One-component moisture-curable urethane resin composition and coating material including the same

Abstract

To provide a one-component moisture-curable urethane resin composition that achieves superior storage stability and curability in a one-component form, and that, once cured, exhibits superior weather resistance and impact resistance as well as high contamination resistance against dirt including rain streaks, and also to provide a coating material including the same.SOLUTION: A moisture-curable resin composition in which a urethane prepolymer synthesized from a polyol and an aliphatic isocyanate is blended with an oxazolidine as a latent curing agent and a polymer having a hydrolyzable silyl group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a one-component moisture-curable urethane resin composition and a coating material using the same. More specifically, the present invention relates to a one-component moisture-curable urethane resin composition that provides a cured product with excellent weather resistance and impact resistance as well as low contamination, and a coating material using the same. [Background technology]

[0002] One-component moisture-curing urethane resins are used in adhesives, paints, coating materials, top coats, sealants, etc. because of their adhesion to substrates, ease of adjusting physical properties, ease of handling, etc. Here, a high level of weather resistance is required of urethane resins, particularly for applications that involve direct exposure to sunlight, such as paints, coating materials, and top coats. On the other hand, paints, coating materials, top coats, etc. also require durability against external forces, such as impact resistance.

[0003] Furthermore, because these materials are directly exposed to rain, snow, etc., they must also be highly resistant to stains such as rain streaks. Paints and coatings that prevent stains such as rain streaks must make their surfaces water-soluble so that any organic matter adhering to them can be washed away by rain.

[0004] Patent Document 1 proposes a room-temperature curable composition with excellent paint contamination resistance, which comprises a polymer having a hydrolyzable silicon group in which three hydrolyzable groups are bonded to silicon, a curing catalyst, a polymeric plasticizer, and / or a plasticizer with a viscosity of 8P or more at 25° C. However, coating films formed using such compositions have issues with weather resistance and do not achieve sufficient hardness, so improvements are required, particularly in terms of the strength of the cured product. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-116831 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a one-component moisture-curable urethane resin composition which has excellent storage stability and curability as a one-component type, and which, after curing, has excellent weather resistance and impact resistance as well as high resistance to contamination by rain streaks and the like, and a paint using the same. [Means for solving the problem]

[0007] Conventionally, it has not been possible to mix a one-component urethane resin composition with a polymer having a hydrolyzable silyl group because the alcohol generated from the hydrolyzable silyl group inhibits the curing of the one-component urethane resin.

[0008] The object of the present invention is achieved by a moisture-curable resin composition obtained by blending a urethane prepolymer synthesized from a polyol and an aliphatic isocyanate, preferably a urethane prepolymer synthesized from a polyol consisting of a polycarbonate polyol (PC) and an acrylic polyol (AC) having a hydroxyl value of 60 to 150 mgKOH / g, and a polyisocyanate, with an oxazolidine latent curing agent and a polymer having a hydrolyzable silyl group. [Effects of the Invention]

[0009] The urethane resin composition of the present invention has excellent storage stability as a one-component type and is moisture-curable, so that it cures with atmospheric moisture to form a cured product. In addition, the cured product of this composition has the effects of having high weather resistance and impact resistance, and also excellent contamination resistance of the paint surface. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention comprises a urethane prepolymer synthesized from a polyol and an aliphatic isocyanate, preferably a urethane prepolymer synthesized from a polyol consisting of a polycarbonate polyol (PC) and an acrylic polyol (AC) having a hydroxyl value of 60 to 150 mgKOH / g, and a polyisocyanate, a latent curing agent, and a hydrolyzable silyl group-containing polymer.

[0011] Examples of polyols include those having 2 to 10 hydroxyl groups per molecule, such as polycarbonate polyol, polyether polyol, polyester polyol, and poly(meth)acrylic polyol. Preferably, a polyol consisting of at least one polyol selected from polycarbonate polyol, polytetramethylene polyol, and polyester polyol and poly(meth)acrylic polyol is used.

[0012] Examples of polycarbonate polyols include those obtained by reacting at least one aliphatic polyhydric alcohol, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, or cyclohexanedimethylol, with a dialkylene carbonate or dialkyl carbonate, such as diethylene carbonate, dimethyl carbonate, or diethyl carbonate, in which the alkylene or dialkyl group has 2 to 10 carbon atoms. Such polycarbonate polyols preferably have a number average molecular weight Mn of 500 to 3000, and commercially available products such as ETERNACOLL UH-50, UH-100, UH-200, UH-300, PH-50, PH-100, PH-200, PH-300, UC-100, and UM-90U manufactured by UBE, and Nipporan 981, 980R, 982R, 965, 963, 964, and 968 manufactured by Tosoh can be used as they are.

