JP6994887B2 - Transparent undercoat material and concrete piece peeling prevention method - Google Patents

Description

The present invention relates to a transparent undercoat material used for a transparent concrete piece exfoliation prevention structure and a concrete piece exfoliation prevention method using the undercoat material, and is specifically formed by coating on the surface of a concrete structure without yellowing. A transparent undercoat that has a transparent reinforcing layer formed by applying a transparent polyurea resin coating material containing a modified isocyanate prepolymer, alicyclic polyamine , and aggregate , and is used for an overall transparent concrete piece exfoliation prevention structure. The present invention relates to a concrete piece exfoliation prevention method using a material and the undercoat material.

Conventionally, a concrete piece exfoliation prevention structure 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 exfoliation prevention performance. The concrete exfoliation prevention structure is a concrete piece exfoliation prevention structure 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, hydrophilic fine powder silica, and leology. A transparent polyurea resin coating material containing a 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 on the transparent reinforcing layer. This is a concrete piece exfoliation prevention structure characterized in that a transparent protective layer is formed by applying an acrylic silicon resin coating material containing a light stabilizer and an ultraviolet absorber (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-30716

However, the concrete fragment exfoliation prevention structure 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 some cases, there is a problem that the impregnation reinforcing effect of the silicon acrylic resin primer on the concrete surface is insufficient, and when the concrete surface is in a wet state, it is formed by being applied onto the transparent primer layer. There is a problem that the transparent reinforcing layer may swell.

An object of the present invention is a transparent undercoat that impregnates and reinforces the concrete surface even when the concrete surface is fragile, and does not cause swelling in the transparent reinforcing layer even when the concrete surface is in a wet state. It is an object of the present invention to provide a method for preventing peeling of materials and concrete pieces, and an alicyclic polyamine used for the method.

In order to solve the above problems, the invention according to claim 1 is a transparent polyurea resin coating material formed by coating on the surface of a concrete structure and containing a non-yellowing isocyanate prepolymer, an alicyclic polyamine and an aggregate. An undercoat material that has a transparent reinforcing layer formed by coating and is used for an overall transparent concrete piece exfoliation prevention structure, and is a bisphenol A type liquid epoxy resin, an alkylphenol type liquid epoxy resin, and a reactive diluent. Provided is a transparent undercoat material comprising a polyamide amine and an aliphatic modified polyamine, wherein the bisphenol A type liquid epoxy resin is 25 to 40 parts by weight in 100 parts by weight of the entire undercoat material.

（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記載の透明性下塗材を提供する。 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 having 1 to 18 carbon atoms, and m is an integer of at least 2).
The transparent undercoat material according to claim 1, wherein the polyamine is one or more kinds represented by.

The invention according to claim 3 provides the transparent undercoat material according to claim 1 or 2, wherein the alkylphenol type liquid epoxy resin has an epoxy equivalent of 200 to 250.

The transparency according to any one of claims 1 to 3, wherein the invention according to claim 4 is characterized in that the alkylphenol type liquid epoxy resin is 15 to 25 parts by weight out of 100 parts by weight of the entire undercoat material. Provide a sex undercoat material .

Further, in the invention according to claim 5 , the transparent undercoat material according to any one of claims 1 to 4 is applied to the surface of a concrete structure to form an undercoat layer, and the undercoat layer is formed. Provided is a method for preventing concrete pieces from peeling off, which comprises applying a transparent polyurea resin coating material containing a non-yellowing isocyanate prepolymer and an alicyclic polyamine to form a transparent reinforcing layer .

The transparent undercoat material according to the present application is formed by impregnating the concrete surface by being applied to the surface of a concrete structure, having an effect of reinforcing the surface, and applying the transparent undercoat material. It has the effect of having sufficient adhesion to the transparent reinforcing layer also formed by applying it on the undercoat layer, and even if the concrete surface is wet, the transparent reinforcing layer does not swell. effective.

Further, since the concrete piece exfoliation prevention method according to claim 5 uses the transparent undercoat material according to any one of claims 1 to 4 , the concrete surface is fragile as described above. Even if there is, there is an effect of impregnating and reinforcing the surface, and even if the concrete surface is wet, there is an effect that the transparent reinforcing layer does not swell.

Hereinafter, the present invention will be described in detail.

