JP4542021B2 - And drainage concrete structures and repair methods - Google Patents

Description

  The present invention relates to a concrete structure for use and drainage channels coated with a coating film made of a two-component polyurethane composition. Specifically, a concrete structure having a surface in contact with water applied to a use / drainage channel, the surface of which is a polyurethane coating coated with a two-component polyurethane composition by spraying. A structure and a concrete structure for use and drainage that does not have a coating surface at the beginning of construction are used in the use and drainage, and a two-component polyurethane composition is applied to the surface that is aged or damaged during its use. The present invention relates to a method for repairing the surface of a concrete structure for use and drainage, characterized by spraying to form a polyurethane coating.

The water and drainage channel is a waterway that takes in water necessary for public use and agriculture, and discharges used or unnecessary water, adjusts the flow of water, protects the side walls of the waterway, etc. In general, concrete structures are applied.
Such a concrete structure for use and drainage is constructed by precast concrete or concrete casting in place. The constructed use and drainage channels will be used for the duration of the purpose and effect of the concrete structure.
The surface of a concrete structure used as a service / drainage channel becomes obsolete with the passage of service years, and in particular, the drainage channel is inevitably deteriorated due to contaminated organisms, minute solids, etc. in running water. In particular, the drainage channel and drainage channel constructed in rapid rivers and dams have a large scavenging force for the flowing sediment, and are damaged by the sediment and damage caused by impacts, and have various effects on the water flow.

Such aged or damaged concrete structure needs to be repaired to extend the service life of the service and drainage channels.
In such a case, there is a method of replacing a damaged concrete structure with a new structure. However, replacement of a concrete structure may be a large-scale construction and may increase the cost of the structure and the work cost.
On the other hand, the standards of water quality regulations tend to become stricter from the aspect of natural environment conservation, and it is necessary to consider the elution of substances causing water pollution from concrete structures into water.

Under such circumstances, there is no leaching of trace substances that are subject to water quality regulation from the surface where the concrete structure for use and drainage is in contact with water, and for damaged use and drainage. There is a demand for a construction method for repairing an aged or damaged concrete structure at a low cost without repairing the surface of the concrete structure in contact with water with a large-scale construction method.
In addition, the surface of the irrigation / drainage channel is in constant contact with water throughout the year, and after being immersed in water near the waterline, it is constantly cycled to become dry due to direct sunlight, and further in contact with water above the waterline. There are parts that are not. There is a demand for a coating film having excellent durability under such severe conditions.

  The problem of the present invention is to repair at least the surface of the used / drainage concrete structure in use that has been aged or damaged at low cost, to extend the service period as a use / drainage channel, A concrete structure for use / drainage channel in which a trace amount of substances subject to water quality regulation is not eluted into the water from the surface of the use / drainage concrete structure, and a highly durable coating film is sprayed, and It is to provide a repair method.

The present inventors have intensively studied to solve the above-mentioned problems, and the main component (A) containing a terminal isocyanate group-containing urethane prepolymer and an active hydrogen-containing compound (B1) on the surface of the concrete structure for use / drainage. ) And a curing agent (B) containing a lead-free catalyst (B2) comprising an organic acid bismuth salt or a fatty acid bismuth salt having 8 to 20 carbon atoms, and applied by spraying By forming a polyurethane coating film, it is used as a concrete structure having a coating film that does not have to worry about elution of trace components into water, which is subject to water quality regulations, and for use as a drainage channel, By repairing the concrete structure at a low cost by forming the coating film on the surface of the concrete structure whose surface in contact with water is aged or damaged. Heading to be able to extend the use period, which resulted in the completion of the present invention.
That is, the present invention provides: A main agent (A) containing a terminal isocyanate group-containing urethane prepolymer, an active hydrogen-containing compound (B1), and a lead-free catalyst (B2) comprising a bismuth salt of an organic acid or a fatty acid bismuth salt having 8 to 20 carbon atoms. 1. a concrete structure for use and drainage, on which a polyurethane coating film obtained by curing a two-component curable polyurethane composition containing a curing agent (B) is formed; At least on the surface of the concrete structure for use / drainage whose surface in contact with water is aged or damaged, a main agent (A) containing a terminal isocyanate group-containing urethane prepolymer, an active hydrogen-containing compound (B1), and an organic acid A two-component curable polyurethane composition comprising a bismuth salt or a curing agent (B) containing a lead-free catalyst (B2) composed of a fatty acid bismuth salt having 8 to 20 carbon atoms is applied by spraying, reacted and cured. A method of repairing a concrete structure for use and drainage, characterized by forming a polyurethane coating film.
Further, the plastic structure used for the main agent and / or the curing agent is diisononyl adipic acid ester or fatty acid ester, the concrete structure for use / drainage according to 1 above, or the use / drainage use according to 2 above This is a repair method for concrete structures.

