Moisture-curable polyurethane hot-melt resin composition, moisture-curable polyurethane hot-melt adhesive, cured product, and laminate

Abstract

To provide a moisture-curable polyurethane hot-melt adhesive that contains a liquid polyester, which exhibits high adhesion to a smooth substrate, particularly aluminum and PVC substrates, and also shows high initial setting properties.SOLUTION: A moisture-curable polyurethane hot-melt resin composition contains a polyurethane resin having an isocyanate group. The polyurethane resin is a reactant between a polyol (A) and a polyisocyanate (B). The polyol (A) contains a long-chain aliphatic polyester polyol (a1), a liquid aliphatic polyester polyol (a2) and a polyether polyol (a3). In the liquid aliphatic polyester polyol (a2), a mass ratio ((a2-1) / (a2-2)) between an aliphatic polyester polyol (a2-1) with a number average molecular weight of 1,000 or more and 3,000 or less and an aliphatic polyester polyol (a2-2) with a number average molecular weight of 5,000 or more and 9,000 or less is 1 / 1 or more and 3 / 1 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a moisture-curable polyurethane hot-melt resin composition, a moisture-curable polyurethane hot-melt adhesive, a cured product, and a laminate. [Background technology]

[0002] Hot melt adhesives are solvent-free and therefore environmentally friendly, and are widely used for bonding metal materials such as aluminum, wood materials, plastics, rubber, textile products, synthetic leather, paper products, etc., and are utilized in various fields such as building panels, decorative panels, automotive interior materials, and clothing. In addition to moisture-curing polyurethane hot melt adhesives, olefin-based hot melt adhesives, polyester-based hot melt adhesives, etc. are known as hot melt adhesives. In recent years, there has been a growing demand for good adhesion to smooth substrates, and hot melt adhesives containing ionomer resins have been proposed as hot melt adhesives that have good adhesion to such smooth metal substrates (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-23674 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the research of the present inventors, moisture-curable polyurethane hot melt adhesives often contain polyester as a constituent component to achieve ideal adhesive performance. To achieve adhesion to relatively smooth aluminum and polyvinyl chloride (PVC) substrates, it is effective to include an amorphous linear aliphatic polyester (hereinafter referred to as "liquid polyester") with a relatively low glass transition temperature. However, when the proportion of liquid polyester is high, the initial cohesive strength (initial set) of the adhesive is not achieved. The initial cohesive strength of the adhesive is important for certain processing operations, such as wrapping.

[0005] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a moisture-curable polyurethane hot melt adhesive that contains a liquid polyester that exhibits adhesion to smooth substrates, particularly aluminum and PVC substrates, and that also exhibits high initial setting properties. [Means for solving the problem]

[0006] The use of the liquid polyester increases the mobility of molecular chains, allowing the polyurethane as a whole to follow and interact with the aluminum surface. On the other hand, because of its low glass transition temperature, increasing its ratio deteriorates the initial setting property after adhesion. The inventors focused on high-molecular-weight liquid polyesters and conducted research, and unexpectedly found that, despite having the same composition, the viscosity of the polyurethane as a whole was increased and the initial setting property was improved, thereby completing the present invention.

