One-part curable composition and cured product of the one-part curable composition

Abstract

To provide a one-liquid type curable composition that has high transparency and weather resistance, does not impair the beauty of a building appearance, and does not stain the surrounding area for a long time.SOLUTION: A one-liquid type curable composition contains an isocyanate group-containing urethane prepolymer (A) and a thixotropy imparting agent (B). A cured product of the one-liquid type curable composition has a haze value of 40% or less in accordance with ASTM D1003-97.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a one-component curable composition containing an isocyanate group-containing urethane prepolymer and a cured product of the one-component curable composition. [Background technology]

[0002] Usually, the Building Standards Act requires the installation of ventilation equipment that can replace the air in buildings such as houses at a specified time, so a ventilation device is often installed inside the building. The ventilation device has a duct that communicates with the outdoors, and the end of the duct is connected to a ventilation port opened on the exterior wall surface. A vent cap is attached to the ventilation port to prevent rainwater, etc. from entering inside the ventilation port. Here, if there is even a small gap between the vent cap and the exterior wall, rainwater, etc. will enter through this gap. Therefore, in order to prevent rainwater, etc. from entering through the gap between the vent cap and the exterior wall, the gap is filled with a sealant, and a waterproof seal is formed by this sealant.

[0003] In addition, with the trend toward more sophisticated designs for detached houses in recent years, exterior walls painted in a variety of patterns and colors are being used. In contrast, the sealant used in the gap between the vent cap and the exterior wall is usually only white or comes in only a few colors, and is often chosen to be relatively close to the color of the exterior wall. If such a sealant is used on an exterior wall with a high level of design, the area around the vent cap may stand out, which may detract from the aesthetics of the entire building.

[0004] On the other hand, although sealants for use in the joints of exterior walls may be available in a wide variety of colors, the contractor for installing the vent cap is generally different from the contractor who fills the joints of the exterior walls with the sealant. In reality, it is not realistic for the contractor for installing the vent cap to prepare a sealant for use only in the waterproof seal of the vent cap for each building with a different pattern and color.

[0005] In order to solve the above problems, transparent sealants are commercially available for use in the gap between the vent cap and the exterior wall, but their transparency is low and they may still impair the aesthetic appearance of the building. In addition, the transparent sealants cannot use pigments such as titanium oxide, which has high hiding power, from the viewpoint of transparency, so their weather resistance is insufficient, which is a problem in the current situation where the durability of the entire building is being improved.

[0006] Most of this type of sealant is silicone-based or modified silicone-based (Patent Document 1), and has problems such as water-repellent contamination due to silicone precursor molecules after application and contamination of the surrounding area due to the plasticizers contained. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2001-055799 A Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made to solve such problems, and an object of the present invention is to provide a one-component curable composition that has high transparency and weather resistance, does not impair the aesthetic appearance of the building exterior, and does not contaminate the surrounding area for a long period of time. [Means for solving the problem]

[0009] An embodiment of the present invention is a one-component curable composition comprising an isocyanate group-containing urethane prepolymer (A) and a thixotropy-imparting agent (B), and the one-component curable composition has an ASTM The one-component curable composition has a haze value of 40% or less as measured by D1003-97.

[0010] An embodiment of the present invention is a one-part curable composition further comprising a compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group.

[0011] An embodiment of the present invention is a one-component curable composition, in which the isocyanate group-containing urethane prepolymer (A) is a reaction product of an organic isocyanate compound (a) and an active hydrogen-containing compound (b), and the active hydrogen-containing compound (b) comprises an active hydrogen-containing (meth)acrylic polymer (b-1), a compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, and a polyol (b-3) having a number average molecular weight of 1,000 or more.

[0012] An embodiment of the present invention is a one-part curable composition in which the active hydrogen-containing compound (b) contains the active hydrogen-containing (meth)acrylic polymer (b-1) in an amount of 1.0 mass % or more and 7.0 mass % or less.

[0013] An embodiment of the present invention is a one-component curable composition, in which the active hydrogen-containing compound (b) contains the compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group in an amount of 1.0 mass % or more and 7.0 mass % or less.

[0014] An embodiment of the present invention is a one-component curable composition, in which the organic isocyanate compound (a) contains an alicyclic polyisocyanate compound.

[0015] An embodiment of the present invention is a one-component curable composition, in which the thixotropy-imparting agent (B) contains finely divided silica.

[0016] An embodiment of the present invention is a one-part curable composition, wherein the compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group is an oxazolidine compound.

[0017] An embodiment of the present invention is a one-component curable composition, wherein the isocyanate group-containing urethane prepolymer (A) has an isocyanate group content of 0.10 mass % or more and 15 mass % or less.

[0018] An embodiment of the present invention is a one-component curable composition, in which the isocyanate group-containing urethane prepolymer (A) is a reaction product in which 1.5 mol to 8.0 mol of isocyanate groups in the organic isocyanate compound (a) are reacted with 1.0 mol of active hydrogen in the active hydrogen-containing compound (b).

[0019] An embodiment of the present invention is a one-component curable composition comprising the thixotropy-imparting agent (B) in an amount of 0.50 parts by mass or more and 20 parts by mass or less based on the isocyanate group-containing urethane prepolymer (A) (solid content).

[0020] An embodiment of the present invention is a one-component curable composition in which the compound (C) which is hydrolyzed by moisture to generate an active hydrogen-containing functional group has an active hydrogen of 0.10 mol or more and 1.5 mol or less per 1.0 mol of isocyanate groups in the isocyanate group-containing urethane prepolymer (A).

[0021] An embodiment of the present invention is a cured product of the one-part curable composition. Effect of the Invention

[0022] According to an embodiment of the present invention, a one-component curable composition containing an isocyanate group-containing urethane prepolymer (A) and a thixotropy-imparting agent (B) has a haze value of 40% or less as measured by ASTM D1003-97. This makes it possible to obtain a one-component curable composition that has high transparency and weather resistance, does not impair the aesthetic appearance of the building exterior, and does not contaminate the surrounding area for a long period of time.

[0023] According to an embodiment of the present invention, a one-component curable composition can be obtained that can further improve transparency and weather resistance and that can become a cured product that does not impair the aesthetic appearance of the building exterior and does not contaminate the surroundings for a long period of time. In the isocyanate group-containing urethane prepolymer (A), which is a reaction product of an organic isocyanate compound (a) and an active hydrogen-containing compound (b), the active hydrogen-containing compound (b) contains an active hydrogen-containing (meth)acrylic polymer (b-1), a compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, and a polyol (b-3) having a number average molecular weight of 1000 or more.

[0024] According to an embodiment of the present invention, the active hydrogen-containing compound (b) contains 1.0 mass % or more and 7.0 mass % or less of the active hydrogen-containing (meth)acrylic polymer (b-1), whereby a cured product having further improved weather resistance and rubber physical properties can be obtained.

[0025] According to an embodiment of the present invention, the active hydrogen-containing compound (b) contains 1.0 mass % or more and 7.0 mass % or less of a compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, so that a cured product having further improved weather resistance and rubber physical properties can be obtained.

