Polyol composition and non-foaming urethane resin

Abstract

The present invention provides a non-foaming urethane resin for reinforcing existing hollow columns, which can be easily filled without causing uneven density distribution, is less prone to uneven reinforcement, and has sufficient strength, as well as a polyol composition used in its manufacture. [Solution] A polyol composition for producing a non-foaming urethane resin for reinforcing existing hollow columns without using aggregate, comprising a polyol and a urethane catalyst, wherein the polyol includes a polyether polyol, has an average hydroxyl value of 250 to 450 mgKOH / g, and the non-foaming urethane resin has a compressive strength of 15 to 100 MPa as measured in accordance with JIS K 6911:1995.

Description

Technical Field

[0001] The present invention relates to a polyol composition for producing a non-foamed urethane resin and a non-foamed urethane resin for reinforcing an existing hollow column damaged by deterioration.

Background Art

[0002] Existing hollow columns such as hollow concrete utility poles may develop cracks and peeling due to aging deterioration since installation, leading to serious accidents such as breakage and collapse.

[0003] As one of the methods for repairing and reinforcing utility poles to prevent such accidents, a method of supplying a reinforcing material in which a resin and a filler as an aggregate are mixed into the hollow part inside the utility pole is known (for example, Patent Document 1). In addition, a method of filling and expanding a foamed urethane resin into the hollow part inside the utility pole has also been proposed (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the method of supplying the reinforcing material as described in Patent Document 1, it is difficult to uniformly mix the resin and the filler as the aggregate, and uneven reinforcement is likely to occur. In addition, while the operations such as the preparation and handling of the aggregate become complicated, sufficient reinforcing strength could not be obtained due to the curing shrinkage of the resin when the aggregate was not used.

[0006] On the other hand, in the reinforcement method using foamed urethane resin as described in Patent Document 2, the porosity of the resin filling the hollow part inside the utility pole is high, which tends to cause unevenness in the density distribution of the resin, and in this case as well, uneven reinforcement tends to occur. In addition, the resin density is low, and sufficient reinforcement strength cannot be obtained.

[0007] Therefore, there was a need for a reinforcing material that could be easily and uniformly filled into existing hollow columns, and that could evenly reinforce them with sufficient strength to prevent breakage or collapse of the existing hollow columns.

[0008] This invention has been made in view of the above circumstances, and aims to provide a non-foaming urethane resin for reinforcing existing hollow columns, which can be easily filled without causing uneven density distribution, is less prone to uneven reinforcement, and provides sufficient reinforcement strength, as well as a polyol composition used in its manufacture. [Means for solving the problem]

[0009] This invention is based on the discovery that hollow columns can be easily reinforced with sufficient strength without using aggregates by using a non-foaming urethane resin manufactured using a predetermined polyol composition.

[0010] The present invention provides the following means. [1] A polyol composition for the production of a non-foaming urethane resin for reinforcing existing hollow columns without using aggregate, comprising a polyol and a urethane catalyst, wherein the polyol comprises a polyether polyol, has an average hydroxyl value of 250 to 450 mgKOH / g, and the non-foaming urethane resin has a compressive strength of 15 to 100 MPa as measured in accordance with JIS K 6911:1995. [2] The polyol composition of [1], wherein the non-foaming urethane resin has a bending strength of 25 to 120 MPa as measured in accordance with JIS K 6911:1995. [3] The polyol composition of [1] or [2], wherein the non-foaming urethane resin has a flexural modulus of 450 to 3000 MPa as measured in accordance with JIS K 6911:1995. [4] A polyol composition according to any of [1] to [3], wherein the non-foaming urethane resin has a bending deflection of 3.0 to 25.0 mm as measured in accordance with JIS K 6911:1995. [5] A polyol composition containing a dehydrating agent, any of [1] to [4]. [6] A polyol composition according to any of [1] to [5], wherein the polyol comprises a polyether polyol having a hydroxyl value of 20 to 100 mg KOH / g and a polyether polyol having a hydroxyl value of 300 to 600 mg KOH / g. [7] A polyol premix, which is any of the polyol compositions from [1] to [6]. A non-foaming urethane resin, which is a reaction product of one of the polyol compositions [8][1] to [7] and a polyisocyanate. [Effects of the Invention]

