Method for producing polyurethane foam sheet and method for producing synthetic leather

Abstract

The present invention provides a moisture-curable hot-melt polyurethane resin composition characterized by containing a urethane prepolymer (i) having an isocyanate group, which is a reaction product of a polyol (A) and a polyisocyanate (B), the polyol (A) contains a biomass-derived polytetramethylene glycol or polycarbonate polyol (a1), a polyol (a2) having an aromatic ring, and a polyester polyol (a3) that is solid at room temperature other than (a2). Furthermore, the present invention provides a method for producing a synthetic leather having at least a base material, an adhesive layer, and a skin layer, and is characterized in that the adhesive layer is obtained by the method for producing the polyurethane foam sheet.

Description

Technical Field

[0001] The present invention provides a method for producing a polyurethane foam sheet and a method for producing synthetic leather. Background Art

[0002] As the use restrictions of dimethylformamide (DMF) in Europe are being formalized, there is an urgent need to supply solvent-free, energy-saving, and environmentally friendly resins. Among them, solvent-free moisture-curable hot-melt urethane compositions have attracted attention and are widely used in the manufacture of building materials, automotive interior materials, refrigerators, smartphones, personal computers, navigation devices and other electrical and electronic equipment. In recent years, there has been an increase in the number of cases where moisture-curable polyurethane hot-melt compositions are foamed and made into foamed solids for the purpose of improving the impact resistance or feel brought about by the cushioning effect and reducing the amount of moisture-curable hot-melt urethane compositions used.

[0003] As a method for foaming and curing the moisture-curable hot-melt urethane composition, a water foaming method using water or water vapor has been widely studied (see, for example, Patent Documents 1 and 2). However, a foam sheet having a better feel is desired.

[0004] On the other hand, as the recent marine plastic problem has attracted attention, bio-based resins that aim to get rid of fossil resources are gaining attention, and moisture-curable polyurethane resin compositions are no exception. However, it is pointed out that the texture and other properties will decrease if the biomass content is increased, and it is a big issue to balance these properties.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2004-115705

[0008] Patent Document 2: Japanese Patent Application Publication No. 2003-306526 Summary of the invention

[0009] Problems to be solved by the invention

[0010] The problem to be solved by the present invention is to provide a method for producing a polyurethane foam sheet having an increased biomass ratio using a biomass raw material, excellent foam retention, and good texture.

[0011] Means for solving problems

[0012] The present invention provides the following method for producing a polyurethane foam sheet, characterized in that a moisture-curable polyurethane hot-melt resin composition (X) containing a urethane prepolymer (i) which is a reaction product of a polyol (A) and a polyisocyanate (B) is mixed with a polyol composition (Y) to obtain a mixture, the mixture is applied on a substrate in a sheet form, and water vapor is brought into contact with the sheet-like mixture to water-foam the mixture, wherein the polyol (A) contains polytetramethylene glycol or polycarbonate polyol (a1) derived from biomass, a polyol (a2) having an aromatic ring, and a polyester polyol (a3) ​​other than the polyol (a2) which is solid at room temperature, and the polyol composition (Y) contains an amine catalyst (y1) having a foaming constant (Kw) of 10 or more.

[0013] The present invention also provides a method for producing synthetic leather, characterized in that the method is a method for producing synthetic leather having at least a substrate, an adhesive layer and a surface layer, wherein the adhesive layer is obtained by the method for producing a polyurethane foam sheet.

[0014] Effects of the Invention

[0015] According to the method for manufacturing a polyurethane foam sheet of the present invention, a polyurethane foam sheet having excellent foam retention and good hand feel can be obtained. The polyurethane foam sheet of the present invention uses biomass raw materials to have a high biomass degree, and is an environmentally friendly sheet. In addition, the polyurethane foam sheet also has excellent adhesiveness, and can therefore be particularly suitable for use as an adhesive layer for synthetic leather. DETAILED DESCRIPTION

[0016] The polyurethane foam sheet of the present invention is produced by mixing a moisture-curable polyurethane hot-melt resin composition (X) containing a urethane prepolymer (i) which is a reaction product of a polyol (A) and a polyisocyanate (B) with a polyol composition (Y) to obtain a mixture, applying the mixture in a sheet form on a substrate, and bringing water vapor into contact with the sheet-like mixture to water-foam the mixture, wherein specific substances are used as the polyol (A) and the polyol composition (Y).

[0017] The urethane prepolymer (i) may be a reaction product of a specific polyol (A) and a polyisocyanate (B).

[0018] The polyol (A) contains, as essential components, polytetramethylene glycol or polycarbonate polyol (a1) derived from biomass, a polyol (a2) having an aromatic ring, and a polyester polyol (a3) ​​other than (a2) that is solid at room temperature in order to increase the biomass content of the resin and obtain excellent bubble retention, hand feel and adhesiveness.

[0019] Biomass-derived polytetramethylene glycol or polycarbonate polyol (a1) is an essential component in terms of increasing the biomass content of the resin and achieving excellent basic physical properties of the adhesive film, such as mechanical strength.

