Moisture-curing hot melt adhesive

Abstract

To provide a moisture-curable hot-melt adhesive which is excellent in resin adhesiveness and wet heat adhesiveness.SOLUTION: A moisture-curable hot-melt adhesive contains crystalline polyester polyol which is a condensation polymer of a polycarboxylic acid having predetermined carbon atoms and polyol having predetermined carbon atoms, microcrystalline polyester polyol having a predetermined number average molecular weight, amorphous polyester polyol having a predetermined number average molecular weight and polyol containing polyether polyol having a predetermined number average molecular weight, and an urethane prepolymer that is a reactant with a polyisocyanate compound and has an isocyanate group at a terminal, wherein the polyol contains the crystalline polyester polyol, the microcrystalline polyester polyol, the amorphous polyester polyol and the polyester polyol each in prescribed amounts.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a moisture-curable hot melt adhesive. [Background technology]

[0002] 2. Description of the Related Art Conventionally, decorative sheets have been attached to the surfaces of substrates such as furniture, exterior materials, and interior materials using moisture-curing hot melt adhesives to impart design features.

[0003] 2. Description of the Related Art Wood has traditionally been used widely as a base material for interior materials and the like, but in recent years, synthetic resin base materials have increasingly been used instead of wood.

[0004] Patent Document 1 discloses a moisture-curing polyurethane hot melt resin composition containing a urethane prepolymer having an isocyanate group, which is a reaction product of a polyol (a) and an isocyanate compound (b), in which the polyol (a) contains an alicyclic polycarbonate polyol (a-1), a crystalline polyester polyol (a-2), and a polyether polyol (a-3), and the isocyanate compound (b) contains a diisocyanate (b-1), a polymethylene polyphenyl isocyanate compound (b-2), and an isocyanurate compound (b-3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-97653 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the moisture-curable hot melt adhesive has a problem in that it has low adhesiveness to substrates made of synthetic resins.

[0007] Furthermore, in recent years, a decorative sheet has been bonded to a base material used in the plumbing area such as a bathroom using a moisture-curing hot melt adhesive. However, the moisture-curing hot melt adhesive has a problem that its water resistance (wet heat adhesiveness) is low under high humidity and high temperature, and the decorative sheet peels off from the base material during use.

[0008] The present invention provides a moisture-curing hot melt adhesive that is excellent in adhesiveness (resin adhesiveness) to a base material made of synthetic resin and can maintain excellent adhesiveness (wet heat adhesiveness) even when used in an atmosphere where humidity is likely to be high under high temperature.

Means for Solving the Problems

[0009] The moisture-curing hot melt adhesive of the present invention contains a urethane prepolymer that is a reaction product of a polyol and a polyisocyanate compound and has an isocyanate group at its terminal, the above polyol includes a first polyol containing a microcrystalline polyester polyol having a number average molecular weight of 3000 to 6000 and a liquid polyester polyol having a number average molecular weight of 1000 to 6000, and at least one second polyol selected from the group consisting of a polyether polyol having a number average molecular weight of 500 to 7000 and a castor oil polyol, the above polyisocyanate compound includes a first polyisocyanate compound containing a diisocyanate and a polymethylene polyphenyl isocyanate, and at least one second polyisocyanate compound selected from the group consisting of an isocyanurate compound and a biuret-type polyisocyanate.

Effects of the Invention

[0010] The moisture-curing hot melt adhesive of the present invention has excellent adhesiveness to a base material made of synthetic resin and maintains excellent adhesiveness even when used in an atmosphere where humidity is likely to be high.

Modes for Carrying Out the Invention

[0011] The moisture-curing hot melt adhesive of the present invention contains a urethane prepolymer which is a reaction product of a polyol containing a predetermined polyol and a predetermined polyisocyanate compound and has an isocyanate group at its terminal. The urethane prepolymer undergoes a crosslinking reaction due to moisture contained in the air and / or the substrate and cures.

[0012] The reaction between the polyol and the polyisocyanate compound may be carried out in a general manner. For example, it can be obtained by charging the polyisocyanate compound into a reaction vessel, dropping the polyol from which moisture has been removed in advance separately or after mixing it including additives, etc., and reacting the hydroxyl group and the isocyanate group under a heated state. Alternatively, the polyol, additives, etc. can be charged into the reaction vessel, heated and melted for dispersion, then moisture is removed, and thereafter, the polyisocyanate compound is charged to carry out the reaction between the hydroxyl group and the isocyanate group. The production of the urethane prepolymer can usually be carried out without a solvent, but it can also be carried out in a solvent that does not inhibit the reaction. Specific examples of the solvent include, for example, butyl acetate, methyl ethyl ketone, toluene, etc. In the reaction between the hydroxyl group of the polyol and the isocyanate group of the polyisocyanate compound, a urethanization catalyst can be used as necessary. The urethanization catalyst is not particularly limited, and examples include triethylamine, triethylenediamine, N-methylmorpholine, potassium acetate, zinc stearate, tin octylate, dibutyltin dilaurate, etc. The urethane catalyst may be used alone or in combination of two or more.

[0013] In the reaction between the polyol and the polyisocyanate compound, the ratio of the number of moles of the hydroxyl group in the polyol to the number of moles of the isocyanate group in the polyisocyanate compound (number of moles of isocyanate group / number of moles of hydroxyl group) is preferably 1.3 to 4.0, and more preferably 1.5 to 3.0. When the molar ratio is 1.5 or more, the coatability of the moisture-curing hot melt adhesive is improved. When the molar ratio is 3.0 or less, the resin adhesiveness of the moisture-curing hot melt adhesive is improved.

[0014] [Polyol] The urethane prepolymer contained in the moisture-curing hot melt adhesive is a reaction product of a polyol (A) containing a predetermined polyol and a polyisocyanate compound (B). The urethane prepolymer has an isocyanate group at the molecular terminal, and preferably has isocyanate groups at both molecular terminals.

[0015] The polyol (A) contains a first polyol including a crystalline polyester polyol (A1) and a liquid polyester polyol (A2) described later, and at least one second polyol selected from the group consisting of a polyether polyol (A3) and a castor oil polyol (A6).

[0016] The polyol (A) contains a crystalline polyester polyol (A1) and a liquid polyester polyol (A2) as essential components, and includes either or both of a polyether polyol (A3) and a castor oil polyol (A6).

[0017] The polyol (A) may further contain a crystalline polyester polyol (A4) and a polycarbonate polyol (A5).

[0018] In the polyol (A), the total amount of the crystalline polyester polyol (A1), the liquid polyester polyol (A2), and the second polyol is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, and most preferably 100% by mass.

[0019] In the polyol (A), the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4), and the polycarbonate polyol (A5) is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, yet more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0020] [First Polyol] The first polyol contains a microcrystalline polyester polyol (A1) and a liquid polyester polyol (A2).

[0021] [Microcrystalline Polyester Polyol (A1)] The polyol (A) contains a microcrystalline polyester polyol (A1) having a number average molecular weight of 3000 to 6000 (hereinafter sometimes simply referred to as "microcrystalline polyester polyol (A1)"). The microcrystalline polyester polyol (A1) is a condensation polymer of a polycarboxylic acid and a polyol. That is, the microcrystalline polyester polyol (A1) is a polymer obtained by subjecting a polycarboxylic acid and a polyol to an ester reaction at the carboxyl group of the polycarboxylic acid and the hydroxyl group of the polyol to cause condensation polymerization.

[0022] The polycarboxylic acid is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylenedicarboxylic acid, dodecamethylenedicarboxylic acid, etc. Adipic acid and terephthalic acid are preferred, and adipic acid is more preferred. The polycarboxylic acid may be used alone or in combination of two or more.

[0023] The polyol is not particularly limited, and examples thereof include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, diethylene glycol, cyclohexanediol, etc. Among them, 1,6-hexanediol and ethylene glycol are preferred, and 1,6-hexanediol is more preferred. The polyol may be used alone or in combination of two or more.

[0024] The polyester polyol (A1) is microcrystalline. The microcrystalline polyester polyol (A1) is a polyester polyol having an endothermic amount (hereinafter sometimes simply referred to as "endothermic amount") of the melting curve measured at a heating rate of 10 ° C. / min in the differential scanning calorimetry (DSC) defined in JIS K7121 of 2.5 cal / g (10 J / g) or more and less than 10 cal / g (40 J / g).

