Moisture-curing polyurethane hot-melt resin composition, coating agent and cured product, as well as articles and methods for manufacturing articles.

Abstract

The objective is to provide a moisture-curing polyurethane hot-melt resin composition, etc., that has high sprayability and can form a thin film with high moisture-proof performance. [Solution] A moisture-curable polyurethane hot melt resin composition containing a urethane prepolymer (i) having an isocyanate group, wherein the urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B), and the polyol (A) at least essentially contains an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), and the content of the alicyclic polyester polyol (a1) in the polyol (A) is 50% by mass or more.

Description

Technical Field

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

Background Art

[0002] At the time of manufacturing electronic devices, in order to protect printed circuit boards and components from moisture and the like, a "conformal coating technology" of thinly applying a moisture-proof coating agent to the surfaces of substrates, electronic components, etc. is known. Conventionally, solvent-based urethane resins have been used as the moisture-proof coating agent (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, solvent-based moisture-proof coating agents have problems in terms of safety due to solvents and environmental aspects. In addition, in order to obtain sufficient moisture-proof properties, the coating film tends to become thick, and a thin film with high moisture-proof properties is required. On the other hand, when using a non-solvent-based moisture-proof coating agent instead of a solvent-based moisture-proof coating agent, when trying to form a coating film by spray coating, stringing or the like is likely to occur, and it may not be suitable for spray coating.

[0005] Therefore, as a result of intensive studies to solve the problems of solvent-based moisture-proof coating agents and conventional non-solvent-based moisture-proof coating agents, the inventors have found a moisture-curable polyurethane hot melt resin composition with high spray suitability and capable of forming a coating film (cured film) with a thin film and high moisture-proof performance as a non-solvent-based moisture-proof coating agent.

[0006] In other words, the present disclosure aims to provide a moisture-curing polyurethane hot-melt resin composition that has high sprayability and can form a thin film with high moisture-proof performance. Furthermore, this disclosure aims to provide coating agents and cured products using the above-mentioned moisture-curing polyurethane hot-melt resin composition, as well as articles and methods for manufacturing articles. [Means for solving the problem]

[0007] This disclosure has the following embodiments. [1] A moisture-curable polyurethane hot melt resin composition comprising a urethane prepolymer (i) having an isocyanate group, wherein the urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B), and the polyol (A) at least essentially comprises an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), and the content of the alicyclic polyester polyol (a1) in the polyol (A) is 50% by mass or more. [2] A moisture-curable polyurethane hot melt resin composition comprising a urethane prepolymer (i) having an isocyanate group, wherein the urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B), and the polyol (A) at least essentially comprises an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), wherein the content of the crystalline polyester polyol (a2) is 10% to 30% by mass, the content of the aromatic polyester polyol (a3) ​​is 10% to 30% by mass, and the content of high molecular weight polycaprolactone polyol (a4) in the polyol (A) is less than 10% by mass. [3] A moisture-curable polyurethane hot melt resin composition comprising a urethane prepolymer (i) having an isocyanate group, wherein the urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B), and the polyol (A) at least essentially comprises an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), wherein the content of the crystalline polyester polyol (a2) is 10% to 30% by mass, the content of the aromatic polyester polyol (a3) ​​is 10% to 30% by mass, and the melt viscosity at 120°C is 5 Pa·s or less. [4] The moisture-curing polyurethane hot-melt resin composition according to any one of [1] to [3] above, wherein the alicyclic polyester polyol (a1) comprises at least an alicyclic polyester polyol (a1-1) having structural units derived from a branched aliphatic polyol and structural units derived from an alicyclic polybasic acid. [5] A moisture-curing polyurethane hot-melt resin composition according to any one of [1] to [4] above, wherein the content of high molecular weight polycaprolactone polyol (a4) in the polyol (A) is less than 10% by mass. [6] A moisture-curing polyurethane hot-melt resin composition according to any of [1] to [5] above, wherein the melt viscosity at 120°C is 5 Pa·s or less. [7] A coating agent comprising the moisture-curing polyurethane hot-melt resin composition described in any of [1] to [6] above. [8] An adhesive comprising the moisture-curing polyurethane hot-melt resin composition described in any of [1] to [6] above. [9] A cured product of a moisture-curing polyurethane hot melt resin composition as described in any of [1] to [6] above.

[10] An article having a cured product of a moisture-curing polyurethane hot melt resin composition as described in any of [1] to [6] above.

[11] An article having a cured product of any of the moisture-curing polyurethane hot melt resin compositions described in [1] to [6] above on an electronic circuit board.

[12] A method for manufacturing an article, comprising spray-applying a moisture-curing polyurethane hot-melt resin composition described in any of [1] to [6] above to an adherend.

[13] A method for manufacturing an article, comprising spray-applying a moisture-curing polyurethane hot-melt resin composition according to any of [1] to [6] above to an electronic circuit board or electronic components on the electronic circuit board. [Effects of the Invention]

[0008] The moisture-curing polyurethane hot-melt resin composition of this disclosure exhibits high sprayability, and a thin, highly moisture-resistant cured film can be formed by spray application. In particular, the moisture-curing polyurethane hot-melt resin composition of this disclosure can be suitably used as a conformal coating agent. [Modes for carrying out the invention]

[0009] 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 an isocyanate group. The urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B), and the polyol (A) essentially includes at least an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3).

