Cavity filling materials and cavity filling methods

Abstract

To provide a cavity filling material capable of suppressing turbidity of water and producing a foam having high compressive strength.SOLUTION: A cavity filling material according to the embodiment is for filling a cavity generated on a back side of a tunnel wall. The cavity filling material includes a component (A) containing a polyol, a foaming agent, and a trimerization catalyst, and a component (B) containing a polyisocyanate. The polyol contains an aromatic polyether polyol obtained by adding alkylene oxide to an active hydrogen compound having two or more benzene rings. An isocyanate index is 150 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a void filling material for filling voids that occur behind tunnel walls, and a void filling method using the same. [Background technology]

[0002] Cavities can sometimes form behind the tunnel wall (such as the concrete lining) and the natural ground due to erosion of the natural ground. When such cavities exist, the load from the natural ground is concentrated locally on the tunnel wall. Therefore, in order to evenly distribute the ground pressure acting on the wall, the cavities between the tunnel wall and the natural ground are filled with cavity filling material.

[0003] Known examples of such cavity fillers include urethane-based cavity fillers that are foam-filled into cavities. For example, Patent Document 1 discloses a urethane composition comprising Liquid A, whose main component is a polyol component containing a trifunctional or higher polyfunctional polyol, and Liquid B, whose main component is an isocyanate component, with an isocyanate index set within the range of 120 to 200. Patent Document 2 discloses a two-component composition comprising Liquid A, which contains a polyisocyanate compound, and Liquid B, which contains a polyol compound, a blowing agent, a silicone surfactant, and a carboxylate, with a hydrofluoroolefin or hydrochlorofluoroolefin used as the blowing agent, and having an isocyanate index of 160 to 500. Patent Document 3 discloses a chemical composition comprising a polyol component containing a polyether polyol, a nurate catalyst, and a tertiary amine catalyst, and a polyisocyanate component that is a mixture of diphenylmethane diisocyanate and polyphenylpolymethylene polyisocyanate, with an isocyanate index of 230 to 350. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-158881 [Patent Document 2] Japanese Patent Application Publication No. 2018-100346 [Patent Document 3] Patent Publication No. 2021-98819 Summary of the Invention [Problem to be solved by the invention]

[0005] Since the cavity filling material is injected between the tunnel wall and the ground, it is desirable to suppress the turbidity of the water in order to reduce adverse effects on water quality. Also, in order to firmly withstand the ground pressure after being foam-filled into the cavity, it is desirable for the foam to have high compressive strength.

[0006] In view of the above, an embodiment of the present invention aims to provide a cavity filling material that can suppress turbidity in water and produce a foam with high compressive strength, and a cavity filling method using the same. [Means for solving the problem]

[0007] The present invention includes the embodiments shown below. [1] A cavity filler for filling cavities that occur on the back side of a tunnel wall, comprising: (A) component containing a polyol, a blowing agent, and a trimerization catalyst; and (B) component containing a polyisocyanate, wherein the polyol contains an aromatic polyether polyol obtained by adding an alkylene oxide to an active hydrogen compound having two or more benzene rings, and the cavity filler has an isocyanate index of 150 or more. [2] The cavity filler according to [1], wherein the aromatic polyether polyol is a polyol obtained by adding an alkylene oxide to a bisphenol compound. [3] The cavity filling material according to [1] or [2], wherein the foaming agent contains water, and the content of the water in 100% by mass of the component (A) is 1.0 to 6.0% by mass. [4] The cavity filler according to any one of [1] to [3], wherein the component (A) further contains a liquid flame retardant. [5] The cavity filler according to any one of [1] to [4], wherein the polyisocyanate contains polymeric MDI. [6] The cavity filler according to any one of [1] to [5], wherein the viscosity of the component (A) at 25°C is 650 mPa·s or less. [7] A void filling method in which the void filling material according to any one of [1] to [6] above is injected into a void that has occurred on the back side of a tunnel wall, and is allowed to foam and harden to fill the void. [Effects of the Invention]

[0008] According to an embodiment of the present invention, it is possible to suppress turbidity in water and form a foam having high compressive strength. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present inventors, while investigating the development of a cavity filler with the aim of suppressing water turbidity and achieving high compressive strength, discovered that aromatic polyether polyols are effective in suppressing water turbidity. However, when an aromatic polyether polyol, for example, obtained by adding alkylene oxide to aniline, is used as the aromatic polyether polyol, the compressive strength of the foam tends to decrease, making it difficult to achieve both suppression of water turbidity and high compressive strength. Further investigations have revealed that by using an aromatic polyether polyol obtained by adding alkylene oxide to an active hydrogen compound having two or more benzene rings as a starting material, it is possible to achieve high compressive strength and suppression of water turbidity.