[0007] That is, the present invention includes the following inventions. [1] A moisture-curable polyurethane hot-melt resin composition containing a polyurethane resin having an isocyanate group, wherein the polyurethane resin is a reaction product of polyol (A) and polyisocyanate (B), and the polyol (A) contains a long-chain aliphatic polyester polyol (a1); a liquid aliphatic polyester polyol (a2); and a polyether polyol (a3), wherein the liquid aliphatic polyester polyol (a2) contains an aliphatic polyester polyol (a2-1) having a number-average molecular weight of 1,000 or more and 3,000 or less and an aliphatic polyester polyol (a2-2) having a number-average molecular weight of 5,000 or more and 9,000 or less, in a mass ratio ((a2-1) / (a2-2)) of 1 / 1 or more and 3 / 1 or less. [2] The moisture-curable polyurethane hot-melt resin composition according to [1], wherein the long-chain aliphatic polyester polyol (a1) is a compound represented by formula (1): [ka] [In formula (1), R 1 and R 2 are straight-chain alkylene groups each having an even number of carbon atoms, and R 1 and R 2 The total number of carbon atoms contained in is 12 or more, and n represents an integer of 1 to 40. [3] The moisture-curable polyurethane hot-melt resin composition according to [1] or [2], wherein the content of the long-chain aliphatic polyester polyol (a1) in the polyol (A) is 15% by mass or more and 80% by mass or less. [4] The moisture-curable polyurethane hot-melt resin composition according to any one of [1] to [3], wherein the content of the aliphatic polyester polyol (a2) in the polyol (A) is 10% by mass or more and 75% by mass or less. [5] The moisture-curable polyurethane hot-melt resin composition according to any one of [1] to [4], wherein the content of the aromatic polyester polyol (a3) ​​in the polyol (A) is 10% by mass or more and 75% by mass or less. [6] A cured product formed from the moisture-curable polyurethane hot melt adhesive described in [5]. [7] A laminate comprising the cured product according to [6]. [Effects of the Invention]

[0008] The moisture-curable polyurethane hot-melt resin composition of the present invention contains a liquid polyester that exhibits excellent adhesion to smooth substrates, particularly aluminum and PVC substrates, and can also exhibit high initial setting properties. DETAILED DESCRIPTION OF THE INVENTION

[0009] The moisture-curable polyurethane hot-melt resin composition of the present invention contains a polyurethane resin having an isocyanate group.

[0010] The polyurethane resin is a reaction product of a polyol (A) and a polyisocyanate (B).

[0011] The polyol (A) includes a long-chain aliphatic polyester polyol (a1); a liquid aliphatic polyester polyol (a2); and an aromatic polyester polyol (a3).

[0012] The long-chain aliphatic polyester polyol (a1) is an essential component for exerting cohesive strength as an adhesive, and represents a polyester polyol in which the total number of carbon atoms in the alkylene groups contained in the repeating units is 10 or more.

[0013] The long-chain aliphatic polyester polyol (a1) is preferably represented by the following formula (1):

[0014] [ka]

[0015] [In formula (1), R 1 and R 2 are straight-chain alkylene groups each having an even number of carbon atoms, and R 1and R 2 The total number of carbon atoms contained in is 10 or more, and n represents an integer of 1 to 40.

[0016] R 1 is a straight-chain alkylene group with an even number of carbon atoms, and R 1 and R 2 The total number of carbon atoms in R can be selected appropriately within the range of 10 or more. 1 The alkylene group is preferably a straight-chain alkylene group having an even number of carbon atoms of 4 or more, and more preferably a straight-chain alkylene group having an even number of carbon atoms in the range of 4 to 10.

[0017] R 2 is the R 1 and independently are straight-chain alkylene groups having an even number of carbon atoms, and R 1 and R 2 The alkylene groups may be appropriately selected so that the total number of carbon atoms is 10 or more, and are preferably straight-chain alkylene groups having an even number of carbon atoms of 4 or more, and more preferably straight-chain alkylene groups having an even number of carbon atoms in the range of 4 to 12 (preferably 10 to 12).

[0018] R 1 and R 2 The total number of carbon atoms is preferably 10 or more, more preferably 12 or more, and for example, 30 or less, more preferably 26 or less, and even more preferably 24 or less.

[0019] R 1 and R 2 However, by using a long-chain aliphatic polyester polyol, which is a straight-chain alkylene group having the number of carbon atoms within the above range, the crystallinity of the resulting urethane prepolymer is increased, making it possible to obtain a moisture-curing polyurethane hot melt adhesive that can prevent peeling of the sheet or film in areas of a substrate with a complex shape.

[0020] In formula (1), n ​​represents an integer of 1 to 40, preferably an integer of 9 to 25, and more preferably an integer of 9 to 15. By using a long-chain aliphatic polyester polyol having n within the above range, the adhesive can exhibit an appropriate cohesive strength.

