JP7344105B2 - How to protect structures - Google Patents

Description

The present invention relates to a method for protecting a structure, and more specifically, to a structure that protects the surface of a structure, allows visual confirmation of defects or damage, and prevents pieces from falling off. Concerning how to protect things.

In concrete structures, parts of concrete members may fall off as fragments due to defects during construction, damage due to earthquakes or collisions, chemical deterioration such as carbonation, salt damage, or alkaline aggregate reactions. . To prevent concrete pieces from falling off, conventional methods include covering the concrete surface with metal such as iron plates, continuous fiber sheets such as glass cloth, synthetic resin fiber sheets, carbon fiber sheets, and synthetic resin materials. Alternatively, a method of attaching it to the concrete surface using an inorganic material such as cement has been proposed and implemented.

In the spalling prevention system using fiber sheets, continuous fiber sheets such as glass cloth and vinylon are combined for reinforcement, so by making the synthetic resin that holds the fiber sheets transparent, it is possible to prevent concrete from forming even after the layer is formed. Although visual diagnosis, which is an important method for diagnosing the degree of deterioration, becomes possible, it is difficult to make the fiber sheet part transparent, and a grid-like opaque part remains in appearance, making visual diagnosis difficult. This poses a problem in that it not only impedes the appearance of the product, but also results in an aesthetically unsightly finish.

In order to solve such problems, Patent Document 1 listed below discloses that a transparent epoxy resin primer having a viscosity in the range of 20 to 5000 mPa・s and a tensile strength of 1 MPa or more when cured is applied to the surface layer of a concrete structure. A curable composition of polyurethane or polyurea having a tensile strength of 5 MPa or more and a tensile elongation at break of 50 to 800% when cured is applied thereon using a trowel, spatula, or similar construction machine to form a primer layer. and a layer of polyurethane or polyurea with a thickness of 0.8 to 4 mm, and the transmitted light image clarity C value measured in accordance with JIS H8686-2 under the condition of an optical comb width of 2 mm is 50% or more. A method for constructing a concrete surface structure has been proposed, which is characterized by forming a concrete surface structure.
Furthermore, Patent Document 2 below describes that an epoxy resin primer having a viscosity in the range of 20 to 5000 mPa·s and a tensile strength of 1 N/mm ² or more when cured is applied to the surface layer of a concrete structure, and then, Spray a polyurethane or polyurea curable composition having a tensile strength of 7 N/mm ² or more and a tensile elongation at break of 50 to 800% when cured to form a polyurethane or polyurea layer with a thickness of 0.8 to 4 mm. A method for constructing a concrete surface structure featuring the following has been proposed.

Japanese Patent Application Publication No. 2005-213844 Japanese Patent Application Publication No. 2005-213842

According to the method for constructing a concrete surface structure described in Patent Document 1, it is possible to maintain transparency over a long period of time, and form a coating film that is easy to visually diagnose. As there is no need to cut or paste the sheet, it has the advantage of being easy to install. However, since it is necessary to perform construction with a trowel, spatula, or similar machine, although it can be used suitably for partial repair of defective parts, it is not efficient when performing construction over a wide area of a structure. It wasn't.
On the other hand, in the method for constructing a concrete surface structure described in Patent Document 2, the concrete structure can be efficiently coated over a wide area by spray coating, but since the coating material used for spray coating has a short curing time, There was a problem in that the coating film hardened before the air bubbles drawn in during discharge were released, and the coating film became opaque due to the air bubbles.

In addition, most of the surfaces of concrete structures that need to be protected are vertical surfaces or ceiling surfaces, and when coating material is applied on-site, dripping occurs, resulting in insufficient coating material being applied to the concrete surface. If it is difficult to apply the liquid, or if the area where the liquid drips hardens as it is, the thickness of the coating material cannot be maintained uniformly, and the coating material may become icicle-like, especially if there is significant dripping on the ceiling. In addition to the appearance problem, there was also the problem that it was difficult to see the concrete surface through the covering material.

Therefore, an object of the present invention is to uniformly and easily form a protective coating on vertical surfaces and ceiling surfaces by spray painting, which can prevent fragments from falling off due to structural defects and which can maintain transparency for a long period of time. The purpose of this invention is to provide a possible protection method for structures.

According to the present invention, a combination of a liquid A containing a urethane prepolymer having two or more isocyanate groups as a main component and a liquid B containing a curing agent having two or more hydroxyl groups and/or amino groups as a main component is combined. A method for protecting a structure by spraying a coating material consisting of a two-liquid collision type spray onto the surface of the structure, the liquid pressure of each of the A liquid and the B liquid when the two liquids are mixed and collided. is 500 psi (3.45 MPa) or more and 1200 psi (8.27 MPa) or less, and the operation of spraying the coating material on one location on the construction surface of the structure is performed in multiple spraying operations. , characterized in that the time interval (open time) during which no spraying is performed between each spraying operation is equal to or longer than the gel time of the coating material, and the coating is applied in an amount that ensures visibility of the construction surface. A method of protecting a structure is provided.

In the structure protection method of the present invention,
1. The viscosity of each of the A liquid and the B liquid when the two liquids are mixed and collided is adjusted to a range of 500 mPa·s or less,
2. Each of the A liquid and the B liquid does not contain a silane coupling agent or contains a silane coupling agent in an amount of less than 1% by weight;
3. The structure is a concrete structure, natural stone structure, masonry structure, metal structure or wooden structure;
4. Spraying the coating material directly onto the surface of the structure;
5. Coating the coating material with a thickness of 0.5 to 3 mm,
6. The hiding rate of the coating formed by the coating material at a thickness of 1 mm is less than 30%;
7. The B liquid contains an aromatic amine as a component, and the coating material contains 0.1% by weight or more of an antioxidant;
8. Either the A liquid or the B liquid contains an organic acid as a curing accelerator;
is a preferred embodiment.

According to the method for protecting a structure of the present invention, a liquid A whose main component is a urethane prepolymer having two or more isocyanate groups, and a liquid B whose main component is a curing agent having two or more hydroxyl groups and/or amino groups. By discharging the coating made by combining the two-component liquid at a predetermined discharge pressure using a two-component mixed impingement spray, it is possible to form a coating with excellent transparency on the surface of a structure without entrapping air bubbles. . It also has excellent coating properties and can efficiently form a smooth and uniformly thick coating.
According to the structure protection method of the present invention, it is possible to protect the surface of structures such as concrete structures, natural stone structures, masonry structures, metal structures, wooden structures, etc., and the structure has excellent transparency. Therefore, the surface of the structure can be visually observed through the coating for a long period of time, and even if a defect occurs in the structure, surface peeling can be effectively prevented.
Furthermore, according to the structure protection method of the present invention, the operation (spray operation) of spraying the coating material on the vertical surface or ceiling surface of the structure can be repeated multiple times at one location on the construction surface. In addition to spraying separately, the time interval (open time) during which no spraying is performed between each spraying operation is at least longer than the gel time of the coating material, and the amount of coating material is such that it does not impede the visibility of the construction surface (substrate). By applying this, the coating material can be sprayed on vertical surfaces and ceiling surfaces without causing any drips that would impede the visibility of the base.

