Moisture-curing urethane hot-melt resin composition, laminate, and synthetic leather

Abstract

Provided is a moisture-curable urethane hot-melt resin composition capable of forming a cured product layer having good initial adhesiveness, heat resistance, hydrolysis resistance, alcohol resistance, and abrasion resistance. A moisture-curable urethane hot-melt resin composition containing a reaction product of a polyol component and a polyisocyanate component, namely a urethane prepolymer having an isocyanate group. The polyol component includes a high molecular weight polyol component and a low molecular weight polyol component. The high molecular weight polyol component includes: at least one polyol (A) selected from the group consisting of SA-based polyester polyols (A1), 1,4-BD / AA-based polyester polyols (A2) having a number average molecular weight (Mn) of 8,000 or more, and 1,6-HD / AA-based polyester polyols (A3) having a Mn of 6,000 or more; and at least one polyol (B) selected from the group consisting of polyester polyols (B1) other than polyol (A) and polyether polyols (B2). The low molecular weight polyol component includes a trifunctional polyol (D) having 3 hydroxyl groups in one molecule and a molecular weight of 300 or less. The ratio of polyol (A) to trifunctional polyol (D) satisfies trifunctional polyol (D) (mmol) / polyol (A) (g) = 0.14 to 55 mmol / g.

Description

Technical Field

[0001] The present invention relates to a moisture-curable urethane hot-melt resin composition, a laminate, and a synthetic leatherette. Background Art

[0002] A moisture-curable urethane hot-melt resin composition is a composition that is solid at normal temperature and can be prepared without a solvent, and is a resin composition that cures by moisture after heat-melting and coating. Therefore, the moisture-curable urethane hot-melt resin composition is widely used as various environmentally friendly adhesives because it does not use a solvent. Such a moisture-curable urethane hot-melt resin composition contains a urethane prepolymer having a functional group such as an isocyanate group (NCO group) in the molecule, and this functional group can react with water (moisture) present in the air or the coated substrate to form a crosslinked structure.

[0003] When the moisture-curable urethane hot-melt resin composition is used as various adhesives, it exhibits adhesive strength by moisture curing, and thus it is difficult to exhibit excellent initial strength. Therefore, technologies aimed at exhibiting excellent initial adhesiveness have been proposed. For example, Patent Document 1 discloses a reactive hot-melt adhesive containing: a "urethane prepolymer (1)" derived from an organic polyisocyanate compound (a) and a specified polyol (b1) and having an NCO group; and a "low molecular weight xylene resin (d1)" having no active hydrogen and having tackiness.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 5-065471 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] The urethane prepolymer for the moisture-curable urethane resin composition can also be used as an adhesive when manufacturing synthetic leatherettes such as artificial leather and synthetic leather. Synthetic leatherettes are used as materials for manufacturing various products such as shoes, clothing, leather bags, furniture, and vehicle interior materials (such as instrument panels, doors, consoles, and seat cushions). Conventional synthetic leatherettes are usually laminates in which an epidermis layer, an adhesive layer (cured product layer), and a substrate layer are laminated in sequence, and the cured product layer is formed of various urethane prepolymers. For the cured product layer constituting the synthetic leatherettes used in the above various products, it is required to have not only good flexibility but also heat resistance capable of withstanding the heat during manufacturing and processing.

[0009] The initial adhesive force after curing of the reactive hot-melt adhesive disclosed in the above-mentioned Patent Document 1 can achieve certain effects under a specified humidity environment. However, such a conventional moisture-curing type urethane hot-melt resin composition has a low heat softening point after curing and fewer mesh structures after curing compared with a two-component curing type polyurethane resin composition. Therefore, there are limitations in its application to uses that require heat resistance and processing at high temperatures, such as the above-mentioned synthetic leather. In addition, when the conventional moisture-curing type urethane hot-melt resin composition is used for clothing applications, in addition to insufficient hydrolysis resistance to withstand washing, the abrasion resistance is also insufficient, and peeling from the substrate may occur due to friction such as rubbing.

[0010] Therefore, the present invention aims to provide a moisture-curing type urethane hot-melt resin composition capable of forming a cured product layer with good initial adhesiveness, heat resistance, flexibility, hydrolysis resistance, alcohol resistance, and abrasion resistance.

[0011] Means for solving the problems

[0012] The present invention provides a moisture-curing type urethane hot-melt resin composition containing a reaction product of a polyol component and a polyisocyanate component, namely a urethane prepolymer having an isocyanate group. The polyol component includes a high molecular weight polyol component and a low molecular weight polyol component. The high molecular weight polyol component includes at least one polyol (A) selected from the group consisting of a polyester polyol (A1) having a structural unit derived from sebacic acid, a polyester polyol (A2) having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and having a number average molecular weight of 8,000 or more, and a polyester polyol (A3) having a structural unit derived from 1,6-hexanediol and a structural unit derived from adipic acid and having a number average molecular weight of 6,000 or more; and at least one polyol (B) selected from the group consisting of a polyester polyol (B1) other than the polyol (A) and a polyether polyol (B2). The low molecular weight polyol component includes a trifunctional polyol (D) having a molecular weight of 300 or less and having 3 hydroxyl groups in one molecule. The ratio of the polyol (A) to the trifunctional polyol (D) satisfies trifunctional polyol (D) (mmol) / polyol (A) (g) = 0.14 to 55 mmol / g.

[0013] Effects of the invention

[0014] According to the present invention, it is possible to provide a moisture-curing type urethane hot-melt resin composition capable of forming a cured product layer with good initial adhesiveness, heat resistance, flexibility, hydrolysis resistance, alcohol resistance, and abrasion resistance. Brief description of the drawings

[0015] Figure 1It is a schematic explanatory drawing explaining the form of the specimen used in the evaluation of the example.

[0016] Figure 2 It is an explanatory drawing explaining the form of the gear oven used in the evaluation of the example. Detailed implementation mode

[0017] Hereinafter, the embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0018] <Moisture-curable urethane hot-melt resin composition>

[0019] The moisture-curable urethane hot-melt resin composition (hereinafter sometimes simply referred to as "resin composition") of one embodiment of the present invention contains a reaction product of a polyol component and a polyisocyanate component, that is, a urethane prepolymer. This urethane prepolymer has an isocyanate group. Through the isocyanate group, the urethane prepolymer can react with water (moisture) present in the air or in the substrate coated with the resin composition to form a crosslinked structure. Therefore, the resin composition mainly composed of this urethane prepolymer has moisture-curability.

[0020] The polyol component for the urethane prepolymer contains a high-molecular polyol component and a low-molecular polyol component. The high-molecular polyol component contains the following polyols (A) and (B). Polyol (A) is at least one selected from the group consisting of polyester polyol (A1) having a structural unit derived from sebacic acid, polyester polyol (A2) having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and having a number-average molecular weight of 8,000 or more, and polyester polyol (A3) having a structural unit derived from 1,6-hexanediol and a structural unit derived from adipic acid and having a number-average molecular weight of 6,000 or more. Polyol (B) is at least one selected from the group consisting of polyester polyol (B1) other than the above polyol (A) and polyether polyol (B2). In addition, the low-molecular polyol component contains a trifunctional polyol (D) having 3 hydroxyl groups in one molecule and a molecular weight of 300 or less. And in this resin composition, the ratio of polyol (A) to trifunctional polyol (D) satisfies trifunctional polyol (D) (mmol) / polyol (A) (g) = 0.14 to 55 mmol / g.