The work and drainage channels are usually constructed with concrete structures. Such waterways are aged over the years of service and are damaged by sediments and other solids in the running water.
The present invention is a method capable of repairing an aged or damaged concrete structure at a low cost. A concrete structure having a repaired polyurethane coating is an organic acid as a urethanization catalyst for a polyurethane coating. Since a bismuth salt or a fatty acid bismuth salt having 8 to 20 carbon atoms is used, a lead component that causes a problem in environmental conservation does not elute into water from the coating film. In addition, when a lead-containing compound is used as a catalyst, the top coat further formed on the polyurethane coating layer may suppress the elution of the lead component in question into water. The film does not necessarily require a topcoat layer. That is, the present invention is a coating that repairs the deterioration and damage of concrete structures for use and drainage at low cost, extends the service period of the waterway, and does not adversely affect the quality of the use and drainage. It is possible to provide a repair method that is a concrete structure covered with a film and that is advantageous in terms of construction man-hours and costs.
Moreover, the polyurethane coating film on the surface of the concrete structure repaired by this method is excellent in durability, particularly water resistance, and does not deteriorate in physical properties even for many years of service.

The concrete structure for use / drainage channel referred to in the present invention is a concrete structure having a surface in contact with water for the use channel or the drainage channel. For example, as a structure that adjusts the flow of water in order to use water effectively and drain it, such as a water channel that supplies water from agricultural dams and reservoirs to fields and fields, and a drainage channel that drains used water. It is a concrete structure that is manufactured and used.
The materials and shapes, etc. that are actually manufactured and put to practical use, or precast / concrete structures, or concrete structures that are made by placing concrete on the construction site, can be used There is no particular limitation as long as it can be used.
For example, concrete structures for use and drainage such as bench flume of various sizes, bench boxes, and L-types for waterways as practical agricultural waterway concrete products. Moreover, the block-shaped concrete structure used for side walls, such as a waterway, a dam, or a pond, may be sufficient.
The concrete structure referred to in the repair method of the present invention is such that the surface of the concrete structure used as a service / drainage channel is aged or damaged with the passage of service years.
In particular, the drainage channel is inevitably deteriorated due to polluted organisms in the flowing water, solid substances of various sizes from small to large. Concrete structures such as drainage channels and drainage channels constructed in rapid rivers and dams have a large scavenging force for flowing sediment, and are severely damaged by sediment and wear.

The polyurethane coating film according to the present invention comprises a main agent containing a terminal isocyanate group-containing urethane prepolymer, a curing agent containing an active hydrogen-containing compound and a non-lead catalyst, that is, a two-component curable polyurethane composition by a spray method. It is obtained by applying and reacting.
The terminal isocyanate group-containing urethane prepolymer used in the main agent is a compound having an isocyanate group, for example, an aromatic isocyanate, an aliphatic isocyanate, an alicyclic isocyanate, a mixture thereof or a modified product of an organic isocyanate compound such as a urethane prepolymer, and the like. It is obtained by reacting a compound having active hydrogen that reacts with isocyanate, that is, an active hydrogen-containing compound such as a polyol compound or polyamine compound having two or more hydroxyl groups at the molecular ends.
Examples of the compound having an isocyanate group include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), 1,5-naphthalene diisocyanate (NDI), liquid Aromatic isocyanates such as diphenylmethane diisocyanate (liquid MDI), crude tolylene diisocyanate (crude TDI), polymethylene polyphenyl polyisocyanate crude (crude MDI), aliphatic isocyanates such as hexamethylene diisocyanate (HDI), isophorone Diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), hydrogenated tetramethyl XDI, norbornane diiso Alicyclic polyisocyanates such as Anetomechiru (NBDI) and the like.