[0011] By using the polyol composition of the present invention, it is possible to provide a non-foaming urethane resin for reinforcing existing hollow columns that is less prone to uneven density distribution, can be easily filled, is less prone to uneven reinforcement, and has sufficient reinforcing strength. The non-foaming urethane resin of the present invention can be suitably used as a filling material for reinforcing existing hollow columns to prevent breakage, collapse, and other damage. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram illustrating the pole bending test in the embodiment. [Modes for carrying out the invention]

[0013] The definitions and meanings of terms and notations used in this specification are given below. Non-foaming polyurethane resin means that it is not foamed polyurethane resin, and refers to polyurethane resin that is not intended to contain air bubbles through the addition of foaming agents or forced foaming. Air bubbles that are unavoidable due to the incorporation of air are not considered foaming. Numerical ranges expressed using "~" indicate that the numbers before and after "~" are the lower and upper limits. For numerical ranges (e.g., ranges of content, etc.), the lower and upper limits described in stages may be combined independently. The lower and upper limits of a numerical range may be replaced with the numbers described in the examples. The isocyanate index is the percentage of moles of isocyanate groups in polyisocyanate relative to 1 mole of hydroxyl groups in the urethane resin raw material liquid. The number of moles of hydroxyl groups in the polyol is based on the average hydroxyl value of the polyol.

[0014] [Polyol composition] The polyol composition of the present invention is a polyol composition for producing a non-foaming urethane resin for reinforcing existing hollow columns without using aggregate, and comprises a polyol and a urethane catalyst, wherein the polyol comprises a polyether polyol, has an average hydroxyl value of 250 to 450 mgKOH / g, and the non-foaming urethane resin has a compressive strength of 15 to 100 MPa as measured in accordance with JIS K 6911:1995.

[0015] Even if existing hollow columns pose a risk of breakage or collapse due to deterioration over time since their installation, immediate replacement may be difficult, and emergency measures such as repair or reinforcement may be implemented. The polyol composition of the present invention can be suitably used in the production of non-foaming urethane resin for reinforcing such existing hollow columns.

[0016] Existing hollow columns are not limited in material, but examples include concrete columns, metal columns such as steel or aluminum, stone columns, and wooden columns. The polyol composition of the present invention is particularly suitable for reinforcing existing hollow columns made of concrete in order to prevent breakage or collapse of hollow columns.

[0017] The shape of the existing hollow column is not particularly limited, and for example, it may be cylindrical or prismatic, and may also be tapered with a constant diameter or with a diameter expanding from the distal end (tip) toward the proximal end (base). The size of the existing hollow column 1 is not particularly limited, and usually, it may be a size suitable for building columns. For example, in the case of a concrete utility pole, those with a length of 7 to 17 m, a distal end diameter (upper part) of 14 to 19 cm, and a proximal end diameter (bottom part) of 23 to 40 cm are common.

[0018] The polyol composition according to one embodiment of the present invention (hereinafter referred to as "this embodiment") contains a polyol and a urethanization catalyst. From the viewpoints of mixing homogeneity and ease of manufacturing a non-foamed urethane resin, the polyol composition is preferably liquid at room temperature (20°C).

[0019] Since the polyol composition of this embodiment is used for manufacturing a non-foamed urethane resin for reinforcing an existing hollow column without using an aggregate, it does not contain an aggregate. The urethane resin raw material liquid produced using the polyol composition of this embodiment also does not contain an aggregate, and when reinforcing an existing hollow column, an aggregate for reinforcing the non-foamed urethane resin is not used in combination. By not using an aggregate, the working burden of mixing the polyol composition and the urethane resin raw material liquid to be uniform is reduced, and it is difficult for a deviation in the density distribution of the filled resin to occur. In the present invention, the aggregate refers to a solid substance (for example, powders such as silica and alumina, glass fibers, resin or metal short fibers, etc.) blended for the purpose of reinforcing the resin filled in the existing hollow column. The aggregate does not include fillers (filler materials) for cost reduction or volume increase, and solid additives not intended for a reinforcing effect.

[0020] The content of the polyol in the polyol composition is preferably 50.0 to 90.0 parts by mass, more preferably 55.0 to 85.0 parts by mass, and still more preferably 60.0 to 80.0 parts by mass with respect to 100 parts by mass of the polyol composition in order to obtain a non-foamed urethane resin having good strength characteristics.