[0021] According to the above constitution, the moisture-curable urethane hot-melt resin composition of the present embodiment can form a cured layer having good initial adhesiveness, heat resistance, flexibility, hydrolysis resistance, alcohol resistance, and abrasion resistance. Further, in one aspect, the resin composition has good stability over time in a molten state. In addition, in one aspect, the resin composition can contribute to providing synthetic artificial leather having good cold-resistant bendability, hydrolysis resistance, flexibility, abrasion resistance, and heat resistance.

[0022] From the viewpoint of easily obtaining the above effects and the like, the preferred constitution and the like of the resin composition of the present embodiment will be described in detail below. It should be noted that in the following description of the compounds (each polyol component, polyisocyanate component, etc.), unless otherwise specified, any one or two or more compounds in the specification can be used.

[0023] [Urethane prepolymer]

[0024] The urethane prepolymer is a reaction product of a polyol component and a polyisocyanate component and has an isocyanate group. The urethane prepolymer is preferably obtained by the addition polymerization reaction of a polyol component and a polyisocyanate component, more preferably obtained by the addition polymerization of a polyol component and an excess polyisocyanate component, and has an isocyanate group at the terminal.

[0025] The equivalent ratio (molar ratio; NCO group / OH group) of the isocyanate group (NCO group) of the polyisocyanate component to the hydroxyl group (OH group) of the polyol component constituting the urethane prepolymer is preferably 1.1 to 2.2, more preferably 1.4 to 2.0, and still more preferably 1.5 to 1.9. By setting the NCO group / OH group within the above range, the processability at high temperatures when used for clothing applications and the like is improved, and synthetic artificial leather with a better feel can be manufactured.

[0026] From the viewpoint of making the resin composition exhibit moisture-curing properties, the urethane prepolymer is preferably the main component of the resin composition. Based on the mass of the solid content of the resin composition, the content of the urethane prepolymer can be 100% by mass, preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more.

[0027] [Polyol component]

[0028] The polyol component for the urethane prepolymer includes a high-molecular polyol component and a low-molecular polyol component. The high-molecular polyol component is a group of polyols having a higher molecular weight than the low-molecular polyol component, and polymers are preferably used. The low-molecular polyol component is a group of polyols having a lower molecular weight than the high-molecular polyol component.

[0029] (High-molecular polyol component)

[0030] The high molecular weight polyol component for the urethane prepolymer contains the following polyol (A) and polyol (B) other than polyol (A). In the polyol component, the high molecular weight polyol component is preferably the main component of the polyol component and is preferably used in an amount larger than that of the low molecular weight polyol component. Based on the total amount of the polyol component, the proportion of the high molecular weight polyol component in the polyol component is preferably 60 to 99.8% by mass, more preferably 80 to 99.5% by mass, and still more preferably 90 to 99% by mass.

[0031] (Polyol (A))

[0032] Polyol (A) is at least one selected from the group consisting of the following polyester polyols (A1) to (A3).

[0033] (A1): Polyester polyol (A1) having a structural unit derived from sebacic acid

[0034] (A2): Polyester polyol (A2) having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and having a number average molecular weight of 8,000 or more

[0035] (A3): Polyester polyol (A3) having a structural unit derived from 1,6-hexanediol and a structural unit derived from adipic acid and having a number average molecular weight of 6,000 or more

[0036] The above polyester polyols (A1) to (A3) are crystalline polyols and can be in a solid state at 60°C. By using polyol (A), the resin composition can form a cured layer with good initial adhesiveness and flexibility, and in addition, it is easy to obtain a synthetic artificial leather with further excellent cold resistance bending property, flexibility and heat resistance. From these viewpoints, it is preferable to use at least polyester polyol (A1) in polyol (A).

[0037] Polyester polyol (A1) has a structural unit derived from sebacic acid (SA). Hereinafter, the polyester polyol having a structural unit derived from sebacic acid is sometimes referred to as "SA-based polyester polyol". SA-based polyester polyol (A1) is a reaction product of sebacic acid and a diol and is a bifunctional (hydroxyl number 2) polyol (diol). Preferably, it is SA-based polyester polyol (A1) obtained by polycondensation of sebacic acid and a diol.

[0038] As the diols for the SA-based polyester polyol (A1), for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, hexanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 1,9-nonanediol, neopentyl glycol, etc. can be cited. Among them, 1,6-hexanediol is preferred. That is, the polyester polyol (A1) is preferably a polyester polyol having a structural unit derived from sebacic acid and a structural unit derived from 1,6-hexanediol (hereinafter sometimes referred to as "1,6-HD / SA-based polyester polyol").

[0039] The number average molecular weight (Mn) of the SA-based polyester polyol (A1) is preferably 2,000 or more, more preferably 3,000 or more, further preferably 5,000 or more, and preferably 20,000 or less. The "number average molecular weight (Mn)" in this specification is a value converted to standard polystyrene measured by gel permeation chromatography (GPC). Specifically, dimethylformamide (DMF) is used as the mobile phase, and the measurement is carried out by GPC analysis under the following conditions (the same applies to the following examples).

[0040] · Measuring device: High-speed GPC device (trade name "HLC-8220GPC", manufactured by Tosoh Corporation)

[0041] · Column: TSK gel Super HM-N × 2 columns,

[0042] TSK guardcolumn Super H-H × 1 column

[0043] · Detector: RI (differential refractometer)

[0044] · Column temperature: 40 °C

[0045] · Flow rate: 0.5 mL / min

[0046] · Injection volume: 50 μL

[0047] The polyester polyol (A2) has a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid. Hereinafter, the polyester polyol having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid is sometimes referred to as "1,4-BD / AA-based polyester polyol". The 1,4-BD / AA-based polyester polyol (A2) is a reaction product of 1,4-butanediol and adipic acid and is a difunctional (hydroxyl number 2) polyol (diol). The polyester polyol (A2) preferably obtained by polycondensation of 1,4-butanediol and adipic acid is preferred.

[0048] The number average molecular weight (Mn) of the 1,4-BD / AA-based polyester polyol (A2) is 8,000 or more. By using the 1,4-BD / AA-based polyester polyol (A2) with Mn of 8,000 or more, the resin composition can form a cured product layer with good initial adhesiveness, and furthermore, it is easy to obtain a synthetic leather with better cold resistance bending property and flexibility. The Mn of the 1,4-BD / AA-based polyester polyol (A2) is preferably 20,000 or less.

[0049] The polyester polyol (A3) has a structural unit derived from 1,6-hexanediol and a structural unit derived from adipic acid. Hereinafter, the polyester polyol having a structural unit derived from 1,6-hexanediol and a structural unit derived from adipic acid may sometimes be referred to as "1,6-HD / AA-based polyester polyol". The 1,6-HD / AA-based polyester polyol (A3) is a reaction product of 1,6-hexanediol and adipic acid, and is a difunctional (number of hydroxyl groups: 2) polyol (diol). The polyester polyol (A3) preferably obtained by polycondensation of 1,6-hexanediol and adipic acid.