Also included are isocyanate group-terminated prepolymers, carbodiimide modified products, uretonimine modified products, acylurea diisocyanate, isocyanurate modified products, trimethylolpropane adducts, biuret modified products, and allophanate modified products using these isocyanates.
Preferably, it is an MDI polyisocyanate and / or a modified product thereof. These compounds having an isocyanate group may be used alone or in combination of two or more.

A compound containing an active hydrogen that reacts with an isocyanate (sometimes simply referred to as an active hydrogen-containing compound) is a polyol compound or a polyamine compound having two or more hydroxyl groups at a molecular end, and is a typical preparation of a polyurethane resin composition. Active hydrogen-containing compounds used in
For example, as a relatively low molecular weight polyhydric alcohol, ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), 1,3-butanediol (1,3-BD), Dihydric alcohols such as 1,4-butanediol (1,4-BD), neopentyl glycol (NPG), 4,4′-dihydroxyphenylpropane, 4,4′-dihydroxyphenylmethane, glycerin, 1,1, Examples include trihydric alcohols such as 1-trimethylolpropane (TMP), 1,2,5-hexanetriol, and triethanolamine (TEA), and polyhydric alcohols such as pentaerythritol, glucose, sucrose, and sorbitol. It is done.

As the polyether polyol, for example, one or more types of relatively low molecular weight polyhydric alcohols, or one or more types of low molecular weight amine compounds such as ethylenediamine and aniline, ethylene oxide, propylene oxide, butylene oxide or the like Examples include polyether polyols obtained by addition polymerization of two or more, or polytetramethylene ether glycol (PTMEG) obtained by ring-opening polymerization of tetrahydrofuran.
Examples of the polyester polyol include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerin, trimethylolpropane and the like, or one or more other low molecular weight polyols, glutaric acid, adipic acid, sebacic acid, terephthalate. Examples thereof include polyester polyols obtained by condensation polymerization with one or more of acid, isophthalic acid, dimer acid or the like or other low molecular dicarboxylic acid or oligomeric acid and ring-opening polymerization of caprolactone.

Furthermore, the polyester polyether polyol etc. which are obtained by addition-polymerizing 1 type (s) or 2 or more types, such as ethylene oxide, a propylene oxide, butylene oxide, to the said well-known polyester polyol, etc. are mentioned.
Examples of the modified product of the polyether polyol or polyester polyol include polymer polyols obtained by graft polymerization of ethylenically unsaturated compounds such as acrylonitrile, styrene and methyl methacrylate to the known polyether polyol or polyester polyol.
Examples of other polyols include polycarbonate polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, acrylic polyol, epoxy polyol, and castor oil.
Moreover, as a polyamine compound, aliphatic polyamines, such as ethylenediamine and polyether polyamine, and aromatic polyamine are mentioned, for example.
Furthermore, alkanolamines such as monoethanolamine (MEA), diethanolamine (DEA) and the like can be mentioned.
These active hydrogen-containing compounds can be used singly or in combination of two or more.