[0013] Suitable polyether polyols include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, with polytetramethylene glycol being more suitable in terms of weather resistance and the mechanical properties of the urethane. Polyether polyols with a number average molecular weight Mn of 500 to 2000 are preferably used.

[0014] As the polyester polyol, for example, a reaction product of a compound having two or more hydroxyl groups with a polybasic carboxylic acid can be used.

[0015] Examples of compounds having two or more hydroxyl groups that can be used include ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, hexanediol, neopentyl glycol, hexamethylene glycol, glycerin, trimethylolpropane, bisphenol A, bisphenol F, and alkylene oxide adducts thereof. Of these, from the viewpoint of weather resistance, at least one of 2,4-diethyl-1,5 pentanediol and 2-ethyl-2-butyl-1,3-propanediol is preferably used.

[0016] Examples of polybasic carboxylic acids that can be used include adipic acid, glutaric acid, pimelic acid, suberic acid, dimer acid, sebacic acid, undecanedicarboxylic acid, hexahydroterephthalic acid, phthalic acid, phthalic anhydride, isophthalic acid, and terephthalic acid. Of these, phthalic acid is preferred from the viewpoints of even better adhesion to fabrics and film strength.

[0017] The number average molecular weight Mn of the polyester polyol is preferably in the range of 500 to 50,000, in order to obtain even better adhesive properties and mechanical properties. For example, commercially available products such as the Polylite series manufactured by DIC, the Nipporan series manufactured by Tosoh, and the Adeka New Ace series manufactured by ADEKA, which are liquid or solid at room temperature, can be used as they are.

[0018] Examples of acrylic polyols include homopolymers or copolymers of (meth)acrylic monomers having hydroxyl groups, or those having a predetermined hydroxyl group number obtained by copolymerizing a (meth)acrylic monomer having hydroxyl groups with another monomer having a polymerizable unsaturated bond. The acrylic polyol used in the one-component moisture-curing urethane resin preferably has an average of 2 to 10 hydroxyl groups per molecule.

[0019] Examples of (meth)acrylic monomers having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, as well as triol (meth)acrylic acid monoesters such as glycerin (meth)acrylic acid monoester and trimethylolpropane (meth)acrylic acid monoester. These may be used alone or in combination of two or more.

[0020] Other monomers having polymerizable unsaturated bonds can also be used in combination, such as alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and 3-methoxybutyl (meth)acrylate; unsaturated carboxylic acids such as (meth)acrylic acid, maleic acid, and itaconic acid; unsaturated amides such as (meth)acrylamide and N-methylol (meth)acrylamide; styrene, vinyl toluene, vinyl acetate, and acrylonitrile. These may be used alone or in combination of two or more. Among these, (meth)acrylic acid esters such as alkyl (meth)acrylate and / or alkoxyalkyl (meth)acrylate are preferably used in terms of weather resistance.

[0021] As the urethane prepolymer, it is essential to use an aliphatic isocyanate as the main component from the viewpoint of weather resistance, and specifically, an aliphatic or alicyclic polyisocyanate is used. Examples of such polyisocyanates include hydrogenated diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), hydrogenated XDI, tetramethylxylene diisocyanate (TMXDI), 1,8-diisocyanatomethyloctane, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, bicycloheptane triisocyanate, and derivatives thereof such as modified products (biuret, allophanate, isocyanurate), and trimethylolpropane adducts, and from the viewpoint of the weather resistance and strength of the coating film, isophorone diisocyanate and its derivatives are preferred.

[0022] When synthesizing the urethane prepolymer, a hydroxyl-containing oxazolidine can be used in an amount of 0.5 equivalents or less relative to the remaining isocyanate groups. Examples of hydroxyl-containing oxazolidines include 2-isopropyl-3-(2-hydroxyethyl)oxazolidine, 2-(1-methylbutyl)-3-(2-hydroxyethyl)oxazolidine, N-hydroxyethyl-2-phenyloxazolidine, and 2-(p-methoxyphenyl)-3-(2-hydroxyethyl)oxazolidine. From the viewpoints of storage stability, curability, and physical properties after curing, 2-isopropyl-3-(2-hydroxyethyl)oxazolidine is preferred. These hydroxyalkyl oxazolidines are synthesized from the corresponding aldehyde or ketone and a hydroxyalkylamine by known methods.