[0010] The moisture-curing polyurethane hot-melt resin composition disclosed herein has excellent sprayability, and a thin, highly moisture-resistant cured film can be easily formed by spray application.

[0011] [Urethane prepolymer (i)] In this disclosure, the urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B). In other words, the urethane prepolymer (i) includes structural units derived from the polyol (A) and structural units derived from the polyisocyanate (B).

[0012] <Polyol (A)> The above polyol (A) includes, at least, an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3).

[0013] <<Alicyclic polyester polyol (a1)>> The above-mentioned alicyclic polyester polyol (a1) is a polyester polyol having structural units derived from alicyclic polybasic acids. Examples of polyester polyols having structural units derived from alicyclic polybasic acids include alicyclic polyester polyols (a1-1) having structural units derived from branched aliphatic glycols and structural units derived from alicyclic polybasic acids, and alicyclic polyester polyols (a1-2) having structural units derived from linear aliphatic glycols and structural units derived from alicyclic polybasic acids.

[0014] -Alicyclic polyester polyol (a1-1)- The above alicyclic polyester polyol (a1-1) has structural units derived from branched aliphatic glycols and structural units derived from alicyclic polybasic acids. In other words, the above alicyclic polyester polyol (a1-1) is a reaction product that requires a polyhydric alcohol mainly composed of a branched aliphatic glycol and a polybasic acid mainly composed of an alicyclic polybasic acid as essential raw materials. The above alicyclic polyester polyol (a1-1) has hydroxyl groups, preferably two or more hydroxyl groups.

[0015] A branched aliphatic glycol is a compound having a main chain with two or more hydroxyl groups in the straight-chain portion and at least one side-chain group bonded to the main chain. As the side-chain group of the branched aliphatic glycol, an alkyl group is preferred, and specifically, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, etc. can be mentioned.

[0016] Examples of the branched aliphatic glycol include branched aliphatic glycols such as 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, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 2,4-diethyl-1,5-pentanediol; 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-based compounds, γ-valerolactone-based compounds, 4,4-dimethyltetrahydro-2H-pyran-2-one compounds, etc. These may be used alone or in combination of two or more. Among them, from the viewpoint of the balance between appropriate open time and moisture-proof performance at low temperature, one or more selected from the group consisting of neopentyl glycol, 3-methyl-1,5-pentanediol, and 2-methyl-1,3-propanediol are preferred.

[0017] The polyhydric alcohol that is a raw material for the alicyclic polyester polyol (a1-1) must contain a branched aliphatic glycol, but it is allowed to contain polyhydric alcohols other than the branched aliphatic glycol as long as the function of the alicyclic polyester polyol (a1-1) is not impaired. The content of the branched aliphatic glycol in the polyhydric alcohol that is a raw material for the alicyclic polyester polyol (a1-1) 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.

[0018] Examples of the above-mentioned alicyclic polybasic acids 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, and 1,4-cyclononane Examples include dicarboxylic acids, 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 acids, 1,2-cyclohexanediacetic acid, 1,3-cyclohexanediacetic acid, 1,4-cyclohexanediacetic acid, and their acid anhydrides; anhydrides such as hydrogenated phthalic acid, cyclohexanediadipate, etc. These may be used alone or in combination of two or more. In particular, from the viewpoint of improving moisture-proof performance, dicarboxylic acids having a cyclohexane ring or derivatives thereof are preferred, 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, with hydrogenated phthalic anhydride being even more preferred.

[0019] The polybasic acid used as a raw material for the above-mentioned alicyclic polyester polyol (a1-1) may contain polybasic acids other than alicyclic polybasic acids, provided that the function of the above-mentioned alicyclic polyester polyol (a1-1) is not impaired. 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 above-mentioned alicyclic polyester polyol (a1-1) is preferably 99% by mass or more, and is particularly preferably substantially 100% by mass.

[0020] The number-average molecular weight (Mn) of the above-mentioned alicyclic polyester polyol (a1-1) is preferably 500 to 10,000, and more preferably 800 to 5,000, from the viewpoint of obtaining excellent moisture resistance and adhesive strength. The number-average molecular weight of the above-mentioned alicyclic polyester polyol (a1-1) is shown as the value measured by gel permeation chromatography (GPC) under the conditions described in the examples below.

[0021] The above alicyclic polyester polyol (a1-1) 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 alicyclic polyester polyol (a1-1) 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 alicyclic polyester polyol (a1-1). Furthermore, the content of structural units derived from alicyclic polybasic acids in the above alicyclic polyester polyol (a1-1) 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 alicyclic polyester polyol (a1-1).