The terminal isocyanate group-containing urethane prepolymer preferably comprises a compound containing an isocyanate group at the terminal and a polyol compound having two or more hydroxyl groups at the molecular terminal as an active hydrogen-containing compound at an NCO / OH ratio of 4 to 25. The reaction is carried out (in the case where the active hydrogen compound is a polyamine compound, the ratio is NCO / H).
There is no particular limitation on the method for synthesizing the urethane prepolymer. For example, the isocyanate group-containing compound can be combined with the active hydrogen-containing compound within the above NCO / OH ratio (or NCO / H ratio) range with respect to the active hydrogen-containing compound. Then, mixing or either one is charged first, the other is added later, and a known catalyst can be added and reacted for 10 to 120 ° C. for 1 to 150 hours, if necessary, in order to speed up the reaction.

Among the above main agents and curing agents, suitable plasticizers for plastics conventionally used in the production of polyurethane resins, such as phthalic acid dibutyl ester (DBP), phthalic acid di-n-octyl ester (DnOP), phthalic acid Di (2-ethylhexyl) ester (DOP), phthalic acid diisononyl ester (DINP), adipic acid di (2-ethylhexyl) ester (DOA), adipic acid diisononyl ester (DINA) and the like can be used.
Among these, in particular, adipic acid diisononyl ester (DINA) is used optimally because it imparts excellent durability to a concrete structure.
Moreover, since fatty acid ester shows the outstanding thinning effect, this can also be used. For fatty acid esters, the viscosity of the two liquids sprayed by the high-pressure two-component spraying device is taken into consideration in consideration of the construction temperature, reaction temperature, etc., to shorten the work time, reduce the amount of work, and save energy during the work. Conditions can be set advantageously in terms of work.

In the polyurethane coating film according to the present invention, the fatty acid ester used for the main agent and / or the curing agent is, for example, stearic acid methyl ester, palmitic acid methyl ester, lauric acid methyl ester, oleic acid methyl ester, etc. Or fatty acid esters derived from the synthesis of natural fatty acids such as beef tallow fatty acid methyl ester, nuka fatty acid methyl ester, vegetable fatty acid methyl ester, palmitic acid butyl ester and vegetable fatty acid butyl ester (hereinafter simply referred to as natural fatty acids) An ester). Preferred are naturally occurring fatty acid esters, and more preferred are Nuka fatty acid esters.
The amount of these plasticizers used is 1 to 25% by weight based on the total amount of the main agent and the curing agent. If it is less than 1% by weight, the viscosity is too high, which is not preferable for the spray method. On the other hand, if it exceeds 25% by weight, it adversely affects the properties of the cured product.

The curing agent used for forming the coating film according to the present invention contains an active hydrogen-containing compound and a lead-free catalyst.
The active hydrogen-containing compound is usually a polyol having two or more hydroxyl groups in one molecule or a polyamine having two or more amino groups in one molecule, and the polyol and polyamine may be used in combination.
Examples of the polyol include polyhydric alcohols having a relatively low molecular weight, polyether polyols, polyester polyols, polyether polyols, and modified polyester polyols.

  Examples of the relatively low molecular weight polyhydric alcohol include ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), and 1,3-butanediol (1,3-BD). 1,2-butanediol (1,4-BD), neopentyl glycol (NPG), 4,4′-dihydroxyphenylpropane, dihydric alcohols such as 4,4′-dihydroxyphenylmethane, glycerin, 1,1 , 1-trimethylolpropane (TMP), 1,2,5-hexanetriol, trihydric alcohols such as triethanolamine (TEA), tetrahydric or higher polyhydric alcohols such as pentaerythritol, glucose, sucrose, sorbitol, etc. Can be mentioned.

In addition, as the polyether polyol, for example, a polyether polyol and tetrahydrofuran obtained by addition polymerization of one or more kinds such as ethylene oxide, propylene oxide, and butylene oxide to one or more kinds of relatively low molecular weight polyhydric alcohols can be opened. Examples thereof include polytetramethylene ether glycol (PTMEG) obtained by polymerization.
Examples of the polyester polyol include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerin, trimethylolpropane and the like or one or more of other low-molecular polyols, glutaric acid, adipic acid, and sebacic acid. And polyester polyols obtained by condensation polymerization with one or more of low molecular dicarboxylic acids and oligomeric acids and ring-opening polymerization of caprolactone, etc., terephthalic acid, isophthalic acid, dimer acid and the like.