[0023] The hydroxyl value of the acrylic polyol is preferably 40 to 150 mgKOH / g, more preferably 60 to 150 mgKOH / g. If the hydroxyl value is less than this value, the hardness of the coating film tends to decrease, and the stain resistance decreases. If the hydroxyl value is greater than this value, the coating film tends to become too hard and brittle.

[0024] The Tg of the acrylic polyol is preferably −70 to 100° C. If it exceeds 100° C., the impact resistance of the coating film will decrease. Even if the Tg of the acrylic polyol is low, the mechanical properties can be controlled by increasing the number of hydroxyl groups, so it can be selected appropriately depending on the properties of the polyol used at the same time.

[0025] As the acrylic polyol, for example, commercially available products such as the Excelol series manufactured by Asia Industries and the Acridec series manufactured by DIC, A-801-P (Tg: 50°C, hydroxyl value: 47, acid value: 1 to 4) and WBU1218 (Tg: 100°C, hydroxyl value: 55, acid value: 1 to 3), can be used as they are.

[0026] The above components are preferably 20 to 80 parts by mass of acrylic polyol, 0 to 80 parts by mass of polycarbonate polyol, 0 to 80 parts by mass of polytetramethylene glycol, and 0 to 80 parts by mass of polyester polyol per 100 parts by mass of polyol, and other polyols can also be used in the range of 0 to 20 parts by mass to adjust the viscosity and mechanical properties.

[0027] The urethane prepolymer is blended with a latent curing agent and a hydrolyzable silyl group-containing polymer.

[0028] As the latent curing agent, a hydroxyl group-containing oxazolidine is used. Examples of the hydroxyl group-containing oxazolidine include the oxazolidines exemplified in the urethane prepolymer. Here, an oxazolidine compound in which a hydroxyl group-containing oxazolidine is reacted with a polyisocyanate in advance, preferably a compound in which a hydroxyl group-containing oxazolidine (OH) is reacted with an isocyanate group (NCO) at a ratio of NCO / OH = 1 / 0.1 to 1 / 1, can also be blended. Here, as the polyisocyanate, an aliphatic polyisocyanate is preferably used.

[0029] The equivalent ratio of isocyanate groups (NCO) to oxazolidine groups (OX) in the urethane resin composition is preferably NCO / OX = 1.0 to 3.0. If the NCO / OX equivalent ratio is less than 1.0, the amount of oxazolidine will be in excess relative to the isocyanate groups, resulting in unreacted amino groups remaining during curing, which can deteriorate weather resistance. On the other hand, if the NCO / OX equivalent ratio exceeds 3.0, the amount of oxazolidine groups (curing agent) will be significantly less than the amount of isocyanate groups, resulting in poor curability.

[0030] Although other hydrolyzable groups in hydrolyzable silyl group-containing polymers include halogen groups and alkoxyl groups, alkoxysilyl groups are preferred due to the ease of reaction control. Polymers with a polyoxyalkylene or poly(meth)acrylic main chain and alkoxysilyl groups at the terminal or side chain are suitable. Kaneka's MS Polymer, XMAP, and Zemulac are examples of suitable polymers. Hydrolyzable silyl group-containing vinyl polymers with a glass transition temperature of 0°C or higher and hydroxyl groups are preferred. Increasing the glass transition temperature to 0°C or higher increases the hardness of the coating film, resulting in excellent stain resistance. Furthermore, the presence of hydroxyl groups chemically bonds the vinyl polymer to the urethane resin, improving not only the weather resistance of the coating film but also its mechanical properties.

[0031] Such a hydrolyzable silyl group-containing vinyl polymer is blended in a ratio of 3 to 30 parts by mass, preferably 5 to 20 parts by mass, per 100 parts by mass of the urethane prepolymer. If the blending ratio is less than this, the amount of silanol generated is insufficient, and sufficient stain resistance cannot be obtained, while if the blending ratio is higher than this, the reaction of the isocyanate in the urethane prepolymer is inhibited by the influence of the generated alcohol, and in addition, the physical properties of the hydrolyzable silyl group-containing vinyl polymer are reflected, making it difficult to obtain a coating film with sufficient mechanical strength.