[0050] The number average molecular weight (Mn) of the 1,6-HD / AA-based polyester polyol (A3) is 6,000 or more. By using the 1,6-HD / AA-based polyester polyol (A3) with Mn of 6,000 or more, the resin composition can form a cured product layer with good initial adhesiveness, and furthermore, it is easy to obtain a synthetic leather with better cold resistance bending property and flexibility. The Mn of the 1,6-HD / AA-based polyester polyol (A3) is preferably 20,000 or less.

[0051] From the perspective that the above effects of the polyol (A) can be easily balanced with the effects of other polyols described later, based on the total amount of the high molecular weight polyol component, the proportion of the polyol (A) in the high molecular weight polyol component is preferably 0.5 to 30% by mass, more preferably 1 to 20% by mass, and further preferably 2 to 15% by mass.

[0052] (Polyol (B))

[0053] The polyol (B) is at least one selected from the group consisting of a polyester polyol (B1) other than the above polyol (A) and a polyether polyol (B2).

[0054] The polyester polyol (B1) and the polyether polyol (B2) other than the polyol (A) are polyols with lower crystallinity than the polyol (A), and can be in a liquid state at 60°C. By using at least one of the polyester polyol (B1) and the polyether polyol (B2), the resin composition can form a cured product layer with good flexibility, and furthermore, it is easy to obtain a synthetic leather with good cold resistance bending property, flexibility, etc.

[0055] The polyester polyol (B1) is a polyester polyol other than the above-mentioned SA-based polyester polyol (A1), 1,4-BD / AA-based polyester polyol (A2) with a Mn of 8,000 or more, and 1,6-HD / AA-based polyester polyol (A3) with a Mn of 6,000 or more. The polyester polyol (B1) is a reaction product of a dicarboxylic acid and a diol, and is a diol (a dihydric alcohol) with two functional groups (two hydroxyl groups). Preferably, the polyester polyol (B1) is obtained by polycondensation of a dicarboxylic acid and a diol.

[0056] Examples of the dicarboxylic acids used for the polyester polyol (B1) include aliphatic dicarboxylic acids such as succinic acid, adipic acid, glutaric acid, and azelaic acid; and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid. Examples of the diols used for the polyester polyol (B1) include the same alcohols as those described in the description of the SA-based polyester polyol (A1).

[0057] Specific examples of the polyester polyol (B1) include polyethylene adipate diol, polybutylene adipate diol, polyhexylene adipate diol, neopentyl glycol adipate diol, ethylene glycol / butylene glycol adipate copolymer, neopentyl glycol / hexylene glycol adipate copolymer, poly-3-methylpentane adipate diol, and polybutylene isophthalate diol.

[0058] Among the polyester polyols (B1), a 1,4-BD / AA-based polyester polyol (B1) having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and a number-average molecular weight (Mn) of 1,000 to 5,000 is preferred. Among them, polybutylene adipate diol with a Mn of 1,200 to 4,000 is more preferred, and polybutylene adipate diol with a Mn of 1,500 to 3,000 is further preferred.

[0059] The polyether polyol (B2) is a diol (a dihydric alcohol) with two functional groups (two hydroxyl groups). The polyether polyol (B2) can be obtained, for example, by polymerizing or copolymerizing any one of alkylene oxides (ethylene oxide, propylene oxide, and butylene oxide, etc.) and heterocyclic ethers (tetrahydrofuran, and 2-methyltetrahydrofuran, etc.). In addition, the polyether polyol (B2) can also be obtained by dehydration condensation reaction of a diol such as 1,3-propanediol.

[0060] Examples of the polyether polyol (B2) include polyethylene glycol, polypropylene glycol, polyethylene glycol-poly(tetramethylene glycol) (block or random), polytrimethylene ether glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol. Among them, from the perspective of flexibility, polyethylene glycol, polytrimethylene ether glycol, and polytetramethylene ether glycol are preferred.

[0061] In one aspect of the moisture-curing urethane hot-melt resin composition, from the perspective of further forming an environmentally friendly composition, the polyol (B) (the above polyester polyol (B1) and / or polyether polyol (B2)) preferably contains a polyol (B b ) using plant-derived raw materials. The polyol (B b ) using plant-derived raw materials can be called a biomass polyol (B b ). As the polyol (B b ) using plant-derived raw materials, for example, polyester polyols (B b 1) and polyether polyols (B b 2) containing one or more of diols derived from plants (preferably diols having 2 to 4 carbon atoms) as raw materials can be cited; and polyether polyols (B b 2) such as those using tetrahydrofuran from plants, etc. As the diols having 2 to 4 carbon atoms derived from plants, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, etc. derived from plants can be cited.

[0062] From the perspective that the above effects of the polyol (B) can be easily balanced with the effects of other polyols and well expressed, based on the total amount of the high-molecular polyol component, the proportion of the polyol (B) in the high-molecular polyol component is preferably 10 to 98% by mass, more preferably 50 to 95% by mass, and further preferably 60 to 90% by mass.

[0063] (Polycarbonate polyol (C))

[0064] The high-molecular polyol component preferably contains a polycarbonate polyol (C) in addition to the above polyol (A) and polyol (B). By using the polycarbonate polyol (C), a cured product layer and synthetic artificial leather with further excellent hydrolysis resistance and abrasion resistance can be easily obtained.

[0065] The polycarbonate polyol (C) can be obtained, for example, by condensing diols such as 1,4-butanediol and 1,6-hexanediol with a dialkyl carbonate while performing a dealcoholization reaction. The polycarbonate polyol (C) is a bifunctional (hydroxyl number 2) polyol (diol), and in addition, crystalline and amorphous substances can be optionally used.

[0066] Examples of the polycarbonate polyol (C) include polytetramethylene carbonate diol, polypentamethylene carbonate diol, polyneopentyl carbonate diol, polyhexamethylene carbonate diol, poly(1,4-cyclohexane dimethylene carbonate) diol, and random / block copolymers thereof. Among them, polyhexamethylene carbonate diol (polycarbonate diol based on 1,6-hexanediol), poly(tetramethylene / decamethylene) carbonate diol (polycarbonate diol based on 1,4-butanediol and 1,10-decanediol), and poly(pentamethylene / hexamethylene) carbonate diol (carbonate diol based on 1,5-pentanediol and 1,6-hexanediol) are preferred.

[0067] In one aspect of the moisture-curable urethane hot-melt resin composition, from the perspective of further forming an environmentally friendly composition, the polycarbonate polyol (C) preferably contains a polycarbonate polyol (C b ) using plant-derived raw materials. The polycarbonate polyol (C b ) using plant-derived raw materials can be referred to as a biomass polycarbonate polyol (C b ). Examples of the polycarbonate polyol (C b ) using plant-derived raw materials include polycarbonate polyols (C b ) using one or more of the diols derived from plants (preferably diols having 2 to 10 carbon atoms) as raw materials. Examples of the diols derived from plants include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 1,10-decanediol derived from plants.

[0068] From the perspective that the above effects of the polycarbonate polyol (C) can be easily balanced with the effects of the polyols (A) and (B) well, based on the total amount of the high molecular weight polyol component, the proportion of the polycarbonate polyol (C) in the high molecular weight polyol component is preferably 0 to 80% by mass, more preferably 4 to 40% by mass, and still more preferably 8 to 30% by mass.