[0010] That is, the cavity filling material according to this embodiment comprises component (A) containing a polyol, a blowing agent, and a trimerization catalyst, and component (B) containing a polyisocyanate, and the polyol contains an aromatic polyether polyol obtained by adding an alkylene oxide to an active hydrogen compound having two or more benzene rings.

[0011] The cavity filler is usually a two-component curing liquid chemical composition in which component (A) as liquid A and component (B) as liquid B are mixed together to foam and cure (solidify) to form a foam. In addition to components (A) and (B), a third component may be included as an optional component.

[0012] [Component (A)] (Aromatic polyether polyol (a1)) Component (A) contains, as a polyol, an aromatic polyether polyol (a1) obtained by adding an alkylene oxide to an active hydrogen compound having two or more benzene rings. The aromatic polyether polyol (a1) is a compound having two or more hydroxyl groups, two or more benzene rings, and an ether bond in the molecule.

[0013] The active hydrogen compound may be any active hydrogen compound having two or more benzene rings in the molecule, and the active hydrogen group may be a hydroxyl group or an amino group. A bisphenol compound is preferably used as the active hydrogen compound. That is, the aromatic polyether polyol (a1) according to a preferred embodiment is an aromatic polyether polyol obtained by adding an alkylene oxide to a bisphenol compound. Since the aromatic polyether polyol (a1) made from a bisphenol compound as a starting material has multiple benzene rings in its main chain skeleton, multiple benzene rings can be introduced into the main chain skeleton of the polyurethane produced by reaction with a polyisocyanate. This is considered to be more advantageous in terms of improving the compressive strength of the foam.

[0014] Examples of the bisphenol compounds include bisphenol A (chemical name: 2,2-bis(4-hydroxyphenyl)propane), bisphenol AP (chemical name: 1,1-bis(4-hydroxyphenyl)-1-phenylethane), bisphenol C (chemical name: 2,2-bis(3-methyl-4-hydroxyphenyl)propane), bisphenol E (chemical name: 1,1-bis(4-hydroxyphenyl)ethane), bisphenol F (chemical name: bis(4-hydroxyphenyl)methane), bisphenol S (chemical name: bis(4-hydroxyphenyl)sulfone), and bisphenol Z (chemical name: 1,1-bis(4-hydroxyphenyl)cyclohexane). These compounds can be used alone or in combination of two or more.

[0015] Examples of the alkylene oxide to be added to the active hydrogen compound (preferably a bisphenol compound) include alkylene oxides having 2 to 4 carbon atoms. Specifically, it is preferable to use at least one alkylene oxide selected from the group consisting of ethylene oxide, propylene oxide, and butylene oxide. The addition of alkylene oxide to the active hydrogen compound can be carried out by known addition polymerization (ring-opening polymerization), resulting in an alkylene oxide-added aromatic polyol. The number of moles of alkylene oxide added to the active hydrogen compound is not particularly limited, and may be 2 to 30 or 3 to 20 on average.

[0016] The number of functional groups (the number of hydroxyl groups) of the aromatic polyether polyol (a1) is not particularly limited, and for example, any one of those having functional groups of 2 to 4 may be used, or two or more types having different numbers of functional groups may be used in combination. Preferably, those having 2 or 3 functional groups are used, and more preferably those having 2 functional groups.

[0017] The hydroxyl value (OHV) of the aromatic polyether polyol (a1) is not particularly limited, but is preferably 50 to 400 mgKOH / g, more preferably 100 to 300 mgKOH / g. In this specification, the hydroxyl value is measured in accordance with Method A of JIS K1557-1:2007.

[0018] The weight-average molecular weight (Mw) of the aromatic polyether polyol (a1) is not particularly limited, but is preferably 300 to 2,000, and more preferably 400 to 1,000. In this specification, the weight-average molecular weight is measured by GPC. Examples of GPC include a method using a Tosoh Corporation HLC-8020 as the GPC main body, a column temperature of 40°C, a pump flow rate of 0.6 to 1.0 mL / min, and an RI (built into the GPC main body) as the detector [column: TSKgel G6000H HR + G4000H HR + G3000H HR + G2000H HR (four columns connected); mobile phase: THF; injection volume: 80 μL; sample concentration: 0.2% (w / v)]. In this method, the weight-average molecular weight can be determined as a PPG-equivalent molecular weight using, for example, a calibration curve of a standard PPG with a known molecular weight (calibration at a molecular weight of 250 or more).

