Moisture-curable polyurethane hot melt resin composition, adhesive, and article

Abstract

This moisture-curable polyurethane hot melt resin composition contains a urethane prepolymer which is a reaction product of a polyol (a) and a polyisocyanate (b) and has an isocyanate group. The polyol (a) contains a crystalline aliphatic polyester polyol (a1), an aromatic polyester polyol (a2), a bifunctional polyether polyol (a3), and a trifunctional polyether polyol (a4), the mass ratio [(a3) / (a4)] of the bifunctional polyether polyol (a3) to the trifunctional polyether polyol (a4) is 10 / 1-10 / 4, and the polyisocyanate (b) contains a diisocyanate (b1) and an isocyanurate compound (b2).　This moisture-curable polyurethane hot melt resin composition has excellent heat resistance and excellent hydrolysis resistance.

Description

Moisture-curable polyurethane hot-melt resin composition, adhesive, and article

[0001] The present invention relates to a moisture-curable polyurethane hot-melt resin composition and an adhesive.

[0002] Decorative boards, in which a decorative sheet is bonded to a plate-shaped substrate, are widely used in architectural interior materials such as flooring, doors, fixtures, and tabletops. Urethane-based adhesives, epoxy-based adhesives, modified silicone resin-based adhesives, acrylic-based adhesives, and the like have been used to bond the substrate and the decorative sheet. Among these, moisture-curing polyurethane hot-melt adhesives, which exhibit excellent final adhesive strength upon moisture curing, have been increasingly used in recent years.

[0003] As the moisture-curable polyurethane hot melt adhesive, for example, a moisture-curable polyurethane hot melt adhesive has been disclosed in which a specific amount of an epoxy group-containing silane coupling agent and a (meth)acryloyl group-containing silane coupling agent are contained in an isocyanate-terminated urethane prepolymer (see, for example, Patent Document 1).

[0004] Recently, there has been a strong demand in the market for high durability of building interior materials, and there is an increasing demand for even greater hydrolysis resistance and heat resistance, but the adhesives described above have not been able to provide these properties in an adequate manner.

[0005] JP 2011-225635 A

[0006] The problem to be solved by the present invention is to provide a moisture-curable polyurethane hot-melt resin composition that is excellent in heat resistance and hydrolysis resistance.

[0007] The present invention provides a moisture-curable polyurethane hot-melt resin composition containing a urethane prepolymer having an isocyanate group, which is a reaction product of a polyol (a) and a polyisocyanate (b), wherein the polyol (a) contains an alicyclic polycarbonate polyol (a-1), a crystalline polyester polyol (a-2), and a polyether polyol (a-3), and the polyisocyanate (b) contains a diisocyanate (b-1), a polymethylene polyphenyl polyisocyanate (b-2), and an isocyanurate compound (b-3).

[0008] The present invention also provides an adhesive containing the moisture-curable hot-melt resin composition, and an article bonded together with the adhesive.

[0009] The moisture-curable polyurethane hot-melt resin composition of the present invention has excellent heat resistance and hydrolysis resistance.

[0010] Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be suitably used as an adhesive for bonding decorative boards. The resulting decorative board can also be suitably used for flooring materials, doors such as shoe door doors, closet doors, and kitchen doors, fixtures such as frames, picture frames, and baseboards, and tabletops such as countertops and furniture tops.

[0011] The moisture-curable polyurethane hot-melt resin composition of the present invention contains a urethane prepolymer having an isocyanate group, which is a reaction product of a specific polyol (a) and a specific polyisocyanate (b).

[0012] The polyol (a) contains, as essential components, a crystalline aliphatic polyester polyol (a1), an aromatic polyester polyol (a2), a bifunctional polyether polyol (a3), and a trifunctional polyether polyol (a4), and further contains (a3) ​​and (a4) in specific ranges.

[0013] The crystalline aliphatic polyester polyol (a1) is an essential component for obtaining excellent adhesiveness, heat resistance, and hydrolysis resistance. As the crystalline aliphatic polyester polyol (a1), for example, a reaction product of a compound having a hydroxyl group and a polybasic acid can be used. In the present invention, "crystalline" refers to a material in which a peak of heat of crystallization or heat of fusion can be confirmed in DSC (differential scanning calorimetry) measurement according to JIS K7121:2012, and "amorphous" refers to a material in which the peak cannot be confirmed.

[0014] Examples of the compound having a hydroxyl group that can be used include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, glycerin, etc. These compounds may be used alone or in combination of two or more.

