JP6983031B2 - Concrete piece peeling prevention method - Google Patents

Description

The present invention relates to a transparent concrete piece exfoliation prevention method, and is specifically formed by coating on the surface of a concrete structure, and is coated with a transparent polyurea resin coating material containing a non-yellowing isocyanate prepolymer and an alicyclic polyamine. The present invention relates to a method for preventing concrete pieces from peeling off, which has a transparent reinforcing layer and is transparent as a whole.

Conventionally, a concrete piece peeling prevention method has been proposed in which the degree of deterioration of the concrete surface layer can be confirmed in a timely manner and the coating film strength is set to high strength to exhibit high peeling prevention performance. The concrete piece peeling prevention method is a concrete piece peeling prevention method formed by coating on the surface of a concrete structure, and a silicon acrylic resin primer containing an amino group-containing acrylic resin and an epoxysilane is applied to the surface of the concrete. A transparent primer layer is formed, and on the transparent primer layer, a non-yellowing isocyanate prepolymer having an NCO weight% of 5 to 10% by weight, an alicyclic polyamine, transparent reinforcing short fibers, and hydrophilic fine powder silica are added. A transparent polyurea resin coating material containing a rheology control agent, a light stabilizer, and an ultraviolet absorber is applied to form a transparent reinforcing layer, and a glass fiber cloth is laminated in the transparent reinforcing layer to form the transparent reinforcing layer. It is a concrete piece exfoliation prevention method characterized by applying an acrylic silicone resin coating material containing a light stabilizer and an ultraviolet absorber to form a transparent protective layer (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-30716

However, the concrete fragment exfoliation prevention method according to Patent Document 1 uses a silicon acrylic resin primer containing an amino group-containing acrylic resin and an epoxysilane as a transparent primer layer to be applied to the concrete surface, so that the concrete surface is fragile. In the case of, there is a problem that the impregnation reinforcing effect of the silicon acrylic resin primer on the concrete surface may be insufficient, and when the concrete surface is in a wet state, it is formed by applying it on the transparent primer layer. There is a problem that the transparent reinforcing layer to be formed may swell.

The subject of the present invention is that even if the concrete surface is fragile, the concrete surface is impregnated and reinforced, and even if the concrete surface is in a wet state, the transparent reinforcing layer is not swelled and is transparent. It is an object of the present invention to provide a concrete piece exfoliation prevention method and an alicyclic polyamine used for the method.

In order to solve the above problems, the invention according to claim 1 is formed by coating on the surface of a concrete structure, and is coated with a transparent polyurea resin coating material containing a non-yellowing isocyanate prepolymer and an alicyclic polyamine. It is a concrete piece peeling prevention method that has a transparent reinforcing layer formed by the concrete and forms a transparent concrete piece peeling prevention structure as a whole. A transparent undercoat material consisting of polyamide amine and aliphatic modified polyamine is applied to the surface of a concrete structure to form an undercoat layer and hardened, and a plain weave consisting of untwisted warp threads and weft threads is formed on the undercoat layer. A transparent reinforcing layer is formed and cured in a state where the polyester fiber sheet, the non-yellowing isocyanate prepolymer, the alicyclic polyamine, and the polyurea resin coating material composed of silica sand are integrated, and the transparent reinforcing layer is transparent on the transparent reinforcing layer. Provided is a concrete piece exfoliation prevention method characterized by forming a protective layer.

（式中Ｘはイソシアネート基に対して不活性であり、脂環式炭化水素に結合したｍ個の第１級アミノ基を含む数平均分子量８８〜４００の有機ポリアミンから第１級アミノ基を除去することにより得られるｍ価基であり、Ｒ^１及びＲ^２は同一または異なっていて、炭素原子数１〜１８の有機基であり、ｍは少なくとも２の整数である）
で表される１種以上のポリアミンであることを特徴とする請求項１記載のコンクリート片剥落防止工法を提供する。 Further, in the invention according to claim 2, the alicyclic polyamine is the formula I :.

