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

Abstract

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 polyol (a) and a polyisocyanate (b), the polyol (a) containing a crystalline aliphatic polyester polyol (a1), an aromatic polyester polyol (a2), a difunctional polyether polyol (a3), and a trifunctional polyether polyol (a4), the mass ratio [ (a3) / (a4) ] of the difunctional polyether polyol (a3) to the trifunctional polyether polyol (a4) being 10 / 1 to 10 / 4, and the polyisocyanate (b) containing a diisocyanate (b1) and an isocyanurate compound (b2). The moisture-curable polyurethane hot melt resin composition of the present invention is excellent in heat resistance and hydrolysis resistance.

Description

Technical Field

[0001] This invention relates to moisture-curing polyurethane hot melt resin compositions and adhesives. Background Technology

[0002] Decorative panels, formed by bonding decorative sheets to a sheet-like substrate, are widely used in building interior materials such as flooring, doors, decorative components, and ceilings. Previously, bonding these substrates to decorative sheets utilized urethane-based adhesives, epoxy-based adhesives, modified silicone resin-based adhesives, and acrylic adhesives. In recent years, however, the use of moisture-curing polyurethane hot-melt adhesives, which exhibit excellent final bond strength upon moisture curing, has been increasing.

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

[0004] Recently, there has been a strong market demand for high durability in building interior materials, with further increases in requirements for hydrolysis resistance and heat resistance. However, these properties are insufficient for the adhesives mentioned above.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-225635 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The problem to be solved by the present invention is to provide a moisture-curing polyurethane hot melt resin composition with excellent heat resistance and hydrolysis resistance.

[0010] Methods for solving problems

[0011] The present invention provides a moisture-curing polyurethane hot melt resin composition, characterized in that it contains a urethane prepolymer having isocyanate groups, the urethane prepolymer being 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).

[0012] Furthermore, the present invention provides an adhesive containing the above-described moisture-curing hot melt resin composition, and articles characterized by being bonded using the adhesive.

[0013] Invention Effects

[0014] The moisture-curing polyurethane hot melt resin composition of the present invention has excellent heat resistance and hydrolysis resistance.

[0015] Therefore, the moisture-curing polyurethane hot melt resin composition of the present invention is suitable for use as an adhesive for bonding decorative panels. Furthermore, the resulting decorative panels are suitable for use in flooring; doors such as shoe cabinet doors, wardrobe doors, and kitchen doors; decorative materials such as frames, picture frames, and baseboards; and top panels such as bar tables and furniture tops. Detailed Implementation

[0016] The moisture-curing 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).

[0017] The above-mentioned polyol (a) contains crystalline aliphatic polyester polyol (a1), aromatic polyester polyol (a2), difunctional polyether polyol (a3) ​​and trifunctional polyether polyol (a4) as essential components, and further contains (a3) ​​and (a4) within a specific range.

[0018] The aforementioned crystalline aliphatic polyester polyol (a1) is an essential component for obtaining excellent adhesion, heat resistance, and hydrolysis resistance. As the aforementioned crystalline aliphatic polyester polyol (a1), for example, the reaction product of a compound having hydroxyl groups and a polybasic acid can be used. It should be noted that in this invention, "crystalline" means that the peaks of heat of crystallization or heat of fusion can be identified in DSC (differential scanning calorimetry) measurements according to JIS K 7121:2012, and "amorphous" means that the aforementioned peaks cannot be identified.

[0019] Examples of compounds containing hydroxyl groups include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptahydrin, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, and glycerol. These compounds can be used alone or in combination of two or more.

[0020] Examples of polyacids that can be used include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and dodecanedicarboxylic acid. These polyacids can be used alone or in combination of two or more.

[0021] Regarding the aforementioned compounds containing hydroxyl groups and the aforementioned polybasic acids, the total number of carbon atoms is preferably 12 to 22, more preferably 16 to 18. By using long-chain raw materials with high hydrophobicity, the introduction of water can be suppressed, and a higher level of hydrolysis resistance can be obtained. It should be noted that when multiple raw materials are used as the aforementioned compounds containing hydroxyl groups, their average value is used for counting the number of carbon atoms; when multiple raw materials are used as the aforementioned polybasic acids, their average value is used for counting 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) and 1,4-butanediol (C4) and adipic acid (C6) are used as raw materials, the number of carbon atoms is set to 10.