[0019] The amount of aromatic polyether polyol (a1) is not particularly limited, but is preferably 15 to 60 mass% and more preferably 20 to 50 mass% relative to 100 mass% of component (A) (i.e., the total amount of component (A)). The amount of aromatic polyether polyol (a1) relative to 100 mass% of polyol (i.e., the total amount of polyol) is not particularly limited, but is preferably 25 to 95 mass%, more preferably 30 to 90 mass%, and may be 40 to 85 mass%.

[0020] (Other polyols) Component (A) may contain a polyol other than the aromatic polyether polyol (a1). Here, polyol refers to a compound having multiple hydroxyl groups in the molecule. While such other polyol may be an aromatic polyol other than aromatic polyether polyol (a1), it is preferable to use an aliphatic polyol (a2) because it can reduce the viscosity of the chemical solution. That is, in one embodiment, the polyol constituting component (A) preferably contains the aliphatic polyol (a2) in addition to the aromatic polyether polyol (a1), thereby reducing the viscosity of component (A).

[0021] Examples of the aliphatic polyol (a2) include diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, 1,3-butanediol, 1,4-butanediol, and 1,6-hexanediol; polyols such as glycerin, trimethylolpropane, and pentaerythritol; and aliphatic polyether polyols obtained by addition polymerization of a single or mixture of active hydrogen compounds such as monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, ammonia, diglycerin, sorbitol, and sucrose with one or more alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide by known methods, as well as aliphatic polyols to which no alkylene oxide has been added. Hydroxyl-terminated urethane prepolymers obtained by reacting these aliphatic polyols with polyisocyanates may also be used as the aliphatic polyol (a2).

[0022] Among these, the aliphatic polyol (a2) is preferably an aliphatic polyether polyol obtained by adding an alkylene oxide to an aliphatic active hydrogen compound having no aromatic ring in the molecule. Here, the addition of the alkylene oxide to the aliphatic active hydrogen compound can be carried out by known addition polymerization (ring-opening polymerization).

[0023] More preferred examples of the aliphatic polyol (a2) include polyether polyols obtained by adding propylene oxide to glycerin, polyether polyols obtained by adding propylene oxide to propylene glycol, and polyether polyols obtained by adding propylene oxide to sorbitol, and these may be used alone or in combination of two or more.

[0024] The number of functional groups (number of hydroxyl groups) of the aliphatic polyol (a2) is not particularly limited, and for example, any one of those having 2 to 6 functional groups may be used, or two or more types having different numbers of functional groups may be used in combination.

[0025] The hydroxyl value (OHV) of the aliphatic polyol (a2) is not particularly limited and may be, for example, 50 to 700 mgKOH / g or 100 to 600 mgKOH / g.

[0026] The weight average molecular weight (Mw) of the aliphatic polyol (a2) is not particularly limited, and may be, for example, 200 to 3,000, or 400 to 2,000.

[0027] The amount of the aliphatic polyol (a2) is not particularly limited, but is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, relative to 100% by mass of the component (A).The amount of the aliphatic polyol (a2) relative to 100% by mass of the polyol is not particularly limited, but is preferably 5 to 75% by mass, more preferably 10 to 70% by mass, and may be 15 to 60% by mass.

[0028] The blending ratio of the aromatic polyether polyol (a1) and the aliphatic polyol (a2) is not particularly limited, but the mass ratio (a1) / (a2) between the two is preferably 0.3 to 10, more preferably 0.5 to 8.0, and may be 0.7 to 6.0.

[0029] (foaming agent) A blowing agent is blended into component (A). Examples of blowing agents include water, hydrocarbons, hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), and hydrochlorofluoroolefins (HCFOs). These can be used alone or in combination of two or more.

[0030] Examples of HFCs include HFC-134a, HFC-245fa, and HFC365mfc. Examples of HFOs include HFO-1234yf, HFO-1234ze(E), HFO-1336mzz(E), and HFO-1336mzz(Z). Examples of HCFOs include HCFO-1233zd(E), HCFO-1233zd(Z), and HCFO-1224yd(Z).

[0031] The amount of the foaming agent is not particularly limited, but is preferably 2.0 to 30% by mass, and more preferably 3.0 to 25% by mass, relative to 100% by mass of the component (A).

