Two pack type curable polyurethane resin composition

Abstract

To provide a two pack type curable polyurethane resin composition in which the initial viscosity of a mixture of a main agent and a curing agent can be made low while using a polybutadiene polyol having a high molecular weight as the main agent, and as a result, the mixture can sufficiently penetrate even into a narrow gap to exhibit excellent water cut-off properties, and the obtained polyurethane resin can be made excellent in flame retardancy.SOLUTION: The two-pack curable polyurethane resin composition for a water stop material comprises a main agent and a curing agent, wherein the main agent contains (A) a polybutadiene polyol compound, (B) a phosphoric ester compound, (C) a plasticizer A, (D) a metal hydroxide, and (E) a catalyst, the curing agent contains (F) a polyisocyanate compound and (G) a plasticizer B, the number-average molecular weight of the component (A) in the main agent is 1200 to 3000, the viscosity of the main agent is 5 to 50 Pa·s, and the viscosity of the curing agent is 0.01 to 0.15 Pa·s.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a two-component curable polyurethane resin composition. [Background technology]

[0002] Polyurethane resins are excellent in flexibility and pliability, mechanical strength, abrasion resistance, and chemical resistance, and are therefore used, for example, as waterproofing materials (waterstop materials) at civil engineering and construction sites. For example, Patent Document 1 discloses a two-component curable polyurethane resin composition (two-component curable polyurethane resin composition) in which a curing agent containing a specific active hydrogen compound (a) as the main component and a base resin containing an organic polyisocyanate or a polyisocyanate component (b) obtained by reacting an organic polyisocyanate with a polyol as the main component are reacted in the presence of at least one curing catalyst (c) selected from organic and inorganic acids. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-113217 Summary of the Invention [Problem to be solved by the invention]

[0004] When polyurethane resins are used for waterproofing applications, polyurethane resins with improved water resistance are widely used by using polyol components that do not have ester groups that can be hydrolyzed. One example of such polyols that do not have ester groups is polybutadiene polyol. When a two-component curable polyurethane resin composition contains a polybutadiene polyol as its main component and is mixed with a polyisocyanate-containing curing agent to undergo a polyaddition reaction to produce a polyurethane resin used as a waterproofing material, the initial viscosity of the mixture of the main component and curing agent is significantly affected by factors such as the molecular weight of the polybutadiene polyol. Using a high-molecular-weight polybutadiene polyol (e.g., a number-average molecular weight of 1,000 or more) as the main component increases the initial viscosity of the mixture of the main component and curing agent. This increased initial viscosity is advantageous when the mixture is applied to a desired location and allowed to react while being held in close contact with the location. Conventional two-component curable polyurethane resin compositions, such as those described in Patent Document 1, employ compositions designed to achieve a relatively high initial viscosity. In response to this, the inventors have found through their studies that when a two-component curable polyurethane resin composition is used for waterproofing purposes in places such as openings in buildings where cable bundles or the like are passed through through-holes, with conventional two-component curable polyurethane resin compositions, the mixture does not penetrate to the inside of the cable bundle that is passed through the through-hole, resulting in insufficient filling of the polyurethane resin and the formation of gaps, making it impossible to fully demonstrate waterproofing. One possible solution to this problem would be to reduce the molecular weight of the polybutadiene polyol used, but there are restrictions on the use of low-molecular-weight polybutadiene polyols from the standpoint of supply.

[0005] An object of the present invention is to provide a two-component curable polyurethane resin composition that uses a high-molecular-weight polybutadiene polyol as a base agent, yet can achieve a low initial viscosity for a mixture of this base agent and a curing agent, so that the mixture can sufficiently penetrate even narrow gaps and exhibit excellent water-stopping properties, and that can also provide a polyurethane resin with excellent flame retardancy. [Means for solving the problem]