[0021] As the polyol, a compound having two or more hydroxyl groups in one molecule and capable of producing polyurethane through reaction with a polyisocyanate is used. The polyol may be used alone or in combination of two or more types. In this embodiment, the polyol includes a polyether polyol from the viewpoint of obtaining a non-foaming urethane resin with good strength properties. The polyol may include polyols other than polyether polyols, such as polyester polyols, polylactone polyols, polycarbonate polyols, polymer polyols, and the like.

[0022] From the viewpoint of obtaining a non-foaming urethane resin with good strength properties, the content of polyether polyol in the polyol is preferably 90.0 to 100 parts by mass, more preferably 95.0 to 100 parts by mass, and even more preferably 100 parts by mass, per 100 parts by mass of polyol.

[0023] Examples of polyether polyols include polymers obtained by ring-opening polymerization of alkylene oxides such as ethylene oxide and propylene oxide, or tetrahydrofuran, to an initiator having two or more active hydrogen atoms in one molecule. Examples of initiators include diols such as ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, and bisphenol A; triols such as glycerin and trimethylolpropane; tetraols such as pentaerythritol; and amines such as ethylenediamine and butylenediamine.

[0024] Examples of polyester polyols include polymers obtained by dehydration condensation of polybasic acids (e.g., adipic acid, azelaic acid, sebacic acid, isophthalic acid, terephthalic acid, succinic acid, etc.) and diols (e.g., bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexane glycol, neopentyl glycol, etc.), and condensates of hydroxycarboxylic acids (castor oil, reaction products of castor oil and ethylene glycol, etc.) and the aforementioned diols.

[0025] Examples of polylactone polyols include polypropiolactone glycol, polycaprolactone glycol, and polyvalerolactone glycol.

[0026] Examples of polycarbonate polyols include polyols obtained by the de-alcoholization reaction of aliphatic polyols (e.g., ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, nonanediol, etc.) with carbonates (e.g., ethylene carbonate, propylene carbonate, etc.).

[0027] Examples of polymer polyols include polymers obtained by graft polymerization of ethylenically unsaturated compounds (e.g., acrylonitrile, styrene, methyl acrylate, methacrylate, etc.) onto aromatic polyols (e.g., bisphenol A, bisphenol F, phenol novolac, cresol novolac, etc.), alicyclic polyols (e.g., cyclohexanediol, methylcyclohexanediol, isophoronediol, dicyclohexylmethanediol, dimethyldicyclohexylmethanediol, etc.), aliphatic polyols, polyester polyols, etc.; polybutadiene polyols; and hydrogenated versions thereof.

[0028] The polyol has an average hydroxyl value of 250 to 450 mg KOH / g, preferably 255 to 430 mg KOH / g, and more preferably 260 to 410 mg KOH / g. If the average hydroxyl value of the polyol is 250 mgKOH / g or higher, a non-foaming urethane resin with good strength properties can be obtained. Furthermore, if the average hydroxyl value is 450 mgKOH / g or lower, the polyol composition is easily obtained with a viscosity that is easy to handle.

[0029] Since polyols readily yield non-foaming urethane resins with good strength properties, it is preferable to use a mixture of two or more polyether polyols within the range of the above average hydroxyl value, and it is preferable to include a polyether polyol with a hydroxyl value of 20 to 100 mg KOH / g and a polyether polyol with a hydroxyl value of 300 to 600 mg KOH / g. More preferably, the polyol includes a polyether polyol with a hydroxyl value of 20 to 70 mg KOH / g and a polyether polyol with a hydroxyl value of 330 to 570 mg KOH / g, and even more preferably, a polyether polyol with a hydroxyl value of 20 to 50 mg KOH / g and a polyether polyol with a hydroxyl value of 360 to 540 mg KOH / g. The hydroxyl value of polyols is determined by measurement in accordance with JIS K 1557-1:2007. When two or more polyols are used in combination, in this specification, the weighted average value based on the mass of each polyol is considered to be the average hydroxyl value of the polyols.

[0030] The urethane catalyst contained in the polyol composition of this embodiment is a catalyst that promotes the reaction between the polyol and the polyisocyanate. The urethane catalyst may be used alone or in combination of two or more types. Examples of urethane catalysts include amine catalysts; organo-bismuth compounds, organotin compounds, and organometallic catalysts such as acetylacetone metal salts. The catalyst may be used alone or in combination of two or more types. Of these, amine catalysts are preferred from the viewpoint of ease of handling, etc. The polyol composition may also contain a trimerizing catalyst.

