Moisture-curable polyurethane hot-melt resin composition, adhesive, and synthetic leather

Abstract

The present invention provides a moisture-curable hot-melt polyurethane resin composition characterized by containing a hot-melt urethane prepolymer (A) having an isocyanate group and a flame retardant (B), the hot-melt prepolymer (A) comprising a polyol (a) containing 50% by mass or more of a polyether polyol (a1) as a starting material, and the amount of the flame retardant (B) being 100 parts by mass per 100 parts by mass of the hot-melt urethane prepolymer (A). The content of the flame retardant (B) is more than 15 parts by mass. The present invention also provides an adhesive agent characterized by containing the moisture-curable hot-melt polyurethane resin composition as described above. The flame retardant (B) is preferably a phosphoric acid ester having three or more aromatic rings.

Description

Technical Field

[0001] The present invention relates to a moisture-curable polyurethane hot-melt resin composition, an adhesive and synthetic leather. Background Art

[0002] In synthetic leather, polyurethane (PU), polyvinyl chloride (PVC), olefin-based thermoplastic elastomer (TPO), etc. are used as surface materials, and materials obtained by bonding these surface materials to base fabrics such as cloth and non-woven fabrics with adhesives are generally used (for example, see Patent Document 1). Among them, solvent-based adhesives have been widely used and generally used so far, but as a measure for the environment, regions, countries, and companies require the reduction of VOCs, and there is a need to replace solvent-based adhesives with water-based and solvent-free adhesives.

[0003] On the other hand, synthetic leather used in vehicle interior materials and interior furniture requires flame retardancy from the viewpoint of fire prevention, but also requires high flexibility at low temperatures when used in cold regions. However, no material having all these properties has been found.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2008-514403 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The problem to be solved by the present invention is to provide a moisture-curable polyurethane hot-melt resin composition having excellent adhesiveness, low-temperature flexibility and flame retardancy.

[0009] Means for solving problems

[0010] The present invention provides the following moisture-curable polyurethane hot-melt resin composition, characterized in that it contains a hot-melt urethane prepolymer (A) having an isocyanate group and a flame retardant (B), wherein the hot-melt prepolymer (A) uses a polyol (a) containing 50% by mass or more of a polyether polyol (a1) as a raw material, and the content of the flame retardant (B) exceeds 15 parts by mass relative to 100 parts by mass of the hot-melt urethane prepolymer (A).

[0011] The present invention also provides the following adhesive, characterized in that it contains the above-mentioned moisture-curable polyurethane hot-melt resin composition. The present invention also provides the following synthetic leather, characterized in that it has at least a thermoplastic resin layer and the above-mentioned adhesive layer.

[0012] Effects of the Invention

[0013] The moisture-curable polyurethane hot-melt resin composition of the present invention has excellent adhesiveness, low-temperature bendability and flame retardancy. Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be particularly suitably used in the production of synthetic leather using a thermoplastic resin as a surface material. DETAILED DESCRIPTION

[0014] The moisture-curable polyurethane hot-melt resin composition of the present invention contains a hot-melt urethane prepolymer (A) having an isocyanate group made from a specific polyol (a) and a specific amount of a flame retardant (B).

[0015] In order to obtain excellent low-temperature bendability, the hot-melt urethane prepolymer (A) having an isocyanate group must be made of a polyol (a) containing 50% by mass or more of a polyether polyol (a1) as a raw material. By designing in this way, the glass transition temperature of the adhesive can be lowered, thereby obtaining excellent low-temperature bendability. The amount of the polyether polyol (a1) used is preferably 50 to 90% by mass, and more preferably 55 to 70% by mass in the polyol (a), in order to obtain better low-temperature bendability.