[0015] Examples of the polybasic acid that can be used include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, etc. These polybasic acids may be used alone or in combination of two or more.

[0016] The total number of carbon atoms in the hydroxyl group-containing compound and the polybasic acid is preferably 12 to 22, more preferably 16 to 18. Using a highly hydrophobic, long-chain raw material can suppress water absorption and achieve a higher level of hydrolysis resistance. When multiple raw materials are used as the hydroxyl group-containing compound, the average value is used to count the number of carbon atoms. When multiple raw materials are used as the polybasic acid, the average value is used to count the number of carbon atoms. For example, when 1,6-hexanediol (C6) and adipic acid (C6) are used as raw materials, the number of carbon atoms is 12. When 1,6-hexanediol (C6), 1,4-butanediol (C4), and adipic acid (C6) are used as raw materials, the number of carbon atoms is 10.

[0017] The number average molecular weight of the crystalline aliphatic polyester polyol (a1) is preferably 500 to 10,000, more preferably 1,000 to 8,000, in order to obtain even better adhesiveness, heat resistance, and hydrolysis resistance. The number average molecular weight of the crystalline aliphatic polyester polyol (a1) is a value measured by gel permeation chromatography (GPC).

[0018] The amount of the crystalline polyester polyol (a1) used is preferably 10 to 40 mass %, more preferably 15 to 30 mass %, of the total mass of the polyol (a) and the polyisocyanate (b), from the viewpoint of obtaining even better adhesiveness, heat resistance, and hydrolysis resistance.

[0019] The aromatic polyester polyol (a2) is an essential component for obtaining excellent adhesiveness, heat resistance, and hydrolysis resistance.As the aromatic polyester polyol (a2), for example, the reaction product of a compound having a hydroxyl group and a polybasic acid, including an aromatic polybasic acid; the reaction product of an aromatic compound having two or more hydroxyl groups and a polybasic acid; the reaction product of an aromatic compound having two or more hydroxyl groups and a polybasic acid, including an aromatic polybasic acid, etc. can be used.

[0020] Examples of the compound having a hydroxyl group include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, and 2-methyl-1,3-propanediol. Examples of compounds that can be used include aliphatic compounds such as propanediol, 2,2-diethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,4-diethyl-1,5-pentanediol, trimethylolethane, trimethylolpropane, and pentaerythritol; and alicyclic compounds such as cyclopentanediol, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, and alkylene oxide adducts thereof. These compounds may be used alone or in combination of two or more.

[0021] Examples of the aromatic compound having two or more hydroxyl groups that can be used include bisphenol A, bisphenol F, and alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts thereof. These compounds may be used alone or in combination of two or more.

[0022] Examples of the aromatic polybasic acid that can be used include phthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride. Other examples of the polybasic acid that can be used include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and 1,12-dodecanedicarboxylic acid. These polybasic acids may be used alone or in combination of two or more. It is preferable to use one or more compounds selected from the group consisting of phthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride as the aromatic polybasic acid, since this provides even better initial adhesive strength and flexibility.

[0023] Examples of the other polybasic acids that can be used include succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, dodecanedioic acid, eicosadioic acid, citraconic acid, itaconic acid, citraconic anhydride, and itaconic anhydride.

[0024] The number average molecular weight of the aromatic polyester polyol (a2) is preferably 300 to 2,500, more preferably 600 to 2,200, in order to obtain even better adhesiveness, heat resistance, and hydrolysis resistance. The number average molecular weight of the aromatic polyester polyol (a2) is a value measured by gel permeation chromatography (GPC).

[0025] The amount of the aromatic polyester polyol (a2) used is preferably 10 to 40 mass %, more preferably 15 to 30 mass %, of the total mass of the polyol (a) and the polyisocyanate (b), from the viewpoint of obtaining even better adhesiveness, heat resistance, and hydrolysis resistance.

[0026] The bifunctional polyether (a3) ​​is an essential component for obtaining excellent adhesiveness, heat resistance, and hydrolysis resistance, and has two hydroxyl groups, and examples thereof include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, polyoxypropylene polyoxytetramethylene glycol, etc. Among these, polypropylene glycol is preferred because it provides even better adhesiveness, heat resistance, and hydrolysis resistance.