(Coating material)
In the method for protecting a structure of the present invention, a liquid A whose main component is a urethane prepolymer having two or more isocyanate groups, and a liquid B whose main component is a curing agent having two or more hydroxyl groups and/or amino groups are used. A coating material made of polyurea or polyurethane is used.
The urethane prepolymer constituting Liquid A is prepared by reacting a polyisocyanate compound having two or more isocyanate groups in one molecule with a compound having two or more active hydrogens in one molecule that react with the isocyanate groups. Obtainable. Particularly suitable as the active hydrogen compound are urethane prepolymers formed by combining one or more polyol compounds having two or more alcoholic hydroxyl groups in one molecule, such as polyether polyols, polyester polyols, or other polyols. It is.

The polyisocyanate compounds that can be used to prepare the urethane prepolymer include aliphatic polyisocyanates such as hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine methyl ester diisocyanate; Alicyclic polyisocyanates such as 1,4-cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated tolylene diisocyanate, norbornene diisocyanate, hydrogenated m-xylylene diisocyanate, hydrogenated p-xylylene diisocyanate, etc. Class; p-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene diisocyanate, m-xyly Aromatic polyisocyanates such as aromatic diisocyanates such as diisocyanate and toridine diisocyanate; examples include those obtained by modifying each of the above polyisocyanates with carbodiimide or isocyanurate, and these may be used alone or in a mixture of two or more. I can do it. Among these, aliphatic or alicyclic polyisocyanates are preferably used from the viewpoint of transparency and color fastness.

Specific examples of polyether polyols that can be used to prepare urethane prepolymers include polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene oxypropylene glycol, polyoxytetramethylene glycol, polyoxyhexamethylene glycol, etc. , low molecular weight active hydrogen compounds having two or more active hydrogens, such as bisphenol A, ethylene glycol, propylene glycol, butylene glycol, diols such as 1,6-hexanediol; glycerin, trimethylolpropane, 1,2,6- Triols such as hexanetriol; random polymers obtained by ring-opening polymerization of propylene oxide and/or ethylene oxide in the presence of one or more amines such as ammonia, methylamine, ethylamine, propylamine, butylamine, etc. Polymers may be mentioned.

Polyester polyols that can be used to prepare urethane prepolymers include, for example, polymers obtained by dehydration condensation of polybasic acids and polyhydric alcohols; condensates of hydroxycarboxylic acids and polyhydric alcohols; ring-opening polymers of lactones, etc. is preferably used. Examples of the polybasic acids include adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, succinic acid, dimerized linoleic acid, maleic acid, and the like. Examples of polyhydric alcohols include bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, Diols such as pentyl glycol; triols such as glycerin, 1,1,1-trimethylolpropane, and 1,2,6-hexanetriol may be used. More specifically, polyethylene adipate, polytetramethylene adipate, polyhexamethylene adipate, polytetramethylene sebacate, poly(diethylene glycol adipate), poly(hexamethylene glycol-1,6-carbonate) whose both ends are diol components ), polycaprolactone, and the like.

Other polyols that can be used to prepare urethane prepolymers include, for example, acrylic polyols, hydrogenated polybutadiene polyols, castor oil derivatives, tall oil derivatives, polymer polyols, polycarbonate polyols, as well as ethylene glycol, diethylene glycol, Low-molecular polyols such as propylene glycol, dipropylene glycol, butanediol, pentanediol, and hexanediol are also preferably used.

These polyol compounds preferably have a number average molecular weight of 100 to 10,000, particularly 300 to 5,000, and can be used alone or in combination of two or more as desired.

The urethane prepolymer has a ratio of more than 1 mole of isocyanate groups contained in the polyisocyanate compound to 1 mole of hydroxyl groups contained in the polyol compound, that is, a chemical equivalent ratio (NCO/OH) of more than 1. The blend can be obtained by reacting a polyol compound and a polyisocyanate compound by heating if necessary. Such a urethane prepolymer usually has isocyanate groups at both ends of its molecule. As a urethane prepolymer, a polyol compound and a polyisocyanate compound are reacted at a chemical equivalent ratio (NCO/OH) of hydroxyl groups contained in the polyol compound and isocyanate groups contained in the polyisocyanate compound at a ratio of 1.6 to 20. In terms of workability, physical properties of the cured product, etc., those that exhibit a liquid state at 23° C. are more preferable.

The coating material used in the structure protection method of the present invention includes a liquid A containing the above-mentioned urethane prepolymer as a main component, a liquid B containing a curing agent having two or more hydroxyl groups and/or amino groups as a main component, It can be formed by curing a curable composition containing other additives as required.
The compound having two or more hydroxyl groups and/or amino groups that cures the urethane prepolymer is preferably a compound having a molecular weight of 18 to 10,000, preferably 30 to 5,000, such as ethylene glycol and 1,2-propylene glycol. , 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexylene glycol, glycerin, trimethylolpropane, 1,2,4-trihydroxybutane, 1,2,3,4-tetrahydroxybutane , 1,2,6-trihydroxyhexane, 1,1,1-trimethylolethane, pentaerythritol, polycaprolactone, fructose, xylitol, arabitol, sorbitol, and mannitol; polyhydric alcohols such as ethanolamine; Alcohol; ammonia, hydrazine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, m-phenylenediamine, 2,4-toluenediamine, 2,6-toluenediamine, diethyltoluenediamine, dimethylthiotoluene In the preparation of low-molecular polyamine compounds such as diamine, N,N'-bis(sec-butylamino)diphenylmethane, 3,3'-dichloro-4,4'-diamino-diphenylmethane, and the above-mentioned urethane prepolymers. Polyols such as polyether polyols and polyester polyols that can be used in Examples include polyether polyamines such as polyoxyethylene diamine, polyoxypropylene diamine, and polyoxybutylene diamine obtained by substituting with . Among these curing agents, it is preferable to use polyether polyols or polyether polyamines, but it is also possible to use polyether polyols or polyether polyamines in combination with one or more other low-molecular polyols or low-molecular polyamines. can.
As these curing agents, the ratio of active hydrogen in the low molecular compound is about 0.8 mol or more, preferably about 0.95 to 1.2 mol, per 1 mol of isocyanate groups contained in the urethane prepolymer. A hardening agent is added.

In addition to the urethane prepolymer and curing agent, additives such as plasticizers, solvents, surfactants, curing accelerating catalysts, anti-aging agents, and dyes are added to the A and B solutions according to conventionally known formulations, as necessary. can do.

Plasticizers include carboxylic acid esters such as phthalic acid esters, adipic acid esters, sebacic acid esters, azelaic acid esters, and trimellitic acid esters, as well as phosphoric acid esters, normal paraffins, chlorinated paraffins, alkylbenzenes, and various other liquid components. These may be used alone or in combination of two or more.

A solvent is used if necessary to adjust the viscosity of the curable resin composition. As the solvent, an organic solvent that does not show reactivity with the A liquid and the B liquid can be suitably used. Examples include, but are not limited to, aromatic hydrocarbon solvents such as toluene and xylene, ester solvents such as ethyl acetate, n-butyl acetate, and n-amyl acetate, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, methylcyclohexane, and ethyl acetate. Alicyclic hydrocarbon solvents such as cyclohexane, petroleum hydrocarbon solvents such as mineral spirits, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate Examples include diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, glycol ether ester solvents, and two or more of these solvents may be used in combination.

As the surfactant, various surfactants may be added alone or in combination of two or more depending on the properties of the antifoaming agent, emulsifier, viscosity improver, etc.

