JPH1036658A - Waterproofing work for concrete structure by using flame-retardant urethane composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waterproofing work for a concrete structure excellent in workability in application and waterproofness after application by forming a waterproofing layer made from a one-package moisture-curing urethane composition comprising a specified polyurethane prepolymer, a curing agent and a flame retardant between concrete layers. SOLUTION: This work comprises forming a waterproofing layer between concrete layers in waterproofing a structure made of a concrete or the like. The waterproofing layer is made from a one-package flame-retardant moisture- curing urethane composition comprising a latent curing agent which forms an amine upon hydrolysis, an isocyanato-containing urethane prepolymer and a flame retardant. The curing agent is desirably a polyaldimine represented by the formula (X is a 6-15C aryl; Y is a 2-15C di- or tri-valent hydrocarbon group or a di- or tri-valent polyoxyalkylene group having a molecular weight of 70-6,000; and n is 2 or 3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a waterproof layer between a concrete layer and a concrete layer in order to impart waterproofness to a structure made of concrete or the like.
In particular, the present invention relates to a waterproofing method using a flame-retardant one-pack moisture-curable urethane composition containing a latent curing agent that produces an amine by hydrolysis, a polyurethane prepolymer having an isocyanate group, and a flame retardant as a waterproof layer.

[0002]

2. Description of the Related Art Tunnels such as traffic tunnels, water tunnels, and tunnels, or subways, underground passages, underground parking lots, underground shopping malls, underground shopping malls, underground power facilities, underground storage facilities, underground rainwater storage facilities, underground sewerage facilities, Various concrete underground structures such as underground space utilization facilities such as waste underground transportation facilities,
It is constantly exposed to pressurized groundwater. Therefore, in these concrete underground structures, there is a problem of water leakage from construction seams or cracks caused by external loads such as earthquakes and crustal deformation. As means for preventing this, a method of forming a waterproof layer between a concrete layer and a concrete layer by using a sheet of asphalt, synthetic rubber, synthetic resin, or the like is often used.

[0003] However, in this method, it takes a long time to spread the sheet and requires skill, and it is difficult to apply the method to a complicated shape. There is a problem that water is leaked due to a decrease in water tightness due to a cause such as tearing of the sheet due to pressing of the sheet or cutting of the sheet due to lack of ability to follow the crack of the concrete. In addition, since these sheets are flammable, when installing the waterproofing sheet, there is a risk of sparks and flames during welding, fusing, overheating of electric heaters, frictional heat of rotating equipment, fires due to sparks due to static electricity, etc. There is a risk of causing a serious accident.

[0004]

SUMMARY OF THE INVENTION To overcome the above-mentioned problems, that is, the workability at the time of construction is excellent, the reliability of the waterproofness of the waterproof layer after construction is high, and the waterproof function is maintained for a long time. There has been a strong demand for a waterproofing method for concrete structures that is held in place and has no danger of fire even when a waterproofing layer is constructed.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above problems, and as a result, when forming a waterproof layer, a polyurethane curing agent having an isocyanate group and a latent curing agent which generates an amine by hydrolysis. The inventors have found that the problem can be solved by applying a flame-retardant one-pack moisture-curable urethane composition containing a polymer and a flame retardant, and have completed the present invention.

That is, the present invention relates to (1) a method of forming a waterproof layer between a concrete layer and a concrete layer when imparting waterproofness to a structure made of concrete or the like. Concrete structure characterized by using a flame-retardant one-pack moisture-curable urethane composition containing a latent curing agent that produces an amine by the reaction, a polyurethane prepolymer having an isocyanate group, and a flame retardant (2) a latent curing agent which produces an amine by hydrolysis is represented by the following general formula (1)

[0007]

Embedded image Y-(— N ＝ CH—X) n (1) (wherein, X represents an aryl group having 6 to 15 carbon atoms).
Y represents a divalent or trivalent hydrocarbon group having 2 to 15 carbon atoms or a divalent or trivalent polyoxyalkylene group having a molecular weight of 70 to 6000. n represents 2 or 3. The method for waterproofing a concrete structure according to (1), wherein the polyaldimine is represented by
(3) The method for waterproofing a concrete structure according to (1) or (2), wherein the flame retardant is red phosphorus. (4) The content of red phosphorus in the composition is 0. 5-20
(5) The method for waterproofing a concrete structure according to (3), wherein the flame retardant is aluminum hydroxide or magnesium hydroxide (1) or (6) The concrete construction according to (5), wherein the content of aluminum hydroxide or magnesium hydroxide is 5 to 70% by weight in the composition. It provides a waterproofing method for structures.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, the flame-retardant one-pack moisture-curable urethane composition contains a latent curing agent which produces an amine by hydrolysis, a polyurethane prepolymer having an isocyanate group, and a flame retardant.