[0027] The number average molecular weight of the bifunctional polyether polyol (a3) ​​is preferably 300 to 50,000, more preferably 500 to 10,000, in order to obtain even better adhesiveness, heat resistance, and hydrolysis resistance. The number average molecular weight of the bifunctional polyether polyol (a3) ​​is a value measured by gel permeation chromatography (GPC).

[0028] The amount of the bifunctional polyether polyol (a3) ​​used is preferably 10 to 30 mass %, more preferably 15 to 20 mass %, of the total mass of the polyol (a) and the polyisocyanate (b), from the viewpoint of obtaining even better adhesiveness, heat resistance, and hydrolysis resistance.

[0029] The trifunctional polyether polyol (a4) is an essential component for achieving excellent adhesiveness, heat resistance, and hydrolysis resistance, and has three hydroxyl groups. Examples of such trifunctional polyether polyols include propylene oxide adducts such as a reaction product of glycerin and propylene oxide, or a reaction product of trimethylolpropane and propylene oxide; propylene oxide and ethylene oxide adducts such as a polyoxyethylene polyoxypropylene triol obtained by adding propylene oxide to glycerin as an initiator and then further adding ethene oxide to the terminal; a polyoxyethylene polyoxypropylene triol obtained by adding propylene oxide to trimethylolpropane as an initiator and then further adding ethene oxide to the terminal; and a polyoxyethylene polyoxypropylene triol obtained by adding propylene oxide to trimethylolpropane as an initiator and then further adding ethene oxide to the terminal. These trifunctional polyether polyols may be used alone or in combination of two or more. Among these, a reaction product of glycerin and propylene oxide and / or a reaction product of trimethylolpropane and propylene oxide are preferred because they provide even better adhesiveness, heat resistance, and hydrolysis resistance.

[0030] The number average molecular weight of the trifunctional polyether polyol (a4) is preferably 300 to 50,000, more preferably 500 to 10,000, in order to obtain even better adhesiveness, heat resistance, and hydrolysis resistance. The number average molecular weight of the trifunctional polyether polyol (a4) is a value measured by gel permeation chromatography (GPC).

[0031] The amount of the trifunctional polyether polyol (a4) used is preferably 1 to 10 mass %, more preferably 1 to 3 mass %, of the total mass of the polyol (a) and the polyisocyanate (b), from the viewpoint of obtaining even more excellent adhesiveness, heat resistance, and hydrolysis resistance.

[0032] The mass ratio [(a3) / (a4)] of the bifunctional polyether polyol (a3) ​​to the trifunctional polyether polyol (a4) must be 10 / 1 to 10 / 4, and preferably 10 / 1 to 10 / 2. By using both in this range, the resulting urethane prepolymer has an appropriate intramolecular crosslinking structure, and higher levels of heat resistance and hydrolysis resistance are obtained.

[0033] The polyol (a) contains the above-mentioned (a1) to (a4) as essential components, but other polyols may be used in combination as necessary. Examples of the other polyols that can be used include polycaprolactone polyols, polyester polyols other than the above-mentioned (a1) and (a2), polyether polyols other than the above-mentioned (a3) ​​and (a4), polyacrylic polyols, and polybutadiene polyols. These polyols may be used alone or in combination of two or more. It is preferable not to use polycarbonate polyols as the other polyols. Reasons for this include their higher cost compared to polyether polyols and the fact that they promote compatibilization between polyols and delay the onset of crystallinity.

[0034] The polyisocyanate (b) must contain a diisocyanate (b1) and an isocyanurate compound (b2) in order to obtain excellent adhesiveness, heat resistance, and hydrolysis resistance.

[0035] Examples of the diisocyanate (b1) that can be used include aromatic diisocyanates such as diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate isocyanate, xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate, and aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate. These polyisocyanates may be used alone or in combination of two or more. Among these, aromatic polyisocyanates are preferred, and diphenylmethane diisocyanate is more preferred, because they provide even better reactivity and adhesion.

[0036] The amount of the diisocyanate (b1) used is preferably 10 to 30 mass %, more preferably 15 to 25 mass %, of the total mass of the polyol (a) and the polyisocyanate (b), from the viewpoint of obtaining even better adhesiveness, heat resistance, and hydrolysis resistance.

[0037] As the isocyanurate compound (b2), for example, an isocyanurate of the diisocyanate (b1) can be used. As the diisocyanate used as a raw material, an aliphatic diisocyanate is preferred, and hexamethylene diisocyanate is more preferred, in terms of obtaining even better adhesiveness, heat resistance, and hydrolysis resistance.

