Moisture-curable polyurethane hot melt resin composition, and adhesive

Abstract

The present disclosure provides a moisture-curable polyurethane hot melt resin composition that is excellent in terms of low viscosity, initial adhesive properties (initial creep resistance) and final adhesive strength.　The present disclosure provides a moisture-curable polyurethane hot melt resin composition which contains an isocyanate group-containing urethane prepolymer (i) obtained using a polyol (A) and a polyisocyanate (B) as raw materials, and which is characterized in that the polyol (A) contains polyoxyethylene polyoxypropylene glycol (A-1), a polyether glycol (A-2) other than component (A-1), an aromatic polyester polyol (A-3) that is a product of a reaction between a compound having an ether structure and two or more hydroxyl groups and an aromatic polybasic acid, an aromatic polyester polyol (A-4) other than component (A-3), and a crystalline polyester polyol (A-5) other than components (A-3) and (A-4).

Description

Moisture-curing polyurethane hot melt resin composition, adhesive

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

[0002] Moisture-curing polyurethane hot melt adhesives are solvent-free and are therefore environmentally friendly. Various research has been conducted on them to date, primarily for fiber bonding and building material lamination, and they are widely used in industry.

[0003] The moisture-curing polyurethane adhesive achieves its final adhesive strength through moisture curing of the isocyanate groups in the urethane prepolymer, which is its main component. However, when bonding various substrates, high initial adhesive strength is required even immediately after application of the adhesive.

[0004] However, it has been pointed out that conventional moisture-curing polyurethane hot melt adhesives have high viscosity, making production complicated, and have poor initial adhesiveness (creep resistance) and final adhesive strength, resulting in low production yields.

[0005] Japanese Patent Application Laid-Open No. 2005-133051

[0006] The problem to be solved by the present invention is to provide a moisture-curable polyurethane hot-melt resin composition that has low viscosity, excellent initial adhesion (initial creep resistance), and final adhesive strength.

[0007] The present invention provides a moisture-curable polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, which is made from polyol (A) and polyisocyanate (B) as raw materials, wherein the polyol (A) contains polyoxyethylene polyoxypropylene glycol (A-1), a polyether polyol (A-2) other than (A-1), a compound having an ether structure and two or more hydroxyl groups, and an aromatic polyester polyol (A-3) which is a reaction product of an aromatic polybasic acid, an aromatic polyester polyol (A-4) other than (A-3), and a crystalline polyester polyol (A-5) other than (A-3) and (A-4).

[0008] The moisture-curable polyurethane hot-melt resin composition of the present invention has low viscosity, excellent initial adhesion (initial creep resistance), and final adhesive strength.

[0009] The moisture-curable polyurethane hot-melt resin composition of the present invention contains a urethane prepolymer (i) having an isocyanate group, which is made from a polyol (A) containing a specific polyol and a polyisocyanate (B) as raw materials.

[0010] The polyol (A) contains polyoxyethylene polyoxypropylene glycol (A-1), a polyether polyol (A-2) other than the (A-1), an aromatic polyester polyol (A-3) which is a reaction product of a compound having an ether structure and two or more hydroxyl groups and an aromatic polybasic acid, an aromatic polyester polyol (A-4) other than the (A-3), and a crystalline polyester polyol (A-5) other than the (A-3) and (A-4).

[0011] The polyoxyethylene polyoxypropylene glycol (A-1) is an essential component in that it provides excellent final adhesive strength. The number average molecular weight of the polyoxyethylene polyoxypropylene glycol (A-1) is preferably 2,000 to 10,000, more preferably 3,000 to 5,000, in that it provides even better final adhesive strength. The number average molecular weight of the polyoxyethylene polyoxypropylene glycol (A-1) is a value measured by gel permeation chromatography (GPC).

[0012] The amount of the polyoxyethylene polyoxypropylene glycol (A-1) used is preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, in the polyol (A).

