JP7544312B1 - Moisture-curable polyurethane hot melt resin composition, cured product, laminate, and skin material - Google Patents

Abstract

The present invention provides a moisture-curable polyurethane hot melt resin composition comprising: aromatic polyester polyol (a1) made from compound (x) having a molecular weight of less than 500, a branched structure, and 2 to 4 hydroxyl groups per molecule; aromatic polyester polyol (a2) other than (a1); aliphatic polyester polyol (a3); crystalline polyester polyol (a4) other than (a3); and polyether polyol (a5); and a urethane prepolymer (i) having an isocyanate group, which is a reaction product of polyisocyanate (B). The present invention also provides a cured product formed from the moisture-curable polyurethane hot melt resin composition.

Description

The present invention relates to a moisture-curable polyurethane hot melt resin composition, a cured product, a laminate, and a skin material.

Laminated sheets such as synthetic leather and artificial leather are used on the surface of furniture and vehicle seats, and are generally provided with a buffer layer such as urethane foam (PUF) to provide cushioning properties (see, for example, Patent Document 1). Conventionally, synthetic leather and PUF/PUF and mesh fabric for providing slip during sewing have been bonded together using frame lamination (flame welding), in which the PUF is melted with a flame and bonded to the surface surface/back surface base material of the synthetic leather, etc.

However, the use of flame lamination in lamination of films creates the problem of hydrogen cyanide (HCN) being generated during production, which can lead to poor working conditions. As an alternative, water-based and solvent-based adhesives are used, but they require a drying process, which raises concerns about reduced production efficiency, and in the event of insufficient drying, the adhesive can seep out onto the surface of the backing fabric (adhesive penetration), causing blocking when the film is wound up.

JP 2017-136735 A

The problem that the present invention aims to solve is to provide a moisture-curable polyurethane hot melt resin composition that has excellent initial strength, mechanical strength, and adhesion and can suppress punch-through.

The present invention provides a moisture-curable polyurethane hot melt resin composition comprising: aromatic polyester polyol (a1) made from compound (x) having a molecular weight of less than 500, a branched structure, and having 2 to 4 hydroxyl groups per molecule; polyol (A) containing aromatic polyester polyol (a2) other than (a1); aliphatic polyester polyol (a3); crystalline polyester polyol (a4) other than (a3); and polyether polyol (a5); and a urethane prepolymer (i) having an isocyanate group that is a reaction product of polyisocyanate (B).

The present invention also provides a cured product formed from the moisture-curable polyurethane hot melt resin composition. The present invention also provides a laminate having a polyurethane foam, a layer of the cured product, and a base fabric, and a skin material.

The moisture-curable polyurethane hot melt resin composition of the present invention has excellent initial strength, mechanical strength, and adhesion, and can suppress punch-through. In addition, by using the moisture-curable polyurethane hot melt resin composition, the conventional frame lamination is no longer necessary, which contributes to improving the working environment.

The moisture-curable polyurethane hot melt resin composition of the present invention contains an aromatic polyester polyol (a1) made from a compound (x) having a molecular weight of less than 500, a branched structure, and 2 to 4 hydroxyl groups per molecule, an aromatic polyester polyol (a2) other than (a1), an aliphatic polyester polyol (a3), a crystalline polyester polyol (a4) other than (a3), and a polyether polyol (a5), and a urethane prepolymer (i) having an isocyanate group that is a reaction product of a polyisocyanate (B).

The urethane prepolymer (i) is a reaction product of a specific polyol (A) and a polyisocyanate (B).

The polyol (A) contains the above-mentioned (a1) to (a5) as essential components.

In order to achieve excellent initial strength and suppress breakthrough, it is essential that the aromatic polyester polyol (a1) is made from a compound (x) that has a molecular weight of less than 500, a branched structure, and 2 to 4 hydroxyl groups per molecule. The molecular weight of the compound (x) is a value calculated from the chemical formula.