Potential curing agents which produce amines by hydrolysis include enamine (GB 1575666), polyaldimine or polyketimine (GB 10648).
41, German Patent 3,133,769, JP-A-2-28371
0, JP-A-4-279620), β-lactam (JP-A-2-168), oxazolidine (JP-A-2-5571)
5) and the like are known. In particular, JP-A-4-279620
The polyaldimine represented by the following general formula (1) [Chemical Formula 3] is a curable, storable, and cured product of a one-pack moisture-curable urethane composition containing the same as a latent curing agent. The balance of properties such as physical properties is excellent and most preferable.

[0010]

Embedded image Y-(— N ＝ CH—X) n (1) (wherein, X represents an aryl group having 6 to 15 carbon atoms).
Y represents a divalent or trivalent hydrocarbon group having 2 to 15 carbon atoms or a divalent or trivalent polyoxyalkylene group having a molecular weight of 70 to 6000. n represents 2 or 3. In the present invention, the polyaldimine represented by the general formula (1) is obtained by subjecting a polyamine and an aldehyde to a azeotropic dehydration reaction under an acid catalyst using a solvent such as toluene or xylene to separate water droplets. It is obtained by continuing the reaction until the distillation of water into the vessel stops.

Examples of the polyamine used for producing the polyaldimine represented by the general formula (1) include: 1) ethylenediamine, 1,3-diaminopropane, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, Aliphatic diamines such as octamethylenediamine and decamethylenediamine, 4,4′-diaminodicyclohexylmethane, isophoronediamine, bisaminomethylcyclohexane, 2,5- or 2,6-
Diamino methyl bicyclo [2.2.1] heptane, diaminocyclohexane, 3 (4), 8 (9) - bis (aminomethyl) - tricyclo [5.2.1.0 ^2.6] alicyclic diamines decane, Propylene oxide and / or aromatic diamine such as diaminodiphenylmethane, diaminodiphenylether, xylylenediamine, phenylenediamine, 3,5-diethyltoluene-2,4- or 2,6-diamine, water, ethylene glycol, propylene glycol, etc. Diamines such as polyoxyalkylene diamines obtained by converting hydroxyl groups of polyoxyalkylene glycols obtained by addition polymerization of ethylene oxide into amino groups, 2) 1,3,5-tris (aminomethyl) benzene,
Conversion of hydroxyl groups of polyoxyalkylene triols obtained by addition polymerization of propylene oxide and / or ethylene oxide to triamine such as 1,3,5-tris (aminomethyl) cyclohexane, glycerin, trimethylolpropane, etc., to amino groups And triamines such as polyoxyalkylene triamines.

The aldehyde to be reacted with the polyamine is, for example, benzaldehyde, o-tolualdehyde, m-tolualdehyde, p-tolualdehyde,
-Ethylbenzaldehyde, 4-propylbenzaldehyde, 4-butylbenzaldehyde, 2,4-dimethylbenzaldehyde, 2,4,5-trimethylbenzaldehyde, p-anisaldehyde, p-ethoxybenzaldehyde and the like.

