JP2021087917A - Structure protection method - Google Patents

Abstract

To provide a structure protection method which can prevent falling off of fragments due to a defective structure, and can uniformly and easily form a protective coating film capable of maintaining transparency over a long period of time by spray coating.SOLUTION: In the structure protection method for spray coating a structure surface with a coating material obtained by combining 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 using a two-liquid mixing collision type spray, a value of G calculated by the following expression: G=(P/η)1/2/D satisfies the condition of G≤123. In the expression, D is an orifice diameter (inch) of a mix chamber used in a two-liquid mixing collision type spray; P exhibits a pressure (psi) of the liquid A and the liquid B in two-liquid mixing collision, and when there is a difference in the value of the pressure between both of the liquids, it is a higher value; and η exhibits viscosity (mPa s) of the liquid A and the liquid B in the two-liquid mixing collision, and when there is a difference in the value of the viscosity between both of the liquids, it is a lower value.SELECTED DRAWING: None

Description

The present invention relates to a method for protecting a structure, and more specifically, a structure capable of protecting the surface of the structure, visually confirming when a defect or damage occurs, and preventing debris from peeling off. Regarding how to protect things.

In concrete structures, etc., some concrete members may peel off as debris due to defects during construction, damage due to earthquakes or collisions, neutralization, salt damage, chemical deterioration such as alkali-aggregate reaction, etc. .. In order to prevent such concrete pieces from peeling off, conventional methods such as covering the concrete surface with a metal such as an iron plate, and continuous fiber sheets such as glass cloth, synthetic resin fiber sheet, and carbon fiber sheet are used as synthetic resin materials. Alternatively, a method of attaching to the concrete surface using an inorganic material such as cement has been proposed and implemented.

In the peeling prevention system using fiber sheets, continuous fiber sheets such as glass cloth and vinylon are combined for reinforcement. Therefore, by making the synthetic resin that holds the fiber sheets transparent, concrete can be used even after layer formation. Although visual diagnosis, which is an important method for diagnosing the degree of deterioration, is possible, it is difficult to make the fiber sheet part transparent, and a grid-like opaque part remains in appearance, making visual diagnosis easy. There was a problem that it hindered the appearance and the finish was aesthetically unsightly.

In order to solve such a problem, in Patent Document 1 below, a transparent epoxy resin primer having a viscosity in the range of 20 to 5000 mPa · s and a tensile strength at the time of curing of 1 MPa or more is provided on the surface layer of a concrete structure. A curable composition of polyurethane or polyurea having a tensile strength of 5 MPa or more at the time of curing and a tensile elongation at break of 50 to 800% is applied thereto with a trowel, spatula or a similar construction machine, and a primer layer is applied. A laminated portion consisting of a layer of polyurethane or polyurea having a thickness of 0.8 to 4 mm and having a transmitted light image sharpness C value of 50% or more measured in accordance with JIS H8866-2 under the condition of an optical comb width of 2 mm. A method for constructing a concrete surface structure, which is characterized by forming a concrete surface structure, has been proposed.
Further, in Patent Document 2 below, 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 at the time of curing is applied to the surface layer of the concrete structure, and the surface layer thereof is coated with an epoxy resin primer. A curable composition of polyurethane or polyurea having a tensile strength of 7 N / mm ² or more at the time of curing and a tensile elongation at break of 50 to 800% is sprayed to form a polyurethane or polyurea layer having a thickness of 0.8 to 4 mm. A method for constructing a concrete surface structure characterized by the above has been proposed.

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

According to the method for constructing a concrete surface structure described in Patent Document 1, transparency can be maintained for a long period of time, a coating film can be formed for easy visual diagnosis, and a fiber sheet is used. As described above, since it is not necessary to cut or attach the sheet, there is an advantage that the construction is easy. However, since it is necessary to use a trowel, spatula, or a machine equivalent to this, even if it can be suitably used for partial repair of defective parts, it is efficient when it is applied to a wide range of structures. 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 the coating material used for spray coating has a short curing time. There is a problem that the coating film is cured before the air bubbles entrained at the time of discharge are removed, and the coating film becomes opaque due to the air bubbles.

