Moisture-curing polyurethane hot-melt resin compositions, adhesives, cured products, and articles

Abstract

The present invention provides moisture-curing polyurethane hot-melt resin compositions and the like that exhibit excellent moisture resistance, flexibility, and low-temperature adhesion. [Solution] A moisture-curable polyurethane hot melt resin composition containing a urethane prepolymer (i) having an isocyanate group, which is a reaction product of polyol (A) and polyisocyanate (B), wherein the polyol (A) comprises polyester polyol (a1) having structural units derived from linear aliphatic glycols and structural units derived from alicyclic polybasic acids, and polyester polyol (a2) having structural units derived from branched aliphatic glycols and structural units derived from alicyclic polybasic acids.

Description

Technical Field

[0001] The present disclosure relates to a moisture-curable polyurethane hot melt resin composition having moisture-proof properties.

Background Art

[0002] Generally, hot melt resin compositions are solvent-free, environmentally friendly, curable in a short time, and very easy to handle materials, so it is possible to improve the working environment at the manufacturing site. Therefore, hot melt resin compositions are widely used in a wide range of fields such as precision machinery fields such as automobiles and electric appliances, and construction fields.

[0003] For example, in the field of building members, decorative fabricated members obtained by laminating a base material such as plywood, MDF (medium density fiberboard), particle board, etc. and a surface material such as a decorative sheet are widely used. The decorative fabricated member was generally used as a building member by adhering it to both sides of a hollow core material (see Patent Document 1).

[0004] In the usage environment of building members, dew condensation may occur due to the temperature difference between the inside (especially the hollow part) and the outside of the above building members. When the decorative fabricated part absorbs dew condensation, deformation of the decorative fabricated member such as warping and swelling was likely to occur due to differences in moisture absorption of constituent members such as the base material and the surface material. Therefore, a moisture-proof layer is provided inside the decorative fabricated member for the purpose of suppressing deformation due to moisture absorption and improving durability.

[0005] When providing a moisture-proof layer inside a decorative fabricated member, the moisture-proof layer is usually bonded to a base material, a surface material, etc. via an adhesive. However, from the viewpoint of process reduction, it has been considered to use a moisture-curable polyurethane hot melt resin composition having both moisture-proof performance and adhesive performance to integrate the moisture-proof layer and the adhesive layer (see Patent Document 2).

Prior Art Documents

Patent Documents

[0006] <​ Japanese Patent Publication No. 2016-74826 [Patent Document 2] Japanese Patent Publication No. 2021-75657 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, the demand for moisture resistance has been high not only in the building materials field but also in the precision machinery field. Moisture-curing polyurethane hot-melt resin compositions that combine moisture resistance and adhesive properties are considered useful not only for meeting the demand for high moisture resistance but also from the standpoint of reducing processes and the number of parts.

[0008] On the other hand, moisture-curing polyurethane hot-melt resin compositions with moisture-proof properties generally tend to have poor flexibility in the cured film due to strong intermolecular forces. Furthermore, moisture-curing polyurethane hot-melt resin compositions do not adhere well to substrates in low-temperature environments, especially to cooled substrates. As a result, articles joined together via the above-mentioned moisture-curing polyurethane hot-melt resin compositions are prone to delamination, and the articles may easily break. Given these circumstances, there is a need for moisture-curing polyurethane hot-melt resin compositions that are excellent in moisture-proof properties, flexibility, and low-temperature adhesion.

[0009] This disclosure has been made in view of the above-mentioned problems, and aims to provide a moisture-curing polyurethane hot-melt resin composition that is excellent in moisture resistance, flexibility, and low-temperature adhesion. Furthermore, this disclosure aims to provide an adhesive using the above-mentioned moisture-curing polyurethane hot-melt resin composition, as well as a cured product of the moisture-curing polyurethane hot-melt resin composition and an article having the cured product. [Means for solving the problem]

[0010] This disclosure has the following embodiments. [1] A moisture-curable polyurethane hot melt resin composition containing a urethane prepolymer (i) having an isocyanate group, which is a reaction product of a polyol (A) and a polyisocyanate (B), wherein the polyol (A) comprises a polyester polyol (a1) having structural units derived from linear aliphatic glycols and structural units derived from alicyclic polybasic acids, and a polyester polyol (a2) having structural units derived from branched aliphatic glycols and structural units derived from alicyclic polybasic acids. [2] The moisture-curing polyurethane hot-melt resin composition according to [1] above, wherein the content of the polyester polyol (a1) is equal to or greater than the content of the polyester polyol (a2) above. [3] The moisture-curing polyurethane hot-melt resin composition according to [1] to [2] above, wherein the content ratio of the polyester polyol (a1) to the polyester polyol (a2) is 50 / 50 to 95 / 5 by mass. [4] The moisture-curing polyurethane hot-melt resin composition according to any one of [1] to [3] above, wherein the total content of the polyester polyol (a1) and the polyester polyol (a2) is in the range of 20% to 70% by mass in 100% by mass of the polyol (A). [5] The moisture-curing polyurethane hot-melt resin composition according to any one of [1] to [4] above, wherein the polyol (A) further contains a crystalline polyester polyol (a3). [6] The moisture-curing polyurethane hot-melt resin composition according to [5] above, wherein the content of the above-mentioned crystalline polyester polyol (a3) ​​is in the range of 10% to 40% by mass in 100% by mass of the above-mentioned polyol (A). [7] The moisture-curing polyurethane hot-melt resin composition according to any one of [1] to [6] above, wherein the polyol (A) further contains an aromatic polyester polyol (a4). [8] The moisture-curing polyurethane hot-melt resin composition according to [7], wherein the content of the aromatic polyester polyol (a4) is in the range of 5% to 20% by mass in 100% by mass of the polyol (A). [9] A cured product of a moisture-curing polyurethane hot-melt resin composition as described in any of [1] to [8] above.

[10] An adhesive comprising the moisture-curing polyurethane hot-melt resin composition described in any of [1] to [8] above.

[11] An article having at least a cured layer of a moisture-curing polyurethane hot-melt resin composition as described in any of [1] to [8] above.

[12] The article described in

[11] above, which is a molded component. [Effects of the Invention]

[0011] The moisture-curing polyurethane hot-melt resin composition of this disclosure exhibits excellent moisture resistance, flexibility, and low-temperature adhesion. [Modes for carrying out the invention]

[0012] I. Moisture-curing polyurethane hot-melt resin composition The moisture-curing polyurethane hot-melt resin composition of this disclosure (which may be referred to as "the resin composition of this disclosure" or "this resin composition" in this specification) contains a urethane prepolymer (i) having isocyanate groups, which is a reaction product of polyol (A) and polyisocyanate (B). In the resin composition of this disclosure, polyol (A) comprises at least polyester polyol (a1) having structural units derived from linear aliphatic glycols and structural units derived from alicyclic polybasic acids, and polyester polyol (a2) having structural units derived from branched aliphatic glycols and structural units derived from alicyclic polybasic acids.