(X in the formula is inert to the isocyanate group, and the primary amino group is removed from the organic polyamine having a number average molecular weight of 88 to 400 including m primary amino groups bonded to the alicyclic hydrocarbon. R ¹ and R ² are the same or different organic groups with 1 to 18 carbon atoms, and m is an integer of at least 2).
The concrete piece exfoliation prevention method according to claim 1, wherein the polyamine is one or more kinds represented by.

Further, the invention according to claim 3 provides the concrete piece peeling prevention method according to ^{claim 1 or 2} , wherein the polyester fiber mesh sheet has a basis weight of 60 g to 130 g / m 2.

Further, the invention according to claim 4 provides the concrete piece peeling prevention method according to claim 1 or ² , wherein the polyester fiber mesh sheet has a basis weight of 75 g to 110 g / m 2.

The concrete piece peeling prevention method according to the present application has the effect of impregnating the concrete surface by applying the transparent undercoat material to the surface of the concrete structure to reinforce the surface, and also applies the transparent undercoat material. It has the effect of having sufficient adhesion to the transparent reinforcing layer also formed by coating on the undercoat layer formed in the concrete, and even if the concrete surface is wet, the transparent reinforcing layer will swell. It has the effect of not occurring.

Further, since the concrete piece peeling prevention method according to the present application uses a transparent undercoat material, even if the concrete surface is fragile, it has the effect of impregnating and reinforcing the surface, and even if the concrete surface is wet, it is transparent. There is an effect that the reinforcing layer does not swell.

Hereinafter, the present invention will be described in detail.

First, a concrete piece exfoliation prevention method in which the transparent undercoat material according to the present application is used will be described. The concrete piece exfoliation prevention method is formed by applying a transparent polyurea resin coating material containing a non-yellowing isocyanate prepolymer and an alicyclic polyamine to the surface of a concrete structure to form a transparent reinforcement. Has a layer.

The polyurea resin coating material is composed of a non-yellowing isocyanate prepolymer having an NCO weight% of 5 to 10% by weight and an alicyclic polyamine, and hexamethylene for a non-yellowing isocyanate prepolymer having an NCO weight% of 5 to 10% by weight. An aliphatic bifunctional isocyanate such as diisocyanate (HDI), an alicyclic bifunctional isocyanate such as isophorone diisocyanate (IPDA), 4,4'-diphenylmethane diisocyanate (MDI) and 4,4'-methylenebis (cyclohexyl isocyanate) ( A prepolymerized product of hydride MDI) or the like with a polyhydric alcohol can be used.

The alicyclic polyamine is a polyamine in which at least one amino group such as isophorone diamine is directly bonded to a cyclohexane ring or the like, and an amine having only a secondary amino group containing no primary amino group is used. .. The weight average molecular weight (theoretical value) is preferably 300 to 1000. If it is less than 300, the pot life becomes short and the workability becomes poor, and if it exceeds 1000, the reaction rate decreases, and the time until dry to the touch and the rise of the coating film strength are delayed. For the first time, by using an alicyclic polyamine having only a secondary amino group, it is possible to secure a sufficient pot life during which the polyurea resin coating material can be applied with an iron or the like, and further, no yellowing. When used in combination with a polyisocyanate prepolymer, the cured coating does not turn yellow due to ultraviolet light.

The alicyclic polyamine is represented by the above formula I, and X, R ¹ , R ² , and m are one or more polyamines as described above. This alicyclic polyamine is a polyaspartic acid ester or a polyaspartate, and m is preferably 2. X is a divalent hydrocarbon group having 6 to 30 carbon atoms, for example, 4,4'-diaminodicyclohexylmethane (4,4'methylenebis (cyclohexylamine)), 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane. (4,4'methylenebis (2-methylcyclohexylamine)), 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, hexahydro- (at least 2,4-diaminotoluene or 2,6-diaminotoluene) (Including any), a polyaspartanoic acid ester representing a group obtained by removing a primary amino group from isomeric C-monomethyldiaminodicyclohexylmethane and 3 (4) -aminomethyl-1-methylcyclohexylamine is preferably used. Can be done. In particular, X is 4,4'-diaminodicyclohexylmethane (4,4'methylenebis (cyclohexylamine)) or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (4,4'methylenebis (2-methylcyclohexylamine)). )), A compound of formula I representing a divalent hydrocarbon group that can be obtained by removing the primary amino group is more preferable.