[0025] The number average molecular weight of the microcrystalline polyester polyol (A1) is 3000 or more, preferably 3500 or more, and more preferably 4000 or more. The number average molecular weight of the microcrystalline polyester polyol (A1) is 6000 or less, preferably 5000 or less, and more preferably 4800 or less. When the number average molecular weight of the microcrystalline polyester polyol (A1) is 3000 or more, the resin adhesiveness of the moisture-curing hot melt adhesive is improved. When the number average molecular weight of the microcrystalline polyester polyol (A1) is 6000 or less, the coatability of the moisture-curing hot melt adhesive is improved.

[0026] In the present invention, the number average molecular weight of the polyol refers to the value measured in the following manner. The number average molecular weight of the polyol can be measured using the gel permeation chromatography (GPC) method. Specifically, a sample solution is prepared by dissolving the sample in tetrahydrofuran (THF) so as to have a concentration of 1.0% by mass. Using this sample solution, the number average molecular weight of the polyol is measured by the GPC method using a refractive index detector with reference to standard polystyrene.

[0027] As the measuring device, for example, a system (all manufactured by Shimadzu Corporation) consisting of an LC-9A liquid feeder, an RID-6A refractive index detector, a CTO-6A column oven, and a C-R4A data analysis device can be used. As the GPC column, for example, three GPC-805s (exclusion limit: 4 million) and one GPC-804 (exclusion limit: 400,000) (all manufactured by Shimadzu Corporation) can be connected in this order and used. Also, the measurement conditions are a sample injection volume of 25 μL (liter), an eluent of tetrahydrofuran (THF), a liquid feeding rate of 1.0 mL / min, and a column temperature of 45°C.

[0028] The hydroxyl value of the microcrystalline polyester polyol (A1) is preferably 20 mgKOH / g or more, more preferably 21 mgKOH / g or more, still more preferably 22 mgKOH / g or more, and even more preferably 23 mgKOH / g or more. The hydroxyl value of the microcrystalline polyester polyol (A1) is preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less, still more preferably 35 mgKOH / g or less, and even more preferably 30 mgKOH / g or less. When the hydroxyl value of the microcrystalline polyester polyol (A1) is 20 mgKOH / g or more, it is preferable because the resin adhesiveness of the moisture-curable hot melt adhesive is improved. When the hydroxyl value of the microcrystalline polyester polyol (A1) is 50 mgKOH / g or less, the resin adhesiveness of the moisture-curable hot melt adhesive is improved.

[0029] In the present invention, the hydroxyl value of the polyol means the number of milligrams of potassium hydroxide required to neutralize acetic acid bonded to the hydroxyl group when 1 g of the polyol is acetylated (JIS K0070:1992 2.1(5)). Specifically, it can be measured by acetylating the hydroxyl groups in the polyol with acetic anhydride and then titrating the unused acetic anhydride with potassium hydroxide (JIS K0070:1992 3.1 (neutralization titration method)).

[0030] In the polyol (A), the content of the microcrystalline polyester polyol (A1) is preferably 20% by mass or more, more preferably 25% by mass or more, and still more preferably 30% by mass or more. In the polyol (A), the content of the microcrystalline polyester polyol (A1) is preferably 50% by mass or less, more preferably 48% by mass or less, and still more preferably 45% by mass or less. When the content of the microcrystalline polyester polyol (A1) is 20% by mass or more, the resin adhesiveness of the moisture-curing hot melt adhesive is improved. When the content of the microcrystalline polyester polyol (A1) is 50% by mass or less, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved.

[0031] When the polyol (A) further contains a crystalline polyester polyol (A4) and / or a polycarbonate polyol (A5), in the polyol (A), the content of the microcrystalline polyester polyol (A1) is preferably 20% by mass or more, more preferably 25% by mass or more, and still more preferably 30% by mass or more when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass. The content of the microcrystalline polyester polyol (A1) is preferably 50% by mass or less, more preferably 48% by mass or less, and still more preferably 45% by mass or less when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass. When the content of the microcrystalline polyester polyol (A1) is 20% by mass or more, the resin adhesiveness of the moisture-curing hot melt adhesive is improved. When the content of the microcrystalline polyester polyol (A1) is 50% by mass or less, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved.

[0032] [Liquid polyester polyol (A2)] The polyol (A) is preferably a liquid polyester polyol (A2) having a number average molecular weight of 1,000 to 6,000 (hereinafter sometimes simply referred to as "liquid polyester polyol"), which is a condensation polymer of a polycarboxylic acid and a polyol. That is, the liquid polyester polyol (A2) is preferably a polymer obtained by subjecting a polycarboxylic acid and a polyol to an esterification reaction at the carboxyl group of the polycarboxylic acid and the hydroxyl group of the polyol to cause condensation polymerization.

[0033] The polycarboxylic acid is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, phthalic anhydride, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylenedicarboxylic acid, dodecamethylenedicarboxylic acid, etc. Adipic acid, sebacic acid, isophthalic acid, terephthalic acid, and phthalic anhydride are preferred, and it is more preferred to contain adipic acid, sebacic acid, and isophthalic acid, or to contain adipic acid, terephthalic acid, and phthalic anhydride. The polycarboxylic acid may be used alone or in combination of two or more.

[0034] The polyol is not particularly limited, and examples thereof include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, diethylene glycol, cyclohexanediol, etc. Ethylene glycol, neopentyl glycol, and 1,6-hexanediol are preferred, it is more preferred to contain ethylene glycol, and it is preferred to contain ethylene glycol, neopentyl glycol, and 1,6-hexanediol. The polyol may be used alone or in combination of two or more.

[0035] The liquid polyester polyol (A2) is a liquid at 1 atm (1.013×10 5 Pa) and 20°C.

[0036] The number average molecular weight of the liquid polyester polyol (A2) is 1000 or more, preferably 2000 or more, more preferably 2200 or more, still more preferably 2700 or more, and even more preferably 2800 or more. The number average molecular weight of the liquid polyester polyol (A2) is 6000 or less, more preferably 5000 or less, still more preferably 4000 or less, and even more preferably 3800 or less. When the number average molecular weight of the liquid polyester polyol (A2) is 1000 or more, the resin adhesiveness of the moisture-curing hot melt adhesive is improved. When the number average molecular weight of the liquid polyester polyol (A2) is 6000 or less, the coatability of the moisture-curing hot melt adhesive is improved.

[0037] The hydroxyl value of the liquid polyester polyol (A2) is preferably 20 mgKOH / g or more, more preferably 21 mgKOH / g or more, and still more preferably 22 mgKOH / g or more. The hydroxyl value of the liquid polyester polyol (A2) is preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less, and still more preferably 38 mgKOH / g or less. When the hydroxyl value of the liquid polyester polyol (A3) is 20 mgKOH / g or more, the resin adhesiveness of the moisture-curing hot melt adhesive is improved. When the hydroxyl value of the liquid polyester polyol (A3) is 50 mgKOH / g or less, the resin adhesiveness of the moisture-curing hot melt adhesive is improved.

[0038] In the polyol (A), the content of the liquid polyester polyol (A2) is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and even more preferably 25% by mass or more. In the polyol (A), the content of the liquid polyester polyol (A2) is preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less, and even more preferably 38% by mass or less. When the content of the liquid polyester polyol (A2) is 10% by mass or more, the resin adhesiveness of the moisture-curable hot melt adhesive is improved. When the content of the liquid polyester polyol (A2) is 50% by mass or less, the wet heat adhesiveness of the moisture-curable hot melt adhesive is improved.

[0039] When the polyol (A) further contains a crystalline polyester polyol (A4) and / or a polycarbonate polyol (A5), in the polyol (A), the content of the liquid polyester polyol (A2) is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and even more preferably 25% by mass or more when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass. In the polyol (A), the content of the liquid polyester polyol (A2) is preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less, and even more preferably 38% by mass or less when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass. When the content of the liquid polyester polyol (A2) is 10% by mass or more, the resin adhesiveness of the moisture-curable hot melt adhesive is improved. When the content of the liquid polyester polyol (A2) is 50% by mass or less, the wet heat adhesiveness of the moisture-curable hot melt adhesive is improved.

[0040] [Second polyol] The second polyol contains at least one polyol selected from the group consisting of polyether polyol (A3) and castor oil polyol (A6) having a number average molecular weight of 500 to 7000.