[0020] The biomass-derived polytetramethylene glycol is commercially available, for example, as "Bio PTMG" manufactured by Mitsubishi Chemical Co., Ltd.

[0021] As the above-mentioned biomass-derived polycarbonate polyol, polycarbonate polyols preferably made of diols having 1 to 10 carbon atoms, more preferably 3 to 10 carbon atoms, derived from biomass can be used as raw materials, and for example, "Benebiol NL-2010DB" manufactured by Mitsubishi Chemical Corporation, "Benebiol NL-3010DB" manufactured by Mitsubishi Chemical Corporation, "Benebiol NL-2000D" manufactured by Mitsubishi Chemical Corporation, "PCDX222" manufactured by Asahi Kasei Corporation, etc. can be obtained as commercial products. These polycarbonate polyols can be used alone or in combination of two or more.

[0022] The number average molecular weight of the biomass-derived polytetramethylene glycol or polycarbonate polyol (a1) is preferably 500 to 100,000, and more preferably 700 to 50,000. The number average molecular weight of the biomass-derived polytetramethylene glycol or polycarbonate polyol (a1) is a value measured by gel permeation chromatography (GPC).

[0023] The amount of the biomass-derived polytetramethylene glycol or polycarbonate polyol (a1) used is preferably 50 to 90% by mass, more preferably 60 to 80% by mass, in the polyol (A).

[0024] The polyol (a2) having an aromatic ring can provide excellent film flexibility, texture and adhesiveness, and for example, polyether polyol having an aromatic ring, polyester polyol having an aromatic ring, etc. can be used.

[0025] As the polyether polyol having an aromatic ring, for example, bisphenol A, bisphenol F and alkylene oxide adducts thereof can be used. These polyols can be used alone or in combination of two or more. Among these, polyether polyols that are alkylene oxide adducts of bisphenol A are preferred. As the alkylene oxide, an alkylene oxide having 2 to 8 carbon atoms is preferred, and the number of moles of the alkylene oxide added is preferably 2 to 10 moles, and more preferably 4 to 8 moles.

[0026] As the polyester polyol having an aromatic ring, for example, a reaction product of the following hydroxyl group-containing compound and polybasic acid can be used.

[0027] As the compound having a hydroxyl group, for example, ethylene glycol, propylene glycol, 1,4-butanediol, pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, neopentyl glycol, hexamethylene glycol, glycerol, trimethylolpropane, bisphenol A, bisphenol F, and alkylene oxide adducts thereof can be used. Among these, alkylene oxide adducts of bisphenol A are preferably used. In addition, as the alkylene oxide, an alkylene oxide having 2 to 8 carbon atoms is preferred, and the number of moles of the alkylene oxide added is preferably 2 to 10 moles, and more preferably 4 to 8 moles.

[0028] As the polybasic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, dimer acid, sebacic acid, undecanedicarboxylic acid, hexahydroterephthalic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid and the like can be used.

[0029] The number average molecular weight of the polyol (a2) having an aromatic ring is preferably 500 to 10,000, more preferably 500 to 5,000. The number average molecular weight of the polyol (a2) having an aromatic ring is a value measured by gel permeation chromatography (GPC).

[0030] The amount of the polyol (a2) having an aromatic ring to be used is preferably 10 to 40% by mass, more preferably 20 to 30% by mass, in the polyol (A).

[0031] The room temperature solid polyester polyol (a3) ​​other than the above (a2) is an essential component for fixing the bubbles, inhibiting the penetration of the adhesive into the fabric, and exhibiting an excellent texture. The room temperature solid polyester polyol means having no fluidity at 25°C.

[0032] The polyester polyol (a3) ​​is preferably at least one selected from the group consisting of a polyester polyol (a3-1) made of diethylene glycol and sebacic acid, a polyester polyol (a3-2) made of 1,3-propylene glycol and sebacic acid, a polyester polyol (a3-3) made of diethylene glycol, neopentyl glycol and phthalic acid, and a polyester polyol (a3-4) made of diethylene glycol and phthalic acid.

[0033] In addition, as for the polyester polyol (a3), in terms of increasing the biomass content of the resin, polyester polyol (a3-1) using diethylene glycol and sebacic acid as raw materials and / or polyester polyol (a3-2) using 1,3-propylene glycol and sebacic acid as raw materials are preferred. It should be noted that as biomass raw materials for the polyester polyol, for example, sebacic acid derived from biomass ("Bio Seb" manufactured by Toyokuni Oil Co., Ltd.), 1,3-propylene glycol derived from biomass ("SUSTERRA Propylene Glycol" manufactured by Dupont Co., Ltd.), diethylene glycol derived from biomass ("Bio DEG" manufactured by India Glycols Co., Ltd.), etc. can be obtained in the form of commercial products.

[0034] In addition, as for the polyester polyol (a3), in terms of obtaining a more excellent feel, the polyester polyol (a3-3) using diethylene glycol, neopentyl glycol and phthalic acid as raw materials and / or the polyester polyol (a3-4) using diethylene glycol and phthalic acid as raw materials are preferred, and the polyester polyol (a3-3) using diethylene glycol, neopentyl glycol and phthalic acid as raw materials is particularly preferred. It should be noted that the diethylene glycol may be petrochemical-derived diethylene glycol or biomass-derived diethylene glycol, and in terms of increasing the biomass content, the diethylene glycol derived from biomass is preferably used.

