JP7617587B2 - One-part curable composition and cured product of the one-part curable composition - Google Patents

Description

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.

Normally, 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 ventilation devices are often installed inside buildings. The ventilation device has a duct that communicates with the outdoors, and the end of the duct is connected to a ventilation port that opens into the exterior wall. A vent cap is attached to the ventilation port to prevent rainwater and other liquids from entering inside the port. Here, if there is even a small gap between the vent cap and the exterior wall, rainwater and other liquids will enter through this gap. Therefore, in order to prevent rainwater and other liquids from entering through the gap between the vent cap and the exterior wall, the gap is filled with a sealant, and this sealant forms a waterproof seal.

In addition, with the trend towards more sophisticated design in 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 a color that is 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 will stand out, which can detract from the aesthetics of the entire building.

On the other hand, while there are cases where sealants for use in the joints of exterior walls are available in a wide variety of colors, the contractor for installing the vent caps is generally different from the contractor who fills the joints in the exterior walls with the sealant. In reality, it is not realistic for a vent cap contractor to prepare a different sealant for use only in the waterproof seal of the vent cap for each building with a different pattern or color.

To solve the above problems, transparent sealants are commercially available for use in the gap between the vent cap and the exterior wall, but they have low transparency and may still mar the aesthetics of the building. Furthermore, because of the lack of transparency, these transparent sealants cannot use pigments such as titanium oxide, which has high hiding power, and therefore have insufficient weather resistance, which is problematic given the current trend toward making buildings more durable overall.

Most of these types of sealants are silicone-based or modified silicone-based (Patent Document 1), and after application, they have problems such as water-repellent contamination due to silicone precursor molecules and contamination of the surrounding area due to the plasticizers they contain.

JP 2001-055799 A

The present invention was made to solve these problems, and aims 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.

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 an ASTM
The one-component curable composition has a haze value of 40% or less as measured by D1003-97.

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

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) includes 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.

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% by mass or more and 7.0% by mass or less.

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

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

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

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

An embodiment of the present invention is a one-component curable composition in which the isocyanate group-containing urethane prepolymer (A) has 0.10% by mass or more and 15% by mass or less of isocyanate groups.

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

An embodiment of the present invention is a one-component curable composition that contains 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).

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

An aspect of the present invention is a cured product of the one-part curable composition.

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 according to ASTM D1003-97, and therefore a one-component curable composition can be obtained that has high transparency and weather resistance, does not impair the aesthetic appearance of the building exterior, and does not contaminate the surroundings for a long period of time.

According to an aspect of the present invention, the active hydrogen-containing compound (b) of 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), 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. This makes it possible to obtain a one-component curable composition that can further improve transparency and weather resistance, and that can be cured without impairing the beauty of the building exterior and more reliably does not contaminate the surroundings for a long period of time.

According to an embodiment of the present invention, by containing 1.0% by mass or more and 7.0% by mass or less of the active hydrogen-containing (meth)acrylic polymer (b-1) in the active hydrogen-containing compound (b), it is possible to obtain a cured product with further improved weather resistance and rubber physical properties.

According to an embodiment of the present invention, the active hydrogen-containing compound (b) contains 1.0% by mass or more and 7.0% by mass or less of a compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group, thereby making it possible to obtain a cured product with further improved weather resistance and rubber physical properties.

According to an embodiment of the present invention, the organic isocyanate compound (a) contains an alicyclic polyisocyanate compound, which further improves transparency and weather resistance, and allows a durable cured product to be obtained.

According to an embodiment of the present invention, the thixotropy-imparting agent (B) contains finely divided silica, which can more reliably improve transparency.

FIG. 2 is a plan view illustrating a test method for staining in the examples and comparative examples. FIG. 2 is a side view illustrating a test method for staining in the examples and comparative examples. 1 is a photograph showing the results of weather resistance tests in Examples and Comparative Examples.

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 that contains 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.

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

Next, the components of the one-part curable composition of the present invention will be described below.

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.

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% by mass, more preferably 0.20% by mass, and particularly preferably 0.40% by 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% by mass, more preferably 12.0% by mass, and particularly preferably 10.0% by mass, from the viewpoints of foaming during curing of the resulting one-component curable composition and physical properties of the cured product.