[0041] [Polyether polyol (A3)] Polyol (A) contains polyether polyol (A3) having a number average molecular weight of 500 to 7000 (hereinafter sometimes simply referred to as "polyether polyol (A3)"). The polyether polyol (A3) is not particularly limited. As the polyether polyol (A3), (1) a polymer containing a repeating unit represented by the general formula: HO-(R 1 -O)p- (wherein R 1 represents an alkylene group having 1 to 14 carbon atoms, and p is the number of repeating units and is a positive integer), (2) a polyether polyol obtained by subjecting the active hydrogen portion of the bisphenol A molecular skeleton to an addition reaction with an alkylene oxide (for example, ethylene oxide, propylene oxide, butylene oxide, isobutylene oxide, etc.) is preferred. The main chain skeleton of the polyether polyol (A3) may consist of only one kind of repeating unit, may contain two or more kinds of repeating units, or may contain two or more kinds of polymer blocks. Note that the polyether polyol (A3) may be used alone or in combination of two or more.

[0042] In the present invention, the alkylene group is a divalent atomic group generated by removing two hydrogen atoms bonded to two different carbon atoms in an aliphatic saturated hydrocarbon, and includes both linear and branched atomic groups. Note that the branched form includes the case where one carbon (methyl group) is bonded as a side chain.

[0043] Examples of the alkylene group include an ethylene group, a propylene group [-CH(CH3)-CH2-], a trimethylene group [-CH2-CH2-CH2-], a butylene group, an amylene group [-(CH2)5-], a hexylene group, and the like.

[0044] The above general formula: HO-(R1 -O)p-] of the polymer containing the repeating unit represented by [-(R 1 Examples of [-O)p-] include polyethylene oxide, polypropylene oxide, polybutylene oxide, polytetramethylene oxide, polyethylene oxide-polypropylene oxide copolymer, and polypropylene oxide-polybutylene oxide copolymer. Among them, polypropylene oxide and polyethylene oxide-polypropylene oxide copolymer are preferred because the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved.

[0045] As the polyether polyol (A3), it is preferably contained a polypropylene triol represented by the following formula 1. In formula 1, R 4 , R 5 and R 6 each represent an alkylene group having 1 to 14 carbon atoms. R 4 , R 5 and R 6 may be the same as or different from each other. x, y, and z are each the number of repeating units and are positive integers.

[0046] Examples of the alkylene group include an ethylene group, a propylene group [-CH(CH3)-CH2-], a trimethylene group [-CH2-CH2-CH2-], a butylene group, an amylene group [-(CH2)5-], a hexylene group, and the like.

[0047]

Chemical formula

[0048] As the polyether polyol obtained by subjecting the active hydrogen portion of the bisphenol A molecular skeleton to an addition reaction with an alkylene oxide, since the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved, a polyether polyol obtained by subjecting the active hydrogen portion of the bisphenol A molecular skeleton to an addition reaction with propylene oxide and a polyether polyol obtained by subjecting the active hydrogen portion of the bisphenol A molecular skeleton to an addition reaction with ethylene oxide are preferred.

[0049] The number average molecular weight of the polyether polyol (A3) is 500 or more, preferably 600 or more, more preferably 650 or more, still more preferably 700 or more, still more preferably 750 or more, and still more preferably 760 or more. The number average molecular weight of the polyether polyol (A3) is 7000 or less, preferably 6000 or less, more preferably 5000 or less, still more preferably 4000 or less, still more preferably 3000 or less, still more preferably 2500 or less, still more preferably 2000 or less, and still more preferably 1500 or less. When the number average molecular weight of the polyether polyol (A3) is 500 or more, the resin adhesiveness of the moisture-curing hot melt adhesive is improved, which is preferable. When the number average molecular weight of the polyether polyol (A3) is 7000 or less, the coatability of the moisture-curing hot melt adhesive is improved.

[0050] The hydroxyl value of the polyether polyol (A3) is preferably 50 mgKOH / g or more, more preferably 80 mgKOH / g or more, and still more preferably 100 mgKOH / g or more. The hydroxyl value of the polyether polyol (A3) is preferably 200 mgKOH / g or less, more preferably 180 mgKOH / g or less, and still more preferably 170 mgKOH / g or less. When the hydroxyl value of the polyether polyol (A3) is 50 mgKOH / g or more, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. When the hydroxyl value of the polyether polyol (A3) is 200 mgKOH / g or less, the resin adhesiveness of the moisture-curing hot melt adhesive is improved.

[0051] In the polyol (A), the content of the polyether polyol (A3) is preferably 1% by mass or more, more preferably 1.1% by mass or more, still more preferably 1.2% by mass or more, and even more preferably 1.5% by mass or more. In the polyol (A), the content of the polyether polyol (A3) is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, and even more preferably 2.5% by mass or less. When the content of the polyether polyol (A3) is 1% by mass or more, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. When the content of the polyether polyol (A3) is 5% by mass or less, the resin adhesiveness of the moisture-curing hot melt adhesive is improved. Furthermore, the thermal stability of the moisture-curing hot melt adhesive is improved, and thickening during coating can be suppressed to improve the coatability.

[0052] When the polyol (A) further contains a crystalline polyester polyol (A4) and / or a polycarbonate polyol (A5), in the polyol (A), when the total amount of the polyether polyol (A3), the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass, the content of the polyether polyol (A3) is preferably 1% by mass or more, more preferably 1.1% by mass or more, still more preferably 1.2% by mass or more, and even more preferably 1.5% by mass or more. In the polyol (A), when the total amount of the polyether polyol (A3), the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass, the content of the polyether polyol (A3) is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, and even more preferably 2.5% by mass or less. When the content of the polyether polyol (A3) is 1% by mass or more, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. When the content of the polyether polyol (A3) is 5% by mass or less, the resin adhesiveness of the moisture-curing hot melt adhesive is improved, and further, the thermal stability of the moisture-curing hot melt adhesive is improved, and the thickening during coating can be suppressed to improve the coatability.

[0053] [castor oil polyol (A6)] Castor oil polyol is a polyol formed by the reaction of the carboxyl group of ricinoleic acid, which is a monocarboxylic acid, and the hydroxyl group of glycerin, and has a plurality of hydroxyl groups derived from the hydroxyl group of glycerin and / or ricinoleic acid in the molecule. Since castor oil polyol improves the wet heat adhesiveness, it preferably has an average of 2 to 3 hydroxyl groups in one molecule.

[0054] The number average molecular weight of the castor oil polyol (A6) is 500 or more, preferably 600 or more, more preferably 650 or more, still more preferably 700 or more, yet more preferably 750 or more, and even more preferably 760 or more. The number average molecular weight of the castor oil polyol (A6) is 7000 or less, preferably 6000 or less, more preferably 5000 or less, still more preferably 4000 or less, yet more preferably 3000 or less, even more preferably 2500 or less, still more preferably 2000 or less, and yet more preferably 1500 or less. When the number average molecular weight of the castor oil polyol (A6) is 500 or more, the resin adhesiveness of the moisture-curable hot melt adhesive is improved, which is preferable. When the number average molecular weight of the castor oil polyol (A6) is 7000 or less, the coatability of the moisture-curable hot melt adhesive is improved.

[0055] The hydroxyl value of the castor oil polyol (A6) is preferably 50 mgKOH / g or more, more preferably 80 mgKOH / g or more, and still more preferably 100 mgKOH / g or more. The hydroxyl value of the castor oil polyol (A6) is preferably 200 mgKOH / g or less, more preferably 180 mgKOH / g or less, and still more preferably 170 mgKOH / g or less. When the hydroxyl value of the castor oil polyol (A6) is 50 mgKOH / g or more, the wet heat adhesiveness of the moisture-curable hot melt adhesive is improved. When the hydroxyl value of the castor oil polyol (A6) is 200 mgKOH / g or less, the resin adhesiveness of the moisture-curable hot melt adhesive is improved.

[0056] In the polyol (A), the content of the castor oil polyol (A6) is preferably 1% by mass or more, more preferably 1.1% by mass or more, still more preferably 1.2% by mass or more, and even more preferably 1.5% by mass or more. In the polyol (A), the content of the castor oil polyol (A6) is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, and even more preferably 2.5% by mass or less. When the content of the castor oil polyol (A6) is 1% by mass or more, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. When the content of the castor oil polyol (A6) is 5% by mass or less, the resin adhesiveness of the moisture-curing hot melt adhesive is improved, and further, the thermal stability of the moisture-curing hot melt adhesive is improved, and thickening during coating can be suppressed to improve the coatability.

[0057] When the polyol (A) further contains a crystalline polyester polyol (A4) and / or a polycarbonate polyol (A5), in the polyol (A), when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass, the content of the castor oil polyol (A6) is preferably 1% by mass or more, more preferably 1.1% by mass or more, still more preferably 1.2% by mass or more, and even more preferably 1.5% by mass or more. In the polyol (A), when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass, the content of the castor oil polyol (A6) is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, and even more preferably 2.5% by mass or less. When the content of the castor oil polyol (A6) is 1% by mass or more, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. When the content of the castor oil polyol (A6) is 5% by mass or less, the resin adhesiveness of the moisture-curing hot melt adhesive is improved, and further, the thermal stability of the moisture-curing hot melt adhesive is improved, and thickening during coating can be suppressed to improve the coatability.