[0035] The number average molecular weight of the polyester polyol (a3) ​​is preferably 500 to 10,000, and more preferably 800 to 5,000. The number average molecular weight of the polyester polyol (a3) ​​refers to a value measured by gel permeation chromatography (GPC).

[0036] The amount of the polyester polyol (a3) ​​used is preferably 10 to 30% by mass, more preferably 10 to 20% by mass, in the polyol (A).

[0037] The polyol (A) must contain the components (a1) to (a3), but may contain other polyols as necessary. The total content of the components (a1) to (a3) ​​in the polyol (A) is preferably 20% by mass or more, more preferably 50% by mass or more.

[0038] As the other polyols, for example, polyester polyols other than the above (a2) and (a3), polycarbonate polyols other than the above (a1), polyether polyols other than the above (a1), polybutadiene polyols, polyacrylic polyols, etc. can be used. These polyols can be used alone or in combination of two or more.

[0039] Examples of the number average molecular weight of the other polyols include 500 to 100,000. The number average molecular weight of the other polyols refers to a value measured by gel permeation chromatography (GPC).

[0040] As the above-mentioned polyisocyanate (B), for example, aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, polymerized diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, xylylene diisocyanate, phenylene diisocyanate, toluene diisocyanate, and naphthalene diisocyanate; aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate can be used. These polyisocyanates can be used alone or in combination of two or more. Among these, aromatic polyisocyanates are preferred, and diphenylmethane diisocyanate is more preferred, from the perspective of obtaining good adhesion, reactivity, and mechanical properties.

[0041] The urethane prepolymer (i) 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 the condition that the isocyanate groups of the polyisocyanate (B) are in excess relative to the hydroxyl groups of the polyol (A).

[0042] When producing the urethane prepolymer (i), the equivalent ratio (NCO / OH) of the isocyanate group of the polyisocyanate (B) to the hydroxyl group of the polyol (A) is preferably 1.1 to 5.0, more preferably 1.5 to 3.5, from the viewpoint of adhesiveness, texture and mechanical strength.

[0043] The isocyanate group content (hereinafter referred to as "NCO%") of the urethane prepolymer (i) is preferably 1.1 to 5.0% by mass, and more preferably 1.5 to 3.5% by mass, from the viewpoint of adhesion, feel, and mechanical strength. The isocyanate group content of the urethane prepolymer (i) is a value measured by potentiometric titration in accordance with JIS K1603-1:2007.

[0044] The moisture-curable polyurethane hot-melt composition (X) used in the present invention contains the urethane prepolymer (i) as an essential component, but may contain other additives as necessary.

[0045] As for the above-mentioned other additives, as additives other than the polyol composition (Y) described later, for example, silane coupling agents, thixotropy imparting agents, antioxidants, plasticizers, fillers, dyes, pigments, waxes, etc. can be used. These additives can be used alone or in combination of two or more.

[0046] The polyol composition (Y) is mixed with the moisture-curable polyurethane hot-melt composition, whereby the isocyanate group of the urethane prepolymer (i) reacts with the polyol in the polyol composition (Y), thereby appropriately increasing the viscosity, thereby being able to fix the bubbles in the polyurethane foam sheet during water foaming, and also contributing to the flexibility, mechanical strength and durability of the obtained polyurethane foam sheet.

[0047] As the polyol, for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,2-dimethyl-1,3-propylene glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, etc. can be used. These compounds can be used alone or in combination of two or more.

[0048] The content of the polyol in the polyol composition (Y) is preferably 0.1 to 10.0% by mass, more preferably 0.5 to 5.0% by mass.

[0049] In the present invention, in order to obtain excellent texture, the polyol composition (Y) must contain an amine catalyst (y1) having a foaming constant (Kw) of 10 or more. By using the specific amine catalyst (y1), the reaction between the isocyanate group of the urethane prepolymer (i) and water during water foaming can be accelerated, and an excellent texture can be obtained from the perspective of forming large cells and setting the temperature and humidity during water foaming to milder conditions than before.

[0050] In the present invention, the foaming constant (Kw) of the amine catalyst (y1) represents the catalytic activity constant (L 2 / (wq.mol·hr)), specifically, reference can be made to Japanese Patent Application Publication No. 2019-85513, Japanese Patent Application Publication No. 2009-14981, etc.

[0051] As the specific amine catalyst (y1), for example, N,N,N',N''-pentamethyldiethylenetriamine (PMDETA, Kw=159), N,N,N',N'',N''-pentamethylethylenepropylenetriamine (PMEPTA, Kw=21.5), N,N,N',N'',N''-pentamethyldipropylenetetramine (PMDPTA, Kw=11.6), 1,1,4,7,10,10-hexadecene Methyltriethylenetetramine (HMTETA, Kw = 84.8), bis(2-dimethylaminoethyl) ether (DMAEE, Kw = 25.5), N,N,N'-trimethylaminoethylethanolamine (TMAEEA, Kw = 43.4), bis(2-dimethylaminoethyl) ether (BDMEE, Kw = 117), 1,4-diazabicyclo[2.2.2]octane=triethylenediamine (TEDA, Kw = 14.5), etc. These catalysts may be used alone or in combination of two or more.