The number of moles of isocyanate groups of the organic isocyanate compound per 1.0 mole of active hydrogen of the active hydrogen-containing compound is not particularly limited as long as the number of moles 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 resulting one-part curable composition. On the other hand, 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 resulting one-part curable composition and physical properties of the cured product.

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.

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, diphenyl ether diisocyanate, etc.

Examples of aliphatic polyisocyanates 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.

Also included are carbodiimide modified products, biuret modified products, allophanate modified products, dimers, trimers, and polymethylene polyphenyl polyisocyanates (crude MDI or polymeric MDI) of these diisocyanates. These may be used alone or in combination of two or more. Among these, alicyclic polyisocyanates and aromatic aliphatic polyisocyanates are preferred, alicyclic polyisocyanates are more preferred, and isophorone diisocyanate is particularly preferred, in order to further improve the transparency of the cured product of the one-component curable composition of the present invention, prevent defects such as cracking, discoloration, and chalking over a long period of time, further improve weather resistance, and further impart durability.

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

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 having at least one active hydrogen and at least one photocurable ethylenically unsaturated group (b-2), a polyol having a number average molecular weight of 1000 or more (hereinafter, sometimes referred to as a "polymeric polyol") (b-3), a low molecular weight polyol, an amino alcohol, a polyamine, etc. 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 having at least one active hydrogen and at least one photocurable ethylenically unsaturated group (b-2), and a polyol having a number average molecular weight of 1000 or more (polymeric polyol) (b-3).

By using a combination of 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 as at least a part of the active hydrogen-containing compound (b) constituting the isocyanate group-containing urethane prepolymer (A), 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.

Active hydrogen-containing (meth)acrylic polymer (b-1)
Examples of the active hydrogen-containing (meth)acrylic polymer (b-1) include poly(meth)acrylic polyols. The poly(meth)acrylic polyols are those obtained by subjecting an ethylenically unsaturated compound containing at least a hydroxyl group-containing (meth)acrylic monomer to a high-temperature continuous polymerization reaction, preferably at 150 to 350°C, more preferably at 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, and are suitable in that the molecular weight distribution of the reaction product is narrow and the viscosity is low.

The poly(meth)acrylic polyol may be obtained by polymerizing one type of hydroxyl group-containing (meth)acrylic monomer, may be obtained by copolymerizing two or more types of hydroxyl group-containing (meth)acrylic monomer, or may be obtained by copolymerizing one or more types of hydroxyl group-containing (meth)acrylic monomer and an ethylenically unsaturated compound other than a hydroxyl group-containing (meth)acrylic monomer. Among these, poly(meth)acrylic polyols obtained by copolymerizing one or more types of hydroxyl group-containing (meth)acrylic monomer and one or more types of ethylenically unsaturated compound other than a hydroxyl group-containing (meth)acrylic monomer are preferred, since 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 9 or less carbon atoms and one or more hydroxyl group-containing (meth)acrylic monomers having 10 or more carbon atoms 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 9 or less carbon atoms and one or more ethylenically unsaturated compounds other than hydroxyl group-containing (meth)acrylic monomers with 30% by mass or less are particularly preferable.

During the copolymerization, it is preferable to use one or more hydroxyl-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 1.2 to 3. If the average number of hydroxyl groups exceeds 10, the physical properties after curing may become hard and sufficient rubber-like elasticity may not be obtained.

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 exceeds 0°C, and the viscosity at 25°C exceeds 100000 mPa·s, respectively, the workability during construction may decrease.

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), it is preferably 1.0% by mass or more and 7.0% by mass or less, and particularly preferably 2.0% by mass or more and 6.0% by mass or less.

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.

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

Examples of compounds that have one or more hydroxyl groups as active hydrogen groups and one or more acryloyl 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.

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), it is preferably 1.0% by mass or more and 7.0% by mass or less, and particularly preferably 2.0% by mass or more and 6.0% by mass or less.

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.

In addition, 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).

By having the number average molecular weight of the polymer polyol be 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, and 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 for example, from the viewpoint of preventing an increase in the viscosity of the isocyanate group-containing urethane prepolymer (A) and obtaining excellent workability, it is preferably 100,000, more preferably 30,000, and particularly preferably 20,000.