As the alicyclic polyamine represented by the formula I, R ¹ and R ² are preferably methyl, ethyl, n-butyl or 2-ethylhexyl, _{and the primary polyamine represented by the formula X- (-NH 2} ) m is represented by the formula R. ¹ It is produced by reacting with a maleic acid ester or a fumaric acid ester represented by OOC-CH = CH-COOR ^2.

The alicyclic polyamine having only a secondary amino group, which is obtained by reacting 1 mol of 4,4'-methylenebiscyclohexylamine with 2 mol of diethyl maleate, is 4,4'-methylenebiscyclohexylamine / maleic acid. It is supplied to the market as a diethyl adduct, and its weight average molecular weight (Mw) is 548 (theoretical value) and its viscosity is 2000 mPa · s / 23 ° C. Further, as an alicyclic polyamine having only a secondary amino group, which is obtained by reacting 1 mol of 4,4'methylenebis (2-methylcyclohexylamine) with 2 mol of diethyl maleate, 4,4'-. It is supplied to the market as a methylenebis (2-methylcyclohexylamine) -diethyl maleate adduct, and its weight average molecular weight (Mw) is 578 (theoretical value), and its viscosity is 2000 mPa · s / 23 ° C.

As described above, the non-yellowing isocyanate prepolymer having an NCO% by weight of 10 to 30% by weight includes an aliphatic bifunctional isocyanate such as hexamethylene diisocyanate (HDI) and an alicyclic bifunctional such as isophorone diisocyanate (IPDA). Isocyanates, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-methylenebis (cyclohexyl isocyanate) (hydrogenated MDI) and the like prepolymerized with a polyhydric alcohol can be used. In particular, a non-yellowing isocyanate prepolymer obtained by reacting a polycoupler cton-modified polyol with 1,6-hexamethylene diisocyanate is suitable, and as the prepolymer, Duranate TSE-100 (trade name, manufactured by Asahi Kasei Chemicals Co., Ltd.) is suitable. , NCO weight%: 12.0%, viscosity 1650 mPa · s / 25 ° C., solid content 100%). If the NCO% by weight is less than 10% by weight, the coating film strength becomes insufficient, and if it exceeds 30% by weight, the pot life when the material is used in the summer is shortened.

The equivalent ratio (number of NCO groups / number of active hydrogen groups) between the NCO group of the non-yellowing isocyanate prepolymer and the active hydrogen group of the alicyclic polyamine is preferably 0.8 to 1.2. If it is less than 0.8, the viscosity increase after mixing the non-yellowing isocyanate prepolymer and the alicyclic polyamine becomes faster and the pot life becomes shorter. If it exceeds 1.2, the time to dry to the touch and the rise of the coating film strength are delayed.

The polyurea resin coating material preferably contains a light stabilizer and an ultraviolet absorber in addition to the above-mentioned non-yellowing isocyanate prepolymer and alicyclic polyamine, and by containing these, it is transparent even when exposed to ultraviolet rays for a long period of time. The strength of the reinforcing layer does not decrease. A hindered amine-based light stabilizer can be used as the light stabilizer, and a hydroxyphenyltriazine-based ultraviolet absorber or a benzotriazole-based ultraviolet absorber can be used as the ultraviolet absorber. As a commercially available hindered amine-based light stabilizer, TINUVIN292 (trade name, chemical name; bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate), manufactured by Ciba Japan Co., Ltd.) is commercially available. As a hydroxyphenyltriazine-based ultraviolet absorber, TINUVIN400 (trade name, chemical name; 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine-2-yl) -5- TINBIN928 (trade name, chemical name; 2- (2H-benzotriazole-2-yl)) is a commercially available benzotriazole-based ultraviolet absorber produced by Ciba Japan Co., Ltd., a reaction product of hydroxyphenyl and oxylan. -6- (1-Methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol, manufactured by Ciba Japan Co., Ltd.