[0058] By the polyol (A) containing the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2) and the second polyol, both the resin adhesiveness and the wet heat adhesiveness of the moisture-curing hot melt adhesive are improved.

[0059] By using a combination of a predetermined microcrystalline polyester polyol (A1), a liquid polyester polyol (A2) and the second polyol, in the moisture-curing hot melt adhesive, both the resin adhesiveness and the wet heat adhesiveness are improved without impairing either the resin adhesiveness or the wet heat adhesiveness.

[0060] The polyol (A) may contain polyester polyols other than the microcrystalline polyester polyol (A1) and the liquid polyester polyol (A2), polycarbonate polyols, polyether polyols other than the polyether polyol (A3), and polyols such as polycaprolactone, within a range that does not impair the effects of the moisture-curing hot melt adhesive.

[0061] [Crystalline polyester polyol (A4)] The polyol (A) may contain a crystalline polyester polyol (A4). The crystalline polyester polyol (A4) is a condensation polymer of a polycarboxylic acid having 2 to 14 carbon atoms excluding the carbon in the carboxy group (-COOH) and a polyol having 2 to 8 carbon atoms. That is, the crystalline polyester polyol (A4) is a polymer obtained by causing an ester reaction to occur between a polycarboxylic acid having 2 to 14 carbon atoms excluding the carbon in the carboxy group and a polyol having 2 to 8 carbon atoms at the carboxyl group of the polycarboxylic acid and the hydroxyl group of the polyol, and then subjecting them to condensation polymerization. The condensation polymerization reaction between the polycarboxylic acid and the polyol may be carried out using a general method. Note that the number of carbon atoms excluding the carbon in the carboxy group as defined for the polycarboxylic acid refers to the number of carbon atoms obtained by subtracting the total number of carbon atoms in all carboxy groups from the total number of carbon atoms contained in the molecule.

[0062] In the polycarboxylic acid, the number of carbon atoms excluding the carbon in the carboxy group is preferably 2 or more, more preferably 10 or more. In the polycarboxylic acid, the number of carbon atoms excluding the carbon in the carboxy group is preferably 14 or less, more preferably 12 or less. When the number of carbon atoms excluding the carbon in the carboxy group is 2 or more, the crystallinity of the crystalline polyester polyol (A4) is improved, and the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved, which is preferable. When the number of carbon atoms excluding the carbon in the carboxy group is 14 or less, the resin adhesiveness of the moisture-curing hot melt adhesive is improved, which is preferable.

[0063] The polycarboxylic acid is preferably a divalent carboxylic acid (HOOC-R 2 -COOH). When it is a divalent carboxylic acid, the melt viscosity of the moisture-curing hot melt adhesive can be reduced. The number of carbon atoms of R 2 is preferably 2 or more, more preferably 10 or more. The number of carbon atoms of R 2 is preferably 14 or less, more preferably 12 or less. When the number of carbon atoms of R 2 is within the above range, the resin adhesiveness of the moisture-curing hot melt adhesive is improved.

[0064] R 2 is preferably an aliphatic chain, more preferably a straight-chain aliphatic chain. When R 2 is an aliphatic chain, the crystallinity of the crystalline polyester polyol (A4) is improved, and the resin adhesiveness of the moisture-curing hot melt adhesive is improved, which is preferable. When R 2 is straight-chain, the crystallinity of the crystalline polyester polyol (A4) is improved, and the resin adhesiveness of the moisture-curing hot melt adhesive is improved, which is preferable. That R 2 is straight-chain means that the carbons are linearly bonded without branching. R 2 is preferably a straight-chain alkylene group (-CnH2n-), where n is a natural number.

[0065] The polycarboxylic acid having 2 to 14 carbon atoms excluding the carbon in the carboxy group (-COOH) is not particularly limited, and examples thereof include sebacic acid, 1,12-dodecanedioic acid, decamethylene dicarboxylic acid (1,10-decanedicarboxylic acid), 1,14-tetradecanedicarboxylic acid, etc., and sebacic acid, 1,12-dodecanedioic acid, and decamethylene dicarboxylic acid are preferred. The polycarboxylic acid may be used alone or in combination of two or more.

[0066] The polyol preferably has 2 or more carbon atoms, more preferably 4 or more carbon atoms. The polyol preferably has 8 or less carbon atoms, more preferably 6 or less carbon atoms. When the polyol has 2 or more carbon atoms, the crystallinity of the crystalline polyester polyol (A4) is improved, and the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. When the polyol has 8 or less carbon atoms, the resin adhesiveness of the moisture-curing hot melt adhesive is improved.

[0067] The polyol is preferably a divalent alcohol (HO-R 3 -OH). When it is a divalent alcohol, the melt viscosity of the moisture-curing hot melt adhesive can be reduced. The carbon number of R 3 is preferably 2 or more, more preferably 4 or more. The carbon number of R 3 is preferably 8 or less, more preferably 6 or less. When the carbon number of R 3 is within the above range, the resin adhesiveness of the moisture-curing hot melt adhesive is improved.

[0068] R 3 is preferably an aliphatic chain, more preferably a straight-chain aliphatic chain. When R 3 is an aliphatic chain, the crystallinity of the crystalline polyester polyol (A4) is improved, and the resin adhesiveness of the moisture-curing hot melt adhesive is improved, which is preferable. When R 3 is straight-chain, the crystallinity of the crystalline polyester polyol (A4) is improved, and the resin adhesiveness of the moisture-curing hot melt adhesive is improved, which is preferable. R 3 being straight-chain means that the carbon atoms are bonded linearly without branching. R 3A linear alkylene group (-CmH2m-) is preferred. However, m is a natural number. m is preferably an even number because the crystallinity of the crystalline polyester polyol (A4) is improved and the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved.

[0069] The polyol having 2 to 8 carbon atoms is not particularly limited, and examples thereof include 1,2-ethanediol (ethylene glycol), 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, etc. 1,6-Hexanediol and 1,2-ethanediol (ethylene glycol) are preferred, and 1,6-hexanediol is more preferred. The polyol may be used alone or in combination of two or more.

[0070] The crystalline polyester polyol (A4) is crystalline. The crystalline polyester polyol is a polyester polyol having an endothermic amount of the melting curve measured at a heating rate of 10 ° C. / min in the differential scanning calorimetry (DSC) defined in JIS K7121 of 10 cal / g (40 J / g) or more.

[0071] The number average molecular weight of the crystalline polyester polyol (A4) is preferably 1000 or more, more preferably 1500 or more, more preferably 1800 or more, more preferably 2000 or more, more preferably 2500 or more, more preferably 2800 or more, and more preferably 2900 or more. The number average molecular weight of the crystalline polyester polyol (A4) is preferably 20000 or less, more preferably 10000 or less, more preferably 7000 or less, more preferably 6000 or less, more preferably 5000 or less, more preferably 4500 or less, more preferably 4000 or less, and more preferably 3500 or less. When the number average molecular weight of the crystalline polyester polyol (A4) is 1000 or more, the resin adhesiveness of the moisture-curing hot melt adhesive is improved. When the number average molecular weight of the crystalline polyester polyol (A4) is 20000 or less, the coatability of the moisture-curing hot melt adhesive is improved.

[0072] The hydroxyl value of the crystalline polyester polyol (A4) is preferably 20 mgKOH / g or more, more preferably 25 mgKOH / g or more, and even more preferably 30 mgKOH / g or more. The hydroxyl value of the crystalline polyester polyol (A4) is preferably 50 mgKOH / g or less, more preferably 45 mgKOH / g or less, even more preferably 40 mgKOH / g or less, and even more preferably 35 mgKOH / g or less. When the hydroxyl value of the crystalline polyester polyol (A4) is 20 mgKOH / g or more, the resin adhesiveness of the moisture-curable hot melt adhesive is improved. When the hydroxyl value of the crystalline polyester polyol (A4) is 50 mgKOH / g or less, the resin adhesiveness of the moisture-curable hot melt adhesive is improved.

