The results obtained in each of the above Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 1. Table 1 Evaluation items Actual 1 Actual 2 Actual 3 Actual 4 Actual 5 Actual 6 Fluidity (cm) 7.3 5.9 4.9 5.5 8.0 1.5 Construction evaluation ○ ○ ○ ○ △ △ Breaking strength (N / mm 2 ) 30 38 40 28 20 42

[0055] Example 7 A one-component moisture-curable urethane resin composition (KF Chemical product Ochinite; viscosity 1,000 mPa·s) containing a urethane prepolymer composed of an acrylic polyol and an aliphatic polyisocyanate was used to measure the tensile strength and elongation at break of the cured urethane resin product, and to evaluate its workability. Tensile strength, elongation at break: Complies with JIS K6301 A one-component moisture-curing urethane resin composition is applied to the release paper to a thickness of 2 mm. The Dan was applied and cured and dried at 23°C for 7 days to create the Dan. Measurement using Bell No. 3 test specimen Workability: Apply a one-component moisture-curing urethane resin composition onto a 600mm x 900mm slate board. When applying a coating with a film thickness of 300 μm, we will investigate the number of coats required to prevent dripping. Applications are evaluated as follows: ○ if applied 2 times or less, × if applied 3 times or more.

[0056] Next, in accordance with JIS A 5371-2010, the formation of the urethane resin layer on the tile surface attached to the concrete body was carried out as follows.

[0057] A hole was drilled in the center of a 300 mm × 300 mm × 60 mm ordinary concrete flat plate with a core cutter having a diameter of 100 mm, and the surface leaving 5 mm was roughened with a disk sander (#150 sandpaper). On the treated surface of this concrete, tile adhesive mortar was applied to a thickness of 4 to 5 mm, and a 50-byobu tile with a size of 9.5 mm × 4.5 mm × 5.0 mm and a weight of 60 g was pasted thereon, followed by curing at 23°C for 7 days. Further, joint mortar was filled between the tiles and cured at 23°C for 3 days.

[0058] On the constructed tiles, a primer containing an acrylic resin (KF Chemical product KF Super Ochinite C undercoat one) was applied at 150 g / m 2 and cured at 23°C and 50% RH for 24 hours. Next, the first protective layer (the company's product KF Super Ochinite C) was applied at 250 g / m 2 and cured at 23°C and 50% RH for 24 hours, and the second protective layer was applied at 250 g / m 2 and cured at 23°C and 50% RH for 14 days for hardening.

[0059] The test specimens were tested in accordance with the Japan Society of Civil Engineers Standard JSCE K-533 "Punching Test Method for Surface Coating Materials Applied to Prevent Spalling of Concrete Pieces". The testing machine used was an autograph AG-Xplus manufactured by Shimadzu Science Corporation. In a room at 23°C, the remaining part of the test specimen core was destroyed at a low speed (1 mm / min), and then a forced displacement (5 mm / min) was applied to the surface coating material, and the load and displacement were continuously recorded. The maximum load at a displacement of 10 mm or more and the displacement at the time of showing the maximum load were measured. The punching strength is preferably 200 N or more, and 170 N or more can be evaluated as good.

[0060] Example 8 In Example 7, KF Chemical product KF20 with a viscosity of 300 mPa·s was used as the one-component moisture-curing urethane resin composition.

[0061] Comparative Example 1 (1) In a 500 ml separable flask equipped with a stirring blade, 40.0 g of polytetramethylene glycol (Mitsubishi Chemical product PTMG2000, hydroxyl value 56 mg KOH / g), 40.0 g of polypropylene glycol (bifunctional, hydroxyl value 56 mg KOH / g), 20.0 g of acrylic polyol (Toagosei product ARUFON UH-2041, hydroxyl value 120 mg KOH / g), and 7.0 g of diisononyl adipate (DINA) were placed and dried under reduced pressure at 100 °C for 4 hours. After cooling, 2.1 g of hydroxyethyl acrylate, 50.8 g of isophorone diisocyanate, 90 g of naphthenic solvent (Maruzen Petrochemical Products Swakleen 150), and 0.01 g of dibutyl dilaurate were added. The mixture was gradually heated to 80°C under a nitrogen atmosphere and reacted at 80°C for 2 hours. Then, 13.0 g of 2-isopropyl-3-(2-hydroxyethyl)oxazolidine was added and reacted at the same temperature for 1 hour to obtain 262.9 g of one-component moisture-curable polyurethane resin A (viscosity 130 mPa·s). (2) One-component moisture-curing polyurethane resin A 262.9g Dimethyl carbonate 10g Octylic acid 0.03g Fumed silica (Evonik ACEMATT3300, secondary particle size D50, 9.5 μm) 10 g Amid wax (Kusumoto Chemical Co., Ltd. product Disparon 6650) 6g UV absorber (Ciba-Geigy UV1164 product) 4g Light stabilizer (company product HALS292) 4g Hardener 32.1g [2-Isopropyl-3-(2-hydroxyethyl)oxazolidine An adduct of 2 moles of hexamethylene diisocyanate and 1 mole of hexamethylene diisocyanate. Molecular weight 486.68] The above mixture was thoroughly stirred to obtain a transparent moisture-curable resin composition (viscosity of 150 mPa·s at 23°C at 20 rpm using an E-type viscometer), which was used as the one-component moisture-curable urethane resin composition in Example 4.