[0038] The amount of the isocyanurate compound (b2) used is preferably 1 to 10 mass %, more preferably 3 to 8 mass %, of the total mass of the polyol (a) and the polyisocyanate (b), from the viewpoint of obtaining even more excellent adhesiveness, heat resistance, and hydrolysis resistance.

[0039] The mass ratio [(b1) / (b2)] of the diisocyanate (b1) to the isocyanurate compound (b2) is preferably 10 / 1 to 10 / 5, and more preferably 10 / 2 to 10 / 3, in order to obtain even more excellent adhesive properties, heat resistance, and hydrolysis resistance.

[0040] The polyisocyanate (b) contains the (b1) and (b2) as essential components, but may contain other polyisocyanates as necessary. Examples of the other polyisocyanates that can be used include adducts and biuret forms of the diisocyanate (b1). These polyisocyanates may be used alone or in combination of two or more. It is preferable not to use polymethylene polyphenyl polyisocyanate as the other polyisocyanate, as this reduces heat resistance.

[0041] The urethane prepolymer is obtained by reacting the polyol (a) with the polyisocyanate (b), and has an isocyanate group that can react with moisture present in the air or in the substrate to which the urethane prepolymer is applied to form a crosslinked structure.

[0042] The urethane prepolymer can be produced, for example, by adding the polyol (a) mixture dropwise to a reaction vessel containing the polyisocyanate (b), followed by heating, and reacting the mixture under conditions in which the isocyanate groups of the polyisocyanate (b) are in excess relative to the hydroxyl groups of the polyol (a).

[0043] When producing the urethane prepolymer, the molar ratio (NCO / OH) of the hydroxyl groups in the polyol (a) to the isocyanate groups in the polyisocyanate (b) is preferably 1.5 to 7, more preferably 1.8 to 3, in order to obtain even better adhesiveness, heat resistance, and hydrolysis resistance.

[0044] The isocyanate group content (hereinafter abbreviated as "NCO %") of the urethane prepolymer obtained by the above method is preferably 1 to 10% by mass, more preferably 2 to 5% by mass, in order to obtain even better adhesion, heat resistance, and hydrolysis resistance. The NCO % of the urethane prepolymer is a value measured by potentiometric titration in accordance with JIS K1603-1:2007.

[0045] The moisture-curable polyurethane hot-melt resin composition of the present invention contains the urethane prepolymer, and may contain other additives as needed.

[0046] Examples of the other additives that can be used include curing catalysts, antioxidants, tackifiers, plasticizers, light stabilizers, fillers, dyes, pigments, antifoaming agents, fluorescent brighteners, silane coupling agents, waxes, thermoplastic resins, etc. These additives may be used alone or in combination of two or more.

[0047] Next, the article will be described.

[0048] The article is formed by bonding at least two articles together with an adhesive containing the moisture-curable polyurethane hot-melt resin composition.

[0049] Examples of the article to be bonded include wooden substrates such as planks of wood, laminated lumber, plywood, MDF (medium density fiberboard), and particle board; inorganic substrates such as hard cement calcium silicate board; resin sheets; glass; rubber; plastic molded products; decorative paper, nonwoven fabrics, woven fabrics, veneers; and tatami mats.

[0050] The thickness of the adhesive layer can be appropriately determined as long as sufficient adhesiveness is obtained, and may be, for example, in the range of 0.03 to 0.15 mm.

[0051] As described above, the moisture-curable polyurethane hot-melt resin composition of the present invention has excellent heat resistance and hydrolysis resistance.

[0052] Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be suitably used as an adhesive for bonding decorative boards. The resulting decorative board can also be suitably used for flooring materials, doors such as shoe door doors, closet doors, and kitchen doors, fixtures such as frames, picture frames, and baseboards, and tabletops such as countertops and furniture tops.

[0053] The present invention will be described in more detail below using examples.