[0006] The above problems were solved by the following means. [1] A two-component curable polyurethane resin composition comprising a base agent and a curing agent, the base material contains (A) a polybutadiene polyol compound, (B) a phosphoric acid ester compound, (C) a plasticizer A, (D) a metal hydroxide, and (E) a catalyst; the curing agent contains (F) a polyisocyanate compound and (G) a plasticizer B; The number average molecular weight of the component (A) in the base resin is 1200 to 3000, The viscosity of the base agent is 5 to 50 Pa·s, and the viscosity of the curing agent is 0.01 to 0.15 Pa·s. A two-component curable polyurethane resin composition for use as a waterproofing material. [2] The two-component curable polyurethane resin composition according to [1] above, wherein the two-component curable polyurethane resin composition is produced by mixing and reacting the main agent and the curing agent in such a ratio that the molar ratio of the hydroxyl groups (OH) of component (A) in the main agent to the isocyanate groups (NCO) of component (F) in the curing agent is NCO / OH = 0.5 to 2.0. [3] The two-component curable polyurethane resin composition according to [1] or [2] above, wherein the polyurethane resin obtained by mixing and reacting the base agent and the curing agent has an oxygen index of 26 or more. [4] The two-component curable polyurethane resin composition according to any one of [1] to [3] above, wherein the content of component (B) in the main component is 3 to 10 mass %, and component (B) contains a halogen-containing phosphate ester compound. [5] The two-component curable polyurethane resin composition according to any one of [1] to [4] above, wherein the content of component (D) in the main component is 53 to 63 mass %, and component (D) contains aluminum hydroxide and / or magnesium hydroxide. [6] The two-component curable polyurethane resin composition according to any one of [1] to [5] above, wherein the content of component (C) in the main component is 3 to 10 mass %, and component (C) includes at least one of a phthalate ester compound, an adipic acid ester compound, a process oil, and a polybutene compound. [7] The two-component curable polyurethane resin composition according to any one of [1] to [6] above, wherein the content of component (G) in the curing agent is 80 to 90 mass %, and component (G) includes at least one of a phthalate ester compound, an adipic acid ester compound, a process oil, and a polybutene compound. [8] The two-component curable polyurethane resin composition according to any one of [1] to [7] above, wherein the content of the component (F) in the curing agent is 10 to 20 mass %, and the component (F) includes diphenylmethane diisocyanate. [9] The two-component curable polyurethane resin composition according to any one of [1] to [8] above, wherein the initial viscosity of a mixture of the base agent and the curing agent is 4 to 7 Pa·s. [Effects of the Invention]

[0007] The two-component curable polyurethane resin composition of the present invention uses a high-molecular-weight polybutadiene polyol as the base agent, and yet the initial viscosity of the mixture of this base agent and curing agent can be made low. As a result, this mixture can penetrate sufficiently into narrow gaps and exhibit excellent water-stopping properties. Furthermore, the polyurethane resin obtained by the reaction (polyaddition reaction) between the base agent and the curing agent exhibits high flame retardancy. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram specifically illustrating one example of a usage form of the two-component curable polyurethane resin composition of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A preferred embodiment of the two-component curable polyurethane resin composition of the present invention will be described below, but the present invention is not limited to the following embodiment except as defined by the present invention.

[0010] [Two-component curable polyurethane resin composition] The two-component curable polyurethane resin composition of the present invention (hereinafter also referred to as the "two-component curable composition of the present invention") is composed of a base agent containing a high-molecular-weight polybutadiene polyol compound that undergoes a polyaddition reaction and is incorporated as a constituent component of the polyurethane resin, and a curing agent containing a polyisocyanate compound that is also incorporated as a constituent component of the polyurethane resin through a polyaddition reaction. That is, the base agent and curing agent are contained independently of each other (in other words, it is a composition set containing the base agent and the curing agent). Therefore, the two-component curable polyurethane resin composition undergoes a polyaddition reaction when the base agent and the curing agent are mixed, and this polyaddition reaction results in the production of a polyurethane resin. The term "composition" in the two-component curable polyurethane resin composition means that the base agent is a homogeneous mixture (composition) of the components that make up the base agent, and that the curing agent is also a homogeneous mixture (composition) of the components that make up the curing agent. Note that a "homogeneous mixture" is sufficient as long as it is substantially homogeneous. The concentrations of the components may be completely uniform, and some concentration variation is acceptable as long as it does not impair the effects of the present invention.