[0013] According to the resin composition of this disclosure, by including two specific polyester polyols (a1) and (a2) with different structures, it is possible to achieve good moisture resistance, high flexibility, and low-temperature adhesion simultaneously.

[0014] [Urethane prepolymer (i)] In this disclosure, the urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B).

[0015] <Polyol (A)> The polyol (A) constituting the urethane prepolymer (i) in this disclosure comprises at least polyester polyol (a1) and polyester polyol (a2). Polyester polyols (a1) and (a2) may be used individually or in combination of two or more. Since polyester polyols (a1) and polyester polyols (a2) each have structural units derived from alicyclic polybasic acids, they may be referred to as alicyclic polyester polyol (a1) and alicyclic polyester polyol (a2).

[0016] <<Polyester polyol (a1)>> The above polyester polyol (a1) has structural units derived from linear aliphatic glycols and structural units derived from alicyclic polybasic acids. In other words, the above polyester polyol (a1) is a reaction product that requires a polyhydric alcohol mainly composed of linear aliphatic glycols and a polybasic acid mainly composed of alicyclic polybasic acids as essential raw materials. Furthermore, the above polyester polyol (a1) has two or more hydroxyl groups.

[0017] A linear aliphatic glycol is a compound in which a linear aliphatic hydrocarbon has two or more hydroxyl groups and no side chains. Examples of the linear aliphatic glycol include aliphatic glycols such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol (dodecanedioic acid), 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-eicosanediol; ether bond-containing glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, polytetramethylene glycol, polyethylene glycol, polypropylene glycol; and the like. These may be used alone or in combination of two or more.

[0018] The polyhydric alcohol that is a raw material of the polyester polyol (a1) essentially contains a linear aliphatic glycol, but allows the inclusion of polyhydric alcohols other than the linear aliphatic glycol as long as the functions of the polyester polyol (a1) are not impaired. From the viewpoint of ensuring the physical properties exhibited by including the polyester polyol (a1) and the effects of the resin composition of the present disclosure, the content of the linear aliphatic glycol in the polyhydric alcohol that is a raw material of the polyester polyol (a1) is preferably 85% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably substantially 100% by mass.

[0019] Examples of the alicyclic polybasic acid include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclopropanedicarboxylic acid, 1,2-cyclobutanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cycloheptanedicarboxylic acid, 1,3-cycloheptanedicarboxylic acid, 1,4-cycloheptanedicarboxylic acid, 1,2-cyclooctanedicarboxylic acid, 1,3-cyclooctanedicarboxylic acid, 1,4-cyclooctanedicarboxylic acid, 1,5-cyclooctanedicarboxylic acid, 1,2-cyclononanedicarboxylic acid, 1,3-cyclononanedicarboxylic acid, 1,4-cyclononanedicarboxylic acid, 1,5-cyclononanedicarboxylic acid, 1,2-cyclodecanedicarboxylic acid, 1,3-cyclodecanedicarboxylic acid, 1,4-cyclodecanedicarboxylic acid, 1,5-cyclodecanedicarboxylic acid, 1,6-cyclodecanedicarboxylic acid, 1,2,3-cyclopropanetricarboxylic acid, 1,2,3-cyclobutanetricarboxylic acid, 1,2,3-cyclopentanetricarboxylic acid, 1,2,3-cycloheptanetricarboxylic acid, 1,2,3-cyclohexanetricarboxylic acid, dicyclohexyl-4,4'-dicarboxylic acid and dimer acid, 1,2-cyclohexanediacetic acid, 1,3-cyclohexanediacetic acid, 1,4-cyclohexanediacetic acid, and acid anhydrides thereof; anhydrides such as hydrogenated phthalic acid, cyclohexanedipate, etc. These may be used alone or in combination of two or more. Among them, from the viewpoint of improving the moisture-proof performance, a dicarboxylic acid having a cyclohexane ring or its derivative is preferable, and it is more preferable to use at least one selected from 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and hydrogenated phthalic anhydride, and hydrogenated phthalic anhydride is even more preferable.

[0020] The polybasic acid used as a raw material for the polyester polyol (a1) may contain polybasic acids other than alicyclic polybasic acids, provided that it does not impair the function of the polyester polyol (a1). However, from the viewpoint of exhibiting high moisture-proof performance, it is preferable that it does not contain polybasic acids other than alicyclic polybasic acids. The content of alicyclic polybasic acids in the polybasic acid used as a raw material for the polyester polyol (a1) is preferably 99% by mass or more, and particularly preferably substantially 100% by mass.

[0021] The number-average molecular weight (Mn) of the above polyester polyol (a1) is preferably in the range of 500 to 10,000, and more preferably in the range of 800 to 5,000, from the viewpoint of obtaining excellent moisture resistance and adhesive strength. The number-average molecular weight of the above polyester polyol (a1) is shown as the value measured by gel permeation chromatography (GPC) under the conditions described in the examples below.

[0022] The above polyester polyol (a1) may have other structural units as long as it has structural units derived from linear aliphatic glycols and structural units derived from alicyclic polybasic acids, but it is preferable that it is substantially composed only of structural units derived from linear aliphatic glycols and structural units derived from alicyclic polybasic acids. The content of structural units derived from linear aliphatic glycols in the above polyester polyol (a1) is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass, based on the total amount of structural units derived from polyhydric alcohols in the above polyester polyol (a1). Furthermore, the content of structural units derived from alicyclic polybasic acids in the above polyester polyol (a1) is preferably 99% by mass or more, and particularly preferably substantially 100% by mass, based on the total amount of structural units derived from polybasic acids in the above polyester polyol (a1).

[0023] The above polyester polyol (a1) is obtained by polycondensation reaction of a polybasic acid containing an alicyclic polybasic acid and a polyhydric alcohol containing a linear aliphatic glycol using a conventionally known method. The above polycondensation reaction can be carried out by, for example, charging a polybasic acid containing an alicyclic polybasic acid and a polyhydric alcohol containing a linear aliphatic glycol into a reaction vessel, adding a high-boiling point solvent such as xylene, an esterification catalyst, a polymerization inhibitor, etc. as needed, and carrying out dehydration condensation to promote the esterification reaction. The reaction temperature for the above polycondensation reaction is preferably 140°C to 240°C, more preferably 170°C to 230°C, and the reaction time is preferably 5 hours to 20 hours, more preferably 7 hours to 17 hours.

[0024] Examples of the esterification catalysts mentioned above include metal oxides such as tin oxide, antimony oxide, titanium oxide, and vanadium oxide; Brønsted acids such as p-toluenesulfonic acid, sulfuric acid, and phosphoric acid; boron trifluoride complexes; Lewis acids such as titanium tetrachloride and tin tetrachloride; and organometallic compounds such as calcium acetate, zinc acetate, manganese acetate, zinc stearate, alkyltin oxides, and titanium alkoxides. These may be used individually or in combination of two or more. The amount of the esterification catalyst used is preferably in the range of 0.001% to 0.1% by mass, and more preferably in the range of 0.005% to 0.03% by mass, based on 100% by mass of the total mass of polybasic acids including alicyclic polybasic acids and polyhydric alcohols including linear aliphatic glycols.