Further, the polyurea resin coating material is applied over the transparent undercoat material according to the present application, and the transparent undercoat material impregnates the concrete surface to reinforce the surface and is applied as the upper layer. Firmly adheres to polyurea resin coating material. In order to maintain the transparency of the concrete piece exfoliation prevention method as a whole for a long period of time, the thickness (coating amount) of the transparent undercoat material containing the epoxy resin that easily turns yellow should be small. Preferably, in the present invention, a coating amount of about ^{0.15 to 0.30 kg / m 2 is preferable.} With the amount of coating, it is difficult to fill all the large and small voids (unevenness) on the concrete surface and adjust the non-landing. It is preferable to contain an aggregate such as silica sand having a diameter.

The silica sand preferably has a particle size (average particle size D ₅₀ ) at which the cumulative cumulative weight is 50% is 100 to 500 μm, and may contain 20 to 80 parts by weight of the silica sand with respect to 100 parts by weight of the polyurea resin coating material. preferable. If it is less than 20 parts by weight, the non-landing preparation may be insufficient when the base has irregularities, and if it exceeds 80 parts by weight, the transparency is lowered. As a commercially available silica sand, there is Mizunami silica sand No. 6 (trade name, average particle size D ₅₀ : 400 μm, manufactured by Tokai Mattel Co., Ltd.).

A fiber mesh sheet is preferably disposed in the transparent reinforcing layer in order to enhance the concrete piece peeling prevention performance, and the fiber mesh sheet is particularly preferably a polyester fiber mesh sheet. The polyester fiber mesh sheet, particularly, a plain weave composed of warp and weft of non-twist yarns are preferred, and is preferably a polyester fiber sheet 60g~130g / ^{m 2} as a weight per unit area, the more basis weight 75g~110g / ^{m 2} Is particularly preferable in terms of workability and transparency.

When the grain size is ^{less than 60 g / m 2} , when the polyester fiber mesh sheet is arranged on the undercoat layer and integrated with the polyurea resin coating material consisting of a non-yellowing isocyanate prepolymer, an alicyclic polyamine and silica sand. In addition, the warp and weft of the polyester fiber mesh sheet are frayed, resulting in poor workability. When the basis weight exceeds 130 g / m ² , the transparency decreases. As a commercially available polyester fiber mesh sheet that can be particularly suitably used for the present invention, there is Unitika 5500 (trade name, basis weight: 95 g / m ² , manufactured by Unitika Ltd.).

The transparent undercoat material used in the concrete piece exfoliation prevention method having a transparent reinforcing layer as described above is composed of bisphenol A type liquid epoxy resin, alkylphenol type liquid epoxy resin, reactive diluent, polyamide amine and aliphatic modified polyamine. Become.

The bisphenol A type liquid epoxy resin is a bisphenol A type diglycidyl ether having an epoxy equivalent of 180 to 195 and is liquid, and the alkylphenol type liquid epoxy resin has an epoxy equivalent of 200 to 250 and has a hydroxyl group. Liquid epoxy resin is preferred. The blending amount of the bisphenol A type liquid epoxy resin is preferably 25 to 40 parts by weight out of 100 parts by weight of the entire transparent undercoat material, and if it is less than 25 parts by weight, curing is insufficient, and if it exceeds 40 parts by weight, workability at low temperature is achieved. Decreases.

The blending amount of the alkylphenol type liquid epoxy resin is preferably 15 to 25 parts by weight out of 100 parts by weight of the entire transparent undercoat material, less than 15 parts by weight reduces workability at low temperature, and more than 25 parts by weight at 50 ° C. The punching test of is less than 1.5kN. As a commercially available alkylphenol type liquid epoxy resin, there is Epicron HP-820 (trade name, epoxy equivalent: 200 to 250, viscosity 1000-3000 mPa · s / 25 ° C., manufactured by DIC) which is an alkyldiphenol type liquid epoxy resin.

The transparent primer contains a reactive diluent in addition to these epoxy resins, which are used for the purpose of reducing the viscosity of the epoxy resin and have two glycidyls in the molecule. A bifunctional reactive diluent having a group is preferred. The blending amount of the reactive diluent is preferably 10 to 20 parts by weight out of 100 parts by weight of the entire transparent undercoat material, and if it is less than 10 parts by weight, the workability at low temperature becomes insufficient, and if it exceeds 20 parts by weight, the hardness of the cured product is high. Run short. As a commercially available bifunctional reactive diluent, there is ADEKA glycyrol ED-503 (trade name, 1,6-hexanediol diglycidyl ether, epoxy equivalent: 165, manufactured by ADEKA).