[0022] Regarding the number-average molecular weight of the aforementioned crystalline aliphatic polyester polyol (a1), from the perspective of obtaining superior adhesion, heat resistance, and hydrolysis resistance, a value of 500 to 10,000 is preferred, and more preferably 1,000 to 8,000. It should be noted that the number-average molecular weight of the aforementioned crystalline aliphatic polyester polyol (a1) represents a value determined by gel permeation chromatography (GPC).

[0023] Regarding the amount of the crystalline polyester polyol (a1) used, from the perspective of obtaining better adhesion, heat resistance and hydrolysis resistance, the total mass of the polyol (a) and the polyisocyanate (b) is preferably 10 to 40% by mass, more preferably 15 to 30% by mass.

[0024] The aforementioned aromatic polyester polyol (a2) is an essential component for obtaining excellent adhesion, heat resistance, and hydrolysis resistance. Examples of the aforementioned aromatic polyester polyol (a2) include: reaction products of compounds having hydroxyl groups and polyacids containing aromatic polyacids; reaction products of aromatic compounds having two or more hydroxyl groups and polyacids; and reaction products of aromatic compounds having two or more hydroxyl groups and polyacids containing aromatic polyacids.

[0025] As the aforementioned compounds containing hydroxyl groups, for example, the following can be used: 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, tetraethylene glycol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-butanediol. Aliphatic compounds such as propylene glycol, 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, cyclohexanediol, hydrogenated bisphenol A, and their alkyl oxide adducts. These compounds can be used alone or in combination of two or more.

[0026] As aromatic compounds having two or more hydroxyl groups, bisphenol A, bisphenol F, and their alkyl oxide (ethylene oxide, propylene oxide, butane oxide, etc.) adducts can be used, for example. These compounds can be used alone or in combination of two or more.

[0027] Examples of aromatic polybasic acids used as the aforementioned aromatic polybasic acids include phthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride. Other polybasic acids include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and 1,12-dodecanedicarboxylic acid. These polybasic acids can be used alone or in combination of two or more. From the perspective of obtaining superior initial adhesive strength and flexibility, it is preferable to use one or more compounds selected from phthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride as the aforementioned aromatic polybasic acid.

[0028] Other polyacids mentioned above can be succinic acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, decanoic acid, dodecanoic acid, eicosanoic acid, citacic acid, itaconic acid, citacic anhydride, itaconic anhydride, etc.

[0029] Regarding the number-average molecular weight of the aforementioned aromatic polyester polyol (a2), from the perspective of obtaining superior adhesion, heat resistance, and hydrolysis resistance, a value of 300 to 2500 is preferred, and more preferably 600 to 2200. It should be noted that the number-average molecular weight of the aforementioned aromatic polyester polyol (a2) represents a value obtained by gel permeation chromatography (GPC).

[0030] Regarding the amount of the aromatic polyester polyol (a2) used, from the perspective of obtaining better adhesion, heat resistance and hydrolysis resistance, the total mass of the polyol (a) and the polyisocyanate (b) is preferably 10 to 40 by mass, more preferably 15 to 30 by mass.

[0031] The aforementioned difunctional polyether polyol (a3) ​​is an essential component for achieving excellent adhesion, heat resistance, and hydrolysis resistance, and has two hydroxyl groups. Examples of suitable polyols include polyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, and polyoxypropylene polyoxytetramethylene glycol. Among these, polypropylene glycol is preferred for achieving even better adhesion, heat resistance, and hydrolysis resistance.

[0032] Regarding the number-average molecular weight of the aforementioned difunctional polyether polyol (a3), from the perspective of obtaining superior adhesion, heat resistance, and hydrolysis resistance, a value of 300 to 50,000 is preferred, and more preferably 500 to 10,000. It should be noted that the number-average molecular weight of the aforementioned difunctional polyether polyol (a3) ​​represents a value determined by gel permeation chromatography (GPC).

[0033] Regarding the amount of the aforementioned difunctional polyether polyol (a3), from the perspective of obtaining better adhesion, heat resistance and hydrolysis resistance, the total mass of the aforementioned polyol (a) and the aforementioned polyisocyanate (b) is preferably 10 to 30% by mass, more preferably 15 to 20% by mass.