Examples of curing accelerating catalysts for accelerating the reaction between the urethane prepolymer and the curing agent include N-alkylbenzylamine, N-alkyl aliphatic polyamine, triethylenediamine, N-alkylpiperazine, N-alkylmorpholine, dimorpholino diethyl ether, Organometallic compounds such as tin octenoate, dibutyltin dilaurate, organic acid lead salts, organic acid zirconium salts, or organic acid bismuth salts, aromatic carboxylic acids such as benzoic acid, phthalic acid, o-chlorobenzoic acid, etc. - Organic acids such as aliphatic carboxylic acids such as ethylhexanoic acid, octylic acid, stearic acid, oleic acid, and linoleic acid can be mentioned, and 2-ethylhexanoic acid is preferred because of its excellent compatibility with polyols. These can be used alone or in a mixture of two or more.
Note that the above-mentioned curing accelerating catalyst can also be used when preparing a urethane prepolymer, and can be used to efficiently produce a urethane prepolymer.

Anti-aging agents are used to protect the above-mentioned coating materials from light, oxygen, heat, etc. Anti-aging agents commonly used include ultraviolet absorbers, light stabilizers, antioxidants, etc. Examples of ultraviolet absorbers and light stabilizers include benzotriazole-based, benzophenone-based, benzoate-based, cyanoacrylate-based, hindered amine-based, and nickel-based. Examples of antioxidants include hindered phenol, amine, sulfur, and phosphorus antioxidants. These can be used alone or in combination of two or more. It is preferable to use a combination of an ultraviolet absorber or a light stabilizer and an antioxidant because it can prevent discoloration, cloudiness, and deterioration of surface gloss over a long period of time. In particular, when aromatic amines such as diethyltoluene diamine are used in the above B liquid, a remarkable effect is observed when an antioxidant such as a hindered phenol antioxidant is used in combination as an anti-aging agent. A sufficient effect can be obtained even if the amount is 0.1% by weight or more based on the coating material.

Furthermore, since the coating material used in the present invention has excellent adhesion to the structure, it is not necessary to contain a silane coupling agent, but the amount of the silane coupling agent contained in the curable composition constituting the coating material is less than 1% by weight. may contain a silane coupling agent.
When the silane coupling agent is contained in the curable composition in an amount of less than 1% by weight, examples of the silane coupling agent include isocyanate group-containing silanes, amino group-containing silanes, mercapto group-containing silanes, and epoxy group-containing silanes. , vinyl type unsaturated group-containing silanes, and the like. When epoxy group-containing silanes are included, they are included in the A solution, and when amino group-containing silanes are included, they are included in the B solution.

(Primer layer)
In the structure protection method of the present invention, since the above-mentioned coating material has excellent adhesion to the structure, it is possible to directly spray it on the surface of the structure, but it is possible to spray it directly onto the surface of the structure. A coating material can also be applied to the surface of the object. By forming the primer layer on the surface of the structure, the primer penetrates into the surface layer of the structure, so it becomes possible to more firmly adhere the coating material to the structure.
As the primer, a transparent epoxy resin primer that has excellent adhesion to the film made of the above-mentioned coating material (polyurea or polyurethane) can be suitably used. As such an epoxy resin primer, those described in Japanese Unexamined Patent Application Publication No. 2008-75033 by the present applicant can be suitably used, and the primer can be formed by the method described in the publication. Furthermore, a transparent urethane resin primer can also be suitably used. These primers can contain a silane coupling agent depending on the purpose.
When the primer layer is formed on the surface of the structure, its thickness is preferably about 0.02 to 0.4 mm.

(Method of covering structures)
In the present invention, the above-mentioned liquid A is mainly composed of a urethane prepolymer having two or more isocyanate groups, and liquid B is mainly composed of a curing agent having two or more hydroxyl groups and/or amino groups. The surface of the structure is sprayed and coated using a liquid mixed impingement type spray, and in this case, the pressure of each of the liquid A and the liquid B when the two liquids are mixed and collided is 500 psi (3.45 MPa) or more and 1200 psi. (8.27 MPa) or less, preferably in the range of 500 psi (3.45 MPa) or more and 1050 psi (7.23 MPa) or less.
In other words, if the liquid pressure is lower than the above range, the coating properties will be poor and a uniform film cannot be formed, whereas if the liquid pressure is higher than the above range, air bubbles will be trapped. This results in a lack of transparency.

As the spray device used for spraying the coating material onto the structure, a spray device consisting of a pressure and temperature control measuring device, a spray gun equipped with a mix chamber, and a hot hose capable of heating can be used. In the present invention, it is important to use a two-component mixed impingement spray as the spray gun.
In this two-liquid mixing collision type spray, it is preferable to select a mix chamber suitable for mixing and colliding liquids A and B at the liquid pressure within the above range. In the present invention, the mix chamber manufactured by Graco is used, but is not limited to, No. 000 (orifice diameter 0.020 inch (0.508 mm) ), No. 00 (orifice diameter 0.029 inch (0.737 mm) ), and 01. A two-component mixing impingement type spray gun equipped with a mix chamber with a chamber size corresponding to No. 02 (0.042 inch (1.067 mm) ), No. 02 (0.052 inch (1.321 mm) ), etc. is suitable. can be used. In particular, it is preferable to use a mix chamber equivalent to No. 01 (0.042 inch (1.067 mm) ) for low discharge or equivalent to No. 00 (0.029 inch (0.737 mm) ) with an even smaller orifice diameter. It is.

In the present invention, when liquids A and B are mixed and collided, specifically when liquids A and B are introduced into the mix chamber, it is preferable that the viscosity of each is 500 mPa·s or less. and more preferably 350 mPa·s or less. If the viscosity is higher than the above range, the coating properties will be poor and it will be difficult to form a uniform film. Adjusting the viscosity of liquids A and B to be lower will reduce the difference in viscosity between the two liquids, making mixing easier and improving the physical properties of the film.
In addition, liquid A and liquid B have a dry-to-touch time of 10 seconds to 60 minutes according to the evaluation method described in JIS K-5600-1-1 after mixing and colliding liquids A and B. Preferably, it is prepared so that

In the present invention, in order to form a uniform coating with excellent transparency, in addition to the liquid pressure when liquids A and B are mixed and collided, and the viscosity of liquids A and B, the discharge direction (upward, downward, It is desirable to adjust various conditions as appropriate, such as the spray distance (horizontal direction) and the distance between the discharge port of the two-component mixed impingement spray and the surface of the structure. For example, when the spray discharge direction is horizontal, the spray distance is preferably in the range of 20 to 100 cm, more preferably 30 to 80 cm. If the thickness is less than 20 cm, the spray discharged material will be concentrated locally, resulting in uneven thickness. If the thickness exceeds 100 cm, materials that harden quickly may generate a large amount of mist or locally harden into particles. This may inhibit the formation of a film and cause the physical properties of the coating material to deteriorate.

In the structure protection method of the present invention, as described above, a coating material consisting of liquids A and B is applied directly to the surface of the structure or, if the primer layer described above is formed, on the primer layer. is applied using a two-component mixed impingement spray.
Preferably, the coating has a thickness of 0.5 to 3 mm, particularly 0.7 to 2.5 mm. If the thickness of the coating is thinner than the above range, it may not be able to function sufficiently as a protective coating, while if it is thicker than the above range, the transparency and economic efficiency will be lowered.
When spraying coating material, the amount of coating applied in one round trip of the spray gun varies depending on the liquid pressure, liquid viscosity, orifice diameter of the mix chamber, etc., so check the coating amount while checking the condition of the sprayed coating material. It is desirable to adjust the Particularly with slow-curing materials, this is advantageous in that air bubbles caught up during spraying can be easily removed, but if a large amount is sprayed at once, dripping may occur and the desired film thickness may not be obtained. However, in the structure protection method of the present invention, the open time between sprays is at least equal to or longer than the gel time of the coating material to be sprayed. It is possible to spray on vertical and ceiling surfaces without causing drips that would impede the visibility of the base.