Therefore, an object of the present invention is to provide a method for protecting a structure, which can prevent debris from peeling off due to defects in the structure and can uniformly and easily form a protective coating capable of maintaining transparency for a long period of time by spray coating. That is.

According to the present invention, 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 are combined. This is a method for protecting a structure in which the coating material is spray-coated on the surface of the structure using a two-component mixed collision type spray, and the value of G calculated by the following formula (1) is a condition of G ≦ 123. A method of protecting a structure is provided, which comprises satisfying.
G = (P / η) ^1/2 / D ... (1)
In the formula, D is the orifice diameter (inch) of the mix chamber used for the two-liquid mixed collision type spray, and P indicates the pressure (vis) of the A liquid and the B liquid at the time of the two-liquid mixed collision. If there is a difference in the pressure values of the liquids, it is the higher value, and η indicates the viscosities (mPa · s) of the liquids A and B when the two liquids are mixed and collided, and the values of the viscosities of both liquids. If there is a difference in, it is the lower value.

According to the method of protecting the structure of the present invention
1. 1. Each of the liquid A and the liquid B does not contain a silane coupling agent or is contained in an amount of less than 1% by weight.
2. The structure is a concrete structure, a natural stone structure, a masonry structure, a metal structure or a wooden structure.
3. 3. The coating material is directly spray-coated on the surface of the structure.
4. Covering the covering material with a thickness of 0.5 to 3 mm,
5. The concealment rate of the coating film formed by the covering material at a thickness of 1 mm is less than 30%.
Is a preferred embodiment.

According to the method for protecting a structure of the present invention, a liquid A containing a urethane prepolymer having two or more isocyanate groups as a main component and a curing agent containing two or more hydroxyl groups and / or amino groups as main components B By using a two-component mixed collision type spray to discharge a coating formed by combining liquids at a predetermined discharge pressure, a coating having excellent transparency can be formed on the surface of the structure without embracing air bubbles. .. In addition, it has excellent coatability and can efficiently form a coating having a smooth and uniform thickness.
According to the structure protection method of the present invention, it is possible to protect the surface of a structure such as a concrete structure, a natural stone structure, a laminated structure, a metal structure or a wooden structure, and it is excellent in transparency. Therefore, the surface of the structure can be visually observed for a long period of time through the coating film, and even if a defect occurs in the structure, the surface can be effectively prevented from peeling off.

The quadratic polynomial approximation curve calculated by the thickness and the concealment ratio in Example 1 is shown.

(Coating material)
In the method for protecting a structure of the present invention, 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. A coating material made of a combination of polyurea or polyurethane is used.
As the urethane prepolymer constituting the liquid A, a polyisocyanate compound having two or more isocyanate groups in one molecule and a compound having two or more active hydrogens reacting with the isocyanate groups in one molecule are reacted. Obtainable. In particular, as the active hydrogen compound, a polyol compound having two or more alcoholic hydroxyl groups in one molecule, for example, a urethane prepolymer formed by one or a combination of two or more types such as a polyether polyol, a polyester polyol, or another polyol is preferable. Is.

Examples of the polyisocyanate compound that can be used for preparing 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-cyclohexanediisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated tolylene diisocyanate, norbornene diisocyanate, hydrogenated m-xylylene diisocyanate, hydrogenated p-xylylene diisocyanate Kind: p-phenylenediisocyanate, 2,4-toluenediisocyanate, 2,6-toluenediisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 4,4'-diphenylmethanediisocyanate, naphthalenediocyanate, m-xyli Aromatic polyisocyanates such as aromatic diisocyanates such as range isocyanate and trizine diisocyanate; examples thereof include those obtained by modifying each of the above polyisocyanates with carbodiimide or isocyanurate, and these may be used alone or in combination of two or more. Can be done. Among these, it is preferable to use an aliphatic or alicyclic polyisocyanate from the viewpoint of transparency and discoloration resistance.