First, a concrete piece exfoliation prevention structure in which the transparent undercoat material according to the present application is used will be described. The concrete piece exfoliation prevention structure is formed by applying it to the surface of a concrete structure, and is formed by applying a transparent polyurea resin coating material containing a non-yellowing isocyanate prepolymer and an alicyclic polyamine. 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 modified isocyanate 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) A polyaspartic acid ester representing a group obtained by removing a primary amino group from isomeric C-monomethyldiaminodicyclohexylmethane and 3 (4) -aminomethyl-1-methylcyclohexylamine may be preferably used. can. 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 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). Diisocyanates, 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 structure 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 adhesion with the polyester fiber sheet disposed on the polyester fiber sheet may be insufficient, and if it is more than 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 polyester fiber sheet is preferably disposed in the transparent reinforcing layer in order to enhance the property of preventing concrete pieces from peeling off, and the amount of the polyester fiber sheet is preferably 0.06 to 0.13 kg / m ² . If the grain size of the polyester fiber sheet is less than 0.06 kg / m ² , the polyester fiber sheet frays at the time of laminating the polyester fiber sheet and the workability becomes poor, and if it exceeds 0.13 kg / m ² , the transparency becomes insufficient. In particular, the polyester fiber sheet has the effect of maintaining the transparency of the transparent reinforcing layer, and can be suitably used for the present invention. As a commercially available polyester fiber sheet, there is Unitika 5500 (trade name, basis weight: 0.095 kg / m ² , manufactured by Unitika Ltd.).

The undercoat material used when the concrete piece exfoliation prevention structure having the above-mentioned transparent reinforcing layer is applied to the concrete surface is the transparent undercoat material according to the present application, and the transparent undercoat material is bisphenol. It consists of an A-type liquid epoxy resin, an alkylphenol-type liquid epoxy resin, a reactive diluent, a polyamide amine, and an aliphatic modified polyamine.

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, and adipic acid, dimer acid or the like is used as the polybasic acid, and ethylenediamine, diethylenetriamine or the like is used as the polyamine compound. 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 to 405, viscosity: 500 to 1000 mP · s / 25 ° C., manufactured by T & K TOKA).

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 a 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).

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 the polyamide amine and the aliphatic modified polyamine is 0.8 to 1. 2 is preferable. If it is less than 0.8, the adhesiveness with the transparent reinforcing layer becomes insufficient at 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.

Hereinafter, a specific description will be given with reference to Examples and Comparative Examples.
Examples and Comparative Examples 1 to 5
JER828 (trade name, epoxy equivalent: 184 to 194, manufactured by Mitsubishi Chemical Corporation) as a bisphenol A type liquid epoxy resin, Epicron HP-820 as an alkylphenol type liquid epoxy resin, and adecaglycyrole ED-503 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 1 to obtain a transparent undercoat material of Examples and Comparative Examples 1 to 5.

Further, in evaluating the transparent undercoating materials of Examples and Comparative Examples 1 to 5, as a transparent polyurea resin coating material, a non-yellowing isocyanate prepolymer was added to Duranate TSE-100 (trade name, 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, and as an alicyclic polyamine, 4,4'-methylenebiscyclohexaneamine -Diethyl maleate adduct (weight average molecular weight (Mw): 548 (theoretical value), viscosity: 2000 mPa · s / 23 ° C.) and 4,4'-methylenebis (2-methylcyclohexylamine) -diethyl maleate adduct (diethyl maleate adduct (2-methylcyclohexylamine) Weight average molecular weight (Mw): 578 (theoretical value), viscosity; 2000 mP · s / 23 ° C.) mixed at 140: 460 (parts by weight) as a curing agent, and a main agent: curing agent in a weight blending ratio of 120. : A mixture of 100 was used.

Evaluation methods

Transparency 0.2 mm, 0.5 mm, 1.0 mm, 2.0 mm width on 300 mm x 300 mm x 60 mm thick dry concrete flat plate (5% or less in Kett Moisture Meter HI-520 concrete range) of JIS A5371 Make a line with a commercially available oil-based marker and dry it. After applying 0.25 kg / m ² of the transparent undercoat material of Examples and Comparative Examples 1 to 5 and curing it to form a transparent undercoat layer, polyurea resin coating material is coated with silicate sand Mizunami silica sand No. 6 polyurea. A mixture of 50 parts by weight with 100 parts by weight of the resin coating material was coated with 1.0 kg / m ² and immediately coated with polyester sheet Unitica 5500 (trade name, grain: 0.095 kg / m ² , manufactured by Unitica). After curing, 25 parts by weight of Sisago Mizunami No. 6 was mixed with 100 parts by weight of the polyurea resin coating material, and 0.3 kg / m ² was applied to the mixture. And dry to form a transparent reinforcing layer. After the transparent reinforcing layer was cured and dried, those in which the 0.2 mm line on the concrete surface was clearly visible were evaluated as ◯, and those invisible were evaluated as ×.