Examples of the compound (x) that can be used include 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,2-butanediol, 1,3-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, neopentyl glycol, 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, 2-methyl-1,8-octanediol, and trimethylolpropane. These compounds may be used alone or in combination of two or more. Among these, neopentyl glycol is preferred since it provides a more excellent effect of suppressing penetration.

The amount of compound (x) used is preferably in the range of 0.1 to 30% by mass, more preferably 0.2 to 20% by mass, and even more preferably 0.3 to 15% by mass, of the total mass of polyol (A) and polyisocyanate (B), in order to obtain a cured film with a suitable viscosity and good flexibility while maintaining an excellent punch-through suppression effect.

Specific examples of the aromatic polyester polyol (a1) include the reaction product of a compound having two or more hydroxyl groups, including the compound (x), with a polybasic acid.

Examples of compounds having two or more hydroxyl groups other than the compound (x) include aliphatic compounds such as ethylene glycol, 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, and tetraethylene glycol; alicyclic compounds such as cyclopentanediol, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, and alkylene oxide adducts thereof; and aromatic compounds such as 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, aliphatic compounds are preferred, and diethylene glycol is more preferred, in that even better punch-through suppression effects and flexibility can be obtained.

As the polybasic acid, for example, phthalic acid, isophthalic acid, terephthalic acid, phthalic anhydride, etc. can be used. As other polybasic acids, for example, aromatic polybasic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, 1,12-dodecanedicarboxylic acid, etc.; succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, dodecanedioic acid, eicosadionic acid, citraconic acid, itaconic acid, citraconic anhydride, itaconic anhydride, etc. can be used. These polybasic acids may be used alone or in combination of two or more. Among these, aromatic polybasic acids are preferred from the viewpoint of obtaining even more excellent punch-through suppression effect, adhesion, reactivity, and flexibility, and phthalic acid (one or more compounds selected from the group consisting of phthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride) is more preferred.

The number average molecular weight of the aromatic polyester polyol (a1) is more preferably 700 to 10,000, and more preferably 800 to 5,000, in order to obtain a more excellent punch-through suppression effect and flexibility. The number average molecular weight of the aromatic polyester polyol (a1) is a value measured by gel permeation chromatography (GPC).

The content of the aromatic polyester polyol (a1) in the polyol (A) is preferably 10 to 40% by mass, and more preferably 15 to 30% by mass, in order to obtain a more excellent punch-through suppression effect and flexibility.

The aromatic polyester polyol (a2) is other than the aromatic polyester polyol (a1) (not using the compound (x) as a raw material) and is intended to extend the bonding time and obtain excellent handling properties.

As the raw material for the aromatic polyester polyol (a2), the compound having two or more hydroxyl groups or the polybasic acid that can be used as the raw material for the aromatic polyester polyol (a1) can be used, the compound having two or more hydroxyl groups is preferably the aliphatic compound, and the polybasic acid preferably includes phthalic acid.

The number average molecular weight of the aromatic polyester polyol (a2) is preferably 700 to 10,000, more preferably 800 to 5,000. The number average molecular weight of the aromatic polyester polyol (a1) is a value measured by gel permeation chromatography (GPC).

The content of the aromatic polyester polyol (a2) in the polyol (A) is preferably 5 to 30 mass%, more preferably 10 to 25 mass%.

The aliphatic polyester polyol (a3) adjusts the solidification time, and may be a reaction product of an aliphatic compound having two or more hydroxyl groups and an aliphatic polybasic acid.

Examples of the aliphatic compound having two or more hydroxyl groups include the compound (x); aliphatic compounds such as ethylene glycol, 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, and tetraethylene glycol. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use the compound (x) in combination with the aliphatic compound.

Examples of the aliphatic polybasic acid that can be used include 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. These polybasic acids may be used alone or in combination of two or more.

The number average molecular weight of the aliphatic polyester polyol (a3) is preferably 700 to 50,000, more preferably 800 to 7,000. The number average molecular weight of the aromatic polyester polyol (a1) is a value measured by gel permeation chromatography (GPC).