[0032] In addition to the essential ingredients listed above, compounds with hydrophilic groups, such as tertiary amines, ammonium salts, carboxylates, and polyethylene glycols, can be added at approximately 1 to 10% by weight per 100 parts by weight of urethane prepolymer to hydrophilize the coating surface and improve stain resistance. Examples include choline chloride, 4-(2-hydroxyethyl)morpholine, 4-(2-morpholinoethoxy)aniline, N,N-dimethylethylenediamine, 1-methylpiperazine, N,N,N'-trimethylethylenediamine, 1-(2-hydroxyethyl)-3-methylimidazolium chloride, polyethylene glycol monomethyl ether, and sodium oleate. Commercially available products, such as Nippon Nyukazai's Aminoion AS200 and AS400, and Koei Chemical's reactive ionic liquids IL-OH2 and IL-OH9, can be used as is.

[0033] The moisture-curable urethane resin composition comprising the above components is dissolved in an aromatic solvent and / or an ether solvent to form a coating material having a solids concentration of 40 to 80 mass % in order to ensure coating thickness and ease of use.

[0034] Examples of the solvent include aromatic hydrocarbons such as toluene, xylene, Solvent Naphtha 100, and Solvent Naphtha 150, and ethers such as diethyl ether, dimethyl ether, ethylene glycol mono-n-butyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monobutyl ether acetate, and propylene glycol monomethyl ether acetate. These may be used alone or in combination of two or more.

[0035] Further, other additives that may be used as appropriate include leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, pigments, thixotropic agents, anti-sagging agents, matting agents, fillers, etc. Preferred examples of the thixotropic agents include finely divided silica, amide-based thixotropic agents, and urea-based thixotropic agents.

[0036] Furthermore, as other additives, carboxylic acids and sulfonic acids are preferably used as catalysts for promoting the hydrolysis of oxazolidine, and from the viewpoints of storage stability and curability, aliphatic carboxylic acids having 6 or more carbon atoms are particularly used. [Example]

[0037] Next, the present invention will be described with reference to examples.

[0038] Example 1 (1) 66.7 g of propylene glycol monobutyl ether acetate was charged into a four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube, and the mixture was heated to 92°C while purging with nitrogen. Next, a mixture of 60.0 g of methyl methacrylate, 27.8 g of 2-hydroxyethyl methacrylate, 10.0 g of methyl acrylate, 2.2 g of acrylic acid, 0.02 g of n-dodecyl mercaptan, and 2.9 g of tert-butylperoxy-2-ethylhexanoate was added over 4 hours. One hour and two hours after the end of the supply, 0.2 g of tert-butylperoxy-2-ethylhexanoate was added, and the reaction was continued for another 2 hours to obtain acrylic polyol A (number average molecular weight Mn 1920, hydroxyl value 120 mgKOH / g, Tg 70°C, 60% by weight solution of propylene glycol butyl ether acetate).

[0039] (2) In a 500 mL separable flask equipped with a stirring blade, 83.3 g (equivalent to 50.0 g) of acrylic polyol A, 20 g of dried polyester polyol (DIC Polylite OD-X-2420; hydroxyl value 58.0 mg KOH / g), and 30.0 g of dried polycarbonate diol (ETERNACOLL PH-200; hydroxyl value 55.5 mg KOH / g) were dissolved in 110 g of aromatic solvent (Shin-Nihon Kagaku R100). Then, 42.6 g of isophorone diisocyanate and 0.02 g of dibutyl dilaurate were added and stirred at room temperature for 1 hour. Next, 5.0 g of 2-isopropyl-3-(2-hydroxyethyl)oxazolidine was added, and the mixture was gradually heated to 80°C under a nitrogen stream and reacted at 80°C for 2 hours to yield 257.6 g of urethane prepolymer A (55.4% by weight solution).

[0040] (3) Urethane prepolymer A (55.4% by mass solution) 257.4 g (equivalent to 142.6g of urethane prepolymer) Leveling agent (BYK-UV3576, manufactured by BYK Japan) 0.2g UV absorber (Ciba-Geigy UV1164) 5g Light stabilizer (Ciba-Geigy product HALS292) 5g Hardener 34.6g [2-Isopropyl-3-(2-hydroxyethyl) 2 moles of oxazolidine and hexamethylene Adduct with 1 mole of diisocyanate; molecular weight 486.68 Hydrolyzable silyl group-containing vinyl polymer 14.2g (Kaneka product Zemurac YC4150; 50wt% solution Glass transition temperature (Tg) 20°C Octylic acid 0.03g The mixture was thoroughly stirred to obtain a transparent, one-component, moisture-curable urethane resin composition (viscosity: 314 mPa·s at 25°C using an E-type viscometer at 100 rpm). The equivalent ratio of isocyanate groups to oxazolidine groups (NCO / OX) was 1.10.