[0011] The two-component curable composition of the present invention can control the initial viscosity of the base agent and the curing agent when mixed to a low value by controlling the viscosity of each agent within a desired range through ingenuity in the component composition, and thus can be suitably used for forming a water-stopping material that prevents water from entering infrastructure facilities or buildings, etc. In the present invention, the term "water-stopping material" is a concept that includes not only materials that directly prevent water from entering, but also sealants that prevent the inflow of, for example, moisture-rich gases (humidity). The two-component curable composition of the present invention can be used to form a waterstop material (for a waterstop material) in, for example, infrastructure facilities, mainly electric power and railways, large plants, buildings, etc. Therefore, the two-component curable composition of the present invention is preferably a two-component curable composition for forming a waterstop material for infrastructure facilities, plant facilities, or buildings. More preferably, the two-component curable composition of the present invention can be used to form a waterstop material for buildings having openings through which cable bundles or the like are passed, or a sealing material for distribution boards and the like in buildings. FIG. 1 shows a schematic diagram of an example of an application of the two-component curable composition of the present invention, in which the composition is used to form a water-stop material. A cable bundle 3 is passed through a through-hole in a concrete wall 2. A formwork 4 and putty 5 are used to form an area into which a mixed solution 1 (a base agent and a curing agent) constituting the two-component curable composition of the present invention is poured. By pouring the mixed solution 1 into the through-hole, a polyaddition reaction of the mixed solution 1 occurs, producing a polyurethane resin, which fills the through-hole and forms a water-stop material. The mixed solution 1 (a base agent and a curing agent) has a low initial viscosity and can penetrate deep into the cable bundle 3 (the gaps between the cables). The reaction (polyaddition reaction) of the mixed solution 1 that has penetrated deep into the cable bundle 3 produces a polyurethane resin, providing excellent water-stop properties.

[0012] In this specification, the "initial viscosity (initial mixed viscosity)" of a mixture of a base agent and a curing agent is measured one minute after mixing the base agent and the curing agent, which have been adjusted to a temperature of 25±3°C, and rotating the viscometer four minutes after the start of mixing. The viscometer used for this measurement is a B8H-type viscometer (manufactured by Toki Sangyo Co., Ltd.), with a No. 6 rotor and a rotation speed of 50 rpm. When viscosity is specified in this invention or this specification, unless otherwise specified, the viscosity is measured at 25°C. In the present invention, the initial viscosity of the mixture of the base agent and curing agent is preferably 1 to 30 Pa·s, more preferably 2 to 15 Pa·s, even more preferably 3 to 10 Pa·s, even more preferably 4 to 7 Pa·s, and even more preferably 4 to 6 Pa·s. Particularly when the two-component curable composition of the present invention is used as a waterstop material, if the initial viscosity is too low, the liquid will easily leak through gaps in formwork, etc., while if the initial viscosity is too high, it will be difficult to penetrate narrow gaps. By controlling the initial viscosity of the mixture of the base agent and curing agent to a low level, but not too low, when used as a waterstop material, the mixture of the base agent and curing agent can be sufficiently penetrated into narrow gaps between cable bundles, and the mixture can remain in the desired location.

[0013] The mixing ratio of the base agent and the curing agent is preferably such that the molar ratio (NCO / OH) of the hydroxyl groups (OH) of the (A) polybutadiene polyol compound in the base agent to the isocyanate groups (NCO) of the (F) polyisocyanate compound in the curing agent is 0.5 to 2.0, more preferably 0.7 to 1.7, even more preferably 0.9 to 1.5, and even more preferably 1.0 to 1.2. Alternatively, for example, the mixing ratio of the base agent and the curing agent can be set to a mass ratio of [base agent]:[curing agent]=4.5:1 to 5.5:1. By mixing the base agent and the curing agent, each of which has a controlled viscosity, in the above-mentioned preferred molar or mass ratio, the initial viscosity of the mixture of the base agent and the curing agent can be controlled to an appropriately low range. Furthermore, after the main component and curing agent of the two-component curable composition of the present invention are mixed to cause a polyaddition reaction (preferably, after mixing the main component and the curing agent, at least 336 hours have elapsed at 10 to 50°C), the hardness (Shore A hardness) of the polyurethane resin is preferably 20 to 65, more preferably 25 to 60, and even more preferably 30 to 55. By adjusting the hardness of the resulting polyurethane resin from the two-component curable composition of the present invention so that it falls within the above-mentioned preferred range, the composition can be used as a waterproofing material with even better water pressure resistance.