[0069] When the high molecular weight polyol component contains a polycarbonate polyol (C), from the perspective of easily obtaining the target moisture-curing urethane hot-melt resin composition of the present disclosure, the total amount of the polyol (B) and the polycarbonate polyol (C) is preferably more than the amount of the polyol (A). In addition, in this case, the proportion of the total amount (total mass) of the polyol (A), the polyol (B), and the polycarbonate polyol (C) relative to the total amount (total mass) of the polyol component is preferably 90% by mass or more. The total amount of the polyol (A), the polyol (B), and the polycarbonate polyol (C) can be the total amount of the high molecular weight polyol component. Therefore, as described above, regarding the proportion of the high molecular weight polyol component in the polyol component, the proportion of the total amount of the polyol (A), the polyol (B), and the polycarbonate polyol (C) relative to the total amount of the polyol component is preferably 99.8% by mass or less, more preferably 99.5% by mass or less, and further preferably 99% by mass or less.

[0070] (Low molecular weight polyol component)

[0071] The low molecular weight polyol component for the urethane prepolymer is preferably used in an amount less than that of the above high molecular weight polyol component in the polyol component. Based on the total amount of the polyol component, the proportion of the low molecular weight polyol component in the polyol component is preferably 0.2 to 40% by mass, more preferably 0.5 to 20% by mass, and further preferably 1 to 10% by mass.

[0072] (Trifunctional polyol (D))

[0073] The low molecular weight polyol component for the urethane prepolymer contains a trifunctional polyol (D) having a molecular weight (chemical formula weight) of 300 or less and having 3 hydroxyl groups in one molecule. In addition to the trifunctional polyol (D), the low molecular weight polyol component may contain other low molecular weight polyols (E) as needed.

[0074] Since the trifunctional polyol (D) has 3 hydroxyl groups in one molecule, it can be called a triol (D). By using this specific low molecular weight trifunctional polyol (D), the target moisture-curing urethane hot-melt resin composition of the present disclosure can be obtained.

[0075] Examples of the trifunctional polyol (D) having a molecular weight of 300 or less include glycerol, trimethylolethane, trimethylolpropane, butanetriol, pentanetriol, hexanetriol, heptanetriol, and octanetriol. Among them, glycerol and trimethylolpropane are preferred.

[0076] The amount of the trifunctional polyol (D) used is in the following range in relation to the above polyol (A). That is, the ratio of the polyol (A) to the trifunctional polyol (D) satisfies trifunctional polyol (D) (mmol) / polyol (A) (g)=0.14-55 mmol / g. By making the amount of the trifunctional polyol (D) 0.14 mmol or more and 55 mmol or less per unit mass (1 g) of the polyol (A), the target moisture-curing urethane hot-melt resin composition of the present disclosure can be obtained. From the perspective of easily obtaining the target resin composition, trifunctional polyol (D) (mmol) / polyol (A) (g) is preferably 0.3 mmol / g or more, more preferably 0.5 mmol / g or more, and still more preferably 1 mmol / g or more. In addition, trifunctional polyol (D) (mmol) / polyol (A) (g) is preferably 30 mmol / g or less, more preferably 20 mmol / g or less, and still more preferably 10 mmol / g or less.

[0077] From the perspective that the above effects of the trifunctional polyol (D) are easily manifested, based on the total amount of the low-molecular-weight polyol component, the proportion of the trifunctional polyol (D) in the low-molecular-weight polyol component is preferably 50-100% by mass, more preferably 70-100% by mass, and still more preferably 90-100% by mass.

[0078] As other low-molecular-weight polyols (E), for example, low-molecular-weight diols and low-molecular-weight polyols having 4 or more functional groups can be cited. As the low-molecular-weight diols, for example, the same alcohols as those described in the description of the SA-based polyester polyol (A1) can be cited. As the low-molecular-weight polyols having 4 or more functional groups, for example, diglycerol, pentaerythritol, and dipentaerythritol can be cited.

[0079] 〔Polyisocyanate component〕

[0080] The polyisocyanate component for the urethane prepolymer is not particularly limited, and a compound having 2 or more isocyanate groups in one molecule (polyisocyanate) can be used. As the polyisocyanate, aromatic diisocyanates, alicyclic diisocyanates, aliphatic diisocyanates, and aliphatic diisocyanate modified bodies can be cited. Among them, aromatic diisocyanates, alicyclic diisocyanates, and aliphatic diisocyanate modified bodies are preferred, aromatic diisocyanates and aliphatic diisocyanate modified bodies are more preferred, and aromatic diisocyanates are still more preferred.

[0081] As the aromatic diisocyanate, for example, 4,4'-diphenylmethane diisocyanate (MDI), 2,2'-MDI, 2,4'-MDI, 2,4-toluene diisocyanate (TDI), 2,6-TDI, m-xylylene diisocyanate (XDI), 1,4-phenylene diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, benzidine diisocyanate, etc. can be cited. Among them, MDI is preferred.

[0082] As the alicyclic diisocyanate, for example, 4,4'-methylenebis(cyclohexyl isocyanate), isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated XDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), 1-methylcyclohexane-2,4-diisocyanate (hydrogenated TDI), etc. can be cited.

[0083] As the aliphatic diisocyanate, for example, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 1,10-decamethylene diisocyanate, etc. can be cited.

[0084] As the modified body of the aliphatic diisocyanate, for example, the isocyanurate body, urethane body, biuret body of the aliphatic diisocyanate, and the adduct with polyol (such as trimethylolpropane), etc. can be cited. Among them, the urethane body of the aliphatic diisocyanate is preferred, and the urethane body of HDI is more preferred.

[0085] [Manufacturing method of urethane prepolymer]

[0086] The urethane prepolymer can be manufactured, for example, by reacting the polyol component and the polyisocyanate component by a one-step method or a multi-step method at a temperature preferably of 60 to 150°C, more preferably 60 to 110°C, until the product reaches the theoretical NCO group content rate (mass %). When the polyol component and the polyisocyanate component react, a catalyst can be used in combination as needed. As the catalyst, metal salts and organometallic derivatives such as dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, lead octoate, tetra-n-butyl titanate, etc.; organic amines such as triethylamine; diazabicycloundecene-based catalysts, etc. can be cited.

[0087] The polyol component and the polyisocyanate component preferably react in the absence of solvents such as organic solvents, that is, under solvent-free conditions. By reacting the polyol component with the polyisocyanate component in the absence of solvents such as organic solvents, a solvent-free urethane prepolymer can be obtained.

[0088] It is preferable to use various polyols so that the amount of the polyol component used in the production of the urethane prepolymer falls within the above-mentioned ratio range for the polyol component. For example, regarding the high molecular weight polyol component, it is preferable to use the polyol (A), the polyol (B), and the polycarbonate polyol (C) used as needed, respectively, in amounts within the above-mentioned ratio range in the high molecular weight polyol component. In addition, regarding the trifunctional polyol (D) used as the low molecular weight polyol component, it is preferable to use it in an amount within the ratio range of the low molecular weight polyol component in the above-mentioned polyol component. As a preferred example, relative to 100 parts by mass of the total of the polyol (A), the polyol (B), and the polycarbonate polyol (C), the amount of the trifunctional polyol (D) used is preferably 0.5 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and still more preferably 0.5 to 10 parts by mass.