The coating material formed by the method for protecting structures of the present invention has strength to prevent peeling and the like, and also has excellent transparency, with a hiding rate of less than 30% at a thickness of 1 mm. The hiding rate is determined by coating a 1 mm thick resin on a hiding rate test paper in accordance with the JIS K5600 4-1 B method, and calculating the tristimulus value Y of the coated film in the white area (Y _W ) and the black area (Y W ). _B ) It is possible to measure each and calculate the hiding rate Y _B /Y _W as a percentage.
In addition, the covering material formed by the structure protection method of the present invention can shorten the gel time without reducing the hiding rate, and can be coated with a liquid that inhibits the visibility of the base on vertical and ceiling surfaces. The coating material can be efficiently applied without causing dripping. Furthermore, even when exposed to ultraviolet rays, the reduction in hiding rate due to yellowing or reduction in surface gloss can be kept to a minimum.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Gel time]
A vertical wall surface is covered with a blue sheet, and after spraying the blue sheet continuously for 2 seconds from a distance of 60 cm at one point on the surface of the blue sheet, the time until the sprayed coating material stops dripping is measured.

[Tack free time]
Cover a horizontal floor surface with a blue sheet, and after spraying the material two times from a distance of 60 cm (equivalent to a spraying thickness of 0.3 mm) on one spot on the surface of the blue sheet, touch the surface of the sprayed covering material with your fingers. Measure the time until the tack disappears.

[Physical property measurement]
Spray on a horizontally placed polypropylene plate to a thickness of 2 mm. After 7 days, a No. 3 dumbbell specified in JIS K6251 is produced from the cured spray sheet by punching. On the 7th day of age, the tensile properties are measured using a testing machine in accordance with JIS K6251.

[Concealment rate]
The two liquids are mixed and collided against a horizontally placed polypropylene plate from above at a spray distance of 60 cm, and sprayed back and forth 1 to 4 times to produce four types of spray sheets with different thicknesses.
The thickness of each of the above four types of spray sheets is measured at three arbitrary points. Next, these four types of spray sheets were placed on a hiding rate test paper in accordance with JIS K5600 4-1 B method, and the tristimulus values Y were calculated for the white area (YW) and the black area (YW) at the three positions where the thickness was measured. YB) and obtain the hiding rate YB/YW as a percentage. Next, the concealment rate at a thickness of 1 mm is calculated from the quadratic polynomial approximation curve calculated from the thickness and the concealment rate.

[Hue]
Place a spray sheet on the white part of a hiding rate test paper compliant with JIS K5600 4-1 B method and measure the hue in the L*, a*, b* color system specified by JIS Z7829 using a color difference meter. .

[Glossiness]
Place the spray sheet on the white part of a hiding rate test paper in accordance with JIS K5600 4-1 B method, measure the gloss at 60° using a gloss meter, and record the maximum value.

[exterior]
Place a spray sheet on the white part of a concealment rate test paper in accordance with JIS K5600 4-1 B method, and visually evaluate transparency due to discoloration such as yellowing or bubbles.

[Push-out test]
A cylindrical groove with a diameter of 100 mm was formed at a depth of 50 mm in the center of a reinforced concrete U-shaped lid (400 x 600 x 60 mm) specified in JIS A5334 using a concrete core cutter. Next, the surface opposite to where the grooves were formed was thoroughly polished using a disc grinder, and then immersed in water at 20°C.
After 24 hours, the lid was taken out of the water, and the U-shaped lid was immersed in water for 30 mm from the bottom with the polished side facing up, and water droplets on the surface were removed with a cloth. After 3 minutes, the primer is applied with a roller in an amount of 200 g/m ² to a central area of 400 x 400 mm. After 4 hours, the U-shaped lid is removed from the water, placed horizontally, and application of the coating begins within 5 minutes. After the construction is completed, the U-shaped lid is again immersed in water for 30 mm from the bottom end.
After keeping it as it is for 7 days, place the U-shaped lid on the H steel with the coated side facing down so that the span is 400 mm, and test using a compression tester (Shimadzu Universal Testing Machine UH-I, manufactured by Shimadzu Corporation). Place the ball in the center of the inner core of the cylindrical groove and load it at a speed of 1 mm/min until the part of the lower part of the U-shaped lid core that the groove does not reach is destroyed. After loading and confirming that the initial stress peak has been exceeded and fracture occurs, load is applied at a rate of 5 mm/min, and the relationship between displacement and stress up to a displacement of 50 mm is recorded.
In the case of wet conditions, the test is carried out using the method described above, and in the case of dry conditions, a series of construction and drying operations are carried out with the U-shaped lid dry, and a punch-out test is carried out.
Also, as for the transparency of the covering material, carefully check visually whether the surface of the underlying concrete can be seen through the covering material from above the construction surface. ◎ indicates that the visibility of the base surface is excellent; ○ indicates that a 0.2 mm wide line drawn on the base (equivalent to the width of a line drawn with a ballpoint pen) is visible; ○ indicates that the line drawn on the base is visible. A case in which it is difficult to visually recognize a 0.2 mm wide line is marked as Δ, and a case in which it is difficult to visually recognize the surface of the base is marked as ×.

[Paintability test on vertical and ceiling surfaces]
Assemble a 2m high vertical plane and a 2m high ceiling frame using metal frame materials, and attach a reinforced concrete U-shaped lid (400 x 600 x 60 mm) to the frame with the construction side facing you. Fix it. In the case of a vertical surface, install the U-shaped lid at a height of at least 1 m or more so that the long side of the U-shaped lid is the bottom end.
Whether spraying on a vertical or horizontal surface, spray perpendicular to the construction surface of the U-shaped lid. After construction has been carried out and the covering material has hardened, remove the U-shaped lid from the frame, and in the case of a vertical surface, measure the length of the liquid dripping downward from the bottom end surface. In the case of a ceiling surface, measure the length of the liquid dripping perpendicularly from the U-shaped lid surface. Record the maximum length of the drip unless there is an abnormally long drip. If there is little dripping, place a board perpendicular to the dripping direction, check to see if there is a gap from the construction surface, and measure the gap. In addition, the thickness of the coating film is measured using a penetrating film thickness meter.
Particularly in areas with large drips on vertical surfaces, the same phenomenon as spraying a thick coating occurs, causing the coating to become cloudy and lose its transparency, making it difficult to see the underlying concrete surface through the coating. becomes. Therefore, the condition of the surface of the covering material and the transparency of the covering material should be carefully checked with the naked eye to see if the surface of the base concrete can be seen through the covering material from above the construction surface.
Regarding the condition of the surface of the coating material, if it is smooth or almost smooth, check 〇, if there is uneven thickness or unevenness in even a part of the coating material, check △, if there are icicle-like drips. is ×. Regarding the visibility of the surface of the base concrete through the covering material from above the construction surface, ◎ indicates that the visibility of the base surface is excellent, and a 0.2 mm wide line drawn on the base (drawn with a ballpoint pen) 〇: when it is difficult to see the 0.2 mm wide line drawn on the base (corresponding to the width of the line); △: when it is difficult to see the surface of the base Let be ×.