[0031] From the viewpoint of appropriate reactivity, the content of the urethane catalyst in the polyol composition is preferably 0.005 to 0.5 parts by mass, more preferably 0.01 to 0.2 parts by mass, and even more preferably 0.02 to 0.1 parts by mass, per 100 parts by mass of polyol.

[0032] Examples of amine catalysts include pentamethyldiethylenetriamine, triethylamine, N-methylmorpholine bis(2-dimethylaminoethyl) ether, bis(2-dimethylaminoethyl) ether, N,N,N',N”,N”-pentamethyldiethylenetriamine, N,N,N'-trimethylaminoethyl-ethanolamine, bis(2-dimethylaminoethyl) ether, N-methyl-N',N'-dimethylaminoethylpiperazine, N,N-dimethylcyclohexylamine, diazabicycloundecene, triethylenediamine, tetramethylethylenediamine, tetramethylhexamethylenediamine, trimethylaminoethylpiperazine, tripropylamine; and imidazole compounds such as 1-methylimidazole, 1,2-dimethylimidazole, and 1-isobutyl-2-methylimidazole. From the viewpoint of controlling the reaction rate appropriately, imidazole compounds are preferred as amine catalysts, and among them, 1-isobutyl-2-methylimidazole is more preferred.

[0033] Examples of organometallic catalysts include organobismuth compounds such as bismuth 2-ethylhexanoate, bismuth neodecanoate, and bismuth octoate. Examples of organotin compounds include stannous octoate, dibutyltin diacetate, and dibutyltin dilaurate. Examples of acetylacetone metal salts include aluminum acetylacetone, iron acetylacetone, copper acetylacetone, zinc acetylacetone, beryllium acetylacetone, chromium acetylacetone, indium acetylacetone, manganese acetylacetone, molybdenum acetylacetone, titanium acetylacetone, cobalt acetylacetone, vanadium acetylacetone, and zirconium acetylacetone.

[0034] The polyol composition of this embodiment preferably contains an antifoaming agent to suppress foaming and facilitate the acquisition of a non-foaming urethane resin. Generally, compounds with an HLB value of about 1 to 3, which represents the hydrophilic-lipophilic balance, are used as antifoaming agents. Examples of antifoaming agents include silicone-based antifoaming agents (oil type, compound type, self-emulsifying type, emulsion type, etc.), fatty acid esters, metal soaps, phosphate esters, nonionic surfactants, etc. The antifoaming agent may be used alone or in combination of two or more. Of these, silicone-based antifoaming agents are preferred from the viewpoint of good foam suppression.

[0035] The amount of defoaming agent in the polyol composition is preferably 0.1 to 2.0 parts by mass, more preferably 0.2 to 1.0 parts by mass, and even more preferably 0.3 to 0.7 parts by mass, per 100 parts by mass of polyol, from the viewpoint of suppressing foaming of the non-foaming urethane resin and providing good strength characteristics.

[0036] In order to obtain a non-foaming urethane resin with good strength properties, the polyol composition of this embodiment preferably contains substantially no foaming agent. Here, "substantially" means that, if the polyol composition contains water, the amount of water does not act as a foaming agent. Specifically, if the polyol composition contains a dehydrating agent, the water content is 20.0 parts by mass or less, preferably 15.0 parts by mass or less, per 100 parts by mass of the dehydrating agent. If the polyol composition does not contain a dehydrating agent, it means that it does not contain water as a foaming agent, excluding water that may be unavoidably included or included as a medium for the compounding components. Therefore, from the viewpoint of suppressing the action of water contained in the polyol composition as a foaming agent, it is preferable that the polyol composition contains a dehydrating agent.

[0037] Examples of dehydrating agents include zeolite, silica gel, calcium oxide, activated carbon, potassium hydroxide, sodium hydroxide, and lithium hydroxide. The dehydrating agent may be used alone or in combination of two or more. Of these, zeolite is preferred from the viewpoint of ease of handling.