[0089] The moisture-curable urethane hot-melt resin composition can be appropriately blended with various additives such as a thermoplastic resin, a tackifying resin, a catalyst, a pigment, an antioxidant, an ultraviolet absorber, a surfactant, a flame retardant, a filler, and a foaming agent as needed. Among them, the moisture-curable urethane hot-melt resin composition can consist essentially of only the above-mentioned urethane prepolymer. Even when the resin composition consists essentially of only the urethane prepolymer, components that inevitably exist due to the production of the urethane prepolymer can be included in the composition.

[0090] As described above, in one mode, the moisture-curable urethane hot-melt resin composition has good stability over time in a molten state and can form a cured product layer with good initial adhesiveness, heat resistance, alcohol resistance, softness, hydrolysis resistance, and abrasion resistance. Therefore, the resin composition can be suitably used for applications that require heat resistance or high-temperature processability, such as synthetic artificial leather, and applications that require wash resistance or abrasion resistance, such as clothing, and is expected to expand processability and applications.

[0091] In addition, by using the moisture-curable urethane hot-melt resin composition, laminates such as synthetic artificial leather with good cold flex resistance, hydrolysis resistance, softness, abrasion resistance, and heat resistance can be provided. For example, the above-mentioned resin composition can be used as a hot-melt adhesive for bonding a base material layer such as a base cloth constituting synthetic artificial leather and an epidermal layer. In addition, since the resin composition can form a cured product layer with good initial adhesiveness and abrasion resistance, it can form a cured product layer that maintains the performance of good adhesion to a base material layer such as a base cloth and has properties such as abrasion resistance as an epidermal layer.

[0092] <Laminates>

[0093] A laminate according to an embodiment of the present invention includes a substrate and a cured product layer of the above-described moisture-curable urethane hot-melt resin composition provided on the substrate. When using the above resin composition as a hot-melt adhesive, one substrate can be used as one adherend and another substrate can be used as another adherend, and they can be bonded. As the substrate (adherend), in addition to the skin layer and substrate layer for synthetic leather described later, examples of film-like or sheet-like substrates include optical films, optical plates, flexible printed circuit boards, glass substrates, and substrates with ITO vapor-deposited on these substrates; and substrates of metals and non-metals (plastics, glass, etc.).

[0094] The laminate is preferably manufactured by coating a moisture-curable urethane hot-melt resin composition melted at 80 to 130°C onto a substrate and curing it with moisture to form a cured product layer. When using the above resin composition as a hot-melt adhesive, the melted above resin composition is coated onto one substrate, and then another substrate is pasted thereon and moisture-cured.

[0095] The method of coating the moisture-curable urethane hot-melt resin composition onto the substrate is not particularly limited, and the coating methods of conventional hot-melt adhesives can be appropriately adopted. As the coating method, for example, comma coating method, knife coating method, roll coating method, screen coating method, T-die coating method, fiber coating method, gravure transfer coating method engraved on a roll, die coating machine method with a gear pump, etc. can be cited.

[0096] The laminate of this embodiment can also be configured as the synthetic leather described later. In addition, as described above, since the cured product layer of the moisture-curable urethane hot-melt resin composition for the laminate has good initial adhesiveness and abrasion resistance, an epidermis layer that can be directly bonded to a substrate such as a base fabric constituting the synthetic leather can be formed. Therefore, a synthetic leather having a two-layer structure of a substrate such as a base fabric and an epidermis layer composed of the above cured product layer provided on the substrate can be provided.

[0097] A synthetic leather having a cured product layer of a moisture-curable urethane hot-melt resin composition as the epidermis layer can be manufactured, for example, as follows. First, by the above coating method, the moisture-curable urethane hot-melt resin composition forming the epidermis layer is melt-coated on a release paper, a substrate such as a base fabric is pasted thereon, and the above resin composition is cured with moisture to form a cured product layer (epidermis layer). Then, by peeling it from the release paper, a synthetic leather having a two-layer structure of a substrate and an epidermis layer composed of a cured product layer provided on the substrate can be obtained. It should be noted that when pasting a substrate such as a base fabric, for example, a laminator equipped with a roll can be used for crimping. In addition, when curing the above resin composition with moisture, it can be aged under specified temperature and humidity conditions.

[0098] <Synthetic artificial leather>

[0099] The synthetic artificial leather according to an embodiment of the present invention includes a base material layer, a skin layer, and an adhesive layer provided therebetween and bonding them. And in this synthetic artificial leather, the adhesive layer is formed of a cured product layer of the above moisture-curable urethane hot-melt resin composition.

[0100] Examples of the base fabric constituting the base material layer include woven fabrics including twill, plain weave, etc., napped fabrics obtained by mechanically raising the cotton grey fabric of the woven fabric, rayon fabrics, nylon fabrics, polyester fabrics, Kevlar (registered trademark) fabrics, non-woven fabrics (polyester, nylon, various latexes), various films, sheets, etc. In addition, examples of the skin layer include those formed of coating materials for forming the skin layer such as solution-type urethane resin compositions, aqueous polyurethanes, and thermoplastic polyurethanes (TPU).

[0101] The synthetic artificial leather can be manufactured as follows. First, using known methods such as comma coating, knife coating, roll coating, gravure coating, die coating, spraying, etc., a coating material for forming the skin layer is coated on a release paper. After appropriately drying the coated coating material to form the skin layer, the above moisture-curable urethane hot-melt resin composition in a molten state is coated on the skin layer by the above coating method, and a base material layer such as a base fabric is pasted thereon and pressed using a laminator or the like. Then, if necessary, it is cured under specified temperature and humidity conditions to form a cured product layer (adhesive layer). Next, by peeling off the release paper, the target synthetic artificial leather can be obtained.

[0102] A surface treatment agent can be coated on the surface of the skin layer (including the skin layer composed of a cured product layer described in the description of the above laminate). By performing surface treatment on the skin layer using the surface treatment agent, a synthetic artificial leather having a quality further suitable for productization can be obtained. The synthetic artificial leather of this embodiment is suitable as a material for constituting shoes, clothing, leather bags, furniture, vehicle interior materials (such as instrument panels, doors, consoles, seat cushions), etc.

[0103] It should be noted that, as described above, the following configuration can be adopted in an embodiment of the present invention.

[0104] [1] A moisture-curable urethane hot-melt resin composition containing a reaction product of a polyol component and a polyisocyanate component, that is, a urethane prepolymer having an isocyanate group,

[0105] The polyol component includes a high-molecular polyol component and a low-molecular polyol component,

[0106] The high-molecular polyol component includes:

[0107] A polyol (A) selected from at least one member of the group consisting of a polyester polyol (A1) having a structural unit derived from sebacic acid, a polyester polyol (A2) having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and having a number-average molecular weight of 8,000 or more, and a polyester polyol (A3) having a structural unit derived from 1,6-hexanediol and a structural unit derived from adipic acid and having a number-average molecular weight of 6,000 or more; and

[0108] A polyol (B) selected from at least one member of the group consisting of a polyester polyol (B1) other than the polyol (A) and a polyether polyol (B2),

[0109] The low molecular weight polyol component contains a trifunctional polyol (D) having a molecular weight of 300 or less and having 3 hydroxyl groups in one molecule,

[0110] The ratio of the polyol (A) to the trifunctional polyol (D) satisfies trifunctional polyol (D) (mmol) / polyol (A) (g) = 0.14 to 55 mmol / g.

[0111] [2] The moisture-curable urethane hot-melt resin composition according to [1] above, wherein the polyol (B) contains a polyol (B b ) using a plant-derived raw material.