The content of the aliphatic polyester polyol (a3) in the polyol (A) is preferably 5 to 30 mass%, more preferably 10 to 25 mass%.

The crystalline polyester polyol (a4) is for obtaining excellent adhesion and is other than the aliphatic polyester polyol (a3), and may be, for example, a reaction product of a compound having a hydroxyl group and a polybasic acid. In the present invention, "crystalline" refers to a peak of heat of crystallization or heat of fusion that can be confirmed in a DSC (differential scanning calorimeter) measurement according to JIS K7121:2012.

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

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

The number average molecular weight of the crystalline polyester polyol (a4) is preferably 600 to 50,000, and more preferably 1,000 to 10,000, in order to obtain even better adhesion. The number average molecular weight of the crystalline polyester polyol (a4) is a value measured by gel permeation chromatography (GPC).

The content of the crystalline polyester polyol (a4) in the polyol (A) is preferably 5 to 30 mass%, more preferably 10 to 25 mass%.

The polyether polyol (a5) is used for low viscosity and for adjusting the lamination time, and may be, for example, a polyalkylene glycol such as polyethylene glycol, polypropylene glycol, or polytetramethylene glycol; or a derivative of the polyalkylene glycol (for example, a derivative of alkyl-substituted tetrahydrofuran, or a derivative of neopentyl glycol). These polyether polyols may be used alone or in combination of two or more kinds. Among these, polypropylene glycol and/or polytetramethylene glycol are preferred.

The number average molecular weight of the polyether polyol (a5) is preferably 300 to 10,000, and more preferably 350 to 4,000. The number average molecular weight of the polyether polyol (a5) is a value measured by gel permeation chromatography (GPC).

The content of the polyether polyol (a5) in the polyol (A) is preferably 10 to 50 mass%, more preferably 15 to 40 mass%.

The polyol (A) contains the above-mentioned (a1) to (a5) as essential components, but other polyols may be used in combination if necessary.

As the other polyols, for example, polyester polyols other than (a1) to (a4), acrylic polyols, polycarbonate polyols, polybutadiene polyols, etc. can be used. These polyols may be used alone or in combination of two or more.

As the polyisocyanate (B), for example, aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate isocyanate, xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate can be used. These polyisocyanates may be used alone or in combination of two or more. Among these, aromatic polyisocyanates are preferred from the viewpoint of mechanical strength, and diphenylmethane diisocyanate is more preferred.

The urethane prepolymer (i) can be produced, for example, by adding a mixture of 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).

When producing the urethane prepolymer (i), 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 1.5 to 5, more preferably 1.6 to 2.5.

The isocyanate group content (hereinafter abbreviated as "NCO%") of the urethane prepolymer (i) is preferably 1.0 to 5.0% by mass, and more preferably 2.3 to 4.8% by mass. The NCO% of the urethane prepolymer (i) is a value measured by potentiometric titration in accordance with JIS K1603-1:2007.

The moisture-curable polyurethane hot melt resin composition of the present invention contains the urethane prepolymer (i) as an essential component, but may also contain other additives as necessary.

Examples of the other additives that can be used include curing catalysts, antioxidants, tackifiers, plasticizers, stabilizers, flame retardants, fillers, dyes, pigments, fluorescent brighteners, silane coupling agents, waxes, thermoplastic resins, etc. These additives may be used alone or in combination of two or more.

The laminate of the present invention has a polyurethane foam, a cured layer of the moisture-curable polyurethane hot melt resin composition, and a base fabric.

The polyurethane foam provides shock-absorbing properties, cushioning properties, breathability, etc., and any known polyurethane foam can be used. The thickness of the polyurethane foam may be, for example, in the range of 1.5 to 20 mm.