[0013] The polyether polyol (A-2) is an essential component for obtaining excellent low viscosity and final adhesive strength, and is a polyether polyol other than the polyoxyethylene polyoxypropylene glycol (A-1), and examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene polyoxytetramethylene glycol, polyoxypropyne polyoxytetramethylene glycol, etc. Among these, polypropylene glycol is preferred because it provides even more excellent low viscosity and final adhesive strength.

[0014] The number average molecular weight of the polyether polyol (A-2) is preferably less than 1,500, and more preferably from 500 to 1,400, in order to obtain even better low viscosity and final adhesive strength. The number average molecular weight of the polyether polyol (A-2) is a value measured by gel permeation chromatography (GPC).

[0015] The amount of the polyether polyol (A-2) used is preferably from 5 to 30% by mass, more preferably from 10 to 20% by mass, of the polyol (A).

[0016] The aromatic polyester polyol (A-3), which is a reaction product of the compound having an ether structure and two or more hydroxyl groups with an aromatic polybasic acid, is an essential component for obtaining excellent low viscosity, initial creep resistance, and final adhesive strength.

[0017] Examples of the compound having an ether structure and two or more hydroxyl groups that can be used include the polyoxyethylene polyoxypropylene glycol (A-1), the polyether polyol (A-2), diethylene glycol, triethylene glycol, tetraethylene glycol, etc. These compounds may be used alone or in combination of two or more.

[0018] Examples of the aromatic polybasic acid that can be used include phthalic acid, isophthalic acid, terephthalic acid, phthalic anhydride, etc. These compounds may be used alone or in combination of two or more.

[0019] The number average molecular weight of the aromatic polyester polyol (A-3) is preferably less than 1,500, and more preferably from 500 to 1,400, in order to obtain even better low viscosity and final adhesive strength. The number average molecular weight of the aromatic polyester polyol (A-3) is a value measured by gel permeation chromatography (GPC).

[0020] The amount of the aromatic polyester polyol (A-3) used is preferably from 2 to 20% by mass, more preferably from 5 to 15% by mass, in the polyol (A).

[0021] The aromatic polyester polyol (A-4) is an essential component for obtaining excellent initial creep resistance and final adhesive strength, and is other than the aromatic polyester polyol (A-3).

[0022] Examples of the aromatic polyester polyol (A-4) that can be used include a reaction product of a compound having a hydroxyl group with a polybasic acid including an aromatic polybasic acid; a reaction product of an aromatic compound having two or more hydroxyl groups with a polybasic acid; and a reaction product of an aromatic compound having two or more hydroxyl groups with a polybasic acid including an aromatic polybasic acid.

[0023] Examples of the compound having a hydroxyl group include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, and 2,2-diethyl-1,3-propanediol. Examples of the usable compounds include aliphatic compounds such as pentanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,4-diethyl-1,5-pentanediol, trimethylolethane, trimethylolpropane, and pentaerythritol; and alicyclic compounds such as cyclopentanediol, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, and alkylene oxide adducts thereof. These compounds may be used alone or in combination of two or more.

[0024] Examples of the aromatic compound having two or more hydroxyl groups that can be used include bisphenol A, bisphenol F, and alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts thereof. These compounds may be used alone or in combination of two or more.

[0025] Examples of the aromatic polybasic acid that can be used include phthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride. Other examples of the polybasic acid that can be used include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and 1,12-dodecanedicarboxylic acid. These polybasic acids may be used alone or in combination of two or more. It is preferable to use one or more compounds selected from the group consisting of phthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride as the aromatic polybasic acid, since this provides even better initial adhesive strength and flexibility.

[0026] Other polybasic acids that can be used include, for example, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, dodecanedioic acid, eicosadioic acid, citraconic acid, itaconic acid, citraconic anhydride, and itaconic anhydride.

[0027] The number average molecular weight of the aromatic polyester polyol (A-4) is preferably 2,000 to 10,000, more preferably 3,000 to 5,000, in terms of obtaining even better low viscosity and final adhesive strength. The number average molecular weight of the aromatic polyester polyol (A-4) is a value measured by gel permeation chromatography (GPC).

[0028] The amount of the aromatic polyester polyol (A-4) used is preferably from 1 to 20% by mass, more preferably from 2 to 10% by mass, in the polyol (A).