[0022] The above-mentioned alicyclic polyester polyol (a1-1) is obtained by polycondensation of an alicyclic polybasic acid and a branched aliphatic glycol using a conventionally known method. The above polycondensation reaction can be carried out, for example, by charging an alicyclic polybasic acid and 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 proceeding with the esterification reaction by dehydration condensation. The reaction temperature for the above polycondensation reaction is preferably in the range of 140°C to 240°C, more preferably in the range of 170°C to 230°C, and the reaction time is preferably in the range of 5 hours to 20 hours, more preferably in the range of 7 hours to 17 hours.

[0023] 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 the alicyclic polybasic acid and linear aliphatic glycol.

[0024] Examples of the polymerization inhibitors mentioned above 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 the alicyclic polybasic acid and linear aliphatic glycol.

[0025] -Alicyclic polyester polyol (a1-2)- The above alicyclic polyester polyol (a1-2) has structural units derived from linear aliphatic glycols and structural units derived from alicyclic polybasic acids. In other words, the above alicyclic polyester polyol (a1-2) 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. The above alicyclic polyester polyol (a1-2) has two or more hydroxyl groups.

[0026] Linear aliphatic glycols are compounds that have a structure in which one hydroxyl group is substituted on each of the two carbon atoms of a linear aliphatic hydrocarbon, and do not have side chains. Examples of the above-mentioned linear aliphatic glycols include 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 (dodecanediol), 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, and 1,20-eicosanediol; and ether-linked glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, polytetramethylene glycol, polyethylene glycol, and polypropylene glycol. These may be used individually or in combination of two or more.

[0027] The polyhydric alcohol used as a raw material for the above-mentioned alicyclic polyester polyol (a1-2) must contain a linear aliphatic glycol, but it is permissible to include polyhydric alcohols other than linear aliphatic glycols as long as the function of the above-mentioned alicyclic polyester polyol (a1-2) is not impaired. From the viewpoint of ensuring the physical properties exhibited by the inclusion of the above-mentioned alicyclic polyester polyol (a1-2) and the effects of the resin composition of this disclosure, the content of linear aliphatic glycol in the polyhydric alcohol used as a raw material for the above-mentioned alicyclic polyester polyol (a1-2) 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.

[0028] Examples of the alicyclic polybasic acid mentioned above include specific compounds of alicyclic polybasic acids used as raw materials for the alicyclic polyester polyol (a1-1) described above. Alicyclic polybasic acids may be used alone or in combination of two or more types. Details of the alicyclic polybasic acid in the alicyclic polyester polyol (a1-2) described above are the same as details of the alicyclic polybasic acid in the alicyclic polyester polyol (a1-1) described above.

[0029] The polybasic acid used as a raw material for the above-mentioned alicyclic polyester polyol (a1-2) may contain polybasic acids other than alicyclic polybasic acids, provided that the function of the above-mentioned alicyclic polyester polyol (a1-2) is not impaired. 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 above-mentioned alicyclic polyester polyol (a1-2) is preferably 99% by mass or more, and is particularly preferably substantially 100% by mass.

[0030] The number-average molecular weight (Mn) of the above-mentioned alicyclic polyester polyol (a1-2) 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-mentioned alicyclic polyester polyol (a1-2) is shown as the value measured by gel permeation chromatography (GPC) under the conditions described in the examples below.

[0031] The above-mentioned alicyclic polyester polyol (a1-2) 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-mentioned alicyclic polyester polyol (a1-2) 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 in the above-mentioned alicyclic polyester polyol (a1-2). Furthermore, the content of structural units derived from alicyclic polybasic acids in the above-mentioned alicyclic polyester polyol (a1-2) 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-mentioned alicyclic polyester polyol (a1-2).

[0032] The above-mentioned alicyclic polyester polyol (a1-2) is obtained by polycondensation of an alicyclic polybasic acid and a linear aliphatic glycol using a conventionally known method. The above polycondensation reaction can be carried out, for example, by charging an alicyclic polybasic acid and a linear aliphatic polyol into a reaction vessel, adding a high-boiling point solvent such as xylene, an esterification catalyst, a polymerization inhibitor, etc. as needed, and proceeding with dehydration condensation to carry out 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-mentioned preparation of alicyclic polyester polyol (a1-1), as well as specific examples and amounts of the esterification catalyst and polymerization inhibitor used in the above-mentioned preparation of alicyclic polyester polyol (a1-1).

[0033] -Alicyclic polyester polyol (a1)- The content of the alicyclic polyester polyol (a1) in the polyol (A) (total content of the alicyclic polyester polyol (a1-1) and the alicyclic polyester polyol (a1-2)) is preferably 50% by mass or more, may be 55% by mass or more, or may be 60% by mass or more, based on 100% by mass of the polyol (A). Furthermore, the upper limit of the content of the alicyclic polyester polyol (a1) in 100% by mass of the polyol (A) is preferably 80% by mass or less, although this depends on the content of other components. More specifically, the content of the alicyclic polyester polyol (a1) in 100% by mass of the polyol (A) is more preferably in the range of 50% by mass to 75% by mass, and even more preferably in the range of 50% by mass to 65% by mass. By setting the content of the alicyclic polyester polyol (a1) in the polyol (A) within the above range, the resin composition of this disclosure exhibits excellent moisture resistance and sprayability.