[0112] [3] The moisture-curable urethane hot-melt resin composition according to [1] or [2] above, wherein the high molecular weight polyol component further contains a polycarbonate polyol (C).

[0113] [4] The moisture-curable urethane hot-melt resin composition according to [3] above, wherein the polycarbonate polyol (C) contains a polycarbonate polyol (C b ) using a plant-derived raw material.

[0114] [5] The moisture-curable urethane hot-melt resin composition according to [3] or [4] above, wherein the total amount of the polyol (B) and the polycarbonate polyol (C) is more than the amount of the polyol (A),

[0115] The proportion of the total of the polyol (A), the polyol (B) and the polycarbonate polyol (C) relative to the total amount of the polyol component is 90% by mass or more.

[0116] [6] A laminate having: a substrate, and a cured product layer of the moisture-curable urethane hot-melt resin composition according to any one of [1] to [5] above provided on the substrate.

[0117] [7]A synthetic artificial leather, which comprises a base material layer, an epidermis layer, and an adhesive layer disposed therebetween and bonding them, and the adhesive layer is a cured product layer of the moisture-curing urethane hot-melt resin composition according to any one of the above [1] to [5].

[0118] Examples

[0119] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0120] <Materials>

[0121] The polymer polyol materials used are shown in Table 1 below.

[0122] Table 1

[0123]

[0124] <Manufacture of Moisture-Curing Urethane Hot-Melt Resin Composition>

[0125] (Example 1)

[0126] In a glass reaction vessel equipped with a stirrer, a thermometer, and a gas inlet, a polyol component and a polyisocyanate component were added and mixed, and the inside of the reaction vessel was heated under reduced pressure for dehydration treatment. Further, nitrogen was sealed, and the reaction was carried out while stirring for 120 minutes at an internal temperature of 100 °C. The above polyol component used a polymer polyol component (total 100 parts by mass) containing 10 parts by mass of polyester polyol (A1), 45 parts by mass of polyester polyol (B1-1), and 45 parts by mass of polyether polyol (B2-1), and 0.5 part by mass of trimethylolpropane as a trifunctional polyol (D) component having a molecular weight of 300 or less. The ratio of the trifunctional polyol (D) to the polyol (A) was set to trifunctional polyol (D) (mmol) / polyol (A) (g) = 0.37 mmol / g. The above polyisocyanate component used 22.35 parts by mass of 4,4'-diphenylmethane diisocyanate (MDI), and the molar ratio of the NCO group of MDI to the OH group of the polyol component (NCO group / OH group) was set to 1.7. Thus, the urethane prepolymer of Example 1 was obtained.

[0127] (Examples 2 to 17 and Comparative Examples 1 to 10)

[0128] Except for changing the types and amounts of polyol components and the amount of polyisocyanate component (MDI) as shown in the upper part of Table 2 (Tables 2-1 to 2-6) below, urethane prepolymers of each example were obtained in the same manner as in Example 1. Along with the change in the amounts of polyol components and polyisocyanate components used, the values of "3-functional polyol (D) / polyol (A) [mmol / g]" and "NCO group / OH group (molar ratio)" are shown together in the middle part of Table 2. It should be noted that in Comparative Example 10 where 3-functional polyol (D) (mmol) / polyol (A) (g) = 56.0 mmol / g, gelation occurred during the stirring reaction, and the evaluation described below could not be carried out.

[0129] <Evaluation>

[0130] As the moisture-curable urethane hot-melt resin composition of each example (hereinafter sometimes simply referred to as "hot-melt resin composition"), the urethane prepolymers obtained in each example were evaluated as follows. In the evaluation criteria for each item, AA, A, and B are acceptable good levels, and C is an unacceptable level. The evaluation results are shown in the lower part of Table 2.

[0131] (Stability over time in the molten state)

[0132] The hot-melt resin composition of each example was heated to 100 °C and melted, and the change in viscosity over time and the confirmation of visually observed precipitates were carried out under the conditions of 100 °C for 24 hours. Regarding the viscosity of the hot-melt resin composition, a BM-type viscometer (manufactured by Tokyo Instruments) was used to measure it under the conditions of rotor No. 4, 30 rpm, and 100 °C. Based on the change in viscosity over time (viscosity change rate) and the presence or absence of precipitates, the stability over time of the hot-melt resin composition in the molten state was evaluated according to the following evaluation criteria. The viscosity change rate was calculated by viscosity change rate (%) = { (viscosity after 24 hours at 100 °C - initial viscosity at 100 °C) / initial viscosity at 100 °C} × 100.

[0133] AA: No precipitate, viscosity change rate less than 20%.

[0134] A: No precipitate, viscosity change rate of 20% or more and less than 50%.

[0135] B: Precipitate present, viscosity change rate less than 100%.

[0136] C: Precipitate present, viscosity change rate of 100% or more.

[0137] (Production of evaluation film)

[0138] The hot-melt resin composition of each example was melted at 100 °C and coated onto a release paper so that the film thickness after coating was 50 to 70 μm. Then, it was cured for 72 hours in an environment of 25 °C and 60% relative humidity (60% RH), and further stored at room temperature (20 °C) for 1 day to obtain a film for evaluation with release paper.

[0139] (Heat softening point)

[0140] The heat softening point was measured using an evaluation film (1.5 cm wide and 6 cm long) obtained by peeling the release paper from the film for evaluation with release paper. Specifically, first, as Figure 1 shown, clamps 12 were installed above and below the evaluation film 10, and the clamps 12 were further fixed using CELLOTAPE (registered trademark). When hanging from one clamp 12, a weight 14 applying a load of 450 g / cm 2 was installed to produce a specimen 16. It should be noted that a 2-cm lengthwise portion in the center of the evaluation film 10 was not covered by CELLOTAPE (registered trademark). Next, as Figure 2 shown, the clamp 12 of the specimen 16 without the weight 14 installed was installed on the rotating disk 22 of the gear oven 20. Then, the rotating disk 22 was rotated at 5 rpm, and at the same time, the temperature inside the gear oven 20 was raised from room temperature at a rate of 3 °C per minute. The temperature (°C) at which the evaluation film 10 breaks or elongates to twice its original length was taken as the heat softening point. Based on the value of its heat softening point (°C), the heat resistance based on the heat softening point was evaluated according to the following evaluation criteria. The higher the heat softening point, the higher the heat resistance as a film.

[0141] A: The heat softening point is 185 °C or higher.

[0142] B: The heat softening point is 170 °C or higher and less than 185 °C.

[0143] C: The heat softening point is less than 170 °C.

[0144] (Alcohol resistance)

[0145] The evaluation film obtained by peeling the release paper from the film for evaluation with release paper was cut into 50 mm × 50 mm and immersed in ethanol at 25 °C placed in a petri dish for 10 minutes. After 10 minutes, the evaluation film was taken out of the ethanol, and the state of the evaluation film was visually confirmed. The alcohol resistance was evaluated according to the following evaluation criteria. The following linear swelling rate was calculated by linear swelling rate (%) = (length of one side of the evaluation film after immersion (mm) / length of one side of the evaluation film before immersion (50 mm)) × 100.

[0146] AA: The linear swelling rate of one side of the evaluation film is less than 120%.

[0147] A: The linear swelling rate of one side of the evaluation film is 120% or more and less than 150%.