In the present invention, a polyurethane prepolymer having an isocyanate group refers to a known polyisocyanate compound, a known polyol, a known polyamine, or a known compound having two or more active hydrogens in one molecule. The reaction is carried out so that free isocyanate groups remain by the method. That is, it is produced by reacting a polyisocyanate compound with a compound having active hydrogen at 100 ° C. for several hours. The isocyanate group content is 0.3 to
20.0% by weight is preferred, and a particularly preferred range is 0.5 to
15.0% by weight. The polyisocyanates used herein include: 1) tolylene diisocyanate (including various mixtures of isomers), diphenylmethane diisocyanate (including various mixtures of isomers), 3,3′-dimethyl-4,4′-
Biphenylene diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, naphthylene diisocyanate, dicyclohexyl methane 4.4'-diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated xylene diisocyanate, 1.4 -Cyclohexyl diisocyanate, 1
-Methyl-2,4-diisocyanato-cyclohexane,
Diisocyanates such as 2,4,4-trimethyl-1,6-diisocyanato-hexane; 2) tris such as 4,4 ', 4 "-triphenylmethane triisocyanate, tris (4-phenylisocyanato) thiophosphate; Isocyanates; 3) polyfunctional isocyanates such as urethane-modified isocyanates, isocyanurate-modified products, carbodiimidized-modified products, buret-modified products, crude tolylene diisocyanate, and polymethylene polyphenylisocyanate.

Further, the known compounds having two or more active hydrogens in one molecule as used herein include two or more hydroxyl groups, one or more amino groups, two or more mercapto groups, Or a compound having a hydroxyl group and an amino group, or a compound having a hydroxyl group and a mercapto group, such as water, ethylene glycol, propylene glycol, glycerin, trimethylolpropane,
Polyhydric alcohols such as pentaerythritol, sorbitol, sucrose or aniline, tolylenediamine, p, p '
Aromatic amines such as -diamino-diphenylmethane, aliphatic amines such as ethylenediamine, ethanolamine and diethanolamine, or alkanolamines, and compounds having two or more active hydrogens in one molecule thereof or a mixture of these compounds. Polyether polyols obtained by addition polymerization of propylene oxide or propylene oxide and ethylene oxide, polyether polyamines obtained by converting hydroxyl groups of the polyether polyols to amino groups, polytetramethylene ether polyols, polycarbonate Polyols, polycaprolactone polyols, polyester polyols such as polyethylene adipate, polybutadiene polyols, esters of higher fatty acids such as castor oil, Polymer polyols obtained by grafting a vinyl monomer to an ether polyol or polyester polyol, a compound obtained by copolymerizing a known ethylenically unsaturated monomer having at least one active hydrogen in one molecule, a mercapto group Ethers.

In the present invention, the latent curing agent and the polyurethane prepolymer having an isocyanate group are included in the number of amino groups of the polyamine formed by hydrolysis of the latent curing agent and the polyurethane prepolymer having an isocyanate group. The ratio with the number of isocyanate groups is
It is blended in a ratio of 0.5 to 2.0, preferably 0.7 to 1.5.

Examples of the flame retardant used in the present invention include brominated flame retardants such as decabromodiphenyl ether, octabromodiphenyl ether, tetrabromodiphenyl ether, hexabromocyclododecane, bistribromophenoxyethane, and ethylenebistetrabromophthalimide. Flame retardant, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, octyl diphenyl phosphate, tricresyl phosphate, cresyl phenyl phosphate, triphenyl phosphate, trichloroethyl phosphate, tris ( 2-chloropropyl) phosphate, tris (2,3-dichloropropyl) phosphate, polyphosphonate, polyphosphate , Tris (2,3-dibromopropyl) phosphate, tris (bromo-chloropropyl) phosphate, 2,3-dibromopropyl, 2,
Phosphorus flame retardants such as 3-chloropropyl phosphate, polyphosphate and red phosphorus; chlorine flame retardants such as chlorinated paraffin, perchlorocyclopentadecane and chlorinated biphenyl; antimony trioxide, antimony pentoxide, aluminum hydroxide Or a mixture of inorganic flame retardants such as magnesium hydroxide, calcium aluminate, zinc borate, barium metaborate, molybdenum oxide, ammonium molybdate, zirconium oxide, zirconium hydroxide, tin oxide, tin hydroxide, etc. In the composition in a maximum of 70% by weight, preferably 1 to 60% by weight. When the amount of the flame retardant is less than the above range, sufficient flame retardancy cannot be obtained, and when the amount is large, the mechanical strength of the cured product is significantly reduced or the properties of the composition are significantly different from the target. It tends to be less practical. Among them, red phosphorus, aluminum hydroxide, and magnesium hydroxide are particularly preferable because they emit a small amount of smoke at the time of fire and do not generate harmful halogen gas. Red phosphorus is present as elemental phosphorus when it is contained in the composition.When kneaded into the composition, the generated phosphoric acid component is used so that a redox reaction does not occur on the surface of the red phosphorus particles. In order to prevent moisture from adhering to the surface due to the hygroscopicity of the particles, and to prevent ignition by raising the temperature, it is preferable to knead a material in which the surface of the fine red phosphorus is coated with a resin, an inorganic substance, or the like. It is blended in the range of 0.5 to 20% by weight, preferably 1 to 15% by weight. When the amount of red phosphorus is less than the above range, sufficient flame retardancy cannot be obtained. Aluminum hydroxide and magnesium hydroxide are contained in the composition in an amount of 5 to 70% by weight, preferably 10 to 70% by weight.
It mix | blends in the range of 60 weight%. If the compounding amount is less than the above range, sufficient flame retardancy cannot be obtained, and if the compounding amount is too large, the mechanical strength of the cured product is significantly reduced, or the property of the composition is far from the target and is poor in practicality. Becomes As a measure of flame retardancy, it is necessary to exhibit self-extinguishing properties, and it is necessary to show an oxygen index of 23 or more in a flame retardancy test.