The polyamide amine contained in the transparent undercoat material is a dehydration condensate of a polybasic acid and a polyamine compound. As the polybasic acid, adipic acid, dimer acid or the like is used, and as the polyamine compound, ethylenediamine, diethylenetriamine or the like is used. Can be done. The active hydrogen equivalent is preferably 100 to 150, and if it is less than 100, the adhesion to the transparent reinforcing layer may be insufficient, and if it exceeds 150, the curing at a low temperature is insufficient. The blending amount is preferably 15 to 30 parts by weight out of 100 parts by weight of the transparent undercoat material, and if it is less than 15 parts by weight, the adhesion to the transparent reinforcing layer may be insufficient, and if it exceeds 30 parts by weight, the hardness of the cured product is insufficient. do. Commercially available polyamined amines include tomide 2500 (trade name, active hydrogen equivalent: 125, amine value: 375-405, viscosity: 500 to 1000 mP · s / 25 ° C., manufactured by T & K TOKA Co., Ltd.).

As the aliphatic-modified polyamine contained in the transparent undercoat material, an aliphatic polyamine modified by Mannig or an epoxy resin added can be used, and the active hydrogen equivalent is preferably 60 to 80, and if it is less than 60, the transparent reinforcement is performed. Adhesion to the layer may be inadequate, and above 80, curing at low temperatures will be inadequate. The blending amount is preferably 5 to 20 parts by weight out of 100 parts by weight of the entire transparent undercoat material, and if it is less than 5 parts by weight, curing at low temperature is insufficient, and if it exceeds 20 parts by weight, the adhesiveness to wet concrete is poor. Will be enough. As a commercially available aliphatic modified polyamine, there is Fujicure 8116 (trade name, active hydrogen equivalent: 71, amine value: 100 to 400, viscosity 100 to 400 mP · s / 25 ° C., manufactured by T & K TOKA Co., Ltd.).

The equivalent ratio (number of epoxy groups / number of active hydrogen groups) between the number of epoxy groups in the epoxy resin of the transparent undercoat material and the number of active hydrogen groups of polyamide amine and aliphatic modified polyamine is 0.8 to 1. 2 is preferable. If it is less than 0.8, the adhesiveness to the transparent reinforcing layer becomes insufficient at a low temperature, and if it exceeds 1.2, the adhesiveness to wet concrete becomes insufficient.

In addition to these, phenols such as styrenated phenol may be added to the transparent undercoat material, and non-crystalline fine powder fumed silica or fumed silica is used to prevent sagging when applied. A rheology control agent having a free OH group that forms a hydrogen bond with a silanol group on the surface of the particles and forms a three-dimensional structure with the silica particles by the hydrogen bond can be used. Polyhydroxycarboxylic acid amide can be preferably used as the rheology control agent, and BYK-405 (trade name, manufactured by Big Chemie Co., Ltd., polyhydroxycarboxylic acid amide content 51) can be preferably used as a commercially available rheology control agent. %). In addition, an adhesive-imparting agent such as a silane coupling agent or an antifoaming agent may be blended.

The transparent protective layer used in the concrete piece peeling prevention method of the present invention may be any material as long as it has transparency and has good adhesiveness to the polyurea resin coating material underlying the transparent protective layer. In particular, an acrylic silicone resin coating material having good transparency, good adhesion to a polyurea resin coating material, and excellent durability can be preferably used.

The acrylic silicone resin coating material may contain, for example, an acrylic silicone oligomer having an alkoxysilyl group as a main component, and a tin-based curing catalyst may be used as the curing agent, and the acrylic silicone resin coating material is applied on the already formed transparent reinforcing layer. Immediately before applying the material, the main agent and the curing agent are uniformly mixed and applied with a roller brush or the like. The alkoxysilyl group of the main agent is crosslinked by the tin-based curing catalyst of the curing agent to form a stable siloxane bond, and exhibits excellent durability.