[0038] If the polyol composition contains a dehydrating agent, its content is preferably 0.1 to 20.0 parts by mass, more preferably 1.0 to 15.0 parts by mass, and even more preferably 5.0 to 10.0 parts by mass, per 100 parts by mass of polyol, from the viewpoint of suppressing foaming of the non-foamed urethane resin and providing good strength characteristics.

[0039] The polyol composition of this embodiment preferably contains a flame retardant from the viewpoint of imparting flame retardancy to the non-foaming urethane resin. As the flame retardant, a liquid flame retardant that is liquid at room temperature (20°C) is preferred from the viewpoint of making the polyol composition easy to handle.

[0040] Examples of flame retardants include monophosphate esters and condensed phosphate esters. The flame retardant may be used alone or in combination of two or more types. Of these, monophosphate esters are preferred. Examples of monophosphate esters include trialkyl phosphates such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, and tri(2-ethylhexyl) phosphate; halogen-containing phosphate esters such as tris(β-chloropropyl) phosphate; trialkoxy phosphates such as tributoxyethyl phosphate; and aromatic ring-containing phosphate esters such as tricresyl phosphate, trixylenyl phosphate, tris(isopropylphenyl) phosphate, cresyldiphenyl phosphate, and diphenyl(2-ethylhexyl) phosphate. Among these, halogen-containing phosphate esters such as tris(β-chloropropyl) phosphate are preferred.

[0041] If the polyol composition contains a flame retardant, the amount is preferably 5.0 to 50.0 parts by mass, more preferably 5.0 to 30.0 parts by mass, and even more preferably 10.0 to 20.0 parts by mass, per 100 parts by mass of polyol, from the viewpoint of flame retardancy and good strength characteristics of the non-foamed urethane resin.

[0042] The polyol composition of this embodiment preferably contains a viscosity reducer, from the viewpoint of making the polyol composition easy to handle and easy to mix with polyisocyanate. As the viscosity reducer, a polyether compound having a structure in which one or both hydroxyl groups at one end of a polyoxyalkylene glycol are replaced with an alkoxy group or alkylene oxy group having 3 or more carbon atoms is preferred. When both hydroxyl groups at both ends are replaced, the replaced alkoxy group or alkylene oxy group may be the same or different. Examples of viscosity reducers include polyoxypropylene monobutyl ether, triethylene glycol monobutyl ether, polyoxyethylene polyoxypropylene monobutyl ether, and polyoxyethylene monobutyl ether. The viscosity reducer may be used alone or in combination of two or more. Of these, triethylene glycol monobutyl ether is preferred.

[0043] If the polyol composition contains a viscosity reducer, its content is preferably 1.0 to 25.0 parts by mass, more preferably 5.0 to 25.0 parts by mass, and even more preferably 10.0 to 20.0 parts by mass, per 100 parts by mass of the polyol composition, from the viewpoint of ease of handling of the polyol composition and ease of mixing with polyisocyanate.

[0044] The polyol composition of this embodiment may contain other additives as needed, within a range that does not impair good miscibility with polyisocyanate and good strength properties of the non-foaming urethane resin. Examples of other additives include trimerizing catalysts, antioxidants (phenol-based, amine-based, sulfur-based, etc.), heat stabilizers, antistatic agents, stabilizers, crosslinking agents, lubricants, softeners, and pigments. These additives may be used individually or in combination of two or more. However, from the viewpoint of preventing uneven density distribution of the non-foaming urethane resin, it is preferable not to include fillers (fillers) for cost reduction or bulk increase.

[0045] The polyol composition of this embodiment may be prepared by mixing each component of the polyol composition at the site where the existing hollow column is reinforced. However, from the viewpoint of reducing the workload at the site and ease of handling, it is preferable to use a polyol premix in which each component is pre-mixed at the site.

[0046] The polyol composition of this embodiment has a compressive strength of 15 to 100 MPa, preferably 20 to 90 MPa, and more preferably 25 to 80 MPa, measured in accordance with JIS K 6911:1995 for a non-foaming urethane resin produced using it. If the compressive strength of the non-foaming polyurethane resin is within the above range, it is possible to effectively reinforce existing hollow columns while suppressing the risk of breakage or collapse. If the compressive strength is 15 MPa or higher, the pole has sufficient strength against bending, and if it is 100 MPa or lower, the deflection of the pole when bending is moderate, making it easier to suppress breakage and collapse.