The flame-retardant one-pack moisture-curable urethane composition used in the present invention is a filler, a thixotropy-imparting agent, a plasticizer, a solvent, an adhesion-imparting agent for controlling viscosity, resin properties, resistance and curing speed. Agents, coloring agents, stabilizers, fungicides, organic acids and the like can be used in combination. There is no particular limitation on the method of blending these, and simply mixing or other known methods such as a flame retardant, a filler, a plasticizer, a thixotropic agent, and other necessary additives such as The product may be stirred and mixed using a mixer such as a planetary mixer or a dissolver, and then a polyurethane prepolymer having an isocyanate group and a latent curing agent may be added and sufficiently mixed. When the water content of various additives is high, it is necessary to perform dehydration in advance or to add a dehydrating agent such as zeolite. The obtained flame-retardant one-part moisture-curable urethane composition is stored in a sealed can in a nitrogen stream.

The waterproofing method according to the present invention is characterized by using the above-mentioned flame-retardant one-part moisture-curable urethane composition, and its working method can be carried out according to a conventional method.
For example, a flame-retardant one-component moisture-curable urethane composition is sprayed on a concrete wall surface, and after the composition is cured, concrete is applied from above. The spraying of the flame-retardant one-part moisture-curable urethane composition can be carried out using a small spray device such as a spray gun for construction or a large-sized pressure-feeding device for construction finishing material. The coating thickness per application is preferably in the range of 0.5 mm to 5 mm, more preferably in the range of 1.0 mm to 3 mm. When the coating thickness is smaller than this, the waterproof layer has poor followability with respect to cracks in the concrete, so that it is difficult to secure water tightness for a long period of time, and when it is thicker, the sprayed composition drips. In this method, groundwater drainage measures may be provided. For example, as in the NATM construction method, after excavating the ground, spraying concrete is applied, and a permeable layer is provided on the concrete to allow the leakage of groundwater from cracks in the concrete. The waterproofing layer can be formed by uniformly spraying a one-part moisture-curable urethane composition, and after the composition is cured, it can be used for a method of lining with concrete.

[0019]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In Examples and Comparative Examples, parts are parts by weight unless otherwise specified. Flame retardancy is JIS K7
201 was evaluated. That is, the flame-retardant one-part moisture-curable urethane composition was applied to a thickness of 3 mm, and was heated at 23 ° C. and 50% R.
After being left to cure in H for 14 days, the resulting cured product sheet was measured for oxygen index.

The crack followability is 120 mm wide x 200 m long
m, 8 mm-thick two slate plates are vertically abutted on each other and a flame-retardant one-part moisture-curable urethane composition
It was applied to a thickness of 23 mm, cured at 23 ° C. and 50% RH for 14 days, and then pulled longitudinally at a rate of 5 mm / min by a tensile tester to measure the elongation at the time of cutting the coating film.