[0025] Examples of polymerization inhibitors include hydroquinone, monomethyl ether hydroquinone, toluhydroquinone, di-tert-4-methylphenol, trimonomethyl ether hydroquinone, phenothiazine, and tert-butylcatechol. These may be used individually or in combination of two or more. The amount of polymerization inhibitor used is preferably in the range of 0.001% to 0.3% by mass, and more preferably in the range of 0.005% to 0.07% by mass, based on 100% by mass of the total mass of polybasic acids including alicyclic polybasic acids and polyhydric alcohols including linear aliphatic glycols.

[0026] <<Polyester polyol (a2)>> The above polyester polyol (a2) has structural units derived from branched aliphatic glycols and structural units derived from alicyclic polybasic acids. In other words, the above polyester polyol (a1) is a reaction product that requires a polyhydric alcohol mainly composed of branched aliphatic glycols and a polybasic acid mainly composed of alicyclic polybasic acids as essential raw materials. Furthermore, the above polyester polyol (a1) has two or more hydroxyl groups.

[0027] Branched aliphatic glycols are compounds having a main chain with two or more hydroxyl groups in the linear portion, and at least one side chain group bonded to the main chain. The side chain group of a branched aliphatic glycol is preferably an alkyl group, specifically a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, etc.

[0028] Examples of the above branched aliphatic glycols include 1,2-propanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol (abbreviated as 3MPD), 2-ethyl-2-butylpropanediol, 2-methylpropanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 2-methyl-2-butyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, and 2 Examples include branched aliphatic glycols such as ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, and 2,4-diethyl-1,5-pentanediol; and lactone-ring-opening polymerization polyester polyols obtained by ring-opening polymerization of cyclic ester compounds (i.e., lactones) containing side chains, such as pentano-4-lactone compounds, γ-valerolactone compounds, and 4,4-dimethyltetrahydro-2H-pyran-2-one compounds. These may be used individually or in combination of two or more. In particular, from the viewpoint of balancing an appropriate open time at low temperatures with moisture-proof performance, one or more selected from the group consisting of neopentyl glycol, 3-methyl-1,5-pentanediol, and 2-methyl-1,3-propanediol are preferred.

[0029] The polyhydric alcohol used as a raw material for the polyester polyol (a2) above must contain a branched aliphatic glycol, but it is permissible to include polyhydric alcohols other than branched aliphatic glycols as long as the function of the polyester polyol (a2) is not impaired. The branched aliphatic glycol content in the polyhydric alcohol used as a raw material for the polyester polyol (a2) above is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass.

[0030] The above-mentioned alicyclic polybasic acid can be the same as the specific compounds of alicyclic polybasic acids used as raw materials for the polyester polyol (a1) described above. The alicyclic polybasic acid may be used alone or in combination of two or more types.

[0031] The polybasic acid used as a raw material for the polyester polyol (a2) described above may contain polybasic acids other than alicyclic polybasic acids, provided that it does not impair the function of the polyester polyol (a2). However, from the viewpoint of exhibiting high moisture-proof performance, it is preferable that it does not contain polybasic acids other than alicyclic polybasic acids. The content of alicyclic polybasic acids in the polybasic acid used as a raw material for the polyester polyol (a2) described above is preferably 99% by mass or more, and is particularly preferably substantially 100% by mass.

[0032] The number-average molecular weight (Mn) of the above polyester polyol (a2) is preferably 500 to 10,000, and more preferably 800 to 5,000, from the viewpoint of obtaining excellent moisture barrier performance and adhesive strength. The number-average molecular weight of the above polyester polyol (a2) is shown as the value measured by gel permeation chromatography (GPC) under the conditions described in the examples below.

[0033] The above polyester polyol (a2) may have other structural units as long as it has structural units derived from branched aliphatic glycols and structural units derived from alicyclic polybasic acids, but it is preferable that it is substantially composed only of structural units derived from branched aliphatic glycols and structural units derived from alicyclic polybasic acids. The content of structural units derived from branched aliphatic glycols in the above polyester polyol (a2) is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass, based on the total amount of structural units derived from polyhydric alcohols in the above polyester polyol (a2). Furthermore, the content of structural units derived from alicyclic polybasic acids in the above polyester polyol (a2) is preferably 99% by mass or more, and particularly preferably substantially 100% by mass, based on the total amount of structural units derived from polybasic acids in the above polyester polyol (a2).

[0034] The above polyester polyol (a2) is obtained by polycondensation of a polybasic acid containing an alicyclic polybasic acid and a polyhydric alcohol containing a branched aliphatic glycol using a conventionally known method. The above polycondensation reaction can be carried out, for example, by charging a polybasic acid containing an alicyclic polybasic acid and a polyhydric alcohol containing a branched aliphatic glycol into a reaction vessel, and adding a high-boiling point solvent such as xylene, an esterification catalyst, a polymerization inhibitor, etc. as needed, and carrying out a dehydration condensation to advance the esterification reaction. The reaction temperature and reaction time of the above polycondensation reaction, as well as specific examples and amounts of the esterification catalyst and polymerization inhibitor used, can be the same as those of the polycondensation reaction temperature and reaction time of the above esterification catalyst and polymerization inhibitor used in the preparation of polyester polyol (a1) described above.

[0035] <<Crystalline polyester polyol (a3)>> The polyol (A) described above may further contain crystalline polyester polyols (a3) ​​other than polyester polyols (a1) and (A2). By further containing crystalline polyester polyols (a3) ​​in the polyol (A), the resin composition of this disclosure can exhibit superior adhesion (initial adhesive strength and final adhesive strength). The crystalline polyester polyol (a3) ​​described above may be used alone or in combination of two or more types. The final adhesive strength refers to the final adhesive strength after the curing reaction of the moisture-curing polyurethane hot melt resin composition.

[0036] In this disclosure, "crystalline" refers to materials in which peaks of crystallization heat or fusion heat can be confirmed by DSC (differential scanning calorimeter) measurement in accordance with JIS K7121:2012, and "amorphous" refers to materials in which the above peaks cannot be confirmed.

[0037] As the above-mentioned crystalline polyester polyol (a3), for example, a crystalline polyester polyol having structural units derived from aliphatic and / or alicyclic compounds having two or more hydroxyl groups and structural units derived from polybasic acids, polycaprolactone polyols, etc., can be used. Note that crystalline polyester polyols having structural units derived from alicyclic polybasic acids are not included in crystalline polyester polyol (a3) ​​and are classified as polyester polyol (a1) or (a2) above depending on the type of structural units derived from polyhydric alcohols.