[0054] Example 1 A four-neck flask equipped with a stirrer, a thermometer, an inert gas inlet, and a reflux condenser was charged with 10 parts by mass of crystalline aliphatic polyester polyol 1 (made from 1,6-hexanediol and adipic acid, number average molecular weight: 4,500), 10 parts by mass of crystalline aliphatic polyester polyol 2 (made from 1,6-hexanediol and dodecanedioic acid, number average molecular weight: 3,500), 20 parts by mass of aromatic polyester polyol 1 (made from ethylene glycol, neopentyl glycol, terephthalic acid, and isophthalic acid, number average molecular weight: 2,600), 15 parts by mass of polypropylene glycol (number average molecular weight: 2,000), and 2 parts by mass of trifunctional polypropylene glycol (reaction product of glycerin and propylene oxide, number average molecular weight: 700), and the mixture was dehydrated by heating under reduced pressure at 90°C until the water content was 0.05% by mass or less. Next, after the temperature inside the reaction vessel was cooled to 60°C, 13 parts by mass of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI") and 3.3 parts by mass of an isocyanurate of hexamethylene diisocyanate (hereinafter abbreviated as "HDI-N") were added, and the temperature was raised to 110°C. The mixture was reacted for about 3 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (1) having isocyanate groups.

[0055] [Example 2] A four-neck flask equipped with a stirrer, thermometer, inert gas inlet, and reflux condenser was charged with 10 parts by mass of crystalline aliphatic polyester polyol 1, 10 parts by mass of crystalline aliphatic polyester polyol 2, 20 parts by mass of aromatic polyester polyol 1, 15 parts by mass of polypropylene glycol, and 6 parts by mass of trifunctional polypropylene glycol, and heated under reduced pressure at 90 ° C. to dehydrate until the water content was 0.05% by mass or less. Next, the temperature in the reaction vessel was cooled to 60 ° C., and then 18 parts by mass of MDI and 4.5 parts by mass of HDI-N were added. The temperature was raised to 110 ° C., and the mixture was allowed to react for about 3 hours until the isocyanate group content became constant, to obtain a urethane prepolymer (2) having an isocyanate group.

[0056] [Example 3] A four-necked flask equipped with a stirrer, thermometer, inert gas inlet and reflux condenser was charged with 10 parts by mass of crystalline aliphatic polyester polyol 1, 10 parts by mass of crystalline aliphatic polyester polyol 2, 20 parts by mass of aromatic polyester polyol 1, 15 parts by mass of polypropylene glycol, and 6 parts by mass of trifunctional polypropylene glycol (number average molecular weight: 3,000), and dehydrated to a water content of 0.05% by mass or less by heating under reduced pressure at 90 ° C. Next, after cooling the temperature in the reaction vessel to 60 ° C., 12.5 parts by mass of MDI and 3.1 parts by mass of HDI-N were added, and the temperature was raised to 110 ° C., and the mixture was allowed to react for about 3 hours until the isocyanate group content became constant, to obtain a urethane prepolymer (3) having an isocyanate group.

[0057] [Comparative Example 1] A four-neck flask equipped with a stirrer, a thermometer, an inert gas inlet, and a reflux condenser was charged with 10 parts by mass of crystalline aliphatic polyester polyol 1, 10 parts by mass of crystalline aliphatic polyester polyol 2, 20 parts by mass of aromatic polyester polyol 1, and 17 parts by mass of polypropylene glycol, and the mixture was dehydrated by heating under reduced pressure at 90°C until the water content was 0.05% by mass or less. Next, the temperature in the reaction vessel was cooled to 60°C, and 13 parts by mass of MDI was added. The temperature was raised to 110°C, and the mixture was reacted for about 3 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (R1) having an isocyanate group.

[0058] [Comparative Example 2] A four-neck flask equipped with a stirrer, thermometer, inert gas inlet, and reflux condenser was charged with 10 parts by mass of crystalline aliphatic polyester polyol 1, 10 parts by mass of crystalline aliphatic polyester polyol 2, 20 parts by mass of aromatic polyester polyol 1, and 17 parts by mass of polypropylene glycol, and heated under reduced pressure at 90 ° C. to dehydrate until the water content was 0.05% by mass or less. Next, the temperature in the reaction vessel was cooled to 60 ° C., and then 13 parts by mass of MDI and 3.3 parts by mass of HDI-N were added, and the temperature was raised to 110 ° C. The mixture was reacted for about 3 hours until the isocyanate group content became constant, to obtain a urethane prepolymer (R2) having an isocyanate group.

[0059] [Comparative Example 3] A four-neck flask equipped with a stirrer, thermometer, inert gas inlet, and reflux condenser was charged with 10 parts by mass of crystalline aliphatic polyester polyol 1, 10 parts by mass of crystalline aliphatic polyester polyol 2, 20 parts by mass of aromatic polyester polyol 1, and 17 parts by mass of polypropylene glycol, and heated under reduced pressure at 90 ° C. to dehydrate until the water content was 0.05% by mass or less. Next, the temperature in the reaction vessel was cooled to 60 ° C., and then 10 parts by mass of MDI and 3 parts by mass of polymethylene polyphenyl polyisocyanate were added. The temperature was raised to 110 ° C., and the mixture was reacted for about 3 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (R3) having an isocyanate group.