Example 1 According to JP-A-4-279620, tetramethylenediamine and p-tolualdehyde were subjected to a dehydration condensation reaction to obtain dialdimine A-1 (amine value: 381 mgKOH / g).
Next, 598 parts of 2,4-tolylene diisocyanate,
Polyoxypropylene glycol (molecular weight 2000) 2
600 parts and 1802 parts of polyoxypropylene triol (molecular weight 3000) were reacted at 100 ° C. for 10 hours to obtain a polyurethane prepolymer having an isocyanate group. The terminal NCO groups of the prepolymer were 1.89% by weight.

In a 3 liter planetary mixer, 200 parts of dioctyl phthalate, 450 parts of calcium carbonate previously dried, 200 parts of red phosphorus, 700 parts of polyurethane prepolymer, 42 parts of dialdimine (A-1), an adhesion promoter (Nihon Unicar (Glycidoxypropyltrimethoxysilane: trade name: A-187) (10 parts) and the mixture was stirred at room temperature for 30 minutes. Next, a thixotropic agent (hydrophobic silica manufactured by Nippon Aerosil Co., Ltd .: trade name Aerosil # R-97)
2) 50 parts of xylene and 150 parts of xylene were inserted, and the mixture was stirred at room temperature under reduced pressure for 20 minutes to obtain a flame-retardant one-part moisture-curable urethane composition of the present invention.

The elongation of this flame-retardant one-part moisture-curable urethane composition in a crack following test is as excellent as 11 mm, and it sufficiently fulfills a waterproof function over a long period of time. The oxygen index was 25. In addition, the flame-retardant one-part moisture-curable urethane composition is applied to a vertically erected 1 m × 1 m slate plate surface with a thickness of about 2 mm using a spray gun for construction. When the cured product was observed the next day, it was found to be uniform without foaming or sagging.

Example 2 According to JP-A-4-279620, about 60
% And diaminomethylbicyclo [2.2.1] heptane, which is a mixture of about 40% of 2,6-isomer, and benzaldehyde were subjected to a dehydration condensation reaction to obtain dialdimine A-2 (amine value: 337 mgKOH / g).

In a 3 liter planetary mixer, 200 parts of dioctyl phthalate, 600 parts of aluminum hydroxide previously dried, 150 parts of red phosphorus, 700 parts of the polyurethane prepolymer used in Example 1, dialdimine (A)
-2) 48 parts and 10 parts of an adhesion-imparting agent (A-187) were inserted, and the mixture was stirred at room temperature for 30 minutes. Next, 50 parts of a thixotropy-imparting agent (R-972) and 150 parts of xylene were inserted, and the mixture was stirred at room temperature under reduced pressure for 20 minutes to obtain a flame-retardant one-pack moisture-curable urethane composition of the present invention.

The flame retardant one-part moisture-curable urethane composition has an excellent elongation of 11 mm in a crack following test, and exhibits a sufficient waterproof function over a long period of time. The oxygen index was 27. In addition, the flame-retardant one-part moisture-curable urethane composition is applied to a vertically erected 1 m × 1 m slate plate surface with a thickness of about 2 mm using a spray gun for construction. When the cured product was observed the next day, it was found to be uniform without foaming or sagging.

Example 3 Polyoxypropylene triamine (Texaco Chemical Com) was prepared according to JP-A-4-279620.
pany, trademark: JEFFAMINE T-403,
(Molecular weight: 440) and p-isopropylbenzaldehyde by a dehydration condensation reaction to give a trialdimine A-3 (amine value 3).
04 mg KOH / g).

In a 3 liter planetary mixer, 200 parts of dioctyl phthalate, 650 parts of magnesium hydroxide previously dried, 700 parts of the polyurethane prepolymer used in Example 1, and trialdimine (A-3) 53
And 10 parts of the adhesion-imparting agent (A-187) were inserted and stirred at room temperature for 30 minutes. Next, a thixotropic agent (R-97)
2) 50 parts of xylene and 150 parts of xylene were inserted, and the mixture was stirred at room temperature under reduced pressure for 20 minutes to obtain a flame-retardant one-part moisture-curable urethane composition of the present invention.