[0026] According to an embodiment of the present invention, the organic isocyanate compound (a) contains an alicyclic polyisocyanate compound, so that a cured product having further improved transparency and weather resistance and durability can be obtained.

[0027] According to an embodiment of the present invention, the thixotropy-imparting agent (B) contains finely divided silica, so that the transparency can be improved more reliably. [Brief description of the drawings]

[0028] [Figure 1] FIG. 2 is a plan view illustrating a test method for staining in the examples and comparative examples. [Diagram 2] FIG. 2 is a side view illustrating a test method for staining in the examples and comparative examples. [Diagram 3] 1 is a photograph showing the results of weather resistance tests in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Next, the one-component curable composition of the present invention will be described in detail. The one-component curable composition of the present invention is a one-component curable composition containing an isocyanate group-containing urethane prepolymer (A) and a thixotropy-imparting agent (B), and the haze value of the cured product of the one-component curable composition according to ASTM D1003-97 is 40% or less.

[0030] The haze value according to ASTM D1003-97 of the cured product of the one-component curable composition of the present invention is not particularly limited as long as it is 40% or less. From the viewpoint of a balance between ease of production and excellent transparency, the haze value is preferably from 8% to 30%, and particularly preferably from 12% to 25%.

[0031] Next, the components of the one-component curable composition of the present invention will be described below.

[0032] Isocyanate group-containing urethane prepolymer (A) The isocyanate group-containing urethane prepolymer (A) is a compound obtained by mixing and reacting an organic isocyanate compound (a) and an active hydrogen-containing compound (b) in a molar ratio in which the number of moles of isocyanate groups in the organic isocyanate compound (a) is in excess of the number of moles of active hydrogen in the active hydrogen-containing compound (b). The isocyanate group-containing urethane prepolymer (A) is a curing component.

[0033] The content of isocyanate groups in the isocyanate group-containing urethane prepolymer (A) is not particularly limited, but the lower limit is preferably 0.10 mass%, more preferably 0.20 mass%, and particularly preferably 0.40 mass%, from the viewpoints of workability and adhesiveness of the resulting one-component curable composition. On the other hand, the upper limit of the content of isocyanate groups in the isocyanate group-containing urethane prepolymer (A) is preferably 15.0 mass%, more preferably 12.0 mass%, and particularly preferably 10.0 mass%, from the viewpoints of foaming during curing of the resulting one-component curable composition and physical properties of the cured product.

[0034] The molar number of isocyanate groups of the organic isocyanate compound relative to 1.0 mole of active hydrogen of the active hydrogen-containing compound is not particularly limited as long as the molar number of isocyanate groups is excessive, but the lower limit is preferably 1.5 moles, more preferably 2.0 moles, even more preferably 3.0 moles, and particularly preferably 4.0 moles from the viewpoints of workability and adhesiveness of the one-component curable composition obtained, while the upper limit is preferably 8.0 moles, more preferably 6.0 moles, and particularly preferably 5.0 moles from the viewpoints of foaming during curing of the one-component curable composition obtained and physical properties of the cured product.

[0035] Organic isocyanate compound (a) The organic isocyanate compound (a) is not particularly limited, but may be an organic polyisocyanate, or may be used as an isocyanate group-containing urethane prepolymer (A)-modifying organic monoisocyanate, which may be used as needed. The organic polyisocyanate may be an aromatic polyisocyanate in which an isocyanate group is bonded to an aromatic hydrocarbon, or an aliphatic polyisocyanate in which an isocyanate group is bonded to an aliphatic hydrocarbon.

[0036] Examples of aromatic polyisocyanates include diphenylmethane diisocyanates (MDIs) such as 4,4'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate; toluene diisocyanates (TDIs) such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate; phenylene diisocyanate, diphenyl diisocyanate, naphthalene diisocyanate, and diphenyl ether diisocyanate.

[0037] Examples of the aliphatic polyisocyanate include aromatic aliphatic polyisocyanates such as xylylene diisocyanate; aliphatic polyisocyanates such as propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, and pentamethylene diisocyanate; and alicyclic polyisocyanates such as cyclohexane diisocyanate, methylene bis(cyclohexyl isocyanate), and isophorone diisocyanate.

[0038] Further, carbodiimide modified products, biuret modified products, allophanate modified products, dimers, trimers, or polymethylene polyphenyl polyisocyanates (crude MDI or polymeric MDI) of these diisocyanates may also be mentioned. These may be used alone or in combination of two or more. Among these, in terms of further improving the transparency of the cured product of the one-component curable composition of the present invention, preventing the occurrence of defects such as cracks, discoloration, and chalking over a long period of time, further improving the weather resistance, and further imparting durability, alicyclic polyisocyanates and aromatic aliphatic polyisocyanates are preferred, alicyclic polyisocyanates are more preferred, and isophorone diisocyanate is particularly preferred.

[0039] The organic monoisocyanate for modifying the isocyanate group-containing urethane prepolymer (A) is not particularly limited, and examples thereof include aliphatic monoisocyanates such as n-butyl monoisocyanate, n-hexyl monoisocyanate, n-octadecyl monoisocyanate, etc. These may be used alone or in combination of two or more.

[0040] Active hydrogen-containing compound (b) Examples of the active hydrogen-containing compound (b) include an active hydrogen-containing (meth)acrylic polymer (b-1), a compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, a polyol (hereinafter sometimes referred to as a "polymeric polyol") having a number average molecular weight of 1000 or more (b-3), a low molecular weight polyol, an amino alcohol, and a polyamine. Among these, in the one-component curable composition of the present invention, it is preferable to use, as the active hydrogen-containing compound (b), a compound containing an active hydrogen-containing (meth)acrylic polymer (b-1), a compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, and a polyol (polymeric polyol) (b-3) having a number average molecular weight of 1000 or more.

[0041] As at least a part of the active hydrogen-containing compound (b) constituting the isocyanate group-containing urethane prepolymer (A), the active hydrogen-containing (meth)acrylic polymer (b-1), the compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, and the polyol (b-3) having a number average molecular weight of 1000 or more are used in combination, so that the weather resistance of the isocyanate group-containing urethane prepolymer (A) can be further improved. In addition, a one-component curable composition in which the isocyanate group-containing urethane prepolymer (A) is blended with a compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group as described below, as necessary, can be cured quickly without deteriorating workability or foaming, and can impart excellent rubber properties. Furthermore, the cured product of the one-component curable composition of the present invention has excellent transparency and weather resistance, and can suppress surrounding pollution for a long period of time without impairing the beauty of the building.

[0042] Active hydrogen-containing (meth)acrylic polymer (b-1) The active hydrogen-containing (meth)acrylic polymer (b-1) may be a poly(meth)acrylic polyol. The poly(meth)acrylic polyol is preferably obtained by subjecting an ethylenically unsaturated compound containing at least a hydroxyl group-containing (meth)acrylic monomer to a high-temperature continuous polymerization reaction at preferably 150 to 350°C, more preferably 210 to 250°C, by a known radical polymerization method such as batch or continuous polymerization in the presence or absence of a polymerization initiator and in the presence or absence of a solvent, since the molecular weight distribution of the reaction product is narrow and the viscosity is low.