[0038] Crystalline polyester polyols having structural units derived from aliphatic and / or alicyclic compounds having two or more hydroxyl groups and structural units derived from polybasic acids are reaction products that require at least a polyhydric alcohol mainly composed of aliphatic and / or alicyclic compounds having two or more hydroxyl groups and a polybasic acid as essential raw materials.

[0039] Examples of aliphatic compounds having two or more hydroxyl groups include ethylene glycol, propylene glycol, 1,3-propanediol (trimethylene glycol), 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, and die Examples include ethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,4-diethyl-1,5-pentanediol, trimethylolethane, trimethylolpropane, pentaerythritol, and glycerin. These may be used individually or in combination of two or more.

[0040] Examples of alicyclic compounds having two or more hydroxyl groups include cyclopentanediol, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, and their alkylene oxide adducts. These may be used individually or in combination of two or more.

[0041] The polyhydric alcohol used as a raw material for the above-mentioned crystalline polyester polyol (a3) ​​may contain polyhydric alcohols other than aliphatic and / or alicyclic compounds having two or more hydroxyl groups, as long as the function of the above-mentioned crystalline polyester polyol (a3) ​​is not impaired. The content of aliphatic and / or alicyclic compounds having two or more hydroxyl groups in the polyhydric alcohol used as a raw material for the above-mentioned crystalline polyester polyol (a3) ​​is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass.

[0042] Examples of the polybasic acids mentioned above include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and dodecanedioic acid. These compounds may be used individually or in combination of two or more. Among these, one or more selected from the group consisting of succinic acid, adipic acid, sebacic acid, and dodecanedioic acid are preferred because they enhance crystallinity and provide even better adhesion.

[0043] As the polycaprolactone polyol mentioned above, for example, a reaction product of a compound having two or more hydroxyl groups and ε-caprolactone can be used. As the compound having two or more hydroxyl groups, aliphatic and / or alicyclic compounds having two or more hydroxyl groups as described in the sections on polyester polyols (a1) to (a3) ​​above, aromatic compounds having two or more hydroxyl groups as described in the section on polyester polyols (a4) below, etc. Polycaprolactone polyols may be used alone or in combination of two or more types.

[0044] The number-average molecular weight of the above-mentioned crystalline polyester polyol (a3) ​​can be appropriately selected depending on its type. For example, if the crystalline polyester polyol has structural units derived from aliphatic and / or alicyclic compounds having two or more hydroxyl groups and structural units derived from polybasic acids, the number-average molecular weight is preferably in the range of 500 to 10,000, and more preferably in the range of 1,000 to 6,000. On the other hand, if it is a polycaprolactone polyol, the number-average molecular weight is preferably in the range of 20,000 to 200,000, and more preferably in the range of 30,000 to 100,000. The number-average molecular weight of the crystalline polyester polyol (a3) ​​is shown as the value measured by gel permeation chromatography (GPC) under the conditions described in the examples below.

[0045] The above-mentioned crystalline polyester polyol (a3) ​​is preferably one that does not contain an alicyclic structure, from the viewpoint of crystallinity development. The crystalline polyester polyol (a3) ​​is preferably a crystalline polyester polyol and / or polycaprolactone polyol having structural units derived from aliphatic compounds and structural units derived from polybasic acids. Furthermore, the above-mentioned crystalline polyester polyol (a3) ​​preferably contains at least a polycaprolactone polyol, as this can further improve the initial adhesion of the resin composition of this disclosure.

[0046] The content of the above-mentioned crystalline polyester polyol (a3) ​​is preferably in the range of 10% to 40% by mass, more preferably in the range of 15% to 35% by mass, and even more preferably in the range of 20% to 30% by mass, per 100% by mass of polyol (A). By setting the content of crystalline polyester polyol (a3) ​​in polyol (A) within the above range, a good balance between open time and initial adhesion can be achieved. If the content is too high, it may lead to a decrease in processability due to a shortened open time, and if it is too low, it may lead to a decrease in initial adhesion. Furthermore, among the above-mentioned crystalline polyester polyol (a3), the content of polycaprolactone polyol is preferably in the range of 5% to 20% by mass, and more preferably in the range of 10% to 15% by mass, per 100% by mass of polyol (A), from the viewpoint of improving initial adhesion. In this case, the blending ratio of polycaprolactone polyol in the crystalline polyester polyol (a3) ​​is preferably in the range of 10% to 50% by mass, and more preferably in the range of 25% to 40% by mass, of 100% by mass of the crystalline polyester polyol (a3).

[0047] <<Aromatic polyester polyol (a4)>> The polyol (A) described above may further contain aromatic polyester polyols (a4) other than polyester polyols (a1), (a2), and crystalline polyester polyol (a3). By further including aromatic polyester polyol (a4) in the polyol (A), the initial adhesive strength can be stabilized.

[0048] Examples of the above-mentioned aromatic polyester polyol (a4) include: aromatic polyester polyol (a4-1) containing structural units derived from aliphatic and / or alicyclic compounds having two or more hydroxyl groups and structural units derived from aromatic polybasic acids; aromatic polyester polyol (a4-2) having structural units derived from aromatic compounds having two or more hydroxyl groups and structural units derived from polybasic acids; and the like.

[0049] The aromatic polyester polyol (a4-1) containing structural units derived from aliphatic and / or alicyclic compounds having two or more hydroxyl groups and structural units derived from aromatic polybasic acids is a reaction product that requires at least a polyhydric alcohol mainly composed of aliphatic and / or alicyclic compounds having two or more hydroxyl groups and a polybasic acid mainly composed of aromatic polybasic acids as essential raw materials.

[0050] The aliphatic and / or alicyclic compound having two or more hydroxyl groups, which serves as a raw material for the aromatic polyester polyol (a4-1) described above, can be the same as the aliphatic and / or alicyclic compound having two or more hydroxyl groups in the "crystalline polyester polyol (a3)" described above.

[0051] As the aromatic polybasic acid used as a raw material for the above-mentioned aromatic polyester polyol (a4-1), for example, phthalic acid, isophthalic acid, terephthalic acid, phthalic anhydride, etc., can be used. These may be used individually or in combination of two or more.

[0052] The above aromatic polyester polyol (a4-1) may have other structural units as long as it has structural units derived from aliphatic and / or alicyclic compounds having two or more hydroxyl groups and structural units derived from aromatic polybasic acids, but it is preferable that it is substantially composed of structural units derived from aliphatic and / or alicyclic compounds having two or more hydroxyl groups and structural units derived from aromatic polybasic acids. The content of structural units derived from aliphatic and / or alicyclic compounds having two or more hydroxyl groups in the above aromatic polyester polyol (a4-1) is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass, based on the total amount of structural units derived from polyhydric alcohols in the above aromatic polyester polyol (a4-1). Furthermore, the content of structural units derived from aromatic polybasic acids in the aromatic polyester polyol (a4-1) is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass, based on the total amount of structural units derived from polybasic acids in the aromatic polyester polyol (a4-1).