Examples of the modified product of the polyether polyol or polyester polyol include polymer polyols obtained by graft polymerization of ethylenically unsaturated compounds such as acrylonitrile, styrene and methyl methacrylate to the known polyether polyol or polyester polyol.
Examples of other polyols include polycarbonate polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, acrylic polyol, epoxy polyol, and castor oil.
When such a modified product of polyether polyol or polyester polyol is used as the active hydrogen-containing compound, the amount used may be appropriately set according to the purpose and physical properties of the obtained polyurethane coating film.
Examples of the polyamine include aliphatic polyamines such as ethylenediamine and polyether polyamine, and aromatic diamines such as diethyltoluenediamine and 4,4′-methylenebis- (2-chloroaniline).
Furthermore, alkanolamines such as monoethanolamine (MEA), diethanolamine (DEA) and the like can be mentioned.

Examples of the lead- free catalyst contained in the curing agent include organic acid bismuth salts and fatty acid bismuth salts having 8 to 20 carbon atoms.
Examples of the organic acid bismuth salt include abietic acid, neoabietic acid, d-pimalic acid, iso-d-pimalic acid, podocarpic acid, and alicyclic organic acids such as bismuth resin acid mainly composed of two or more of these. And bismuth salts of aromatic organic acids such as benzoic acid, cinnamic acid, and p-oxycinnamic acid. Examples of the fatty acid bismuth salt having 8 to 20 carbon atoms include bismuth salts such as octylic acid, neodecanoic acid and neododecanoic acid.
The usage-amount of organic acid bismuth salt is 0.001 to 3 weight% as metal bismuth with respect to a hardening | curing agent, Preferably it is 0.005 to 1 weight%.

In addition, co-catalysts, chain extenders, fillers, anti-aging agents, UV absorbers, light stabilizers, antioxidants, pigments or dye colorants, dispersants, etc., are added to the curing agent as necessary. You may mix | blend an agent arbitrarily.
Moreover, it can also use as a foam by adding a foam stabilizer and a foaming agent according to a use. As long as these other additives are within the range not impairing the effects of the present invention, a part or all of the blending amount may be blended with the main agent.

The polyurethane coating film according to the present invention is obtained by spraying the above main agent and curing agent onto the surface of a concrete structure, which is a construction object, with a high-pressure two-component spraying apparatus, and reacting and curing.
The amount of the main agent and the curing agent used here is a volume ratio of 4: 1 to 1: 4, and NCO Index (equivalent ratio of NCO groups in the terminal isocyanato group-containing urethane prepolymer and active hydrogen in the curing agent) ) Is in the range of 0.9 to 1.3, preferably 1 to 1.2.
When using a fatty acid ester if necessary, the viscosity of the main agent containing the terminal isocyanate group-containing urethane prepolymer and the viscosity of the curing agent containing the active hydrogen-containing compound and the non-lead-based catalyst are the same as those of the conventional plasticizer. Since it is lower than when used, the heating temperature of the main agent and curing agent sent to the spray gun is lower and can be set according to the appropriate reaction temperature in the high-pressure two-component spraying device. Can be shortened.

The method of forming a coating film on the surface of the concrete structure in the present invention is as follows.
On the surface of precast concrete or concrete structures for use in drainage channels made by casting concrete on the construction site, the main component containing the above-mentioned terminal isocyanate group-containing urethane prepolymer, active hydrogen-containing compound and lead-free catalyst A coating film is formed by spraying and reacting with the contained curing agent so that the film thickness of the coating film is 1 mm or more on average, preferably 2 mm or more on average. A film thickness of 5 mm or less on average is usually sufficient.
The surface of the concrete structure for use / drainage that is in contact with water is the inner wall that comes into contact with the water when the newly constructed concrete structure for use / drainage acts as a use / drainage channel. The surface of the concrete and the constructed concrete structure are used for use and drainage, and include surfaces that are aged or damaged in contact with running water. In particular, in the repairing method of the present invention, it refers to a surface including a surface in contact with water of a concrete structure which is used as a use / drainage channel and whose surface is aged or damaged.