[0043] The poly(meth)acrylic polyol may be one obtained by polymerizing one kind of hydroxyl group-containing (meth)acrylic monomer, one obtained by copolymerizing two or more kinds of hydroxyl group-containing (meth)acrylic monomer, or one obtained by copolymerizing one or more kinds of hydroxyl group-containing (meth)acrylic monomer and ethylenically unsaturated compound other than hydroxyl group-containing (meth)acrylic monomer. Among these, one obtained by copolymerizing one or more kinds of hydroxyl group-containing (meth)acrylic monomer and one or more kinds of ethylenically unsaturated compound other than hydroxyl group-containing (meth)acrylic monomer is preferred, because it is easy to adjust the hydroxyl group content of the poly(meth)acrylic polyol and it is easy to select the physical properties of the cured product. Among these, those obtained by copolymerizing a total of 50% by mass or more of one or more hydroxyl group-containing (meth)acrylic monomers having a carbon number of 9 or less, one or more hydroxyl group-containing (meth)acrylic monomers having a carbon number of 10 or more, and one or more ethylenically unsaturated compounds other than hydroxyl group-containing (meth)acrylic monomers with 50% by mass or less are more preferable, and those obtained by copolymerizing a total of 70% by mass or more of one or more hydroxyl group-containing (meth)acrylic monomers having a carbon number of 9 or less, one or more hydroxyl group-containing (meth)acrylic monomers having a carbon number of 10 or more, and one or more ethylenically unsaturated compounds other than hydroxyl group-containing (meth)acrylic monomers with 30% by mass or less are particularly preferable.

[0044] In the copolymerization, it is preferable to use one or more hydroxyl group-containing (meth)acrylic monomers so that the average number of hydroxyl groups per molecule of poly(meth)acrylic polyol is 1.0 to 10, and it is particularly preferable to use them so that the average number of hydroxyl groups per molecule of poly(meth)acrylic polyol is 1.0 to 10, and it is particularly preferable to use them so that the average number of hydroxyl groups per molecule of poly(meth)acrylic polyol is 1.2 to 3. If the average number of hydroxyl groups exceeds 10, the physical properties after curing become hard and sufficient rubber-like elasticity may not be obtained.

[0045] The number average molecular weight of the poly(meth)acrylic polyol in terms of polystyrene by gel permeation chromatography (GPC) is not particularly limited, but is preferably 1000 to 30000, and particularly preferably 1000 to 15000. The Tg of the poly(meth)acrylic polyol is not particularly limited, but is preferably 0°C or lower, more preferably -70 to -20°C, and particularly preferably -70 to -30°C. The viscosity of the poly(meth)acrylic polyol at 25°C is not particularly limited, but is preferably 100000 mPa·s or lower, and particularly preferably 50000 mPa·s or lower. If the number average molecular weight of the poly(meth)acrylic polyol is 30000, the Tg is 0°C, and the viscosity at 25°C exceeds 100000 mPa·s, respectively, the workability during construction may decrease.

[0046] The content of the active hydrogen-containing (meth)acrylic polymer in the active hydrogen-containing compound is not particularly limited, but from the viewpoint of further improving the weather resistance, transparency and rubber physical properties of the one-component curable composition containing the isocyanate group-containing urethane prepolymer (A), the content is preferably from 1.0 mass % to 7.0 mass %, particularly preferably from 2.0 mass % to 6.0 mass %.

[0047] Compound (b-2) Having at least one active hydrogen and at least one photocurable ethylenically unsaturated group The compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group is a compound having one or more active hydrogens that react with the isocyanate groups of the isocyanate group-containing urethane prepolymer (A) and having one or more photocurable ethylenically unsaturated groups.

[0048] Examples of the active hydrogen include hydroxyl, primary amino, secondary amino, carboxyl, and mercapto groups. Of these, hydroxyl is preferred because it reacts easily with the isocyanate group of the isocyanate group-containing urethane prepolymer and the viscosity increase is relatively small. Examples of the photocurable ethylenically unsaturated group include vinyl, vinylene, cinnamoyl, acryloyl, and methacryloyl groups. Of these, acryloyl and methacryloyl groups are preferred because they undergo polymerization reaction in a relatively short time when exposed to light to form a coating with excellent weather resistance.

[0049] Examples of compounds having one or more hydroxyl groups as active hydrogen groups and one or more acryloyl groups and / or methacryloyl groups as photocurable ethylenically unsaturated groups include the "Aronix" series manufactured by Toagosei Co., Ltd., the "KAYARAD" series manufactured by Nippon Kayaku Co., Ltd., and the "Epoxy Ester" series manufactured by Kyoeisha Chemical Co., Ltd.

[0050] The content of the compound having at least one active hydrogen and at least one photocurable ethylenically unsaturated group in the active hydrogen-containing compound is not particularly limited, but from the viewpoint of further improving the weather resistance, transparency and rubber physical properties of the one-component curable composition containing the isocyanate group-containing urethane prepolymer (A), the content is preferably from 1.0 mass % to 7.0 mass %, particularly preferably from 2.0 mass % to 6.0 mass %.

[0051] Polyol (b-3) having a number average molecular weight of 1000 or more Examples of polyols (polymer polyols) (b-3) having a number average molecular weight of 1000 or more include polyester polyols, polycarbonate polyols, polyoxyalkylene polyols, hydrocarbon polyols, animal and vegetable polyols, copolyols thereof, etc. The polyol (b-3) having a number average molecular weight of 1000 or more means a polymer polyol other than the active hydrogen-containing (meth)acrylic polymer (b-1) and the compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group.

[0052] In this specification, high molecular weight polyol and high molecular weight monool respectively refer to polyols and monools having a number average molecular weight of 1000 or more in terms of polystyrene measured by gel permeation chromatography (GPC), and low molecular weight polyols, low molecular weight monools, and low molecular weight amino alcohols respectively refer to polyols, monools, and amino alcohols having a number average molecular weight of less than 1000 in terms of polystyrene measured by gel permeation chromatography (GPC).

[0053] By having a number average molecular weight of 1000 or more, it is possible to obtain better rubber elasticity after curing. The lower limit of the number average molecular weight of the polymer polyol is preferably 1500, particularly preferably 2000, from the viewpoint of further improving the rubber elasticity and obtaining excellent adhesive performance. On the other hand, the upper limit is not particularly limited, but is preferably 100000, more preferably 30000, particularly preferably 20000, from the viewpoint of preventing an increase in the viscosity of the isocyanate group-containing urethane prepolymer (A) and obtaining excellent workability.

[0054] Examples of polyester polyols include polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, orthophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, hexahydroorthophthalic acid, naphthalenedicarboxylic acid, and trimellitic acid; alkyl ester compounds such as methyl esters and ethyl esters of these polycarboxylic acids; and acid anhydrides of these polycarboxylic acids, which are combined with one or more of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentanediol, 1,6-hexane ... Examples of the polyester polyols include polyester polyols and polyester amide polyols obtained by dehydration condensation reaction with one or more of low molecular weight polyamines (polyamines having a number average molecular weight of less than 1000 in terms of polystyrene by GPC) such as butylene diamine, hexamethylene diamine, xylylene diamine, and isophorone diamine. Examples of the polyester polyols include polyester amide polyols and polyester amide polyols obtained by dehydration condensation reaction with one or more of low molecular weight amino alcohols such as monoethanolamine and diethanolamine. Examples of the polyester polyols include lactone-based polyester polyols obtained by ring-opening polymerization of cyclic ester (lactone) monomers such as ε-caprolactone and γ-valerolactone using low molecular weight polyols and low molecular weight amino alcohols as initiators.