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, 1,7-hexanediol, 1,8-hexanediol, 1,9-hexanediol, 2,2-hexanediol, 2,3-hexanediol, 2,4-hexanediol, 2,5-hexanediol, 2,6-hexanediol, 2,7-hexanediol, 2,8-hexanediol, 2,9-hexanediol, 2,10 ... 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 with a number average molecular weight of less than 1000 in terms of polystyrene by GPC) such as butylenediamine, hexamethylenediamine, xylylenediamine, and isophoronediamine; and 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.

Examples of polycarbonate polyols include those obtained by the dehydrochlorination reaction between the low molecular weight polyol used in the synthesis of the above polyester polyol and phosgene, or by the transesterification reaction between the above low molecular weight polyol and diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, etc.

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 low molecular weight polyhydric phenols (number average molecular weight in polystyrene equivalent by GPC less than 1000) such as saccharide-based low molecular weight polyhydric alcohols such as sorbitol, mannitol, sucrose, and glucose, and low molecular weight polyhydric phenols (number average molecular weight in polystyrene equivalent by GPC less than 1000) such as bisphenol A and bisphenol F as an initiator. 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.

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. Of these, polyoxyalkylene diols, polyoxyalkylene triols, and mixtures of polyoxyalkylene diols and polyoxyalkylene triols are particularly preferred from the standpoint of excellent adhesive performance and rubber elasticity after curing.

Catalysts used in the preparation of polyoxyalkylene polyols include, for example, 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.

If necessary, polyoxyalkylene monools such as polyoxypropylene monools obtained by ring-opening addition (co)polymerization of cyclic ether compounds such as propylene oxide may be used as initiators for modifying the isocyanate group-containing urethane prepolymer (A).

The term "polyoxyalkylene-based polyol, polyoxyalkylene-based monool, etc.," means that 50% or more by mass of the portion excluding hydroxyl groups in one 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 80% by mass or more is preferable, 90% by mass or more is more preferable, and 95% by mass or more is particularly preferable.

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

Examples of animal and vegetable polyols include castor oil diols. Examples of 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.

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

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, and particularly preferably 1.0 to 1.3, in order to reduce the viscosity of the isocyanate group-containing urethane prepolymer (A) and to further improve the rubber elasticity after curing.

Among the polymer polyols listed above, polyoxyalkylene polyols are preferred from the standpoint of rubber elasticity and adhesive performance, and among these, polyoxypropylene polyols are particularly preferred.

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), it is preferably 30% by mass or more and 70% by mass or less, and particularly preferably 40% by mass or more and 60% by mass or less.

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), polyols having a number average molecular weight of less than 1000 (low molecular weight polyols), amino alcohols, polyamines, etc. may also be used as the active hydrogen-containing compound (b) as necessary.

Examples of low molecular weight polyols include low molecular weight polyhydric alcohols with a number average molecular weight of less than 1000, which are listed as raw materials for producing the polyester polyols.

Examples of amino alcohols include monoethanolamine, diethanolamine, N-methyldiethanolamine, N-methyldipropanolamine, and N-phenyldiethanolamine.

Examples of polyamines include high molecular weight polyamines such as polyoxyalkylene polyamines having a number average molecular weight of 1000 or more, such as polypropylene glycol with terminal diamination, in which the terminal of a polyoxyalkylene polyol is an amino group. Further examples of polyamines 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.

For the isocyanate group-containing urethane prepolymer (A) used in the present invention, known urethane catalysts can be used, 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., metal chelate compounds such as dibutyltin diacetylacetonate, zirconium tetraacetylacetonate, and EXCESTARC-501 (manufactured by AGC Inc.), which is a tin-based chelate compound, organometallic compounds such as dibutyltin dilaurate and dioctyltin dilaurate, and organic amines such as triethylenediamine, triethylamine, and tri-n-butylamine, and salts thereof. Of these urethane catalysts, metal organic acid salts and organometallic compounds are preferred. Furthermore, known organic catalysts can also be used.

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. For example, an active hydrogen-containing compound (b) and an organic isocyanate compound (a) are charged into a glass or stainless steel reaction vessel, and a reaction catalyst or organic solvent is added as necessary, and the mixture is reacted while stirring at 50 to 120°C. At this time, the isocyanate group may react with moisture, causing the resulting isocyanate group-containing urethane prepolymer (A) to thicken. Therefore, if necessary, the reaction may be performed under conditions that block moisture, such as nitrogen gas replacement or under a nitrogen gas stream.