Specific examples of polyether polyols that can be used for preparing urethane prepolymers include polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethyleneoxypropylene glycol, polyoxytetramethylene glycol, polyoxyhexamethylene glycol, and the like. , Low molecular weight active hydrogen compounds having two or more active hydrogens, such as diols such as bisphenol A, ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol; glycerin, trimethylolpropane, 1,2,6- Triols such as hexanetriol; random co-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 and the like. Polymers can be mentioned.

Examples of the polyester polyol that can be used for preparing the urethane prepolymer include a polymer obtained by dehydration condensation of a polybasic acid and a polyhydric alcohol; a condensate of a hydroxycarboxylic acid and a polyhydric alcohol; a ring-opening polymer of a lactone, and the like. Is preferably used. Examples of the polybasic acid include adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, succinic acid, dimeric 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, and neo. Diols such as pentylene glycol; triols such as glycerin, 1,1,1-trimethylolpropane, 1,2,6-hexanetriol can be used. More specifically, polyethylene adipate, polytetramethylene adipate, polyhexamethylene adipate, polytetramethylene sebacate, poly (diethylene glycol adipate), and poly (hexamethylene glycol-1,6-carbonate) having diol components at both ends. ), Polycaprolactone and the like can be exemplified.

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, etc., as well as ethylene glycols and diethylene glycols. Low-molecular-weight polyols such as propylene glycol, dipropylene glycol, butanediol, pentanediol, and hexanediol are also preferably used.

As these polyol compounds, those having a number average molecular weight of 100 to 10,000, particularly 300 to 5000 are preferable, and they can be used alone or in combination of two or more as desired.

The urethane prepolymer has a ratio of more than 1 mol of isocyanate groups contained in the polyisocyanate compound to 1 mol of hydroxyl groups contained in the polyol compound, that is, a chemical equivalent ratio (NCO / OH) of more than 1. As a formulation, it can be obtained by heating a polyol compound and a polyisocyanate compound, if necessary, and reacting them. Such urethane prepolymers usually have isocyanate groups at both ends of the molecule. As a urethane prepolymer, the polyol compound and the polyisocyanate compound are reacted at a chemical equivalent ratio (NCO / OH) of 1.6 to 20 between the hydroxyl group contained in the polyol compound and the isocyanate group contained in the polyisocyanate compound. It is more preferable that the compound is liquid at 23 ° C. in terms of workability, physical properties of the cured product, and the like.

The coating material used in the method for protecting the structure of the present invention includes a liquid A containing the urethane prepolymer 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. It can be formed by curing a curable composition containing other additives, if necessary.
As the compound having two or more hydroxyl groups and / or amino groups for curing the urethane prepolymer, a compound having a molecular weight of 18 to 10000, preferably 30 to 5000 is preferable, and for example, ethylene glycol and 1,2-propylene glycol are preferable. , 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, polyhydric alcohols such as sorbitol and mannitol; low molecular weight aminos such as ethanolamine Alcohols; ammonia, hydrazine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, m-phenylenediamine, 2,4-toluenediamine, 2,6-toluenediamine, diethyltoluenediamine, dimethylthiotoluene In the preparation of low molecular weight polyamine compounds such as diamine, N, N'-bis (sec-butylamino) diphenylmethane, 3,3'-dichloro-4,4'-diamino-diphenylmethane, and the urethane prepolymers mentioned above. Polyester polyols such as polyether polyols and polyester polyols that can be used in the above; alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide or mixtures thereof are reacted to obtain a hydroxyl group at the polyether end and react with ammonia to form an amino group. Examples thereof include polyether polyamines such as polyoxyethylene diamine, polyoxypropylene diamine, and polyoxybutyrene diamine obtained by substituting with. Among these curing agents, it is preferable to use a polyether polyol or a polyether polyamine, but it is also possible to use a polyether polyol or a polyether polyamine in combination with one or more other low molecular weight polyols or low molecular weight polyamines. it can.
As these curing agents, the ratio of active hydrogen in the low molecular weight compound to 1 mol of the isocyanate group contained in the urethane prepolymer is about 0.8 mol or more, preferably about 0.95 to 1.2 mol. The curing agent is added as described above.