[0055] Examples of polycarbonate polyols include those obtained by the dehydrochlorination reaction of the low molecular weight polyol used in the synthesis of the above polyester polyol with phosgene, or the transesterification reaction of the above low molecular weight polyol with diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, or the like.

[0056] Examples of polyoxyalkylene polyols include low molecular weight polyols, low molecular weight amino alcohols, and polycarboxylic acids used in the synthesis of the above polyester polyols, as well as polyoxyethylene polyols, polyoxypropylene polyols, polyoxybutylene polyols, polyoxytetramethylene polyols, and poly-(oxyethylene)-(oxypropylene)-random or block copolymer polyols obtained by ring-opening addition polymerization or copolymerization (hereinafter, "polymerization or copolymerization" may be referred to as (co)polymerization) of one or more cyclic ether compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran using one or more saccharide-based low molecular weight (number average molecular weight in polystyrene equivalent by GPC less than 1000) polyhydric alcohols such as sorbitol, mannitol, sucrose, and glucose, and low molecular weight polyhydric phenols such as bisphenol A and bisphenol F as initiators. Examples of polyoxyalkylene polyols include polyester ether polyols and polycarbonate ether polyols using the above polyester polyols or polycarbonate polyols as initiators. Further examples include polyols obtained by reacting the above low molecular weight polyols with organic isocyanates with an excess of hydroxyl groups relative to the isocyanate groups.

[0057] The number of alcoholic hydroxyl groups in the polyoxyalkylene polyol is not particularly limited, but is preferably more than 2 on average per molecule, more preferably from 2 to 4 on average per molecule, and even more preferably from 2 to 3 on average per molecule. Among these, polyoxyalkylene diols, polyoxyalkylene triols, and mixtures of polyoxyalkylene diols and polyoxyalkylene triols are particularly preferred from the viewpoint of excellent adhesive performance and rubber elasticity after curing.

[0058] Examples of catalysts used in the preparation of polyoxyalkylene polyols include cesium alkoxides such as cesium hydride, cesium methoxide, and cesium ethoxide, cesium compounds such as cesium hydroxide, diethylzinc, iron chloride, metal porphyrins, phosphazenium compounds, and composite metal cyanide complexes such as glyme complexes and diglyme complexes of zinc hexacyanocobaltate.

[0059] If necessary, a polyoxyalkylene-based monool, such as a polyoxypropylene-based monool obtained by ring-opening addition (co)polymerization of a cyclic ether compound, such as the above-mentioned propylene oxide, may be used to modify the isocyanate group-containing urethane prepolymer (A).

[0060] The term "polyoxyalkylene-based polyol, polyoxyalkylene-based monool, etc.," means that 50% by mass or more of the portion excluding hydroxyl groups in 1 mole of the molecule is composed of polyoxyalkylene. Therefore, the remainder may be modified with other structures such as ester, urethane, polycarbonate, polyamide, poly(meth)acrylate, polyolefin, etc. The portion composed of polyoxyalkylene is not particularly limited as long as it is 50% by mass or more, but is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0061] Examples of hydrocarbon polyols include polyolefin polyols such as polybutadiene polyol and polyisoprene polyol; polyalkylene polyols such as hydrogenated polybutadiene polyol and hydrogenated polyisoprene polyol; and halogenated polyalkylene polyols such as chlorinated polypropylene polyol and chlorinated polyethylene polyol.

[0062] Examples of the animal and vegetable polyols include castor oil diols, etc. Examples of the chain extenders include the low molecular weight polyols and low molecular weight amino alcohols used in the synthesis of the polyester polyols described above, as well as the polyoxyalkylene polyols described above that have a number average molecular weight of less than 1000.

[0063] The various polymer polyols described above may be used alone or in combination of two or more kinds.

[0064] The total degree of unsaturation of the polymer polyol is not particularly limited, but is preferably 0.1 meq / g or less, more preferably 0.07 meq / g or less, and particularly preferably 0.04 meq / g or less. The molecular weight distribution of the polymer polyol [ratio of weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene by GPC=Mw / Mn] is not particularly limited, but is preferably 1.0 to 1.6, particularly preferably 1.0 to 1.3, from the viewpoint of reducing the viscosity of the isocyanate group-containing urethane prepolymer (A) and improving the rubber elasticity after curing.

[0065] Among the above-mentioned polymer polyols, polyoxyalkylene polyols are preferred from the viewpoint of rubber elasticity and adhesive performance, and among these, polyoxypropylene polyols are particularly preferred.

[0066] The content of the polymer polyol in the active hydrogen-containing compound is not particularly limited, but from the viewpoint of further improving the weather resistance, transparency and rubber physical properties of the one-component curable composition containing the isocyanate group-containing urethane prepolymer (A), the content is preferably from 30% by mass to 70% by mass, and particularly preferably from 40% by mass to 60% by mass.

[0067] In the isocyanate group-containing urethane prepolymer (A) blended in the one-component curable composition of the present invention, in addition to the above-mentioned components (b-1), (b-2), and (b-3), a polyol having a number average molecular weight of less than 1000 (low molecular weight polyol), an amino alcohol, a polyamine, or the like may also be used as the active hydrogen-containing compound (b), if necessary.

[0068] Examples of the low molecular weight polyol include the low molecular weight polyhydric alcohols having a number average molecular weight of less than 1,000 listed as the raw materials for producing the polyester polyol.

[0069] Examples of the amino alcohol include monoethanolamine, diethanolamine, N-methyldiethanolamine, N-methyldipropanolamine, and N-phenyldiethanolamine.

[0070] Examples of polyamines include high molecular weight polyamines such as polyoxyalkylene polyamines having a number average molecular weight of 1000 or more and an amino group at the end of a polyoxyalkylene polyol, such as polypropylene glycol with its terminal diamination. Examples of polyamines further include low molecular weight polyamines having a number average molecular weight of less than 500, such as ethylene diamine, hexamethylene diamine, isophorone diamine, diaminophenyl methane, and diethylene triamine.

[0071] The isocyanate group-containing urethane prepolymer (A) used in the present invention can be a known urethane catalyst, such as metal salts (metal organic acid salts) of metals such as zinc, tin, lead, zirconium, bismuth, cobalt, manganese, iron, etc., such as stannous octylate and stannous octylate, and organic acids such as octylic acid, octenic acid, naphthenic acid, etc., dibutyltin diacetylacetonate, zirconium tetraacetylacetonate, metal chelate compounds such as EXCESTARC-501 (manufactured by AGC Corporation), which is a tin-based chelate compound, dibutyltin dilaurate, dioctyltin dilaurate, and other organometallic compounds, triethylenediamine, triethylamine, tri-n-butylamine, and other organic amines and their salts. Among these urethane catalysts, metal organic acid salts and organometallic compounds are preferred. In addition, known organic catalysts can also be used.