[0029] The crystalline polyester polyol (A-5) is an essential component for obtaining excellent low viscosity, initial creep resistance, and final adhesive strength, and is other than the above-mentioned (A-3) and (A-4).

[0030] The crystalline polyester polyol (A-5) may be, for example, a reaction product of a compound having a hydroxyl group and a polybasic acid. In the present invention, "crystalline" refers to a product in which a peak of the heat of crystallization or heat of fusion can be confirmed in a DSC (differential scanning calorimeter) measurement in accordance with JIS K7121:2012, and "amorphous" refers to a product in which such a peak cannot be confirmed.

[0031] Examples of the compound having a hydroxyl group that can be used include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, and glycerin. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use one or more compounds selected from the group consisting of butanediol, hexanediol, octanediol, and decanediol, in order to enhance crystallinity and obtain even better adhesiveness.

[0032] Examples of the polybasic acid that can be used include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and dodecanedioic acid. These compounds may be used alone or in combination of two or more.

[0033] The number average molecular weight of the crystalline polyester polyol (A-5) is preferably 2,000 to 10,000, more preferably 3,000 to 5,000, in terms of obtaining even better low viscosity, initial creep resistance, and final adhesive strength. The number average molecular weight of the crystalline polyester polyol (A-5) is a value measured by gel permeation chromatography (GPC).

[0034] The amount of the crystalline polyester polyol (A-5) used is preferably from 51 to 87% by mass, more preferably from 60 to 75% by mass, of the polyol (A).

[0035] The amount of the crystalline polyester polyol (A-5) used is preferably greater than the total amount of the crystalline polyester polyols (A-1), (A-2), (A-3) and (A-4) used, since this provides even better initial creep resistance.

[0036] The polyol (A) contains the components (A-1) to (A-5) as essential components, but may contain other polyols as necessary. Examples of the other polyols that can be used include polyacrylic polyols, polybutadiene polyols, and polycarbonate polyols. These polyols may be used alone or in combination of two or more.

[0037] Examples of the polyisocyanate (B) that can be used include aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate isocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; and aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate. Among these, aromatic polyisocyanates are preferred, diphenylmethane diisocyanate is more preferred, and 4,4'-diphenylmethane diisocyanate and / or 2,4'-diphenylmethane diisocyanate are preferred, as they provide even better reactivity and final adhesive strength.

[0038] The amount of the polyisocyanate (B) used is preferably 10 to 50% by mass, more preferably 15 to 25% by mass, of the raw materials for the urethane prepolymer (i), in order to obtain even better adhesive strength.

[0039] The urethane prepolymer (i) is obtained by reacting the polyol (A) with the polyisocyanate (B), and has isocyanate groups at the polymer terminals or within the molecule, which are capable of forming a crosslinked structure upon reaction with moisture present in the air or in a housing or adherend to which the urethane prepolymer is applied.

[0040] The urethane prepolymer (i) can be produced, for example, by adding the polyol (A) dropwise to a reaction vessel containing the polyisocyanate (B), followed by heating, and reacting under conditions in which the isocyanate groups of the polyisocyanate (B) are in excess relative to the hydroxyl groups of the polyol (A).

[0041] The urethane bond amount of the urethane prepolymer (i) is preferably 0.4 to 3 mol / kg, more preferably 0.5 to 2.0 mol / kg, and even more preferably 0.6 to 1.2 mol / kg, from the viewpoint of obtaining even better initial creep resistance, low viscosity, and final adhesive strength.

[0042] In producing the urethane prepolymer (i), the equivalent ratio ([isocyanate groups / hydroxyl groups]) of the isocyanate groups in the polyisocyanate (B) to the hydroxyl groups in the polyol (A) is preferably 1.5 to 7.0, more preferably 1.7 to 2.8, from the viewpoint of obtaining even better initial creep resistance, low viscosity, and final adhesive strength.