[0021] The long-chain aliphatic polyester polyol (a1) can be produced, for example, by condensation of a straight-chain aliphatic diol having an even number of carbon atoms with a straight-chain aliphatic dicarboxylic acid having an even number of carbon atoms. Examples of the straight-chain aliphatic diol include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, and 10-decanediol, and 1,6-hexanediol, 1,8-octanediol, and 1,10-decanediol are preferred.

[0022] As the straight-chain aliphatic dicarboxylic acid, for example, succinic acid, adipic acid, sebacic acid, dodecamethylenedicarboxylic acid, etc. can be used, and preferably sebacic acid, dodecamethylenedicarboxylic acid, and 1,12-dodecanedicarboxylic acid can be used.

[0023] The combination of the linear aliphatic diol and the linear aliphatic dicarboxylic acid used in producing the long-chain aliphatic polyester polyol (a1) is preferably R 1 , R 2The total number of carbon atoms contained therein can be appropriately selected from 12 or more, preferably from the range of 12 to 20. Among these, it is preferable to use a long-chain aliphatic polyester polyol obtained by reacting 1,6-hexanediol as the linear aliphatic diol with 1,12-dodecanedicarboxylic acid or sebacic acid as the linear aliphatic dicarboxylic acid. Furthermore, it is more preferable to use a long-chain aliphatic polyester polyol obtained by reacting 1,6-hexanediol as the linear aliphatic diol with 1,12-dodecanedicarboxylic acid as the linear aliphatic dicarboxylic acid, in order to produce an adhesive having a practically sufficient level of initial bond strength, even when used in a relatively high-temperature environment.

[0024] The number average molecular weight of the long-chain aliphatic polyester polyol (a1) is preferably 10,000 or less, more preferably 5,000 or less, and is preferably 500 or more, more preferably 1,000 or more, and even more preferably 3,000 or more.

[0025] In the present invention, the number average molecular weight can be measured by gel permeation chromatography (GPC) using polystyrene as a standard sample.

[0026] The content of the long-chain aliphatic polyester polyol (a1) in the polyol (A) is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and is preferably 80% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less.

[0027] The long-chain aliphatic polyester polyol (a1) is preferably used in an amount of 5 to 40 parts by mass, more preferably 20 to 40 parts by mass, per 100 parts by mass of the total amount of the polyol and polyisocyanate (B) used in producing the polyurethane.

[0028] The liquid aliphatic polyester polyol (a2) is an essential component for conforming to the aluminum substrate and achieving interaction between the adhesive and the aluminum substrate, and may be any polyester polyol that is liquid at room temperature (25°C), such as a reaction product of a polybasic acid including adipic acid with an aliphatic compound having two or more hydroxyl groups, provided that the long-chain aliphatic polyester polyol (a1) and the liquid aliphatic polyester polyol (a2) are different.

[0029] Examples of polybasic acids other than adipic acid include aliphatic polybasic acids such as succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, dodecanedioic acid, eicosadionic acid, citraconic acid, itaconic acid, citraconic anhydride, and itaconic anhydride; and alicyclic polybasic acids such as 1,4-cyclohexanedicarboxylic acid. These polybasic acids may be used alone or in combination of two or more. The amount of adipic acid used is preferably 50% by mass or more of the polybasic acid, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0030] Examples of the aliphatic compound having two or more hydroxyl groups include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, Straight-chain or branched-chain aliphatic compounds such as 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, etc. can be used. These compounds can be used alone or in combination of two or more. Among these, it is more preferable to use one or more compounds selected from the group consisting of ethylene glycol, 1,4-butanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, and 2,4-diethyl-1,5-pentanediol, since even better initial adhesive strength and flexibility can be obtained.

[0031] The number average molecular weight of the liquid aliphatic polyester polyol (a2) is preferably 300 or more, more preferably 600 or more, and even more preferably 1,000 or more, and is preferably 10,000 or less, more preferably 9,000 or less, in order to obtain even better initial adhesive strength and flexibility.

[0032] The glass transition temperature of the liquid aliphatic polyester polyol (a2) is preferably 20°C or lower, more preferably 10°C or lower, and even more preferably 5°C or lower, and may be, for example, -100°C or higher, or -50°C or higher.