[0047] The bending strength of the non-foaming urethane resin produced using the polyol composition of this embodiment, as measured in accordance with JIS K 6911:1995, is preferably 25 to 120 MPa, more preferably 30 to 110 MPa, and even more preferably 35 to 100 MPa, from the viewpoint of suppressing the risk of breakage or collapse of the existing hollow column 1 and providing better reinforcement. From a similar viewpoint, the flexural modulus of a non-foamed urethane resin produced using the polyol composition of this embodiment, as measured in accordance with JIS K 6911:1995, is preferably 450 to 3000 MPa, more preferably 600 to 2800 MPa, and even more preferably 700 to 2500 MPa. From a similar viewpoint, the bending deflection of the non-foaming urethane resin produced using the polyol composition of this embodiment, as measured in accordance with JIS K 6911:1995, is 3.0 to 25.0 mm, more preferably 4.0 to 20.0 mm, and even more preferably 5.0 to 15.0 mm.

[0048] The compressive strength, flexural strength, flexural modulus, and flexural deflection of the non-foaming urethane resin produced using the polyol composition of this embodiment were measured using test specimens of molded products obtained after reacting the polyol composition with polymethylene polyphenyl polyisocyanate (polymeric MDI) and isocyanate index 84-110 at room temperature (20°C) for 2 hours.

[0049] [Non-foaming polyurethane resin] The non-foaming urethane resin of this embodiment is a reaction product of the polyol composition of this embodiment and polyisocyanate. The non-foaming urethane resin obtained by mixing and reacting the polyol composition of this embodiment with polyisocyanate has the above-mentioned good strength characteristics, making it suitable for filling the hollow portion of existing hollow columns to reinforce them.

[0050] The polyisocyanate to be mixed and reacted with the polyol composition is an isocyanate having two or more isocyanate groups in one molecule, and various aromatic, alicyclic, and aliphatic polyisocyanates can be used. One type of polyisocyanate may be used alone, or two or more types may be used in combination. Of these, aromatic polyisocyanates are preferred because they easily produce non-foaming urethane resins with good strength properties, and furthermore, aromatic polyisocyanates that are liquid at room temperature (20°C) are preferred from the viewpoint of ease of handling.

[0051] Examples of aromatic polyisocyanates include phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate (MDI), dimethyldiphenylmethane diisocyanate, triphenylmethane triisocyanate, naphthalene diisocyanate, and polymethylene polyphenyl polyisocyanate (polymeric MDI). Among these, polyisocyanate MDI and polymeric MDI are preferred from the viewpoint of ease of handling and appropriate reactivity, and because they make it easy to obtain non-foaming urethane resins with good strength. Polycyanates obtained by modifying MDI with carbodiimide are also preferred.

[0052] The isocyanate index when reacting a polyol composition with a polyisocyanate to obtain a non-foaming urethane resin is not particularly limited and is usually around 100, but from the viewpoint of obtaining a non-foaming urethane resin with good strength, it is preferably 80 to 120, more preferably 82 to 115, and even more preferably 84 to 110.

[0053] For non-foaming urethane resins, a two-component urethane resin is preferred from the viewpoint of ease of handling at the site where existing hollow columns are reinforced, and the ease with which various strengths such as the compressive strength mentioned above can be obtained to a sufficient degree. In other words, the urethane resin raw material liquid is preferably of a type that is used by mixing two liquids: a first liquid of a polyol composition and a second liquid of polyisocyanate.

[0054] If the urethane resin raw material liquid is a two-component mixture type, for example, it is preferable to mix the first liquid and the second liquid, which are filled in separate containers, using a mixing head or the like, at the site where the existing hollow column is being reinforced, just before injecting them into the hollow part of the existing hollow column. By injecting the urethane resin raw material liquid into existing hollow columns without using aggregate, injection is possible through small inlets. For example, it can be injected through existing side openings used for grounding wire connections or scaffolding bolt installations, and it has the advantage of not requiring large-scale equipment for injection into existing hollow columns.

[0055] The content of the polyol composition in the urethane resin raw material liquid is preferably 45.0 to 80.0 parts by mass, more preferably 50.0 to 75.0 parts by mass, and even more preferably 55.0 to 70.0 parts by mass, per 100 parts by mass of the urethane resin raw material liquid, in order to obtain a non-foaming urethane resin with good strength characteristics.