[0043] The isocyanate group content (hereinafter abbreviated as "NCO %") of the urethane prepolymer (i) is preferably 1.5 to 13.0 mass %, more preferably 2.5 to 5.0 mass %, from the viewpoint of obtaining even better initial creep resistance, low viscosity, and final adhesive strength. The NCO % of the urethane prepolymer (i) is a value measured by potentiometric titration in accordance with JIS K1603-1:2007.

[0044] The moisture-curable polyurethane hot-melt resin composition of the present invention may contain other additives in addition to the urethane prepolymer (i), as required.

[0045] Examples of the other additives that can be used include antioxidants, tackifiers, plasticizers, stabilizers, fillers, dyes, pigments, fluorescent brighteners, silane coupling agents, waxes, etc. These additives may be used alone or in combination of two or more.

[0046] As a method for obtaining a cured (adhesive) film of the moisture-curable polyurethane hot-melt resin composition, for example, the moisture-curable polyurethane hot-melt resin composition is melted at 50 to 130°C, and then coated on a substrate and moisture-cured.

[0047] Examples of the substrate include resin films such as acrylic resins, urethane resins, silicone resins, epoxy resins, fluorine resins, polystyrene resins, polyester resins, polysulfone resins, polyarylate resins, polyvinyl chloride resins, polyvinylidene chloride, cycloolefin resins, polyolefin resins, polyimide resins, alicyclic polyimide resins, cellulose resins, PC (polycarbonate), PBT (polybutylene terephthalate), modified PPE (polyphenylene ether), PEN (polyethylene naphthalate), PET (polyethylene terephthalate), lactic acid polymers, ABS resins, and AS resins; wood substrates such as MDF, plywood, and particle board; and fiber substrates such as nonwoven fabrics, woven fabrics, and knitted fabrics. The substrate may be subjected to corona treatment, plasma treatment, primer treatment, or the like, as necessary.

[0048] Examples of methods for applying the moisture-curable polyurethane hot-melt resin composition include methods using a roll coater, spray coater, T-die coater, knife coater, comma coater, and the like.

[0049] After the coating, the adhesive is aged for 0.5 to 3 days at a temperature of 20 to 80° C. and a relative humidity of 50 to 90%, for example, to obtain the final adhesive strength.

[0050] The moisture-curable polyurethane hot-melt resin composition of the present invention has excellent low viscosity, initial adhesion (initial creep resistance), and final adhesion strength, and is therefore particularly suitable for use as an adhesive for bonding fabrics.

[0051] The present disclosure includes the following embodiments. [1] A moisture-curable polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, the polyol (A) being made from polyol (A) and polyisocyanate (B), wherein the polyol (A) contains polyoxyethylene polyoxypropylene glycol (A-1), a polyether polyol (A-2) other than (A-1), a compound having an ether structure and two or more hydroxyl groups, and an aromatic polyester polyol (A-3) which is a reaction product of an aromatic polybasic acid, an aromatic polyester polyol (A-4) other than (A-3), and a crystalline polyester polyol (A-5) other than (A-3) and (A-4). [2] The moisture-curable polyurethane hot-melt resin composition according to [1] above, wherein the amount of the crystalline polyester polyol (A-5) used is greater than the total amount of the crystalline polyester polyols (A-1), (A-2), (A-3), and (A-4). [3] The moisture-curable polyurethane hot-melt resin composition according to [1] or [2] above, wherein the number-average molecular weights of the polyether polyol (A-2) and the aromatic polyester polyol (A-3) are less than 1,500. [4] The moisture-curable polyurethane hot-melt resin composition according to any one of [1] to [3] above, wherein the number-average molecular weights of the polyoxyethylene polyoxypropylene glycol (A-1), the aromatic polyester polyol (A-4), and the crystalline polyester polyol (A-5) are 2,000 or more. [5] An adhesive comprising the moisture-curable polyurethane hot-melt resin composition according to any one of [1] to [4] above.

[0052] The present invention will be described in more detail below with reference to examples.