[0016] As the above-mentioned polyether polyol (a1), for example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, polyoxypropylene polyoxytetramethylene glycol, etc. can be used. These polyols can be used alone or in combination of two or more. Among these, polypropylene glycol and / or polytetramethylene glycol are preferred from the aspect of obtaining more excellent low-temperature flexibility, and polytetramethylene glycol is more preferred from the aspect of obtaining further excellent heat resistance and wet heat resistance. It should be noted that as the above-mentioned polyether polyol, polyether polyols derived from plants can be used. As the above-mentioned polyether polyol derived from plants, for example, "Bio PTMG" manufactured by Mitsubishi Chemical Co., Ltd., "Bio PTG" manufactured by Hodogaya Chemical Co., Ltd., and biomass polypropylene glycol manufactured by VithalCastor Polyols can be obtained in the form of commercial products.

[0017] As the above-mentioned polyol (a), in addition to the above-mentioned polyether polyol (a), other polyols may also be used in combination. As the above-mentioned other polyols, for example, commercially available polyols such as polyester polyols, polycarbonate polyols, polybutadiene polyols, silicon diols, and acrylic diols may be used. These polyols may be used alone or in combination of two or more, and may be derived from petroleum or plants. With respect to the above-mentioned other polyols, polyester polyols are preferred from the aspect of obtaining more excellent adhesion.

[0018] The number average molecular weight of the polyol (a) is preferably 500 to 10,000, more preferably 1,000 to 6,000, from the viewpoint of obtaining more excellent adhesion, low-temperature flexibility, and mechanical strength. The number average molecular weight of the polyol (a) is a value measured by gel permeation chromatography (GPC).

[0019] As the hot-melt urethane prepolymer (A) having an isocyanate group, for example, a reaction product of the polyol (a) and the polyisocyanate (b) can be used.

[0020] As the above-mentioned polyisocyanate (b), for example, aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, and naphthalene diisocyanate can be used; aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate can be used. These polyisocyanates can be used alone or in combination of two or more, and can be derived from petroleum or plants. Among these, aromatic polyisocyanates are preferred, and diphenylmethane diisocyanate is more preferred, from the perspective of obtaining better reactivity and adhesion.

[0021] The hot-melt urethane prepolymer (A) has isocyanate groups at the polymer terminals and in the molecule. The isocyanate groups can react with moisture in the air, the substrate coated with the urethane prepolymer, or the adherend to form a crosslinked structure.

[0022] The hot-melt urethane prepolymer (A) can be produced, for example, by adding the polyol (a) dropwise to a reaction vessel containing the polyisocyanate (b), followed by heating, and reacting under conditions in which the isocyanate group of the polyisocyanate (b) is in excess relative to the hydroxyl group of the polyol (a).

[0023] The molar ratio [NCO / OH] of the hydroxyl group of the polyol (a) to the isocyanate group of the polyisocyanate (b) when the polyol (a) and the polyisocyanate (b) are reacted is preferably 1.3 to 2.5, more preferably 1.5 to 2.0, from the viewpoint of obtaining better hot melt properties, adhesiveness and low temperature flexibility.

[0024] The isocyanate group content (hereinafter referred to as "NCO%") of the hot-melt urethane prepolymer (A) is preferably 1.2 to 5.0% by mass, and more preferably 1.7 to 3.5% by mass, from the viewpoint of obtaining more excellent hot melt properties, adhesiveness, and low-temperature flexural properties. It should be noted that the NCO% of the hot-melt urethane prepolymer (A) is a value measured by potentiometric titration in accordance with JIS K1603-1:2007.

[0025] The flame retardant (B) is an essential component in order to obtain excellent flame retardancy, and its content must exceed 15 parts by mass relative to 100 parts by mass of the hot-melt urethane prepolymer (A). The content of the flame retardant (B) is preferably 17.5 to 55 parts by mass relative to 100 parts by mass of the hot-melt urethane prepolymer (A) in order to maintain low-temperature flexibility and adhesiveness at a high level and obtain more excellent flame retardancy.

[0026] As the flame retardant (B), for example, phosphate esters, phosphate-containing flame retardants, red phosphorus, bromine-containing flame retardants, boron-containing flame retardants, antimony-containing flame retardants, metal hydroxides, graphite, phosphorus-boron compounds, vinyl polymers, etc. can be used. These flame retardants can be used alone or in combination of two or more. Among these, phosphate esters having three or more aromatic rings are preferred, and phosphate esters having four or more aromatic rings are more preferred, from the perspective of maintaining low-temperature flexibility and adhesion at a high level and obtaining more excellent flame retardancy.