[0062] Comparative Example 2 In Example 7, an inorganic paint (KF Chemical product Semiflon Super Mild II Clear; viscosity 200 mPa·s) was used instead of the one-component moisture-curing urethane resin composition.

[0063] The results obtained in each of the above Examples 7-8 and Comparative Examples 1-2 are shown in Table 2. Table 2 Evaluation items Actual 7 Actual 8 ratio 1 ratio 2 Breaking strength (N / mm 2 ) 40 35 15 10 Elongation at break (%) 300 180 350 8 Workability ○ ○ × ○ Punching strength (N) 400 180 70 8

[0064] Example 9 In the case of the bulging exterior wall, primer and urethane resin were applied twice, as in Example 7, and allowed to cure. Holes were drilled into the mortar joints where the vertical and horizontal joints intersected using a 4.3 mm concrete drill, reaching the concrete of the structure. Epoxy resin used in Example 1 was then injected through these holes, and 35 mm long iron screws with polycarbonate corrugated resin heads were inserted to secure the four tiles. The epoxy resin was allowed to cure for more than 12 hours. After the epoxy resin had cured, the screws were removed, the holes were filled with mortar and allowed to dry, and then the same urethane resin as the first application was applied to the tile surface. The screws were inserted at intervals of approximately 20-40 cm, depending on the degree of bulging.

[0065] As a result, the bulging of the tile surface was eliminated, and the impact test confirmed that there were no gaps between the tiles and the building structure.

[0066] Example 10 In Example 9, for areas where the tile bulge was significant, the insertion of 35mm long iron screws with polycarbonate corrugated resin heads was performed after the urethane resin had hardened but before the epoxy resin was injected. By suppressing the bulge to some extent before injecting the epoxy resin, the epoxy resin was efficiently injected into the peeling surface. As a result, after the epoxy resin hardened, the bulge on the tile surface disappeared, and the impact test confirmed that there were no gaps between the tiles and the structure.

Claims

1. The tiled wall surface contains a urethane prepolymer composed of acrylic polyol and aliphatic polyisocyanate, with a viscosity of 150–2,000 mPa·s at 23°C and 20 rpm measured with an E-type viscometer, and a tensile strength of 20 N / mm² after curing. 2 The above describes a tile fall prevention method comprising a first step of coating with a one-component moisture-curing urethane resin composition having an elongation of 50% or more at break, and a second step of injecting an epoxy resin composition into the back surface of the tile.

2. The epoxy resin composition has a viscosity of 1,000 to 40,000 mPa·s at 23°C and 10 rpm using a B-type viscometer, a thixotropic index (the ratio of values ​​at 2 rpm and 20 rpm using a B-type viscometer) of 1.5 to 6.0, and a tensile strength of 25 N / mm² after curing. 2 The tile fall prevention method according to claim 1, as described above.

3. A method for preventing tiles from falling, according to claim 1 or 2, wherein an epoxy resin composition containing a fluorescent substance is used.

4. A method for preventing tiles from falling, according to claim 1 or 2, wherein an epoxy resin composition containing core-shell type rubber particles or modified silicone resin is used.

5. A method for preventing tiles from falling, according to claim 1 or 2, wherein a primer containing an acrylic resin is applied to the tile before applying a one-component moisture-curing urethane resin composition.

6. A method for preventing tiles from falling, according to claim 1 or 2, wherein the puncture strength after curing of a one-component moisture-curable polyurethane resin composition applied to the tile is 200 N or more.

7. A tile fall prevention method according to claim 1 or 2, wherein after the first or second step, anchor screws are inserted to press the tiles into the concrete structure.

8. The tile fall prevention method according to claim 7, wherein the anchor screw has a resin plate with an arc-shaped curved head.

9. A method for preventing tiles from falling, according to claim 8, wherein after the epoxy resin has hardened, the screw holes from which the anchor pins were removed are filled with urethane resin, or urethane resin and mortar.