[Weather resistance test]
In the weather resistance test, accelerated exposure was performed for 1000 hours using a sunshine weather meter specified in JIS A1415 under conditions of 18 minutes of rain in a 2-hour irradiation cycle.

(Preparation of epoxy resin primer)
An epoxy resin primer was prepared by the following method.
100 parts by weight of liquid bisphenol F type epoxy resin (trade name: ADEKA RIN R4901, manufactured by Asahi Denka Kogyo Co., Ltd.) and 0.5 parts by weight of 3-glycidyloxypropyltrimethoxysilane were mixed, and the mixture was sufficiently stirred with a stirrer to make it uniform. , was used as the main ingredient of the primer.
In addition, a liquid amine curing agent (trade name: Daitoclar I-5476, manufactured by Daito Sangyo Co., Ltd.) was used as a curing agent for the primer.

(Preparation of urethane resin primer)
A urethane resin primer was prepared by the following method.
Norbornene diisocyanate (trade name: Cosmonate NBDI, manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd.) 40.0 parts by weight and polyoxypropylene triol with a number average molecular weight of 320 (trade name: Actocol G-530, manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd.) 30 0 parts by weight and 30.0 parts by weight of polyoxypropylene triol (trade name: MN-1500, manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd.) having a number average molecular weight of 1500 were reacted at 100°C for 6 hours, and after cooling to 40°C. , 20.0 parts by weight of hexamethylene diisocyanate nurate (trade name: Coronate HX), and 1.0 parts by weight of 3-glycidyloxypropyltrimethoxysilane (trade name: SH-6040, manufactured by Dow Corning Toray) were added. 135 parts by weight of ethyl acetate, 135 parts by weight of methylcyclohexane, and 0.4 parts by weight of dibutyltin laurate (trade name: Stan BL, manufactured by Sankyoki Gosei Co., Ltd.) as a moisture curing accelerating catalyst were mixed. A urethane resin primer having a solid content of 30% by weight and an NCO content of 3.0% by weight was obtained.

(Preparation of A1 liquid)
A1 solution of polyurea resin was prepared by the following method.
Norbornene diisocyanate (trade name: Cosmonate NBDI, manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd.) 48.0 parts by weight and polyoxypropylene glycol with a number average molecular weight of 2000 (trade name: Actocol D-2000, manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd.) 52 0 parts by weight was reacted at 100° C. for 4 hours to obtain liquid A1 having an NCO group content of 20% by weight.

(Preparation of A2 liquid)
A2 liquid of polyurea resin was prepared by the following method.
Norbornene diisocyanate (trade name: Cosmonate NBDI, manufactured by Mitsui Chemicals SKC Polyurethane) 38.0 parts by weight and 4,4'-diphenylmethane diisocyanate (trade name: Cosmonate PH, manufactured by Mitsui Chemicals SKC Polyurethane) 12.0 parts by weight and 50.0 parts by weight of polyoxypropylene glycol (trade name: Actocol D-2000, manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd.) with a number average molecular weight of 2000 were reacted at 90°C for 4 hours to form a polyoxypropylene glycol with an NCO group content of 20% by weight. A2 liquid was obtained.

(Preparation of B1 liquid)
A B1 solution of polyurea resin was prepared in the following manner.
77.0 parts by weight of polyether diamine with a number average molecular weight of 2000 (trade name: Jeffamine D-2000, manufactured by Huntsman), 22.0 parts by weight of diethyltoluenediamine (trade name: Ettacure 100, manufactured by Albemarle), anti-aging 1.0 parts by weight of a three-type mixed liquid stabilizer (trade name: Tinuvin B75, manufactured by BASF) was mixed as an agent to obtain B1 liquid.
Tinuvin B75 contains 40% ultraviolet absorber (trade name: Tinuvin 571, manufactured by BASF), 40% hindered amine light stabilizer (trade name: Tinuvin 765, manufactured by BASF), and 40% hindered phenol antioxidant (trade name: Tinuvin 765, manufactured by BASF). Product name: Irganox 1135 (manufactured by BASF) is a liquid stabilizer containing 20% of three components; in this case, 0.4 parts by weight of the ultraviolet absorber Tinuvin 571 and 0 parts of the hindered amine light stabilizer Tinuvin 765. This is equivalent to adding 0.4 parts by weight and 0.2 parts by weight of the hindered phenolic antioxidant Irganox 1135, respectively.

(Preparation of B2 liquid)
A B2 solution of polyurea resin was prepared in the following manner.
76.6 parts by weight of polyether diamine with a number average molecular weight of 2000 (trade name: Jeffamine D-2000, manufactured by Huntsman), 21.9 parts by weight of diethyltoluenediamine (trade name: Ettacure 100, manufactured by Albemarle), anti-aging As an agent, 1.0 parts by weight of a three-type mixed liquid stabilizer (trade name: Tinuvin B75, manufactured by BASF), as a curing accelerator, 2-ethylhexanoic acid (trade name: octylic acid, manufactured by KH Neochem), which is an organic acid. )0.5 part by weight was added and mixed to obtain liquid B2.

(Preparation of B3 liquid)
A B3 solution of polyurea resin was prepared in the following manner.
76.2 parts by weight of polyether diamine with a number average molecular weight of 2000 (trade name: Jeffamine D-2000, manufactured by Huntsman), 21.8 parts by weight of diethyltoluenediamine (trade name: Ettacure 100, manufactured by Albemarle), anti-aging As an agent, 1.0 parts by weight of a three-type mixed liquid stabilizer (trade name: Tinuvin B75, manufactured by BASF), as a curing accelerator, 2-ethylhexanoic acid (trade name: octylic acid, manufactured by KH Neochem), which is an organic acid. ) were mixed to obtain Liquid B3.

(Preparation of B4 liquid)
B4 solution of polyurea resin was prepared by the following method.
73.8 parts by weight of polyether diamine with a number average molecular weight of 2000 (trade name: Jeffamine D-2000, manufactured by Huntsman), 21.1 parts by weight of diethyltoluenediamine (trade name: Ettacure 100, manufactured by Albemarle), anti-aging As an agent, 1.0 parts by weight of a three-type mixed liquid stabilizer (trade name: Tinuvin B75, manufactured by BASF), as a curing accelerator, 2-ethylhexanoic acid (trade name: octylic acid, manufactured by KH Neochem), which is an organic acid. ) 4.0 parts by weight were mixed to obtain liquid B4.

(Preparation of B5 solution)
A B5 solution of polyurea resin was prepared in the following manner.
76.5 parts by weight of polyether diamine with a number average molecular weight of 2000 (trade name: Jeffamine D-2000, manufactured by Huntsman), 21.1 parts by weight of diethyltoluenediamine (trade name: Ettacure 100, manufactured by Albemarle), anti-aging As an agent, 1.0 parts by weight of a three-part mixed liquid stabilizer (trade name: Tinuvin B75, manufactured by BASF), as a curing accelerator, a metal catalyst dibutyltin dilaurate (trade name: Stan BL, Sankyoki Gosei Co., Ltd.) 0.5 part by weight (manufactured by Mimaki Co., Ltd.) was mixed to obtain liquid B5.

(Preparation of B6 liquid)
A B6 solution of polyurea resin was prepared in the following manner.
67.0 parts by weight of polyether diamine with a number average molecular weight of 2000 (trade name: Jeffamine D-2000, manufactured by Huntsman), polyether triamine with a number average molecular weight of 5000 (trade name: Jeffamine T-5000, manufactured by Huntsman) 10.0 parts by weight, 22.0 parts by weight of diethyltoluenediamine (trade name: Etacure 100, manufactured by Albemarle), 1.0 parts of a liquid stabilizer mixed with three types as an anti-aging agent (trade name: Tinuvin B75, manufactured by BASF) Parts by weight were mixed to obtain liquid B6.