In addition to the urethane prepolymer and the curing agent, the solutions A and B contain additives such as plasticizers, solvents, surfactants, curing accelerators, antioxidants, dyes, etc., if necessary, according to conventionally known formulations. can do.

Plasticizers include carboxylic acid esters such as phthalates, 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 can be used alone or in admixture of two or more.

Solvents are used as needed to control the viscosity of the curable resin composition. As the solvent, an organic solvent that does not show reactivity with the liquid A and the liquid B can be preferably used. Not limited to this, 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 and methyl isobutyl ketone, cyclohexane, methylcyclohexane and ethyl. Alicyclic hydrocarbon solvent such as cyclohexane, petroleum hydrocarbon solvent such as mineral spirit, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether pro Pionate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, glycol ether esters solvents and the like can be exemplified, and two or more kinds of these solvents may be mixed and used.

As the surfactant, various surfactants may be added alone or in combination of two or more depending on the characteristics of the antifoaming agent, the emulsifier, the viscosity improving agent and the like.

Examples of the curing acceleration catalyst for accelerating the reaction between the urethane prepolymer and the curing agent include N-alkylbenzylamine, N-alkylaliphatic polyamine, triethylenediamine, N-alkylpiperazine, N-alkylmorpholin, and dimorpholinodiethyl ether. Organic metal compounds such as tin octenoate, dibutyltin dilaurate, lead organic acid, zirconium organic acid or bismuth organic acid, and aromatic carboxylic acids such as benzoic acid, phthalic acid and o-chlorobenzoic acid, 2. Examples thereof include organic acids such as aliphatic carboxylic acids such as −ethylhexanoic acid, octyl acid, stearic acid, oleic acid and linoleic acid, and 2-ethylhexanoic acid is preferable because it has excellent compatibility with polyols. .. These can be used alone or in admixture of two or more.
The above-mentioned curing acceleration catalyst can also be used when preparing the urethane prepolymer, and can be used to efficiently produce the urethane prepolymer.

Anti-aging agents are used to protect the coating material made of the above-mentioned coating material from light, oxygen, heat, etc., and commonly used anti-aging agents include light stabilizers, antioxidants, and the like. Examples of the light stabilizer include benzotriazole-based, benzophenone-based, benzoate-based, cyanoacrylate-based, hindered amine-based, and nickel-based. Further, examples of the antioxidant include hindered phenol-based, amine-based, sulfur-based, phosphorus-based and the like. These can be used alone or in combination of two or more. In particular, when a light stabilizer and a hindered phenolic antioxidant are used in combination, discoloration, cloudiness, and deterioration of surface gloss can be prevented for a long period of time, which is preferable.

Further, the coating material used in the present invention does not need to contain a silane coupling agent because it has excellent adhesion to the structure, but the amount is less than 1% by weight in the curable composition constituting the coating material. 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, the silane coupling agent includes isocyanate group-containing silanes, amino group-containing silanes, mercapto group-containing silanes, and epoxy group-containing silanes. Classes, vinyl-type unsaturated group-containing silanes and the like can be contained, and when the epoxy group-containing silanes are contained, the solution A is contained, and when the amino group-containing silanes are blended, the solution B is contained.