Maximum push-out load JIS A 5372 (precast reinforced concrete product) Class 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") The back surface of the central part of the concrete is cut with a core cutter for concrete with a shape of φ100 mm and a depth of 55 mm ± 3 mm. The surface is sanded, and the transparent undercoat material of Example or Comparative Examples 1 to 5 is applied to the treated surface at 0.25 kg / m ² and cured to form a transparent undercoat layer. A mixture of 100 parts by weight of Polyurea resin coating material and 50 parts by weight of Polyurea resin coating material was coated with 1.0 kg / m ² and immediately coated with polyester sheet Unitica 5500 (trade name, eye-catching:). 0.095 kg / m ² , manufactured by Unitika Co., Ltd.) was laid down to form a laminated state, and after curing, 25 parts by weight of Sisago Mizunami No. 6 was further mixed with 100 parts by weight of the polyurea resin coating material. To form a transparent reinforcing layer by applying 0.3 kg / m ² and drying. Further, a solvent-type acrylic silicon 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 dried concrete flat plate (5% or less in a Ket Moisture Meter HI-520 concrete range) of JIS A5371 300 mm × 300 mm × thickness 60 mm was sanded under 1 ° C., and the treated surface was subjected to Examples or The transparent undercoat material of Comparative Examples 1 to 5 is coated with 0.25 kg / m ² to form a transparent undercoat layer and 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 Mizunami No. 6 with a polyurea resin coating material to 100 parts by weight of the polyurea resin coating material for another 48 hours. Cure. After that, it is left at 23 ° C. for 24 hours, and a cutter knife is used to make cuts between the layers of the base, the transparent undercoat layer, and the transparent reinforcing layer, and a peeling force is applied to evaluate the adhesiveness. Those with good adhesiveness between all layers were evaluated as ◯, and the others were evaluated as x.

Bulge resistance Under 23 ° C, JIS A 5372 (precast reinforced concrete product) One type of upper lid type U-shaped gutter (lid) specified in Annex 5 Nominal name 300 (400 x 600 x thickness 60 mm) (hereinafter, "U-shaped" The concrete plate of "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, the transparent undercoat material of Example or Comparative Examples 1 to 5 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 Polyurea resin coated material with 50 parts by weight of Sisago Mizunami No. 6 was applied to 100 parts by weight of the polyurea resin coated material, and the polyester sheet Unitika 5500 (trade name) was immediately applied. , Grain: 0.095 kg / m ² , manufactured by Unitika Ltd.) and cure for 24 hours. After that, Mizunami No. 6 is mixed with 100 parts by weight of the polyurea resin coating material by 25 parts by weight, 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 silicon 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 forming the transparent protective layer and curing it 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 ○.

Evaluation Results The evaluation results are shown in Table 2.

Claims (5)

It has a transparent reinforcing layer formed by coating on the surface of a concrete structure and coated with a transparent polyurea resin coating containing a non-yellowing isocyanate prepolymer, an alicyclic polyamine and aggregate . It is an undercoat material used for a transparent concrete piece peeling prevention structure as a whole, and consists of bisphenol A type liquid epoxy resin, alkylphenol type liquid epoxy resin, reactive diluent, polyamide amine and aliphatic modified polyamine, and bisphenol A. The mold liquid epoxy resin is a transparent undercoat material, characterized in that it is 25 to 40 parts by weight out of 100 parts by weight of the entire undercoat material. 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 transparent undercoat material according to claim 1, which is the above-mentioned polyamine. The transparent undercoat material according to claim 1 or 2, wherein the alkylphenol type liquid epoxy resin has an epoxy equivalent of 200 to 250. The transparent undercoat material according to any one of claims 1 to 3, wherein the alkylphenol type liquid epoxy resin is 15 to 25 parts by weight out of 100 parts by weight of the entire undercoat material. The transparent undercoat material according to any one of claims 1 to 4 is applied to the surface of a concrete structure to form an undercoat layer, and the undercoat layer is coated with a non-yellowing isocyanate prepolymer and a fat. A concrete piece exfoliation prevention method characterized by applying a transparent polyurea resin coating material containing a ring-type polymer and an aggregate to form a transparent reinforcing layer.