[0032] Among these, it is preferable to use water as the blowing agent. That is, it is preferable that the blowing agent contains water. Water acts as a blowing agent by reacting with the polyisocyanate of component (B) to generate carbon dioxide gas. The blowing agent may be water alone, or water may be used in combination with another blowing agent. When water is used as the blowing agent, the content of water in 100% by mass of component (A) is preferably 1.0 to 6.0% by mass, more preferably 1.5 to 5.0% by mass, and even more preferably 2.0 to 4.5% by mass.

[0033] (trimerization catalyst) A trimerization catalyst is blended into component (A). The trimerization catalyst is a catalyst for the trimerization reaction that trimers the polyisocyanate in component (B). Trimerization produces isocyanurate rings, which increases heat resistance and improves flame retardancy.

[0034] Examples of the trimerization catalyst include alkali metal carboxylates and quaternary ammonium salts.

[0035] As the alkali metal carboxylate, it is preferable to use an alkali metal salt of a carboxylic acid having a carbon number of 1 to 20 (more preferably 2 to 10). Specific examples of the alkali metal carboxylate include potassium formate, potassium acetate, potassium n-octanoate, potassium 2-ethylhexanoate, sodium 2-ethylhexanoate, potassium benzoate, sodium benzoate, potassium propionate, and potassium caprate.

[0036] Examples of quaternary ammonium salts include trimethylhydroxypropylammonium formate, N-(2-hydroxypropyl)-N-(2-hydroxyethyl)-N,N-dimethylammonium octanoate, etc. Commercially available quaternary ammonium salts as trimerization catalysts include, for example, trade names such as "Kaolizer No. 410" and "Kaolizer No. 420" (both manufactured by Kao Corporation), "TOYOCAT-TR20" and "TOYOCAT-TRX" (both manufactured by Tosoh Corporation), and these may also be used.

[0037] The trimerization catalysts may be used alone or in combination of two or more, and among these, it is preferable to use at least one selected from the group consisting of potassium formate, potassium acetate, potassium n-octanoate, potassium 2-ethylhexanoate, and quaternary ammonium salts of carboxylic acids.

[0038] The amount of the trimerization catalyst is not particularly limited, and may be, for example, 0.2 to 10 mass%, 0.5 to 7.0 mass%, 1.0 to 5.0 mass%, or 1.5 to 4.0 mass%, relative to 100 mass% of component (A).

[0039] (liquid flame retardant) It is preferable that a liquid flame retardant be blended into component (A). Blending a liquid flame retardant can impart flame retardancy to the foam and reduce the viscosity of component (A). Specifically, blending aromatic polyether polyol (a1) into component (A) increases the viscosity of component (A), but blending a liquid flame retardant not only imparts flame retardancy but also functions as a diluent, thereby lowering the viscosity of component (A).

[0040] Examples of liquid flame retardants include phosphate ester flame retardants such as trimethyl phosphate, triethyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, and tris(chloropropyl) phosphate, and halogen-containing flame retardants such as chlorinated paraffin. These may be used alone or in combination of two or more. Among these, it is preferable to use a phosphate ester flame retardant as the liquid flame retardant.

[0041] The amount of the liquid flame retardant is not particularly limited, and may be, for example, 5 to 60 mass %, 15 to 50 mass %, or 20 to 45 mass % relative to 100 mass % of the component (A).

[0042] (Other ingredients) In addition to the components described above, known additives such as a tertiary amine catalyst, a foam stabilizer, a diluent, other active hydrogen compounds, a pigment, an inorganic filler, a crosslinking agent, and a coupling agent may be added to component (A) as needed, provided that the object of this embodiment is not impaired.

[0043] Examples of the tertiary amine catalyst include triethylenediamine, 2-methyltriethylenediamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N',N'-tetramethylpropylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-pentamethyldiethylenetriamine, trimethylaminoethylpiperazine, bis-(dimethylaminoethyl)ether, N,N',N''-tris(dialkylaminoalkyl)-s-hexahydrotriazine, N,N-dimethylaminoethylmorpholine, dimethylaminopropylimidazole, hexamethyltriethylenetetramine, hexamethyltripropylenetetramine, and N,N,N-tris(3-dimethylaminopropyl)amine, and any one of these can be used alone or in combination of two or more.

[0044] The amount of the tertiary amine catalyst is not particularly limited, and may be 0.1 to 5.0 mass %, 0.5 to 3.0 mass %, or 0.7 to 2.0 mass % relative to 100 mass % of the component (A).