The base fabric is laminated with the polyurethane foam to impart slipperiness when it is set in a molded product such as a car seat, thereby improving workability. Examples of the base fabric include nonwoven fabrics, woven fabrics, and knitted fabrics made of polyester fibers, polyethylene fibers, nylon fibers, acrylic fibers, polyurethane fibers, acetate fibers, rayon fibers, polylactic acid fibers, cotton, hemp, silk, wool, glass fibers, carbon fibers, and blends thereof. In the present invention, by using the moisture-curing polyurethane hot melt resin composition, an excellent punch-through suppression effect can be obtained even when a mesh fabric base fabric is used.

Examples of the method for producing the laminate include a method of applying the moisture-curable polyurethane hot melt resin composition onto the polyurethane foam. Examples of the method for applying the moisture-curable polyurethane hot melt resin composition include coater methods such as gravure coater, roll coater, spray coater, T-die coater, knife coater, and comma coater; precision methods such as dispenser, inkjet printing, screen printing, and offset printing; nozzle application; spray application; and film lamination methods. Among these, intermittent application is preferred because it provides even better mechanical strength, adhesive strength, and punch-through suppression effects. Before the application, the moisture-curable polyurethane hot melt resin composition may be melted at 70 to 120 ° C.

The coating amount of the moisture-curable polyurethane hot-melt resin composition is, for example, 5 to 35 g/ ^m2 .

After the moisture-curable polyurethane hot melt resin composition has been applied, it may be cooled to increase the solidification rate of the moisture-curable polyurethane hot melt resin composition.

After the moisture-curable polyurethane hot melt resin composition has solidified, a release paper or carrier sheet may be placed on the cured product. When using it as a skin material, it is preferable to peel it off.

The thickness of the cured product of the moisture-curable polyurethane hot melt resin composition may be, for example, in the range of 5 to 200 μm.

The laminate of the present invention has the above-mentioned effects and is therefore particularly suitable for use as a skin material. Examples of the skin material include a laminate of the base fabric, a cured layer of the moisture-curable polyurethane hot melt resin composition, the polyurethane foam, and the skin layer.

If necessary, a base fabric may be provided between the polyurethane foam and the skin layer, and these may be bonded using a known adhesive. Examples of known adhesives that can be used include acrylic adhesives, urethane adhesives, and moisture-curing polyurethane hot melt adhesives.

The skin layer can be formed from known materials, such as solvent-based polyurethane, water-based polyurethane, polyvinyl chloride, thermoplastic urethane (TPU), thermoplastic polyolefin (TPO), thermoplastic polyester (TPE), etc.

The skin material can be used, for example, to cover vehicle seats.

The present invention will now be described in more detail using examples.

Example 1 Preparation of Moisture-Curable Polyurethane Hot-Melt Resin Composition (1) Into a four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser, 35 parts by mass of aromatic polyester polyol (reaction product of neopentyl glycol, diethylene glycol, and phthalic anhydride, number average molecular weight: 1,000, hereinafter abbreviated as "aromatic PEs (a1-1)"), 15 parts by mass of aromatic polyester polyol (reaction product of hexanediol and phthalic anhydride, number average molecular weight: 2,000, hereinafter abbreviated as "aromatic PEs (a2-1)"), and 15 parts by mass of aliphatic polyester polyol (ethylene glycol, neopentyl glycol, hexane A reaction product of diol and adipic acid, number average molecular weight; 5,500, hereinafter abbreviated as "aliphatic PEs (a3-1)"), 15 parts by mass of crystalline polyester polyol (reaction product of 1,6-hexanediol and adipic acid, number average molecular weight; 8,000, hereinafter abbreviated as "crystalline PEs (a4-1)"), and 15 parts by mass of polyether polyol (polypropylene glycol, number average molecular weight; 2,000, hereinafter abbreviated as "PEt (a5-1)") were added, mixed, and heated at 70°C under reduced pressure, thereby dehydrating the water content in the flask to 0.05% by mass or less. Next, the flask was cooled to 90°C, and 22 parts by mass of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI") melted at 70°C was added, and the mixture was reacted at 110°C for about 3 hours under a nitrogen atmosphere until the isocyanate group content became constant, thereby obtaining a hot-melt urethane prepolymer (i-1) with an NCO% of 2.5% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (1).