[0073] In the polyol (A), the content of the crystalline polyester polyol (A4) is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, and even more preferably 20% by mass or more. In the polyol (A), the content of the crystalline polyester polyol (A4) is preferably 35% by mass or less, more preferably 33% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less. When the content of the crystalline polyester polyol (A4) is 1% by mass or more, the resin adhesiveness of the moisture-curable hot melt adhesive is improved. When the content of the crystalline polyester polyol (A4) is 35% by mass or less, the resin adhesiveness of the moisture-curable hot melt adhesive is improved.

[0074] When the polyol (A) further contains a crystalline polyester polyol (A4) and / or a polycarbonate polyol (A5), in the polyol (A), when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4), and the polycarbonate polyol (A5) is 100% by mass, the content of the crystalline polyester polyol (A4) is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, yet more preferably 15% by mass or more, and even more preferably 20% by mass or more. In the polyol (A), when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4), and the polycarbonate polyol (A5) is 100% by mass, the content of the crystalline polyester polyol (A4) is preferably 35% by mass or less, more preferably 33% by mass or less, still more preferably 30% by mass or less, and yet more preferably 25% by mass or less. When the content of the crystalline polyester polyol (A4) is 1% by mass or more, the resin adhesiveness of the moisture-curable hot-melt adhesive is improved. When the content of the crystalline polyester polyol (A4) is 35% by mass or less, the resin adhesiveness of the moisture-curable hot-melt adhesive is improved.

[0075] [Polycarbonate polyol (A5)] The polyol (A) may contain a polycarbonate polyol (A5) having a number average molecular weight of 500 to 4000 (hereinafter sometimes simply referred to as "polycarbonate polyol (A5)").

[0076] Examples of the polycarbonate polyol (A5) include polyhexamethylene carbonate polyol and polycyclohexanedimethylene carbonate polyol. The polycarbonate polyol may be used alone or in combination of two or more.

[0077] The number average molecular weight of the polycarbonate polyol (A5) is preferably 500 or more, more preferably 1000 or more, still more preferably 1500 or more, even more preferably 2000 or more, and even more preferably 2500 or more. The number average molecular weight of the polycarbonate polyol is preferably 4000 or less, more preferably 3800 or less, and still more preferably 3700 or less. When the number average molecular weight of the polycarbonate polyol is 500 or more, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. When the number average molecular weight of the polycarbonate polyol is 4000 or less, the coatability of the moisture-curing hot melt adhesive is improved.

[0078] The hydroxyl value of the polycarbonate polyol (A5) is preferably 15 mgKOH / g or more, more preferably 20 mgKOH / g or more, and still more preferably 25 mgKOH / g or more. The hydroxyl value of the polycarbonate polyol (A5) is preferably 50 mgKOH / g or less, more preferably 45 mgKOH / g or less, still more preferably 40 mgKOH / g or less, and even more preferably 35 mgKOH / g or less. When the hydroxyl value of the polycarbonate polyol (A5) is 15 mgKOH / g or more, the resin adhesiveness of the moisture-curing hot melt adhesive is improved. When the hydroxyl value of the polycarbonate polyol (A5) is 50 mgKOH / g or less, the resin adhesiveness of the moisture-curing hot melt adhesive is improved.

[0079] In the polyol (A), the content of the polycarbonate polyol (A5) is preferably 0.5% by mass or more, more preferably 1% by mass or more, and still more preferably 2% by mass or more. In the polyol (A), the content of the polycarbonate polyol (A5) is preferably 20% by mass or less, more preferably 18% by mass or less, still more preferably 15% by mass or less, even more preferably 11% by mass or less, and even more preferably 8% by mass or less. When the content of the polycarbonate polyol (A5) is 0.5% by mass or more, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. When the content of the polycarbonate polyol (A5) is 20% by mass or less, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved.

[0080] When the polyol (A) further contains a crystalline polyester polyol (A4) and / or a polycarbonate polyol (A5), in the polyol (A), when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass, the content of the polycarbonate polyol (A5) is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 2% by mass or more. In the polyol (A), when the total amount of the microcrystalline polyester polyol (A1), the liquid polyester polyol (A2), the second polyol, the crystalline polyester polyol (A4) and the polycarbonate polyol (A5) is 100% by mass, the content of the polycarbonate polyol (A5) is preferably 20% by mass or less, more preferably 18% by mass or less, still more preferably 15% by mass or less, still more preferably 11% by mass or less, and even more preferably 8% by mass or less. When the content of the polycarbonate polyol (A5) is 0.5% by mass or more, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. When the content of the polycarbonate polyol (A5) is 20% by mass or less, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved.

[0081] [Polyisocyanate compound (B)] The moisture-curing hot melt adhesive contains a urethane prepolymer, and this urethane prepolymer is a reaction product of the above polyol (A) and polyisocyanate compound (B). The urethane prepolymer is a product obtained by condensation polymerization of the polyol (A) and the polyisocyanate compound (B) while forming a urethane bond between the hydroxyl group of the polyol (A) and the isocyanate group of the polyisocyanate compound (B).

[0082] The polyisocyanate compound includes a first polyisocyanate compound containing diisocyanate and polymethylene polyphenyl polyisocyanate, and at least one second polyisocyanate selected from the group consisting of an isocyanurate compound and a biuret type polyisocyanate.

[0083] The polyisocyanate compound contains diisocyanate and polymethylene polyphenyl polyisocyanate as essential components, and contains either or both of an isocyanurate compound and a biuret-type polyisocyanate.

[0084] [First Polyisocyanate Compound] The polyisocyanate compound contains a first polyisocyanate containing diisocyanate and polymethylene polyphenyl polyisocyanate.

[0085] The diisocyanate is not particularly limited. For example, diphenylmethane diisocyanate (MDI, 4,4'-isomer, 2,4-isomer, 2,2'-isomer or a mixture thereof), carbodiimide-modified MDI, carbodiimidized diphenylmethane isocyanate compound, tolylene diisocyanate (TDI, 2,4-isomer, 2,6-isomer or a mixture thereof), xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate (NDI), tetramethylxylylene diisocyanate, phenylene diisocyanate, hexamethylene diisocyanate (HDI), dimer acid diisocyanate, norbornene diisocyanate, lysine diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, etc. may be mentioned. A polyisocyanate compound containing an aromatic ring (for example, benzene ring, naphthalene ring, etc.) is preferred. Diisocyanate is preferred because the resin adhesiveness of the moisture-curing hot melt adhesive is improved, and diphenylmethane diisocyanate and carbodiimide-modified MDI are preferred, and diphenylmethane diisocyanate is more preferred. Note that the diisocyanate may be used alone or in combination of two or more.

[0086] As the polymethylene polyphenyl polyisocyanate, it is represented by the following formula 2 and has 3 or more isocyanate groups in the molecule. In formula 2, q is a natural number, and a natural number from 1 to 5 is preferred. The polymethylene polyphenyl polyisocyanate may be used alone or in combination of two or more.

[0087] [Chemical formula]

[0088] By using the polymethylene polyphenyl polyisocyanate, the crosslinking density of the cured product of the moisture-curing hot melt adhesive can be improved, and the wet heat adhesiveness can be improved.

[0089] [Second polyisocyanate compound] The second polyisocyanate compound contains at least one polyisocyanate compound selected from the group consisting of isocyanurate compounds and biuret-type polyisocyanates.

[0090] The second polyisocyanate compound includes either one or both of an isocyanurate compound and a biuret-type polyisocyanate.

[0091] [Isocyanurate compound] The isocyanurate compound used in the moisture-curing hot melt adhesive is a trimer of diisocyanate, has a cyclic skeleton, and contains a plurality (preferably 3) of isocyanate groups in the molecule. By including an isocyanurate compound in the polyisocyanate compound, the wet heat adhesiveness of the moisture-curing hot melt adhesive is improved. The isocyanurate compound may be used alone or in combination of two or more.

[0092] The isocyanurate compound is a trimer of diisocyanate. The diisocyanate is not particularly limited. For example, diphenylmethane diisocyanate (MDI, 4,4'-isomer, 2,4-isomer, 2,2'-isomer or a mixture thereof), carbodiimide-modified MDI, carbodiimidized diphenylmethane isocyanate compound, tolylene diisocyanate (TDI, 2,4-isomer, 2,6-isomer or a mixture thereof), xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate (NDI), tetramethylxylylene diisocyanate, phenylene diisocyanate, hexamethylene diisocyanate (HDI), dimer acid diisocyanate, norbornene diisocyanate, lysine diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, etc. may be mentioned.

[0093] [Biuret-type polyisocyanate] The biuret-type polyisocyanate is a polyisocyanate having a structure represented by the following formula (3) in the molecule and having a plurality of isocyanate groups.