[0045] Examples of the foam stabilizer include silicone-based foam stabilizers such as polyoxyalkylenedimethylpolysiloxane copolymers that are commonly used in rigid urethane foam resins. The amount of silicone-based foam stabilizer is not particularly limited, and may be 0.01 to 5.0 mass%, 0.1 to 3.0 mass%, or 0.5 to 1.5 mass%, relative to 100 mass% of component (A).

[0046] The diluent is an optional component that is added to reduce the viscosity of component (A). Specific examples of the diluent include phthalates such as dibutyl phthalate, dioctyl phthalate, and diisononyl phthalate, adipates such as dibutyl adipate, dioctyl adipate, diisononyl adipate, and bis(2-(2-butoxyethoxy)ethyl)adipate, and trimellitates such as tri(2-ethylhexyl) trimellitate.

[0047] The other active hydrogen compounds are active hydrogen compounds other than polyols. That is, component (A) may contain only polyols as active hydrogen compounds, but it may also contain active hydrogen compounds other than polyols. Here, the active hydrogen compound refers to a compound (excluding water) having one or more active hydrogen groups in the molecule. The active hydrogen group is a group containing a hydrogen atom that reacts with an isocyanate group, and examples thereof include a hydroxyl group, a primary amino group (-NH), and a secondary amino group (-NHR). Examples of other active hydrogen compounds include monools, primary amines having a primary amino group, and secondary amines having a secondary amino group.

[0048] (Viscosity of component (A)) From the viewpoint of workability, the viscosity of component (A) is preferably 650 mPa·s or less at 25° C., more preferably 500 mPa·s or less, and even more preferably 300 mPa·s or less. There are no particular lower limits for the viscosity of component (A) at 25° C., and it may be, for example, 50 mPa·s or more, or 100 mPa·s or more.

[0049] [(B) Component] (Polyisocyanate) Component (B) contains a polyisocyanate. Polyisocyanate refers to a compound having multiple isocyanate groups in the molecule. Examples of polyisocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

[0050] Specific examples of polyisocyanates include diphenylmethane diisocyanate (MDI) and its isomers (monomeric MDI), polymethylene polyphenyl polyisocyanate (polymeric MDI), tolylene diisocyanate, crude tolylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, naphthalene diisocyanate, hydrogenated diphenylmethane diisocyanate, trimethylene xylylene diisocyanate, and other polyisocyanates, either alone or in mixtures; carbodiimide-modified products of these polyisocyanates, and products obtained by adding a catalyst to form dimers or trimers. These isocyanates can be used alone or in combination of two or more.

[0051] Among these, from the viewpoint of curability and the like, it is preferable to use an aromatic polyisocyanate as the polyisocyanate, and more preferably to use polymeric MDI. Polymeric MDI is a mixture of monomeric MDI and its polynuclear form. In one embodiment, it is preferable that 60 mass % or more, more preferably 80 mass %, and even more preferably 100 mass % of the polyisocyanate is aromatic polyisocyanate (more preferably polymeric MDI).

[0052] (Other ingredients) Component (B) may consist solely of the polyisocyanate. If necessary, other known additives described in the section on component (A) may be added to component (B) as other components, provided that the purpose of this embodiment is not impaired.

[0053] (Viscosity of component (B)) From the viewpoint of workability, the viscosity of component (B) is preferably 650 mPa·s or less at 25° C., more preferably 500 mPa·s or less, and even more preferably 300 mPa·s or less. There are no particular lower limits for the viscosity of component (B) at 25° C., and it may be, for example, 50 mPa·s or more, or 100 mPa·s or more.

[0054] [Mixing of component (A) and component (B)] In the cavity filling material according to this embodiment, the components (A) and (B) are mixed together at the time of use to foam and cure to form a foamed product.

[0055] The mixing ratio of components (A) and (B) is set so that the isocyanate index is 150 or greater. When polyol and polyisocyanate are mixed in the presence of a blowing agent, a foaming reaction and a resinification reaction occur, resulting in the formation of a rigid polyurethane foam. Because the isocyanate index is 150 or greater and a trimerization catalyst is added, the trimerization reaction of the polyisocyanate produces isocyanurate rings. Furthermore, isocyanate groups that do not constitute an isocyanurate ring react with hydroxyl groups in the polyol to form urethane bonds. This results in the formation of a rigid polyurethane foam containing an isocyanurate ring, known as a rigid polyisocyanurate foam.