[Example 2] Preparation of moisture-curable polyurethane hot melt resin composition (2) In a four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 25 parts by mass of aromatic PEs (a1-1), 10 parts by mass of aromatic PEs (a2-1), 10 parts by mass of aliphatic PEs (a3-1), 10 parts by mass of crystalline PEs (a4-1), 10 parts by mass of PEt (a5-1), and 15 parts by mass of polyether polyol (polypropylene glycol, number average molecular weight: 400, hereinafter abbreviated as "PEt (a5-2)"). The mixture was mixed and heated under reduced pressure at 70 ° C. to dehydrate the water content in the flask to 0.05% by mass or less. Next, the flask was cooled to 90°C, 33 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C for about 3 hours under a nitrogen atmosphere until the isocyanate group content became constant, thereby obtaining a hot-melt urethane prepolymer (i-2) with an NCO% of 4.0% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (2).

[Example 3] Preparation of moisture-curable polyurethane hot melt resin composition (3) In a four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 35 parts by mass of aromatic PEs (a1-1), 15 parts by mass of aromatic PEs (a2-1), 10 parts by mass of aliphatic PEs (a3-1), 15 parts by mass of crystalline PEs (a4-1), and 15 parts by mass of polyether polyol (polytetramethylene glycol, number average molecular weight: 2,000, hereinafter abbreviated as "PEt (a5-3)"). The mixture was mixed and heated at 70 ° C. under reduced pressure to dehydrate the water content in the flask to 0.05% by mass or less. Next, the flask was cooled to 90°C, 22 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C for about 3 hours under a nitrogen atmosphere until the isocyanate group content became constant, thereby obtaining a hot-melt urethane prepolymer (i-3) with an NCO% of 2.5% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (3).

[Example 4] Preparation of moisture-curable polyurethane hot melt resin composition (4) A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser was charged with 15 parts by mass of aromatic PEs (a1-1), 35 parts by mass of aromatic PEs (a2-1), 10 parts by mass of aliphatic PEs (a3-1), 15 parts by mass of crystalline PEs (a4-1), and 15 parts by mass of PEt (a5-1), mixed, and heated under reduced pressure at 70 ° C. to dehydrate the water in the flask to 0.05% by mass or less. Next, the flask was cooled to 90 ° C., 25 parts by mass of MDI melted at 70 ° C. was added, and the isocyanate group content was allowed to react at 110 ° C. for about 3 hours under a nitrogen atmosphere until it became constant, NCO%; 4.0% by mass of hot melt urethane prepolymer (i-4) was obtained, and the moisture-curable polyurethane hot melt resin composition (4) was obtained.

[Example 5] Preparation of moisture-curable polyurethane hot melt resin composition (5) In a four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 35 parts by mass of aromatic PEs (a1-1), 15 parts by mass of aromatic PEs (a2-1), 10 parts by mass of aliphatic polyester polyol (neopentyl glycol, diethylene glycol, hexanediol, and adipic acid reaction product, number average molecular weight: 2,000, hereinafter abbreviated as "aliphatic PEs (a3-2)"). 15 parts by mass of crystalline PEs (a4-1), and 15 parts by mass of PEt (a5-1) were added, mixed, and heated under reduced pressure at 70 ° C. to dehydrate the water in the flask to 0.05% by mass or less. Next, the flask was cooled to 90°C, 22 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C for about 3 hours under a nitrogen atmosphere until the isocyanate group content became constant, thereby obtaining a hot-melt urethane prepolymer (i-5) with an NCO% of 2.3% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (5).