[0094] TIFF0007706148000003.tif27170

[0095] As the biuret-type polyisocyanate, a polyisocyanate in which -R 7 -NCO is bonded to each of the nitrogen atoms of the formula (3) is preferable. R 7 is an alkylene group.

[0096] Examples of the alkylene group include an ethylene group, a propylene group [-CH(CH3)-CH2-], a trimethylene group [-CH2-CH2-CH2-], a butylene group, an amylene group [-(CH2)5-], a hexylene group, etc.

[0097] In the urethane prepolymer, the content of the diisocyanate unit is preferably 9% by mass or more, more preferably 10% by mass or more, and still more preferably 11% by mass or more. In the urethane prepolymer, the content of the diisocyanate unit is more preferably 20% by mass or less, and still more preferably 13% by mass or less. When the content of the diisocyanate unit is 9% by mass or more, the resin adhesiveness of the moisture-curable hot melt adhesive is improved. When the content of the diisocyanate unit is 20% by mass or less, the resin adhesiveness of the moisture-curable hot melt adhesive is improved.

[0098] In the urethane prepolymer, the content of polymethylene polyphenyl polyisocyanate is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, and still more preferably 4% by mass or more. The content of polymethylene polyphenyl polyisocyanate is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 6.5% by mass or less. When the content of polymethylene polyphenyl polyisocyanate is 1% by mass or more, the crosslinking density of the cured product of the moisture-curable hot melt adhesive is improved, and the wet heat adhesiveness of the moisture-curable hot melt adhesive is improved. When the content of polymethylene polyphenyl polyisocyanate is 10% by mass or less, the resin adhesiveness of the moisture-curable hot melt adhesive is improved.

[0099] In the urethane prepolymer, the content of the second polyisocyanate compound is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.5% by mass or more, still more preferably 0.8% by mass or more, and still more preferably 1% by mass or more. The content of the second polyisocyanate compound is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 6% by mass or less, still more preferably 4% by mass or less, still more preferably 3% by mass or less, and still more preferably 2% by mass or less. When the content of the second polyisocyanate compound is 1% by mass or more, the crosslinking density of the cured product of the moisture-curable hot melt adhesive is improved, and the wet heat adhesiveness of the moisture-curable hot melt adhesive is improved. When the content of the second polyisocyanate compound is 10% by mass or less, the resin adhesiveness of the moisture-curable hot melt adhesive is improved.

[0100] In the urethane prepolymer, the content of the isocyanurate compound is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.5% by mass or more, still more preferably 0.8% by mass or more, and still more preferably 1% by mass or more. The content of the isocyanurate compound is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 6% by mass or less, still more preferably 4% by mass or less, still more preferably 3% by mass or less, and still more preferably 2% by mass or less. When the content of the isocyanurate compound is 1% by mass or more, the crosslinking density of the cured product of the moisture-curable hot melt adhesive is improved, and the wet heat adhesiveness of the moisture-curable hot melt adhesive is improved. When the content of the isocyanurate compound is 10% by mass or less, the resin adhesiveness of the moisture-curable hot melt adhesive is improved.

[0101] In the urethane prepolymer, the content of the biuret-type polyisocyanate is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.5% by mass or more, still more preferably 0.8% by mass or more, and still more preferably 1% by mass or more. The content of the biuret-type polyisocyanate is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 6% by mass or less, still more preferably 4% by mass or less, still more preferably 3% by mass or less, and still more preferably 2% by mass or less. When the content of the biuret-type polyisocyanate is 1% by mass or more, the crosslinking density of the cured product of the moisture-curable hot melt adhesive is improved, and the wet heat adhesiveness of the moisture-curable hot melt adhesive is improved. When the content of the biuret-type polyisocyanate is 10% by mass or less, the resin adhesiveness of the moisture-curable hot melt adhesive is improved.

[0102] [Additives] The moisture-curable hot melt adhesive may contain additives such as tackifiers, oils, plasticizers, curing catalysts, stabilizers, fillers, antioxidants, light stabilizers, ultraviolet absorbers, colorants, flame retardants, fragrances, pigments, and dyes, as long as the effects thereof are not inhibited.

[0103] The tackifier is not particularly limited, and examples thereof include rosin resins, terpene resins, aliphatic petroleum resins, aromatic petroleum resins, etc. Note that the tackifier may be used alone or in combination of two or more kinds.

[0104] The ring and ball softening point of the tackifier is preferably 90 to 150°C because it can prevent elution from the moisture-curing hot melt adhesive at normal temperature and can be sufficiently melted when the moisture-curing hot melt adhesive is melted. The ring and ball softening point of the tackifier is the temperature measured in accordance with JIS K6863 (as a measurement method, a ring filled with a sample in a glycerin bath is horizontally supported, and the temperature when the ball placed in the center of the sample touches the bottom plate is measured).

[0105] The oil is not particularly limited, and examples thereof include aromatic components, naphthenic oils, paraffinic oils, etc. contained in known oils generally referred to as process oils, extender oils, softeners, etc. as rubber softeners. Note that the oil may be used alone or in combination of two or more kinds.

[0106] The plasticizer is not particularly limited, and examples thereof include phthalic acid esters such as diisononyl phthalate and dioctyl phthalate, fatty acid - basic acid esters such as glycerin monooleate, fatty acid dibasic acid esters such as dioctyl adipate, aliphatic esters such as butyl oleate and methyl acetylricinoleate, trimellitic acid esters, chlorinated paraffins, hydrocarbon plasticizers such as alkyl diphenyl and partially hydrogenated terphenyl, process oils, epoxy plasticizers such as epoxidized soybean oil and benzyl epoxystearate, vinyl polymers obtained by polymerizing vinyl monomers, esters of polyalkylene glycols such as diethylene glycol dibenzoate, triethylene glycol dibenzoate, and pentaerythritol ester, etc. Note that the plasticizer may be used alone or in combination of two or more kinds.

[0107] The curing catalyst is used to improve the curability of the moisture-curing hot melt adhesive. The curing catalyst is not particularly limited, and examples thereof include amine-based curing catalysts and tin-based curing catalysts. The curing catalyst may be used alone or in combination of two or more kinds.

[0108] As the amine-based curing catalyst, a morpholine-based compound is preferable. Specifically, 2,2'-dimorpholinodiethyl ether, bis(2,6-dimethylmorpholinoethyl) ether, bis(2-(2,6-dimethyl-4-morpholino)ethyl)-(2-(4-morpholino)ethyl)amine, bis(2-(2,6-dimethyl-4-morpholino)ethyl)-(2-(2,6-diethyl-4-morpholino)ethyl)amine, tris(2-(4-morpholino)ethyl)amine, tris(2-(4-morpholino)propyl)amine, tris(2-(4-morpholino)butyl)amine, tris(2-(2,6-dimethyl-4-morpholino)ethyl)amine, tris(2-(2,6-diethyl-4-morpholino)ethyl)amine, tris(2-(2-ethyl-4-morpholino)ethyl)amine, tris(2-(2-ethyl-4-morpholino)ethylamine, etc. can be mentioned.

[0109] The tin-based curing catalyst is not particularly limited, and examples thereof include stannous acetate, dibutyltin dilaurate, dibutyltin dioctate, dibutyltin diacetate, dioctyltin dilaurate, dioctyltin dioctate, dioctyltin diacetate, stannous octoate, etc. These may be used alone or in combination of two or more kinds.

[0110] The filler is not particularly limited, and examples thereof include silica, talc, clay, calcium carbonate, magnesium carbonate, silicon anhydride, hydrous silicon, calcium silicate, titanium dioxide, carbon black, bentonite, organic bentonite, silas balloon, glass microballoon, organic microballoon such as phenolic resin and vinylidene chloride resin, resin powder such as polyvinyl chloride (PVC) powder and polymethyl methacrylate powder, etc. The filler may be used alone or in combination of two or more kinds.

[0111] The antioxidant is not particularly limited, and examples thereof include hindered phenol antioxidants, monophenol antioxidants, bisphenol antioxidants, polyphenol antioxidants, etc. The antioxidant may be used alone or in combination of two or more.

[0112] The light stabilizer is not particularly limited. For example, hindered amine light stabilizers are preferred, and hindered amine light stabilizers in which the amine moiety is a tertiary amine are more preferred. Examples of the light stabilizer include N,N’,N’’,N’’’-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine, bis(2,2,6,6-tetramethyl-1(octyloxy)-4-piperidinyl) sebacate, the reaction product of 1,1-dimethylethyl hydroperoxide and octane, bis(1,2,2,6,6,-pentamethyl-4-piperidyl [[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis(1-octyloxy-2,2,6,6tetramethyl-4-piperidyl) sebacate, etc. The light stabilizer may be used alone or in combination of two or more.