[0033] In the present invention, the glass transition temperature refers to a value measured by DSC (differential scanning calorimetry) in accordance with JIS K7121-1987. Specifically, a measurement sample is placed in a differential scanning calorimeter, heated to (glass transition temperature + 50°C) at a heating rate of 10°C / min, held at that temperature for 3 minutes, and then rapidly cooled. The midpoint glass transition temperature (Tmg) is read from the differential thermal curve obtained.

[0034] The liquid aliphatic polyester polyol (a2) comprises a liquid aliphatic polyester polyol (a2-1) having a number average molecular weight of 1,000 to 3,000, and a liquid aliphatic polyester polyol (a2-2) having a number average molecular weight of 5,000 to 9,000. In the liquid aliphatic polyester polyol (a2), the mass ratio of the liquid aliphatic polyester polyol (a2-1) to the liquid aliphatic polyester polyol (a2-2) ((a2-1) / (a2-2)) is 1 / 1 or more, preferably 1.2 / 1 or more, and 3 / 1 or less, preferably 2.5 / 1 or less.

[0035] The total content of the liquid aliphatic polyester polyol (a2-1) and the liquid aliphatic polyester polyol (a2-2) in the liquid aliphatic polyester polyol (a2) is preferably 80% by mass or more, more preferably 90% by mass or more, and preferably 100% by mass or less.

[0036] The content of the liquid aliphatic polyester polyol (a2) in the polyol (A) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, and is preferably 75% by mass or less, more preferably 55% by mass or less, and even more preferably 45% by mass or less.

[0037] The liquid aliphatic polyester polyol (a2) is preferably used in an amount of 15 to 35 parts by mass, more preferably 20 to 35 parts by mass, per 100 parts by mass of the total amount of the polyol and polyisocyanate (B) used in producing the polyurethane.

[0038] The aromatic polyester polyol (a3) ​​is an important component for obtaining excellent initial adhesive strength and flexibility, and represents a polyester polyol having an aromatic ring structure in the molecule. Examples of the aromatic polyester polyol (a3) ​​that can be used include a reaction product of a compound having a hydroxyl group with a polybasic acid, including an aromatic polybasic acid; a reaction product of an aromatic compound having two or more hydroxyl groups with a polybasic acid; and a reaction product of an aromatic compound having two or more hydroxyl groups with a polybasic acid, including an aromatic polybasic acid.

[0039] Examples of the compound having a hydroxyl group include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, and 2-methyl-1,3-propanediol. Examples of compounds that can be used include aliphatic compounds such as 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; and alicyclic compounds such as cyclopentanediol, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, and alkylene oxide adducts thereof. These compounds may be used alone or in combination of two or more.

[0040] Examples of aromatic compounds having two or more hydroxyl groups that can be used include bisphenol A, bisphenol F, and alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts thereof. These compounds may be used alone or in combination of two or more. Among these, alkylene oxide adducts of bisphenol A are preferred because they provide even better initial adhesive strength and flexibility, and the number of moles of alkylene oxide added is preferably in the range of 1 to 10 moles.

[0041] Examples of the aromatic polybasic acid that can be used include phthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride. Other examples of the polybasic acid that can be used include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and 1,12-dodecanedicarboxylic acid. These polybasic acids may be used alone or in combination of two or more. It is preferable to use one or more compounds selected from the group consisting of phthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride as the aromatic polybasic acid, since this provides even better initial adhesive strength and flexibility.

[0042] Other polybasic acids that can be used include, for example, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, dodecanedioic acid, eicosadioic acid, citraconic acid, itaconic acid, citraconic anhydride, and itaconic anhydride.

[0043] The number average molecular weight of the aromatic polyester polyol (a3) ​​is preferably less than 2,800, more preferably in the range of 300 to 2,500, and even more preferably in the range of 600 to 2,200, in order to obtain even better initial adhesive strength and flexibility.

[0044] The content of the aromatic polyester polyol (a3) ​​in the polyol (A) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, and is preferably 75% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less.