[0052] In terms of obtaining a better texture, the amine catalyst (y1) is preferably used in combination with the 1,4-diazabicyclo[2.2.2]octane=triethylenediamine and another amine catalyst. In this case, the mass ratio is preferably 1 / 1 to 1 / 10, more preferably 1 / 1 to 1 / 5, in terms of obtaining a better texture.

[0053] The usage-amount of the said amine catalyst (y1) is preferably 1.0-20 mass % in the polyol composition (Y), and more preferably 1.0-10 mass %.

[0054] The polyol composition (Y) may contain other additives in addition to the amine catalyst (y1). Examples of the other additives include catalysts other than (y1), foam stabilizers, flame retardants, antistatic agents, fillers, conductive agents, moisture absorbents, inert gases, silane coupling agents, thixotropy agents, tackifiers, waxes, plasticizers, heat stabilizers, light stabilizers, pigments, anti-hydrolysis agents, etc. These additives may be used alone or in combination of two or more. These additives may be used alone or in combination of two or more.

[0055] The amount of the polyol composition (Y) used is preferably 1.0 to 50 parts by mass, more preferably 1.0 to 35 parts by mass, based on 100 parts by mass of the moisture-curable polyurethane hot-melt resin composition (X).

[0056] Next, the method for producing the polyurethane foam sheet of the present invention will be described.

[0057] The method for producing a polyurethane foam sheet of the present invention comprises the steps of mixing the moisture-curable polyurethane hot-melt resin composition (X) melted by heating at 70 to 150° C. with the polyol composition (Y) to obtain a mixture, applying the mixture in a sheet form on a substrate, and bringing water vapor into contact with the sheet-like mixture to water-foam the mixture.

[0058] Examples of a method for mixing the moisture-curable polyurethane hot-melt resin composition (X) and the polyol composition (Y) include a method using a high-speed mixing head or a disperser.

[0059] Examples of methods for applying the mixture in a sheet form on a substrate such as release paper include methods using a roll coater, spray coater, T-die coater, knife coater, etc. Examples of the thickness of the mixture applied in a sheet form include 50 to 500 μm.

[0060] The obtained sheet-like mixture is brought into contact with water vapor to perform water foaming. The technical term "water foaming" as used in the present invention means that water contained in the water vapor is used as a foaming agent, and the isocyanate group of the above-mentioned urethane prepolymer (i) used in the present invention reacts with the water to generate carbon dioxide, thereby performing foaming.

[0061] As conditions for contact with the water vapor, for example, the temperature of the atmosphere on the surface of the sheet-like mixture is set to, for example, 20 to 120° C., preferably less than 80° C., more preferably 20 to 35° C., the humidity of the atmosphere on the surface of the sheet-like mixture is set to, for example, 50% or more, preferably 60% or more and less than 95%, more preferably 60 to 85%, and the humidification time is set to 0.5 seconds to 10 minutes.

[0062] In addition, as a method for contacting with water vapor, there is a method using a humidifying chamber, a water vapor spray device, etc. that can keep the conditions of the atmosphere temperature, atmosphere humidity and humidification time on the surface of the above-mentioned mixture constant, and more preferably, when using a device that produces saturated water vapor, the water vapor is not easy to cool and form water droplets in the manufacturing pipeline circulation, so it is preferred. In addition, in order to further improve the thickness accuracy of the polyurethane foam sheet, it is preferably after the humidification treatment and a compaction belt press, a clamping roller, a flat press, etc. are used.

[0063] After contacting with the water vapor, the mixture may be aged for 0.5 to 3 days at a temperature of 20 to 80° C. and a relative humidity of 50 to 90%.

[0064] As described above, according to the method for producing a polyurethane foam sheet of the present invention, a polyurethane foam sheet having a good hand feel can be obtained. In addition, the polyurethane foam sheet has excellent adhesiveness and can be particularly suitably used as an adhesive layer of synthetic leather.

[0065] Next, the method for producing the synthetic leather of the present invention will be described.

[0066] The synthetic leather may include a synthetic leather having at least a base material, an adhesive layer, and a surface layer, and the adhesive layer is obtained by the method for producing a polyurethane foam sheet.

[0067] As the above-mentioned substrate, for example, fiber substrates such as non-woven fabrics, woven fabrics, and knitted fabrics 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; materials formed by impregnating the above-mentioned non-woven fabrics with resins such as polyurethane resins; materials formed by further providing a porous layer on the above-mentioned non-woven fabrics; resin substrates such as thermoplastic urethane (TPU), as well as genuine leather, split leather, and the like.