[0113] The ultraviolet absorber is not particularly limited, and examples thereof include benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, etc. The ultraviolet absorber may be used alone or in combination of two or more.

[0114] [Moisture-curing hot melt adhesive] The production method of the moisture-curing hot melt adhesive is not particularly limited. The production method of the moisture-curing hot melt adhesive can be, for example, produced by adding additives as necessary to the urethane prepolymer produced in the above-described manner, heating and melting it, and uniformly mixing them.

[0115] Since the moisture-curing hot melt adhesive contains a urethane prepolymer which is a reaction product of a polyol (A) containing a first polyol containing a microcrystalline polyester polyol (A1) and a liquid polyester polyol (A2) and a second polyol, and a polyisocyanate compound containing a first polyisocyanate compound containing a diisocyanate and a polymethylene polyphenyl polyisocyanate and a second polyisocyanate, without inhibiting the resin adhesion improving effect of the moisture-curing hot melt adhesive due to a specific polyol, the crosslinking density of the cured product of the moisture-curing hot melt adhesive is improved using a specific polyisocyanate compound (B), and the moisture-curing hot melt adhesive has excellent wet heat adhesiveness.

[0116] The melt viscosity of the moisture-curing hot melt adhesive at 120°C is preferably 5000 to 60000 mPa·s, more preferably 5500 to 55000 mPa·s, and even more preferably 6000 to 50000 mPa·s. When the melt viscosity of the moisture-curing hot melt adhesive at 120°C is 5000 mPa·s or more, the coatability of the moisture-curing hot melt adhesive is improved. When the melt viscosity of the moisture-curing hot melt adhesive at 120°C is 60000 mPa·s or less, the coatability of the moisture-curing hot melt adhesive is improved. The melt viscosity of the moisture-curing hot melt adhesive at 120°C refers to the melt viscosity obtained by measuring under the conditions of a temperature of 120°C and a rotational speed of 20 rpm in accordance with the Japan Adhesives Industry Association Standard JAI-7-1999 using a B-type viscometer. As the B-type viscometer, for example, it is commercially available from Brookfield under the trade name "B-type Viscometer Digital Rheometer DVII (Rotor No. 29)".

[0117] The usage instructions of the moisture-curing hot melt adhesive will be described. To use the moisture-curing hot melt adhesive, heat the moisture-curing hot melt adhesive to 70~160°C to melt it, and then apply the molten moisture-curing hot melt adhesive to the substrate (adherend) or the surface sheet (preferably the surface sheet) using a general method. Bond the surface sheet to the substrate through the moisture-curing hot melt adhesive. Note that examples of the applicator for applying the molten moisture-curing hot melt adhesive to the substrate (adherend) or the surface sheet (preferably the surface sheet) include a roll coater, a spray coater, a T-die coater, a knife coater, etc.

[0118] After that, by leaving the moisture-curing hot melt adhesive preferably at 20~25°C in an environment with a relative humidity of 50~60% for 120~200 hours, the moisture-curing hot melt adhesive can be cured by the moisture (humidity) contained in the air, the substrate (adherend) or the surface sheet, etc., and the surface sheet can be adhesively integrated onto the substrate.

[0119] Since the moisture-curing hot melt adhesive has excellent resin adhesiveness, even when the surface of the substrate is formed of a synthetic resin, the surface sheet can be firmly adhesively integrated onto the substrate surface.

[0120] The material constituting the substrate or the surface of the substrate is not particularly limited, and examples include synthetic resins such as polyvinyl chloride, polyvinylidene chloride, SPC, polyethylene, polypropylene, polystyrene, ABS, polyamide, polyester, polyurethane, polyvinyl alcohol, ethylene-vinyl acetate copolymer resin, chlorinated polypropylene, and melamine resin.

[0121] Examples of the surface sheet include, for example, a decorative sheet. The decorative sheet is not particularly limited, and examples thereof include a synthetic resin sheet containing a synthetic resin such as polyester, nylon, polystyrene, polycarbonate, polyvinyl chloride, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyethylene, and polypropylene, paper, veneer, and metal foil. The decorative sheet may have enhanced decorativeness by attaching colors or patterns to its surface.

[0122] A decorative material obtained by integrally bonding a surface sheet to the surface of a base material using a moisture-curing hot melt adhesive is preferably used, for example, as a flooring material, a frame or panel of a wooden door, a window frame, a threshold, a handrail, a baseboard, a molding, or an exterior material, interior material, and furniture such as a kitchen, a bathroom, a washbasin, and a closet.

[0123] Since the moisture-curing hot melt adhesive has excellent wet heat adhesiveness, even when the decorative material formed using the moisture-curing hot melt adhesive is used in a wet area such as a kitchen, a bathroom, or a washbasin, an unexpected situation where the surface sheet peels off from the base material hardly occurs, and the decorative material can maintain a beautiful appearance over a long period of time.

Examples

[0124] Hereinafter, the present invention will be described more specifically using examples, but the present invention is not limited thereto.

[0125] The polyol (A) and polyisocyanate compound (B) used in the examples and comparative examples are shown below.

[0126] [Polyol (A)] [First polyol] [Microcrystalline polyester polyol (A1)] · Microcrystalline polyester polyol (A1) (manufactured by Toyo Kosan Co., Ltd., trade name "HS 2H-458T", heat absorption amount: 6 cal / g, hydroxyl value: 25 mgKOH / g, number average molecular weight: 4500, a condensation polymer of adipic acid, terephthalic acid, and 1,6-hexanediol)

[0127] [Liquid polyester polyol (A2)] · Liquid polyester polyol (A21) (manufactured by Toyo Oil Co., Ltd., trade name "HS 2F-305S", liquid at 1 atm (1.013×10 5 Pa) and 20 °C, hydroxyl value: 36 mgKOH / g, number average molecular weight: 3100, condensation polymer of ethylene glycol, neopentyl glycol and 1,6-hexanediol, and adipic acid, sebacic acid and isophthalic acid) · Liquid polyester polyol (A22) (manufactured by Toyo Oil Co., Ltd., trade name "HS Polyol 2000", liquid at 1 atm (1.013×10 5 Pa) and 20 °C, hydroxyl value: 32 mgKOH / g, number average molecular weight: 3500, condensation polymer of adipic acid, terephthalic acid and phthalic anhydride, and ethylene glycol)

[0128] [Second polyol] [Polyether polyol (A3)] · Polyether polyol (A3) (manufactured by AGC, trade name "Excenol 1030", polypropylene triol, in formula 1, R 4 : propylene group, R 5 : propylene group, R 6 : propylene group, hydroxyl value: 160 mgKOH / g, number average molecular weight: 1000)

[0129] [Castor oil polyol (A6)] · Castor oil polyol (A6) (manufactured by Toyo Oil Co., Ltd., trade name "TLM", reaction product of glycerin and ricinoleic acid, having an average of 2.7 hydroxyl groups per molecule, hydroxyl value: 160 mgKOH / g, number average molecular weight: 950)

[0130] [Crystalline polyester polyol (A4)] · Crystalline polyester polyol (A41) (manufactured by Ube Industries, Ltd., trade name "Etanacol 3010", heat absorption: 25 cal / g, hydroxyl value: 30 mg KOH / g, number average molecular weight: 3500, condensation polymer of 1,12-dodecanedioic acid and 1,6-hexanediol, carbon number excluding carbon in the carboxyl group of 1,12-dodecanedioic acid: 10, carbon number of 1,6-hexanediol: 6) · Crystalline polyester polyol (A42) (manufactured by Evonik Degussa GmbH, trade name "Dynacol 7380", heat absorption: 25 cal / g, hydroxyl value: 30 mg KOH / g, number average molecular weight: 3500, condensation polymer of 1,12-dodecanedioic acid and 1,6-hexanediol, carbon number excluding carbon in the carboxyl group of 1,12-dodecanedioic acid: 10, carbon number of 1,6-hexanediol: 6)

[0131] [Polycarbonate polyol (A5)] · Polycarbonate polyol (A5) (manufactured by Ube Industries, Ltd., trade name "Etanacol UH-300", condensation polymer of dimethyl carbonate and 1,6-hexanediol and having hydroxyl groups at both ends, hydroxyl value: 38 mg KOH / g, number average molecular weight: 3500)

[0132] [Flame retardant] · Triphenyl phosphate

[0133] [Polyisocyanate compound (B)] [Diisocyanate] · 4,4'-Diphenylmethane diisocyanate (MDI)