[0014] The polyurethane resin obtained by mixing and reacting the two-component curable composition of the present invention is a resin with excellent flame retardancy. The oxygen index (OI value, the higher the value, the more flame retardant) of the polyurethane resin calculated in accordance with JIS K 7201-2 (2007) is preferably 26 or more, more preferably 30 or more, and even more preferably 33 or more. By setting the oxygen index within the above preferred range, the resin can be used more safely as a waterproofing material for a through hole through which a cable bundle is passed.

[0015] The main component and the curing agent constituting the two-component curable composition of the present invention will be described below.

[0016] (Main ingredient) In the two-component curable composition of the present invention, the main component contains the following components (A) to (E). (A) Polybutadiene polyol compound (B) Phosphate ester compound (C) Plasticizer A (D) Metal hydroxide (E) Catalyst In the present invention and this specification, in order to distinguish between the plasticizer contained in the base agent and the plasticizer contained in the curing agent described below, the plasticizer contained in the base agent will be referred to as "plasticizer A" and the plasticizer contained in the curing agent will be referred to as "plasticizer B."

[0017] The viscosity of the base resin is 5 to 50 Pa·s. From the viewpoint of setting the initial viscosity of the mixture with the curing agent in the above-mentioned preferred range, the viscosity is preferably 10 to 45 Pa·s, more preferably 15 to 40 Pa·s, even more preferably 15 to 35 Pa·s, and even more preferably 25 to 35 Pa·s. The viscosity of the base agent is measured by placing approximately 500 g of the base agent in a 500 ml round can (diameter approximately 85 mm), leaving it in a constant temperature room or constant temperature water bath at 25 ± 3°C for at least 2 hours, and then using a B8H type viscometer (manufactured by Toki Sangyo Co., Ltd.) with rotor No. 6 at a rotation speed of 20 rpm, taking the measurement value 1 minute after the start of rotation.

[0018] Each component contained in the base agent will be described below. Each component described below can be used alone or in combination of two or more. The same applies to each component contained in the curing agent described below.

[0019] (A) Polybutadiene polyol compound The base material contains (A) a polybutadiene polyol compound (also referred to as component (A)). Component (A) is preferably a compound having hydroxyl groups at both ends of a polybutadiene compound obtained by polymerizing a butadiene compound. The polybutadiene polyol compound is preferably a diol compound (polybutadiene diol compound). A polyaddition reaction between component (A) and a polyisocyanate compound contained in a curing agent described below generates urethane bonds, resulting in a polyurethane resin. The butadiene compound is a compound having a butadiene skeleton. Examples of the butadiene compound include 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene). The polybutadiene structure constituting the polybutadiene polyol compound includes a polybutadiene rubber structure (which may be either a cis-1,4 structure or a trans-1,4 structure), a polyisoprene rubber structure (which may be either a cis-1,4 structure or a trans-1,4 structure), and a 1,2-polybutadiene structure (1,2 vinyl structure). Component (A) can be produced by a conventional method, or a commercially available product such as polybutadiene diol (trade name: Poly bd (registered trademark) R-45HT, number average molecular weight: 2800, viscosity: 5.0 Pa s (30°C), manufactured by Idemitsu Kosan Co., Ltd.) may be used.

[0020] According to the two-component curable composition of the present invention, even when component (A) is a high-molecular-weight polybutadiene polyol, the viscosity of the base agent containing component (A) and the initial viscosity of the mixture obtained by mixing the base agent with a curing agent can be controlled to be low. In the present invention and this specification, a "high molecular weight" compound refers to a compound having a number-average molecular weight of 1,000 or more. In the two-component curable composition of the present invention, the number-average molecular weight of component (A) is 1,200 to 3,000. The lower limit of the number-average molecular weight can be 1,500, 1,900, or 2,300. That is, the number-average molecular weight of component (A) can be in the range of 1,500 to 3,000, 1,900 to 3,000, or 2,300 to 3,000. When a commercially available product is used as component (A), the number average molecular weight of component (A) can be the value listed in the catalog.