[0148] B: The linear swelling rate of one side of the evaluation film is 150% or more.

[0149] C: The evaluation film dissolves.

[0150] (Initial adhesiveness)

[0151] Heat the hot-melt resin composition of each example to 100 °C to melt it, and uniformly coat it on a PET film (width 3 cm) at a coating amount of 100 μm / wet to form a coating layer of the hot-melt resin composition. After coating, immediately use a laminator to press-bond the base fabric (fabric). Among them, the laminator is set with a roll temperature of 30 °C and a lamination gap of 70% of the total thickness of the base fabric, the coating layer, and the PET film. After bonding for 10 minutes, use a digital dynamometer (manufactured by Nidec-Shimpo Corporation) to measure the bonding strength, and evaluate the initial adhesiveness according to the following evaluation criteria. It should be noted that when the bonding strength after 10 minutes of bonding is less than 0.2 kg / 3 cm, during subsequent processing steps, re-peeling or distortion occurs between the base fabric and the resin layer formed by the hot-melt resin composition, and the risk of defects becomes high. Based on this view, a bonding strength of 0.2 kg / 3 cm or more after 10 minutes of bonding is regarded as qualified.

[0152] A: The bonding strength is 0.4 kg / 3 cm or more.

[0153] B: The bonding strength is 0.2 kg / 3 cm or more and less than 0.4 kg / 3 cm.

[0154] C: The bonding strength is less than 0.2 kg / 3 cm.

[0155] <Production of evaluation synthetic leather>

[0156] (1) Production of the surface layer

[0157] The surface layer in the synthetic artificial leather is prepared as described below. First, 100 parts by mass of a solution-type urethane resin (trade name “RESAMINE NE-8875-30M”, manufactured by Dainichi Seika Kogyo Co., Ltd.), 10 parts by mass of a colorant (trade name “SeikaSeven BS-780(S) Black”, manufactured by Dainichi Seika Kogyo Co., Ltd.), 25 parts by mass of methyl ethyl ketone (MEK) as a dilution solvent, and 25 parts by mass of dimethylformamide (DMF) are mixed to prepare a urethane resin composition for the surface layer. Next, the prepared urethane resin composition is uniformly coated onto a release paper at a coating amount of 250 μm / wet using a bar coater. Then, it is dried at 120 °C for 5 minutes to obtain a surface layer with a film thickness of 30 to 50 μm formed on the release paper.

[0158] (2) Fabrication of a standard synthetic artificial leather for flexibility evaluation

[0159] Using the surface layer and the adhesive obtained in the above “(1) Fabrication of the surface layer”, a standard synthetic artificial leather for flexibility evaluation is fabricated as described below. First, 100 parts by mass of a solution-type urethane resin (trade name “RESAMINE UD-8373BL”, manufactured by Dainichi Seika Kogyo Co., Ltd.), 12 parts by mass of an isocyanate-based crosslinking agent (trade name “RESAMINE NE”, manufactured by Dainichi Seika Kogyo Co., Ltd.), and 30 parts by mass of methyl ethyl ketone (MEK) and 30 parts by mass of dimethylformamide (DMF) as dilution solvents are mixed to prepare an adhesive. Next, the prepared adhesive is coated onto the surface layer on the release paper obtained in the above “(1) Fabrication of the surface layer” so as to form a dried film thickness of about 100 μm to form a coated layer of the adhesive. After removing the solvent in the coated layer of the adhesive by heating, a base fabric (woven fabric) is immediately crimped using a laminator, where the laminator is set such that the roll temperature is 40 °C and the lamination gap is 70% of the total thickness of the base fabric, the coated layer (adhesive layer), the surface layer, and the release paper. Then, it is cured at 50 °C for 48 hours to solidify the coated layer to form an adhesive layer, and then the release paper in contact with the surface layer is peeled off to obtain a standard synthetic artificial leather.

[0160] (3) Fabrication of the synthetic artificial leather for each example

[0161] Using the skin layer obtained in the above-mentioned “(1) Production of the skin layer” and the hot-melt resin composition of each example, the synthetic artificial leather of each example was produced as follows. First, the hot-melt resin composition was heated to 100 °C to melt it, and the molten hot-melt resin composition was coated on the skin layer on the release paper obtained in the above-mentioned “(1) Production of the skin layer” so as to form a dry film thickness of about 100 μm, thereby forming a coated layer of the hot-melt resin composition. After coating, a base fabric (woven fabric) was immediately crimped using a laminator, wherein the laminator was set such that the roll temperature was 30 °C and the lamination gap was 70% of the total thickness of the base fabric, the coated layer (hot-melt resin composition layer), the skin layer, and the release paper. Then, it was cured at 25 °C and 60% RH for 48 hours to form a cured product layer of the hot-melt resin composition, and then the release paper in contact with the skin layer was peeled off. In this way, a synthetic artificial leather was obtained in which the base fabric (woven fabric) as the base material layer was bonded to the skin layer via the cured product layer of the hot-melt resin composition as the adhesive layer.

[0162] (Cold resistance bending property)

[0163] For the synthetic artificial leather of each example, test pieces having a width of 50 mm and a length of 150 mm (evaluation range: 100 mm) were produced. Using the produced test pieces, a bending test was carried out at -10 °C in an environment with a stretching and bending range of 72 to 108% using a Demattia bending tester (model “No. 119-L DEMATTIA FLEXING TESTER”, manufactured by Yasuda Seiki Seisakusho Co., Ltd.). And the cold resistance bending property was evaluated according to the following evaluation criteria.

[0164] AA: No cracks after 60,000 times.

[0165] A: No cracks after 30,000 times and cracks before 60,000 times.

[0166] B: No cracks after 10,000 times and cracks before 30,000 times.

[0167] C: Cracks after 10,000 times.

[0168] (Hydrolysis resistance)

[0169] For each example of synthetic leather, the adhesion strength before the hydrolysis resistance test and the adhesion strength after the hydrolysis resistance test were measured, and the hydrolysis resistance was evaluated by comparing them. Specifically, a hot melt tape was pressed onto the upper surface of the skin layer of the synthetic leather with an iron at 140 °C for 1 minute and cooled at room temperature (20 °C) for 1 hour. Then, the base fabric in the synthetic leather and the skin layer in close contact with the hot melt tape were peeled off in the 180° direction at a peeling speed of 200 mm / min, and the strength was measured using a tensile test device (model "Autograph AGS-100A", manufactured by Shimadzu Corporation) as the adhesion strength.

[0170] On the other hand, after placing each example of synthetic leather in a constant temperature bath at 70 °C and 95% RH for a specified time, the adhesion strength after the hydrolysis resistance test was measured in the same manner as above. By comparing the adhesion strength before the test and the adhesion strength after the test, the hydrolysis resistance was evaluated according to the following evaluation criteria. It should be noted that the retention rate of the adhesion strength refers to the ratio of the adhesion strength after being stored in the bath for a specified time to the adhesion strength before being placed in the bath.

[0171] AA: The retention rate of the adhesion strength after 8 weeks of storage is 70% or more.

[0172] A: The retention rate of the adhesion strength after 5 weeks of storage is 70% or more.

[0173] B: The retention rate of the adhesion strength after 5 weeks of storage is 50% or more and less than 70%.

[0174] C: The retention rate of the adhesion strength after 5 weeks of storage is less than 50%.