[0041] Example 2 In step (3) of Example 1, 1.5 g of Aminoion AS200 (a product of Nippon Nyukazai Co., Ltd.) was further used to obtain a one-component moisture-curable urethane resin composition (NCO / OX equivalent ratio: 1.10, viscosity at 25°C using an E-type viscometer at 100 rpm: 330 mPa s).

[0042] Example 3 In step (3) of Example 1, the amount of hydrolyzable silyl group-containing vinyl polymer was changed to 7.1 g, and a one-component moisture-curable urethane resin composition (NCO / OX equivalent ratio: 1.11, viscosity at 25°C using an E-type viscometer at 100 rpm: 306 mPa s) was obtained.

[0043] Example 4 In step (3) of Example 1, the amount of the hydrolyzable silyl group-containing vinyl polymer was changed to 38.4 g, and a one-component moisture-curable urethane resin composition (NCO / OX equivalent ratio: 1.06, viscosity at 25°C at 100 rpm using an E-type viscometer: 348 mPa s) was obtained.

[0044] Example 5 In step (2) of Example 1, no polyester polyol was used, and 257.4 g (equivalent to 142.4 g) of urethane prepolymer B, obtained by changing the amount of polycarbonate polyol to 50.0 g and the amount of isophorone diisocyanate to 42.4 g, was used instead of urethane prepolymer A. In step (3), the amount of curing agent was changed to 34.3 g, and a one-component moisture-curable urethane resin composition (NCO / OX equivalent ratio 1.10, viscosity at 25°C at 100 rpm using an E-type viscometer 314 mPa s) was obtained.

[0045] Example 6 (1) 50.0 g of acrylic polyol (ARUFON UH-2000, manufactured by Toa Gosei; hydroxyl value 20 mg KOH / g, Tg -55°C) and 50.0 g of polytetramethylene glycol (manufactured by Mitsubishi Chemical; hydroxyl value 56 mg KOH / g) were dissolved in 92 g of aromatic solvent (R100) in a 500 ml separable flask equipped with a stirring blade. Then, 18.4 g of isophorone diisocyanate and 0.02 g of dibutyl dilaurate were added and stirred at room temperature for 1 hour. Next, 2.0 g of 2-isopropyl-3-(2-hydroxyethyl)oxazolidine was added, and the mixture was gradually heated to 80°C under a nitrogen stream and reacted at 80°C for 2 hours to yield 212.4 g of urethane prepolymer C (55.7% by weight solution).

[0046] (2) Urethane prepolymer C (55.7% by mass solution) 212.6 g (equivalent to 118.4g of urethane prepolymer) Leveling agent (BYK-UV3576) 0.2g UV absorber (UV1164) 5g Light stabilizer (HALS292) 5g Hardener 15.4g [2-Isopropyl-3-(2-hydroxyethyl) 2 moles of oxazolidine and hexamethylene Adduct with 1 mole of diisocyanate; molecular weight 486.68 Hydrolyzable silyl group-containing vinyl polymer 11.8g (Zemrack YC4150) Octylic acid 0.03g The mixture was thoroughly stirred to obtain a transparent, one-component, moisture-curable urethane resin composition (viscosity: 295 mPa·s at 25°C using an E-type viscometer at 100 rpm). The equivalent ratio of isocyanate groups to oxazolidine groups (NCO / OX) was 1.08.

[0047] Comparative Example In step (2) of Example 1, the amount of isophorone diisocyanate was changed to 41.8 g, and in step (3) no hydrolyzable silyl group-containing vinyl polymer was used, resulting in a one-component moisture-curable urethane resin composition (NCO / OX equivalent ratio: 1.08, viscosity at 25°C at 100 rpm using an E-type viscometer: 302 mPa s).

[0048] Reference example A one-component moisture-curable urethane resin composition (NCO / OX equivalent ratio: 1.12, viscosity at 25°C using an E-type viscometer at 100 rpm: 298 mPa s) was obtained without using a hydrolyzable silyl group-containing vinyl polymer in step (3) of Example 2.