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.

Examples of thixotropy-imparting agents (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 amides. These may be used alone or in a mixture of two or more.

Examples of finely powdered silica include natural silica, which is made by grinding quartz, silica sand, diatomaceous earth, etc. into a fine powder, as well as synthetic silica, such as wet silica, e.g., precipitated silica, and dry silica, e.g., fumed silica.

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

The amount of thixotropy-imparting agent (B) per 100 parts by mass (solids) of 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. On the other hand, 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.

Compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group
In the one-component curable composition of the present invention, if necessary, a compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group may be further blended. 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.

The compound having an oxazolidine ring is a compound having one or more, preferably two to six, oxazolidine rings in the molecule, which are saturated five-membered heterocyclic rings containing oxygen and nitrogen atoms. When this compound having an oxazolidine ring reacts with moisture (humidity) in the atmosphere or the like and undergoes hydrolysis, the oxazolidine ring generates (regenerates) a secondary amino group and an alcoholic hydroxyl group, and functions as a latent curing agent for the isocyanate group-containing urethane prepolymer (A).

When the isocyanate group of the isocyanate group-containing urethane prepolymer (A) reacts with moisture (humidity) in the air, it forms urea bonds and hardens, but carbon dioxide gas is also generated during this process, and bubbles due to the carbon dioxide gas form in the hardened product, causing problems such as poor appearance, breakage of the hardened product, and reduced 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 the 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 foaming due to carbon dioxide gas in the one-component curable composition of the present invention can be prevented.

In addition, 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 (moisture). However, by using a compound having an oxazolidine ring as the compound (C) that 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 (moisture) and the isocyanate group derived from isophorone diisocyanate has a higher reaction rate than the reaction with water (moisture), so the curing speed can be increased.

Examples of compounds having an oxazolidine ring include urethane bond-containing oxazolidine compounds which are reaction products between the hydroxyl group of a compound having a hydroxyl group and an oxazolidine ring and the isocyanate group of an organic isocyanate compound, ester bond-containing oxazolidine compounds which are reaction products between the hydroxyl group of a compound having a hydroxyl group and an oxazolidine ring and the carboxyl group of a carboxylic acid compound, oxazolidine silyl ethers, carbonate group-containing oxazolidines, etc. Among these, urethane bond-containing oxazolidine compounds are preferred because of their ease of production and low viscosity.

Examples of urethane bond-containing oxazolidine compounds include those obtained by mixing 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 then reacting the compound at a temperature of 50 to 100°C with an organic solvent added as necessary.

Organic isocyanate compounds used in the synthesis of urethane bond-containing oxazolidine compounds include aromatic polyisocyanates in which an isocyanate group is bonded to an aromatic hydrocarbon, aromatic aliphatic polyisocyanates in which an aromatic ring is present 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.

Aromatic polyisocyanates include diphenylmethane diisocyanates (MDIs) such as 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, or mixtures thereof; toluene diisocyanates (TDIs) such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, or mixtures thereof; other aromatic polyisocyanates include phenylene diisocyanate, diphenyl diisocyanate, naphthalene diisocyanate, diphenyl ether diisocyanate, etc.

Examples of aromatic aliphatic polyisocyanates include xylylene diisocyanate.

Examples of aliphatic polyisocyanates 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.

Other examples include carbodiimide-modified, biuret-modified, allophanate-modified, dimers, trimers, and polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI) of the above-mentioned various polyisocyanates. These can be used alone or in combination of two or more.

Among these, aliphatic polyisocyanates are preferred, and hexamethylene diisocyanate is particularly preferred, because they reduce the crystallinity of the urethane bond-containing oxazolidine compound and improve the workability of the resulting one-component curable composition.

An example of a compound having a hydroxyl group and an oxazolidine ring is 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.

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 aldehyde compounds 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.