[Example 6] Preparation of moisture-curable polyurethane hot melt resin composition (6) A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser was charged with 20 parts by mass of aromatic PEs (a1-1), 10 parts by mass of aromatic PEs (a2-1), 10 parts by mass of aliphatic PEs (a3-1), 10 parts by mass of crystalline PEs (a4-1), and 40 parts by mass of PEt (a5-1), mixed, and heated under reduced pressure at 70 ° C. to dehydrate the water in the flask to 0.05% by mass or less. Next, the flask was cooled to 90 ° C., 26 parts by mass of MDI melted at 70 ° C. was added, and the isocyanate group content was allowed to react at 110 ° C. for about 3 hours under a nitrogen atmosphere until it became constant, NCO%; 4.0% by mass of hot melt urethane prepolymer (i-6) was obtained, and the moisture-curable polyurethane hot melt resin composition (6) was obtained.

[Example 7] Preparation of moisture-curable polyurethane hot melt resin composition (7) In a four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 35 parts by mass of aromatic PEs (a1-1), 15 parts by mass of aromatic polyester polyol (a reaction product of ethylene glycol, adipic acid, phthalic anhydride and terephthalic acid, number average molecular weight: 2,000, hereinafter abbreviated as "aromatic PEs (a2-2)"), 10 parts by mass of aliphatic PEs (a3-1), 10 parts by mass of crystalline PEs (a4-1), and 15 parts by mass of PEt (a5-1) were added, mixed, and heated under reduced pressure at 70 ° C. to dehydrate the water in the flask to 0.05% by mass or less. Next, the flask was cooled to 90°C, 27 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C for about 3 hours under a nitrogen atmosphere until the isocyanate group content became constant, thereby obtaining a hot-melt urethane prepolymer (i-7) with an NCO% of 4.0% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (7).

Comparative Example 1 Preparation of Moisture-Curable Polyurethane Hot Melt Resin Composition (R1) In a four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 15 parts by mass of aromatic polyester polyol (neopentyl glycol and phthalic anhydride reaction product, number average molecular weight: 1,000, hereinafter abbreviated as "aromatic PEs (a1-2)"). 35 parts by mass of crystalline polyester polyol (hexanediol and sebacic acid reaction product, number average molecular weight: 4,000, hereinafter abbreviated as "crystalline PEs (a4-2)"). 50 parts by mass of PEt (a5-1) were added, mixed and heated under reduced pressure at 70 ° C. to dehydrate the water in the flask to 0.05% by mass or less. Next, the flask was cooled to 90°C, 24 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C for about 3 hours under a nitrogen atmosphere until the isocyanate group content became constant, thereby obtaining a hot-melt urethane prepolymer (iR-1) with an NCO% of 3.2% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (R1).

[Comparative Example 2] Preparation of moisture-curable polyurethane hot melt resin composition (R2) 20 parts by mass of crystalline PEs (a4-2) and 80 parts by mass of PEt (a5-1) were placed in a four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, mixed, and heated under reduced pressure at 70 ° C. to dehydrate the water in the flask to 0.05% by mass or less. Next, the flask was cooled to 90 ° C., 18 parts by mass of MDI melted at 70 ° C. was added, and the mixture was reacted at 110 ° C. for about 3 hours under a nitrogen atmosphere until the isocyanate group content became constant, thereby obtaining a hot melt urethane prepolymer (iR-2) with an NCO% of 1.9% by mass, which was used as a moisture-curable polyurethane hot melt resin composition (R2).

[Method for measuring number average molecular weight]
The number average molecular weights of the polyols used in the Synthesis Examples and Comparative Synthesis Examples are values measured by gel permeation column chromatography (GPC) under the following conditions.

Measurement device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: 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" (7.8mm I.D. x 30cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (sample concentration 0.4% by mass in tetrahydrofuran solution)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(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

[Mechanical strength evaluation method]
On a hot plate set at 110 ° C., a 50 μm applicator was used to apply the moisture-curable polyurethane hot melt resin composition obtained in the Examples and Comparative Examples, which had been melted at 110 ° C. for 1 hour, to a 100 μm-thick release PET sheet, and the sheet was left at an environmental temperature of 23 ° C. and an environmental humidity of 50% for 3 days to obtain a film. The obtained film was cut into strips with a width of 5 mm and a length of 50 mm, and the test piece was stretched at a crosshead speed of 300 mm / sec using a tensile tester "Autograph AG-I" (manufactured by Shimadzu Corporation) in an atmosphere at a temperature of 23 ° C., and the 100% modulus (MPa) of the test piece was measured. The chuck distance at this time was 40 mm.