The content of the alkoxysilyl group when the acrylic silicone resin coating material is used for forming the transparent protective layer is preferably 2% by weight to 30% by weight. If it is less than 2% by weight, the weather resistance is lowered, and if it is more than 30% by weight, the workability is lowered due to the increase in viscosity. As a commercially available acrylic silicone oligomer having an alkoxysilyl group, Kaneka Zemlac YC4383 (trade name, siloxane crosslinked reactive polymer, viscosity 4000 mP · s / 23 ° C., alkoxyryl group content; 15% by weight, manufactured by Kaneka Corporation ). As a commercially available tin-based curing catalyst, there is BT405Z (trade name, chemical name; organic tin compound, effective tin component; 1.3%, manufactured by Kaneka Co., Ltd.).

The acrylic silicone resin coating material preferably contains a light stabilizer and an ultraviolet absorber, and by containing these, the strength of the transparent protective layer does not decrease even when exposed to ultraviolet rays for a long period of time. A hindered amine-based light stabilizer can be used as the light stabilizer, and as a commercially available hindered amine-based light stabilizer, TINUVIN292 (trade name, chemical name; bis (1,2,2,6,6-pentamethyl-4) -Piperidil) Sevacate), Ciba Japan Co., Ltd.), hydroxyphenyltriazine-based UV absorbers or benzotriazole-based UV absorbers can be used as UV absorbers, and commercially available hydroxyphenyltriazine-based UV absorbers can be used. As the agent, TINUVIN400 (trade name, chemical name; 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine-2-yl) -5-hydroxyphenyl and oxylan As a commercially available benzotriazole-based ultraviolet absorber, the reaction product (manufactured by Ciba Japan Co., Ltd.) is TINUVIN928 (trade name, chemical name; 2- (2H-benzotriazole-2-yl) -6- (1-). Methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol, manufactured by Ciba Japan Co., Ltd.).

Hereinafter, a specific description will be given with reference to Examples and Comparative Examples.

<Examples and comparative examples>
The evaluation of the concrete piece exfoliation prevention method of Examples and Comparative Examples was carried out by the transparent undercoat materials A, B, C, D, E, F, the polyurea resin coating material, and the fiber mesh sheets A, B, as shown below. C, D, E, and F were combined as shown in Table 1.

<Transparent undercoat material>
JER828 (trade name, epoxy equivalent: 184 to 194, manufactured by Mitsubishi Chemical Corporation) is used as a bisphenol A type liquid epoxy resin, Epicron HP-820 is used as an alkylphenol type liquid epoxy resin, and adecaglycyrole ED-503 is used as a reactive diluent. , Tomide 2500 as polyamide amine A, TXE524 (trade name, active hydrogen equivalent: 130, amine value: 55-285, viscosity: 80-180, manufactured by T & K TOKA) as polyamide amine B, and Fujicure as an aliphatic modified polyamine. 8116 was used and uniformly mixed according to the formulation shown in Table 2 to obtain transparent undercoat materials A, B, C, D, E and F of the concrete piece peeling prevention method.

<Polyurea resin coating material>
As a transparent polyurea resin coating material, a non-yellowing isocyanate prepolymer and Duranate TSE-100 (trade name, manufactured by Asahi Kasei Chemicals Co., Ltd., NCO weight%: 12.0%, viscosity: 1650 mPa · s / 25 ° C., solid content : 100%, NCO equivalent: 350) as the main ingredient, as an alicyclic polyamine, 4,4'-methylenebiscyclohexaneamine / diethyl maleic acid adduct (weight average molecular weight (Mw): 548 (theoretical value), viscosity: 2000 mPa · s / 23 ° C) and 4,4'-methylenebis (2-methylcyclohexylamine) -diethyl maleate (weight average molecular weight (Mw): 578 (theoretical value), viscosity; 2000 mP · s / 23 ° C) Was used as a curing agent at a ratio of 140: 460 (parts by weight), and a mixture of a main agent: a curing agent at a weight blending ratio of 120: 100 was used as the polyurea resin coating material A.

<Fiber mesh sheet>
Further, as the fiber mesh sheet to be integrated with the polyurea resin coating material in the transparent reinforcing layer, the fiber mesh sheets A, B, C, D, E and F shown in Table 3 were used.