(Primer layer)
In the method for protecting a structure of the present invention, since the above-mentioned covering material has excellent adhesion to the structure, it is possible to directly spray-cover the surface of the structure, but the structure is formed through a primer layer. It is also possible to coat the surface of the object with a covering material. By forming the primer layer on the surface of the structure, the primer permeates the surface layer of the structure, so that the coating material can be more firmly adhered to the structure.
As the primer, a transparent epoxy resin primer having excellent adhesion to the coating material (polyurea or polyurethane) described above can be preferably used. As such an epoxy resin primer, those described in JP-A-2008-75033 by the applicant can be preferably used, and can be formed by the method described in the publication. Further, a transparent urethane resin primer or the like can also be preferably used.
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 the structure)
In the present invention, liquid A containing the above-mentioned urethane prepolymer having two or more isocyanate groups as a main component and liquid B containing a curing agent having two or more hydroxyl groups and / or amino groups as a main component are used. The surface of the structure is spray-coated using a liquid-mixed collision type spray, and it is important that the value of G calculated by the above formula (1) is adjusted within the range satisfying the condition of G ≦ 123. Is. When the value of G is larger than the above range, a uniform film can be formed, but on the other hand, air bubbles are embraced and the transparency becomes inferior.

As the spray device used for spraying the covering material onto the structure, a spray device consisting of a pressure control 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 collision type spray as a spray gun.
Further, in this two-component mixed collision type spray, it is preferable to select a mix chamber suitable for mixing and colliding liquid A and liquid B at a liquid pressure in the above range. In the present invention, the mixing chamber manufactured by Graco is not limited to this, and is No. 000 (orifice diameter 0.020 inch), No. 00 (0.029 inch), No. 01 (0.042 inch), 02. A two-component mixed collision type spray gun provided with a mix chamber having a chamber size corresponding to the number (0.052 inch) or the like can be preferably used. In particular, it is preferable to use a mix chamber equivalent to No. 01 (0.042 inch) for low discharge or equivalent to No. 00 (0.029 inch) having a smaller orifice diameter.

In the present invention, the pressure P (psi) of each liquid when the liquids A and B are mixed and collided, specifically, when the liquids A and B are introduced into the mix chamber and the two liquids are mixed and collided. ) And viscosity η (mPa · s) and the orifice diameter D (inch) of the mix chamber used for the two-component mixed collision type spray, the value of G calculated by the above formula (1) is G ≦ 123. The pressure P (psi) and viscosity of the liquids A and B so as to satisfy the condition of G ≦ 123 according to the orifice diameter D (inch) of the mix chamber used. It is important to adjust each of η (mPa · s).
Specifically, the pressures of the liquids A and B can be adjusted by setting the two-component mixing collision type spray device, and the viscosities of the liquids A and B can be adjusted by setting the temperature of each liquid. It can be adjusted by changing it.
Normally, the pressures of both liquids are adjusted to approximately the same value by a two-component mixed collision type spray device. Further, if the viscosity difference between the two liquids is adjusted to be smaller, the mixing of the two liquids becomes easier and the physical characteristics of the coating film are also improved. It is preferable to adjust the viscosities of both liquids to be smaller because the difference in viscosity between the two liquids becomes smaller. However, when the pressures of both liquids are adjusted to be high, it is rather better to increase the viscosities of both liquids. In some cases, it is possible to obtain a result with excellent transparency with less air bubbles.
If there is a difference in the pressure and viscosity values of both liquids, the pressure is set so that the G value becomes the maximum value that can be taken when calculating the G value represented by the above formula (1). For the value of (P), the higher value of solution A or solution B is used for calculation, and for the value of viscosity (η), the value of solution A or solution B, whichever is lower, is used for calculation. ..
Further, the liquid A and the liquid B have a touch drying time in the range of 10 seconds to 60 minutes according to the evaluation method described in JIS K-5600-1-1 of the material after the liquid A and the liquid B are mixed and collided. It is preferable that it is prepared so as to be.