[0034] The aforementioned trifunctional polyether polyol (a4) is an essential component for achieving excellent adhesion, heat resistance, and hydrolysis resistance. It possesses three hydroxyl groups and can be used as follows: propylene oxide adducts such as the reaction product of glycerol and propylene oxide, and the reaction product of trimethylolpropane and propylene oxide; products obtained by adding propylene oxide to glycerol as an initiator followed by further adding ethylene oxide to the terminal; products obtained by adding a mixture of propylene oxide and ethylene oxide to glycerol as an initiator; products obtained by adding propylene oxide to glycerol as an initiator followed by further adding ethylene oxide to the terminal; and products obtained by adding a mixture of propylene oxide and ethylene oxide to glycerol as an initiator, etc., as polyoxyethylene polyoxypropylene triols, etc., as propylene oxide and ethylene oxide adducts. These trifunctional polyether polyols can be used alone or in combination of two or more. Among these, from the perspective of obtaining better adhesion, heat resistance and hydrolysis resistance, the reaction products of glycerol and propylene oxide and / or the reaction products of trimethylolpropane and propylene oxide are preferred.

[0035] Regarding the number-average molecular weight of the aforementioned trifunctional polyether polyol (a4), from the perspective of obtaining superior adhesion, heat resistance, and hydrolysis resistance, a value of 300 to 50,000 is preferred, and more preferably 500 to 10,000. It should be noted that the number-average molecular weight of the aforementioned trifunctional polyether polyol (a4) represents a value determined by gel permeation chromatography (GPC).

[0036] Regarding the amount of the trifunctional polyether polyol (a4) used, from the perspective of obtaining better adhesion, heat resistance and hydrolysis resistance, the total mass of the polyol (a) and the polyisocyanate (b) is preferably 1 to 10% by mass, more preferably 1 to 3% by mass.

[0037] The mass ratio of the difunctional polyether polyol (a3) ​​to the trifunctional polyether polyol (a4) [(a3) / (a4)] must be 10 / 1 to 10 / 4, preferably 10 / 1 to 10 / 2. By using both within this range, the resulting urethane prepolymer achieves a moderate intramolecular cross-linked structure, resulting in higher levels of heat resistance and hydrolysis resistance.

[0038] Regarding the aforementioned polyol (a), it contains (a1) to (a4) as essential components, and other polyols may also be used in combination as needed. Examples of these other polyols include polycaprolactone polyols, polyester polyols other than (a1) and (a2), polyether polyols other than (a3) ​​and (a4), polyacrylic acid polyols, and polybutadiene polyols. These polyols may be used alone or in combination of two or more. Polycarbonate polyols are preferably not used as other polyols. Reasons for this include their higher price compared to polyether polyols, their tendency to promote compatibility between polyols, and their delayed crystallinity.

[0039] Regarding the polyisocyanate (b) mentioned above, in order to obtain excellent adhesion, heat resistance and hydrolysis resistance, it must contain diisocyanate (b1) and isocyanurate compound (b2).

[0040] As the aforementioned diisocyanate (b1), for example, aromatic diisocyanates such as diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, phenyl diisocyanate, toluene diisocyanate, and naphthalene diisocyanate, as well as aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and tetramethylphenylmethane diisocyanate can be used. These polyisocyanates can be used alone or in combination of two or more. Among these, aromatic polyisocyanates are preferred from the viewpoint of obtaining better reactivity and adhesion, and diphenylmethane diisocyanate is more preferred.

[0041] Regarding the amount of diisocyanate (b1) used, from the perspective of obtaining better adhesion, heat resistance and hydrolysis resistance, the total mass of the polyol (a) and the polyisocyanate (b) is preferably 10 to 30% by mass, more preferably 15 to 25% by mass.

[0042] As the aforementioned isocyanurate compound (b2), for example, the isocyanurate form of the aforementioned diisocyanate (b1) can be used. Regarding the diisocyanate used as a raw material, from the viewpoint of obtaining better adhesion, heat resistance and hydrolysis resistance, an aliphatic diisocyanate is preferred, and hexamethylene diisocyanate is more preferred.

[0043] Regarding the amount of the aforementioned isocyanurate compound (b2) used, from the perspective of obtaining better adhesion, heat resistance and hydrolysis resistance, the total mass of the aforementioned polyol (a) and the aforementioned polyisocyanate (b) is preferably 1 to 10% by mass, more preferably 3 to 8% by mass.

[0044] Regarding the mass ratio of the diisocyanate (b1) to the isocyanurate compound (b2) [(b1) / (b2)], from the viewpoint of obtaining better adhesion, heat resistance and hydrolysis resistance, it is preferably 10 / 1 to 10 / 5, and more preferably 10 / 2 to 10 / 3.