When such aging or damage is found, the concrete structure needs to be returned to a usable state when it is continuously used. For this purpose, the concrete structure must be replaced with a new one. A method of extending the service life of a concrete structure by replacing it with a new one or repairing only the damaged part will be adopted.
The method of the present invention is a method for repairing the latter. When aging or damage is found, the water channel is dried up, and at least the portion where the concrete structure is in contact with water is cleaned and cured. A main component containing a terminal isocyanate group-containing urethane prepolymer and a curing agent containing an active hydrogen-containing compound and a non-lead catalyst are applied by spraying and reacted to form a polyurethane coating. If necessary, when forming the coating film, a commonly used urethane-based or epoxy-based primer may be applied in advance to a part or the entire surface of the concrete structure to be constructed.

Moreover, the polyurethane coating film on the surface of the concrete structure of the present invention and the repaired polyurethane coating film do not require a further topcoat layer on the surface.
If the catalyst in the curing agent to be used is a lead-based catalyst, a top coat is applied to suppress elution of the lead component from the coating film into water. However, it is difficult to maintain the state of the topcoat layer as it is at the beginning of the operation due to contaminated organisms in the running water, minute to various solids, and normalize the surface condition of the coating film. It is necessary to maintain. Such a topcoat layer increases the initial cost of construction and the cost for maintenance of the coating film surface.
On the other hand, in the coating film according to the present invention, since the lead component does not elute into the water from the coating film, there is no hindrance to the effect as a use / drainage channel even if the topcoat layer is not constructed. . Moreover, since the construction of the top coat layer is not required, the repair method of the present invention can reduce the construction cost. However, if necessary, the top coat may be applied by a usual method.

Replacing an old or damaged concrete structure with a new structure is easy to replace with a precast concrete structure. It was a method that required time and labor of construction, such as construction to transport the structure from the production site to the construction site and install it.
On the other hand, the method of the present invention is a method that enables construction work on the site where a concrete structure found to be aged or damaged is installed, and can be constructed simply and economically.
That is, when a concrete structure is discovered due to damage to the surface in contact with water, the water flow is stopped, the damaged surface is cleaned and dried, and then the two-component polyurethane composition is sprayed onto the sprayed coating film. It is a simple method of forming.

  Conventionally, waterproof coatings made of polyurethane resins have been used as catalysts for urethanization reactions.For example, if metal of a metal compound such as lead elutes from the coating into the water, it is regarded as a problem that pollutes environmental water. However, the polyurethane coating film on the surface of the concrete structure in the present invention has no elution of lead, which is an object of water quality regulation, into water. In addition, the polyurethane coating film according to the present invention does not necessarily need to be applied with a topcoat layer containing an ultraviolet absorber, and even if the coating film is apparently discolored without a topcoat layer. There is no effect on the effectiveness of the irrigation channel. Rather, the initial cost of construction and the cost for maintenance can be reduced.