[0056] The isocyanate index (NCO INDEX) is the number of moles of isocyanate groups in the polyisocyanate in component (B) per mole of hydroxyl groups in the polyol in component (A), expressed as a percentage (%). That is, NCO INDEX = ((number of moles of isocyanate groups) / (number of moles of hydroxyl groups)) × 100. The isocyanate index is calculated using the hydroxyl value of the polyol in component (A) and the isocyanate value of the polyisocyanate in component (B). Here, the isocyanate value is calculated using the isocyanate content measured in accordance with Method A of JIS K1603-1:2007, as follows: Isocyanate value = {(isocyanate content) × 56110} / (42.02 × 100).

[0057] The cavity filler preferably has an isocyanate index of 180 or more, more preferably 200 or more. The isocyanate index is preferably 400 or less, more preferably 300 or less.

[0058] The mass ratio (liquid ratio) of component (A) to component (B) is not particularly limited, and may be, for example, in the range of 1:1 to 1:3, or 1:1.5 to 1:2.5.

[0059] The expansion ratio of the cavity filler is not particularly limited, but is preferably 20 or more, more preferably 20 to 60, and even more preferably 30 to 50, and may be 35 to 45. Here, the expansion ratio is calculated as the ratio (V1 / V0) of the volume V1 of the cured product (foam) after foaming to the volume V0 of the mixed liquid of components (A) and (B).

[0060] The cavity filling material preferably has a compressive strength of 0.16 MPa or more when cured (foamed), more preferably 0.17 MPa or more, and even more preferably 0.18 MPa or more. The upper limit of the compressive strength is not particularly limited, and may be, for example, 0.30 MPa or less.

[0061] [Void filling method] The void filling material according to this embodiment is used to fill voids that occur behind tunnel walls. This method of filling voids between tunnel walls and the natural ground is also called back-filling injection, and therefore the void filling material according to this embodiment is also called back-filling injection material.

[0062] In this specification, a tunnel refers to an underground structure with a predetermined cross-sectional area at a planned location. The definition given by the OECD Tunnel Conference in 1970 is "a tunnel with a finished cross-sectional area of ​​2 m 2 In this specification, tunnels are defined as those with a finished cross-sectional diameter of 0.8m or more, in addition to the above, in accordance with the definition of the Japan Tunneling Association. Therefore, tunnels in this specification are not limited to general tunnels (for example, road or railway tunnels, subways) built for the purpose of transporting traffic or goods between two points, but also include various underground structures built for purposes such as underground shopping malls and storing goods.

[0063] A tunnel wall is a structure that separates the artificial space formed inside the tunnel from the natural ground, and examples thereof include lining concrete. Cavities may form behind the tunnel wall, i.e., between the wall and the natural ground, due to natural ground erosion, or tunnels may be constructed with cavities left behind during construction. The void filling material according to this embodiment can be used to fill such cavities.

[0064] In the cavity filling method according to this embodiment, the cavity filling material is injected into a cavity that has developed behind the tunnel wall, where it foams and hardens to fill the cavity. That is, a mixture of the above-mentioned components (A) and (B) is injected into the cavity as the cavity filling material. Because components (A) and (B) react immediately after mixing, it is preferable to mix them during on-site construction. The mixture injected into the cavity foams due to the reaction between components (A) and (B), and foams to fill the cavity.

[0065] As a cavity filling method, known methods can be employed, except that the cavity filling material of the above embodiment is used as the cavity filling material to be injected into the cavity. For example, in one embodiment of the cavity filling method, the tip of an injection pipe is inserted into the cavity by penetrating the wall from inside the tunnel. Components (A) and (B) of the cavity filling material are mixed, and an injection device is used to send the mixed liquid into the injection pipe, which then injects it into the cavity. The mixed liquid then foams and hardens to form a foam, which fills the cavity. By filling the cavity with the foam in this way, the ground pressure acting on the wall from the natural ground can be evenly distributed, thereby suppressing cracking, collapse, and the like of the wall. [Example]

[0066] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited thereto.