[0045] The aforementioned polyisocyanate (b) uses (b1) and (b2) as essential components, and may also contain other polyisocyanates as needed. Examples of these other polyisocyanates include adducts of the aforementioned diisocyanate (b1), biuret forms, etc. These polyisocyanates can be used alone or in combination of two or more. Regarding the aforementioned other polyisocyanates, polymethylene polyphenyl polyisocyanates are preferably not used because their heat resistance is reduced.

[0046] The above-mentioned urethane prepolymer is a substance obtained by reacting the above-mentioned polyol (a) with the above-mentioned polyisocyanate (b), and has isocyanate groups that can react with moisture present in the air or in the substrate to which the urethane prepolymer is to be coated to form a cross-linked structure.

[0047] As a method for manufacturing the above-mentioned urethane prepolymer, it can be manufactured, for example, by adding a mixture of the above-mentioned polyol (a) dropwise into a reaction vessel containing the above-mentioned polyisocyanate (b) and heating it, and reacting under the condition that the isocyanate groups of the above-mentioned polyisocyanate (b) are in excess relative to the hydroxyl groups of the above-mentioned polyol (a).

[0048] Regarding the molar ratio (NCO / OH) of the hydroxyl groups in the polyol (a) and the isocyanate groups in the polyisocyanate (b) during the manufacture of the above-mentioned urethane prepolymer, from the viewpoint of obtaining better adhesion, heat resistance and hydrolysis resistance, it is preferably 1.5 to 7, more preferably 1.8 to 3.

[0049] Regarding the isocyanate group content (hereinafter referred to as "NCO%)" of the urethane prepolymer obtained by the above method, from the viewpoint of obtaining better adhesion, heat resistance and hydrolysis resistance, it is preferably 1 to 10% by mass, more preferably 2 to 5% by mass. It should be noted that the NCO% of the above urethane prepolymer represents the value obtained by potentiometric titration according to JIS K1603-1:2007.

[0050] The moisture-curing polyurethane hot melt resin composition of the present invention contains the above-mentioned urethane prepolymer, and may also contain other additives as needed.

[0051] Other additives mentioned above may include, for example, curing catalysts, antioxidants, tackifiers, plasticizers, light stabilizers, fillers, dyes, pigments, defoamers, fluorescent whitening agents, silane coupling agents, waxes, thermoplastic resins, etc. These additives may be used alone or in combination of two or more.

[0052] The following is a description of the item.

[0053] Regarding the aforementioned items, at least two items were bonded together using an adhesive containing the aforementioned moisture-curing polyurethane hot melt resin composition.

[0054] For the aforementioned items to be bonded, wood-based substrates such as sheet wood, engineered wood, plywood, MDF (medium-density fiberboard), and particleboard can be used; inorganic substrates such as hard cement calcium silicate board; resin sheets; glass; rubber; molded plastics; decorative paper, non-woven fabric, woven fabric, veneer; tatami mats, etc.

[0055] The adhesive layer can be appropriately determined as long as sufficient adhesion can be obtained; for example, a range of 0.03 to 0.15 mm can be listed.

[0056] As described above, the moisture-curing polyurethane hot melt resin composition of the present invention has excellent heat resistance and hydrolysis resistance.

[0057] Therefore, the moisture-curing polyurethane hot melt resin composition of the present invention is suitable for use as an adhesive for bonding decorative panels. Furthermore, the resulting decorative panels are suitable for use in flooring; doors such as shoe cabinet doors, wardrobe doors, and kitchen doors; decorative materials such as frames, picture frames, and baseboards; and top panels such as bar tables and furniture tops.

[0058] Example

[0059] The present invention will be described in more detail below using examples.

[0060] [Example 1]

[0061] In a four-necked flask equipped with a stirrer, thermometer, inert gas inlet, and reflux condenser, add 10 parts by weight of crystalline aliphatic polyester polyol 1 (based on 1,6-hexanediol and adipic acid, number average molecular weight: 4500), 10 parts by weight of crystalline aliphatic polyester polyol 2 (based on 1,6-hexanediol and dodecanoic acid, number average molecular weight: 3500), 20 parts by weight of aromatic polyester polyol 1 (based on ethylene glycol, neopentyl glycol, terephthalic acid, and isophthalic acid, number average molecular weight: 2600), 15 parts by weight of polypropylene glycol (number average molecular weight: 2000), and 2 parts by weight of trifunctional polypropylene glycol (the reaction product of glycerol and propylene oxide, number average molecular weight: 700). Heat under reduced pressure at 90°C to dehydrate until the moisture content is below 0.05% by weight.