[0072] The method for producing the isocyanate group-containing urethane prepolymer (A) is not particularly limited, and a batch reaction method, a multi-stage reaction method, etc. can be used, but for example, a method in which an active hydrogen-containing compound (b) and an organic isocyanate compound (a) are charged into a glass or stainless steel reaction vessel, a reaction catalyst or an organic solvent is added as necessary, and the mixture is reacted while stirring at 50 to 120 ° C. In this case, the isocyanate group may react with moisture, causing the resulting isocyanate group-containing urethane prepolymer (A) to thicken, so the reaction may be performed under conditions where moisture is blocked, such as nitrogen gas replacement or under a nitrogen gas stream, as necessary.

[0073] Thixotropic agent (B) The thixotropy-imparting agent (B) is used to impart thixotropy to the one-part curable composition of the present invention, thereby preventing sagging (slump) when the one-part curable composition is filled or applied to a vertical surface such as a vent cap or an exterior material of a building. The thixotropy-imparting agent (B) is an extremely important component when the one-part curable composition is used as a sealing material for a building.

[0074] Examples of the thixotropy-imparting agent (B) include inorganic thixotropy-imparting agents such as calcium carbonate surface-treated with an organic acid compound, hydrophilic fine powder silica, and surface-treated fine powder silica in which the surface of hydrophilic fine powder silica is treated with monomethyltrichlorosilane, dimethyldichlorosilane, a ureylene group-containing organic group, and a hydrolyzable silyl group-containing compound, etc.; and organic thixotropy-imparting agents such as organic bentonite and fatty acid amide. These may be used alone or in combination of two or more.

[0075] Examples of finely powdered silica include natural silica obtained by grinding quartz, silica sand, diatomaceous earth, etc. into a fine powder, and synthetic silica such as wet silica, e.g., precipitated silica, and dry silica, e.g., fumed silica.

[0076] In the one-component curable composition of the present invention, from the viewpoint of improving the haze value (ASTM D1003-97) of the cured product of the one-component curable composition being 40% or less, i.e., transparency, hydrophilic fine powder silica, surface-treated fine powder silica, and fatty acid amide are preferred, and from the viewpoint of maintaining stable thixotropy even in the presence of a curing catalyst for the one-component curable composition, surface-treated fine powder silica and fatty acid amide are particularly preferred.

[0077] The amount of the thixotropy-imparting agent (B) to be blended per 100 parts by mass (solid content) of the isocyanate group-containing urethane prepolymer (A) is not particularly limited, but the lower limit is preferably 0.5 parts by mass and more preferably 2.5 parts by mass from the viewpoint of reliably imparting thixotropy, while the upper limit is preferably 20.0 parts by mass and more preferably 12.0 parts by mass from the viewpoint of the workability of the one-component curable composition.

[0078] Compound (C) that is hydrolyzed by moisture to produce an active hydrogen-containing functional group In the one-component curable composition of the present invention, a compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group may be further blended as necessary. Examples of the compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group include ketimine compounds, enamine compounds, and aldimine compounds that are hydrolyzed by moisture to generate primary and / or secondary amines, compounds having an oxazolidine ring that are hydrolyzed by moisture to generate hydroxyl groups and amino groups, and silicate ester compounds that can be hydrolyzed by moisture to generate polyols. Among these, compounds having an oxazolidine ring are preferred because they provide excellent storage stability of the one-component curable composition, non-foaming properties due to reduced gas generation during curing, and excellent curability.

[0079] The compound having an oxazolidine ring is a compound having one or more, preferably 2 to 6, oxazolidine rings in the molecule, which are saturated 5-membered heterocyclic rings containing oxygen and nitrogen atoms. The compound having an oxazolidine ring reacts with moisture (humidity) in the atmosphere or the like and undergoes hydrolysis, whereby the oxazolidine ring generates (regenerates) a secondary amino group and an alcoholic hydroxyl group, thereby functioning as a latent curing agent for the isocyanate group-containing urethane prepolymer (A).

[0080] When the isocyanate group of the isocyanate group-containing urethane prepolymer (A) reacts with moisture (humidity) in the air, it forms a urea bond and hardens, but at the same time, carbon dioxide gas is also generated, and bubbles due to the carbon dioxide gas are generated in the hardened product, causing problems such as a deterioration in appearance, breakage of the hardened product, and a decrease in adhesion. However, when a mixture of the isocyanate group-containing urethane prepolymer (A) and a compound having an oxazolidine ring is exposed to moisture, the oxazolidine ring of the compound having an oxazolidine ring is hydrolyzed by moisture before the moisture reacts with the isocyanate group, generating active hydrogen (secondary amino group and alcoholic hydroxyl group in the case of a compound having an oxazolidine ring). When the generated active hydrogen reacts with the isocyanate group to harden, no carbon dioxide gas is generated, so that foaming due to carbon dioxide gas in the one-component curable composition of the present invention can be prevented.

[0081] Furthermore, in the case of an isocyanate group-containing urethane prepolymer (A) using isophorone diisocyanate as the organic isocyanate compound (a), the curing speed is extremely slow when it reacts only with water (humidity). However, by using a compound having an oxazolidine ring as the compound (C) which is hydrolyzed by moisture to generate an active hydrogen-containing functional group, the reaction between the secondary amino group generated by the reaction of the compound having an oxazolidine ring with water (humidity) and the isocyanate group derived from isophorone diisocyanate has a higher reaction rate than the reaction with water (humidity), and therefore the curing speed can be increased.

[0082] Examples of the compound having an oxazolidine ring include a urethane bond-containing oxazolidine compound which is a reaction product between a hydroxyl group of a compound having a hydroxyl group and an oxazolidine ring and an isocyanate group of an organic isocyanate compound, an ester bond-containing oxazolidine compound which is a reaction product between a hydroxyl group of a compound having a hydroxyl group and an oxazolidine ring and a carboxyl group of a carboxylic acid compound, an oxazolidine silyl ether, a carbonate group-containing oxazolidine, etc. Among these, a urethane bond-containing oxazolidine compound is preferred from the viewpoints of ease of production and low viscosity.

[0083] Examples of urethane bond-containing oxazolidine compounds include those obtained by blending a compound having a hydroxyl group and an oxazolidine ring with an organic isocyanate compound so that the molar ratio of isocyanate group / hydroxyl group is in the range of 0.9 to 1.2 / 1.0, preferably 0.95 to 1.05 / 1.0, and adding an organic solvent as necessary, and reacting at a temperature of 50 to 100°C.

[0084] Examples of the organic isocyanate compound used in the synthesis of the urethane bond-containing oxazolidine compound include aromatic polyisocyanates in which an isocyanate group is bonded to an aromatic hydrocarbon, araliphatic polyisocyanates having an aromatic ring and an isocyanate group is bonded to an aliphatic hydrocarbon group, and aliphatic polyisocyanates consisting only of an isocyanate group and an aliphatic hydrocarbon group.

[0085] Examples of aromatic polyisocyanates include diphenylmethane diisocyanates (MDIs) such as 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and mixtures thereof; toluene diisocyanates (TDIs) such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and mixtures thereof; and other aromatic polyisocyanates such as phenylene diisocyanate, diphenyl diisocyanate, naphthalene diisocyanate, and diphenyl ether diisocyanate.