[0060] [Method for Measuring Number Average Molecular Weight] The number average molecular weight of the polyols used in the examples and comparative examples is a value measured by gel permeation chromatography (GPC) under the following conditions.

[0061] Measurement apparatus: High-speed GPC apparatus ("HLC-8220GPC" manufactured by Tosoh Corporation) Column: The following columns manufactured by Tosoh Corporation were used, connected in series: "TSKgel G5000" (7.8 mm I.D. x 30 cm) x 1, "TSKgel G4000" (7.8 mm I.D. x 30 cm) x 1, "TSKgel G3000" (7.8 mm I.D. x 30 cm) x 1, "TSKgel G2000" (7.8 mm I.D. x 30 cm) x 1 Detector: RI (differential refractometer) Column temperature: 40°C Eluent: Tetrahydrofuran (THF) Flow rate: 1.0 mL / min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass) Standard sample: A calibration curve was prepared using the following standard polystyrene.

[0062] (Standard polystyrene) "TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

[0063] [Method for evaluating heat resistance] The moisture-curable polyurethane hot melt resin compositions obtained in the examples and comparative examples were heated to a molten state at 120°C and applied to a polyethylene terephthalate (PET) sheet to a thickness of 50 μm. Next, MDF (medium density fiberboard) was placed on the coated surface and laminated, and this was left for 5 days under conditions of 23°C and 50% humidity. Thereafter, it was placed in a dryer at 80°C, and a load of 500 g / inch was applied in a 90° direction. The distance traveled after 24 hours was measured and evaluated as follows: "T": Less than 5 mm. "F": 5 mm or more.

[0064] [Method for evaluating hydrolysis resistance] The moisture-curable polyurethane hot melt resin compositions obtained in the examples and comparative examples were heated to a molten state at 120°C and applied to a polyethylene terephthalate (PET) sheet to a thickness of 50 μm. Next, MDF (medium density fiberboard) was placed on the coated surface and laminated, and this was left for 5 days under conditions of 23°C and 50% humidity. Thereafter, it was placed in a thermostatic chamber at 85°C and 85% humidity, and a load of 70°C was applied in a 90° direction, and the number of days until the PET sheet peeled off 40 mm was measured and evaluated as follows: "T": 30 days or more "F": Less than 30 days

[0065]

[0066] It was found that the moisture-curable polyurethane hot-melt resin composition of the present invention has excellent heat resistance and hydrolysis resistance.

[0067] On the other hand, Comparative Example 1 is an embodiment in which neither the trifunctional polyether polyol (a4) nor the isocyanurate compound (b2) was used, and the hydrolysis resistance was poor.

[0068] Comparative Example 2 is an embodiment in which the trifunctional polyether polyol (a4) was not used, and the hydrolysis resistance was poor.

[0069] Comparative Example 3 is an embodiment in which the trifunctional polyether polyol (a4) was not used and further polymethylene polyphenyl polyisocyanate was used instead of the isocyanurate compound (b2), but the heat resistance was poor.

Claims

1. A moisture-curable polyurethane hot melt resin composition containing a urethane prepolymer having an isocyanate group, which is a reaction product of polyol (a) and polyisocyanate (b), wherein the polyol (a) contains a crystalline aliphatic polyester polyol (a1), an aromatic polyester polyol (a2), a bifunctional polyether polyol (a3), and a trifunctional polyether polyol (a4), wherein the mass ratio of the bifunctional polyether polyol (a3) ​​to the trifunctional polyether polyol (a4) [(a3) / (a4)] is 10 / 1 to 10 / 4, and the polyisocyanate (b) contains a diisocyanate (b1) and an isocyanurate compound (b2).

2. The moisture-curable polyurethane hot-melt resin composition according to claim 1, wherein the polyol (a) does not contain a polycarbonate polyol.

3. The moisture-curable polyurethane hot-melt resin composition according to claim 1, wherein the polyisocyanate (b) does not contain polymethylene polyphenyl polyisocyanate (b-2).

4. An adhesive comprising the moisture-curable polyurethane hot-melt resin composition according to claim 1.

5. An article having a bonded joint made with the adhesive according to claim 4.

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