In the present invention, in order to form a uniform coating having excellent transparency, in addition to the liquid pressure when the liquids A and B are mixed and collided, the viscosities of the liquids A and B, and the discharge direction (upper, lower, (Horizontal direction) It is desirable to appropriately adjust various conditions such as the spray distance, which is the distance between the discharge port of the two-component mixed collision type 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, and more preferably 30 to 80 cm. If it is less than 20 cm, the spray discharge is locally concentrated and uneven thickness is likely to occur, and if it exceeds 100 cm, a large amount of mist is generated or a portion that is locally cured into particles is generated in a material that cures quickly. It inhibits the formation of a film and deteriorates the physical properties of the coating material.

In the method for protecting a structure of the present invention, as described above, a coating material composed of liquid A and liquid B is formed directly on the surface of the structure or when the primer layer described above is formed on the primer layer. Is coated using a two-component mixed collision type spray.
The coating preferably has a thickness of 0.5 to 3 mm, particularly 0.7 to 2.5 mm. If the thickness of the coating film is thinner than the above range, it may not be able to exert a sufficient function as a protective coating, while if it is thicker than the above range, the transparency is lowered and the economy is also inferior.
When spraying the coating material, the amount of application for one round trip of the spray gun changes depending on the liquid pressure, liquid viscosity, orifice diameter of the mix chamber, etc., so the amount of coating is applied while checking the condition of the sprayed coating material. It is desirable to adjust. Especially for slow-curing materials, it is advantageous in that air bubbles caught during spraying can be easily removed, but if a large amount is sprayed at one time, liquid dripping may occur and the target film thickness may not be obtained. , It is necessary to spray small amounts in several divided doses.

The covering material formed by the method for protecting the structure of the present invention has excellent transparency, and the hiding rate at a thickness of 1 mm of the coating is less than 30%. Note that hiding factor, the resin was coated with 1mm thick hiding test paper conforming to JIS K5600 4-1 B method, the coated white portion tristimulus value Y of the film _{(Y W)} and black part (Y _B ) It can be measured in each case and the concealment rate Y _B / Y _W can be calculated as a percentage.
Further, the coating film formed by the method for protecting a structure of the present invention has a tensile strength of 2.3 N / mm ² or more and a tensile elongation at break of 200% or more, follows the displacement of the structure, and withstands appropriate stress. It can be formed as a film.

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

(Example 1)
Liquids A and B of polyurea resin were prepared by the following method.
Norbornene diisocyanate (trade name: Cosmonate NBDI, manufactured by Mitsui Chemicals SKC Polyurethane) 48.0 parts by weight and number average molecular weight 2000 polyoxypropylene glycol (trade name: Actol D-2000, manufactured by Mitsui Chemicals SKC Polyurethane) 26 26.0 parts by weight of polyoxypropylene glycol (trade name: Actol D-3000, manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd.) having a weight of 0.0 parts by weight and a number average molecular weight of 3000 was reacted at 100 ° C. for 4 hours to have an NCO group content. A liquid A of 17% by weight was obtained.
On the other hand, 77.4 parts by weight of polyether diamine (trade name: Jeffermin D-2000, manufactured by Huntsman) and diethyl toluenediamine (trade name: EtaCure 100, manufactured by Albemarle) having a number average molecular weight of 2000, 22.1 parts by weight, As an anti-aging agent, 0.5 parts by weight of a three-kind mixed liquid stabilizer (trade name: Chinubin B75, manufactured by BASF) was mixed to obtain a liquid B.

Liquids A and B are heated to a viscosity of 100 mPa · s, respectively, and as a two-component collision mixing type sprayer, a spray device H-40 manufactured by Graco and a prober gun manufactured by Glass Craft (with an orifice diameter) are used. A 0.029-inch mix chamber No. 00 manufactured by the same company is used), and the liquid A and liquid B are used when two liquids are mixed and collided from above at a spray distance of 60 cm against a horizontally placed propylene sheet. At each liquid pressure of 600 psi, spraying was performed 1 to 4 times for reciprocation to prepare four types of polyurea sheets having different thicknesses. The liquid pressures of the liquid A and the liquid B were adjusted in advance so that the liquid pressures of the liquid A and the liquid B were 600 psi by performing a trial spraying of the spray in advance. The touch-drying time of the coating material at room temperature after the spraying was completed was 30 minutes.