<Evaluation method>

<Transparency>
Lines with widths of 0.2 mm, 0.5 mm, 1.0 mm, and 2.0 mm on a dry concrete flat plate (5% or less in the Ket Moisture Analyzer HI-520 concrete range) of 300 mm x 300 mm x 60 mm thickness of JIS A5371. Is made with a commercially available oil-based magic and dried. ^{After applying 0.25 kg / m 2} of each of the transparent undercoat materials of Examples and Comparative Examples and curing them to form a transparent undercoat layer, the polyurea resin coating material is coated with silica sand Mizunami silica sand No. 6 and the polyurea resin coating material 100. The mixture of 50 parts by weight ^{was coated with 1.0 kg / m 2} , and the fiber mesh sheets of Examples and Comparative Examples were immediately laid down to form a laminated state, which was further coated with polyurea resin after curing. A transparent reinforcing layer is formed by applying ^{0.3 kg / m 2} of the mixture obtained by mixing 25 parts by weight of Sisago Mizunami No. 6 with 100 parts by weight of a polyurea resin coating material and drying it. After the transparent reinforcing layer is cured and dried, a solvent-type acrylic silicone resin clear coating material JUU-630 (trade name, solvent content: 38% by weight, manufactured by Aica Kogyo Co., Ltd.) is applied and dried at ^{0.07 kg / m 2.} Form a transparent protective layer. After curing for 7 days under the conditions of 23 ° C. and RH 50%, those in which the 0.2 mm line on the concrete surface was visually visible were evaluated as ◯, and those invisible were evaluated as ×.

<Maximum push-out load>
JIS A 5372 (precast reinforced concrete product) Type 1 of upper lid type U-shaped gutter (lid) specified in Annex 5 Nominal name 300 (400 x 600 x 60 mm) (hereinafter referred to as "U-shaped lid") concrete central part Cut the back surface with a concrete core cutter with a shape of φ100 mm and a depth of 55 mm ± 3 mm. ^{The surface is sanded, and 0.25 kg / m 2} of each of the transparent undercoat materials of Examples or Comparative Examples is applied to the treated surface and cured to form a transparent undercoat layer, and then a polyurea resin coating material is formed. A mixture of 100 parts by weight of Polyurea resin coating material and 50 parts by weight ^{was coated with 1.0 kg / m 2,} and the fiber mesh sheets of Examples or Comparative Examples were immediately laid down. After curing, the mixture was further mixed with Sisago Mizunami No. 6 by 25 parts by weight with 100 parts by weight of the polyurea resin coating material, and 0.3 kg / m ² was applied and dried. Form a transparent reinforcing layer. Further, a solvent-type acrylic silicone resin clear coating material JUU-630 (trade name, solvent content: 38% by weight, manufactured by Aica Kogyo Co., Ltd.) is applied onto the transparent reinforcing layer at 0.07 kg / m ² and dried. Form a transparent protective layer. After curing for 7 days under the conditions of 23 ° C. and RH 50%, a test piece for measuring the maximum punching load is obtained. Then, the test piece was tested according to JSCE-K 533 2013 (punching test method of surface covering material applied to prevent peeling of concrete pieces), and the maximum load was set to the maximum punching load (kN). The value of 1.5 kN or more was evaluated as ◯, and the other values were evaluated as x. The temperatures at the time of the test were 23 ° C and 50 ° C.

<Adhesiveness>
The surface of a dry concrete flat plate (5% or less in a Kett Moisture Analyzer HI-520 concrete range) of JIS A5371 having a thickness of 300 mm × 300 mm × thickness 60 mm was sanded at 1 ° C., and the treated surface was subjected to Example or Comparative Example. ^{0.25 kg / m 2} of each transparent undercoat material is applied to form a transparent undercoat layer, which is cured for 48 hours. Then, a transparent reinforcing layer was formed by applying ^{1.0 kg / m 2 of the} mixture obtained by mixing 50 parts by weight of Polyurea resin coated material with 50 parts by weight of Sisago Mizunami No. 6 to 100 parts by weight of the polyurea resin coated material for another 48 hours. Cure. After that, it was left at 23 ° C for 24 hours, and a notch was made between each layer of the base, the transparent undercoat layer, and the transparent reinforcing layer formed of the polyurea resin coating material with a cutter knife, and the adhesiveness was evaluated by applying peeling force. do. Those with good adhesiveness between all layers were evaluated as ◯, and the others were evaluated as x.