[0062] Subsequently, the temperature inside the reaction vessel was cooled to 60°C, and then 13 parts by mass of 4,4'-diphenylmethane diisocyanate (hereinafter referred to as "MDI") and 3.3 parts by mass of the isocyanurate body of hexamethylene diisocyanate (hereinafter referred to as "HDI-N") were added. The temperature was raised to 110°C, and the reaction was carried out for about 3 hours until the isocyanate group content became constant, thus obtaining a urethane prepolymer with isocyanate groups (1).

[0063] [Example 2]

[0064] In a four-necked flask equipped with a stirrer, thermometer, inactive gas inlet and reflux condenser, add 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 heat under reduced pressure at 90°C to dehydrate to a moisture content of less than 0.05% by mass.

[0065] Subsequently, the temperature inside 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 reaction was carried out for about 3 hours until the isocyanate group content became constant, thus obtaining a urethane prepolymer with isocyanate groups (2).

[0066] [Example 3]

[0067] In a four-necked flask equipped with a stirrer, thermometer, inert gas inlet, and reflux condenser, add 10 parts by weight of crystalline aliphatic polyester polyol 1, 10 parts by weight of crystalline aliphatic polyester polyol 2, 20 parts by weight of aromatic polyester polyol 1, 15 parts by weight of polypropylene glycol, and 6 parts by weight of trifunctional polypropylene glycol (number average molecular weight: 3000). Heat under reduced pressure at 90°C to dehydrate to a moisture content of less than 0.05% by weight.

[0068] Subsequently, the temperature inside the reaction vessel was cooled to 60°C, and then 12.5 parts by mass of MDI and 3.1 parts by mass of HDI-N were added. The temperature was raised to 110°C and the reaction was carried out for about 3 hours until the isocyanate group content became constant, thus obtaining a urethane prepolymer with isocyanate groups (3).

[0069] [Comparative Example 1]

[0070] In a four-necked flask equipped with a stirrer, thermometer, inactive gas inlet and reflux condenser, add 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 heat under reduced pressure at 90°C to dehydrate to a moisture content of less than 0.05% by mass.

[0071] Subsequently, the temperature inside the reaction vessel was cooled to 60°C, and then 13 parts by mass of MDI were added. The temperature was then raised to 110°C, and the reaction was carried out for about 3 hours until the isocyanate group content became constant, thus obtaining a urethane prepolymer (R1) with isocyanate groups.

[0072] [Comparative Example 2]

[0073] In a four-necked flask equipped with a stirrer, thermometer, inactive gas inlet and reflux condenser, add 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 heat under reduced pressure at 90°C to dehydrate to a moisture content of less than 0.05% by mass.

[0074] Subsequently, the temperature inside 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. The temperature was then raised to 110°C, and the reaction was carried out for about 3 hours until the isocyanate group content became constant, thus obtaining a urethane prepolymer (R2) with isocyanate groups.

[0075] [Comparative Example 3]

[0076] In a four-necked flask equipped with a stirrer, thermometer, inactive gas inlet and reflux condenser, add 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 heat under reduced pressure at 90°C to dehydrate to a moisture content of less than 0.05% by mass.

[0077] Subsequently, the temperature inside 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 then raised to 110°C and the reaction was carried out for about 3 hours until the isocyanate group content became constant, thus obtaining a urethane prepolymer (R3) with isocyanate groups.

[0078] [Methods for determining number-average molecular weight]

[0079] The number-average molecular weights of the polyols used in the examples and comparative examples are values ​​obtained by gel permeation chromatography (GPC) under the following conditions.

[0080] Measurement apparatus: High-speed GPC device (Tosoh Corporation "HLC-8220GPC")

[0081] Columns: The following columns manufactured by Tosoh Corporation are connected in series.

[0082] "TSKgel G5000" (7.8mm I.D. × 30cm) × 1 stick

[0083] "TSKgel G4000" (7.8mm I.D. × 30cm) × 1 stick

[0084] "TSKgel G3000" (7.8mm I.D. × 30cm) × 1 stick

[0085] "TSKgel G2000" (7.8mm I.D. × 30cm) × 1 stick

[0086] Detector: RI (Differential Refractometer)

[0087] Column temperature: 40℃

[0088] Eluent: Tetrahydrofuran (THF)

[0089] Flow rate: 1.0 mL / min

[0090] Injection volume: 100 μL (0.4% by mass tetrahydrofuran solution of sample concentration)

[0091] Standard test specimen: Calibration lines were made using the following standard polystyrene.