[0021] The content of the component (A) in the base material is preferably 20 to 40% by mass, more preferably 22 to 37% by mass, even more preferably 25 to 35% by mass, and still more preferably 25 to 30% by mass.

[0022] (B) Phosphate ester compound The base agent contains (B) a phosphate ester compound (also referred to as component (B)). The inclusion of component (B) in the base agent improves the flame retardancy of the resulting two-component curable composition of the present invention (or the polyurethane resin obtained by reacting the composition). Antimony compounds are known as flame retardants commonly blended into polyurethane resins. However, recent regulatory changes have made their handling more stringent, requiring notification for handling of antimony compounds at concentrations of 1% by mass or more. This handling is expected to become even more stringent in the future. In contrast, the two-component curable composition of the present invention uses a phosphate ester compound as a flame retardant, allowing for stable supply of the two-component curable composition of the present invention without any particular restrictions on handling. Furthermore, it is preferable to use a flame retardant with a low viscosity. Component (B) preferably contains a halogen-containing phosphate ester compound, and more preferably a halogen-containing condensed phosphate ester compound. A commercially available example of such a phosphate ester compound is a halogen-containing condensed phosphate ester manufactured by Daihachi Chemical Industry Co., Ltd. (trade name: CR-504L, viscosity: 0.8 to 1.1 Pa s).

[0023] The content of the component (B) in the base resin is preferably 3 to 10 mass %, more preferably 4 to 8 mass %, and even more preferably 5 to 7 mass %, from the viewpoint of further improving the flame retardancy of the cured product produced from the two-component curable composition of the present invention.

[0024] (C) Plasticizer A The base agent contains (C) plasticizer A (also referred to as component (C)). By including plasticizer A in the base agent, the viscosity of the base agent or the initial viscosity of the mixture of the base agent and the curing agent can be controlled within a preferred range. Examples of component (C) include phthalate ester compounds, adipic acid ester compounds, process oils, polybutene compounds (polyisobutylene compounds), benzoate ester compounds, epoxy compounds, and chlorinated paraffin compounds. Among these, the base agent preferably contains at least one of phthalate esters, adipic acid ester compounds, process oils, and polybutene compounds, and more preferably contains an adipic acid ester compound. The adipic acid ester compound has little effect on cable sheaths, a lower viscosity than other plasticizers, and excellent cold resistance, heat resistance, and light resistance, making it more suitable for use as plasticizer A. An example of a commercially available product of the adipic acid ester compound is dioctyl adipate (viscosity: 9.6 mPa·s (30° C.), manufactured by Taoka Chemical Co., Ltd.). The content of the component (C) in the base agent is preferably 3 to 10% by mass, more preferably 4 to 8% by mass, and even more preferably 5 to 7% by mass, from the viewpoint of controlling the viscosity of the base agent or the initial viscosity of the mixture of the base agent and the curing agent within a preferred low viscosity range.

[0025] (D) Metal hydroxide The base material contains (D) a metal hydroxide (also referred to as component (D)). Component (D) functions as a flame retardant in the same manner as component (C). Examples of component (D) include aluminum hydroxide and magnesium hydroxide. The content of the component (D) in the base resin is preferably 43 to 73 mass%, more preferably 48 to 68 mass%, and even more preferably 53 to 63 mass%, from the viewpoint of further improving the flame retardancy of the cured product produced from the two-component curable composition of the present invention.

[0026] (E) Catalyst The base resin contains a catalyst (E) (also referred to as component (E)). Component (E) has the effect of promoting the polyaddition reaction (formation of urethane bonds) between the polybutadiene polyol compound (component (A)) in the base resin and the polyisocyanate compound (component (F)) in the curing agent. Examples of component (E) include amine catalysts and metal catalysts. Examples of metal catalysts include catalysts containing tin. Commercially available catalysts containing such tin include Adeka STAB BT-11 (manufactured by ADEKA Corporation). The content of the component (E) in the base resin is preferably 0.0003 to 0.0020% by mass, more preferably 0.0005 to 0.0018% by mass, and even more preferably 0.0008 to 0.0018% by mass, from the viewpoint of promoting the polyaddition reaction.