[0056] In order to obtain a non-foaming urethane resin with good strength characteristics, the total amount of the polyol composition and polyisocyanate in the urethane resin raw material liquid is preferably 90.0 to 100 parts by mass, more preferably 95.0 to 100 parts by mass, and even more preferably 100 parts by mass, per 100 parts by mass of the urethane resin raw material liquid. When the total amount of the polyol composition and polyisocyanate is less than 100 parts by mass, other substances that can be added to the urethane resin raw material liquid besides the polyol composition and polyisocyanate include, for example, the same substances as the other additives in the polyol composition described above.

[0057] The urethane resin raw material liquid for producing the non-foaming urethane resin of this embodiment has a pot life of 10 to 40 minutes, more preferably 15 to 35 minutes, and even more preferably 20 to 30 minutes, while remaining fluid at room temperature (20°C), from the viewpoint of ease of handling. Similarly, the curing time when curing the urethane resin raw material liquid at room temperature (20°C) is preferably 30 to 80 minutes, more preferably 45 to 75 minutes, and even more preferably 50 to 70 minutes.

[0058] The urethane resin raw material liquid is preferably injected into the hollow part of the existing hollow column and reaches a strength of about 80% of its final strength in 24 hours. To obtain good strength characteristics, it is preferable to leave it for at least 3 days, more preferably 4 days, and even more preferably 5 days. [Examples]

[0059] The present invention will be described in detail below based on examples, but the present invention is not limited to the following examples, and various modifications are possible without departing from the spirit of the invention.

[0060] [Preparation of urethane resin test specimens] Polyol compositions formulated with the raw material compositions shown in each example and comparative example in Table 1 were mixed with polyisocyanate by stirring, and the resulting urethane resin raw material liquid was poured into a mold and allowed to stand for 2 hours. The cured urethane resin was demolded, and urethane resin test specimens for strength measurement were prepared. The molded size of the test specimen for compressive strength measurement (compression test) was 150 mm x 150 mm with a thickness of 12.7 mm, and the molded size of the test specimen for flexural strength, flexural modulus, and flexural deflection (flexural test) was 150 mm x 150 mm with a thickness of 4 mm.

[0061] The details of each raw material component shown in Table 1 are as follows: • KC-209: "Sannix (registered trademark) KC-209", manufactured by Sanyo Chemical Industries, Ltd., polyether polyol (initiator: glycerin), hydroxyl value 34 mg KOH / g • FA-908: "Sannix (registered trademark) FA-908", manufactured by Sanyo Chemical Industries, Ltd., polyether polyol (initiator: glycerin), hydroxyl value 24 mg KOH / g ·EL-410NE: "Exsenol (registered trademark) 410NE", manufactured by AGC Inc., polyether polyol (initiator: pentaerythritol), hydroxyl value 400 mg KOH / g • SP-750: "Sannix (registered trademark) SP-750", manufactured by Sanyo Chemical Industries, Ltd., polyether polyol (initiator: sorbitol), hydroxyl value 490 mg KOH / g • NP-300: "Sannix (registered trademark) NP-300", manufactured by Sanyo Chemical Industries, Ltd., polyether polyol (initiator: ethylenediamine), hydroxyl value 755 mg KOH / g • 14BG: 1,4-butanediol, manufactured by Mitsubishi Chemical Corporation • KL-120: "Kaorizer (registered trademark) No. 120", manufactured by Kao Corporation, 1-isobutyl-2-methylimidazole • BYK-A506: Silicone-based defoaming agent manufactured by BYK Corporation. • TMCPP: Tris(chloropropyl) phosphate, manufactured by Daihachi Chemical Industry Co., Ltd. • BTG: "Butyl triglycol", Nippon Emulsifier Co., Ltd., Triethylene glycol monobutyl ether • Molecular sieve 3A: Manufactured by Resonaq Universal Co., Ltd., zeolite • MR-200: "Millionate (registered trademark) MR-200", manufactured by Tosoh Corporation, polymethylene polyphenyl polyisocyanate (polymeric MDI) • MTL: "Millionate (registered trademark)", manufactured by Tosoh Corporation, carbodiimide-modified phenylmethane diisocyanate (monomeric MDI)

[0062] Table 1 shows the results of visually inspecting the presence or absence of foaming of the urethane resin raw material liquid, as well as the pot life and curing time at 20°C.