Specific examples of the present invention will be described below. However, the present invention is not limited to this embodiment.
Example 1
It was discovered that a canal that had been in service for 10 years as a canal using precast concrete structures was discolored and damaged. The water channel was temporarily dammed, the water in that portion was discharged, the inner wall of the concrete structure in contact with the water was cleaned and dried.
Thereafter, 41.731 parts by weight of Cosmonate PH (Pure MDI: manufactured by Mitsui Takeda Chemical Co., Ltd.), 10.432 parts by weight of Cosmonate LK (carbodiimide-modified MDI; manufactured by Mitsui Takeda Chemical Co., Ltd.), and Actcol D-2000 (number average) Polypropylene ether diol having a molecular weight of 2000: 42.836 parts by weight of Mitsui Takeda Chemical Co., Ltd., and 90.degree. C. for 3 hours in the presence of 5.000 parts by weight of fine ester R-1000 (Nuka fatty acid ester: Miyoshi Oil & Fats Co., Ltd.) The main agent (A), which is a prepolymer having a NCO% of 9.4 and a viscosity of 450 mPa · s / 25 ° C., obtained by the reaction, and Actcol D-1000 (polypropylene ether diol having a number average molecular weight of 1000: manufactured by Mitsui Takeda Chemical Co., Ltd.) 83.701 parts by weight, Ethacure # 100 (diethyltoluene di) Min: Albemarle Asano) 15.249 parts by weight, pcat B-7 (resin acid bismuth: bismuth metal content 7%: manufactured by Nippon Chemical Industry Co., Ltd.) 0.500 parts by weight, 2-ethylhexanoic acid 0.050 parts by weight, TINUVIN B-75 (three kinds of mixed liquid stabilizers: Ciba Geigy Co., Ltd.) 0.500 parts by weight was mixed with a curing agent (B) prepared with a mixed liquid having a viscosity of 300 mPa · s / 25 ° C., and the main agent (A) The curing agent (B) was sprayed using an H-20 spray machine manufactured by Gasmer Co. at A / B = 1/1 (volume ratio) and NCO Index 1.1. Liquid feeding to the spray machine was performed by applying a 0.5 MPa air pressure to a Graco supply pump (air driven 2: 1 type). The spray machine was used at a stationary pressure of 14 MPa and a spraying pressure of 10 to 12 MPa.
The temperature of the liquid was adjusted to a main agent primary heater 60 ° C., a curing agent primary heater 60 ° C., and a hose heater 60 ° C.
The spray gun was sprayed using a round chamber # 1 of a glass gun probler gun. Lamination was performed 3 to 5 times to form a coating film having a thickness of about 2 mm.
Thus, the irrigation channel repaired with the polyurethane coating was able to open the dam and release the irrigation water again three days after the construction.

The coating film was peeled off from the concrete structure to a size of 5 cm × 5 cm, washed with running water for 1 hour with tap water (Tama City, Tokyo), and then washed with purified water three times. Next, it is immersed in a leaching solution (pH 7.0 ± 0.1, hardness 45 ± 5 mg / L, alkalinity 35 ± 5 mg / L, residual chlorine 1.0 ± 0.2 mg / L) at about 23 ° C. The conditioning operation was repeated twice by replacing the immersed liquid after standing for 24 hours. After conditioning, the specimen was immersed in the leaching solution and allowed to stand at about 23 ° C. for 72 hours, and the resulting solution was used as the leaching solution. The leaching solution was allowed to stand under the same conditions as a blank test solution.
The amount of bismuth in the leachate was measured by inductively coupled plasma mass spectrometry with a lower detection limit of 0.001 mg / L. In the prepared coating film, the bismuth elution amount measured by such a method was 0.001 mg / L or less, which is the detection limit, and the bismuth elution amount in water was extremely small.

Further, after one year of the coating film sprayed on the surface of the concrete structure, the underwater part, the water line part, and the part above the water line were respectively peeled off from the concrete structure by 10 cm × 20 cm. This was compared with a sheet having a thickness of about 2 mm, which was prepared when the polyurethane coating was used for repair, and a tensile test was conducted with a dumbbell-shaped No. 3 shape in accordance with the tensile test method for vulcanized rubber JISK6251-1993. As a result, tensile strength, 10.4N / mm ² at a sheet at the time of performing maintenance, 10.2 N / mm ² in water portion, 10.0 N / mm ² at the waterline part 10 at the portion above the waterline 1 N / mm ² . The elongation rate was 500% for the repaired sheet, 490% for the underwater portion, 490% for the waterline portion, and 480% for the portion above the waterline, and was found to be sufficiently durable.
In addition, the sample sheet was preliminarily subjected to hot water immersion and thermal degradation test for up to 8 weeks according to the method described later.
These results are summarized in Table 1.