[0053] The aromatic polyester polyol (a4-2) having structural units derived from an aromatic compound having two or more hydroxyl groups and structural units derived from a polybasic acid is a reaction product that requires at least a polyhydric alcohol mainly composed of an aromatic compound having two or more hydroxyl groups and a polybasic acid as essential raw materials.

[0054] As aromatic compounds having two or more hydroxyl groups that serve as raw materials for the above-mentioned aromatic polyester polyol (a4-2), for example, bisphenol A, bisphenol F, and their alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts can be used. These may be used individually or in combination of two or more.

[0055] As the polybasic acid used as a raw material for the aromatic polyester polyol (a4-2) above, the aromatic polybasic acids exemplified as raw materials for the aromatic polyester polyol (a4-1) above; aliphatic or alicyclic polybasic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, pimelic acid, suberic acid, decandioic acid, dodecandioic acid, eicosanioic acid, citraconic acid, itaconic acid, anhydrous citraconic acid, and anhydrous itacone; etc. may be used. These may be used individually or in combination of two or more.

[0056] The above aromatic polyester polyol (a4-2) may have other structural units as long as it has structural units derived from aromatic compounds having two or more hydroxyl groups and structural units derived from polybasic acids, but it is preferable that it is substantially composed of structural units derived from aromatic compounds having two or more hydroxyl groups and structural units derived from polybasic acids. The content of structural units derived from aromatic compounds having two or more hydroxyl groups in the above aromatic polyester polyol (a4-2) is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably substantially 100% by mass, based on the total amount of structural units derived from polyhydric alcohols constituting the aromatic polyester polyol (a4-2).

[0057] The number-average molecular weight of the above aromatic polyester polyol (a4) is preferably in the range of 500 to 10,000, and more preferably in the range of 1,000 to 5,000, from the viewpoint of achieving high and stable final adhesive strength and good melt viscosity. The number-average molecular weight of the above aromatic polyester polyol (a4) is shown as the value measured by gel permeation chromatography (GPC) under the conditions described in the examples below.

[0058] The content of the aromatic polyester polyol (a4) is preferably in the range of 5 to 20% by mass, and more preferably in the range of 5% to 15% by mass, per 100% by mass of polyol (A). By setting the content of aromatic polyester polyol (a4) in polyol (A) within the above range, high strength and stability of the initial and final adhesive strength can be achieved, and a good melt viscosity can be obtained. If the content is too high, the melt viscosity may become too high and handling properties may decrease, and if it is too low, the final adhesive strength may not be sufficiently achieved.

[0059] <<Other polyols (a5)>> In this disclosure, polyol (A) may include, in addition to the various polyester polyols (a1) to (a4) described above, other polyols (a5). Examples of the other polyols (a5) include amorphous polyester polyols, polyacrylic polyols, polycarbonate polyols, and polyether polyols. These may be used individually or in combination of two or more.

[0060] <<Polyol (A)>> The polyol (A) in this disclosure essentially contains the polyester polyol (a1) and polyester polyol (a2) described above. The total content ratio of polyester polyol (a1) and polyester polyol (a2) is preferably in the range of 20% to 70% by mass, more preferably in the range of 30% to 60% by mass, and even more preferably in the range of 40% to 50% by mass, based on 100% by mass of polyol (A). By setting the total content of polyester polyol (a1) and (a2) in polyol (A) within the above range, a resin composition with excellent moisture resistance, flexibility, and low-temperature adhesion can be obtained.

[0061] The content of polyester polyol (a1) is preferably equal to or greater than the content of polyester polyol (a2), and more preferably greater than the content of polyester polyol (a2). More specifically, the content ratio of polyester polyol (a1) to polyester polyol (a2) [(a1) / (a2)] is preferably in the range of 50 / 50 to 95 / 5 by mass, more preferably in the range of 55 / 45 to 90 / 10, and even more preferably in the range of 60 / 40 to 80 / 20. By having the above relationship between the content of polyester polyol (a1) and polyester polyol (a2), the cured film formed by the resin composition of this disclosure can exhibit higher elongation at break and a lower 100% modulus value while maintaining high moisture resistance. As a result, the resin composition of this disclosure can exhibit even higher flexibility and excellent low-temperature adhesion.

[0062] <Polyisocyanate (B)> Examples of polyisocyanates (B) in this disclosure include aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate (specifically 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, etc.), carbodiimide-modified diphenylmethane diisocyanate isocyanate, phenylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, etc.; and aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, etc. These may be used alone or in combination of two or more. In particular, aromatic polyisocyanates are preferred, and diphenylmethane diisocyanate is more preferred, from the viewpoint of obtaining even better reactivity and final adhesive strength, as well as improving flexibility and low-temperature adhesion.

[0063] The amount of polyisocyanate (B) used is preferably in the range of 5% to 40% by mass, and more preferably in the range of 10% to 30% by mass, of the total mass of the raw materials constituting the urethane prepolymer (i).

[0064] <Urethane prepolymer (i)> The urethane prepolymer (i) in this disclosure is a reaction product of the polyol (A) and the polyisocyanate (B), and has isocyanate groups. Because the urethane prepolymer (i) has isocyanate groups, it can react with moisture present in the air or in the substrate to which the urethane prepolymer is applied to form a crosslinked structure. "A reaction product of the polyol (A) and the polyisocyanate (B)" means that the reaction product has the polyol (A) and the polyisocyanate (B) as essential reaction components, and the reaction may include any components other than the polyol (A) and the polyisocyanate (B) as long as it does not impair the function of the resin composition of this disclosure.

[0065] A known method can be used to produce the above-mentioned urethane prepolymer (i). For example, one method involves 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 of the hydroxyl groups of the polyol (A).

[0066] When producing the above-mentioned urethane prepolymer (i), the equivalent ratio (NCO / OH) of isocyanate groups (NCO) in polyisocyanate (B) and hydroxyl groups (OH) in polyol (A) is preferably in the range of 1.5 to 5.0, and more preferably in the range of 2.0 to 3.0, from the viewpoint of reducing unreacted polyisocyanate (B) and achieving high adhesive strength, high moisture resistance, high flexibility, and excellent low-temperature adhesion.

[0067] The isocyanate group content (hereinafter abbreviated as "NCO%") of the above urethane prepolymer (i) is preferably in the range of 1% to 10% by mass, and more preferably in the range of 2% to 5% by mass, from the viewpoint of achieving high adhesive strength, high moisture resistance, high flexibility, and excellent low-temperature adhesion. The NCO% of the above urethane prepolymer (i) is the value measured by potentiometric titration in accordance with JIS K 1603-1:2007.

[0068] The number average molecular weight of the above urethane prepolymer (i) is preferably in the range of 5,000 to 500,000, and more preferably in the range of 10,000 to 300,000, from the viewpoint of achieving high adhesive strength, high moisture resistance, high flexibility, and excellent low-temperature adhesion.