[Concealment rate]
The thickness of any three points was measured for each of the above four types of polyurea sheets. Next, these four types of polyurea sheets were placed on a concealment rate test paper conforming to the JIS K5600 4-1B method, and the tristimulus values Y were set to the white part (YW) and the black part (YW) at the positions of the three points where the thickness was measured. Each measurement was performed in YB), and the concealment rate YB / YW was obtained as a percentage. In addition, the one measured without the polyurea sheet was used as a blank. Table 1 shows the thickness and concealment ratio of each sheet.

Next, the concealment rate at a thickness of 1 mm was calculated from a quadratic polynomial approximation curve (FIG. 1) calculated from the thickness and concealment rate shown in Table 1. The results are shown in Table 2.

[Tensile characteristics]
Of the above four types of polyurea sheets, the polyurea sheets obtained by spraying four times in a reciprocating manner were evaluated for tensile properties in accordance with JIS K6251 and found to have a tensile strength of 18.3 N / mm ² and tensile elongation at break. Was 467%.

(Example 2)
Polyurea in the same manner as in Example 1 except that the liquid pressures of each of the liquid A and the liquid B were adjusted in advance so as to be 1000 psi, and the liquids A and B were each heated to have a viscosity of 150 mPa · s. A sheet was prepared and the concealment rate at a thickness of 1 mm was evaluated. The results are shown in Table 2.

(Example 3)
Polyurea in the same manner as in Example 1 except that the liquid pressures of each of the liquid A and the liquid B were adjusted in advance to be 550 psi, and the liquids A and B were each heated to have a viscosity of 100 mPa · s. A sheet was prepared and the concealment rate at a thickness of 1 mm was evaluated. The results are shown in Table 2.

(Example 4)
Polyurea in the same manner as in Example 1 except that the liquid pressures of each of the liquid A and the liquid B were adjusted in advance to be 1700 psi, and the liquids A and B were heated to have a viscosity of 250 mPa · s, respectively. A sheet was prepared and the concealment rate at a thickness of 1 mm was evaluated. The results are shown in Table 2.

(Example 5)
Replace the mix chamber used in the glass craft prober gun with the company's mix chamber 01 with an orifice diameter of 0.042 inches, and make the liquid pressures of liquid A and liquid B 1100 psimPa · s in advance. A polyurea sheet was prepared in the same manner as in Example 1 except that the liquids A and B were adjusted and heated to have viscosities of 100 mPa · s and 50 mPa · s, respectively, and the hiding ratio at 1 mm thickness was evaluated. went. The results are shown in Table 2.

(Comparative Example 1)
In the same manner as in Example 1, the thickness was 1 mm, except that the pressures of each of the liquid A and the liquid B were adjusted in advance to 800 psi, and the liquid A and the liquid B were heated to have a viscosity of 50 mPa · s, respectively. The concealment rate was evaluated. The results are shown in Table 2.

(Comparative Example 2)
In the same manner as in Example 1, the thickness was 1 mm, except that the pressures of each of the liquid A and the liquid B were adjusted in advance to be 2000 psi, and the liquid A and the liquid B were heated to have a viscosity of 150 mPa · s, respectively. The concealment rate was evaluated. The results are shown in Table 2.