[0067] [Raw materials used] (Aliphatic polyol (a2)) Polyol (a2-1): Aliphatic polyether polyol obtained by addition polymerization of propylene oxide with an aliphatic active hydrogen compound containing sorbitol, a mixture of functional groups of 3 and 6, hydroxyl value 550 mg KOH / g (trade name: Exenol 550SO, manufactured by AGC Corporation) Polyol (a2-2): Aliphatic polyether polyol obtained by addition polymerization of propylene oxide to propylene glycol, with 2 functional groups, weight-average molecular weight of 400, and hydroxyl value of 281 mg KOH / g (product name: Exenol 420, manufactured by AGC Corporation) Polyol (a2-3): Aliphatic polyether polyol obtained by addition polymerization of propylene oxide to glycerin, with 3 functional groups, weight-average molecular weight of 421, and hydroxyl value of 400 mg KOH / g (product name: Exenol 430, manufactured by AGC Corporation)

[0068] (Aromatic polyether polyol (a1)) Polyol (a1-1): Aromatic polyether polyol obtained by addition polymerization of bisphenol A with propylene oxide, having 2 functional groups, a weight-average molecular weight of 580, and a hydroxyl value of 193 mg KOH / g (trade name: Adeka Polyether BPX-33, manufactured by ADEKA Corporation) Polyol (a1-2): Aromatic polyether polyol obtained by addition polymerization of propylene oxide to bisphenol A, with a functionality of 2, a weight-average molecular weight of 400, and a hydroxyl value of 281 mgKOH / g (trade name: Adeka Polyether BPX-21, manufactured by ADEKA Corporation) Polyol (a1-3): Aromatic polyether polyol obtained by addition polymerization of aniline with propylene oxide, having 2 functional groups, a weight-average molecular weight of 267, and a hydroxyl value of 420 mg KOH / g (trade name: Polyhardener PA-400, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[0069] (catalyst) Tertiary amine catalyst: N,N,N-tris(3-dimethylaminopropyl)amine (trade name: Polycat 9, manufactured by EVONIK) Trimerization catalyst 1: Potassium octanoate (trade name: DABCO K15, manufactured by EVONIK, 75% by weight diethylene glycol solution) Trimerization catalyst 2: Quaternary ammonium salt (product name: Kaolizer No. 420, manufactured by Kao Corporation)

[0070] (Flame retardant) Flame retardant 1: Tris(chloropropyl)phosphate (trade name: TMCPP, manufactured by Daihachi Chemical Industry Co., Ltd.) Flame retardant 2: Tricresyl phosphate (trade name: TCP, manufactured by Daihachi Chemical Industry Co., Ltd.)

[0071] (foaming agent) ·water HCFO: trans-1-chloro-3,3,3-trifluoropropene (trade name: Solstice LBA, manufactured by Honeywell)

[0072] (Foam stabilizer) Foam stabilizer: Silicone foam stabilizer (product name: SZ-1671, manufactured by Dow Toray Industries, Inc.)

[0073] (Polyisocyanate) Isocyanate 1: Polymeric MDI, isocyanate value 414 mg KOH / g (trade name: Millionate MR-200, manufactured by Tosoh Corporation) Isocyanate 2: Polymeric MDI, isocyanate value 414 mg KOH / g (trade name: Millionate MR-100, manufactured by Tosoh Corporation)

[0074] [Preparation of solutions A and B] Liquid A was made up of component (A), and liquid B was made up of component (B). Liquid A and liquid B were prepared by appropriately mixing the raw materials according to the formulations (parts by mass) shown in Tables 1 and 2 below. Liquid A and B were evaluated for viscosity, compressive strength, expansion ratio, turbidity in water, and flame retardancy. The evaluation methods are as follows. Note that in Tables 1 and 2, compressive strength, expansion ratio, and flame retardancy could not be measured due to shrinkage of the foam after foaming, etc., and these are indicated by "-".

[0075] (viscosity) The viscosity (mPa·s) of liquids A and B at 25°C was measured using a Brookfield BM type viscometer (manufactured by Eiko Seiki Co., Ltd.) in accordance with JIS K7117-1:1999.

[0076] (Compressive strength) After the temperatures of both liquids A and B were brought to 20°C, liquids A and B were mixed and foamed and cured using a disperser (5000 rpm, stirring for 5 seconds) in the mixing ratio (mass ratio of liquid A to liquid B:A:B) shown in Tables 1 and 2. A 50 mm x 50 mm x 50 mm piece was cut out of the resulting foam and measured using a method in accordance with JIS K7220:2006 to determine the average value.

[0077] (Expansion ratio) After the temperatures of both liquid A and liquid B were brought to 20°C, liquid A and liquid B were mixed using a disperser (5000 rpm, stirring for 5 seconds) in the mixing ratio (mass ratio of liquid A to liquid B:A:B) shown in Tables 1 and 2. After the curing reaction was completed, the volume V1 of the cured product was divided by the volume V0 of the mixed liquid of liquid A and liquid B (the sum of the volumes of liquid A and liquid B) to calculate the expansion ratio, which is the ratio of the two (V1 / V0).