[0034] The above-mentioned alicyclic polyester polyol (a1) comprises at least one of the above-mentioned alicyclic polyester polyol (a1-1) and the above-mentioned alicyclic polyester polyol (a1-2). In particular, it is preferable that it comprises at least alicyclic polyester polyol (a1-1). By comprising alicyclic polyester polyol (a1-1), the resin composition of this disclosure has excellent moisture resistance and sprayability, and a thin and more homogeneous coating film can be formed by spray coating. The content of alicyclic polyester polyol (a1-1) in the above-mentioned alicyclic polyester polyol (a1) is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more. When the above-mentioned alicyclic polyester polyol (a1) contains both the above-mentioned alicyclic polyester polyol (a1-1) and the above-mentioned alicyclic polyester polyol (a1-2), the content ratio of the above-mentioned alicyclic polyester polyol (a1-1) to the above-mentioned alicyclic polyester polyol (a1-2) [(a1-1) / (a1-2)] is preferably in the range of 50 / 50 to 95 / 5 by mass ratio, 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-mentioned relationship between the content of the above-mentioned alicyclic polyester polyol (a1-1) and the above-mentioned alicyclic polyester polyol (a1-2), the resin composition of this disclosure has excellent moisture resistance and spray suitability, and a thin and more homogeneous coating film can be formed by spray coating.

[0035] <<Crystalline polyester polyol (a2)>> The polyol (A) described above includes crystalline polyester polyols (a2) other than the alicyclic polyester polyol (a1) described above. By further including crystalline polyester polyols (a2) in the polyol (A), the resin composition of this disclosure can exhibit superior adhesion (initial adhesive strength and final adhesive strength). The crystalline polyester polyols (a2) may be used alone or in combination of two or more types. The final adhesive strength refers to the final adhesive strength of the moisture-curable polyurethane hot-melt resin composition after curing.

[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 (a2), for example, a crystalline polyester polyol (a2-1) having structural units derived from an aliphatic compound having two or more hydroxyl groups and structural units derived from a polybasic acid, a crystalline polyester polyol (a2-2) having structural units derived from an alicyclic compound having two or more hydroxyl groups and structural units derived from a polybasic acid, etc. can be used.

[0038] Crystalline polyester polyols having structural units derived from alicyclic polybasic acids are not included in crystalline polyester polyols (a2) and are classified as alicyclic polyester polyols (a1) according to the type of structural units derived from polyhydric alcohols. Furthermore, high molecular weight polycaprolactone polyols (a4), which will be described later, are not included in crystalline polyester polyols (a2).

[0039] Crystalline polyester polyol (a2-1) having structural units derived from aliphatic compounds having two or more hydroxyl groups and structural units derived from polybasic acids is a reaction product that requires at least a polyhydric alcohol mainly composed of aliphatic compounds having two or more hydroxyl groups and a polybasic acid as essential raw materials. Furthermore, crystalline polyester polyol (a2-2) having structural units derived from alicyclic compounds having two or more hydroxyl groups and structural units derived from polybasic acids is a reaction product that requires at least a polyhydric alcohol mainly composed of alicyclic compounds having two or more hydroxyl groups and a polybasic acid as essential raw materials.

[0040] 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, and 1,12-dodecanediol. Examples include diethylene glycol, triethylene 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, and pentaerythritol. These may be used individually or in combination of two or more.

[0041] 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.

[0042] The polyhydric alcohols used as reaction raw materials for the above-mentioned crystalline polyester polyols (a2-1) and (a2-2) 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 (a2) is not impaired. The content of aliphatic and / or alicyclic compounds having two or more hydroxyl groups in the polyhydric alcohol 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.

[0043] As the polybasic acid used as a reaction raw material for the above-mentioned crystalline polyester polyols (a2-1) and (a2-2), for example, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanediic acid, etc., can be used. 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 dodecanediic acid are preferred in order to enhance crystallinity and obtain even better adhesion.

[0044] In particular, from the viewpoint of crystallinity expression, the above crystalline polyester polyol (a2) is preferably mainly composed of crystalline polyester polyol (a2-1) having structural units derived from aliphatic compounds having two or more hydroxyl groups and structural units derived from polybasic acids, and more preferably is crystalline polyester polyol (a2-1) substantially having structural units derived from aliphatic compounds having two or more hydroxyl groups and structural units derived from polybasic acids. Specifically, the content of crystalline polyester polyol (a2-1) having structural units derived from aliphatic compounds having two or more hydroxyl groups and structural units derived from polybasic acids in the above crystalline polyester polyol (a2) is preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 100% by mass, per 100% by mass of the above crystalline polyester polyol (a2). By setting the content of crystalline polyester polyol (a2-1) in the above crystalline polyester polyol (a2) to the above range, the decrease in crystallinity due to the presence of an alicyclic structure can be suppressed.

[0045] The number-average molecular weight of the above-mentioned crystalline polyester polyol (a2) is preferably in the range of 500 to 10,000, and more preferably in the range of 1,000 to 6,000. The number-average molecular weight of the crystalline polyester polyol (a2) is shown as the value measured by gel permeation chromatography (GPC) under the conditions described in the examples below.