[0068] As the material forming the above-mentioned epidermis layer, for example, water-based urethane resin, solvent-based urethane resin, solvent-free urethane resin, water-based acrylic resin, solvent-based acrylic resin, solvent-free acrylic resin, solvent-based silicone resin, water-based silicone resin, solvent-free silicone resin, vinyl chloride resin, thermoplastic polyurethane resin, thermoplastic polyester resin, thermoplastic amide resin, thermoplastic polyolefin resin, etc. can be used. These materials can be used alone or in combination of two or more.

[0069] As a method for producing the above-mentioned synthetic leather, for example, the following method can be cited: a mixture obtained by mixing the above-mentioned moisture-curable polyurethane hot-melt resin composition (X) and the above-mentioned polyol composition (Y) is applied in a sheet-like manner on a surface layer formed on a release paper, water vapor is brought into contact with the above-mentioned mixture in the sheet-like form to water-foam the above-mentioned mixture as described above, and the obtained foamed sheet is bonded to the adhesive layer and the above-mentioned substrate.

[0070] A surface treatment layer (top coating layer) may be provided on the above-mentioned skin layer as required.

[0071] Example

[0072] Hereinafter, the present invention will be described in more detail using examples.

[0073] [Synthesis example 1]

[0074] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Co., Ltd., number average molecular weight: 2,000), 20 parts by mass of a polyether polyol having an aromatic ring (a polyether polyol which is a 6-mol adduct of propylene oxide to bisphenol A, number average molecular weight: 508), and 10 parts by mass of a biomass-derived polyester polyol (a reaction product of biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Co., Ltd., number average molecular weight: 2,000) and biomass-derived diethylene glycol ("BioDEG" manufactured by India Glycols Co., Ltd., number average molecular weight: 2,000) were placed, and dried under reduced pressure at 110° C. to dehydrate the mixture until the moisture content became 0.05% by mass or less. Next, after cooling to 60°C, 33 parts by mass of diphenylmethane diisocyanate was added, the temperature was raised to 110°C, and the reaction was carried out for 2 hours until the isocyanate group content reached a constant, thereby obtaining a urethane prepolymer (i-1) having an NCO% of 3.32% by mass and a biomass degree of 60.2% by mass, and preparing a moisture-curable polyurethane hot-melt resin composition (X1).

[0075] [Synthesis example 2]

[0076] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Co., Ltd., number average molecular weight: 2,000), 20 parts by mass of a polyester polyol having an aromatic ring (a reaction product of 6 mol of propylene oxide adduct of bisphenol A, isophthalic acid and biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Co., Ltd., number average molecular weight: 2,000), and 10 parts by mass of a biomass-derived polyester polyol (a reaction product of biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Co., Ltd.) and biomass-derived diethylene glycol ("Bio DEG" manufactured by India Glycols Co., Ltd., number average molecular weight: 2,000) were charged and dried under reduced pressure at 110° C. to dehydrate the mixture until the moisture content became 0.05% by mass or less. Next, after cooling to 60°C, 23.5 parts by mass of diphenylmethane diisocyanate was added, the temperature was raised to 110°C, and the reaction was carried out for 2 hours until the isocyanate group content reached a constant, thereby obtaining a urethane prepolymer (i-2) having an NCO% of 3.33% by mass and a biomass degree of 65.4% by mass, and preparing a moisture-curable polyurethane hot-melt resin composition (X2).

[0077] [Synthesis example 3]

[0078] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Co., Ltd.), 20 parts by mass of a polyester polyol having an aromatic ring (a reaction product of 6 mol of propylene oxide adduct of bisphenol A, isophthalic acid and biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Co., Ltd., number average molecular weight: 2,000), and 10 parts by mass of a biomass-derived polyester polyol (a reaction product of biomass-derived 1,3-propanediol ("SUSTERRA Propylene Glycol" manufactured by Dupont Co., Ltd.) and biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Co., Ltd., number average molecular weight: 2,000) were charged and dried under reduced pressure at 110° C. to dehydrate the mixture until the moisture content became 0.05% by mass or less. Next, after cooling to 60°C, 23.5 parts by mass of diphenylmethane diisocyanate was added, the temperature was raised to 110°C, and the reaction was carried out for 2 hours until the isocyanate group content reached a constant, thereby obtaining a urethane prepolymer (i-3) with an NCO% of 3.33% by mass and a biomass degree of 65.4% by mass, and preparing a moisture-curable polyurethane hot-melt resin composition (X3).

[0079] [Synthesis Example 4]

[0080] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Co., Ltd., number average molecular weight: 2,000), 20 parts by mass of a polyester polyol having an aromatic ring (a reaction product of 6 mol of propylene oxide adduct of bisphenol A, isophthalic acid and biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Co., Ltd., number average molecular weight: 2,000), and 10 parts by mass of a biomass-derived polyester polyol (a reaction product of biomass-derived diethylene glycol ("Bio DEG" manufactured by India Glycols Co., Ltd.), neopentyl glycol and phthalic acid, number average molecular weight: 1,000) were charged and dried under reduced pressure at 110° C. to dehydrate the mixture until the moisture content became 0.05% by mass or less. Next, after cooling to 60°C, 26.5 parts by mass of diphenylmethane diisocyanate was added, the temperature was raised to 110°C, and the reaction was carried out for 2 hours until the isocyanate group content reached a constant, thereby obtaining a urethane prepolymer (i-4) with an NCO% of 3.39% by mass and a biomass degree of 63.9% by mass, and preparing a moisture-curable polyurethane hot-melt resin composition (X4).