[0027] The moisture-curable polyurethane hot-melt resin composition of the present invention contains the hot-melt urethane prepolymer (A) and the flame retardant (B) as essential components, but may contain other additives as necessary.

[0028] As above-mentioned other additives, for example, urethanization catalyst, neutralizing agent, crosslinking agent, silane coupling agent, thickener, filler, thixotropy imparting agent, tackifier, wax, heat stabilizer, light stabilizer, fluorescent whitening agent, foaming agent, pigment, dye, conductivity imparting agent, antistatic agent, moisture permeability improving agent, water repellent, oil repellent, hollow foam, water absorbent, moisture absorbent, deodorant, foam regulating agent, plasticizer, anti-blocking agent, hydrolysis preventing agent etc. can be used.These additives can be used alone, and two or more can be used in combination.

[0029] As described above, the moisture-curable polyurethane hot-melt resin composition of the present invention has excellent adhesiveness, low-temperature bendability and flame retardancy. Therefore, the moisture-curable polyurethane hot-melt resin composition of the present invention can be particularly suitably used in the production of synthetic leather using a thermoplastic resin as a surface material.

[0030] Next, the synthetic leather of the present invention will be described.

[0031] The synthetic leather comprises at least a thermoplastic resin layer and an adhesive layer containing the moisture-curable polyurethane hot-melt resin composition, and examples thereof include synthetic leathers in which a substrate, the adhesive layer and the thermoplastic resin layer are sequentially laminated.

[0032] As the above-mentioned substrate, for example, non-woven fabrics, woven fabrics, knitted fabrics, etc. formed by polyester fibers, polyethylene fibers, nylon fibers, acrylic fibers, polyurethane fibers, acetate fibers, rayon fibers, polylactic acid fibers, cotton, linen, silk, wool, glass fibers, carbon fibers, and blended fibers thereof can be used.

[0033] As the thermoplastic resin layer, for example, a resin layer formed of known polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, polystyrene, TPO (Thermoplastic Olefinic Elastomer), thermoplastic ester elastomer, thermoplastic polyurethane, etc. can be used. In the present invention, even when polyvinyl chloride, TPO, thermoplastic ester elastomer, or thermoplastic polyurethane is used as the thermoplastic resin, it has excellent adhesion and low-temperature flexural properties, especially for polyvinyl chloride that is difficult to adhere, whether it is a foamed body or an unfoamed body, it has excellent adhesion and low-temperature flexural properties.

[0034] The above-mentioned adhesive layer is formed by the moisture-curable polyurethane hot-melt resin composition of the present invention. As a method for forming the adhesive layer, for example, the following method can be cited: after the above-mentioned moisture-curable polyurethane hot-melt resin composition is melted at 100-140°C, it is applied to the above-mentioned thermoplastic resin layer or the above-mentioned substrate using a coating machine method such as a roller coater, a spray coater, a T-die coater, a knife coater, a comma coater, a dispenser, inkjet printing, screen printing, offset printing, etc. precision methods; nozzle coating, etc., and then laminated.

[0035] After the two layers are bonded together using the adhesive, the adhesive may be dried and cured by a known method as needed.

[0036] The synthetic leather may be provided with a surface treatment layer on the basis of the thermoplastic resin layer. For example, a surface treatment layer formed of a known solvent-based urethane resin, water-based urethane resin, solvent-based acrylic resin, water-based acrylic resin, etc. may be used as the surface treatment layer.

[0037] Example

[0038] Hereinafter, the present invention will be described in more detail using examples.