[0046] The content of the above-mentioned crystalline polyester polyol (a2) is preferably in the range of 10% to 30% by mass, and more preferably in the range of 20% to 30% by mass, of 100% by mass of polyol (A). By setting the content of the above-mentioned crystalline polyester polyol (a2) in polyol (A) to the above range, a good balance between initial solidification and moisture resistance can be achieved. If the content is too high, moisture resistance may decrease, and if it is too low, initial solidification may decrease.

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

[0048] Examples of the above-mentioned aromatic polyester polyol (a3) ​​include: aromatic polyester polyol (a3-1) 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 (a3-2) 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 (a3-1) 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 an aliphatic and / or alicyclic compound having two or more hydroxyl groups and an aromatic polybasic acid 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 (a3-1) described above, can be the same as the aliphatic and / or alicyclic compound having two or more hydroxyl groups in the "crystalline polyester polyol (a2)" described above.

[0051] As the aromatic polybasic acid used as a raw material for the above-mentioned aromatic polyester polyol (a3-1), 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 (a3-1) 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 (a3-1) 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 (a3-1). Furthermore, the content of structural units derived from aromatic polybasic acids in the above aromatic polyester polyol (a3-1) 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 above aromatic polyester polyol (a3-1).

[0053] The aromatic polyester polyol (a3-2) 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 an aromatic compound having two or more hydroxyl groups and a polybasic acid as at least 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 (a3-2), examples include bisphenol A, bisphenol F, and their alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts. These may be used individually or in combination of two or more.

[0055] As aromatic compounds having two or more hydroxyl groups that serve as raw materials for the above-mentioned aromatic polyester polyol (a3-2), 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.

[0056] As the polybasic acid used as a raw material for the aromatic polyester polyol (a3-2) above, the following aliphatic or alicyclic polybasic acids can be used: aromatic polybasic acids exemplified as raw materials for the aromatic polyester polyol (a3-1) above, 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, anhydrous itacone, etc. These may be used individually or in combination of two or more.

[0057] The above aromatic polyester polyol (a3-2) 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 (a3-2) 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 (a3-2).

[0058] The number-average molecular weight of the above aromatic polyester polyol (a3) ​​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 (a3) ​​is shown as the value measured by gel permeation chromatography (GPC) under the conditions described in the examples below.

[0059] The content of the aromatic polyester polyol (a3) ​​is preferably in the range of 10% to 30% by mass, and more preferably in the range of 10% to 20% by mass, per 100% by mass of polyol (A). By setting the content of aromatic polyester polyol (a3) ​​in polyol (A) within the above range, high strength and stability of initial and final adhesive strength can be achieved, low melt viscosity can be achieved, and sprayability is also excellent. If the content is too high, the melt viscosity may become too high and handling performance may decrease, and if it is too low, the final adhesive strength may not be sufficiently achieved.

[0060] <<Other Polyols>> The polyol (A) described above may contain other polyols besides those mentioned above. Examples of these other polyols include polyacrylic polyols, polycarbonate polyols, polyether polyols, polybutadiene polyols, and polycaprolactone polyols other than the high molecular weight polycaprolactone polyol (a4) described later. These polyols may be used individually or in combination of two or more.

[0061] <<Polyol (A)>> The polyol (A) may contain high molecular weight polycaprolactone polyol (a4), but it is preferable that the content of high molecular weight polycaprolactone polyol (a4) in the polyol (A) is low, and it is particularly preferable that it is substantially absent. Specifically, the content of high molecular weight polycaprolactone polyol (a4) in the polyol (A) is preferably less than 10% by mass, more preferably 5% by mass or less, even more preferably 3% by mass or less, preferably 1% by mass or less, and 0% by mass, i.e., it is particularly preferable that the polyol (A) does not contain high molecular weight polycaprolactone polyol (a4). By setting the content of high molecular weight polycaprolactone polyol (a4) in the polyol (A) within the above range, the sprayability of the resin composition of this disclosure can be further improved.

[0062] High molecular weight polycaprolactone polyol (a4) refers to a polycaprolactone polyol with a number-average molecular weight of 30,000 or more. More specifically, the number-average molecular weight of high molecular weight polycaprolactone polyol (a4) may be 30,000 or more, 40,000 or more, or 50,000 or more. Furthermore, there is no particular upper limit to the number-average molecular weight of the above high molecular weight polycaprolactone polyol (a4), but it can generally be 200,000 or less, or 100,000 or less. The number-average molecular weight of high molecular weight polycaprolactone polyol (a4) is shown as the value measured by gel permeation chromatography (GPC) under the conditions described in the examples below.

[0063] Examples of the high molecular weight polycaprolactone polyol (a4) mentioned above include reaction products of a compound having two or more hydroxyl groups with ε-caprolactone. Examples of compounds having two or more hydroxyl groups include aliphatic and / or alicyclic compounds having two or more hydroxyl groups, as described in the sections on polyester polyols (a1) to (a3) ​​above, and aromatic compounds having two or more hydroxyl groups.