[0027] The base material may contain other components in addition to the above-mentioned components (A) to (E), such as flame retardants, antioxidants, pigments, ultraviolet absorbers, surfactants, dispersants, antistatic agents, weight-reducing agents, expanding agents, fiber chips, fragrances, etc. The base resin may contain an antimony compound as a flame retardant. As mentioned above, handling of antimony compounds at 1% by mass or more requires notification. Therefore, the content of the antimony compound in the base resin is preferably less than 1% by mass, and may be 0.8% by mass or less, or even 0.5% by mass or less. Furthermore, from the viewpoint of improving the flame retardancy of the polyurethane resin produced from the two-component curable composition of the present invention, the content is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.10% by mass or more. Furthermore, by incorporating an antimony compound into the two-component curable composition of the present invention, the initial viscosity of the mixture of the base resin and the curing agent can be reduced.

[0028] (hardening agent) In the two-component curable composition of the present invention, the curing agent contains the following components (F) and (G). (F) Polyisocyanate compounds (G) Plasticizer B

[0029] The viscosity of the curing agent is 0.01 to 0.15 Pa·s. From the viewpoint of setting the initial viscosity of the mixture with the base agent in the above-mentioned preferred range, the viscosity of the curing agent is preferably 0.05 to 0.15 Pa·s, more preferably 0.07 to 0.15 Pa·s, and may be 0.07 to 0.11 Pa·s. The viscosity of the curing agent is measured by placing about 400 g of the curing agent in a 500 ml round can (diameter about 85 mm), leaving it in a constant temperature room or constant temperature water bath at 25±3°C for more than 2 hours, and then using a B8H type viscometer (manufactured by Toki Sangyo Co., Ltd.) with rotor No. 2 at a rotation speed of 50 rpm, one minute after the start of rotation.

[0030] Each component contained in the curing agent will be described below.

[0031] (F) Polyisocyanate compounds The curing agent contains (F) a polyisocyanate compound (also referred to as component (F)). A polyaddition reaction between component (A) contained in the base resin and component (F) contained in the curing agent generates urethane bonds, resulting in a polyurethane resin. The component (F) is not particularly limited as long as it has two or more isocyanate groups in one molecule, and examples thereof include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), 3,3'-bitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate, and the like. Examples of suitable polyisocyanates include aromatic polyisocyanates such as diphenylmethane diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and paraphenylene diisocyanate (PPDI); and alicyclic or aliphatic polyisocyanates such as 4,4'-dicyclohexylmethane diisocyanate (H12MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDII). One or more of these may be used. Among these, it is preferable that component (F) contains 4,4'-diphenylmethane diisocyanate. The component (F) may be a commercially available product, such as diphenylmethane diisocyanate (trade name: Cosmonate M-300, manufactured by Mitsui Chemicals, Inc.).

[0032] The content of the component (F) in the curing agent is preferably 5 to 25 mass %, more preferably 10 to 20 mass %, and even more preferably 15 to 20 mass %, from the viewpoint of allowing the polyaddition reaction with the component (A) to proceed without excess or deficiency.

[0033] (G) Plasticizer B The curing agent contains (G) plasticizer B (also referred to as component (G)). By including plasticizer B in the curing agent, the viscosity of the curing agent or the initial viscosity of the mixture of the base resin and curing agent can be controlled within a preferred low-viscosity range. Examples of component (G) include phthalate ester compounds, adipic acid ester compounds, process oils, polybutene compounds, benzoic acid ester compounds, epoxy compounds, and chlorinated paraffin compounds. Among these, the curing agent preferably contains at least one of phthalate esters, adipic acid ester compounds, process oils, and polybutene compounds, and more preferably contains a phthalate ester compound. When the polyisocyanate compound in the curing agent reacts with moisture in the air, the curing agent may become cloudy white. Using such a curing agent as is can result in poor curing. On the other hand, some plasticizers become cloudy when blended with the curing agent. When such plasticizers are used, it becomes difficult to distinguish whether the clouding is due to the reaction of the polyisocyanate compound. The phthalate ester does not cause clouding even when blended into the curing agent, and therefore can be more suitably used as the plasticizer B. An example of a commercially available phthalate ester compound is diisononyl phthalate (viscosity: 78 mPa s, manufactured by C.G. Ester Corporation).