[0092] (Standard polystyrene)

[0093] TSKgel Standard Polystyrene A-500 manufactured by Tosoh Corporation

[0094] TSKgel Standard Polystyrene A-1000 manufactured by Tosoh Corporation

[0095] TSKgel Standard Polystyrene A-2500 manufactured by Tosoh Corporation

[0096] TSKgel Standard Polystyrene A-5000 manufactured by Tosoh Corporation

[0097] "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation

[0098] TSKgel Standard Polystyrene F-2 manufactured by Tosoh Corporation

[0099] TSKgel Standard Polystyrene F-4 manufactured by Tosoh Corporation

[0100] TSKgel Standard Polystyrene F-10 manufactured by Tosoh Corporation

[0101] TSKgel Standard Polystyrene F-20 manufactured by Tosoh Corporation

[0102] TSKgel Standard Polystyrene F-40 manufactured by Tosoh Corporation

[0103] TSKgel Standard Polystyrene F-80 manufactured by Tosoh Corporation

[0104] TSKgel Standard Polystyrene F-128 manufactured by Tosoh Corporation

[0105] TSKgel Standard Polystyrene F-288 manufactured by Tosoh Corporation

[0106] TSKgel Standard Polystyrene F-550 manufactured by Tosoh Corporation

[0107] [Evaluation methods for heat resistance]

[0108] The moisture-curing polyurethane hot-melt resin compositions obtained in the examples and comparative examples were heated to a molten state at 120°C and coated onto polyethylene terephthalate (PET) sheets to a thickness of 50 μm. MDF (medium-density fiberboard) was then placed on the coated surface and bonded together, and the mixture was placed at 23°C and 50% humidity for 5 days. Afterward, it was placed in a dryer at 80°C, and a load of 500 g / inch was applied along a 90° direction. The movement distance after 24 hours was measured and evaluated as follows.

[0109] “T”: less than 5mm.

[0110] “F”: 5mm or more.

[0111] [Evaluation method for hydrolysis resistance]

[0112] The moisture-curing polyurethane hot-melt resin compositions obtained in the examples and comparative examples were heated to a molten state at 120°C and coated onto polyethylene terephthalate (PET) sheets to a thickness of 50 μm. MDF (medium-density fiberboard) was then placed on the coated surface and bonded together, and the mixture was placed at 23°C and 50% humidity for 5 days. Afterward, the mixture was placed in a constant temperature and humidity chamber at 85°C and 85% humidity, and a load of 70°C was applied along a 90° direction. The number of days required for the PET sheet to peel off 40 mm was measured, and the results were evaluated as follows.

[0113] "T": More than 30 days.

[0114] “F”: less than 30 days.

[0115]

[0116] It is known that the moisture-curing polyurethane hot melt resin composition of the present invention has excellent heat resistance and hydrolysis resistance.

[0117] On the other hand, Comparative Example 1, which did not use trifunctional polyether polyol (a4) and isocyanurate compound (b2), showed poor hydrolysis resistance.

[0118] Comparative Example 2, which did not use trifunctional polyether polyol (a4), showed poor hydrolysis resistance.

[0119] Comparative Example 3, which did not use trifunctional polyether polyol (a4) and further used polymethylene polyphenyl polyisocyanate to replace isocyanurate compound (b2), had poor heat resistance.

Claims

1. A moisture-curing polyurethane hot melt resin composition, characterized in that, It contains a urethane prepolymer with isocyanate groups, which is the product of the reaction between a polyol (a) and a polyisocyanate (b). The polyol (a) contains crystalline aliphatic polyester polyol (a1), aromatic polyester polyol (a2), difunctional polyether polyol (a3) ​​and trifunctional polyether polyol (a4). The mass ratio of the difunctional polyether polyol (a3) ​​to the trifunctional polyether polyol (a4) (a3) / (a4) is 10 / 1 to 10 / 4. The polyisocyanate (b) contains diisocyanate (b1) and isocyanurate compound (b2).

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

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

4. An adhesive, characterized in that, It contains the moisture-curing polyurethane hot melt resin composition as described in claim 1.

5. An article having an adhesive portion based on the adhesive of claim 4.

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