[0064] <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. Among these, aromatic polyisocyanates are preferred, and diphenylmethane diisocyanate is more preferred.

[0065] 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).

[0066] <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.

[0067] The urethane prepolymer (i) is described as "a reaction product of the polyol (A) and the polyisocyanate (B)" if it is a reaction product in which the polyol (A) and the polyisocyanate (B) are essential reaction components, and the reaction components may include any components other than the polyol (A) and the polyisocyanate (B) as long as they do not impair the function of the resin composition of this disclosure.

[0068] 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).

[0069] 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), achieving spray suitability, high moisture resistance, and high adhesion to the substrate by spray coating.

[0070] 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 6% by mass, from the viewpoint of achieving spray suitability, high moisture resistance, and high adhesion to the substrate by spray application. The NCO% of the above urethane prepolymer (i) is shown as the value measured by potentiometric titration in accordance with JIS K 1603-1:2007.

[0071] 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 spray suitability, high moisture resistance, and high adhesion to the substrate by spray application.

[0072] <Moisture-curing hot melt resin composition> 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.

[0073] The urethane prepolymer content in the moisture-curing hot melt resin composition of this disclosure 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 be 99% by mass or less, or 95% by mass. Setting the urethane prepolymer content within the above range makes it possible to achieve spray suitability, high moisture resistance, and high adhesion to the substrate by spray application.

[0074] The moisture-curing hot melt resin composition of this disclosure preferably has a melt viscosity of 5 Pa or less at 120°C, more preferably 0.5 Pa to 3 Pa, and even more preferably 0.5 Pa to 2 Pa. The melt viscosity of the moisture-curing hot melt resin composition of this disclosure being within the above range results in excellent sprayability and allows for thin coating. The melt viscosity of the moisture-curing hot melt resin composition of this disclosure at 120°C is the value measured using a cone plate viscometer (manufactured by ICI) after heating and melting the moisture-curing hot melt resin composition at 120°C.

[0075] One preferred embodiment of the moisture-curing hot-melt resin composition of the present disclosure (Embodiment Example 1) is a moisture-curing polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, wherein the urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B), and the polyol (A) at least essentially contains an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), and the content of the alicyclic polyester polyol (a1) in the polyol (A) is 50% by mass or more.

[0076] One preferred embodiment of the moisture-curing hot-melt resin composition of the present disclosure (Embodiment Example 2) is a moisture-curing polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, wherein the urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B), and the polyol (A) at least essentially contains an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), wherein the content of the crystalline polyester polyol (a2) is 10% to 30% by mass, the content of the aromatic polyester polyol (a3) ​​is 10% to 30% by mass, and the content of high molecular weight polycaprolactone polyol (a4) in the polyol (A) is less than 10% by mass.

[0077] One preferred embodiment of the moisture-curing hot-melt resin composition of the present disclosure (Embodiment Example 3) is a moisture-curing polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, wherein the urethane prepolymer (i) is a reaction product of a polyol (A) and a polyisocyanate (B), and the polyol (A) at least essentially contains an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), wherein the content of the crystalline polyester polyol (a2) is 10% to 30% by mass, the content of the aromatic polyester polyol (a3) ​​is 10% to 30% by mass, and the melt viscosity at 120°C is 5 Pa·s or less.

[0078] [II. Cured product] The cured product of this disclosure is obtained by curing the moisture-curing hot melt resin composition described in section I. Moisture-curing hot melt resin composition above.

[0079] Examples of cured products of this disclosure include cured films obtained by moisture curing a coating film obtained by applying a heated and melted moisture-curing hot-melt resin composition in a desired manner. The heating and melting temperature of the moisture-curing hot-melt resin composition is not particularly limited, but can be, for example, 100°C to 140°C.

[0080] In this disclosure, a spray coating method is preferred for applying the heated and melted moisture-curing hot-melt resin composition, from the viewpoint of enabling conformal coating for protecting printed circuit boards and components used in electronic devices.

[0081] Furthermore, the application method for the moisture-curing hot melt resin composition is not limited to spray application, and known application methods such as screen printing, bar coating, applicator application, blade coating, knife coating, roll coating, T-die coating, comma coating, gravure coating, dispenser application, nozzle application, inkjet printing, screen printing, and offset printing can be used.

[0082] The above moisture-curing polyurethane hot-melt resin composition is preferably dried and cured after application.

[0083] The thickness of the cured product of this disclosure is not particularly limited, but can be in the range of, for example, 5 μm to 300 μm.

[0084] Examples of cured products of this disclosure include films, adhesive layers, coating layers, and the like. One embodiment of the cured product of this disclosure, a film, has excellent moisture resistance and can therefore be used, for example, as a conformal coating for substrates such as printed circuit boards and other substrates containing electrical or electronic components, as well as as a weatherproof film used in solar cells and the like, as well as an adhesive film.

[0085] Furthermore, the cured products of this disclosure can be used in various industrial applications, such as automobiles, electronic equipment, construction, and textiles.