[0086] An example of the aralkyl polyisocyanate is xylylene diisocyanate.

[0087] Examples of the aliphatic polyisocyanate include aliphatic polyisocyanates such as hexamethylene diisocyanate, pentamethylene diisocyanate, propylene diisocyanate, and butylene diisocyanate; and alicyclic polyisocyanates such as cyclohexane diisocyanate, methylene bis(cyclohexyl isocyanate), and isophorone diisocyanate.

[0088] Other examples include carbodiimide-modified, biuret-modified, allophanate-modified, dimers, trimers, and polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI), etc. These may be used alone or in combination of two or more.

[0089] Among these, aliphatic polyisocyanates are preferred, and hexamethylene diisocyanate is particularly preferred, since they can reduce the crystallinity of the urethane bond-containing oxazolidine compound and improve the workability of the resulting one-liquid curable composition.

[0090] An example of a compound having a hydroxyl group and an oxazolidine ring is an N-hydroxyalkyloxazolidine obtained by a dehydration condensation reaction between a secondary amino group of an alkanolamine and a carbonyl group of a ketone compound or an aldehyde compound.

[0091] Examples of alkanolamines include diethanolamine, dipropanolamine, N-(2-hydroxyethyl)-N-(2-hydroxypropyl)amine, etc. Examples of ketone compounds include acetone, diethyl ketone, isopropyl ketone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl butyl ketone, isobutyl ketone, methyl-t-butyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, etc. Examples of the aldehyde compound include aliphatic aldehyde compounds such as acetaldehyde, propionaldehyde, n-butylaldehyde, isobutyraldehyde, valeraldehyde, isovaleraldehyde, 2-methylbutyraldehyde, n-hexylaldehyde, 2-methylpentylaldehyde, n-octylaldehyde, and 3,5,5-trimethylhexylaldehyde; and aromatic aldehyde compounds such as benzaldehyde, methylbenzaldehyde, trimethylbenzaldehyde, ethylbenzaldehyde, isopropylbenzaldehyde, isobutylbenzaldehyde, methoxybenzaldehyde, dimethoxybenzaldehyde, and trimethoxybenzaldehyde.

[0092] Among these, diethanolamine is preferred as the alkanolamine, in terms of ease of production of a compound having a hydroxyl group and an oxazolidine ring, and excellent foaming prevention properties when the resulting one-component curable composition is cured. Among the ketone compounds and the aldehyde compounds, the aldehyde compounds are preferred, and among the aldehyde compounds, isobutyraldehyde, 2-methylpentylaldehyde, and benzaldehyde are preferred.

[0093] Specific examples of the compound having a hydroxyl group and an oxazolidine ring include 2-isopropyl-3-(2-hydroxyethyl)oxazolidine, 2-(1-methylbutyl)-3-(2-hydroxyethyl)oxazolidine, and 2-phenyl-3-(2-hydroxyethyl)oxazolidine.

[0094] Examples of a method for synthesizing a compound having a hydroxyl group and an oxazolidine ring include a method in which 1.0 mol or more, preferably 1.0 to 1.5 mol, and particularly preferably 1.0 to 1.2 mol of a carbonyl group of a ketone compound or an aldehyde compound is used per 1.0 mol of a secondary amino group of an alkanolamine, and the mixture is heated under reflux in a solvent such as toluene or xylene to carry out a dehydration condensation reaction while removing water produced as a by-product.

[0095] The ester bond-containing oxazolidine compound can be obtained, for example, by reacting the above-mentioned compound having a hydroxyl group and an oxazolidine ring with a lower alkyl ester of a dicarboxylic acid compound or a polycarboxylic acid compound.

[0096] The oxazolidine silyl ether can be obtained, for example, by a dealcoholization reaction between the above-mentioned compound having a hydroxyl group and an oxazolidine ring and an alkoxysilane such as trimethoxysilane, tetramethoxysilane, triethoxysilane, dimethoxydimethylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, or 3-glycidoxypropyltriethoxysilane.

[0097] The carbonate group-containing oxazolidine can be obtained by reacting the above-mentioned compound having a hydroxyl group and an oxazolidine ring with a carbonate such as diallyl carbonate using a polyhydric alcohol such as diethylene glycol or glycerin.

[0098] The total amount of active hydrogen (secondary amino group and alcoholic hydroxyl group in the case of a compound having an oxazolidine ring) generated by hydrolysis of the compound (C) which is hydrolyzed by moisture to generate an active hydrogen-containing functional group per 1.0 mole of isocyanate group in the isocyanate group-containing urethane prepolymer (A) is not particularly limited, but the lower limit is preferably 0.1 mole, more preferably 0.2 mole, and particularly preferably 0.3 mole from the viewpoint of more reliably preventing the generation of carbon dioxide gas, while the upper limit is preferably 1.5 mole, and particularly preferably 1.0 mole from the viewpoint of the physical properties of the cured product.

[0099] If necessary, a hydrolysis catalyst for the compound (C) (e.g., a compound having an oxazolidine ring) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group may be added. Examples of the hydrolysis catalyst include a hydrolysis catalyst for an oxazolidine ring. The hydrolysis catalyst for an oxazolidine ring promotes the reaction of a compound having an oxazolidine ring with moisture to hydrolyze and generate (regenerate) active hydrogen, or promotes the reaction between the generated (regenerated) active hydrogen and the isocyanate group of the isocyanate group-containing urethane prepolymer (A), thereby improving the curing speed of the one-component curable composition of the present invention. Examples of the hydrolysis catalyst for an oxazolidine ring include organometallic catalysts, organic carboxylic acid catalysts, acid anhydrides thereof, p-toluenesulfonyl isocyanate, a reaction product of p-toluenesulfonyl isocyanate with moisture, and organic phosphate ester compounds. These may be used alone or in combination of two or more.

[0100] The amount of the oxazolidine ring hydrolysis catalyst is not particularly limited, but is preferably 0.001 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass, relative to 100 parts by mass (solid content) of the isocyanate group-containing urethane prepolymer (A). If it is less than 0.001 part by mass, the effect of promoting the hydrolysis of the compound having an oxazolidine ring is insufficient, and if it exceeds 10 parts by mass, the storage stability of the one-component curable composition may be affected.

[0101] The one-component curable composition of the present invention may further contain additives such as a filler, an adhesion improver, a storage stability improver (dehydrating agent), and a colorant, if necessary.

[0102] Examples of the filler include inorganic powder fillers such as mica, kaolin, zeolite, graphite, white clay, clay, talc, slate powder, silicic anhydride, aluminum powder, zinc powder, magnesium carbonate, alumina, and magnesium oxide; fibrous fillers such as glass fiber and carbon fiber; inorganic fillers such as inorganic balloon-shaped fillers such as glass balloons, shirasu balloons, and ceramic balloons; fillers in which the surface of the inorganic fillers is treated with an organic substance such as fatty acid; organic powder fillers such as wood flour, walnut flour, rice husk flour, pulp powder, cotton chips, rubber powder, fine powder of thermoplastic or thermosetting resin, and polyethylene powder; organic fillers such as polyethylene hollow bodies and organic balloon-shaped fillers such as saran microballoons, and flame retardant fillers such as magnesium hydroxide and aluminum hydroxide. These may be used alone or in combination of two or more. The particle size of the filler is not particularly limited, but is preferably 0.01 to 1000 μm from the viewpoint of coatability.