[0034] The content of the component (G) in the curing agent is preferably 75 to 95 mass %, more preferably 80 to 90 mass %, and even more preferably 80 to 85 mass %, from the viewpoint of controlling the viscosity of the curing agent or the initial viscosity of the mixture of the base agent and the curing agent within a preferred low viscosity range.

[0035] The curing agent may contain other components in addition to the above-mentioned components (F) and (G), such as flame retardants, antioxidants, pigments, ultraviolet absorbers, surfactants, dispersants, antistatic agents, inorganic fillers, flame retardants, lightweight materials, expanding agents, fiber chips, fragrances, etc. [Example]

[0036] The present invention will be described in more detail based on the following examples and comparative examples, but the present invention is not limited to these.

[0037] <Preparation of Two-Part Curable Composition> The base resin and curing agent were prepared according to the blending ratios shown in Table 1 below to obtain two-component curable compositions of Examples 1 and 2 and Comparative Examples 1 to 3. The materials used as each component were as follows: Component (A): Polybutadiene diol, trade name: Poly bd (registered trademark) R-45HT, number average molecular weight: 2800, viscosity: 5.0 Pa·s (30°C), manufactured by Idemitsu Kosan Co., Ltd. Component (B): Halogen-containing condensed phosphate ester, product name: CR-504L, viscosity: 0.8 to 1.1 Pa·s, manufactured by Daihachi Chemical Industry Co., Ltd. Component (C): Dioctyl adipate, viscosity: 9.6 mPa·s (30°C), manufactured by Taoka Chemical Co., Ltd. Ingredient (D): Aluminum hydroxide Ingredient (E): Organotin compounds Component (F): 4,4'-diphenylmethane diisocyanate, trade name: Cosmonate M-300, manufactured by Mitsui Chemicals, Inc. Component (G): Diisononyl phthalate, viscosity: 78 mPa·s, manufactured by C.G. Ester Co., Ltd. Antimony: Antimony trioxide

[0038] (viscosity measurement) The viscosity of the base resin and curing agent of each two-component curable composition obtained above was measured. The viscosity of the base resin was measured by placing approximately 500 g of the base resin in a 500 ml round can (approximately 85 mm in diameter) and leaving it in a thermostatic water bath at 25 ± 3°C for two hours. The viscosity was measured one minute after the start of rotation using a B8H viscometer (manufactured by Toki Sangyo Co., Ltd.) with a rotor No. 6 at 20 rpm. The viscosity of the curing agent was measured by placing approximately 400 g of the curing agent in a 500 ml round can (approximately 85 mm in diameter) and leaving it in a thermostatic water bath at 25 ± 3°C for two hours. The viscosity was measured one minute after the start of rotation using a B8H viscometer (manufactured by Toki Sangyo Co., Ltd.) with a rotor No. 2 at 50 rpm. Furthermore, the base agent and the curing agent were adjusted to a temperature of 25±3°C in advance and mixed in the mixing ratio shown in Table 1 below ([base agent]:[curing agent] = 5:1 (mass ratio)). Four minutes after the start of mixing, the viscometer was rotated, and the measurement value after one minute was taken as the initial viscosity of the mixture of the base agent and the curing agent (initial mixed viscosity). The viscometer used for this measurement was a B8H type viscometer (manufactured by Toki Sangyo Co., Ltd.), with a No. 6 rotor and a rotation speed of 50 rpm. The measured viscosities of the two-component curable compositions are also shown in Table 1 below.

[0039] <Production of polyurethane resin> The base agent and curing agent of each of the two-component curable compositions obtained above were mixed to the mixing ratio shown in Table 1 below ([base agent]:[curing agent] = 5:1 (mass ratio)), and polyurethane resins were obtained by polyaddition reaction. The flame retardancy of each of the obtained polyurethane resins was evaluated by the oxygen index measurement described below.