[0045] The aromatic polyester polyol (a3) ​​is preferably used in an amount of 5 to 35 parts by mass, more preferably 10 to 30 parts by mass, per 100 parts by mass of the total amount of the polyol and polyisocyanate (B) used in producing the polyurethane.

[0046] The total content of the long-chain aliphatic polyester polyol (a1), the liquid aliphatic polyester polyol (a2), and the aromatic polyol (a3) ​​in the polyol (A) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and preferably 100% by mass.

[0047] As the polyol (A), in addition to the long-chain aliphatic polyester polyol (a1), the liquid aliphatic polyester polyol (a2), and the aromatic polyol (a3), other polyols can be used as needed.

[0048] Examples of the other polyols that can be used include polyester polyols other than (a1) and (a2), polycarbonate polyols, polyacrylic polyols, butadiene polyols, hydrogenated polybutadiene polyols, etc. These polyols may be used alone or in combination of two or more.

[0049] Examples of the polyisocyanate (B) that can be used include aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate isocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; and aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate. Among these, aromatic polyisocyanates are preferred, and diphenylmethane diisocyanate is more preferred, in view of obtaining even better reactivity and final adhesive strength.

[0050] The amount of the polyisocyanate (B) used is preferably in the range of 5 to 60% by mass, more preferably 15 to 50% by mass, of the raw materials for the polyurethane resin, in order to obtain even better adhesive strength.

[0051] The polyurethane resin is obtained by reacting the polyol (A) with the polyisocyanate (B), and has isocyanate groups at the polymer terminals or within the molecule, which are capable of forming a crosslinked structure by reacting with moisture present in the air or in a housing or an adherend to which the urethane prepolymer is applied.

[0052] The polyurethane resin can be produced, for example, by adding the polyol (A) dropwise to a reaction vessel containing the polyisocyanate (B), followed by heating, and reacting under conditions in which the isocyanate groups of the polyisocyanate (B) are in excess relative to the hydroxyl groups of the polyol (A).

[0053] The urethane bond amount of the polyurethane resin is preferably in the range of 0.5 to 3 mol / kg, more preferably in the range of 0.9 to 2.7 mol / kg, and even more preferably in the range of 1.1 to 2.4 mol / kg, in order to obtain even better initial adhesive strength, flexibility, and low viscosity.

[0054] When producing the polyurethane resin, the equivalent ratio ([isocyanate group / hydroxyl group]) of the isocyanate groups in the polyisocyanate (B) to the hydroxyl groups in the polyol (A) is preferably in the range of 1.1 to 1.5, more preferably in the range of 1.15 to 1.45, in order to obtain even better initial adhesive strength, flexibility, and low viscosity.

[0055] The isocyanate group content (hereinafter abbreviated as "NCO%") of the polyurethane resin is preferably in the range of 1 to 4 mass%, more preferably in the range of 1.2 to 3.5 mass%, in order to obtain even better initial adhesive strength, flexibility, and low viscosity. The NCO% of the polyurethane resin is a value measured by potentiometric titration in accordance with JIS K1603-1:2007.

[0056] The content of the polyurethane resin in the moisture-curable polyurethane hot-melt resin composition is preferably 40% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, with the upper limit being 100% by mass.

[0057] The moisture-curable polyurethane hot-melt resin composition of the present invention may contain other additives in addition to the polyurethane resin, as required.

[0058] Examples of the other additives that can be used include antioxidants, tackifiers, plasticizers, stabilizers, fillers, dyes, pigments, fluorescent brighteners, silane coupling agents, waxes, etc. These additives may be used alone or in combination of two or more.

[0059] A method for obtaining a cured coating of the moisture-curable polyurethane hot-melt resin composition includes, for example, melting the moisture-curable polyurethane hot-melt resin composition at 50 to 130°C, applying it to a substrate, and then moisture-curing it.