(Preparation of B7 liquid)
A B7 solution of polyurea resin was prepared in the following manner.
77.4 parts by weight of polyether diamine with a number average molecular weight of 2000 (trade name: Jeffamine D-2000, manufactured by Huntsman), 22.1 parts by weight of diethyltoluenediamine (trade name: Ettacure 100, manufactured by Albemarle), anti-aging As an agent, 0.5 parts by weight of a three-type mixed liquid stabilizer (trade name: Tinuvin B75, manufactured by BASF) was mixed to obtain B7 liquid.
In this case, 0.2 parts by weight of the ultraviolet absorber Tinuvin 571, 0.2 parts by weight of the hindered amine light stabilizer Tinuvin 765, and 0.1 parts by weight of the hindered phenol antioxidant Irganox 1135 were added. It is equivalent to what you did.

(Preparation of B8 liquid)
A B8 solution of polyurea resin was prepared in the following manner.
76.2 parts by weight of polyether diamine with a number average molecular weight of 2000 (trade name: Jeffamine D-2000, manufactured by Huntsman), 21.8 parts by weight of diethyltoluenediamine (trade name: Ettacure 100, manufactured by Albemarle), anti-aging As an agent, 2.0 parts by weight of a three-part mixed liquid stabilizer (trade name: Tinuvin B75, manufactured by BASF) was mixed to obtain B8 liquid.
In this case, 0.8 parts by weight of the ultraviolet absorber Tinuvin 571, 0.8 parts by weight of the hindered amine light stabilizer Tinuvin 765, and 0.4 parts by weight of the hindered phenol antioxidant Irganox 1135 were added. It is equivalent to what you did.

(Preparation of B9 liquid)
A B9 solution of polyurea resin was prepared in the following manner.
76.2 parts by weight of polyether diamine with a number average molecular weight of 2000 (trade name: Jeffamine D-2000, manufactured by Huntsman), 21.8 parts by weight of diethyltoluenediamine (trade name: Ettacure 100, manufactured by Albemarle), anti-aging As an agent, 1.0 parts by weight of an ultraviolet absorber (trade name: Tinuvin 571, manufactured by BASF) and 1.0 parts by weight of a hindered amine light stabilizer (trade name: Tinuvin 765, manufactured by BASF) were mixed, and B9 liquid was prepared. I got it.

(Example 1)
The above polyurea resin liquids A1 and B1 were used as liquids A and B of the polyurea resin.
As a two-component impingement mixing type sprayer, Graco's spray device H-40 is used with Glass Craft's Problurr gun (using the same company's mix chamber No. 01 with an orifice diameter of 0.042 inch (1.067 mm) ). The two liquids A and B were collided and mixed and sprayed onto a horizontally placed polypropylene plate from above at a spray distance of 60 cm in an environment of 23°C. When spraying, shake the gun back and forth once from side to side to spray uniformly, wait a while, repeat the spray again, and spray back and forth multiple times to create sprays with different thicknesses. A sheet was produced. When the two liquids are mixed and collided, the pressure of liquid A and liquid B was set to 1000 psi (6.89 MPa) , and the viscosity of liquid A and liquid B was set to 75 mPa・s, respectively. Adjusted by heating. During spraying, the gel time of the coating at room temperature was 90 seconds, and the tack-free time was 900 seconds. Further, the spray sheet had a tensile strength of 19.0 N/mm ² , an elongation of 500%, and a hiding rate of 19%. Visual transparency was good and no yellowing was observed.
Under the above spraying conditions, a 1.5 mm thick covering material was sprayed under wet conditions and a punch-out test was conducted. Before spraying, as a primer, 100.5 parts by weight of the main ingredient of the epoxy resin primer and 50 parts by weight of a curing agent were uniformly stirred, and then 0.2 kg/m ² of the primer was applied to the U-shaped lid using a roller. Spraying was carried out 2 hours after the primer was applied. As a result of a punch-out test under wet conditions, the maximum load was 2.7 kN at a displacement of 50 mm. The transparency of the coating material was also sufficient, and the underlying concrete surface could be clearly seen from above the coating material on the construction surface.

(Example 2)
A punch-out test was conducted under the same conditions as in Example 1, changing the wet condition to a dry condition, and as a result, the maximum displacement was 50 mm and the maximum load was 2.7 kN. The transparency of the coating material was also sufficient, and the underlying concrete surface could be clearly seen from above the coating material on the construction surface.

(Example 3)
Under the same conditions as in Example 1, a 2.0 mm thick covering material was sprayed and a push-out test was performed, with the result that the displacement was 50 mm and the maximum load was 3.3 kN. Furthermore, although the transparency of the covering material was slightly lower than that of Example 2, it was possible to confirm the underlying concrete surface from above the covering material on the construction surface.

(Example 4)
A paintability test on a vertical surface was conducted under the same conditions as in Example 1. At the time of spraying, the gun was swung from side to side and reciprocated once to spray uniformly, and after a while, spraying was repeated in the same manner, for a total of 5 sprays. The interval time between spraying was 90 seconds, and the total time of the four intervals was 360 seconds. As a result, the thickness of the covering material was 1.4 mm, the surface of the covering material was finished almost flat, and the concrete underlying the construction surface was visible through the covering material, but icicle-like drips occurred from the bottom edge. However, the maximum length of the liquid drip was 20 mm.

(Example 5)
Under the same conditions as in Example 4, the spraying target was changed from the vertical surface to the ceiling surface, the interval was increased from 90 seconds to 120 seconds, and spraying was performed a total of 5 times. The total time of the four intervals was 480 seconds. As a result, the thickness of the covering material was 1.6 mm, the covering material was finished almost flat, and the underlying concrete on the construction surface could be visually confirmed well. Almost no dripping was observed, and the measured length was less than 1 mm.

(Reference example 1)
Under the same conditions as in Example 5, the number of sprays was increased from 5 to 7, with the interval kept at 120 seconds, for a total of 7 sprays. The total time of the six intervals was 720 seconds. As a result, icicle-like drips occurred over the entire surface, and the maximum length of the drips was 15 mm. The area where the liquid dripped was cloudy, making it difficult to visually confirm the condition of the underlying concrete surface. The thickness of the coating material was measured by looking for a flat part and found to be 2.2 mm.

(Example 6)
Spraying was performed a total of 7 times under the same conditions as in Reference Example 1, with the interval extended from 120 seconds to 180 seconds. The total time of the six intervals was 1080 seconds. As a result, the thickness of the covering material was 2.1 mm, the surface of the covering material was finished almost flat, and it was possible to visually confirm the underlying concrete on the construction surface. Almost no dripping was observed, and the measured length was less than 1 mm.

(Example 7)
A test was conducted under the same conditions as in Example 1, except that the B solution of the polyurea resin was replaced with a B2 solution containing 0.5 parts by weight of 2-ethylhexanoic acid, an organic acid, as a curing accelerator. The coating material essentially contains 0.25% by weight of 2-ethylhexanoic acid. As a result, during spraying, the gel time of the coating material at room temperature was 59 seconds, and the tack-free time was 610 seconds. Moreover, the tensile strength of the spray sheet was 18.8 N/mm ² , the elongation was 495%, and the hiding rate was 19%. Visually, the transparency was good and no yellowing was observed.
Furthermore, we conducted a paintability test on the ceiling surface. Spraying was performed a total of 7 times at intervals of 120 seconds under the same conditions as in Reference Example 1. As a result, the thickness of the covering material was 2.2 mm, and the surface of the covering material was slightly uneven, but the concrete underlying the construction surface could be visually confirmed. The maximum length of the drip was 2 mm.