[0039] [Example 1]

[0040] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 171 parts by mass of polytetramethylene glycol (number average molecular weight: 2,000, hereinafter referred to as "PEt-1"), 78 parts by mass of polyester polyol (a substance obtained by reacting 1,6-hexanediol with phthalic acid, number average molecular weight: 2,000, hereinafter referred to as "PEs-1"), and 62 parts by mass of polyester polyol (a substance obtained by reacting 1,6-hexanediol with sebacic acid, number average molecular weight: 3,500, hereinafter referred to as "PEs-2") were added and mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became 0.05% by mass or less. Next, the flask was cooled to 90°C, 71 parts by weight of 4,4'-diphenylmethane diisocyanate (hereinafter referred to 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 reached a constant, thereby obtaining a hot-melt urethane prepolymer. 35 parts by weight of phosphate (1,3-phenylenebis(2,6-dimethylphenyl=phosphate), hereinafter referred to as "flame retardant (B1)") was added to 100 parts by weight of the hot-melt urethane prepolymer to obtain a moisture-curable polyurethane hot-melt resin composition (1).

[0041] [Example 2]

[0042] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 74 parts by mass of PEt-1, 31 parts by mass of PEs-1 and 18 parts by mass of PEs-2 were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became less than 0.05% by mass. 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 under a nitrogen atmosphere for about 3 hours until the isocyanate group content reached a constant, thereby obtaining a hot-melt urethane prepolymer. With respect to 100 parts by mass of the hot-melt urethane prepolymer, 25 parts by mass of a flame retardant (B1) were added to obtain a moisture-curable polyurethane hot-melt resin composition (2).

[0043] [Example 3]

[0044] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 48 parts by mass of polypropylene glycol (number average molecular weight: 2,000, hereinafter referred to as "PEt-2"), 17 parts by mass of PEs-1, and 22 parts by mass of polyester polyol (a substance obtained by reacting ethylene glycol, neopentyl glycol, 1,6-hexanediol and adipic acid, number average molecular weight: 5,500, hereinafter referred to as "PEs-3") were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became 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 in a nitrogen atmosphere until the isocyanate group content became constant, thereby obtaining a hot-melt urethane prepolymer. 35 parts by mass of the flame retardant (B1) was added to 100 parts by mass of the hot-melt urethane prepolymer to obtain a moisture-curable polyurethane hot-melt resin composition (3).

[0045] [Example 4]

[0046] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 133 parts by mass of PEt-1, 56 parts by mass of PEs-1 and 33 parts by mass of PEs-2 were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became less than 0.05% by mass. Next, the flask was cooled to 90°C, 49 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C under a nitrogen atmosphere for about 3 hours until the isocyanate group content reached a constant, thereby obtaining a hot-melt urethane prepolymer. With respect to 100 parts by mass of the hot-melt urethane prepolymer, 30 parts by mass of a flame retardant (B1) was added to obtain a moisture-curable polyurethane hot-melt resin composition (4).

[0047] [Example 5]

[0048] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 139 parts by mass of PEt-2, 32 parts by mass of PEs-1 and 43 parts by mass of PEs-3 were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became less than 0.05% by mass. Next, the flask was cooled to 90°C, 47 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C under a nitrogen atmosphere for about 3 hours until the isocyanate group content reached a constant, thereby obtaining a hot-melt urethane prepolymer. With respect to 100 parts by mass of the hot-melt urethane prepolymer, 35 parts by mass of a flame retardant (B1) were added to obtain a moisture-curable polyurethane hot-melt resin composition (5).

[0049] [Example 6]

[0050] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 83 parts by mass of PEt-1, 19 parts by mass of PEs-1 and 26 parts by mass of PEs-3 were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became less than 0.05% by mass. Next, the flask was cooled to 90°C, 26 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C under a nitrogen atmosphere for about 3 hours until the isocyanate group content reached a constant, thereby obtaining a hot-melt urethane prepolymer. With respect to 100 parts by mass of the hot-melt urethane prepolymer, 40 parts by mass of a flame retardant (B1) was added to obtain a moisture-curable polyurethane hot-melt resin composition (6).