[0060] Examples of the substrate that can be used include wood substrates such as plywood, MDF (medium density fiberboard), and particle board; metal substrates such as aluminum and iron; sheet substrates made from resins such as polyester, polyamide, polystyrene, polycarbonate, vinyl chloride, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyethylene, and polypropylene; calcium silicate board; paper; metal foil; veneer; fiber substrates such as nonwoven fabric and woven fabric; synthetic leather; paper; rubber substrates; and glass substrates. The thickness of the substrate is determined depending on the intended use, but is, for example, in the range of 1 to 500 mm.

[0061] Examples of methods for applying the moisture-curable urethane hot-melt resin composition to the substrate include methods in which the moisture-curable urethane hot-melt resin composition melted at 70 to 140°C is applied to the substrate using a coater method such as a roll coater, spray coater, T-tie coater, knife coater, or comma coater; or a precision method such as a dispenser, spray, inkjet printing, screen printing, or offset printing.

[0062] The thickness of the cured layer of the moisture-curable urethane hot-melt composition is determined appropriately depending on the intended use, but is, for example, in the range of 0.001 to 3 cm.

[0063] After the coating, the adhesive is aged for 0.5 to 3 days at a temperature of 20 to 80° C. and a relative humidity of 50 to 90%, for example, to obtain the final adhesive strength.

[0064] The moisture-curable polyurethane hot-melt resin composition of the present invention can achieve both initial setting properties and adhesion to smooth substrates such as vinyl chloride substrates and aluminum substrates. Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be suitably used for building panels, decorative panels, automotive interior materials, etc. [Example]

[0065] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is possible to carry out the invention by making appropriate modifications within the scope of the above and below-described aims, and all such modifications are included in the technical scope of the present invention.

[0066] [Example 1] Into a four-neck flask equipped with a stirrer and a thermometer, liquid polyester polyol (a reaction product of diethylene glycol, neopentyl glycol, 1,6-hexanediol, and adipic acid, number average molecular weight: 2,000, hereinafter abbreviated as "DEG / NPG / HG / AA2000"), a polyester polyol with the same composition but a number average molecular weight of 7,000 (hereinafter abbreviated as "DEG / NPG / HG / AA7000"), and an aromatic polyester polyol were added. A polyol (neopentyl glycol and phthalic anhydride reacted, number average molecular weight: 2,000, hereafter abbreviated as "NPG / oPA2000") and a long-chain aliphatic polyester polyol (1,6-hexanediol and dodecanedioic acid reacted, number average molecular weight: 3,500, hereafter abbreviated as "HG / DDA3500") were charged and heated under reduced pressure at 100°C to dehydrate the flask until the water content in the flask was 0.05% by mass. After cooling the flask to 90°C, 15 parts by mass of 4,4'-diphenylmethane diisocyanate (hereafter abbreviated as "MDI") melted at 70°C was added, and the mixture was reacted at 110°C for approximately 2 hours under a nitrogen atmosphere until the NCO% remained constant, producing a moisture-curable polyurethane hot melt adhesive.

[0067] [Examples 2 to 3, Comparative Examples 1 to 6] A moisture-curable polyurethane hot-melt adhesive was obtained in the same manner as in Example 1, except that the polyol (A) and polyisocyanate (B) were changed as shown in Table 1.

[0068] The resulting moisture-curable polyurethane hot melt adhesive was evaluated as follows.

[0069] [Evaluation method for initial set] The moisture-curing polyurethane hot melt adhesives obtained in the examples and comparative examples were melted at 120°C for one hour and then applied to a sheet at a thickness of 0.10 mm using an applicator. Aluminum, PVC substrates, or medium-density fiberboard were bonded together using a press roll. A 25 mm wide cut was made, and three minutes after bonding, a creep test was conducted at a temperature of 35°C and a load of 150 g. The peel distance was measured 15 minutes after hanging, and the results were evaluated as follows: "Good": Peeling distance is 5 mm or less. "X": The peeling distance is 5 mm or more.