[0081] [Comparative Synthesis Example 1]

[0082] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 100 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Co., Ltd., number average molecular weight: 2,000) was added, and the mixture was dried under reduced pressure at 110°C to dehydrate the mixture until the moisture content became 0.05% by mass or less. Next, after cooling to 60°C, 25.0 parts by mass of diphenylmethane diisocyanate was added, the temperature was raised to 110°C, and the mixture was reacted for 2 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (iR-1) having an NCO% of 3.36% by mass and a biomass degree of 80% by mass, and a moisture-curable polyurethane hot-melt resin composition (XR1) was prepared.

[0083] [Comparative Synthesis Example 2]

[0084] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Co., Ltd., number average molecular weight: 2,000) and 30 parts by mass of biomass-derived polyester polyol (a reaction product of biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Co., Ltd.) and biomass-derived diethylene glycol ("Bio DEG" manufactured by India Glycols Co., Ltd., number average molecular weight: 2,000) were placed, and dried under reduced pressure at 110° C. to dehydrate the mixture until the moisture content became 0.05% by mass or less. Next, after cooling to 60°C, 25.0 parts by weight of diphenylmethane diisocyanate was added, the temperature was raised to 110°C, and the reaction was carried out for 2 hours until the isocyanate group content reached a constant, thereby obtaining a urethane prepolymer (iR-2) having an NCO% of 3.36% by weight and a biomass degree of 80% by weight, and preparing a moisture-curable polyurethane hot-melt resin composition (XR2).

[0085] [Comparative Synthesis Example 3]

[0086] In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser, 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Co., Ltd., number average molecular weight: 2,000) and 30 parts by mass of a polyether polyol having an aromatic ring (a polyether polyol which is a 6-mol adduct of propylene oxide to bisphenol A, number average molecular weight: 508) were added, and the mixture was dried under reduced pressure at 110°C to dehydrate the mixture until the moisture content became 0.05% by mass or less. Next, after cooling to 60°C, 25.0 parts by mass of diphenylmethane diisocyanate was added, the temperature was raised to 110°C, and the mixture was reacted for 2 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (iR-3) having an NCO% of 3.36% by mass and a biomass degree of 56% by mass, and a moisture-curable polyurethane hot-melt resin composition (XR3) was prepared.

[0087] [Method for measuring number average molecular weight]

[0088] The number average molecular weight of the polyol used in Synthesis Examples and the like refers to a value measured by gel permeation chromatography (GPC) under the following conditions.

[0089] Measuring device: High-speed GPC device (Tosoh Corporation "HLC-8220GPC")

[0090] Column: The following columns manufactured by Tosoh Corporation were connected in series and used.

[0091] "TSKgel G5000" (7.8mm I.D. × 30cm) × 1 piece

[0092] "TSKgel G4000" (7.8mm I.D. × 30cm) × 1 piece

[0093] "TSKgel G3000" (7.8mm I.D. × 30cm) × 1 piece

[0094] "TSKgel G2000" (7.8mm I.D. × 30cm) × 1 piece

[0095] Detector: RI (differential refractometer)

[0096] Column temperature: 40°C

[0097] Eluent: Tetrahydrofuran (THF)

[0098] Flow rate: 1.0mL / min

[0099] Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4 mass %)

[0100] Standard samples: The following standard polystyrene was used to prepare a calibration curve.

[0101] (Standard Polystyrene)

[0102] "TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation

[0103] "TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation

[0104] "TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation

[0105] "TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation

[0106] "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation

[0107] "TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation

[0108] "TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation

[0109] "TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation

[0110] "TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation

[0111] "TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation

[0112] "TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation

[0113] "TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation

[0114] "TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation

[0115] "TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

[0116] [Preparation Example 1] <Method for preparing epidermal film>

[0117] A pigment (DILAC BLACK HS6001 (DIC Corporation)) and a defoamer (TEGO Foamex 800 (EVONIK Corporation)) were mixed with HYDRAN WLS 230 (DIC Corporation) as a water-based urethane resin for the surface layer of synthetic leather, and 0.3 parts by mass were added. The mixture was coated with a comma coater at a coating amount of 100 g / m 2 The obtained mixture was uniformly applied on a release paper ("EV130TPD" manufactured by Lintec Corporation) in a wet manner, dried at 70°C for 2 minutes, and then dried at 120°C for 2 minutes to prepare a surface film having a thickness of 30 μm.