[0053] Example 1 Into a four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser, 2 parts by mass of polyoxyethylene polyoxypropylene glycol ("Preminol PML-5001F" manufactured by Asahi Glass Co., Ltd., number average molecular weight: 4,000, abbreviated as "EOPO4000"), 18 parts by mass of polypropylene glycol (number average molecular weight: 1,000, hereinafter abbreviated as "PPG1000"), 12 parts by mass of aromatic polyester polyol (produced by reacting diethylene glycol with phthalic anhydride, number average molecular weight: 1,000, hereinafter abbreviated as "DEG / oPA1000"), and 12 parts by mass of aromatic polyester polyol. 6 parts by mass of crystalline polyester polyol (a reaction product of ethylene glycol, phthalic anhydride, terephthalic acid, and adipic acid; number average molecular weight: 3,500; abbreviated as "EG / oPA / TPA / AA3500"), 31 parts by mass of crystalline polyester polyol (a reaction product of hexanediol and adipic acid; number average molecular weight: 4,500; abbreviated as "HG / AA4500"), and 31 parts by mass of crystalline polyester polyol (a reaction product of hexanediol and dodecanedioic acid; number average molecular weight: 3,500; abbreviated as "HG / DDA3500") were charged, and the mixture was heated under reduced pressure at 110°C to dehydrate it until the moisture content was 0.05% by mass or less. Next, after cooling the temperature inside the container to 90°C, 24 parts by mass of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI") was added, the temperature was raised to 110°C, and the mixture was reacted for about 3 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (1) having isocyanate groups.

[0054] Example 2 A urethane prepolymer (2) having an isocyanate group was obtained in the same manner as in Example 1, except that 19 parts by mass of MDI and 5 parts by mass of "Millionate NM" (a mixture of 4,4'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate (45 / 55 by mass ratio)) manufactured by Tosoh Corporation were used instead of 24 parts by mass of MDI.

[0055] [Example 3] A urethane prepolymer (3) having an isocyanate group was obtained in the same manner as in Example 1, except that the amount of HG / AA4500 was changed from 31 parts by mass to 62 parts by mass, the amount of HG / DDA3500 was changed from 31 parts by mass to 0 parts by mass, and the amount of MDI was changed from 24 parts by mass to 23 parts by mass.

[0056] Example 4 A urethane prepolymer (4) having an isocyanate group was obtained in the same manner as in Example 1, except that the amount of HG / AA4500 was changed from 31 parts by mass to 0 parts by mass, the amount of HG / DDA3500 was changed from 31 parts by mass to 62 parts by mass, and the amount of MDI was changed from 24 parts by mass to 25 parts by mass.

[0057] Comparative Example 1 A urethane prepolymer (R1) having an isocyanate group was obtained in the same manner as in Example 1, except that the amount of DEG / oPA1000 was changed from 12 parts by mass to 18 parts by mass, the amount of EG / oPA / TPA / AA3500 was changed from 6 parts by mass to 0 parts by mass, and the amount of MDI was changed from 24 parts by mass to 26 parts by mass.

[0058] Comparative Example 2 A urethane prepolymer (R2) having an isocyanate group was obtained in the same manner as in Example 1, except that the amount of EOPO4000 was changed from 2 parts by mass to 20 parts by mass, the amount of PPG1000 was changed from 18 parts by mass to 0 parts by mass, and the amount of MDI was changed from 24 parts by mass to 26 parts by mass.

[0059] [Method for Measuring Number Average Molecular Weight] In the examples and comparative examples, the number average molecular weight of polyols and the like is a value measured by gel permeation chromatography (GPC) under the following conditions.

[0060] Measuring device: High-speed GPC device ("HLC-8420GPC" manufactured by Tosoh Corporation) Column: The following columns manufactured by Tosoh Corporation were used, connected in series. "TSKgel G5000HXL" (7.8mm I.D. x 30cm) x 1 tube "TSKgel G4000HXL" (7.8mm I.D. x 30cm) x 1 tube "TSKgel G3000HXL" (7.8mm I.D. x 30cm) x 1 tube "TSKgel G2000HXL" (7.8mm I.D. x 30cm) x 1 tube Guard column "Guard column: TSKguard column HxL-H" Detector: RI (differential refractometer) Column temperature: 40°C Eluent: tetrahydrofuran (THF) stabilizer-containing Flow rate: 1.0 mL / min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 4 mg / mL) Standard sample: A calibration curve was prepared using the following monodisperse polystyrene.