(Example 8)
A test was conducted under the same conditions as in Example 1, except that the B solution of the polyurea resin was replaced with a B3 solution containing 1.0 parts by weight of 2-ethylhexanoic acid, an organic acid, as a curing accelerator. The coating material essentially contains 0.5% by weight of 2-ethylhexanoic acid. As a result, during spraying, the gel time of the coating material at room temperature was 42 seconds, and the tack-free time was 438 seconds. The spray sheet had a tensile strength of 18.5 N/mm ² , an elongation of 490%, and a hiding rate of 19%. Visually, the transparency was good and no yellowing was observed.
Furthermore, we conducted a paintability test on the ceiling surface. Spraying was performed a total of 7 times at intervals of 120 seconds under the same conditions as in Reference Example 1. As a result, the thickness of the covering material was 2.2 mm, the surface of the covering material was finished almost flat, and the underlying concrete on the construction surface could be visually confirmed well. Almost no dripping was observed, and the measured length was less than 1 mm.

(Example 9)
A test was conducted under the same conditions as in Example 1, except that the B solution of the polyurea resin was replaced with a B4 solution containing 4.0 parts by weight of 2-ethylhexanoic acid, an organic acid, as a curing accelerator. The coating material essentially contains 2.0% by weight of 2-ethylhexanoic acid. As a result, during spraying, the gel time of the coating material at room temperature was 15 seconds, and the tack-free time was 154 seconds. Further, the spray sheet had a tensile strength of 17.0 N/mm ² , an elongation of 455%, and a hiding rate of 20%. Visually, the transparency was good and no yellowing was observed.
Furthermore, we conducted a paintability test on the ceiling surface. Spraying was performed a total of 7 times under the same conditions as in Reference Example 1, with the interval shortened from 120 seconds to 30 seconds. The total time of the six intervals was 180 seconds. As a result, the thickness of the covering material was 2.0 mm, the surface of the covering material was finished almost flat, and the underlying concrete on the construction surface could be visually confirmed. Almost no dripping was observed, and the measured length was less than 1 mm.

(Example 10)
A test was conducted under the same conditions as in Example 1, except that the B solution of the polyurea resin was replaced with a B4 solution containing 0.5 parts by weight of dibutyltin dilaurate, a metal catalyst, as a curing accelerator. The coating material essentially contains 0.25% by weight of dibutyltin dilaurate. As a result, during spraying, the gel time of the coating material at room temperature was 11 seconds, and the tack-free time was 115 seconds. Further, the spray sheet had a tensile strength of 18.2 N/mm ² , an elongation of 470%, and a hiding rate of 27%. Research traces such as slight foaming were observed, and the visual transparency was slightly lower than in Example 9. Note that no yellowing was observed.
Furthermore, we conducted a paintability test on the ceiling surface. Spraying was performed a total of 7 times under the same conditions as in Example 9, with an interval of 30 seconds. As a result, the thickness of the coating material was 2.0 mm, the surface of the coating material was finished almost flat, almost no dripping was observed, and the measured length was less than 1 mm. However, the visibility of the base concrete on the construction surface was slightly lower than in Example 9, probably due to foaming during spraying.

(Example 11)
A test was conducted under the same conditions as in Example 1, changing the polyurea resin liquid A to a polyurea resin liquid A2 containing an aromatic isocyanate as a raw material, and changing the polyurea resin liquid B to a polyurea resin liquid B6. The coating material does not contain a curing accelerator. As a result, during spraying, the gel time of the coating material at room temperature was 27 seconds, and the tack-free time was 158 seconds. Further, the spray sheet had a tensile strength of 20.5 N/mm ² , an elongation of 465%, and a hiding rate of 22%. Visually, the transparency was good and no yellowing was observed.
Furthermore, we conducted a paintability test on the ceiling surface. Spraying was performed a total of 7 times under the same conditions as in Example 9, with an interval of 30 seconds. As a result, the thickness of the covering material was 2.0 mm, and the underlying concrete on the construction surface could also be visually confirmed. The surface of the coating material was finished almost flat, almost no dripping was observed, and the measured length was less than 1 mm.

(Comparative example 1)
Spraying was performed a total of 5 times under the same conditions as in Example 5, with the interval shortened from 120 seconds to 45 seconds. The total time of the four intervals was 180 seconds. As a result, icicle-like drips occurred over the entire surface, and the maximum length of the drips was 15 mm. The area where the liquid dripped was cloudy and it was difficult to visually confirm the base. The thickness of the coating material was measured by looking for a flat part and found to be 1.5 mm.

(Comparative example 2)
Under the same conditions as in Example 6, a static mixer was installed in place of the problur gun, the spray machine was adjusted so that the coating material was extruded into liquid form, and the resin liquid was applied to the ceiling surface using a rubber spatula. A paintability test was conducted on. As a result of trying to apply the coating material to the ceiling with the goal of making it 2mm thick, most of the applied resin solution dripped down, and a small amount of wavy resin solution adhered to the ceiling surface. However, it was difficult to apply.

(Example 12)
Under the same conditions as the punch-out test in Example 1, the urethane resin primer was applied with a roller in an amount of 0.2 kg/m ² instead of the epoxy resin primer, and after applying the primer, After a period of time, a coating film with a thickness of 1.5 mm was sprayed and a push-out test was performed under wet conditions. As a result, the displacement was 50 mm and the maximum load was 3.2 kN. The transparency of the covering material was also sufficient, and the surface of the underlying concrete could be clearly seen from above the covering material.

(Example 13)
Under the same conditions as Example 12, a coating material with a thickness of 1.5 mm was sprayed without applying a primer, and a punch-out test was conducted under wet conditions.The results were as follows: displacement of 50 mm, maximum load of 1.7 kN. there were. The transparency of the coating material was also sufficient, and the underlying concrete surface could be clearly seen from above the coating material on the construction surface. Compared to Example 12, there was almost no perceived effect on transparency due to the application of the primer.

(Example 14)
Using the spray sheet prepared in Example 1, an accelerated exposure test was conducted for 1000 hours using a sunshine weather meter. The spray sheet prepared in Example 1 contained 0.2% by weight of an ultraviolet absorber, 0.2% by weight of a hindered amine light stabilizer, and a hindered phenol antioxidant from the formulation of liquid B used. It is estimated to contain substantially 0.1% by weight of the agent.
The hue of the spray sheet before the exposure test had an L* value of 75.0, an a* value of -0.4, a b* value of 8.0, and a gloss level at 60° of 76. The hue of the spray sheet after the exposure test had an L* value of 70.2, an a* value of 0.5, a b* value of 11.9, and a gloss level at 60° of 39. Visually, slight yellowing was observed.