[Evaluation method for initial strength]
In a constant temperature and humidity chamber adjusted to a temperature of 23°C and a humidity of 50±5%, a moisture-curable polyurethane hot melt resin composition obtained in each of the Examples and Comparative Examples was applied to a 100 μm-thick corona-treated PET sheet on a hot plate set at a temperature of 110°C using a 100 μm applicator, and the sheet was laminated to the corona-treated PET sheet with a rubber roller. After that, the sheet was cut to a width of 1 inch after a predetermined time, and the tensile strength was measured using a tensile tester "Autograph AG-I" (manufactured by Shimadzu Corporation, H.S.=200 mm/min).

[Method for evaluating adhesion and punch-through suppression]
Using a gravure coater, the moisture-curing polyurethane hot melt resin composition obtained in the examples and comparative examples was intermittently applied to the polyurethane foam so as to be 20±5 g/m ² , and then bonded to a backing fabric nylon mesh. After aging for 24 hours at an environmental temperature of 23°C and an environmental humidity of 50% while applying a load of 2 kg/A4 size, the adhesion was measured using a tensile tester "Autograph AG-I" (manufactured by Shimadzu Corporation, H·S=200 mm/min). In addition, the penetration of the bonded product into the backing fabric mesh was visually confirmed. Note that those that did not have the moisture-curing polyurethane hot melt resin composition penetrated were evaluated as "◯", and those that did have the moisture-curing polyurethane hot melt resin composition penetrated were evaluated as "×". Note that "PUF" in the table indicates polyurethane foam.

It has been found that the moisture-curable polyurethane hot melt resin composition of the present invention has excellent mechanical strength, initial strength, and adhesion, and can suppress punch-through.

On the other hand, Comparative Example 1 is an embodiment in which aromatic polyester polyol (a2) and aliphatic polyester polyol (a3) are not used, but the initial strength was low and there was breakthrough.

On the other hand, in Comparative Example 2, which does not use aromatic polyester polyols (a1), (a2), and aliphatic polyester polyol (a3), the initial strength was lower than that of Comparative Example 1 and breakthrough occurred.

Claims (9)

A moisture-curable polyurethane hot melt resin composition comprising: an aromatic polyester polyol (a1) containing, as essential raw materials , neopentyl glycol and diethylene glycol ; an aromatic polyester polyol (a2) other than the (a1); an aliphatic polyester polyol (a3); a crystalline polyester polyol (a4) other than the (a3); and a polyether polyol (a5); and a urethane prepolymer (i) having an isocyanate group, which is a reaction product of a polyisocyanate (B). The moisture-curable polyurethane hot melt resin composition according to claim 1, wherein the aromatic polyester polyol (a1) and the aromatic polyester polyol (a2) are both made from aromatic polybasic acids. The moisture-curable polyurethane hot melt resin composition according to claim 1, wherein the aliphatic polyester polyol (a3) is made from a compound (x) that has a molecular weight of less than 500, a branched structure, and 2 to 4 hydroxyl groups per molecule. The moisture-curable polyurethane hot melt resin composition according to claim 1, wherein the polyether polyol (a5) is polypropylene glycol and/or polytetramethylene glycol. A cured product formed from the moisture-curable polyurethane hot melt resin composition according to claim 1. A laminate comprising a polyurethane foam, the cured material layer according to claim 5, and a base fabric. The laminate according to claim 6, wherein the cured layer of the moisture-curable polyurethane hot melt resin composition is formed by intermittent application. The laminate according to claim 6, wherein the base fabric is a mesh fabric. The skin material according to claim 6, further comprising a skin layer.