[0061] (Standard polystyrene) "TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

[0062] [Viscosity Measurement Method] The moisture-curable polyurethane hot-melt resin compositions obtained in the Examples and Comparative Examples were melted at 120°C for 1 hour, and then the melt viscosity was measured using a cone-plate viscometer (40P cone, rotor rotation speed: 50 rpm), and the low viscosity was evaluated as follows: "T": less than 30,000 mPa·s "F": 30,000 mPa·s or more

[0063] [Method for measuring initial creep resistance] The moisture-curable polyurethane hot-melt resin compositions obtained in the examples and comparative examples were each melted at a temperature of 120°C for 1 hour. The adhesive was applied to a polyethylene terephthalate sheet using an applicator to a thickness of 100 µm. A polyethylene terephthalate sheet was laminated onto the coated layer and pressed with a pressure roller. After pressing, the sheet was cut to a width of 1 inch, and after 3 minutes, a 50 g weight was hung from it. The peeled distance was measured 30 minutes later, and the initial creep resistance was evaluated as follows: "T": Peel distance is less than 5 mm. "F": Peel distance is 5 mm or more.

[0064] [Method for Measuring Final Adhesive Strength] The moisture-curable polyurethane hot-melt resin compositions obtained in the Examples and Comparative Examples were each melted at a temperature of 120°C for 1 hour. The adhesive was applied to a polyethylene terephthalate sheet using an applicator to a thickness of 100 μm. A polyethylene terephthalate sheet was laminated onto the coated layer and pressed with a pressure roller. After pressing, the sheet was left for 3 days to obtain a cured film. The adhesive strength (N / 25 mm) was measured using a precision universal testing machine "AG-10NX" manufactured by Shimadzu Corporation, and the final adhesive strength and peel mode were evaluated as follows: (Final Adhesive Strength) "T": Peel strength is 15 (N / 25 mm) or more. "F": Peel strength is less than 15 (N / 25 mm). (Peel Mode) "T": Peel mode is substrate failure. "F": Peel mode is cohesive failure or interfacial peeling.

[0065]

[0066] It was found that the moisture-curable polyurethane hot-melt resin composition of the present invention is excellent in low viscosity, initial creep resistance, and final adhesive strength.

[0067] On the other hand, Comparative Example 1, which is an embodiment in which aromatic polyester polyol (A-4) was not used, was poor in initial creep resistance and final adhesive strength.

[0068] Comparative Example 2 is an embodiment in which polyether polyol (A-2) was not used, and the low viscosity and peeling mode at the final adhesion were poor.

Claims

1. A moisture-curable polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, the urethane prepolymer (i) being made from polyol (A) and polyisocyanate (B), wherein the polyol (A) contains: polyoxyethylene polyoxypropylene glycol (A-1); a polyether polyol (A-2) other than (A-1); an aromatic polyester polyol (A-3) which is a reaction product of a compound having an ether structure and two or more hydroxyl groups, and an aromatic polybasic acid; an aromatic polyester polyol (A-4) other than (A-3); and a crystalline polyester polyol (A-5) other than (A-3) and (A-4).

2. The moisture-curable polyurethane hot-melt resin composition according to claim 1, wherein the amount of the crystalline polyester polyol (A-5) used is greater than the total amount of the crystalline polyester polyols (A-1), (A-2), (A-3) and (A-4) used.

3. The moisture-curable polyurethane hot-melt resin composition according to claim 1, wherein the number average molecular weights of the polyether polyol (A-2) and the aromatic polyester polyol (A-3) are less than 1,500.

4. The moisture-curable polyurethane hot-melt resin composition according to claim 1, wherein the number average molecular weights of the polyoxyethylene polyoxypropylene glycol (A-1), the aromatic polyester polyol (A-4), and the crystalline polyester polyol (A-5) are 2,000 or more.

5. An adhesive comprising the moisture-curable polyurethane hot-melt resin composition according to any one of claims 1 to 4.

Images