[0086] [III. Coating Agents] The coating agent of this disclosure contains a moisture-curable polyurethane hot-melt resin composition as described in section I. Moisture-curing hot-melt resin composition above. The coating agent of this disclosure is usually solvent-free, but may contain solvents such as water or organic solvents.

[0087] The coating agent of this disclosure can be used, for example, as a conformal coating agent, and specifically, can be used to provide electrical insulation to an electronic circuit board after soldering in order to protect the electronic circuit board from water, moisture and dust.

[0088] [IV. 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.

[0089] The adhesive of this disclosure can also 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 "I. Moisture-curing 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".

[0090] The thickness of the adhesive film mentioned 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.

[0091] [V. Goods] The articles of this disclosure have at least a cured layer of a moisture-curable polyurethane hot-melt resin composition as described in section I. Moisture-curing hot-melt resin composition above.

[0092] One example of an embodiment of an article of the present disclosure is an embodiment comprising a first adherend and a coating layer formed on at least one surface of the first adherend by a cured product of the moisture-curable polyurethane hot-melt resin composition of the present disclosure. More specifically, an example of an article comprising an electronic circuit board having electronic components on a substrate and a coating layer provided on the electronic components and covering the electronic components is provided. The coating layer can stably protect the electronic components from contaminants such as water, dust, and metal powder over a long period of time while maintaining the electrical insulation state of the electronic components.

[0093] Another example of an embodiment of the article of the present disclosure is an embodiment having at least a first adherend and an adhesive layer provided on the first adherend and formed by a cured product of the moisture-curable polyurethane hot-melt resin composition of the present disclosure. In the above embodiment, a second adherend may be provided on the adhesive layer, and the first adherend and the second adherend may be joined by the adhesive layer.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] Examples of the substrates mentioned above include components used in electronic devices or mounting boards 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 boards); substrates for semiconductor devices; and semiconductor device substrates on which semiconductor elements are mounted. Various materials can be used for substrates for electronic devices or electronic materials (e.g., printed wiring boards), 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, and can be appropriately selected according to the application.

[0098] 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 Section II. Cured Products above, and then moisture-cured. When the articles of this disclosure have two or more substrates, the moisture-curable polyurethane hot melt resin composition of this disclosure is applied to the first substrate, the second substrate is 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.

[0099] In the method for manufacturing articles of this disclosure, it is preferable to spray-coat the substrate with the moisture-curable polyurethane hot-melt resin composition. Because the moisture-curable polyurethane hot-melt resin composition has excellent sprayability, a thin coating can be formed.

[0100] Specific examples of the articles disclosed in this disclosure include electronic components such as circuit boards, and portable electronic devices such as smartphones, tablets, and watches. Other examples of the articles disclosed in this disclosure include building materials such as building panels and decorative boards, automotive interior materials, automotive parts, battery components, and electronic components such as circuit boards, depending on the type of substrate and application.

[0101] 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]

[0102] The present invention will be described in more detail below using examples and comparative examples.

[0103] [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.

[0104] 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.

[0105] (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.

[0106] [Example 1] Moisture-curing polyurethane hot melt resin composition (PUR-A) A mixture of 60 parts by mass of alicyclic polyester polyol (a1-2) (a reaction product of neopentyl glycol and hydrogenated phthalic anhydride, number average molecular weight: 2,000, abbreviated as "NPG / HHPA" in the table below), 30 parts by mass of crystalline polyester polyol (a2) (a reaction product of 1,6-hexanediol and dodeca-2 acid, number average molecular weight: 3,500, abbreviated as "HG / DDA" in the table below), and 10 parts by mass of aromatic polyester polyol (a3) ​​(a reaction product of neopentyl glycol and phthalic anhydride, number average molecular weight: 1,000, abbreviated as "NPG / oPA" 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 30 parts by mass of 4,4-methylene diisocyanate (abbreviated as "MDI" in the table below) was 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 prepare a urethane prepolymer, thereby obtaining a moisture-curing polyurethane hot-melt resin composition (PUR-A).

[0107] [Example 2] Moisture-curing polyurethane hot melt resin composition (PUR-B) A urethane prepolymer was prepared in the same manner as in Example 1, except that 60 parts by mass of alicyclic polyester polyol (a1-1) (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 used instead of 60 parts by mass of alicyclic polyester polyol (a1-2), to obtain a moisture-curing polyurethane hot-melt resin composition (PUR-B).

[0108] [Comparative Example 1] Moisture-curing polyurethane hot-melt resin composition (PUR-C) A urethane prepolymer was prepared in the same manner as in Example 1, except that the amount of alicyclic polyester polyol (a1-2) was 30 parts by mass and the amount of aromatic polyester polyol (a3) ​​was 40 parts by mass, to obtain a moisture-curing polyurethane hot-melt resin composition (PUR-C).

[0109] [Comparative Example 2] Moisture-curing polyurethane hot-melt resin composition (PUR-D) A urethane prepolymer was prepared in the same manner as in Example 1, except that the amount of alicyclic polyester polyol (a1-2) was 30 parts by mass, the amount of crystalline polyester polyol (a2) was 50 parts by mass, the amount of aromatic polyester polyol (a3) ​​was 20 parts by mass, and the amount of 4,4-methylene diisocyanate was 35 parts by mass, thereby obtaining a moisture-curable polyurethane hot-melt resin composition (PUR-D).