Comparative Example 1
Other than using 0.14 parts of Minico P-25 (lead octylate: lead content 25%: manufactured by Active Materials Chemical Co., Ltd.) in place of the pcat B-7 in Example-1 for the small-sized bench flume. Formed a coating film in the same manner as in Example-1. The coating film was peeled off by the same method, and the amount of lead eluted from the coating film was measured. The amount of lead eluted in the leachate was 0.008 mg / L.

Example 2
The same procedure as in Example 1 was repeated except that the fine ester R-1000 was changed to adipic acid diisononyl ester (DINA). One year after the coating film sprayed on the surface of the concrete structure, the underwater part, the water line part, and the part above the water line were respectively peeled off from the concrete structure by 10 cm × 20 cm. This was compared with a sheet having a thickness of about 2 mm, which was prepared when the polyurethane coating was used for repair, and a tensile test was conducted with a dumbbell-shaped No. 3 shape in accordance with the tensile test method for vulcanized rubber JISK6251-1993. As a result, tensile strength, 10.2 N / mm ² at a sheet at the time of performing maintenance, 10.1N / mm ² in water portion, 10.0 N / mm ² at the waterline part 10 at the portion above the waterline 0.0 N / mm ² . The elongation rate was 520% for the repaired sheet, 500% for the underwater portion, 510% for the waterline portion, and 490% for the portion above the waterline, which was recognized as being sufficiently durable.
In addition, the sample sheet was subjected to a hot water immersion and a heat deterioration test for a maximum of 8 weeks in the same manner as in Example 1, but the durability was at a level with no problem.
These results are summarized in Table 1 together with the results of Example 1.

Note) * 1: Remove after immersion in 50 ° C water for 8 weeks. Immediately soak in water at 23 ° C. to prevent the sample sheet from drying. After the sample sheet reached 23 ° C., it was taken out and a tensile test was performed within 30 minutes.
* 2: Removed after immersion in 50 ° C. water for 8 weeks, dried for 1 week in an atmosphere of 23 ° C. and 55%, and then subjected to a tensile test.
* 3: Taken out after heating at 80 ° C. for 8 weeks, left in a 23 ° C., 55% atmosphere for 1 day, and then conducted a tensile test.

  The concrete structure having a polyurethane coating film of the present invention is a concrete structure having a polyurethane coating film that is free from elution of lead components, which are subject to water pollution control of environmental pollution, from the coating film itself and has excellent durability. In addition, if the concrete structure for use / drainage that has been aged or damaged by the method of the present invention is repaired with this polyurethane coating, it can be repaired at low cost, and the service life can be improved. Very useful.

Claims (4)

A main agent (A) containing a terminal isocyanate group-containing urethane prepolymer, an active hydrogen-containing compound (B1), and a lead-free catalyst (B2) comprising a bismuth salt of an organic acid or a fatty acid bismuth salt having 8 to 20 carbon atoms. A concrete structure for use and drainage in which a polyurethane coating film obtained by curing a two-component curable polyurethane composition containing a curing agent (B) is formed on the surface.   The concrete structure for use and drainage according to claim 1, wherein the plasticizer used for the main agent and / or the curing agent is diisononyl adipate or fatty acid ester. At least on the surface of the concrete structure for use / drainage whose surface in contact with water is aged or damaged, a main agent (A) containing a terminal isocyanate group-containing urethane prepolymer, an active hydrogen-containing compound (B1), and an organic acid A two-component curable polyurethane composition comprising a bismuth salt or a curing agent (B) containing a lead-free catalyst (B2) composed of a fatty acid bismuth salt having 8 to 20 carbon atoms is applied by spraying, reacted and cured. A method of repairing a concrete structure for use and drainage, characterized by forming a polyurethane coating film.   The method for repairing a concrete structure for use and drainage according to claim 3, wherein the plasticizer used for the main agent and / or the curing agent is diisononyl adipate or fatty acid ester.