[0175] (Flexibility)

[0176] Each synthetic leather was compared with the standard synthetic leather obtained in the above "(2) Production of standard synthetic leather for flexibility evaluation" by the feeling of touching by hand, and the flexibility was evaluated according to the following evaluation criteria based on the standard synthetic leather.

[0177] AA: Significantly softer than the standard synthetic leather.

[0178] A: Softer than the standard synthetic leather.

[0179] B: As flexible as the standard synthetic leather.

[0180] C: Significantly harder than the standard synthetic leather.

[0181] (Abrasion resistance)

[0182] The hot-melt resin composition of each example was heated to 100 °C to be melted, and the melted hot-melt resin composition was coated on a release paper so as to form a dry film thickness of about 100 μm, thereby forming a coating layer of the hot-melt resin composition. After the coating, the base fabric (woven fabric) was immediately crimped using a laminator, wherein the laminator was set such that the roller temperature was 30 °C and the lamination gap was 70% of the total thickness of the base fabric, the coating layer (hot-melt resin composition layer) and the release paper. Then, it was cured at 25 °C and 60% RH for 48 hours to form a cured product layer of the hot-melt resin composition, and then the release paper in contact with the cured product layer was peeled off. In this way, a synthetic artificial leather having a base fabric (woven fabric) and an epidermal layer formed of a cured product layer of a hot-melt resin composition provided on the base fabric was produced as a laminate having a two-layer structure. This was used as the synthetic artificial leather for the abrasion resistance test described below.

[0183] For the synthetic artificial leather for the abrasion resistance test of each example, a circular test piece having a diameter of 11.5 cm was produced. Using this test piece and a Taber abrasion tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), an abrasion resistance test was carried out under the conditions of a load of 500 g, a rotational speed of 60 ± 2 rpm, and an abrasive wheel CS-10. And, according to the following evaluation criteria, the abrasion resistance was evaluated.

[0184] AA: There was no appearance change such as scratches after 1500 times.

[0185] A: There was no appearance change such as scratches after 1000 times, and there was an appearance change such as scratches before 1500 times.

[0186] B: There was no appearance change such as scratches after 500 times, and there was an appearance change such as scratches before 1000 times.

[0187] C: There was an appearance change such as scratches in less than 500 times

[0188] <Heat resistance (heat creep test)>

[0189] As a creep test, a test of applying a certain load to a test piece for a long time at a high temperature state and measuring the deformation amount and the time until fracture was carried out. Specifically, 1) to 8) were carried out as follows.

[0190] 1) The hot-melt resin composition and the coating rod of each example to be tested were put into an oven at 100 °C for preheating.

[0191] 2) The hot-melt resin composition was coated on the polyurethane (PU) resin layer of the wet film-forming fabric (A) with a 200 μGap (thickness 200 μm), and immediately adhered to the PU resin layer of the wet film-forming fabric (B).

[0192] Note that as the wet film-forming fabrics (A) and (B), the following synthetic leather is used. A polyurethane resin solution (trade name "RESAMINE CU-4340NS" (resin solid content: 30% by mass, manufactured by Dainichi Seika Kogyo Co., Ltd.)) in DMF is coated on a nonwoven fabric used as a substrate and diluted with DMF to a solution with a solid content of 15% by mass, and then solidified and DMF is removed in a water bath and dried to form a PU resin layer, and a porous layer with a dried thickness of 800 to 1000 μm is formed on the substrate.

[0193] 3) After curing the above-mentioned hot-melt resin composition at 25°C / 60% RH for 24 hours, the heat resistance is measured according to the following steps.

[0194] 4) Set the oven to 170°C. In addition, cut the bonded product into a width of 3 cm and a length of 12 cm or more to obtain test pieces.

[0195] 5) Peel off the ends of the test pieces at the bonded surface, install clamps on the wet film-forming fabric (A) side and the wet film-forming fabric (B) side respectively and fix them, and hang a 3-kg weight on one side.

[0196] 6) Hang the test specimens in the oven at 170°C and quickly close the oven door.

[0197] 7) Leave it for 5 minutes after closing the door.

[0198] 8) Immediately take out the test pieces after 5 minutes, observe the peeling length and peeling state at 170°C / left for 5 minutes, and evaluate the heat resistance according to the following evaluation criteria.

[0199] A: The peeling length is less than 2 cm and the peeling state is substrate fracture.

[0200] B: The peeling length is 2 cm or more and less than 5 cm, and the peeling state is substrate fracture.

[0201] C: The peeling length is 5 cm or more or the peeling state is peeling of the PU resin surface.

[0202] Table 2-1

[0203]

[0204] Table 2-2

[0205]

[0206] Table 2-3

[0207]

[0208] Table 2-4

[0209]

[0210] Table 2-5

[0211]

[0212] Table 2-6

[0213]

[0214] Description of Reference Numerals

[0215] 10 Evaluation film

[0216] 12 clamps

[0217] 14 weights

[0218] 16 samples

[0219] 20 Gear Oven

[0220] 22 rotating disk

Claims

1. A moisture-curable urethane hot-melt resin composition containing a reaction product of a polyol component and a polyisocyanate component, namely a urethane prepolymer having an isocyanate group. The polyol component includes a high-molecular polyol component and a low-molecular polyol component. The high-molecular polyol component includes: At least one polyol (A) selected from the group consisting of a polyester polyol (A1) having a structural unit derived from sebacic acid, a polyester polyol (A2) having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and having a number-average molecular weight of 8,000 or more, and a polyester polyol (A3) having a structural unit derived from 1,6-hexanediol and a structural unit derived from adipic acid and having a number-average molecular weight of 6,000 or more; and A polyol (B). The polyol (B) is a polyether polyol (B2), or a combination of a polyester polyol (B1) other than the polyol (A) and a polyether polyol (B2). The low-molecular polyol component includes a trifunctional polyol (D) having a molecular weight of 300 or less and having 3 hydroxyl groups in one molecule. The ratio of the polyol (A) to the trifunctional polyol (D) satisfies trifunctional polyol (D) / polyol (A) = 0.14 to 55 mmol / g, where, The unit of the trifunctional polyol (D) is mmol, and the unit of the polyol (A) is g.

2. The moisture-curing urethane hot-melt resin composition according to claim 1, wherein, The polyol (B) contains a polyol (B) using a plant-derived raw material b ).

3. The moisture-curable urethane hot-melt resin composition according to claim 1, wherein, The high-molecular polyol component further includes a polycarbonate polyol (C).

4. The moisture-curing urethane hot-melt resin composition according to claim 3, wherein, The polycarbonate polyol (C) includes a polycarbonate polyol (C b ) prepared using plant-derived raw materials.

5. The moisture-curable urethane hot-melt resin composition according to claim 3, wherein, The total amount of the polyol (B) and the polycarbonate polyol (C) is more than the amount of the polyol (A). The proportion of the total of the polyol (A), the polyol (B), and the polycarbonate polyol (C) relative to the total amount of the polyol component is 90% by mass or more.

6. A laminate having: A substrate, and A cured product layer of the moisture-curable urethane hot-melt resin composition according to any one of claims 1 to 5 provided on the substrate.

7. A synthetic leather having a substrate layer, an epidermis layer, and an adhesive layer provided between them and bonding them, The adhesive layer is a cured product layer of the moisture-curable urethane hot-melt resin composition according to any one of claims 1 to 5.

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