[0110] [Comparative Example 3] Moisture-curing polyurethane hot-melt resin composition (PUR-E) A urethane prepolymer was prepared in the same manner as in Example 1, except that the amount of alicyclic polyester polyol (a1-2) was set to 50 parts by mass, and 10 parts by mass of polycaprolactone polyol (a4) (number average molecular weight: 80,000, abbreviated as "PCL" in the table below) was added to obtain a moisture-curing polyurethane hot-melt resin composition (PUR-E).

[0111] [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.

[0112] <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, was applied using an applicator to a film thickness of 100 μm. After curing for one week in an atmosphere of 23°C and 50% relative humidity, the cured film of the moisture-curing urethane hot-melt resin 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 1976 Method B). (Evaluation Criteria) T: 20g / m 2 ·24 hours or less F: 20g / m 2 • Greater than 24 hours

[0113] <Melting viscosity at 120℃> A moisture-curing urethane hot-melt resin composition was used as a coating agent, and the viscosity of the coating agent, which was heated and melted at 120°C, was measured using a cone plate viscometer (manufactured by ICI).

[0114] <Suitability for spraying> A moisture-curing urethane hot melt resin composition was used as the coating agent. The coating agent, heated to 120°C, was applied using a glue gun (REKA TR-80LCD) at a rate of 100g / m². 2 The spray coating was applied to a steel plate, and the suitability of the spray was evaluated based on the condition of the coated surface according to the following criteria. A: No stringing phenomenon was observed on the coated surface, and a uniformly smooth coated surface was obtained. B: No stringing phenomenon was observed on the coated surface, but the uniformity and smoothness of the coated surface was slightly inferior. C: Stringing was observed on the coated surface, indicating poor uniformity and smoothness of the coated surface.

[0115] [Table 1]

[0116] From the results above, the moisture-curing urethane hot-melt resin compositions of the examples showed good sprayability, and it was possible to form a thin, highly moisture-resistant coating layer by spray application. In particular, Example 1 was suggested to be able to form a coating film with an even more uniform and smooth surface than Example 2.

[0117] On the other hand, the moisture-curing urethane hot melt resin compositions of Comparative Examples 1 and 3 exhibited stringing of the coating agent after discharge, resulting in unevenness on the coated surface and poor sprayability. Furthermore, the moisture-curing urethane hot melt resin composition of Comparative Example 2 did not provide moisture resistance.

Claims

1. A moisture-curing polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, The urethane prepolymer (i) is a reaction product of polyol (A) and polyisocyanate (B), The polyol (A) contains at least an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), A moisture-curing polyurethane hot-melt resin composition wherein the content of the alicyclic polyester polyol (a1) in the polyol (A) is 50% by mass or more.

2. A moisture-curing polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, The urethane prepolymer (i) is a reaction product of polyol (A) and polyisocyanate (B), The polyol (A) contains at least an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), The content of the crystalline polyester polyol (a2) is 10% by mass to 30% by mass, The content of the aromatic polyester polyol (a3) ​​is 10% by mass to 30% by mass, A moisture-curing polyurethane hot-melt resin composition wherein the content of high molecular weight polycaprolactone polyol (a4) in the polyol (A) is less than 10% by mass.

3. A moisture-curing polyurethane hot-melt resin composition containing a urethane prepolymer (i) having an isocyanate group, The urethane prepolymer (i) is a reaction product of polyol (A) and polyisocyanate (B), The polyol (A) contains at least an alicyclic polyester polyol (a1), a crystalline polyester polyol (a2), and an aromatic polyester polyol (a3), The content of the crystalline polyester polyol (a2) is 10% by mass to 30% by mass, The content of the aromatic polyester polyol (a3) ​​is 10% by mass to 30% by mass, A moisture-curing polyurethane hot-melt resin composition having a melt viscosity of 5 Pa·s or less at 120°C.

4. The moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 3, wherein the alicyclic polyester polyol (a1) comprises at least an alicyclic polyester polyol (a1-1) having structural units derived from a branched aliphatic polyol and structural units derived from an alicyclic polybasic acid.

5. The moisture-curing polyurethane hot-melt resin composition according to claim 1, wherein the content of high molecular weight polycaprolactone polyol (a4) in the polyol (A) is less than 10% by mass.

6. A moisture-curable polyurethane hot-melt resin composition according to claim 1 or claim 2, wherein the melt viscosity at 120°C is 5 Pa·s or less.

7. A coating agent comprising the moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 6.

8. An adhesive comprising the moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 6.

9. A cured product of a moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 6.

10. An article having a cured product of a moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 6.

11. An article having a cured product of a moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 6 on an electronic circuit board.

12. A method for manufacturing an article, comprising spray-coating an adherend with a moisture-curing polyurethane hot-melt resin composition according to any one of claims 1 to 6.

13. The method for manufacturing an article according to claim 12, wherein the adherend is an electronic circuit board or an electronic component on the electronic circuit board.

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