[0103] An example of the adhesiveness improver is a coupling agent. Examples of the coupling agent include silane-based, aluminum-based, zircoaluminate-based coupling agents or partial hydrolysis condensates thereof. Among these, silane-based coupling agents or partial hydrolysis condensates thereof are preferred from the viewpoint of adhesive performance.

[0104] Specific examples of the silane coupling agent include vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, vinylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane, which have an alkoxysilyl group and a molecular weight of 500 or less, preferably 400 or less, and compounds having a molecular weight of 200 to 3000 that are partial hydrolysis condensates of one or more of the above silane coupling agents. These may be used alone or in combination of two or more.

[0105] Examples of the storage stability improver include vinyltrimethoxysilane, calcium oxide, and p-toluenesulfonyl isocyanate, which react with moisture present in the one-component curable composition. These may be used alone or in combination of two or more. As described above, p-toluenesulfonyl isocyanate is particularly preferred because it also acts as a curing accelerator when using the compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group.

[0106] Examples of colorants include inorganic pigments such as titanium oxide, iron oxide, and carbon black, and organic pigments such as copper phthalocyanine, etc. These may be used alone or in combination of two or more.

[0107] The amounts of the various additives added are selected so that the haze value of the cured product of the one-part curable composition is 40% or less.

[0108] The total amount of the adhesion improver and the storage stability improver is preferably 0 to 500 parts by mass, particularly preferably 5 to 300 parts by mass, per 100 parts by mass of the isocyanate group-containing urethane prepolymer (A).

[0109] In the one-component curable composition of the present invention, the above-mentioned additives can be used alone or in combination of two or more kinds. EXAMPLES

[0110] Next, examples of the present invention will be described, but the present invention is not limited to these examples as long as they do not depart from the spirit of the present invention.

[0111] Synthesis of urethane bond-containing oxazolidine compound O-1 (compound (C) which hydrolyzes with moisture to produce active hydrogen-containing functional groups) Synthesis Example 1 In a reaction vessel equipped with a stirrer, a thermometer, a nitrogen seal tube, an ester tube, and a heating / cooling device, 420 g of diethanolamine (molecular weight 105), 177 g of toluene, and 317 g of isobutyraldehyde (molecular weight 72.1) were charged while flowing nitrogen gas, and the mixture was heated with stirring to carry out a reflux dehydration reaction at 110-150°C while removing the by-product water (71.9 g) from the system. After water was no longer distilled out, the mixture was further heated under reduced pressure (50-70 hPa) to remove the toluene and unreacted isobutyraldehyde, and the intermediate reaction product N-hydroxyethyl-2-isopropyloxazolidine was obtained. Next, 336 g of hexamethylene diisocyanate (molecular weight 168) was further added to 636 g of the obtained N-hydroxyethyl-2-isopropyloxazolidine, and the mixture was heated at 80° C. for 8 hours. The reaction was terminated when the NCO content measured by titration reached 0.0 mass%, and a urethane bond-containing oxazolidine compound O-1 (molecular weight 487) having two oxazolidine rings in the molecule was obtained. The obtained urethane bond-containing oxazolidine compound O-1 was liquid at room temperature.

[0112] Preparation of one-component curable composition A-1 used in Example 1 While flowing nitrogen gas into a kneading / reaction vessel equipped with a stirring rod, a thermometer, a nitrogen seal tube, and a heating / cooling device, 55 g of a naphthenic solvent (Suwaclean 150, manufactured by Maruzen Petrochemical Co., Ltd.), 330 g of polyoxypropylene diol (product name: Exenol 3021, manufactured by AGC Corporation, number average molecular weight 3300), 140 g of an active hydrogen-containing (meth)acrylic polymer (product name: ARUFON UH2041, manufactured by Toa Gosei Co., Ltd., weight average molecular weight 2500), and 25 g of a compound having at least one active hydrogen and at least one photocurable ethylenically unsaturated group (KAYARADR-167, manufactured by Nippon Kayaku Co., Ltd., average molecular weight 374) were charged and mixed with stirring. Next, 176.5 g of isophorone diisocyanate and 0.1 g of inorganic bismuth (manufactured by Nitto Kasei Kogyo Co., Ltd., Neostan U-600) as a reaction catalyst were added while stirring, and then the mixture was heated and reacted at 70 to 75 ° C. for 1 hour. After that, the mixture was cooled to room temperature, and 15 g of a hindered phenol-based antioxidant (manufactured by BASF Japan Ltd., IRGANOX245), 15 g of a hindered amine-based light stabilizer (manufactured by ADEKA Corporation, Adekastab LA-63P), 15 g of polyvinyl methyl ether (manufactured by Senka Corporation, polyvinyl methyl ether-65D), 66 g of hydrophobized fine powder silica (manufactured by Tokuyama Corporation, Reolosil MT-10), and 115 g of a urethane bond-containing oxazolidine compound O-1 were added, and the mixture was kneaded for another 30 minutes until it became uniform, and further degassed under reduced pressure, packed into a container, and sealed to prepare a one-component curable composition A-1. The viscosity of the obtained one-component curable composition A-1 immediately after preparation was 90 to 140 Pa s at 25°C and 20 revolutions per minute using a B-type rotational viscometer with a No. 6 rotor. The obtained one-component curable composition A-1 had a colorless, transparent paste-like appearance.

[0113] Preparation of one-component curable composition A-2 used in Example 2 In Example 1, 45 g of a hydrocarbon solvent (Exsol D40, manufactured by EMG Marketing LLC) was used instead of the naphthenic solvent, 250 g of polyoxypropylene diol, 250 g of polyoxypropylene triol (manufactured by AGC Inc., product name: Exenol 4030, number average molecular weight 4000), 160 g of an active hydrogen-containing (meth)acrylic polymer (manufactured by Toa Gosei Co., Ltd., product name: ARUFON UH2000, weight average molecular weight 4900), 13 g of a compound having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, 95.3 g of isophorone diisocyanate, and 66 g of a urethane bond-containing oxazolidine compound O-1 were used. A one-component curable composition A-2 was prepared in the same manner. The viscosity of the obtained one-component curable composition A-2 immediately after preparation was 120 to 160 Pa s at 25°C and 20 revolutions per minute using a B-type rotational viscometer with a No. 6 rotor. The obtained one-component curable composition A-2 had a colorless, transparent paste-like appearance.

[0114] As the one-component curable composition of Comparative Example 1, a commercially available sealant-1 (manufactured by Konishi Co., Ltd., modified silicone caulk clear, one-component modified silicone system) was used, and as the one-component curable composition of Comparative Example 2, a commercially available sealant-2 (manufactured by Cemedine Co., Ltd., Cemedine 8000 Clear, one-component silicone system) was used.