[0049] The one-component moisture-curable urethane resin compositions obtained in the above examples and comparative examples were subjected to weather resistance tests, impact resistance tests, and stain resistance tests. [Weather resistance test] A 0.15mm thick urethane primer was applied to a Nichiha ceramic siding board, which was prepared by reacting 3.0g of 3-aminopropyltriethoxysilane with the reaction product of 200.0g of acrylic polyol (Toa Gosei Alfon UH2041), 200.0g of aromatic solvent (Shin-Nihon Kagaku R100), 94.1g of isophorone diisocyanate, and 0.3g of dibutyl dilaurate. A 0.3mm thick one-component moisture-curing urethane resin composition was then applied to the board. The board was then cured and aged for two weeks at 23(±2)°C and 50(±10)% RH, resulting in a one-component moisture-curing urethane resin layer. The siding board was then tested and evaluated as follows: Testing machine: Iwasaki Electric Eye Super UV Tester Test conditions: UV irradiance: 150±8mW / cm 2 Temperature: 63℃ Wavelength: 295~450nm Cycle: 63°C ± 3°C, 50% RH, 4 hours of irradiation ⇒ 4 hours of condensation Test result evaluation: No change after 1600 hours: A, no change after 1200 hours: B, no change after 800 hours: C: Whitening or cracking occurs after 800 hours. D: [Impact resistance test] Test method: JIS K5600-5-3 (1999) General test method for paints, Part 5: Mechanical properties of coating film, Part Section 3: Compliant with DuPont standards for resistance to falling weights A one-component moisture-curing adhesive was applied to a 2mm thick piece of acrylic resin cut to 50mm x 50mm. The ethylene resin composition was applied to a thickness of 0.3 mm, and the temperature was maintained at 23 (±2) °C and 50 (± The adhesive was then cured and aged for two weeks in an environment of 10% RH. A 6.35mm radius shot mold and a cradle are attached, and a 300g weight is placed at 40cm and 30cm. Or drop it from a height of 20cm and observe the appearance of the coating. Test result evaluation: A indicates that the coating film does not crack at a height of 40 cm, and A indicates that the coating film cracks at a height of 30 cm. B indicates that no cracks occur, and C indicates that no cracks occur in the coating film at a height of 20 cm. Those in which cracks appeared on the coating at a height of 20 cm were rated as C, and those in which cracks appeared on the coating at a height of 20 cm were rated as D. [Stain resistance test] Test method: A 1mm thick aluminum plate (100 x 300mm) is coated with a white primer (KF Chemical Products Semiconductor) Apply Fluorocarbon Binder Si II to a thickness of 0.1 mm, dry for 16 hours, and then A one-component moisture-curing urethane resin composition was applied to the surface to a thickness of 0.3 mm, and the surface was then cooled to 23 (±2)°C. Vertical test surface of test plate cured and aged for one week under ℃, 50(±10)%RH environment The test piece was bent at an angle of 120° so that the diameter was 200 mm. The specimen was placed on a stand so that the surface was vertical and facing upward, and the contamination status after six months of exposure was observed. Visual evaluation Test result evaluation: AA for no visible rain stains, AA for very slight rain stains A: Rain stains are visible, B: Rain stains are severe, C:

[0050] The results obtained in the above examples and comparative examples are shown in the following table. table Example Evaluation items 1 2 3 4 5 6 Comparative Example Reference example Weather resistance AAAAABAA Impact resistance AAABAAAA Stain resistance A AA AAAACB

Claims

1. A one-component moisture-curable resin composition comprising a urethane prepolymer synthesized from a polyol and an aliphatic isocyanate, a latent curing agent, and a polymer containing a hydrolyzable silyl group.

2. The one-component moisture-curable resin composition according to claim 1, wherein a polyol consisting of 20 to 80 parts by mass of acrylic polyol, 0 to 80 parts by mass of polycarbonate polyol, 0 to 80 parts by mass of polytetramethylene glycol, 0 to 80 parts by mass of polyester polyol, and 0 to 20 parts by mass of a polyol other than these is used.

3. 2. The one-component moisture-curable resin composition according to claim 1, wherein the polyol comprises a polycarbonate polyol (PC) and an acrylic polyol (AC) having a hydroxyl value of 60 to 150 mgKOH / g.

4. 4. The one-component moisture-curable resin composition according to claim 1, wherein the equivalent ratio NCO / OX of the oxazolidine group (OX) serving as a latent curing agent to the isocyanate group (NCO) in the urethane resin composition is 1.0 to 3.0, and the hydrolyzable silyl group-containing vinyl polymer is added in an amount of 3 to 30 parts by mass per 100 parts by mass of the urethane prepolymer.

5. 4. The one-component moisture-curable resin composition according to claim 1, wherein the hydrolyzable silyl group-containing polymer is a vinyl polymer having a glass transition temperature Tg of 0° C. or higher and having a hydroxyl group.