[0069] The moisture-curing hot melt resin composition of this disclosure may consist solely of a urethane prepolymer, or it may contain any other components in addition to the urethane prepolymer. Examples of such optional components include additives such as tackifiers, curing catalysts, plasticizers, stabilizers, dyes, pigments, fluorescent whitening agents, silane coupling agents, waxes, fillers (e.g., inorganic fillers such as layered silicates, metal powders, calcium carbonate, clay, and carbon black), and thermoplastic resins. The content of the optional components can be appropriately selected within a range that does not hinder the effects of the moisture-curing hot melt resin composition of this disclosure.

[0070] The urethane prepolymer content in the above moisture-curing hot melt resin composition is preferably 60% by mass or more, more preferably 70% by mass or more, 80% by mass or more, or 90% by mass or more. Furthermore, the above content is preferably 100% by mass or less, but may also be 99% by mass or less, or 95% by mass. By setting the urethane prepolymer content within the above range, high adhesive strength, high moisture resistance, high flexibility, and excellent low-temperature adhesion can be achieved simultaneously.

[0071] The moisture-curing polyurethane hot-melt resin composition disclosed herein can form a cured film that exhibits excellent low adhesion to the substrate, high moisture resistance, and high flexibility, and the cured film can function as both an adhesive layer and a moisture-proof layer. The applications of the moisture-curing polyurethane hot-melt resin composition disclosed herein are not limited, but because it has the above-mentioned functions, it is particularly suitable for applications that require high moisture resistance, high flexibility, strong adhesion, and high adhesion to the substrate (especially low-temperature adhesion). Such applications include, for example, adhesives for bonding building material panels, decorative panels, and automotive interior materials; adhesives for joining components in automotive parts, electronic equipment, and batteries; and so on. Furthermore, the resulting decorative panels can be suitably used as flooring; doors such as shoe cabinet doors, closet doors, and kitchen doors; trim materials such as frames, picture frames, and baseboards; and countertops for counter tables and furniture tops.

[0072] [II. Cured product] The cured product of this disclosure is obtained by curing the moisture-curing hot-melt resin composition of this disclosure as described in section I. Moisture-curing hot-melt resin composition above.

[0073] The cured product of the moisture-curing hot-melt resin composition of this disclosure preferably has a 100% modulus in the range of 10 MPa to 30 MPa, more preferably in the range of 10 MPa to 25 MPa, and even more preferably in the range of 10 MPa to 20 MPa. Having 100% modulus within the above range of the cured product of the resin composition of this disclosure provides a highly flexible cured film with high adhesive strength and high moisture resistance.

[0074] The cured product of the moisture-curing hot-melt resin composition of this disclosure preferably has a tensile elongation at break in the range of 200% to 1000%, more preferably in the range of 300% to 900%, and even more preferably in the range of 300% to 800%. When 100% of the duralumin content of the cured product of the resin composition of this disclosure is within the above range, a highly flexible cured film is obtained that possesses high adhesive strength and high moisture resistance.

[0075] The 100% modulus and tensile elongation at break of the cured product of the moisture-curing hot-melt resin composition are values ​​measured by the measurement method described in the examples below.

[0076] Examples of cured products of this disclosure include, but are not limited to, a cured film obtained by moisture curing a coating film formed by applying the moisture-curing hot-melt resin composition of this disclosure in the form of a sheet or film.

[0077] A known method can be used to apply the above-mentioned moisture-curing polyurethane hot-melt resin composition. Examples of such methods include heating and melting the moisture-curing polyurethane hot-melt resin composition at 100 to 140°C, followed by coating methods such as roll coaters, spray coaters, T-die coaters, knife coaters, and comma coaters; precision methods such as dispensers, inkjet printing, screen printing, and offset printing; and nozzle coating. The moisture-curing polyurethane hot-melt resin composition may be applied continuously or intermittently depending on the shape of the cured product to be manufactured.

[0078] It is preferable to allow the above moisture-curing polyurethane hot-melt resin composition to dry and cure after application.

[0079] [III. Adhesives] The adhesives of this disclosure contain the moisture-curable polyurethane hot-melt resin composition described in section I. Moisture-curing hot-melt resin composition above. The adhesives of this disclosure are usually solvent-free, but may contain solvents such as water or organic solvents.

[0080] The adhesive of this disclosure can be formed into a film and used in the form of an adhesive film. The adhesive film can be formed by applying an adhesive containing the moisture-curable polyurethane hot-melt resin composition described in section 1, "Moisture-curable polyurethane hot-melt resin composition," onto a release substrate such as a polyethylene terephthalate (PET) film, and drying it. The application method of the adhesive of this disclosure can be the same as the application method described in section II, "Cured product."

[0081] The thickness of the adhesive film described above is not limited as it can be set appropriately depending on the application, but for example, it can be in the range of 5 μm to 300 μm.

[0082] [IV. Goods] The articles of this disclosure have at least a cured layer of the moisture-curable polyurethane hot-melt resin composition of this disclosure as described in section I. Moisture-curing hot-melt resin composition above.

[0083] An example of an embodiment of the article of the present disclosure is an embodiment having at least a first adherend and a layer provided on the first adherend, which is made of a cured product of the moisture-curable polyurethane hot-melt resin composition of the present disclosure.

[0084] Another example of an embodiment of an article of the present disclosure includes a first adherend and a coating layer formed on at least one surface of the first adherend by a cured product of a moisture-curable polyurethane hot-melt resin composition of the present disclosure.

[0085] Another example of an embodiment of an article of the present disclosure is an embodiment comprising a first adherend, a second adherend, and an adhesive layer for bonding the first adherend and the second adherend, wherein the adhesive layer is a cured layer of an adhesive containing the moisture-curable polyurethane hot-melt resin composition of the present disclosure.

[0086] Examples of the adherends mentioned above include substrates, films, sheets, etc. When the article of this disclosure has two or more adherends, the first adherend and the second adherend may be the same or different. For example, one of the first adherend and the second adherend may be a substrate, and the other adherend may be a film or sheet. Alternatively, for example, one of the first adherend and the second adherend may be a resin substrate, and the other adherend may be a substrate made of a material other than resin.

[0087] Examples of the above-mentioned substrates include fiber substrates, glass substrates, wood substrates, metal substrates, ceramic substrates, and resin substrates. More specifically, wood substrates such as plywood, MDF (medium-density fiberboard), and particleboard; metal substrates such as aluminum, iron, copper, nickel, and silicon; ceramic substrates such as aluminum nitride, alumina, and silicon carbide; fiber substrates such as nonwoven fabrics, woven fabrics, and knitted fabrics made from polyester fibers, polyethylene fibers, nylon fibers, acrylic fibers, polyurethane fibers, acetate fibers, rayon fibers, polylactic acid fibers, cotton, hemp, silk, wool, glass fiber, carbon fiber, and blends thereof; impregnated substrates obtained by impregnating nonwoven fabric with a resin such as polyurethane resin; composite substrates obtained by further providing a porous layer on a nonwoven fabric; paper; and resin substrates. The above-mentioned substrates may be flat plates or may have parts with complex shapes such as grooves, R-shaped parts, and reverse R-shaped parts.