(Comparative Example 3)
Liquids A and B of polyurea resin were prepared by the following method.
4,4'-Diphenylmethane diisocyanate (trade name: Cosmonate PH, manufactured by Mitsui Chemicals SKC Polyurethane) 55.0 parts by weight and number average molecular weight 2000 polyoxypropylene glycol (trade name: Actol D-2000, Mitsui Chemicals SKC) 45.0 parts by weight (manufactured by Polyurethane Co., Ltd.) was reacted at 80 ° C. for 4 hours to obtain a solution A having an NCO group content of 17% by weight.
On the other hand, 60.4 parts by weight of a polyether diamine having a number average molecular weight of 2000 (trade name: Jeffermin D-2000, manufactured by Huntsman) and a polyether triamine having a number average molecular weight of 5000 (trade name: Jeffamine T-5000, manufactured by Huntsman). 7.0 parts by weight, diethyltoluenediamine (trade name: EtaCure 100, manufactured by Albemar) 22.1 parts by weight, 3 types of mixed liquid stabilizer as anti-aging agent (trade name: Chinubin B75, manufactured by BASF) 0 .5 parts by weight was mixed to obtain liquid B.

The liquid A and the liquid B in the previous term were heated to have viscosities of 70 mPa · s and 30 mPa · s, respectively, and as a two-liquid collision mixing type sprayer, a spray device H-40 manufactured by Graco and a professional manufactured by Glass Craft Co., Ltd. When using a Bragan (using the company's mix chamber No. 00 with an orifice diameter of 0.029 inches) attached and colliding with a horizontally placed propylene sheet from above at a spray distance of 70 cm. Four types of polyurea sheets having different thicknesses were prepared by spraying at 1500 psi of each of the liquid A and the liquid B with the number of reciprocations of 1 to 4 times. The liquid pressures of the liquid A and the liquid B were adjusted in advance so that the liquid pressures of the liquid A and the liquid B were 1500 psi by performing a trial spraying of the spray in advance. The touch-drying time of the coating material at room temperature after the spraying was completed was 25 seconds. The results are shown in Table 2.

(Comparative Example 4)
The same as in Comparative Example 3 except that the liquid pressures of each of the liquids A and B were adjusted in advance to 900 psi, and the liquids A and B were heated to have viscosities of 70 mPa · s and 30 mPa · s, respectively. The concealment rate at a thickness of 1 mm was evaluated. The results are shown in Table 2.

As shown in Table 2, the orifice diameter D (inch) of the mix chamber used for the two-component mixed collision type spray, and the respective liquid pressures of liquid A and liquid B at the time of two-component mixed collision are P (psi) and two liquids. The concealment rate is reduced by selecting the condition that the value of G calculated by the above formula (1) is 123 or less from η (mPa · s) for the respective liquid viscosities of the liquid A and the liquid B at the time of mixed collision. did.

Claims (6)

A coating material composed of 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 used. A method of protecting a structure by spraying and coating the surface of the structure using a liquid-mixed collision type spray.
A method for protecting a structure, wherein the value of G calculated by the following formula satisfies the condition of G ≦ 123.
G = (P / η) ^1/2 / D
In the formula, D is the orifice diameter (inch) of the mix chamber used for the two-liquid mixed collision type spray, and P indicates the pressure (vis) of the A liquid and the B liquid at the time of the two-liquid mixed collision. If there is a difference in the pressure values of the liquids, it is the higher value, and η indicates the viscosities (mPa · s) of the liquids A and B when the two liquids are mixed and collided, and the values of the viscosities of both liquids. If there is a difference in, it is the lower value. The method for protecting a structure according to claim 1, wherein each of the liquid A and the liquid B does not contain a silane coupling agent or contains an amount of less than 1% by weight. The method for protecting a structure according to claim 1 or 2, wherein the structure is a concrete structure, a natural stone structure, a masonry structure, a metal structure or a wooden structure. The method for protecting a structure according to any one of claims 1 to 3, wherein the covering material is directly spray-coated on the surface of the structure. The method for protecting a structure according to any one of claims 1 to 4, 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 5, wherein the hiding rate of the coating film formed of the covering material at a thickness of 1 mm is less than 30%.

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