[0118] [Example 1] <Method for producing polyurethane foam sheet>

[0119] The moisture-curable polyurethane hot-melt resin composition (X1) obtained in Synthesis Example 1 was heated to 120° C. and melted, and 3.3 parts by mass of a polyol composition was mixed with 100 parts by mass of a urethane prepolymer (i-1) at 6,000 rpm using a homodispersor for 20 seconds. The polyol composition was prepared by mixing 2.0 parts by mass of 1,4-butanediol (hereinafter, abbreviated as “14BG”), 0.15 parts by mass of PMDETA, and 0.15 parts by mass of TEDA. The film was prepared by mixing 1.0 parts by weight of a silicone foam stabilizer ("SF-2962" manufactured by Dow Corning Corporation, hereinafter referred to as "SF2962") and then immediately applying it on a release paper ("DK-100" manufactured by LINTEC Co., Ltd.) with a thickness of 200 μm using an applicator, laminating a 50 μm thick polyethylene film, humidifying with water vapor for 1 minute at 30°C and 80% humidity, and leaving it at 23°C and 65% humidity for 1 day to obtain a polyurethane foam sheet.

[0120] <Production of synthetic leather>

[0121] The moisture-curable polyurethane hot-melt resin composition (X1) obtained in Synthesis Example 1 was heated to 120°C and melted, and 3.3 parts by mass of a polyol composition prepared by mixing 2.0 parts by mass of 1,4-butanediol (hereinafter abbreviated as "14BG"), 0.15 parts by mass of PMDETA, 0.15 parts by mass of TEDA, and 1.0 parts by mass of a silicone foam stabilizer ("SF-2962" manufactured by Dow Corning Corporation, hereinafter abbreviated as "SF2962") with respect to 100 parts by mass of the urethane prepolymer (i-1) was stirred and mixed at 6,000 rpm for 20 seconds using a homodispersor. Immediately thereafter, the composition was applied onto the surface film using an applicator to a thickness of 200 μm, and a rayon raised cloth was laminated thereto. The composition was then humidified with water vapor for 1 minute in an atmosphere of 30°C and 80% humidity, and allowed to stand for 1 day in an environment of temperature 23°C and 65% humidity, thereby obtaining a synthetic leather.

[0122] [Example 2]

[0123] A polyurethane foam sheet and synthetic leather were obtained in the same manner as in Example 1 except that the type of the moisture-curable polyurethane hot-melt resin composition (X1) was changed to the moisture-curable polyurethane hot-melt resin composition (X2).

[0124] [Example 3]

[0125] A polyurethane foam sheet and a synthetic leather were obtained in the same manner as in Example 1 except that the type of the moisture-curable polyurethane hot-melt resin composition (X1) was changed to the moisture-curable polyurethane hot-melt resin composition (X3).

[0126] [Example 4]

[0127] A polyurethane foam sheet and a synthetic leather were obtained in the same manner as in Example 1 except that the type of the moisture-curable polyurethane hot-melt resin composition (X1) was changed to the moisture-curable polyurethane hot-melt resin composition (X4).

[0128] [Example 5]

[0129] A polyurethane foam sheet and synthetic leather were obtained in the same manner as in Example 2 except that HMTETA was used instead of PMDETA.

[0130] [Example 6]

[0131] A polyurethane foam sheet and synthetic leather were obtained in the same manner as in Example 2 except that PMDPTA was used instead of PMDETA.

[0132] [Comparative Example 1] <Method for producing polyurethane foam sheet>

[0133] The moisture-curable polyurethane hot-melt resin composition (XR1) obtained in Comparative Synthesis Example 1 was heated to 120°C and melted, and a polyol composition prepared by mixing 0.5 parts by mass of 14BG, 0.10 parts by mass of N,N-dimethylcyclohexylamine (Kw=8.3, hereinafter abbreviated as "DMCHA"), and 0.1 parts by mass of SF-2962 was stirred and mixed at 6,000 rpm for 20 seconds with a homodispersor, and then immediately applied to a release paper ("DK-100" manufactured by LINTEC Co., Ltd.) with a thickness of 200 μm using an applicator, and a 50 μm thick polyethylene film was attached thereto, and then humidified with water vapor for 1 minute in an atmosphere of 30°C and 80% humidity, and allowed to stand for 1 day in an environment of temperature 23°C and 65% humidity to obtain a polyurethane foam sheet.

[0134] <Production of synthetic leather>

[0135] The moisture-curable polyurethane hot-melt resin composition (XR1) obtained in Comparative Synthesis Example 1 was heated to 120°C and melted, and a polyol composition prepared by mixing 0.5 parts by mass of 14BG, 0.10 parts by mass of N,N-dimethylcyclohexylamine (Kw=8.3, hereinafter abbreviated as "DMCHA"), and 0.1 parts by mass of SF-2962 was stirred and mixed at 6,000 rpm for 20 seconds with a homogenizer. Then, the composition was immediately applied to the above-mentioned epidermal film with a thickness of 200 μm using an applicator, and after bonding a rayon raised cloth, it was humidified with water vapor for 1 minute in an atmosphere of 30°C and 80% humidity, and allowed to stand for 1 day in an environment of temperature 23°C and 65% humidity to obtain synthetic leather.

[0136] [Comparative Example 2]

[0137] A polyurethane foam sheet and a synthetic leather were obtained in the same manner as in Comparative Example 1 except that the type of the moisture-curable polyurethane hot-melt resin composition (XR1) was changed to the moisture-curable polyurethane hot-melt resin composition (XR2).