[0088] As the above-mentioned sheets or films, for example, sheets or films obtained using resins such as polyolefin, polyester, polyamide, polystyrene, polycarbonate, vinyl chloride, ethylene-vinyl acetate copolymer, polyvinyl alcohol, and polypropylene, as well as paper, metal foil, veneer, etc., can be used. In addition, the above-mentioned sheets or films may also be those that are generally referred to as decorative paper, base paper for decorative panels, decorative sheets, etc., and which have decorative plain or multi-colored or patterned surfaces. Furthermore, the back surface may be treated with a primer using resin or the like.

[0089] Furthermore, the above-mentioned substrates include components used in electronic devices or mounting substrates for such components. Specifically, these include, but are not limited to, substrates for electronic devices such as printed wiring boards (especially electronic circuit boards or electronic circuit mounting substrates); substrates for semiconductor devices; and substrates for semiconductor devices on which semiconductor elements are mounted. As materials for substrates for electronic devices or electronic materials (e.g., printed wiring boards), various materials can be used, such as plastic substrates; metallic substrates such as aluminum, copper, nickel, and silicon; ceramic substrates such as aluminum nitride, alumina, and silicon carbide; and glass plates, which can be appropriately selected according to the application.

[0090] The method for manufacturing the articles of this disclosure is not particularly limited, and a method can be used in which the moisture-curable polyurethane hot melt resin composition of this disclosure is applied to a substrate using the application method described in the section [II. Cured Products] above, and then moisture-cured. If the articles of this disclosure have two or more substrates, the moisture-curable polyurethane hot melt resin composition of this disclosure can be applied to the first substrate, the second substrate can be bonded onto the moisture-curable polyurethane hot melt resin composition, and then pressed together using a roll press, flat press, belt press, or the like. After drying and curing the moisture-curable polyurethane hot melt resin composition as necessary, an article can be manufactured in which the two substrates are joined via a cured product of the moisture-curable polyurethane hot melt resin composition of this disclosure.

[0091] Specifically, the articles described herein include building materials such as building panels and decorative boards; automotive interior materials; automotive parts; battery components; and electronic components such as wiring boards. Among these, it is preferable that the articles described herein are molded components (for example, additive manufactured components).

[0092] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and produces similar effects is included within the technical scope of this disclosure. [Examples]

[0093] The present invention will be described in more detail below using examples and comparative examples.

[0094] [Method for measuring number-average molecular weight] The number-average molecular weight is the value measured by gel permeation chromatography (GPC) under the following conditions.

[0095] Measurement device: High-speed GPC device (HLC-8220GPC manufactured by Tosoh Corporation) Columns: The following columns manufactured by Tosoh Corporation were used, connected in series. "TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (Differential Refractometer) Column temperature: 40℃ Eluent: Tetrahydrofuran (THF) Flow rate: 1.0mL / min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass) Standard samples: Calibration curves were prepared using the following standard polystyrene samples.

[0096] (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.

[0097] [Example 1] Preparation of moisture-curing polyurethane hot melt resin composition (PUR-A) 22.5 parts by mass of polyester polyol (a2) (reaction product of neopentyl glycol and hydrogenated phthalic anhydride, number average molecular weight: 2,000, abbreviated as "NPG / HHPA" in the table below), 22.5 parts by mass of polyester polyol (a1) (reaction product of 1,6-hexanediol and hydrogenated phthalic anhydride, number average molecular weight: 2,000, abbreviated as "HG / HHPA" in the table below), crystalline polyester polyol (a3-1) (reaction product of 1,6-hexanediol and dodecanedioic acid, number average molecular weight: A mixture of 20 parts by mass of 3,500 (abbreviated as "HG / DDA" in the table below), 5 parts by mass of aromatic polyester polyol (a4) (reaction product of neopentyl glycol and phthalic anhydride, number average molecular weight: 1,000, abbreviated as "NPG / oPA" in the table below), and 10 parts by mass of crystalline polyester polyol (a3-2) (polycaprolactone polyol, number average molecular weight: 80,000, abbreviated as "PCL" in the table below) was dried under reduced pressure at 110°C until the moisture content was 0.05% or less. Next, the dehydrated mixture was cooled to 90°C, and 20 parts by mass of 4,4-methylene diisocyanate (abbreviated as "MDI" in the table below) were added. The temperature was then raised to 120°C, and the mixture was reacted for 2 hours until the isocyanate group content became constant to obtain a reactive urethane hot melt resin, which was then prepared as a moisture-curing polyurethane hot melt resin composition (PUR-A).

[0098] [Example 2] Preparation of moisture-curing polyurethane hot melt resin composition (PUR-B) Polyester polyol (a2) (reaction product of neopentyl glycol and hydrogenated phthalic anhydride, number average molecular weight: 2,000, abbreviated as "NPG / HHPA" in the table below) 5 parts by mass, polyester polyol (a1) (reaction product of 1,6-hexanediol and hydrogenated phthalic anhydride, number average molecular weight: 2,000, hereinafter abbreviated as "HG / HHPA") 40 parts by mass, crystalline polyester polyol (a3-1) (reaction product of 1,6-hexanediol and dodecanedioic acid, number average molecular weight: 3, A mixture of 20 parts by mass of 500 (abbreviated as "HG / DDA" in the table below), 5 parts by mass of aromatic polyester polyol (a4) (reaction product of neopentyl glycol and phthalic anhydride, number average molecular weight: 1,000, abbreviated as "NPG / oPA" in the table below), and 10 parts by mass of crystalline polyester polyol (a3) ​​(polycaprolactone polyol, number average molecular weight: 80,000, abbreviated as "PCL" in the table below) was dried under reduced pressure at 110°C until the moisture content was 0.05% or less. The dehydrated mixture was then cooled to 90°C, 20 parts by mass of 4,4-methylene diisocyanate (MDI) was added, and the temperature was raised to 120°C. The mixture was reacted for 2 hours until the isocyanate group content became constant to obtain a reactive urethane hot melt resin, which was then used as a moisture-curing polyurethane hot melt resin composition (PUR-B).

[0099] [Comparative Example 1] Preparation of moisture-curing polyurethane hot melt resin composition (PUR-C) A reactive urethane hot melt resin was obtained in the same manner as in Example 1, except that the amount of polyester polyol (a2) (a reaction product of neopentyl glycol and hydrogenated phthalic anhydride, number average molecular weight: 2,000, abbreviated as "NPG / HHPA" in the table below) was changed from 22.5 parts by mass to 45 parts by mass, and polyester polyol (a1) (a reaction product of 1,6-hexanediol and hydrogenated phthalic anhydride, number average molecular weight: 2,000, abbreviated as "HG / HHPA" in the table below) was changed from 22.5 parts by mass to 0 parts by mass, to obtain a moisture-curing polyurethane hot melt resin composition (PUR-C).