[0051] [Example 7]

[0052] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 121 parts by mass of PEt-1, 121 parts by mass of PEt-2, 81 parts by mass of PEs-1 and 81 parts by mass of PEs-2 were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became 0.05% by mass or less. Next, the flask was cooled to 90°C, 87 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C under a nitrogen atmosphere for about 3 hours until the isocyanate group content became constant, thereby obtaining a hot-melt urethane prepolymer. With respect to 100 parts by mass of the hot-melt urethane prepolymer, 30 parts by mass of a flame retardant (B1) was added to obtain a moisture-curable polyurethane hot-melt resin composition (7).

[0053] [Example 8]

[0054] A moisture-curable polyurethane hot-melt resin composition (8) was obtained in the same manner as in Example 1 except that the type of PEt-1 was changed to biomass polytetramethylene glycol (“Bio PTMG” manufactured by Mitsubishi Chemical Co., Ltd., number average molecular weight: 2,000).

[0055] [Comparative Example 1]

[0056] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 92 parts by mass of PEt-1, 33 parts by mass of PEs-1 and 25 parts by mass of PEs-2 were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became less than 0.05% by mass. 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 under a nitrogen atmosphere for about 3 hours until the isocyanate group content reached a constant, thereby obtaining a hot-melt urethane prepolymer. With respect to 100 parts by mass of the hot-melt urethane prepolymer, 10 parts by mass of a flame retardant (B1) was added to obtain a moisture-curable polyurethane hot-melt resin composition (R1).

[0057] [Comparative Example 2]

[0058] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 109 parts by mass of PEt-2, 45 parts by mass of PEs-1 and 27 parts by mass of PEs-2 were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became 0.05% by mass or less. Next, the flask was cooled to 90°C, 40 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C under a nitrogen atmosphere for about 3 hours until the isocyanate group content became constant, thereby obtaining a hot-melt urethane prepolymer, and a moisture-curable polyurethane hot-melt resin composition (R2) was obtained.

[0059] [Comparative Example 3]

[0060] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 111 parts by mass of PEt-1, 77 parts by mass of PEs-1 and 66 parts by mass of PEs-3 were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became less than 0.05% by mass. Next, the flask was cooled to 90°C, 50 parts by mass of MDI melted at 70°C was added, and the mixture was reacted at 110°C under a nitrogen atmosphere for about 3 hours until the isocyanate group content reached a constant, thereby obtaining a hot-melt urethane prepolymer. With respect to 100 parts by mass of the hot-melt urethane prepolymer, 65 parts by mass of a flame retardant (B1) were added to obtain a moisture-curable polyurethane hot-melt resin composition (R3).

[0061] [Comparative Example 4]

[0062] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 27 parts by mass of PEt-1, 41 parts by mass of PEs-1 and 23 parts by mass of PEs-3 were added, mixed, and heated under reduced pressure at 100°C to dehydrate until the water content in the flask became less than 0.05% by mass. 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 under a nitrogen atmosphere for about 3 hours until the isocyanate group content reached a constant, thereby obtaining a hot-melt urethane prepolymer. With respect to 100 parts by mass of the hot-melt urethane prepolymer, 40 parts by mass of a flame retardant (B1) were added to obtain a moisture-curable polyurethane hot-melt resin composition (R4).

[0063] [Method for determining number average molecular weight and weight average molecular weight]

[0064] The number average molecular weight of the polyol used in Examples and Comparative Examples refers to a value measured by gel permeation column chromatography (GPC) under the following conditions.

[0065] Measuring device: High-speed GPC device (Tosoh Corporation "HLC-8220GPC")

[0066] Column: The following columns manufactured by Tosoh Corporation were connected in series and used.

[0067] "TSKgel G5000" (7.8mm I.D. × 30cm) × 1 piece

[0068] "TSKgel G4000" (7.8mm I.D. × 30cm) × 1 piece

[0069] "TSKgel G3000" (7.8mm I.D. × 30cm) × 1 piece

[0070] "TSKgel G2000" (7.8mm I.D. × 30cm) × 1 piece

[0071] Detector: RI (differential refractometer)

[0072] Column temperature: 40°C

[0073] Eluent: Tetrahydrofuran (THF)

[0074] Flow rate: 1.0mL / min

[0075] Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4 mass %)

[0076] Standard samples: The following standard polystyrene was used to prepare a calibration curve.