[0115] test Preparation of measurement sheet A square frame was created on a release paper using a 3 mm thick square backer, and the one-part curable compositions prepared in Examples 1 and 2 and the commercially available products used in Comparative Examples 1 and 2 were poured into the frame. Next, the excess one-part curable composition was removed with a spatula, the surface was smoothed, and a sheet was obtained that was cured for 7 days in an atmosphere of 23°C and 50% RH.

[0116] Evaluation items (1) Haze measurement The haze of the measurement sheet was measured according to Procedure B of ASTM D1003-97. (2) Measurement of tensile properties Based on JIS K6251:2010, a dumbbell-shaped No. 4 test piece was prepared from the measurement sheet. Using the obtained test piece, a tensile test (tensile speed 500 mm / min) was carried out in an atmosphere of 23°C using a tensile tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name STROGRAPH VG10-E) to measure the tensile elongation at break Eb (%) and the tensile strength Tb (N / mm 2 ) was measured. (3) Measurement of contamination As shown in Fig. 2, the one-component curable compositions prepared in Examples 1 and 2 and the commercially available products used in Comparative Examples 1 and 2 were cast on the painted surface of siding (manufactured by KMIU Co., Ltd., painted surface: white color) with a width of 10 mm and a height of 10 mm using a 10 mm square backer in the shape shown in Fig. 1. After casting, the siding was left indoors at 23 ° C. and 50% relative humidity for 7 days, and then the backer was removed and the siding was installed near a busy intersection outdoors with the surface of the siding board facing the road and its length direction vertical, and exposed for 3 months. The surfaces of the siding boards under the one-component curable composition and the commercially available product were visually observed, and the staining was evaluated according to the following criteria. ○: No obvious contamination was observed on the surface, or very little. ×: Many obvious stains were observed on the surface. (4) Weather resistance measurement Test pieces were taken from the measurement sheet and tested using a Sunshine Weather Meter (S80 model, manufactured by Suga Test Instruments Co., Ltd.) according to the WS-A method of "6.2 Exposure test method using an open frame carbon arc lamp" in JISA 1415:2013 "Laboratory light source exposure test method for polymeric building materials." The test pieces were removed every 1000 hours of exposure up to 5000 hours, and the surface was visually observed, and the weather resistance was evaluated according to the following criteria. ○: No obvious cracks, discoloration, chalking or other abnormalities are observed on the surface, or there are very few. ×: Many obvious abnormalities such as cracks, discoloration, chalking, etc. were observed on the surface.

[0117] The evaluation results are shown in Table 1 below and FIG.

[0118] [Table 1]

[0119] From the above Table 1, in Examples 1 and 2, which are one-part curable compositions containing an isocyanate group-containing urethane prepolymer, which is a reaction product of isophorone diisocyanate and an active hydrogen-containing compound, a thixotropic agent, and a urethane bond-containing oxazolidine compound O-1, and in which the active hydrogen-containing compound contains an active hydrogen-containing (meth)acrylic polymer, a compound having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, and a polyol having a number average molecular weight of 1000 or more, the haze was reduced and excellent transparency was obtained. Furthermore, from the above Table 1 and FIG. 3, in Examples 1 and 2, both weather resistance and stain resistance were excellent. Furthermore, in Examples 1 and 2, the tensile strength (Tb) was improved without impairing the tensile elongation at break (Eb), and excellent durability was obtained.

[0120] On the other hand, in Comparative Example 1, which is a one-component modified silicone-based one-liquid curing composition, and Comparative Example 2, which is a one-component silicone-based one-liquid curing composition, both of which are commercially available sealants, even though they were advertised as being transparent, the haze increased and transparency was not obtained. In addition, while a sealant that is a silicone-based one-liquid curing composition is generally more weather resistant than a sealant that is a urethane-based one-liquid curing composition, Comparative Examples 1 and 2, which are silicone-based one-liquid curing compositions, were unable to obtain weather resistance and also could not obtain tensile strength (Tb) as shown in Table 1 and FIG. 3 above, with abnormalities such as discoloration, cracking, and chalking. In addition, Comparative Example 2 was unable to obtain contamination resistance. [Industrial Applicability]

[0121] The one-component curable composition of the present invention has high transparency and weather resistance, and can give a cured product that does not impair the aesthetic appearance of a building or contaminate the surroundings for a long period of time. Therefore, the one-component curable composition can be used as a sealing material for buildings, for example, a sealing material for vent caps. [Explanation of symbols]

[0122] 1. Siding 2 One-component curable composition

Claims

1. A one-component curable composition for a sealant for buildings, comprising: an isocyanate group-containing urethane prepolymer (A); a thixotropy-imparting agent (B); and a compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group; the isocyanate group-containing urethane prepolymer (A) is a reaction product of an organic isocyanate compound (a) and an active hydrogen-containing compound (b); the active hydrogen-containing compound (b) comprises an active hydrogen-containing (meth)acrylic polymer (b-1), a compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, and a polyol (b-3) having a number average molecular weight of 1000 or more; The one-component curable composition for use as a sealant for buildings has a haze value of 40% or less when the composition is cured according to ASTM D1003-97.

2. The one-component curable composition according to claim 1, wherein the active hydrogen-containing compound (b) contains the active hydrogen-containing (meth)acrylic polymer (b-1) in an amount of 1.0 mass % or more and 7.0 mass % or less.

3. The one-component curable composition according to claim 1 or 2, wherein the active hydrogen-containing compound (b) contains the compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group in an amount of 1.0 mass % or more and 7.0 mass % or less.

4. The one-component curable composition according to claim 1 , wherein the organic isocyanate compound (a) comprises an alicyclic polyisocyanate compound.

5. The one-component curable composition according to claim 1 , wherein the thixotropy-imparting agent (B) comprises finely divided silica.

6. The one-component curable composition according to any one of claims 1 to 5, wherein the compound (C) which is hydrolyzed by moisture to generate an active hydrogen-containing functional group is an oxazolidine compound.

7. The one-component curable composition according to claim 1 , wherein the isocyanate group-containing urethane prepolymer (A) has an isocyanate group content of 0.10 mass % or more and 15 mass % or less.

8. 8. The one-component curable composition according to claim 1, wherein the isocyanate group-containing urethane prepolymer (A) is a reaction product in which 1.5 mol or more and 8.0 mol or less of the isocyanate group of the organic isocyanate compound (a) is contained relative to 1.0 mol of active hydrogen of the active hydrogen-containing compound (b).

9. The one-component curable composition according to claim 1 , comprising 0.50 parts by mass or more and 20 parts by mass or less of the thixotropy-imparting agent (B) relative to the isocyanate group-containing urethane prepolymer (A) (solid content).

10. 10. The one-component curable composition according to claim 1 , wherein the compound (C) which is hydrolyzed by moisture to generate an active hydrogen-containing functional group has an active hydrogen of 0.10 mol or more and 1.5 mol or less relative to 1.0 mol of isocyanate groups in the isocyanate group-containing urethane prepolymer (A).

11. The one-component curable composition according to any one of claims 1 to 10, wherein the polyol (b-3) having a number average molecular weight of 1,000 or more includes a polyoxypropylene-based polyol.

12. A cured product of the one-component curable composition according to any one of claims 1 to 11.

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