[0100] [Comparative Example 2] Preparation of moisture-curing polyurethane hot melt resin composition (PUR-D) A reactive urethane hot melt resin was obtained in the same manner as in Example 1, except that the amount of polyester polyol (a2) (a reaction product of neopentyl glycol and hydrogenated phthalic anhydride, number average molecular weight: 2,000, abbreviated as "NPG / HHPA" in the table below) was changed from 22.5 parts by mass to 0 parts by mass, and polyester polyol (a1) (a reaction product of 1,6-hexanediol and hydrogenated phthalic anhydride, number average molecular weight: 2,000, abbreviated as "HG / HHPA" in the table below) was changed from 22.5 parts by mass to 45 parts by mass, to obtain a moisture-curing polyurethane hot melt resin composition (PUR-D).

[0101] [evaluation] The moisture-curing urethane hot-melt resin compositions obtained in the examples and comparative examples were evaluated as follows. The results are shown in the table.

[0102] <Moisture permeability> A release film made of polyethylene terephthalate was placed on a glass plate whose surface temperature was adjusted to 100°C. A moisture-curing urethane hot-melt resin composition, heated and melted at 120°C for 1 hour, was applied using an applicator to a film thickness of 100 μm. After curing for 1 week in an atmosphere of 23°C and 50% relative humidity, the cured film of the moisture-curing urethane hot-melt resin composition was peeled off the release film and used as a sample for measurement. The water vapor permeability of the sample was measured and evaluated based on the water vapor permeability cup method (JIS Z0208 Method B). (Evaluation Criteria) T:10g / m2・24h or less F: Greater than 10g / m2·24h

[0103] <Coating strength> A moisture-curing polyurethane hot-melt resin composition, heated and melted at 120°C for 1 hour, was applied to a release film made of polyethylene terephthalate using an applicator to a film thickness of 100 μm. After curing for 1 week under conditions of 23°C and 50% humidity, the cured film of the moisture-curing polyurethane hot-melt resin was peeled off the release film and used as a sample for measurement. The sample was cut into strips 10 mm wide and 50 mm long, and tensile tested using a tensile testing machine "Autograph AG-I" (manufactured by Shimadzu Corporation) at a temperature of 23°C and a crosshead speed of 10 mm / second. The 100% modulus (MPa) and elongation at break (%) were measured and evaluated according to the following criteria. (100% Modulus Evaluation Criteria) T: 100% Modulus is 30 MPa or less F: 100% Modulus exceeds 30 MPa (Evaluation criteria for elongation at break) T: Elongation is 100% or more F: Elongation is less than 100%

[0104] <Adhesion> A moisture-curing polyurethane hot-melt resin composition, heated and melted at 120°C for 1 hour, was applied to substrate 1 (5.5 mm MDF) using a roll coater to a film thickness of 100 μm. When the surface temperature of the coating reached 40°C, substrate 2 (2.7 mm MDF, surface temperature: 23°C) was bonded to it, roll-pressed at a pressure of 1.2 MPa, and then cured at 23°C and 50 RH% to obtain laminate 1. Furthermore, under the same conditions, base material 3 (2.7 mm MDF, surface temperature: 10°C) was bonded together, roll-pressed at a pressure of 1.2 MPa, and then cured at 10°C and 50 RH% to obtain laminate 2. A chisel was used to make a crack in the adhesive surface of the resulting laminates 1 and 2 (between substrate 1 and substrate 2 or substrate 3), and the adhesion to the substrate (at room temperature and low temperature) was determined from the peeling state according to the following criteria. ○: Adhesion present (Delamination state: Material failure) ×: No adhesion (Detachment state: Interfacial detachment)

[0105] [Table 1]

[0106] The above results confirm that the cured film obtained using the moisture-curing urethane hot melt resin composition of the example exhibits low moisture permeability and high moisture-proof performance. Furthermore, it was confirmed that it exhibits high 100% modulus value and tensile strength, as well as high flexibility. In addition, the moisture-curing urethane hot melt resin composition of the example showed excellent adhesion to both substrates at room temperature (23°C) and low temperature (10°C). These points suggest that the moisture-curing urethane hot melt resin composition of the example exhibits excellent adhesion not only at room temperature but also in low-temperature environments (low-temperature adhesion).

[0107] On the other hand, the cured film obtained from the moisture-curing urethane hot-melt resin composition of Comparative Example 1 had the same moisture-proof performance as the example, but the flexibility of the film was inferior. Furthermore, the moisture-curing urethane hot-melt resin composition of Comparative Example 1 had poor low-temperature adhesion. The cured film obtained using the moisture-curing urethane hot-melt resin composition of Comparative Example 2 had high moisture permeability and poor moisture-proof performance.

Claims

1. A moisture-curing polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, which is a reaction product of a polyol (A) and a polyisocyanate (B), The polyol (A) is A polyester polyol (a1) having structural units derived from linear aliphatic glycols and structural units derived from alicyclic polybasic acids, A polyester polyol (a2) having structural units derived from branched aliphatic glycols and structural units derived from alicyclic polybasic acids, A moisture-curing polyurethane hot-melt resin composition containing [the specified ingredient].

2. The moisture-curing polyurethane hot-melt resin composition according to claim 1, wherein the content of the polyester polyol (a1) is equal to or greater than the content of the polyester polyol (a2).

3. The moisture-curing polyurethane hot-melt resin composition according to claim 1, wherein the content ratio of the polyester polyol (a1) to the polyester polyol (a2) is 50 / 50 to 95 / 5 by mass ratio.

4. The moisture-curing polyurethane hot-melt resin composition according to claim 1, wherein the total content of the polyester polyol (a1) and the polyester polyol (a2) is in the range of 20% to 70% by mass in 100% by mass of the polyol (A).

5. The moisture-curing polyurethane hot-melt resin composition according to claim 1, wherein the polyol (A) further contains a crystalline polyester polyol (a3).

6. The moisture-curing polyurethane hot-melt resin composition according to claim 5, wherein the content of the crystalline polyester polyol (a3) ​​is in the range of 10% to 40% by mass in 100% by mass of the polyol (A).

7. The moisture-curing polyurethane hot-melt resin composition according to claim 1, wherein the polyol (A) further contains an aromatic polyester polyol (a4).

8. The moisture-curing polyurethane hot-melt resin composition according to claim 7, wherein the content of the aromatic polyester polyol (a4) is in the range of 5% to 20% by mass in 100% by mass of the polyol (A).

9. A cured product of a moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 8.

10. An adhesive comprising the moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 8.

11. An article having at least a cured layer of a moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 8.

12. The article according to claim 11, which is a molded component.

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