Among these, diethanolamine is preferred as the alkanolamine because of the ease of manufacturing the compound having a hydroxyl group and an oxazolidine ring and the superior foaming prevention properties when the resulting one-part curable composition is cured. Of the ketone compounds and aldehyde compounds, aldehyde compounds are preferred, and of the aldehyde compounds, isobutyraldehyde, 2-methylpentylaldehyde, and benzaldehyde are preferred.

Specific examples of compounds 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.

As a method for synthesizing a compound having a hydroxyl group and an oxazolidine ring, for example, 1.0 mole or more, preferably 1.0 to 1.5 moles, and particularly preferably 1.0 to 1.2 moles of a carbonyl group of a ketone compound or aldehyde compound is used per 1.0 mole of secondary amino group of an alkanolamine, and the mixture is heated and refluxed in a solvent such as toluene or xylene to carry out a dehydration condensation reaction while removing the by-product water.

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.

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

Carbonate group-containing oxazolidines can be obtained by reacting the above-mentioned compounds 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.

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 compound (C) that is hydrolyzed by moisture to generate active hydrogen-containing functional groups per 1.0 mole of isocyanate groups in 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. On the other hand, 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.

If necessary, a hydrolysis catalyst for a 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 an organometallic catalyst, an organic carboxylic acid catalyst, an acid anhydride thereof, p-toluenesulfonyl isocyanate, a reaction product of p-toluenesulfonyl isocyanate with moisture, and an organic phosphate ester compound. These can be used alone or in combination of two or more.

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, per 100 parts by mass (solids) 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.

The one-part curable composition of the present invention can further contain additives such as fillers, adhesion improvers, storage stability improvers (dehydrating agents), and colorants, as necessary.

Examples of fillers include inorganic powdered 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 above inorganic fillers has been treated with an organic substance such as a fatty acid; organic powdered 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, as well as 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 from the viewpoint of coatability, 0.01 to 1000 μm is preferable.

An example of an adhesion improver is a coupling agent. Examples of coupling agents include silane-based, aluminum-based, and zircoaluminate-based coupling agents or partial hydrolysis condensation products thereof. Among these, silane-based coupling agents or partial hydrolysis condensation products thereof are preferred from the standpoint of adhesion performance.

Specific examples of silane coupling agents include compounds having an alkoxysilyl group and a molecular weight of 500 or less, preferably 400 or less, such as 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, 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.

Examples of storage stability improvers include vinyltrimethoxysilane, calcium oxide, and p-toluenesulfonyl isocyanate, which react with moisture present in the one-part curable composition. These may be used alone or in combination of two or more. As mentioned above, p-toluenesulfonyl isocyanate is particularly preferred because it also acts as a curing accelerator when compound (C) that hydrolyzes with moisture to generate active hydrogen-containing functional groups is used.

Colorants include inorganic pigments such as titanium oxide, iron oxide, and carbon black, and organic pigments such as copper phthalocyanine. These may be used alone or in combination of two or more.

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

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

In the one-part curable composition of the present invention, the above additives can be used alone or in combination of two or more kinds.

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 deviate from the spirit of the invention.

Synthesis of urethane bond-containing oxazolidine compound O-1 (compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group) 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, and a reflux dehydration reaction was carried out at 110 to 150° C. while removing the by-product water (71.9 g) from the system. After the distillation of water was no longer observed, the mixture was further heated under reduced pressure (50 to 70 hPa) to remove 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 actual NCO content measured by titration reached 0.0 mass %, thereby obtaining a urethane bond-containing oxazolidine compound O-1 (molecular weight 487) having two oxazolidine rings in the molecule. The obtained urethane bond-containing oxazolidine compound O-1 was a liquid at room temperature.

Preparation of One-Component Curable Composition A-1 Used in Example 1 While nitrogen gas was flowing 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, number average molecular weight 3300, manufactured by AGC Inc.), 140 g of an active hydrogen-containing (meth)acrylic polymer (product name: ARUFON UH2041, weight average molecular weight 2500, manufactured by Toa Gosei Co., Ltd.), and 25 g of a compound having at least one active hydrogen and at least one photocurable ethylenically unsaturated group (KAYARA DR-167, average molecular weight 374, manufactured by Nippon Kayaku Co., Ltd.) were charged and mixed by 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 charged while stirring, and then the mixture was heated and reacted for 1 hour at 70 to 75 ° C. Then, 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 charged, 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 and transparent paste-like appearance.