The elongation of the flame-retardant one-part moisture-curable urethane composition in a crack following test is as excellent as 8 mm, and it sufficiently fulfills a waterproof function over a long period of time. The oxygen index was 23. In addition, the flame-retardant one-part moisture-curable urethane composition is applied to a vertically erected 1 m × 1 m slate plate surface with a thickness of about 2 mm using a spray gun for construction. When the cured product was observed the next day, it was found to be uniform without foaming or sagging.

Example 4 1,4-bis {3,3-dimethyl-2-oxo-1- [3- (2- (2-ethoxyethoxy) ethoxycarbonylaminomethyl) benzyl] according to JP-A-2-168
Azetidin-4-yl dipiperazine was synthesized to obtain β-lactam A-4 (amine value: 133 mgKOH / g).

In a 3 liter planetary mixer, 200 parts of tris (2-chloropropyl) phosphate, 650 parts of calcium carbonate previously dried, 700 parts of the polyurethane prepolymer used in Example 1, β-lactam (A-4 ) 121 parts and 10 parts of an adhesion-imparting agent (A-187) were inserted and stirred at room temperature for 30 minutes. Next, 50 parts of a thixotropy-imparting agent (R-972) and 150 parts of xylene were inserted, and the mixture was stirred at room temperature under reduced pressure for 20 minutes to obtain a flame-retardant one-pack moisture-curable urethane composition of the present invention.

The elongation of the flame-retardant one-part moisture-curable urethane composition in a crack following test was as excellent as 35 mm, and it sufficiently fulfilled a waterproof function over a long period of time. The oxygen index was 24. In addition, the flame-retardant one-part moisture-curable urethane composition is applied to a vertically erected 1 m × 1 m slate plate surface with a thickness of about 2 mm using a spray gun for construction. When the cured product was observed the next day, it was found to be uniform without foaming or sagging.

Example 5 In a 3 liter planetary mixer, 200 parts of tris (2-chloropropyl) phosphate, 250 parts of magnesium hydroxide previously dried, 400 parts of calcium carbonate
Part, 50 parts of red phosphorus, 700 parts of the polyurethane prepolymer used in Example 1, bisoxazolidine (manufactured by MILES, trade name: HARDENER OZ, amine value: 23)
0 mgKOH / g) 70 parts, adhesion-imparting agent (A-187)
10 parts were inserted and stirred at room temperature for 30 minutes. Next, 50 parts of a thixotropy-imparting agent (R-972) and 150 parts of xylene were inserted, and the mixture was stirred at room temperature under reduced pressure for 20 minutes to obtain a flame-retardant one-pack moisture-curable urethane composition of the present invention.

The flame retardant one-part moisture-curable urethane composition has an excellent elongation of 10 mm in a crack following test, and sufficiently fulfills a waterproof function over a long period of time. The oxygen index was 27. In addition, the flame-retardant one-part moisture-curable urethane composition is applied to a vertically erected 1 m × 1 m slate plate surface with a thickness of about 2 mm using a spray gun for construction. When the cured product was observed the next day, it was found to be uniform without foaming or sagging.

Comparative Example 1 In a 3 liter planetary mixer, 200 parts of dioctyl phthalate and 650 calcium carbonate dried in advance were mixed.
Part, polyurethane prepolymer 70 used in Example 1
0 parts, 10 parts of an adhesion-imparting agent (A-187), and 2 parts of dibutyltin dilaurate as a curing accelerator were inserted, and the mixture was stirred at room temperature for 30 minutes. Next, a thixotropic agent (R-972)
Insert 50 parts of xylene and 150 parts of xylene.
The mixture was stirred for 0 minutes to obtain a one-part moisture-curable urethane composition.

The one-part moisture-curable urethane composition is applied to a vertically slated 1 m × 1 m slate plate surface at a thickness of about 2 mm using a spray gun for construction, and cured the next day. Upon observing the object, it was found that it was foaming violently and could not fulfill the waterproof function at all. The oxygen index in the flame retardancy test was 18, indicating that the composition was flammable.