[0070] [Method for evaluating adhesion to substrate] The moisture-curing polyurethane hot melt adhesives obtained in the examples and comparative examples were melted at 120°C for one hour and then applied to a sheet at a thickness of 0.10 mm using an applicator. Aluminum, PVC substrates, or medium-density fiberboard were bonded using a press roll. A 25 mm wide cut was made and the sheet was left in an environment of 23°C and 50% humidity for 48 hours. After that, a creep test was conducted at 60°C and a load of 500 g. The peel distance was measured 60 minutes after hanging and evaluated as follows: "Good": Peeling distance is 5 mm or less. "X": The peeling distance is 5 mm or more.

[0071] The results are shown in Table 1.

[0072] [Table 1]

[0073] Examples 1 to 3 are examples of the present invention, and were able to achieve both initial set properties and adhesion to substrates. Comparative Examples 1 and 2 are examples that did not contain an aliphatic polyester polyol (a2-1) having a number-average molecular weight of 1,000 to 3,000, and were unable to achieve both initial set properties and adhesion to substrates. Comparative Example 3 was an example that did not contain an aliphatic polyester polyol (a2-2) having a number-average molecular weight of 5,000 to 9,000, and was poor in adhesion to substrates. Comparative Examples 4 and 5 were examples in which the mass ratio of the aliphatic polyester polyols (a2-1) to (a2-2) was smaller than the range specified in the present invention, and were unable to achieve both initial set properties and adhesion to substrates. Comparative Example 6 was an example in which the mass ratio of the aliphatic polyester polyols (a2-1) to (a2-2) was greater than the range specified in the present invention, and was poor in initial set properties. [Industrial Applicability]

[0074] The moisture-curable polyurethane hot-melt resin composition of the present invention can achieve both initial setting properties and adhesion to smooth substrates such as vinyl chloride substrates and aluminum substrates. Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be suitably used for building panels, decorative panels, automotive interior materials, etc.

Claims

1. A moisture-curable polyurethane hot-melt resin composition containing a polyurethane resin having an isocyanate group, the polyurethane resin is a reaction product of a polyol (A) and a polyisocyanate (B), the polyol (A) comprises a long-chain aliphatic polyester polyol (a1); a liquid aliphatic polyester polyol (a2); and an aromatic polyester polyol (a3); The long-chain aliphatic polyester polyol (a1) is represented by the formula (1): 【Chemical 1】 [In formula (1), R 1 and R 2 are each a straight-chain alkylene group having an even number of carbon atoms, and R 1 and R 2 The total number of carbon atoms contained in the alkyl group is 12 or more, and n represents an integer of 1 to 40. is a compound represented by The liquid aliphatic polyester polyol (a2) is different from the long-chain aliphatic polyester polyol (a1), The moisture-curable polyurethane hot-melt resin composition is characterized in that, in the liquid aliphatic polyester polyol (a2), the mass ratio ((a2-1) / (a2-2)) of the aliphatic polyester polyol (a2-1) having a number average molecular weight of 1,000 or more and 3,000 or less to the aliphatic polyester polyol (a2-2) having a number average molecular weight of 5,000 or more and 9,000 or less is 1 / 1 or more and 3 / 1 or less.

2. 2. The moisture-curable polyurethane hot-melt resin composition according to claim 1, wherein the long-chain aliphatic polyester polyol (a1) is a condensation reaction product of a linear aliphatic diol having an even number of carbon atoms and a linear aliphatic dicarboxylic acid having an even number of carbon atoms.

3. The moisture-curable polyurethane hot-melt resin composition according to claim 1 or 2, wherein the content of the long-chain aliphatic polyester polyol (a1) in the polyol (A) is 15% by mass or more and 80% by mass or less.

4. The moisture-curable polyurethane hot melt resin composition according to any one of claims 1 to 3, wherein the content of the aliphatic polyester polyol (a2) in the polyol (A) is 10% by mass or more and 75% by mass or less.

5. The content of the aromatic polyester polyol (a3) ​​in the polyol (A) is 10% by mass or more and 75% by mass or less. The moisture-curable polyurethane hot melt resin composition according to any one of claims 1 to 4.

6. A cured product formed from the moisture-curable polyurethane hot-melt resin composition according to claim 5.

7. A laminate comprising the cured product according to claim 6.

Images