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., trade name: Exenol 4030, number average molecular weight 4000), 160 g of active hydrogen-containing (meth)acrylic polymer (manufactured by Toa Gosei Co., Ltd., trade 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. In the same manner as in Example 1, a one-component curable composition A-2 was prepared. 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 and transparent paste-like appearance.

As the one-component curable composition for 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 for Comparative Example 2, a commercially available sealant-2 (manufactured by Cemedine Co., Ltd., Cemedine 8000 Clear, one-component silicone system) was used.

Test Preparation of measurement sheet A square frame was created on 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 aged for 7 days in an atmosphere of 23°C and 50% RH.

Evaluation Item (1) Measurement of Haze 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 performed in an atmosphere of 23°C using a tensile tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name STROGRAPHVG10-E) to measure the tensile elongation at break Eb (%) and the tensile strength Tb (N/mm ² ).
(3) Measurement of staining property 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 one-component curable compositions were placed in a room at 23 ° C. and 50% relative humidity for 7 days, and then the backer was removed and the siding board was placed 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 one-component curable composition and the commercial product under the siding board were visually observed, and staining property 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) Measurement of Weather Resistance 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 JIS A 1415:2013 "Exposure test method using a laboratory light source for polymer-based building materials". The test pieces were taken out every 1000 hours of exposure up to 5000 hours, 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 defects such as cracks, discoloration, chalking, etc. were observed on the surface.

The evaluation results are shown in Table 1 and Figure 3 below.

From Table 1 above, 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, haze was reduced and excellent transparency was obtained. Furthermore, from Table 1 and FIG. 3 above, in Examples 1 and 2, both weather resistance and stain resistance were excellent. In addition, in Examples 1 and 2, tensile strength (Tb) was improved without impairing tensile elongation at break (Eb), and excellent durability was obtained.

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 advertised transparency, the haze was high and transparency was not obtained. In addition, while sealants that are silicone-based one-liquid curing compositions generally have better weather resistance than sealants that are urethane-based one-liquid curing compositions, Comparative Examples 1 and 2, which are silicone-based one-liquid curing compositions, did not achieve weather resistance and did not achieve tensile strength (Tb) as shown in Table 1 and Figure 3 above, due to abnormalities such as discoloration, cracking, and chalking. In Comparative Example 2, contamination resistance was also not achieved.

The one-part curable composition of the present invention has high transparency and weather resistance, and can produce a cured product that does not impair the aesthetic appearance of the building exterior and does not contaminate the surrounding area for a long period of time, so it can be used as a sealant for buildings, for example, a sealant for vent caps.

1 Siding 2 One-component curable composition

Claims (12)

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. 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% by mass or more and 7.0% by mass or less. The one-part curable composition according to claim 1 or 2, wherein the active hydrogen-containing compound (b) contains 1.0% by mass or more and 7.0% by mass or less of the compound (b-2) having at least one active hydrogen and at least one photocurable ethylenically unsaturated group. The one-component curable composition according to any one of claims 1 to 3, wherein the organic isocyanate compound (a) includes an alicyclic polyisocyanate compound. The one-component curable composition according to any one of claims 1 to 4, wherein the thixotropic agent (B) contains finely divided silica. The one-component curable composition according to any one of claims 1 to 5, wherein the compound (C) that is hydrolyzed by moisture to generate an active hydrogen-containing functional group is an oxazolidine compound. The one-component curable composition according to any one of claims 1 to 6, wherein the isocyanate group-containing urethane prepolymer (A) has an isocyanate group content of 0.10% by mass or more and 15% by mass or less. The one-component curable composition according to any one of claims 1 to 7, wherein the isocyanate group-containing urethane prepolymer (A) is a reaction product in which the isocyanate group of the organic isocyanate compound (a) is 1.5 mol to 8.0 mol per 1.0 mol of active hydrogen of the active hydrogen-containing compound (b). The one-component curable composition according to any one of claims 1 to 8, 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). The one-component curable composition according to any one of claims 1 to 9, 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 per 1.0 mol of isocyanate group in the isocyanate group-containing urethane prepolymer (A). 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 1000 or more includes a polyoxypropylene-based polyol. A cured product of the one-component curable composition according to any one of claims 1 to 11 .

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