Comparative Example 2 200 parts of dioctyl phthalate was placed in a 3 liter planetary mixer, and calcium carbonate 650 was dried in advance.
Part, polyurethane prepolymer 70 used in Example 1
0 parts, dialdimine (A-1) 42 parts, adhesion-imparting agent (A
187), and stirred at room temperature for 30 minutes.
Next, 50 parts of a thixotropy-imparting agent (R-972) and 150 parts of xylene were inserted, and the mixture was stirred at room temperature under reduced pressure for 20 minutes to obtain a one-part moisture-curable urethane composition. The oxygen index in the flame retardancy test of this one-part moisture curable urethane composition was 18, indicating that it was flammable. Next, an embodiment of the present invention in the NATM method will be described as an example of a waterproofing method for a concrete structure.

Example 6 After excavating a tunnel in the ground by a known method, concrete is sprayed on the excavated surface to form primary sprayed concrete. During this time, the work of placing a lock bolt, which is usually performed in the known NATM method, and other works are performed. After the primary shotcrete is cured, the waterproof layer is formed by spraying the flame-retardant one-part moisture-curable urethane composition of the present patent. After confirming that the waterproof layer has hardened and there is no water leakage,
A mold is assembled at an appropriate distance from the waterproof layer, and concrete is poured between the mold and the waterproof layer and hardened to form a secondary lining concrete.

In the above description, the case of the NATM method for tunnel construction has been described. However, in the case where the primary concrete is precast concrete such as cement or box culvert or concrete cast in formwork, the secondary concrete is sprayed concrete or cement. It is also applicable to cases and the like.

[0040]

According to the present invention, in imparting waterproofness to a structure made of concrete or the like, in a method of forming a waterproof layer between concrete layers, the waterproof layer is hydrolyzed. The use of a flame-retardant one-part moisture-curable urethane composition containing a latent curing agent that generates amines, a polyurethane prepolymer having an isocyanate group, and a flame retardant makes it possible to work during the construction of a waterproof layer. Excellent fire resistance and no risk of fire accident,
High reliability for water tightness of waterproof layer hardened after construction,
A waterproofing method for a concrete structure in which the waterproofing function is maintained for a long time can be obtained.

More specifically, in the waterproofing method of the present invention, the one-pack type urethane composition used for forming the waterproof layer is simple in construction work and has a constant viscosity during construction. Since the state becomes uniform and there is no stirring and mixing work that is performed when a two-pack type is applied, there is an advantage that there is no problem of poor curing and uniform cured physical properties can be obtained. And, since the waterproof layer is formed by a coating film, there is no joint portion in the sheet method, and further, when the coating film is cured, there is no generation of carbon dioxide gas as in the conventional moisture-curable urethane composition. Therefore, there is no defective portion due to foaming and the like, so that it has excellent watertightness, and the danger of fire accident can be avoided because of the flame-retardant waterproof layer. In addition, the excellent rubber elasticity and cold resistance of the urethane resin show excellent performance in conforming to cracks in concrete and durability against cooling and heating cycles, so that the function of the waterproof layer is maintained for a long period of time. .

Claims (6)

[Claims] 1. A method for forming a waterproof layer between a concrete layer and a concrete layer when imparting waterproofness to a structure made of concrete or the like. A waterproofing method for a concrete structure, comprising using a flame-retardant one-pack moisture-curable urethane composition containing a curing agent, a polyurethane prepolymer having an isocyanate group, and a flame retardant. 2. The latent curing agent which produces an amine by hydrolysis is represented by the following general formula (1): ## STR1 ## Y-(-N = CH-X) n (1) , X represents an aryl group having 6 to 15 carbon atoms.
Y represents a divalent or trivalent hydrocarbon group having 2 to 15 carbon atoms or a divalent or trivalent polyoxyalkylene group having a molecular weight of 70 to 6000. n represents 2 or 3. 2. The waterproofing method for a concrete structure according to claim 1, wherein the polyaldimine is represented by the following formula: 3. The method for waterproofing a concrete structure according to claim 1, wherein the flame retardant is red phosphorus. 4. The method for waterproofing a concrete structure according to claim 3, wherein the content of red phosphorus is 0.5 to 20% by weight in the composition. 5. The method for waterproofing a concrete structure according to claim 1, wherein the flame retardant is aluminum hydroxide or magnesium hydroxide. 6. The method for waterproofing a concrete structure according to claim 5, wherein the content of aluminum hydroxide or magnesium hydroxide is 5 to 70% by weight in the composition.