[0077] (Standard Polystyrene)

[0078] "TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation

[0079] "TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation

[0080] "TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation

[0081] "TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation

[0082] "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation

[0083] "TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation

[0084] "TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation

[0085] "TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation

[0086] "TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation

[0087] "TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation

[0088] "TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation

[0089] "TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation

[0090] "TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation

[0091] "TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

[0092] [How synthetic leather is made]

[0093] In a constant temperature and humidity chamber adjusted to 23°C and 50±5%, a gravure coater was used to coat a polyvinyl chloride sheet at a temperature of 40±5 g / m 2 The moisture-curable polyurethane hot-melt resin composition obtained in the examples and comparative examples was intermittently coated in a manner and laminated with a polyester fabric, and the resultant was cured for 24 hours at a temperature of 23° C. and a humidity of 50±5%, thereby obtaining a synthetic leather.

[0094] [Evaluation method of adhesiveness]

[0095] The peel strength of each synthetic leather obtained was measured using Tensilon (Tensilon universal testing machine “RTC-1210A” manufactured by ORIENTEC Corporation) at a crosshead measurement speed of 200 mm / min. 6 N / cm or more was evaluated as “○”, and less than 6 N / cm was evaluated as “×”.

[0096] [Evaluation method of low temperature flexural properties]

[0097] Each of the obtained synthetic leathers was subjected to a bending test using a deflectometer (-10°C, 100 times / minute) to measure the number of times until cracks occurred on the surface of the synthetic leather. 20,000 times or more was evaluated as "○", and less than 20,000 times was evaluated as "×".

[0098] [Evaluation method of flame retardancy]

[0099] The moisture-curable polyurethane hot-melt resin composition obtained in the examples and comparative examples was applied with a roll coater to a thickness of 300 microns, and then cured for more than 72 hours under the conditions of a temperature of 23°C and a humidity of 50±5% to produce a film. Next, the obtained film was cut into a rectangle with a width of 102 mm and a length of 356 mm, and a flammability test (FMVSS302) was performed. The test pieces that did not catch fire or extinguished themselves before reaching the A mark, the test pieces that extinguished themselves within a combustion distance of 51 mm (and within 60 seconds), and the test pieces with a combustion rate of 102 mm / minute or less were evaluated as "○", and the test pieces other than these were evaluated as "×".

[0100] [Table 1]

[0101]

[0102] [Table 2]

[0103]

[0104] [Table 3]

[0105]

[0106] It is found that Examples 1 to 8, which are moisture-curable polyurethane hot-melt resin compositions of the present invention, are excellent in adhesiveness, low-temperature bendability, and flame retardancy.

[0107] On the other hand, in Comparative Example 1, the content of the flame retardant (B) is below the range specified in the present invention, and the flame retardancy is poor.

[0108] Comparative Example 2 is a method in which the flame retardant (B) is not used, and the flame retardancy is poor.

[0109] Comparative Examples 3 and 4 are embodiments in which the amount of the polyether polyol (a1) used is below the range specified in the present invention, and thus low-temperature flexural properties and the like are poor.

Claims

1. A moisture-curable polyurethane hot-melt resin composition, characterized in that: Contains a hot-melt urethane prepolymer (A) having an isocyanate group and a flame retardant (B), The hot melt prepolymer (A) is made of a polyol (a) containing 50% by mass or more of a polyether polyol (a1). The content of the flame retardant (B) exceeds 15 parts by mass based on 100 parts by mass of the hot-melt urethane prepolymer (A).

2. The moisture-curable polyurethane hot-melt resin composition according to claim 1, wherein The flame retardant (B) is a phosphate ester having three or more aromatic rings.

3. An adhesive, characterized in that: A moisture-curable polyurethane hot-melt resin composition according to claim 1.

4. A synthetic leather, characterized in that: The adhesive layer according to claim 3 comprises at least a thermoplastic resin layer.

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