[0040] (Oxygen index measurement) Each polyurethane resin obtained was cut into a length of 100 mm, a width of 6.1 to 6.9 mm, and a thickness of 2.0 to 3.1 mm to prepare a test specimen. The oxygen index of each test specimen was measured using a D-type candle combustion tester (manufactured by Toyo Seiki Seisakusho) in accordance with JIS K 7201-2:2007. This test indicates the minimum oxygen concentration (volume %) required for the test specimen to continue burning in a mixed gas stream of oxygen and nitrogen, with a higher value indicating higher flame retardancy. For Comparative Example 2, the oxygen index was not measured.

[0041] [Table 1]

[0042] In the two-component curable compositions of Comparative Examples 1 and 2, in which the viscosity of the base agent was high, the initial viscosity of the mixture of the base agent and curing agent was also high. Furthermore, even though the viscosity of the base agent was within an appropriate range, the two-component curable composition of Comparative Example 3, in which no phosphate ester compound was blended in the base agent, resulted in a low oxygen index of the polyurethane resin after the reaction. In contrast, in the two-component curable compositions of Examples 1 and 2 satisfying the configuration of the present invention, by blending plasticizer A with the base agent, it was possible to control the viscosity of the base agent to a low viscosity even while using a high molecular weight polybutadiene diol compound, thereby controlling the initial viscosity of the mixture of the base agent and curing agent within a low viscosity range. Furthermore, it was shown that the polyurethane resin after reaction of the two-component curable composition had a high oxygen index and could be a resin with excellent flame retardancy. Furthermore, a comparison between Examples 1 and 2 shows that blending a specific small amount of antimony compound not only further increased the oxygen index but also further reduced the initial viscosity of the mixture of the base agent and curing agent. [Explanation of symbols]

[0043] 1. Mixture of base agent and hardener 2. Concrete wall 3 Cable bundles 4. Formwork 5. Putty

Claims

1. A two-component curable polyurethane resin composition comprising a base agent and a curing agent, the base material contains (A) a polybutadiene polyol compound, (B) a phosphoric acid ester compound, (C) a plasticizer A, (D) a metal hydroxide, and (E) a catalyst; The curing agent contains (F) a polyisocyanate compound and (G) a plasticizer B, the number average molecular weight of the component (A) in the base resin is 1,200 to 3,000; The viscosity of the base agent is 5 to 50 Pa·s, and the viscosity of the curing agent is 0.01 to 0.15 Pa·s. A two-component curable polyurethane resin composition for use as a waterproofing material.

2. 2. The two-component curable polyurethane resin composition according to claim 1, wherein the two-component curable polyurethane resin composition is produced by mixing and reacting the main component and the curing agent in such a ratio that the molar ratio of hydroxyl groups (OH) of component (A) in the main component to isocyanate groups (NCO) of component (F) in the curing agent is NCO / OH = 0.5 to 2.0, thereby producing a polyurethane resin.

3. 3. The two-component curable polyurethane resin composition according to claim 2, wherein the polyurethane resin obtained by mixing and reacting the base agent and the curing agent has an oxygen index of 26 or more.

4. 4. The two-component curable polyurethane resin composition according to claim 3, wherein the content of component (B) in the main component is 3 to 10 mass %, and component (B) includes a halogen-containing phosphate ester compound.

5. 5. The two-component curable polyurethane resin composition according to claim 4, wherein the content of component (D) in the main component is 53 to 63 mass%, and component (D) comprises aluminum hydroxide and / or magnesium hydroxide.

6. 6. The two-component curable polyurethane resin composition according to claim 5, wherein the content of component (C) in the main component is 3 to 10 mass%, and component (C) includes at least one of a phthalate ester compound, an adipic acid ester compound, a process oil, and a polybutene compound.

7. 7. The two-component curable polyurethane resin composition according to claim 6, wherein the content of component (G) in the curing agent is 80 to 90 mass%, and component (G) includes at least one of a phthalate ester compound, an adipic acid ester compound, a process oil, and a polybutene compound.

8. 8. The two-component curable polyurethane resin composition according to claim 7, wherein the content of component (F) in the curing agent is 10 to 20 mass%, and component (F) includes diphenylmethane diisocyanate.

9. The two-component curable polyurethane resin composition according to any one of claims 1 to 8, wherein the initial viscosity of a mixture of the base agent and the curing agent is 4 to 7 Pa·s.

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