<Blistering resistance>
At 23 ° C, one type of upper lid type U-shaped gutter (lid) specified in JIS A 5372 (precast reinforced concrete product) Annex 5 Nominal name 300 (400 x 600 x thickness 60 mm) (hereinafter referred to as "U-shaped lid") ) Is immersed in water for 24 hours or more. Immediately before applying the transparent undercoat material, keep the water level lowered to a thickness of 30 mm on the concrete plate and wipe off the water on the surface of the concrete plate with a waste cloth. Within 5 minutes after wiping, each transparent undercoat material of Example or Comparative Example is applied at 0.25 kg / m ² to form a transparent undercoat layer and cured for 24 hours. ^{Next, 1.0 kg / m 2} of the mixture obtained by mixing 50 parts by weight of the polyurea resin coating material with 50 parts by weight of Kisago Mizunami No. 6 with 100 parts by weight of the polyurea resin coating material was immediately applied to each of Examples or Comparative Examples. A fiber mesh sheet is attached and cured for 24 hours. After that, the polyurea resin coating material is mixed with 25 parts by weight of Sisago Mizunami No. 6 with 100 parts by weight of the polyurea resin coating material, and 0.3 kg / m ² is applied to the mixture to form a transparent reinforcing layer and cure for 24 hours. Further, a solvent-type acrylic silicone resin clear coating material JUU-630 (trade name, solvent content: 38% by weight, manufactured by Aica Kogyo Co., Ltd.) is applied onto the transparent reinforcing layer at 0.07 kg / m ² and dried. Form a transparent protective layer. After the transparent protective layer is formed and cured for 6 days, the concrete plate is taken out from the water (semi-immersed state) and further cured at 23 ° C. for 48 hours. After that, visually observe the presence or absence of swelling of the coating film composed of the transparent undercoat layer, the transparent reinforcing layer, and the transparent protective layer. Δ, those without swelling were evaluated as ○.

<Workability>
In the evaluation of the above transparency, the one in which the fiber mesh sheet was laid down smoothly was evaluated as ◯, the one in which the laying down work took a little time and effort was evaluated as Δ, and the one in which the laying down work could not be performed smoothly was evaluated as ×.

<Evaluation result>
The evaluation results are shown in Table 4.

Claims (4)

It has a transparent reinforcing layer formed by coating on the surface of a concrete structure and formed by applying a transparent polyurea resin coating material containing a non-yellowing isocyanate prepolymer and an alicyclic polyamine, and is transparent as a whole. A transparent undercoat material consisting of a bisphenol A type liquid epoxy resin, an alkylphenol type liquid epoxy resin, a reactive diluent, a polyamide amine, and an aliphatic modified polyamine. Is applied to the surface of a concrete structure to form an undercoat layer and hardened, and a plain-woven polyester fiber mesh sheet consisting of warp and weft of non-twisted yarn, a non-yellowing isocyanate prepolymer, and fat A transparent reinforcing layer is formed and cured in a state in which a polyurea resin coating material composed of a cyclic polyamine and silica sand is integrated, and a transparent protective layer is formed on the transparent reinforcing layer. Prevention method. Alicyclic polyamines are of formula I:

(X in the formula is inert to the isocyanate group, and the primary amino group is removed from the organic polyamine having a number average molecular weight of 88 to 400 including m primary amino groups bonded to the alicyclic hydrocarbon. R ¹ and R ² are the same or different organic groups having 1 to 18 carbon atoms, and m is an integer of at least 2). The concrete piece exfoliation prevention method according to claim 1, wherein the polyamine is the above. The concrete piece exfoliation prevention method according to claim 1 or ² , wherein the polyester fiber mesh sheet has a basis weight of 60 g to 130 g / m 2. The concrete piece exfoliation prevention method according to claim 1 or ² , wherein the polyester fiber mesh sheet has a basis weight of 75 g to 110 g / m 2.