(Example 15)
Using the spray sheet prepared in Example 9, an accelerated exposure test for 1000 hours was conducted using a sunshine weather meter. The spray sheet prepared in Example 9 contained 2% by weight of an organic acid as a curing accelerator, 0.2% by weight of an ultraviolet absorber as an anti-aging agent, and a hindered amine, as estimated from the formulation of liquid B used. It substantially contains 0.2% by weight of a light stabilizer and 0.1% by weight of a hindered phenolic antioxidant.
The hue of the spray sheet before the exposure test had an L* value of 75.5, an a* value of -0.2, a b* value of 8.2, and a gloss level of 77 at 60°. The hue of the spray sheet after the exposure test had an L* value of 69.5, an a* value of 0.7, a b* value of 12.4, and a gloss level at 60° of 32. Visually, slight yellowing was observed.

(Comparative example 3)
A test was conducted under the same conditions as in Example 1, except that the polyurea resin liquid B was changed to liquid B7 containing 0.5 parts by weight of a three-part liquid stabilizer Tinuvin B75 as an anti-aging agent. The coating material substantially contains 0.1% by weight of an ultraviolet absorber, 0.1% by weight of a hindered amine light stabilizer, and 0.05% by weight of a hindered phenolic antioxidant as anti-aging agents. Become. As a result, during spraying, the gel time of the coating material at room temperature was 90 seconds, and the tack-free time was 900 seconds. Further, the spray sheet had a tensile strength of 19.1 N/mm ² , an elongation of 505%, and a hiding rate of 19%. Visually, the transparency was good and no yellowing was observed.
The hue of the spray sheet before the exposure test had an L* value of 76.0, an a* value of -0.1, a b* value of 8.5, and a gloss level of 76 at 60°. The hue of the spray sheet after the exposure test had an L* value of 56.2, an a* value of 1.2, a b* value of 20.8, and a gloss level of 0 at 60°. Visually, a strong yellow tinge was felt.

(Example 16)
A test was conducted under the same conditions as in Example 1, except that the polyurea resin solution B was replaced with a B8 solution containing 2.0 parts by weight of a three-part liquid stabilizer Tinuvin B75 as an anti-aging agent. The coating material substantially contains 0.4% by weight of an ultraviolet absorber, 0.4% by weight of a hindered amine light stabilizer, and 0.2% by weight of a hindered phenolic antioxidant as anti-aging agents. Become. As a result, during spraying, the gel time of the coating material at room temperature was 90 seconds, and the tack-free time was 900 seconds. Further, the spray sheet had a tensile strength of 19.0 N/mm ² , an elongation of 500%, and a hiding rate of 19%. Visually, the transparency was good and no yellowing was observed.
The hue of the spray sheet before the exposure test had an L* value of 76.0, an a* value of -0.2, a b* value of 8.0, and a gloss level at 60° of 76. The hue of the spray sheet after the exposure test had an L* value of 74.0, an a* value of 0.2, a b* value of 9.2, and a gloss level at 60° of 70. Visually, it was felt that there was little yellowing.

(Example 17)
Under the same conditions as in Example 1, the polyurea resin liquid B was changed to liquid B9 containing 0.5 parts by weight of the ultraviolet absorber Tinuvin 571 and 1.0 parts by weight of the hindered amine light stabilizer Tinuvin 765 as anti-aging agents. A test was conducted. The coating material substantially contains 0.5% by weight of an ultraviolet absorber and 0.5% by weight of a hindered amine light stabilizer as anti-aging agents. As a result, during spraying, the gel time of the coating material at room temperature was 90 seconds, and the tack-free time was 900 seconds. Further, the spray sheet had a tensile strength of 18.9 N/mm ² , an elongation of 495%, and a hiding rate of 19%. Visually, the transparency was good and no yellowing was observed.
The hue of the spray sheet before the exposure test had an L* value of 75.9, an a* value of -0.2, a b* value of 8.0, and a gloss level at 60° of 76. The hue of the spray sheet after the exposure test had an L* value of 61.8, an a* value of 1.0, a b* value of 16.4, and a gloss level at 60° of 8. Visually, it was felt that the yellowish tinge was a little strong.

(Example 18)
Using the spray sheet prepared in Example 11, an accelerated exposure test was conducted for 1000 hours using a sunshine weatherometer. In addition to using aromatic isocyanate as a raw material, the spray sheet prepared in Example 11 also contained 0.2% by weight of an ultraviolet absorber, 0.2% by weight of a hindered amine light stabilizer, and hindered phenol as anti-aging agents. It substantially contains 0.1% by weight of antioxidant.
The hue of the spray sheet before the exposure test had an L* value of 74.0, an a* value of -0.1, a b* value of 9.2, and a gloss level at 60° of 75. The hue of the spray sheet after the exposure test had an L* value of 63.1, an a* value of 1.0, a b* value of 15.3, and a gloss level of 23 at 60°. Visually, it was felt that the yellowish tinge was a little strong.

The test results of the punch-out test are summarized in Table 1.

As shown in Table 1, a coating material with excellent transparency and peeling prevention performance was obtained under the condition that the pressure of liquid A and liquid B was 1000 psi (6.89 MPa) when the two liquids were mixed and collided. Ta.

Table 2 summarizes the results of the paintability test on vertical surfaces and ceiling surfaces.

As shown in Table 2, it can be confirmed that by setting the open time to at least the gel time of the coating material, spraying can be applied to vertical surfaces and ceiling surfaces. The conditions differ depending on whether the construction surface is a vertical surface or a ceiling surface, but it is more preferable to make the open time 1.3 times or more the gel time, and even more preferably, the open time is at least twice the gel time. We were able to construct a covering material with little sagging and good surface condition and transparency.

The results of the weather resistance test are summarized in Table 3.

As shown in Table 3, the weather resistance of the coating material was significantly improved by adding a small amount of antioxidant, at least 0.1% by weight, in addition to the ultraviolet absorber and light stabilizer.

Claims (9)

A coating material consisting of a combination of a liquid A whose main component is a urethane prepolymer having two or more isocyanate groups and a liquid B whose main component is a curing agent having two or more hydroxyl groups and/or amino groups, A method for protecting a structure by spray coating the surface of the structure using a liquid mixed impingement spray, the method comprising:
The liquid pressure of each of the A liquid and the B liquid when the two liquids are mixed and collided is 500 psi (3.45 MPa) or more and 1200 psi (8.27 MPa) or less,
The operation of spraying the coating material on one place on the construction surface of the structure is divided into multiple spraying operations, and there is a time interval (open time) during which no spraying is performed between each spraying operation. ) is coated with an amount that exceeds the gel time of the coating material and ensures visibility of the construction surface without causing dripping . 2. The method for protecting a structure according to claim 1, wherein the viscosity of each of the liquid A and the liquid B when the two liquids are mixed and collided is adjusted to a range of 500 mPa·s or less. 3. The method for protecting a structure according to claim 1, wherein each of the A liquid and the B liquid does not contain a silane coupling agent or contains less than 1% by weight of a silane coupling agent. 4. The method for protecting a structure according to claim 1, wherein the structure is a concrete structure, a natural stone structure, a masonry structure, a metal structure, or a wooden structure. 5. The method for protecting a structure according to claim 1, wherein the coating material is sprayed directly onto the surface of the structure. The method for protecting a structure according to any one of claims 1 to 5, wherein the covering material is coated with a thickness of 0.5 to 3 mm. The method for protecting a structure according to any one of claims 1 to 6, wherein the coating formed by the coating material has a hiding rate of less than 30% at a thickness of 1 mm. The method for protecting a structure according to any one of claims 1 to 7, wherein the liquid B contains an aromatic amine as a component, and the coating material contains 0.1% by weight or more of an antioxidant. The method for protecting a structure according to claim 1, wherein either the A liquid or the B liquid contains an organic acid as a curing accelerator.