[0138] [Comparative Example 3] <Method for producing polyurethane foam sheet>

[0139] The moisture-curable polyurethane hot-melt resin composition (XR3) obtained in Comparative Synthesis Example 3 was heated to 120°C and melted, and then immediately applied to a release paper ("DK-100" manufactured by LINTEC Co., Ltd.) with a thickness of 200 μm using an applicator, and then adhered to a polyethylene film with a thickness of 50 μm. The film was humidified with water vapor for 1 minute in an atmosphere of 30°C and 80% humidity, and allowed to stand for 1 day in an environment of temperature 23°C and 65% humidity to obtain a polyurethane foam sheet.

[0140] <Production of synthetic leather>

[0141] The moisture-curable polyurethane hot-melt resin composition (XR3) obtained in Comparative Synthesis Example 3 was heated to 120°C and melted, and then immediately applied to the above-mentioned epidermal film with a thickness of 200 μm using an applicator. After bonding a rayon raised cloth, it was humidified with water vapor for 1 minute in an atmosphere of 30°C and 80% humidity, and allowed to stand for 1 day in an environment of temperature 23°C and 65% humidity to obtain synthetic leather.

[0142] [Evaluation method of foam retention]

[0143] Each polyurethane foam sheet obtained in the examples and comparative examples was cured by moisture treatment and then left to stand for 30 minutes at an ambient temperature of 23° C. and a relative humidity of 65%. A load of 1 kg was applied to an area of ​​5 cm×5 cm square for 2 hours, and the crushability of the foam against stress after the load was removed was evaluated by visual inspection as follows.

[0144] A: A state in which cells of the foam are maintained and the appearance does not change.

[0145] B: The cells of the foam are partially crushed and the appearance is changed.

[0146] C: The cells of the foam are entirely crushed and the appearance is changed.

[0147] [Evaluation method of hand feel]

[0148] The flexibility of each of the synthetic leathers obtained in Examples and Comparative Examples when bent by hand was evaluated as follows.

[0149] “1”: Very soft.

[0150] “2”: A bit hard.

[0151] “3”: Hard.

[0152] [Table 1]

[0153]

[0154] [Table 2]

[0155]

[0156] In all of Examples 1 to 6 as the production method of the present invention, a polyurethane foam sheet having a high biomass degree, excellent foam retention, and excellent texture was obtained.

[0157] On the other hand, both Comparative Examples 1 and 2 are embodiments using a polyol (A) and a polyol composition (Y) other than those specified in the present invention, and the foam retention and texture are poor.

[0158] Comparative Example 3 is an embodiment in which a polyol (A) other than that specified in the present invention is used and the polyol composition (Y) is not used, and the foam retention and texture are significantly poor.

Claims

1. A method for producing a polyurethane foam sheet, characterized in that: A moisture-curable polyurethane hot-melt resin composition (X) containing a urethane prepolymer (i) which is a reaction product of a polyol (A) and a polyisocyanate (B) is mixed with a polyol composition (Y) to obtain a mixture, the mixture is applied in a sheet form on a substrate, and the mixture in the sheet form is contacted with water vapor to water-foam the mixture, The polyol (A) contains: Polytetramethylene glycol or polycarbonate polyol (a1) derived from biomass, a polyol (a2) having an aromatic ring, and A polyester polyol (a3) ​​other than the above (a2) that is solid at room temperature, The polyol composition (Y) contains an amine catalyst (y1) having a foaming constant Kw of 10 or more.

2. The method for producing a polyurethane foam sheet according to claim 1, wherein: The amine catalyst (y1) is used together with 1,4-diazabicyclo[2.2.2]octane=triethylenediamine and other amine catalysts.

3. The method for producing a polyurethane foam sheet according to claim 1, wherein: The polycarbonate polyol (a1) is made from a diol having 1 to 10 carbon atoms and derived from biomass.

4. The method for producing a polyurethane foam sheet according to claim 1, wherein: The polyol (a2) having an aromatic ring is a polyether polyol which is an alkylene oxide adduct of bisphenol A, or a polyester polyol using an alkylene oxide adduct of bisphenol A as a raw material.

5. The method for producing a polyurethane foam sheet according to claim 1, wherein: The polyester polyol (a3) ​​is one or more selected from the group consisting of a polyester polyol (a3-1) made of diethylene glycol and sebacic acid, a polyester polyol (a3-2) made of 1,3-propylene glycol and sebacic acid, a polyester polyol (a3-3) made of diethylene glycol, neopentyl glycol and phthalic acid, and a polyester polyol (a3-4) made of diethylene glycol and phthalic acid.

6. The method for producing a polyurethane foam sheet according to claim 1, wherein: The temperature when in contact with the water vapor is less than 80° C., and the humidity is less than 95%.

7. A method for producing synthetic leather, characterized in that: The present invention relates to a method for producing a synthetic leather having at least a substrate, an adhesive layer and a surface layer, wherein the adhesive layer is obtained by the method for producing a polyurethane foam sheet according to claim 1.

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