[0078] (Mud in the water) After the temperatures of both liquids A and B were brought to 20°C, liquids A and B were mixed using a disperser (5000 rpm, stirring for 5 seconds) at the mixing ratio (mass ratio of liquid A to liquid B:A:B) shown in Tables 1 and 2. The mixture was immediately poured into a 2-L disc cup containing 300 g of water and allowed to stand until the reaction was complete. The water in the disc cup was then sampled, and its light transmittance at a wavelength of 500 nm was measured using a UV-visible spectrophotometer (Hitachi U-3900H).

[0079] (Flame retardant) After bringing the temperatures of both liquids A and B to 20°C, they were mixed using a disperser (5000 rpm, stirring for 5 seconds) at the mixing ratio (mass ratio of liquid A to liquid B) listed in Tables 1 and 2. The mixture was immediately placed in a wooden box with internal dimensions of 250 mm length x 250 mm width x 250 mm height and allowed to foam and harden. The resulting foam was tested for flammability in accordance with JIS A9511:2017 Method B. For the average of five tests, a test specimen was deemed pass if the time from when the flame was applied to the test specimen until the flame extinguished was within 60 seconds and the length of the longest internal combustion length of the burned portion of the test specimen was within 60 mm; otherwise, the test specimen was deemed fail.

[0080] [Table 1]

[0081] [Table 2]

[0082] The results are shown in Tables 1 and 2. In Comparative Example 3, in which no aromatic polyether polyol was blended in Solution A, the water became significantly turbid. In Comparative Example 1, the blending of an aromatic polyether polyol eliminated the turbidity of the water, but the aromatic polyether polyol was derived from aniline, which has one benzene ring, as a starting material, resulting in a decrease in compressive strength compared to Comparative Example 3. In Comparative Example 2, no foam was obtained because no blowing agent was blended. In Comparative Example 4, the isocyanate index was low, resulting in insufficient formation of isocyanurate rings and urethane bonds, and shrinkage after foaming, making it impossible to measure the compressive strength and expansion ratio. In Comparative Example 5, the absence of a trimerization catalyst prevented the formation of isocyanurate rings and the residual excess polyisocyanate, resulting in shrinkage after foaming, making it impossible to measure the compressive strength and expansion ratio.

[0083] In contrast, Examples 1 to 13 were able to eliminate water turbidity, and demonstrated equal or superior turbidity suppression effects compared to Comparative Example 1, which used an aromatic polyether polyol made from aniline as a starting material. Furthermore, Examples 1 to 13 did not experience the decrease in compressive strength observed in Comparative Example 1, and foams with equal to or higher compressive strength than Comparative Example 3 were obtained. Furthermore, the expansion ratio was approximately 40 times, and therefore, foams with high compressive strength could be formed while maintaining a high expansion ratio. Furthermore, by incorporating a liquid flame retardant, the viscosity of Liquid A could be kept low, and the foams exhibited excellent flame retardancy.

[0084] The various numerical ranges described in this specification can be arbitrarily combined with their upper and lower limits, and all such combinations are considered to be preferred numerical ranges described in this specification. Furthermore, a numerical range described as "X to Y" means from X to Y.

[0085] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their omissions, substitutions, modifications, etc. are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents.

Claims

1. A cavity filling material for filling cavities that occur behind the walls of a tunnel, The present invention comprises an (A) component containing a polyol, a blowing agent, and a trimerization catalyst, and a (B) component containing a polyisocyanate, the polyol includes an aromatic polyether polyol obtained by adding an alkylene oxide to an active hydrogen compound having two or more benzene rings, A cavity filler having an isocyanate index of 150 or greater.

2. 2. The cavity filler according to claim 1, wherein the aromatic polyether polyol is a polyol obtained by adding an alkylene oxide to a bisphenol compound.

3. 3. The cavity filler according to claim 1, wherein the foaming agent contains water, and the content of the water in 100% by mass of the component (A) is 1.0 to 6.0% by mass.

4. The cavity filler according to any one of claims 1 to 3, wherein the component (A) further comprises a liquid flame retardant.

5. 5. The cavity filler of claim 1, wherein the polyisocyanate comprises polymeric MDI.

6. 6. The cavity filler according to claim 1, wherein the viscosity of component (A) at 25° C. is 650 mPa·s or less.

7. A cavity filling method, comprising injecting the cavity filling material according to any one of claims 1 to 6 into a cavity that has occurred on the back side of a tunnel wall, and allowing it to foam and harden to fill the cavity.

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