[0134] [Polymethylene polyphenyl polyisocyanate] · Polymethylene polyphenyl polyisocyanate (crude MDI, q in formula 2: integer from 1 to 5)

[0135] [Isocyanurate compound] · Isocyanurate compound 1 (trimer (isocyanurate form) of hexamethylene diisocyanate, manufactured by Asahi Kasei Corporation, trade name "TPA-100") · Isocyanurate compound 2 (trimer of isophorone diisocyanate (isocyanurate form), product name "VESTANAT T 1890 SN" manufactured by Evonik Japan Co., Ltd., 70% by mass solution, the table shows only the amount of isocyanurate compound 2)

[0136] [Biuret type polyisocyanate] · Biuret type polyisocyanate (product name "24A-100" manufactured by Asahi Kasei Corporation, HDI biuret type polyisocyanate)

[0137] [Flame retardant] · Triphenyl phosphate (TPP, manufactured by Daihachi Chemical Industry Co., Ltd., molecular weight: 326, melting point: 48.6 °C)

[0138] (Examples 1 to 23, Comparative Examples 1 to 4) Into a 3-liter four-necked flask equipped with stirring blades, the polyol (A) was supplied in the predetermined amounts shown in Tables 1 to 3, heated and melted at 120 °C and mixed, and then the inside of the flask was depressurized to 1 mmHg or less to dehydrate the polyol (A). After purging the inside of the flask with nitrogen, the polyol (A) was maintained at 80 °C.

[0139] In the polyol (A), the content ratios (mass %) of the microcrystalline polyester polyol (A1), liquid polyester polyol (A2), polyether polyol (A3), crystalline polyester polyol (A4), and polycarbonate polyol (A5) are shown in Tables 1 to 3.

[0140] Into the flask, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, and isocyanurate compound as the polyisocyanate compound (B) and triphenyl phosphate were supplied, and the polyol (A) and the polyisocyanate compound (B) were reacted at 80 °C for 3 hours in a nitrogen atmosphere to produce a urethane prepolymer.

[0141] While maintaining the obtained urethane prepolymer at 80°C, a specified amount of triphenyl phosphate shown in Table 1 was added to the urethane prepolymer as a flame retardant to produce a moisture-curing hot melt adhesive. The obtained moisture-curing hot melt adhesive was solid at 25°C.

[0142] Regarding the obtained moisture-curing hot melt adhesive, the melt viscosity at 120°C was measured in the above-mentioned manner, and the results are shown in Tables 1 to 3.

[0143] Regarding the obtained moisture-curing hot melt adhesive, the normal heat-resistant creep (resin adhesiveness) and the wet heat continuous creep (wet heat adhesiveness) were measured in the following manner, and the results are shown in Tables 1 to 3.

[0144] [Normal heat-resistant creep (resin adhesiveness)] The moisture-curing hot melt adhesive was heated to 120°C and melted. The melted moisture-curing hot melt adhesive was applied with a coating thickness of 40 μm over the entire surface of one side of a polyolefin resin sheet having a planar rectangular shape (length 150 cm × width 50 cm) and a thickness of 180 μm.

[0145] Next, a polyolefin resin sheet was superposed on the surface of a plate-shaped substrate made of SPC (Stone Plastic Composite) composed of calcium carbonate and polyvinyl chloride, with the surface temperature maintained at 40°C, so that the moisture-curing hot melt adhesive was on the substrate side. Then, a rubber roll was rolled on the polyolefin resin sheet to produce a laminated sheet. A strip-shaped test piece with a width of 1 inch (2.54 cm) and a length of 15 cm was cut out from the laminated sheet.

[0146] The obtained test piece was cured for one week in an atmosphere at 23°C and a relative humidity of 55% to moisture-cure the moisture-curing hot melt adhesive.

[0147] The test piece was arranged with the main surface in the horizontal direction such that the polyolefin resin sheet was on the lower side. A load of 500 g / 1 inch was applied to one end of the polyolefin resin sheet in the length direction, and while maintaining this state, the test piece was left in an atmosphere of 60 °C for 24 hours, and the length (mm) of the polyolefin resin sheet peeled from the base material was measured. In Comparative Examples 1, 2, and 5, since the polyolefin resin sheet peeled from the base material over the entire length within 24 hours from the start of the test, measurement could not be performed.

[0148] [Wet heat continuous creep (wet heat adhesiveness)] A test piece was prepared in the same manner as in the measurement of normal heat-resistant creep. The test piece was arranged with the main surface in the horizontal direction such that the polyolefin resin sheet was on the lower side. A load of 70 g / 25 mm was applied to one end of the polyolefin resin sheet in the length direction, and while maintaining this state, the test piece was left in an atmosphere of 85 °C and a relative humidity of 85% for 30 days, and the length (peeling length) (mm) of the polyolefin resin sheet peeled from the base material was measured. In Comparative Examples 1 to 4, since the polyolefin resin sheet peeled from the base material over the entire length within 30 days from the start of the test, measurement could not be performed.

[0149] At the time point when 30 days had passed since the start of the test, for the test piece in which a part of the polyolefin resin sheet was adhered to the base material, it was left under the same conditions, and the number of days (peeling days) elapsed until the polyolefin resin sheet was completely peeled from the base material was measured.

[0150] [Table 1]

[0151] [Table 2]

[0152] [Table 3]

Claims

1. A urethane prepolymer that is a reaction product of a polyol and a polyisocyanate compound and has an isocyanate group at its terminal, wherein the polyol includes a first polyol containing a microcrystalline polyester polyol having a number average molecular weight of 3,000 to 6,000 and a liquid polyester polyol having a number average molecular weight of 1,000 to 6,000, and at least one second polyol selected from the group consisting of a polyether polyol having a number average molecular weight of 500 to 7,000 and a castor oil polyol; the polyisocyanate compound includes a first polyisocyanate compound containing a diisocyanate and a polymethylene polyphenyl isocyanate, and at least one second polyisocyanate compound selected from the group consisting of an isocyanurate compound and a biuret-type polyisocyanate; the polyol includes 20 to 45% by mass of the microcrystalline polyester polyol, 15 to 40% by mass of the liquid polyester polyol, and 1 to 5% by mass of the second polyol; in the urethane prepolymer, the diisocyanate unit is 1 to 20% by mass, the polymethylene polyphenyl isocyanate compound unit is 1 to 10% by mass, and the second polyisocyanate compound unit is 0.1 to 10% by mass, characterized in that it is a moisture-curing hot melt adhesive.

2. A urethane prepolymer that is a reaction product of a polyol and a polyisocyanate compound and has an isocyanate group at its terminal, wherein the polyol includes a first polyol containing a microcrystalline polyester polyol having a number average molecular weight of 3,000 to 6,000 and a liquid polyester polyol having a number average molecular weight of 1,000 to 6,000, and at least one second polyol selected from the group consisting of a polyether polyol having a number average molecular weight of 500 to 7,000 and a castor oil polyol; the polyisocyanate compound includes a first polyisocyanate compound containing a diisocyanate and a polymethylene polyphenyl isocyanate, and at least one second polyisocyanate compound selected from the group consisting of an isocyanurate compound and a biuret-type polyisocyanate; The above polyol further contains a crystalline polyester polyol which is a condensation polymer of a polycarboxylic acid having 2 to 14 carbon atoms excluding the carbon in the carboxy group and a polyol having 2 to 8 carbon atoms, and a polycarbonate polyol having a number average molecular weight of 500 to 4,000. When the total amount of the above microcrystalline polyester polyol, the above liquid polyester polyol, the above second polyol, the above crystalline polyester polyol, and the above polycarbonate polyol is 100% by mass, the above polyol contains 20 to 45% by mass of the above microcrystalline polyester polyol, 15 to 40% by mass of the above liquid polyester polyol, 1 to 5% by mass of the above second polyol, 1 to 35% by mass of the above crystalline polyester polyol, and 1 to 35% by mass of the above polycarbonate polyol. The moisture-curing hot-melt adhesive is characterized in that in the above urethane prepolymer, it contains 1 to 20% by mass of the above diisocyanate unit, 1 to 10% by mass of the above polymethylene polyphenyl isocyanate compound unit, and 0.1 to 10% by mass of the above second polyisocyanate compound unit.

3. The moisture-curing hot-melt adhesive according to claim 1 or 2, wherein the above polyether polyol contains polypropylene triol.

4. The moisture-curing hot-melt adhesive according to any one of claims 1 to 3, characterized in that the melt viscosity at 120 °C is 5,000 to 60,000 mPa·s.

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