[0063] [Measurement and evaluation of physical properties of urethane resin] The compressive strength, flexural strength, flexural modulus, and flexural deflection of the prepared urethane resin test specimens were measured using a method compliant with JIS K 6911:1995. Table 1 shows the results of various physical property measurements and evaluations of urethane resin.

[0064] [Table 1]

[0065] [Column bending test] For the urethane resins of Examples 1 and 2 and Comparative Example 2, a column bending test was conducted to evaluate the reinforcing effect on existing hollow columns as follows. We assessed the feasibility of preventing collapse of a simulated deteriorated reinforced concrete column, assuming that the tensile steel members fractured due to lateral cracking. Figure 1 shows an overview of the column bending test. The deteriorated simulated column was fabricated by creating a half-section cut section 11f by grinding away the concrete portion from the outer surface with a grinder at a position 600 mm below the ground-level marker line 11e (2.5 m from the base opening 11b) of a 12 m long reinforced concrete column, and cutting the exposed reinforcing bars. After erecting a deteriorated simulated column in ground 12 equivalent to soil type B, a urethane resin raw material liquid was injected from the bottom end 11c to fill the hollow part of the column. After leaving it for 5 days, a hollow column test specimen 11 was prepared in which the urethane resin was filled to 100% of the height from the base end 11b. A column bending test was conducted on a hollow column test specimen 11 by applying a horizontal load P in the opposite direction to the surface (half-section cut section 11f) where a half-section cut was made, at a position 250 mm from the tip 11c. The horizontal load P was applied by pulling a wire 14 connected through a pulley 15 attached to the reaction column 13 using a winch. The test results are shown in Table 2.

[0066] The safety factor was calculated using the maximum load at which the hollow column test specimen 11 collapsed or broke as the maximum load. The safety factor is the ratio of the maximum load to the design load (maximum load / design load). For the reinforced concrete column of the hollow column test specimen 11, the design load is specified as 3.43 kN for a 12m column. A safety factor of 1.0 or higher indicates sufficient resistance to horizontal loads.

[0067] Furthermore, it was determined whether the hollow column test specimen 11 would collapse when its tip position was displaced by 2.5m. In Table 2, cases where it did not collapse are indicated as A, and cases where it collapsed are indicated as B. Comparative Example 5 is an unfilled hollow column test specimen (blank).

[0068] [Table 2]

[0069] As can be seen from the column bending test results shown in Table 2, filling a deteriorated simulated column with the non-foaming urethane resin obtained using the polyol composition of this embodiment provides a sufficient safety factor, prevents collapse, and effectively reinforces the column. [Explanation of Symbols]

[0070] 11 Hollow column test specimen 11b Motoguchi 11c end 11e Ground marking line 11f Half-section cutting section 12 Ground 13 Reaction Column 14 wires 15 Pulleys

Claims

1. A polyol composition for manufacturing non-foaming polyurethane resin for reinforcing existing hollow columns without using aggregates, It contains a polyol and a urethane catalyst, The aforementioned polyol includes a polyether polyol and has an average hydroxyl value of 250 to 450 mg KOH / g. A polyol composition having a compressive strength of 15 to 100 MPa, measured in accordance with JIS K 6911:1995 for the aforementioned non-foaming urethane resin.

2. The polyol composition according to claim 1, wherein the non-foaming urethane resin has a bending strength of 25 to 120 MPa, as measured in accordance with JIS K 6911:1995.

3. The polyol composition according to claim 1, wherein the flexural modulus of the non-foaming urethane resin, as measured in accordance with JIS K 6911:1995, is 450 to 3000 MPa.

4. The polyol composition according to claim 1, wherein the bending deflection of the non-foaming urethane resin, measured in accordance with JIS K 6911:1995, is 3.0 to 25.0 mm.

5. A polyol composition according to claim 1, comprising a dehydrating agent.

6. The polyol composition according to claim 1, wherein the polyol comprises a polyether polyol having a hydroxyl value of 20 to 100 mg KOH / g and a polyether polyol having a hydroxyl value of 300 to 600 mg KOH / g.

7. The polyol composition according to claim 1, which is a polyol premix.

8. A non-foaming urethane resin, which is a reaction product of a polyol composition according to any one of claims 1 to 7 and a polyisocyanate.

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